• 한국시뮬레이션학회:학술대회논문집
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• 한국시뮬레이션학회 2000년도 추계학술대회 논문집
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• pp.28-33
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• 2000

This article describes the application of discrete event simulation in a process industry (coffee manufacturing) as a daily production-scheduling tool. A large number of end products (around 300), sporadic demand, and limited shelf life of coffee (90 days) make it difficult to generate feasible production schedules manually. To solve this problem an integrated system was developed incorporating discrete event simulation methodology into scheduling process. The integrated system is comprised of two components: a scheduling program and a simulation model. The scheduling program is used to generate daily schedules for roasting, grinding, and packing coffee. The simulation model uses the generated schedules to simulate the production of coffee and regenerates a modified production schedule. In this paper, each of the components will be described in detail, evaluated in terms of performance factors, and validated with a set of real production data. Although this article focuses on a specific system, we will share our experiences and intuitions gained and encourage other process industries to develop simulation-based scheduling tools.

• Industrial Engineering and Management Systems
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• 제3권1호
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• pp.22-37
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• 2004

An integrated heuristic approach based on genetic algorithms (GAs) is proposed for solving the container selection and loading problems. The GA for container selection solves a two-dimensional knapsack problem, determining a set of containers to minimize the transportation or shipment cost. The GA for container loading solves for the weighted coefficients in the evaluation functions that are applied in selecting loading positions and boxes to be loaded, so that the volume utilization is maximized. Several loading constraints such as box orientation, stack priority, stack stability, and container stability are also incorporated into the algorithm. In general, our computational results based on randomly generated data and problems from the literature suggest that the proposed heuristic provides a good solution in a reasonable amount of computational time.

• 충청수학회지
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• 제23권2호
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• pp.231-236
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• 2010

Using the properties of the concave function, we show that the Hausdorff dimension of the product $C_{\frac{a+b}{2},\frac{a+b}{2}}{\times}C_{\frac{a+b}{2},\frac{a+b}{2}}$ of the same symmetric Cantor sets is greater than that of the product $C_{a,b}{\times}C_{a,b}$ of the same anti-symmetric Cantor sets. Further, for $1/e^2$ < a, b < 1/2, we also show that the dimension of the product $C_{a,a}{\times}C_{b,b}$ of the different symmetric Cantor sets is greater than that of the product $C_{\frac{a+b}{2},\frac{a+b}{2}}{\times}C_{\frac{a+b}{2},\frac{a+b}{2}}$ of the same symmetric Cantor sets using the concavity. Finally we give a concrete example showing that the latter argument does not hold for all 0 < a, b < 1/2.

• 대한전자공학회논문지SD
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• 제37권4호
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• pp.80-89
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• 2000

본 논문에서는 시간제약 조건하에서 순차회로를 위한 새로운 CPLD 기술매핑 알고리즘을 제안한다. 본 기술매핑 알고리즘은 주어진 순차회로의 궤환을 검출한 후 궤환이 있는 변수를 임시 입력 변수로 분리한다. 조합논리 부분을 DAG로 표현하여 그래프 분할과 collapsing, bin packing을 수행한다. 그래프 분할에서 DAG의 각 노드를 검색한 후, 출력 에지의 수가 2이상인 노드를 분할하지 않고 노드만을 복제(replication)하여 팬 아웃 프리 트리로 재구성한다. 이러한 구성 방법은 주어진 시간 조건 안에서 기존의 CPLD 기술매핑 알고리즘으로 제안된 TEMPLA보다 적은 면적으로 회로를 구현하고, TMCPLD의 단점인 전체 수행시간을 개선하기 위한 것이다. 본 논문에서 제안한 기술매핑 알고리즘을 MCNC 논리합성 벤치마크 회로들에 적용하여 실험한 결과 기존의 CPLD 기술 매핑 툴인 TEMPLA에 비해 CLB의 수가 17.01% 감소되었고, TMCPLD에 비해 수행 시간이 감소되었다.

• 한국정보처리학회논문지
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• 제7권1호
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• pp.224-234
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• 2000

본 논문에서는 시간제약 조건하에서 순차회로를 위한 새로운 CPLD 기술매핑 알고리즘을 제안한다. 본 기술매핑 알고리즘은 주어진 순차회로의 궤환을 검출한 후 궤환이 있는 변수를 임시 입력 변수로 분리한 후 조합논리 부분을 DAG로 표현한다. DAG의 각 노드를 검색한 후, 출력 에지의 수가 2이상인 노드를 분할하지 않고 노드만을 복제(replication)하여 팬 앙웃 프리 트리로 재구성한다. 이러한 구성 방법은 주어진 시간 조건 안에서 기존의 CPLD 기술 매핑 알고리즘으로 제안된 TEMPLA보다 적은 면적으로 회로를 구현하고, TMCPLD의 단점인 전체 수행 시간을 개선하기 위한 것이다. 시간제약 조건과 소자의 지연시간을 이용하여 그래프 분할이 가능한 다단의 수를 정하고, 각 노드의 OR 텀수를 비용으로 하는 초기비용과 노드 병합 후 생성될 OR 텀수인 전체비용을 게산하여 CPLD를 구성하고 있는 CLV의 OR텀수보다 비용이 초과되는 노드를 분할하여 서브그래프를 구성한다. 분할된 서브그래프들은 collapsing을 통해 노드들를 병합하고, 주어진 소자의 CLB안에 있는 OR텀 개수에 맞게 Bin packing를 수행하였다. 본 논문에서 제안한 기술매핑 알고리즘을 MCNC 논리합성 벤치마크 회로들에 적용하여 실험한 결과 기존의 CPLD 기술 매핑 툴인 TEMPLA에 비해 CLB의 수가 15.58% 감소되었고, TMCPLD에 비해 수행 시간이 감소되었다.

• 한국포장학회지
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• 제26권2호
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• pp.61-69
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• 2020

As post-harvest processes of onions are carried by a 20 kg-net package which results in high-cost and low-efficiency, especially, the insufficient drying and physical damage of onions after harvesting leads to a huge second loss in storage, we had developed a low-cost, high-efficiency post-harvest bulk handling machinery system by collecting onions on a farm using ton-bags, drying with forced air circulation, and sorting/packaging. The post-harvest bulk handling machinery system consisted of 6 devices, and this study designed an automatic feed hopper with a feeding rate control device, an inclined belt conveyor with a two-step chute, and an automatic pallet unloading device for feeding onions into the sorting/packing line. This study also analyzed the performance and control of the total system. The device had 1-ton handling capacity, but the operational condition was set to increase the capacity. The three-step filling method of pallet by the velocity control of the inclined belt conveyor was applied in the post-harvest bulk handling machinery system for the prevention of physical damage. If one worker was set to operate the total system, the time required to complete one palletized load was approximately 5 minutes and 5 seconds. The calculated daily handling capacity was approximately 94 tons, when the daily actual working time was 8 hours. When the developed system was applied to the managerial size of 2,000 ton, the processing cost per ton of the system was decreased by 19.5%, compared with the existing 20 kg-net package-based handling. The developed post-harvest bulk handling machinery system would be a good substitute for the rapid decline and aging of rural labor.

• 산학경영연구
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• 제4권
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• pp.339-354
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• 1991

Araditionally, a business enterprise was a unit of individual economy which looked after it's own interesting. This business philosophy gave not only much wealth and advantages to the society but also caused many social problems, such as pollution, inferior goods, false advertisements, unreasonable packing and so on. Because of this criticism, it is necessary for us to fulfill the social responsibility of business and to make an accounts report about it. A business should examine itself that, for the long run, the philosophy, looking after its own interesting by means of unreasonable economical actions, is unfavorable to the business and be aware of the social responsibility of business. It is important that the business accounting should identifying, measuring and communicating on the former business actibities, but in order to help the persons interested in the business in the with their interests control and their appraising the degree of social contribution, its object should be the embodiment of social justice by giving the economic intelligences. We con get at the root of formation of corporate social accounting on this point, that it to say, we can lay it down that business activities deal with the affairs which are measured, reported, and appraised from the social view points. Givena definition of this corporate social accounting according to the general standard of business accounting. I think the persons interested in business can get useful accounting informations to make a reasonable decision from the social view points. Set forth the responsibility of accounting based on this, it is very meaningful to study in the social recognition.

• 반도체디스플레이기술학회지
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• 제19권2호
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• pp.105-109
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• 2020

Today's placement machines can pick and place thousands of components per hour with a very high degree of accuracy. The packaged semiconductor chips are inserted into a carrier at regular intervals, covered with a tape to protect the chips from external impact, and supplied in a roll form. These packaging processes also progress rapidly in a consistent direction, affecting the peelback strength between the cover tape and carrier depending on the main process conditions. In this paper, we analyzed the main process variables that affect peelback strength in the reel tape packaging process for packaging semiconductor chips. The main effects and interactions were analyzed. The peelback strength range required in the packaging process was set as the nominal the best characteristics, and the optimum process condition satisfying this was derived.

• 한국전기전자재료학회논문지
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• 제37권1호
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• pp.56-62
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• 2024

By introducing curing kinetics and chemo-rheology for the epoxy resin formulation for ultra-high voltage gas insulated switchgear (GIS) Insulating Spacers, a study was conducted to simulate the curing behavior, flow and warpage analysis for optimization of the molding process in automatic pressure gelation. The curing rate equation and chemo-rheology equation were set as fixed values for various factors and other physical property values, and the APG molding process conditions were entered into the Moldflow software to perform optimization numerical simulations of the three-phase insulating spacer. Changes in curing shrinkage according to pack pressure were observed under the optimized process conditions. As a result, it was confirmed that the residence time in the solid state was shortened due to the lowest curing reaction when the curing holding pressure was 3 bar, and the occurrence of deformation due to internal residual stress was minimized.

• Design & Manufacturing
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• 제17권1호
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• pp.20-26
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• 2023

Lab-on-a-disc is a circular disc shape of cartridge that can be used for blood-based liquid biopsy to diagnose an early stage of cancer. Currently, liquid biopsies are regarded as a time-consuming process, and require sophisticated skills to precisely separate cell-free DNA (cfDNA) and circulating tumor cells (CTCs) floating in the bloodstream for accurate diagnosis. However, by applying the lab-on-a-disc to liquid biopsy, the entire process can be operated automatically. To do so, the lab-on-a-disc should be designed to prevent blood leakage during the centrifugation, transport, and dilution of blood inside the lab-on-a-disc in the process of liquid biopsy. In this study, the main components of lab-on-a-disc for liquid biopsy are fabricated by injection molding for mass production, and ultrasonic welding is employed to ensure the bonding strength between the components. To guarantee accurate ultrasonic welding, the flatness of the components is optimized numerically by using the response surface methodology with four main injection molding processing parameters, including the mold & resin temperatures, the injection speed, and the packing pressure. The 27 times finite element analyses using Moldflow® reveal that the injection time and the packing pressure are the critical factors affecting the flatness of the components with an optimal set of values for all four processing parameters. To further improve the flatness of the lab-on-a-disc components for stable mass production, a quarter-disc shape of lab-on-a-disc with a radius of 75 mm is used instead of a full circular shape of the disc, and this significantly decreases the standard deviation of flatness to 30% due to the reduced overall length of the injection molded components by one-half. Moreover, it is also beneficial to use a quarter disc shape to manage the deviation of flatness under 3 sigma limits.