• 한국수산과학회지
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• 제42권1호
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• pp.78-82
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• 2009

We describe a catch experiment and the size selectivity of gill nets for male Japanese sandfish (Arctoscopus japonicus) caught near Gosung, Korea. The experiment, which was conducted between October and December 2007, examined six different mesh sizes: 36.4, 39.4, 45.5, 51.5, 53.0, and 57.6 mm. The catch was mostly Japanese sandfish (91.3%) and some others (8.7%). More male Japanese sandfish were caught with smaller mesh sizes and more females with larger mesh sizes. Relationships between the weight and fork length of the male and female Japanese sandfish were obtained. The relationship between the catch (Y) and mesh size of the gill net (X) was $Y=0.1773X^3-5.3753X^2+40.042X+26.846$ ($R^2=0.99$). The selection curve for male Japanese sandfish caught in the experiment was fit, via Kitahara's method, to a polynomial equation, which was $s(R={\exp}\{(-2.1391\;R^3+24.294\;R^2-88.289\;R+105.5)-5.180\}$, where R=l/m, and l and m are the fork length and mesh size, respectively.

• 한국전산구조공학회논문집
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• 제24권4호
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• pp.365-373
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• 2011

병렬과 영역분할을 이용한 폭발하중을 받는 철근콘크리트패널의 손상을 분석하였다. 폭풍파는 극도로 짧은시간 동안에 발생되기 때문에 수치해석을 통한 결과값은 폭풍파의 메쉬크기에 영향을 받는다. 그러므로 폭풍파 메쉬크기의 영향을 분석하기 위해 explicit 유한요소해석 프로그램인 AUTODYN을 이용하여 기존 실험결과와 메쉬크기에 따른 해석결과가 비교되었다. 폭발해석결과 메쉬크기가 작을수록 정확도가 높았으나 수행시간이 증가하여 효율성이 떨어졌다. 추가로 수치해석의 효율성을 높이기 위해 영역별 Euler와 Lagrange 기법을 달리하는 병렬해석이 수행되었다. 결과로, 폭풍파영역에서는 영역분할된 Euler 메쉬를 사용하고 구조물영역에서는 영역 분할된 Lagrange 메쉬를 사용하는 것이 구조물영역에서 영역 분할된 Lagrange 메쉬만을 사용한 것보다 수치효율성이 가장 높았다.

• International Journal of Aeronautical and Space Sciences
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• 제12권2호
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• pp.149-155
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• 2011

The viscous flow in an axisymmetric nozzle was analyzed while accounting for the mesh sizes in both in the free stream and the boundary layer. The Navier-Stokes equations were resolved using the finite volume method in order to determine the supersonic flow parameters at the exit of the converging-diverging nozzle. The numerical technique in the aforementioned method uses the flux vector splitting of Van Leer. An adequate time stepping parameter, along with the Courant, Friedrich, Lewis coefficient and mesh size level, was selected to ensure numerical convergence. The boundary layer thickness significantly affected the viscous flow parameters at the exit of the nozzle. The best solution was obtained using a very fine grid, especially near the wall at which a strong variation of velocity, temperature and shear stress was observed. This study confirmed that the boundary layer thickness can be obtained only if the size of the mesh is lower than a certain value. The nozzles are used at the exit of the shock tube in order to obtain supersonic flows for various tests. They also used in propulsion to obtain the thrust necessary to the displacement of the vehicles.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 세계 도시지반공학 심포지엄
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• pp.1441-1446
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• 2009

Numerical analysis is a powerful method in evaluating the soil-pile-structure interaction under the dynamic loading, and this approach has been applied to the practical area due to the development of computer technology. Finite Difference Method, one of the most popular numerical methods, is sensitive to the shape and the number of mesh. However, the trial and error approach is conducted to obtain the accurate results and the reasonable simulation time because of the lack of researches about mesh size and the number. In this study, FLAC 3D v3.1 program(FDM) is used to simulate the dynamic pile model tests, and the numerical results are compared with the 1G shaking table tests results. With the different size and shape of mesh, the responses of pile behavior and the simulation time are estimated, and the optimum mesh sizes in dynamic analysis of single pile is studied.

• 수산해양기술연구
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• 제50권3호
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• pp.284-291
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• 2014

Finely-striate buccinum Buccinum striatissimum, a species of whelks, is caught mainly by pot in the eastern coastal waters of Korea. In order to determine the size selectivity of pot for the species, comparative fishing experiments were conducted near Yeongil Bay from June to September in 2003 using the dome-shaped pots with different five mesh sizes (17.1, 24.8, 35.3, 39.8, and 48.3 mm). The parameters of logistic equation were estimated by the SELECT (Share Each Length's Catch Total) method based on a multinomial distribution. The model with the estimated split parameter was found to fit the catch data best. The master selection curve was estimated to be s (R)=exp (13.044R-16.438)/[1 + exp (13.044R-16.438)], where R is the ratio of shell height to mesh size. The relative shell height of 50% retention was 1.260, and the selection range was 0.168. Enlargement in mesh size of the pot allows more small-sized whelks to escape.

• 소성∙가공
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• 제31권4호
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• pp.200-206
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• 2022

The finite element analysis is one of the representative methods for predicting the materials behavior for experiments that are difficult to perform empirically. Constitutive equations are essential for reducing computation time and sharing data because they enable finite element analysis simulations through simple formulae. However, it is difficult to derive accurate flow curves for all materials as most constitutive equations are not formulated based on their physical meaning. Also, even if the constitutive equation is a good representation of the flow curve to the experimental results, some fundamental issues remain unresolved, such as the effect of mesh size on the calculation results. In this study, a new constitutive equation was proposed to predict various materials by modifying the combined Swift-Voce model, and the calculation results with various mesh sizes were compared to better simulate the experimental results.

• 한국식품과학회지
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• 제20권4호
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• pp.463-469
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• 1988

쌀가루의 압출성형 특성을 조사하기 위하여 원료의 수분합량과 입자크기를 달리하여 자가발열형 single screw extruder로 처리하고 이때 온도변화에 따른 extrudate의 물성학적인 성질을 비교하였다. 원료의 수분함량은 17%, 19%, 22%, 25%, 28%로 했고 입자크기는 18-60mesh와 60-120mesh의 두 범위로 했다. 내부흐름의 온도는 자동 온도기록계에 기록되게 하여 정상상태 가동이 될 때까지 경시적으로 시료를 채취하였다. 팽화율은 수분함량과 입자크기가 감소함에 따라 증가하였으며, bulk density는 팽화율과 역상관 관계를 나타내었다. Extrudate의 절단력은 수분함량이 적고 입자조기가 감소함에 따라 낮아졌으며 기공의 크기도 균일하였다. 색도는 수분함량과 입자크기가 증가함에 따라 명도는 증가하였고 황색도는 감소하였다. 겉보기 점도는 수분함량이 증가함에 따라 증가했고, 수용성 지수는 감소하였다. 원료의 수분이 감소함에 따라 일부의 전분은 호정화를 유발하는 것으로 판단되었다.

• 자원리싸이클링
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• 제7권5호
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• pp.13-18
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• 1998

전기로 제강분진의 물성을 파악하기 위하여 분진의 성분, 형상, 입도, 자성, 비중, 공극율 및 용출에 관한 성질을 조사하였다. 분진의 대부분은 서브 마이크론에서 수십 마이크론에 이르는 다양한 크기의 구형입자들이 서로 응집된 상태이고, 큰 입자에는 철분이 그리고 작은 입자에는 아연이 주로 농집되며, XRD 분석으로는 franklinite(${ZnFe}_{2}{O}_{4}$), magnetite(${Fe}_{3}{O}_{4}$), zincite(ZnO) 등의 결정이 확인된다. 분진을 습식으로 체가름하였을 때에 +200 mesh의 입단은 1.5% 정도이고 magnetite와 quartz의 결정을 함유하며, 200∼500 mesh는 magnetite, franklinite, zincite가 혼재되고, 분진의 약 82%를 차지하는 -500 mesh에는 franklinite와 zincite의 결정이 혼재한다. 공극율이 78% 정도인 분진을 약 1㎪로 압착하면 공극율은 68% 정도가 되고, 약 13㎪로 압착하면 53% 정도로 된다. 제강분진을 폐기물 처리공정 시험방법에 따라 용출시켰을 때에 허용기준치를 초과한 중금속은 카드뮴, 납, 수은이었다.

• 수산해양기술연구
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• 제41권2호
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• pp.95-100
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• 2005

In order to improve the gill nets for croaker, Miichthys miiuy which is proper to the fishermen's income ans fisheries resource management, we had studied to the net height of present gill nets (mesh size 160mm, 50 mesh in depth), experimental gill nets-I(mesh size 150mm, 68 mesh in depth) and experimental gill nets-II(mesh size 142mm, 75 mesh in depth) in wter using the gill nets design ans analysis simulation system, and then investigated and analyzed the catch efficiency of each gill nets through the field fishing experiments. The net height of emperimental gill nets-I and experimental gill nets-II in water were estimated respectively about 1.5 times and 1.3 times higher than present gill nets which the net height is about 3.5m as the results of simulation considering the current of fishing fields. Total number of croakers which were caught by the persent gill nets was 62(body length 300~1,200mm), total catch weight was 398.7kg (mean 0.6kg/sheet). Total number of croakers which were caught by the experimental gill nets- I was 68(body length 600~1,100mm), total catch weight was 391.6kg (mean 1.2kg/sheet). Total number of croakers which were caught by the experimental gill nets-II was 28(body length 400~900mm), total catch weight was 99.2kg (mean 0.3kg/sheet).

• 한국정보과학회논문지:시스템및이론
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• 제36권5호
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• pp.335-343
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• 2009

교차큐브는 병렬처리 시스템의 상호연결망으로서 널리 알려진 하이퍼큐브와 많은 면에서 비슷하면서도 절반 정도의 지름을 가지는 등 개선된 망 성질들을 가지므로 각광 받아 왔다. 크기 $4{\times}2^m$인 메쉬의 복사본 두 개, 혹은 크기 $8{\times}2^m$인 메쉬의 복사본 네 개가 교차큐브에 연장율 1, 확장율 1로 임베딩 될 수 있음이 알려져 있다.[Dong, Yang, Zhao, and Tang, 2008]. 그러나 양변의 길이가 모두 8 보다 큰 메쉬 다수 개가 교차큐브에 연장율 1, 확장율 1로 임베딩될 수 있는지는 알려진 바가 없다. 이 논문에서는 크기 $2^n{\times}2^m$인 메쉬의 복사본 $2^{n-1}$개가 교차큐브에 연장율 1, 확장율 1로 임베딩될 수 있음을 보인다. $n{\geq}1$, $m{\geq}3$. 이 연구 결과는 연장율과 확장율이라는 주요 임베딩 측정 척도에서 최적이다. 또한 이 연구 결과는 메쉬 구조를 가지는 다수 개의 작업을 교차큐브 구조를 가지는 병렬 컴퓨터에 할당하는데 효과적으로 활용될 수 있다.