• Proceedings of the KSME Conference
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• 2000.11a
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• pp.807-812
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• 2000

In general, a structure that is composed with plates has lower bending strength and stiffness than solid structure. To solve this problem, reinforced structures have been used. And we need rules to choose best shape for each using conditions. In this paper, simple equation that expresses equivalent thickness with respect to parameters by substituting results from Finite Element Analysis to normal plate displacement equation was derived.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2001.11a
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• pp.129-137
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• 2001

As the rotational speed and the track density are increased, the vibration of disk/spindle system becomes critical issue. In this work, we propose a simple inclined air bearing(20mm${\times}$20mm) system which is positioned very near to the rotating disk especially compact disc(CD) as a flexible disk, and we investigate suppressing effect about disk mode (0,0) both experimentally and numerically. We find dynamic stiffness and damping coefficients of bearing and apply to the disk vibration. The results show about 10 percent errors comparing to the experimental results. Also we investigate experimentally the reduction of disk vibration and power consumption with two different kinds of inclined bearing for normal disk drive system, which has tray and cover. We find inclined air bearing can decrease about 30 percents of the original disk vibration amplitude.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.472-475
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• 2014

Abnormal cab vibrations in the Y direction in commercial vehicles during driving(70~90kph) are not common vibrations that happen to vehicles during driving and can be an obstacle to normal driving. This study conducted Operation Deflection Shape(ODS) testing to identify the causes of those abnormal cab vibrations and find solutions for them and also a sine sweep test to find resonance and frequency in the cab suspension system and set directions for improvement. The study also altered the shape of the bush inner part for changes to the rigidity features of the cab bush in the Y direction and revised the design with optimal rigidity in the Y direction, thus improving abnormal cab vibrations in the Y direction during driving.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.539-543
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• 2014

This work investigated the electromechanical performance of a cantilevered vibration energy harvester incorporating the single crystal PMN-PZT, manufactured with the most recent technology of solid-state single crystal growth. Single crystal PMN-PZTs with two different crystallographic axes such as [011] and [001] were considered. For the [011] orientation, because material properties such as the stiffness, piezoelectric strain coefficients are not the same in the directions normal to the crystallographic axis, the effects of the transversely anisotropy on the magnitude and frequency bandwidth of output power were also analyzed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.1404-1408
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• 2006

In this paper, a hybrid-type vibration isolator which has air chamber(spring) and viscous damper in series is developed. The developed vibration isolator is designed to perform 3 following functions : spring function for normal operating conditions, damping function to reduce an impact for sudden move of upper beam, and finally leveling function. Based on the given natural frequency and damping factor, the design procedure is proposed. The performance of the developed isolator is tested by measuring stiffness and damping.

• Journal of the Korean Society of Clothing and Textiles
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• v.12 no.2 s.27
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• pp.133-144
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• 1988

Silk fabrics were degummed and dyed in one bath under the condition of high temperature and high pressure and the results obtained were summerized as follows. 1. The degumming ratio is nearly the same as that of two bath method under the normal condition and the optimal condition is for 30 minutes at $120^{\circ}C$. 2. The dyeing absorption ratio is a little lower than that of two bath method. 3. The tensile strength and elongation are hardly shown the difference between two methods. 4. The fastness of the dyed fabric of one bath method is a little better than that of two bath method. (light, washing, rubbing) 5. The stiffness of the silk fabric treated by one bath method is a little harshier compare to that of two bath method.

• Journal of the Korean Geotechnical Society
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• v.16 no.6
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• pp.161-172
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• 2000

자연암석절리 및 인공 절리에 대하여 일정수직응력제어, 일정 수직하중제어 그리고 무한 강성제어가 가능한 암석 절리면 전단기 시험기를 개발하였다. 이 시험기는 전단변위에 의한 첩촉면적의 변화량을 계산하여 하중변화량을 조절하여 일정수직응력상태를 유지한다. 수직하중에 따른 시험기 강성에 의한 변화향이 제어 프로그램 내에서 제어되어 순수한 시편의 변위량을 출력하도록 하였다. 전단하중에 따른 시험기 강성에 의한 변위량은 상, 하부 전단상자의 상대변위 측정으로 최소화하였다. 전단거동 중의 자유도는 전당방향에 대하여 수평이도, 연직이동, 피칭, 롤링이 가능하도록 하였다. 자연절리면을 모사한 석고시편에 대하여 일정 수직응력 제어, 일정수직하중제어 그리고 무한 강성제어 조건으로 시험하여 제어상태 검증 및 비교를 하였다. 또한 경사각이 16.7˚와 22.6˚인 톱니형 시편에 대하여 시험한 결과 경사각 16.7˚와 22.6˚는 JRC로 10과 15를 나타내었으며, 첨두팽창각이 첨두전단강도에서 발생되며, Barton의 모델과 잘 일치함을 보였다.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.4
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• pp.355-360
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• 2010

In this study, a modeling process of a 3-axis planar alignment stage is suggested. Vibration tests using a laser vibro-meter is performed to find the modeling parameters of the stage. By analyzing the result of the test, the stiffness of prismatic joints and revolute joints, as well as the contact conditions of the thrust bearings, can be calculated. The modeling of the stage was validated by comparing six normal mode shapes, which are acquired from experiments and simulations.

• Journal of the Society of Naval Architects of Korea
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• v.40 no.6
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• pp.49-57
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• 2003

This method surely needs a hole that causes local strength and stiffness deterioration of the structure because of stress intensity. In this work, three dimensional stress analysis of pin-loaded joint for quasi-isotropic composite laminates was performed using commercial finite element software. Stress distribution was calculated near the edge of the pin-leaded hole and effects of the stacking sequence on the delamination were investigated. Also, the delamination strength of the composite laminates was predicted using the Ye-delamination failure criterion and compared with the experimental results. finally, newly modified failure criterion has been suggested owing to the consideration of effects of interlaminar normal stress on the delamination strength.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.2151-2155
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• 2008

The tilting train express (TTX) is able to tilt its body toward to the center of the turning radius on curved railways. TTX can travel at higher speed than the existing normal railway vehicles due to the tilting mechanism decreasing centrifugal force. Also, a new suspension system is required for TTX which has proper stiffness constants and damping ratios because it has different suspension characteristics with the others. Therefore, the suspension systems need to be optimized to maximize dynamic characteristic of the railway vehicle. To optimize the dynamic characteristics of TTX, sensitivity analysis should be onde to identify design variables. In this paper, Design of Experiments(DOE) is used for the sensitivity analysis of TTX.