• 한국측량학회지
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• 제40권4호
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• pp.261-273
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• 2022

본 연구는 시스템 다이내믹스 기법을 활용하여 성남시의 토지이용수요를 예측하고 가족구조 변화와 토지이용밀도 조정정책이 토지이용수요에 미치는 영향을 모의실험하는데 연구의 목적이 있다. 이를 위해 분석모형을 설계하고 시뮬레이션 결과를 통해 시간의 흐름에 따른 토지이용수요의 변화를 살펴보았다. 분석결과에 의하면, 2035년 기준으로 주거용지는 2.08km², 상업용지는 1.36km²의 추가 공급이 필요하고, 공업용지는 현재 공급면적으로 수요를 충족할 수 있는 것으로 나타났다. 한편, 기본 모형에서 변수값을 변경하여 세가지 정책실험을 실시하였다. 첫 번째 정책실험에서는 가구원수가 기본 모형에 비해 급격히 감소할 경우에는 주거용지가 최대 7.99km² 추가공급이 필요한 것으로 나타났다. 두 번째 정책실험에서는 아파트 용적율이 200%에서 300%로 상향하면 현재의 성남시 주거지역 공급면적으로 주거용지 수요 충족이 가능하였다. 세 번째 정책실험에서는 상업지역 평균층수를 4층에서 5층 상향하고 상업지역 건폐율을 80%에서 85%로 상향하더라도 상업용지의 수요가 성남시 상업지역 공급면적을 초과하는 것으로 나타났다. 본 연구는 시스템 다이내믹스를 활용하여 토지이용수요 예측의 새로운 분석모형을 제시하고, 성남시의 실제 도시계획 현황 및 통계치를 적용하여 모형을 실증하였다는데 연구의 의의가 있다. 향후 성남시 토지이용수요 예측 및 분석 모형의 정교화를 위한 후속연구가 이루어져야 할 것이다.

• 한국시스템다이내믹스연구
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• 제9권2호
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• pp.5-25
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• 2008

This paper analysed the impact of return policy as a coordination mechanism for decentralized supply chain with one capacitated supplier and two competing retailers under random demand distribution. In this study, Shortage gaming also considered to reflect a competing environment of two retailers. System dynamics approach was used to model the baseline two echelon supply chain and return policy on it. Given each of 4 experiment settings being used for 100 simulations with different random seeds, 400 random samples were used in a t-test. The result show that return policy significantly enhance the supply chain profits and fillrates. The analysis suggest that the supply chain performance can be build up by implementing a return policy even though under consideration of a capacitated supplier and competing retailers.

• 한국컴퓨터정보학회논문지
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• 제21권2호
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• pp.1-7
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• 2016

In this paper, we propose in this paper present a novel locality data allocation policy as COLD(Correlated Locality Data) allocation policy. COLD is defined as a set of data that will be updated together later. By distributing a COLD into a NAND block separately, it can preserve th locality. In addition, by handling multiple COLD simultaneously, it can obtain the parallelism among NAND chips. We perform two experiment to demonstrate the effectiveness of the COLD data allocation policy. First, we implement COLD detector, and then, analyze a well-known workload. And we confirm the amount of COLD found depending on the size of data constituting the COLD. Secondly, we compared the traditional page-level mapping policy and COLD for garbage collection overhead in actual development board Cosmos OpenSSD. Experimental results have shown that COLD data allocation policy is significantly reduces the garbage collection overhead. Also, we confirmed that garbage collection overhead vary depending on the COLD size.

• 한국정보처리학회논문지
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• 제7권2S호
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• pp.621-628
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• 2000

A retrieval performance of VOD sever is estimated by how quickly it services popular videos to users and how many users it is able to service. Each video data is placed on heterogeneous disks and placement techniques are various, retrieval performance is under the control of these elements, so that a retrieval performance is affected by placement policy. In this paper, we place video data considering their characteristics, especially, we place videos distributively according to their popularity. To verify our policy, we make various environment of experiment, estimate a placement policy using popularity of videos and a contrary policy, and compare them.

• 한국경영과학회지
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• 제30권1호
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• pp.17-26
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• 2005

There is the uncertainty of demands at each retailer in the supply chain. To satisfy customers' demand, retailer must have enough inventory. Nevertheless, stockout is occurred for some retailers. A lateral transshipment policy can be effectively used to deal with stockout. The new lateral transshipment policy, referred to service level adjustment (SLA), is suggested. The difference between SLA and previous policies is the integration of an emergency lateral 'transshipment with a preventive lateral transshipment to efficiently respond customers' demand in the proposed policy. Additionally, the service level to decide the quantity of products is considered. Simulation experiment is executed to treat stochastic factors in the two-echelon supply chain. The proposed policy can reduce total cost and is more effective to the change of demand, penalty cost, and ordering cost than the currently used policies.

• 산업경영시스템학회지
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• 제38권2호
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• pp.91-100
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• 2015

In this study, we propose an efficient two-phase heuristic policy, called an acceptance tolerance control policy, for Infrastructure as a Service (IaaS) cloud services that considers both the service provider and customer in terms of profit and satisfaction, respectively. Each time an IaaS cloud service is requested, this policy determines whether the service is accepted or rejected by calculating the potential for realizing the two performance objectives. Moreover, it uses acceptance tolerance to identify the possibility for error with the chosen decision while compensating for both future fluctuations in customer demand and error possibilities based on past decisions. We conducted a numerical experiment to verify the performance of the proposed policy using several actual IaaS cloud service specifications and comparing it with other heuristics.

• 융합보안논문지
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• 제18권3호
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• pp.3-9
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• 2018

DDPG(Deep Deterministic Policy Gradient)알고리즘은 인공신경망과 강화학습을 사용하여 학습하는 알고리즘이다. 최근 많은 연구가 이루어지고 있는 강화학습과 관련된 연구 중에서도 DDPG 알고리즘은 오프폴리시로 학습하기 때문에 잘못된 행동이 누적되어 학습에 영향을 미치는 경우를 방지하는 장점이 있다. 본 연구에서는 DDPG 알고리즘을 응용하여 자전거를 자율주행 하도록 제어하는 실험을 진행하였다. 다양한 환경을 설정하여 시뮬레이션을 진행하였고 실험을 통해서 사용된 방법이 시뮬레이션 상에서 안정적으로 동작함을 보였다.

• Industrial Engineering and Management Systems
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• 제11권2호
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• pp.134-141
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• 2012

It is difficult to find an appropriate ordering policy for a many types of items. One of the reasons for this difficulty is that each item has a different demand trend. We will classify items by shipment trend and then decide the ordering policy for each item category. In this study, we indicate that categorizing items from their statistical characteristics leads to an ordering policy suitable for that category. We analyze the ordering policy and shipment trend and propose a new method for selecting the ordering policy which is based on finding the strongest relation between the classification of the items and the ordering policy. In our numerical experiment, from actual shipment data of about 5,000 items over the past year, we calculated many statistics that represent the trend of each item. Next, we applied the canonical correlation analysis between the evaluations of ordering policies and the various statistics. Furthermore, we applied the cluster analysis on the statistics concerning the performance of ordering policies. Finally, we separate items into several categories and show that the appropriate ordering policies are different for each category.

• 한국유기농업학회지
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• 제18권3호
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• pp.291-313
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• 2010

The objective of this paper is to apply choice experiment methods to estimate non-market value of organic farming and its policy implication. A preliminary survey shows that the attributes of organic farming are reduce environmental pollution, bio-diversity improvements, cultural diversity improvements and maintain local community, reduce green-house gas emissions, energy saving, landscape improvements and tax for organic farming improvement policy. Questionnaire was eight different choice sets presented to each respondent. Implicit values of the attributive levels of organic farming have been calculated into tax money costs per house. This paper compared the six feasible scenarios in terms of willingness to pay per year. This study is expected to contribute to government's organic farming policies and quantitative information related to practice of organic farming.

• 산업경영시스템학회지
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• 제39권3호
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• pp.30-38
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• 2016

Shuttle-Based Storage/Retrieval System (SBS/RS) is relatively new to industry. The system is in the category of Automated Storage/Retrieval System (AS/RS), but it is different in that the SBS/RS uses shuttles as Storage/Retrieval (SR) machine instead using a stacker crane. The shuttles are assigned to each tier on multi-tier system and operated for pick-up or drop-off order. Since the system can handle multiple orders simultaneously, it can provide much higher throughput than that of general AS/RS with single stocker crane. Thus, this new system is well fit to recent tendency of increasing small quantity batch production and orders. One of the drawback of this system is that it needs a lot of investment to set up. The efficient operation of the system would be one of the critical matters to increase economic efficiency of capital investment. In this study, we focused on the dwell point policy for shuttles to find efficient way of operating the system. There are four basic policies for the dwell point and we had simulation-based experiment for two different scenarios based on the speed of the shuttle and inter-arrival time of the loads coming to the system combined with four different policies. As it was mentioned above, this SBS/RS relatively new to the field and there is no such experiment shown on previous research and the study of dwell point policy for this SBS/RS could provide the direct comparison of each policy with different hardware specification; the capability of the system. The policy that achieves most efficient operation among the given environment is proposed and the usability of the system is discussed.