• 한국주거학회논문집
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• 제15권3호
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• pp.53-62
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• 2004

Recently the landscape of housing has been emphasized. This trend seems to reflect the negative aspects of housing landscape in urban area. Throughout the analysis on the various visual density index, the following findings were obtained; 1) Elevation blockage ratio(EBR) was permitted differently according to the types of housing blocks, and the preference of block layout was different to the location of site. 2) EBR regulation level was acceptable. But 40m level of general area should be stepped up to the 35m level. 3) The correlation between the floor area ratio(FAR) and the EBR was not high. Therefore it is reasonable to regulate the EBR to the location. 4) Elevation coverage ratio(ECR) was highly correlated with the FAR. It means that FAR can substitute for the ECR, and ECR should be regulated to the level of FAR.

• 대한안전경영과학회지
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• 제22권2호
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• pp.39-46
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• 2020

This paper recognizes the risk of ignition of air fryer (machine that can cook fried dishes with hot air without oil) that is far exceeding the sales rate of microwave ovens, which is necessary to modern household kitchen, and identifies fire risk through the operation principle of the process of heat transfer, and the main structure of the machine. The fire test that we conducted is to observe the risk of ignition of the machine due to the damage to the safety system and the possibility of igniting oil paper along with food, to experiment with the possibility of ignition due to blockage of the exhaust due to obstacles, and accumulation of oil stains on the hot wire, and to present the method of fire control and devise countermeasures.

• 한국농촌건축학회논문집
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• 제19권4호
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• pp.77-85
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• 2017

In order to preserve beautiful coastal areas landscapes of Jeju Island's the landscape resource, Jeju Special Self-Governing Province is dedicated to protecting the landscape through legal regulations and deliberations. However, the Coastal Landscape of Jeju Island was continuously damaged by due to increased tourist and high development pressure. Based on buildings along the Coastal Road in Aeowal of Jeju Island, this study focused on Management Status of Coastal Areas Landscapes through the Analysis of Building Landscape Elements. As a result, 1) It was effective to limit the use and scale of buildings through legal regulations such as Use zoning. 2) The result of analysis on the physical landscape elements of buildings showed some of the them have the damage values despite passing the review of Architecture Committee. Therefore Landscape Policies required institutional maintenance. 3) As physical landscape Elements of buildings is a minimum quantitation criterion of not less than 1.5 for D/H, or less than a factor of $27^{\circ}$ for angle of elevation and not less than 7.8m for elevation blockage ratio was presented as a criterion for preventing damage to the minimum Coastal Landscape.

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 1999년도 춘계 학술발표회 논문집
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• pp.151-157
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• 1999

원심 펌프내 3차원 유동 특성을 고찰하기 위하여 혼류형 원심펌프의 내부유동특성을 수치적 고찰하였다. 회전차 내의 유동현상에 대한 상세한 해석과 이해는 원심펌프의 주요 요소들에 대한 성능 예측에 있어 매우 중요하다. 회전차 내부의 유동은 3차원 점성효과가 지배적이기 때문에 펌프 성능에 중대한 영향을 준다. 회전차내의 3차원 점성유동은 주 영역인 등엔트로피 유동과 원심력과 Coriolis힘에 의한 경계층의 변화, 벽면의 전단응력, 2차 유동(secondary flow)등의 영향에 의한 비가역 영역으로 구분한다. 저 운동량 영역을 만드는 회진차 내부의 점성 유동은 정체영역(blockage)과 실속(stall)이라는 비가역 영역을 만들게 되는데, 결과적으로 펌프의 성능과 효율저하를 유발시킨다. 특히 Coriolis힘과 원심력은 비가역 영역을 증대시키는 가장 큰 힘이라는 사실을 알았다.

• 대한건축학회연합논문집
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• 제20권6호
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• pp.33-40
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• 2018

The coastal village in Woljeong-ri, Jeju is highly preferred by tourists because of its unique natural landscape different from inland areas. Especially, the number of buildings in the coastal area of the village is increasing due to escalating commercial value. Buildings are densely developed, along the seaside, resulting in privatization of coastal landscape. This results in blocking of landscape and psychological exchanges between the coastal village and coast. This study analyzed the actual conditions of coastal landscape before and after 2010, when the number of tourists and demand for development were increased in the coastal area of the coastal village in Woljeong-ri, Jeju. In this study, open index, visible horizontal index, elevation angle, elevation blockage and visible facade index were used to compute objective indicators of coastal landscape status. The analysis reveals visible facade index, a complex landscape assessment indicator, was increased by 7 times after 2010 as compared with before 2010. As such, there are many coastal villages in Jeju similar to Woljeong-ri that have a high landscape value and are in need of management. A comprehensive measure including a system for management of coastal landscape is urgently required to create narrative landscape in Jeju.

• 한국위성정보통신학회논문지
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• 제10권4호
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• pp.39-45
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• 2015

위성통신은 상공에 있는 인공위성으로 통신하는 방식으로 고속 대용량 전송이 가능하며, 통신 구역이 넓다는 장점이 있는 반면 정보의 보안성이 없다는 단점이 있다. 이를 보완하기 위해 AES 암호화를 CTR과 CBC 모드를 적용하였다. 또한, 송신기와 수신기 사이에 나무나 건물 등의 장애물로 인해 발생하는 영향을 알아보기 위해 Markov chain을 이용하여 Blockage channel을 Urban과 Open 환경으로 구성하였다. 위성통신 고속링크 기반의 시뮬레이션을 통해 성능을 분석해 본 결과, 암호화를 적용한 경우 보안성은 보완되나 BER의 성능이 악화됨을 보였고, 장애물이 적은 Open 환경에서 장애물이 많은 Urban 환경보다 BER 성능이 향상됨을 확인하였다.

• 한국항해항만학회지
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• 제36권6호
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• pp.429-435
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• 2012

위성항법시스템의 기술발전이 지속적으로 진행되고 있지만 여전히 신호차폐가 빈번히 발생하는 지역에서는 측위정확도 확보에 어려움을 겪고 있다. 이 연구에서는 통합 GPS/GLONASS 이중차분 상대측위 알고리즘을 구현하고 신호차폐 환경의 시뮬레이션을 수행해 그 성능을 검증하였다. 동쪽, 서쪽, 남쪽 방향으로 고층건물에 의해 신호차폐가 발생하는 환경을 시뮬레이션 하고 시뮬레이션 상황에 따른 GPS와 GPS/GLONASS의 정확도 평가를 수행하였다. 그 결과, 신호차폐 시뮬레이션 환경에서는 GPS/GLONASS가 GPS에 비해 최소 0.3m에서 최대 13m이상의 수평정확도가 향상되었다.

• 한국항공우주학회지
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• 제34권4호
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• pp.11-16
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• 2006

유체 공급배관내의 압력진동을 감쇠할 수 있는 방법으로 배관내에 오리피스를 설치하는 방법을 채택하여, 그 압력진동 감쇠효과를 수치해석을 통해 조사하였다. 본 연구에서는, 압력진동의 진폭이 작다는 가정에 기초하여 오리피스의 음향학적 감쇠효과에 초점을 맞추었다. 오리피스의 위치에 따른 계산 결과로부터 압력진동의 마디, 즉 속도진동의 배가 되는 위치에 오리피스를 설치할 때 가장 효과적으로 압력 진동이 감쇠되었다. 이에 반해서, 오리피스를 압력진동의 배에 설치한 경우에는 오리피스의 설치 효과가 아주 미약하였다. 오리피스의 유로 봉쇄율이 증가함에 따라 감쇠효과는 단조적으로 증가하였고, 오리피스의 두께가 증가할수록 공진성을 약화시켜 감쇠효과가 크게 나타났다. 또한, 직경이 작은 배관에서 감쇠 효과가 더 크게 나타났다.

• 대한기계학회논문집B
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• 제21권1호
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• pp.89-98
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• 1997

Compression waves propagating in a high speed railway tunnel impose large pressure fluctuations on the train body or tunnel structures. The pressure fluctuations can cause ear discomfort for the passengers and increase the aerodynamic resistance of trains. As a fundamental research to resolve the pressure wave phenomenon in the tunnel, a steady theory of Chester-Chisnell- Whitham was applied to a simple shock tube with a sudden cross-sectional area reduction to model trains inside the tunnel. The results of the present theoretical analysis were compared with the experiments of the shock tube. The results show that the reflected compression wave from the model becomes stronger as the strength of incident compression wave and the blockage ratio increase. However, the compression wave passing through the model is not strongly dependent on the blockage ratio. The theoretical results are in good agreement with the experiments.

• Environmental Engineering Research
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• 제22권1호
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• pp.95-107
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• 2017

Adsorption equilibrium and kinetic behavior of two toxic heavy metals hexavalent chromium [Cr(VI)] and mercury [Hg(II)] on mustard oil cake (MOC) was studied. Isotherm of total chromium was of concave type (S1 type) suggesting cooperative adsorption. Total chromium adsorption followed BET isotherm model. Isotherm of Hg(II) was of L3 type with monolayer followed by multilayer formation due to blockage of pores of MOC at lower concentration of Hg(II). Combined BET-Langmuir and BET-Freundlich models were appropriate to predict Hg(II) adsorption data on MOC. Boyd's model confirmed that external mass transfer was rate limiting step for both total chromium and Hg(II) adsorptions with average diffusivity of $1.09{\times}10^{-16}$ and $0.97m^2/sec$, respectively. Desorption was more than 60% with Hg(II), but poor with chromium. The optimum pH for adsorptions of total chromium and Hg(II) were 2-3 and 5, respectively. At strong acidic pH, Cr(VI) was adsorbed by ion exchange mechanism and after adsorption reduced to Cr(III) and remained on MOC surface. Hg(II) removal was achieved by complexation of $HgCl_2$ with deprotonated amine ($-NH_2$) and carboxyl (COO-) groups of MOC.