• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.5
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• pp.640-651
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• 2000

For the heat and fluid flow analyses of a parallel flow heat exchanger, an improved model considering the effect of flat tube with micro-channels is proposed. The effect of flow distribution on the thermal performance of a heat exchanger is numerically investigated. The flow distribution is examined by varying geometrical parameters, i.e., the position of the separators and the inlet/outlet, and the aspect ratio of micro-channels of the heat exchanger. The flow nonuniformities along the paths of the heat exchanger are proposed and observed to evaluate the thermal performance of the heat exchanger. The optimization using ALM method has been accomplished by minimizing the flow nonuniformity. It is found that the heat transfer rate of the optimized model is increased by 6.0% of that of the reference heat exchanger model, and the pressure drop by 0.4%

• Journal of the Korea Society of Computer and Information
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• v.22 no.10
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• pp.145-150
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• 2017

This study aims to analyze panel data using OECD Health data of 34 years to examine how significant the inequality of income is to the inequality of health. The data was from OECD's pooled Health data of 32 countries from 1980 to 2013. The process of determining analysis model was as follows; First, through the descriptive statistics, we examined averages and standard deviation of variables. Second, Lagrange multiplier test has done. Third, through the F-test, we compared Least squares method and Fixed effect model. Lastly, by Hausman test, we determined proper model and examined effective factor using the model. As a result, rather than Pooled OLS Model, Fixed Effect Model was shown as effective in order to consider the characteristics of individual in the panel. The results are as follows: First, as relative poverty rate(${\beta}=-19.264$, p<.01) grows, people's life expectancy decreases. Second, as the rate of smoking(${\beta}=-.125$, p<.05) and the rate of unemployment (${\beta}=-.081$, p<.01) grows, people's life expectancy decreases. Third, as health expenditure(${\beta}=.414$, p<.01) shares more amount of GDP and as the number of hospital beds(${\beta}=-.190$, p<.05) grows, people's life expectancy increases.

• Journal of the Korean association of regional geographers
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• v.19 no.2
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• pp.246-258
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• 2013

The relocation of the public institutions such as the provincial government attracts much attentions since it results in substantial regional economic impacts. In this context this paper analyzes the effects of relocation of Gyeongsangbuk-Do provincial government from Daegu city to Gyeongsangbuk-Do, which is scheduled for 2014, on Daegyeong economic region. Based on the interregional input-output model and I-O data which were provided by the Bank of Korea, this paper examines the multiplier effects of the relocation in terms of production, value added, and employment on Daegyeong economic region and other regions, except for the construction effects of the provincial capital. According to the analysis, the relocation is expected to reduce the production by 290million won, value added by 709million won, and employment by 571 persons in Daegyeong economic region. Also, the relocation turns out to decrease the production by 1,179million won and value added by 123million won of other regions. This paper discusses some policy implications of the analysis.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.1
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• pp.9-18
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• 2013

Two-phase vapor-liquid flows exist in many shell and tube heat exchangers such as condensers, evaporators, and nuclear steam generators. To understand the fluid dynamic forces acting on a structure subjected to a two-phase flow, it is essential to obtain detailed information about the characteristics of a two-phase flow. The characteristics of a two-phase flow and the flow parameters were introduced, and then, an experiment was performed to evaluate the pressure loss in the tube bundles and the fluid-dynamic force acting on the cylinder owing to the pressure distribution. A two-phase flow was pre-mixed at the entrance of the test section, and the experiments were undertaken using a normal triangular array of cylinders subjected to a two-phase cross-flow. The pressure loss along the flow direction in the tube bundles was measured to calculate the two-phase friction multiplier, and the multiplier was compared with the analytical value. Furthermore, the circular distributions of the pressure on the cylinders were measured. Based on the distribution and the fundamental theory of two-phase flow, the effects of the void fraction and mass flux per unit area on the pressure coefficient and the drag coefficient were evaluated. The drag coefficient was calculated by integrating the measured pressure on the tube by a numerical method. It was found that for low mass fluxes, the measured two-phase friction multipliers agree well with the analytical results, and good agreement for the effect of the void fraction on the drag coefficients, as calculated by the measured pressure distributions, is shown qualitatively, as compared to the existing experimental results.

• Journal of the Korean Regional Science Association
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• v.33 no.2
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• pp.25-37
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• 2017

The paper is basically designed to investigate how regional consumption affects to regional income in Korea by introducing a model with panel cointegration, rational expectation and FM-OLS cointegration methodology. Empirical evidence reveals that the regional income could be stimulated by manipulating the regional consumption due to the fact that current regional consumption and first-lagged regional income are positively related to the level of regional income. Although there exists a possibility to increase the regional income which is associated with a spending multiplier in the group of regions with highly calculated MPC, but not in the groups of regions with middle and low calculated MPCs. To this end, it could be tentatively concluded that market-oriented system should be implemented elaborately to enable that the spending multipliers are appropriately operated in these two groups.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.4
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• pp.51-57
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• 2003

The development of the communication network and the other network method can generate serious social problems. So, it is highly required to control security of network. These problems related security will be developed and keep up to confront with anti-security field such as hacking, cracking. The way to preserve security from hacker or cracker without developing new cryptographic algorithm is keeping the state of anti-cryptanalysis in a prescribed time by means of extending key-length. In this paper, we proposed M3 algorithm for the reduced processing time in the montgomery multiplication part. Proposed M3 algorithm using the matrix function M(.) and lookup table perform optionally montgomery multiplication with repeated operation. In this result, modified repeated operation part produce 30% processing rate than existed montgomery multiplicator. The proposed montgomery multiplication structured unit array method in carry generated part and variable length multiplication for eliminating bottle neck effect with the RSA cryptosystem. Therefore, this proposed montgomery multiplier enforce the real time processing and prevent outer cracking.

• The Journal of Information Systems
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• v.29 no.1
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• pp.267-287
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• 2020

Purpose Online platform companies can increase the spread of content by communicating with users who have diverse preferences through social networks. Previous studies show the mixed effect on the network overlap, and there was a limited examinations for the underlying mechanism. This study expects high academic and practical implications that can be provided by studying on the user's viewership network. The purpose of this research is to examine the effects of network overlap on the users' viewership for creators of user-generated content in YouTube. We explain the direct and in-direct effects through the content sharing and the valence of user ratings. Design/methodology/approach The data contains 45 channels and 4,085 video clips from YouTube. We control the effect of the categories, channel characteristics, and vide clip characteristics on the viewership. PROCESS macro were used to analyze the direct and in-direct effects of network overlap. Findings The analysis results showed that the network overlap directly affect on the users' viewership. The variable decreases the moderators (i.e., content sharing and the valence of user ratings). This result implies that the users can not satisfy their need for uniqueness which is achieved by content sharing and rating in the overlapped network.

• The Journal of the Korea Contents Association
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• v.16 no.3
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• pp.33-42
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• 2016

Utilization of cultural contents is more and more increasing as it is believed to improve local problems and provide historical values. This kind of business is positive in terms of the fact that it attracts visitors into local areas and activate local commercial areas. Under this trend, the construction of specialized streets is required to be approached with first priority to solve problems of cities. So to speak, it's more important to solve intrinsic problems found in local communities and then approach cultural contents step-by-step rather than constructing new spaces with first priority. Moreover, cultural contents should accompany economic aspects which result in local community-friendly and sympathetically concentrated values. Under this sentiment, the efforts to suggest economic ripple effects for government local government's businesses using cultural contents are very important. This study analyzed how much economic ripple effects is yielded by reflecting cultural contents. As the result of analysis, specialized street with cultural contents applied are proved to be more concentrated on multiplier of expediting employment, income and tax and tourism industry than service industry. On the contrary to this, service industry showed more concentrated multiplier of expediting production, income, added values and chain reaction effect (coefficients for influence and sensitivity for front and rear side of tourism industry. Based on these results, construction of specialized streets with cultural contents applied is proved to help synergy effects for local economy.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.2
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• pp.43-53
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• 1998

This paper addresses an optimization for reducing a steering error of a rack-and-pinion steering linkage with a MacPherson strut independent front suspension system. The length, orientations and inner joint positions of a tie-rod are selected as design variables and Ackerman geonetry, understeer effect, minimum turn radius, wheel alignment and packaging are considered as design constraints. Nonlinear kinematic analysis of the steering system is performed for calculating the values of cost and constraints, and Augmented Lagrange Multiplier(ALM) method is used for solving the constrained optinization problem. The optimization results show that the steering error are considerably reduced while satisfying all the constraints.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.50 no.12
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• pp.584-589
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• 2001

This paper presents an implementation method of multi-channel synchronized phasor measurement device, which is based on the ASIC implementation of the sliding-DFT. A time-shared multiplier structure is proposed to minimize the number of gates required for the implementation. The design is verified by the timing simulation of its operation. The effect of coefficient approximation in the recursive implementation of the sliding-DFT is analytically derived and verified with the computer simulations.