• 대한조선학회논문집
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• 제54권4호
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• pp.312-320
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• 2017

This paper deals with the development of structural test facility for the strength assessment of marine leisure boat built from carbon fiber reinforced plastics (CFRP) materials. The structural test facility consists of test jig, load application and control system, and data acquisition system. Test jig, and load application and control system are designed to accommodate various size and short span to depth ratios of single skin, top-hat stiffened and sandwich constructions in plated structural format such as square and rectangular shapes. A lateral pressure load, typical and important applied load condition to the plates of the hull structure for marine leisure boat, is simulated by employing a number of hydraulic cylinders operated automatically and manually. To examine and operate the structural test facility, five carbon/epoxy based FRP square plates having the test section area of $1m^2$, which are part of CFRP marine leisure boat hull, are prepared and they are subjected to monotonically increasing lateral pressure loads. In the test preparation, considering the symmetry of the plates geometry, various strain gauges and linear variable displacement transformer are used in conjunction with data acquisition system utilizing LabVIEW. From the test observation, the responses of the CFRP hull structure of marine leisure boat are understood by obtaining load to deflection and strain to load curves.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.372-377
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• 2002

Residual stress by welding should be reduced because that decreases the reliability on strength of welded structure. The reason is that the total stiffness of structure decreases by non-linear behavior of weldment under external load. The release of residual stress by mechanical loading and unloading is often performed in the fabrication of box structure for steel bridge. The proper degree of loading and unloading is significant at release method of residual stress by mechanical loading because that degree is changed by material and geometric shape of welded structure. Therefore, the simulation model that could exactly analyze the release of residual stress by mechanical loading is to be necessary. This simulation model should be established on the based of variable and accurate measurement data. In this study, the non-linear behavior of weldments under external loading and unloading, such as the decrease and increase of structure stiffness, was investigated by monitoring of nominal stress and strain. Tensile loading and unloading test under variable load was performed and the proper degree of stress relaxation was measured by sectioning technique using strain gauge.

• 대한치과보철학회지
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• 제37권1호
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• pp.93-103
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• 1999

Stress distribution on mandibular implants supporting overdentures were registered in vitro experimental model by means of 4 rosette gauges which were placed around the implant. The overdenture attachments used in this study were the Resilient Dolder bar, Rigid Bolder bar, Round bar, Hader bar & Dal-Ro attachment. An occlusal jig was placed on the overdenture and the loading sites were 3 points which mimicked working, balancing, and median relations. With 5 and 10kg loading, strains were measured by strain indicator(P-3500, Measurement group, Raleigh, USA), and using these data, maximum and minimum principal stresses and Von Mises stress were calculated and evaluated. The results were as follows : There was a tendency of high stress concentration in the lingual side of the implant, and in the buccal side low stress was developed regardless of the attachment systems. The resilient Bolder bar concentrated highest stress among the attachment systems, and the Round bar and the Dal-Ro attachment provided comparatively low stresses around the implant. The rigid Bolder bar concentrated high stress in the mesial side, and the Dal-Ro attachment developed tensile stress patterns in the lingual and distal sides of the implant at the balancing relation.

• International Journal of Korean Welding Society
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• 제2권1호
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• pp.40-44
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• 2002

Residual stress by welding should be reduced because that decreases the reliability on strength of welded structure. The reason is that the total stiffness of structure decreases by non-linear behavior of weldment under external load. The release of residual stress by mechanical loading and unloading is often performed in the fabrication of box structure for steel bridge. The proper degree of loading and unloading is significant at release method of residual stress by mechanical loading because that degree is changed by material and geometric shape of welded structure. Therefore, the simulation model that could exactly analyze the release of residual stress by mechanical loading is to be necessary. This simulation model should be established on the based of variable and accurate measurement data. In this study, the non-linear behavior of weldments under external loading and unloading, such as the decrease and increase of structure stiffness, was investigated by monitoring of nominal stress and strain. Tensile loading and unloading test under variable load was performed and the proper degree of stress relaxation was measured by sectioning technique using strain gauge.

• 한국지반공학회지:지반
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• 제9권1호
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• pp.59-68
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• 1993

In deep excavations for creation of underground spaces, it would be difficult to predict earth pressure, especially multilayered ground including rock strata. The earth pressures and displacements on the retention walls are measured by load cell, strain gauge and inclinometer which were installed at struts or anchors at 4 deep excavation sites in Seoul area. In this paper, the measured earth pressure from the struts or anchors are compared with Peck's empirical values, and the coefficient of the earth pressures for each strata and horizontal wall displacement are investigated. The coefficient of earth pressure distribution, a(0.65zka), in the flexible and the rigid walls was about 74% and 88% of Peck's value respecitively. The measured earth pressure distributions for the 4 sites showed about 70%∼80% of Peck's empirical values and the average earth pressure coefficients based on the measured data were 0.3 for the felted layer, 0.23 for the weathered rock and 0.19 for the weak rock. The maximum w리1 displacements were found to be less 0.2% of excavation depth.

• Journal of Advanced Marine Engineering and Technology
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• 제29권7호
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• pp.785-794
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• 2005

Modern ship hulls of large oil carriers and container carrers have become more flexible with scantling optimization and increase in ship length. On the other hand. as the demand for power has increased with the ship size. shaft diameters have become larger and stiffer. Consequently. the alignment of the propulsion system has become more sensitive to hull girder deflections. resulting in difficulties in analyzing the alignment and conducting the alignment procedure. Accordingly. the frequency of shaft alignment related bearing damages has increased significantly in recent years. The alignment related damages are mostly attributed to inadequate analyses. changes in the design of the vessel. shipyards' practices in conducting the alignment. and a lack of well defined analytical criteria. The hull deflections should be considered at the design stage to minimize the bearing damage caused by hull deflection. Hull deflections can be estimated by analytical approach and reverse calculation using the measured data. The hull girder deflection analysis using the reverse calculation will be introduced in this paper.

• 한국정보통신학회논문지
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• 제5권7호
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• pp.1308-1313
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• 2001

본 논문은 3상 유도전동기의 파라미터 측정정법과 기동특성을 제시한다. 고정자 권선저항, 구속 및 무부하시험에 의해 측정된 유도전동기 파라미터를 이용하여 전동기의 기동특성을 시뮬레이션 하였다. 또한 유도전동기 축에 스트레인 게이지를 부착하여 기동토크에 대한 특성을 실험으로 확인하고 이를 시뮬레이션 결과와 비교 분석하여 그 타당성을 검증하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 B
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• pp.849-851
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• 2001

This paper presents experimental method of parameter measurement and starting characteristics of 3 phase induction motor. Equivalent circuit parameters measured by DC test, the blocked rotor test, and no load test were used as the input data for computer simulation. Starting characteristics, such as starting current and torque were analyzed through computer simulation by Matlab, and the simulation results were compared with experiment using strain gauge attached on motor shaft. We conform that experimental results are very similar to that of simulation.

• 설비공학논문집
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• 제7권3호
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• pp.421-434
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• 1995

A new instantaneous flowmeter for hydraulics by means or cylindrical chokes is developed. In this method the instantaneous flowrate through chokes is predicted in real time from measurement of pressure difference on both sides of cylindrical choke. The experimental study for the flowrate of pulsating flow in a pipe is carried out to measure differential pressure drop by using a strain gauge pressure transducer with data acquisition and processing system. A pulsating flow is verified by a visualization method. In the present study, the flow characteristic variables of laminar pulsating flow are investigated analytically and experimentally in a circular pipe. Characteristic parameters of ratio of inertia term to pressure term($\phi_{t.1}$) and ratio of viscous term to pressure term($\phi_{z.1}$) are introduced to describe the flow pattern of laminar pulsating flow.

• 대한소아치과학회지
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• 제33권4호
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• pp.606-614
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• 2006

이 연구의 목적은 이장재의 종류에 따른 광중합형 복합레진 충전 후 중합수축을 비교함으로써 중합수축 감소를 보이는 좀 더 우수한 재료의 조합을 모색하고자 시행되었다. 이장재로는 유동형 레진, 컴포머, 광중합 글래스아이오노머를 사용하였고 수축응력을 측정하기 위해 스트레인 게이지를 사용하였다. 표본은 광원의 종류, 이장재의 종류에 따라 8개의 군으로 나눠졌다. 스트레인 게이지를 아크릴릭 링에 부착하고 strainmeter에 연결한 후 각 군에 따라 이장재 적용 후 광중합 하고 이장재 중합 후 750초간 수축응력을 측정하였다. 결과는 Repeated measures ANOVA와 Tukey test를 이용해 통계학적으로 분석하였다. 이상의 실험을 통해 얻은 결과는 다음과 같다. 1. 이장재를 사용하지 않은 군보다 이장재를 사용한 군의 중합수축이 적었으나 Ionosit을 사용한 군에서는 유의한 차이는 없었다(p>0.05). 2, Tetric flow 또는 Vitrebond를 이장재로 사용하는 것이 Ionosit을 사용하는 것보다 중합 수축이 적었다(p<0.05). 3. Tetric flow 이장재를 한 군은 광원에 따른 수축력의 차이가 적었고 Vitrebond와 Ionosit 이장재를 한 군은 할로겐 광원보다 LED 광원에서 수축응력이 컸으나 유의한 차이는 없었다(p>0.05).