• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.310-310
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• 2010

태양전지의 양자효율이란 입사되는 광자 수에 대한 태양전지에 의해 수집되는 캐리어 수의 비를 의미한다. 본 연구에서는 결정질, 다결정질, 비정질 실리콘 태양전지 양자효율 측정 정확도 향상에 대하여 연구하였다. 태양전지 양자효율 측정에 어떠한 변수들이 영향을 미치고 정확한 측정을 하기위해서는 측정을 어떻게 하여야 하는가에 대한 실험을 하였다. 태양전지 특성분석은 실제 사용 환경에 맞도록 표준측정조건(standard test condition: STC)에서 측정한 데이터를 사용하여야 한다. 이 표준측정조건은 AM1.5G 스펙트럼, $100\;mW/cm^2$의 강도 및 온도 $25^{\circ}C$에서의 측정을 말한다. 조건에 맞지 않는 측정을 할 경우 어떠한 변화가 있는지와 어떻게 측정을 하는 것이 정확한 측정인가에 대한 연구를 진행하였다. 바이어스 광의 강도와 쵸핑 주파수에 따라 측정을 진행하였고, 태양전지의 분광반응도(spectral response: SR)를 측정하여 이를 이용하여 양자효율을 계산하였고, 양자효율 결과를 토대로 분석을 진행하였다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.1185-1188
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• 2002

The objective of this paper is to apply experimental methods to measure the in-plane vibration intensity of a semi-infinite beam. Two experimental methods have been implemented to measure the in-plane vibration intensity of the beam. The first method is the cross spectral intensity measurement method using two accelerometers. The second method is the frequency response method using the only one acrelerometer. It has the advantages of shortening measurement time and reducing accelerometer phase error. Experimental results showed that those experimental methods can be effectively used to measure the structural In-plane vibration intensity.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.5 s.110
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• pp.521-528
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• 2006

The vibration fatigue is suitable case of fatigue problem that system is exposed to the random or other irregular sources. Even some kinds of effort using power spectral density (PSD) and statistical concept was presented to cope with the intangible force signal, it is still lack of providing a reasonable solution when its exciting frequency is near or beyond of first eigenvalue. In this paper, energy approach method is presented to calculate a vibration induced fatigue damage in frequency domain. Since the corresponding damage become much larger than nominal case when the vibration is coupled with a mode shape of given structure, the new technique compensate the characteristics of structure with a measured frequency response function (FRF) between forcing acceleration and responding stress.

• International Journal of Aeronautical and Space Sciences
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• v.2 no.2
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• pp.56-64
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• 2001

An optical temperature sensor based on the etched planar waveguide Bragg grating is developed and its performance is explored using theoretical and experimental methods. The planar waveguide is designed and fabricated using optical lithography and wet chemical etching. An efficient butt coupled optical fiber is used to examine the spectral characteristics of the grating sensor, and to investigate the grating parameters. The typical bandwidth and reflectivity of the surface etched grating has been ~0.2 nm and ~7%, respectively, at a wavelength of ~1,552 nm. The temperature-induced wavelength change of the optical sensor is found to be slightly non-linear over ${\sim}200^{\circ}C$ temperature range. Theoretical models for the grating response of the sensor based on waveguide and classical laminated plate deformation theories agree with experiments to within acceptable tolerance.

• Fibers and Polymers
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• v.6 no.2
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• pp.127-130
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• 2005

Intrinsic UV reflection and fluorescence behaviors of polycarbonate, polyurethane and poly(ethylene terephthalate) films were investigated in order to characterize the interaction of water in these films. During water sorption process, UV reflection spectra of polycarbonate and polyurethane films showed little peak position changes. Fluorescence emission spectra of polycarbonate films showed red spectral shifts from 332 nm with water immersion time. This red-shifted peak could be due to phenyl-2-phenoxybenzoate, which is one of the major thermal degradation products in polycarbonate. Fluorescence peaks of polyurethane films appeared at two different positions and the ratio of these peak intensities increased with increasing immersion time. In the case of PET films, the UV reflection spectrum showed the peak intensity around 340 nm to change in response to water sorption. The fluorescence near 388 nm probably due to ground state dimer exhibited sensitivity with water sorption, when excited at 340 nm.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.10B
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• pp.1707-1713
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• 2000

We have proposed a tunable optical ADM using a fiber-optic transversal filter which is composed of fiber couplers and metal-film coated fiber-optic tapped delay-lines with a flat spectral response in abroad range of wavelength. Simulation results show that the optical loss at the DROP and PASS wavelengths of the OADM is negligible and the wavelength tunability is 0.78${\mu}{\textrm}{m}$/ps for the unit time delay of 2 ps. In order to investigate the effects of wavelength drift of the imput optical signal on the OADM the loss at the DROP port and the crosstalks to the other ports have been calculated. The maximum bit rates have been calculated at 46.26 Gb/s for the input Gaussian pulse width of 10 ps.

• Journal of ILASS-Korea
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• v.20 no.4
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• pp.230-235
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• 2015

The demands for reliable particle cloud temperature measurement exist in many process industries and scientific researches. Particle cloud temperature measurements depend on radiation thermometry at two or more color bands. In this study, we developed a sensitive, fast response and compact online infrared two-color probe to measure the temperature of a particle cloud in a phase of two field flow (solid-gas). The probe employs a detector contained two InGaAs photodiodes with different spectral responses in the same optical path, which allowed a compact probe design. The probe was designed to suit temperature measurements in harsh environments with the advantage of durability. The developed two-color probe is capable of detecting particle cloud temperature as low as $300^{\circ}C$, under dynamic conditions.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.28A no.9
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• pp.752-760
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• 1991

The computer aided analysis is performed to investigate the influence of physical parameters (thickness and doping concentration, etc.) in the window, emitter, base on the efficiency characteristics of a uniformly doped hetroface cell. A field aided heteroface cell is newly designed on a basis of optimum data obtained from the theoretical analysis. The field aided heteroface cell fabricated using MOCVD exhibits a total/active area conversion efficiency of EFF. (tot) = 18.9% /EFF. (act.) = 21.4% under the natural incident light of 56.2 mW/cm\ulcorner having a low series resistance of Rs = 0.94 \ulcornercm\ulcornerand a high spectral response of S.R. (ext) > 90% in a range of $7700{\AA}$ < $8500{\AA}$.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 1998.04a
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• pp.57-62
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• 1998

The objectice of this study is to dvaluate the physical condition response of a drever by the change of CO$^{2}$ concentration in the automobile with EEG spectrum analysis. The experiment was performed in a semi-shielded simulated automobile with 10 healthy adults. The results showed that as CO$_{2}$ concentration increased from 500ppm to 6,000ppm, the $\alpha$' value significantly decreased(p*<0.05) while $\beta$' increased (p*<0.05). In a real parked automobile with 2 adult passengers, the CO$_{2}$ gas concintration reached at 6,000ppm in 15 minutes. These spectral data are in well agreement with the subject's verval statement of experiencing uncomfortableness when CO$_{2}$gas was increased ti over 5,000ppm. These results indecated that the EEG spectrum analysis can be appropriately used to assess physical condition of a driver in the changing automobile environment.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.1125-1131
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• 2009

This paper presents the evaluation of fatigue life for a journal box attached to rolling stock bogie under random dynamic loading condition. Because a journal box was under random dynamic loading conditions, the fatigue life assessment due to these loads requires the analysis considering the multiaxial effect of random dynamic loading. To do this work, the finite element analysis has been conducted to calculate random dynamic response using multiaxial acceleration data. Then, the fatigue life assessment of component has been conducted using vibration fatigue analysis applying the power spectral densities of the responses obtained through the FEA The results of fatigue life assessment were compared to the damage from the strain measurement. This study shows that can be evaluated the fatigue life assessment considering real service condition about a component attached to rolling stock bogie.