• Journal of the Korean Institute of Intelligent Systems
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• v.8 no.6
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• pp.1-11
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• 1998

In this work, we propose a modeling method based on an artifical intelligence technique for a stem generator in a nuclear power plant. Modeling the steam generator is known to be difficult due to several facts; especially, the dynamics of the steam generator is nonminimum phase which is mainly caused by the swell and shrink phenomena from thermal effects. In order to overcome this difficulty, we adopt so-called logic processor whose structure itself has a logical meaning to be easily established and also efficiently learned. Such a manner, we could derive an useful model simulating the dynamics of the steam generator in a nuclear power plant.

• Journal of the Korea Convergence Society
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• v.8 no.9
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• pp.365-372
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• 2017

Squat exercise is one of the important free weight exercises that can safely and effectively expect the athletic performance by establishing the rationale. Therefore, it is necessary to study the side effects caused by incorrect exercise, scientific countermeasures and to develop a exercise estimation model. It is effective and accurate to use a variety of assistive devices to calibrate athletic posture. The issues of the structural analysis for designing a foot plate for squat exercise is to model the behavior by the dynamic behavior. It should be consider that the center of gravity of each segmented body is different when the maximum load is applied. It is applied to complete system design through simulation method with kinematic dynamic, ground reaction force and load analysis for the free weight exercise equipment, VR device, and safety foot plate. In this paper, the authors propose the design method for the vertical load distribution applied in the design of the foot plate used for the squat exercise mechanism, and based on these results, design make the more safe and reliable free weight exercise equipment system.

• Explosives and Blasting
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• v.33 no.1
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• pp.13-20
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• 2015

Recently, as the demand for development and utilization of underground space is increasing worldwide, the blast damaged zone has become a major issue in constructing underground structures. In this study, numerical analyses were performed for modelling a small-scale blasting of rock plates using PFC3D and ANSYS LS-DYNA. In order to verify the analysis results, several test blasts were conducted. It is concluded from the study that the numerical modelling methods well simulate the crack propagation procedure near blast holes under given conditions.

• The Transactions of the Korean Institute of Power Electronics
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• v.12 no.6
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• pp.491-499
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• 2007

The variation of a load characteristic in the motor drive is one of the most important consideration. Because the current flowing into the motor generally varies according to the load variation, it needs to design the motor drive circuit properly in accordance with the load variation. However, the load variation of the drum washing machine is irregular and large due to the water flow and reverse load torque. Therefore, to design the motor drive circuit considering this load pattern, simulation results shows the load pattern modeling of the drum washing machine based on the physical analysis in this paper.

• Tunnel and Underground Space
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• v.27 no.4
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• pp.185-194
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• 2017

This technical paper is a study on the unique displacements of Shotcrete Lining at the mined tunnel during excavation period through deep consideration with real time data from monitoring instrumentations correlation with the numerical analysis to identify the rock stresses and the rock spring points at the working face of the Conventional tunnelling by the Drill and Blast, based on the geological face mapping results of the project NS2, Transmission cable tunnel project in Singapore. The created geometry of numerical model was prepared to the real mined tunnel construction site including, vertical shaft, construction adit, tunnel junction area, and 2 enlargement caverns. The convergence measurements by the monitoring instrumentation were performed during the tunnel excavation and shaft sinking construction stages to guarantee the safety of complicated underground structures.

• Magazine of the Korea Concrete Institute
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• v.16 no.4 s.81
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• pp.70-77
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• 2004

콘크리트 구조물에 대한 많은 기준들의 요건에 따르면, 휨을 받는 철큰 콘크리트(RC) 보의 압축부에서의 응력은 일반적으로 일축의 응력-변형을 관계를 이용하여 계산한다. 이와 같은 접근은 가끔씩 압축력을 받는 콘크리트에서 부서짐이 발성할 때 보의 구조적 거동을 재현하지 못할 수 있다. 결과적으로, RC 구조물의 지지력과 그들의 연성은 근사적으로 평가된다. 본 논문에서는 압축을 받고 있는 콘크리트의 postpeak 거동은 활동면을 이용하여 모델링되었다. 이 활동 면의 모멘트-곡률곡선에서 연화부분에 그 원인이 있다. 제안된 활동현상의 수학적 표현은 압축력을 받는 콘크리트(즉, 연화부분의 거동이 압축영역의 크기와 변형률구배(곡배)에 의존하는)에 있어서 특정한 응력-변형률 관계를 정의하는 것이 얼마나 어려운지를 보여주고 있다.

• Magazine of the Korea Concrete Institute
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• v.10 no.3
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• pp.175-183
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• 1998

고강도콘크리트의 역학적 특성은 그 압축강도의 증가 이외에도 여러 가지 변화를 갖게 된다. 본 연구에서는 이와 같은 여러 특성의 변화 중 철근과의 부착특성에 관한 해석적 접근을 통하여 고강도콘크리트부재의 부착설계를 위한 이론적인 접근을 시도하였다. 해석의 변수로는 콘크리트의 압축강도, 부착길이 및 피복두께 등 3가지의 변수를 선정하였으며, 해석의 목적은 본 연구에 앞서 실시된 실험의 결과를 예측할 수 있는 단순화된 모델을 개발하고 이를 이용하여 부착실험의 결과를 해석적으로 분석하도록 하였다. 이에 따라 사용된모델은 실험에서 사용한 보단부형 부착시험체의철근과 콘크리트 부착부분의 기하학적 형상을 비교적 실제와 유사하게 모델링시킨 2차원의 평면모델을 사용하였다. 본 연구의 주요결과를 살펴보면 고강도콘크리트의 부착강도는 콘크리트의 피복두께에는 선형으로 비례하게 되나 부착길에는 비례하지 않는 것으로 나타났다. 이와 같은 결고는 기존의 실험결과와도일치하고있으며, 그 원인은 콘크리트의 강성증가에 따라 하중단측에 응력이 집중됨으로써 보통강도콘크리트의 경우와 같이 응력의 균등한 배분을 기대할 수 없기 때문으로 나타났다.

• Journal of the Korean Geotechnical Society
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• v.31 no.9
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• pp.5-15
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• 2015

In this study, rainfall-induced slope stability and coupling effect are investigated using hydro-mechanical finite element model. This model is developed by formulating constitutive and coupled balance equations and is verified by comparing the numerical results with field matric suction. The homogeneous soil layer (soil column) and soil slope are modeled by this model, and the results of variation in matric suction, mean effective stress, porosity, displacement, factor of safety are compared with those of staggered analysis. It is found that the vertical and horizontal displacement from coupling analysis considering change in porosity is larger than that of staggered analysis. The displacement and matric suction from coupling analysis by rainfall infiltration can affect slope instability, which shows a progressive failure behavior. The lowest factor of safety is observed under short-term rainfall. This results confirm the fact that coupling analysis is needed to design soil slope under severe rain condition.

• Journal of the Korean Geotechnical Society
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• v.19 no.5
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• pp.59-67
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• 2003

In this study, the change in hydraulic conductivity according to the changes in the contact area, aperture, confining pressure and temperature was observed to improve the reliability of the analysis of underground water flow. Also, the mechanical and thermal properties of domestic crystalline rocks in a great depth were obtained. It was found that the averaged intial aperture ranged from 544.33${\mu}{\textrm}{m}$ to 898.62${\mu}{\textrm}{m}$ and it followed a log-normal distribution. The hydraulic conductivity decreased with the increase of normal stress on the fracture surface and the hydraulic conductivity decreased as temperature increased. The change in hydraulic conductivity was strongly correlated with the change in contact area. It was verified by experiments that hydraulic conductivity was inversely proportional to the contact area. The measured mechanical and thermal properties were very close to the existing typical properties of domestic granites.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.9
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• pp.1003-1008
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• 2012

The paper presents an Experimental Vehicle Model (EVM), that utilizes the kinematic characteristics of suspensions from SPMD test data. The relative displacement and orientation of a wheel with respect to the body are represented as a function of the vertical displacement of the wheel. The equations of motion of the vehicle are formulated in terms of local coordinates that do not require coordinate transformation, which improves the efficiency of dynamic analysis. The EOM was modularized for each suspension model, and a $6{\times}6$ vehicle model was obtained by combining six suspensions. The analysis results were compared with ADAMS to verify the accuracy of the EVM. This study also verifies the feasibility of real-time simulation with the developed EVM. For a vehicle simulation for 1 ms, the real simulation time required within 20% of the prescribed time. This result shows that the EVM meets the real-time simulation requirements.