• 한국수학교육학회지시리즈B:순수및응용수학
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• 제5권1호
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• pp.55-63
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• 1998

A Gauss map of m-dimensional distribution on a Riemannian manifold M is called a harmonic Gauss map if it is a harmonic map from the manifold into its Grassmann bundle $G_m$(TM) of m-dimensional tangent subspace. We calculate the tension field of the Gauss map of m-dimensional distribution and especially show that the Hopf fibrations on $S^{4n＋3}$ are the harmonic Gauss map of 3-dimensional distribution.

• Earthquakes and Structures
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• 제2권1호
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• pp.43-64
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• 2011

One-dimensional rod theory is very effective as a simplified analytical approach to large scale or complicated structures such as high-rise buildings, in preliminary design stages. It replaces an original structure by a one-dimensional rod which has an equivalent stiffness in terms of global properties. The mechanical behavior of structures composed of distinct constituents of different stiffness such as coupled walls with opening is significantly governed by the local variation of stiffness. Furthermore, in structures with setback the distribution of the longitudinal stress behaves remarkable nonlinear behavior in the transverse-wise. So, the author proposed the two-dimensional rod theory as an extended version of the rod theory which accounts for the two-dimensional local variation of structural stiffness; viz, variation in the transverse direction as well as longitudinal stiffness distribution. This paper proposes how to deal with the two-dimensional rod theory for structures with setback. Validity of the proposed theory is confirmed by comparison with numerical results of computational tools in the cases of static, free vibration and forced vibration problems for various structures. The transverse-wise nonlinear distribution of the longitudinal stress due to the existence of setback is clarified to originate from the long distance from setback.

• Journal of Advanced Marine Engineering and Technology
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• 제29권1호
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• pp.25-33
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• 2005

When a circular tube with uniform heat generation within the wall was placed in a cross flow, heat flows by conduction in the circumferential direction due to the asymmetric nature of the fluid flow around the perimeter of the circular tube The circumferential heat flow affects the wall temperature distribution to such an extent that. in some cases, significantly different results may be obtained for geometrically similar surfaces. In the present investigation, the effect of circumferential wall heat conduction is investigated for forced convection around circular tube in cross flow of air and water Two-dimensional temperature distribution $T_w(r,{\theta})$ is calculated through the numerical analysis. The difference between one-dimensional and two-dimensional solutions is demonstrated on the graph of local heat transfer coefficients. It is observed that the effect of working fluid is very remarkable.

• 한국정밀공학회지
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• 제18권1호
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• pp.187-194
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• 2001

The objective of this study is to develop a model for the grinding process for predicting the temperature, thermal stress and thermal deformation. The thermal load during grinding is modeled as uniformly distributed, 2D heat source moving across the surface of elastic half space, which is insulated or subjected to convective cooling. That non-dimensional temperature distribution, non-dimensional longitudinal stress distribution and non-dimensional thermal deformation distribution are calculated with non-dimensional heat source half width and non-dimensional heat transfer coefficient. Finite element models are developed to simulate moving heat source, which is modeled as uniformly or triangularly distributed, the FEM simulation is compared with numerical solution.

• 설비공학논문집
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• 제11권5호
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• pp.579-587
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• 1999

The flow distribution characteristics in a complex duct system have been investigated in this paper by three means, namely experimental measurement, numerical simulation and the Extended T-method analysis. While the exit flow rates predicted by the three-dimensional CFD calculation and those given by the experiment show a close agreement, the results from the one-dimensional Extended T-method are found to differ from the experiment by -22.2% to 26.3% for the various exits. These discrepancies may be attributed to the underlying limitation concerning the fitting loss coefficients, which assume that the flow in front of the fittings is fully developed. It is proposed that, in order to analyse the three-dimensional flow distributions in a complex duct system by one-dimensional analysis such as the Extended T-method, further Improvements to the fitting loss coefficients should be made.

• 한국산학기술학회논문지
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• 제12권11호
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• pp.4718-4725
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• 2011

본 연구는 성능 해석을 통하여 1600cc급 흡기매니폴드의 흡기유량 및 분배특성에 대한 연구를 수행하였다. 일차원 엔진 성능해석 프로그램과 3차원 유동해석프로그램을 이용하여 해석을 수행하였다. 흡기 매니폴드의 정상상태 유동해석을 수행한 결과, 일차원 유동해석과 3차원 유동해석의 유량계수 표준편차는 1% 미만으로 우수한 분배특성을 나타내었다. 일차원 해석 결과가 3차원 결과 대비 미소하게 증가된 결과를 보였지만 동등한 유량계수 경향성을 나타냈다. 비정상상태 해석은 분배특성 측면에서 정상상태 해석 결과와 유사한 결과를 보였으며, 정상상태 해석결과를 통한 비정상상태 분배특성의 예측이 가능함을 확인하였다.

• 한국자동차공학회논문집
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• 제10권4호
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• pp.223-233
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• 2002

The air distribution duct with multiple outlets is an essential part of automotive air-conditioning system In a bus. The estimation of airflow rate in an automotive air-conditioning duct is typically very complicate due to large variations in cross-sectional area and abrupt changes in flow direction, as well as unbalanced distribution of the flow. In this paper, the flow characteristic in a duct with multiple outlets is investigated through experiment, CFD simulation and a one-dimensional simulation. Numerical simulations have been performed for two simplified air conditioning ducts with multiple outlets used in a medium bus. The three dimensional Navier-Stokes code was used to evaluate the overall pressure, velocity Held, and distribution rate at each diffuser according to the change of various design parameters such as ratio of cross-sectional area and radius of bifurcated region. In addition, a one-dimensional program based on Bernoulli equation was developed to obtain optimized diffuser area required to equalize discharge flow rate at each outlet. As a result of this study, optimized diffuser area of design variable by one-dimensional program was very reasonable as compared to the trend deduced from CFD Simulation. Therefore, the simple and convenient one-dimensional analysis developed in this study can be applied in practical design procedure for air-conditioning duct.

• 한국지반공학회지:지반
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• 제12권1호
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• pp.87-110
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• 1996

터널굴착시, 막장부근의 3차원 효과를 반영하기 위해 주로 경험적인 하중분담률 개념을 도입한 2차원 유한차분법 수치해석이 수행된다. 본 논문에서는 3차원 수치해석을 수행하고 그 해석 결과와 2차원 수치해석 결과를 비교함으로써 합리적인 하중분담률의 적용 가능성 및 막장 부근의 음력집중 문제를 규명하고자 하였다. 무지보 굴착길이, 초기지중응력, 지반종류, 단면크기와 터널심도등의 하중분담률에 주된 영향을 미치는 인자들에 대한 매개변수 연구를 수행하고, 그 결과를 토대로 서울지하철의 대표적인 단면에 대해 적용가능한 하중분담률을 추천하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.162-165
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• 2005

The objective of this research work is to investigate into the three-dimensional temperature distribution using quasi steady-state heat transfer analysis fur the case of the laser cutting of CSP 1N sheet using high power CW Nd:YAG laser. The laser heat source is assumed as a volumetric heat source with a gaussian heat distribution in a plane. Through the comparison of the results of analyses with those of the experiments, the optimal finite element model is obtained. Finally, characteristics of the three-dimensional heat transfer and temperature distribution have been estimated by the optimal finite element model.

• 대한기계학회논문집
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• 제18권1호
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• pp.101-112
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• 1994

The measurement of residual stress distribution of $Si_3N_4/SUS304$ joint was performed on 23 specimens with the same joint condition using PSPC type X-ray stress measurement system and the two-dimensional elastoplastic analysis using finite element method was also attempted. As results, residual stress distribution near the interface on the ceramic side of the joint was revealed quantitatively. Residual stress on the ceramic side of the joint was turned out to be tensional near the interface, maximum along the edge, varying in accordance with the condition of the joint and variance to be most conspicuous for the residual stress normal to the interface characterized by the stress singularities. In the vicinity of the interface, the high stress concentration occurs and residual stress distributes three-dimensionally. Therefore, the measured stress distribution differed remarkably from the result of the two-dimensional finite-element analysis. Especially at the center of the specimen near the interface, the residual stress, $\sigma_{x}$ obtained from the finite element analysis was compressive, whereas measurement using X-ray yielded tensile $\sigma_{x}$. Here we discuss two dimensional superposition model the discrepancy between the results from the two dimensional finite element analysis and X-ray measurement.