• Title/Summary/Keyword: Reserves

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Practical Applications of Reactive Power and Voltage Planning In Korea Power System (우리나라 계통에서의 무효전력 수급현황 및 전압특성 분석)

  • Lee, Joo-Ho;Jung, Eung-Soo
    • Proceedings of the KIEE Conference
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    • 2004.11b
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    • pp.158-161
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    • 2004
  • This paper presents practical applications of reactive power and voltage planning to obtain voltage stability and operational voltage level for 2005 year summer peak Korea power system. It also describes the new electric facilities, operation criteria, voltage levels, MVAr flows, reactive power reserves in each control area. And reactive compensation devices are installed to maintain established voltage levels and stability margins. This simulation results show the improvement of voltage levels and the increase of reactive margins & interface flow margins. Finally, the paper reports the necessity of dynamic reactive reserves. It can be applied to analysis reactive compensation requirements and P-V & V-Q curves by PSS/E & VSAT.

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Phenotypic Relationship between Lactation Persistency and Change in Body Condition Score in First-lactation Holstein Cows

  • Yamazaki, Takeshi;Takeda, Hisato;Nishiura, Akiko;Sasai, Youji;Sugawara, Naoko;Togashi, Kenji
    • Asian-Australasian Journal of Animal Sciences
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    • v.24 no.5
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    • pp.610-615
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    • 2011
  • We examined the correlations between lactation curve shape, including persistency and changes in body condition score (BCS) during early-stage (0 to 30 days in milk (DIM)), nadir-stage (31 to 90 DIM), and late-stage (91 to 240 DIM) lactation in 191 first-lactation cows. Data used were first-parity BCS records, scored twice every month after calving, and daily milk yields. Individual lactation curves were depicted by the Wilmink function. Lactation persistency was defined as the difference in estimated milk yields between 240 DIM and 60 DIM. Changes in BCSs in the early and late stages were defined as linear regression coefficients. There were no significant correlations between traits for lactation curve shape and change in BCS in early-stage lactation. Peak yield and total milk yield were negatively correlated with BCSs in nadir- and late-stage lactation and with BCS change in late-stage lactation, suggesting that cows with high lactation yields had low body reserves and health status in mid- to late lactation and had delayed recovery of body reserves. Lactation persistency was positively correlated with change in BCS in late-stage lactation, suggesting that cows with high lactation persistency tended to be healthy and to recover their body reserves well in late lactation.

An extension plan of Yakushima Biosphere Reserve as a case study of consensus building of islanders

  • Matsuda, Hiroyuki;Yumoto, Takakazu;Okano, Takahiro;Tetsuka, Kenshi;Fujimaki, Aomi;Shioya, Katsunori
    • Journal of Ecology and Environment
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    • v.38 no.2
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    • pp.241-247
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    • 2015
  • A participatory approach of local stakeholders is important to create a balance between nature protection and the sustainable use of natural resources in a nature reserve and its vicinity area. The zoning and management policy of biosphere reserves (BRs) is a good example of this idea, especially for island reserves. Yakushima was inscribed as a World Natural Heritage (WH) in 1993. Almost all of its residents did not remember that Yakushima was a BR. In addition, Yakushima has some problems in nature reserve management. Overabundance of the deer population is a critical threat to both agriculture and natural vegetation in the world heritage site. There are too many tourists visiting the WH site and Nagata-hama beach. The beach is a Ramsar site and one of the most important spawning grounds of sea turtles in the north Pacific. Now, residents and the municipality have decided to reactivate the Yakushima BR. Although the Ministry of the Environment of Japan has an initiative to manage the WH and the Ramsar site, the BR is managed by the municipality and local stakeholders. Local activities of both nature conservation and the sustainable use of natural resources are encouraged in the BR site. The islanders willingly included all areas of the island into the BR site. Scientists who have participated in the Society of Yakushimaology have played a significant role to build trust between local stakeholders and to seek feasible policies on the nature reserves. The concept of the "Yakushima Environmental Culture Village" is a good model for the extension plan of the Yakushima and Kuchinoerabujima BRs.

A Study on the Sudden Stop in Capital Flows and Foreign Exchange and Distribution Market Stability (자본유출입 급변동과 외환 및 유통시장 안정성에 관한 연구)

  • Kim, Yoon-Chul;Yi, Myung-Hoon
    • Journal of Distribution Science
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    • v.14 no.12
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    • pp.79-87
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    • 2016
  • Purpose - Since 1990, the sudden stop in capital flows has caused the economic crisis. The purpose of this research is to suggest the policy measures to mitigate the risk of the sudden stop in capital flows. To this end, we examine the theoretical framework and analyze the case study for countries which are faced with the sudden stop. Also we examine the structural problems of the foreign exchange market in Korea and derive the policy implications to prevent the sudden stop. Research design, data, and methodology - The criteria of whether the sudden stop in capital flows occurs are based upon Calvo et al. (2008). In case the proxy variable for the balance of capital account decreases from the average by over twice standard deviation, we determine that the sudden stop occurs for that country. The sample period is from January 1990 to December 2008, as in Calvo (2014). The sample countries are 17 developed countries and 19 emerging market countries, which are different from those of the previous papers as Agosin and Huaita (2012), and Calvo (2014). When the exchange market pressure index(EMPI) is deviated from the average by over three times standard deviation, we determine that the foreign exchange market is unstable for that country. Results - We find that the characteristics of the sudden stop in capital flows are the bunching or contagion among countries, the rapid drop in real effective exchange rate, and the huge decrease in foreign exchange reserves. Many countries tried to increase foreign exchange reserves and regulate capital flows. Also the foreign exchange market in Korea are found to be the volatile exchange rate, the vulnerable external debt and careless management of the foreign exchange derivatives transaction risk. Conclusions - To lessen the risk in the sudden stop of capital flows, this research suggests the some useful policy measures. To enhance the foreign exchange and distribution market stability, we should improve the price mechanism of exchange rate, hold the appropriate level of foreign exchange reserves, prevent excessive inflows of foreign exchange and promote sound transactions of foreign exchange derivatives.

Comparative Analysis of Factors in Country Risk between Cambodia and Vietnam (캄보디아와 베트남의 국가위험도 영향요인 비교 분석)

  • Lee, Changkeun;Choo, Yongsik
    • Journal of the Korean Regional Science Association
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    • v.34 no.2
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    • pp.65-77
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    • 2018
  • The purpose of this study is to compare and analyze factors in country risk between Cambodia and Vietnam. OECD and the Export-Import Ban of Korea assess country risk of Cambodia more highly than Vietnam. As results of the parametric tests for evaluation factors on the basis of country risk classification, the economic growth rate, the foreign trade index, and the foreign exchange reserves among the economic risks with the corruption index as the political and social risk have statistically significant effect on the difference between country risks of two countries. However, discriminant factor analysis indicates that the economic growth rate, the foreign exchange reserves, and the corruption index are key variables, which represent the difference between country risks of Cambodia and Vietnam. Consequently, the government of Cambodia needs to try to root out the corruption and to expand trade through increasing export for lowering the country risk to the level of Vietnam. Vietnam would also need to focus on attaining the sustainable high economic growth rate and increasing the foreign exchange reserves.

Status of Exploitable Groundwater Estimations in Korea (우리나라 지하수 개발가능량 산정의 현황과 전망)

  • Chung, Il-Moon;Kim, Jitae;Lee, Jeongwoo;Chang, Sun Woo
    • The Journal of Engineering Geology
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    • v.25 no.3
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    • pp.403-412
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    • 2015
  • We summarize the status of exploitable groundwater reserves in Korea based on reports of the National Basic Groundwater Plan, and review methods for estimating groundwater recharge rates, as recharge is a key factor in the estimation of exploitable groundwater reserves. We also outline the various methods used to assess exploitable groundwater reserves in previous groundwater investigation reports. Regarding advancements in the estimation of exploitable groundwater, we recommend that enhanced estimation methodologies (e.g., the water balance method and the advanced water table fluctuation method) and sustainable groundwater management concepts be adopted in the near future.