• Journal of Korea Water Resources Association
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• v.41 no.4
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• pp.365-377
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• 2008

In this study, PROMETHEE(Preference Ranking Organization METHod for Enrichment Evaluations) which is one of the multi criteria decision making methods is applied to estimate the relative inundation risk of the urban subcatchment. For this purpose, several factors which have an effect on the inundation risk are selected and used to perform PROMETHEE. Those are elevation average, slope average, density of conduit, population and sediment yields per unit area of each subcatchment. Based on them, PROMETHEE is performed and the relative inundation risk for each subcatchment is estimated. For the validation of the suggested method, the results from the suggested method are compared with the historical inundation records occured on 1998 and the relative inundation risk estimated by the method considering sediment yields per unit area only. From the comparison, it is found that the suggested method may generate better results to estimate the relative inundation risk of each subcatchment than the method considering sediment yields per unit area only. Also, it can be applied to establish a rehabilitation order of subcatchments for mitigating the inundation risk.

• Journal of the Korean Geosynthetics Society
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• v.18 no.2
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• pp.45-54
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• 2019

This paper describes the results of finite element analysis (FEA), in order to investigate a characteristics of pile pullout behavior according to the conditions of the relative density and fines content in original ground. In the FEA, a boundary elements and strength reduction factors ($R_{inter}$) on pile-soil interface were applied to simulate appropriately the shear behavior at the pile-soil interface, and then the reliability of numerical analysis method was verified by comparison of FEA results and previous experimental research(You et al., 2018). In addition, a the deformation characteristics at the pile-soil interface and determination method of $R_{inter}$ value was laid out. The results showed that the FEA, based on the analytical model applied in this study simulates appropriately the characteristics of the pile-soil interface by pullout model test of pile. In order to apply the suggested $R_{inter}$ value, it is necessary to consider the condition of the relative density and the fines content in ground.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2061-2066
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• 2007

Recently, ultra-lightweight materials with open, periodic cell structures take much attention owing to its potential for multi-functionality such as load bearing, thermal dissipation, and actuation. This paper presents experimental results on the hydraulic and heat transfer characteristics for the Wire-woven Bulk Kagome(WBK) composed of aluminum 1100 wires. The overall pressure drop and heat transfer of the WBK specimen have been experimentally investigated under forced air convection condition. The pressure loss and heat transfer performance of the aluminum WBK are compared with other heat dissipation media. It was shown that heat transfer depended on relative density and surface area density. Comparison with metal foams and other heat dissipation media such as packed beds, lattice frame materials, louvered fins, and other materials suggests that the aluminum WBK competes favorably with the best available heat dissipation media in heat transfer performance.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.1
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• pp.15-22
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• 2008

Recently, ultra-lightweight materials with open, periodic cell structures take much attention owing to its potential for multi-functionality such as load bearing, thermal dissipation, and actuation. This paper presents experimental results on the fluid flow and heat transfer characteristics for the Wire-woven Bulk Kagome (WBK) composed of aluminum 1100 wires. The overall pressure drop and heat transfer of the WBK specimen was experimentally investigated under forced air convection condition. The pressure loss and heat transfer performance of the aluminum WBK were compared with other heat dissipation media. It was shown that heat transfer characteristics depended on relative density and surface area density. Comparison with metal foams and other heat dissipation media such as packed beds, lattice frame materials, louvered fins, and others suggests that the aluminum WBK competes favorably with the best available heat dissipation media in heat transfer performance.

• Journal of the Korean Society of Physical Medicine
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• v.8 no.2
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• pp.239-243
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• 2013

PURPOSE: The purpose of present study was to investigate effects of obesity, blood pressure and life style on lipid indices and blood pressure in men of age 40s. METHODS: One hundred forty five subjects in men of age 40s were participated in this study. All participants were taken physical examination, lifestyle survey and laboratory test. According to examination, participants were divided into two group in four categories ; obesity and normal group, hypertension and normal group, smokers and non-smokers, and drinkers and non-drinkers. The low density lipoprotein cholesterol (LDL), high density lipoprotein cholesterol (HDL), total cholesterol (TC), triglyceride (TG), systolic blood pressure (SBP), diastolic blood pressure (DBP) were analyzed by independent t-test for comparison between two groups. RESULTS: The values of LDL, TC, SBP, DBP were higher and HDL was lower in obesity than in normal group (p<.05). The values of LDL, TC, SBP, DBP were higher in hypertension group than in normal group (p<.05). The values of TG was higher and HDL was lower in smokers than in non-smokers (p<.05). There's no significant differences between drinkers and non-drinkers (p>.05). CONCLUSION: It can be seen that obesity and blood pressure were more relative risk factors than smoking and alcohol indices in cardiovascular diseases.

• Bulletin of the Korean Chemical Society
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• v.34 no.10
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• pp.2995-3004
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• 2013

The structural, electronic, and optical properties of poly(3-hexylthiophene) (P3HT) have been comprehensively studied by density functional theory (DFT) to rationalize the experimentally observed properties. Rather, we employed periodic boundary conditions (PBC) method to simulate the polymer block, and calculated effective charge mass from the band structure calculation for describing charge transport properties. The simulated results of P3HT are consistent with the experimental results in band gaps, absorption spectra, and effective charge mass. Based on the same calculated methods as P3HT, a series of polymers have been designed on the basis of the two types of building blocks, furofurans and furofurans substituted with cyano (CN) groups, to investigate suitable polymers toward polymer solar cell (PSC) materials. The calculated results reveal that the polymers substituted with CN groups have good structural stability, low-lying FMO energy levels, wide absorption spectra, and smaller effective masses, which are due to their good rigidity and conjugation in comparison with P3HT. Besides, the insertion of CN groups improves the performance of PSC. Synthetically, the designed polymers PFF1 and PFF2 are the champion candidates toward PSC relative to P3HT.

• Journal of Ocean Engineering and Technology
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• v.35 no.4
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• pp.257-265
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• 2021

Many studies have been performed to predict a reliable and accurate stress-range distribution and fatigue damage regarding the Gaussian wide-band stress response due to multi-peak waves and multiple dynamic loads. So far, most of the approximation models provide slightly inaccurate results in comparison with the rain-flow counting method as an exact solution. A step-by-step study was carried out to develop new approximate spectral moments that are close to the rain-flow counting moment, which can be used for the development of a fatigue damage model. Using the special parameters and bandwidth parameters, four kinds of parameter-based combinations were constructed and estimated using the R-squared values from regression analysis. Based on the results, four candidate empirical formulas were determined and compared with the rain-flow counting moment, probability density function, and root mean square (RMS) value for relative distance. The new approximate spectral moments were finally decided through comparison studies of eight response spectra. The new spectral moments presented in this study could play an important role in improving the accuracy of fatigue damage model development. The present study shows that the new approximate moment is a very important variable for the enhancement of Gaussian wide-band fatigue damage assessment.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.35 no.4
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• pp.303-312
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• 2017

This paper indirectly created high density point cloud data using unmanned aerial vehicle image. Then, we tried to suggest new concept of classification technique where particular objects from point cloud data can be selectively classified. For this, we established the classification technique that can be used as search factor in classifying color information in point cloud data. Then, using suggested classification technique, we implemented object classification and analyzed classification accuracy by relative comparison with self-created proof resource. As a result, the possibility of point cloud data classification was observable using the image's information. Furthermore, it was possible to classify particular object's point cloud data in high classification accuracy.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2001.11a
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• pp.193-197
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• 2001

In this paper, reduction characteristics of the ac flashover voltage in the horizontal air gap of sphere-sphere and needle-needle electrode system were investigated when the combustion flame was present near the high-voltage electrodes. The reduction characteristics of ac flashover voltage were discussed with thermal ionization process, the relative air density and the deflection phenomena in the shape of flames that changed by the corona wind and coulomb's force. As the results of an experimental, It was found that the reduction of flashover voltage in sphere-sphere system, in comparison with the no-flame case, are 79.9 [%] for k=0, 82.9 [%] for k=0.5, 87.5 [%] for k=1.0, 85.0 [%] for h=0 [cm], 40.8 [%] for h=5 [cm] and 28.2 [%] for h=9 [cm] when ac voltage is applied.

• Proceedings of the KIEE Conference
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• 2003.04a
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• pp.125-127
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• 2003

Brake forces due to eddy-currents induced by the relative motion of a conductor and a magnetic devices: motors, brakes and magnetically levitated vehicles. In particular, the practicality of using permanent magnet in eddy-current brakes system is obviously recent, due to the manifold improvement in magnet materials and technology. For such a system we give analytical formulas considering eddy-current distribution as variables: flux density for each region and forces.