• Journal of the Korean Society for Railway
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• v.15 no.2
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• pp.154-161
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• 2012

The damping ratio of railway bridge has become one of the most important issues in dynamic design and dynamic stability of railway bridge. In the present study, laboratory and field test were performed for railway bridges such as a twin I-shaped steel composite girder, PSC box, steel box, PSC, IPC, PRECOM, preflex. The damping ratio of railway bridge according to structure types was estimated by logarithmic decrement method. Therefore, magnitude, frequency and amplitude of load did not affect damping ratio of railway bridge. Also, damping ratio limit of steel composite and PSC bridges was evaluated in 1.0%.

• Proceedings of the Korean Information Science Society Conference
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• 2005.11a
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• pp.559-561
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• 2005

CAN(Controller Area Network)은 시스템이 간단하고 저렴하게 구현 할 수 있는 필드버스(Field bus)로써 1980년대 독일의 BOSCH사에 의해 자동차 제어용 네트워크로 개발되었고, 실시간 계측제어 능력이 우수하여 산업전반(산업 자동화, 건을 자동화, 의료 장비, 열차, 중장비 차량)에 사용되고 있다. 본 논문에서는 CAN의 단일 마스터 시스템(Single Master System)에서 마스터 노드에 문제가 발생할 때, 전체 시스템이 다운되는 현상을 악기 위해 마스터 노드를 동적으로 변화시키는 동적 마스터 시스템(Dynamic Master System)을 제안하고 기존의 시스템과 비교하여 시스템의 가용성을 알아보았다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.741-744
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• 2003

in this paper, we propose a dynamic-based compression system by creating mosaic background and transmitting the change information. A dynamic mosaic of the background is progressively integrated in a single image using the camera motion information. For the camera motion estimation, we calculate perspective projection parameters for each frame sequentially with respect to its previous frame. The camera motion is robustly estimated on the background by discriminating between background and foreground regions. The modified block-based motion estimation is used to separate the background region.

• Journal of Korean Society of Transportation
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• v.12 no.2
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• pp.5-30
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• 1994

다이아몬드형 인터체인지는 고속도로와 노면가로가 교차할 경우 방향별 교통류를 처리하는데 보편적으로 사용하는 인터체인지이다. 인터체인지에 교통량의 부하가 과도해지 면 인터체인지내부의 교차로에서 발생한 대기차량이 종종 고속도로본선으로 역류하여 본선 의 교통소통에 문제를 야기하며 특히 고속도로의 안전에도 큰 위험요소가 된다. 본 논문은 과포화상태의 다이아몬드형 인터체인지의 교통신호제어를 다루며, 신호시간계획을 산출하는 동적 최적화모형(dynamic optimization model)을 제시한다. 최적화 모형은 지체도최소화를 목적함수로 하며, 함수계측법의 형태가 된다. 본 모형의 핵심은 신호제어에 따라 발생하는 대기차량길이를 모형화하여 대기차량길이가 정해진 상한치를 초과하지 않도록 하는 신호시 간계획을 산출하는데 있다. 제시된 동적모형은 다이아몬드형 인터체인지의 신호시간을 위하 여 널리 사용되는 PASSER III와 최적해를 상호 비교한다. TRAF-NETSIM을 통한 시뮬레이 션의 결과에 따르면 동적 모형이 우수한 결과를 보이며, 대기차량의 길이를 효과적으로 제 어하는 것으로 판명된다.

• Journal of the Society of Naval Architects of Korea
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• v.32 no.3
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• pp.37-43
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• 1995

The procedure and the results of the full scale strain measurement of the long-range high-speed foil catamaran are described. The wave induced stresses at the center struts of the foils were measured during the sea trials in order to evaluate the hydrodynamic force acting on the foils and to verify the structural safety of the foil structures. From the statistical properties of the measured response of the stress, the most probable maximum values of the lift force and the stresses at the foils in service life of the ship are predicted and compared with the design parameters of the foils which were applied in the design of the subject ship. The available prediction processes of the measured stress are studied and the results of the applied processes are compared with each other.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.2
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• pp.619-629
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• 2013

The objective of this study is to estimate shear wave velocity of earth dam materials using artificially generated vibration from blasting events and to verify its applicability. In this study, the artificial blasting and vibration monitoring were carried out at the site adjacent to Seongdeok dam, which is the first blasting test for an existing dam in Korea. The vibrations were induced by 4 different types of blasting with various depths of blasting boreholes and explosive charge weights. During the tests, the acceleration time histories were recorded at the bedrock adjacent to the explosion and the crest of the dam. From frequency analyses of acceleration histories measured at the crest, the fundamental frequency of the target dam could be evaluated. Numerical analyses varying shear moduli of earth fill zone were carried out using the acceleration histories measured at the bedrock as input ground motions. From the comparison between the fundamental frequencies calculated by numerical analyses and measured records, the shear wave velocities with depth, which are closely related to shear moduli, could be determined. It is found that the effect of different blasting types on shear wave velocity estimation for the target dam materials is negligible and the shear wave velocity can be consistently evaluated. Furthermore, comparing the shear wave velocity with the previous researchers' empirical relationships, the applicability of suggested method is verified. Therefore, in case that the earthquake record is not available, the shear wave velocity of earth dam materials can be reasonably evaluated if blasting vibration test is allowed at the site adjacent to the dam.

• Journal of Sensor Science and Technology
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• v.4 no.4
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• pp.47-54
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• 1995

Sensory measurements are inevitably uncertain, and this may decrease the reliability of sensor feedback systems. In this paper we present a method to achieve reliable measurements using multiple sensors. Assuming sensors with unknown characteristics in dynamic surroundings, readings from the sensors are clustered and fused with the estimated degrees of credit. In the experiment performed with logical sensors the technique proposed is employed to adaptively estimate the measurand under the circumstances where an existing probabilistic technique is difficult to be applied. The technique proposed may be useful for automatic systems working in unstructured environments - for example, sensory robots employed for intelligent manipulation.

• Explosives and Blasting
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• v.36 no.3
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• pp.10-18
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• 2018

The dynamic behaviour of the rock mass under the dynamic load is different from the static application of the maximum load of the same size. An experimental approach to investigating rock behavior under dynamic loads is more difficult than that under static conditions in control of dynamic loads, measurement and analysis of the results. Numerical methods are less constrained by performing the experiments numerically, rather than experimental ones, so they can be very powerful analytical tool at the design stage. However, even if the algorithms of the analysis method are appropriate, careful analysis is required because the calculation results may vary largely depending on input data and boundary conditions. In this paper, when investigating the behavior of rock structures under dynamic load numerically, the effects of boundary conditions, dynamic load and calculation time step, and dynamic load characteristics on the calculation results were reviewed to provide guidance on setting up boundary conditions and calculation time step related to dynamic analysis.

• Journal of the Earthquake Engineering Society of Korea
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• v.15 no.6
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• pp.19-31
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• 2011

The current Korean criteria for seismic performance evaluated by dynamic analysis regulates that the horizontal displacement and vertical settlement of a dam body, including the static deformation, should be within 1% of the dam height. However, there has been weak theoretical support, so that the current criteria have to be validated. Korea is in a region of low or moderate seismicity located inside the Eurasian plate, and few earthquakes with considerable magnitudes and intensities have been recorded in the area. Therefore, in this study, published data measured in overseas countries were collected in order to construct a database and validate the current criteria. In addition, dynamic centrifuge tests and a parametric study using numerical simulations were performed in order to investigate the effect on the horizontal displacement and settlement of a dam body and to validate the current criteria.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.5
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• pp.635-643
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• 2018

In the present study, influence of earthquake intensity range on seismic fragility analysis of a RC bridge has been evaluated. For this purpose, a RC bridge damaged by a past earthquake has been selected, and analytical model of the bridge has been developed for nonlinear dynamic time-history analysis. A total of 25 recorded earthquake motions have been employed for the nonlinear analysis from which maximum lateral drift ratio of piers are obtained. Then, seismic fragility analysis has been conducted for the bridge using the nonlinear analysis results. Probability of exceeding damage has been computed in terms of using the maximum likelihood estimation, and effect of earthquake intensity range of the motions on seismic fragility curves has been assessed analytically. Analytical predictions indicate that the earthquake intensity range is of utmost significance for rationale seismic fragility analysis reflecting a physical damage state of a bridge and seismic performance evaluation of such bridge.