• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 추계학술대회 논문집 전기물성,응용부문
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• pp.145-147
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• 2005

In present, most of metallic structures(gas pipeline, oil pipeline, water pipeline, etc) are running parallel with subway and power line in seoul. Moreover subway system and power line make a stray current due to electrical corrosion on metallic structures. The owner of metallic structures has a burden of responsibility for the protection of corrosion and the prevention against big accident such as gas explosion or soil pollution and so on. So, they have to measure and analyze the data about P/S(Pipe to Soil) potential due to stray current of subway system. So, we have developed the Real-time Wireless Remote Monitoring System for Stray Current of Subway System. In this system, the permanent buried type reference electrode is necessary. In this paper, results of development of buried type reference electrode using porous ceramic$({\alpha}-Al_{2}O_{3})$ are presented.

• 센서학회지
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• 제7권2호
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• pp.140-146
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• 1998

정전기는 고집적 반도체소자의 제조공정에서 제품의 제조수율을 감소시키거나, 정전하에 의해 가스폭발이나 화재 등을 일으키는 원인이 되므로 정전기를 제거하기 위한 수단이나 장치가 필수적으로 요구된다. 본 논문에서는 전하중화장치의 사용시간 경과에 따른 침전극 마모 및 분진부착 특성에 대해서 실험적으로 연구하였다. 또한 전하중화장치의 침전극의 마모 최소화와 발생이온량의 정량적인 제어를 위해 인가전원을 종래의 교류전원 대신에 고주파 펄스전원으로 하여 펄스주파수 및 펄스의 시비율을 변화시킴으로서, 펄스전력을 유효하게 제어할 수 있었으며, 또 펄스전원을 사용함으로서 전하중화장치의 이온 발생특성을 크게 할 수 있음을 실험적으로 확인하였다.

• ETRI Journal
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• 제32권1호
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• pp.73-83
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• 2010

Combinatorial testing has been an active research area in recent years. One challenge in this area is dealing with the combinatorial explosion problem, which typically requires a very expensive computational process to find a good test set that covers all the combinations for a given interaction strength (t). Parallelization can be an effective approach to manage this computational cost, that is, by taking advantage of the recent advancement of multicore architectures. In line with such alluring prospects, this paper presents a new deterministic strategy, called multicore modified input parameter order (MC-MIPOG) based on an earlier strategy, input parameter order generalized (IPOG). Unlike its predecessor strategy, MC-MIPOG adopts a novel approach by removing control and data dependency to permit the harnessing of multicore systems. Experiments are undertaken to demonstrate speedup gain and to compare the proposed strategy with other strategies, including IPOG. The overall results demonstrate that MC-MIPOG outperforms most existing strategies (IPOG, IPOF, IPOF2, IPOG-D, ITCH, TConfig, Jenny, and TVG) in terms of test size within acceptable execution time. Unlike most strategies, MC-MIPOG is also capable of supporting high interaction strengths of t > 6.

• 한국수소및신에너지학회논문집
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• 제23권4호
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• pp.330-336
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• 2012

FCEV uses 250 ~ 450 V instead of using 12 V battery. High voltage vehicle can cause electric shock, fire and explosion accident. Therefore, it has potential factors that can cause hazard of safety for users. United states of America and Europe legislate regulations such as ECE R100, FMVSS 305 for regulating electrical safety during driving or after collision. The company manufacturing high voltage components must do advanced R&D about Method for improving and confirming the safety of high voltage. We develop the specific hardware components of high voltage wiring system for the power train system and power supply system of Hyundai Motors FCEV. This paper shows test method of insulative performance for securing the electrical safety of high voltage components such as power cable, connectors and buss-bar, and proposals the guide line value for human safety of FCEV according to the test result of our development components.

• 한국안전학회지
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• 제27권3호
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• pp.63-70
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• 2012

In the hazardous areas where explosive gases, vapor or mists exist, electrical apparatus and installations must be the explosion-proof construction to prevent or limit the danger of the ignition of potentially explosive atmosphere. In Korea, nine types of protection have been specified in the government regulations at present: flameproof enclosure, pressurization, oil immersion, increased safety, intrinsic safety, non-incendive, powder filling, encapsulation, and special types. Among these types, the intrinsic safety has the construction which limit or by-pass igniting the electric energy using electronic devices. This type has lots of merits but at the same time requires a high-degree of technology. In this paper, we investigated several dominating factors which affect the minimum ignition energy; this energy plays a very important role in design and evaluation of the intrinsic safety type electrical apparatus. Electrode material, which is one of the most important factors, was intensively studied for the five sorts of material(Al, Cd, Mg, Sn, and Zn) with performing experiment in a low-voltage inductive circuit using IEC-type(International Electro-technical Commission) spark apparatus. The experimental results show that the minimum ignition energy of electrode material is varied: highest in Cd and lowest in Sn. We also confirmed the effect of electrode make-and-break speed.

• 대한전기학회논문지:전력기술부문A
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• 제48권3호
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• pp.234-240
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• 1999

This paper presents a new approach for large-scale generator maintenance scheduling optimizations. The generator preventive maintenance scheduling problems are typical discrete dynamic n-dimensional vector optimization ones with several inequality constraints. The considered objective function to be minimized a subset of{{{{ { R}^{n } }}}} space is the variance (i.g., second-order momentum) of operating reserve margin to levelize risk or reliability during a year. By its nature of the objective function, the optimal solution can only be obtained by enumerating all combinatorial states of each variable, a task which leads to computational explosion in real-world maintenance scheduling problems. This paper proposes a new priority search mechanism based on each generator's discrete sensitivity value which was analytically developed in this study. Unlike the conventional capacity-based priority search, it can prevent the local optimal trap to some extents since it changes dynamically the search tree in each iteration. The proposed method have been applied to two test systems (i.g., one is a sample system with 10 generators and the other is a real-world lage scale power system with 280 generators), and the results anre compared with those of the conventional capacith-based search method and combinatorial optimization method to show the efficiency and effectiveness of the algorithm.

• 전기학회논문지
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• 제61권8호
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• pp.1148-1152
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• 2012

The vegetable-based insulating oils are substitutes for mineral oils in oil-filled transformer. The important properties of vegetable insulating oil is their higher flash/fire point and biodegradability than conventional mineral oils. The large oil-filled transformer eliminate the risk of explosion and fire should the transformer fail and oil ignite owing to high flash/fire point of vegetable insulating oil. In addition, higher biodegradability of vegetable insulating oils can let the oil spill damage reduced. In this experiment, the real oil-filled transformers using mineral oil and vegetable oil have accelerated aging. After working on the 100% accelerated aging experiment were conducted comparing the transformer. The hottest-spot temperature using thermal coefficients were calculated to determin the degree of accelerated aging. As a result, apply mineral oil transformer in accordance with the accelerated aging life come to an end. In contrast, vegetable insulating oils showed the opposite characteristics. Vegetable insulating oil compared to the mineral oil are found to be an long life. As a result, the vegetable oil has a long-term stability.

• KIEE International Transactions on Electrophysics and Applications
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• 제3C권3호
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• pp.99-105
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• 2003

The influence of discharge conditions, including the resistance of the sparking circuit, the shape of the electrodes and the width of the falling dust on the ignitability of lycopodium streams were investigated. Discharge characteristics and the ignition phenomena were also explored. When a 100 ㏀ resistor was connected in series with the sparking circuit, the lowest level of minimum ignition energy (MIE) was attained for lycopodium streams. Simultaneously, the area where flammable gas generated increased and the duration of flammable gas generation decreased. That is, the ignita-bility of lycopodium streams depended strongly on the discharge power and discharge duration. Electrodes with sharp tips gave smaller MIEs than those with round tips in a capacitive-inductive sparking circuit, while shape made no difference in a capacitive-resistive circuit. Streams that were too narrow required a considerable amount of energy for ignition.

• 한국전기전자재료학회논문지
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• 제31권6호
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• pp.427-432
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• 2018

High-capacity secondary batteries can cause explosion hazards owing to microcurrent variations or current surges that occur in short circuits. Consequently, complete safety cannot be achieved with general protection that is limited to a mere current fuse. Hence, in the case of secondary batteries, it is necessary for the protector to limit the inrush current in a short circuit, and to detect the current during microcurrent variations. To serve this purpose, a fuse can be employed for the secondary battery protection circuit with current detection. This study aims at designing a protection device that can stably operate in the hazardous circumstances associated with high-capacity secondary batteries. To achieve the said objective, a detecting fuse was designed from an alloy of low melting point elements for securing stability in abnormal current states. Experimental results show that the operating I-T and V-T characteristic constraints can be satisfied by employing the proposed current detecting self-contained low melting point fuse, and through the resistance of the heating resistor. These results thus verify that the proposed protection device can prevent the hazards of short circuit current surges and microcurrent variations of secondary batteries.

• 전기학회논문지
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• 제67권12호
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• pp.1619-1625
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• 2018

Portable electronic devices secondary batteries can cause fire and explosion due to micro-current change in addition to the situation of short-circuit inrush current, safety can not be secured with a general operation limited current fuse. Therefore, in secondary battery, it is necessary for the protector to satisfy both the limit current type operation in the open-short-circuit inrush current and the current detection operation characteristic in the micro current change situation and for this operation, a fuse for the current detection type secondary battery protection circuit can be applied. The purpose of this study is to design a protection device that operates stably in the hazardous situation of small capacity secondary battery for portable electronic devices through the design of low melting fuse elements alloy of sensing type fuse and secures stability in abnormal current state. As a result of the experiment, I-T and V-T operation characteristics are satisfied in a the design of the alloy of the current sensing type self-contained low melting point fuse and the resistance of the heating resistor. It is confirmed that it can prevent accidents of short circuit over-current and micro current change of secondary battery.