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곽규형,박홍용 明知大學校 産業技術硏究所 2003 産業技術硏究所論文集 Vol.22 No.-
Abstract - This experimental study were carried out in order to investigate the shear strength of steel fiber reinforced concrete. 96 specimen were tested for shear strength and 32 specimen for flexural. Test parameters were the volume fraction of steel fiber and aspect ratio. Test results show that shear strength are increase as fiber content and aspect ratio increase. The procedure proposed in this study is the simple method for calculating the shear strength in terms of steel fiber- volume fraction and concrete compressive strength. To verify the proposed equations the experimental result were compared with those from other researches such as equations of ACI code 318-95, Narayanan, Iman, Sharma, and Ashour. For the proposed equation, the mean value of the radio of the measured to calculated shear strength was 93%.
곽규형,김태현,신한솔,김수영,김욱 대한전기학회 2020 전기학회논문지 Vol.69 No.8
The Korean government currently implements Renewable Portfolio Standard(RPS) and the price of the Renewable Energy Certificate(REC) affects the profits and costs of various market players. But uncertainty over the price trend of the REC, such as the recent plunge in REC prices in the spot market and the announcement of an increase in RPS target, is increasing. However, research on the methodology of estimating the price of the REC has not been actively conducted compared to its importance. Therefore, the research on estimating marginal costs for REC is significant in that it can not only give market players the appropriate price signal but also act on various decisions based on the marginal costs derived. In this study, a mathematical model in the form of bi-level programming is established to reflect Korea’s RPS system mechanisms and to take into account changes in power market prices as large-scale renewable energy generation facilities are deployed, and then marginal costs of REC are derived using a mathematical model. It could be used for design and analysis of the REC market, such as the supply and demand situation of the market, the optimal renewable energy sources portfolio, and the impact of the RPS system mechanism
신재생에너지 공급인증서(REC)의 한계비용 추정에 관한 연구
곽규형(Kyu-Hyeong Kwag),김태현(Tae-Hyun Kim),신한솔(Han-Sol Shin),김수영(David Kim),김욱(Wook Kim) 대한전기학회 2020 전기학회논문지 Vol.69 No.8
The Korean government currently implements Renewable Portfolio Standard(RPS) and the price of the Renewable Energy Certificate(REC) affects the profits and costs of various market players. But uncertainty over the price trend of the REC, such as the recent plunge in REC prices in the spot market and the announcement of an increase in RPS target, is increasing. However, research on the methodology of estimating the price of the REC has not been actively conducted compared to its importance. Therefore, the research on estimating marginal costs for REC is significant in that it can not only give market players the appropriate price signal but also act on various decisions based on the marginal costs derived. In this study, a mathematical model in the form of bi-level programming is established to reflect Korea’s RPS system mechanisms and to take into account changes in power market prices as large-scale renewable energy generation facilities are deployed, and then marginal costs of REC are derived using a mathematical model. It could be used for design and analysis of the REC market, such as the supply and demand situation of the market, the optimal renewable energy sources portfolio, and the impact of the RPS system mechanism.
실계통기반 제약조건 반영에 따른 계통한계가격과 시장참여자 편익 분석연구
장재훈,신한솔,곽규형,오효빈,윤형석,김 욱 대한전기학회 2024 전기학회논문지 Vol.73 No.1
The Korean electricity market previously determined the system marginal price (SMP) without considering actual operational constraints under the Cost Based Pool electricity market system. Recently, in order to improve system operational problems, the pricing methodology was revised to reflect constraints, with the goal of introducing the actual system-based day-ahead market. However, there are no studies comparing the methodologies before and after this change. This study used a mathematical model to simulate pricing methodologies both before and after the revision, deriving SMP, social welfare, and congestion surplus. This study evaluated the impact of the methodology change on the electricity market and underscored the need for further congestion cost studies. An analysis of this revision can serve as a reference for market and system operators to refine the domestic power market's pricing approach. It also assists market participants in managing financial risks and establishing countermeasures due to the methodology change.
Binding constraints를 고려한 딥러닝 기반 최적조류계산 모델 및 대형계통 적용 사례 연구
윤상민,신한솔,곽규형,오효빈,윤형석,김욱 대한전기학회 2023 전기학회논문지 Vol.72 No.4
Recently, research using machine learning and deep learning is being conducted to quickly solve the AC optimal power flow (AC OPF) problem. The problem with the existing research is that, unlike the actual system, it did not consider the generator start-up status according to demand change by using a test system in which the minimum power generation of the generator is zero. This paper proposes a deep learning-based AC OPF model and post-processing for a simulated large-scale system in Korea. It is a difficult problem to predict in Korea's large-scale simulation system as the generator start-up status changes as the demand changes. Accordingly, the accuracy of the deep neural network model, which is a deep learning algorithm, was increased by inserting the binding constraints and generator start-up status as variables. In addition, we want to satisfy the constraints of AC OPF with post-processing including the merit order stack model and AC power flow.
김병오(Byungoh Kim),곽규형(Kyuhyeong Kwag),김태현(Tae Hyun Kim),신한솔(Hansol Shin),김욱(Wook Kim) 대한전기학회 2021 전기학회논문지 Vol.70 No.3
The Korean government is supplying many renewable energy facilities through policies to expand renewable energy such as the RPS(Renewable Portfolio Standard), and the need to supply ESS(Energy Storage System) is being emphasized in order to maintain stable power systems and secure power quality. However, uncertainties in terms of profits for ESS businesses, such as abolition of ESS incentive policy, are growing. At this point, renewable energy provider that reflects the business profit mechanism under the ESS incentive policy and a mathematical model in the form of a bi-level programming problem, consisting of "renewable energy busines profit’ and ‘economic dispatch problem’ in which large-capacity renewable energy and ESS can be reflected in resource scheduling and commitment to take into account changes in the electricity market price. In addition, based on the mathematical model, a simulation was performed for the Jeju island to calculate the optimal ESS capacity for each year, and a sensitivity analysis was performed according to the change in ESS REC incentive weight and the decrease in ESS installation cost.