• Korea-Australia Rheology Journal
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• 제11권3호
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• pp.247-253
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• 1999

The growth of a spherical vapor bubble contained in a large body of upper convected Maxwell fluid is theoretically analyzed under the devolatilization condition of polymer by using a Galerkin FEM in the Lagrangian frame. Using the finite element technique, a fully explicit numerical scheme is developed both for the calculation of pressure distribution and for the tracking of bubble surface. Oscillatory behavior in bubble radius is observed during growth and the oscillatory behavior is found to be due to the interaction of mass transfer resistance and elasticity. It is found that the elasticity of fluid accelerates the growth and removal of volatile component. It is also found that the bubble growth in the devolatilization of polymers is affected by both mass transfer resistance and viscoelasticity of fluids.

• 한국전산유체공학회지
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• 제12권3호
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• pp.41-46
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• 2007

Dynamic behavior of immiscible gas bubble attached to the wall in channel flow plays very important role in many engineering applications. Special attention has been paid to micro direct methanol fuel cell(${\mu}$DMFC) where surface tension becomes dominant factor with minor gravitational effect due to its reduced size. Therefore, displacement of $CO_2$ bubble generating on a cathode side in ${\mu}$DMFC can be very difficult and efficient removal of $CO_2$ bubbles will affect the overall machine performance considerably. We have focused our efforts on studying the dynamic behavior of immiscible bubble attached to the one side of the wall on 2D rectangular channel subject to external shear flow. We used Level Contour Reconstruction Method(LCRM) which is the simplified version of front tracking method to track the bubble interface motion. Effects of Reynolds number, Weber number, advancing/receding contact angle and property ratio on bubble detachment characteristic has been numerically identified.

• 한국실내디자인학회:학술대회논문집
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• 한국실내디자인학회 2004년도 춘계학술발표대회 논문집
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• pp.131-135
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• 2004

The purpose of this research is to improve exhibition effectiveness by implementing hands-on exhibition technique that best provides adults with cultural resting place and children with outdoor education which simply supports school curriculum. By completing this research, the museum of natural history will become defined innovatively as a place that enables people actively develop creativity. Seodaemun museum of natural history was selected for this research and itinerary tracking method of Robinson and Melton was adopted to find out adults' and children's particular movements in the museum. At the same time, observation method was used to get information on each room's visiting and viewing rate. In order to understand adults' and children's movements, their behavior was encoded.

• 로봇학회논문지
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• 제2권4호
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• pp.310-316
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• 2007

The paper proposes a human-following behavior of mobile robot and an intelligent space (ISpace) is used in order to achieve these goals. An ISpace is a 3-D environment in which many sensors and intelligent devices are distributed. Mobile robots exist in this space as physical agents providing humans with services. A mobile robot is controlled to track a walking human using distributed intelligent sensors as stably and precisely as possible. The moving objects is assumed to be a point-object and projected onto an image plane to form a geometrical constraint equation that provides position data of the object based on the kinematics of the intelligent space. Uncertainties in the position estimation caused by the point-object assumption are compensated using the Kalman filter. To generate the shortest time trajectory to track the walking human, the linear and angular velocities are estimated and utilized. The computer simulation and experimental results of estimating and trackinging of the walking human with the mobile robot are presented.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2010년 춘계학술대회논문집
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• pp.376-379
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• 2010

Bubble rising phenomenon is widely founded in many industrial applications such as a stream generator in power plant. Many experimental and numerical researches have been already performed to predict dynamic behavior of the bubble rising process. Recently numerical approaches are getting popular since it can offer much detailed information which is almost impossible to obtain from the experiments. Rising bubble could penetrate through the top free surface which makes the problem much more complicate in addition to the phase changing effect even with latest numerical techniques. In this paper, the top free surface effect on rising bubble has been investigated. The gas-liquid interface was explicitly tracked using high-order Level Contour Reconstruction Method(LCRM) which is a hybridization of Front-Tracking and Level-Set method. Break-up behavior of rising bubble at free surface showed different characteristics with initial diameter of bubble.

• 한국수산과학회지
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• 제50권2호
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• pp.222-226
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• 2017

It is well known that typhoons strongly influence marine ecosystems. For example, red tides nearly disappear after the passage of typhoons, although the physical or biological mechanism underlying this has not been elucidated. Here, a particle tracking model is executed in a three-dimensional primitive equation model to understand the process of red tide extinction after the passage of a typhoon. Red tide organisms may be regarded as tracers because they have limited mobility and thus their behavior is governed entirely by currents. Initially, tracers are randomly scattered within a limited area, and their spatial and temporal behavior is tracked during and after the passage of a typhoon. This model suggests that the extinction of red tides is significantly influenced by momentum disturbances caused by the typhoon.

• 동력기계공학회지
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• 제18권3호
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• pp.5-13
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• 2014

In order to control emissions from engine, it is necessary to understand the mixture formation process of diesel spray. In this study, analysis of diesel fuel(n-Tridecane, $C_{13}H_{28}$) spray under a high temperature and pressure was performed by a general-purpose program, ANSYS CFX release 11.0, and the results of these are compared with experimental results of diesel fuel spray using the Exciplex Fluorescence Method. The simulation results of diesel spray is analyzed by using the combination of Large-Eddy Simulation(LES) and Lagrangian Particle Tracking(LPT), and then injection pressure was selected as an analysis parameter. Consequently, it was found that the experimental results and the numerical results are consistent with each other, and then in order to investigate the behavior characteristics of evaporative diesel spray, the effectiveness of the use of CFX of commercial code is definitely validated.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2002년도 학술발표회 논문집(II)
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• pp.1027-1033
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• 2002

The solute transport in a two-dimensional heterogeneous porous medium is numerically studied by using a random walk particle tracking (RWPT) method. Lognormally isotropic hydraulic conductivity fields are generated by using the turning band methods with mean zero and four different values of standard deviation. The numerical transport experiments are carried out to investigate the large time and spatial effects of the variable pore velocity field on solute plumes. The behavior of the solute plume through numerical simulations is presented in terms of longitudinal and transverse spatial moments: displacement of center-of-mass, plume spread variance and skewness coefficient. It was observed that the dispersive behavior of the solute plume is strongly affected by the degree of heterogeneity in the flow domain.

• 한국비블리아학회지
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• 제20권1호
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• pp.209-220
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• 2009

본 연구의 목적은 인지적 업무분석(CWA) 프레임워크를 활용하여 중학생들의 공공도서관에서의 정보행태를 조사하며, 도서관 공간에서의 행태 분석 연구에서 CWA의 효과를 파악하는데 있다. 연구방법으로 CWA 프레임워크를 적용한 심층면담과 관찰방법을 사용하였다. 연구 결과 학생들이 보고서 작성을 위해 도서관에서 자료를 찾을 때, 보고서에 적합한 자료, 도서관 자료의 한정성, 도서관의 개관시간, 자료의 이용 가능성 등이 정보행태에 영향을 미치는 것으로 나타났다. 이용 행동은 크게 3가지 타입으로 보여주고 있는데, 온라인목록을 이용하여 자료의 청구기호를 확인한 후, 서가에서 자료를 찾아 열람테이블에서 보고서를 작성하는 타입, 바로 서가에 가서 필요한 자료를 찾아 대출하는 타입, 도서관 직원에 의존하여 자료를 대출하는 타입으로 구분되었다. 또한 CWA는 도서관 공간에서 정보행태를 조사하는데 효과적이지만, 여러 가지 복합적인 조사가 누적되어야만 효과적으로 공간을 재구성하는데 적용할 수 있다고 본다.

• 한국문헌정보학회지
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• 제52권3호
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• pp.5-33
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• 2018

본 연구의 목적은 사용자의 정보 서비스 이용행태를 분석하여 검색하는 의도와 관심분야를 국가과학기술표준분류기반으로 파악하고 추적하며, 이를 이용해 과학기술정보를 개인화하는 것이다. 즉 과학기술정보 검색 성능을 개선하여 사용자가 원하는 정보를 탐색하는데 효율성과 만족도를 동시에 충족시키고자 하였다. 실시간 관심분야 추적, 관심태그 클라우드 제공, 관심분야 기반 추천정보 제공, 검색 결과 개인화 네 가지 기능으로 구성된 과학기술정보 개인화 서비스를 개발하여 전문가 실험집단과 통제집단과의 검색 성능 비교를 통해 개인화 정보의 적합성 및 개인화 기능 유용성을 평가하였다. 그 결과 본 연구에서 제안된 개인화 서비스가 비교 대상 서비스보다 검색 성능이 더 우수한 것으로 나타났으며 더 높은 유용성을 제공하는 것을 입증하였다.