• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.285-288
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• 2000

This paper deals with the theoretical estimation and its experimental verification of grinding wheel wear in surface grinding process. A theoretical formulation is provided to predict the grinding wheel wear in surface grinding. The associated surface roughness and grinding force are also investigated both theoretically and experimentally. Through a series of simulations and experiments, it is shown that the predictions are in good agreement with the experimental results.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.1109-1112
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• 2001

In the grinding process, the edge of shape is very important to evaluate the surface roughness and the precision of dimension. To keep precision of product, parameters with respect to the amount of wheel wear have to limit by grinding condition. In this paper, we measured variation of grinding force to seek the grinding characteristics by the amount of wheel wear in surface grinding. Also, we find out that how these condition give influence to wheel life.

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.499-502
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• 2006

This paper presents computed results of FEM analysis on the tribological contact behaviors of a primary sealing components of mechanical face seals for a small hydro-power turbine. The FEM computed results present that the contact area between seal rings and seal seats is very important for a good tribological performance such as low friction heating, low wear, high contact normal stress in a primary seal ing components. Based on the FEM computation, model III in which has a small sealing contact area shows low dilatation of primary sealing components, and high contact stress between a seal ring and a 1)seal seat.

• The Journal of Natural Sciences
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• v.14 no.2
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• pp.1-14
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• 2004

The observation of the various swing parameters and its effect on golfer swing are tatally analyzed. The golf ball impact and flies away, therefore it must be controlled bofore ball impact. The purpose of this paper is that the cause of hook and slice are found and the posture of swing is corrected. The trajectory after ball impact is on the $\Delta$-plane, which is consisted of the normal vector on club face and the swing velocity vector of club head including the initial celocity and the spin axis after ball imfact. In order to correct the miss shot in golf swing, this paper is is shown that the theoretical review and study is discussed to use the D-plane and $\Delta$-plane.

• The Journal of the Acoustical Society of Korea
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• v.31 no.3
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• pp.151-160
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• 2012

In medical ultrasound imaging, elasticity imaging helps to diagnose tumors such as cancer. This paper is concerned with the application of acoustic radiation force to soft tissue of interest to implement elasticity imaging. In order to reduce the data acquisition time, instead of relying on transmit focusing, a plane wave of burst type is transmitted to apply the acoustic radiation force simultaneously to an entire imaging region to be observed. A homogeneous phantom experiment confirms that increasing the transmit excitation duration instead of employing transmit focusing generates a high enough acoustic radiation force to obtain elasticity images. It is found, however, that a different displacement versus time characteristic is observed unlike the case of using a conventional focused acoustic radiation force. Experimental results obtained through the use of an ultrasound phantom and a bovine liver show that lesions can be correctly differentiated.

• Journal of the Korean earth science society
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• v.32 no.1
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• pp.73-83
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• 2011

A new method was developed to better understand the principle of Coriolis force. We also investigated the understanding of 5 10th grade students and analyzed their responses. Since no clear explanation about the nature of a rotating disk is provided in school textbooks, it tends to be misunderstood as the earth surface revolving on its axis pointing to the North Pole. This study was carried out focusing on the fact that a rotating disk is the tangential plane at arbitrary latitude. Results showed that there are changes in students' conceptions on the principle of Coriolis force with a new understanding of the rotating disk. In conclusion, a new method used in this study helped students better understand the link between Coriolis force and rotating disk. The method would be helpful to clarify the principle of Coriolis force in school science.

• Journal of Korean Ophthalmic Optics Society
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• v.8 no.2
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• pp.57-63
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• 2003

To investigate the RMS SD(Root Mean Square Spot Diameter) in a back focal plane as the front surface power, the center thickness, and the refraction index vary, we use programs which are Cove V and LOSA 2.0, and consider a spectacle lens with back vertex power of -4.00D and diameter of 70 mm. We also consider the front surface power varied from 0.00 to 10.00D, the center thickness varied from 1.1 to 2.0 mm, and the indices which are $n_d$ = 1.498, 1.523, 1.586, and 1.660, respectively. As the front surface power increases the RMS SD in the back focal plane increase rapidly. When the refraction index increases, the RMS SD in the back focal plane decrease and the variation of RMS SD in the back focal plane decreases as the front surface power increases. When the center thickness of spectacle lens increases, the RMS SD in the back focal plane is constant and the edge thickness of that increases. We know from these results that the image in the back focal plane of a spherical spectacle lens improves as the front surface power increases and the refraction index decreases.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2017.04a
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• pp.72-72
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• 2017

국내 농업에서 토양의 반전, 쇄토, 배토, 가능한 복합작업기인 무동력 디스크해로우 방식의 경운과 배토 고효율 복합작업기의 수요가 증가 하고 있다. 경운작업에서 일련의 과정은 작물의 생육과 관리차원에서 큰 의미를 지니며 작물재배의 첫 단계로 중요시 다루어져야할 과정이다. 이러한 작업기의 성능 시험에서 포장시험을 통해 복합기의 신뢰도와 실제 필드에서 발생하는 문제들을 포괄적으로 해결 할 수 있는 방안이 필요하다. 토양 경작을 위한 농업기기의 작업 저항은 식물 생산에서 유용성을 평가하는 가장 중요한 지표중 하나이다. 작업 저항(수평, 수직 방향의 힘)은 트랙터의 힘에 의해 생성된 동작을 방해하므로 토양 경운 시 에너지 소비를 결정하고 설계 매개 변수 측면에서 최적의 작업 조건을 결정하는 데 중요한 영향을 미친다. 따라서 본 연구에서는 경상대학교 내 위치한 실험동에서 Soil-bin에 이송장치를 설치한 후, 이송장치에 디스크 해로우 (Multidisc Vario, Tulip Agri., Netherlands)를 부착하여 실험을 진행하였다. 디스크 해로우의 원주 평면과 수직 평면 사이의 각 a(토양 표면에 수직)와 디스크의 해로우의 원주 평면과 작업 방향 사이의 각 b의 값을 독립 변수로 두고 a, b를 변화 시키면서 발생하는 이송장치의 견인력을 측정하여 농가 및 효율적인 경운작업 시 기초자료로 활용하고자 한다.

• 전기의세계
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• v.35 no.1
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• pp.20-26
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• 1986

시간오차 및 수수에너지오차의 교정방법은 많은 전력회사(또는 제어지역)이 한개의 대전력계통으로 동작하는 경우에 적용되는 것이므로 단일 회사의 전력계통에는 적용할 수 없다. 다만 한 전력회사계통도 수개의 제어지역으로 나누어질 수도 있으므로 수개의 제어지역이 Tie-line Bias control에 의하여 동작하는 경우에는 적용된다.(a) 시간오차 및 수수에너지오차를 한개 벡터의 두 성분으로 보고, 이를 하나의 제어지역i와 나머지 제어지역의 성분으로 분해가능하다. (b) 벡터 Decomposition은 2차원 Cartesian평면에 도시할 수 있으며 이를 (.epsilon., Ii)평면이라고 하였다. 이 평면에서 Ii=(-Br/6).epsilon.상에 있고, 나머지 제어지역이 지역i에 미치는 벡터성분은 선분 Ii=(Bi/6).epsilon. 상에 있다. (c) 제어지역i단독 또는 나머지 제어지역의 control action이 지역i의 시간오차 및 수수에너지오차에 미치는 영향을 관찰하고 현행 NERC 교정법도 이에 따라 도시하였다. (d) 현행 NERC교정법을 수정한 교정법을 제시하였으며, 두가지 교정법의 Regulation에너지를 비교하고 예시하였다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.13 no.1
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• pp.105-113
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• 2000

Seismic behavior of 3-dimensional setback structures showing abrupt reductions of the floor size within the structure height and the effect of in-plane deformations of floor slabs on the seismic behavior of those structures are investigated. To find out general seismic behavior of 3-dimensional setback structures two parameters, level of setback(L/sub s/) and degree of setback(R/sub s/) are used. Analysis results obtained from forty eight setback structures show that a sudden change in story shear near setback level is occurred for irregular setback structures. The effect of in-plane deformation of floor slabs on the seismic behavior of setback structures is greatly influenced by the arrangement of lateral load resisting elements and it is more pronounced for frame-shear wall system showing large difference in stiffness among the lateral load resisting elements. The in-plane deformation of floor slabs results in reduced base shear, especially for FW-type structures with L/sub s/=1.0. Also, it brings about reduced story shear for the lateral load resisting element with shear wall and increase in story shear lot the lateral load resisting element without shear wall. The in-plane deformation of floor slabs at the base portion and/or tower portion due to difference in stiffness among the lateral load resisting elements brings about increment of floor displacements at all floor level.