• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.7
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• pp.650-656
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• 2011

The noise inside a naval vessel is very important in considering the need for hearing protection, improving the working environment and maintaining good communications for crews living on board a naval vessel. The indoor noise of a ship usually is specified by the A-weighted sound pressure level, but other evaluating parameters are required to reflect human senses more effectively. This paper uses additional noise indices related to room acoustics, such as NR(noise rating), NC(noise criterion), RC(room criterion), PSIL(preferred speech interference level) and loudness level to evaluate the noise inside cabins on a naval vessel. Using these psychological noise indices, allowable limit of noise level in cabins is suggested through psycho-acoustic evaluation for the noise in cabins.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.10a
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• pp.563-563
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• 2013

Railway noise has been a social issues nowadays in our community. This paper discusses the environmental noise problem along railway lines. We overview the noise level and noise exposed populations due to conventional and high speed train operation at first. Then we introduce variety of noise reduction schemes to protect the community based on an engineering approach. Some applicationcases to reduce the noise will be demonstrated. Finally, we propose the noise barrier tunnel as a tool of a generic solution to reduce the community noise along railway lines.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.25-32
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• 2005

In China, environmental noise policies are composed of correlated laws adopted by the Standing Committee of the National People's Congress and promulgated by the President of the country, regulations promulgated by the State Council and/or local government, standards issued by the Standardization Administration Committee (SAC) under the State Council. The laws mainly include the 'Environmental Protection Law' and the 'Law on Prevention and Control of Pollution From Environmental Noise' Regulations are often applied to a special noise pollution phenomenon of wide influence. They are generally only effective in a given area and/or a specific period. Tens of correlated standards specify the noise level limits of different functional zones of land use and of different equipment, machines, devices, appliances etc., and the measurement methods. In this presentation, a brief introduction to these policies and their operations is given and discussed. The conclusion is that the policies supply an effective legislative basis for environmental noise prevention and control in China, but still a lot of work should be conducted and completed to strive for a quiet society.

• 한국터널공학회:학술대회논문집
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• 2005.04a
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• pp.63-74
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• 2005

The environmental influence in tunnel construction is the drying of the ground water, the drop of the ground water level, and noise and vibration by tunnel excavation. The environmental influence can cause the change of natural ecosystem and the source of popular complaints. In case of popular complaints, the tunnel construction can be stopped or the construction period can be extended. Also, the financial loss may be reached to hundreds of billions won. The technology development to minimize the environmental influence in the tunnel construction is very important in order to control popular complaints and to preserve ecosystem. It should be required the investigation, the evaluation, and the assessment of environmental impact to reduce environmental influence in the tunnel construction. The objective of this research is to review the environmental impact assessment in Korea and to introduce the environmental protection technology which minimizes the environmental influence generated in the tunnel construction.

• Current Photovoltaic Research
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• v.2 no.3
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• pp.84-87
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• 2014

Protection of solar cell surface is important to prevent from dust, pollen, sand, etc. Therefore, development of large area antifouling film is urgent for high performance of solar cells. The surface of silica spheres was modified to fabricate large area antifouling film. The surface of monodisperse silica spheres has been modified with 3-(trimethoxysilyl) propylmethacrylate (TMSPM) to fabricate large area photonic crystal. Although the surface modification of silica spheres with TMSPM has been failed for the base catalyst, the second trial using acid catalyst showed the following results. The FTIR absorption peak at $1721cm^{-1}$ representing C=O stretching vibration indicates that the TMSPM was attached on the surface of silica spheres. The methanol solution comprised of the surface modified silica spheres (average diameter of 380 nm) and a photoinitiator was poured in the patterned silicon wafer with the dimension of 10 cm x 10 cm and irradiated UV-light during the self-assembly process. The result showed large area crack and defect free nanostructures.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.6
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• pp.381-386
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• 2017

A railway track generates severe levels of vibrations. In order to reduce these vibrations and to provide structural stability, various rail pads, mats, etc., are used for vibration protection. In this study, a specially designed rail pad was developed to reduce vibration and to generate electric power simultaneously, that is, by using the vibrations generated by railway cars on the track. The newly developed rail pads were tested to evaluate the characteristics of electric power by investigating the generated voltage and the current levels and patterns. In addition, we proposed an optimal laminated structure and adhesive by comparing the voltage generated by each type of adhesive required for optimal adhesion of the rail pad and the piezoelectric device.

• Journal of Power System Engineering
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• v.16 no.1
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• pp.19-23
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• 2012

This thesis is the result of conducting an analysis to find the solution to the phenomenon of power stoppage due to the disconnection of a CT (Current Transformer) because of vibration. The CT which measures the most essential current is used in power industries as part of a generator protection relay. When it comes to the bottom plate of a CT, nonconductor; such as bakelite and laminates; these material elements should be used because it is impossible to utilize the conductor when measuring the current of a generator which carries a high current if you use other materials. These nonconductor's material properties are irregular and interpretation errors often occur because the weight is light. In addition, since the change of dynamic characteristics which are related to the temperature often occur, it is important to match the real situation by considering an error of interpretation rather than selecting the quality of the material. Lastly, the conclusion that the study drew is that it is possible to avoid the resonance by utilizing three changes to the components to solve the problem concerning the high vibration which is caused by non-conductive objects. These changes are the most crucial points in this thesis: First, material changes to the Plate. Second, weight changes to the Coil. Third, thickness changes to the Plate.

• Smart Structures and Systems
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• v.33 no.1
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• pp.27-39
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• 2024

The effectiveness of conventional tuned liquid dampers (TLDs) in controlling the wind-induced response of tall flexible structures has been indicated. However, the impaired control effect in the detuning condition or a considerably high mass cost of liquid may be incurred in ensuring the high-level serviceability. To provide an efficient TLD-based solution for wind-induced vibration control, this study proposes a serviceability-oriented optimal design method for isolated TLDs (ILDs) and derives analytical design formulae. The ILD is implemented by mounting the TLD on the linear isolators. Stochastic response analysis is performed for the ILD-equipped structure subjected to stochastic wind and white noise, and the results are considered to derive the closed-form responses. Correspondingly, an extensive parametric analysis is conducted to clarify a serviceability-oriented optimal design framework by incorporating the comfort demand. The obtained results show that the high-level serviceability demand can be satisfied by the ILD based on the proposed optimal design framework. Analytical design formulae can be preliminarily adopted to ensure the target serviceability demand while enhancing the structural displacement performance to increase the safety level. Compared with conventional TLD systems, the ILD exhibits higher effectiveness and a larger frequency bandwidth for wind-induced vibration control at a small mass ratio.

• Structural Monitoring and Maintenance
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• v.3 no.1
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• pp.33-49
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• 2016

Structural Health Monitoring (SHM) has been attracting numerous research efforts around the world because it targets at monitoring structural conditions and performance to prevent catastrophic failure, and to provide quantitative data for engineers and infrastructure owners to design a reliable and economical asset management strategy. In the past decade, with supports from Australian Research Council (ARC), Cooperative Research Center for Infrastructure and Engineering Asset Management (CIEAM), CSIRO and industry partners, intensive research works have been conducted in the School of Civil, Environmental and Mining Engineering, University of Western Australia and Centre for Infrastructural Monitoring and Protection, Curtin University on various techniques of SHM. The researches include the development of hardware, software and various algorithms, such as various signal processing techniques for operational modal analysis, modal analysis toolbox, non-model based methods for assessing the shear connection in composite bridges and identifying the free spanning and supports conditions of pipelines, vibration based structural damage identification and model updating approaches considering uncertainty and noise effects, structural identification under moving loads, guided wave propagation technique for detecting debonding damage, and relative displacement sensors for SHM in composite and steel truss bridges. This paper aims at summarizing and reviewing the recent research advances on SHM of civil infrastructure in Western Australia.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.4
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• pp.359-366
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• 2013

This study aims to investigate the characteristics of the flow-induced vibrations of two circular cylinders. The characteristics of the flow-induced vibrations are examined for various flow velocities and spaces between the two cylinders when they are arranged in tandem, staggered, and side-by-side positions. The results are as follows: (i) Seven flow-induced vibration patterns are observed when the two circular cylinders are placed in either tandem, staggered, or side-by-side positions. (ii) The two cylinders induce a vibration because they affect each other. (iii) The easiest way to induce a vibration of the two cylinders is by placing them in the side-by-side position among the three arrangements (tandem, staggered, and side-by-side). (iv) The change in the maximum flow-induced vibration of the two cylinders depends strongly on the fluctuating lift forces of each of them.