• Journal of Electrical Engineering and Technology
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• 제2권3호
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• pp.294-299
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• 2007

This paper presents a special protection scheme, which was established in the KEPCO (Korea Electric Power Corporation) system, against a critically low voltage profile in a part of the system after a double-circuit tower outage. Without establishing the scheme, the outage triggers the operation of a zone 3 relay and trips the component. This sequence of events possibly leads to a blackout of the local system. The scheme consists of an inter-substation communication network using PITR (Protective Integrated Transmitter and Receiver) for acquisition of the substations' data, and under-voltage load shedding devices. This paper describes the procedure for determining the load shedding in the scheme and the experiences of the implementation.

• 대한전기학회논문지:전력기술부문A
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• 제53권3호
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• pp.161-167
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• 2004

Zone 3 of the distance relay is used to provide the remote back-up protection in case of the failure of the primary protection. However, the risk lot mal-operations under stressed conditions such as heavy loading, voltage and transient instability is usually high. Zone 3 is used in combination with the derivatives of the voltage, and current, etc to prevent mal-operations. Sometimes, the impedance characteristics that restrict the tripping area of relay are used to avoid the mal-operations due to load encroachment. This paper presents a novel Zone 3 scheme based on combining the steady-state components (i.e. 60Hz) and the transient components (TCs) using a state diagram that visualizes the sequence of studies that emanate from the sequence of events. The simulation results show that the novel zone 3 distance relay elements using the proposed method operates correctly for the various events.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 추계학술대회 논문집 전력기술부문
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• pp.245-247
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• 2003

Zone 3 of the distance relay is used to provide the remote back-up protection in case of the failure of the primary protection. However, the risk for mal-operations under stressed conditions such as heavy loading, voltage and transient instability is usually high. Zone 3 is used in combination with the derivatives of the voltage, and current, etc to prevent mal-operations. Sometimes, the impedance characteristics that restrict the tripping area of relay are used to avoid the mal-operations due to load encroachment. This paper presents a novel zone 3 scheme based on combining the steady-state components(i.e. 60Hz) and the transient components(TCs) using a state diagram that visualizes the sequence of studies that emanate from the sequence of events. The simulation results show that the novel zone 3 distance relay elements using the proposed method operates correctly for the various events.

• 한국물환경학회지
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• 제20권3호
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• pp.231-235
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• 2004

To investigate removal effects of nutrients in stormwater runoff by soil of riparian protection zone, soil column experiment was conducted for 20 months. Artificial stormwater runoff containing phosphate and nitrate was applied on the surface of soil column twice a week, and phosphate and nitrate concentrations were measured from the leached water. Soil of riparian protection zone reduced the released amount of infiltrated water to the surrounding water. After infiltration of 1m depth of soil column, average removal rates of phosphate and nitrate were 97.7 % and 74.7 %, respectively. As main mechanisms of phosphate are adsorption to soil particle and utilization by plants, periodical replacement of soil and harvesting of plant at the end of growing season are required. For the removal of nutrients in stormwater runoff by the soil layer, soil of riparian protection zone has higher hydraulic conductivity to infiltrate stormwater. Sandy soil having hydraulic conductivity of about $1{\times}10^{-2}cm/s$ range might be appropriate for this purpose.

• 환경영향평가
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• 제9권3호
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• pp.239-248
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• 2000

The aggravating water quality from the expansion of industrialization along with increasing population lead to develop more intensive physical measures to secure better drinking water quality. This study was mainly initiated to establish a water-pollutant buffering zone for the upper stream basin of Paldang--the major source area of drinking water for the metropolitan Seoul and suburban areas with a population more than 13 million. Two different criteria were considered in determining the buffering distance from the edge of the streamflow : 1km-width buffer zone for the special protection area which has been strictly controlled by the conventional laws for the protection of drinking water supply, and 500m-width buffer zone for the rest of the area. To delineate the exact boundaries of the water-pollutant buffering zone, GIS database was created integrating topography, hydrography, cadastral, and other related layers. The newly designated water-pollutant buffering zone would contribute to improve the water quality in a long term along with the conservation of the wet land. More study, however, should be made within the water-pollutant buffering zone such as the detailed survey of the pollutants, vegetation, and ecosystem for more effective management of the buffering zone.

• Journal of Advanced Marine Engineering and Technology
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• 제8권2호
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• pp.39-50
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• 1984

The plane bending corrosion fatigue test was performed on the welded zone between SM58 steel plate and SM41 steel plate jointed with submerged arc welding in the air and in the natural sea water with various conditions. The main results obtained from the test are summarized as follows: 1) The welded zone of the steel plates has the lowest impact strength and the highest electrode potential, but the hardness was mediate of SM58 base and SM41 base. 2) The cathodic protection of the welded zone was also effective for the plane bending corrosion fatigue, and the optimum protection potential of the welded zone was -1,000 mV SCE. 3) The corrosion fatigue strength under the various stress conditions of the steel plate could be estimated and also the require safety factors on the design could be obtained from the plane bending fatigue limit diagram.

• 한국자동차공학회논문집
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• 제20권3호
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• pp.126-132
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• 2012

Recently, pedestrian protection related research topics have been actively studied by automotive designers and engineers due to the enhanced pedestrian protecting regulations. It is required to design an energy absorbing structure, such as crumple zone that can sufficiently absorb the impact energy to reduce the leg injury when accident happens. The structure is designed by reducing the height of front end module, considering the mounting location, and investigating impact characteristics. In this paper, the concept of the crumple zone was introduced and the role of the crumple zone was investigated by analyzing the performance of upper legform impact to a bonnet leading edge test, and the design process was suggested.

• 수산해양기술연구
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• 제25권2호
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• pp.87-104
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• 1989

Recently, with the tendency of more lightening, high-strength and high-speed in the marine industries such as marine structures, ships and chemical plants, the use of the aluminium Alloy is rapidly enlarge and there occurs much interest in the study of corrosion fatigue crack characteristics. In this paper, the initiation of surface crack and the propagation characteristics on the base metal and weld zone of 5086-H116 Aluminium Alloy Plate which is one of the Al-Mg serious alloy(A5000serious) used most when building the special vessels, were investigated by the plane bending corrosion fatigue under the environments of marine, air and applying cathodic protection. The effects of various specific resistances on the initiation, propagation behavior of corrosion fatigue crack and corrosion fatigue life in the base metal and heat affected zone were examined and its corrosion sensitivity was quantitatively obtained. The effects of corrosion on the crack depth in relation to the uniform surface crack length were also investigated. Also, the structural, mechanical and electro-chemical characteristics of the metal at the weld zone were inspected to verify the reasons of crack propagation behavior in the corrosion fatigue fracture. In addition, the effect of cathodic protection in the fracture surface of weld zone was examined fractographically by Scanning Electron Microscope(S.E.M.). The main results obtained are as follows; (1) The initial corrosion fatigue crack sensitibity under specific resistance of 25Ω.cm% show 2.22 in the base metal and 19.6 in the HEZ, and the sensitivity decreases as specific resistance increases (2) By removing reinforcement of weldment, the initiation and propagation of corrosion crack in the HAZ are delayed, and corrosion fatigue life increases. (3) As specific resistance decreases, the sensitivity difference of corrosion fatigue life in the base metal and HAZ is more susceptible than that of intial corrosion fatigue crack. (4) Experimental constant, m(Paris' rule) in the marine environment is in the range of about 3.69 to 4.26, and as specific resistance increases, thje magnitude of experimental constant, also increases and the effect by corrosion decreases. (5) Comparing surface crack length with crack depth, the crack depth toward the thickness of specimen in air is more deeply propagated than that in corrosion environment. (6) The propagation particulars of corrosion fatigue crack for HAZ under initial stress intensity factor range of $\Delta$k sub(li) =27.2kgf.mm super(-3/2) and stress ratio of R=0 shows the retardative phenomenon of crack propagation by the plastic deformation at crack tip. (7) Number of stress cycles to corrosion fatigue crack initiation of the base metal and the welding heat affected zone are delayed by the cathodic protection under the natural sea water. The cathodic protection effect for corrosion fatigue crack initiation is eminent when the protection potential is -1100 mV(SCE). (8) When the protection potential E=-1100 mV(SCE), the corrosion fatigue crack propagation of welding heat affected zone is more rapid than that of the case without protection, because of the microfissure caused by welding heat cycle.

• Safety and Health at Work
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• 제9권3호
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• pp.352-355
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• 2018

Hazardous work zones (i.e., hot, warm, and cold) are typically established by emergency response teams during hazardous materials (HAZMAT) calls but less consistently for fire responses to segment personnel and response activities in the immediate geographic area around the fire. Despite national guidelines, studies have documented the inconsistent use of respiratory protective equipment by firefighters at the fire scene. In this case-series report, we describe warm zone gas levels using multigas detectors across five independent fire incident responses all occurring in a large South Florida fire department. Multigas detector data collected at each fire response indicate the presence of sustained levels of volatile organic compounds in the "warm zone" of each fire event. These cases suggest that firefighters should not only implement strategies for multigas detector use within the warm zone but also include respiratory protection to provide adequate safety from toxic exposures in the warm zone.

• 한국방재안전학회논문집
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• 제16권4호
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• pp.137-145
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• 2023

어린이보호구역 일명 스쿨존에서 어린이와 보행자 사망사고가 지속적으로 발생하고 있다. 2019부터 2021년까지 3년 동안 전국 스쿨존 내 어린이사망사고는 11건이나 발생했으며, 2022년 12월에도 서울특별시 강남구 초등학교 인근 스쿨존에서 초등학생 사망사고가 발생했고, 2023년 4월에도 대전광역시 서구 중학교 인근 스쿨존과 부산광역시 영도구 초등학교 인근 스쿨존에서 각각 초등학생이 사망하는 사고가 발생하는 등 최근까지도 어린이보호구역 내 보도에서 어린이 사망사고가 지속적으로 발생하고 있어, 스쿨존 내 설치된 안전시설 현황과 관련 규정에 대한 면밀한 검토가 필요한 시점이다. 국내 어린이보호구역 보도에 설치된 안전시설 현황과 관련 규정을 조사 ‧ 분석하고, 어린이보호구역 보도용 안전시설에 대한 제도개선 필요사항을 도출하였다.