epert system literature review

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CHAPTER II

LITERATURE REVIEW

2.1 Artificial intelligence

Artificial intelligence is a branch of computer science that makes machine

(computer) can do a job as good as human [1].

To perform an artificial intelligence application, there are two main parts needed

(Figure 1.1), those are [1]:

a. Knowledge Base, containing facts, theories, ideas and relationships between

each other.

b. Inference Engine, that is an ability to make a conclusion based on

experience.

Figure 2.1 Basic Concept of an Artificial Intelligence [1]

Artificial intelligence technology have been learned in several areas such as

Expert Systems, Natural Language Processing, Speech Recognition, Robotics and

Sensory Systems, Computer Vision, Intelligent Computer-aided Instruction and

Games Playing.

Knowledge

base

Inference

Engine

Input:

problem,

question,

etc

Output:

answer,

solution,

etc

Computer

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2.2 Expert System

Expert system is a computer programs that adopt analytical skill from an expert

in a particular area of knowledge [2]. An expert system is a program of artificial

intelligence that combines knowledge base with inference engine. It is part of high -

level specialized software or high-level programming language, which is trying to

duplicate the functionality of an expert in a particular field of expertise. This program

acts as a smart consultant or advisor in an specific environment of expertise, as a

result of knowledge that has been gathered from several experts.Thus even a

nonexpert can use the expert system to solve various problems he faced, and for an

expert, the expert system can be used as a tool to support his activities that work as an

experienced assistant. General -purpose problem solver ( GPS ) is the first expert

system created that developed by Newl and Simon. Until now there are many expert

systems that have been created such as MYCIN , DENDRAL , XCON & XSEL ,

SOPHIE , Prospector , FOLIO , DELTA , etc. [1].

Table 2.1 Expert System Applications [1]

Expert System Function

MYCIN For medical diagnosis

DENDRAL For molecular structure identification

XCON & XSEL For corporation computer system configuration

SOPHIE For the selection of hazard evaluation procedures

Prospector Used in geology to help searching and finding deposits

FOLIO Provides decision for a manager in terms of the stock

brokerage and investment

DELTA Maintenance of diesel electric locomotives

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Table 2.2 Comparison of Conventional System and Expert System [1]

Conventional System Expert System

Information and its processing are

usually combined in one sequential

program.

Knowledge base is clearly separated

from the processing (inference)

mechanism (i.e., knowledge rules are

separated from the control).

Program does not make mistakes

(programmers or users do).

Program may make mistakes.

Do not (usually) explain why input

data are needed or how conclusions

are drawn.

Explanation is a part of most Expert

Systems.

Require all input data. May not

function properly with missing data

unless planned for.

Do not require all initial facts.

Typically can arrive at reasonable

conclusions with missing facts.

Changes in the program are tedious Changes in the rules are easy to make.

The system operates only when it is

completed.

The system can operate with only a

few rules (as the first prototype).

2.2.1 Characteristics of Expert System

An expert system is usually designed to have the following general characteristic

[1]:

1. Limited to a particular domain.

2. Can provides reasoning for some uncertain data.

3. Can put forward a series of that can be understood.

4. Based on rules.

5. Developed to be developed gradually.

6. The output of the system is a recommendation.

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2.2.2 General Categories of Expert System

Here are the general categories of expert system [1] :

1. Interpretation, is to make conclusion or description from a set raw of data.

2. Prediction, is to project the consequences that caused of some situations.

3. Diagnosis, is to determine the cause of malfunctions in the situation that based

on observed symptoms.

4. Design used to determine the configuration of system components that

matched with specific performance goals that meet certain constraints.

5. Planning, is planning a series of actions that can achieve a number of goals

with specific initial conditions.

6. Debugging and Repair, is determining and menginterpresentasikan ways to

cope with malfunctions.

7. Instruction, is detecting and correcting deficiencies in the understanding of the

subject domain.

8. Control is set behavior of a complex environment.

9. Selection , is to identify the best option from a set of possibilities.

10. Simulation , is modeling the interactions between system components.

11. Monitoring , is to compare the observations with the expected conditions.

2.2.3 Advantages and Disadvantages of Expert System

Advantages of Expert System [1]:

1. Allows nonexpert to do the work of expert.

2. The proccess can be repeated automatically.

3. Stores the knowledges and expertise of the experts.

4. Improves the quality by giving consistent advise and decreasing error.

5. Improves outcomes and productivity, because expert system can work faster

than humans.

6. Has the ability to work with incomplete and urcertain information.

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7. Has the ability to access the knowledge.

8. Increases the capability of problem solving.

9. Saves times in making decision.

Disadvantages of Expert System [1] :

1. Need much money to create, maintain and develop the system.

2. Hard to developed, because of the limit of experts in some domain.

3. Expert systems are not 100% correct, because a person who involved in

making of expert systems can be wrong. Therefore, it needs to be re-examined

carefully before launching.

4. Expertise is hard to be extracted from a human.

5. Approach among an expert and others in solving a problem could be different,

although both of them are true.

6. Its hard for an experts to abstract and explain their steps in solving problems.

7. Expert system can only works well in a narrow field of expertise.

8. The terms and jargon used by experts to express facts is usually limited and

not easy to be understood by others.

9. Knowledge transfer can be subjective and refraction.

2.2.4 Structure of Expert System

There are two main parts of an Expert System, they are [1]:

1. Development environment, which is the part that used to incorporate

expertsknowledge into an expert system environment.

2. Environmental consultation, which is the part that used by nonexpert users to

gain knowledge.

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Figure 2.2 Structure of Expert System [1]

An expert system consists of the following components:

1. User Interface

User interface is a mechanism that used by users to communicate with the

system. The user interface receives information from user and convert it into a

form that can be received by the system. Moreover interface receives

information from the system and presenting it in a form that can be

understood by the user. (Mcleod, 1995).

2. Knowledge Base

According to Sri Hartati and Sari Iswanti (2008) knowledge base is a

collection of a particular field of knowledge at the level of experts in a

particular format. The knowledge gained from the accumulated knowledge of

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experts and sources - other knowledge sources. Dynamic knowledge base can

evolve over time.

There are two forms of knowledge base approach [1]:

(rule-based reasoning)

In the rule-based reasoning, knowledge is represented using IF-THEN

rules of the form. This form is used when we have a number of expert

knowledge on a particular issue, and the expert can solve the problem

sequentially. In addition, this form is also used when needed

explanation of the trail (the steps) the achievement of a solution.

(case-based reasoning)

In case-based reasoning, knowledge base will contain solutions that

have been achieved previously, then lowered a solution to the current

situation (the facts). This form is used when the user wants to know

more on the cases are almost the same (similar). In addition, this form

is used when we have had a number of situations or specific cases in

the knowledge base.

3. Knowledge acquisition

The acquisition of knowledge is the accumulation, transfer and transformation

of expertise in solving the problem of the source of knowledge into a

computer program. In this stage the knowledge engineer trying to absorb

knowledge to transfer to the knowledge base. The knowledge obtained from

experts, equipped with books, databases, research reports and user experience

(Arhami, 2005).

According to Turban (1988), there are three main methods in the

acquisition of knowledge, namely

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Interview

Interview is the acquisition method which most widely used. This

method involves direct discussions with experts in an interview.

Protocol analysis

In this method the expert is asked to do a job and revealing his thought

process by using words. The work was recorded, written and analyzed.

Observations on the work of experts

In this method the work is done in a specific field experts observed.

4. Inference engines

Inference engine is used to make inferences by deciding which rules filled

with objects or facts , filled sort of priority rules , and executed in accordance

with the priority rules ( Giarratano & Riley, 1998) .

5. Working Memory

Working memory storing a fact which would then be used by the rule

(Giarratano & Riley, 1998). The existence of the facts in the working memory

will trigger the execution of the rules with the fulfillment of the premise of the

rule.

6. Explanation facilities

Facilities explanation serves to explain the reasoning of the system to the user

(Giarratano & Riley 1998). In addition to providing reasoning, this section

can also explain the action or recommendation of an expert system (Marimin,

2005).

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7. Knowledge Improvement

Experts have the ability to analyze and improve their performance as well

as the ability to learn from its performance. These capabilities are

important in computerized learning , so the program will be able to analyze

the causes of success and failure that caused also evaluate whether the

knowledges are still suitable for use in the future ( Arhami , 2005).

2.3 (Certainty Factor)

Certainty Factor (CF) was introduced by Shortliffe Buchanan dalam MYCIN

manufacture. Certainty factor (CF) is a clinical parameter values given MYCIN to

show how much confidence.

The basic equation of certainty factors [3]:

CF(H,E) = MB(H,E) MD(H,E)

Description:

CF (H, E): certainty factor of a hypothesis H which is affected by symptoms

(evidence) E. CF value ranges from -1 to 1. A value of -1 indicates an absolute

distrust while the absolute value of 1 indicates absolute trust.

MB (H, E): the size of the increase in confidence (measure of Increased belief) to

hypothesis H is affected by the symptoms of E. MD (H, E): the size of the increase

distrust (Increased measure of disbelief) the hypothesis H that are affected by the

symptoms of E.

An expert system rules often have more than one and consists of several

premises connected with AND or OR. Knowledge of the premise can also uncertain,

this is because the value (value) provided by the CF patient when answering

questions above premise systems (symptoms) which can also be experienced by the

patient or of the value of the CF hypothesis.

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CF equation for some rules that lead to the same hypothesis can be written as

follows [3]

CF(R1) + CF(R2) [CF(R1) * CF(R2)]; Value CF(R1) and CF(R2) > 0

CF(H) CF(R1) + CF(R2) + [CF(R1) * CF(R2)]; Value CF(R1) and CF(R2) < 0

There are 2 certainty factor value, namely:

Value rule certainty factor whose value is attached to a rule specified and the

value provided by the experts.

Certainty factor value given by the user to represent the degree of certainty /

confidence in the premise (eg, symptoms, conditions, characteristics)

experienced by users.

2.3.1 Advantages and Disadvantages of Certainty Factor

Advantages of Certainty Factor method [3]:

1. This method is suitable for use in an expert system to measure something for

sure.

2. Calculations using this method only two data can be processing in a single try so

the accurate data can be maintained.

Disadvantages of Certainty Factor method [3]:

1. The general ideas of modeling human uncertainty by using numerical

methods certainty factors are usually debated. Some people would

CF (RR1) + CF (R2)

1-min[|CF(R1)|,|CF(R2)|]

; CF(R1) Value and CF (R2) Value has

opposite sign

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dispute the notion that the equation for certainty factors above methods

have the truth.

2. This method can only process the certainty only two data. It needs to be

done several times for processing data which has more than two datas.

3. CF values given are subjective because every expert assessment may

vary depending on the knowledge and experience of experts.

2.4 UML (Unified Modeling Language)

UML stands for Unified Modeling Language is a set of modeling conventions

used to define or describe a software system in terms of objects. (Whitten, 2004,

P430).

UML can also mean a standard graphic language used for modeling object-based

software. UML first developed in the 1990s with collaboration between James

Rumbaugh, Grady Booch and Ivar Jacobson, who each have developed their own

notation in the early 1990s. (Lethbride and Leganiere, 2002, p151)

UML defines many types such as use case diagrams, class diagrams, object

diagrams, statechart diagram, activity diagram, sequence diagrams, and so on. But not

all of them must be used, adapted to the selected diagram kebutuhan.Pada this study

used a use case, activity diagrams and UML class diagrams as her.

2.4.1 Use Case Diagram

Use case diagram is a diagram which illustrates the interaction between systems

with external systems and users. In other words, describe who will use the system and

in what way the user expects to interact with systems (Whitten et al. 2004). Table 2.3

shows the basic components in a use case diagram.

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Table 2.3 Basic Components of Use Case Diagram (Munawar, 2005)

Component Components Name Information

Actor A role that can be played by users

in their interaction with the system

Use Case A series of scenarios were

combined together by users

general purpose

(stereotype) Showed that a use case is part of

another use case.

(stereotype) Used to create a new use case by

adding steps to the existing use

case.

2.4.2 Class Diagram

Class diagram is a diagram which shows the object classes that make up a

system and also the relationship between the classes (Whitten et al. 2004). Class

diagram is a design tool that helps developers get the system structure before writing

program code, to help ensure that the system is the best design (Sholiq, 2006).

Class notation consists of a class name that is located at the very top and

optionally also be regarded as a stereotype. The middle section is used to declare

attributes while the bottom is used to declare the operation.

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2.4.3 Activity Diagram

Activity diagram is a diagram that can be used to represent the flow of a business

process, the steps of a use case or logic ari behavior of an object graphically (Whitten

et al. 2004).

Activity diagrams are constructed from a limited number of shapes, connected

with arrows. The most important shape types:

Rounded rectangles represent actions.

Diamonds represent decisions.

Bars represent the start (split) or end (join) of concurrent activities.

A black circle represents the start (initial state) of the workflow.

An encircled black circle represents the end (final state).

2.5 PHP

PHP was created by Rasmus Lerdorf in 1995 using the name of the PHP/FI

which stands for Personal Home Page / Forms Interpreter. But in its development, in

1997 Andi Gutmans and Zeev Suraski rewrite of PHP which then until now known as

stands for Hypertext Preprocessor said. PHP is classified as open source software

that under the rules set out general purpose licenses (GPL) [4].

PHP is classified into a server-based programming language ( server side

scripting ) that means all PHP scripts placed on the server and translated by the web

server first, then the translation is sent to the client browser. This is in contrast with

JavaScript. JavaScript program code must be downloaded on the client computer

first, then translated by the internet browser. Therefore, the JavaScript program code

always appears on the web page in question, if it is done to the file storage web.

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Technologically, PHP programming language has similarities with the ASP (Active

Server Page), Cold Fusion, JSP ( Java Server Pages ) or Perl (Suprianto, 2008).

There are many advantages of PHP. This programming language can run on a

wide variety of operating systems such as Windows , Linux and Mac OS. In addition

to Apache, PHP also supports several other web servers such as Microsoft IIS,

Caudium, PWS, etc (Suprianto, 2008).

PHP can utilize database to generate dynamic web pages. Database management

systems that often used in PHP are Microsoft Access, Interbase, dBase, PostgresSQL

etc. In its development, now PHP version 5 supports all of the latest MySQL

extensions, web development services with SOAP and REST, and hundreds of other

improvement compared with the versions previously. In addition to the advantages

that have been described , PHP also has other advantages as open source that can be

downloaded for free ( Suprianto, 2008).

In PHP , a variable can be declared as a place for a single value. While array is a

place for more than one values . An array consists of a number of elements that each

number has a value of data stored in the array element and a key or index, which the

element can be referenced. Normally , an integer is an index. Basically, array is zero

base, it means that the first element in the array has index zero . However, the index

can also be a string.

There are three types of arrays (Suprianto, 2008), those are:

1. Numeric arrays - Array with numeric ID.

2. Associate array - array where each ID key is associated with a value.

3. Multidimensional array array that store one or more array.

2.5.1 PHP Function

The following are some function that used in PHP programming language:

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a. PHP Echo Statement

Echo is a language construct, and can be used with or without parentheses:

echo or echo(). The following example shows how to display different strings

with the echo command (also notice that the strings can contain HTML

markup):

Example:

b. PHP Conditional Statements

Very often when you write code, you want to perform different actions for

different decisions. You can use conditional statements in your code to do

this. In PHP we have the following conditional statements:

if statement - executes some code only if a specified condition is true

if...else statement - executes some code if a condition is true and

another code if the condition is false

if...elseif....else statement - selects one of several blocks of code to be

executed

1. PHP - The if Statement

The if statement is used to execute some code only if a specified

condition is true.

Syntax:

if (condition)

{

code to be executed if condition is true;

}

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2. PHP - The if...else Statement

Use the if....else statement to execute some code if a condition is true

and another code if the condition is false.

Syntax:

if (condition)

{


}

else

{

code to be executed if condition is false;

}

3. PHP - The if...elseif....else Statement

Use the if....elseif...else statement to select one of several blocks of

code to be executed.

Syntax:

if (condition)

{


}

elseif (condition)

{


}

else

{

code to be executed if condition is false;

}

c. Php Switch Statement

Use the switch statement to select one of many blocks of code to be executed.

Syntax:

switch (n)

{

case label1:

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code to be executed if n=label1;

break;

case label2:

code to be executed if n=label2;

break;

...

default:

code to be executed if n is different from all labels;

}

d. PHP Loops

Often when you write code, you want the same block of code to run over and

over again in a row. Instead of adding several almost equal code-lines in a

script, we can use loops to perform a task like this.In PHP, we have the

following looping statements:

while - loops through a block of code as long as the specified

condition is true

do...while - loops through a block of code once, and then repeats the

loop as long as the specified condition is true

for - loops through a block of code a specified number of times

foreach - loops through a block of code for each element in an array

1. The PHP While Loop

The while loop executes a block of code as long as the specified

condition is true.

Syntax:

while (condition is true)

{

code to be executed;

}

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2. The PHP do...while Loop

The do...while loop will always execute the block of code once, it will

then check the condition, and repeat the loop while the specified

condition is true.

Syntax:

do

{


}

while (condition is true);

3. The PHP for Loop

The for loop is used when you know in advance how many times the

script should run.

Syntax:

for (init counter; test counter; increment counter)

{


}

4. The PHP foreach Loop

The foreach loop works only on arrays, and is used to loop through

each key/value pair in an array.

Syntax:

foreach ($array as $value)

{


}

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e. PHP Array

An array is a special variable, which can hold more than one value at a time.

Syntax :

$nameof_variable[key] = value ;

For every loop iteration, the value of the current array element is assigned

to $value and the array pointer is moved by one, until it reaches the last array

element.

2.6 MySQL

MySQL is one of famous database servers that widely used. This is because

MySQL uses SQL (Structure Query Language) as a base to access the database.

MySQL is included in RDBMS (Relational Database Management System) well

known through web programming especially in the Linux environment (Saptro,

2005).

The reason why programmers chose MySQL as their database is in process

(Saputro, 2005):

1. Speed , MySQL has better speed than other RDBMS.

2. Open source , anyone can can take the role and develop MySQL and

investment results can be published to the users.

3. Security , MySQL implementing security systems and access rights are

multilevel , including support for security encryption with the data layer . The

presence of user levels and types of access beragam.Terdapat randomization

system passwords (encrypted passwords ).

4. Easy to use , the MySQL commands and rules are relatively easy to remember

and implement.

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5. The cost is cheap , the user can use MySQL without significant financial cost

for adhering to the concept of open source / GNU Public Licenses.

6. Cross- platform , MySQL can run on multiple operating systems including

Linux , Windows , FreeBSD , Novell Netware , Sun Solaris , SCO and IBM 's

AIX OpenUNIX.

7. Capabilities , MySQL can process the data stored in the database with the

amount of 50 million records , 60,000 tables and 5 billion and the number of

lines capable of processing 32 indexes per table.

2.6.1 PHP & MySQL Functions

The Following are some PHP & MySQL functions:

1. mysql_connect()

mysql_connect() is a function that used to get connected to the MySQL

database. This function has some attributes, such as:

Mysql_connect($host,$username,$password);

Table 2.4 mysql_connect Attributes

$host Hostname/IP Address is used to access MySQL

$username User who has MySQL account

$password Password

2. mysql_select_db()

After getting conected to MySQL, the next step is to choose the database that

will be used.

mysql_select_db($db,$link_id)

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Table 2.5 mysql_select_db Atributes

$db Database name

$link_id Variabel to get connected to mysql, in this case

(go see connect.php) is $koneksi

3. mysql_query()

The main requirement to access mysql has been done. The third function is to

perform query to mysql.

mysql_query ($query, $link_id)

4. mysql_num_rows()

This function is used to count the number of rows that taken from variable

query.

mysql_num_rows($query)

5. mysql_fetch_array()

This function is used to fetch record from query. This function produces array

value. By this function, the results of query can be shown on browser.

mysql_fetch_array($query)

2.7 Diseases

2.7.1 Tuberculosis

Mycobacterium tuberculosis is the leading causative agent of tuberculosis in

human beings which is believed to be a human-specialized version of Mycobacterium

bovis, an animal pathogen, developed among milk drinkers. Due to its aerobic nature,

M. tuberculosis inhabits tissues with high oxygen content such as the lungs [5]. As a

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result of this, tuberculosis disease is transmitted from an infected person to another

person through airborne means such as coughing, sneezing, spitting and even

speaking. However, a large number of tuberculosis infections in human beings remain

latent, but in a few cases it may advance to an active form which may be deadly in

nature [6].

2.7.2 Scarlet Fever

Scarlet fever (known as scarlatina in older literature references) is a syndrome

characterized by exudative pharyngitis, fever, and scarlatiniform rash. It is caused by

toxin-producing group A beta-hemolytic streptococci (GABHS) found in secretions

and discharge from the nose, ears, throat, and skin. Scarlet fever may follow

streptococcal wound infections or burns, as well as upper respiratory tract infections,

but food-borne outbreaks have been reported [7].

2.7.3 Thypoid Fever

Typhoid fever, also known as enteric fever, is a potentially fatal multisystemic

illness caused primarily by Salmonella typhi. The protean manifestations of typhoid

fever make this disease a true diagnostic challenge. The classic presentation includes

fever, malaise, diffuse abdominal pain, and constipation. Untreated, typhoid fever is a

grueling illness that may progress to delirium, obtundation, intestinal hemorrhage,

bowel perforation, and death within one month of onset. Survivors may be left with

long-term or permanent neuropsychiatric complications.

S typhi has been a major human pathogen for thousands of years, thriving in

conditions of poor sanitation, crowding, and social chaos. It may have responsible for

the Great Plague of Athens at the end of the Pelopennesian War [8]. The nameS

typhi is derived from the ancient Greek typhos, an ethereal smoke or cloud that was

believed to cause disease and madness. In the advanced stages of typhoid fever, the

patient's level of consciousness is truly clouded. Although antibiotics have markedly

26

reduced the frequency of typhoid fever in the developed world, it remains endemic in

developing countries [9].

2.7.4 Upper Respiratory Tract Infection

The upper respiratory tract or upper airway primarily refers to the parts of

the respiratory system lying outside of the thorax or above the sternal angle. Another

definition commomly used in medicine is the airway above the glottis or vocal cords.

Some specify that the glottis (vocal cords) is the defining line between the upper

and lower respiratory tracts, yet even others make the line at the cricoid cartilage

[10].

2.7.5 Measles

Measles, also known as Morbili is a highly contagious disease (infectious) which

is caused by measles virus, 90% of children who are not immune,will be infected by

measles. Measles virus are from the secretions from the nose and throat, measles

when sneezing, coughing or breathing. Measles only attack humans so as to gradually

be reduced and eliminated (Ministry of Health Republic of Indonesia, 2008).

2.7.6 Diarrhea

Diarrhea is an abnormal and liquid of feces produced. It could be define also as

abnormal amount of feces and liquid with more frequent than normal. An Infant

infected by diarrhea if he/she is deficating by 3 or more, meanwhile a neonatus

infected if he/she is deficating by 4 or more. (Vivian Nanny Lia Dewi, 2010)

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2.7.7 Tonsil

Tonsilitis is an infection caused by some bacteria which being classified as

streptococcus beta hemolitik bacteria which caused by several group of Bacteria A

streptococcus, but also infected by another types of bacteria or viruses infection

(Hembing, 2004).

Acute Tonsilitis is an infection on tonsil which still moderate. Tonsilitis on

children is usually involving many organ around it, thus faring infection is usually

reach tonsil or known as tonsilofaringitis. (Ngastiyah,1997 )

2.7.8 Chickenpox

Chickenpox is an airborne disease which spreads easily through coughing or

sneezing by ill individuals or through direct contact with secretions from the rash. A

person with chickenpox is infectious one to two days before the rash appears. They

remain contagious until all lesions have crusted over (this takes approximately six

days). Immunocompromised patients are contagious during the entire period as new

lesions keep appearing. Crusted lesions are not contagious [11].

2.7.9 Mumps

According Sumarmo (2008), mumps (parotitis) can be transmitted through direct

contact, spray saliva, vomit and urine. Not all infected people have complaints, even

about 30-40% of patients do not show signs of illness (subclinical). They can be a

source of infection such as mumps patients who appear ill. The incubation period of

parotitis is approximately 14-24 days with an average of 17-18 days.

2.7.10 Hepatitis

Hepatitis is also known as an inflammation of the liver, and can be caused by

chemicals or drugs, or various types of viral infections. One common cause of

infectious hepatitis is hepatitis A virus Infection with one type of viral hepatitis do

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not provide protection against infection with other hepatitis viruses. Clinical

symptoms of the virus varies hepatitis expansion of which is not perceived or only

little complaint until heavy objec even coma until death (Mansjoer, 2001).

epert system literature review

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