• 전기학회논문지
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• 제62권4호
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• pp.457-466
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• 2013

Wind energy is rapidly becoming significant generating technologies in electricity markets. As probabilistic nature of wind energy creates many uncertainties in the short-term scheduling, additional actions for reliable market operation should be taken. This paper presents a novel approach to evaluate ramping capability requirement for changes in imbalance energy between day-ahead market and real-time market due to uncertainty of wind generation as well as system load. Dynamic ramp rate model has been applied for realistic solution in unit commitment problem, which is implemented in day-ahead market. Probabilistic optimal power flow has been used to verify ramping capability determined by the proposed method is reasonable in economic and reliable aspects. This approach was tested on six-bus system and IEEE 118-bus system with a wind farm. The results show that the proposed approach provides ramping capability information to meet both forecasted variability and desired confidence level of anticipated uncertainty.

• 대한전자공학회논문지SD
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• 제41권2호
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• pp.77-83
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• 2004

on-chip 상에서 발생하는 누화 잡음은 신호의 충실성을 위협하는 매우 중요한 요소이다. 따라서 본 논문에서는 최대 누화잡음의 크기를 예측하는 해석적인 방법을 제안한다. 정확한 잡음 수치를 예측하기 위해 연결선의 인덕턴스 성분을 고려하였고, 임의의 램프입력을 사용하였다. 또한 복잡한 누화 잡음 모형에서 최대 누화 잡음을 해석적으로 간단히 구하기 위해 가상의 소스 개념을 도입하였다. 된 연구에서 제안한 방법은 HSPICE 시뮬레이션 결과와 비교하여 최대 상대오차 4.3％ 이내의 정확도를 보였다. 따라서 본 연구는 신호 충실성 보장을 위한 다양한 설계 보조 도구 개발에 활용될 수 있을 것으로 본다.

• Advances in aircraft and spacecraft science
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• 제4권6호
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• pp.651-677
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• 2017

For the past ten years' efforts have been made to introduce environmentally-friendly "green" electric-taxi and maneuvering airplane systems. The stated purpose of e-taxi systems is to reduce the taxiing fuel expenses, expedite pushback procedures, reduce gate congestion, reduce ground crew involvement, and reduce noise and air pollution levels at large airports. Airplane-based autonomous traction electric motors receive power from airplane's APU(s) possibly supplemented by onboard batteries. Using additional battery energy storages ads significant inert weight. Systems utilizing nose-gear traction alone are often traction-limited posing serious dispatch problems that could disrupt airport operations. Existing APU capacities are insufficient to deliver power for tractive taxiing while also providing for power off-takes. In order to perform comparative and objective analysis of taxi tractive requirements a "standard" taxiing cycle has been proposed. An analysis of reasonably expected tractive resistances has to account for steepest taxiway and runway slopes, taxiing into strong headwind, minimum required coasting speeds, and minimum acceptable acceleration requirements due to runway incursions issues. A mathematical model of tractive resistances was developed and was tested using six different production airplanes all at the maximum taxi/ramp weights. The model estimates the tractive force, energy, average and peak power requirements. It has been estimated that required maximum net tractive force should be 10% to 15% of the taxi weight for safe and expeditious airport movements. Hence, airplanes can be dispatched to move independently if the operational tractive taxi coefficient is 0.1 or higher.

• Journal of Electrical Engineering and Technology
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• 제4권3호
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• pp.353-359
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• 2009

This paper proposes a novel technique for calculating the security costs that properly includes ramping constraints in the operation of a deregulated power system. The ramping process is modeled by a piecewise linear function with certain assumptions. During this process, a ramping cost is incurred if the permissible limits are exceeded. The optimal production costs of the power producers are calculated with the ramping cost included, considering a time horizon with N-1 contingency cases using contingency constrained optimal power flow (CCOPF), which is solved by the primal-dual interior point method (PDIPM). A contingency analysis is also performed taking into account the severity index of transmission line outages and its sensitivity analysis. The results from an illustrative case study based on the IEEE 30-bus system are analyzed. One attractive feature of the proposed approach is that an optimal solution is more realistic than the conventional approach because it satisfies physical constraints, such as the ramping constraint.

• 한국문헌정보학회지
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• 제38권4호
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• pp.167-178
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• 2004

본 연구는 '장애인${\cdot}$노인${\cdot}$임산부 등의 편의증진보장에 관한 법률 시행규칙(1999)'에서 정한 공공도서관의 편의시설의 세부기준과 노인의 표준인체지수를 비교분석하여 시행규칙의 세부기준에서 제시한 수치가 노인에게도 적합한지를 조사 분석한다. 본 연구에서 조사대상으로 선정한 편의시설의 종류는 출입구(문), 복도 및 통로, 계단, 승강기, 에스컬레이터, 경사로, 대변기 소변기, 접수대 또는 작업대, 그리고 우체통으로 총 10가지이며, 이들 각각의 세부기준에 대한 적합성을 밝힌다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2005년도 제25회 추계학술대회논문집
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• pp.64-71
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• 2005

효과적인 초음속 연소를 위해 연료와 공기의 빠른 혼합이 필요하며, 혼합 향상을 위해 연료분사 방식에 대한 여러 연구들이 수행되어 왔다. 본 연구에서는 길이-깊이 비가 4.8, 후면 경사각이 $22.5^{\circ}$인 개방형 공동 모델을 사용하였으며, 마하수 1.92에서 운동량비에 따른 분사구 주변의 유동 특성 및 연소실 내 압력 분포를 슐리렌 가시화와 압력 측정을 사용하여 파악하였다. 운동량비는 연료의 침투거리와 분사지역의 유동에 큰 영향을 끼친다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2011년도 제37회 추계학술대회논문집
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• pp.613-617
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• 2011

한국항공우주연구원은 비행시험용 스크램제트 엔진의 최적 형상을 도출을 목표로 추력 노즐 변화에 따른 스크램제트 엔진의 특성을 파악하고자 여러 가지 형상의 추력 노즐을 설계 및 제작하였다. 성능시험은 호주 University of Queensland의 T4 충격파 터널에서 수행되었으며, 총 8종의 노즐과 2 종의 측벽이 시험되었다. 본 논문에는 스크램제트 엔진의 추력 노즐과 측벽의 설계 및 사양을 정리하였다. 또한 스크램제트 엔진 Baseline의 정압력과 노즐 출구 피토 압력 분포를 계산한 결과 양의 비추력을 얻었음을 확인하였다.

• 한국실내디자인학회논문집
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• 제41호
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• pp.215-225
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• 2003

The residential and welfare facilities for the elderly are continuously increasing due to change of value on family under situation of aging population increase. And it is predicted that accommodation capacity of facilities for the elderly and its rate those facilities takes compared to whole social welfare facilities will be accelerated considering past increase speed. On the other hand, about 60% of the elderly have low physical and mental level almost close to disabled people therefore special environmental concerns helping their independent living are necessary. Among them, color application is one of the most important factors for smooth understanding, communication and psychological remedy effect for them. The purpose of this study is to analyze the interior color status in assisted living facilities for the elderly in America which is a leading country in terms of the understanding and policy for the elderly as a part of the research project to suggest the developed solution about the Korean residential welfare facilities for the elderly For this purpose, not only importance and effect of color and visual characteristics and reaction to color in elderly environment but also general concept and policy of the ‘assisted living facility’ in America were researched through documents review. And measuring of color on 5 main spaces such ; lobby/lounge, corridor, dining room, bedroom, stairway/ramp of the 10 facilities in America were performed under analysis of its functional and aesthetic level based on Moon & Spencer's color theory.

• 한국측량학회지
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• 제24권5호
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• pp.425-431
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• 2006

최근 정부는 제4차 국토종합계획을 수정 보완하는 등 국토의 균형발전에 많은 노력을 경주하고 있다. 그러나, 기존 도로의 교통사고발생은 OECD 29개 국가 중 최하위권인 25위로 머물러있는 실정이다. 따라서 본 연구에서는 고속국도 및 국도 등에서 교통사고가 가장 많이 발생하고 있는 입체교차시설인 인터체인지 분기점의 기존 설계기준에 대한 문제점을 분석하여 적합한 설계속도를 제안하고자 한다. 그 결과로 교통사고를 미연에 방지하고 안전하고 쾌적한 도로조건 확보 및 교통용량의 극대화 등 도로기능을 극대화할 수 있는 유출입 접속부에서의 설계속도를 얻고자 한다.

• 한국초전도ㆍ저온공학회논문지
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• 제14권3호
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• pp.53-59
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• 2012

Adiabatic demagnetization refrigerator (ADR) for hydrogen re-liquefaction operating between 24 K and 20 K has been designed. $Dy_{0.9}Gd_{0.1}Ni_2$, whose Curie temperature is 24 K, is selected as a magnetic refrigerant. The magnetic refrigerant powder is sintered with oxygen-free high purity copper (OFHC) powder to enhance its effective thermal conductivity as well as to achieve relatively high frequency. A perforated plate heat exchanger (PPHE) operated with forced convection is utilized as a heat switch. The forced convection heat switch is expected to have fast response relative to a conventional gas-gap heat switch. A conduction-cooled high Tc superconducting (HTS) magnet is employed to apply external magnetic field variation on a magnetic refrigerant. $2^{nd}$ generation GdBCO coated conductor HTS tape with Kapton$^{(R)}$ insulation (SUNAM Inc.) will be utilized for the HTS magnet. The magnetization and demagnetization processes are to be achieved by the AC operation of the HTS magnet. The designed magnetic field and target ramp rate of the HTS magnet are over 4 T with 180 A and 0.4 T/s, respectively. AC loss distribution on HTS magnet is theoretically estimated.