• 한국분무공학회지
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• 제21권1호
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• pp.47-52
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• 2016

This paper describes the modeling of CNG direct injection using gaseous sphere injection model. Simulation of CNG direct injection does not need break up and evaporation model compared to that of liquid fuel injection. And very fine mesh is needed near the injector nozzle to resolve the inflow boundary. Therefore it takes long computation time for gaseous fuel injection simulation. However, simulation of CNG direct injection could be performed with the coarse mesh using gaseous sphere injection model. This model was integrated in KIVA-3V code and RNG $k-{\varepsilon}$ turbulence model needs to be modified because this model tends to over-predict gas jet diffusion. Furthermore, we preformed experiments of gaseous fuel injection using PLIF (planar laser induced fluorescence)method. Gaseous fuel injection model was validated against experiment data. The simulation results agreed well with the experiment results. Therefore gaseous sphere injection model has the reliability about gaseous fuel direct injection. And this model was predicted well a general tendency of gaseous fuel injection.

• 한국전산유체공학회지
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• 제13권1호
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• pp.1-6
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• 2008

Direct Write Technologies are being utilized in various industrial fields such as antennas, engineered structures, sensors and tissue engineering. With Direct Write Technologies, producing features have the mesoscale range, from 1 to 100 microns. One form of the Direct Write Technologies is based on aerosol dynamics. The shape of deposited aerosols determine the form of products in the Direct Write Technology based on aerosol dynamics. To predict shape of deposited aerosol, a prediction model is created. In this study, we estimated Line-Width and Line-Thickness from the prediction model. Results of prediction model is valid from comparison with experimental results.

• 대한산업공학회지
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• 제29권4호
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• pp.321-333
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• 2003

Although manufacturing cost is a major part of profit in a company, it is difficult to be calculated by an analytic method. Besides, the manufacturing cost gained by simple financial structure dose not have an important meaning in market place. Therefore, an analytic method of computing the manufacturing cost is very necessary in manufacturing system. In this study, we suggested the direct cost analysis model which are able to measure accurate cost analysis of product in manufacturing system. The direct cost analysis model is made up of directly used expenditure for unit product. Also, system performances are put in the manufacturing cost analysis model so that it could be possible to analyze the change of manufacturing cost as system performances change. At the end of this paper, it verifies its relevancy and practicality of the suggested direct cost analysis model through the case study, using real data for direct labor cost.

• 농업과학연구
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• 제43권4호
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• pp.595-602
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• 2016

In pigs, individuals in the same pen may show aggressive behavior toward each other, such as tail biting. Such social interactions among pen mates may considerably affect their welfare and performance, both in negative and positive ways. The present study was conducted to investigate social genetic effects on days to 90 kg using data from 12,208 Duroc and Yorkshire pigs that were born between 2008 and 2012. Heritability was estimated using the five following animal models: a basic model with direct heritable effects only (Model 1), a social model with direct and social heritable effects (Model 2), a model accounting for covariance between direct and social heritable effects (Model 3), and two models considering a dilution factor with direct and social heritable effects (Models 4 and 5). The optimal model to represent Duroc pigs was Model 1 which only uses direct heritable effects. Direct heritability (0.21) was higher than total heritability (0.09) and covariance was negative. Model 2 was evaluated as the optimum model for Yorkshire pigs. Yorkshire data showed that total heritability (0.5) was twice as high as direct heritability (0.25) and covariance was positive. Our results suggest that the efficiency of social effects differed among breeding lines. Further research on social effects related to breeds by group size would clarify which is the most efficient selection method that accounts for social genetic effects.

• 한국정보처리학회논문지
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• 제4권9호
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• pp.2403-2411
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• 1997

Direct3D는 새로운 3차원 그래픽 가속기로써, 이를 이용하여 보다 쉽게 윈도우용 그래픽 프로그램을 제작할 수가 있다. 여기서는 Direct3D를 이용하여 제작한 프랙탈 지형 데이터 모델 뷰어를 제시한다. 지형 모델 뷰어 제작에 따른 클래스의 정의, 입력을 위한 대화상자의 설계, 초기화 과정, 프로그램의 실행과정을 설명하고 지형 모델 뷰어의 실행으로 얻어진 결과중, 철사형, 솔리드형, 포인트형의 출력을 보인다. 지형 형상화의 결과를 보이기 위하여, 여기서는 프랙탈 격자형 중간점 이동 알고리즘에 의하여 만들어진 데이터를 사용하였다.

• The Journal of Asian Finance, Economics and Business
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• 제7권4호
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• pp.121-131
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• 2020

This study aims to investigate the interplay between education and local roads on Foreign Direct Investment (FDI) in the Philippines, using economic growth as an instrument. The study used the quantitative research design applying both descriptive and inferential statistics. A combination of Two Stage Least Square Regression Model and three approaches in Panel Regression Model such as Pooled Least Square, Fixed Effect Model, and Random Effect Model were utilized in order to study the effects of education and local roads on foreign direct investment of the Philippines. Based on Fixed Effect regression results, higher education graduates and local road investments, as conditioned by economic growth, were significant factors in order to increase the foreign direct investment in the Philippines. Accordingly, a unit increase in higher education graduates, as conditioned by economic growth, leads to 8.758 unit increases in the foreign direct investment. While, a unit increased in local road investments, as conditioned by economic growth, leads to a 0.002 decrease in foreign direct investment. The regression results of the study suggest that the Foreign Direct Investment in the regions such as CAR, I, II, IV-B, V, VIII, IX, X, XI, XII, XIII, and ARMM are higher compared to Region IV-A.

• 동아시아경상학회지
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• 제8권3호
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• pp.43-56
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• 2020

Purpose - This study was carried out to analyze the influential factors of how consumers methodize purchasing agricultural products via direct market. It further utilizes the Discrete Choice Model to analyze consumer decision specifically with regards to individual markets and store attributes. Research design and methodology - This study will use the multinomial logit model to interpret the influential factors behind selecting a specific market to purchase from. This study establishes 'online direct-purchase' as the base category with 'direct farm markets', 'local foods direct markets', 'produce boxes (CSA)' as substitutes. Results - Firstly, the variety of products, price and freshness had a positive influence on choosing 'direct farm markets' while convenience of payment and transportation had a negative influence. Second, freshness and store attributes had a positive influence on choosing 'local foods direct markets' but product price and packaging, location accessibility had a negative influence. And although product creditability had a positive influence on purchasing 'produce boxes (CSA)', product price had a negative influence. Conclusions - Accordingly, there is a need for the South Korean government to encourage the adoption of mobile payment through smartphone applications in direct farm markets to vitalize direct agricultural purchasing. However, this does need to be approached cautiously as price has a conflicting affect for each method of purchase.

• 한국정보전자통신기술학회논문지
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• 제12권3호
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• pp.192-200
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• 2019

본 연구에서는 해외직접구매와 해외직접판매와 거시경제변수 간의 인과관계를 도출하고 공적분 검정, 충격반응을 이용하여 인과관계를 실증분석하였다. 실증분석에 이용된 모형은 벡터오차수정모형(vector error correlation model)이고, 거시경제변수인 소비자물가지수, GDP를 이용하였고, 전자상거래변수로는 해외직접구매, 해외직접판매, 온라인쇼핑액을 이용하였다. 실증분석결과에 따르면, 해외직접구매는 소비자물가지수와 인과관계가 있고, GDP는 해외직접판매, 온라인쇼핑액과 각각 인과관계가 있는 것으로 나타났다. VECM의 충격반응분석 결과에 따르면, 해외직접구매는 소비자물가지수와 GDP에는 긍정적인 영향을 미치지만, 해외직접판매는 소비자물가지수와 GDP에 부정적인 영향을 미치는 것으로 나타났다. 그리고 해외직접구매와 해외직접판매 모두 온라인쇼핑액에 부정적인 영향을 미치지만, 해외직접구매가 온라인쇼핑액에 더 큰 부정적인 영향을 미치는 것으로 나타났다.

• 근관절건강학회지
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• 제5권1호
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• pp.7-25
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• 1998

Rheumatoid arthritis, unlike other chronic diseases, causes the patients to experience uncertainty in their daily lives and thus to feel threat on their emotional comfort because of inconsistent and unpredictable symptoms such as pain. Therefore, a theoretical framework is needed for explanation of uncertainty in patients having rheumatoid arthritis. A hypothetical model was constructed on the basis of Mishel's Uncertainty Theory and other literature review. The model included 9 theoretical concepts and 19 paths. Subjects of the study constituted 330 partients who visited outpatient clinics of two university hospitals and one general hospital in Seoul. Self report questionnaires were used to measure the variables affecting uncertainty. Reliability coefficients of these instruments were found Cronbach's Alpha=$.70{\sim}.94$. In data analysis, SAS program and PC-LISREL 8.03 computer program were utilized for descriptive statistics and covariance structure analysis. The results of covariance structure analysis for model fitness were as follows : 1) Hypothetical model showed a good fit to the empirical data : Chi-square($X^2$)=41.81 (df=11, P=.000), Goodness of Fit Index=.974, Root Mean Square Residual=.049, Normed Fit Index=.928, Non Normed Fit Index=.814. 2) For the validity and the parcimony of model, a modified model was constructed by appending 2 paths and deleting 5 paths according to the criteria of statistical significance and meaningfulness. 3) The results of hypothesis testing were as follows : (1) Educational level, event familiarity and severity of illness had a direct effect on uncertainty : Event congruency had both direct and indirect effect on uncertainty : Credible authority and symptom consistency had a nonsignificant direct effect on uncertainty, (2) Illness duration, symptom consistency, and event congruency had a direct effect on severity of illness ; Credible authority had a both direct and indirect effect on severity of illness ; Event congruency had the greatest effect on severity of illness, and event familiarity had a nonsignificant direct effect on severity of illness.

• 한국물환경학회지
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• 제23권4호
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• pp.474-481
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• 2007

With population growth, industrialization, and urbanization within the watershed, the hydrologic response changed dramatically, resulting in increases in peak flow with lesser time to peak and total runoff with shortened time of concentration. Infiltration is directly affected by initial soil moisture condition, which is a key element to determine runoff. Influence of the initial soil moisture condition on hydrograph analysis should be evaluated to assess land use change impacts on runoff and non-point source pollution characteristics. The Long-Term Hydrologic Impact Assessment (L-THIA) model has been widely used for the estimation of the direct runoff worldwide. The L-THIA model was applied to the Little Eagle Creek (LEC) watershed and Its estimated direct runoff values were compared with the BFLOW filtered direct runoff values by other researchers. The $R^2$ value Was 0.68 and the Nash-Sutcliffe coefficient value was 0.64. Also, the L-THIA estimates were compared with those separated using optimized $BFI_{max}$ value for the Eckhardt filter. The $R^2$ value and the Nash-Sutcliffe coefficient value were 0.66 and 0.63, respectively. Although these higher statistics could indicate that the L-THIA model is good in estimating the direct runoff reasonably well, the Antecedent Moisture Condition (AMC) was not adjusted in that study, which might be responsible for mismatches in peak flow between the L-THIA estimated and the measured peak values. In this study, the L-THIA model was run with AMC adjustment for direct runoff estimation. The $R^2$ value was 0.80 and the Nash-Sutcliffe coefficient value was 0.78 for the comparison of L-THIA simulated direct runoff with the filtered direct runoff. However there was 42.44% differences in the L-THIA estimated direct runoff and filtered direct runoff. This can be explained in that about 80% of the simulation period is classified as 'AMC I' condition, which caused lower CN values and lower direct runoff estimation. Thus, the coefficients of the equation to adjust CN II to CN I and CN III depending on AMC condition were modified to minimize adjustments impacts on runoff estimation. The $R^2$ and the Nash-Sutcliffe coefficient values increase, 0.80 and 0.80 respectively. The difference in the estimated and filtered direct runoff decreased from 42.44% to 7.99%. The results obtained in this study indicate the AMC needs to be considered for accurate direct runoff estimation using the L-THIA model. Also, more researches are needed for realistic adjustment of the AMC in the L-THIA model.