• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.11
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• pp.1757-1763
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• 2010

Flywheel energy storage system (FESS) is defined as a high speed rotating flywheel system that can save surplus electric power. The FESS is proposed as an efficient energy storage system because it can accumulate a large amount of energy when it is operated at a high rotating speed and no mechanical problems are encountered. The FESS consists of a shaft, flywheel, motor/generator, bearings, and case. It is difficult to simulate rotor dynamics using common structure simulation programs because these programs are based on the 3D model and complex input rotating conditions. Therefore, in this paper, a program for the FESS based on the 2D FEM was developed. The 2D FEM can model easier than 3D, and it can present the multi-layer rotor with different material each other. Stiffness changing of the shaft caused by shrink fitting of the hub can be inputted to get clear solving results. The results obtained using the program were compared with those obtained using the common programs to determine any errors.

• Journal of the Korean Society for Railway
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• v.18 no.3
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• pp.175-185
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• 2015

Generally, in the train area, switch tracks have required high reliability because this system is directly associated with derailment. Especially, switch tracks of Maglev vehicles must be moved in terms of the whole geometric characteristics, in which the bogies are encased in the switch track. For this reason, switch track was constructed with steel lighter than concrete girders. But, the steel switch track was weak because of structural vibration as well as structural deformation. Therefore, it is important to predict the levitation stability when a vehicle passes over flexible switch track. The aims of this paper are to develop a coupled dynamic model to describe the relationship between a Maglev vehicle and switch track and to predict the levitation stability. In order to develop the coupled dynamic model, a three dimensional vehicle model was developed based on multibody dynamics; a switch model was made using the modal superposition method. And, the developed model was verified using comparison measured data.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.7 s.196
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• pp.133-138
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• 2007

It is important to understand the characteristics of amputee gait to develop more advanced prostheses. The aim of this study was quantitatively to analyze the stair climbing task for the above-knee amputee with a prosthesis and to predict muscle forces and joint moments at musculoskeletal joints by dynamic analysis. The three-dimensional musculoskeletal model of lower extremities was constructed by gait analysis and transformation software for one above-knee amputee and ten healthy people. The measured ground reaction forces and kinematical data of each joint by gait analysis were used as input data during inverse dynamic analysis. Lastly, dynamic analysis of above-knee amputee during stair climbing were performed using musculoskeletal models. The results showed that summed muscle farces of hip extensor of amputated leg were greater than those of sound leg but the opposite results were revealed at hip abductor and knee flexor of amputated leg. We could also find that the higher moments at hip and knee joint of sound leg were needed to overcome the flexion moment caused by body weight and amputated leg. In conclusion, dynamic analysis using musculoskeletal models may be a useful mean to predict muscle forces and joint moments for specific motion tasks related to rehacilitation therapy..

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.167.1-167.1
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• 2012

본 논문에서는 인공위성 전개장치용 테잎힌지 특성해석을 수행하고 그 결과에 대하여 분석하였다. 테잎힌지를 이용한 전개장치는 신뢰성이 높고, 형상이 매우 단순하며, 제작단가 또한 저렴하여 우주용 안테나 및 태양전지판에 널리 이용이 되고 있다. 테잎힌지를 이용한 전개장치의 전개특성은 테잎힌지 특성에 의하여 좌우가 되므로 안전성 있는 전개장치 설계를 수행하기 위해서는 가능한 정확한 해석이나 계산이 요구되어진다. 초기에는 쉘 이론등을 바탕으로 테잎힌지의 전개특성을 계산하는 식들이 연구되었으나 테잎힌지의 강한 비선형성 때문에 정확성이 많이 떨어지는 큰 단점이 존재하였다. 이후 많은 연구를 통하여 유한요소모델을 이용한 비선형해석을 통하여 비로소 정확한 전개특성을 해석할 수 있게 되었다. 본 논문에서는 다물체 동역학해석프로그램인 리커다인의 유연체 해석모듈을 이용하여 테잎힌지에 대한 특성해석을 수행하였다. 해석결과 신뢰성 있는 테잎힌지의 전개거동 확인 및 전개특성을 계산할 수 있었다.

• Journal of Biomedical Engineering Research
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• v.24 no.5
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• pp.447-451
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• 2003

A new method for analyzing the bone-remodeling process using quasi-molecular dynamics was proposed in this study. The effect of pressure due to bone marrow, which could not be considered in previous methods, was also considered in this method. Bone-remodeling response of the 2D vertebral body of lumbar spine to a uniaxial compressive displacement of 1.8564mm. corresponding to approximately 2kN of compressive load, was studied. Converged shape change of the cortical shell and rearrangement of cancellous bone structure matched well with a normal shape of the vertebral body. The calculated responses in the spinal elements also shows closed results compared with experimental results.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.5
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• pp.575-584
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• 2014

In this study, the NREL 5 MW wind turbine tower model was optimized according to the multi-body dynamics and reliability-based design. The mathematical model was defined as a link-joint system including dynamic characteristics derived from Timoshenko's beam theory. For the optimization problem, the sensitivities to variations in the tower thicknesses and inner and outer diameters were acquired and arranged in terms of safety and efficiency according to bending stress and buckling standards. An optimal design was calculated with the advanced first-order second moment method and used to define a finite element model for validation. The finite element model was simulated by static analysis. The relationship between the multi-body dynamic and finite element method throughout the process was investigated, and the optimal model, which had high endurance despite its low mass, was determined.

• Korean Chemical Engineering Research
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• v.55 no.6
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• pp.807-815
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• 2017

This study investigated the removal efficiency of residual pentane from paclitaxel according to the drying temperature in the case of rotary evaporation, and performed a kinetic and thermodynamic analysis of the drying process. At all the temperatures (25, 30, 35, 40, and $45^{\circ}C$), a large amount of the residual solvent was initially removed during the drying, and the drying efficiency increased when increasing the drying temperature. Five drying models (Newton, Page, modified Page, Henderson and Pabis, Geometric) were then used for the kinetic analysis, where the Henderson and Pabis model showed the highest coefficient of determination ($r^2$) and lowest root mean square deviation (RMSD), indicating that these models were the most suitable. Furthermore, in the thermodynamic analysis of the rotary evaporation, the activation energy ($E_a$) was 4.9815 kJ/mol and the standard Gibbs free energy change (${\Delta}G^0$) was negative, whereas the standard enthalpy change (${\Delta}H^0$) and standard entropy change (${\Delta}S^0$) were both positive, indicating that the drying process was spontaneous, endothermic, and irreversible.

• Journal of Aerospace System Engineering
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• v.14 no.5
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• pp.1-8
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• 2020

The aeroservoelastic analysis that deals with the interactions of the inertial, elastic, and aerodynamic forces and the influence of the control system have been performed. MSC Nastran was used for the free vibration analysis of the structure model as the pre-analysis. ZAERO was used to calculate the unsteady aerodynamic forces. The unsteady aerodynamic forces were verified by comparing with Doublet Hybrid Method. Karpel's Minimum-State Approximation method was used for approximation of the aerodynamic forces to the Laplace domain in the frequency domain. The aeroservoelastic state-space equation was obtained by combining the aeroelastic equation with the actuator dynamics. The analysis of aeroservoelastic stability concerning the elevator input of the high aspect ratio model was performed. The root-locus method and time-integration method were used for the analysis of aeroservoelastic in frequency and time domain.

• Journal of IKEEE
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• v.11 no.4
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• pp.137-144
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• 2007

Fire Control System(FCS) errors can be classified as hardware errors and software errors, and one of the software errors is from target tracking filter which estimates target's location, velocity, acceleration, and so on. It affects function of ballistic calculation equipment significantly. For gun to form predicted hitting point accurately and enhance hitting rate, we need status information of target's future location. Target tracking filter algorithms consist of Single Singer Model, Fixed Gain filter algorithm, IMM, PBIMM and so on. This paper will design IMM tracking filer, which is going to be! applied to domestic warship. Target tracking filter using CV model, Song model and CRT model for IMM tracking filter is made, and tracking ability is analyzed through Monte-Carlo simulation.

• Journal of Ocean Engineering and Technology
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• v.4 no.2
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• pp.35-40
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• 1990

해양 산업에서 심해로의 이동은 해양 구조물의 계류 장치의 중요성을 부각시켰고 그에 따른 기본적인 연구로서의 케이블 동력학에 대한 흥미를 일깨웠다. 거친 해상에서 케이블에 형성될 수 있는 큰 동장력과 기하학적 비선형성의 고려는 케이블의 비선형적 거동 해석에 주요 인자가 될 것이다. 또한 매우 큰 동장력 증폭에 의한 음의 큰 동장력은 케이블의 양의 정장력을 초과할 수 있고, 따라서 전체장력은 영 또는 음이 될 수 있다. 비선형 유체 항력을 포함한 모든 비선형성을 갖는 케이블의 이론적 해석 모델을 개발하고, 수치 결과와 기존의 실험 결과를 비교한다.