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MATRIX REALIZATION AND ITS APPLICATION OF THE LIE ALGEBRA OF TYPE F<sub>4</sub>
CHOI, SEUNGIL 호남수학회 2006 호남수학학술지 Vol.28 No.2
The Lie algebra of type $F_4$ has the 26 dimensional representation. Its matrix realization can be obtained via 26 by 26 matrices and has a direct useful application to degenerate principal series for p-adic groups of type $F_4$.
Choi, Seungil,Lim, Yooseng,Jang, Min Hyung,Park, Ji In,Hwang, Nam Kyung,Yi, Moonsuk American Scientific Publishers 2017 Journal of nanoscience and nanotechnology Vol.17 No.11
<P>We investigated the performance of zinc oxide (ZnO) nanowires in indium zinc oxide (IZO) thin-film transistors. These transistors were fabricated with ZnO nanowires channel layers, which were deposited by a solution process, whereas the IZO channel layers were deposited by a radio-frequency magnetron sputtering system. We varied the nanowire composition ratio from 0.05 to 0.2, keeping the IZO channel layers fixed to investigate the effects of the nanowires. At a nanowires composition ratio of 0.1 wt%, the saturation mobility of the IZO/ZnO nanowires thin-film transistors decreased to 28.8 cm(2)/V.s, the threshold voltage shifted to a more positive voltage than the pure IZO thin-film transistors, and the subthreshold swing increased to 0.79 V/dec. We used an X-ray photoelectron spectroscope, an atomic force microscope, and a field-emission scanning electron microscope to investigate the electrical performances, binding energy and surface roughness of the IZO/ZnO nanowire thin-film transistors.</P>
최승일(Seungil Choi) 한국산학기술학회 2014 한국산학기술학회 학술대회 Vol.- No.-
본 논문에서는 충남 제조업의 경쟁력 변화를 통계자료 분석을 통해 살펴보았다. 분석 방법으로는 입 지계수모형과 변이할당모형을 적용하였고, 이를 통해 2008년 이후의 충남 지역 제조업의 경쟁력 변화 를 살펴보고 지속적인 성장을 위한 전략 수립의 필요성을 제기하였다.
Dongmin Choi,Jung-Yong Lee,Seungil Choi,Taehwan Ahn,Younghoon Cho 전력전자학회 2023 JOURNAL OF POWER ELECTRONICS Vol.23 No.6
This paper proposes a high precision harmonic controller combined with repetitive and modulated model predictive controllers for standalone inverter applications. The proposed method is configured as a dual loop controller that includes an outer voltage controller with a plug-in repetitive controller (RC) and an inner current controller with a modulated model predictive controller (MMPC). The RC in the outer control loop effectively synthesizes the harmonic current reference when connecting a nonlinear load with a periodic harmonic current. Then, the MMPC-based current controller, with its ultra-wide bandwidth, regulates the harmonic current without additional harmonic current controllers. Thus, the abilities to precisely control the harmonic current and improve the output voltage quality are achieved. To combine the MMPC and the repetitive controller, an equivalent transfer function is derived from the ac sweep result of the MMPC. The stability of the RC is analyzed by applying the equivalent transfer function to the closed-loop voltage control model. To validate the performance of the proposed control method, a 3 kVA single phase 3-level T-type inverter prototype is built and tested. The harmonic compensation and dynamic performance of the proposed method are verified by simulation and experimental results.
최승일(Seungil Choi) 한국산학기술학회 2014 한국산학기술학회 학술대회 Vol.2014 No.2
본 논문에서는 기계생산성관리분야 국가직무능력표준을 개발하는 과정에서 능력단위와 능력단위요소를 도출하는 과정을 정리하였다. DACUM 방식을 적용하여 산업현장전문가, 교육훈련전문가, 자격전문가의 집단토의를 통해 직무분석을 수행하였다.
최승일(Seungil Choi) 한국경영과학회 2011 經營 科學 Vol.28 No.3
Basel Ⅱ advanced measurement approaches for operational risk need to estimate the frequency and severity distribution of operational losses. Due to lack of internal loss data, the estimation is impossible in many cases and so external loss data might be used by scaling on asset or gross income. To get around lack of loss data, scenario analysis combined with loss distribution approach can be useful in calculating the capital charge of operational risk. However, scenario based loss distribution approach requires much time and effort. Instead we may apply the analytic hierarchy process to measure operational risk of financial institutions. The analytic hierarchy process combined with loss distribution approach is to estimate the capital charge of operational risk in other areas based on the operational VaR in an area with sufficient loss data. AHP provides a tool for timely measurement of operational risk in this rapidly changing global environment.
Dongmin Choi,Jinwoo Kim,Jung-Yong Lee,Seungil Choi,Younghoon Cho 전력전자학회 2023 JOURNAL OF POWER ELECTRONICS Vol.23 No.7
This paper proposes a phase compensation in the synchronous frame for applying modulated model predictive control (MMPC) to a high-speed motor. In the conventional MMPC, when future values for the control variable are predicted, it is necessary to assume that the other variables have constant values during one sample period. However, under a high electrical frequency, this assumption provokes a prediction error, which affects the steady state response. Hence, to improve the precision for predicting variables, the phase variation in the synchronous frame is analyzed and compensation methods are proposed. In particular, the instantaneous variance for the back electromotive force during one sampling period is analyzed, and a compensation method for its variance is derived. To validate the effectiveness of the proposed compensation methods, a motor drive system that can be operated at 3000 rpm is built and tested. Simulation and experiments are performed while comparing the transient and steady state responses.
미니클러스터 정부 지원사업이 경영성과에 미치는 영향에 대한 실증 연구
최종태(Jongtae Choi),정해일(Haiil Jung),이경근(Kyunggeun Lee),최승일(Seungil Choi) 한국산학기술학회 2021 한국산학기술학회논문지 Vol.22 No.8
본 연구는 산업단지내 중소기업의 경쟁력을 강화하기 위한 미니클러스터(Mini-Cluster, 이하 MC) 사업의 지원효과를 분석하였다. 이를 위해 R&D와 비R&D를 동시에 지원받은 수혜기업과 비수혜기업간 경영성과 차이를 비교하는 방법으로 효과성을 분석하였다. 두 집단을 비교하기 위해 비교집단을 선택하는 데 있어 선택적 편의를 제거하기 위한 수단으로 성향점수매칭(Propensity Score Matching, PSM) 기법을 적용하였다. 매칭 결과 수혜기업과 비수혜기업 각각 46개 기업씩 1:1로 매칭이 이루어졌다. 매칭 결과를 t-test를 통해 매칭 전 · 후를 검증하였으며 매칭에 대한 타당성을 분산비를 통해 확인하였다. PSM 결과 매칭 전 서로 다른 집단이 매칭 후에는 동일한 성격의 기업들로 매칭이 되었으며 분산비도 개선된 것을 확인할 수 있었다. 매칭이 완료된 두 집단 간의 실질적인 경영성과 차이를 알아보기 위하여 이중차분법(Difference in Differences, DID) 기법을 이용하였다. DID 분석 결과 MC 지원 수혜기업이 비수혜기업에 비하여 매출, 영업이익, 성장률 등 모든 성과 변수에서 양(+)의 순효과가 있음을 알 수 있었다. 본 연구를 통하여 산업단지내 중소기업의 경쟁력 강화를 위해 R&D와 비R&D 사업을 함께 지원할 필요성을 확인할 수 있었다. This study analyzed the effect of the Mini-cluster (MC) project in strengthening the competitiveness of small and medium enterprises (SMEs) in industrial complexes. To this end, effectiveness was analyzed by comparing the business performance of beneficiary companies that received research and development (R&D) and non-R&D support with that of non-beneficiary companies. In selecting the control group, the propensity score matching (PSM) technique was applied to remove selection bias. Each beneficiary and non-beneficiary company was matched 1:1 in a total of 46 companies. The matching result was verified through a t-test, and the validity of matching was verified through the variance ratio. As a result of the PSM analysis, it was confirmed that two different groups before matching were matched with the companies that have the same characteristics after matching , and the variance ratio also improved. In addition, the difference in differences (DID) method was used to find out the difference in actual business performance between the two groups that were matched. As a result of the DID analysis, it was found that the companies that were beneficiaries of the MC project had seen a positive net effect in all performance variables such as sales, operating profit, and growth rate compared to non-beneficiary ones. Through this study, it was possible to confirm the necessity of supporting both R&D and non-R&D projects to strengthen the competitiveness of SMEs in industrial complexes.