• KIEAE Journal
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• 제16권6호
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• pp.51-56
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• 2016

Purpose: As declines in the quality of residential environments occur, such as urban heat island effect, tropical night phenomenon, and violations of right to light and privacy due to urban densification and high rise building, these problems are emerging as social issues. In order to improve these issues, design factors which consider environmental aspects must be selected when planning apartment complexes, and ways to reflect them in the planning phase must be explored. Method: In this study, the analytical hierarchy process(AHP) was used to deduce design factors that considered environmental elements during the planning of apartment complexes. Furthermore, the priority and weight for each evaluation index were assessed. The objective was to propose a guideline for planning apartment complexes by finding the best solution for each evaluation index using complex weight values. Result: Floor area ratio was selected as the most important evaluation criterion in the environmentally conscious evaluation index for apartment complex planning. The shape and placement of skylights were selected as the most important evaluation criteria in the sunshine environment for a pleasant residential environment. Ground surface cover design was selected as the most important criterion in the outdoor thermal environment index for improving the microclimate within cities and apartment complexes. Thus, the results of this study can serve as an investigation guideline that concerns policy and regulations, and as reference data that can be used in planning apartment complexes.

• 한국음향학회지
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• 제37권4호
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• pp.181-187
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• 2018

본 논문은 원형 단면 임피던스 튜브내에 고정된 미세천공 탄성판의 흡음을 해석적으로 구하는 방법을 다루었다. 판의 진동과 덕트 내부 음장을 모드 함수의 무한 급수의 합으로 전개하였는데 반경방향으로는 Bessel 함수를 포함한다. 평면파 가정하에서 저주파수 대역의 근사식을 판의 처음 몇 개의 모드만 고려하여 흡음율을 유도하였으며 등가 임피던스를 갖는 단일 표면의 형태로 제시하였다. 본 논문에서 제안한 공식과 FEM(Finite Element Method)을 이용한 결과는 잘 일치 하였는데 탄성의 효과는 판의 고유진동수에 해당하는 골 또는 피크의 형태로 나타난다. 천공율이 매우 작으면 진동의 영향이 지배적이나 천공율이 어느 한계이상 되면 박판의 탄성거동은 매우 작게 나타나고 강체 MPP(Micro-Perforated Plate)의 흡음 특성이 지배적이 된다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 하계종합학술대회 논문집
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• pp.942-945
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• 1999

In this work, we proposed Proper etching algorithm for ultra-large scale integrated circuit device and simulated etching process using the proposed algorithm in the case of ICP (inductive coupled plasma) 〔1〕source. Until now, many algorithms for etching process simulation have been proposed such as Cell remove algorithm, String algorithm and Ray algorithm. These algorithms have several drawbacks due to analytic function; these algorithms are not appropriate for sub 0.1 ${\mu}{\textrm}{m}$ device technologies which should deal with each ion. These algorithms could not present exactly straggle and interaction between Projectile ions and could not consider reflection effects due to interactions among next projectile ions, reflected ions and sputtering ions, simultaneously In order to apply ULSI process simulation, algorithm considering above mentioned interactions at the same time is needed. Proposed algorithm calculates interactions both in plasma source region and in target material region, and uses BCA (binary collision approximation4〕method when ion impact on target material surface. Proposed algorithm considers the interaction between source ions in sheath region (from Quartz region to substrate region). After the collision between target and ion, reflected ion collides next projectile ion or sputtered atoms. In ICP etching, because the main mechanism is sputtering, both SiO$_2$ and Si can be etched. Therefore, to obtain etching profiles, mask thickness and mask composition must be considered. Since we consider both SiO$_2$ etching and Si etching, it is possible to predict the thickness of SiO$_2$ for etching of ULSI.

• 한국광학회지
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• 제23권5호
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• pp.179-188
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• 2012

어안렌즈(fisheye lens)란 통상 초 광각의 시야각을 가지는 렌즈를 일컫는다. 초 광각의 시야각을 가지는 렌즈에서는 주변부시야각으로 갈수록 상의 조도가 급격히 저하하게 되는데, 본 논문에서는 이의 원인과 개선방안에 관해 논의한다. 왜냐하면 어안렌즈와 같은 초 광각의 렌즈에서는 기하광학적인 수차특성보다 오히려 시야각의 안정적인 확보가 광학적인 성능을 훨씬 더 좌우할 수 있기 때문이다. 그러므로 이를 위해, 먼저, 방향코사인벡터의 부호규약과 곡면 상에서의 법선벡터의 방향을 해석기하학적으로 다룬다. 이어서 해석기하학적인 논의를 바탕으로 조도저하의 다양한 원인들에 대해 수치 및 원리적인 분석을 실시하고, 개선에 대한 방안들을 제시한다.

• 소음진동
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• 제9권1호
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• pp.196-205
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• 1999

6승의 비선형 항을 가지는 두개의 질량으로 구성된 비선형 해밀톤계에 대해서, 비선형 정규모드인 주기운동의 존재성, 분기현상 및 궤도 안정성을 연구하였다. 운동방정식의 직접적분을 통해 4차원 위상공간에서의 운동궤적을 2차원 면으로 투영하는 푸앙카레 사상을 구하였고, 또한 버크 호프-구스타프슨 표준 변환을 통해 구한 운동적분을 이용하여 에너지가 작을때 푸앙카레 사상에 나타나는 불변 곡선들의 해석적인 표현을 유도하였다. 본 논문에서 연구한 진동계는 비선형 계수의 값에 따라 2개 또는 4개의 비선형 정규모드를 가짐이 밝혀졌다. 푸앙카레 사상은, 분기된 모드는 안정하고, 원래의 모드는 안정한 상태에서 불안정한 상태로 변한다는 것을 분명하게 보여주었다.

• 천문학회보
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• 제43권1호
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• pp.43.1-43.1
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• 2018

Star formation in galaxies predominantly takes place in giant molecular clouds (GMCs). While it is widely believed that UV radiation feedback from young massive stars can destroy natal GMCs by exciting HII regions and driving their expansion, our understanding on how this actually occurs remains incomplete. To quantitatively assess the effect of UV radiation feedback on cloud disruption, we conduct a series of theoretical studies on the dynamics of HII regions and its role in controlling the star formation efficiency (SFE) and lifetime of GMCs in a wide range of star-forming environments. We first develop a semi-analytic model for the expansion of spherical dusty HII regions driven by the combination of gas and radiation pressures, finding that GMCs in normal disk galaxies are destroyed by gas-pressure driven expansion with SFE < 10%, while more dense and massive clouds with higher SFE are disrupted primarily by radiation pressure. Next, we turn to radiation hydrodynamic simulations of GMC dispersal to allow for self-consistent star formation as well as inhomogeneous density and velocity structures arising from supersonic turbulence. For this, we develop an efficient parallel algorithm for ray tracing method, which enables us to probe a range of cloud masses and sizes. Our parameter study shows that the net SFE, lifetime (measured in units of free-fall time), and the importance of radiation pressure (relative to photoionization) increase primarily with the initial surface density of the cloud. Unlike in the idealized spherical model, we find that the dominant mass loss mechanism is photoevaporation rather than dynamical ejection and that a significant fraction of radiation escapes through low optical-depth channels. We will discuss the astronomical.

• 한국산학기술학회논문지
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• 제16권10호
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• pp.7189-7195
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• 2015

모멘트법(MoM)인 TE(transversw electric) 전장 적분 방정식(EFIE)으로 완전 전기도체(PEC) 원통을 산란 해석하였다. 이 과정에서 나타나는 특이점(singlarity)과 과대 특이점(hypersingularity)을 포함한 적분 계산은 어렵기 때문에 수치해석 방법으로 특이점을 고립시켜 자체항(self-term)을 얻었다. 모멘트법에서 base 함수와 test 함수의 선택은 수치해석 결과의 정확도와 수렴에 있어 매우 중요한 요인이됨은 알려져 있는 사실이다. basis 함수와 test함수를 달리하여 세 가지 방법으로 PEC 원통에 유도된 전류를 구하였다. 이렇게 구한 결과를 해석학적 방법과 모멘트법에서 얻은 전류와 비교하여 상대 효율 전류 오차를 구하였으며 어떤 결합 방법이 효율적인지 확인하였다. 또한 각 결합방법에 따른 상대 효율 전류 오차의 수렴율을 구하여 가장 정확한 결과를 얻을 조건을 찾았다. 전류 오차의 가장 빠른 수렴오더(order of convergence) 2.528은 펄스 base 함수/델타 test 함수 결함 조건에서 얻었다.

• Composites Research
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• 제16권3호
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• pp.9-17
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• 2003

타이어 벨트층내의 코드간 균열연결 및 층간균열진전을 모사하기 위해 자유단을 갖는 2층 고무/코드 적층시험편에 대한 4~11mm 변위제어 실험을 수행하였다. 자유단의 코드간 균열연결시의 폭방향 균열진전량은 45$^{\circ}$ 경사진 코드들간 길이의 절반에 도달할 때의 측정값으로 하였으며, 이는 탐침법에 의해 측정되었다 또한, 자유단에서 코드들간 균열연결을 모사하기위해 2차원의 이상화된 모델링 기법을 고안하였다. 이론수명은 테어링에너지(균열파단면의 단위면적당 방출에너지)를 이용하여 코드간 균열연결수명(임계값)과 이후 최종파손까지의 수명으로 구분하였으며, 이들을 각기 실험값과 비교하였다. 임계값까지의 수명예측은 실험과 비교하여 약 20%, 최종파손까지 약 65%의 오차가 발생하였다. 따라서, 전체 이론수명은 실험과 비교하여 약 45%의 오차를 발생하였다.

• Water Engineering Research
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• 제3권1호
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• pp.57-62
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• 2002

This research is intended to integrate long-term operation rules and real time operation policy for conservation & flood control in a reservoir. The familiar Yield model has been modified and used to provide long-term rule curves. The model employs linear programming technique under given physical conditions, i.e., total capacity, dead storage, spillways, outlet capacity and their respective elevations to find required and desired minimum storage fur different demands. To investigate the system behavior resulting from the above-mentioned operating policy, i.e., the rule curves, the simulation model was used. Results of the simulation model show that the results of the optimization model are indeed valid. After confirmation of the above mentioned rule curves by the simulation models, gate operation procedure was merged with the long term operation rules to determine the optimum reservoir operating policy. In the gate operation procedure, operating policy in downstream flood plain, i.e., determination of damaging and non-damaging discharges in flood plain, peak floods, which could be routed by reservoir, are determined. Also outflow hydrograph and variations of water surface levels for two known hydrographs are determined. To examine efficiency of the above-mentioned models and their ability in determining the optimum operation policy, Esteghlal reservoir in Iran was analyzed as a case study. A numerical model fur the solution of two-dimensional dam break problems using fractional step method is developed on unstructured grid. The model is based on second-order Weighted Averaged Flux(WAF) scheme with HLLC approximate Riemann solver. To control the nonphysical oscillations associated with second-order accuracy, TVD scheme with SUPERBEE limiter is used. The developed model is verified by comparing the computational solutions with analytic solutions in idealized test cases. Very good agreements have been achieved in the verifications.

• 한국농공학회지
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• 제18권4호
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• pp.4218-4225
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• 1976

To insure the safety of the drainage sluice, topogrophical change due to erosion as well as capability of discharging the design flow in a very important factor. In consideration of the fact that the drainage sluice is built in the sea, its construction has many topographically restricted problems and naturally requires a completeness of research and experiment. This thesis is a comparative and analytic study of discharging flow acting on the erosion at the bottom of the structure on the basis of the measured velocity on the downstream channel of the drainage sluice. (1) The measured velocity shows a little higher values than the computed velocity, because the measured velocity was observed at the surface of the stream. There fore, it is reasonable that the compated velocity should be taken in this study. (2) The field observation was conducted to have the measurement of the flow velocity without surveying the area of flow. Therefore, the coefficient of discharge could not be computed. The survey of the area of flow is planned to be conducted along with the measurement of the flow velocity. (3) The apron of the drainage sluice is free discharging type and it was designed to be about 80m in length less than it should be. (4) The apron of free flow discharging type should have a solid foundation to protect the structure by preventing erosion damage to upstream and downstream channels against weathering of rock and strong torrent. Whether free flow discharging type or energy-dissipating type is best chosen depends on the topographical condition of the forage site, therefore, there would be a comparative study before the final decision was made about the protrection for the structure. (5) It is considered to be appropriate that the design and construction of the drainage sluice should have a complete study which is based on hydraulie model test before the type of protection is decided. (6) It is much requested that a variety of experiment equipments be installed and observed to study the protection for the drainage sluice.