• 국제학술발표논문집
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• The 9th International Conference on Construction Engineering and Project Management
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• pp.1009-1016
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• 2022

As environmental concerns grow, people are becoming more aware of energy efficiency, carbon reduction, and sustainable development. Leadership in Energy and Environmental Design (LEED) certification is currently the most widely recognized building environment assessment method connected to energy and the environment worldwide. This study explores trends for six factors (energy and atmosphere, materials and resources, indoor environmental quality, sustainable sites, water efficiency, and innovation in design) to assess four levels of LEED certification (Platinum, gold, silver, and certified) using 11,209 LEED projects in the United States. The study analyzes trends using scores of percentages of maximum points by certification level, ownership type, space type, and climate zones. With the interest in the Environmental, Social, and Governance (ESG) principle on the rise, this study contributes to a better understanding of the trends and future of LEED certification in the built environment sector.

• 동력기계공학회지
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• 제10권4호
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• pp.119-126
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• 2006

Gerotor hydraulic motor is widely used in hydraulic systems due to its low speed, high torque output and compactness in rotational direct driving of a heavy weight. Gerotor is a Planar mechanism consisted of a pair of rotor and circular teeth of stator assembly which forms a closed space, so called a chamber. The motion of rotor relative to the circular tooth is produced by the pressure difference of hydraulic operating fluid between the adjacent chamber. As all active contact points of rotor and circular teeth are subjected to very high sliding friction, a reduction in the performance of the gerotor hydraulic motor can not be avoided. Therefore, the core design parameters of gerotor profile used in hydraulic motors is to minimize a friction force by high contact stresses. The analytical design method of gerotor profile, based on envelope of a family of curves, is proposed. In this study, the influence of the tip clearances on three critical contact points between rotor and circular teeth of stator assembly has been explored by experimental data in this paper. At the same time a improvement method to reduce the friction force is proposed and the tip clearances on three critical points for getting an optimum gerotor profile are also analyzed.

• 한국실내디자인학회논문집
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• 제22권6호
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• pp.3-10
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• 2013

This study intends to clarify the key elements of designing low energy residential building construction by planning out residential construction in nature oriented designing method utilizing nearby environment and nature oriented energy from designing stage instead of construction of low energy residential building. Development of building technology is proportional to the development of technology that lasts already. However, what is no less important than the advancement of technology, it is the study of fundamental phenomena energy use in response to climate, reduction, such as recycling. It is possible in such a purpose, it is assumed that there is a need to study elements implementation plan in accordance with the climatic characteristics of the study. Method for controlling the condition solar radiation, sunshine, depending on the characteristics of the weather, by utilizing the convection phenomenon of nature, to maintain the air comfort in the interior space is the essence of eco-friendly construction and passive Property This is an important architectural elements to be aim. For through the analysis of this case, corresponding to the phenomenon of the features of the macro climate and micro climate due to climate change, a combination building blocks of classification placement of each, shape, structure, elevation, space, of the material appeared in various it was possible to know the construction characteristics were. As shown in each case, construction method to address climate change has been found to apply to a comprehensive analysis climatic characteristics of each region, in response to this, the construction of element each corresponding.

• International Journal of Fluid Machinery and Systems
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• 제9권3호
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• pp.265-276
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• 2016

Energy systems working coherently in different conditions may not have a specific design which can provide optimal performance. A system working for a longer period at lower efficiency implies higher energy consumption. In this effort, a methodology demonstrated by a jet pump design and optimization via numerical modeling for fluid dynamics and implementation of an evolutionary algorithm for the optimization shows a reduction in computational costs. The jet pump inherently has a low efficiency because of improper mixing of primary and secondary fluids, and multiple momentum and energy transfer phenomena associated with it. The high fidelity solutions were obtained through a validated numerical model to construct an approximate function through surrogate analysis. Pareto-optimal solutions for two objective functions, i.e., secondary fluid pressure head and primary fluid pressure-drop, were generated through a multi-objective genetic algorithm. For the jet pump geometry, a design space of several design variables was discretized using the Latin hypercube sampling method for the optimization. The performance analysis of the surrogate models shows that the combined surrogates perform better than a single surrogate and the optimized jet pump shows a higher performance. The approach can be implemented in other energy systems to find a better design.

• 한국항공우주학회지
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• 제35권4호
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• pp.308-315
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• 2007

연구는 경비행기인 창공-91의 인증 획득을 위한 비행시험의 일부로서 상승성능을 파악하기 위하여 수행되었다. 창공-91은 1993년에 대한민국의 건설교통부로부터 최초로 인증을 취득한 단발엔진을 장착한 일반유형의 5인승 항공기이다. 상승을 위한 비행시험 절차 및 자료는 형식증명을 획득하는데 사용되었다. 톱니형 상승 데이터로부터 양항곡선방법으로 데이터를 처리하여 창공-91의 최대상승률, 최대상승각 속도, 최대상승률 속도, 그리고 절대상승한도를 구하였다. 또한, 상승성능의 결과로부터 양항곡선식을 구함으로써 형상항력계수와 오스왈드 효율계수를 비행기 설계시의 값과 비교하였다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume I
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• pp.274-277
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• 2006

KARI is currently developing a geostationary ocean color imager (GOCI) for COMS. We report the progress in integrated optical modeling and analysis for stray light suppression and the end-to-end instrument performance verification including in-orbit calibration. The Sun is modeled as the emitting light source and the selected area around Korean peninsular as the observation target that scatters the sun light towards GOCI in orbit. The optical ray tracing employing active geometric scaling was then used for precise characterization of the spatial and radiometric performance at the instrument focal plane. The analysis results show positive reduction in the simulated stray light level with the design improvement including baffles. It also indicates that the ray traced in-orbit radiometric performances are effective tools for the independent assessment of more traditional linear and quadratic equation based estimation of water leaving radiance. The concept of integrated GOCI optical model and the computational method are presented.

• 한국항공우주학회지
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• 제46권4호
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• pp.297-305
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• 2018

UCAV는 적진 중심으로의 침투, 공격 등 적대적 상황에서 임무를 수행하는 것을 목표로 한다. 일차적으로 적의 레이더에 포착되지 않아야 하므로 RF 스텔스 기술의 적용이 필수적이다. 최신 RCS 저감 기술이 적용된 대표적인 비행체로는 Blended Wing Body 형태의 X-47B UCAV이다. 본 연구에서는 X-47B와 유사한 모델 UCAV 형상을 설계한 다음, Ray Launching Geometrical Optics(RL-GO) 기법을 활용하여 모델 UCAV의 고주파수 영역에서의 RCS 특성을 분석하였다. 특히 IR 저감이 고려된 UCAV 형상이 RCS에 미치는 영향성을 조사하였다. 마지막으로 모델 UCAV의 공기 흡입구에 최적화된 RAM을 적용하였을 때의 RCS 변화를 분석하였다.

• 한국터널지하공간학회 논문집
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• 제19권2호
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• pp.109-120
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• 2017

터널 내 지하수 침투는 터널붕괴와 그에 따른 지반침하의 주요 원인 중 하나이다. 따라서 터널굴착 중 시간에 따른 지하수 침투량과 간극수압 변화를 적절히 예측하는 것이 중요하다. 실무에서는 균질한 지반조건으로 가정하는 Goodman의 산정법을 사용하여 지하수 침투량을 계산하지만, 터널굴착 중 지하수위 강하와 깊이에 따른 투수계수 변화를 고려하지 않아 설계단계에서 지하수 유입량을 과다하게 산정할 우려가 있다. 따라서 본 연구에서는 지하수위 강하 및 깊이별 투수계수의 감소를 적용한 매개변수분석을 통해 지하수 유입량 변화를 분석 비교하였으며, 시간에 따른 지하수 침투량 변화와 지하수위 및 간극수압 분포 변화를 분석하기 위해 비정상류 해석을 수행하였다.

• 한국항공우주학회지
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• 제41권6호
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• pp.488-494
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• 2013

전자식 비행제어시스템(Fly-By-Wire Flight Control System)에 적용되는 헬리콥터의 제어법칙 설계 및 해석은 모델기반 설계기법(Model Based Design)을 사용하여 개발되고 있다. 모델기반 설계기법은 회전익뿐만 아니라 고정익, 무인항공기, 자동차 산업에서도 널리 사용되고 있다. 모델기반 설계기법은 핵심기술인 시뮬레이션과 자동생성코드를 이용하여 개발기간 단축 및 개발리스크 감소라는 장점을 제공한다. 본 논문에서는 FBW 헬리콥터 비행제어법칙의 자동생성코드에 대해서 체계적인 기능검증을 위한 프로세스를 개발하였다. 그리고 지식경제부 과제로 진행하고 있는 FBW 헬리콥터 개발에 적용하여 비행제어법칙 자동생성코드의 기능 검증을 수행 결과, 요구 조건을 충족하는 것으로 확인할 수 있었다.

• Structural Engineering and Mechanics
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• 제32권1호
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• pp.21-36
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• 2009

An importance sampling method is presented for computing the first passage probability of elasto-plastic structures under stochastic excitations. The importance sampling distribution corresponds to shifting the mean of the excitation to an 'adapted' stochastic process whose future is determined based on information only up to the present. A stochastic control approach is adopted for designing the adapted process. The optimal control law is determined by a control potential, which satisfies the Bellman's equation, a nonlinear partial differential equation on the response state-space. Numerical results for a single-degree-of freedom elasto-plastic structure shows that the proposed method leads to significant improvement in variance reduction over importance sampling using design points reported recently.