• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.5
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• pp.523-529
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• 2010

Recently, several research groups have been investigating the motion of flagellated bacteria, with the aim of examining the feasibility of using bacterial chemotaxis as an efficient power source for microactuators. In this study, microparticle-tracking velocimetry ($\mu$-PTV) is used for investigating the motion of fluorescent microbeads propelled by bacterial chemotaxis. Flagellated bacteria, Serratia marcescens, are spontaneously attached to the surface of the fluorescent polystyrene (PS) microbeads in an aqueous culture. The microbeads thus treated are injected into the test medium, which contains the solidified chemoattractant L-aspartate. With time, the particles slowly move toward the zone in which the L-aspartate concentration is high. This study shows that chemotaxis of flagellated bacteria can be applied as an efficient power source for microactuators.

• Journal of the Korean Chemical Society
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• v.43 no.4
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• pp.469-474
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• 1999

In this study, the simulation program using the randomwalk model is developed. Generally, students in the chemistry class have some difficulties to understand the motion of atomic particles or molecules. And then, they have many mis-conceptions about the motion of molecules. This program expressed by the computer simulations using the randomwalk theory may help students to understand visually the process of molecular motion. This program can be used easily, because it is based on Web by application of JAVA languages. The program consists of two parts. One is 'Diffusion' program, expressing the process of molecular diffusion as a computer simulation. Another is 'Randomwalk' program, expressing the trajectory of molecular motion to help the students to follow the random motion virtually.

• Journal of the Korea Computer Industry Society
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• v.10 no.5
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• pp.221-226
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• 2009

The closed system's internal rigid body particle rotation motion can be distinguished by a main body that becomes the core of the rotation and the particles that are subjected to the rotation. The instance of particles becoming bounded to the main body as a holonomic system, has till now, been well defined and formulated in the study of Kinetics, and the structure of the formulas relate well to reality. However, when the structure is non-holonomic it deviates from these existing equations. The purpose of this research is to categorize the differences between a holonomic system and a non-holonomic system when rotating, through devices. With a special emphasis on the real phenomenon of the non-holonomic system which will be formulated in the form of a model or computer simulation. With these formulas, the center of mass shift in a closed rotating motion system and confined motion of external friction will be adequately expressed, so that it may be applied to computer graphics motions methods.

• Journal of The Geomorphological Association of Korea
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• v.17 no.1
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• pp.49-57
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• 2010

To evaluate physical characteristics of open rainfall in Korea, terminal velocity of raindrop and drop size distributions (DSD) were continuously measured using by laser-optical disdrometer around Gosam reservoir, Anseong-si, Gyeonggi-do during three rainfall events from 2008 to 2009. The relationships between kinetic energies (KE, Jm^-2mm^-1; KER, Jm^-2h^-1) and rainfall intensity were obtained, respectively. Moreover, we compared the rainfall intensity from a disdrometer with the rainfall intensity from a tipping bucket raingauge to transform the kinetic energy of rainfall using the data from a tipping bucket raingauge. Therefore, the established relationships between kinetic energies (KE and KER) and rainfall intensity could be a useful model to consider the kinetic energy of raindrop using the rainfall intensity below 40mmh^-1 of max 5-min rainfall intensity in the middle of South Korea. However, to better examine the relationship between kinetic energy and rainfall intensity, further measurement will be required.

• Proceedings of the Optical Society of Korea Conference
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• 2002.07a
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• pp.108-109
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• 2002

Optical tweezers는 광압(radiation pressure)을 사용하여 입자들을 포획하거나 조절할 수 있다는 점에서 마이크로스케일의 유전체구뿐만 아니라 세포에서도 널리 사용되고 있다. 일반적으로 빛이라는 것은 광자들의 집합체로서 광자의 입자성으로 인하여 외부의 물체와 충돌시 운동량을 전달하게 되고 이것을 광압(radiation pressure)이라고 하며 optical tweezers [1]는 이 광압을 이용한 방법중 하나이다. 레이저빔을 입자에 집속 시켜 주게 되면 입자는 광압에 의해서 gradient force와 scattering force의 힘을 받게 된다. (중략)

• Proceedings of the KAIS Fall Conference
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• 2008.11a
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• pp.167-169
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• 2008

본 논문에서는 대전입자형 디스플레이에 인가된 펄스에 따라 운동하는 대전입자(토너)를 광학적인 관측과 전기적인 측면에서 관찰하였으며, 증폭되는 펄스에 따라 변화하는 대전입자의 응답속도를 측정하여 대전입자의 구동특성을 분석하였다.

• Proceedings of the Membrane Society of Korea Conference
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• 1998.04a
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• pp.56-58
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• 1998

1. 서론 : 무한한(unbounded) 용매 속에 떠 있는 구형입자의 확산계수는 Stokes-Einstein 식에 의해 주어지며, 이를 이용하여 입자의 반지름을 결정하기도 한다. 입자가 그 크기정도(order-of-magnitude)의 공간에 제한되는 경우에는 제한하는 벽이 입자의 운동에 많은 영향을 주게 된다. 이런 제한적 이동(hidered transport)은 막이나 크로마토그래피를 이용하는 분리공정이나 촉매를 이용하는 반응공정에서 이용되고 있다. (생략)

• Proceedings of the Korean Society of Computer Information Conference
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• 2019.01a
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• pp.315-318
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• 2019

본 논문은 화학에서 사용되는 2가지 산, 염기 모델에 대한 이해를 높이고자 각 모델의 핵심 알고리즘가 반영된 단계별 교육용 콘텐츠를 개발하는데 목적이 있다. 이를 위해 먼저 Arrhenius와 Brønsted-Lowry 모델이 갖는 핵심 알고리즘을 탐색하였으며, 이러한 핵심 알고리즘을 반영된 단계별 교육용 콘텐츠를 JAVA를 이용하여 개발하였다. 개발된 교육용 콘텐츠는 총 5단계로 구성되어 있다. 1단계는 화학에서 다루어지는 입자들이 개별적으로 무작위하게 운동함으로 표현하였으며, 2단계는 화학반응이란 이러한 무작위적 운동 중 입자 간 충돌에 의해 반응이 개시됨을 보여주었다. 3단계에서는 단일입자에 대해 정반응과 역반응을 동시에 고려한 진행되는 상황을, 4단계는 여러 입자가 동시다발적으로 정반응과 역반응에 참여한 상황을 구현하였다. 마지막 5단계는 정반응과 역반응의 공존의 비율이 다른 상황을 통해 평형상수의 의미를 고찰하도록 하였다. 창발적 사고의 핵심은 여러 입자를 생각하는 확률적 사고와 이러한 여러 입자가 개별적으로 움직인다는 사고가 반영되어야 한다. 이 연구에서 개발한 교육콘텐츠를 활용한다면 학생들이 보다 창발적 사고를 하는데 도움을 줄 것으로 기대된다.

• Journal of the Korea Concrete Institute
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• v.20 no.3
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• pp.317-323
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• 2008

In the current study, A model for the flow analysis of fresh and highly flowable concrete has been developed using a particle method, the moving particle semi-implicit (MPS) method. The phenomena on the flow of concrete has been considered as a visco-plastic flow problem, and the basic governing equation of concrete particle dynamics has been based on the Navier-Stokes equation in Lagrangian form and the conservation of mass. In order to formulate a visco-plastic flow constitutive law of fresh concrete, concrete is modeled as a highly viscous material in the state of non-flow and as a visco-plastic material in the state of flow after reaching the yield stress of fresh concrete. A flow test of fresh concrete in the L-box was simulated and the predicted flow was well matched with the experimental result. The developed method was well showed the flow motion of concrete particles because it was formulated to be based on the motion of visco-plastic fluid dynamics.

• 전기의세계
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• v.19 no.6
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• pp.39-44
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• 1970

본고에서는 plasma전체의 거동에 대해서는 plasma를 전자기체 및 (+)이온기체로서 이루어지는 유체로서 취급을 하면 잘 부합되며 설명되는 경우가 많기 때문에 이 절에서는 plasma를 유체로서 취급하여 기술하기로 한다. 우선 plasma는 열운동을 하고 있는 하전입자의 집단이기때문에 그 거동은 기체운동론에서 사용되는 Baltamann방정식을 기초로 두어서 논하게 된다.