• Journal of Korean Society for Quality Management
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• v.39 no.3
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• pp.365-376
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• 2011

Robust design (RD) has emerged as a key feature in process design and development for more than twenty years. Many researchers and industrial engineers around the world have invested their intensive efforts to develop and apply RD in many fields in order to improve quality of output products. However, there is also room for improvement. The primary objective of this research is to determine "robust formulation" of a medicine by checking its gelation index. In order to achieve this target, based on the nature of problem, at first, a customized experimental format is designed for obtaining data. Second, time-depended responses based models are developed by the proposed inverse problem (IP) methodology. Third, an RD model based on mean square error (MSE) concept is introduced for time-depended responses. Finally, the proposed approach is illustrated by a case study while comparing obtained results to the response surface methodology (RSM) approach.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.2
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• pp.197-204
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• 2014

As more and more renewable energy resources are connected into the existing power system and their generation capacities are increasing, the need for regulations to minimize their impacts on the power grid is increasingly growing. And minimizing the irregular impacts made by grid-connected wind generators is important, since the output power generated by renewable energy resources can be changed easily by the weather condition and surrounding environment. In South Korea, an operational technical standard for distributed generation is used as a regulation, in which renewable energy sources including wind power are considered as a kind of distributed generation. In this paper, an international standard, IEC 61400-21, for the grid-connected wind turbine generating system(WTGS) will be introduced and a comprehensive and detailed review on the measuring methods of power quality characteristic parameters for WTGS based on the related IEC standards will be presented. Additionally, some prerequisites for applying the international standards to KEPCO system will be proposed.

• International Commerce and Information Review
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• v.7 no.2
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• pp.75-94
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• 2005

This study is focused on evaluating the computer-integrated just-in-time (CI-JIT) production system of a semi-conductor manufacturing firm in Korea. Approaching the mid-1980s, the emphasis was on low price, low-cost operations, and quality, especially in USA. American companies have shifted output to low-wage countries like the Philippines, Korea, Japan, Malaysia and allied countries that can make quality products at low prices. Korea and other Asian countries forego short-term profits to gain a solid foothold in a product market, recognizing that larger market share leads to lower cost and higher profit in the long run. They bring manufacturers and suppliers together to improve material management and operation management, using project teams that investigate topics, such as Just-In-Time(JIT)manufacturing, among others. The "Kanban" word means "card" in Japanese, and is used to indicate the desired final delivery schedule. The operation for a particular item produced is scheduled for a specific time. The same process is extended to the external suppliers. More recently, the cards are gradually being replaced by electronic procedures that follow the same concept. Its capacity must be capable of handling the various transactions required by the JIT coverage as well as some allowances for expanded applications.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.7
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• pp.2365-2382
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• 2014

While single-user spatial multiplexing multiple-input multiple-output (SU-MIMO) allows spatially multiplexed data streams to be transmitted to one node at a time, multi-user spatial multiplexing MIMO (MU-MIMO) enables the simultaneous transmission to multiple nodes. However, if the transmission time required to send packets to each node varies considerably, MU-MIMO may fail to utilize the available MIMO capacity to its full potential. The transmission time typically depends upon two factors: the link quality of the selected channel and the data length (packet size). To utilize the cumulative capacity of multiple channels in MIMO applications, the assignment of channels to each node should be controlled according to the measured channel quality or the transmission queue status of the node.A MAC protocol design that can switch between MU-MIMO and multiple SU-MIMO transmissions by considering the channel quality and queue status information prior to the actual data transmission (i.e., by exchanging control packets between transmitter and receiver pairs) could address such issues in a simple but in attractive way. In this study, we propose a new MAC protocol that is capable of performing such switching and thereby improve the system performance of very high throughput WLANs. The detailed performance analysis demonstrates that greater benefits can be obtained using the proposed scheme, as compared to conventional MU-MIMO transmission schemes.

• Journal of Korea Multimedia Society
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• v.20 no.11
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• pp.1741-1749
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• 2017

In commercial digital-cameras, color-filter filters light according to wavelength range of color filter array (CFA) and the filtered intensities contain color information of light. Then, output data of CFA is transformed to final rendered image through demosaicing process. In image processing of digital-camera, the quality of the final rendered image is affected by optical cross talk of CFA, kind of CFA pattern etc. Basically, pattern of CFA plays important role in image quality of final image rendered by digital-camera. Therefore, an evaluation system capable of quantitatively evaluating CFA is needed. This paper proposes a novel evaluation system using existing and proposed image metrics for evaluating CFAs of digital-camera. Proposed CFA evaluation system consist of color difference in CIELAB and S-CIELAB, Structure SImilarity (SSIM), MTF50, moire starting point (MSP), and subjective preference (SP). MSP and SP are newly designed for the proposed evaluation system. Proposed evaluation system is expressed in polar coordinates to analyze the characteristics of CFA objectively and intuitively. Through simulations, we confirmed that proposed CFA evaluation system can objectively assess performance of developed CFAs.

• KIEAE Journal
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• v.16 no.5
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• pp.87-92
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• 2016

Purpose: The objective of this research is to investigate and analyze the relationship between physical residential conditions and occupants' responses in apartment buildings by POE(Post-Occupancy Evaluation). The analysis results from this research will help to identify the indoor residential problems and find design solutions for improving overall residential indoor residential environment. Method: The occupant survey was conducted at four different apartment complex area at Cheongju City, Chungbuk Province, Korea. Combination of unbalanced indoor environmental conditions in residential building had difference of occupants' responses according to occupants' characteristics, such as gender, age, and so on. The survey collected data regarding the occupants' EQ(Environmental Quality) priorities to determine the weight of each environmental-quality factor (lighting, acoustic, thermal and indoor air quality). A paired comparison method was used to determine the weight by comparing the relative importance of the two factors based on occupant's survey response. Result: The output from this research is useful to understand the residential environment, occupants' satisfaction, preference, and identifies the current residential problems and finds an architectural solution in apartment buildings.

• Journal of Korean Society for Quality Management
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• v.46 no.1
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• pp.39-74
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• 2018

Purpose: For more than 30 years, robust parameter design (RPD), which attempts to minimize the process bias (i.e., deviation between the mean and the target) and its variability simultaneously, has received consistent attention from researchers in academia and industry. Based on Taguchi's philosophy, a number of RPD methodologies have been developed to improve the quality of products and processes. The primary purpose of this paper is to review and discuss existing RPD methodologies in terms of the three sequential RPD procedures of experimental design, parameter estimation, and optimization. Methods: This literature study composes three review aspects including experimental design, estimation modeling, and optimization methods. Results: To analyze the benefits and weaknesses of conventional RPD methods and investigate the requirements of future research, we first analyze a variety of experimental formats associated with input control and noise factors, output responses and replication, and estimation approaches. Secondly, existing estimation methods are categorized according to their implementation of least-squares, maximum likelihood estimation, generalized linear models, Bayesian techniques, or the response surface methodology. Thirdly, optimization models for single and multiple responses problems are analyzed within their historical and functional framework. Conclusion: This study identifies the current RPD foundations and unresolved problems, including ample discussion of further directions of study.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.4
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• pp.646-652
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• 2015

In this paper, the system-level performance is evaluated for the feedback scheme on the pre-coding matrix index (PMI) and channel quality indication (CQI), which are required for user selection in the multi-user MIMO system. Our analysis demonstrates that the number of users, the number of selected users, and codebook size are the key factors that govern the performance of the best companion grouping (BCG)-based user scheduling. Accordingly, we have confirmed that the probability of forming the co-scheduled user group is determined by these factors, which implies that the number of PMI's and codebook size can be dynamically determined so as to maximize the average system throughput as the number of users varies in the cell.

• Korean Journal of Computational Design and Engineering
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• v.19 no.3
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• pp.224-235
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• 2014

Recently, Productivity of the construction industry has been decreasing than other industries. Because of this, BIM is being spread in the construction industry. However, quality criteria for BIM data is insufficient. Regulation information is an important factor for initial architectural design evaluations. However, building code and related regulation are numerous. National building code structure in Korea is much more complex than other countries. The purpose of this study is to suggest the typology method of building code and apply to real regulations. To achieve this purpose, the authors have extracted required information to from original regulation for code checking and suggested mapping methods between extracted information and information of IFC scheme. In addition, the authors have represented EXPRESS-G diagram for extracting information from IFC scheme and suggested code checking method through stair case. Output of this study can be used as a base line data for automated code checking system based on open BIM. Automated code checking system will be utilized in architectural design evaluations and supported to increase design quality. It can be used to mount in SEUMTER that is the construction administration system of Ministry of Land, Infrastructure and Transport (MOLIT).

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.82-84
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• 2008

This paper presents the modeling and power quality analysis of Jeju island power system connected with wind farm, and thermal power plant. It is for indicating the influence of wind farm operation in steady and transient state in Jeju island power system during the HVDC system overhaul period. For the computer simulation, three kinds of main item are modeled, which are 67[MW] wind farm, thermal power plant and Jeju power load. To analyze the influence of the wind power generation to the Jeju power system, two kinds of simulations are carried out by using the PSCAD/EMTDC program. One is the steady state operation under the variable speed wind, and the other is the transient state operation when all of wind farms in Jeju island are disconnected from the Jeju power grid instantaneously on the rated power output. With the comparison of these results, it is useful for analyzing the power quality of Jeju power system versus wind power generation.