• Proceedings of the Acoustical Society of Korea Conference
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• autumn
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• pp.327-330
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• 2004

파워흐름해석법은 진동에너지 흐름 형태에 따른 에너지지배방정식을 이용하는 방법으로서, 진동에너지의 공간적인 분포와 전달 경로 등을 제시할 수 있는 방법이다. 이러한 파워흐름해석법은 고주파수 대역의 진동을 해석하기 위하여 효과적으로 적용될 수 있다. 본 연구에 서는 평판 구조물 진동에 대한 파워흐름해석법의 예측 결과를 실험 결과와 비교하여 분석하였다. 분석할 진동 특성들은 손실계수, 주파수 응답함수 등을 포함한다. 그리고 이러한 분석 결과로부터 파워흐름해석법이 고주파수 진동에 효과적으로 적용될 수 있음을 보였다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.36 no.5
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• pp.331-338
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• 2023

Modern bulletproof armor must be light and have excellent penetration resistance to ensure the mobility and safety of soldiers and military vehicles. The ballistic performance of heterogeneous structures of laminated flat plates as bulletproof armor depends on the arrangement of constituent materials for the same weight. In this study, we analyze bulletproof performance according to the stacking sequence of laminated bulletproof armor composed of Kevlar, ultra-high molecular weight polyethylene, and ethylene-vinyl-acetate foam. A ballistic analysis was performed by colliding a 7.62 × 51 mm NATO cartridge's M80 bullet at a speed of 856 m/s with six lamination arrangements with constituent materials thicknesses of 5 mm and 6.5 mm. To evaluate the bulletproof performance, the residual speed and residual energy of the projectile that penetrated the heterogeneous laminated flat plates were measured. Simulation results confirmed that the laminated structure with a stacking sequence of Kevlar, ultra-high molecular weight polyethylene, and ethylene-vinyl-acetate foam had the best bulletproof performance for the same weight.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.11
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• pp.2136-2149
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• 1992

The natural convection from an inclined ice flat plate immersed in cold water near its density maximum is studied numerically. Finite difference analysis has been performed for the heat and momentum transfer with respect to various inclined angles and ambient water temperatures. The results of the analysis are presented for ambient water temperatures, 1.0deg. C. leq. T／sub .inf.／.leq. 15.0deg. C and the inclined anales from 0deg to 60deg. They include velocity profiles, temperature profiles, melting velocities, and mean Nusselt numbers for entire flow fields, Generally, in the range of 0deg. C .leq.theta. .leq. 60.deg. C, the results show three distinct flow regimes, In the range of 1.0 deg. C .leq. T／sub .inf.／ .leq. 4.6 .deg. C, the greatest mean Nuselt number exists about 3.0deg. C. In the range of 5.7deg. C .leq. T／sub .inf.／ .leq. 15.0deg. C, mean Nuselt number increases as ambient water temperature increases. Also, the mean Nuselt number decreases as the inclined angle increases. This theoretical results are compared with previous experimental ones and multiple steady state ones.

• The Journal of Engineering Geology
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• v.15 no.4 s.42
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• pp.423-433
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• 2005

For the design of spread foundation and the stability evaluation, we compared and analyzed it for theoretical, empirical bearing capacity formulas, and various settlement computation formulas, by conducting the plate bearing test at the site of A and B, which consisted of gneiss weathered soil. In addition, we considered the effective method of stability evaluation by carrying out the plate bearing test carried out on the ground consisted of weathering soil of gneiss. Consequently, it was found out that the allowablebearing capacity by the theoretical formula of Terzaghi was too excessive in comparison with the result of the plate bearing test and the Terzaghi-Peck method, which was used widely domestically in designing the spread foundation. It was more effective for a stable design. As a result of the plate bearing test carried out, on the ground consisted of weathering soil. It was found that reviewing the stability by the bearing capacity calculated with load-settlement curve. It is evaluated in a safer side than the point of view of the settlement.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.5
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• pp.1059-1068
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• 1990

The minimum weight design for the simply-supported eccentrically stiffened plates subjected to combined loads is studied according to the stiffening configuration. The optimal programming is accomplished by formulating the design requirements in terms of a mathematical programming problem, and by using the gradient projection algorithm. The Huber type equilibrium equation is used as the governing equation for the overall buckling. The overall buckling of stiffened plates and the local buckling of the unstiffened plate between stiffeners and the stiffeners themselves are used as behavior constraints. Results of design examples for the orthogonally stiffening case compared with those of the other study support that the present study is feasible. Design examples for the symmetrically oblique stiffening case are presented and the results indicate that a significant improvement in design efficiency may be achieved through symmetrically oblique stiffening compared to the orthogonal stiffening under the combined loading condition.

• The KIPS Transactions:PartC
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• v.16C no.2
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• pp.143-150
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• 2009

In trust-based networks, it is very important how to decide a node is trustworthy when one node performs communications with other node. In current networks based on trust, a node creates a new trust value from observation and then establishes an intercommunication path through the process of evaluating a targeted communication node. In our paper, we propose four trust models in which a new node enters a cluster and finds a target node to create a communication in ad-hoc networks. The proposed models have been classified according to the existence of reputation server and the trust evaluation functions. Through the proposed model, we found that new node finds target node more quickly in which there exists a reputation server in the cluster and considers neighbor node's recommendation as well as own experience information when calculates trust values. As our performance analysis, we focus the communication delay time to generate a final trust value for each trust model.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.4
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• pp.74-80
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• 2003

Ionic wind is produced by a corona discharge when a DC high voltage is applied across the point-to-plane gap geometry. The corona discharge phenomena have been investigated in several beneficial application fields such as electrostatic cooling, ozone generation, electrostatic precipitation and electrostatic spraying. Recently ionic wind might be used in aerodynamic, for example, heat transfer, airflow modification, and etc. In this work, in order to analyze the control behavior of the velocity and amount of ionic wind produced by the positive DC corona discharges. The ionic wind velocity was measured as a function of the applied voltage, diameter of the punched hole on plate electrode and separation between the point-to-plate electrodes. As a results, the airflow is generated from the tip of needle to the plate electrode in the needle-to-punched-plate electrode systems. The ionic wind velocity is linearly increased with an increase in applied voltage and ranges from 1 to 3 m/sec at the locations of 100-200 mm from the punched-plate.

• Culinary science and hospitality research
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• v.22 no.4
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• pp.240-253
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• 2016

This study was undertaken to better understand the professional recognition of the food service industry of college students in food service realted majors based on characteristics of the respondents In order to achieve the purpose of the study, 211 questionnaire surveys were colelcted in the period from May 19 to May 30, 2014. The study conducted regression analysis by using SPSS Win18.0 package, for frequency analysis, exploratory factor analysis, analysis of reliability, correlation analysis tests, t-test, andone way ANOVA. Measure of occupation self-esteem, positive values, social reputation, negatively handled, relatively effectively configuration, each construct was to ensure reliable and statistically significant relevance. The results were analyzed by the difference factor of occupation self-esteem according to demographic characteristics, depending on gender, has confirmed that the perceived social reputation in a different way, depending on the differences in grade, to verify that you are aware of the positive values in a different way. Also Department has been analyzed with the degree of cognitive differ for positive values and negative treatment in accordance with, understand that it perceives the relative effects and negative treatment in accordance with the future desired profession in a different way. This suggests that there is a need to find ways to satisfaction and career decision level of major occupational self-esteem is high is to raise the occupational self-esteem major of food service industry college students based on the results of previous research get higher. In particular, I would like to emphasize that there is a need provide a substantial improvement on the negative treatment and the most negative recognize and social reputation is for the work of the food service industry.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.6
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• pp.43-50
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• 2010

In this paper, we analyzed radiated emission generated by the split power/ground plane structures in order to reduce EMI in system modules. The magnetic fields and electric fields were simulated and measured on the test boards under various conditions. In order to reduce radiated emission, we have to determine spacing and location of the split ground gap so that input signal frequency does not coincide with the resonance frequency of the split power/ground plane structure and the phase of reflection coefficient is close to $0^{\circ}$ at input signal frequency. Moreover, we found that inserting a stitching capacitor could reduce the radiated emission. Low magnitude of reflection coefficient and the phase close to $0^{\circ}$ are required to reduce radiated emission. It is necessary to properly decide value and location of a stitching capacitor to fulfil those requirements.

• Journal of Food Hygiene and Safety
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• v.38 no.3
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• pp.170-175
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• 2023

In this study, the effect of MnSO₄ on the insecticidal crystal (IC) produced by Bacillus thuringiensis for a rapid detection medium was analyzed. The strains used included one B. thuringiensis reference (KCTC 1511) and nine wild-type strains. The IC in B. thuringiensis was detected following the method published by the Ministry of Food and Drug Safety in Korea. In the nutrient agar to which 0.005% MnSO₄ was added, IC was observed on two of the three plates after 48 hours of incubation and on all three plates after 120 hours. In AK agar, IC was observed on one and two of the three plates after 48 and 96 hours of incubation, respectively. These results indicated that 0.005% MnSO₄ nutrient agar is more appropriate than AK agar for production of IC in B. thuringiensis. The effect of various MnSO₄ concentrations on IC production was studied after 24 hours of incubation. IC was produced on 1 of the 10 plates with 0.000% MnSO₄ nutrient agar, 2 of the 10 plates with 0.001% MnSO₄ nutrient agar, and 3 of the 10 plates with 0.002% MnSO₄ nutrient agar. IC was not observed for the other nutrient agars containing 0.003%-0.009% MnSO₄. These results indicated that nutrient agar with 0.002% MnSO₄ led to the most rapid production of IC by B. thuringiensis after 24 hours of incubation. However, the conditions for IC production by B. thuringiensis depended on the incubation conditions and strain activity. Therefore, further studies are needed to verify the effects of 0.002% MnSO₄ on the production of IC by various Bacillus thuringiensis strains.