• The Transactions of the Korean Institute of Power Electronics
• /
• v.5 no.3
• /
• pp.229-237
• /
• 2000

본 논문에서는 멀티브리지 인버터로 구성된 SSSC를 제안하였다. SSSC의 동적특성을 분석하기 위해서 1기 무한모선 전력계통에 SSSC를 연결한 것을 가정하고 EMTP 시뮬레이션을 수행하였고, 축소모형 실험으로 그 특성을 확인하였다. 다중브리지 SSSC는 한 상당 6개의 단상 풀브리지 인버터로 구성되었고, 13-레벨 출력전압을 얻을 수 있다. 다중브리지 SSSC는 전압 주입을 위한 연계 변압기가 필요하기 않고, 전력계통에서 요구되는 동작전압에 따라 브리지 수를 가감하여 용이하게 구성할 수 있다.

• Proceedings of the Korean Society of Computer Information Conference
• /
• 2009.01a
• /
• pp.423-427
• /
• 2009

웹 2.0시대를 맞이하여 사용자가 콘텐츠 및 동영상을 직접 만들어 참여하고 공유하는 방향으로 바뀌었고 각종 포털사이트에서도 동영상 사이트를 제공함으로써 동영상 UCC가 대중화될 수 있는 계기가 되었다. 본 논문에서는 동영상 UCC를 만들기 위해 제작, 편집, 등 프로그램 특성에 따라 효율적인 효과를 거둘 수 있을지 몇 가지 프로그램에 관해 편집 편리성, 제작 파일의 크기, 렌더링 소요 시간, 등을 사진 콘텐츠를 이용하여 비디오 전환 효과, 비디오 효과, 사운드 등을 이용하여 프로그램에 따른 장단점을 비교하였다. 프로그램 별로 실험 성능 평가 및 분석한 결과 무비메이커와 베가스 프로그램들이 비 전문가로서 전문가 못지않은 손쉽게 동영상 콘텐츠제작 및 동영상 UCC를 만들 수 있는 좋은 프로그램으로 여러 장점들을 갖고 있음을 나타내었다.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.10 no.5 s.51
• /
• pp.107-115
• /
• 2006

The power supply system is one of the most important infrafacilities which should maintain their inherent function during and after earthquakes. This study was performed to analyze dynamic characteristics and seismic performance of Korean typical 154kV transformer porcelain bushing. For the purpose of this study, actual 154kV porcelain bushings were selected and tested on the shaking table. The vibration tests consist of modal identification tests, seismic performance tests, and fragility tests. The sine sweep waves, artificial earthquake waves, and continuous resonant sine waves were used as shaking table motions. This paper describes the test specimens, shaking facilities, and test methods. Natural frequencies and damping ratios of the bushing have been evaluated from the experimental data. The failure mode and the performance level of the Korean transformer bushing have been first identified in this study.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.15 no.6
• /
• pp.11-18
• /
• 2011

Accurate modal identification analysis is required to reasonably perform a seismic qualification of safety-related electric equipment installed in nuclear power plants (NPPs). This study evaluates a variation of the modal properties of an electric equipment cabinet structure in NPPs according to the excitation levels. For the study, an actual electric equipment cabinet was selected as a specimen and was dynamically tested by using a portable exciter in accordance with the level of input vibration energy. Tests were classified into two sets: with-door cases, and without-door cases. Frequency response functions were computed from the signals of the acceleration responses and input motions measured from the vibration tests. A polynomial curve fitting algorithm was used to extract the modal properties from the frequency response functions. This study reviews the variation of the modal properties according to the variation of the excitation levels. The results of the study show that the modal frequencies and the modal dampings of the object specimen varies nonlinearly according to the excitation level of the test motion. Attaching the door increases the modal damping of the cabinet.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.49 no.1
• /
• pp.31-40
• /
• 2021

Modern aircraft are high-performance and lightweight. Thus, the characteristics of the flexible structure appear and affect flight performance or limit it. These flexible characteristics need to be analyzed from the early stages of aircraft design. To this end, a program to analyze the dynamic and static behavior of flexible aircraft has been developed and the results are presented. Based on the multi-body dynamics simulation technique, rigid flight mechanics, structural vibrating behavior, and unsteady aerodynamics have been developed and integrated. Lastly, the level flight and the turn flight of the flexible characteristic aircraft have been analyzed using this integrated simulation program.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.7
• /
• pp.38-45
• /
• 2020

A magnetically levitating capsule train, which runs inside the sub-vacuum tube, can reach ultra-fast speeds by dramatically reducing the aerodynamic drag and friction. The capsule train uses the superconductor electrodynamic suspension (SC-EDS) method for levitation. The SC-EDS method has advantages, such as a large levitation gap and free of gap control, which could reduce the infra-construction cost. On the other hand, disadvantages, such as the large variation of the levitation-guidance gap and small damping characteristics in levitation-guidance force, could degrade the running stability and ride comfort of the capsule train. In this study, a dynamic analytical model of a capsule train based on the SC-EDS was developed to analyze the running dynamic characteristics. First, as important factors in the capsule train dynamics, the levitation and guidance stiffness in the SC-EDS system were derived, which depend non-linearly on the velocity and gap variation. A 3D dynamic analysis model for capsule trains was developed based on the derived stiffness. Through the developed model, the effects of the different running speeds on the ride comfort were analyzed. The effects of a disturbance from infrastructure, such as the curve radius, tube sag, and connection joint difference, on the running stability of the capsule train, were also analyzed.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.29 no.4
• /
• pp.301-308
• /
• 2016

In this study, a novel method referred as non-marker vision-based displacement measuring system(NVDMS) was introduced in order to measure the displacement of structure. There are two distinct differences between proposed NVDMS and existing vision-based displacement measuring system(VDMS). First, the NVDMS extracts the pixel coordinates of the structure using a feature point not a marker. Second, in the NVDMS, the scaling factor in order to convert the coordinates of a feature points from pixel value to physical value can be calculated by using the external conditions between the camera and the structure, which are distance, angle, and focal length, while the scaling factor for VDMS can be calculated by using the geometry of marker. The free vibration test using the three-stories scale model was conducted in order to analyze the reliability of the displacement data obtained from the NVDMS by comparing the reference data obtained from laser displacement sensor(LDS), and the measurement of dynamic characteristics was proceed using the displacement data. The NVDMS can accurately measure the dynamic displacement of the structure without the marker, and the high reliability of the dynamic characteristics obtained from the NVDMS are secured.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.4 no.1
• /
• pp.77-83
• /
• 2000

구조물의 동특성은 대형구조물을 상시감시 할 수 있는 장점으로 인하여 널리 활용된다. 상시감시를 위해 계측된 랜덤 데이터는 FFT를 통한 구조물의 동적 고유특성을 분석함으로써 이루어진다. 이 과정에서 Input Data와 Response Data사이에서 FFT Analyzer를 통하여 FRF가 측정된다. 특히 랜덤 데이터의 계측은 여건과 환경에 따라 발생하는 Noise로부터 가능한 정확한 FRF를 계측해야만 성공적인 구조물의 고유의 동적특성을 파악하게 된다. 랜덤 데이터에서 발생할 가능성이 높은 입력, 출력 Noise를 동시에 최소화 할 수 있는 새로운 개념의 FRF측정 알고리즘을 제안한다. 이 알고리즘에 의하여 장대형 모형교량으로부터 Modal 실험을 수행하여 계측된 동특성을 FE 해석 결과와 비교 평가하여 유용성을 제시한다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 1994.10a
• /
• pp.205-209
• /
• 1994

본 연구에서는 오디오용 데크의 음질특성과 벨트구동계의 회전진동 특성과의 연관성을 규명하고자 한다. 이를 위해 벨트구동계를 다자유도 진동계로 모델링하여 회전진동 특성을 규명하고 실험으로 확인하였다. 이의 결과를 실제 데크에 응용하기 위해 각 파라미터의 변화에 따른 특성변화의 경향을 살펴보았으며, 당사에서 개발중인 신모델에서 회전비의 적절한 설계를 제안하여 우수한 음질특성을 확인하였다.

• The Journal of the Korea Contents Association
• /
• v.16 no.3
• /
• pp.11-21
• /
• 2016

Recently, structure safety management techniques using cutting-edge technology(Displacement senor, sensor of acceleration) has emerged as an important issue owing to the aging of infrastructure such as bridge and building. In general, the structural monitoring system for structure safety management is based on IT technology and it is expensive to install. In this paper developed an image-based structure dynamic characteristic analysis system prototype to assess the damage of structure in a more cost-effective way than traditional structure health monitoring system. The inspector can take a video of buildings or other structures with digital camera or any other devices that is passible to take video, and then using NCC calculation for image processing technique to get natural frequency. This system is analysis of damage of the structure using a compare between the frequency response ratio and functions when problems are occurs send alarm to administrator. This system is easier to install and remove than previous monitoring sensor in economical way.