• The Science & Technology
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• v.7 no.3 s.58
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• pp.27-28
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• 1974

• Journal of Service Research and Studies
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• v.6 no.4
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• pp.75-85
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• 2016

Coal can be divided into thermal coal and coking coal. The price of thermal coal is basically affected by demand and supply. However, many other factors with regard to economic condition such as exchange rate, economy growth rate also make an influence on the price. This study is targeted to develop a forecast model for thermal coal price by using System Dynamics Method. System dynamics provides results that better reflect the real world by employing an inter-dependent system of variables. This study found out that 8 factors have important influence on the thermal coal price. Most of the data of the variables were acquired from the Bloomberg Database. The period extends to 2 years and 4 months, from May of 2011 to August of 2013. The causal relations among the variables were acquired by regression analysis

• Analytical Science and Technology
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• v.13 no.1
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• pp.5-11
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• 2000

During the commissioning period in Tonghae thermal power plant which is the largest circulating fluidized bed boiler in the nation, a considerable amount of clinker was formed at FBAC and seal pot. Various attempts, for example, concentration analysis, surface phenomena, thermal characterization, and crystal structure of ash, bed sand, limestone, clinker, and mixture of each gradients have been studied to identify the causes of clinker formed in circulating fluidized bed boiler. As the results, the characterization of black particles in which separated from the clinker is more similar to that of bed sand, on the other hand, white particles are more similar to ash. In addition, the sintering temperature of sand is over $1,200^{\circ}C$ and this temperature was decreased as limestone is added to bed material. The cause of clinker was proved that ash was sticked to molten or sintered sand or limestone in the area of high temperature in the circulating system.

• Environmental and Resource Economics Review
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• v.15 no.4
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• pp.673-692
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• 2006

In order to test for the dynamic optimality condition for the use of nonrenewable resource, it is necessary to estimate the shadow value of the resource in situ. In the previous literatures, a time series for in situ price has been derived either as the difference between marginal revenue and marginal cost or by differentiating with respect to the quantity of ore extracted the restricted cost function in which the quantity of ore is quasi-fixed. However, not only inconsistent estimates are likely to be generated due to the nonmalleability of capital, but the estimate of marginal revenue will be affected by market power. Since firms will likely fail to minimize the cost of the reproducible inputs subject to market prices under realistic circumstances where imperfect factor markets, strikes, or government regulations are present, the shadow in situ values obtained by estimating the restricted cost function can be biased. This paper provides a valid methodology for checking the dynamic optimality condition for a nonrenewable resource by using the input distance function. Our methodology has some advantages over previous ones: only data on quantities of inputs and outputs are required; nor is the maintained hypothesis of cost minimization required; adoption of linear programming enables us to circumvent autocorrelated errors problem caused by use of time series or panel data. The dynamic optimality condition for domestic coal mining does not hold for constant discount rates ranging from 2 to 20 percent over the period 1970~1993. The dynamic optimality condition also does not hold for variable rates ranging from fourth to four times the real interest rate.

• Korean Chemical Engineering Research
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• v.57 no.3
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• pp.400-407
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• 2019

Oxy-combustion with a circulating fluidized bed (Oxy-CFBC) technology has been paid attention to cope with the climate change and fuel supply problem. In addition, Oxy-CFBC technology as one of the methods for carbon dioxide capture is an eco-friendly that can reduce air pollutants, such as $SO_2$, NO and CO through a flue gas recirculation process. The newly developed $100kW_{th}$ pilot-scale Oxy-CFBC system used for this research has been continuously utilizing to investigate oxy-combustion characteristics for various fuels, coals and biomasses to verify the possibility of fuel diversification. The anthracite is known as a low reactivity fuel due to a lot of fixed carbon and ash. Therefore, this study aims not only to improve combustion efficiency of an anthracite, but also to capture carbon dioxide. As a result, compared to air-combustion of sub-bituminous coal, oxy-combustion of anthracite could improve 2% combustion efficiency and emissions of $SO_2$, CO and NO were reduced 15%, 60% and 99%, respectively. In addition, stable operating of Oxy-CFBC could capture above 94 vol.% $CO_2$.

• Journal of Energy Engineering
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• v.4 no.1
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• pp.42-51
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• 1995

준역청탄에서 무연탄까지의 등급을 갖는 8개탄을 대상으로 ASTM 방법으로 회분을 제조하였으며 회분조성과 용융온도를 측정하여 각 시료의 융착성향을 비교하였다. 보다 간단한 방법으로 정확하게 융착성향을 예측하기 위한 방법을 찾는 것을 목적으로 시료의 색을 측정하였으며 TGA를 이용하여 회분중 휘발량을 측정하였다. 또한 1$600^{\circ}C$에서 회분을 용융시키고 다시 응고시켜 제조한 연마시료를 대상으로 표면에 형성된 공동크기를 분석하였으며 회분의 색, 휘발량, 공동크기 등과 융착성향과의 관계를 고찰하였다. 분석결과 회분의 색은 회분의 융착성향을 크게 구분할 수 있는 지표로써 사용될 수 있으며 TGA에 의한 회분중 휘발량의 측정은 용융온도와, 그리고 용융후 응고시편의 공동크기는 1$600^{\circ}C$에서 계산된 점도와 밀접한 상관성을 갖고 있어 이들을 석탄회분의 융착성향 예측에 사용할 수 있음을 알 수 있다.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.109-114
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• 2001

In this study, the physical and dynamic characteristics of Bottom-ash produced at steam power plants were compared and considered. The comparative objects were Bottom-ash in which a lot of powder contained and that in which less than that relatively contained. The difference in quantity of powder showed different effect on the character of flow. This study was undertaken on the use of Bottom-ash as a fine aggregate, and showed the durability and the character of strength according to each rate.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1990.04a
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• pp.111-124
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• 1990

All most factories producing briquets in Seoul are currently located at residential districts. The coal dusts scattered from these factories are making serious problems in living. To get rid of this environmental pollution, moving thesis factories to places of mining coals is considered now. For doing this project, first, annual briquet demands are forecasted using regression analysis and then, optimal factory capacities to be built are obtained based on forecast demands using LP. To validate factory capacities obtained above simulation is conducted using SLAM II.

• Journal of Energy Engineering
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• v.8
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• pp.86-102
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• 1999

우리나라의 석탄산업은 해방후 40여년간 거의 불황을 모르고 오직 생산의 극대화에 전념하며 국가경제의 유지에 필수적인 에너지, 주로 민수용 에너지를 공급하는데 지대한 공헌을 하여왔다. 국내 석탄산업은 50년대 1인당 국민소득 100US$에도 미치지 못하였던 우리나라의 경제규모를 한때 10,000US$까지 100배의 신장을 이룩하는데 가장 중요한 역할을 담당하였으며, 또한 해방전 우리나라의 가정용 주 에너지원이었던 신탄을 무연탄으로 대체함에 따라 산림녹화에 의한 치산치수와 환경개선에 지대한 공헌을 하였다. (중략)

• Journal of Energy Engineering
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• v.1 no.1
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• pp.102-110
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• 1992

The determination of production level of the domestic anthracite coal is an important issue in the national energy strategy. It is also closely related to the energy mix scenarios in the future. The objective of the paper is to discuss and analyze the options of expanding anthracite coal demand in the utility sector. The observed options are including; (1) New pulverized system of the 200 and 500 MW level, (2) Atmospheric Fluidized Bed Combustion (AFBC), and (3) Pressurized Fluidized Bed Combustion (PFBC). Special emphasis is placed on the considerations in estimating the effects on the electric system costs and government subsidies when the options are introduced in the utility sector.