• Electrical & Electronic Materials
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• v.11 no.11
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• pp.1-8
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• 1998

This paper presents an arificial neuro-fuzzy technique based prtial discharge (PD) pattern classifier to power system application. This may require a complicated analysis method employ -ing an experts system due to very complex progressing discharge form under exter-nal stress. After referring briefly to the developments of artificical neural network based PD measurements, the paper outlines how the introduction of new emerging technology has resulted in the design of a number of PD diagnostic systems for practical applicaton of residual lifetime prediction. The appropriate PD data base structure and selection of learning data size of PD pattern based on fractal dimentsional and 3-D PD-normalization, extraction of relevant characteristic fea-ture of PD recognition are discussed. Some practical aspects encountered with unknown stress in the neuro-fuzzy techniques based real time PD recognition are also addressed.

• Nuclear Engineering and Technology
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• v.55 no.5
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• pp.1901-1910
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• 2023

The safety-class (1E) digital control system (DCS) of nuclear power plant characterized structural multiple redundancies, therefore, it is important to quantitatively evaluate the reliability of DCS in different degree of backup loss. In this paper, a reliability evaluation model based on T-S fuzzy fault tree (FT) is proposed for 1E DCS of nuclear power plant, in which the connection relationship between components is described by T-S fuzzy gates. Specifically, an output rejection control system is chosen as an example, based on the T-S fuzzy FT model, the key indicators such as probabilistic importance are calculated, and for a further discussion, the T-S fuzzy FT model is transformed into Bayesian Network(BN) equivalently, and the fault diagnosis based on probabilistic analysis is accomplished. Combined with the analysis of actual objects, the effectiveness of proposed method is proved.

• Nuclear Engineering and Technology
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• v.54 no.9
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• pp.3324-3335
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• 2022

Several countries show interest in the Generation-IV power reactor innovative small module (PRISM), including: Canada, Japan, Korea, Saudi Arabia and the United Kingdom. Generation IV International Forum (GIF) has recommended the utilizing of probabilistic safety assessment (PSA) in evaluating the safety of Generation-IV reactors. This paper reviews the PSA performed for PRISM using SAPHIRE 7.27 code. This work shows that the core damage frequency (CDF) of PRISM for a single module is estimated by 8.5E-8/year which is lower than the Generation-IV target that is 1E-6 core damage per year. The social risk of PRISM (likelihood of latent cancer fatality) with evacuation is estimated by 9.0E-12/year which is much lower than the basic safety objective (BSO) that is 1E-7/year. The social risk without evacuation is estimated by 1.2E- 11/year which is also much lower than the BSO. For the individual risk (likelihood of prompt fatality), it is concluded that it can be considered negligible with evacuation (1.0E-13/year). Assuming no evacuation, the individual risk is 2.7E-10/year which is again much lower than the BSO. In comparison with other PSAs performed for similar sodium fast reactors (SFRs), it shows that PRISM concept has the lowest CDF.

• Proceedings of the KIEE Conference
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• 1999.07c
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• pp.1039-1041
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• 1999

Recently Advanced Static Var Compensators(ASVC) or STATic Synchronous COMpesator(STATCOM) has been considered as a next generation reactive power controller. [2] STATCOM is a voltage source inverter(VSI) based static VAr compensator with only small capacitors on the do side. The main function of the STATCOM is to keep the bus voltage magnitude at the desired value. [1] This paper compares the PAM STATCOM with PWM STATCOM. The characteristics and the control method of each model is analyzed. And the simulation of STATCOMs based on the above two methods was presented.

• Proceedings of the KIEE Conference
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• 1997.07f
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• pp.2246-2248
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• 1997

This paper presents a high-frequency inverter type high-voltage power supply for X-ray equipments. The high-voltage generator consist of an inverter unit including the SR(Series Resonance) type PSC(Phase-Shifted Control) PWM circuit adopting IGBT as the switching power device and high-voltage unit including the CW(Cockcroft Walton) circuit. When the X-ray equipment is radiographing at large power for a short time, this generator operates through feedback voltage mode control to obtain a high speed leading edge and low ripple. The operating modes and design consideration of the proposed power supply are given. Issues in the design of high-voltage divider for high voltage measuring. Experimental results are presented to verify the performance of the designed power supply for varying load conditions. The proposed apparatus has several advantages, e.g., the fast rising time of tube voltage, accuracy and reduced component size etc.

• Smart Structures and Systems
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• v.18 no.3
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• pp.449-470
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• 2016

Energy harvesting is an emerging technique that extracts energy from surrounding environments to power low-power devices. For example, it can potentially provide sustainable energy for wireless sensing networks (WSNs) or structural control systems in civil engineering applications. This paper presents a comprehensive study on harvesting energy from earthquake-induced structural vibrations, which is typically of low frequency, to power WSNs. A macroscale pendulum-type electromagnetic harvester (MPEH) is proposed, analyzed and experimentally validated. The presented predictive model describes output power dependence with mass, efficiency and the power spectral density of base acceleration, providing a simple tool to estimate harvested energy. A series of shaking table tests in which a single-storey steel frame model equipped with a MPEH has been carried out under earthquake excitations. Three types of energy harvesting circuits, namely, a resistor circuit, a standard energy harvesting circuit (SEHC) and a voltage-mode controlled buck-boost converter were used for comparative study. In ideal cases, i.e., resistor circuit cases, the maximum electric energy of 8.72 J was harvested with the efficiency of 35.3%. In practical cases, the maximum electric energy of 4.67 J was extracted via the buck-boost converter under the same conditions. The predictive model on output power and harvested energy has been validated by the test data.

• Proceedings of the KIEE Conference
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• 2006.10a
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• pp.143-144
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• 2006

Since one decade. the detection of High frequency Partial Discharge has been proposed as one of the effective method for the diagnosis of the power component under service in power grids. As a tool for this detection. UHF sensor based on the antenna technology has been commercialized for mainly GIS due to its advantages. However, regarding the recognition of the vital defects introducible into the GIS. different types of softwares have been proposed and employed without any convincing probability of identification. In this regards, our work leads us to suggest a novel method named "PA Map" to identify the defects inside the GIS based on the HFPD detection by use of HFCT sensor which is designed according to our patent.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.393-396
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• 1991

The load factor is continuously decreasing with the increase of the daytime power demand so that the load levelling is required. Since the pumped storage power plant for the load levelling has some problems, new storage techniques such as the battery energy storage system (BESS) had been developed in the early 1980s. The MW BESS had been already interconnected to power system in the developed countries, while the 20KW BESS was developed and is being operated by KERI and KEPCO in our country, the development project of MW BESS is being persued now. Then, it is important to evaluate the economics and prospect of BESS. This paper presents the economic target and introduction prospect of BESS in korea.

• Electronics and Telecommunications Trends
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• v.29 no.6
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• pp.1-13
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• 2014

GaN(Gallium Nitride)는 3.4eV의 넓은 에너지 갭으로 인하여 고전압에서 동작이 가능하고, 분극전하를 이용한 캐리어 농도가 높아 높은 전류밀도와 전력밀도를 얻을 수 있으며, 높은 전자 이동도와 포화 속도로부터 고속 동작이 가능하여 고주파 고출력 고효율 소형의 전력증폭기 소자의 재료로 적합하다. 본고에서는 민수 및 군수 겸용 Ku-대역 및 Ka-대역 GaN 고출력 전력증폭기(SSPA: Solid-State Power Amplifier)와 관련된 GaN 전력증폭 소자, GaN 전력증폭기 MMIC(Microwave Monolithic Integrated Circuit), 내부정합 패키지형 GaN 전력증폭기 및 GaN SSPA에 대하여, 국내외 특허 기술동향과 연구개발 기술동향을 중심으로 고찰하고자 한다. 국외의 GaN 고주파 고출력 전력증폭기 기술의 연구동향이나 특허동향을 심층분석하여 연구개발에 활용하고자 한다.

• Nuclear Engineering and Technology
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• v.51 no.6
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• pp.1689-1695
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• 2019

This study suggests a simple economic model to analyze electricity grid that consists of different power sources. The substitutability of renewable energy for nuclear power in Korean electricity transmission network is investigated by suggested model. The monthly data from January 2006 to December 2013 reported by Electricity Power Statistics Information System (EPSIS) of Korea Power EXchange (KPX) are used. To estimate the elasticities of substitution among four power sources (i.e. coal, natural gas, nuclear power, and renewable energy), this paper uses the trans-log cost function model on which local concavity restrictions are imposed. The estimated Hicks-Allen and Morishima elasticity of substitution shows that renewable electricity and nuclear power are complementary. The results also evidenced that renewable electricity and fossil fueled thermal power generation are substitutes.