• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2019년도 학술발표회
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• pp.158-158
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• 2019

Recent studies show the possibility of more frequent extreme events as a result of the changing climate. These weather extremes, such as excessive rainfall, result to debris flow, river overflow and urban flooding, which post a substantial threat to the community. Therefore, an effective flood model is a crucial tool in flood disaster mitigation. In recent years, a number of flood models has been established; however, the major challenge in developing effective and accurate inundation models is the inconvenience of running multiple models for separate conditions. Among the solutions in recent researches is the development of the combined 1D-2D flood modeling. The coupled 1D-2D river flood modeling allows channel flows to be represented in 1D and the overbank flow to be modeled over two-dimension. To test the efficiency of this approach, this research aims to assess the capability of HEC-RAS model's implementation of the combined 1D-2D hydraulic simulation of river overflow inundation, and compare with the results of GERIS and FLUMENS 2D flood model. Results show similar output to the flood models that had used different methods. This proves the applicability of the HEC-RAS 1D-2D coupling method as a powerful tool in simulating accurate inundation for flood events.

• 한국입자에어로졸학회지
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• 제9권3호
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• pp.163-171
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• 2013

Soot particles emitted from combustion processes are often coated by non-absorbing organic materials, which enhance the global warming effect of soot particles. It is of importance to study the condensation characteristics of soot particles experimentally and theoretically to reduce the uncertainty of the climate impact of soot particles. In this study, the condensational growth of soot particles in a tubular coater was modeled by a one-dimensional (1D) plug flow model and a two-dimensional (2D) laminar flow model. The effects of 2D heat and mass transports on the predicted particle growth were investigated. The temperature and coating material vapor concentration distributions in radial direction, which the 1D model could not accounted for, affected substantially the particle growth in the coater. Under the simulated conditions, the differences between the temperatures and vapor concentrations near the wall and at the tube center were large. The neglect of these variations by the 1D model resulted in a large error in modeling the mass transfer and aerosol dynamics occurring in the coater. The 1D model predicted the average temperature and vapor concentration quite accurately but overestimated the average diameter of the growing particles considerably. At the outermost grid, at which condensation begins earliest due to the lowest temperature and saturation vapor concentration, condensing vapor was exhausted rapidly because of the competition between condensations on the wall and on the particle surface, decreasing the growth rate. At the center of the tube, on the other hand, the growth rate was low due to high temperature and saturation vapor concentration. The effects of Brownian diffusion and thermophoresis were not high enough to transport the coating material vapor quickly from the tube center to the wall. The 1D model based on perfect radial mixing could not take into account this phenomenon, resulting in a much higher growth rate than what the 2D model predicted. The result of this study indicates that contrary to a previous report for a thermodenuder, 2D heat and mass transports must be taken into account to model accurately the condensational particle growth in a coater.

• 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.

• 한국IT서비스학회지
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• 제12권2호
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• pp.373-386
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• 2013

The purpose of this research is to develop a model for efficient service R&D investment in government budgeting process. It is necessary to develop an efficient and effective investment model to improve competitiveness of the service industry and national economy. Various existing types of service R&D classification have been reviewed. And object-oriented service R&D request classification types have been derived. A tentative model for evaluating service R&D requests have been developed through extensive discussions on effective methodologies. The model has been refined and revised by four service budgeting experts. The revised and refined checklists and guidelines have been used for 40 real service R&D requests evaluations. As a result, a full model for service R&D evaluation and budgeting has been proved to be useful. Also, a need for more efficient and concise evaluation model has been raised through this evaluation process. A brief model with only 10 checklists has been developed and its usefulness has been proven by pilot test with 10 real service R&D requests. The results of this study can be used for evaluation of service R&D proposals and effective budgeting of R&D requests for improving global competitiveness. Further research is needed for refining the developed evaluation models.

• 한국위성정보통신학회논문지
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• 제10권1호
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• pp.17-21
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• 2015

본 논문에서는 아마추어 무선 HR(HAM Radio)을 기반으로 구축되는 새로운 무선 재난통신망인 이동단말용 위성 통신 무선패키지 시스템과 이 재난통신망에 접속하려는 D2D 단말의 채널 환경에 대해 소개한다. 이러한 재난통신망과 D2D 단말이 서로 재난통신할 때 재난정보를 멀티미디어 데이터급 수준으로 원활하게 전송 및 통신하기 위해서는 D2D 단말이 처한 다양한 재난상황에 적응적으로 채널 값을 추정하는 채널 모델링 연구가 요구된다. 따라서 본 논문에서 LOS component ratio 기반의 적응적 채널 모델링 기법을 제안하고, 제안한 기법의 성능을 Okumura-Hata model의 Open area 및 Urban area model과 비교하였다. 컴퓨터 시뮬레이션 결과 거리 대비 BER 성능 및 SNR 대비 BER 성능에서 이득이 있음을 확인하였다.

• 한국재난정보학회 논문집
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• 제19권4호
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• pp.897-907
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• 2023

연구목적: 본 연구에서는 단일 24GHz FMCW레이더를 사용하여 수집된 적은 양의 학습데이터로 학습된 AI 모델을 사용하여 학습되지 않은 사람의 3가지 자세를 구분하고자 한다. 연구방법: 실내에서 학습 대상자들의 3가지 자세(서기, 앉기, 눕기)에 대한 FFT데이터를 수집하여 2D 이미지로 변환시킨 후 제안하는 2D CNN 모델로 학습시켜 학습에 사용되지 않은 새로운 대상자들의 자세를 잘 구분할 수 있는지 실험을 통해 정확도를 분석하였다. 연구결과: 제안하는 기법을 통해 3가지 자세의 평균 정확도가 89.99%임을 보였고, 기존의 1D CNN이나 SVM 보다 성능이 향상되었다. 결론: 실내에서 재난이 발생하는 경우 단일 FMCW 레이더와 AI 기법을 통해 요구조자의 자세를 추정하고자 하였으며, 학습되지 않은 대상자의 자세도 높은 정확도로 추정이 가능함을 실험을 통해 확인하였다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2004년도 봄 학술발표회 논문집
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• pp.301-308
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• 2004

The present study mainly focuses on the inelastic stress analysis of the 1/4 scale prestressed concrete containment vessel model(PCCV) under internal pressure and evaluates not only failure mode but also ultimate pressure capacity of the PCCV. Inelastic analysis is carried out 2D axisymmertic FE model and 3D FE model using four concrete material models which are Drucker-Prager Model, Chen-Chen Model, Damaged Plasticity Model and Menetrey-Willam Model. The uplift phenomenon of the basemat is considered in the 2D axisymmetric FE models. It is found from the 2D axisymmetric analysis results that both of Drucker-Prager model and Damaged Plasticity Model have a good performance and the uplift of the basemat is too small to influence on the global behavior of the PCCV. The FE analysis results on the ultimate pressure and failure mode have a good agreement with experimental results.

• 임산에너지
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• 제17권1호
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• pp.23-29
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• 1998

중국 백두산 북부지역 소나무천연림을 대상으로 임분의 biomass를 추정하기 위하여 5개 등급 밀도별로 각각 7본씩 표본목을 선정하여 벌도한 후 4개의 상대생장식(W=aDb, W=a(D2H)b, logW=a b·logD＋cD, logW=a＋b·log(D2H)＋c(D2H)을 이용하여 부위별로 biomass 추정식을 유도하였다. 밀도가 다른 임분에서 부위별로 적합한 biomass 추정식 유형이 다르게 나타났는데 줄기, 수피 및 지상부 전체 biomass량을 추정하는 경우, logW=a＋b·log(D2H)＋c(D2H)식이 결정계수는 높고 상대오차 추정치는 낮게 나타나 적합도가 높았다. 가지, 잎 biomass량 및 엽면적의 경우는 logW=a＋b·logD＋cD식이 상관계수가 높고 상대오차 추정치는 낮게 나타나 적합하였다.

• Journal of Biosystems Engineering
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• 제18권3호
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• pp.209-219
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• 1993

A series of soil bin experiment was carried out on sand to investigate if true model theory is applicable to blade-soil system and finally to find mathematical relationship between the dimensionless terms which contain the blade-soil parameters. The following conclusions were derived from the study. 1. It was proved that the draft of the prototype blade can be predicted without distortion by those of model blades with the length scale of 1.2, 2 and 2.4. 2. For the sand, bulk density was found to be a good measure of soil physical properties which are pertinent to predict the draft of the blade-soil system. 3. The mathematical relationship between $D/{\gamma}W$ and d/W, ${\beta}$, and $V^2/Wg$ are as follows ; $$\frac{D}{{\gamma}W^3}=124.98[\frac{d}{W}]^2+7.16[\frac{d}{W}]+0.43 \\ \frac{D}{{\gamma}W^3}=-0.00099{\beta}^2+0.13{\beta}-2.01 \\ \frac{D}{{\gamma}W^3}=0.041[\frac{V^2}{Wg}]^2+0.08[\frac{V^2}{Wg}]+1.3$$

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.358-363
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• 2008

Through this study, 2D multibody dynamics models for analysis of train collisions have been developed to evaluate the crashworthiness requirements of the TSI regulation. The crashworthiness regulation requires some performance requirements for two heavy collision accident scenarios; a train-to-train collision at the relative speed of 36 kph, and a collision against a standard deformable obstacle of 15 ton at 110 kph. The complete train set will be composed of hybrid model with 2D and 1D model. Using numerical analysis of the hybrid model, some crashworthy design were evaluated in terms of mean crush forces and energy absorptions for main crushable structures and devices. especially, 2D model can evaluate overriding effect in train collisions. It is shown from the simulation results that the suggested hybrid model can easily evaluate the crashworthiness requirements.