• 한국연소학회:학술대회논문집
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• 한국연소학회 2015년도 제51회 KOSCO SYMPOSIUM 초록집
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• pp.113-114
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• 2015

In this study, 1D and 3D thermoacoustic analysis model were developed in order to predict fundamental characteristics of combustion instability in a gas turbine lean premixed combustor. The 1D network model can be used to analyze frequency and growth rate of combustor instability by simply dividing whole system into a couple of acoustic sub-elements, while the 3D Helmholtz solver model can predict directly acoustic modes as well as basic properties of combustion instability. Prediction results of both 1D and 3D models generally showed a good agreement with the measurements, even if there was a slight overestimation for instability range.

• 대한원격탐사학회지
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• 제23권1호
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• pp.43-53
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• 2007

In this study, two standard specifications such as GML (Geography Markup Language) from OGC (Open Geo-spatial Consortium, Inc.) and X3D (extensible 3D) from Web3D consortium were dealt with for a web-based 3D urban application without using commercialized tools. In the first step of this study, DEM (Digital Elevation Model) and 3D GIS data sets were converted to GML structure with attribute schema. Then, these GML elements were projected onto a common coordinate system, and they were converted to the X3D format for visualization on web browser. In this work, a 3D urban data model, as a simple framework model, is extended to a framework model having further detailed information, depending upon application levels. Conclusively, this study is to demonstrate for practical uses of GML and X3D in 3D urban application and this approach can be applied to other application domains regarding system integrators and data sharing communities on distributed environments.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2011년도 한국우주과학회보 제20권1호
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• pp.30.1-30.1
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• 2011

We present construction of 3D Earth optical Model for in-orbit performance prediction of L1 halo orbiting earth remote sensing instrument; the Albedo Monitor and Radiometer (Amon-Ra) using Integrated Ray Tracing (IRT) computational technique. The 3 components are defined in IRT; 1) Sun model, 2) Earth system model (Atmosphere, Land and Ocean), 3)Amon-Ra Instrument model. In this report, constructed sun model has Lambertian scattering hemisphere structure. The atmosphere is composed of 16 distributed structures and each optical model includes scatter model with both reflecting and transmitting direction respond to 5 deg. intervals of azimuth and zenith angles. Land structure model uses coastline and 5 kinds of vegetation distribution data structure, and its non-Lambertian scattering is defined with the semi-empirical "parametric kernel method" used for MODIS (NASA) missions. The ocean model includes sea ice cap with the sea ice area data from NOAA, and sea water optical model which is considering non-Lambertian sun-glint scattering. The IRT computation demonstrate that the designed Amon-Ra optical system satisfies the imaging and radiometric performance requirement. The technical details of the 3D Earth Model, IRT model construction and its computation results are presented together with future-works.

• 한국신뢰성학회지:신뢰성응용연구
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• 제17권4호
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• pp.296-304
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• 2017

Purpose: Recent weapon systems in defense have increased the complexity and importance of software when developing multifunctional equipment. In this study, we analyze the accuracy of the proposed software reliability model when applied to weapon systems. Methods: Determine the similarity between software reliability analysis results (prediction/estimation) utilizing data from developing weapon systems and system failures data during operation of weapon systems. Results: In case of a software reliability prediction model, the predicted failure rate was higher than the actual failure rate, and the estimation model was consistent with actual failure history data. Conclusion: The software prediction model needs to adjust the variables that are appropriate for the domestic weapon system environment. As the reliability of software is increasingly important in the defense industry, continuous efforts are needed to ensure accurate reliability analysis in the development of weapon systems.

• 한국전자파학회논문지
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• 제12권4호
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• pp.622-629
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• 2001

본 논문에서는 Ku 대역 위성중계기에 사용되는 저위상잡음 특성을 갖는 Engineering Model 전압제어 발진기를 비선형 설계방법으로 설계하였다. 제작한 발진기의 주파수는 1~5 V의 제어전압으로 1.745~1.577MHz의 발진범위를 갖는다. 공급전력은 5V, 6.9mA를 요구한다. 제작한 발진기의 위상잡음은 -114 dBc/Hz ＠10kHz offset, -131 dBc/hz ＠100kHz offsetf을 갖고 출력전력으로 5 dBm을 얻었다.

• Nutrition Research and Practice
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• 제3권4호
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• pp.286-294
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• 2009

This study aimed to identify risk factors for type 2 diabetes (T2D) in Korea, a rapidly changing country. Data of 5,132 adults aged 20-85 were used from the 2001 Korean Health and Nutrition Examination Survey. Multiple logistic regression was carried out to identify risk factors for T2D. Three models were specified: (i) socioeconomic and demographic factors (model 1: age, gender, education, poverty income ratio, employment), (ii) behavioral risk factors and covariates (model 2: obesity, physical activity, smoking, alcohol drinking, dietary quality, family history of T2D, co-morbidity) and (iii) socioeconomic, demographic, and behavioral factors (model 3). The prevalence of T2D was 7.4%. Less education (OR 1.41, 95% CI 1.08-1.84), age (OR 2.19, 95% CI 1.56-3.08 in 40-59 yrs, OR 4.05, 95% CI 2.76-5.95 in 60 yrs + comparing to 20-39 yrs) and abdominal obesity (OR 2.24, 95% CI 1.79-2.82) were risk factors for T2D even after controlling for other factors simultaneously. There was a significant association of T2D with ever smoking (OR 1.34, 95% CI 1.06-1.67). The relationship of age with T2D was modified by gender in model 1 and the relationship of smoking with T2D was modified by obesity in model 2. Less educated, older, obese or ever smokers were more likely to have T2D. Gender mediated the relationship of age, and obesity mediated the relationship of smoking, with T2D. Intervention programs for T2D in Korea should take the interactions among risk factors into account.

• 한국수자원학회논문집
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• 제50권4호
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• pp.263-275
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• 2017

고정확도의 도시침수 모의를 위해서는 물리적 개념에 기반한 통합적 수치해석이 필요하다. 본 연구에서는 Lee et al. (2015)이 개발한 1차원 하수관망, 2차원 범람 모형의 국내 적용성을 검토하고, 과거 도시 홍수 사상의 침수 원인 분석을 수행하였다. 본 모형은 이중배수 개념에 기반하여 멘홀 대신 집수구를 지표면과 하수관망 사이의 교환유량 산정 지점으로 이용하므로 보다 실제와 유사하게 침수 과정을 모의할 수 있을 뿐 아니라 지표면 범람 해석시 건물에 의한 차단 효과를 고려할 수 있다. 개발된 모형의 적용성은 서울 사당 유역에서 발생한 침수 사상에 대해서 재현 모의를 통해 검증하였다. 적용 결과, 본 연구에서 개발된 모형은 실제 침수 피해 영역을 실제와 유사하게 모의 하였을 뿐만 아니라 침수 원인을 보다 자세히 분석할 수 있는 장점을 보여주었다.

• 대기
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• 제25권1호
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• pp.149-154
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• 2015

As an attempt to improve fog predictability at Incheon International Airport (IIA) we couple the 3D weather forecasting model currently operational in Korea Meteorological Administration (regional Unified Model, UM_RE) with a 1D turbulence model (PAFOG). The coupling is done by extracting the meteorological data from the 3D model and properly inserting them in the PAFOG model as initial conditions and external forcing. The initial conditions include surface temperature, 2 m temperature and dew point temperature, geostrophic wind at 850 hPa and vertical profiles of temperature and dew point temperature. Moisture and temperature advections are included as external forcing and updated every hr. To validate the performance of the coupled system, simulation results of the coupled system are compared to those of the 3D model alone for the 22 sea fog cases observed over the Yellow Sea. Three statistical indices, i.e., Root Mean Square Error (RMSE), linear correlation coefficient (R) and Critical Success Index (CSI), are examined, and they all indicate that the coupled system performs better than the 3D model alone. These are certainly promising results but more improvement is required before the coupled system can actually be used as an operational fog forecasting model. For the RMSE, R, and CSI values for the coupled system are still not good enough for operational fog forecast.

• Journal of Computational Design and Engineering
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• 제1권2호
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• pp.96-102
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• 2014

In the field of design and manufacturing, there are many problems with managing dynamic states of three-dimensional (3D) objects. In order to solve these problems, the four-dimensional (4D) mesh model and its modeling system have been proposed. The 4D mesh model is defined as a 4D object model that is bounded by tetrahedral cells, and can represent spatio-temporal changes of a 3D object continuously. The 4D mesh model helps to solve dynamic problems of 3D models as geometric problems. However, the construction of the 4D mesh model is limited on the time-series 3D voxel data based method. This method is memory-hogging and requires much computing time. In this research, we propose a new method of constructing the 4D mesh model that derives from the 3D mesh model with continuous rigid body movement. This method is realized by making a swept shape of a 3D mesh model in the fourth dimension and its tetrahedralization. Here, the rigid body movement is a screwed movement, which is a combination of translational and rotational movement.

• 한국전기전자재료학회논문지
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• 제25권1호
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• pp.6-14
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• 2012

For integrated complementary metal oxide semiconductor (CMOS) circuits, the lateral spread for two-dimensional (2-D) impurity distributions are very important for the analyzing the devices. The measured two-dimensional SEM data obtained using the chemical etching-method matched very well with the results of the Gauss model for boron implanted samples. But the profiles in boron implanted silicon were deviated from the Gauss model. The profiles in boron implanted silicon were shown a little bit steep profile in the deep region due to backscattering effect on the near surface from the bombardments of light boron ions. From the simulated 3-D data obtained using an analytical model, the 1-D and 2-D data were compared with the experimental data and could be verified the justification from the experimental data. The data of 3-D model were also shown good agreements with the experimental and the simulated data. It can be used in the 3-D chip design and the analysis of microelectro-mecanical system (MEMS) and special devices.