국내 저널 논문

Abstract
In semiconductor manufacturing, each wafer comprises multiple chips, and each chip is tested before the packaging process. Wafer test data on electrical characteristics of chips are collected during the wafer test process. However, missing values often occur due to various manufacturing environments. In this study, a new missing value imputation method based on Generative Adversarial Imputation Nets (GAIN) is proposed. The proposed method takes into account the two characteristics of wafer test data, namely, spatial similarity among chips and test item correlation. Spatial similarity refers to the property of having similar test item values between chips in adjacent or symmetrical positions. Test item correlation refers to the positive correlation between test items with similar physical properties. Spatial similarity and test item correlation are reflected by the addition of locational information of chips and modification of the loss function in GAIN, respectively. The performance of the proposed method is validated with a real wafer test dataset by a comparison with those of existing methods in various circumstances.

Abstract
Purpose: Smart lighting adjusts brightness and color temperature according to weather, the user’s activity, mood, etc. This study performed user experience(UX) evaluation of smart lighting in a living lab. The purpose of evaluating UX and analyzing the evaluation results is to improve user-friendliness and market competitiveness of smart lighting.
Methods: A living lab is a virtual or physical space where various stakeholders participate to develop, verify, and evaluate products, services, or systems in a real-life environment. In this study, an environment of using smart lighting was established in the Smart Safety Living Lab. Subjects performed UX evaluation after interacting freely with smart lighting in the Smart Safety Living Lab.
Results: As a result of UX evaluation, it was confirmed that UX was overall excellent and subjects were satisfied with setting a desired indoor mood through smart lighting. However, operating the switch of smart lighting may be difficult due to its complexity, and it is needed to improve some functionalities such as the brightness range provided by smart lighting. Conclusion: This study is expected to contribute to establishing the way of UX improvement of smart lighting. This study is also expected to contribute to developing smart lighting as a high-quality product by reflecting the subjects’ needs and UX derived in a real-life environment.

Abstract
Purpose: This paper introduces Pohang University of Science Technology (POSTECH) advanced metering infrastructure (AMI) and Open Innovation Big Data Center (OIBC) platform and analysis results of electricity consumption data collected via the AMI in POSTECH campus.
Methods: We installed 248 sensors in seven buildings at POSTECH for the AMI and collected electricity consumption data from the buildings. To identify the amounts and trends of electricity consumption of the seven buildings, electricity consumption data collected from March to June 2019 were analyzed. In addition, this study compared the differences between the amounts and trends of electricity consumption of the seven buildings before and after the COVID-19 outbreak by using electricity consumption data collected from March to June 2019 and 2020.
Results: Users can monitor, visualize, and download electricity consumption data collected via the AMI on the OIBC platform. The analysis results show that the seven buildings consume different amounts of electricity and have different consumption trends. In addition, the amounts of most buildings were significantly reduced after the COVID-19 outbreak.
Conclusion: POSTECH AMI and OIBC platform can be a good reference for other universities that prepare their own microgrid. The analysis results provides a proof that POSTECH needs to establish customized strategies on reducing electricity for each building. Such results would be useful for energy-efficient operation and preparation of unusual energy consumptions due to unexpected situations like the COVID-19 pandemic.

Abstract
Purpose: Smart Safety Living Lab is a Living Lab facility, constructed and operated by KITECH in Korea, to support the user experience(UX) evaluation, planning and certification of smart safety products and services. The purpose of this study is to develop a UX evaluation methodology that accommodates the characteristics of the Living Lab and smart safety products and services for a systematic and efficient UX evaluation in the Smart Safety Living Lab. Methods: A generic model of UX evaluation was first derived based on a review of related literature. Then, the generic model is revised to accommodate the characteristics of the Smart Safety Living Lab and smart safety products and services, resulting in the UX Evaluation Methodology for Smart Safety Living Lab (SSLL-UXEM). Results: The developed SSLL-UXEM consists of a structured process for UX evaluation, a guideline for conducting each step of the process, and a set of forms for recording the major evaluation results in each step. Conclusion: SSLL-UXEM can help to enhance the efficiency of the UX evaluation process and the consistency of the UX evaluation results. SSLL-UXEM is also expected to serve as a basis for UX evaluation in various living lab environments in the future.

Abstract
Main engine failures in ship operations can lead to a major damage in terms of the vessel itself and the financial cost. In this respect, condition monitoring of a vessel’s main engine condition is crucial in ensuring the vessel’s performance and reducing the maintenance cost. The collection of a huge amount of vessel operational data in the maritime industry has never been easier with the advent of advanced data collection technologies. Real-time monitoring of the condition of a vessel’s main engine has a potential to create significant value in maritime industry. This study presents a case study on the establishment of upper control limit to detect vessel’s main engine failures using multivariate control chart. The case study uses sample data of an ocean-going vessel operated by a major marine services company in Korea, collected in the period of 2016.05-2016.07. This study first reviews various main engine-related variables that are considered to affect the condition of the main engine, and then attempts to detect abnormalities and their patterns via multivariate control charts. This study is expected to help to enhance the vessel’s availability and provide a basis for a condition-based maintenance that can support proactive management of vessel’s main engine in the future.

Abstract
The purpose of this research is to identify new service opportunities for enhancing driving safety of intra-city buses based on driving behavior analysis. Service opportunity identification involves finding target customers of service (to whom), motivations for service (why), service contents (what), and service delivery process (when, where). This paper presents an analysis of driving behaviors using the operational data of intra-city buses in conjunction with traffic accident data and drivers’ driving history data. This paper also presents four identified service opportunities based on the data analysis results. This research would contribute to enhancing driving safety of intra-city buses in Korea and serve as a basis for developing new services for driving safety enhancement.

Abstract
Dual response surface optimization (DRSO), inspired by Taguchi’s philosophy, attempts to optimize the process mean and variability by using response surface methodology. Researches on DRSO were extensively done in 1990’s and have been matured recently. This paper reviews the existing DRSO methods from the decision making perspective. More specifically, this paper classifies the existing DRSO methods based on the optimization criterion and the timing of preference articulation. Also, some of case studies are reviewed. Extension to multiresponse optimization, triple response surface optimization, and application of data mining method are suggested as future research issues.

Abstract
In recent business environments, the competition among firms is shifting from the competition based on individual firm only to the competition based on alliance of firms. This is because it is not easy for a firm to perform all functions which consumers want. Thus, it is more effective to combine core competencies of different firms based on a strategic partnership. It is essential to establish a strategic partnership and this strategic partnership is a key success factor in PSS(Product-Service System) which combines products and services. In this paper, we propose a profit sharing model for PSS partnership. We first analyze customer’s utility using Cobb-Douglas utility functions and then propose the PSS profit sharing ratio considering functionalities and cost structures based on the combination ratio of PSS. This paper helps firms to develop partnership strategies for PSS.

Abstract
Product-service system (PSS) is a novel type of business model integrating products and services in a single system. It provides a strategic alternative to product-oriented economic growth and price-based competition in the global market. This paper first reviews the current status of PSS, including its concept, characteristics, benefits, and cases. This paper then reviews the existing literature and identifies major research issues for three main phases of a PSS development lifecycle, namely, PSS design, PSS evaluation, and PSS operation. This research is expected to contribute to promoting awareness and improving understanding of PSS in our society and planning of future research in this field.

Abstract
A central theme in recent IT (information technology) industry is a mobile ecosystem. While a concept of business ecosystem, which is an economic community of firms and individuals producing and consuming goods and services, has been around for about 20 years now, the recent spotlight is mainly caused by the enormous success of iPhone. Many hand-set makers or platform developers want to mimic Apple’s iPhone ecosystem from which both application developers and hand-set users can benefit. In this study, a representation model of the business ecosystem is proposed for supporting systematic design and analysis of ecosystems. Whereas previous studies also proposed some representation models, they emphasized only on the value chain between participating players. The proposed model, which is named relation-based ecosystem model, represents an ecosystem with the requirement relationships between product and service components and the roles of players, as well as their value chain. Such comprehensive representation explicitly reveals the strategic difference between ecosystems. This advantage was illustrated by comparing a Korean traditional mobile ecosystem and an emerging smart-phone ecosystem represented by the proposed model.

Abstract
Modern industrialized economies have been dominated by service sector industries. In this regards, the portion of service sector in industry is growing faster recently. According to this movement, manufacturers try to combine the intangible service with their existing tangible products to fulfill specific customer needs. It has been called as concepts of “servitization” or “Product-Service System(PSS).” In other words, manufacturers are facing new opportunities that lead them to maintain sustainable competitive advantage. Companies should also attempt to utilize “service innovation” constantly for creating new services or improving existing services in order to satisfy the unique needs of customers. The objective of this study is to find the key success factors of four companies which did successful service innovation. First, this paper introduces the concept of Product-Service Systems and servitizaiton and presents four companies based on classification framework of Shumenner’s service process matrix. Second, this paper analyzes four business models of companies through the binding platform of buyer utility map and value curve. Finally, this paper derives common and unique key success factors from four business models for creating new added value sources, competitive edge and sustainability.

Abstract
The competitiveness of the service sector is driven by its productivity. Services innovation is essential to enhancing service productivity. This paper first presents a framework for services innovation. The framework consists of three main phases of a service lifecycle (namely, service development, service operation, and service improvement), which are supported by IT infrastructure and service RnD management functions. This paper then identifies major research issues that should be investigated in the near future. The current issues of three representative service industries (namely, healthcare service, telecommunications service, and financial service) are also discussed.

Abstract
IPTV 시장 성장과 더불어 사용자 단말 기술 발달 및 사용자의 서비스 요구사항 증대로 인한 IPTV 환경 변화가 가속화 되고 있으며 이러한 환경 변화에 대응하기 위하여 IPTV 서비스에 대한 품질 관리 요소를 도출하고 지속적인 관리를 통하여 고객 체감 품질 만족도를 제고해야 한다. IPTV 서비스의 본원적 QoE(Quality of Experience)에 대한 전반적 향상을 위해서는 QoE, QoS(Quality of Service), NP(Network Performance)의 전반적 향상이 요구되는데 한정적 자원으로 최대의 효과를 얻기 위해서는 각 품질 요소를 구성하는 항목 중 영향도가 큰 항목들을 우선적으로 향상시키고 관리하는 것이 중요하다. 본 논문에서는 IPTV 품질 요소를 구성하는 항목 중 영향도가 큰 항목을 IPTV 서비스 품질 핵심 요소라 정의하고 이를 도출하기 위해 QFD(Quality Functions Deployment) 방법론을 적용한 사례와 그 결과로 도출된 IPTV 서비스 품질 핵심 요소를 기술하고 IPTV 서비스 품질 핵심 요소 간 상관 관계 및 인과 관계를 도출하여 분석한다.

Abstract
The main purpose of this research is to find out whether curriculums of industrial engineering (IE) departments meet the demand of IE graduates working in various fields. The research was conducted as an online questionnaire survey selecting IE Graduates working in industries as practising engineers. 1,324 participants were validated among 1,477 participants. 13 fields were selected and used in the survey. Those were; 1) Mathematical statistics, 2) Computer, 3) Purchase, 4) Production system, 5) Logistics, 6) Marketing, 7) Monetary, 8) Experiment methods, 9) Operations Research (OR), 10) Human Factors, 11) Quality, 12) Engineering management, and 13) Information systems. Using the 5-scale Likert rating, each education subject was assessed both in terms of its usefulness in practices and the amount it being taught in school. As a result, courses such as motion/time study, linear programming that IE has traditionally focused showed less usefulness in practices while it is taught in relatively large amount in schools. However, courses such as 6 sigma, CRM which are closely related to industrial practices showed high usefulness in practices compared with low degree of teaching in school. This was the first ever large scale survey conducted for IE graduates in Korea. The result of survey displayed many helpful information on current status and future direction of IE education in Korea.

Abstract
Today, many companies realize that the effort to develop new products/services faster that customers want and continue to purchase is crucial for their survival. As the service sector is rapidly growing, one of the challenges faced by the service industries is the lack of effective methodologies for new service development. This paper proposes a systematic framework for developing new service concepts, with an emphasis on generating innovative, convergence-type service concepts from the customer’s perspective. The framework consists of three phases ? identification of customer needs (Phase I), extraction of new service opportunities (Phase II), and generation of new service concepts (Phase III). The proposed framework is demonstrated through a case study in the telecommunications industry. In the case study, a survey was conducted on ten customers to identify the latent customer needs; 61 new service opportunities were extracted; and 129 new service concepts were generated.

Abstract
With the common objective to improve process productivity and product quality, statistical process control (SPC) and engineering process control (EPC) have been widely used in the discrete-parts industry and the process industry, respectively. The major focus of SPC is on process monitoring, while that of EPC is on process adjustment. The emergence of the hybrid industry necessitates a synergistic combination of the two methods for an effective process control. This paper investigates the existing studies on SPC, EPC, and the integration of the two methods. This paper also presents future research issues in this field.

Abstract
A desirability functions approach to a multiresponse problem is proposed considering process parameter fluctuation which may amplify the variance of response. It is called POE(propagation of error), which is defined as the standard deviation of the transmitted variability in the response as a functions of process parameters. In order to obtain more robust process parameter setting, a new desirability functions is proposed by considering POE as well as distance-to-target of response and response variance. The proposed method is illustrated using a rubber product case in Ribeiro et al. (2000).

Abstract
A desirability functions approach to a multiresponse problem is proposed considering process parameter fluctuation as well as distance-to-target of response and response variance. The variation of process parameters amplifies the variance of responses. It is called POE (propagation of error), which is defined as the standard deviation of the transmitted variability in the response as a functions of process parameters. In order to obtain more robust process parameters, this variability should be considered in the optimization problem. The proposed method is illustrated using a rubber product case.

Abstract
The project objectives, called critical-to-quality (CTQs) in six sigma, should be defined to faithfully reflect the customer requirements. The identification of such a set of CTQs, which is currently done using brainstorming in practice, is a challenging task. Notwithstanding the rapid growth of the six sigma literature, development of a systematic procedure for identifying CTQs has scarcely been addressed. This paper proposes a systematic method for generating CTQ candidates based on the given voice of the customer in the DFSS/C (Design for Six Sigma / Commercial) context. By providing a step-by-step procedure, the proposed method ensures that all the important CTQ candidates are identified and subjective judgments are minimally required. Hence, the shortcomings associated with the existing practice based on brainstorming can be effectively overcome. The unique characteristics of the proposed method are also demonstrated via a case study.

Abstract
As the functional characteristics of passenger cars have reached to a satisfactory level, customers place more concerns with the aesthetic aspects of interior designs. The present study developed satisfaction models of passenger car interior materials for six parts including crash pad, steering wheel, transmission gearshift knob, audio panel, metal grain, and wooden grain. Eight to fifteen material design variables such as color, embossing, and smoothness were defined for the six interior parts based on literature survey, customer reviews, and expert opinions. A satisfaction survey was conducted for 30 vehicles with 30 participants (mean ± SD of age = 28.7 ± 6.6) by using a modified magnitude estimation scale. Based on the survey results, the material design variables were screened from statistical, technical, and practical aspects. With the screened variables, satisfaction models were developed by using the quantification I method for the six interior parts, indicating the importance of material design variables and preferred material properties.

Abstract
A group of digital human models with various sizes which properly represents a population under consideration is needed in the design process of an ergonomic product in virtual environment. The present study proposes a two-step method which produces a representative group of human models in terms of stature and weight. The proposed method first generates a designated number of pairs of stature and weight within an accommodation range from the bivariate normal distribution of stature and weight of the target population. Then, from each pair of stature and weight, the method determines the sizes of body segments by using ‘hierarchical’ regression models and corresponding prediction distributions of individual values. The suggested method was applied to the 1988 US Army anthropometric survey data and implemented to a web-based system which generates a representative group of human models for the following parameters: nationality, gender, accommodation percentage, and number of human models.

Abstract
Kano model distinguishes three types of customer requirements, namely, one-dimensional quality, must-be quality, and attractive quality. There are a few methods for classifying a given customer requirement into one of the Kano`s quality elements. However, the existing methods have a common limitation in that they are based on Kano evaluation tables. Kano evaluation tables is not always effective for the classification task, and suffers fromm a significant information loss. This paper proposes an alternative to Kano`s evaluation tables and a new classification scheme based on fuzzy sets concept. The proposed method is illustrated using a case study on the ADSL service.

Abstract
This research in the field of quality engineering has mainly focused on the manufactured products. The philosophy and concept of the existing quality engineering should be equally applicable in the coming e-Business era. However, there would be numerous new quality-related issues in the e-Business environment, due to the fundamental change in the business processes, which did not exist in the past. This paper first proposes a framework for quality engineering research suited for the e-Business environment, and then identifies major quality-related issues that should be resolved in the near future. It also evaluates the potential usefulness and limitations of the existing quality engineering tools in resolving such issues.

Abstract
An economic procedure of selective assembly is proposed when a product is composed of two matching components. The major quality characteristic of the product is the clearance between the two components. The components are divided into several classes prior to assembly. The component characteristics are assumed to be independently and normally distributed with equal variance. The procedure is designed so that the proportions of both components in their corresponding classes are the same. A cost model is developed based on the quadratic loss functions and methods of obtaining the optimal class limits as well as the optimal number of classes are provided. Formulas for obtaining the proportion of rejection and the unavailability of mating components are also provided. The proposed model is compared with the equal width and the equal area partitioning methods uing a numerical example.

Abstract
We often have multiple quality characteristics to develop, improve and optimize industrial processes and products. It is not easy to find optimal control factor setting when there are multiple quality characteristics, since there will be conflict among the selected levels of the control factors for each individual quality characteristics. In this paper, we propose a desirability functions approach and devise a scheme which gives a systematic way of solving multiple quality characteristic problems. A numerical example is provided.