• Journal of Biosystems Engineering
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• v.13 no.3
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• pp.11-19
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• 1988

분무량(噴霧量) 및 유량계수(流量係數)에 관(關)한 많은 연구(硏究)가 실험결과자료(實驗結果資料)에 기초하여 수행(遂行)되어졌다. 그러나 공시체(供試體)의 노즐의 특성(特性)에 따라서 유선(流線)의 특성(特性)이 다르므로 많은 실험결과(實驗結果) 및 해석(解析)이 서로 상치되는 점이 많다. 본(本) 연구(硏究)에서는 이론분석결과(理論分析結果)가 실험결과(實驗結果)와 다소 다르더라도 노즐 설계(設計)의 실제응용면(實際應用面)에서 필요(必要)한 노즐구조(構造)의 기본기능(基本機能)을 이론적(理論的)으로 분석(分析), 이해(理解)시키고저 한다. 이론분석(理論分析)의 결과(結果)는 다음과 같다. 공동면적(空洞面積)은 분구경(噴口徑), 와실경(渦室徑), 중자도구경(中子導溝徑) 및 중자도구각(中子導溝角)에 관계되고 있으며, 특히 중자도구각(中子導溝角)이 공동현상(空洞現象)에 큰 영향을 미친다. $$r_r{^6}-3r_o{^2}r_r{^4}+[3r_o{^4}+\frac{r_c{^4}r_o{^2}}{(r_c-r_g)^2\;tan^2{\theta}}]r_r{^2}-r_o{^6}=0$$ 반경방향(半徑方向) 힘의 요소(要素)로 인(因)한 유량계수(流量係數)($C_t$)는 산출식(算出式)은 아래와 같다. $$C_t=[1-(\frac{r_r}{r_o})^2]^{3/2}$$ 분무각(噴霧角)(${\alpha}$)은 공동반경(空洞半徑) 및 분구반경(噴口半徑)에 의(依)하여 변화(變化)된다. $${\alpha}=2\;tan^{-1}\(\frac{r^r}{\sqrt{r_o{^2}-r_r{^2}}}\)$$분무각(噴霧角)은 특히 와실유선각(渦室流線角)의 영향을 많이 받음을 시사하고 있다.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.27 no.4
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• pp.205-227
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• 2016

The research analyzed the collaborative research network based on the data of international academic papers in order to understand the structure of production of scientific knowledge by North Korean scientists. According to the analysis results, the subject areas of research were concentrated on basic science fields such as physics, mathematics and chemistry. The main collaborative research collaboration with North Korea is China, and the phenomenon has become stronger since Kim Jong Eun era. Major joint research in physics has moved from Germany to China. Among the research institutions that actively engaged in academic activities, KIM IL SUNG UNIV, ACAD SCI DPRK, KIM CHAEK UNIV TECHNOL, and UNIV SCI among 32 research institutes belonging to North Korean researchers who published international academic papers.

• Journal of Korean Tunnelling and Underground Space Association
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• v.2 no.2
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• pp.62-71
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• 2000

The abandoned mines causing settlement of the surface above and collapse of the cavities are the major influencing factor on the stability of the nearby underground structures. To prevent the harmful effect, the backfill methods are commonly applied to the cavities although the design criteria and the analysis method are not properly addressed in some cases. An approximate analytical method together with the numerical technique is considered in this study to simulate the gradual deterioration of the rock masses around the cavities and, therefore, the influential zone to the underground structures passing through the cavities. Also considered in this study is the backfill effect on the stability of the rock masses around the cavities. Specifically, the incomplete backfill effect is compared with that of the idealized backfill method by adopting elasto-plastic analysis involving a strain softening material law.

• Fire Science and Engineering
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• v.34 no.3
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• pp.49-57
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• 2020

Apartment buildings are becoming taller and more densely populated with the advancements in science and the development of cities, Consequently, various amenities and safety facilities are being developed to improve the quality of life for residents. However, according to statistics, the number of casualties in apartments accounts for a high proportion of accidents, and the leading cause of the casualties is smoke emitted from fires while sleeping at night. Although it is best to install separate indoor facilities in apartments to minimize smoke damages to occupants, it is useful to minimize the smoke damages by utilizing the installed facilities while reducing the financial burden of occupants. Based on the review, the heat exchanger ventilation system and the kitchen collective exhaust system were selected, and the feasibility of these systems was verified through fire simulation. From the verification results, the available safe egress time improved by 27, 30, and 35 s on the 25th, 35th, 50th floors, respectively.

• Journal of the Society of Disaster Information
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• v.14 no.4
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• pp.399-408
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• 2018

Purpose: Recently, the ground subsidence has caused social problem, because it occurred life and economic damage. Method: Ground subsidence is different from a sink hole. Ground subsidence occurred cavities from loss of by groundwater flow, surface layer is collapsed due to relaxation and expansion. Results: According to the survey, the caused of ground subsidence are classified as ground cavities, surrounding ground relaxation and pipe joint failure. Conclution: Cavities of ground is mainly caused by cavities formed by rainfall induced infiltration of the heavy rainfall, loss of soil due to rise and fall of ground water level and repeated sewage runoff.

• The Southeast Asian review
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• v.27 no.2
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• pp.155-184
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• 2017

ASEAN marking its 50th anniversary in 2017 draws hopes and concerns. There is hope for the full realization of the vision of ASEAN Community since 2015 while there are increasing concerns about the changing internal and external environments. This article reviews the process of ASEAN's community building and its external relations. First, after reviewing institutionalization and functional cooperation in 2016, it argues that there is increasing pressure for the modification of the 'ASEAN Way' mainly due to the recent political changes in some ASEAN member states. Second, this article considers the nature of ASEAN's external relation focusing on continuity rather than change. The tendency of external relations of ASEAN appears to be 'avoiding conflict' and 'status quo' while it concentrates on development cooperation. We argue that such attitude contributes to the unity of ASEAN as it is useful in searching for regional resilience which is a common goal of ASEAN power elites.

• Journal of the Korea Institute of Military Science and Technology
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• v.25 no.5
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• pp.487-500
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• 2022

Supercavitation is a phenomenon in which the cavity covers the entire underwater vehicle. The purpose of this paper is to compare and analyze the thermal effect on the cavity characteristics by changing the ventilated gas temperature through computational analysis. For this study, a homogeneous mixture model based on the 3D Navier-Stokes equation was used. As a phase change model, it is its own code considering both pressure change and temperature change. A dimensionless number T_m was presented to analyze the numerical results, and as the T_m increased, the cavity length increased by about 3.6 times and the cavity width by about 3.3 times at 393.15 K compared to room temperature. Analyzing these thermal effects, it was confirmed that rapid heat exchange and heat transfer between the gas phase and the liquid phase occurred at the location where the ventilated gas was sprayed, affecting the cavity characteristics. In addition, it can be confirmed that the initial cavity surface becomes unstable as the ventilated gas temperature increases, and it can be confirmed based on the numerical analysis results that the critical temperature at which the cavity surface becomes unstable is 373.15 K.

• Proceedings of the Korean Information Science Society Conference
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• 2004.10b
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• pp.157-159
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• 2004

정보통신 기술의 발달로 자치단체에서 개별적으로 운영되던 업무별 단위시스템을 단일화 또는 연계하여 자료를 공동 활용하려는 노력이 계속되고 있다 하지만 타 시스템의 자료를 실시간으로 검색함에 있어 빠른 응답시간이 요구되며, 검색건수 증가에 따른 수행지연으로 인한 문제가 되고 있다. 따라서 본 논문에서는 검색 대상 자료를 본 시스템의 메모리에 상주시켜 연계자료에 대한 검색속도를 높이고 수행지연에 의한 병목현상을 해결할 수 있는 방안을 제시하였다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2000.04a
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• pp.35-35
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• 2000

터빈의 핵심구동부품은 손상이 누적되어 파괴에 이를 경우 치명적인 결과를 야기할 수 있기 때문에, 부품사용조건에서의 소성변형과 이에 따른 손상 누적을 정확히 예측하고 평가함으로써 균열생성 시점을 정확히 파악하여야 할 필요가 있다. 현재 터빈디스크와 같이 고온 고응력에서 사용되고 있는 소재부품의 수명은 궁극적으로 크리프변형과 피로시험의 공동작용으로 결정되며, 재료특성모델링 시험에 있어서도 dwell time 피로시험을 통해 dwell time 효과를 점검하고 점소성 재료변형에 근거하여 피로에 의한 변형 현상을 설명할 수 있다.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 2000.11a
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• pp.435-441
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• 2000

건설산업은 국가발전의 초기 단계에서 유통망의 확보 및 제조시설의 확보과정에서 대단히 중요한 역할을 담당한다. 현재 우리나라는 국가 도로망의 정비가 일정수준이상 진행된 상태이며, 제조시설 역시 IMF이후 시설 투자가 감소하면서 건설경기가 침체되어 있는 것이 사실이다. 따라서 대규모의 건설현장은 감소하고 소규모의 도로망 확장공사 및 공동주택 재개발등이 건설경기의 맥을 겨우 잇고 있는 것이 현실이다. 건설경기의 침체와 더불어 안전시설 투자와 안전관리의 공동화현상이 빚어지고 있으며 이로 인해 안전사고가 급증하고 있다. 따라서 본 연구는 안전시설투자에 대한 부담을 줄이고 안전교육의 효율을 극대화함으로써 안전사고를 예방할 수 있는 방법을 연구 하고자 한다.(중략)