• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.25 no.1
• /
• pp.108-113
• /
• 2014

This paper presents the influence on the transmission characteristics of swelling in rectangular waveguides for Q-band. We derived the Green's functions of the waveguide with eigenfunction expansion method. The reflection coefficient of the waveguide with a swelling is calculated by using internal impedance in order to investigate the influence of swelling in the waveguide. In order to check the validity of the theoretical analysis, the calculated reflection coefficients are compared with the measured results.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.24 no.7
• /
• pp.722-729
• /
• 2013

This paper presents the influence on the transmission characteristics of dimensional tolerances of rectangular waveguides usually used as a low-loss transmission line in the millimeter-wave band. We derived the Green's functions of the waveguide with eigenfunction expansion method. The reflection coefficient of the waveguide with a post is calculated by using internal impedance in order to investigate the influence of dimensional tolerances of the waveguide. In order to check the validity of the theoretical analysis, the calculated reflection coefficients are compared with the measured results.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
• /
• 2005.11a
• /
• pp.175-178
• /
• 2005

TM plane-wave scattering from finite rectangular grooves in a conducting plane is systematically analyzed with the overlapping T-block method. Multiple rectangular grooves are divided into several overlapping T-blocks to obtain the fast CPU time, CAD applicability, and wide versatility. The scattered fields are obtained in simple closed forms including a fast-convergent integral.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2000.04a
• /
• pp.7-12
• /
• 2000

As the offshore oil fields are moved to the deep ocean, the oil production systems of FPSO(Floating production storage and offloading system) are building these days and so it is the most important to estimate the drift motion and damping effects the drift motion importantly. The components of damping consist of viscous, wave radiation effect and wave drift damping. It is need to estimate the wave drift damping exactly among them. The wave drift damping means the change rate of mean wave drift force with respect to the ship and ocean structures speed. In order to calculate this, the 3-Dimensional panel method used to translating and pulsating Green function is adopted. The calculation is carried out for series 60(CB = 0.7) vessel and the results are compared with other theoretical ones.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
• /
• 2002.11a
• /
• pp.423-433
• /
• 2002

A very fast method of moments(MoM) for the analysis of microstrip structure is considered based upon the use of rooftop basis and razor test functions in conjunction with a new closed-form Green's functions. The present method presents a robust approach to obtain the Green's functions which can be derived by use of only one set of approximation parameters independently of operating frequency range. Moreover, using the present MoM scheme, the MoM matrix elements can be analytically evaluated with few number of terms in comparison with the previous method. So, the computational efficiency can be improved significantly without loss of the precision. In order to check the validity of the present method, performance is demonstrated for the example of a coaxially-fed microstrip transmission line and the present results are compared with the previous results.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2011.04a
• /
• pp.493-498
• /
• 2011

구름접촉피로는 차륜과 레일의 반복적인 접촉으로 인하여 발생하는 표면손상현상으로 점차 증가하는 레일손상 중 하나이다. 접촉마모 및 주기적 그라인딩보다 균열의 성장속도가 더 빨라 균열진전이 시작되는 최소균열크기(minimum crack size for growth)는 레일의 파괴방지 및 유효한 유지보수전략을 수립하는데 기초자료로 활용된다. 본 연구에서는 최소균열크기를 예측하기 위하여 차륜레일의 접촉에 영향을 미치는 주요 파라미터를 변화시키면서 최소균열크기의 변화를 살펴보았다. 이를 위하여 Fletcher와 Kapoor의 "2.5D"모델을 적용한 시뮬레이션 소프트웨어를 개발하였으며, 최대접촉하중(1174MPa), 표면마찰계수(0.1, 0.2, 0.3 and 0.4), 잔류응력, 접촉에 의한 표면마모(1.0nm/cycle), 그라인딩량(0.3mm/10MGT)을 파라미터로 하여 해석을 수행하였다. 해석결과 최소균열크기는 해석조건에 따라 1.41-1.95mm로 계산되었다.

• Journal of Ocean Engineering and Technology
• /
• v.14 no.4
• /
• pp.17-22
• /
• 2000

As the offshore oil fields are moved to the deep ocean, the oil production system of FPSO(Floating Production Storage and Offloading System) Type are constructed frequently these days. So, it is very important to estimate the drift motion and damping effects due to the drift motion simultaneously. The components of slow drift motion damping consist of viscous, wave radiation effect and wave drift damping. It is needed to estimate the wave drift damping more accurately than others. The wave drift damping signifies the time-rate of mean wave drift force on oscillating ship or ocean structure which constant speed. In order to calculate this, the 3-Dimensional panel method is employed with the translating and pulsating Green function in the frequency domain. The calculation is carried out for a Series 60 ($C_B$/=0.7) and the results are compared with other numerical ones.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.13 no.1
• /
• pp.26-32
• /
• 2002

When a spatial method of moments(MoM) is used in conjunction with closed-form Greens functions for the analysis of a general microstrip structures of thin or thick substrate, an efficient technique fur the evaluation of MeM off-diagonal matrix elements as well as diagonal elements is proposed. In order to check the validity of the present method, performance is demonstrated for the example of a coaxially-fed microstrip antenna and the present results are compared with the previous results.

• Proceedings of the Korea Contents Association Conference
• /
• 2008.05a
• /
• pp.543-546
• /
• 2008

A genetic algorithm is introduced to design a waveguide filter which is one of essential elements of satellite system. The waveguide filter composed of waveguide steps is analyzed based on the Green's function and mode-matching technique. Genetic optimization for a waveguide filter is performed in terms of each parameter. Insertion loss behaviors versus frequency are computed and compared with measurement results.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.21 no.3
• /
• pp.378-384
• /
• 1997

In curing process of tire, contact and slip occurs between green tire and curing bladder. The curing process is a critical step in the manufacture of tires. In this investigation, curing bladder shaping is examined using a finite element method. Specifically, a finite element model between the inner part of green tire and the outer part of curing bladder is generated using contact element and curing bladder is generated using incompressible element. Numerical analysis are performed on two different bladder types, different overall outer diameters of curing bladder and different heights of curing bladder. Numerical results show that contact pressure is increased by using toroidal type of curing bladder, increasing overall diameter and increasing height of curing bladder. To obtain natural equilibrium carcass line, there is a requirement in increasing contact pressure of the section between side and bead.