• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2017년도 학술발표회
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• pp.329-329
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• 2017

In this study attempted to evaluate the stability of the protection methods by examining hydraulic characteristics of the area around the point in which marine cable protector is installed such as surf zone occurrence point of shore-end submarine cables suitable for coastal marine environmental conditions, flow rate t the tope of the protector and maximum wave height, and to provide basic data for the selection of the optimal protection method. In performing hydraulic model experiments, the topography of submarine cable installation location was reproduced in 2-D sectional channel, and models appropriate for experimental scale and similitude law were produced and installed for each condition of submarine cables and protectors. Since the topography and submarine cable protectors were reproduced and installed in 2-D sectional channel, the exact reproduction of surf and transformation in shallow water zone was possible, and thus the physical properties could be clearly analyzed. For stability review, an experiment to examine the stability was conducted using a wave maker with 50-year frequency design waves as target, and wave height and cycles were applied based on the approximate lowest low water level(Approx. L.L.W), which is the most dangerous in submarine cable protection methods. As for experimental time, typhoon passing time in summer (about 3 hours) was applied, and wave patterns and deviation ratio of the submarine cable protector were investigated after making irregular waves corresponding to design waves. In addition, current meter and wave height meter were installed at the installation location of the submarine cable protector, and the flow rates and wave height at the top of the protector were measured and analyzed to review hydraulic properties.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 춘계 학술발표회
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• pp.278-287
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• 2009

This thesis studied effect of zoning on seepage flow in concrete faced gravel-fill dam (CFGD) designed to have selected main rockfill or gravel-fill zone, Zone 3Bs with higher permeability to enhance the safety against accidental water infiltration into the dam. For this purpose, centrifuge model tests with two cases, with and without Zone 3Bs, were performed in order to investigate the necessity and the function of Zone 3Bs. Model dams were made by soil samples with modified coefficients of permeability and concrete faced slab was simulated with aluminum alloy. Water infiltration was simulated by rising water table over cracks on the facing. Behaviors of model dams were measured by LVDTs, strain gages, pore water pressures and cameras. Form the results of centrifuge tests, it was found out that the Zone 3Bs acts as a protection of main gravel-fill zone by inducing flow paths for infiltrated water into it as well as by draining off the infiltrated water out of the dam in a short time.

• 한국초전도ㆍ저온공학회논문지
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• 제13권3호
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• pp.24-30
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• 2011

The stability issue of high temperature superconducting (HTS) racetrack coils is one of the most important factors for the development of large-scale rotating machines, such as ship propulsion motors and power generators. However, The stability and normal zone propagation characteristics of HTS racetrack pancake (RP) coils are not sufficient yet. In this study, quench tests for a GdBCO racetrack pancake coil were carried out under the condition of $LN_2$ at 77 K. Minimum quench energy and two-dimensional normal zone propagation velocities of the coil are also discussed. Normal zone propagation velocity in the coil's curved section is faster than in its straight section due to stress effects. The test results show that the protection of the straight section is of greater importance than that of the curved section when GdBCO racetrack pancake coils are applied to large-scale rotating machines.

• Journal of Electrical Engineering and Technology
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• 제3권1호
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• pp.29-35
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• 2008

With long time setting, zone 3 impedance relays are considered insensitive to power swings, and their operation condition during power swings is seldom analyzed. Instead of ti me-consuming simulation to the swing loci, their operation condition is directly quantified by polynominal functions in this paper to find the critical swing angle and frequency for relay operation under different relay settings and system parameters. It is found: (1) the swing loci are more densely populated inside than outside of the protection region, which corresponds to long residence time and possible relay operations; (2) the relays may be sensitive to load encroac hments and stable power swings with different relay settings and system parameters; (3) the critical swing frequency may be in the range of low-frequency power swings.

• 한국환경농학회:학술대회논문집
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• 한국환경농학회 2009년도 정기총회 및 국제심포지엄
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• pp.220-227
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• 2009

For last about 10 years, the Republic of Korea experienced 3 times of outbreaks of highly pathogenic avian influenza (HPAI) from 10 December 2003 to 30 April 2004 (a total number of 19 outbreaks), 22 November 2006 to 6 March 2007 (a total number of 7 outbreaks), and 1 April 2008 to 12 May 2008 (a total number of 33 outbreaks). Among the totally 59 outbreaks, the infected premises included 35 chicken farms, 17 duck farms, 1 quail farm, and 6 farms rearing mixed species. Control measures were applied according to the HPAI standard operation procedure including depopulation of all infected and suspected flocks, movement restrictions, and disinfection of the infected farms within a 500-meter radius. Including movement restrictions, stringent control measures were additionally applied to two designated zones: the protection zone was an area within a 3-kilometer radius of the outbreak farm, and the surveillance zone was an area between a 3- to 10-kilometer radius of the outbreak farm. Farms with dangerous contacts and/or all of poultry within the protection zone was subjected to preemptive culling. Epidemiological investigations were also carried out including trace-back and trace-forward investigations to identify possible sources of spread and dangerous contact farms. Investigation teams conducted on-site examination of farm premises and facilities, interview with farm owner and staff, and review of records. Genetic and pathogenic characteristics of the virus isolates, and the results of the various surveillance activities were also analyzed. HPAI surveillance conducted in Korea includes passive surveillance of investigating notified cases, and active surveillance of testing high risk groups and areas. HPAI is a notifiable disease in Korea and all suspect cases must be reported to the veterinary authorities. Cases reported for other poultry diseases that require differential diagnosis are also tested for HPAI. Active surveillance includes annual testing of breeder duck farms, broiler duck farms and wild bird surveillance, which is concentrated during the autumn and winter. Surveillance activities conducted prior to the outbreaks have shown no evidence of HPAI infection in Korea.

• 한국환경복원기술학회지
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• 제21권1호
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• pp.13-30
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• 2018

In terms of environmental friendly land use and objective environmental assessment, legislative assessment items of Environmental Conservation Value Assessment Map (ECVAM) consists of designated areas related to conservation and protection, and areas that are planned to be designated in the future. However, the gap with the reality due to omission of several protection areas and land use regulations, and assessment grades according to 3 division land use map of forest, agricultural land, and urbanized area, results in low application and utilization of ECVAM. Therefore in this study, the legislative assessment of the ECVAM was performed with new assessment items and its new ratings, to suggest an improvement in legislative assessment items of the ECVAM. As a result, legally protected areas of inhabited islands under absolute conservation, special wildlife protection districts, protected marine areas, environmental preservation sea areas, scenic spots, forest protection zone, traditional temple preservation zone, and 45 zone or district related to regulation of land use were additionally designated as new legislative assessment items. New grade ratings were given to each additional assessment items in consideration of the restrictions on acts. As a result of the legislative assessment based on the new assessment items and new grades, the 1st grade area increased by 3.47%, and the 2nd grade area increased by 19.35%. The 3rd grade area decreased by 8.54%, the 4th grade area increased by 2.95%, and 5th grade increased by 2.91%. In addition, the out-of-grade area decreased by 20.14%, considered to be a realistic assessment based on land use. With the improved legislative assessment, it is possible to provide a more accurate environmental assessment map. Increase usage of ECVAM is expected in providing regulations of land use and base data for integrated land management of land environmental planning.

• 한국방재안전학회논문집
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• 제12권1호
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• pp.23-34
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• 2019

농촌지역 하천이나 호소수 수질 개선을 위한 비점오염원의 관리 및 저감은 시급한 현안이다. 본 연구에서는 농촌지역의 비점오염 저감을 위하여, 개비온 매트리스호안공에 혐기/호기의 구역을 적용한 자연형 비점오염처리 하천호안을 제안하고, 이의 축소모형 실험(1/6 축적) 및 현장 적용(가로2.0 m 세로 3.0 m 높이 0.4 m의 3단 격벽의 호안)을 통하여 활용성을 평가하였다. 개비온 매트리스 내부에 골재를 채운후 차수 격벽을 설치하고, 호안 법면의 자연 경사를 활용하여 혐기/호기 조건의 여과대를 조성하여 오염물질을 다단으로 처리하였다. 또한 호안공의 표면에 식생을 활착시켜, 토사의 표면 유입을 차단하고, 추가적으로 식생에 의한 정화 기능을 도모하였다. 본 호안공의 축소모형 및 현장 적용에서의 화학적산소요구량(COD) 및 질소성분(T-N, $NH_4{^+}-N$, $NO_3{^-}-N$)의 모니터링 결과, Lab Scale에서는 TCOD 17%, SCOD 35%, TN 14%, $NH_4{^+}-N$ 62%, $NO_3{^-}-N$ 33%의 제거효율을 나타내었고, pilot plant 시운전에서는 TCOD 24%, SCOD 29%, TN 47%, $NH_4{^+}-N$ 50%, $NO_3{^-}-N$ 33%의 제거효율을 나타내었으며, pilot plant 시운전에서는 29%의 TP 제거효율도 달성하였다.

• 한국화재소방학회논문지
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• 제33권2호
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• pp.56-62
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• 2019

스프링클러는 방호구역에 설치된 감지기 또는 헤드가 화재를 감지하여 자동으로 화재를 진압하는 소화설비로 화재 초기에 뛰어난 소화효과가 있어 폭넓게 설치되고 있다. 하지만 국토교통부의 "건축물의 피난 방화구조 기준 등에 관한 규칙"에는 공장 또는 창고의 경우 스프링클러설비를 설치하면 방화구획을 3배까지 완화해 줄 수 있도록 그 근거를 제공하고 있다. 이에 본 연구에서는 스프링클러설비 설치로 방화구획을 완화한 실제 Printed Circuit Board (PCB) 공장 1개소를 대상으로 화재위험성을 분석하였고, 컴퓨터 시뮬레이션을 통한 스프링클러설비의 헤드 개방 특성 및 스프링클러 설비의 설치기준, 감열성능, 작동범위, 방수량 등을 분석하였다. 또한 이를 통해 화재 시 스프링클러 설비 작동의 문제점을 확인하고, 제도 개선을 위한 요구 살수유량 등 근거를 제시하고자 한다.

• 전기학회논문지
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• 제61권10호
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• pp.1542-1547
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• 2012

Asynchronous phenomenon occurs on the synchronous generators under power system when a generator's amplitude of electromagnetic force, phase angle, frequency and waveform etc become different from those of other synchronous generators which can follow instantly varying speed of turbine. Because the amplitude of electromagnetic force, phase frequency and waveform differ from those of other generators with which are to be put into parallel operation due to the change of excitation condition for load sharing and the sharing load change, if reactive current in the internal circuit circulates among generators, the efficiency varies and the stator winding of generators are overheated by resistance loss. When calculation method of protection settings and logic for protection of generator asynchronization will be recommended, a distance relay scheme is commonly used for backup protection. This scheme, called a step distance protection, is comprised of 3 steps for graded zones having different operating time. As for the conventional step distance protection scheme, zone 2 can exceed the ordinary coverage excessively in case of a transformer protection relay especially. In this case, there can be overlapped protection area from a backup protection relay and, therefore, malfunctions can occur when any fault occurs in the overlapped protection area. Distance relays and overcurrent relays are used for backup protection generally, and both relays have normally this problem, the maloperation, caused by a fault in the overlapped protection area. Corresponding to an IEEE standard, this problem can be solved with the modification of the operating time. On the other hand, in Korea, zones are modified to cope with this problem in some specific conditions. These two methods may not be obvious to handle this problem correctly because these methods, modifying the common rules, can cause another coordination problem. To overcome asynchronizing protection, this paper describes an improved backup protection coordination scheme using a new logic that will be suggested.

• 전기학회논문지
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• 제60권11호
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• pp.2000-2006
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• 2011

Asynchronous phenomenon occurs on the synchronous generators under power system when a generator's amplitude of electromagnetic force, phase angle, frequency and waveform etc become different from those of other synchronous generators which can follow instantly varying speed of turbine. Because the amplitude of electromagnetic force, phase frequency and waveform differ from those of other generators with which are to be put into parallel operation due to the change of excitation condition for load sharing and the sharing load change, if reactive current in the internal circuit circulates among generators, the efficiency varies and the stator winding of generators are overheated by resistance loss. Where calculation method of protection settings and Logic for Protection of Generator Asynchronization will be recommended, A distance relay scheme is commonly used for backup protection. This scheme, called a step distance protection, is comprised of 3 steps for graded zones having different operating time. As for the conventional step distance protection scheme, Zone 2 can exceed the ordinary coverage excessively in case of a transformer protection relay especially. In this case, there can be overlapped protection area from a backup protection relay and, therefore, malfunctions can occur when any fault occurs in the overlapped protection area. Distance relays and overcurrent relays are used for backup protection generally, and both relays have normally this problem, the maloperation, caused by a fault in the overlapped protection area. Corresponding to an IEEE standard, this problem can be solved with the modification of the operating time. On the other hand, in Korea, zones are modified to cope with this problem in some specific conditions. These two methods may not be obvious to handle this problem correctly because these methods, modifying the common rules, can cause another coordination problem. To overcome asynchronizing protection this paper describes an improved backup protection coordination scheme using a new Logic that will be suggested.