• Journal of the Computational Structural Engineering Institute of Korea
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• v.31 no.2
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• pp.71-78
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• 2018

This paper presents the assembling of multiple patches based on the single patch isogeometric formulation for the shear deformable shell element given in the previous study. The geometrically exact shell formulation has been accomplished with the shell theory based formulation and the generalized curvilinear coordinate system directly derived from the given NURBS geometry. For the knot elements matching across adjacent surfaces, the zero-th and first parametric continuity conditions are considered and the corresponding coupling constraints are implemented by a master-slave formulation between adjacent patches. The constraints are then enforced by a substitution method for condensation of the slave variables, thereby reducing the model size. Through numerical investigations, the important features of the first parametric continuity condition are confirmed. The performance of the multi-patch shell models is also examined comparing the rate of convergence of response coefficients for the zero and first order continuity conditions and continuity in coupling boundary between two patches is confirmed.

• Proceedings of the KIPE Conference
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• 2013.11a
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• pp.97-98
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• 2013

본 논문에서는 2차 측에 Current-Doubler 정류방식을 적용한 LLC 직렬 공진 컨버터를 제시한다. 일반적으로 LLC 직렬 공진 컨버터에 경우 2차 측에는 유도 성 부하를 사용하지 않는다. 2차 측에 유도 성 부하가 존재하는 경우 방식이 바뀌게 되어, 이는 더 이상 LLC 직렬 공진 컨버터의 특성을 갖지 않기 때문이다. 제안하는 논문에서는 2차 측 출력 인덕터를 Common Mode Choke로 구성한 회로를 수학적인 해석을 통해 증명하고, 이를 바탕으로 Matlab / Simulink를 이용하여 타당성을 검증 한다.

• Journal of Korea Water Resources Association
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• v.34 no.6
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• pp.651-657
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• 2001

The second-order long waves generated by short wave groups propagating over a step are theoretically investigated. The diffraction of short waves is firstly formulated and the governing equations of second-order long waves are then derived by using a multiple-scale perturbation method. It is observed that free and locked long waves are generated and propagated with different velocities.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.6
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• pp.813-823
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• 1998

This paper analyzed the circularly polarized conformal microstrip patch antennal using the unsplit anisotropic perfectly matched layer(UAPML) method. Also, this paper are treated effectively the edge and corner parts on the 3 dimensional UAPML. Especially, to analyze microstrip patch antennas with the coaxial feeder line, it was applied to mixed the UAPML with Mur's first order absorbing boundary condition. Therefore this paper suggest the new the method to mix the UAPML with Mur's first order absorbing boundary condition. The results show the time responses of electromagnetics $E_z$ and $H\chi'$, input impedances of coaxial cable and radiation patterns of strip parchs on the single and the array patchs with central frequencies 1.575 GHz, 1.778 GHz and 4.8 GHz in L-band and C-band for mobile communication. The results of this paper shows that its results was compared the Mur's first order abc and mixed the second order dispersion boundary condition(SDBC) with the Mur's first order absorbing boundary condition. In accordance with, the validity of the method is confirmed.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.30 no.5
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• pp.207-216
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• 2018

This research compared and analyzed safety ratio of slope with Talren97 and SoilWorks based on limit equilibrium analysis and Midas GTS based on finite element analysis. For the analysis variables, there are slope height, berm condition, soil parameter, groundwater level, slope inclination. All of slope stability analysis were performed by dividing into dry season and rainy season. As the result of the analysis of Talren97 and SoilWorks based on same theory, safety ratio of slope shows same value, so there was no difference between the programs. In comparison with limit equilibrium analysis, the result of finite element analysis showed somewhat high ratio of safety and it was higher by about 2.4% averagely. The difference between the result of limit equilibrium analysis and that of finite element analysis is in the range which can ignored in practical work.

• Journal of the Korea Concrete Institute
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• v.28 no.6
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• pp.655-663
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• 2016

The present study shows the moment-average curvature relationship and effective inertia moment of RC beams obtained from the nonlinear analysis based on the parabola-rectangular stress-strain curve defined in EC-2 code. The variables examined are concrete strength and steel ratio, and moment-average curvature relationship and effective inertia moment obtained are compared with those of the current KCI provisions. As the results of the comparison, the followings could be said: Since the KCI provisions(the Branson method) were originally derived based on the experimental data ranged from 2.2 to 4 of $M/M_{cr}$ and 1.3 to 3.5 of $I_{ut}/I_{cr}$, thereby within these ranges the inertia moments obtained from the nonlinear analysis are closely agreed with those predicted by the Branson method. However, beyond those range the remarkable difference could be found between the two results. In particular, for beams having low steel ratio the inertia moment resulted from the nonlinear analysis are significantly smaller than those obtained from the KCI(Branson) method. This result may imply that the deflection of lightly reinforced members, such as slabs in buildings, becomes much larger than those calculated according to the current design provisions.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2003.05b
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• pp.191-192
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• 2003

본 연구는 서울을 중심으로 한 수도권지역에서 해륙풍과 주풍 및 계절풍을 고려하여 대기오염 측정소가 있는 지점을 중심으로 강화도 석모리, 인천 용현동, 서울 불광동, 정동, 전농동, 방이동지점과 양평 국수리지점을 측정장소로 선정하여 미세먼지 분야의 측정자료를 해석한 것으로 1차 측정은 2002년 8월 5일 ∼8월 22일, 2차 측정은 2002년 10월 10일 ∼ 10월 18일까지 실시 되었으며, 3차 측정은 2003년 1월 10일∼l월 24일까지 겨울 집중 측정이 실시되었으며, 측정결과를 해석중에 있다. 또, 4차 측정은 2003년6월에 실시될 예정이다. (중략)

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.8 no.2
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• pp.208-218
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• 1996

Performance of a VM heat pump is considerably affected by various losses, such as enthalpy dump, reheat loss, pumping loss, conduction loss and shuttle loss. A second-order analysis model of VM heat pumps, which allows consideration of the major losses, was presented. Actual heat transfer rates for heat exchangers were calculated from the heat transfer rates obtained by the adiabatic analysis and various losses. New effective temperatures of heat exchangers were calculated from the actual heat transfer rates and the mean heat transfer coefficients until there was no appreciable change in the effective temperatures. Effects of design parameters, such as phase angle, swept volume ratio, regenerator length and speed on heating capacity, cooling capacity and COP were shown.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.6
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• pp.77-82
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• 1999

대형 화물트럭의 차실 내에 높은 수준의 차바닥 진동을 수반한 높은 소음이 발생하였다. 측정 및 분석결과 문제의 진동 소음은 추진축의 회전 1차 및 2차 성분으로 나타났다. 진동 전달경로상의 구성계 및 구성요소들에 대해 모드해석과 실차 주행 모드 해석시험을 실시한 결과 드라이브라인 및 프레임의 공진주파수가 문제가 되는 소음진동 주파수와 거의 일치하였으며, 또한 캡의 실내음향 공진 모드가 문제되는 주파수에서 존재하였다. 실험결과에 따라 액슬과 액슬간의 축의 장착각도를 변경하여 가진력을 줄이고, 비틀림 동흡진기를 추진축에 장착하여 드라이브라인계 공진을 제어함으로써 문제의 시내진동소음을 현저히 개선하였다.

• Journal of the Korean Society of Propulsion Engineers
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• v.5 no.1
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• pp.18-25
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• 2001

The results of systematic numerical experiments of secondary gas injection thrust vector control are presented. The effects of secondary injection system such as injection location and nozzle divergent cone angle onto the overall performance parameters such as thrust ratio, specific impulse ratio and axial thrust augmentation, are investigated. Complex nozzle exhaust flows induced by the secondary jet penetration is numerically analyzed by solving unsteady three-dimensional Reynolds-averaged Navier-Stokes equations with Baldwin-Lomax turbulence model for closure. Numerical simulations compared with the experiments of secondary air injection into the rocket nozzle of $9.6^{\cire}$ divergent half angle showed good agreement. The results obtained in terms of overall performance parameters showed that locating the secondary injection orifice further downstream of primary nozzle ensures the prevention of occurrence of reflected shock wave, therefore is suitable for efficient and stable thrust vectoring over a wide range of use.