• KEPCO Journal on Electric Power and Energy
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• 제2권2호
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• pp.227-232
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• 2016

To test the effectiveness of using an energy storage system for frequency regulation, the Energy New Business Laboratory at KEPCO Research Institute installed a 4 MW energy storage system (ESS) demonstration facility at the Jocheon Substation on Jeju Island. And after the successful completion of demonstration operations, a total of 52 MW ESS for frequency regulation was installed in Seo-Anseong (28 MW, governor-free control) and in Shin-Yongin (24 MW, automatic generation control). The control system used in these two sites was based on the control system developed for the 4 MW ESS demonstration facility. KEPCO recently finished the construction of 184 MW ESS for frequency regulation in 8 locations, (e.g. Shin-Gimjae substation, Shin-Gaeryong substation, etc.) and they are currently being tested for automatic operation. KEPCO plans to construct additional ESS facilities (up to a total of about 500 MW for frequency regulation by 2017), thus, various operational tests would first have to be conducted. The high-speed characteristic of ESS can negatively impact the power system in case the 500 MW ESS is not properly operated. At this stage we need to verify how effectively the 500 MW ESS can regulate frequency. In this paper, the effect of using ESS for frequency regulation on the power system of Korea was studied. Simulations were conducted to determine the effect of using a 524 MW ESS for frequency regulation. Models of the power grid and the ESS were developed to verify the performance of the operation system and its control system. When a high capacity power plant is tripped, a 24 MW ESS supplies power automatically and 4 units of 125MW ESS supply power manually. This study only focuses on transient state analysis. It was verified that 500 MW ESS can regulate system frequency faster and more effectively than conventional power plants. Also, it was verified that time-delayed high speed operations of multiple ESS facilities do not negatively impact power system operations. It is recommended that further testing be conducted for a fleet of multiple ESSs with different capacities distributed over multiple substations (e.g. 16, 24, 28, and 48 MW ESS distributed across 20 substations) because each ESS measures frequency individually. The operation of one ESS facility will differ from the other ESSs within the fleet, and may negatively impact the performance of the others. The following are also recommended: (a) studies wherein all ESSs should be operated in automatic mode; (b) studies on the improvement of individual ESS control; and (c) studies on the reapportionment of all ESS energies within the fleet.

• 한국전자파학회논문지
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• 제21권12호
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• pp.1343-1351
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• 2010

본 논문에서는 metamaterial CRLH(Composite Right- and Left-Handed) 구조 기반의 새로운 패치 안테나를 설계 제작하여 측정하였다. 일반 마이크로스트립 패치 구조의 기본 공진 모드인 반파장 공진이나 반파장 공진의 양의 정수배와 달리 제안된 안테나는 구조 전체에 전계가 같은 위상을 갖게 한다. 본 논문에서 제안하는 안테나는 요구되는, $\lambda/4$ 모노폴 안테나의 전형적인 특성인 전방향 패턴을 갖는 동시에 low-profile의 장점을 가진다. 제안된 안테나의 전산 모의 실험에는 Ansoft사의 FEM(Finite Element Method) 방식의 HFSS(High Frequency Structure Simulator)를 사용하였다. 제안된 안테나는 두께 1.6 mm, 유전율 4.4의 FR-4 기판을 사용하여 제작하였다. 구현된 안테나는 S-DMB(Satellite-Digital Multimedia Broadcasting) 서비스에서 사용되는 2.63~2.655 GHz에서 VSWR(Voltage Standarding Wave Ratio)$\leq$2임을 만족하며, 측정된 최대 이득과 효율은 각각 2.65 dBi와 81.14 %이다.

• 복식
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• 제55권1호
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• pp.25-42
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• 2005

Costume is a formative art expressed by active human unlike the field of other living formativeness, and an expression of social actions based on a style of culture in a period. Therefore, costume has a deep connection with a mode of living and is recognized as a 'culture for living', and is more characteristic culture than all metaphysical cultures including architecture, craft, painting, and sculpture. Therefore, it expresses wearer's status or social standing, and furthermore, ideas and values of the times with aesthetic features in their form, color, materials, and pattern, so it is expressed as a mirror reflecting the phases of the times as. Korean costume had been dressed until the period of the Joseon Dynasty without a great change and started to be simplified in a simple style on the grounds of inconvenience in behaviors with the opening of an interchange of Western culture in the civilized period. And, this movement had been continued and Korean costume had been applied as an everyday dress under the name of 'Reformed Korean Costume'. Since the middle phase of 1980s, it aroused many people's interests with the introduction of designs focused on activity and convenience. In 1990's, many people had taken a growing interest in Korean costume with development of various designs keeping pace with the internationalization period and Korean Costume had been revitalized under the name of 'The Modernized Korean Costume'. And, since the 21st century, the advanced communication and full-scaled import of Western fashion have made the introduction of many fashion information in the world into Korea, affected greatly the fashion market, led consumers' sensitivity on a trend to be increased. Therefore, a design accepting a trend 'The Modernized Korean Costume' with fashions has risen. Second, this study is an attempt to suggest a revitalization method of domestic casual Korean costume brands by developing and suggesting competitive and highly value-added products with connection of practicality, variety, and highly sensitive fashion styles. For theoretical study, domestic and foreign literatures, academic journals, professional monthly magazines, and newspapers were examined. And, a process of change and features of the Korean fashion since the civilization period, and concept, features and images of casual Korean costume were analyzed, On the basis of analyzing image, features, and consumers' preference of the modernized Korean costume, a design development plan was established and 10 suits of costume were designed and made.

• Bulletin of the Korean Chemical Society
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• 제30권11호
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• pp.2559-2562
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• 2009

The lattice vibration and crystal structure of alkaline earth metal-substituted $RuSr_{1.9}A_{0.1}GdCu_{2}O_{8}$ (A = Ca, Sr, and Ba) have been investigated with micro-Raman spectroscopy. The present $RuSr_{1.9}A_{0.1}GdCu_{2}O_{8}$ materials show not only several weak Raman peaks corresponding to the vibrations of $O_{Cu}$ and $O_{Ru}$ but also strong characteristic phonon lines related to $O_{Sr}$ vibration mode. A comparison between the frequency of $O_{Sr}$ vibration and the bond distances of (Ru$O_{Sr}$) and (Cu‒$O_{Sr}$) in the present ruthenocuprates reveals that the vibration energy of $O_{Sr}$ is mainly dependent on the bond distance of (Ru‒$O_{Sr}$). The peak splitting of the $O_{Sr}$ phonon lines was observed for the unsubstituted $RuSr_{1.9}A_{0.1}GdCu_{2}O_{8}$, suggesting the existence of two different (Ru‒$O_{Sr}$) bond distances. Such a peak splitting caused by the appearance of low-energy shoulder reflects the presence of internal charge transfer pathway from the $RuO_2$ plane to the superconductive $CuO_2$ one. After the substitution of Sr with Ca or Ba, the low-energy shoulder peak of $O_{Sr}$ vibration becomes suppressed, underscoring the depression of internal charge transfer between the $RuO_2$ and $CuO_2$ planes. The weakened role of $RuO_2$ layer as charge reservoir in the $RuSr_{1.9}A_{0.1}GdCu_{2}O_{8}$8 (A = Ca, Ba) would be responsible for the depression of $T_c$ upon the Ca/Ba substitution.

• 대한기계학회논문집 C: 기술과 교육
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• 제5권2호
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• pp.135-143
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• 2017

국내 유일의 연구용원자로인 하나로(Hi-flux Advanced Neutron Application ReactOr)는 다목적으로 중성자를 이용하기 위해 개방형 수조 내 노심이 존재하는 구조이며, 노심에서 발생되는 핵분열 열을 제거하기 위한 일차 냉각계통, 그리고 연결된 유체계통이 구비되어 있다. 원자로 수조 상부 근방에서 진행되는 방사성 작업 시 작업자의 방사능 피폭을 최소화하기 위해 수조고온층계통에 의해 상부에 고온층이 형성되어 있으며, 다소 저온 영역에 있는 방사능 가스 및 이물질이 상부로 올라오는 것을 방지하기 위해 수조수 온도를 $50^{\circ}C$이하로 제한하고 있으며 이를 위해 수조수관리계통이 연결되어 있다. 수조수관리계통의 구비된 판형열교환기의 열용량을 정상운전 조건에서 260 kW가 되도록 설계하여 각 수조에서 발생되는 열원을 제거하는지에 대해 평가하였고, 원자로 운전 모드와 관계없이 정상적으로 유체계통이 운전된다면 각 수조의 수조수 온도는 제한치 이하를 유지하고 있음을 확인하였다.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2004년도 춘계학술대회 논문집
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• pp.29-33
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• 2004

본 논문에서는 패러데이 효과(Faraday effect)를 이용한 초고압 전력설비에서의 대전류 측정을 위한 광CT의 특성에 대한 기초 연구를 기술하였다. 1310[nm] Laser Diode를 광원으로 사용하고 PIN-Photodiode를 수신부로 사용하였다. 광의 전송로는 파이버 내에서 편광상태를 유지 할 수 있는 30[m]의 싱글모드 파이버를 사용하였다. 전류의 측정은 400[A]에서 1300[A]까지의 범위에서 측정하였으며 온도는 $20[^{\circ}C]$에서 $50[^{\circ}C]$까지 측정하였다. 동일한 실험 환경 하에서 출력의 크기는 인가전류가 증가할수록, 온도가 낮을수록 비례하여 증가하였다. 온도가 $50[^{\circ}C]$의 경우 최대 $50[^{\circ}C]$의 오차율을 나타냈으며, $40[^{\circ}C],\;30[^{\circ}C],\;20[^{\circ}C]$의 경우 각각 최대 오차 0.16[%], 1.24[%], 0.07[%]의 오차율을 보였다.

• The Korean Journal of Physiology and Pharmacology
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• 제2권3호
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• pp.297-305
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• 1998

This study used in vivo intracellular recording in rat hippocampus to evaluate the effect of lidocaine and MK-801 on the membrane properties and the synaptic responses of individual neurons to electrical stimulation of the commissural pathway. Cells in control group typically fired in a tonic discharge mode with an average firing frequency of $2.4{\pm}0.9$ Hz. Neuron in MK-801 treated group (0.2 mg/kg, i.p.) had an average input resistance of $3.28{\pm}5.7\;M{\Omega}$ and a membrane time constant of $7.4{\pm}1.8$ ms. These neurons exhibited $2.4{\pm}0.2$ ms spike durations, which were similar to the average spike duration recorded in the neurons of the control group. Slightly less than half of these neurons were firing spontaneously with an average discharge rate of $2.4{\pm}1.1$ Hz. The average peak amplitude of the AHP following the spikes in these groups was $7.4{\pm}0.6$ mV with respect to the resting membrane potential. Cells in MK-801 and lidocaine treated group (5 mg/kg, i.c.v.) had an average input resistance of $3.45{\pm}6.0\;M{\Omega}$ and an average time constant of $8.0{\pm}1.4$ ms. The cells were firing spontaneously at an average discharge rate of $0.6{\pm}0.4$ Hz. Upon depolarization of the membrane by 0.8 nA for 400 ms, all of the tested cells exhibited accommodation of spike discharge. The most common synaptic response contained an EPSP followed by early-IPSP and late-IPSP. Analysis of the voltage dependence revealed that the early-IPSP and late-IPSP were putative $Cl^--and\;K^+-dependent$, respectively. Systemic injection of the NMDA receptor blocker, MK-801, did not block synaptic responses to the stimulation of the commissural pathway. No significant modifications of EPSP, early-IPSP, or late-IPSP components were detected in the MK-801 and/or lidocaine treated group. These results suggest that MK-801 and lidocaine manifest their CNS effects through firing pattern of hippocampal pyramidal cells and neural network pattern by changing the synaptic efficacy and cellular membrane properties.

• 한국항해항만학회지
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• 제33권1호
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• pp.27-33
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• 2009

압축하중 및 횡하중의 조합하중을 받는 연속 보강판넬의 좌굴강도 및 최종강도의 평가는 선체구조 안정성을 재고하는데 아주 중요한 요소이다. 예를들면, 선박의 공창 상태에서 선체외판은 수압하중에 의해서 파생되는 횡방향 면내 압축하중과 선체외판에 작용하는 횡하중은 대표적인 하중 성분이다. 지금까지의 대부분의 연구 결과들은 실험테스트 및 이론석인 접근 그리고 수치계산 방법에 의해서 수행되었으며, 단일 판 또는 보강판의 조합하중에 대한 많은 업적들이 있다. 그러나, 이들 중 대부분의 연구는 종방향 면내 압축하중과 횡하중에 의한 연구결과가 대부분이며, 횡방항 면내 압축하중과 횡하중에 대한 결과들은 상대적으로 많지가 않다. 게다가 이전의 연구들은 주고 네변 단순지지된 판부재를 고려하였으나, 실제의 구조를 고려해보면, 횡방향 프레임과 종방향 거더들이 교차되어 있는 보강 판넬 구조이다. 본 연구는, 3척의 실적선에서 얻은 이중저 판넬 모델을 적용하고, 횡하중의 크기를 변수로 한 탄소성대변형 유한요소해석을 수행하였다. 이러한 여러 가지 수치 해석을 통하여, 횡하중의 크기 변화에 대한 영향과 횡방향 압축하중이 작용하는 붕괴 매커니즘에 대해서 고찰하였다.

• 유통과학연구
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• 제4권2호
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• pp.123-144
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• 2006

국민의 재산권 보호를 위하여 부동산거래의 불확실성 해소와 신뢰성 확보는 매우 중요하다. 생활양식의 변화에 따라 부동산시장은 다양화되고 부동산거래의 수준도 다양화되는데 비하여 부동산거래제도는 아직도 과거의 틀을 벗지 못하고 있다. 이에 능동적으로 대처해 나가기 위해서는 부동산 거래방식에 대한 재검토가 필요하며, 특히 현재의 중개계약방식을 선진화할 수 있는 방안을 검토할 필요가 있다. 전속중개계약과 부동산거래정보망제도는 이미 미국, 일본 등의 여러 선진국가에서 보편화된 제도이며 부동산중개업의 거래질서를 확립하고 부동산중개의뢰인의 재산권 보호 및 편익제공을 위해 권장 실시되고 있는 제도이다. 우리나라에서는 1993년 12월에 개정된 부동산중개업법에서 전속중개계약과 부동산거래정보망제도가 신설되었다. 그러나 여러 가지 문제로 말미암아 10여년이 지난 현재까지도 제대로 제도 정착이 안 되고 있는 실정이다. 이에 본 연구에서는 전속중개계약 및 부동산거래정보망제도 활성화에 대한 특성요인을 개발하여 요인별 상관관계를 살펴보고, 이러한 요인이 중개기능의 제고와 부동산중개업자의 신뢰성, 고객만족에 미치는 영향을 실증분석을 통하여 고찰하였다. 이를 바탕으로 현재 존재가치가 유명무실한 우리나라의 전속중개계약 및 부동산거래정보망제도에 대한 활성화방안과 정책적 시사점을 제시하였다.

• 한국분무공학회지
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• 제23권4호
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• pp.212-220
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• 2018

As increase the number of vehicles, the issue of greenhouse gas that was emitted by them became important. As a result, greenhouse gas (GHG) regulations are being strengthened and efforts are being actively made to reduce greenhouse gas emissions in the automotive industry. In the other hand, regulations for harmful emission of vehicles have been reinforced by step. Especially, the lastly applied step, so called Euro 6, not only decreased NOx limit down to half of Euro 5 but also introduced real driving emission limit for NOx and PN. It is a challenge for manufacturers to meet the recent GHG regulation as well as the latest emission regulation. To overcome these regulations a De-NOx after-treatment system is being applied to diesel vehicles that are known emitting the lowest GHG among conventional internal combustion engines. At the time of the introduction of Euro 6 emission standard in Korea, in the domestic fuel economy certification test, some diesel vehicles emitted more $CH_4$ than Euro 5 vehicles. As a result, it was confirmed that LNT-equipped vehicles emitted a high level $CH_4$ and the level exceeded the US emission standard. In order to determine the reason, various prior literature was investigated. However, it was difficult to find a detailed study on the methane increase with LNT. In this paper, to determine whether the characteristics of vehicles equipped with LNT the affects the above issue and other greenhouse gases, 6 passenger cars were tested on several emission test modes and ambient temperatures with a environment chamber chassis dynamometer. 2 cars of these were equipped with LNT only, other 2 cars had SCR only, and LNT + SCR were applied to remaining 2 cars. The test result shown that the vehicles equipped with LNT emitted more $CH_4$ than the vehicles with SCR only. Also, $CH_4$ tended to increase as the higher acceleration of the test mode. However, as the test temperature decreases, $CH_4$ tended to decreased. $CO_2$ was not affected by kinds of De-NOx device but characteristic of the test modes.