• 한국경영과학회지
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• 제29권1호
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• pp.43-56
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• 2004

The purpose of clustering is to partition a set of objects into several clusters based on some appropriate similarity measure. In most cases, clustering is considered without any prior information on the number of clusters or the structure of the given data, which makes clustering is one example of very complicated combinatorial optimization problems. In this paper we propose a general-purpose clustering method that can determine the proper number of clusters as well as efficiently carry out clustering analysis for various types of data. The method is composed of two stages. In the first stage, two different hierarchical clustering methods are used to get a reasonably good clustering result, which is improved In the second stage by ASA(accelerated simulated annealing) algorithm equipped with specially designed perturbation schemes. Extensive experimental results are given to demonstrate the apparent usefulness of our ASA clustering method.

• Clinical and Experimental Reproductive Medicine
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• 제27권3호
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• pp.253-259
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• 2000

Objective: To verify the effect of Matrigel, a ECM complex from Engelbreth-Holm-Swarm (EHS) mouse sarcoma on the preimplantation development and apoptosis of mouse fertilized eggs. Method: Late pronucleus stage eggs were cultured through the blastocyst stage in the presence of Matrigel (0.5%, v/v). Characteristics of apoptosis and cell number assesed by Hoecst staining and TUNEL labeling at the blastocyst stage, respectively. Results: Morphological development, number of cells per embryo was significantly increased but rate and number of TUNEL positive nuclei of the embryo were decreased in the presence of Matrigel. Conclusion: This result suggested that at low concentration of Matrigel improves both viability and morphological development in the preimplantation mouse embryos.

• 품질경영학회지
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• 제13권2호
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• pp.29-36
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• 1985

The problem of selecting the gamma population with the largest mean out of k gamma populations, each of which has the same shape parameter is considered. An elimination type two-stage procedure is proposed which guarantees the same probability requirement using the indifference-zone approach as does the single-stage procedure of Gibbons, Olkin and Sobel (1977). The two-stage procedure has the highly desirable property that the expected total number of observations required by the procedure is always less than that of the corresponding single-stage procedure regardless of the configuration of the population parameters.

• 환경위생공학
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• 제14권4호
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• pp.41-49
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• 1999

The water treatment by was performed to remove VOC and organic substances in the multi-stage ozone contactor. Ozone is mainly utilized to change the chemical structures of organic substance, of which finally has the purpose to degrad them. The removal efficiency of VOC has 20~60% at the ozone concentration of 3 ppm, in case of trichloroethylene, its efficiency is reduced by 85% at the ozone contact time of 8 min. Design factors such as the number of stage, ozone concentration, zone contact time are determined for optimal treatment in the multi-stage contactor.

• 화훼연구
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• 제19권2호
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• pp.89-95
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• 2011

본 연구는 daminozide의 엽면살포를 이용하여 국내 육성 스프레이 국화 '챠밍아이(Charming Eye)'와 '핑크프라이드(Pink Pride)' 온실 내 고온에 의한 꽃목의 과도한 신장을 억제함으로써 품질을 향상시키기 위해 수행하였다. 처리 시기는 화뢰 발달 과정별로 2단계 (stage I, II)로 나누고 daminozide의 처리농도는 0, 500, 1000, $2000mg{\cdot}L^{-1}$로 구분하여 처리하였다. '챠밍아이'의 경우, 절화장, 꽃목 직경, 줄기직경, 화뢰 직경, 화뢰 수에 있어서 무처리구와 처리구간의 차이가 없었다. 그러나 꽃목 신장의 억제효과, 정단부 화서배열 각도의 증가 및 화뢰 수의 증가는 daminozide 농도에 관계없이 stage I의 처리구가 stage II의 처리구보다 우수하였다. '핑크프라이드'의 경우는 절화장, 꽃목 직경, 줄기 직경에 있어서 무처리구와 처리구간의 차이가 없었으나, 정단부 화서배열 각도는 stage II의 $2,000mg{\cdot}L^{-1}$ 처리구를 제외하고는 stage I과 stage II의 모든 daminozide 처리구가 무처리구에 비해 증가하였다. 화뢰 수와 화뢰 직경은 stage I의 $1,000mg{\cdot}L^{-1}$ 처리구에서 가장 큰 증가를 나타내었고, stage II의 $2,000mg{\cdot}L^{-1}$ 처리구에서 가장 적은 값을 보여주었다. 꽃목 길이는 daminozide 농도가 증가함에 점차적으로 감소하였으나, daminozide를 엽면 살포한 꽃 목의 신장은 Stage I에 처리시 stage II 처리보다 억제효과가 크게 나타났다. 평행한 화뢰 수의 증가는 stage I의 $2,000mg{\cdot}L^{-1}$ 처리구에서 가장 우수하였다. 결론적으로 '챠밍아이'는 stage I 시기에 $500{\sim}1,000mg{\cdot}L^{-1}$ daminozide를 엽면 살포하고 '핑크프라이드'는 stage I 시기에 $1,000{\sim}2,000mg{\cdot}L^{-1}$ daminozide를 엽면 살포하여 절화 상품성을 향상시킬 수 있을 것으로 판단되었다.

• Journal of Power Electronics
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• 제18권5호
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• pp.1325-1335
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• 2018

This paper presents a discontinuous pulse width modulation (DPWM) method to reduce switching losses in an indirect matrix converter (IMC) drive. The IMC has a number of power semiconductor switches. In other words, it consists of a rectifier stage and an inverter stage for AC/AC power conversion, which are composed of 12 and 6 switching devices, respectively. Therefore, the switching devices of the IMC suffer from high switching losses in the IMC drives. Various topologies to reduce switching losses have been studied by eliminating a number of switches from the rectifier stage. In this study, in contrast to prior research, a DPWM method is presented to reduce the switching losses of the inverter stage. The effectiveness of the proposed method to reduce switching losses in IMC drives is verified by simulations and experimental results.

• Smart Structures and Systems
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• 제11권1호
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• pp.69-86
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• 2013

An efficient methodology using static test data and changes in natural frequencies is proposed to identify the damages in structural systems. The methodology consists of two main stages. In the first stage, the Damage Signal Match (DSM) technique is employed to quickly identify the most potentially damaged elements so as to reduce the number of the solution space (solution parameters). In the second stage, a particle swarm optimization (PSO) approach is presented to accurately determine the actual damage extents using the first stage results. One numerical case study by using a planar truss and one experimental case study by using a full-scale steel truss structure are used to verify the proposed hybrid method. The identification results show that the proposed methodology can identify the location and severity of damage with a reasonable level of accuracy, even when practical considerations limit the number of measurements to only a few for a complex structure.

• 한국국방경영분석학회지
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• 제24권1호
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• pp.176-188
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• 1998

In this paper, it is identified that the optimal level of each performance measures (service and inventory level) is not sensitive to an uncertain environment under JIT Kanban system designed by Moeeni. Moreover, it is proposed that the optimal design method considering multiple performance characteristics is the optimal level decision method according to the relative importance differences of each performance when there exist multiple performance characteristics. The result from the simulation analysis shows that the number of Kanban for stage 3 (final process) and stage 2 is increased at the service level. It is found that the expected loss is minimal when the cycle time decreases and the container size increases. However, the stage 1 is not affected by the number and cycle time of Kanban. It is thus important to consider carefully the cycle time and the container size of the Kanban to satisfy the demand in right time. In case of inventory level, the working inventory level decreases when the container size is decreased and the working inventory level also decreases slightly when the cycle time of the Kankban is increased in stage 1 and 2.

• 산업경영시스템학회지
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• 제20권43호
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• pp.249-263
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• 1997

This paper addresses the parts route selection and economic design in flexible manufactuirng system (FMS). Parts are processed through several stage workstations according to operation sequences. The machine of each workstation can do multiple operation functions. And the operation stage of a part can be processed in several workstations, which are non-identical in functional performance. The objective of this paper is to determine the processing routes of parts, number of machine at each workstation, number of vehicle and makespan time. Two models are suggested. One is assumed that the operation stage of parts can be processed at the only one among several available workstations. Other is assumed that the operation stage of parts is allowed to be processed at several workstations. Parts are transported by automated guided vehicles (AGVs). The decision criteria is to minimize the sum of processing cost, travel cost, setup cost and overhead cost. The formulation of models is represented. A solution algorithm is suggested, and a numerical example is shown.

• 한국정보처리학회논문지
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• 제6권5호
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• pp.1212-1218
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• 1999

This paper proposes a new multipath interconnection network(MIN) structure for improving performance which uses widely in the design of multiprocessing, ATM system and VOD server. For improving performance such as passthrough ratio and packet latency, it proposes new routing method which routes one of the collided packets into the i+1-th switching stage of the adding Banyan MIN network when it occurred collision at the i-th switching stage of the basic MIN again when they collide each other. The new improved performance MIN network has been compared with MBSF, TBSF and PBSF structured MIN network from the viewpoint of passthrough ratio and the number of switching stage vs. passthrough ratio. It is shown to improve a performance and to be a simple structure which reducing the number of switching stage of adding MIN in comparison with other structured MIN including TBSF.