• Information and Communications Magazine
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• v.32 no.11
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• pp.41-49
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• 2015

현대 사회는 스마트폰 사용량의 급증으로 인한 모바일 트래픽의 폭발적인 증가와 IoT(Internet of Things)를 비롯한 융복합 유무선 서비스의 확대 등으로 국가적으로 한정적 자원인 주파수의 효율적 사용을 인한 대책 마련이 시급한 실정이다. 이에 미국 및 유럽을 중심으로 다양한 용도의 무선기기들이 한정적 주파수 대역을 효율적으로 이용하기 위한 방안으로 주파수 공동사용에 대한 정책도입 및 연구개발이 지속적으로 추진되고 있다. 본 고에서는 수요 대비 공급 부족 현상이 점차 심각해 지고 있는 한정적 주파수 자원의 효율적 이용을 위한 대안으로 급부상하고 있는 주파수 공동사용 기술에 대한 국내외 관련 정책 및 기술추진 현황에 대해 소개하고자 한다. 특히 본 고에서는 2010년 국가광대역계획(NBP, National Broadband Plan) 발표를 시작으로 전 세계적으로 주파수 공동사용 추진에 있어 가장 적극적인 행보를 보여주고 있는 미국에서의 3.5GHz 대역 주파수 공동사용을 위한 전파규칙인 CFR(Code of Federal Regulation) Part 96의 주요 내용을 자세히 소개하고자 한다. 본 고의 II장에서는 국내외에서 진행되고 있는 대표적인 주파수 공동사용 정책추진 현황에 대해 소개하였으며, III장에서는 올해 4월 최종 전파규칙이 발표된 미국의 SAS(Spectrum Access System) 기반 주파수 공동사용 전파규칙에 대해 소개하였다. 또한 IV장에서는 SAS 기반의 주파수 공동사용 기법 및 기존에 개발되고 있는 다양한 동적 스펙트럼 접속 기법들을 미국 내 주요 도심지역에 적용하기 위한 대규모 테스트베드 프로그램인'Model City'프로그램 소개 및 결론을 통하여 주파수 공동사용 도입의 당위성을 설명하고자 한다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.2 no.1
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• pp.108-120
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• 1998

많은 주거용 및 상업용 건물에서 콘크리트 구조물이 사용되고 있는데 콘크리트 슬래브 아래의 기초부분에 공동이 생기는 경우가 종종 발견되었다. 이 현상은 진동하중, 반복되는 충격, 흙의 유실, 혹은 불량시공 등 여러가지 이유에 의해 발생할 수 있다. 이러한 현상은 구조물의 지지력을 저하시키고 결국 수명을 단축시키는 원인이 되므로 이러한 문제는 일찍 발견되고 조치가 취해질수록 구조물의 수명을 연장시킬 수 있을 것이다. 이러한 공동이 슬래브 아래에서 형성되고 커져가는 과정을 모니터할 수 있으면 현재 상태에서 지지력을 결정하고 또한 앞으로 남은 수명을 예측함으로써 적절한 유지보수계획을 세우는 데에 큰 도움이 될 것이다. 이 연구에서는 음파와 응력파, 특히 표면파가 슬래브 아래의 공동을 찾아내는데 이용되었고 두 가지 방법의 효과가 상호 비교되었다. 두개의 콘크리트 슬래브를 만들어 이용했는데 하나는 미리 공동이 만들어져 있었고 다른 하나에는 공동이 없었다. 공동이 없던 슬래브는 처음 손상안된 상태에서 실험을 한 후 나중에 하부에 공동을 만들어 다시 실험하였다. 실험결과와 실제 공동의 위치가 잘 일치되는 것으로 나타났다. 응력파를 이용하는 방법과 음파를 이용하는 방법사이의 장단점이 비교검토되었고 실험의 표준방법과 결과에 대한 일반적인 기준이 확립되어야 하는 필요성에 대해서도 설명되었다.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.538-538
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• 2012

최근 기후변화에 따른 이상홍수의 발생으로 인하여 댐의 수문학적 안정성 확보가 필요하다. 이에 따라 댐의 비상여수로를 건설하여 이상홍수에 대비한 대책을 마련하고 있다. 여수로의 운영상 고유속의 흐름이 방류되는데 이때 공동현상이 발생하며, 공동현상으로 인해 발생된 공동이 파괴되면서 구조물에 큰 피해를 주고 있다. 이러한 피해예방을 위해 현재까지 개발된 가장 경제적이고 효과적인 대책은 공기혼입장치이며, 국내에는 최근에 적용되고 있으나, 세부적인 설계기준과 설계기법, 절차등이 부족한 현실이다. 본 연구에서는 여수로 구조물을 대상으로 발생하는 공동현상에 대해서 이론적, 실험적인 분석을 실시하고자 한다. 공동현상에 대한 이론적인 배경과 최근의 연구동향을 분석하고, 국내 기존댐에 적용한 공기혼입장치 설치에 대해서 사례연구를 실시하여 적정성을 검토하였다. 또한 여수로의 대표단면인 개착식 여수로의 구형단면에 대해서는 주암조절지댐을 선정하고 터널식 여수로의 원형단면에 대해서는 임하댐 비상여수로를 대상구조물로 선정하여 각각 1차원 수치해석을 실시한 결과를 토대로 공기혼입장치의 위치 및 최적규모를 산정하고자 한다. 1차원 수치해석을 통해 분석된 공동현상 및 공기혼입장치에 대해서 3차원 수치해석을 실시하여 압력변화 및 공기혼입량등 공기혼입장치의 설치전과 설치후에 대한 효과를 검증하고 마지막으로 수리모형실험을 실시하여 1차원, 3차원 수치해석 결과에 대한 검증과 구조물의 안정성 증대를 확인하고, 추후 기타 여수로 구조물의 설계시 참고할 수 있는 기초자료가 될 수 있도록 하고자 한다.

• Journal of Korean Society of Transportation
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• v.17 no.2
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• pp.41-53
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• 1999

The rate of automobile ownerships has been increased significantly in multi-family housing sites so that government has made new parking regulations increasing the rate of parking supply by the high demand of parking lots in multi-family housing sites. However, the new regulation of parking supply has several problems that it applies to only new multi-family housing sites and disregards to the locational distinctions around the sites. It also has reduced to the open spaces in the sites and increased the price of housing units especially to the small size units of multi-family housing sites by increasing the number of underground parking lots. Furthermore, the residents have not been equal opportunity to access their parking lots even though they have been charged to equal amount of financial burden for the construction of underground parking lots. This research aims to relieve above problems by analysing parking supply and demand management strategies both domestic and foreign countries, and suggest to new parking management system for multi-family housing sites in 21st Centuries. This research reveals that most of multi-family housing sites want to be applied 1) diverse parking supply regulations considering the locational distinctions of sites, 2) parking lot ownership programs, 3) charging parking fees to second vehicles, 4) increasing parking lots both in the sites and around the sites, 5) enforcing police power to the parking violation vehicles to their sites. Especially, the multi-family housing sites consisting of small & medium size of units and locating in small & medium size of cites strongly want to be accepted new Parking regulations considered their locational and social distinctions and applied police power to the parking violation vehicles in their sites compared to the other multi-family housing sites.

• The Journal of Society for e-Business Studies
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• v.23 no.1
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• pp.23-36
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• 2018

This study analyzed the causal relationship between cooperation elements and the performance of joint R&D and verified the mediating effect of collaborative efforts. Cooperation elements consist of strategic agreement, complementation of resources, trust and absorption capacity, and influence the intention to participate in the joint R&D. The purpose of this study is to identify the effects of the cooperation elements and collaborative efforts on the short-term and long-term performance of the joint R&D. The results are summarized as follows: First, it is verified that strategic agreement, complementation of resources, trust and absorption capacity constitute the second order factor of cooperation elements, which positively affects the joint R&D performance. Second, it is verified that collaborative effort play a role as a mediating factor in the relationship between joint R&D performance and cooperation elements. Specifically, it was confirmed that positive effects on short-term performance of the joint R&D can be increased through cooperative efforts. However, in the case of long-term performance, the effects of collaborative efforts could not be confirmed.

• Journal of the Korean Geosynthetics Society
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• v.16 no.2
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• pp.23-33
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• 2017

Due to the rapid development of cities, densities and heights of urban structures are increased, and much larger and more underground spaces are being developed accordingly. Increasing development of underground spaces has induced more ground sinks and underground cavities. Therefore, safety of people is threatened by potential ground collapses and possible accidents, which may result from underground cavity. To actively respond against potential danger of ground sink, evaluation of existing cavity grade and development of recovery procedure are important. There exists the ground sinking management grade system of expressway developed as local standards in Japan. Recently, ground sinking management grade system of Seoul was developed with consideration of road and asphalt conditions. In this study, 209 underground cavities of ${\bigcirc}{\bigcirc}$ area were explored and their cavity shapes and grades were evaluated based on both ground sinking management grade systems of Japan and Seoul. Comparison is made between cavity grades evaluated based on both grading systems from Japan and Seoul. As a result of comparative analysis, the conservatively-estimated cavity grades requiring emergency restoration based on the Japanese management grade system of expressway result from neglection of layer thickness of surface pavement, considering only width and cover depth of a cavity.

• The Korean Journal of Archival Studies
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• no.38
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• pp.225-264
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• 2013

The Purpose of this study is to analyze an active discussion in North America about the issue of community archives governance which mainly focused on 'participatory archives' model and from it, draws implications for the present stage of domestic community archives development. Traditionally in the United States and Canada, local community archives have been built mostly by mainstream cultural institutions such as public archives, public libraries, museums, and historical societies as a part of comprehensive documentation of the society at large. At the same time, they have been processed and managed in accordance with the institution's collection development policy. As a result, most community archives in North America are characterized as top-down community archives model (in contrast with down-up model of 'independent' community archives as a part of grass roots movement in the UK). Recently, the community archives in North America with these characteristics try to overcome their limitations, which result in 'the others' of community archives, through governance, that is, community-institution partnership. Participatory archives model which assumes active community participation in all archives processes is being suggested by archival communities as the effective alternative of governance model of top-down community archives. This discussion of community archives governance suggests progressive direction for the present stage of domestic community archives, which has been built mostly by various mainstream cultural institutions and still has been stayed in 'about the community' stage. Particularly, community outreach strategies that participatory archives model concretely suggests are useful as a conceptual framework in building community archives based on community-institution partnership in reality.

• Journal of the Korean Geosynthetics Society
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• v.17 no.1
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• pp.55-64
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• 2018

The purpose of this study is to evaluate the suitability of emergency underground cavity restoration method filling cavity with expansive material based on numerical analysis. For the numerical analysis, experiments were conducted to evaluate properties of expansive material. Based on the measured expansion pressure of the expansive material from the experiment, behavior of underground cavity restoration with various cavity dimensions (variation of height and width of rectangular-shape cavity) was numerically assessed. As a result of analysis, the vertical displacements of the top and bottom of cavity were significantly influenced by the cavity width and lateral displacements of cavity sides were highly dependent on cavity height. These vertical and lateral displacements were increased with increasing expansion pressure of expansive material. Also, when the expansion pressure was applied, the vertical displacement of the upper surface layer of the road was less dependent on cavity height, and was greatly influenced by cavity width.

• Journal of the Korean Society for information Management
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• v.31 no.3
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• pp.153-179
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• 2014

This study explores the characteristics of centrality measures for analyzing researchers' impact and structural positions in research collaboration networks. We investigate four binary network centrality measures (degree centrality, closeness centrality, betweenness centrality, and PageRank), and seven existing weighted network centrality measures (triangle betweenness centrality, mean association, weighted PageRank, collaboration h-index, collaboration hs-index, complex degree centrality, and c-index) for research collaboration networks. And we propose SSR, which is a new weighted centrality measure for collaboration networks. Using research collaboration data from three different research domains including architecture, library and information science, and marketing, the above twelve centrality measures are calculated and compared each other. Results indicate that the weighted network centrality measures are needed to consider collaboration strength as well as collaboration range in research collaboration networks. We also recommend that when considering both collaboration strength and range, it is appropriate to apply triangle betweenness centrality and SSR to investigate global centrality and local centrality in collaboration networks.

• Journal of Korean Library and Information Science Society
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• v.44 no.2
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• pp.167-195
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• 2013

According to the Korean Library Act, a regional representative library is fully responsible for the integrated management of all collections held by local libraries. It intends to resolve space problem for collections and to prepare room for new materials in local libraries. Under the Act, a regional representative library should make a plan for a regional repository library to accomodate overflows from local library collections as soon as possible. The purpose of this study is to figure out the meanings of 'regional repository library' as a cooperative storage facility of local library collections, and to suggest the proper solutions for developing a regional repository library with case of Busan metropolitan city. To the end, this study (1) examined the extent of space shortage in local libraries of Busan, (2) assessed the needs of both local libraries and library users for a regional repository library, and finally, (3) suggested the detailed procedure and methods for establishing and managing a regional repository library in Busan metropolitan city.