• Journal of Korean Society for Quality Management
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• v.43 no.1
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• pp.31-42
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• 2015

Purpose: System consists of a lot of units with coherent function. In design phase, various units could be considered with the same function. In this study, we consider the alternative units with the same function and redundancy allocation to maximize system reliability in multi level system. Methods: The redundancy allocation problem with the alternative units in multi level system is formulated. Memetic algorithm(MA) is proposed to optimize the redundancy allocation problem. In addition, the performance of the proposed algorithm is explained by a numerical experiment. Results: MA showed better results than genetic algorithm(GA) and the convergence of the solutions in MA was also faster than GA. In addition, we could know from experiment that system reliability is increased and the chosen unit for redundancy allocation is changed if cost limit is increased. Conclusion: The chose unit for redundancy allocation is changed as resource constraints. It means we need to consider the alternative units in system design. In the future, we need to consider various problem related to redundancy allocation in multi level system and develop the better method to enhance search performance.

• Journal of Korean Society for Quality Management
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• v.47 no.4
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• pp.701-711
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• 2019

Purpose: The problem of optimizing redundancy allocation in multi-level systems is considered when each item in a multi-level system has alternative items with the same function. The number of redundancy of multi-level system is allocated to maximize the reliability of the system under path set and cost limitation constraints. Methods: Based on cost limitation and path set constraints, a mathematical model is established to maximize system reliability. Particle swarm optimization is employed for redundant allocation and verified by numerical experiments. Results: Comparing the particle swarm optimization method and the memetic algorithm for the 3 and 4 level systems, the particle swarm optimization method showed better performance for solution quality and search time. Particularly, the particle swarm optimization showed much less than the memetic algorithm for variation of results. Conclusion: The proposed particle swarm optimization considerably shortens the time to search for a feasible solution in MRAP with path set constraints. PS optimization is expected to reduce search time and propose the better solution for various problems related to MRAP.

• 프린팅코리아
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• v.8 no.6
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• pp.58-63
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• 2009

대표적인 소량다품종인쇄물인 웨딩인쇄물 시장에 변화의 바람이 불고 있다. 대부분의 고객이 $3{\sim}500$장 내외로 인쇄하는 경우가 많은 청첩장인쇄는 예전부터 기성카드에 마스터인쇄를 해서 제작하는 경우가 일반적이었다. 물량이 상대적으로 소량이어서 오프셋인쇄로 작업할 수 없었기 때문에 마스터인쇄사의 대표적인 일감의 하나로 불렸다. 그러나 최근 들어서 개성을 중시하는 결혼식과 청첩장을 차별화하고 싶다는 경향이 소비자를 중심으로 활발하게 일어나는가 하면 디지털인쇄기의 본격적인 보급으로 소량다품종 인쇄를 지원하기 시작했으며 다양한 후가공 작업을 쉽게 진행할 수 있게 되어 맞춤형 및 고급형 청첩장 인쇄시장이 지속적인 성장을 거듭하고 있다. 물론 아직까지 기성카드사의 제품을 사용하는 청첩장 인쇄가 제일 많다. 그렇지만 예전과 달리 청첩장의 종류가 수백, 수천가지에 달하기 때문에 개성을 최대한으로 살리는 선택을 하는 것이 가능하기 때문에 어떤 면에서는 맞춤형 청첩장인쇄와 다름없다는 주장과 평가도 나오고 있다. 현재 청첩장을 비롯한 결혼과 관련된 인쇄물은 대체적으로 카드업체를 중심으로 하는 기성품시장, 개별 단가는 매우 높지만 아직까지 시장의 수요는 일부 계층에 국한되어 있는 고급형 맞춤 청첩장을 비롯, 디지털인쇄기를 이용해 포토청첩장 등 특별한 디자인의 청첩장을 수주하는 인쇄업체 등으로 크게 분류되어 있다. 한편 지난 2007년을 기준으로 $3{\sim}500$억원 대에 달하는 웨딩인쇄물 시장은 결코 큰 시장이라고 할 수는 없으나 꾸준한 성장세를 보인다. 청첩장이 어떤 의미에서 볼 때 작은 소품의 기능을 갖는다는 것을 보면 상당히 큰 시장이라고도 볼 수 있을 것이다. 최근 진행되고 있는 웨딩 인쇄물 시장의 변화와 현황을 살펴본다.

• IE interfaces
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• v.19 no.2
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• pp.124-132
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• 2006

The system under study is a single item, multi-echelon distribution system with a capacitated production facility. All the nodes at the downstream ends are demand-sites, i.e., ordered items are delivered to the customers from the node. Also any transshipment depots in the midstream can be demand-sites as well. For a given planning period, at each of demand-site, demand is forecasted and known. Our objective is to minimize the average system cost per period which is the sum of holding and backorder costs in the entire network. Due to the capacity restrictions, it is difficult to establish efficient distribution planning. To overcome such a difficulty and obtain a reasonable and better solution, we convert this problem into a single machine earliness and weighted tardiness scheduling. We propose a simple but cost-effective heuristic for this problem. The experimental results showed that the proposed heuristic obtained much better solutions compared with another approach.

• Journal of Biomedical Engineering Research
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• v.19 no.3
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• pp.305-312
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• 1998

A small PACS based on PC is designed for CR. To receive the digital image from CR, a DICOM Interface Unit (DIU) is designed that complied with the medical image standard, DICOM V3.0. The CR images acquired through the DIU are stored in a file-server; the patient information of the images is stored in a database. To improve the performance of PC and to use it easily, multiresolution images are constructed by wavelet transform and displayed progressively. Wavelet compression method is newly adopted to store the images hierarchically to storage units. In this compression method, the image is decomposed into subclasses of image by wavelet transform, and then the subclasses of the image are vector quantized using a multiresolution codebook. The storage units for CR images were divided into the short-term storage in file-server and the harddisk in viewing station. Image processing tools supported by general PACS is implemented based on PC.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.3
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• pp.285-297
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• 2016

In this paper, a centralized mmWave-based multi-spot beam cellular system architecture having such a base station equipped with a plurality of beam-forming antennas, multi-layered dynamic cell configuration method as one of key concepts of this system operation and a mobility management method based on it are introduced. To estimate the performance of new system, system simulation was performed under the ideal environment without blockage. These results show the possibility that system capacity can be dramatically increased and mobility performance similar to the existing cellular system may be achieved.

• Korean Management Science Review
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• v.31 no.3
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• pp.61-76
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• 2014

There are three methods for calculating the optimal level for spare part inventories in a MIME (Multi Indenture and Multi Echelon) system : marginal analysis, Lagrangian relaxation method, and genetic algorithm. However, their solutions are sub-optimal solutions because the MIME system is neither convex nor separable by items. To be more specific, SRUs (Shop Replaceable Units) are required to fix a defected LRU (Line Replaceable Unit) because one LRU consists of several SRUs. Therefore, the level of both SRU and LRU cannot be calculated independently. Based on the limitations of three existing methods, we proposes a improved algorithm applying marginal analysis on determining LRU stock level and genetic algorithm on determining SRU stock level. It can draw optimal combinations on LRUs through separating SRUs. More, genetic algorithm enables to extend the solution search space of a SRU which is restricted in marginal analysis applying greedy algorithm. In the numerical analysis, we compare the performance of three existing methods and the proposed algorithm. The research model guarantees better results than the existing analytical methods. More, the performance variation of the proposed method is relatively low, which means one execution is enough to get the better result.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.3C
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• pp.271-278
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• 2003

In this paper, we propose a new MLP based detector which has low circuit complexity and fast adaptation capability for CDMA downlink in frequency selective fading, and is easy for parameter optimization. The simplified structure of the proposed MLP is designed by making use of transmission characteristics of downlinks such that all users signals transmitted over same propagation paths and the number of channelization codes are limited. Significant performance improvement over Rake receiver can be obtained with the proposed MLP and the efficiency of the proposed MLP was compared with that of conventional MLP.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.8
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• pp.718-725
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• 2004

The real-time industrial network, often referred to as fieldbus, is an important element for intelligent manufacturing systems. Thus, in order to satisfy the real-time requirements of field devices, numerous fieldbus protocols have been announced. But, the application of fieldbus has been limited due to the high cost of hardware and the difficulty in interfacing with multi-vendor products. Therefore, as an alternative to fieldbus, the computer network technology, especially Ethernet (IEEE 802.3), is being adapted to the industrial environment. However, the crucial technical obstacle for Ethernet is its non-deterministic behavior that makes it inadequate for industrial applications where real-time data have to be delivered within a certain time limit. Recently, the development of switched Ethernet shows a very promising prospect for industrial application due to the elimination of uncertainties in the network operation resulting in much improved performance. This paper focuses on the application of the switched Ethernet with cascade structure for industrial communications. More specifically, this paper presents an analytical performance evaluation of switched Ethernet with cascade structure, and a case study about networked control system.

• Journal of Korea Game Society
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• v.10 no.3
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• pp.73-82
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• 2010

The Metadata are used for the reuse of core information, distribution and management, protection of copyright and prevention of overlapping investment. Serious game consists of multi-hierarchial multimedia data. And quality information is very important for selection according to the purpose of the game. In this paper, we designed the serious game metadata schema, including multi-media characteristic information and measurable quality information. This study will lay the groundwork for the development of metadata system which can provide serious game users with reliability through quality information, and with compatibility through multi-media characteristic information. Furthermore, we hope this study will be helpful to stable growth in serious game industry.