• Journal of Theoretical and Applied Mechanics
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• 제1권1호
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• pp.69-88
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• 1995

The paper attempts to estimate the incubation time of a cavity in the interface between a power law creep particle and an elastic matrix subjected to a uniaxial stress. Since the power law creep particle is time dependent, the stresses in the interface relax. Through previous stress analysis related to the present physical model, the relaxation time is defined by ${\alpha}$2 which satisfies the equation $\Gamma$0 ｜1+${\alpha}$2k｜m=1-${\alpha}$2 [19]. $\Gamma$0=2(1/√3)1+m($\sigma$$\infty$/2${\mu}$)m($\sigma$0/$\sigma$$\infty$tm) where $\sigma$$\infty$ is an applied stress, ${\mu}$ is a shear modulus of a matrix, $\sigma$$\infty$ is a material constant of a power law particle, $\sigma$=$\sigma$0 $\varepsilon$ and t elapsed time. the volume free energy associated with Helmholtz free energy includes strain energies associated with Helmholtz free energy includes strain energies caused by applied stress anddislocations piled up in interface (DPI). The energy due to DPI is found by modifying the results of Dundurs and Mura[20]. The volume free energies caused by both applied stress and DPI are a function of the cavity size(${\gamma}$) and elapsed time(t) and arise from stress relaxation in the interface. Critical radius ${\gamma}$ and incubation time t to maximize Helmholtz free energy is found in present analysis. Also, kinetics of cavity fourmation are investigated using the results obtained by Riede[16]. The incubation time is defied in the analysis as the time required to satisfy both the thermodynamic and kinetic conditions. Through the analysis it is found that [1] strain energy caused by the applied stress does not contribute significantly to the thermodynamic and kinetic conditions of a cavity formation, 2) in order to satisfy both thermodynamic and kinetic conditions, critical radius ${\gamma}$ decreases or holds constant with increase of time until the kinetic condition(eq.40) is satisfied. Therefore the cavity may not grow right after it is formed, as postulated by Harris[11], and Ishida and Mclean[12], 3) the effects of strain rate exponent (m), material constant $\sigma$0, volume fraction of the particle to matrix(f) and particle size on the incubation time are estimated using material constants of the copper as matrix.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2005년도 춘계학술발표회
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• pp.177-178
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• 2005

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2005년도 춘계학술발표회
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• pp.1052-1053
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• 2005

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2005년도 춘계학술발표회
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• pp.305-306
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• 2005

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2017년도 추계학술논문요약집
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• pp.347-348
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• 2017

• 한국자기학회지
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• 제16권2호
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• pp.130-135
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• 2006

강자성체/비자성 금속/강자성체/반도체 구조에서 층간교환강호작용(interlayer exchange coupling) 에너지가 외부 인가전압으로 제어 가능함을 이론적으로 보였다. 비자성 금속층으로 격리된 두 강자성층 사이의 층간교환상호작용 에너지는 강자성체/비자성 금속 계면에서 전자의 스핀에 의존하는 반사율의 차이에 의해 결정된다는 것은 잘 알려진 사실인데, 이를 각자성체/비자성 금속/강자성체/반도체 구조에 적용하여 층간교환상호작용 에너지가 강자성체/비자성 금속/강자성체 계면에서 전자의 반사율뿐 아니라 강자성체/반도체 계면에서의 반사율에도 의존한다는 것을 보였다 강자성체/반도체 계면에 생기는 Schottky 장벽의 높이와 두께는 인가전압으로 바꿀 수 있고, 그에 따른 전자의 반사율이 인가전압에 의해 바뀔 수 있음을 알 수 있었다. 결과적으로 일차원 자유전자 모델을 사용하여 외부 인가 전압으로써 두 강자성체 사이의 층간 교환 상호작용 에너지를 제어할 수 있다는 것을 확인하였다.

• Journal of Astronomy and Space Sciences
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• 제34권3호
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• pp.225-235
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• 2017

The energy balance in a satellite needs to be designed properly for the satellite to safely operate and carry out successive missions on an orbit. In this study, an analysis program was developed using the MATLAB(R) graphic user interface (GUI) for nanosatellites. This program was used in a simulation to confirm the generated power, consumed power, and battery power in the satellites on the orbit, and its performance was verified with applying different satellite operational modes and units. For data transmission, STK(R)-MATLAB(R) connectivity was used to send the generated power from STK(R) to MATLAB(R) automatically. Moreover, this program is general-purpose; therefore, it can be applied to nanosatellites that have missions or shapes that are different from those of the satellites in this study. This power simulation tool could be used not only to calculate the suitable power budget when developing the power systems, but also to analyze the remaining energy balance in the satellites.

• Journal of Advanced Marine Engineering and Technology
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• 제29권5호
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• pp.587-592
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• 2005

The ESS(Energy Saving System) is designed to have functions of controlling. monitoring for cooling system. etc. ESS consists of the I/O module, CPU module and Display module I/O module detects various ESS data on local area and treats signals via I/O interface system. The interface system receives various status data and outputs control signals. ESS is tested with dummy signal to verify proposed functions and is shown good results. For future study ESS will be tested under real condition in the ship.

• 한국생산제조학회지
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• 제19권5호
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• pp.603-608
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• 2010

In this study, one type of circular shaped composite tube was used, combined with reinforcing foam and without foam. Furthermore, CFRP(Carbon Fiber Reinforced Plastic) circular member manufactured from CFRP prepreg sheet for lightweight design. CFRP is an anisotropic material which is the most widely adapted lightweight structural member. The crashworthy behavior of circular composite material tubes subjected to static axial compression under same conditions is reported in this paper. Test was executed in order to compare the results to the energy absorption and collapse shape. The collapse mode during the failure process were observed and analyzed. The behavior of polymeric foams to the tubes crashworthiness were also investigated. According to the experimental results, specimens filled with foam are higher total energy absorption than the other specimens not filled with the foam.

• 대한전자공학회논문지
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• 제25권1호
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• pp.27-32
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• 1988

Electron Spectroscopy for Chemical Analysis(ESCA) allowes the determination of the elemental composition and the bonding state of the surface atomes in the interface between two materials. In the binding energies of ESCA spectrum, there are zero error, voltage scaling error and random error. Accurate analysis of the intensity energy response functions and accurate calibration of the energy scale are essential to use X-ray photoelectron spectron meter. At the results of the calibration of the ESCA spectra in the copper and cordierite (Mg2Al4Si5kO18) interfaces, the errors relative to the copper are -3.03 eV for the zero error -z,-197 ppm for the voltage scaling error -V and 6.9 meV for the random error -R. The method of the calibration is able to apply for the binding energy calibration of the another ESCA spectra.