• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.68-71
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• 2004

Recently, a great deal of research and development of a fuel cell have been carried out to solve problems on the drain of fossil fuel, air pollution and global warning. In order to improve the efficiency of a fuel cell, it is necessary to clarify the flow in separator. In this study, distributions of velocity flow rate and pressure, and streamlines are examined in detail from numerical analysis with CFD code. In the experiment the distribution of flow rate is measured and flow in the each grooves of the separator is visualized by dye method changing Reynolds number. Furthermore, effects of size of the inlet and outlet manifolds and shape of ribs near the inlet outlet on the distributions of flow and pressure are examined.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2005년도 Proceedings of ISRS 2005
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• pp.30-33
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• 2005

Though sensible heat flux is one of heat flux components, it is generally considered that the importance is low compared with other components because of the small value. Actually sensible heat flux over the tropical ocean is extremely small, less than $100\;W/m^2$ .. However, it should be noted that sensible heat flux in boreal winter over the western boundary current regions is considerably large, about $100\;W/m^2$, and not neglected. In this study we carry out intercomparison of various global sensible heat flux data including not only satellite-derived data but also reanalysis data in order to clarify the characteristics of those data.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1992년도 하계학술대회 논문집 B
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• pp.922-924
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• 1992

This paper presents a CAE(Computer Aided Engineering)system for solving electrostatic field problems by means of a small size computer such as a personal computer. The system software operated on the personal computer is composed of a CAD(Computer aided Design), electric field analysis by using FEM(Finite Element Method)and DB(Data Base)of insulating materials. In addition, we discuss an application of the system to analyzing electric field such as parallel plate electrodes with an insulation spacer, which result suggests that the visualization of electric field distribution and tolerance for insulation strength enables us to assure a simplified evaluation of the insulating design.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -3
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• pp.1630-1633
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• 2002

In this paper, we proposed a new control system of the dividing ratio changeable type ADPLL (DCPLL). The DCPLL has been designed by us. However, in the DCPLL, there are some problems such as this curcuit is increased the output jitter on multiple frequency, and the output jitter is large on steady state. Then, the output jitter characteristic on multiple frequency is improved by using “rest-control” system. Also, output jitter decreases by using “W-edge (positive edge h negative edge)” system. We confirmed some characteristics of the DCPLL with the circuit simulator, PSpice.

• 한국해안·해양공학회논문집
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• 제24권4호
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• pp.295-304
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• 2012

본 연구는 지진해일의 전파과정을 수치모의할 수 있는 비선형수치모델을 구축하고, 이로부터 최근 일본 태평양 연안에서 발생 가능성이 제기되고 있는 리히터 규모 9.0의 Tokai, Tonankai 및 Nankai의 3연동지진으로 인한 지진해일이 제주도 연안에 미치는 영향을 검토하였다. 수치해석에 있어서는 천해역에서의 천수효과를 충분히 재현하기 위해 격자접속기법을 이용하였으며, 2011년에 발생한 동일본지진과 1983년 동해중부지진에 의한 지진해일에 대한 수치계산을 수행하여 수위변동, 전파시간, 침수계산 등에 대한 기존의 계산치 및 관측치와의 비교로부터 본 수치모델의 타당성을 검증하였다. 3연동지진에 대한 수치모의는 지진해일의 영향을 충분히 고려할 수 있도록 지진 발생으로부터 10시간 동안 계산을 수행하였다. 수치모의를 통해 지진해일의 전파과정에서의 수위변동은 해저수심변화, 굴절, 회절, 반사 등의 영향에 의해 크게 좌우되며, 우리나라 제주도 연안에서는 사계항에서 1.6 m의 최대지진해일고가 추정되었다.

• Animal Bioscience
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• 제34권11호
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• pp.1749-1756
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• 2021

Objective: Microminipig (MMP) is a miniature pig with an extra small body size for experimental use. In the present study, the occurrence of stillbirths and their genetic association with swine leukocyte antigen (SLA) class II haplotypes were evaluated in a population of MMPs. Methods: The occurrences of stillbirth and genetic association with SLA class II haplotypes using 483 stillborn and 2,246 live piglets, and their parents were compared among the three groups of newborn piglet litters; an all stillborn (AS) group consisting of only stillborn piglet litters, a partial stillborn (PS) group consisting of stillborn and live piglet litters, and an all alive (AA) group consisting of only live piglet litters. Results: The incidence of stillborn piglets was 483/2,729 (17.7%). Distributions of litter sizes, numbers of stillborn piglets in a litter, parities, and gestation periods were distinct among the three groups. The frequencies of low resolution haplotype (Lr)-0.7 or Lr-0.23 were higher in the AS group than in the PS or AA groups. In sires, the frequency of Lr-0.7 associated with the AS group was significantly higher in the AS group than with the AA group. In dams, the frequency of Lr-0.23 was significantly higher in the AS group than in the PS or AA groups, whereas the frequency of Lr-0.7 was not significantly different. Conclusion: The incidence of stillborn piglets in MMPs appears to be higher than those in other pig breeds. Several traits related with stillbirths such as the number of stillborn piglets and parities of the AS group were different from those of the PS and AA groups. Specific SLA class II haplotypes were associated significantly with a high incidence of stillbirths and could be used as genetic markers to adopt breeding strategies to lower the rate of stillbirth in MMPs.

• 한국자기학회지
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• 제5권5호
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• pp.659-662
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• 1995

Co-ferrite ($CoO-Fe_{2}O_{3}$) thin films have been prepared by two ways of low temperature solid reaction including oxidation process, being based on $Co-layer/{\alpha}-Fe_{2}O_{3}$ films and $Co-layer/Fe_{3}O_{4}$ films. Magnetic properties of both Co-ferrite films have been measured and compared. The samples from $Co-layer/Fe_{3}O_{4}$ films have a large coercive force in the direction perpendicular and have a great poler kerr rotation angle at wavelength 700 nm than ones from $Co-layer/{\alpha}-Fe_{2}O_{3}$ films. The typical magnetic properties are as follows; saturation magnetization $4{\pi}Ms$, 2.9 kG; remnant magnetization $4{\pi}Mr$, 2.0 kG; coercive force Hc, 4.0 kOe; kerr rotation angle ${\PHI}k$, 0.39 deg($\lambda\;=\;700\;nm$); and initial magnetization energy E, $3.3\;{\times}\;10^6\;erg/\textrm{m}^3$, respectively.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.1355-1359
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• 2004

The two way subscriber transmission systems have tendency to spread its carrier frequency bandwidth or information bit rate and average bit error rate according to popularization of high speed information through the digital communication system, transmission medium and the Internet. This fact is an important incentive to realize new systems. These two way subscriber transmission systems usually use same cable or same carrier frequency bandwidth for up stream channel and down stream channel. In the systems, the disturbances of noise, crosstalk or fading affect the characteristics. Specifically, these disturbances cause the decrease of information bit rate and degradation of transmission quality. This paper proposes the improved method of their degradations using the particular feature of two way subscriber transmission systems and it makes clear proposed method is effective by theoretically and some numerical examples.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.536-539
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• 2004

In this paper, a brief discussion on I-PD position controller design for step motor drive is presented. The proposed method mainly focuses on the robustness property of the controller, which is very important for this type of system in which the variation of external load affects plant parameters. It is considered in this paper that two types of controller design methods namely; Coefficient Diagram Method (CDM), and arbitrary Pole Assignment Method (PAM) are treated and compared them. The control plant chosen for our study is a SM inherently is comprised of some non-linear elements. A the scope of the design method is limited to only linear time invariant systems, the SM modeling is approximated to linear system.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.291-295
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• 2004

New valve driving system to control for the best volumetric efficiency at each load of an internal combustion engine within one engine cycle has been developed. The system needs to reduce pumping loss that cause by throttle valve during the intake valve is opened. In this system the intake valve is driven by a linear DC electromagnetic actuator which is controlled by personal computer. The result is compared both installed and uninstalled actuator into the cylinder head. By both of experimental and numerical calculation, the responsibility of the valve driving system to the engine speed was examined