• 한국해양공학회지
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• 제12권2호통권28호
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• pp.79-86
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• 1998

A three-dimensional WIG (Wing In Ground effect) moving above free surface is numerically studied by means of finite difference techniques. The air flow field around the WIG is analyzed by MAC (Marker & Cell) method, and interactions between WIG and the free surface are appeared as the variation of pressure distribution acting on the free surface. To analyze the wavemaking phenomena by those pressure distributions, the NS (Navier-Stokes) solver is employed in which nonlinearities of the free surface conditions can be included. Through the numerical simulation, Cp values and lift/drag ratio are carefully reviewed by changing the height/chord ratio. The section shape of model is NACA0012 with the span/chord ratio of 3.0. Through computational results, it is confirmed that the effect of free surface is small enough to treat it as a rigid wavy wall.

• Journal of Ship and Ocean Technology
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• 제5권4호
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• pp.29-43
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• 2001

In this paper, free surface flows around an advancing two-dimensional rectangular cylinder piercing the free surface are studied using numerical and experimental methods. Especially, wave breaking phenomenon around the cylinder is treated in detail. A series of numerical simulations and experiments were performed for the purpose of comparison. For the numerical simulations, a finite difference method was adopted with a rectangular grid system, and the variation of the free surface was computed by the marker density method. The computational results are compared with the experiments. It is confirmed that the present numerical method is useful for the numerical simulation of nonlinear free surface waves around a piercing body.

• 한국식물생명공학회:학술대회논문집
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• 한국식물생명공학회 2004년도 생명공학 실용화를 위한 비젼
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• pp.109-109
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• 2004

• 생명과학회지
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• 제26권10호
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• pp.1121-1129
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• 2016

밀의 고분자 글루테닌 서브유닛[high molecular-weight glutenin subunit (HMW-GS)]은 밀가루의 성질을 결정하는데 가장 중요한 요소이며 가공적성을 나타내는데 중요한 역할을 수행한다. 우리는 Agrobacterium 동시 형질전환법을 이용하여 한국 밀 품종인 ‘조경’으로부터 밀 HMW-GS을 암호화하는 TaGlu-Ax1 유전자를 가지는 marker-free 형질전환 벼를 생산하였다. TaGlu-Ax1 유전자의 종자 특이적 발현을 위하여 밀에서 존재하는 TaGlu-Bx7 유전자의 자체 프로모터를 벡터 내에 삽입하였다. 동시 접종을 위해서 오직 TaGlu-Ax1 유전자와 hygromycin phosphotransferase II (HPTII) 저항성 유전자만으로 구성된 두 종류의 발현 카세트를 독립적으로 Agrobacterium EHA105에 도입하였고, TaGlu-Ax1와 HPTII가 도입된 각각의 EHA105 Agrobacterium을 3:1 비율로 혼합하여 벼 캘러스에 접종하였다. 210개의 HPTII 저항성 형질전환체 중에서 벼 게놈에 TaGlu-Ax1과 HPTII가 모두 삽입된 20개의 형질전환 라인을 획득하였다. TaGlu-Ax1와 HPTII가 벼 게놈에 도입된 것을 Southern blot을 통해서 다시 확인하였다. 형질전환 벼 T₁ 세대의 종자에서 밀 TaGlu-Ax1 유전자가 전사와 번역되어 오직 TaGlu-Ax1만을 가지는 marker-free 식물체를 T₁세대에서 성공적으로 선발할 수 있었다. TaGlu-Ax1 유전자가 발현되는 marker-free 형질전환 식물체는 야생형(wild type)과의 표현형 차이는 없었다. 형질전환 벼의 쌀가루의 제빵적성을 비교하였을 때 TaGlu-Ax1 유전자만이 발현되어서는 제빵적성이 더 나아지지 않았다. 그러므로 더 많은 밀 고분자 및 저분자 글루테닌, 글리아딘의 유전자의 집적과 조합이 쌀가루 가공적성을 증진시키는데 필요하다. 결론적으로 TaGlu-Ax1 marker-free 형질전환 벼는 쌀가루 가공적성을 증진시키는데 좋은 재료로 사용될 것이다.

• 대한조선학회논문집
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• 제54권1호
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• pp.26-33
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• 2017

In this study, the surface marker method, one of the particle tracking methods, used to track the free surface is extended to cover the more general cases easily including the collision and separation of the free surface. In surface particle method to redistribute particles effectively using the grid system, the free surface is composed of the sum of quadrilaterals having four curves where fixed markers are placed at ends of each curve. Fixed markers are used to know how curves are connected to each other. The position of fixed markers can move as the free surface deforms but all fixed markers cannot be deleted during all time of simulation to keep informations of curve connection. In the case of the collision or separtion of the free surface where several curves can be intersected disorderly, severe difficulties can occur to define newly states of curve connection. In this study, the adaptable surface parTicle method without fixed markers is introduced. Intersection markers instead of the fixed markers are used to define quadrilaterals. The position of the intersection markers is defined to be the intersection point between the free surface and the edge of the grid and it can be added or deleted during the time of simulation to allow more flexibilities. To verify numerical schemes, two flow cases are simulated and the numerical results are compared with other's one and shown to be valid.

• 한국전산유체공학회지
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• 제11권4호
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• pp.90-100
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• 2006

A digital wave tank (DWT) simulation technique has been developed by authors to investigate the interactions of fully nonlinear waves with 3D marine structures. A finite-difference/volume method and a modified marker-and-cell (MAC) algorithm have been used, which are based on the Navier-Stokes (NS) and continuity equations. The fully nonlinear kinematic free-surface condition is implemented by the marker-density function (MDF) technique or the Level-Set (LS) technique developed for one or two fluid layers. In this paper, some applications for various engineering problems with free-surface are introduced and discussed. It includes numerical simulation of marine environments by simulation equipments, fully nonlinear wave motions around offshore structures, nonlinear ship waves, ship motions in waves and marine flow simulation with free-surface. From the presented simulations, it seems that the developed DWT simulation technique can handle various engineering problems with free-surface and reliably predict hydrodynamic features due to the fully-nonlinear wave motions interacting with such marine structures.

• Journal of Ship and Ocean Technology
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• 제12권1호
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• pp.16-27
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• 2008

The interaction between advancing ships and the waves generated by them plays important roles in wave resistances and ship motions. Wave breaking phenomena near the ship bow at different speeds are investigated both numerically and experimentally. Numerical simulations of free surface profiles near the fore bodies of ships are performed and visualized to grasp the general trend or the mechanism of wave breaking phenomena from moderate waves rather than concentrating on local chaotic irregularities as ship speeds increase. Navier-Stokes equations are differentiated based on the finite difference method. The Marker and Cell (MAC) Method and Marker-Density Method are employed, and they are compared for the description of free surface conditions associated with the governing equations. Extra effort has been directed toward the realization of extremely complex free surface conditions at wave breaking. For this purpose, the air-water interface is treated with marker density, which is used for two layer flows of fluids with different properties. Adaptation schemes and refinement of the numerical grid system are also used at local complex flows to improve the accuracy of the solutions. In addition to numerical simulations, various model tests are performed in a ship model towing tank. The results are compared with numerical calculations for verification and for realizing better, more efficient research performance. It is expected that the present research results regarding wave breaking and the geometry of the fore body of ship will facilitate better hull form design productivity at the preliminary ship design stage, especially in the case of small and fast ship design. Also, the obtained knowledge on the impact due to the interaction of breaking waves and an advancing hull surface is expected to be applicable to investigation of the ship bow slamming problem as a specific application.

• 대한전자공학회논문지SP
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• 제38권3호
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• pp.1-1
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• 2001

본 논문에서는 복잡 배경으로부터 임의의 다중물체를 효과적으로 검출함과 동시에 고속 분할할 수 있는 문맥자유 마커제어 분수계 변환 (context-free marker controlled watershed transform)을 제안하였다. 먼저 잡음에 강건한 주목 연산자 (attention operator)를 써서 복잡 배경 속의 여러 물체 별로 그 위치를 검출하여 문맥자유 마커를 추출하고, 이를 마커로 한정된 레이블링 (marker constrained labeling)을 하여 최소값 부과과정이 필요 없는 문맥자유 마커제어 분수계 변환을 제안함으로써 과분할없이 신속하게 분할할 수 있도록 하였다. 다중 물체가 포함된 복잡 영상에 적용 실험하여, 대상 물체에 대한 사전정보 없이도 과분할과 처리시간을 대폭 줄여 효과적으로 다중 물체를 검출함과 동시에 고속 분할이 가능함을 확인 할 수 있었다.

• Journal of Microbiology and Biotechnology
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• 제29권9호
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• pp.1488-1493
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• 2019

The rising cases of multidrug-resistant Acinetobacter baumannii (Ab) and the lack of effective drugs call for quick attention. Here, based on a Tn7 transposon and Xer/dif system, we constructed a stable, selectable marker-free autoluminescent Ab capable of producing visible light without extra substrates. Utilization of this autoluminescent reporter strain has the potential to reduce the time, effort and costs required for the evaluation of activities of anti-Ab drug candidates in vitro.

• 한국전산유체공학회지
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• 제4권1호
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• pp.19-26
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• 1999

This paper describes a numerical method for predicting the incompressible unsteady laminar three-dimensional flows with free-surface. The Navier-Stokes equations governing the flows have been discretized by means of finite-difference approximations, and the resulting equations have been solved via the SIMPLE-C algorithm. The free-surface is defined by the motion of a set of marker particles and the interface behaviour was investigated by means of a "Lagrangian" technique. Using the GALA concept of Spalding, the conventional mass continuity equation is modified to form a volumetric or bulk-continuity equation. The use of this bulk-continuity relation allows the hydrodynamic variables to be computed over the entire flow domain including both liquid and gas regions. Thus, the free-surface boundary conditions are imposed implicitly and the problem formulation is greatly simplified. The numerical procedure is validated by comparing the predicted results of a periodic standing waves problems with analytic solutions. The results show that this numerical method produces accurate and physically realistic predictions of three-dimensional free-surface flows.