• 한국시스템다이내믹스연구
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• 제5권2호
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• pp.149-174
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• 2004

Since the economic crisis in 1997, the Korean government has implemented a number of reforms in order to eliminate inefficiencies in both private and public sectors. One of the reforms made in the public sector was to lower the retirement age of teachers from the original age of 65 to that age 62. The ultimate aim of this compulsory policy was to improve the quality level of education by hiring many young teachers instead of senior teachers. It was made based on the calculation that by lowering the retirement age by three years, the government can hire three young teachers with the saved wages. However, this policy has brought an unexpected result; the imbalance between the supply and demand for teachers has become a much more serious problem in Korea's elementary education system The purpose of this study is largely twofold; First of all, it aims to identify the scope of imbalances occurred in the supply-demand system of elementary school teachers in a region of the nation, and also to find out why such imbalance occurred. Secondly, the purpose of this study is to experiment with feasible policy alternatives and their effects on the system and to suggest some resolutions on the imbalance.

• 한국농공학회:학술대회논문집
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• 한국농공학회 1998년도 학술발표회 발표논문집
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• pp.279-286
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• 1998

The south-western part of Korea is situated in an unbalance of water supply and demand relating to the Keum, Mankyung, Dongjin and Youngsan River and their estuary reservoirs. For example, the Keum River estuary reservoir is discharging the larger amount of yearly runoff into the sea due to the small storage capacity, while Saemankeum estuary reservoir which is under construction, has the smaller runoff amount comparing with its storage capacity, And the downstream area of the Youngsan River, such as Youngkwang, Youngam are deficient in water due in larger demand and smaller supply. In order to solve the above unbalanced water supply and demand and also to improve the water use efficiency, the Hierarchical Operation Model for Multi-reservoir System(HOMMS) has been developed and applied to analyze the multi-reservoir operation assuming that the above reservoirs were linked each other. The result of this study shows that 2,148MCM of annual additional water requirement for agricultural and rural water demands are required in this region at 2011 of target year, and these demands can be resolved by diverting and reusing 1,913MCM of the released water from the estuary reservoirs into the sea.

• 전기학회논문지
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• 제67권2호
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• pp.173-178
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• 2018

This study organizes scenarios on the power supply and demand plans considering the uncertainties and the portion of distributed energy resources. In analysing the scenarios, it estimates total electricity supply cost in the social aspect, natural gas demand and air pollutants emission including carbon dioxide. Also the analysis is performed to estimate the marginal cost of carbon dioxide reduction for the fuel switching from coal to liquified natural gas. In result, the social cost could be decreased by replacing some portion of renewable energy by LNG-based combined heat and power and delaying the construction of large base-load generators such as coal and nuclear plants. The marginal carbon dioxide reduction cost by fuel switching is in plausible range for fuel switching to be an option for carbon dioxide emission reduction when the social cost is considered.

• 유기물자원화
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• 제24권2호
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• pp.31-39
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• 2016

저수조는 유입/유출량의 시간적인 편차 때문에 필요하다. 저수조 용량 산정하기 위해서 공급(예, 강수) 누적 량과 요구(예, 관수) 누적 량의 차이를 사용한다. (-)와 (+)영역의 상관없이 누적 량 차의 절댓값 최대치가 되었을 때 용량의 산정이 이루어진다. 본 논문에서는, 온실 시설물의 강수와 관수를 이용하여 비선형적인 공급이나 요구량에서도 이를 적용하여 용량을 산정하였고, 비선형적인 변화가 커졌을 시에도 적용 할 수 있음을 증명하였다. 그리고 모니터링에 대한 시간 간격이 작아짐에 따라서, 저수조 용량이 증가되며, 강수량의 경우에는 약 10일을 변곡점으로 증가폭이 감소됨을 보인다.

• 한국토양비료학회지
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• 제9권3호
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• pp.133-147
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• 1976

1. The purpose of this study is to provide a series of statistical "bench marks" from which one can begin to think systematically about the required development of the Korean food and fertilizer needs over the next quarter-century. 2. The Korean population has been estimated by the characteristics of the population and its social and political situations today. Because fertility and mortality rates are relatively stable and are under control of politics concerned, the estimation rates were established with 1.6% over 1975-1980, 1.3% over 1981-1990, and 1.0% over 1991-2000. 3. Annual per capita absorption of milled rice has fluctuated rather closely around 140kg, since 1968, with no evidence of declining trend. Per capita absorption of barley and wheat around 120 kg, and legumes around 10.6kg, However because the case of wheat and corn productions are rather difficult the self-sufficiency in the future, the rice is considered to be accelerate its yield growth surplus the level of self-sufficiency to export. 4. The fertilizer demand in each element has been calculated by mechanical multiplication of "the recommend index of fetilizer application" to yield a unit production over the need of national food supply by crop year. 5. As a results refer to Table (8), the estimated quantities of total fertilizer demand to meet the national food supply of the years of 1974, 1980, 1985, 1.990, 1995, and 2000 are reached around 871500, 1138150, 1375480, 1515030, 1652090 and 1799850 metric tons in each year.

• 대한한약학회:학술대회논문집
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• 대한한약학회 2007년도 Autumn Conference
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• pp.129-144
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• 2007

In order for stable demand-supply and regularity of distribution, "The regulations for management of demand-supply and distribution of medicinal herbs" were established on 1995. Therefore, the medicinal herbs of good quality have been controled to be distributed in the market. However, to be wide of the purpose, the standardized sound distribution system was caused due to the governmental control on demand-supply to protect domestic farmers who produce the material for medicinal herbs, which results in the over distribution of non-standardized or illegally imported medicinal herbs. In addition, because of the distribution of faulty or poor medicinal herbs, there are chances of affecting bad effects on public health. The standardized medicinal herbs cover 514 different kinds in total, of which 69 products are specified to be standardized in the oriental medicine product companies. Also, in order to protect farmers who produce the materials for medicinal herbs, the amount of imported materials are regulated in normal times. The 14 different materials for medicinal herbs, which are allowed to be imported to a certain amount only when the shortage of goods or sudden rise of prices is to happen, are frequently introduced into domestic market as food not as medical usage, and the origin of those illegally changes to home cropped one for the distribution in the market. In addition, the system of distribution are to be disordered and the condition for the distribution of medicinal herbs of good quality can not be made since they illegally changes the usage of the materials for medicinal herbs from their original one and can not be regulated by the domestic laws.

• 한국농공학회논문집
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• 제55권3호
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• pp.41-49
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• 2013

Drought risk assessment is usually performed qualitatively and quantitatively depending on the definition a drought. The meteorological drought indices have a limit of not being able to consider the hydrological components such as evapotranspiration, soil moisture and runoff, because it does not consider the water demand in paddies and water supply in reservoirs. Agricultural drought was defined as the reservoir storage shortage state that cannot satisfy water requirement from the paddy fields. The objectives of this study were to suggest improved agricultural drought risk assessment in order to evaluate of regional drought vulnerability and severity studied by using Reservoir Drought Index (RDI). The RDI is designed to simulate daily water balance between available water from agricultural reservoir and water requirement in paddies and is calculated with a frequency analysis of monthly water deficit based on water demand and water supply condition. The results indicated that RDI can be used to assess regional drought risk in agricultural perspective by comparing with the historical records of drought in 2012. It can be concluded that the RDI obtained good performance to reflect the historical drought events for both spatially and temporally. In addition, RDI is expected to contribute to determine the exact situation on the current drought condition for evaluating regional drought risk and to assist the effective drought-related decision making.

• KIEE International Transactions on Power Engineering
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• 제5A권3호
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• pp.214-220
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• 2005

In order to improve energy efficiency and solve power disturbances, power components measurement for both the supply and demand side of a power system must be implemented before appropriate action on the power problems can be taken. This paper presents a DSP (Digital Signal Processor)-based multi-channel (voltage 8-channel and current 10-channel) power measurement system that can simultaneously measure and analyze power components for both supply and demand. Voltage 8-channel and current 10-channel measurement is made through voltage and current sensors connected to the developed system, and power components such as reactive power, power factor and harmonics are calculated and measured by the DSP. The measured data are stored in a personal computer (PC) and a commercial program is then used for measurement data analysis and display. After voltage and current measurement accuracy revision using YOKOGAWA 2558, the developed system was tested using a programmable ac power source. The test results showed the accuracy of the developed system to be about 0.3 percent. Also, a simultaneous measurement field test of the developed system was implemented by application to the supply and demand side of the three-phase power system.

• Journal of Electrical Engineering and Technology
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• 제9권5호
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• pp.1454-1470
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• 2014

This paper propose a new power conditioner topology with intelligent power management controller that integrates multiple renewable energy sources such as solar energy, wind energy and fuel cell energy with battery backup to make best use of their operating characteristics and obtain better reliability than that could be obtained by single renewable energy based power supply. The proposed embedded controller is programmed for maintaining a constant voltage at PCC, maximum power point tracking for solar PV panel and WTG and power flow control by regulating the reference currents of the controller on instantaneous basis based on the power delivered by the sources and load demand. Instantaneous variation in reference currents of the controller enhances the controller response as it accommodates the effect of continuously varying solar insolation and wind speed in the power management. The power conditioner uses a battery bank with embedded controller based online SOC estimation and battery charging system to suitably sink or source the input power based on the load demand. The simulation results of the proposed power management system for a standalone solar/WTG/fuel cell fed hybrid power supply with real time solar radiation and wind velocity data collected from solar centre, KEC for a sporadically varying load demand is presented in this paper and the results are encouraging in reliability and stability perspective.

• 한국산학기술학회논문지
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• 제9권3호
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• pp.831-839
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• 2008

전 세계적으로 철강산업의 중요성은 높아지고 있으며, 철강수요 역시 증가하고 있는 추세이다. 한국 철강산업의 철강생산량은 전 세계에서 5위를 차지하고 있어 국내에서는 철강산업에 대한 관심이 커져가고 있다. 또한 철강산업은 국내에서 경제성장을 이끌어 온 국가기간산업중의 하나이다. 이에 본 연구에서는 산업연관분석을 이용하여 철강산업이 국민경제에 미치는 파급효과들을 시계열로 분석하여 보고자 한다. 먼저 수요유도형 모형을 이용하여 생산유발효과, 부가가치 유발효과 그리고 취업유발효과를 살펴 볼 것이며, 아울러 공급유도형 모형 및 레온티에프 가격모형을 적용하여 철강산업의 공급지장효과와 물가파급효과에 대하여 살펴보고자 한다.