• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.10 no.S_1
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• pp.29-33
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• 2001

A numerical simulation was carried out to investigate the mechanism of snowfall around the Seoul region during a cold air-outbreak in the winter season. A particular case was selected for this study(Dec. 19, 1999). The inflow directions of the synoptic flow in the upper and lower levels were westerly and north-westerly, respectively. Plus, there was a deep trough and thermal ridge at a level of 500/700/850 hPa over the Bal-Hae region, in the northern part of the Korean peninsula. According to the model results, snowfall occurred around the Seoul region with the simultaneous existence of a strong static instability in the lower atmosphere, northerly or westerly dry air advection, and strong thermal advection toward the Seoul region. There was a strong convergence thereby indicating the existence of convective rolls in the clouds. The main energy source of convection over the Yellow sea was a sensible heat flux. The main moisture source was convection. Radiative cooling in the cloud layer intensified the static instability in the lower atmosphere.

• 한국가스학회:학술대회논문집
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• 2005.10a
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• pp.83-87
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• 2005

The kinetics of the direct synthesis of DME was studied under different conditions over a temperature range of $220\~280^{\circ}C$, syngas ratio $1.2\~ 3.0$ All experiment were carried out over hybrid catalyst, composed to a methanol synthesis catalyst (Cu/ZnO/$Al_2O_3$) and a dehydration Catalyst ($\gamma$-Al_2O_3$) The observed reaction rate qualitatively follows a Langmiur-Hinshellwood type of reaction mechanism. Such a mechanism is considered with three reaction, methanol synthesis, methanol dehydration and water gas shift reaction. From a surface reaction with dissociative adsorption of hydrogen, methanol and water, individual reaction rate was determined

• 제어로봇시스템학회:학술대회논문집
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• 1989.10a
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• pp.166-171
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• 1989

In the view of the fact that mobile robot in nuclear facilities should be able to turn in narrow space, go over obstacles, and climb stairs for the inspection and maintenance, a robot, named as KAEROT, is developed. It adopts 2DWIS (2-Driving Wheels, 1-Steering) and has three planetary wheels that are composed of two star-like arms and three small wheels. The experiments were carried out in two locomotion methods; (1) by controlling the rear wheel speed as a function of steering angle, and (2) by using inclination and stair-detection sensor to control the position of planetary and small wheel. The developed robot moved on the floor with stability. Results from the experiment on the rectangular obstacle as well as the computer simulation showed a feasibility on the stairs.

• Journal of the Ergonomics Society of Korea
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• v.17 no.1
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• pp.103-114
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• 1998

This study was carried out on 132 obese women who satisfied both of the conditions for the obesity: over 1.6 in Rohrer index and over 90cm in bust girth. The purpose of the study was to classify the body types of the obese women and find out their respective characteristics. The characteristics of the body shape were as follows. The one was that the height of the front waist was higher than that of the back waist. The other was that the depth of the front abdomen was high, which implies the protruding of the abdominal region. Five factors were extracted as the result of the factor analysis. Body types were classified 4 types(type 1 : long upper torso, type 2 : obese torso, type 3 : short and less upper torso, type 4 : obese arms and legs) according to the cluster analysis.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.63.3-64
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• 2017

KIC6118779 is an over-contact binary system having a short orbital period of about 0.36 days. The photometric data for this system are acquired by the observations of Kepler mission in the long cadence mode having a time resolution of about 30 minutes. It means that the Kepler light curves of the system may be strongly affected by phase smearing effect and the analysis of them without consideration of the phase smearing effect may result in wrong stellar properties. Additionally, this system also shows dynamical variation of light curve resulting from spot activity. For all those reasons, it is difficult to investigate KIC6118779, and the investigation should be carried out carefully. In this presentation, we introduce the phase smearing effect and carry out the light curve modeling with the 2015 version of the Wilson-Devinney binary code considering the phase smearing effect. Our results show that the system is a deep over contact binary system and has extremely low mass ratio of about 0.12. Moreover our spot modeling implies the cyclic migration of a big cool spot on the massive component.

• 한국전산유체공학회:학술대회논문집
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• 2007.10a
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• pp.100-110
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• 2007

A new design approach for a delicate treatment of complex geometries such as a wing/body configuration is arranged using overset mesh technique under large scale computing environment for turbulent viscous flow. Various pre- and post-processing techniques which are required of overset flow analysis and sensitivity analysis codes are discussed for design optimization problems based on gradient based optimization method (GBOM). The overset flow analysis code is validated by comparing with the experimental data of a wing/body configuration (DLR-F4) from the 1st Drag Prediction Workshop (DPW-I). In order to examine the applicability of the present design tools, careful design works for the drag minimization problem of a wing/body configuration are carried out by using the developed aerodynamic shape optimization tools for the viscous flow over multiple-body aircraft geometries.

• 한국전산유체공학회:학술대회논문집
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• 2006.10a
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• pp.66-69
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• 2006

In the present study, we propose a virtual boundary method for simulation of massive inextensible flexible strings immersed in viscous fluid flow. The fluid motion is governed by the Navier-Stokes equations and a momentum forcing is added in order to bring the fluid to move at the same velocity with the immersed surface. A massive inextensible flexible string model is described by another set of equations with an additional momentum forcing which is a result of the fluid viscosity and the pressure difference across the string. The momentum forcing is calculated by a feedback loop. Simulations of several numerical examples are carried out, inlcuding a hanging string which starts moving under gravity without ambient fluid, a string swimming within a uniform flow and a uniform flow over two side-by side strings. The numerical results agree well with the theoretical analysis and previous experimental observations. Preliminary results of a swimming elongated fishlike body will also be presented.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.12
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• pp.86-92
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• 2002

This paper presents a new model of NC verification in NC milling using z-map. The model can describe the motion of machine tool like a real machine effectively. The model uses x, y, and z directional feed rate as well as cutting data for modeling Z-map of workpiece. The model verifies the over-cut, the under-cut and the surface topography using NC codes and cutting conditions. To investigate the performance of the model, simulation study was carried out. As the results, the model gave the geometry accuracy of workpiece, the surface topography, and the chip loads.

• The Journal of the Acoustical Society of Korea
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• v.19 no.1E
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• pp.13-21
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• 2000

In this paper, we present the description and results of experimental study of the sound power measurements based on International Standards ISO 3741 and 3745. The sound power emitted by a calibrated reference sound source was measured in a reverberation room and a free field over a reflecting plane, using the precision methods of International Standards ISO 3741 direct method and ISO 3745, respectively. The sound power measurements carried out in this study give accurate estimation and also show that both methods for determining the sound power levels of a sound source in a reverberation room and a free field over a reflecting plane, according to the ISO 3741 and 3745, respectively, have proved equally good.

• Korean Journal of Plant Resources
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• v.10 no.3
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• pp.271-273
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• 1997

This study was carried out to obtain basic envirinmental information of the native area and growth characteristics at different age of Dendropanax morbifera LEV. In the southern Korea. The Dendropanax morbifera LEV. Was grown naturally at Wando, Cheju(Mt. Halla), Yecheon(Kermoon island),Sinan(Hong isand), Jindo(Mt. Chermchill) and Haenam(Mt. Taeroon), all between 30 to 450m above the sea level. The soil characterisitics of the native area had a pH of 5.3 to 5.4 with 8.4 to 9.8% content of organic matter and 18.2 to 21.3% soil moisture. Flowering starting in the middle of July begun when the trees were 6 years old. Six year old trees are 129 cm in stem height, 34 mm in stem diameter,15.4 in number of leaves with petioles 12.9 cm long. Xylem sap can be obtained from over 10 year old trees that grew well and have over 10 cm stems in diameter.