INTERNATIONAL JOURNAL OF PRECISION ENGINEERING AND MANUFACTURING Vol. 14, No. 12, pp. 2165-2170 DECEMBER 2013 / 2165

© KSPE and Springer 2013

A Development of a Web-Based and User-CenteredProcess Analysis System for Quality Improvement

Young Whun Chang1 and Soo Hong Lee1,#

1 School of Mechanical Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul, South Korea, 120-749# Corresponding Author / E-mail: shlee@yonsei.ac.kr, TEL: +82-2-2123-2823, FAX: +82-2-312-2159

KEYWORDS: Statistical process control, Control charts, Process analysis system, User-centered design, Web-based system

In order to manage and control quality of the products in a real-time manner, statistical process control methodology, one of the most

popular quality control activities, is utilized as a software service in many manufacturing industries. However, these quality control

systems are not affordable to small and medium sized industries due to their expense in installation and difficulty in the systems. To

reduce installation cost and difficulty of the systems, this research paper suggests web-based statistical process control system with

user-centered design. Although number of non-traditional and web-based SPC systems exists, they tend to focus their designs to either

beginners or experts of SPC system. The suggested system, PAS, aims to develop the system to be compatible with frequently used

browsers and acceptable in both beginners and experts. Lastly, it accepts diverse forms of data so that it attempts to support data

from industry to be used directly to the system.

Manuscript received: August 2, 2013 / Accepted: October 26, 2013

1. Introduction

Quality Control is a widely-practiced activity in manufacturing

industries to monitor quality of their products. SPC (Statistical Process

Control) is one of the quality control methodologies and it supports

real-time action to check quality continuously in manufacturing process.

The SPC system will detect any variations in the process and visualize

them in graphs and numbers manually by using statistical calculations.

As a consequence of applying SPC system, there will be significant

improvements in the quality of products, services and productivity.1

Furthermore, the SPC system has been commercialized into software

solutions so that people can simply use the system by using their own

computers. By adapting these software solutions, operation will be easier

due to user interface and calculation time will be reduced significantly

as the software will execute most of the mathematical calculations.2

Even though such SPC programs seem to be excellent and efficient in

monitoring quality, some industries are not encouraged to participate in

using them. First of all, the SPC programs are not affordable due to their

installation costs; affording license for entire computers in industries is

extremely expensive; some industries, especially small and medium

sized ones, should look for proportionally inexpensive method to check

the quality of their products. Secondly, the SPC programs are complex

and not easily comprehensible systems. Beginners in SPC systems may

find difficulty in discovering the purpose of control charts, process to

divide data into groups, implications in results and so on. In other words,

even if some companies are able to purchase the products, if they have

to train their employees to become experts, it will certainly be a time-

consuming matter. As a result, only a few companies are capable of

testing their products’ quality via SPC systems.

Despite the fact that implementing SPC system seems to be

challenging to small and medium sized industries, SPC system is a

necessary system to make products more valuable and competitive in

terms of quality. This paper presents a suggested SPC system named

Process Analysis System (PAS) which aims to resolve the issues in

small and medium sized industries. The system has an enhanced user-

centered design to guide users from start to end so that beginners in

SPC system can operate the system like experts. Furthermore, it aims

to cut the installation cost by providing its service online; users are no

longer in need to install the software with its license on their computer

and they are able to use web-based SPC system by using internet.

2. Related Works

Over the past decades, the topic related to SPC has been discussed

and there were plenty of notable changes in technology and

DOI: 10.1007/s12541-013-0293-6

2166 / DECEMBER 2013 INTERNATIONAL JOURNAL OF PRECISION ENGINEERING AND MANUFACTURING Vol. 14, No. 12

manufacturing system as well. Thus, there were previous studies to

discuss similar problems and recommend theoretical solutions to them.

S. K. Lee mentioned that various software tools applied for diverse

process were considerably expensive and difficult so that web-based

system emerged as alternative solution to use.3 Also, if systems were

able to utilize knowledge resources which were yet difficult to organize

systematically, then users might understand the system more easily.4,5

By gathering the information, major components of the system is

narrowed to web-based system and user-supporting system.

As the installation cost and difficulty of the SPC product has become

main issues for application, some researchers have addressed the same

problems and tried to resolve them with the practical approaches.

Laosiritaworn proposed a software system by using Visual Basic program

which uses the SQL server to store and load data from measurement

and notices whether defects occur through specific regulations.6

However, this system only accepted the data from the SQL server and

data size is limited to one hundred. Ab Rahman suggested SMEs-SPC

(Small and Medium Enterprises – Statistical Process Control) which is

a web-based SPC system for small and medium sized industries in

Malaysia and tries to reduce manual operations of traditional SPC

system.7

Moreover, KBAS (Knowledge-Based Analysis System) was another

online SPC system which accepts considerable types of data from

measurement and stores analytical results by converting them into XML

(eXtensible Markup Language).8 This system attempted to allow

beginners in SPC system to participate by automatically finding

appropriate control charts with process characteristics. Additionally, this

system had a node-diagram interface to store the previous information

and make users understand the system more easily; however, the system

is yet difficult and time-consuming process for beginners since such

user-required actions as defining process characteristic are quite

ambiguous.

3. Process Analysis System: Difference in User-centered

Design

By combining ideas from theoretical and practical solutions from

Section 2, many practical systems are successfully shifting to web-

based systems and they are indeed ‘non-traditional’. Nevertheless,

making user-centered design seems not to be their major goal. Indeed,

these systems would still be acceptable to limited number of users.

There exist several critical issues to resolve regarding to user-centered

design.

3.1 Universal web-based application

Although many systems are capable of being operated online, they

may face problems related to compatibility: will they operate

appropriately in each browser? For instance, some web-based systems

were constructed under using web-interface languages like Silverlight

mainly to design configurable user interface. These systems may face

compatibility issues with various browsers other than Internet Explorer

and maintainability issues due to usage of the interface languages.

Besides this issue, usage of Internet Explorer has been decreased and

that of other browsers especially Chrome and Firefox have increased

significantly. Therefore, the system must be operated in any typical

browsers and Silverlight can no longer be sustainable language under

this condition. Due to these concerns, the system must be developed

under different interface language which can holds both compatibility

and maintainability. Consequently, PAS uses HyperText Markup

Language (HTML) to create a basic structure, Cascading Style Sheets

(CSS) to visualize the structure with certain styles and Javascript to

make interaction between clients and servers. These three languages

have been used frequently to develop structure of client side in websites

and so many developers provide sustainable sources to increase

maintainability. Furthermore, their compatibility with major browsers

is greater than compatibility of Silverlight. Therefore HTML, CSS and

Javascript are chosen as new interface languages to reinforce

compatibility and maintainability of the system. As a result of

substitution, the system is capable of operating in major browsers,

namely Firefox, Chrome, Safari and Internet Explorer.

3.2 User-centered simplification

Most of the non-traditional SPC systems emphasized the fact that

they attempt to facilitate process of the SPC system. For example, some

solutions provide direct comments to users to understand whether the

process data is stable or not. Also, some other solutions offer the

service which finds applicable control chart by setting characteristics of

process data automatically. Despite the facilitations, beginners in SPC

system might still have difficulty in finding roles of control charts and

meanings of graphical results. User-centered simplification is not just

concerning simplification; it must distinguish two types of users:

beginners and experts. For beginners, each step must be comprehensible

so that they will be adapted into the system and methodologies inside

the SPC system more easily and quickly. At the same time, since

experts understand the complete process of the system, the system

should provide the simple steps to approach their objectives. In other

words, while facilitating system will guide users to the results quickly,

the system should train users to understand what kind of algorithm is

used to compute the result through interface of the webpage.

To make such a simplified system, there are three major

improvements on the interface. First, the guide system regarding to

control chart should be provided to increase comprehension in SPC

system. There are various types of process data and control charts to

analyze them. To match them appropriately, users must know

characteristics of their data and roles of each control chart in the SPC

system. PAS divided control chart systems into five distinguishable

scenarios in terms of characteristic of selected data so that novice users

can narrow down the targeted charts they want to use. However, some

beginners may not understand characteristic of data. By identifying

various cases, PAS divides users within three cases as shown in Fig. 1.

For users who do not understand either characteristic of their data and

control charts, PAS suggests a guide system with sets of questions

which clarifies the characteristics of process data with words as shown

in Fig. 2. Moreover, if users understand characteristic of their data, they

may select the appropriate scenario and attempt to choose one of the

control charts; after selection, users will be able to see the sample graph

and description of the graph as demonstrated in Fig. 3. The guide system

is completely optional component in the system so that experts in SPC

system may select the control chart without question sections.

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Secondly, the system includes dynamically communicating interface.

Many systems used static communication which should use various

buttons to head onto the next process; some portions of processes could

be preceded on new windows. Asynchronous communication is applied

to demonstrate the process more smoothly and intuitively by reducing

number of actions users have to do and number of pages to represent

results or return values from server pages. Consequently, asynchronous

communicating interface will aid interactions between system and users.

For instance, to reduce buttons and steps in the database connection

process, PAS decreases numbers of buttons significantly and

demonstrates sample data from the table through asynchronous

communication.

Thirdly, the system provides user-centered graphical interfaces to

improve interaction between system and users. For example, once users

achieve the data from their sources, they may want to change the rage

of the data. To aid this process, filtering system should exist in PAS. In

order to make this system interact with users easily, a horizontal scroll-

bar is attached so that users can easily modify the size of the range and

starting and ending points of the range.

Moreover, the difference between other systems and PAS is that the

typical SPC systems are capable of providing results for just one control

chart at singular analysis while PAS can provide various control charts

at singular analysis. In SPC system, it is important to use various control

charts for observing process variations in different perspectives. For

instance, by using Xbar-R control chart, users may find no significant

variation since all the resultant data is located inside upper and lower

control limits. However, applying CUSUM (CUmulative SUM control

chart) control chart which is utilized for change detection may bring

different result to users. Thus, it is crucial to compare multiple charts

concurrently to check the result in details. By accepting multiple

scenarios in scenario configuration page shown in Fig. 3, PAS is

developed to demonstrate various control charts by singular analysis.

During the analysis configuration step where users have to insert required

inputs for corresponding control chart, multiple control charts can give

users repeated process like inserting the same inputs. To avoid such an

issue, the researchers find all the similar and unique inputs requested in

all of the control charts; they unify similar inputs as basic inputs and

leave the unique inputs as the inputs required for specific chart. Finally,

users are able to view multiple control charts by inserting basic inputs

and some unique inputs specifically required for certain charts. This

reduction process not only reduces times for analysis but also provides

a simple way to compare individual charts.

Fig. 1 The guiding procedure of PAS for selecting control charts

Fig. 2 The guide system of PAS for beginners

Fig. 3 The guide system of PAS for chosen control chart

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Lastly, a statistical plot of the SPC system provides the most valuable

result of control charts and implies whether the quality of data is stable

or not. If thousands of data are used to be analyzed, then users may have

to expand the plot to check the result precisely and clearly. By using the

graphical plot provided from statistical software like R-script, developers

cannot modify the plot because the plot will be made as a static image

source. To make this graph dynamically, the system uses its own analysis

engine instead of using R-script; therefore, analysis engine computes a

data into numerical results and Javascript code will compute them and

draw a corresponding dynamic plot. Due to this dynamic process,

developers may add expansion/compression system into the plot so that

users may see the plot more clearly as they wanted. In case when users

want to see the current area they expanded, there exists a navigational

picture which demonstrates not only the whole data of the plot, but also

the specific area chosen to view. To represent this system in graphical

details, the plot result is shown in Fig.4. Also, Fig. 5 demonstrates

another function in graphical results which users may see the numerical

result graphically by hovering their mouse on each point.

3.3 Wide range of data approval

In order to make the universal SPC platform, one of the most

important considerations is to accept various types of storing measured

data from industries. In other words, typical kinds of database and

external data formats should be acceptable in the system. In order to

actualize this goal, the study analyzes typical databases used frequently

in the industries and external data formats capable of containing

numerical data. As a result, four types of databases, namely DB2,

Oracle, MYSQL and MSSQL and three types of external data format,

EXCEL, Text and CSV, are chosen as acceptable data containers as

shown in Fig. 6.

By combining these aspects, PAS is capable of operated in multi-

browsers, supporting users with user-centered interface and controlling

most types of the data.

4. Implementation of Process Analysis System

4.1 System architecture

The architecture of PAS can be divided into three sections: client,

server and data. Client section solely controls structure and actions of

user interface. If users request to save the data or bring the data, client

tier will send users’ request to server tier. Server section contains three

distinct layers which must be preceded with proper steps. Server section

is connected with Client and Data Sections. Thus, server section will

Fig. 4 User-interacting functions in graphical result of PAS

Fig. 5 Mouse hovering action on the graphs of PAS to visualize

numerical information of results

Fig. 6 Acceptable external data sources in PAS

Fig. 7 The architecture of PAS

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read users’ requests and either bring or save data from Data Section.

Data section controls the server resources or the data users stored in the

server database. The thorough scheme of PAS architecture is represented

in Fig. 7 precisely.

4.2 System procedure

The system includes five major pages. The first page is project

history page which contains basic information in the previous projects.

The second page is setting up project and data page. First of all, users

should insert a unique name for the project to save data and result in

the database. Furthermore, the users should pick certain data format.

Once data format is chosen, they are able to extract data from their own

external data sources by inserting specifically required inputs which are

different from each data format. This process is described in Fig. 8. Then,

users are allowed to configure the extracted data. As shown in Fig. 9,

data is contained in rows and columns of a table. By using options

listed in Fig. 9, they may narrow the range of the data by reducing size

of rows and columns. Lastly, filtered data will be saved into the server

database. Once the data is saved, users have to choose control charts to

be used for analysis on the scenario page demonstrated previously in

Fig. 3. If they are not familiar with control charts, they should click

“control chart guide” and the system will aid users to find the appropriate

control charts. After the control chart is selected, users need to insert

values into corresponding inputs on the analysis configuration page.

Figure 10 shows the basic input required for Xbar-R control chart; user

should configure number of data in each group and the system will

automatically calculate total number of groups visualized on the result

page. The last page is the result page, demonstrated in Fig. 4 and Fig.

5, where users are capable of observing both graphical and numerical

results on the interface and they may print the results if necessary. The

whole process of PAS and relationship among five major steps is

described in Fig. 11.

5. Conclusion

The goal of PAS is to reduce the installation cost of the SPC system

and make the system much simpler. Previous research work aimed to

Fig. 8 A step of project creation and data extraction

Fig. 9 A step of filtering and configuring extracted data

Fig. 10 A step of analysis input configuration

Fig. 11 An overall system procedure

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create such a system by making it as a web-based and simplified

application. Nevertheless, this study discussed possible improvements

to reinforce SPC system by distinguishing beginners and experts and

finally the study suggested the new system called PAS. This system has

three major modifications, namely universal web-based application, user-

centered simplification and wide range of data approval. Through these

major changes, the system is able to accept various types of users,

especially ones who are willing to use SPC system while they do not

know how to use them practically. Furthermore, by demonstrating

multiple control charts concurrently, the system reduces time for

multiple analyses. Also, the study emphasizes a point that status of a

manufacturing process cannot be fixed with just one control chart.

In order to evaluate the system and compare it with other

commercialized SPC products, applying system into actual small and

medium-sized industries is certainly required. Through applications,

system’s evaluation will be measured in details and receive various

feedbacks in diverse aspects. Furthermore, in order to make system

familiar to users, the interface of the system should be customizable. In

other words, the system should be divided as distinguishable modules

or parts so that users may organize them into personalized interface. As

a consequence, users can memorize and configure the system more

easily.9 Moreover, the best way to inspect the quality is by inspecting

the “raw” process data. If the system is able to store the process data

measured by machines directly to the server database, the process time

of the system will be significantly efficient. In order to actualize this

system, there should be a way to standardize data from various types

of process machines and an algorithm to automatically send process

data into PAS server database. Lastly, usage of SPC system has been

shifting towards to different fields, especially to healthcare services.10

It is important to adapt the system to accept data from these fields as

well so that the suggest system can get closer to develop a “universally”

acceptable system.

ACKNOWLEDGEMENT

“This work was supported by the Configurable Manufacturing

Execution System Project funded by Ministry of Knowledge Economy,

Republic of Korea” (10033304).

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