• The Journal of Korean Association of Computer Education
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• v.18 no.4
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• pp.55-62
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• 2015

Recommender systems through collaborative filtering has been utilized successfully in various areas by providing with convenience in searching information. Measuring similarity is critical in determining performance of these systems, because it is the criteria for the range of recommenders. This study analyzes distributions of similarity from traditional measures and investigates relations between similarities and the number of co-rated items. With this, this study suggests a method for selecting reliable recommenders by restricting similarities, which compensates for the drawbacks of previous measures. Experimental results showed that restricting similarities of neighbors by upper and lower thresholds yield superior performance than previous methods, especially when consulting fewer nearest neighbors. Maximum improvement of 0.047 for cosine similarity and that of 0.03 for Pearson was achieved. This result tells that a collaborative filtering system using Pearson or cosine similarities should not consult neighbors with very high or low similarities.

• Proceedings of the KAIS Fall Conference
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• 2009.05a
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• pp.817-820
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• 2009

신종 및 재출현 전염병이 지속적으로 유행하고 해외 전염병의 국내유입가능성이 증대됨에 따라 국립검역소의 검역관리 사업의 효율성 평가는 매우 중요하다. 연구는 평가 구성요소 사이의 상대적 중요도, 즉 가중치(weight) 부여에 있어서 과학적 타당성을 인정받고 있는 계층분석절차(Analytical Hierarchy Process; AHP) 기법에 의한 이원비교방법을 사용하여 설정하였다. AHP기법은 복잡한 다기준 의사결정문제(multi-criteria decision making problem)를 계층화하여 단순화 체계화시킴으로써 그 영향도를 계량화하는데 탁월한 기법이라는 평가를 받고 있다. 실제 측정에 있어서는 본 모형을 이용하여 얻어졌다. 대영역(기관평가영역, 서비스 및 프로그램평가 영역), 중영역(투입, 과정, 결과, 검역업무, 검사업무, 위생관리업무, 병원체조사감시업무, 전염병예방홍보 교육업무)으로 구분하여 최종적으로 평가지표로 선정된 지표는 실제 국립검역소 사업에 적용하였으며, 이에 대한 최소한의 평가지표를 최종 선정하여 향후 국립검역소사업 평가체계를 보다 체계화 하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.5
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• pp.153-159
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• 2018

In recent years, the development of weapons systems in the field of defense research and development has become increasingly large, complex, and long-term, and so have budgets and the time spans involved. In order to improve this, the Weapon Systems Requirement Verification Committee, which benchmarked the preliminary feasibility of the private sector, was established to verify the appropriateness of requirements, and the necessity and priority of the projects. This research proposes a methodology for analyzing and prioritizing proposed weapons systems for effective and strategic allocation of defense budget funding. First, the evaluation factors that can be used in the defense sector were assessed by analyzing the related fields. We set the weighting of items by using the analytical hierarchy process for technical risk assessment and technical profitability evaluation. After that, we applied the methodology to 32 weapons systems and analyzed the results. In conclusion, through this study, it was possible to analyze profitability dimensions overlooked in the existing methodology.

• International Journal of Highway Engineering
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• v.13 no.1
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• pp.239-249
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• 2011

The behavior of the fiber reinforced concrete (FRC) base under environmental loads was analyzed numerically as a fundamental study to develop a high structural and functional performance composite pavement system in which the base was formed using FRC and the asphalt or cement concrete surface was placed on it. A two-dimensional finite element model of the FRC base was developed and the sensitivity study was performed with the variables including slab thickness of base, thermal expansion coefficient, elastic modulus, and tensile and compressive strengths. The crack spacing and crack width were selected as representatives of the base behavior. The effects of the selected variables on the crack spacing and crack width were analyzed and the sensitive variables were determined. The results of this study could be useful to determine the optimal material properties of the FRC base for combining well with the surface materials.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.11
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• pp.8021-8029
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• 2015

This study obtains design assessment indexes that should be considered in order to improvements of the public space was to analysis the importance in the public officials/academics and practitioners side. Obtained assessment topics in accordance with characteristic of public space through previous research to them and after a detailed selection indicators was so lead through the FGI. Derived surface was subjected to the significance analysis AHP through the survey expert. For this study, the importance of the public space are working professionals usability, publicness, environment, connectivity, identity, spatiality the order, public officials/academics usability, environment, connectivity, identity, spatiality, publicness the order. In addition, professionals working in the comprehensive analysis of the most important priority was to recognize safety, public officials/academics of the most important element appeared to have cleanliness. The results obtained in this study will be used as an index that can be used in planning and evaluation for consideration of the next improvement of public space.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.26 no.1
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• pp.8-13
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• 2016

A top-seeded solution growth (TSSG) is a method of growing SiC single crystal from the Si melt dissolved the carbon. In this study, multiphysics modeling was conducted using COMSOL Multiphysics, a commercialized finite element analysis package, to get analytic results about electromagnetic analysis, heat transfer and fluid flow in the Si melt. Experimental results showed good agreements with simulation data, which supports the validity of the simulation model. Based on the understanding about solution growth of SiC and our set-up, crystal growth was conducted on off-axis 4H-SiC seed crystal in the temperature range of $1600{\sim}1800^{\circ}C$. The grown layer showed good crystal quality confirmed with optical microscopy and high resolution X-ray diffraction, which also demonstrates the effectiveness of the multiphysics model to find a process condition of solution growth of SiC single crystal.

• Journal of KIISE:Software and Applications
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• v.34 no.10
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• pp.900-909
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• 2007

This paper describes an experiment on the evaluation of human sensibility by monitoring responses to changes In the frequency and amplitude of a tactile display system. Preliminary tasks were performed to obtain effective adjectives concerning texture perception. The number of collected adjectives was originally 33. This number of adjectives was reduced to 14 by a suitability survey that asked whether an adjective is suitable for expressing a texture feeling. Finally after performing a semantic similarity evaluation, the number of adjectives was further reduced to ten and these ten were used in the main experiment. In the main experiment, selected sandpaper types and 15 selected combinations of frequencies and amplitudes of a tactile display were utilized to quantitatively evaluate the ten adjectives using a bipolar seven-point scale. The data show that a relationship exists between the independent variables(frequency, amplitude, and grit site) and the dependent variable(perceived texture). That is, the change of frequency and amplitude is directly related to perceived roughness or essential elements of human tactile sensitivity found in the preliminary experiment.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2002.05a
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• pp.50-57
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• 2002

소프트웨어 자제나 소프트웨어 관련 기업의 평가를 위한 기존의 평가 시스템들은 소프트웨어 조직의 다양성과 측정 요소들의 정성적인 특성 등으로 측정이 어려웠고 이로 인해 조직의 프로세스, 기업환경이나 제품 기능성과 같은 제품위주의 단편적인 측면만을 고려한 평가 시스템들이 주를 이루어왔다. 따라서 잠재적 고객의 소프트웨어 구매나 제휴 업체 선정 등에 있어 일부 제한적인 정보만을 이용할 수 있었고, 이로 인해 소프트웨어나 소프트웨어 업체의 결정에 있어서 합리적이며 적절하고 빠른 의사결정을 하는 데 한계가 있었다. 본 연구에서는 기존의 평가 시스템들이 안고 있는 한계를 극복하여, 기업이 가지고 있는 역량에 대한 측면과 기업이 제공하는 고객 서비스 그리고 제품에 대한 고객 만족도 측면을 동시에 고려할 수 있는 평가 시스템(SISW)을 개발하였으며. 이를 국내 유수한 소프트웨어 기업을 대상으로 적용하여 그 결과를 분석, 제시하였다.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.18 no.1
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• pp.59-67
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• 2009

The purpose of this study is to provide a decision support to select an appropriate layered manufacturing(LM) machine that suits the application of a part. Selection factors include concept model, form/fit/functional model, pattern model far molding, material property, build time and part cost that greatly affect the performance of LM machines. However, the selection of a LM is not an easy decision because they are uncertain and vague. For this reason, the aim of this research is to propose hybrid multiple attribute decision making approaches to effectively evaluate LM machines. In addition, because subjective considerations are relevant to selection decision, a fuzzy logic approach is adopted. The proposed selection procedure consists of several steps. First, we identify LM machines that the users consider After constructing the evaluation criteria, we calculate the weights of the criteria by applying the fuzzy Analytic Hierarchy Process(AHP) method. Finally, we construct the fuzzy Technique of Order Preference by Similarity to Ideal Solution(TOPSIS) method to achieve the ranking order of all machines providing the decision information for the selection of LM machines.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.229-229
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• 2023

강화학습은 에이전트(agent)가 주어진 환경(environment)과의 상호작용을 통해서 상태(state)를 변화시켜가며 최대의 보상(reward)을 얻을 수 있도록 최적의 행동(action)을 학습하는 기계학습법을 의미한다. 최근 알파고와 같은 게임뿐만 아니라 자율주행 자동차, 로봇 제어 등 다양한 분야에서 널리 사용되고 있다. 상수도관망 분야의 경우에도 펌프 운영, 밸브 운영, 센서 최적 위치 선정 등 여러 문제에 적용되었으나, 설계에 강화학습을 적용한 연구는 없었다. 설계의 경우, 관망의 크기가 커짐에 따라 알고리즘의 탐색 공간의 크기가 증가하여 기존의 최적화 알고리즘을 이용하는 것에는 한계가 존재한다. 따라서 본 연구는 강화학습을 이용하여 상수도관망의 구성요소와 환경요인 간의 복잡한 상호작용을 고려하는 설계 방법론을 제안한다. 모델의 에이전트를 딥 강화학습(Deep Reinforcement Learning)으로 구성하여, 상태 및 행동 공간이 커 발생하는 고차원성 문제를 해결하였다. 또한, 해당 모델의 상태 및 보상으로 절점에서의 압력 및 수요량과 설계비용을 고려하여 적절한 수량과 수압의 용수 공급이 가능한 경제적인 관망을 설계하도록 하였다. 모델의 행동은 실제로 공학자가 설계하듯이 절점마다 하나씩 차례대로 다른 절점과의 연결 여부를 결정하는 것으로, 이를 통해 관망의 레이아웃(layout)과 관경을 결정한다. 본 연구에서 제안한 방법론을 규모가 큰 그리드 네트워크에 적용하여 모델을 검증하였으며, 고려해야 할 변수의 개수가 많음에도 불구하고 목적에 부합하는 관망을 설계할 수 있었다. 모델 학습과정 동안 에피소드의 평균 길이와 보상의 크기 등의 변화를 비교하여, 제안한 모델의 학습 능력을 평가 및 보완하였다. 향후 강화학습 모델을 통해 신뢰성(reliability) 또는 탄력성(resilience)과 같은 시스템의 성능까지 고려한 설계가 가능할 것으로 기대한다.