• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.222-223
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• 2012

본 논문에서는 태양광 인버터용 최대전력점 추종기의 고 효율화를 위한 새로운 구조의 무손실 스너버를 제안한다. 제안된 무손실 스너버는 보조 인덕터 1개, 스너버 캐패시터 2개, 다이오드 2개만으로 구성되어 시스템 부피가 크게 증가하지 않는다. 또한 제안된 무손실 스너버는 보조 인덕터 및 스너버 캐패시터로 인하여 스위치의 턴 온 및 턴 오프 시 소프트 스위칭이 가능하며, 출력 다이오드의 역회복 특성에 의한 역전류 현상 또한 크게 개선할 수 있다. 또한 스너버 캐패시터에 저장된 에너지는 공진을 통하여 모두 출력측으로 회생되므로 효율이 우수한 장점을 갖는다. 제안된 무손실 스너버의 타당성 검증을 위하여 1.5kW급 부스트 컨버터의 시작품 제작을 통한 실험결과를 제시한다.

• The Optical Journal
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• v.13 no.3 s.73
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• pp.14-16
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• 2001

국내 카메라 시장은 1997년 약 1,300억원 규모까지 성장했으나, IMF로 인해 1998년에는 775억원 규모로 -40$\%$의 역신장을 기록하였다. 1999년에는 35mm 카메라 시장규모가 1,000억원대로 회복 국면에 들어섰으며, 2000년 시장규모는 경기 침체 속에서도 1,150억원 수준에 도달해 전년 대비 성장했다. 2001년도 역시 35mm 카메라와 디지털카메라의 성장이 이어지는 가운데 디지털카메라 전체시장 규모는 약63

• Journal of Korean Ophthalmic Optics Society
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• v.8 no.1
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• pp.59-64
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• 2003

To Photochoromic lens light irradiation side darkening status and fading status photo-transmittance decrease. If remove light irradiation, get into fading state and photo-transmittance has reversibility process that get back originally in state. Get CIE $L^*a^*b^*$ relationship colorimetric using darkening in Photochoromic lens and at fading process. Photochromism's spectrophotometer that produce itself. Darkening and fading state colorimetric ($a^*-b^*$) linear be curvy, and is gradidnt of (-) value. And change lineally. The colorimetric transfer amount is Blue ${\rightarrow}$ Yellow, Red ${\rightarrow}$ Green form. Colorimetric is low $b^*$ value than darkning state in fading state, and Photochromism's coodination transfer moves on the contrary with darkning state, photochoromism relationship estimation method about photochoromic lens can use by colorimetric difference about darkening and fading.

• Bulletin of the Korea Photovoltaic Society
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• v.3 no.2
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• pp.42-47
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• 2017

The potential induced degradation (PID) phenomenon shows severe power loss within several years from the initial installation of solar power system. The accumulated power loss by PID is inevitable because the PID is suspected only if the power loss exceeds several percent. In this paper, we analyzed the cases of PID diagnosis and recovery by visiting the suspected PID site about 17 months after the installation of the 100kW PV system. The power difference of the two 50kW inverters was more than 20kWh, and the PR difference was more than 8%. From the beginning of the installation, the difference in power gradually increased. The recovery was observed for about 7 months by applying 1000V in the reverse bias at night. As a result, the power difference of the two inverters was recovered to within 2kWh. In the case of a power station suffering from PID in the field, it will be helpful for stable development operation by quick diagnosis and problem solving.

• Korean Journal of Food Science and Technology
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• v.47 no.1
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• pp.81-86
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• 2015

Intense pulsed light (IPL), a nonthermal technology, has attracted increasing interest as a food processing technology. However, its efficacy in inactivating microorganisms has not been evaluated thoroughly. In this study, we investigated the influence of IPL treatment on the inactivation of Escherichia coli O157:H7 depending on light intensity, treatment time, and pulse number. Increased light intensity from 500 V to 1,000 V, raised the inactivation rate at room temperature. At 1000 V, the cell numbers were reduced by 7.1 log cycles within 120 s. In addition, increased pulse number or decreased distance between the light source and sample surface also led to an increase in the inactivation rate. IPL exposure caused a significant increase in the absorption at 260 nm of the suspending agent used in our experiments. This indicates that IPL-treated cells were damaged, consequently releasing intracellular materials. The growth of IPL-irradiated cells were delayed by about 5 h. The degree of damage to the cells after IPL treatment was confimed by transmission electron microscopy.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.48 no.2
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• pp.157-167
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• 2022

In this study, we investigated the effects of heptapeptide on cellular activation and inhibition of cellular damage induced by photoaging condition in NIH3T3 fibroblasts. Cell proliferation and extracellular matrix (ECM) expression were induced by heptapeptide. The reduced cell viability under photoaging condition through ultraviolet A (UVA) irradiation was increased by heptapeptide. And UVA-induced apoptosis, matrix metalloproteinases-1 (MMP-1) expression, and reactive oxygen species (ROS) level were decreased by heptapeptide. In addition, the inhibition of transforming growth factor-β (TGF-β)/smad signaling under UVA irradiation which resulting in reduction of ECM expression was also recovered by heptapeptide. We also tested the effect of heptapeptide under another photoaging condition through heat shock, and pre-treatment of heptapeptide prevented the phosphorylation of mitogen-activated protein kinase (MAPK) and MMP-1 expression induced by heat shock. From these results, it has been shown that the heptapeptide has protective effects on fibroblasts through the up-regulation of cellular activity and through the decreasing of intracellular ROS level induced by UVA irradiation or heat shock. It is expected that the dermal protection effect of heptapeptide can be applied as a new cosmetic material in the future.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.41 no.1
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• pp.1-7
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• 2015

Cornus walteri Wanger has been used in folk medicine in Korea. Ultraviolet (UV) irradiation has been known as a major cause of photo damage in skin. In the present study, research on how to cure damaged cells by UVB was conducted using an extract of Cornus walteri Wanger leaves (CWE), which was treated with an enzyme. CWE was applied to human dermal fibroblasts (HDFs) affected by UVB. UVB-irradiated HS68 cells showed increased caspase-3 activity, phosphorylation of p53, ${\gamma}H2AX$, cyclobutane pyrimidine dimers (CPDs) formation, and DNA fragmentation compared with non-irradiated cells. However, all these effects were inhibited by treatment with CWE for 12 h after UVB irradiation. Furthermore, CWE has proved not to cause primary skin irritation through the human patch test. Collectively, these results suggest that CWE could be a new potential candidate as photoprotective agent against UVB-induced cellular damage in HDFs.

• Journal of Sensor Science and Technology
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• v.5 no.3
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• pp.65-73
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• 1996

One of the important factor in drug stuffs to a patient is to inject exact amount with stable flow rates. Since improper injection amount and flow rates would cause bad effect to recovery of a patient, the detecting sensors with high sensitivity is required for an injection pump systems' performance improvement. In this study, the three sensors, piezo film sensor, photo transistor and photo array, were compared to find best one for an injection pump monitoring system. Using suggested data processing technique and photo array sensors, we could minimize the effect of interference, disturbance, illumination, and sensitivity change caused by sensor's position. According to the experiments, the photo array showed the higher reliance than any other the three types of sensors.

• The KIPS Transactions:PartC
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• v.12C no.6 s.102
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• pp.881-890
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• 2005

Over for the past 10 years, the increase in geometric progression for the internet traffic, has allowed the IP protocol framework to be the most important network technology. In addition, the internet service is being developed as a service mode differentiated, aiming to support the new-mode real-time multimedia services such as internet phone, video conference, cyber reality, and internet game, focusing on offering a latest service. These days, aiming to solve the need for broad bandwidth along with guaranteeing QoS, the WDM technology of offering multiple gigabit wavelengths is emerging as the core technology of next-generation optical internet backbone network. In the next-generation optical internet backbone network based on WDM, the QoS framework is one of fore subjects aiming to offer a service of guaranteeing QoS This study analyzes the requirements of performance related to QoS framework in IP Subnet and in WDM optical backbone network, and suggests optical QoS service framework differentiated. in order to guarantee end-to-end QoS through the next-generation optical internet backbone network, using GMPLS control protocol.

• Journal of Plant Biotechnology
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• v.31 no.3
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• pp.239-248
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• 2004

This experiment was carried out to confirm that phytochrome regulates anthocyanin bio-synthesis during cell suspension culture system of grape or not. In suspension culture of grape, maximum accumulation of anthocyanin was observed at the stationary phase under continuous white light condition. From mono-chromatic light interruption for 24h at the 4th or 7th day on the suspension cultured cells, the anthocyanin accumulation was highly enhanced at the light interruption at 7th day than 4th day under all monochromatic light treatment. However, the cell growth patterns were not affected by any light treatment. In the darkness, the anthocyanin synthesis was very low but remarkably increased by blue light or red light irradiation. However, the increase of anthocyanin accumulation by blue or red light was suppressed by far-red light in the suspension cells of grape. This suppression by far-red light on the anthocyanin synthesis also observed on the cells treated red or far-red light alternatively. These results implied that phytochrome regulation system may be involved in the anthocyanin biosynthesis of the suspension grape cells. By RNA expression analysis, chalcone synthase (CHS) gene was expressed highly by blue and red light but low by far-red light. The synergistic increase of CHS gene expression was also observed at the treatment of blue light followed by red for 24h. This result may explain the increase of anthocyanin accumulation in B/R treatment. Although the expression of phytochrome gene (PHYA or PHYB) was not highly increased by all light treatment (blue, red, and far-red light) the expression of both PHYA gene and PHYB gene was increased a little in cells treated red or far-red light. In grape suspension cells, the red light enhanced the anthocyanin synthesis, whereas the far-red light was suppressed. Although it was not confirmed whether or not phytochrome gene is activated in anthocyanin accumulating grape cells, we believed that anthocyanin biosynthesis in grape cells may be regulated under phytochrome signal transduction system.