• Journal of Radiation Protection and Research
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• v.18 no.1
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• pp.37-51
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• 1993

A standard radon chamber and a radon generator adjusted by ventilation system which had used in this research were assumed to calculate theoretically the concentration of radon progeny using Jacobi model theory. On the one hand, the filter sampled from the radon standard chamber and the radon generator was measured and analysed by the alpha spectrometry method. It is clear that measured result shows a good agreement with theoretical result. Therefore, it is observed that this research can made a great contribution to more accurate internal dose assessment by alpha emission of radon progeny in indoor radon environment, and fast individual measurement and determination of concentration for radon progeny.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.68 no.1
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• pp.1-7
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• 2019

Due to the highly concentrated power plants integrated through the limited transmission lines in Korea, a Special Protection System(SPS) has been applied to stabilize the power systems by instantly tripping the pre-determined generators in a large-scaled power plant when a fault occurs on the drawing transmission lines. Moreover, power outputs of those generators are constrained to avoid any activation of Under Frequency Load Shedding(UFLS) even after those generators are tripped by SPS action. For this, this paper proposes a method for calculating the required capacity of Energy Storage System(ESS) expected to relieve the operating constraints to generators using its fast response for controlling power system frequency. The proposed method uses the generator acceleration energy to derive the stable condition during the SPS action. In addition, its effectiveness is verified by the case studies adopting actual SPS operations in Korean power systems.

• Journal of Radiation Protection and Research
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• v.34 no.4
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• pp.176-183
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• 2009

Maintenance on the water chamber of steam generator during outage in nuclear power plants (NPPs) has a likelihood of high radiation exposure to whole body of workers even short time period due to the high radiation exposure rates. In particular, it is expected that hands would receive the highest radiation exposure because of its contact with radiation materials. In this study, characteristic analysis of inhomogeneous radiation fields for contact operations was conducted using thermoluminescent dosimeter (TLD) readouts from the application tests of two-dosimeter algorithm to Korean NPPs in 2004. It is regarded that inhomogeneous radiation fields for contact operations in NPPs are dominated by high energy photons. In addition, field tests for workers who participated in maintenance on the steam generator during outage at Ulchin NPPs in 2009 and pressure tube replacement at Wolsong NPPs in 2009 were conducted to analyze radiation fields and to estimate the extremity dose. As a result, radiation fields were dominated by high energy photons.

• Journal of Radiation Protection and Research
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• v.44 no.2
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• pp.72-78
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• 2019

Background: In the calibration and testing laboratory of Korea Atomic Energy Research Institute, the old X-ray generator used for the production of reference X-ray fields was replaced with a new one. For this newly installed X-ray irradiation system, beam alignment as well as the verification of beam qualities was conducted. Materials and Methods: The existing X-ray generator, Phillips MG325, was replaced with YXLON Y.TU 320-D03 in order to generate reference X-ray fields. Theoretical calculations and Monte Carlo simulations were used to determine initial filter thickness. Beam alignment was performed in three steps to deliver a homogeneous radiation dosage to the target at different distances. Finally, the half-value layers were measured for different X-ray fields to verify beam qualities by using an ion chamber. Results and Discussion: Beam alignment was performed in three steps, and collimators and other components were arranged to maintain the uniformity of the mean air kerma rate within ${\pm}2.5%$ at the effective beam diameter of 28 cm. The beam quality was verified by using half-value layer measurement methods specified by American National Standard Institute (ANSI) N13.11-2009 and International Organization for Standardization (ISO)-4037. For each of the nine beams than can be generated by the new X-ray irradiation system, air kerma rates for X-ray fields of different beam qualifies were measured. The results showed that each air kerma rate and homogeneity coefficient of the first and second half-value layers were within ${\pm}5%$ of the recommended values in the standard documents. Conclusion: The results showed that the new X-ray irradiation system provides beam qualities that are as high as moderate beam qualities offered by National Institute of Standards and Technology in ANSI N13.11-2009 and those for narrow-spectrum series of ISO-4037.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.50 no.11
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• pp.506-513
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• 2001

The islanding detection for distributed resources (DR) becomes an important and emerging issue in power system protection since the distributed generator installations are rapidly increasing and most of the installed systems are interconnected with distribution network. In order to avoid the negative impacts from islanding operations of DR on protection, operation and management of distribution system, it is necessary to effectively detect the islanding operations of DR and rapidly disconnect it from distribution network. Generally, it is difficult to detect islanding operation by monitoring only one system parameter This paper presents a new logic based islanding detection method for distributed resources(DR) which are interconnected with distribution network. The proposed method detects the islanding operation by monitoring four system parameter: voltage variation, phase displacement, frequency variation, and the variation of total harmonic distortion(THD) of current; therefore, it effectively detects island operation of DR unit operating in parallel with the distribution network. We also verified the efficiency of the proposed algorithm using the radial distribution network of IEEE 34 bus model.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.1
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• pp.90-94
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• 2009

The inundation of substation and ground power equipment breaks out every summer season in low-lying downtown and low-lying shore by localized heavy rain, typhoon and tidal wave. For diminishing flood damage of electrical equipment in the root, flood protection system which is used the basic frame of Pad transformer is developed using pneumatic pressure. This system is established on pressure generator equipment and sensor of flooded level operates at flooding occurrence and is maintained a shutting tightly structure. The system is able to protect indraft water in Pad Transformer and supply the electricity at emergency(flooding). And we tested safety for insulation resistance at flooding and applying an electrical current. We estimate that loss cost which is caused by with flooding and the power failure will be diminished if it is addition to advances the reliability evaluation by setting an example.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.516-518
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• 2005

This paper presents a distance protection algorithm a lied to the linked line for interconnecting wind farm with the utility. The capacity of wind farm is lower than utility system and its fault current level is very low. When a high resistance fault occurs in the linked line, it is difficult to detect accurate fault distance because of reactance effect. By using the characteristic of equivalent source impedance of induction generator which is compensated by capacitor bank and characteristic of the capacity of wind farm, this paper proposes improved distance protection algorithm applied to the linked line. A series of PSCAD/EMTDC simulation results have shown effectiveness of the proposed algorithm.

• Proceedings of the KIEE Conference
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• 2006.11a
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• pp.300-301
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• 2006

최근 전력계통(Power system)은 대형화, 고용량화됨에 따라 전력계통의 안전적으로 운용에 대한 제어가 점점 커지고 있다. 그로인한 각종 사고 시 전력 계통을 보호하기 위한 보호계전기(Protection relay)의 중요성은 나날이 커져가고 있다. 기존의 전력계통용 모니터링 시스템은 사고 순간의 데이터를 분석하여 사고원인을 알아내기는 어려운 점이 많이 있다. 그리하여 본 논문에서는 실시간으로 보호계전기용 모니터링 시스템을 설계하였다. 분산전원에 적용하여 계통 사고에 대해서 제어, 보호 등의 안정적인 시스템을 설계하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.05a
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• pp.480-483
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• 2000

We developed a home electric panel board with surge protection device to protect home electric appliances from transient overvoltages and electromagnetic(EM) noise. In this paper, electrical characteristics of the home electric panel board are described. From the performance test using a combination surge generator standardized in IEC 610004-5, it is confirmed that the proposed home panel board has an excellent surge protection performance. Also, EM noise reduction characteristics of the panel board in ranges from 150 kHz to 30 MHz is estimated by using a network analyser, and the results showed that the panel board has an over 20 45 noise reduction performance.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.05a
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• pp.489-492
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• 2000

This paper describes a new transient voltage suppressor(TVS) with a low insertion loss and a very wide frequency bandwidth to protect antenna circuit from transient voltages. Conventional protection devices have some problems such as low frequency bandwidth and high insertion loss. In order to improve these limitations, a coaxal type TVS, which consists of a gas tube is developed. The performance of the proposed transient voltage suppressor is tested by using a combination surge generator specified in IEC 61000-4-5 standard and by using a network analyzer of 40 MHz ∼ 5GHz bandwidth. From the experimental results, it is confirmed that the proposed TVS has an enough protection performance in low insertion loss and in wide frequency bandwidth