• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1996.10a
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• pp.237-242
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• 1996

A theoretical formulation for the analysis of free vibration of clamped-free cylindrical shells with plates attached at arbitrary axial positions was derived and it was programed to get the numerical results which yield natural frequencies and mode shape of the combined system of plate and shells. The frequencies and mode shapes from theoretical calculation were compared with those of commercial finite element code, ANSYS as well as modal test in order to validate the formulation. The effects of the thickness and location of the plate were evaluated.

• Tunnel and Underground Space
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• v.33 no.2
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• pp.83-94
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• 2023

Unlike the conventional triaxial test cells for cylindrical specimens, which impose uniform lateral confining pressures, the GREAT (Geo-Reservoir Experimental Analogue Technology) cell can exert differential radial stresses using eight independently-controlled pairs of lateral loading elements and thereby generate horizontal stress fields with various magnitudes and orientations. In the preceding companion paper, GREAT cell tests were numerically simulated under different mechanical loading conditions and the validity of the numerical model was investigated by comparing experimental and numerical results for circumferential strain. In the present study, we simulated GREAT cell tests for an artificial sample containing a fracture under both mechanical loading and fluid flow conditions. The numerical simulation was carried out by varying the mechanical properties of the fracture surface, which were unknown. The numerical responses (circumferential strains) of the sample were compared with experimental data and a good match was found between the numerical and experimental results under certain mechanical conditions of the fracture surface. Additionally, the effect of fluid flow conditions on the mechanical behavior of the sample was investigated and discussed.

• Defense and Technology
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• no.10 s.164
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• pp.43-44
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• 1992

복합재 연소관과 노즐을 기계적 체결방법으로 결합하면 결합부위에서 재료의 불연속성과 기하학적 불연속성으로 인한 높은 응력집중이 발생해 구조적으로 매우 취약하게 됩니다. 복합재 연소관의 경우에는 내압을 받는 원통형 구조물이므로 기존의 평판에 대한 연구결과를 그대로 사용할수 없으므로, 이 글에서는 복합재 셀 구조물의 응력 및 파손 해석을 수행할수 있도록 1차전단변형 셀이론을 이용한 유한요소해석 프로그램을 개발하였습니다. 기계적체결부위의 모델링에 대해 검토하였으며 복합재료의 파손평가에 사용되는 여러가지 파손식을 적용해 비교하였습니다. 이 해석 방법을 이용해 복합재 연소관의 적층각, 볼트직경, 연소관의 끝단까지의 길이 등이 파손하중에 미치는 영향을 제시하였습니다

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1998.10a
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• pp.273-278
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• 1998

In this paper, basic micro-mechanical properties of unidirectional CFRP composite shell such as bonding strength, fiber volume fraction and void fraction are measured and tensile strength test is performed with a fixture. And then fracture surfaces are observed by SEM. In case of basic micro-mechanical properties, bonding strength is reduce with decreasing of radius of each ply in a shell for the effect of residual stress, fiber volume fraction is smaller than plate, and void fraction is vise versa. For these reason, tensile strength of shell is smaller than plate fabricated with same prepreg. For failure mode shell has many splitted part along its length, and it is assumed that this phenomenon is caused by the difference of bonding strength for residual stress.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.83.1-83.1
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• 2011

고체산화물 연료전지는 전해질의 양쪽에 cathode층과 anode층으로 구성되어 있다. 이러한 셀을 제작하기 위한 구성소재 코팅법으로는 EVD, CVD, sputter등의 기상공정과 screen printing, tape casting, dip coating등의 습식공정이 있다. 이중 현재 가장 널리 사용되고 있는 screen printing법은 코팅기판의 크기와 형태에 제한을 받아 원통형, 평관형에는 적용이 어렵다. 이러한 문제점을 해결하기 위해 본 연구에서는 electrolyte 지지체 위에 전사법을 통해 연료극(NiO-YSZ), 공기극(LSCF-GDC) 코팅층의 두께 및 형상을 제어할 수 있었으며 button cell을 제작하여 실제 SOFC에 적용이 가능함을 확인하였다.

• Proceedings of the KIPE Conference
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• 2018.11a
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• pp.125-126
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• 2018

본 논문에서는 원통형 NCA 리튬이온 배터리로 제작된 고출력 직렬조합 배터리팩으로 C-rate에 따른 전기적 특성 실험을 수행하였다. 방전 용량 프로파일 실험을 통해 배터리팩의 충/방전 C-rate가 배터리팩의 내부 파라미터에 어떠한 영향을 주는지 비교 분석한다. 실험을 통해 방전 용량과 전압 편차 파라미터를 측정한다. 전압 편차 그래프는 만방 구간과 만방 이후 휴지 구간의 셀 간 전압 편차를 중심으로 관찰하며 두 구간의 전압 편차를 비교한다. 3가지 파라미터를 비교하여 가장 효율적인 C-rate를 알아보았다.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.6 no.2
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• pp.49-58
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• 1997

The objective of this study is to investigate effects of prebuckling on the bucking of laminated compostie cylindrical shells, Both axial compression and lateral pressure are considered for laminated composite cylindrical shells with length to radius ratios. The shell walls are made of a laminate with several symmetric ply orientations. The study was using finite difference energy method, utilizing the nonlinear bifurcation branch with nonlinear prebuckling displacements. The results are compared to the buckling loads determined when membrane prebuckling displacements are considered.

• Proceedings of the KIPE Conference
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• 2019.07a
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• pp.453-454
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• 2019

본 논문은 ESS(Energy Storage System)의 과충전, 과방전으로 인한 열 폭주 현상을 방지하기 위한 사전 연구로 원통형 리튬이온 단일 셀의 충/방전에 따른 열 분포를 열화상 카메라로 촬영하여 분석하였다. 실험을 통한 열 분포 이미지를 학습 데이터로 구성하여, SOC(State of Charge)를 추정하는 CNN(Convolution Neural Network) 모델을 제안한다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.1
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• pp.46-51
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• 2009

In this work, the experimental investigation was carried out to evaluate the heat transfer performance on the shell side of shell-and-plate finned tube heat exchanger with three different tube numbers(9, 13 and 19). Oil flowing on the shell side was cooled by cold water flowing inside the tubes. A shell-and-tube heat exchanger of an oil cooler consisted of one shell pass and two tube passes with the inner tube diameter of 8.82 mm and the tube length of 575 mm. Mass flow rate was varied from 1.2 to $6.0\;m^3/h$ for oil and from 0.6 to $3.0\;m^3/h$ for cold water, respectively. From the experiment of shell-and-plate finned tube heat exchanger, the overall heat transfer coefficient of heat exchanger with 9 tubes was compared with that of 13 and 19 tubes. It was found that the heat transfer coefficients in shell side of heat exchanger with 9 plate finned tubes showed averagely 1.8 times and 2.3 times higher than those of 13 and 19 tubes, respectively.

• Journal of the Korean Geotechnical Society
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• v.38 no.11
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• pp.7-17
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• 2022

This study investigates the effect of cylindrical baffle arrays behind a rigid barrier on debris flow behavior and dynamic impact load. Small-scale tests were performed with various transverse blockage ratios and row numbers of baffles. High-speed cameras were installed at the flume's top and side, and load cells were installed in front of the rigid barrier. Moreover, glass beads simulated large boulders with debris flow in the flume. Test results revealed that the impact load of debris flow on the rigid barrier was significantly reduced using the cylindrical baffles behind the rigid barrier. In addition, the increased transverse blockage ratio of baffle arrays led to a greater impact load of debris flow because of flow suppression due to the baffle arrays.