• Journal of the Korean Society for Railway
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• v.10 no.5
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• pp.511-519
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• 2007

This study provides comprehensive design improvements covering technical issues concerning life safety matter In case of fire train stoppage in the middle of a tunnel. Recently Government announced that most of subway platforms will have screen doors in 3 years. Therefore, many fire safety engineers considered that they may contribute on life safety on train stoppage in tunnel. Especially The screen door can protect platform from smoke along tunnel ceiling when fire train stopped in tunnel. The study showed that platform ventilation ducts and the a tunnel ventilation chimney in the middle of tunnel in exiting subway tunnel could not guarantee life safety ability in terms of RSET vs. ASET comparison. Furthermore during evacuation process many peoples may be threatened from the smoke spread from the origin of fire. Although only additional vertical route can be installed in tunnels In order to decrease RSET, it will costs high or no spaces remains in outside on the road. The study suggested that increase of ASET can be best solution without additional escape route, therefore alternative design methods suggested on the base of simulation results. Finally the study shows alternative methods can give good result in terms of evacuation performance evaluation. The evacuation performance evaluation helps the decision-maker to determine the preferred alternatives or upgrades to existing tunnel infrastructure and other measure to meet safety objectives. Finally, the study details the effectiveness of measures the can be taken to reduce the risk of incidents in subway tunnels.

• Journal of the Earthquake Engineering Society of Korea
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• v.14 no.6
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• pp.1-9
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• 2010

Most of shear wall structures require openings in shear walls and thus shear walls are linked by floor slabs or coupling beams resulting in the coupled shear wall structures. When these structures are subjected to seismic excitations, excessive shear forces are induced in coupling beams. Accordingly, brittle failure of coupling beams may occur or shear walls may yield first. To avoid this problem, damping devices can be installed in coupling beams. It can increase the vibration control effect and improve the seismic resistance performance of the coupled shear wall structure by avoiding stress concentration and the brittle failure of coupling beams. Based on this background research, an LRB (lead rubber bearing) was introduced in the middle of the coupling beam in this study and the authors investigated the seismic response control effect and stress distribution of the proposed system. To this end, a modeling technique that can effectively predict the structural behavior of coupled shear wall structures has been proposed. With this proposed technique, time history analyses of the example coupled shear wall structure subjected to seismic excitation were performed and the vibration control effects of the seismic responses were investigated.

• The Journal of the Korea Contents Association
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• v.20 no.5
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• pp.11-22
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• 2020

The academic credit banking system is an educational system to implement a lifelong learning society. Students who meet the requirements of this system can achieve academic degrees equivalent to those of junior colleges or four-year universities. Credits and degree information of these students are recorded and managed by the central institution. However, this system can cause security problem such as hacking due to centralized management. In this paper, we propose an academic credit banking system which can manage credits and degree information based on blockchain technology. In the proposed system, credits and degree information are stored in block and managed in the public ledger in a permanent manner. Blocks are connected in the form of blockchain on a distributed network to improve security problems such as hacking and manipulation. Also, the efficiency of credit bank management can be increased because the functions of the central institution are distributed to the network participants. The prototype of the proposed system was implemented on the Go-Ethereum platform and experimentally verified the blockchain information among participating organizations using smart contracts.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.5
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• pp.161-169
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• 2018

This study presents a time synchronization system in decentralized structure by using the blockchain, a core technology of Bitcoin introduced by Satoshi Nakamoto in 2008. In this study, Getting away from existing time synchronization system in centralized structure, A blockchain network has completely decentralized structure using public blockchain. In decentralized structure, Only certain peers among the peers that participate in a blockchain network access the NTP server. Therefore, others can synchronize time without having to go to public network. Furthermore if appropriate time synchronization cycles are established for each peer, time synchronization can be maintained even when connection to public network is completely lost. A time synchronization system in this study has advantages of p2p system and can be also guaranteed reliability and stability because it used digital signature, merkle tree, consensus algorithm which are core characteristics of block chains.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.11
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• pp.879-894
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• 2013

Recently, due to a explosive growth in the mobile Internet traffic, the problem of excessive data traffic handling on core network and thus scalability problem have been magnified in 3GPP LTE/SAE networks. Current LTE/SAE network based on the central P-GW (PDN Gateway) used as mobility anchor cannot deal with such demand for exponentially increasing mobile Internet traffic. In this paper, we propose a new LTE/SAE network architecture supporting distributed P-GWs and corresponding distributed mobility management to solve these problems. For this, in addition to the deployment of such distributed P-GWs, we propose a dynamic and distributed mobility management by distributing MMEs (Mobility Management Entities) which dynamically manages the location information of a UE's PDN connection, and also propose a handover procedure of such PDN connections by using the proposed distributed P-GWs and MMEs. The performance of the proposed dynamic and distributed LTE/SAE network system is compared with the current LTE/SAE network system in terms of handover latency and network throughput.

• The Journal of the Korea Contents Association
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• v.12 no.12
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• pp.661-671
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• 2012

The purpose of this study was to analyze the core policies of local government directors by performing centrality analysis on their core policies using network text analysis method. From the research results, it was verified to some extent that major policies of local government directors were changing during the path to arrive at 5th civil election. However, according to policy type by Peterson (development policy, allocation policy and redistribution policy) it was found that they still focused on development policies. However, it is encouraging that the government directors elected in the 5th election started to pay attention to 'Culture' which is one of allocation policies.

• Design Convergence Study
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• v.17 no.6
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• pp.127-143
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• 2018

Although women's status in society have been improving, the existing space for women's main activities is still perceived as limited in scope. In this respect, this study analyzes the domestic literature on women's space and discusses the space for women with intent to gain some implications for further studies on space associated with women. Articles on women's space were sub-classified in light of keywords, years of publication, sites, purposes, methods and journal categories, followed by network and frequency analyses. In addition, focus group interview was conducted to explore a new orientation for further studies. The degree centrality was found high in such keywords as 'women's clinics', 'CPTED', 'women-friendly cities' and 'femininity'. In addition, there is a paucity of studies on women's space. Recent studies have diversified the scope of women's space. At the same time, macroscopic 'urban' approaches to women's space have lately been emerging. Finally, the focus group interview on women's space highlighted the needs to further studies about 'femininity, 'maternity', and 'gender equality' in space, and 'safe environment'.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2004.06a
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• pp.353-354
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• 2004

사용후 핵연료의 조성을 분석하거나 또는 반사전자상과 2차 전자상 등으로 시료를 관찰하기 위해서는 핫셀(Hot cell)에 증착기(coater)를 설치하여 시료표면을 전도성 물질인 탄소 등으로 증착시켜야 한다. 그러나 원격조정기를(manipulator)를 이용하여 수행되는 핫셀에서의 증착작업은 사용후 핵연료 시험의 선진분석기술을 갖고 있는 원자력 선진국에서도 핫셀내에 설치되어 있는 증착기의 탄소봉을 교체하는 작업과 진공장치의 성능 유지가 까다로워 시료표면에 균질하게 전도성 물질을 증착시키는 작업에 많은 어려움을 겪고 있다. 본 연구는 통상적으로 이용되는 증착기를 사용하지 않고 Silver Paint를 사용하여 사용후 핵연료를 분석할 수 있는 새로운 방법에 대한 연구를 수행하였다. 산화물 핵연료는 전기전도도가 매우 낮아($3{\times}10^{-1}~4{\times}10^{-8}/ohm{\cdot}cm$)입사된 전자의 이동이 원활하지 못해 일어나는 들뜸(Charging)현상이 발생한다. 그러나 Silver Paint 에 사용후 핵연료를 접착하면 모세관(capillary)현상에 의해 시료 주위와 핵연료의 결정립계로 Silver가 스며들어 입사된 전자의 이동이 원활해져 전도성이 극히 낮은 시료의 분석이 가능하게 된다. 본 시험에 사용된 EPMA는 (Electron Probe Micro Analyzer, SX-50R, CAMECA, Paris, France) 고 방사능을 띤 조사 핵연료의 시험을 수행할 수 있도록 기기의 적절한 부위에 납과 텅스텐으로 차폐되어 시편의 방사능 세기가 $3{\times}10^{10}Bq$까지 시험 가능한 기기이다. 그림 1은 JAERI 에 설치 운영중인 증착기 설비 사진이다. 그림에서 핫셀에 설치된 증착기의 진공을 유지하기 위해 핫셀 벽을 관통하여 증착기 본체까지 연결된 배출관의 형상과 복잡한 주변장치들을 볼 수 있다. 그림 2는 비조사 핵연료 시편을 Silver Pain떼 접착한 사진이다. 그림은 시료주위와 시료 표면까지 Silver Paint가 도포된 모습을 보여주고 있다. 상용발전소에서 연소도가 50,000 Mwd/tU인 사용후 핵연료를 상기와 같은 방법으로 만든 시편의 표면을 관찰한 사진을 그림 3~8에 나타내었다. 그림 3은 핵연료 중앙부위의 결정립을 나타낸 그림이다. Silver Paint만으로 접착한 시료의 표면관찰 및 정량분석이 그림에서 보듯이 가능함을 확인하였다. 그림 4는 사용후 핵연료시료를 중앙부위에서 가장자리까지를 다섯 부위로 나누어 그 중 중앙부위(1/5) 지점의 입계 및 형상을 관찰한 사진이다. 결정립의 크기가 다른 부위보다 상대적으로 크고, 결정립에 생성된 기공이 발달되어 있음을 볼 수 있다. 그림 5와 6과 7은 중심부위와 rim부위 사이 지점을 관찰한 사진으로서 결정립과 기공의 분포가 비슷한 형상을 나타내고 있음을 관찰할 수 있었다. 그림 8은 rim 부위 사진으로 전형적인 rim 영역 현상을 관찰할 수 있었다. 표 1은 그림 2와 같이 비조사 산화물 핵연료를 Silver Paint로 접착한 시편을 정량 분석한 결과이다. 시편의 조성은 33.6 at% U, 66.4 at% O의 결과를 얻었다. 산화물 핵연료의 표면 관찰 및 정량 분석 시험시 시편 표면을 전도성 물질로 증착시키지 않고, Silver Paint 에 시편을 접착하는 방법으로도 만족한 시험 결과를 얻을 수 있었다.

• Journal of the Korea Society for Simulation
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• v.27 no.3
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• pp.65-73
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• 2018

In this paper, we propose a simulation output analysis environment using Elastic Stack technology in order to reduce the complexity of the simulation analysis process. The proposed simulation output analysis environment automatically transfers simulation outputs to a centralized analysis server from a set of simulation execution resources, physically separated over a network, manages the collected simulation outputs in a fashion that further analysis tasks can be easily performed, and provides a connection to analysis and visualization services of Kibana in Elastic Stack. The proposed analysis environment provides scalability where a set of computation resources can be added on demand. We demonstrate how the proposed simulation output analysis environment can perform the simulation output analysis effectively with an example of spreading epidemic diseases, such as influenza and flu.

• Journal of the Korea Society of Computer and Information
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• v.28 no.5
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• pp.129-153
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• 2023

This study was conducted in the context of the Covid-19 pandemic by analyzing a large amount of press report frames regarding the Covid-19 vaccine which is of great public interest, in order to explore the role and direction of trusted media as core elements of crisis communication. The study period lasted for eight months beginning in November 2020 when the development of the Covid-19 vaccine was in progress until June 2021. Set-up as research subjects were the Chosun Ilbo, Joongang Ilbo, Dong-A Ilbo and Hankyoreh according to their public confidence rankings and number of readers.The analysis method used structured topic Modeling (STM) and semantic network analysis. As a result, based on a clear cluster of word structures and a central analysis value, a total of 64 relevant frames, 16 for each news company, were gathered. In the third phase a comparative analysis of the four news companies was carried out to verify the organizational degree of the frames and substantial differences.