• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.799-802
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• 2002

Korea Aerospace Research Institute has been developing a 50-meter class airship to demonstrate the technology to be used in the development of a stratospheric airship, and importance of accurate prediction of the dynamic behavior of an airship before flight test is widely conceived. The added mass has large impact on the dynamic characteristics of an airship unlike for an airplane and the added mass of the airship with empennage is predicted in this paper. At first, the usability of the strip theory is examined which integrates the analytic two dimensional results in the cross section along the longitudinal axis. A panel method with the surface distribution of sources is developed and its validity is also examined. Finally, the panel method with both source and doublet distributions is implemented, and it is validated and applied for the calculation of the added mass of a 50-meter class airship. Using the methods developed, the influence of empennage and control surface deflection on the added mass property of the airship is studied.

• 대한기계학회논문집A
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• 제25권3호
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• pp.520-528
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• 2001

This paper investigates a resonant microaccelerometer that measures acceleration using a built-in micromechanical resonator, whose resonant frequency is changed by the acceleration-induced axial force. A set of design equations for the resonant microaccelerometer has been developed, including analytic formulae for resonant frequency, sensitivity, nonlinearity and maximum stress. On this basis, the sizes of the accelerometer are designed for the sensitivity of 10$^3$Hz/g in the detection range of 5g, while satisfying the conditions for the maximum nonlinearity of 5%, the minimum shock endurance of 100g and the size constraints placed by microfabrication process. A set of the resonant accelerometers has been fabricated by the combined use of bulk-micromachining and surface-micromachining techniques. From a static test of the cantilever beam resonant accelerometer, a frequency shift of 860Hz has been measured for the proof-mass deflection of 4.3${\pm}$0.5$\mu\textrm{m}$; thereby resulting in the detection sensitivity of 1.10${\times}$10$^3$Hz/g. Uncertainty analysis of the resonant frequency output has been performed to identify important issues involved in the design, fabrication and testing of the resonant accelerometer.

• 한국해양학회지
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• 제19권2호
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• pp.163-171
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• 1984

대기 및 해양적 요인들이 동해의 해면을 통한 열교환에 미치는 영향을 구명 하기 위하여, 해양의 열수지에 근거한 해석적인 모델을 만들고, 이 모델을 통하여 동해상 해면 열교환의 각 성분과 대기 온도의 연변화를 해석적으로 재현 (simulation) 하였다. 모델에 의한 이론적인 결과에 의하면, 동해에서 난류에 의한 열수송이 클수록 열복사, 잠열 및 현열의 방출이 증가한다. 그리고 표면수온이 증 가 함에 따라 잠열은 증가하지만, 역복사와 현열은 감소한다. 동해에서 연평균 수온이 1$^{\circ}C$ 증가하면 해상 기온의 연평균이 1.2$^{\circ}C$ 증가하는 효과를 가져오며, 해양의 저열량의 크기는 해면을 통한 열교환의 연변화에 지대한 영향을 미친다.

• 한국정밀공학회지
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• 제27권12호
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• pp.92-98
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• 2010

The design of press bonding tool in LCD module equipment is a very complex and difficult task because many design able variables are involved while their effects are not known. It takes longtime experiments and much expenses to verify the effects of these design variables. However the optimization of bonding tool using OLB(outer lead bonding) and PCB Bonding is a very important problem in LCD manufacturing process, so much design efforts have been made for improving the bonding tool performance. In this paper, a reasonable and fast process which gives optimized solution under the design requirements has been presented. Both analytical and statistical methods are employed in this process. A reliable analytic model using experiment-oriented FE analysis can be obtained, in which the regression equations that predict the tool efficiency from various DOE method are found. Improvement of tool efficiency could be estimated by the regression equations using meaningful factors converged by RSM(Response Surface Method). With this process a reasonable optimized solution that meets a variety of design requirements can be easily obtained.

• Composites Research
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• 제17권2호
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• pp.1-8
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• 2004

본 논문은 겹판 스프링의 정적 스프링 상수를 가지고 복합재료 데이퍼 스프링을 최적설계 하였다. 두께와 폭을 설계변수로 실정하였다. 회귀모형의 목적함수는 상용 해석 프로그램을 통해 얻었다. 회귀모형의 함수를 가지고 회귀계수를 계산한 후, DOT를 이용하여 최적해를 구하였다. 설계에 이용된 복합재료로는 E-glass/epoxy와 carbon/epoxy를 선정하였고 겹판 스프링과 비교 해석하였다. 그 결과 정적 스프링 상수는 최적화된 복합재료 스프링들과 겹판 스프링이 1％내로 일치함을 보였다.

• 대한조선학회지
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• 제25권2호
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• pp.19-30
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• 1988

Sectional added masses of an elastic beam vibrating vertically on the free surface in higher harmonic modes are evaluated. Hydrodynamic interactions between neighboring sections, which strip theory ignores, are considered for modal wave lengths of the order of magnitude of cross-sectional dimensions of the body. An approximate solution of modified Helmholtz equation which becomes a singular perturbation problem at small wave lengths is secured to get an analytic expression for added masses attending higher harmonic modes. As a bound of the present theory, the modified Helmholtz equation is solved for the long flat plate vibrating at high frequency on the water surface without any limitations on modal frequency. Finally, extensive series of numerical calculations are carried out for ship-like forms. It is found that when modal wave length is comparable to or shorter than a typical cross-sectional dimension of a body, sectional interaction effects are large which result in considerable reductions in added masses. For a fuller section, the ratio of added mass reduction is greater. In the limit of vanishing sectional area, the added masses approach to that of flat plate of equal beam. It is shown that the added mass distribution for a Legendre modal from can be determined form the present theory and that the results agree with the extensive three-dimensional determination of Vorus and Hilarides.

• 한국HCI학회:학술대회논문집
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• 한국HCI학회 2007년도 학술대회 3부
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• pp.326-333
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• 2007

To simulate solid dynamics,a we must com-pute the mass, the center of mass, and the products of inertia about the axes of the body of interest. These mass property computations must be continuously re-peated for certain simulations with rigid bodies or as the shape of the body changes. We introduce a GPU-friendly algorithm to approximate the mass properties for an arbitrarily shaped body. Our algorithm converts the necessary volume integrals into surface integrals on a projected plane. It then maps the plane into a frame-buffer in order to perform the surface integrals rapidly on the GPU. To deal with non-convex shapes, we use a depth-peeling algorithm. Our approach is image-based; hence, it is not restricted by the mathematical or geometric representation of the body, which means that it can efficiently compute the mass properties of any object that can be rendered on the graphics hardware. We compare the speed and accuracy of our algorithm with an analytic algorithm, and demonstrate it in a hydrostatic buoyancy simulation for real-time applications, such as interactive games.

• 한국안전학회지
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• 제27권3호
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• pp.9-14
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• 2012

The objectives of this study were to compare the results of HSL (Health and Safety Laboratory) ramp test with perceived sense of slip onto the several different floor surfaces under contaminated conditions. There are a variety of approaches from biomechanical measurements to psychophysical test and human perception. However, controversies over these approaches still remain. Some widely accepted methods need to be improved. AHP (Analytic Hierarchy Process) was used to evaluate the perception of slipperiness of seven different floor surfaces under the contaminated condition with glycerol solution. Twelve subjects worn same footwear and walked with self-selected step and cadence along the test floors. The angle of inclination obtained for water wet condition using 5 l/min with HSL ramp test was compared to perception of slipperiness. The surface roughness ($R_z$) related very well both AHP (r=0.95) and ramp test (r=0.92). The high significant correlation (r=0.90) was found between AHP and HSL ramp test.The HSL ramp test values (Coefficient of Friction, COF) according to subjective evaluation were divided into two categories. There were high correlations between test results (subjective evaluation, HSL ramp test) and surface roughness in Rz. Perception rating obtained with AHP showed a high correlation with COF obtained with HSL ramp test.

• 한국추진공학회지
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• 제11권5호
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• pp.14-22
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• 2007

측면 표면 기울기가 변화하는 역 사다리꼴 핀이 2차원 해석적 방법을 사용하여 최적화된다. 핀 바닥 경계조건을 위해서, 내부유체로부터 내벽까지의 대류와 내벽부터 핀 바닥까지의 전도가 고려된다. 핀 끝 면으로부터의 열손실은 무시되지 않는다. 실제적인 핀 길이에서의 최대 열손실, 그 최대 열손실이 발생할 때의 최적의 효율, 핀 길이 그리고 핀 바닥 높이가 핀 내 외부의 대류특성계수의 함수로 나타내어진다. 결과 중 하나는 핀 바닥 높이에 대한 핀 끝 높이의 비가 커질수록 최적의 핀 형상은 두껍고 짧아지는 형상이 됨을 보여준다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2003년도 춘계학술대회 논문집
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• pp.376-381
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• 2003

This study is focused on the dynamic response of curved bridge when the rubber tired AGT vehicles is running with alternative articulations. For the analytic approach, there is necessary for the three dimensional vehicle model with 11 degree of freedom and the three dimensional curved bridge model by means of finite element method. It can be described by conventional Lagrangian formula with respect to the dynamic interactions between vehicles and its met bridge. The formula is implemented by Fortran language on the simulation program designated BADIA II(Bridge-AGT Dynamic Interaction Analysis II). The solutions of the formula are derived by Newmark- ${\beta}$ method. The BADIA II is for the dynamic interactions between vehicle and curved bridge in terms of the roughness of running surface and guide rail. The applicability of the BADIA II is verified in terms of displacement and modal frequency. This study is described that the dynamic interactive behaviors between the rubber tired AGT vehicle and curved bridge in terms of the radius of curvatures of curved bridge, vehicle articulations, vehicle speeds, vehicle weights, flatness of running surface and roughness of guide rail using BADIA II.