• The Journal of the Acoustical Society of Korea
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• v.43 no.3
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• pp.335-343
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• 2024

This paper came up with the theoretical modelling of the metrology for the acoustic power using ultrasonic radiation force and showed some theoretical results. In order to do this, a scattering model for a rigid circular cone based upon the Kirchhoff approximation was made, which was followed by the calculation of acoustic power, and then, was converted to the radiation force. From these works, it provided the accuracy and limitation of the conventional method using a circular cone, and the expanded metrology modelling that can be applied to a circular cone with arbitrary apex angle. Using these, this study provided the dependence of the metrology for the acoustic power using ultrasonic radiation force on the frequency and the size of the target. As a result, the correction was yielded in the value of the acoustic power calculated by the suggested International Electrotechnical Commission (IEC) method, which needs to be added when the frequency and the size of the target was considered.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2000.11a
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• pp.419-427
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• 2000

The 4 by 4 microstrip phased array antenna designed and radiation characteristics are studied. The design frequency was chosen to be 5.8GHz. Chebyshev ratio was achieved by unequal power divider and Wilkinson power divider. The ratio of current at each port is 1 : 2.6 : 2.6 : 1 and then side lobe level is less than -30 dB. It is shown that the radiation beam direction can be changed up to 30。 by control the phase at each port. The result can be used to design electrically controllable microwave scanning antennas.

• Proceedings of the KSR Conference
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• 2004.06a
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• pp.658-663
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• 2004

The interaction between a vibrating structure and a surrounding acoustic medium determines the acoustic power propagating into the far-field. A straightforward method to reduce the radiated power is to reduce the vibration of the structure. However it is more efficient to control the modes of the structure separately since each vibration mode of the structure has different radiation efficiency. An efficient method to reduce the sound radiation in the low frequency region is proposed by reducing the radiation efficiency of the structure.

• Nuclear Engineering and Technology
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• v.7 no.2
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• pp.159-165
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• 1975

The Nuclear power industry today faces a serious and rapidly emerging problem in reactor maintenance and occupational radiation exposure control. The basic problem is the need for much maintenance on nuclear power plants. The problem is seriously compounded by radiation exposure control requirements. Many studies are underway seeking solutions tut the industry is developing rapidly and new plants will not await the results of such studies. It is essential that attention be given to maintenance and exposure control in all phases of plant design, construction and operation.

• The Korean Journal of Health Service Management
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• v.13 no.3
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• pp.137-147
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• 2019

Objectives: This study aimed to identify the relationship between thoughts and psychological anxiety about nuclear power among Busan residents. Methods: Convenience sampling was used for this cross-sectional survey conducted from February 13 to 14, 2016. A total of 520 residents participated in the study and completed a self-administered questionnaire. Results: We found a significant association between negative thoughts and psychological anxiety about nuclear power. People older than 60 years (odds ratio (OR) 2.53, 95% confidence interval (CI) 1.41-4.54), who feared the possibility of radiation accidents (OR 1.75, 95% CI 1.17-2.62), considered nuclear power plants unsafe (OR 1.94, 95% CI 1.10-3.40), and believed the Gori nuclear power plant in Busan must be shut down (OR 1.84, 95% CI 1.22-2.79), had the highest anxiety about radiation exposure. Conclusions: The authors suggest the need for the formulation of a policy to provide people with precise information on nuclear power to increase their understanding and help eliminate unfounded negative thoughts. Furthermore, policy decisions about nuclear power must be based on social consensus.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2002.11a
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• pp.340-343
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• 2002

Electromagnetic(EM) radiation problems and their possible solutions are addressed in this paper for the split power plane of high-speed digital systems. Stitching and decoupling capacitors are proved to be very effective fur reducing signal noise, ground bounce as well as electromagnetic radiation from the split power plane. Simulations based on 3D-Finite Difference Time Domain (FDTD) method are utilized for the analysis of practical high frequency multi-layered PC main board

• Journal of the Korean Society of Safety
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• v.13 no.1
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• pp.34-39
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• 1998

This paper describes a evaluation method of sound power radiated from the vibrating faces of a single stage gear box using sound radiation. The vibration caused from meshing gears is transmitted to the gear box faces through shafts and bearings. A Boundary Element Method (BEM) is developed to calculate the sound power radiated from the faces with their velocity response which is based on the Building Block Approach (BBA). Radiation efficiency as well as the sound intensity on the surface of the gear box is also calculated. Sound power of the gear box is larger in the case that bearings have offset to the wall of the gear box than that bearings are on the center of the gear box. The sound power increases with the augmentation of the offset.

• International Journal of Automotive Technology
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• v.2 no.1
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• pp.33-38
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• 2001

The noise generated from a treadband mechanism of a tire has been the subject of this research. In particular, the treadband has been treated as an infinite tensioned beam resting on an elastic foundation which includes damping. The main objective is here to predict the sound power generated from a system mentioned above by locating harmonic point forces representing the excitation of treadband at the contact patch. It is possible to predict the sound power radiated from this structure by wavenumber transformation techniques. To find out the minimum radiated sound power, All parameters were varied. Thus this model can be used as a tire design guide for selecting parameters which produce the minimum noise radiation.

• Nuclear Engineering and Technology
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• v.30 no.4
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• pp.308-317
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• 1998

Ensuring occupational radiation exposure(ORE) as low as is reasonably achievable(ALARA) has been one of very important requirements in a nuclear power plant. It is well known that about 70 percent of occupational dose has incurred from maintenance jobs in the outage period. To reduce occupational dose effectively, the high-dose jobs in the outage period should be identified with their dose reduction potentials and methods. In this study, a PC-based ORE database program, INSTORE, is developed to evaluate ORE doses in individual jobs, and the ORE data of Kori Units 3 and 4 are assembled to the database. Based on customary job classification, radiation work is classified into 26 main jobs which comprise 61 detailed jobs, and occupational doses are assessed according to each detailed job. As a result, high-dose jobs are identified with dose reduction priority in terms of collective ORE dose. It is recommended that adeqaute dose reduction methods for these jobs should be prepared to improve their working conditions and procedures.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.12
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• pp.173-179
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• 1995

This paper descrived housing design in conception of dynamic characteristics. The vibration and noise in power train system of automobile are important on the environment matter. The vibration caused by meshing teeth of gear is transmitted to the gear box faces through shafts and bearings. Shape of housing is used different radius of curvature(R=0 to 80 mm). The velocity responese, sound power and radiation efficency on the surface of gear box are calculated. The sound power and radiation efficency are compared with different radius of curvature.