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한국(韓國)의 교육수급결정(敎育需給決定) 및 투자수익율(投資收益率) 분석(分析)
성태현 ( Tae Hyun Sung ) 경남대학교 산업경영연구소 1984 지역산업연구 Vol.7 No.1
The objectives of this study are to revise the classial demand supply theory of education, and analyses the trends of internal rate of return (IROR) in Korea from 1967 to 1980. It hoped that this study will not only give clearer picture of supply-demand function of education but provide a better basis for forcasting optimum investment level in education industry in Korea. It is theorized that demand for a consumption goods is a function of its cost, available financial resources and expected returns. Education is viewed as a good with both consumption and investment characteristics. In an attempt to find the demand for education in Korea, it uses the explanatory variables of disposable income, educational cost and number of per household. The real cost of education is the measure of the relative price of education as consumption good and the cost of inputs from the viewpoint of investment demand. Real disposable income and the number of persons per household reflect the availability of financial resources. In the classical theory, the decision criterion of private demand for education is; remain at school if private rate of return on the next increment of education exceeds the yields of the best alternative investment option, and not otherwise. The model is; D=f(r/i) But that model exclude the psychological, social factors of education. We must be consider the downward rigidity of demand for education and intergeneration ratchet effect tends constantly to shift the one to the right as succeeding generations achieve ever higher terminal education age. The revised model is; D* =f(r/i, w) D≤D*. The trends of social rate of return (SROR) show that additional SROR increase for high graduates who finish college. Our study indicates that in the future course of educational development in Korea the education system as whole will continue to expand with the increase of national income, decrease of the average family size. There are numerous difficulties in applying the rate of return approach to developing nations. In particular earnings differentials do not reflect true marginal social products due to labor market imperfection. And that approach does not consider the externalities, psychic returns and spill-overs of education.
부하연결에 따른 외팔보 압전에너지 하베스터의 공진주파수 변화 해석
황성주(Sung Joo Hwang),안정환(Jung Hwan Ahn),김선중(Sun Jung Kim),김정훈(Jeong Hun Kim),송예원(Yewon Song),성태현(Tae Hyun Sung) 한국소음진동공학회 2015 한국소음진동공학회 학술대회논문집 Vol.2015 No.4
Piezoelectric cantilever beam is used in conversion of mechanical energy to electrical energy, and vice versa. But, when an external load connected to piezoelectric material, mechanical characteristic of cantilever beam is changed. We study resonance frequency shift of the piezoelectric cantilever beam according to load connection. When the external circuit changed from open to short, resonance frequency of the piezoelectric cantilever beam is changed from 40 Hz to 39 Hz. Also, displacement of the free end of the piezoelectric cantilever beam increased 2.4%. After then, we optimize resistive impedance matching for maximum power transfer. In matching case, resonance frequency is located between open and short circuit connection. Free end displacement also 21.4% decreased. This result shows that electrical load connection results in changing of mechanical characteristic like stiffness, resonance frequency, displacement.
남긍현(Gueng-Hyun Nam),최효상(Hyo-Sang Choi),성태현(Tae-Hyun Sung),한영희(Young-Hee Han),이정필(Jeong-Pill Lee),한상철(Sang-Chul Han) 대한전기학회 2006 대한전기학회 학술대회 논문집 Vol.2006 No.7
The energy storage systems are being widely researched for the electric power. The operations running in a vacuum chamber mainly consists of a composite flywheel rotor, superconductor bearings, a motor/generator and its controller. Among composed the apparatus, the floating magnet bearing consists of the ring-type permanent magnets with epoxy resin impregnation for reinforcement and surface protection. In order to storage as much energy as possible, the flywheel is supposed to be rotated with very high speed. The magnetic field is analyzed by using the Maxwell 2D/3D for the simulations.
한상철,정년호,한영희,성태현,Han, Sang-Chul,Jeong, Neyon-Ho,Han, Young-Hee,Sung, Tae-Hyun 한국전기전자재료학회 2007 전기전자재료학회논문지 Vol.20 No.6
Large and single-grain Y-Ba-Cu-O(YBCO) bulk superconductors have been fabricated by using a seeded infiltration and growth method. $Y_2BaCuO_5$(Y211) precursor pellets and $YBa_2Cu_3O_x$(Y123) liquid source pellets were prepared using commercial powder and were processed by infiltration and growth method to achieve low pore and high trapped field property. The superconductor properties of the single crystal are measured and analyzed in relation with the density and size of the Y211 particle in the Y123 matrix. An optimum processing condition is suggested based on the analyzed results.
태양광 에너지저장장치(ESS) 경제성 분석 및 최적 용량 평가
이영훈 ( Young-hun Lee ),성태현 ( Tae-hyun Sung ) 한국산업융합학회 2022 한국산업융합학회 논문집 Vol.25 No.2
The purpose of this study is to analyze an economic assessment of PV-ESS systems based on the power generation performance data of solar power (PV) operating in domestic area, and to calculate the optimal capacity of the energy storage system. In this study, PVs in Gyeonggi-do, Jeollabuk-do, and Gyeongsangbuk-do were targeted, and PVs in this area were assumed to be installed on a general site, and the research was conducted by applying weights based on the facility's capacity. All the analysis was conducted using the actual amount of KPX transactions of PVs in 2019. In order to calculate the optimal capacity of PCS and BESS according to GHI, PV with a minimum/maximum/central value was selected by comparing the solar radiation before the horizontal plane between three years (2017-2019) of the location where PV was installed. As a result of the analysis, in Gyeonggi-do, if the REC weight decreases to 3.4 when there is no change in the cost of installing BESS and PCS, it is more economical to link BESS than PV alone operation of PV. In Jeollabuk-do, it was analyzed that if the REC weight was reduced to 3.6, it was more likely to link BESS than PV operated alone. In Gyeongsangbuk-do, it was analyzed that if the REC weight was reduced to 3.4, it was more likely to link BESS than PV operated alone.