• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1603-1604
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• 2006

본 논문은 구멍(aperture)이 나있는 육면체 진기에 전자파가 조사 되었을 때, 공진기 내부에 침투한 전자파를 Modal MoM 수치계산법을 이용하여 추정하였다. 공진기 내부의 전자파는 cavity Green 함수로, 외부는 자유 공간 Green 함수로 표현 할 수 있고, 구멍이 난 부분에서 전계와 자계의 접선 성분이 연속하다는 경계조건을 이용하여, 차폐하고자 하는 도체공간 내부에 침투한 전자파를 알 수 있다.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.05a
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• pp.241-248
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• 2004

In general, the salient features if the floating breakwater have excellent regulation of sea-water keeping the marine a1ways clean, up and dorm free movement with the incoming and outgoing tides, capable of being installed without considering the geological condition of sea-bed at any water depth, This study discusses the three dimensional wave transformation of the floating breakwater moored by catenary. Numerical method is based at the Green function method and eigenfunction expansion method. The validity of the present is confirmed by comparing it with the result of Ijima et a1.(1975) fer tensile maxed floating breakwater. According to the numerical results, drift and width of the floating breakwater affect at the wave transformation greatly, and incident wave of long period is well transmitted to the rear of the floating breakwater.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.8
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• pp.1059-1068
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• 1993

We will put the emphasis on the analysis of arbitrarily shaped microstrip antennas. The most general and rigorous treatment of microstrip antennas is given by the electric field integral equation(EFIE), usally formulated in the spectral domain. In this paper, we use a modification of EFIE, called the mixed potential integral equation(MPIE) , and we solve it in the space domain. This technique uses Green's functions associated with the scalar and vector potential which are calculated by using stratified media theory and are expressed as Sommerfeld integrals. The integral equation is solved by a moment's method using rooftop subsectional basis function. Thus, microstrip patches of any shape can be analysed at any frequency and for any substrate. Numerical results for a rectangular patch and for a L-shaped patch are given and compared with measured values.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.7 no.4
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• pp.38-43
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• 2011

For the efficient and safe operation of nuclear power plant, evaluating quantitatively aging phenomenon of major components is necessary. Especially, typical aging parameters such as stresses and cumulative usage factors should be determined accurately to manage the lifetime of the plant facility. The 3-D finite element(FE) model is generated to calculate the aging parameters. Mechanical and thermal transfer functions called Green's functions are developed for the FE model with standard step input. The stress results estimated from transfer functions are verified by comparing with 3-D FE analyses results. Lastly, we suggest an effective fatigue evaluation methodology by using the transfer functions. The usefulness of the proposed fatigue evaluation methodology can be maximized by combining it with an on-line monitoring system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.1
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• pp.60-67
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• 2004

In this paper, a rectangular ring microstrip patch antenna has been analyzed by using desegmentation method and evaluation impedance matrices from Green's functions fur rectangular segment and desegmentation method for analysis of planar electro-magnetic structures is discussed. As the rectangular ring cavity could be seen as a structure subtracted a small rectangular cavity from a large one, the overall impedance matrix was obtained by applying a multiport connection method to the individual impedance matrices expressed as a term of Green's function fer rectangular segment. The electromagnetic fields can be solved from a vector potential which is satisfied it's eight boundary conditions. The electric field distribution at each edges was expressed as a histogram table with exciting modes. These results can be used to analyze the operational modes for a rectangular ring microstrip antennas.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.10
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• pp.1720-1725
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• 2004

Absorption characteristics of green tea powder were investigated. The monolayer moisture content determined by GAB equation was 0.024~0.052 g $H_2O$/g dry solid. The absorption enthalpy was calculated with different particle size and various water activities. It showed that the absorption energy was decreased with increasing water activity but no difference was found on particle size increasement. Among models applied for predicting equilibrium moisture content, Halsey model was the best fit model for green tea powders, showing the lowest prediction deviation of 2.1~4.0%. The prediction model equations for the water activity was established as function of relative humidity, time and temperature. The model equation will be helpful for future work on drying and storage of green tea powder.

• Journal of the Korean Society for Marine Environment & Energy
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• v.10 no.3
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• pp.173-180
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• 2007

Oscillating wave amplitude in a bottom-mounted OWC chamber designed for wave energy converter is investigated by applying characteristic wave conditions in Korean coastal water. The effects of shape parameters of OWC chamber in a view of wave energy absorbing capability are analyzed. Both experimental and numerical approaches are adopted and their results are compared to optimize the shape parameters which can result in a maximum power production under given wave distribution. The experiment was carried out in a wave flume under 2-D assumption of OWC chamber. The numerical scheme employed a hybrid Green integral equation which adopts the Rankine Green function inside chamber to take account of fluctuating air pressure, while it uses the Kelvin Green function in outer domain. Air duct diameter, chamber width, and submerged depths of front skirt and back wall of chamber changes the magnitude and peak frequency of wave absorption significantly.

• Journal of Korea Foresty Energy
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• v.22 no.1
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• pp.1-7
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• 2003

The purpose of this study was to investigate variabilities in green moisture content, specific gravity and shrinkage in the stems of a Larch(Larix leptolepis) to provide fundamental information for technical processes. There were significant differences in green moisture contents, specific gravity and shrinkage between heratwood and sapwood. The green moisture content was correlated negatively with the height in the sapwood. On the other hands, in the heratwood, there was a positive correlation between moisture content and the height. There were no significant differences in specific gravity between south-bound and north-bound directions in both heartwood and sapwood. There were no significant differences in specific gravity due to the height in sapwood, but significant differences were foundin heartwood. There were no significant differences in shrinkage between south-bound and north-bound directions, and due to the height in most of heartwood and sapwood. However, shrinkage in north-bound direction was higher than that of in the south-bound direction in some sapwoods.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.24 no.5
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• pp.535-540
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• 2015

We propose an enhanced Green's function approach to predict thermal stresses by considering temperature-dependent material properties. We introduce three correction factors for the maximum stress, the time taken to reach maximum stress, and the time required to attain steady state based on the Green's function results for each temperature. The proposed approach considers temperature-dependent material properties using correction factors, which are defined as polynomial expressions with respect to temperatures based on Green's functions, that we obtain from finite-element (FE) analyses at each temperature. We verify the proposed approach by performing detailed FE analyses on thermal transients. The Green's functions predicted by the proposed approach are in good agreement with those obtained from FE analyses for all temperatures. Moreover, the thermal stresses predicted using the proposed approach are also in good agreement with the FE results, and the proposed approach provides better predictions than the conventional Green's function approach using constant, time-independent material properties.

• Journal of the Society of Naval Architects of Korea
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• v.47 no.2
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• pp.188-195
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• 2010

Green water load is an important parameter to be considered in designing a modern ship or offshore structures like FPSO and FSRU. In this research, a numerical simulation method for green water phenomenon is introduced. The Navier-Stokes equations and the continuity equation are used as governing equations. The equations are calculated using Finite Difference Method(FDM) in rectangular staggered grid system. To increase the numerical accuracy near the body, the Cartesian cut cell method is employed. The nonlinear free-surface during green water incident is defined by Marker-density method. The green waters on a box in regular waves are simulated. The simulation results are compared with other experimental and computational results for verification. To check the applicability to moving ship, the green water of the ship which is towed by uniform force in regular wave, is simulated. The ship is set free to heave and to surge.