• Spatial Information Research
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• v.6 no.1
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• pp.1-10
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• 1998

The need of aerial photographs is increasing for small area development such as facility management, site planning, residence planning, and so on. It is not an easy task, however, to take aerial photographs using an aircraft for metric photogrammetry because of the strict regulatins of flying and also photographing in Korea, as well as the cost. As one of efficient methods to take large-scale aerial photographs, we investigated the ways of photographing by a remote controlled model plane(RC plane) with a light weight non-metric camera on board. We had examined the principles of RC planes and assembled a RC plane, And test photographing was performed. Even though we obtained reasonably good stereo-pairs for the grounds and facilities using the RC plane, we found there were yet many problems to be solved, such as difficulties of RC plane control, camera focusing, and accumulation of dust on the camera lens.

• The Journal of Bigdata
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• v.4 no.2
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• pp.105-114
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• 2019

Missing value replacement is one of the big issues in data analysis. If you ignore the occurrence of the missing value and proceed with the analysis, a bias can occur and give incorrect results for the estimate. In this paper, we need to find and apply an appropriate alternative to missing data from weather data. Through this, we attempted to clarify and compare the simulations for various situations using existing methods such as MICE and MissForest based on R and time series-based models. When comparing these results with each variable, it was determined that the kalman filter of the auto arima model using the ImputeTS package and the MissForest model gave good results in the weather data.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.44.1-44.1
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• 2017

In barred galaxies, gaseous structures such a nuclear ring and dust lanes are formed by a non-axisymmetric stellar bar potential, and the evolution of the stellar bar is influenced by mass inflows to the center and central star formation. To study how the presence of the gas affects the evolution of the stellar bar, we use the mesh-free hydrodynamics code GIZMO and run fully self-consistent three-dimensional simulations. To explore the evolution with differing initial conditions, we vary the fraction of the gas and stability of initial disks. In cases when the initial disk is stable with Q=1.2, the bar strength in the model with 5% gas is weaker than that in the gas-free model, while the bar with 10% gas does not form a bar. This suggests that the gaseous component is unfavorable to the bar formation dynamically. On the other hand, in models with relatively unstable disk with Q=1.0, the presence of gas helps form a bar: the bar forms more rapidly and strongly as the gas fraction increases. This is because the unable disks form stars vigorously, which in turn cools down the stellar disk by adding newly-created stars with low velocity dispersion. However, the central mass concentration also quickly increases as the bar grows in these unstable models, resulting in fast bar dissolution in gas rich models. We will discuss our results in comparison with previous work.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.43.1-43.1
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• 2017

A three-dimensional (3D) $Ly{\alpha}$ radiative transfer code is developed to study the Wouthuysen-Field effect, which couples the 21 cm spin temperature of neutral hydrogen and the $Ly{\alpha}$ radiation field, and the escape fraction of $Ly{\alpha}$ from galaxies. The Monte Carlo code is capable of treating arbitrary 3D distributions of $Ly{\alpha}$ source, neutral hydrogen and dust densities, gas temperature, and velocity field. It is demonstrated that the resonance-line profile at the center approaches to the Boltzmann distribution with the gas temperature. A plane-parallel ISM model, which is appropriate for the neutral ISM of our Galaxy, is used to calculate the $Ly{\alpha}$ radiation field strength as a function of height above the galactic plane. We also use a two-phase, clumpy medium model which is composed of the cold and warm neutral media (WNM). It is found that the $Ly{\alpha}$ radiation field is strong enough to thermalize the 21 cm spin temperature in the WNM to the gas kinetic temperature. The escape fraction of $Ly{\alpha}$ is found to be a few percent, which is consistent with the $Ly{\alpha}$ observations of our Galaxy and external galaxies.

• Proceedings of the Korean Reliability Society Conference
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• 2011.06a
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• pp.107-113
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• 2011

The windshield wiper consists of 4 parts: a blade, an arm, a linkage and a motor. The wiper blade makes contact with the windshield and is designed to be operated normally at an angle of 30~50 degrees to the front glass. If the contact pressure between the wiper blade and windshield surface is too high, noise and wear of the rubber will result. On the other hand, if the contact pressure is too low, the performance will do badly, since foreign substances such as dust and stains will not be removed well. The pressure and friction of the wiper blade has a great influence on its effectiveness in cleaning the front window. This is due to the contact of the rubber with the window. This paper presents the dynamic analysis method to estimate the performance of the flat type blade of the wiper system. The blade has a nonlinear characteristic since the rubber is an incompressible hyper-elastic and visco-elastic material. Thus, Structural dynamic analysis using a complex contact model for the blade is performed to find the characteristics of the blade. The flexible multi-body dynamic model is verified by the comparison between test and analysis result. Also, the optimization using the central composite design table is performed.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.105-108
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• 2007

최근 세라믹 막은 우수한 화학적, 열적 안정성으로 기체 분리 공정에 각광을 받아왔다. 특히 혼합기체에서 고 순도의 수소를 분리해 내는 기술은 연료전지 공정에서 화학 에너지를 적기화학 에너지로 전환시키는데 중요한 역할을 차지한다. 본 연구에서는 MTES 템플레이팅 막을 이용하여 이 막 공정의 흡착 및 투과 특성을 규명하고, 이성분 혼합기체에서 고 순도의 수소를 추출해 낼 수 있는 최적 조건을 도출해 내었다. 또한, 기체 분리 거동을 살펴보기 위해 Gproms Simulator를 이용하였으며, 이때 기체상의 물질전달을 모사하기 위해 Dust Gas Model(DGM)을, 표면 확산 거동을 모사하기 위해 Generalized Stefan-Maxwell(GSM)식을 적용하였다. 이를 통해 평형론적 흡착 뿐 아니라 속도론적 흡착을 동시에 적용할 수 있게 하였다. MTES 템플레이팅 막의 흡착 및 분리능을 규명하기 위해 본 연구에서는 혼합기체의 투과, 분리 실험이 선행되었다. 실험 조건은 온도범위 $30{\sim}50$ $^{\circ}C$, 압력범위 $0{\sim}5$ atm에서 수행되었으며, 혼합기체는 2성분으로 수소 메탄, 수소-이산화탄소, 수소-질소로 기체의 구성비는 각각 50:50 이다. 본 연구를 통해 각 혼합 기체들이 정상상태에 도달하는 시간과 분리능을 계산해 내었으며, 이 분리능을 다시 온도와 압력에 따른 결과로 분석하여 어느 조건에서의 수소 분리도가 최고치를 보이는지를 규명했으며, 시뮬레이션과 비교, 대조하여 예측도를 검사하였다.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.1
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• pp.71.1-71.1
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• 2010

We present the FUV continuum map of The Taurus-Auriga-Perseus complex, which is one of the largest local association of dark clouds. The map is well consistent with the dust extinction and the CO emission map of the T-P-A region. The region is divided into 3 sub-regions by diffuse FUV intensities and the spectra of each region imply that the radiation field due to the Per OB2-association can be a main source of the H2 fluorescent emission of the nearby cloud region. We used the PDR H2 model, named CLOUD, developed by van Dishoeck &Black for the sake of comparing our results to the H2 model.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.1
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• pp.59.3-59.3
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• 2018

With a recent observational study of extended Lyman-alpha halos around individual high-z star-forming galaxies by Leclercq et al. (2017) using MUSE, we perform radiative transfer calculations to see if Lyman-alpha scattering can explain the spatial extents of the halos together with their spectra. We adopt a spherically-symmetric halo model in which Lyman-alpha sources and neutral hydrogen (HI) medium have exponential density distributions. The HI medium is set to have outflowing motion based on a momentum-driven wind scenario in a gravitational potential well. We run our Lyman-alpha radiative transfer code, LaRT, upon this halo model for various sets of parameters regarding the HI medium such as temperature, optical depth, density scale radius, outflow velocities, and dust content. We analyze simulation results to see the impact of each parameter on Lyman-alpha spectra and surface brightness profiles, and degeneracies between the parameters. We also find a parameter set that best reproduces simultaneously the observed spectra and surface brightness profiles of the MUSE Lyman-alpha halos.

• Journal of Engineering Education Research
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• v.23 no.2
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• pp.14-23
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• 2020

Based on the constructivist learning environments model and the learner-centered psychological principles, STEAM education program with the theme of eliminating smog was developed. Through the program, senior elementary school students will learn and apply the convergence knowledge of science, technology, engineering, arts and mathematics such as the human body's respiratory system (S), immune system (S), big data (M, T), computer programming(M), and aduino sensor utilization (E) directly to solve the problem. After expert validity testing, we found that developed program meet the standards of STEAM education program development and can develop creative thinking skills to find and solve problems in students' daily lives. In addition, this study is meaningful in providing a reference example for the development of STEAM education programs that enhance convergence knowledge in the future.

• Journal of Korean Society for Atmospheric Environment
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• v.8 no.4
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• pp.269-276
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• 1992

Typical lebvels of heavy metal exposure for humans may be attributed to four components in the environment ; food, inhaled air, various types of dust, and drinking water. To assess the health risk of lead, it is necessary to estimate the blood lead levels in the populations of concern under various air lead concentrations. The blood lead levels of the population in Seoul and Yeoju are estimated by Biokinetic model for the risk assessment in this study. The differences in blood lead levels between areas of different land use are not dominant but some differences show among different age groups and sex. Blood lead levels of the population show log normal distribution. The geometric standard deviation values of blood lead levels are in the range of 1.25 ~ 1.39, it is somewhat smaller than the values in the general U.S pollution which are determined to be from 1.31 to 1.41 by the U.S. EPA.