• 소성∙가공
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• 제12권8호
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• pp.693-701
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• 2003

In this paper, the influence of frictional conditions on the backward impact extrusion of aluminum battery casing with large aspect ratio has been investigated. In the simulation, MSC.Superforge, a package based on the finite volume method, is used for the extrusion analysis. The formability and earing problem during the production have been evaluated by studying the sensitivity to frictional effects. During the sensitivity analysis, the friction factor was varied from 0.02 to 0.24. As the friction factor is increased, the forming height of the narrow edge is decreased, and the forming height of the wide edge is increased. When the friction factor becomes 0.2, the earing problem does not occur The experimental results show a good agreement with analytical results.

• 한국해양공학회지
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• 제11권4호
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• pp.102-110
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• 1997

A two dimensional shallow-water flow around a cavity driven by a sinusoidally oscillating external flow was studied numerically with an Ekman pumping model. A container model of "T" shape was constructed in the numerical computation for comparison with the experimental observation. The material transport in the external region is in good agreement with the experimentally recorded particle trajectories. It turns out that two large coherent vortices situated in the exterior region of the cavity are responsible for clockwise and counterclockwise drift motions, in large scale, of particles. The Ekman pumping model suggested in this study was found to be satisfactory.isfactory.

• 대한기계학회논문집
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• 제18권10호
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• pp.2698-2705
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• 1994

In this paper, the fluid flow and stirring in a rectangular tank focussing on the effect of the plate length is studied numerically and experimentally. the flow model and the method of analysis are the same as those reported previously. The stirring effect changes considerably when the plate length is varied. When the plate is short, the friction at the bottom wall reduces the strength of the vortical flow resulting in a lower stirring effect. When the plate is long, the stirring effect is decreased due to the growth of the regular regions near the lower corners. The stirring effect is the best when the plate length is roughly half the width of the container.

• 대한기계학회논문집B
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• 제30권6호
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• pp.568-577
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• 2006

Developed in this study is a nonlinear Ekman pumping model to be used in simulating the rotating flows with quasi-three-dimensional Navier-Stokes equations. In this model, the Ekman pumping velocity is given from the solution of the Ekman boundary-layer equations for the region adjacent to the bottom wall of the flow domain; the boundary-layer equations are solved in the momentum-integral form. The developed model is then applied to rotating flows in a rectangular container receiving a time-periodic forcing. By comparing our results with the DNS and experimental data we have validated the developed model. We also compared our results with those given from the classical Ekman pumping model. It was found that our model can predict the rotating flows more precisely than the classical linear model.

• 한국식품영양과학회지
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• 제43권7호
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• pp.1095-1103
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• 2014

본 연구에서는 오징어 개별 포장체를 개발하여 포장하지 않은 오징어와 저온 저장에서의 생존율을 비교함으로써 개별포장체를 활용한 유통시스템을 개발하고자 하였다. 개별 포장체를 이용한 활오징어는 저온 저장($10^{\circ}C$, $8^{\circ}C$, $6^{\circ}C$, $4^{\circ}C$, $2^{\circ}C$, $0^{\circ}C$) 조건 하에서 각 10마리씩 저장하였다. $6^{\circ}C$에서 격리 포장된 활오징어는 72시간까지 84%의 우수한 생존율을 나타내었고 이후 생존율이 감소하다 120시간까지 60% 이상의 생존율을 나타내었다. 또한 최대 7일까지 생존하는 것을 관찰하였다. 최적 온도는 $5^{\circ}C$였으며 $5^{\circ}C$에서 96시간 저장했을 때 70% 우수한 생존율을 나타내었고 최대 7일까지 생존이 가능하였다. 냉장트럭을 이용한 유통 실험에서 $5^{\circ}C$ 저온에서 16시간까지 100%의 우수한 생존율을 나타내었고 저장 20시간 이후에도 90% 이상의 우수한 생존율을 보였다. 냉장트럭에 적재할 용기 실험에서는 사각형의 저장용기가 유리하였다. 상자에 공급하는 최소 해수량 실험에서는 20 L 이상의 해수량에서 15시간 이상, 100% 생존하는 것을 확인하였다. 따라서 오징어 한 마리당 2 L의 해수가 필요한 것으로 판단되었다. 냉장트럭 운송 후 보관 수조의 최적 온도는 $5^{\circ}C$였으며 $5^{\circ}C$에서 저장 72시간까지 90% 이상의 생존율을 나타내었고 최대 7일까지 생존이 가능하였다. 따라서 본 연구 결과, 활오징어의 유통 시 개별 포장체를 사용하여 사각용기에 2 L의 해수를 같이 담아 $5^{\circ}C$의 냉장트럭으로 유통하는 것이 가장 바람직한 것으로 나타났다.

• 한국재난정보학회 논문집
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• 제19권2호
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• pp.292-304
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• 2023

연구목적: 일상생활의 편의를 위해 개발된 고흡수성 중합체가 생산 및 저장 사업장에서 크고 작은 발화 사고가 발생하고 있는 바, 이에 대한 화재사고 예방대책 수립을 위한 실험적인 기초자료의 확보를 위해 이 연구를 수행하였다. 연구방법: 시료용기를 가로 및 세로는 0.2m로 고정하고, 폭을 각각 3cm, 5cm, 7cm, 그리고 14cm의 크기로 직육면체 형태로 하여 무한평판에 접근하게 하였다. 미리 설정된 온도제어 프로그램에 따라 소정의 온도로 가열되게 한 항온조 중심부에 시료용기를 고정시키고 중심부의 온도가 설정하여 둔 온도보다 20℃이상 상승한 경우를 ｢발화｣한 것으로, 시료의 중심부 온도가 설정하여 둔 온도와 유사하게 지속되었을 경우를 ｢비발화｣한 것으로 판정하였다. 연구결과: 자연발화의 한계온도는 시료용기의 폭이 3cm일 때 212.5℃, 5cm일 때 202.5℃, 7cm일 때 192.5℃, 그리고 14cm일 때에는 177.5℃로 산출되었다. 최고의 온도에 도달되는 발화를 위한 유도시간은 3cm일 경우 약 42시간, 5cm일 경우 약 91시간, 7cm일 경우 약 151시간, 그리고 14cm일 경우 약 300시간으로 나타났다. 결론: ① 시료용기의 크기가 커질수록 자연발화온도는 낮아지고, 최고의 온도에 도달되는 발화를 위한 유도시간은 길어졌다. ② 겉보기활성화에너지는 39.30 [kcal/mol]으로 산출되었으며, 상관도는 99.5%였다.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2001년도 춘계학술대회 논문집
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• pp.100-107
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• 2001

One major problem in the model testing is the boundary effect and size effect caused by the limit in the size of the container. To overcome this problem, various types of laminar boxes are gradually manufactured and used in the shaking table test, which ideally has zero stiffness to horizontal shear. In this study, a small-scale laminar box is manufactured, which is composed of 6 thin aluminum rectangular hollow plates, and its inside dimensions are 300 mm length by 200 mm width by 350 mm depth. Shaking table tests are performed both with the laminar box and the rigid box under the same conditions, where displacements and accelerations are measured at various points of the box and model ground. As result of analyzing the measured data, during the propagation of input seismic motion from the bottom to the ground surface, the relative displacement of the model ground and the amplification of acceleration is hardly amplified in the rigid box. Because of the effect of stress waves reflecting from the rigid wall, the acceleration is slightly decreased at the edge in the rigid box. The laminar box, manufactured in this study, has a problem in that the soil behavior at the edge of ground surface is affected by the inertia force of the top layer due to its excessive self-weight.

• 대한조선학회논문집
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• 제47권2호
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• pp.242-247
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• 2010

To consider effects of essential parameters of water impact pressure on dynamic structural responses of bow bottom structures, a parametric study for a ship bottom panel is carried out. The idealized pressure time history models were assumed by triangular and rectangular shapes in time domain. The main loading parameters are duration time and peak pressure value maintaining the same impulse value. The structural models for local bottom stiffened panels of a container ship are analysed. The natural frequency analysis and transient dynamic response analysis are performed using MSC/NASTRAN. Added mass effects of contacting water are considered and the pressure distributions are assumed to be uniform in the whole water contacting surface. The effects of loading parameters on the structural responses, especially maximum displacements, are considered. Besides the peak pressure value, effects of duration time correlated with natural frequencies are thought to be the important parameters.

• 한국자기학회지
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• 제23권1호
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• pp.31-35
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• 2013

본 연구에서는 나노입자 크기를 가지는 강자성체 미립자로 구성된 자성유체의 거동을 예측할 수 있는 수학적 모델링을 유한요소법(Finite element method)을 이용하여 수치적으로 접근하였다. 이를 위하여 뉴턴유체의 거동을 예측하는 지배방정식과 함께 자기력에 반응하는 강자성체의 거동을 예측하기 위한 Maxwell 자장 방정식 및 자성입자의 회전효과를 풀 수 있는 자화의 구성방정식을 추가로 고려하였다. 더불어 유한요소법을 이용하여 각 방정식을 이산화하고 속도와 온도의 경계조건을 이용하여 자성유체의 거동을 예측하였다. 본 모델링의 적합성을 검증하기 위하여 Davis(1983) 및 Fusegi et al.(1991)의 연구결과와 비교하였고, 각각 5.5 % 및 2.7 % 범위에서 비교적 정확하게 예측되었다.

• 한국수산과학회지
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• 제47권5호
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• pp.474-481
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• 2014

This study examined the effect of pretreated sandfish Arctoscopus japonicus meat as a surimi complex for preparing sandfish flavored fish paste. To prepare the sandfish-flavored paste, fine chopped sandfish meat including backbone was added in a ratio of 0 to 50 wt.% to thawed Alaska pollock Theragra chalcogramma surimi to make a mixed surimi gel. To prepare the sandfish-flavored paste, the mixed surimi was ground with salt using a silent cutter, mixed with starch and stabilizers 0.2% transglutaminase and gluconolactone 0.3%, stuffed in a rectangular container, left for 3 h at $25^{\circ}C$, cooked in hot water for 30 min at $90^{\circ}C$, and finally chilled for 20 min at $4^{\circ}C$. The effects of the pretreatment of sandfish meat were investigated by analyzing the quality of the paste produced. The proximate composition of FP (fish paste containing 40% steam-cooked sandfish meat and 0.3% gluconolactone) was moisture 76.1%, crude protein 12.0%, crude fat 3.8%, carbohydrate 6.1%, and ash 2.0%. The major minerals in FP were Na (23.77 mg/L), Mg (1.46 mg/L), Zn (1.04 mg/L), and Fe (0.41 mg/L), and the major free amino acids were taurine, anserine, alanine, and glutamic acid. The monounsaturated fatty acid content of FP was 566.22 mg%, and the polyunsaturated fatty acid content was 498.43 mg%. The n-3 fatty acid content was 398.01 mg%, and C20:5n-3 (218.85 mg %) was a major component.