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Changkeun Son 한국전산유체공학회 2014 한국전산유체공학회 학술대회논문집 Vol.2014 No.10
The main objective of this study is to analyze flow and heat transfer characteristics of a heat exchanger in an industrial application using a high-fidelity simulation. LES was performed to analyze turbulent flows around a fin-tube heat exchanger inside an enclosure. Because of the wide range of the local Re in the complex geometry, various scales of 3-D vortices and complex flow patterns were generated. Tests with the grid resolution and inflow condition were performed carefully, in order to compare our results with the data from a MRV experiment as well as the results from RANS. The complex flow patterns like 3-D vortices were visualized using various techniques. A few interesting flow phenomena were observed which are different from the results of a plain fin-tube heat exchanger such as helical flows and a jet stream observed behind the fin-tube region. The complex flow structures and spatial pressure imbalance were found in the fluctuation of the jet stream. To enhance the efficiency of the computational costs, a few performance factors of the heat exchanger were compared with the results of the plain fin-tube things. As the results, numerical technique was derived to reduce the computational costs, using a porous media model.
Son, Minsu,Kim, Brian H.S.,Park, ChangKeun Asian Society for Innovation and Policy 2021 Asian Journal of Innovation and Policy Vol.10 No.1
The increase of international trade across countries and borders results in increased risks associated with the inflow of new pests and diseases. These risks are likely to be increased more rapidly due to climate change. Some countries implement strict regulations on imports to prevent these risks and protect biosecurity, food safety, and public health. However, the problems arise when the diseases and pests are found in a country where their economic structure largely depends on agricultural exports and cause ripple effects on other industries and ecosystems. Therefore, establishing an effective quarantine system is essential to protect and recover from the damage caused by non-native diseases and pests. This study's objectives are 1) analyzing the agricultural policies relate to the quarantine system on diseases and pests in Korea, 2) evaluating the Korea plant quarantine system's value, and 3) simulating plant quarantine policy strategies. We estimated the Korean quarantine system's benefits on diseases and pests to reach these objectives. The benefits are measured with a willingness to pay from respondents surveyed by the contingent valuation method (CVM). The CVM approach directly asks people how much they would willingly pay for food security. Finally, the Korean quarantine system's values are simulated with several policy scenarios and different scales of infection at the regional level. The results of this study can deliver policy implications on the quarantine system innovation in developing countries including Asia.
이창근(Changkeun Lee),손민수(Minsu Son),김의준(Euijune Kim) 한국도시행정학회 2011 도시 행정 학보 Vol.24 No.1
The purpose of this paper is to study the expansion of consumer choices utilizing a voucher system taking into consideration the institutional measures currently in place. The option of having the voucher system will require the redefinition of the system in order to differentiate between the coupons and vouchers. The criteria applied for the income support settings as well as the minimum burden absorbed by social services will be differentiated according to the types of goods in question. This is much more flexible in terms of the range of choices and will contribute to the increased utility for consumers. In addition, the voucher classification system is a standalone and integrated system that is necessary. The goods and services provided by the individual vouchers (coupons) divide the amount as well as the amount available of the real opportunity costs which are separated between the local and central governments. This will lead to consolidation of similar voucher systems. Finally, the principles of choice and competition are needed in order to work seamlessly with the vouchers. Therefore it is necessary to utilize a computerized system for the voucher.