• 마이크로전자및패키징학회지
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• 제24권4호
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• pp.91-95
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• 2017

Package-On-Package (PoP) technology is developing toward smaller form factors with high-speed data transfer capabilities to cope with high DDR4x memory capacity. The common application processor (AP) used for PoP devices in smartphones has the bottom package as logic and the top package as memory, which requires both thermally and electrically enhanced functions. Therefore, it is imperative that PoP designs consider both thermal and power distribution network (PDN) issues. Stacked packages have poorer thermal dissipation than single packages. Since the bottom package usually has higher power consumption than the top package, the bottom package impacts the thermal budget of the top package (memory). This paper investigates the thermal and electrical characteristics of PoP designs, particularly the bottom package. Findings include that via and dense via-cluster volume have an important role to lower thermal resistance to the motherboard, which can be an effective way to manage chip hot spots and reduce the thermal impact on the memory package. A Cu block and dense via-cluster layout with an optimal location are proposed to drain the heat from the chip hot spots to motherboard which will enhance thermal and electrical performance at the design stage. The analytical thermal results can be used for design guidelines in 3D packaging.

• Human Ecology Research
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• 제61권2호
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• pp.233-245
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• 2023

The aim of this study was to identify community-level childcare infrastructure for infants and toddlers and to use the data to categorize community types using K-Means cluster analysis with spatial constraints. Seven indicators of childcare resource supply were used for the purpose of categorization and the results revealed six types of community cluster. Communities in the Type 1 cluster provided sufficient parks, libraries, and kindergartens, but lacked pediatric facilities and private education institutions. This cluster comprised small cities and rural areas in Gangwon-do, Gyeongsangbuk-do, Chungcheongbuk-do, and Jeollabuk-do. The Type 2 cluster had numerous pediatric facilities and childcare centers, but lacked other childcare infrastructure. This comprised small and medium-sized cities in Gyeonggi-do, some areas in Chungcheongnam-do, Chungcheongbuk-do, and Gangwon-do bordering Gyeonggi-do. The Type 3 cluster comprised Busan, Daegu, and Gyeongsangnam-do, but had insufficient childcare infrastructure as a whole. Type 4 had the largest number of childcare centers, libraries, and private education institutions and comprised Jeollabuk-do, areas near Gwangju, and Jeju-do. Type 5, consisting of Seoul, Incheon and the southern part of Gyeonggi-do had many pediatric facilities and certified childcare centers, but lacked other childcare infrastructure. Type 6, being the rural areas and islands in Jeollanam-do, had sufficient kindergartens, but other infrastructure was insufficient. These results are expected to provide local government with policy implications in terms of relieving the childcare burden on residents with infants and toddlers.

• Smart Structures and Systems
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• 제18권3호
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• pp.525-540
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• 2016

The CFRP-confined circular concrete-filled steel tubular column is composed of concrete, steel, and CFRP. Its failure mechanics are complex. The most important difficulties are lack of an available method to establish a relationship between a specific damage mechanism and its acoustic emission (AE) characteristic parameter. In this study, AE technique was used to monitor the evolution of damage in CFRP-confined circular concrete-filled steel tubular columns. A fuzzy c-means method was developed to determine the relationship between the AE signal and failure mechanisms. Cluster analysis results indicate that the main AE sources include five types: matrix cracking, debonding, fiber fracture, steel buckling, and concrete crushing. This technology can not only totally separate five types of damage sources, but also make it easier to judge the damage evolution process. Furthermore, typical damage waveforms were analyzed through wavelet analysis based on the cluster results, and the damage modes were determined according to the frequency distribution of AE signals.

• 대한산업공학회지
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• 제42권2호
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• pp.138-150
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• 2016

This study aims to analyze the structure and characteristics of the domestic online game industry using network analysis. In particular, two-mode network analysis is employed to measure the network structure, centrality, and cluster for two types of online game platforms, online games and mobile games, from 1996 to 2014. We also conduct a dynamic analysis to capture the structural changes in the ecosystem by internal and external environmental changes before and after turning point for each online game platform. It is revealed that the online game econsystem has the higher number of clusters and higher concentration ratio than those of mobile game ecosystem. In dynamic analysis, both platforms exhibit similar trends over time with the increasing number of clusters, enlargement of largest cluster's size, and decreasing concentration ratio. This study is expected to provide fruitful implications for strategic decision making of online game companies and policy making for the online game industry.

• Journal of Information Science Theory and Practice
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• 제8권4호
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• pp.6-19
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• 2020

The objective of this research is to analyze which functions make up web-based as well as mobile social media services and messengers. Services are clustered by their functionality. A total of 640 individual functions were identified, while investigating altogether 44 selected services in their web and mobile versions. Applying content analysis, functions were assigned to the services. The services were ranked by the number of implemented functions, and the functions were ranked by their occurrence in the services. Cluster analysis was applied to classify the services according to their functionality. Facebook and VKontakte were found to be the ones with the most functions; the most frequently implemented functions are support, profile, and account-related. Cluster analysis revealed six classes for mobile and seven classes for web applications. There is a noteworthy difference regarding the functionality scope between web and mobile applications of the same services. An example for this is Mendeley with 38 functions in the mobile and 91 functions in the web version. This is the first empirical attempt at clustering social media services based on their functionality.

• 한국산학기술학회논문지
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• 제19권10호
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• pp.386-393
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• 2018

한국의 군수품 산업은 국내 민간 산업직접지의 전략적인 육성 정책에 맞추어, 그 개발과 생산이 특정지역에 편중되는 경향이 있다. 하지만, 최저가 입찰제, 물류의 발달 등으로 인하여 산업직접지의 거점 클러스터와 중소 클러스터의 연관성이 낮아지고 있다. 본 연구에서는 군수품의 납품에 필수적인 공인 시험성적서 관련 정보를 군수품 품질정보 시스템을 통해 수집하고, 이에 대한 사회연결망분석을 실시하였다. 사회연결망분석은 국방품질보증기관, 시험기관, 계약 및 협력업체의 관계를 UCINET의 Two-Mode Network를 통해 분석하였으며, 데이터 간 관계의 단방향성으로 인하여 근접 및 매개 중심성 등은 계산되지 않았다. 중위 기술 산업인 무기체계 분야에서는 서울지역의 시험분석 인프라에 대한 의존도가 높아 지역 산업 클러스터의 특수성능시험과 같은 시험분석 인프라 강화가 필요한 것으로 분석되었으며, 이에 대한 정부 주도의 정책적인 지원이 필요한 것으로 판단되었다. 또한, 저위 기술사업인 전력지원체계 분야에서는 상대적으로 지역적인 시험분석 인프라를 효율적으로 활용하고 있는 것으로 분석되었고, 계약 낙찰과 관련한 전략적 사유로, 지역과 관계없이 컨소시엄을 구축하고, 계약 협력업체 지위를 전략적으로 바꾸는 등 중소 클러스터의 지역적 경계를 극복하고 있는 것으로 분석되었다. 연구결과, 군수품 산업에서 거점 클러스터와 중소 클러스터의 공간적인 불일치성이 일부 확인되었으며, 이에 대한 정책적인 제언이 필요한 것으로 판단되었다.

• 기술혁신학회지
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• 제19권4호
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• pp.848-872
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• 2016

본 연구는 경기도 남부지역의 대표적인 혁신클러스터인 판교테크노밸리를 연구대상으로 혁신클러스터의 성과 영향요인에 대한 실증분석을 통한 사례연구이다. 혁신클러스터의 평가를 위한 영향요인은 이론연구 및 문헌고찰을 통해 제도적 물리적 사회적 구성 요인으로 구분하여 도출하였다(정선양, 2012). 특히 정선양(2012)에서 제안된 클러스터 구성요인은 혁신클러스터 기능 및 역할에 대한 연구분석의 틀은 기존의 이론과 연구를 통해 통합되어, 최근 많은 연구에 의해 실증분석의 틀로 제안되고 있다(예: 임종빈. 2013; 임종빈 외, 2016; 이상욱 외, 2014). 본 연구는 기 제시된 제도적 요인, 물리적 요인, 사회적 요인을 중심으로 판교테크노밸리의 혁신클러스터의 성과에 영향을 주는 요인에 대하여 실증분석하고, 혁신클러스터내 기업들의 기술협력이 이들 영향요인에 어떠한 영향을 미치는 가를 다중회귀분석을 활용하여 분석한다. 이 같은 실증분석은 기존에 제시된 혁신클러스터의 영향요인에 대한 변별력을 제고하고, 실제적인 혁신클러스터 공간에서의 운영과 성장, 향후발전에 영향을 미치는 구성요소들을 도출하는데 유용성을 줄 것이다. 무엇보다도 본 연구는 혁신클러스터 영향요인을 도출함에 따라 혁신클러스터의 혁신평가 실증분석을 통해 지표의 변별력을 향상해주고, 새로운 지표개발 및 평가적용에 합리성 제고 등을 기여할 것이다. 직접적으로 동 연구는 연구대상 및 사례로 하고 있는 판교테크노밸리의 정책적 시사점을 제공한다.

• Communications for Statistical Applications and Methods
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• 제21권3호
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• pp.225-234
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• 2014

We propose a novel hierarchical clustering for distribution valued dissimilarities. Analysis of large and complex data has attracted significant interest. Symbolic Data Analysis (SDA) was proposed by Diday in 1980's, which provides a new framework for statistical analysis. In SDA, we analyze an object with internal variation, including an interval, a histogram and a distribution, called a symbolic object. In the study, we focus on a cluster analysis for distribution valued dissimilarities, one of the symbolic objects. A hierarchical clustering has two steps in general: find out step and update step. In the find out step, we find the nearest pair of clusters. We extend it for distribution valued dissimilarities, introducing a measure on their order relations. In the update step, dissimilarities between clusters are redefined by mixture of distributions with a mixing ratio. We show an actual example of the proposed method and a simulation study.

• 한국환경과학회지
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• 제20권3호
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• pp.373-384
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• 2011

This study aims at the examination of the relative characteristics of discharge and water quality in river basins using statistical methods. For it, water quality and discharge data was collected in observed stations of Nakdong river and carried out correlation analysis, regression analysis, factor analysis and cluster analysis. And it was investigated the applicability of water quality prediction using Nearest-neighbor method. As a result, it grasped a trenditional characteristics and mutual relations between discharge an water quality data. Therefore, this results were suggested the comprehensive data and methods for a management of water quality, effective operation and policy development in Nakdong river basin.

• 한국항행학회논문지
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• 제15권2호
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• pp.204-212
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• 2011

최근 모바일 기기의 사용 급증에 따라 모바일 애드혹 네트워크(MANET, Mobile Ad-hoc Networks)에서 사용하는 모바일 P2P(Peer to Peer)에 대한 관심이 높아지고 있으며 그에 대한 연구도 활발히 이루어지고 있다. P2P 방식은 구조적인(Structured) P2P 방식과 비구조적인(Unstructured) P2P 방식으로 분류할 수 있다. 모바일 애드혹 네트워크에서 구조적인 방식의 P2P 알고리즘은 정보의 인접성을 고려하지 않아 컨트롤 트래픽이 증가하는 문제가 있으며, 비구조적인 방식의 P2P 알고리즘은 노드 수가 많아질 경우 확장성에 문제가 있다. 그래서 구조적인 방식의 P2P 알고리즘과 비구조적인 방식의 P2P 알고리즘의 장점을 취합한 하이브리드(Hybrid) 방식의 P2P 알고리즘이 제안 되었다. 본 논문에서는 하이브리드 P2P 방식 중 클러스터 기반(Cluster-based)의 P2P 알고리즘의 컨트롤 트래픽을 분석하고, 이에 관한 최적 클러스터 구성을 도출하였다. 이러한 최적 클러스터 구성 사용시, 비구조적인 방식의 P2P 알고리즘 중 대표적인 Gnutella 보다 더 좋은 성능을 나타냄을 보였다.