• Journal of electromagnetic engineering and science
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• 제17권2호
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• pp.91-97
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• 2017

An accurate and efficient evaluation for hypersingular integrals (HIs), strongly singular integrals (SSIs), and weakly singular integrals (WSIs) plays an essential role in the numerical solutions of 3D electromagnetic scattering problems. We derive analytic formulas for WSIs based on Stokes' theorem, which can be expressed in elementary functions. Several numerical examples are presented to validate these analytic formulas. Then, to show the feasibility of the proposed formulations for numerical methods, these formulations are used with the existing analytical expressions of HIs and SSIs to correct the near-field interaction in an iterative physical optics (IPO) scheme. Using IPO, the scattering caused by a dihedral reflector is analyzed and compared with the results of the method of moments and measurement data.

• Molecules and Cells
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• 제28권5호
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• pp.441-446
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• 2009

During epididymal transit, mammalian sperm acquire selected proteins secreted by the epididymis. We previously showed that a disintegrin and metalloprotease (ADAM) 7 is expressed specifically in the epididymis and transferred to the sperm surface during epididymal transit. Here, we show that mouse ADAM7 secreted to the epididymal lumen is associated with membranous vesicles known as epididymosomes. Furthermore, we found that ADAM7 can be transferred directly from epididymal vesicles to sperm and that it is an integral plasma membrane protein in sperm. Thus, our study provides new information regarding the unique mode of secretion and interaction of ADAM7 during the epididymis-to-sperm transfer process.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제24권3호
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• pp.293-303
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• 2020

The present work aims to analyzed the transient thermoelastic stress analysis of a thin circular plate with uniform internal heat generation. Initially, the plate is characterized by a parabolic temperature distribution along the z-direction given by T = T₀(r, z) and perfectly insulated at the ends z = 0 and z = h. For times t > 0, the surface r = a is subjected to convection heat transfer with convection coefficient h_c and fluid temperature T_∞. The integral transform method used to obtain the analytical solution for temperature, displacement, and thermal stresses. The associated thermoelastic field is analyzed by making use of the temperature and thermoelastic displacement potential function. Numerical results are carried out with the help of computational software PTC Mathcad Prime-3.1 and shown in figures.

• 대한수학회보
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• 제53권2호
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• pp.531-540
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• 2016

In this work, we introduce the complete Riemannian manifold $\mathbb{F}_3$ which is a three-dimensional real vector space endowed with a conformally flat metric that is a solution of the Einstein equation. We obtain a second order nonlinear ordinary differential equation that characterizes the helicoidal minimal surfaces in $\mathbb{F}_3$. We show that the helicoid is a complete minimal surface in $\mathbb{F}_3$. Moreover we obtain a local solution of this differential equation which is a two-parameter family of functions ${\lambda}_h,K_2$ explicitly given by an integral and defined on an open interval. Consequently, we show that the helicoidal motion applied on the curve defined from ${\lambda}_h,K_2$ gives a two-parameter family of helicoidal minimal surfaces in $\mathbb{F}_3$.

• 대한수학회논문집
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• 제30권4호
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• pp.505-513
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• 2015

The present paper deals with the determination of displacement and thermal stresses in a semi-infinite circular cylinder defined as $0{\leq}r{\leq}b$, $0{\leq}z<{\infty}$, due to internal heat generation within it. A circular cylinder is considered having arbitrary initial temperature and subjected to time dependent heat flux at the fixed circular boundary (r = b) whereas the zero temperature at the lower surface (z = 0) of the semi-infinite circular cylinder. The governing heat conduction equation has been solved by using integral transform method. The results are obtained in series form in terms of Bessel functions. The results for displacement and stresses have been computed numerically and illustrated graphically.

• 대한조선학회지
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• 제24권2호
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• pp.1-10
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• 1987

The wave resistance of ships is calculated with the numerical solution of the Newmann-Kelvin problem. For the sake of the numerical evaluation of the Green function, Shen and Farell's method is used[7]. In particular, the contribution of the line integral term in the Neumann-Kelvin problem to the calculated values of the wave resistance is shown. For the Wigley's hull the calculated values of the wave resistance and the wave profiles at the hull surface are in fairly good agreement with the experimental data. However, for the series 60 hull and the practical hull, a 454,000 cubic feet reefer vessel, the calculated results of the wave resistance show definte hollows and humps considering the experimental result.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제26권1호
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• pp.67-75
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• 2022

Analysis of non-integer order thermoelastic temperature distribution and it's thermal deflection of thin hollow circular disk under the axi-symmetric heat supply is investigated. Initially, the disk is kept at zero temperature. For t > 0 the parametric surfaces are thermally insulated and axi-symmetric heat supply on the thickness of the disk. The governing heat conduction equation has been solved by integral transform technique, including Mittag-Leffler function. The results have been computed numerically and illustrated graphically with the help of PTC-Mathcad.

• 대한설비공학회지:설비저널
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• 제3권3호
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• pp.185-190
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• 1974

Floor panel heating system is popular in Korea as dwelling house heating system. There are two methods for keeping floor surface warm. One method is delivering warm air under the floor such as Roman Hypocaust and Korean traditional Ondol. The other method is imbedding hot water pipes into the concrete floor slab. This paper gives basic equations for steady and transient solutions of heat conduction from hurried pipes. For steady-state solution, fin Efficiency Method and Sink and Source Method were introduced. Sink and Source Method is applied to transient state and basic solution is given in the form of Exponential Integral Function. Numerical solutions can be solved easily by digital computer from these equations.

• 한국건설순환자원학회논문집
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• 제11권4호
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• pp.535-541
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• 2023

Friction material, an integral constituent of bearing supports, facilitates frictional interactions between two components. Polytetrafluoroethylene (PTFE), a commonly employed friction material in bearing supports, has assessed resultant friction equilibrium. Nonetheless, protracted utilization diminishes frictional performance as the lubricating agent is progressively depleted. Friction materials can affect the entire structural system. Hence, this study applied ceramic material as a friction material due to its high strength, low friction, and low deformation. The frictional behavior was investigated using a cyclic friction test, considering various friction materials as the primary design variables and examining their covariance in cyclic frictional movements. The results substantiated that the ceramic friction material yielded a low variance and friction coefficients in cyclic frictional movements.

• 한국안광학회지
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• 제13권4호
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• pp.75-81
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• 2008

목적: 직경 2 m급 반사면을 가지는 태양열 집광 장치를 개발하고자 한다. 방법: 태양열 집광 장치 반사면 제작을 위해서는 제작에 사용될 반사판 섹터의 형상이 필요한데 먼저 이 형상을 도출할 수 있는 공식을 유도하였다. 반사경 외형 직경, 근축영역에서의 반사경 곡률반경, 반사경 섹터의 개수, 반사경 중심 홀의 크기, 출력 데이터의 간격을 입력 변수로 하여 반사면 섹터의 형상과 수치 데이터를 상기 공식으로 도출하는 프로그램을 델파이 6.0 언어를 사용하여 개발하였다. 결과: 반사면 섹터의 형상과 수치 데이터를 도출하기 위해 개발된 프로그램은 반사면 섹터의 형상을 모니터에 나타낼 수 있도록 하였으며, 형상에 대한 수치 데이터 파일을 저장할 수 있도록 하였다. 따라서 이 프로그램 사용자는 반사면 섹터의 수치 데이터를 쉽게 다룰 수 있게 되었다. 결론: 태양열 집광 장치 반사면 제작에 사용되는 반사면 섹터를 만들어내는 프로그램을 개발하여 실제 직경 2m급 태양열 집광장치 개발에 적용하여 시제품 제작에 성공하였다.