The research of the floating

Tomoyuki Horikomi,Kuniaki Shoji,Kiyokazu Minami 한국항해항만학회 2006 한국항해항만학회 학술대회논문집 Vol.2006 No.-

A floating-type wave power pump is a device which sends air into water by using wave power. The floating-type wave power pump has the new configuration composed of a curved surface reflection board, a slope, and phase plates. As a result of a water-tank experiment, it turned out that the floating-type wave power pump with a curved surface reflection board and a slope raised power and efficiency in the wide wavelength waves. The result of a marine experiment was also preferable. The floating-type wave power pump sends air into the sea by using wave power, so it can be used for the improvement of marine environment. In addition, the floating body constituted of a curved surface reflection board, a slope, and phase plates, is effective as a device to utilize the energy of a wave. Therefore, it can be widely used for a wave power generation, pumping up deep seawater.

Power Performance Test of the Long-Distance Wind Turbine using Nacelle Anemometer

Kim, Hyeon-Wu(김현우),Ko, Kyung-Nam(고경남),Huh, Jong-Chul(허종철) 한국태양에너지학회 2013 한국태양에너지학회 학술대회논문집 Vol.2013 No.4

Power performance test of the long-distance wind turbine from met-mast was carried out according to the IEC 61400-12-2 FDIS. The wind speed for this study was measured at HanKyoung wind farm in Jeju. A Nacelle Transfer Function, NTF, was modeled using the correlation between wind speed of the met-mast and the neighboring nacelle anemometer. The NTF was verified by the comparison of AEP. The nacelle power curve, NPC, was derived from the nacelle wind speed corrected by the NTF. The NPC of long-distance wind turbine and the power curve offered by the manufacturer were compared to verify whether the power curves were well matched. Overall power performance of long-distance wind turbine under test was a good agreement with manufacturer"s power curve. The IEC 61400-12-2 FDIS could be applied to carry out the power performance test of long-distance wind turbine.

Wingate 무산소성 파워평가 시 Cadence를 이용한 파워커브 평가방법 제안

정승호 ( Seung Ho Jung ),김종규 ( Jong Kyu Kim ),천윤석 ( Yoon Seouk Chun ),조현철 ( Hyun Chul Cho ) 한국스포츠정책과학원(구 한국스포츠개발원) 2010 체육과학연구 Vol.21 No.4

단위시간당 최대 일을 수행하는데 있어 발생되는 피로를 객관적으로 평가하기 위해 개발된 Wingate Anaerobic Test(WAnT)는 1970년대부터 현재까지 일반인의 건강 체력 평가 및 엘리트 운동선수의 경기력 평가를 위해 보편적으로 이용되어 왔으나, WAnT에서의 피로개념을 보다 객관화할 수 있는 새로운 방법의 필요성이 제기되어 왔다. 이러한 필요성을 위해서, 이 연구는 WAnT 시 산출되는 피로지수 또는 피로율을 X-Y 2차 평면상에서 분당 페달링 횟수를 X축, 파워를 Y축으로 설정할 때 나타나는 곡선(Cadence-Power curve, CPC)상 특성들을 분석하여 WAnT에서의 피로개념을 보다 객관화할 방법을 제시하는데 목적을 두고 국민체육진흥공단 경륜운영본부에 등록되어 있는 단거리 선수 24명을 대상으로, 인체계측, Wingate 무산소성 파워검사 및 200m 경기기록을 측정하여 분석하였다. 이 연구의 결과, CPC에 나타나는 P, Q, R, S 지점들의 X(cadence)값들 중, P, Q, R 지점의 값들은 200m 기록, 절대치 피크파워, 상대치 피크파워, 절대치 평균파워, 상대치 평균파워, 피로지수 등과 유의한 상관관계(p<0.05)를 보여주었다. 각 지점들의 Y(power)값들 중 P, Q, R 지점의 값들은 대퇴상위 둘레, 200m 기록, 체중, 피크파워 절대치, 피크파워 상대치, 피로지수, 운동직후 혈중젖산농도 등과 유의한 상관계수(p<0.05)를 보여주었다. 더 나아가, 각 지점별 차이 값들과 각 지점간의 기울기 값들도 유의한 상관관계를 보였다. 결론적으로, 기존의 피로지수 측정방법보다 이 연구에서 사용한 CPC를 이용하는 방법이 보다 전문 운동선수들의 무산소성 운동능력 평가 시 피로능력을 보다 객관적으로 평가할 수 있는 도구로서의 활용가치가 있다고 생각된다. Wingate Anaerobic Test (WAnT) has been used, since 1970`s, as fatigue index to evaluate adolescents` and adults` physical strength and elite athletes` performance and anaerobic capacity. However, the necessity of objectifying its fatigue concept has arisen. Therefore, the purpose of this study was to develop new method for interpreting WAnT results by cadence-power curve. Twenty-four registered short-track cyclists participated in this study and were performed anthropometric measurements, wingate anaerobic tests and 200m sprint cycling. The results showed that cadence values of P, Q and R spots on the cadence-power curve (CPC) were significantly correlated with 200m, peak powers, mean powers and fatigue index (p<0.05) and that power values of P, Q and R on the CPC were significantly correlated with thigh girth, 200m, body weight, peak powers, fatigue index and lactic acid level immediately after the test (p<0.05). Furthermore, deferences and slopes between 2 distinct points among P, Q, R, and S on the CPC were significantly correlated with some variables (p<0.05). Therefore, we suggest that, based on our findings, the method for interpreting WAnT results by the cadence-power curve may provide more meaningful and objective values to evaluate elite athletes` performance and anaerobic capacity.

Improved Global Maximum Power Point Tracking Method Based on Voltage Interval for PV Array under Partially Shaded Conditions

Ding, Kun,Wang, Xiang,Zhai, Quan-Xin,Xu, Jun-Wei,Zhang, Jing-Wei,Liu, Hai-Hao The Korean Institute of Power Electronics 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.4

The power-voltage (P-V) curve of photovoltaic (PV) arrays connected in parallel to bypass diodes would have several local maximum power points (LMPP) under partial shading conditions (PSC). Conventional maximum power point tracking (MPPT) methods fail to search for the global maximum power point (MPP) because the searched peak point may remain at the LMPP on the P-V curve under PSC. This study proposes an improved MPPT algorithm to ensure that PV arrays operate at global maximum power point (GMPP) under PSC. The proposed algorithm is based on a critical study and a series of observations of PV characteristics under PSC. Results show the regularity of voltage interval between LMPPs. The algorithm has the advantages of rapidly reaching GMPP, maintaining stability, and recovering GMPP quickly when the operating condition changes. Simulation and experimental results demonstrate the feasibility of the proposed algorithm.

Random Point Blinding Methods for Koblitz Curve Cryptosystem

백유진 한국전자통신연구원 2010 ETRI Journal Vol.32 No.3

While the elliptic curve cryptosystem (ECC) is getting more popular in securing numerous systems, implementations without consideration for side-channel attacks are susceptible to critical information leakage. This paper proposes new power attack countermeasures for ECC over Koblitz curves. Based on some special properties of Koblitz curves, the proposed methods randomize the involved elliptic curve points in a highly regular manner so the resulting scalar multiplication algorithms can defeat the simple power analysis attack and the differential power analysis attack simultaneously. Compared with the previous countermeasures, the new methods are also noticeable in terms of computational cost.

Wind Turbine Power Performance Testing using Nacelle Transfer Function

Kim, Hyeon-Wu(김현우),Ko, Kyung-Nam(고경남),Huh, Jong-Chul(허종철) 한국태양에너지학회 2013 한국태양에너지학회 논문집 Vol.33 No.4

A study on power performance testing of a wind turbine which has no met-mast at a distance of 2~4 rotor diameter was carried out using the Nacelle Transfer Function, NTF, according to IEC 61400-12-2. The wind data for this study was measured at HanKyoung wind farm of Jeju Island. The NTF was modeled using the correlation between wind speeds from the met-mast and from the wind turbine nacelle within 2~4 rotor diameter from the met-mast. The NTF was verified by the comparison of estimated Annual Energy Productions, AEPs, and binned power curves. The Nacelle Power Curve, NPC, was derived from the nacelle wind speed data corrected by NTF. The NPC of wind turbine under test and the power curve offered by the turbine manufacturer were compared to check whether the wind turbine is properly generating electricity. Overall the NPC was in good agreement with the manufacturer"s power curve. The result showed power performance testing for a wind turbine which has no met-mast at a distance of 2~4 rotor diameter was successfully carried out incompliance with IEC 61400-12-2.

A Novel Curved-Coil Transmitter for Quasiomnidirectional Wireless Power Transfer

Guo Bochao,Zhao Yubo,Chen Wei,Guo Ni,Tian Zijian 한국전자파학회 2023 Journal of Electromagnetic Engineering and Science Vol.23 No.2

Achieving stable power transfer by merely relying on quasi-omnidirectional couplers is challenging. In this paper, we propose a quasi-omnidirectional wireless power transfer (QWPT) system with a novel curved-coil transmitter to achieve steady transmission performance. A single power source is used to drive the transmitter's current without using a phase and current control methodology. Power is transmitted to the receiver through magnetic resonant coupling at a distance of 50 mm. Moreover, an equivalent circuit model of the curved-coil system is derived and mathematically analyzed. The mutual inductance of the proposed QWPT system is evaluated through analysis and experiments. The experimental results for the resonant coupling system confirm the theoretical analysis of the performance of the curved-coil transmitter and quasi-omnidirectional power transfer.

우리나라의 실물경제활동에 대한 수익률 곡선의 예측력 분석

박형달 한국무역보험학회 2022 무역금융보험연구 Vol.23 No.4

Purpose : This paper investigates whether the yield curve factors can predict the Industrial Production Index’s growth rate. Research design, data, methodology : This paper uses the linear regression for the yield curve’s predictability of the annualized cumulative percentage change and the annualized marginal percentage change in Industrial Production Index. Results : The result suggests that the slope(term spread) and curvature of yield curve have the good predictive power, but the level of yield curve has the low predictive power for the annualized cumulative percentage change in Industrial Production Index. Conclusions : This result shows that predictive power for the Industrial Production Index’s growth rate is especially very high during 2008.1-2021.9 that is continued the lower inflation and interest rate after the 2008 global financial crisis. 이 논문에서는 우리나라에서 수익률 곡선 요인들이 실물경제활동인 산업생산지수의 성장률에어느 정도의 예측력을 갖는지를 분석한다. 이러한 분석을 위해 여기에서는 선형회귀모형을 이용하여 산업생산지수의 연간 누적 및 한계 비율 변동과 수익률 곡선 요인들 간의 관계를 추정한다. 추정의 결과 수익률 곡선의 기울기(기간 스프레드)와 곡률은 산업생산지수의 연간 누적비율 변동에 대해 양호한 예측력을 갖고 있음을 보여준다. 반면에, 수익률 곡선의 수준 요인은이러한 변동에 대해 낮은 예측력을 나타내고 있다. 전체 추정기간 중에서 산업생산지수의 성장률에 대한 수익률 곡선의 예측력은 보다 낮은 인플레이션과 저금리가 지속된 2008년 1월부터 2021년 9월까지의 기간에서 매우 높게 나타나고 있다.

Improved Global Maximum Power Point Tracking Method Based on Voltage Interval for PV Array under Partially Shaded Conditions

Kun Ding,Xiang Wang,Quan-Xin Zhai,Jun-Wei Xu,Jing-Wei Zhang,Hai-Hao Liu 전력전자학회 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.4

The power?voltage (P?V) curve of photovoltaic (PV) arrays connected in parallel to bypass diodes would have several local maximum power points (LMPP) under partial shading conditions (PSC). Conventional maximum power point tracking (MPPT) methods fail to search for the global maximum power point (MPP) because the searched peak point may remain at the LMPP on the P?V curve under PSC. This study proposes an improved MPPT algorithm to ensure that PV arrays operate at global maximum power point (GMPP) under PSC. The proposed algorithm is based on a critical study and a series of observations of PV characteristics under PSC. Results show the regularity of voltage interval between LMPPs. The algorithm has the advantages of rapidly reaching GMPP, maintaining stability, and recovering GMPP quickly when the operating condition changes. Simulation and experimental results demonstrate the feasibility of the proposed algorithm.

PHEMT 비선형 모델을 이용한 IMT-2000 단말기용 전력증폭기 설계

김창우,박주상 慶熙大學校 레이저 工學硏究所 1999 레이저공학 Vol.10 No.-

The 2-stage Power Amplifiers with AlGaAs/InGaAs/GaAs PHEMT are designed for the new generation mobile communication IMT-2000 handsets. The parameters of Statz-Pucel's nonlinear model are extracted by a curve-fitting method. Comparing with measured S parameter, the validity of equivalent model parameters are proved. To achieve the high gain performance, the Drive(gain) amplifier was designed in the front stage of power amplifier. At 1.95 GHz, the 2-stage Power Amplifier designed in this paper was achieved with a ?? of 31 dB (1.26 W), power added efficiency of 39%, linear gain of 32 dB. The chip size is 1.35 X 2.27㎠.