• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 A
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• pp.418-419
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• 2006

After electricity power industry restructuring, "Long term power development plan", setting up by government, is replaced by "Basic plan of electricity supply and demand". In this basic plan, one of the most important factors is assessment of appropriate capacity margin. The benefit of GENCO is decided by the market price, and the price is largely affected by the level of reserve margin. As a consequence, appropriate reserve margin is determined by market power. However, Cost Based Pool(CBP) is a limited competitive market, and government policy for supply and demand is very important factor or reserve margin determination. This paper points out issues about existing reserve margin assessment method which is used in basic plan and suggests improved assessment method. In the case study, capacity margin is calculated by proposed assessment method and result shows the advantages of suggested method.

• KEPCO Journal on Electric Power and Energy
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• 제2권3호
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• pp.425-431
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• 2016

Supply Capability of the generator, if the maximum demand occurs, refers to the maximum power that can be stably supplied and it is possible to maintain stable power supply to be greater than actual load. However, unexpected power demand and reduction in supply Capability due to stop of unexpected generator in operation can temporarily make a big chaos in power system. In fact, due to a lack of power supply Capability in the country, enforced emergency load adjustment to the September 15, 2011, the circulation power outage has occurred in several cities. As the result, interrupted operation of the elevator and stopped hospital medical equipment led to a great deal of trouble to people's lives, causing a social problem. At that time, it was found that a failed frequency control because of smaller actual supply Capability than that of predicted. The difference was about 1,170 MW with Gas turbine power plant. By accurately calculating the generator supply capability, we can not only grasp the power reserve rate, but also correspond to the time of power supply instability.

• 산업경영시스템학회지
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• 제44권4호
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• pp.220-226
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• 2021

In supply chain, there are a variety of different uncertainties including demand, service time, lead time, and so forth. The uncertainty of demand has been commonly studied by researchers or practitioners in the field of supply chain. However, the uncertainty of upstream supply chain has also increased. A problem of uncertainty in the upstream supply chain is the fluctuation of the lead time. The stochastic lead time sometimes causes to happen so called the order crossover which is not the same sequences of the order placed and the order arrived. When the order crossover happens, ordinary inventory policies have difficult to find the optimal inventory solutions. In this research, we investigate the lead time distribution in case of the order crossover and explore the resolutions of the inventory solution with the order crossover.

• 지능정보연구
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• 제22권4호
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• pp.45-67
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• 2016

최근 정보 유통의 주요 매체인 인터넷 뉴스와 SNS의 매체 간 특성 차이를 주목한 많은 연구가 있었음에도 불구하고, 양 매체의 차이를 정보의 수요 및 공급 관점에서 파악한 연구는 상대적으로 매우 부족하다. 일반적으로 새로운 정보는 언론사의 뉴스 기사를 통해 대중에게 노출되고, 대중은 이러한 기사에 대한 의견 또는 추가정보를 SNS를 통해 공유함으로써 해당 정보를 수용함과 동시에 확산시킨다. 이러한 측면에서 언론사가 뉴스를 제공하는 행위를 정보의 공급으로 파악할 수 있으며, 대중은 SNS를 통해 이에 대한 관심을 능동적으로 나타냄으로써 해당 정보에 대한 소비 수요를 표출하는 것으로 이해할 수 있다. 이는 상품 및 서비스의 가격이 수요와 공급의 관계에 의해 결정되는 것과 유사한 원리로, 정보의 가치를 정보 수요와 정보 공급의 관계에 기반을 두어 측정할 수 있음을 시사한다. 본 연구에서는 정보 공급의 대표 매체로 인터넷 뉴스 기사를, 정보 수요를 나타내는 대표 매체로 트위터를 선정하고, 특정 이슈에 대한 뉴스의 정보로서의 가치를 이와 관련된 트위터의 양으로 평가하는 뉴스가치지수(NVI, News Value Index)를 고안하여 제시한다. 구체적으로 제안 방법론은 각 이슈별로 NVI를 도출하고 이를 통해 시간의 흐름에 따른 정보 가치의 변화를 시각화하여 나타낸다. 또한 본 연구에서는 제안 방법론의 실무 적용 가능성을 평가하기 위해 인터넷 뉴스 387,018건과 트윗 31,674,795건에 대한 실험을 수행하였다. 그 결과 대부분의 이슈가 전체 정보 시장의 평균 가치에 수렴하는 형태로 변화함을 알 수 있었으며, 꾸준히 평균 이상의 가치를 가지며 정보 시장을 장악하는 등 특이한 양상을 보이는 흥미로운 이슈도 존재함을 파악할 수 있었다.

• 품질경영학회지
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• 제36권4호
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• pp.93-101
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• 2008

The rare metals, used for semiconductors, PDP-LCS and other specialized metal areas necessarily, has been playing a key role for the Korean economic development. Rare metals are influenced by exogenous variables, such as production quantity, price and supplied areas. Nowadays the supply base of rare metals is threatened by the sudden increase in price. For the stable supply of rare metals, a rational demand outlook is needed. In this study, focusing on the domestic demand for chromium, the uncertainty and probability materializing from demand and price is analyzed, further, a demand forecast model, which takes into account various exogenous variables, is suggested, differing from the previously static model. Also, through the OOS(out-of-sampling) method, comparing to the preexistence ARIMA model, ARMAX model, multiple regression analysis model and ECM(Error Correction Mode) model, we will verify the superiority of suggested model in this study.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.96.6-96
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• 2001

A high peak power demand at substations will result under Moving Block Signalling (MBS) when a dense queue of trains begins to start from a complete stop at the same time in an electrified railway system. This may cause the power supply interruption and in turn affect the train service substantially. In a recent study, measures of Starting Time Delay (STD) and Acceleration Rate Limit (ARL) are the possible approaches to reduce the peak power demand on the supply system under MBS. Nevertheless, there is no well-defined relationship between the two measures and peak power demand reduction (PDR). In order to attain a lower peak demand at substations on different traffic conditions and system requirements, an expert system is one of the possible approaches to procure the appropriate use of peak demand reduction measures ...

• 제어로봇시스템학회논문지
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• 제15권10호
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• pp.1056-1061
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• 2009

This paper proposes a short-term water demand forecasting algorithm based on kalman filtering with data mining for sustainable water supply and effective energy saving. The proposed algorithm utilizes a mining method of water supply data and a decision tree method with special days like Chuseok. And the parameters of MLAR (Multi Linear Auto Regression) model are estimated by Kalman filtering algorithm. Thus, we can achieve the practicality of the proposed forecasting algorithm through the good results applied to actual operation data.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 A
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• pp.298-300
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• 2004

Arc-furnace facilities consume 9,895,165(MWh) which is about 69.6 Percent of electronic furnace power consumption. and interior of a country demand power have inclosed annual. but becaused of the problem of cost, power plant location, and environment have faced difficulty to electric power supply. In this paper, Examining Load cutting of Arc-furnace that is dominating high weight of industry electric power use. and it is expected to solve easily electric power supply and demand problem by highest Priority load cutting examination of Arc-furnace when electric power supply and demand problem happens to area electric power system when is urgent.

• 한국농공학회논문집
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• 제63권3호
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• pp.75-85
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• 2021

This study evaluated variations in the paddy rice water demand based on the continuous changing in rice transplanting period and ponding depth at the four study paddy fields, which represent typical rice producing regions in Korea. Total 7 scenarios on rice transplanting periods were applied while minimum ponding depth of 0 and 20 mm were applied in accordance with maximum ponding depth ranging from 40 mm to 100 mm with 20 mm interval. The weather data from 2013 to 2019 was also considered. The results indicated that the highest rice water demand occurred at high temperature and low rainfall region. Increased rice transplanting periods showed higher rice water demand. The rice water demand for 51 transplanting days closely matched with the actual irrigation water supply. In case of ponding depth, the results showed that the minimum ponding depth had a proportional relationship with rice water demand, while maximum ponding depth showed the contrary results. Minimum ponding depth had a greater impact on rice water demand than the maximum ponding depth. Therefore, these results suggest that increasing the rice transplanting period, which reflects the current practice is desirable for a reliable estimation of rice water demand.

• 수산경영론집
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• 제41권3호
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• pp.59-78
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• 2010

This paper tries to apply the asymmetrical price transmission(APT) behavior observed in the agricultural industry to supply chains of the domestic fishery industry by a statistical manner. The fore mentioned asymmetrical price transmission refers to when price movements in the later stage of the supply chain do not move in a normal or symmetrical manner corresponding to price movements in the earlier stage of the supply chain. Therefore, when the earlier stage price increase and the later stage price increases to a larger degree, it is called positive(+) asymmetry and the opposite behavior is called negative(-) asymmetry. The study examines the data from domestic producers of three fresh fish types, hairtail, mackerel, and cuttlefish, and tries to examine the price asymmetry between the producer or farm, wholesaler, and retail prices via an APT test utilizing unit root, cointegration, and error correction model. The study found, hairtail wholesale and retail pricing bas a negative asymmetric relationship while mackerel has a negative asymmetric pricing relationship at the producer and retail levels of the supply chain. In the case of cuttlefish, all levels of the supply chain showed negative asymmetrical behavior in the supply chain price transmission, meaning the earlier stage price changes are more rapidly and greatly inputted in the later stage of the supply chain pricing. We believe that the reason why the analysis results show negative price asymmetry is due to the uniqueness of fishery products having an important variable such as freshness. If price increases are greater and quicker than price decreases, then consumer demand, which is sensitive to price increases will decrease and subsequently result in the increase of inventory levels, reducing profits for retailers. Also, frozen hairtail, mackerel, and cuttlefish will act as substitute goods to fresh fishery products. Therefore, fresh fishery products have a high demand of price elasticity. When prices increase, demand quickly decreases. Therefore the profit of wholesalers and retailers to decrease, I think this is the main reason of APT in the supply chain of Korea' s fisheries industry.