• Journal of Intelligence and Information Systems
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• v.29 no.4
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• pp.229-256
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• 2023

The increase in telecommuting and household electricity demand due to the pandemic has led to significant changes in electricity demand patterns. This has led to difficulties in identifying KEPCO's PPA (power purchase agreements) and residential solar power generation and has added to the challenges of electricity demand forecasting and grid operation for power exchanges. Unlike other energy resources, electricity is difficult to store, so it is essential to maintain a balance between energy production and consumption. A shortage or overproduction of electricity can cause significant instability in the energy system, so it is necessary to manage the supply and demand of electricity effectively. Especially in the Fourth Industrial Revolution, the importance of data has increased, and problems such as large-scale fires and power outages can have a severe impact. Therefore, in the field of electricity, it is crucial to accurately predict the amount of power generation, such as renewable energy, along with the exact demand for electricity, for proper power generation management, which helps to reduce unnecessary power production and efficiently utilize energy resources. In this study, we reviewed the renewable energy generation forecasting system, its objectives, and practical applications to construct optimal aggregated power resources using data from 169 power plants provided by the Ministry of Trade, Industry, and Energy, developed an aggregation algorithm considering the settlement of the forecasting system, and applied it to the analytical logic to synthesize and interpret the results. This study developed an optimal aggregation algorithm and derived an aggregation configuration (Result_Number 546) that reached 80.66% of the maximum settlement amount and identified plants that increase the settlement amount (B1783, B1729, N6002, S5044, B1782, N6006) and plants that decrease the settlement amount (S5034, S5023, S5031) when aggregating plants. This study is significant as the first study to develop an optimal aggregation algorithm using aggregated power resources as a research unit, and we expect that the results of this study can be used to improve the stability of the power system and efficiently utilize energy resources.

• Journal of the Korean Data and Information Science Society
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• v.27 no.2
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• pp.275-284
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• 2016

Accurate electricity demand forecasts is essential in reducing energy spend and preventing imbalance of the power supply. In forcasting electricity demand, we considered double seasonal Holt-Winters model and TBATS model with sliding window. We selected a specific time zone as the reference line of daily electric demand because it is least likely to be influenced by external factors. The forecasting performance have been evaluated in terms of RMSE and MAPE criteria. We used the observations ranging January 4, 2009 to December 31 for testing data. For validation data, the records has been used between January 1, 2012 and December 29, 2012.

• Korea Petroleum Association Journal
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• no.5 s.254
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• pp.30-35
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• 2006

정유사들이 오는 7월부터 2년 동안 바이오디젤을 자발적으로 구매해 경유에 혼합 공급한다. 바이오디젤이란 콩이나 유채, 팜 등에서 추출한 식물성 유지나 폐식용유 등을 원료로 생산한 경우 대체연료로 정부가 지난 2002년부터 시범보급사업이 진행중이다. 그간의 시범보급사업에서 정부는 바이오디젤을 경유에 2:8로 혼합한 BD20 형태를 유지했지만 올해부터는 사정이 달라졌다. 주유소에서 판매가 허용되던 BD20 형태를 유지했지만 올해부터는 사정이 달라졌다. 주유소에서 판매가 허용되던 BD20은 7월 이후 자가 정비시설 등을 갖춘 연료 자가소비처로 유통을 한정하고 그 대신 모든 경유에 5% 이하의 바이오디젤을 혼합, 공급하는 'BD5' 방식을 선택했다. 하지만 'BD5'가 의무적인 것은 아니다. 현재 경유의 법정 품질기준에는 바이오디젤을 지칭하는 '지방산메틸에스테르 함량이 5% 이하까지 혼합할 수 있도록 하는 'BD5'기준이 설정되어 있지만 최저 혼합비율을 설정하지 않아 정유사 마음먹기에 따라서 전혀 혼합하지 않아도 된다. 혼합 가능한 상한선만 정해 있을 뿐 하한선은 없기 때문이다. 이와 관련해 정부는 2008년 월 이후부터 법으로 최저 혼합비율을 명시해 정유사들이 의무적으로 바이오디젤을 섞어 판매할 수 있도록 하겠다는 복안이다. 이에 앞서 정유사들은 지난 3월 산업자원부와 협약을 맺고 올해 7월부터 2008년 6월까지 2년동안 바이오디젤을 자발적으로 구매해 경유에 혼합 공급하겠다고 선언했다. 구매 물량은 연간 9만톤 수준으로 정부가 의도중인 2008년 7월 이후의 본 보급에 앞선 사실상의 마지막 실험 무대가 될 수 있다는 측면에서 중요한 의미를 갖게 된다. 바이오디젤이 대중적으로 보급되기 위해서 필수적으로 갖춰야 하는 원료의 안정적인 수급이나 품질의 안정성, 가격경쟁력 등이 향후 2년간의 과정에서 충분히 검증돼야만 본 보급에 착수할 수 있기 때문이다. 이처럼 중요한 시점에서 바이오디젤시장이 안고 있는 문제점을 점검해 보고자 한다.

• Resources Recycling
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• v.29 no.3
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• pp.24-35
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• 2020

Management of resource productivity is important for the reduction of natural resources and energy consumption. This is closely linked to circular economy which has recently been stressed worldwidely. Resource productivity is a key indicator which is to be managed in various industry sectors. Especially Korea which is heavily dependent on the natural resources import from overseas needs to give attention to this point. Nevertheless resource productivity related domestic researches and policies are extremely rare. This paper thus presents trends on resources productivities and their management policies of European countries and OECD G7 countries compared to the situation of Korea. In addition, the decoupling phenomenon of DMC (domestic material consumption) and GDP of Europe is analyzed and the resource productivity promotion strategy of Korea is proposed.

• Clean Technology
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• v.7 no.1
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• pp.43-49
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• 2001

To meet $CO_2$ emission regulation, this study describes the present state of $CO_2$ reduction technology and the effect of the regulation on power industry. In Japan, R&D investment is actively continuing through a long-term R&D project, along with trying to meet the reduction demand by the ways of energy saving and abroad business. EU has made a lot of investments in increasing the efficiency of power generation and developing alternative energy sources. The US is making provision of the portion of reduction by using energy saving program and emission trading, and the current DOE-driven program is addressing the development of cost-effective power systems. In the country, the research to reduce $CO_2$ emission has been mainly driven by the government and research institute supported by the government. Meanwhile, if the reduction obligation imposed on Portugal which is the least strict condition will be enforced in Korea, it is likely that about 50 running power plants should be stopped or shut down after 2015, in spite of voluntary reduction efforts such as conversion to clean fuels, etc. according to the government's long-term electric power need and supply plan.

• Journal of Energy Engineering
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• v.21 no.2
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• pp.158-167
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• 2012

The purpose of this paper is to examine the factors that encouraged the industrial growth of Koran city gas industry during 1995-2009, by carrying out input-output structural decomposition analysis(IO-SDA) using Syrquin's model. The results show that the main factors which contributed to the growth of the Korean city gas industry are final domestic demand(48.4%) and technological change(38.6%). By examining the results for the three periods of 1995-2000, 2000-2005, and 2005-2009, the tendency of changes between the two main factors is drawn. In contrast to the drastic decreasing tendency of the final domestic demand's contribution to the growth, 84.5%, 18.9%, and 15.4%, respectively for each period, there is an increasing tendency for technological change as seen by the results of 7.4%, 70.0%, and 42.2%, respectively. These findings may be a result from the fact that the rate of gas supply in the residential sector has been saturated recently. They are also reflective of the energy consumption trend of industrial activities as there has been a shift in the approach for supplying energy, from the traditional approach which use fossil fuels to the newer approach which uses environmentally friendly energy sources. For the continued growth of the city gas industry, policymakers sould consider greater investment in the expansion of city gas supply infrastructure for industrial activities rather than for the residential sector.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.52.1-52.1
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• 2011

최근에 에너지 자원의 고갈이 다가오는 상황에서 태양전지 분야가 주목받고 있으며 이에 대한 시장이 급격하게 확대되고 있다. 그러나 현재의 태양전지는 주를 이루고있는 실리콘태양전지의 경우 원재료 수급이 불안정하여 가격 변동이 심하다. 따라서 이를 대체할 2세대 태양전지인 박막형 태양전지의 연구가 활발히 이루어지고 있다. 박막형 태양전지 중에서도 주목받고 있는 것은 Cu(In,Ga)$Se_2$(CIGS)박막 태양전지이다. CIGS는 Ga의 농도에 따라 1.02~1.68eV의 다양한 에너지 밴드갭을 갖는 직접천이형 반도체 물질이다. 또한 $1{\times}10^5cm^{-1}$의 높은 광흡수계수를 가지고 있으며, $450{\sim}590^{\circ}C$의 고온공정에서도 매우 안정하여 열화현상이 거의 보이지 않아 박막형 광흡수층 재료로서 적합하다. 흡수층을 제조하는 방법은 여러 가지가 있지만, 본 연구에서는 균일성이 뛰어나고 원료사용효율이 높은 sputtering 방법을 사용하였다. 그리고 결정화하기위해서 유독기체를 사용하는 셀.렌.화. (selenization) 방법 대신 전자빔을 조사하는 방법을 채택하였다. sputtering을 통한 CIGS precursor을 제조하기위해 2~3개의 화합물target을 사용하는데, 대표적인 방법으로 동시에 sputtering하는 co-sputtering 방법과 각각의 단일 층을 쌓아 제조하는 stack형으로 분류된다. 본 연구는 CIGS precursor를 제조하기 앞서 CuGa 단일 층만을 제조하여 공정조건에 따른 박막을 제조하였다. 제조된 CuGa 단일층은 전자빔 처리에 따른 영향을 알아보기 위해 전자빔의 세기와 공정시간을 달리하여 특성을 알아보았다. 실험에서는 Cu:75wt%,Ga:25wt% 조성의 target을 사용하여 공정 압력을 각각 10~1mTorr로 변화시키며 실험을 실시하였으며 공정 power는 50W, 70W, 100W로 변화 시키며 실험을 실시하였다. 이때 실험의 초기진공은 turbo-molecular pump를 이용하여 $1{\times}10^{-6}torr$ 이하로 하였으며, Target과 기판사이의 거리는 모두 같은 조건으로 고정하여 실험을 실시하였다. 박막의 균일성을 증가시키기 위하여 5 rpm의 속도로 기판을 회전하였으며 기판 온도는 가열하지 않고 상온에서 전구체를 증착하였다. 그 후 전자빔의 세기를 고정 시킨 후 전자빔 조사 시간을 조절하여 전자빔 조사 전후의 특성을 각각 분석하였다. 전기적특성은 Hall effect, 4-point probe, 구조적 특성은 SEM,EDS, XRD, XRF 를 이용하여 분석하였다.

• Journal of Energy Engineering
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• v.28 no.3
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• pp.42-54
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• 2019

The solar and wind power is spreading as a means to $CO_2$ reduction, but it has the characteristics of the volatility depending on the weather changes. This article aims to estimate the additional integration costs in Korea electric system in response to such volatility of increasing solar and wind power generation, using Korea electric power trading analyzer(KEPTA). The analysis utilizes the statistics of "8th Basic Plan for Long-term Electricity Supply and Demand" and "Renewable Energy Plan 3020". As the results, integration costs will be estimated 13.94Won/kWh~32.55Won/kWh, consisting of 8.94Won/kWh as back-up costs, 1.03Won/kWh~4.45Won/kWh as balancing costs, and 3.97Won/kWh~19.16Won/kWh as grid-costs. These results suggest that when the integration costs are secured, Korea electric system will be expected in the stable situation. This article leaves the further studies with taking the technological development of solar and wind power generation, the introduction of energy storage system, and wholesale price of electricity into consideration.

• Journal of Korean Society of Forest Science
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• v.83 no.2
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• pp.133-147
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• 1994

Wastepaper recycling has significant implications not only in providing scarce raw material input for the paper industry but in environmental concerns such as reducing solid waste disposal, energy conservation and preservation of forest resources. The objectives of this study was (1) to develop an econometric model of demand for and supply of wastepaper, (2) to forecast wastepaper consumption and price to the year 2000 applying the econometric models estimated and (3) to estimate the elasticity of variables which are included in the wastepaper supply and demand equations. In this study wastepaper was classified into three groups, old newsprint, old corrugated and mixed For each group such as demand and supply equation were estimated. The demand equations were estimated as a function of paper and paper product consumption and wholesale price index and supply equations as a function of wastepaper price, one year lagged paper and paperproduct consumption and transportation price. Applying the econometric models to forcasting results in the future consumption and supply of wastepaper projected as 11.645 million MT and 7.396 million MT in 2000, respectively. The rate of wastepaper self-supply is forcasted about 63.5% in 2000. Especially, the rate of old neswprint self-supply is predicted about 16% which means about 2.2 million MT of old newsprint should be imported from foreign countries. Lastly, some policy measures to promote wastepaper recycling rate based upon economic and physical characteristics of wastepaper and market structure are suggested.

• The Korean Journal of Petroleum Geology
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• v.14 no.1
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• pp.45-52
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• 2008

The GTL(Gas to Liquids) technology, manufacturing synthesized oil from natural gas, had been developed about 1920 for the military purpose by Fischer and Tropsch, German scientists. And 1960, Sasol company had started commercializing the FT(Fischer-Tropsch) synthesis technology, for the transport fuel in South Africa. Until a recent date, the commercialization of GTL technology had been delayed by low oil price. But concern about depletion of petroleum resources, and development in synthesizing technology lead to spotlight on the GTL businesses. Especially, Qatar, which has rich natural gas fields, aims at utilizing natural gas like conventional oil resources. Therefore, around this nation, GTL plants construction has been promoted. There are mainly 3 processes to make GTL products(Diesel, Naphtha, lube oil, etc) from natural gas. The first is synthesis gas generation unit reforming hydrogen and carbomonoxide from natural gas. The second is FT synthesis unit converting synthesized gas to polymeric chain-hydrocarbon. The third is product upgrading unit making oil products from the FT synthesized oil. There are quite a little sulfur, nitrogen, and aromatic compounds in GTL products. GTL product has environmental premium in discharging less harmful particles than refinery oil products from crude to the human body. In short, the GTL is a clean technology, easier transportation mean, and has higher stability comparing to LNG works.