• Aerospace Engineering and Technology
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• v.6 no.1
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• pp.146-156
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• 2007

In this paper, the TVC actuation test and analysis results for a flexible seal kick motor nozzle are presented. A real-sized test model of KSLV-I kick motor system is applied to water pressurizing TVC tests which investigate the property changes in TVC nozzle expansion and TVC actuation performance against chamber pressure changes. The equipments which are required for TVC actuation tests are briefly explained. The TVC actuation tests are firstly accomplished in static mode, which reveals TVC error characteristics including thrust misalignment, control accuracy, and TVC stroke increase, etc. The properties in frequency domain is given via dynamic tests. These results may play an important role in enhancing the TVC control performance of KSLV-I.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.4A
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• pp.245-253
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• 2012

In the longway tunnel and underground traffic road, the structure of transverse ventilation system is constructed by the airpit slab. In this study, the full scale specimens of the PSC airpit slab that attached fire resistance panel are performed the static and dynamic loading tests for evaluation of bending capacity. The first of all, it confirmed the evaluations about the fundamental efficiency of the fire resistance panel and PSC slab by the 3-point bending test and pull-off test. The tests are performed for evaluation of the bending resistance under ultimate static load and the bonded capacity under dynamic fatigue load. A fatigue test is performed for an investigation of the effect on wind pressure that is developed by transit of traffic. The damage or debonding on surface between fire resistance panel and PSC slab was not developed in dynamic fatigue load test, also the behavior of the specimens is very stable and the debonding of the fire resistance panel attached at the bottom surface of PSC slab was not developed in static load test, too. Therefore, the crack or debonding of the fire resistance panel will be not developed by external loads during the construction or completion of the precast fire resistance system.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.5
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• pp.1741-1751
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• 2013

The main purpose of this study is to investigate the static behavior of a prestressed concrete (PSC) girder using pre-tension method. A 30m long full-scale pretension PSC girder is fabricated by the portable fabrication system and tested. All results have been compared to those obtained from F.E.A results. Deflections at the middle of girders have been measured for evaluation. Also, strains of concrete at the middle of span have been measured. From the results of experimental, the load when initial crack was developed was obtained to be 1.75 time the unfactered design load in the full-scale girder specimen. Also, the data of specimen are satisfied the desgin requirements of ductility on the Korea Bridge Design Specification(2010). In service state, the vertical deflection at center of test specimen when a initial crack was developed is satisfied the vertical deflection requirement under live load of the Korea Bridge Design Specification(2010). To verify the experimental results, we numerical analyze the test and confirmed that the data were similar with results from the test above. The pretension girder fabricated in site were found to have enough strength for safety under and after construction.

• Journal of the Earthquake Engineering Society of Korea
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• v.5 no.3
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• pp.29-36
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• 2001

Same as-built drawings in national roadway bridges in Korea were examined. As a result, many bridge piers were found whose aspect ratios are in the vicinity of 2.5. These columns are expected to do shear-flexure behaviour, but the previous research works considered flexure behaviour columns only. In the study, therefore, a shear-flexure behaviour column was selected as the model pier, and quasi static test on the full and 1/2 scale models was carried out. From the test results, the scale effect on the seismic performance evaluation was analyzed, and the seismic performance of the model bridge pier without seismic details was evaluated by the capacity spectrum method.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.4
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• pp.747-757
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• 2015

The main purpose of this study is to investigate the static behavior of a horizontally curved prestressed concrete (PSC) girder. A 30m long full-scale curved PSC girder with 80.0m radius is fabricated by a portable curved form system. Deflections and concrete strains at the middle of span were measured. The obtained experimental results have been compared to those from F.E.A. analysis. When a initial crack developed, the applied load was 1.3 times the service design load and the vertical deflection at the middle of span satisfied the requirement for a live load state according to the Korea Bridge Design Specifications (2010). Also, the ductility of the full scale specimen satisfied the limit in the Specifications (2010). To verify the experimental results, a numerical F.E. analysis was carried and confirmed that the data were similar with results from the test above. The horizontally curved PSC girder fabricated on site was found to have enough strength for safety under and after construction.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.12
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• pp.1599-1606
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• 2011

It is possible to study the load characteristics of full-scale hingeless rotor with the changing of physical smallscaled configurations such as rectangular and paddle blades, and metal and composite hubs. In this study, a static test, and a ground and wind-tunnel test were carried out using small-scale rotor models. The static test was carried out to confirm structural stiffness, characteristics of inertia, natural frequency, and damping ratio of rotors, and the ground and wind-tunnel test was carried out to confirm the stability and aerodynamic characteristics under hovering and forward flight conditions. According to the test results, the vertical load in the case of a combination of a small composite hub with paddle blades was higher than that in the case of a metal hub with paddle blades at same condition. Further, it was confirmed that the restraint of the combination of composite hub can be more flexible than the metal hub for the motion of paddle blades.

• Computational Structural Engineering
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• v.5 no.2
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• pp.12-17
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• 1992

지진하중에 대한 내진성능을 평가하기 위하여 유사동적 실험기법은 다양한 시험체를 대상으로 응용되어 왔다. 특히 실물크기의 시험체에 대한 실험이 가능하다는 특징 때문에 substructuring기법을 도입하여 부분구조물에 대한 유사동적실험이 활발히 진행되고 있으며, substructuring기법에 사용되는 수치적분 알고리즘의 효율성 및 새로운 보완이 필요한 것으로 판단된다. 근래에 구조물의 진동제어(vibration control)를 목적으롤 개발된 rubber bearing, viscous damper 등은 두드러진 감쇠특성을 갖고 있는 장치로서 strain-rate 효과에 비교적 민감하다. 지금까지의 유사동적실험을 준정적으로 실험이 수행되었으나, 이러한 장치가 설치된 구조물의 진동제어 성능실험을 위해서는 가능한 실시간(real time)에 가까운 실험 진행속도를 갖는 것이 유리하다. 최근에 Nakashima는 digital servomechanism을 이용하여 실시간에 가까운 실험속도의 유사동적 실험을 수행하였으며, 이에 대한 지속적인 연구를 진행하고 있다.

• Journal of Korean Society of Steel Construction
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• v.12 no.3 s.46
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• pp.239-250
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• 2000

This study investigates the mechanical behavior on trough rib to crossbeam joint in orthotropic steel plate decks, specially emphasizing on the effect of diaphragm inside trough rib on the fatigue behavior of slit by static and fatigue tests. In particular, the effects of diaphragm on in-plane stress and out-of-plane stress, stress concentration, propagation of fatigue cracks at the silt are studied. With the result of experiment and numerical analysis, we have estimated the fatigue strength using the nominal stress and hot-sport stress. The details with diaphragm have occurred about 50% stress reduction at trough rib part of trough rib to crossbeam joint than the detail without diaphragm, however, the lower parts of crossbeam have occurred much more stress. Initial crack size or slit have an considerable influence on the propagation of fatigue cracks due to V-notch. The fatigue strength category of the details without diaphragm has higher value than fatigue limit, whereas that of the details with diaphragm is estimated lower than fatigue limit.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2464-2472
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• 2011

Train runs on high speed and the concrete track is constructed. Rail fastening device needs to reduce elasticity, transferred load, noise, and vibration etc. Consequently, low elastic pad has a great impact of the durability and stability of the track. In this study, discussed in previous studies, static numerical analysis and real scale repeated loading test, followed by dynamic response analysis were implemented. The most distinctive characteristics of the model proposed is to simulate the real wheel behavior on rail. And the main analysis object is to evaluate and compare the deformation characteristics of the transition track while load reduction effect of transfer on roadbed assessed by various low elastic pad.

• Journal of the Korea Concrete Institute
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• v.16 no.5 s.83
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• pp.697-707
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• 2004

Most bridge piers were practically designed and constructed with lap spliced longitudinal reinforcing steels before the 1992 seismic design provisions of Korea Bridge Design Specification were implemented. It has been known that lap splice of longitudinal reinforcement in the plastic hinge region is not desirable for seismic performance of RC bridge piers. The objective of this research is to evaluate the seismic performance of existing circular reinforced concrete bridge piers by the Quasi-static test and to propose the need of seismic retrofit of existing bridge piers through the damage level. Test specimens were nonseismically designed with the aspect ratio 4.0 which could induce the flexural failure mode. It was confirmed from this experiment that significant reduction of seismic performance was observed for test specimens with lap spliced longitudinal reinforcing steels. Pertinent seismic retrofit was determined to be needed for existing RC bridge piers with the lap-spliced of $50\%$ longitudinal reinforcing steels.