• Proceedings of the KIEE Conference
• /
• 2003.07a
• /
• pp.464-466
• /
• 2003

우리나라는 1980년대 이후 급격한 경제성장에 따라 년 10%대의 급격한 전력수요 증가를 보이고 있으며, 1인당 전력소비량 또한 매년 큰 폭의 증가세를 보이고 있다. 특히, 주요한 전력 수요 증가지대가 경인 지역에 집중되어 있으나, 이 지역은 인구 밀집지역으로 환경과 입지적인 관점에서 새로운 발전원을 개발하기가 곤란하다. 이에 따라 대용량 발전단이 있는 중서부권이나 영동권으로부터 수요지인 경인지역으로의 대규모 전력전송로가 필요하게 되었다. 이에 따라 1979년부터 765kV로의 전압격상을 준비하였으며, 1983년부터 765kV 연구개발을 시작하여 1997년 10월에 1차로 765kV 송전선로에 345kV 가압을 시작하여 2002년 5월 8일에 역사적인 765kV 송전을 개시하였다. 전력계통운용에서 765kV 송전선로의 중요도가 매우 커지게 됨으로써 국내 최초로 적용되는 765kV송전선로 보호시스템의 정동작 유무를 정확히 판단하여 전력계통의 보호 신뢰도를 향상시키는 문제가 중요하게 대두 되었다. 본 논문에서는 시각동기장치가 부착된 보호계전기 시험장치를 이용하여 양단 변전소에서 동시에 EMTP와 RTDS 둥으로 검토된 송전선로 고장상태를 인가하여 보호시스템의 정동작 여부를 종합적으로 판정하는 시험 기술을 개발하여 실적용한 사례와 향후 사용 계획에 대해서 기술하였다.

• Nuclear Engineering and Technology
• /
• v.17 no.4
• /
• pp.302-316
• /
• 1985

Small break LOCA caused by a stuck-open PORV is one of the important contributors to nuclear power plant risk. This paper deals with the design of a pressurizer surveillance system using microcomputer to prevent the malfunction of system and has assessed the effect of this improvement through Probabilistic Risk Assessment (PRA) method. Micro-computer diagnoses the malfunction of system by a process checking method and performs automatically backup action related to each malfunction. Owing to this improvement, we can correctly diagnose “Spurious Opening”, “Fail to Reclose” and “Small break LOCA” which are difficult for operator to diagnose quickly and correctly and reduce the probability of a human error by an automatic backup action.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.58 no.9
• /
• pp.1674-1680
• /
• 2009

This paper proposes an autonomous fault determination, fault zone isolation and fault restoration strategy based on the ethernet communication as a new attempt to solve the problem the of the existing central control method. In proposed method, The FRTU(Feeder Remote Terminal Unit)s on the feeder determines autonomously where the faulted zone is by exchanging the voltage and current information with neighbor FRTUs based on the network communication, and then separates the faulted zone in an nil-voltage status to make the protective device to reclose successively. In particular, the minimization of outage time and relational load balancing is archived by each interconnection switch which determines autonomously the load zone to be allocated among those zones after the sound outage zones was separated individually. Finally, to show effectiveness of the proposed fault restoration strategy, the several fault cases are simulated for the test distribution system, and the load balancing index of the proposed solution is compared with all of feasible solutions.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.19 no.8
• /
• pp.40-47
• /
• 2005

The objective of this paper is to analyze power system dynamics influenced by UPFC(Unified Power flow Controller) operation and to develop a refined DCRM(Differential Current Relaying Method) to protect the transmission line with UPFC effectively. The implementation of control strategies for UPFC introduces new power system dynamic problems that must be considered while applying the conventional DCRM. In this paper, impact of UPFC operation on the DCRM has been reviewed and a refined DCRM has been proposed to detect faults properly in spite of UPFC operation. The porposed method is verified by simulation on the line-faulted system with UPFC.

• Proceedings of the KIEE Conference
• /
• 2007.07a
• /
• pp.421-422
• /
• 2007

계통의 정확한 상태추정을 위해서는 현재 확보된 데이터를 이용하여 계통의 가관측성을 확인하여야 한다. 실제 계통에서는 통신장애, 계기의 고장 등과 같은 이유로 전체 계통에 대한 상태추정이 불가능한 경우가 있으며, 이러한 경우 계통은 가관측성을 확보하지 못하였다고 한다. 견실한 상태추정을 위해서는, 전체 계통의 가관측성을 확보하였는지 판단하고, island가 발생한 경우 의사측정데이터를 추가하여 계통의 가관측성을 확보하는 과정이 필요하다. 본 논문에서는 수치해석법을 이용한 가관측성 해석 알고리즘을 이용하여 전체 시스템의 가관측성을 판별하고, 필요한 경우 의사측정데이터를 추가하는 프로그램을 개발하였다. IEEE 14모선 시험계통을 이용하여 가관측성 확보에 대한 타당성을 검증하였다.

• Fire Science and Engineering
• /
• v.25 no.2
• /
• pp.107-113
• /
• 2011

This paper presents the results of artificially accelerated aging characteristics of the rate of rise spot type heat detectors. This experiment carried out to investigate the detector's operating characteristics when a fire was broken out or the regular tests were performed. The result showed that the delay of operating time or no-operation of heat detector which was made by company B and used in the field for 5 years may be occurred even at the $100^{\circ}C$. This result is due to the leakage of inflated air from heat chamber. However the operating display LED was not out of order, even if the temperature was increased up to $160^{\circ}C$.

• Journal of the Korean Society of International Agriculture
• /
• v.31 no.1
• /
• pp.8-16
• /
• 2019

Alternatives for increasing the competitiveness of locally manufactured agricultural machinery in domestic and foreign markets has been proposed. This was done by analyzing the major agricultural machinery's price and market share as well as their performance and quality. In the Korean domestic market, the market share of Japanese agricultural machinery has been identified to be 14.5% for tractors, 31.1% for combine harvesters, and 35.8% for rice transplanters, and on track for further increase. Japanese manufacturers' domestic patent shares are 58.5% for tractors, 79.9% for combine harvesters, and 69.8% for rice transplanters, showing the dire need for Korean domestic firms to expand their technological rights. To strengthen the industrial competitiveness of agricultural machinery, therefore, researches that develop the fundamental and elemental technology to reduce the frequency of breakdown should be needed in the short term. To achieve this, it is imperative to establish technology roadmap, promote greater cooperation between academia and industry, and systematically increase research funding. In addition, as a long-term solution for enhancing the competitiveness, an establishment of Agricultural Equipment Technology Institute is strongly recommended to systematically support R&D for developing core technologies, particularly high-quality components that guarantee durability and quality.

• Korean Chemical Engineering Research
• /
• v.60 no.3
• /
• pp.347-355
• /
• 2022

The safety valve (PSV) is a safety device that automatically releases a spring when the pressure generated by various causes reaches the set pressure, and is restored to a normal state when the pressure falls below a certain level. Periodic inspection and monitoring of safety valves are essential so that they can operate normally in abnormal conditions such as pressure rise. However, as the current safety inspection is performed only at a set period, it is difficult to ensure the safety of normal operation. Therefore, evaluation items were developed by finding failure modes and causative factors of safety valves required for safety management. In addition, it is intended to provide decision-making information for securing safety by deriving the priority of items. To this end, a Delphi survey was conducted three times to derive evaluation factors that were judged to be important in relation to the Failure Mode Cause Factor (FMCFs) of the safety valve (PSV) targeting 15 experts. As a result, 6 failure modes of the safety valve and 22 evaluation factors of its sub-factors were selected. In order to analyze the priorities of the evaluation factors selected in this way, the hierarchical structure was schematized, and the hierarchical decision-making method (AHP) was applied to the priority calculation. As a result of the analysis, the failure mode priorities of FMCFs were 'Leakage' (0.226), 'Fail to open' (0.201), 'Fail to relieve req'd capacity' (0.152), 'Open above set pressure' (0.149), 'Spuriously' 'open' (0.146) and 'Stuck open' (0.127) were confirmed in the order. The lower priority of FMCFs is 'PSV component rupture' (0.109), 'Fail to PSV size calculation' (0.068), 'PSV Spring aging' (0.065), 'Erratic opening' (0.059), 'Damage caused by improper installation and handling' (0.058), 'Fail to spring' (0.053), etc. were checked in the order. It is expected that through efficient management of FMCFs that have been prioritized, it will be possible to identify vulnerabilities of safety valves and contribute to improving safety.

• Journal of Korean Society of Steel Construction
• /
• v.17 no.5 s.78
• /
• pp.561-568
• /
• 2005

The object of this paper is to determine appropriateness for use of high-strength tensile bar as a tension web member. The gap K-joint of tensile bar types were compared with gap K-joint of square hollow section (SHS) types. For the same width-to-thickness ratio ($2{\gamma}=33.3$ ), tests were performed on four specimens of the SHS type and eight specimens of the tensile bar type. The comparison of capacity with the experimental results showed a capacity of the SHS type joint to be higher than that of the tensile bartype joint for the same brace-to-chord width ratio. Moreover, the capacity of the SHS type joints increased proportionally to the width ratio ${\beta}$), while tensile bar type joints increased as the tension width ratio (${\beta}2$). In failure mode, SHS-type specimens showed local buckling of the compression brace and plastic failure was observed between the tension brace and chord face, and with the tensile bar type specimens there appeared punching shear failure of the chord face at the toe of the connection plate. It is, therefore, concluded that width-to-thickness ratio should be lower than that of the hollow-section type and the relation between tension and compression width ratio should be considered.

• Journal of Navigation and Port Research
• /
• v.37 no.1
• /
• pp.113-121
• /
• 2013

IMO(International Maritime Organization) is existed the movement for revising ISM Code so that the maintenance history and the trouble information given trading in a ship can be transferred. An empirical analysis was made on the influence that will have upon shipping industry through surveying on the recognition on ISM Code revision in employees of the relevant field and on the expected problems given being amended ISM Code as the above. In conclusion, the positive effect is judged to be more in the aspect of ship safety, which is the aim of ISM Code, rather than the negative effect, which may take place given being revised ISM Code. In other words, the clean market can be formed through this because fairness is maintained on both sides given trading in a ship by which opening the maintenance record and the trouble history is applied equally to a buyer and a seller. Ships can be reduced a loss of time and cost in preventing similar problems and seeking solution that may appear in important equipments, through this maintenance record. Also, based on these materials, it comes to be available for analyzing a risk of ship and preventing and managing a risk, thereby being increased ability of maintenance and repair in a ship, resulting in being judged to likely contributing to ship safety and environmental-pollution prevention.