• 대한의용생체공학회:의공학회지
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• 제21권4호
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• pp.411-417
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• 2000

본 연구에서는 시뮬레이션을 이용하여 동맥압 파형 형태에 대한 오실로메트릭 방법을 분석하고 수축기압과 이완기압을 검출할 수 있는 새로운 알고리즘을 제시하였다. 동맥압 파형 형태에 대한 오실로메트릭 방법을 분석하고 수축기압과 이완기압을 검출할 수 있는 새로운 알고리즘을 제시하였다. 동맥압 파형 형태에 대한 오실로메트릭 방법을 분석하기 위해 동맥압 파형 형태를 쉽게 가변할 수 있는 동맥압 모델을 만들었으며, 기존의 정적인 동맥 압력-용적 지수함수 모델을 이용하여 오실로메트릭 모델의 구현 및 컴퓨터 시뮬레이션을 수행하였다. 동맥압 파형 형태와 보편화된 혈압 검출 기준인 특성비율과의 상관관계 분석을 통하여 동맥압 파형 형태와 맥압의 영향 때문에 특성비율이 수축기압과 이완기압을 결정하는 유일한 기준이 될 수 없음을 밝혔으며, 동맥압 파형 형태와 오실레이션 파형 형태의 상관관계 분석을 통하여 오실레이션 파형으로부터 동맥압 파형 형태를 추정할 수 있는 방법을 제시하였다. 최대 크기 오실레이션 파형과 동맥압 파형의 관계로부터 맥압을 구할 수 있는 맥압 표를 구성하여 수축기압과 이완기압을 검출할 수 있는 혈압 검출 알고리즘을 제시하였으며 그 결과 수축압, 이완압, 평균압의 절대편차 평균값은 각각 1.62%, 2.40%, 2.20%를 얻었다. 결론적으로 제안된 알고리즘은 정확한 혈압검출을 위한 유용 가능성을 보였다.

• 한국정밀공학회지
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• 제29권3호
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• pp.279-288
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• 2012

The material removal mechanism in machining is significantly affected by the cutting edge geometry. Its effect becomes even more substantial when the depth of cut is relatively small as compared to the characteristic length which represents the shape and size of the cutting edge. Conventionally, radius or focal length has been employed as the characteristic length with the assumption that the shape of cutting edge is round or parabolic. However, in reality, there could be various ways to determine the radius or focal length even for the same tool edge profile, depending on the region to be considered as cutting edge in the measured profile and the constraints to be set in constructing the best fitted circle or parabola. In this regard, the present study proposes various models to determine the characteristic length in terms of radius or focal length. Their physical compatibility are validated by carrying out 2D orthogonal cutting experiments using inserts with a wide range of characteristic length ($30{\sim}180\;{\mu}m$ in terms of radius) and then by investigating the correlation between the characteristic length and the cutting forces. Such validation is based on the common belief that the larger the characteristic length is, the blunter the cutting edge is and the higher the cutting forces are. Interestingly, the results showed that the correlation is higher for the radius or focal length obtained with a constraint that the center of best fitted circle or the focus of the best fitted parabola should be on the bisectional line of the wedge angle of tool.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2013년도 춘계학술대회 논문집
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• pp.237-238
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• 2013

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2004년도 봄 학술발표회 논문집
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• pp.151-160
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• 2004

Genetic algorithm is the theory of grafting the principle of survival of the fittest in genetics on to the computer algorithm and it is used to solve the optimization problems, especially the shape and size optimization of the structure in Architectural problems. In the size optimization problem discrete variables are used, but series variables have to be used in the shape optimization problem because of the incongruenty. The purpose of this study is to obtain the optimum shape of cable domes by using the real coding genetic algorithm. Generally, the structural performance of the cable domes is influenced very sensitively by pre-stress, geometry and length of the mast because of its flexible characteristic. So, it is very important to decide the optimum shape to get maximum stiffness of cable domes. We use the model to verify the usefulness of this algorithm for shape optimization and analyze the roof system of Seoul Olympic Gymnastic Arena as analytical model of a practical structures. It is confirmed lastly that the optimum shape domes have more stiffness than initial shape ones.

• KIEAE Journal
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• 제8권6호
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• pp.47-55
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• 2008

The purpose of this study is as follows. 1) An element to organize the landscape of an apartment entrance space and setting up, a characteristic of landscape through the actual condition analysis. 2) The characteristic of the type analysis and classified the shape of the entrance as the type. 3) The degree to like the landscape analysis through the making up question. The result of this research is as follows. The entrance of the apartment complex of 71 as of 92 and set an element to organize the landscape and the characteristic of landscape through the frequency analysis and divided an entrance landscape of apartment into 4 types through the cluster analysis. An entrance landscape of apartment types of the entrance is classified as follows. 1) Type I: A model wall-fence type, 2) Type II: The side constructing a building-fence type, 3) type III: The side constructing a building-retaining wall-mixing tree type, 4) type IV: The moulding constructing a building-a retaining wall type.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2011년 춘계학술대회논문집
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• pp.210-217
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• 2011

Recently, research on evaluating thermal comfort by using CFD has been vigorously active. This research evaluates not only distribution of temperature and air flow analysing but also thermal comfort in indoor space by applying human model. But research of human model's shape, Grid characteristic and turbulence model has not yet been studied. In this paper, human model's shape, physical characteristic of variable Grid, and change of turbulence model has been studies by CFD. In this study. FLUENT is used for analysis and PMV(predicted Mean Vote), PPD(Predicted Percentage Dissatisfied) and EHT(Equivalent Homogeneous Temperature} are used for evaluation and comparison of thermal comfort. As a result, it shows that shape of CSP and lattice features does not affect on global flow field or evaluation on PMV, PPD. However, it demonstrates more precise result from evaluation of thermal comfort by equivalent temperature when it used detailed human model considering prism grid.

• 한국지반공학회논문집
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• 제24권2호
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• pp.15-25
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• 2008

압축성이 크고 지지력이 작은 연약지반에 구조물 축조 시 침하저감 및 지지력의 향상을 위한 다양한 공법이 필요하며 이러한 목적으로 팽이기초가 개발되어 사용되어왔다. 본 논문에서는 기존의 구형팽이기초에 형상의 변화를 준 다양한 팽이기초에 대한 수치해석을 실시하여 하중-침하 특성을 파악한 후 침하량 저감 효과가 입증된 부양팽이기초에 대하여 평판재하시험 및 수치해석을 실시하였다. 연구결과, 부양팽이기초는 연약지반의 침하 저감 및 지지력 향상에 효과를 발휘하는 것으로 나타났다.

• 한국추진공학회지
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• 제15권2호
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• pp.8-14
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• 2011

본 논문에서는 경사진 그레인 포트 형상을 가진 고체 연료를 사용한 하이브리드 로켓의 연소 특성을 실험적으로 연구하였다. $1^{\circ}$의 경사각을 갖는 수렴, 확산 형상 고체 연료는 원통형 연료에 비해 충전 효율이 6.8 % 더 높았다. 수렴 형상의 그레인 포트를 갖는 연료에서는 경사각이 없는 원통형 연료에 비해 동일 산화제 유속 구간에서 후퇴율이 평균 17.5 % 증가하였으나 확산 형상 연료에서는 후퇴율의 차이가 크지 않았다. 또한, 수렴 형상의 연료를 사용한 경우 특성속도 및 특성속도효율이 증가하였으며, 이를 통해 하이브리드 로켓 연료에서 수렴 형상의 그레인 포트가 연소 효율 및 성능을 개선하는데 효과적임을 확인하였다.

• 한국초전도ㆍ저온공학회논문지
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• 제1권2호
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• pp.37-42
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• 1999

The stability of high-temperature superconducting current leads for cryogenic devices are investigated. By assuming full transition from superconducting state to normal state at a transition temperature, the HTS current at a transition temperature, the HTS current lead shows bifurcation phenomenon. There is a bifurcation shape-factor, HTS leads have three steady state. Below the bifurcation shape-factor, the superconducting current lead is unconditionally stable, because there exists only one steady-factor HTS current lead is conditionally stable depending on the shape and intensity of disturbance.

• 공학논문집
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• 제7권1호
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• pp.99-103
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• 2005

The ferrimagnetic resonance technique, with the inclusion of shaper anisotropy effects, was used to obtain information about the early stages in the precipitation of magnesium ferrite from iron-doped magnesia. The very small magnesioferrite particles were produced by precipitation method from solid solution of iron ion in single crystal magnesia. The temperature dependence of the resonance anisotropy field for a coherent assembly of hyperfine magnesium ferrite precipitates was investigated in the range 100~400K. The results are interpreted in terms of the shape anisotropy of the precipitates.