• Journal of Digital Convergence
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• v.20 no.3
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• pp.487-495
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• 2022

Pycnogenol is used as a dietary supplement based on various medical research studies suggesting health benefits. In recent years, it has also been used in cosmetic products, but the clinical research on its dermatologic effects has been insufficient. This study was designed to determine the effectiveness of pycnogenol topically applied to skin of individuals with acne in their teens and twenties. Cosmetics containing 0.2% pycnogenol were applied to a group of 11 clinical subjects for 6 weeks and their skin conditions were assessed. The group that used cosmetics with pycnogenol showed decrease in P-Acnes, acne causing bacteria, phorphyrin index, a metabolite, and the pigmentation and redness index. This study confirms that pycnogenol extract is effective dermatologically in decreasing acne bacteria and reducing redness and pigmentation of skin affected by acne.

• Journal of Radiation Protection and Research
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• v.30 no.3
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• pp.107-112
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• 2005

Cascade summing occurs when two gamma-rays emitted in the decay of a single nucleus both deposit energy in a detector. The effect may cause systematic errors that can reach levels of more than ten percent for some radionuclides. A method for estimation of the effect of these coincidences was developed. It is based on direct computation of the effect by means of peak to total ratio measured for the place around the detector. It has been shown that the P/T ratio for the given energy in the working space around the detector may not be a constant value and must use its mean value. Some results from a peak to total calibration study in the presence of scattering materials are also given.

• Environmental and Resource Economics Review
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• v.17 no.2
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• pp.213-233
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• 2008

In this paper, we estimate the effects of the two most important means of summer time demand side management in Korean power market: adjustment of vacation or repair timing and the voluntary saving program. We use regression analyses to estimate how effective these two programs are in reducing the peak time demand during the summer. Our results show that adjustment of vacation or repair timing actually reduces the daily peak demand by 0.53 kWh per one kWh reported reduction calculated from the agreements between Kepco and the users. The voluntary saving program reduces the daily peak by 0.57 kWh per one kWh reported reduction calculated from the agreements between Kepco and the users. However, when we include these two effects in the same regression model, their respective estimated effects become much weaker.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2011.07a
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• pp.462-465
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• 2011

본 논문에서는 다중 반송파, 특히 OFDM 시스템의 PAPR 을 감소시킬 수 있는 CFR 알고리즘을 다룬다. 기존의 피크 윈도윙 기법이 윈도우 길이 내에 피크들이 여러 개 있을 경우, 과도 clipping 으로 인하여 성능이 열화되는 현상을 개선하기 위하여 포락선 기반 피크 윈도윙 기법을 적용한다. 뿐만 아니라, 피크 윈도윙이 가지고 있는 EVM 열화를 완화하기 위하여 기존의 단순 clipping 기법과 혼합하여 시스템에서 요구하는 EVM 성능뿐 아니라 ACLR 성능까지도 만족하도록 한다. MATLAB 을 이용하여 알고리즘을 검증하고, 하드웨어 구현을 위하여 Xilinx Virtex5 를 이용하여 검증하여 제안하는 기법의 복잡도는 높지만 EVM 과 ACLR 성능이 우수함을 알 수 있다. 효율적인 주파수 이용과 수신 성능 측면에서 우수한 성능을 보인다. 따라서 DVB-T 나 LTE, IEEE 802.16m 등의 차세대 방송 및 통신의 전송에 이용되는 OFDM 신호의 PAPR 을 효과적으로 줄일 수 있는 기법으로 적용될 수 있다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2012.05a
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• pp.240-240
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• 2012

MgZnO는 전기적, 광학적 특성으로 인해 여러 연구 분야에서 주목을 받고 있으며, 발광특성을 알아보기 위해 Si 기판에 ZnO나노막대를 성장시킨 후 MgZnO 덮개층을 성장시켰다.열처리 효과에 따른 구조적 및 광학적 특성을 조사하기 위해 scanning electron microscopy, X-ray diffraction (XRD), 그리고 photoluminescence (PL)를 이용하였다. PL 측정 결과 3.3 eV에서 ZnO 나노막대 피크가 관측되었고, 3.48 eV에서 MgZnO 덮개층과 관련 된 피크가 관측되었다. 열처리 온도가 증가함에 따라 균일한 밀도를 가지는 청색 (432nm), 녹색 (512nm), 적색 (652nm)의 피크가 관측되었다.

• 한국사회정책
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• v.23 no.2
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• pp.25-48
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• 2016

This study stemmed from the notion that effects of wage peak system were investigated exclusively on management efficiency from the perspective of workplace. As a way to overcome the limitation of previous studies, This study examined the effects of wage peak system on age integration of senior workers. Quantitative analyses with data from workplace panel survey were executed. Results revealed that percent of workers aged 50 and over was significantly higher in work places that implemented wag peak system than that of those did not. Also Average year of employment for full time workers was higher in work places that implemented wag peak system than that of those did not, suggesting that wage peak system was related to labor market integration of aged workers in some ways.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.8
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• pp.1810-1817
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• 2004

A diffractive optical element(DOE) for an optical pickup system is proposed in this thesis. Optimization algorithms are used to synthesise the DOE to meet a detailed specification of the two kind of cost function. The one isso called as apodization which refers to the process of suppressing the secondary maxima and the other is so called as sharpness which refers to the process of reducing the size of primary maxima. The result obtained by simplex optimization method is that the apodization and sharpness are well achieved separately. In apodization, the secondary maxima is reduced up to 39%. And in sharpness, the size of first maxima is reduced to 95.2％.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.6
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• pp.105-110
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• 2008

We have investigated the high temperature rapid thermal annealing of GaN epilayers in nitrogen atmosphere. Annealing has been performed in a rapid thermal annealing furnace at $950^{\circ}C$. The effect of rapid thermal annealing of GaN was studied by x-ray diffraction. The Bragg peak shifts toward larger angle as the annealing time increases. The full width at half maximum (FWHM) of the peak slightly increase, followed by decreases, and increases again as the thermal treatment time increases. The improvement of structural properties of the samples was observed after rapid thermal annealing under optimum conditions. This improvement in crystal quality is due to a reduction of the spread in the lattice parameter in epilayers.

• Journal of the Mineralogical Society of Korea
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• v.22 no.2
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• pp.81-86
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• 2009

The luminescence and fluorescence were investigated by photoluminescence spectroscopy for six gemstones which exhibit color change effect. The shape of luminescence peaks appears different when observed by a photoluminescence spectroscopewith a 514 nm Ar laser source. However, it was not possible to observe the difference in the spectra between the natural and synthetic origins for the same type of gemstones. It was found that the photoluminescence spectrum was related to the crystal structure of the stones. Photoluminescence spectra using a 325 nm He-Cd source reveal that fluorescence is relatively strong for synthetic alexandrite, synthetic color change sapphire and natural alexandrite comparing to the rest of gemstones examined.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.1
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• pp.9-17
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• 2005

We studied the characteristics of impedance and electromechanical coupling coefficient in ZnO and AIN thin films by using resonance frequency spectrum method. The response peak of impedance decreased with the decrease of thickness of piezoelectrics, the number of mode of response peak decreased with the decrease of substrate thickness. An error of Kt² estimated from input Kt² increased as the thickness of piezoelectrics decreased and the thickness of substrate increased. Also, the error was increased in case of a large acoustic impedance of substrate. It was found that the composite resonator operating in optimized condition could be designed through the resonance frequency spectrum analysis of composited resonator consisted of piezoelectric thin film and substrate.