• The Korean Journal of Ecology
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• 제24권6호
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• pp.365-370
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• 2001

The vegetation of the Khogno Khan Natural Reserve of the central Mongolia was studied in terms of the Zurich-Montpellier School's method. Twenty plant communities were identified from the three different landscape types such as mountain areas(63%), plains(32%), and wetlands(5%). Actual vegetation map using five vegetation domains was accomplished in order to understand the spatial distribution of regional vegetation. Steppe vegetation of 88% vegetation cover to the whole area is representative, which is composed of a matrix of landscape. The birch-aspen forests and the elm bush forests are relics as a patch distribution. It is recognized that the whole territory of protected area be under the effects of severe grazing from the phytosociological viewpoint.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2003년도 춘계종합학술대회
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• pp.594-597
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• 2003

본 연구에서는 DLC와 경제운용을 연계시킴에 있어 계통운전예비력 특성을 감안할 수 있도록 하였다. 우선, 새로이 제약조건을 정식화하여 계통운전예비력을 고려하였으며 3차원 동적계획법을 적용하여 이들을 연계토록 한 결과, DLC와 경제운용을 동시에 경제적으로 구할 수 있게 하였다. 제안한 방법을 시험계통에 적용하여 종래의 방법보다 우수함을 입증하였다.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 2001년도 추계학술대회 논문집
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• pp.199-202
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• 2001

This article deals with stochastic reliability systems that include a repair facility and unreliable machines: the main facility of working and an auxiliary facility of "super-reserve" machines. The number of super-reserve machines are random number with a arbitrarily distribution and working machines break down exponentially. Defective machines line up for repair, whose durations are arbitrarily distributed. Refurbished machines return to the main facility. If the main facility is restored to its original quantity, the repair facility leaves on routine maintenance until all of super-reserve machines are exhausted. Then, the busy period is regenerated. The whole system also falls into the category of closed queues, with more options than those of basic models. The techniques include two-variate Markov and semi-regenerative processes, and a duality principle, to find the probability distribution of the number of intact machines. Explicit formulas obtained demonstrate a relatively effortless use of functionals of the main stochastic characteristics (such as expenses due to repair, maintenance, waiting, and rewards for higher reliability) and optimization of their objective function. Applications include computer networking, human resources, and manufacturing processes.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 A
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• pp.417-419
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• 2005

This paper presents the effects and the regional power distribution of an increase or a decrease of a power reserve by load flow calculations under seasonal load patterns of each country for the future power shortages faced by the metropolitan areas or by the southeastern area of the South Korea in North-East Asia. In these connections, the types of a power transmission for interconnection consist of the 765kV HVAC and the HVDC. In this paper, the various cases of the power system interconnections in Far-East Asia are presented, and the resulting interconnected power systems are simulated by means of a power flow analysis performed with the PSS/E 28 version tool. The power flow map is drawn from data simulated and the comparative study is done. In this future, a power flow analysis will be considered to reflect the effects of seasonal power exchanges And the plan of assumed scenarios will be considered with maximum or minimum power exchanges during summer or winter in North-East Asia countries.

• 에너지공학
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• 제21권3호
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• pp.221-227
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• 2012

The CANDU 9 shield cooling system was designed and layout with the objective of promoting natural circulation on loss of forced flow. In the present study, the shield cooling natural circulation was analyzed using verified the thermal-hydraulic code when the coolant pump or the heat exchanger was lost. This study showed that thermosyphoning cooled the end shields and prevented the end shields and the reserve water tank from boiling for at least 8 hours on loss of the shield cooling pumps but the heat exchangers still operational. With the loss of both pumps and heat exchangers, the end shields remain subcooled for up to 4 hours. To enhance thermosyphoning, the bypass connection to the line from the reserve water tank should be relocated to a point as low as possible.

• 대한핵의학회지
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• 제39권2호
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• pp.118-123
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• 2005

Positron emission tomography (PET) serves as a gold standard for noninvasive in vivo measurement of myocardial blood flow (MBF) and coronary flow reserve (CFR). CFR can be defined as the ratio of maximally vasodilated MBF over its basal flow. It is an important parameter for the evaluation of functional severity of coronary stenosis and prognositification in various diseases such as dilated cardiomyopathy. $^{13}NH_3,\;H_2^{15}O,\;^{82}Rb$ are widely used radiopharmaceuticals for measuring MBF and CFR, This review introduces imaging techniques and its clinical utility. Cardiac application or PET and PET/CT is expected to be increased in near future.

• 대한전기학회논문지
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• 제37권6호
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• pp.331-338
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• 1988

A simple algorithm is presented for solving the thermal unit commitment problem which is one of very important areas in economic operation of power systems. This algorithm is based on simple priority ordering by the unit operation cost and it is shown that the operation cost of chosen sets of generators is the minimum. The proposed method differs from the conventional priority-based formulations in that the unit operation are calculated in every load level. Further the poerating reserve requiements are satisfied by the newly derived analytical security function or the expectation of reserve. The proposed method is proven to be very simple, accurate and efficient in a sample system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 추계학술대회 논문집 전력기술부문
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• pp.182-184
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• 2001

This paper presents the application draft of system frequency and reserve criteria for Korean Wholesale Electricity Market. This application draft of system frequency and reserve criteria is based on frequecy, voltage control rules and technical rules for ancillary services agreements prepared by KEMA and the present conditions of KEPCO system operations and future directions.

• Smart Structures and Systems
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• 제6권9호
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• pp.1007-1023
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• 2010

This paper describes the development and evaluation of an innovative TDR distributed moisture sensor. This sensor features advantages of being responsive to the spatial variations of the soil moisture content. The geometry design of the sensor makes it rugged for field installation. Good linear calibration is obtained between the sensor measured dielectric constant and soil physical properties. Simulations by the finite element method (FEM) are conducted to assist the design of this sensor and to determine the effective sampling range. Compared with conventional types of moisture sensor, which only makes point measurement, this sensor possesses distributed moisture sensing capability. This new sensor is not only easy to install, but also measures moisture distribution with much lower cost. This new sensor holds promise to significantly improve the current field instruments. It will be a useful tool to help study the influence of a variety of moisture-related phenomena on infrastructure performance.

• KIEE International Transactions on Power Engineering
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• 제11권X00호
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• pp.27-32
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• 2001

This paper presents a concept of reactive reserve based contingency constrained optimal power flow (RCCOPF). RCCOPF for enhancement of interface flow limit is composed of two modules, which are the modified continuation power flow (MCPF) and reactive optimal power flow (ROPF). In RCCOPF, two modules are repeatedly performed to increase interface flow margins of selected contingent states until satisfying the required enhancement of interface flow limit. In numerical simulation, a simple example with New England 39-bus test system is shown.