• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.398-399
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• 2011

In this paper, an analysis is being performed on the effect of harmonics on loads in a distributed generation environment which includes renewable energy sources such as wind farms. The paper will assess the limits of the harmonic content that is allowed to be present in the adjacent loads while conforming to the distributed generation connection standards. The analysis is being performed in PSCAD/EMTDC where field measurements of wind data is being employed for the study.

• 한국생산제조학회지
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• 제19권6호
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• pp.790-796
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• 2010

This paper designed the horn of half-wave needed for Ultrasonic meta) welding. The horn has to be designed and manufactured accurately, because measurements such as the shape, length, mass and etc. have effects on the resonant frequency and the vibration mode. Designed horn of half-wave has the feature of 40,000Hz of nature frequency, and maximizes vibration range in the Tip by resonance in the frequency of ultrasonic wave machine. In this study, we calculated and analyzed the natural frequency to find the optimal design of the horn that amplified the amplitude about double by the modal analysis and harmonic analysis using ANSYS. And we did FFT analysis of the manufactured horn.

• 한국생산제조학회지
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• 제20권3호
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• pp.263-267
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• 2011

Ultrasonic metal welding can be used to weld different metals together safely and precisely, without solder, flux and special preparation. Ultrasonic metal welding machine consists of a power supply, a transducer, a booster and a horn. This paper designed the horn needed for Ultrasonic metal welding. The horn has to be designed and manufactured accurately, because measurements such as the shape, length, mass and etc. have effects on the resonant frequency and the vibration mode. The designed horn has the feature of 40,000Hz of nature frequency, and maximizes vibration range in the Tip by resonance in the frequency of ultrasonic wave machine. In this paper, we calculated and analyzed the natural frequency to find the optimal design of the horn that had the amplitude about $12{\mu}m$ by the modal analysis and harmonic analysis using ANSYS. And we analyzed FFT analysis of the manufactured horn.

• 한국농림기상학회지
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• 제14권1호
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• pp.11-18
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• 2012

월별 기후통계량의 조화해석에 의해 생성한 일 기온 자료가 생물계절모형의 입력자료로서 적합한지 여부를 평가하여 농림업 부문 기후시나리오 응용정보 제작 상오류를 제거하기 위해 본 연구를 수행하였다. 서울관측소의 1971-2000 평년 월별 일 최고기온과 최저기온 평균값으로부터 조화해석에 의해 365일 간 기온자료를 생성하였다. 이것을 널리 검증된 온도시간 기반의 벚꽃 개화모형에 입력하여 휴면, 발아, 개화 등 주요 식물계절을 추정하였다. 같은 기간 중 실측기온자료에 의해 모형을 구동시켜 얻은 결과와 비교한 바, 연차변이를 전혀 반영하지 못하는 것은 물론, 휴면해제 25일 단축, 강제 휴면기간 57일 연장, 발아 14일 지연, 개화 13일 지연등 평균값도 크게 달라 식물계절을 크게 왜곡시키는 것으로 판단되었다. 대안으로서 확률추정기법에 의해 일기상자료를 생성하고 이를 이용하여 모형을 구동한 결과 실측결과에 비해 휴면해제 6일 단축, 강제휴면기간 10일 단축, 발아 3일 지연, 개화 2일 지연 등으로 조화해석자료 사용에 비해 크게 개선되었음을 확인하였다. 연차변이양상 역시 실측기온에 의한 모의결과와 크게 다르지 않아, 향후 이 자료를 농업부문 전자기후도 제작에 적용하면 기후변화 적응정책 수립을 실용수준에서 지원할 수 있을 것으로 보인다.

• Journal of the Optical Society of Korea
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• 제2권2호
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• pp.54-57
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• 1998

A noncollinear-phase-matching cone of second harmonic generation(SHG) was observed in a LiNbO3 crystal doped with l mol% MgO. Birefringence refractive indices can be accurately evaluated by analysing the temperature phase matching characteristic for SHG combined with the measurement of the half cone angle. The electro-optic coefficient can also be determined form the observed change of the half cone angle when a DC electric field is applied along the optic axis.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.677-678
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• 2008

In this study, the method for the measurement of harmonics at nonsinusodial signal, which utilizes two synchronized high precision digital multimeters has been developed. The harmonics of voltage and current waveforms were computed from the acquired digitize samples through the DMMs and using developed software which based on FFT algorithm. The system can be used as a reference system to calibrate harmonic analyzers.

• 전기의세계
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• 제28권1호
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• pp.53-58
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• 1979

In the microwave heating system, a ferroresonant transformer is used to regulate the magnetron power fluctuation. For the simplification, nonlinear characteristics of the transformer and the magnetron are idealized to be piecewise linear. Dipped peak shape of the magnetron current is explained qualitatively by considering the fundamental and third harmonic frequency components in the circuit. Design equations providing the values of the leakage inductance, turn ratio of the transformer and the capacitance are derived analytically by cosnidering the fundamental frequency component only. The ferroresonant transformer is designed to obtain a required regulation and high input power factor from the derived design equations, and analytical calculations are compared with experimental measurements.

• Transactions on Electrical and Electronic Materials
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• 제9권4호
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• pp.151-155
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• 2008

Using pentacene field effect transistors (FETs) with Au source and drain electrodes, electron injection from the Au electrodes into the pentacene was investigated. The capacitance-voltage (C-V) and optical second harmonic generation (SHG) measurements were employed. Electron injection from the Au electrodes was suggested by the hysteresis behavior with the C-V characteristics and slowly decaying SHG signal under DC biasing, A mechanism of hole-injection assisted by trapped electrons is proposed. To confirm electron injection process, light-emitting behavior under the application of AC applied voltage was observed.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 추계학술대회 논문집
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• pp.868-873
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• 2004

Recently, The surface-wave method has widely been used for the site investigation due to the economic advantage and the improved reliability. The typical surface-wave methods currently available are SASW method, MASW method and CSW method. The CSW method has a potential of high-quality measurement, but its inherent problems limited its use to the special cases such as the compaction-quality control. The CSW method uses the steady-state harmonic vibration for the seismic source as in the steady-state Rayleigh-wave method, which is superior to the impact source used for other methods. This study proposed a new procedure to solve the inherent problems of the CSW method and to improve the reliability of the CSW measurements. To verify the validity of the proposed in this study, the SASW results were compared with the CSW results for the numerical simulation of the CSW testing. Also, the feasibility of the proposed method was verified using the field measurements at a geotechnical site.

• 한국분무공학회지
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• 제9권4호
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• pp.67-76
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• 2004

Diode laser absorption sensors are advantageous because they may provide fast, sensitive, absolute, and selective measurements of species concentration. These systems are very attractive for practical applications owing to its compactness, reasonable cost, robustness, and ease of use. In addition, diode lasers we fiber-optic compatible and thus enable simultaneous measurements of multiple species along a line-of-sight. Recent advances of room-temperature, near-IR and visible diode laser sources for telecommunication, optical data storage applications make it possible to be applied for combustion diagnostics based on diode laser absorption spectroscopy. Therefore, combined with fiber-optics and high sensitive detection strategies, compact and portable sensor systems are now appearing for variety of applications. The objectives of this research are to develop new gas sensing system and to verify feasibility of this system. Wavelength modulation spectroscopy has been demonstrated in these experiments and has a bright prospect to this diode laser system.