• 한국강구조학회 논문집
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• 제15권2호
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• pp.117-124
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• 2003

고층건물의 사용성설계는 가속도와 같은 풍응답진동에 의하여 자주 영향을 받으므로, 이때 고유진동수의 올바른 산정은 중요하다. 설계단계에서 사용되고 있는 이러한 진동수 경험식들은 상호간에 서로 다른 결과치를 제시하는 경향이 있다. 이 논문은 철골조 건물의 진동주기에 대한 것으로서, 건물의 진동실험방법과 상시진동실험에서 얻은 고유주기를 예측하기 위한 방법을 제시하였다. 서울지역 21개동의 상시진동 계측데이터에서 고유주기를 산정하였다. 철골조 고층건물의 고유주기 근사식을 제안하였으며, 고유주기의 근사식을 국내외 기준 및 고유치해석의 결과와 비교하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.1029-1033
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• 2006

During operation of generator, the excitation force with 120Hz always exist irrespective of No. of poles. Therefore the vibration is generated in the stator end windings and the micro-crack is grown up inside the bars. After all, coolant water is leaked outside the bars or the stator is moved and is worn out. What is more, one bar is touched with another bar so a short circuit may frequently happen in operation. In order to prevent it from occurring, the evaluation of mechanical integrity for generator stator windings is carried out periodically during overhaul period. This help troublesome end windings to complement with insulation material and to change vibration characteristics. In this paper, the evaluation of mechanical integrity for generator stator windings is described and the change of vibration characteristics is analysed.

• 한국소음진동공학회논문집
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• 제24권10호
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• pp.809-816
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• 2014

This paper presents a systematic optimization process for designing an electromagnetic vibration energy harvester using FEA(finite element analysis) to improve computational accuracy and efficiency. A static FEA is used in the optimization process where trend analysis in a short period of time is rather important than precise computation, while a dynamic FEA is used in the verification step for the final result where precise computation is more important. An electromechanical transduction factor can be calculated efficiently by using an approach to use the radial component of magnetic flux density directly instead of an approach to compute the flux density gradient. The proposed optimization process was verified through a case study where simulation and experiment results were compared.

• Advances in concrete construction
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• 제8권2호
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• pp.77-90
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• 2019

This paper aims to investigate vibration frequency decrease (vibration period elongation) of reinforced concrete (RC) structure with unreinforced infill wall and reinforced infill wall exposed to progressively increased artificial earthquake load on shaking table. For this purpose, two shaking table experiments were selected as a case study. Shaking table experiments were carried on 1:1 scaled prototype one bay one storey RC structure with infill walls. The purpose of this shaking table experiment sequence is to assess local behavior and progressive collapse mechanism. Frequency decrease and eigen-vector evolution are directly related to in-plane and out-of-plane bearing capacities of infill wall enclosure with reinforced concrete frame. Firstly, frequency decrease-damage relationship was evaluated on the base of experiment results. Then, frequency decrease and stiffness degradation were evaluated with applied Peak Ground Acceleration (PGA) by considering strength deterioration. Lastly, eigenvector evolution-local damage and eigenvector evolution-frequency decrease relationship was investigated. Five modes were considered while evaluating damage and frequency decrease of the tested specimens. The relationship between frequency decrease, stiffness degradation and damage level were presented while comparing with Unreinforced Brick Infill (URB) and Reinforced Infill wall with Bed Joint Reinforcement (BJR) on the base of natural vibration frequency.

• 대한의료기공학회지
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• 제20권1호
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• pp.15-67
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• 2020

Objective : The purpose of this study is to identify the trends of vibration(or wave) therapy in Korea, to actively utilize vibration(or wave) therapy, and to help research activities of vibration therapy in Korean Medicine. Methods : The following Korean words "진동기", "진동요법", "진동운동", "진동치료", "파동요법", "파동운동", "파동치료" were searched on three specialized search sites (RISS, NAL, DBpia). Trends of vibration therapy were analyzed through the selected researches suitable for this study among these searched researches in an overview format. Results : 1. A total of 8,116 studies were searched and a total of 365 studies were finally selected 2. From 2000 to 2019, when research began to increase in earnest, there were 17.45±10.28 studies per year, and the AGR(Average Annual Growth Rate) was 11.92%. 3. In the main field of research, the 'Medicine and Pharmacy' was the largest with 147(40.16%) studies. In the Middle Field, the 'Kinesiology' was the largest with 99(27.05%) studies. In the study design, 'RCT(Randomized Controlled trial)' was the largest with 138(47.75%) studies. In the Age Group, 'Youth' was the largest with 126(48.84%) studies. 4. The average of the number of participants was 24.90±17.44. 5. The most used Intervention was the 'WBV(Whole Body Vibration)' with 177(61.25%) studies. 6. The average of Intervention Period was 5.99±4.14 weeks, while the maximum was 36 weeks. 7. The journal that published the most research papers is 'K. J. of Sports Science(체육과학연구;13)', and the society is 'Rehabilitation Engineering And Assistive Technology Society of Korea(한국재활복지공학회; 14)'. The University that published the most dissertations is 'Sahmyook University(11)'. 8. The authors who published the most studies are Ju-Hwan O(8) as the main author and Tae Kyu Kwon(18) as the co-author (including the thesis Director). In an integrated analysis of the authors and co-authors, Tae Kyu Kwon published the most numerous studies(19) Conclusions : 1. The study of vibration or wave therapy has been increasing noticeably every year. 2. The major academic Fields studying vibration or wave therapy are the 'Kinesiologic Field', 'Physical Therapy Field', and 'Biomedical Engineering Field'. 3. The most chosen method of study design on vibration or wave treatment was 'RCT', and there was no significant change in the annual presentation rate. 4. Types of vibration or wave therapy could be classified as 'LVS(Local Vibration Stimulation)', 'WBV(Whole Body Vibration)', 'MV(Micro Vibration)', 'BV(Bio Vibration)' and 'SWV(Sound Wave Vibration)', and the study on Whole Body Vibration is most active. 5. Most of the studies of vibration or wave therapy were on musculoskeletal systems, but there were very few studies on internal diseases.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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• pp.689-694
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• 2001

Until now, various period formulas Pre proposed, but those of have a little difficult procedure and variation according to structural system. This paper presents an analysis of the uncoupled vibration of symmetric in RC structures. A generalized approximate method is developed using the Southwell-Dunkerley approximation and characteristics of structural deformation. The results of the proposed method for the example structure show good agreement with those of the Midas Genw4.2.2.

• 한국자동차공학회논문집
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• 제18권2호
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• pp.97-103
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• 2010

The four combustion stages in a diesel engine have close correlation among them. Especially, the ignition delay period has significant effect on the following combustion stage. And the period is also one of inevitable combustion processes in the diesel engine. For example, the diesel knocking is a well-known phenomenon due to the long ignition delay period. The interval of the ignition delay period is affected by the mixture formation process in the cylinder. However, in the case of the D.I. diesel engine, the available duration to make the mixture formation of air-fuel is very short. In addition, the means of the mixture formation mainly depends on the injection characteristics and properties of the fuel. It is difficult to make complete mixture. Therefore, an early stage of combustion is violent, which leads to the weakness of noise and vibration. In this study, using the visible engine, we measured the ignition delay period by photo sensor which detect occurrence of flame and presented the factors of the injection characteristics such as kinds of injection system, the injection pressure and the injection timing. The relation between the ignition delay period and cylinder pressure diagram which was concurrently obtained was also estimated.

• Smart Structures and Systems
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• 제11권5호
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• pp.453-476
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• 2013

DuraMote is a remote sensing system developed for the "NIST TIP project: next generation SCADA for prevention and mitigation of water system infrastructure disaster". It is designed for supervisory control and data acquisition (SCADA) of ruptures in water pipes. Micro-electro mechanical (MEMS) accelerometers, which record the vibration of the pipe wall, are used detect the ruptures. However, the performance of Duramote cannot be verified directly on a water distribution system because it lacks an acceptable recordable level of ambient vibration. Instead, a long-span cable-stayed bridge is an ideal test-bed to validate the accuracy, the reliability, and the robustness of DuraMote because the bridge has an acceptable level of ambient vibration. The acceleration data recorded on the bridge were used to identify the modal properties of the structure and to verify the performance of DuraMote. During the test period, the bridge was subjected to heavy rain, wind, and a typhoon but the system demonstrates its robustness and durability.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1993년도 Proceedings of International Conference for Agricultural Machinery and Process Engineering
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• pp.1117-1126
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• 1993

Physical parameters in the forward direction of the tractor , which mainly affects the vibration characteristics of the tractor dynamic model, were able to be identified in a short time by using the Gauss-Newton method with extremum searching based on the data obtained from a forced vibration experiment. It was clarified that a period for the updating of the parameter estimates method has effects on the convergence accuracy of identification for the spring constant in the forward direction of the tractor.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1994년도 Proceedings of the Korea Automatic Control Conference, 9th (KACC) ; Taejeon, Korea; 17-20 Oct. 1994
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• pp.593-596
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• 1994

When a force impulse acting on a massive and plex object is measured with a dynamometer, be resonant vibration of the measurement system often leads to serious inaccuracies. A more accurate measurement is obtained when the transfer function ,of the object-dynamometer system is used to compensate for the error in the dynamometer's output signal. The natural frequency and the damping coefficient of the transfer function are estimated by analyzing the waveform of the free damped vibration period after the loading of the force has ended. The residue of the system is determined such that the compensated force spectrum becomes smooth within a neighborhood of the natural frequency. The effectiveness of this signal processing method is experimentally tested on a hammer impulse, under the assumption that the hammer's high resonant frequency accurately models the problems encountered in force impact measurement. The compensation method is used to derive a improved estimate of the hammer impulse.