• 산업기술연구
• /
• 제10권
• /
• pp.69-72
• /
• 1990

In this paper the numerical method for the study of wave reflection from and transmission through submerged permeable breakwaters using the boundary element method is developed. The numerical analysis technique is based on the wave pressure function instead of velocity potential because it is difficult to define the velocity potential in the each region arising the energy dissipation. Also, the non-linear energy dissipation within the submerged porous structure is simulated by introducing the linear dissipation coefficient and the tag mass coefficient equivalent to the non-linear energy dissipation. For the validity of this analysis technique, the numerical results obtained by the present boundary element method are compared with those obtained by the other computation method. Good agreements are obtained and so the validity of the present numerical analysis technique is proved.

• 한국동물생명공학회지
• /
• 제34권2호
• /
• pp.70-74
• /
• 2019

The kidney is a highly complex organ, and acute or chronic renal diseases can occur with various complications such as diabetes and hypertension. So far, no target specific treatment is available in acute or chronic renal failure, necessitating the development of alternative therapeutic strategy. Recent experimental findings suggest that the renal function and structure can be restored after being treated with various sources of stem/progenitor cells. In this review, we discuss up-to-date findings of the potential of renal progenitor/stem cells in alleviating renal injuries with a focus on preclinical studies. We also review cellular mechanisms underlying the therapeutic function of these cells.

• 대한조선학회논문집
• /
• 제42권1호
• /
• pp.18-23
• /
• 2005

The transmission and reflection coefficiencies of a BBDB-type floating breakwater in water of finite depth are studied taking account of fluctuating air pressure in the air chamber. The wave potential is calculated by a hybrid integral equation consisting of a Green integral equations associated with the Rankiue Green function inside the BBDB and the Kelvin Green function outside. The transmission and reflection coefficients of the breakwater are obtained directly from the potential solution in the outer region.

• 한국수자원학회:학술대회논문집
• /
• 한국수자원학회 2008년도 학술발표회 논문집
• /
• pp.49-58
• /
• 2008

The function of river navigation is being reconsidered from the viewpoints of environment-friendly and energy-efficient, easing traffic congestion, emergency transport in disaster, and supporting tourism and recreation activities, etc. The purpose of this study is to identify current trends and problems of river navigation in Japan and indicate the role that river navigation should play in future and the directionality of development. This study focused on disaster prevention function with especially high importance degree in metropolitan area from among various functions of river navigation, and showed potential of river navigation corresponding to stranded commuter who is examined as a serious problem in government.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1996년도 하계학술대회 논문집 C
• /
• pp.1844-1847
• /
• 1996

In the paper, we have obtained electron energy distribution function (EEDF) in plasma by using two differentiators. In addition, we have investigated the comparision of the EEDFs by sawtooth and triangle waveform voltages. It is found that as pressure is decreased, electron density is decreased, and plasma potential is increased. And as the position of probe moves the outer of plasma, plasma potential is decreased, and electron temperature is decreased.

• 전기학회논문지
• /
• 제58권12호
• /
• pp.2311-2315
• /
• 2009

This paper presents a method to apply energy margin for assesment of total transfer capability (TTC). In order to calculate energy margin, two values of the transient energy function have to be computed. The first value is transient energy that is the sum of kinetic and potential energy at the end of fault. The second is critical energy that is potential energy at controlling UEP(Unstable Equilibrium Point). It is seen that TTC level is determined by not only bus voltage magnitudes and line thermal limits but also transient stability. TTC assessment is compared by the repeated power flow(RPF) method and optimization method.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2003년도 추계학술대회
• /
• pp.121-126
• /
• 2003

A study of argon droplet vaporization is conducted using molecular dynamics, instead of using traditional methods such as the Navier-Stokes equation. Molecular dynamics uses Lagrangian frame to describe molecular behavior in a system and uses only momentum and position data of all molecules in the system. So every property is not a hypothetical input but a statistical result calculated from the momentum and position data. This work performed a simulation of the complete vaporization of a three dimensional submicron argon droplet within quiescent environment. Lennard-Jones 12-6 potential function is used as a intermolecular potential function. The molecular configuration is examined while an initially non-spherical droplet is changed into the spherical shape and droplet evaporates. And the droplet radius versus time is calculated with temperature and pressure profile.

• International Journal of Aeronautical and Space Sciences
• /
• 제4권1호
• /
• pp.99-109
• /
• 2003

Attitude control law synthesis for the three-axis attitude maneuver of a flexible spacecraft model is presented in this study. The basic idea is motivated by previous works for the extension into a more general case. The new case includes gravitational gradient torque which has significant effect on a wide range of low earth orbit missions. As the first step, the fully nonlinear dynamic equations of motion are derived including gravitational gradient. The control law design based upon the Lyapunov approach is attempted. The Lyapunov function consists of a weighted combination of system kinetic and potential energy. Then, a set of stabilizing control law is derived from the basic Lyapunov stability theory. The new control law is therefore in a general form partially validating the previous work in some sense.

• 지질공학
• /
• 제11권3호
• /
• pp.269-278
• /
• 2001

MD 시뮬레이션을 이용하여 $\alpha$-quartz, 백운모, 조장석의 열팽창계수를 산정하였다. MD 시뮬레이션에서 가장 중요한 포텐셜 함수로는 부분이온성 두입자간 포텐셜을 이용하였다. 열팽창계수는 격자구조의 온도에 따라 변화를 NPT-ensemble 시뮬레이션을 통하여 계산하여 산정하였으며 그 결과를 실험결과와 비교하였다. 시뮬레이션을 통하여 산정된 열팽창계수는 시험결과와 잘 일치하고 있으며, 유효한 수준의 결과를 보이고 있다.

• 조명전기설비학회논문지
• /
• 제25권6호
• /
• pp.49-56
• /
• 2011

Grounding system insures a reference potential point for electric devices and also provides a low impedance path for fault currents or transient currents in the earth. The ground impedance as function of frequency is necessary for determining its performance since fault currents could contain a wide range of frequencies. In this paper, the grounding resistance, grounding impedance and transient grounding impedance are measured by using 3-point fall-of-potential method in order to analyse grounding characteristics of the copper and concrete rod grounding electrodes. An equivalent transfer function model of the ground impedance and transient grounding impedance are identified from the measured values by using ARMA method and evaluated by comparing the conventional grounding impedance.