• Korean Journal of Food Science and Technology
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• v.22 no.7
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• pp.762-766
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• 1990

The effect of storage conditions on the oxidative stability of cholesterol in butter was studied by identifing cholesterol oxides by TLC. Experimental variables for storage conditions were packaging(packaged and unpackaged), storage temperature(ambient and refrigerated), light source(dark, fluorescent and ultraviolet), and storage period(2, 4, 6, and 8 weeks). No cholesterol oxides were detected from packaged butter under all storage conditions. When unpackaged butter was stored under darkness at ambient and refrigerated temperatures, cholesterol oxides were not detected even after 6 weeks of storage, but small amounts of $7{\alpha}-and\;7{\beta}-hydroxycholesterols$ were detected after 8 weeks of storage. When unpackaged butter was stored under ultraviolet light at ambient temperature, $7{\alpha}-hydroxycholesterol,\;7{\beta}-hydroxycholesterol$ cholestane-triol, and cholesterol epoxide were detected after 2 weeks of storage, and when fluorescent light was used instead of ultraviolet light, the same species of cholesterol oxides were detected after 6 weeks of storage.

• Journal of Bio-Environment Control
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• v.21 no.3
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• pp.220-227
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• 2012

This study was conducted to analyze the seeding quality of paprika and the growth and early yield after transplanting of paprika nursed under artificial light and natural light. In this study, blue LED, red LED, and white fluorescent lamps (FL) were used as artificial lighting sources. Photoperiod, average photosynthetic photon flux, air temperature, and relative humidity in a closed transplants production system (CTPS) were maintained at 16/8 h, $204{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, 26/$20^{\circ}C$, and 70%, respectively. Leaf length, leaf width, leaf area, top fresh weight and dry weight of paprika seedlings, and chlorophyll content in paprika leaves nursed under LED and fluorescent lamps for 21 days after experiment were significantly affected by light treatments. As compared with the control (white FL), leaf area of paprika grown under blue LED, red LED, and natural light was decreased by 63%, 63%, and 28%, respectively. Top dry weight of paprika grown under blue LED, red LED, and natural light was 64%, 50%, and 22%, respectively, compared with the control. Number of leaves on 18 days after transplanting showed with red LED, blue LED, and natural light by 86%, 84%, and 48%, respectively, compared with the control. On 114 days after transplanting, paprika nursed under blue LED and red LED had relatively short plant height. This result might be caused that the elongation of its internodes was suppressed by the illumination of sole blue or red light. Average number of fruits per plant harvested during 4 weeks after first harvest was 3.5 with red LED, 3.3 with blue LED, 1.0 with natural light, and 2.2 with control, respectively. Early yield of paprika nursed under red LED, blue LED, natural light, and control were 453 g/plant, 403 g/plant, 101 g/plant, and 273 g/plant, respectively. Larger fruit of 136 g was harvested with red LED treatment. Even though the early yield of paprika was greatly increased with artificial lighting, but total yield was almost similar as the harvest period after transplanting in greenhouses was lengthened. From the above results, we could understand that paprika nursed under white FL, blue LED, and red LED showed good growth after transplanting and was early harvested by a week as compared to the natural light. Therefore, the white FL, blue LED, and red LED as the artificial lighting sources in CTPS could be strategically used to enhance the seedling quality, to shorten the harvest time, and to increase the yield of paprika.

• Journal of Bio-Environment Control
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• v.23 no.4
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• pp.263-268
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• 2014

This research was performed to investigate the effect of light source and light quality in night break treatment on the growth and flowering of standard chrysanthemum. It was processed 4 hours (22:00-02:00) night break using LED 590, 610, 630, 660, 680nm and fluorescent lamp (mixed light of 480+540+610nm) in standard chrysanthemum 'Baekma' and 'Jinba' for 40 days from transplanting. The days to flower budding from short-day treatment of 'Baekma' were the longgest at fluorescent treatment (21.3 days) and were the shorttest at LED 590nm treatment (15.8 days) among all treatments. The days to flower budding from short-day treatment of 'Jinba' was longger with 18.0 days, 17.8 days, and 17.7 days at the fluorescent, LED 610nm, and 660nm treatments. And it was the shortest with 15.1 days in LED 590nm treatment. Similarly, the days to flowering from short-day treatment of 'Baekma' was the longgest with 56.9 days at fluorescent treatment, and was the shorttest in 51.6 days about LED 590 nm treatment. The days to flowering from short-day treatment of 'Jinba' was longer at fluorescent (56.0 days) and LED 660nm (56.7 days) treatments and was shortest at LED 590nm (52.9 days) among all treatments. Therefore, inhibition of flower bud initiation and flowering were the most effective under fluorescent treatment in case of 'Baekma', and fluorescent and LED 660nm treatments in case of 'Jinba'. The length and weight of cut flower of 'Baekma' and 'Jinba' were most excellent in fluorescent treatment in which the floral differentiation suppression effect was the best. Consequently, as to the growth and flowering of standard chrysanthemum, the treatment which was suitable as the light source and light quality for night break is regarded as the fluorescent lamp, and also under LED 660nm up to a certain level.

• Korean Chemical Engineering Research
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• v.53 no.5
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• pp.620-626
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• 2015

$Ho^{3+}$ doped $SrAl_2O_4$ upconversion phosphor powders were synthesized by spray pyrolysis, and the crystallographic properties and luminescence characteristics were examined by varying activator concentrations and heattreatment temperatures. The effect of organic additives on the crystal structure and luminescent properties was also investigated. $SrAl_2O_4:Ho^{3+}$ powders showed intensive green emission due to the $^5F_4/^5S_2{\rightarrow}^5I_8$ transition of $Ho^{3+}$. The optimal $Ho^{3+}$ concentration in order to achieve the highest luminescence was 0.1%. Over this concentration, emission intensities were largely diminished via a concentration quenching due to dipole-dipole interaction between activator ions. According to the dependence of emission intensity on the pumping power of a laser diode, it was clear that the upconversion of $SrAl_2O_4:Ho^{3+}$ occurred via the ground state absorption-excited state absorption processes involving two near-IR photons. Synthesized powders were monoclinic as a major phase, having some hexagonal phase. The increase of heat-treatment temperatures from $1000^{\circ}C$ to $1350^{\circ}C$ led to crystallinity enhancement of monoclinic phase, reducing hexagonal phase. The hexagonal phase, however, did not disappear even at $1350^{\circ}C$. When both citric acid (CA) and ethylene glycol (EG) were added to the spray solution, the resulting powders had pure monoclinic phase without forming hexagonal phase, and led to largely enhancement of crystallinity. Also, N,N-Dimethylformamide (DMF) addition to the spray solution containing both CA and EG made it possible to effectively reduce the surface area of $SrAl_2O_4:Ho^{3+}$ powders. Consequently, the $SrAl_2O_4:Ho^{3+}$ powders prepared by using the spray solution containing CA/EG/DMF mixture as the organic additives showed about 168% improved luminescence compared to the phosphor prepared without organic additives. It was concluded that both the increased crystallinity of high-purity monoclinic phase and the decrease of surface area were attributed to the large enhancement of upconversion luminescence.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.2
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• pp.8-15
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• 2006

To reduce costs and address other practical concern related to architectural lighting, we have been involved in various aspects of advanced daylighting design and control. If we look toward future building trends, we see that the advanced has already successfully deployed such complex lighting control systems. This paper takes a broad view of what advanced manufacturers have done to develop energy efficient lighting control technologies such as sensors, lumen maintenance, time of day scheduling, peak demand reduction and so forth. First of all strategies, daylighting controls would also need to be commissioned to respond to the specific daylighting signature of the zone. To translate the daylight in term of the amount of energy savings, an electric lighting system is designed and automatic on-off control system integrated with the contribution of daylighting has been applied to the operating of the artificial lighting. The lighting analysis program, Lumen-Micro predicts the optimal layout of conventional fluorescent and incandescent lighting fixtures to meet the designed lighting level and calculates unit power density, which translates the demanded amount of lighting energy.

• Horticultural Science & Technology
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• v.35 no.4
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• pp.490-498
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• 2017

The in vitro growth of virus-free sweet potato [Ipomoea batatas (L.) Lam.] plantlets was investigated under different light sources: fluorescent lamp (control); red (660 nm), blue (460 nm), white light-emitting diodes (LED), and two mixtures of blue and red LED (R:B = 8:2, and 7:3). Single node explants (10 mm) of three cultivars ('Matnami', 'Shincheonmi', and 'Yeonhwangmi') were cultured on Murashige and Skoog medium supplemented with $0.2mg{\cdot}L^{-1}$ 6-benzyladenine for 4 weeks. Explants were exposed to $150{\pm}5{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ photosynthetic photon flux at a distance of 20 cm, constant temperature of $25^{\circ}C$, and under 16/8-h (day/night) photoperiod. Using the same method, the in vitro growth of 10 cultivars under red LED was also compared. After 3 weeks, vine length was highest in plantlets cultured under red LED, and lowest in plantlets cultured under blue LED. Fresh and dry weights were also greatest in plantlets cultured under red LED. Compared to the control, vine thickness was significantly higher in plantlets grown under white LED and the 7:3 R:B LED mixture. Significant differences were observed among the 10 cultivars grown under red LED. 'Matnami', 'Shincheonmi', and 'Shinhwangmi' all had excellent vine lengths, and fresh and dry weights. Compared to the control, vine elongation of sweet potato plantlets was most effective under red LED, and culture duration was about 1 week shorter.

• Journal of the Korean Chemical Society
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• v.43 no.6
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• pp.636-643
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• 1999

Green-emission intensity of a $Zn_{2-x}Mn_xSiO_4$ phosphor, which is a potential candidate as a green component in PDP device, significantly increases provided that the compound is additionally heat treated at 900$^{\circ}C$ after solid state reaction at 1300$^{\circ}C$. In order to verify origin of such an intensity enhancement after the additional heat treatment in association with the electronic and local structural change at around Mn ions, the Mn K-edge X-ray absorption spectra were recorded. From the analyses of the preedge peak corresponding to $1s{\rightarrow}3d$ bound state transition and XANES spectrum, it is known that most Mn ions are in +2 oxidation state and substitute Zn ion site regardless of the thermal treatment. In addition, EXAFS analyses revealed that Mn ions formed $MnO_4$ tetrahedra with the Mn-O bond length shortened by 0.01${\AA}$ and with reduced Debye-Waller factor in the thermally treated sample.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.140-140
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• 2016

유기전계발광소자 (Organic Light Emitting Diode : OLED)는 보조광원이 필요 없고 천연색 표현이 가능하며, 낮은 소비 전력 및 저전압 구동 등의 장점으로 이상적인 디스플레이 구현이 가능하여 차세대 디스플레이로써 많은 이목을 끌고 있으나 제한된 수명과 안정성의 문제점을 안고 있다. 따라서 OLED의 열화 원인을 분석하고 수명을 연장하기 위한 체계적인 방법과 기술 개발이 중요하다. Impedance Spectroscopy는 이온, 반도체, 절연체 등의 벌크 또는 계면 영역의 전하 이동을 조사하는데 사용될 수 있어, OLED에서도 Impedance Spectroscopy를 이용하여 전하수송과 전자주입 메커니즘 등 폭넓은 전기적 정보를 얻을 수 있다. 본 연구에서는 Impedance Spectroscopy를 이용하여 경과시간에 따른 OLED의 임피던스 특성을 측정하여 열화 메커니즘을 분석하였다. 본 연구에서 OLED는 ITO / 2-TNATA (4,4,4-tris2-naphthylphenyl-aminotriphenylamine) / NPB (N,N'-bis-(1-naphyl)-N, N'-diphenyl-1,1'- biphenyl-4,4'-diamine) / Alq3 (tris(quinolin-8-olato) aluminum) / Liq / Al으로 구성된 녹색 형광 OLED를 제작하였다. OLED의 전계 발광 특성을 측정하기 위한 전원 인가장치로 Keithley 2400을 사용하여 전압과 전류를 인가하였고, 소자에서 발광된 휘도 및 발광 스펙트럼은 Photo Research사의 PR-650 Spectrascan을 사용하여 암실 환경에서 측정하였다. 임피던스 스펙트럼은 컴퓨터 제어 프로그래밍이 가능한 KEYSIGHT사의 E4990A를 사용하여 측정하였다. 임피던스 측정 전압은 0 V부터 2 V 간격으로 8 V까지, 주파수는 20 Hz에서 2 kHz의 범위로 설정하여 측정하였다. I-V-L과 임피던스 특성은 24 시간의 간격을 두고 실온에서 측정하였다. 그림은 경과시간에 따른 녹색 형광 OLED의 인가전압 2 V, 6 V의 Cole-Cole plot을 나타낸 것이다. 문턱전압 미만인 인가전압 2 V에서는 소자를 통하여 전류가 흐르지 않아 큰 반원 형태를 나타내었고, 시간이 경과함에 따라 소자 제작 직후엔 실수 임피던스의 최댓값이 $8982.6{\Omega}$에서 480 시간 경과 후엔 $9840{\Omega}$으로 약간 증가하였다. 문턱전압 이상인 인가전압 6 V에서는 소자 제작 직후 실수 임피던스의 최댓값이 $108.2{\Omega}$으로 작은 반원 형태를 나타내나 시간이 경과함에 따라 방사형으로 증가하는 것을 확인 할 수 있었고, 672 시간 경과 후엔 실수 임피던스의 최댓값이 $9126.9{\Omega}$으로 문턱 전압 미만 일 때와 유사한 결과를 나타내었다. 이러한 임피던스의 증가 현상은 시간이 경과함에 따라 OLED의 열화에 의한 것으로 판단된다.

• Journal of the Korean Vacuum Society
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• v.15 no.6
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• pp.587-593
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• 2006

The circuit of the EEFL system and the inverter has been analyzed into the resistance RL, the capacitance C of the EEFL-backlight system, and the inductance of transformer in the inverter. The lamp resistance and capacitance are deter-mined from the phase difference is between the lamp current and voltage and from the Q-V diagram, respectively. The single Lamp of EEFL for 32' LCD-BLU has the resistance of $66\;k\Omega$ and the capacitance of 21.61 pF. The resistance, which is connected by parallel in the 20-EEFLS BLU, is $3.3\;k\Omega$ and the capacitance is 402.1 pF. The matching frequency in the operation of lamp system is noted as $\omega_M=1/\sqrt{L_2C(1-k^2)}$, where $L_2$ is the inductance of secondary coil and k is the coupling coefficient between primary and secondary coil. The lamp current and voltage has maximum value at the matching frequency in the LCD BLU system. The results of analytic solutions are in good agreement with the experimental results.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.164.1-164.1
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• 2010

최근 에너지 절감과 환경 문제에 대한 관심이 커지면서 친환경적이고 에너지 효율이 높은 LED에 대한 관심이 대두되고 있으며, 국가 저탄소 녹색성장에 맞는 신성장동력산업의 하나로 LED가 선정되어 적극적으로 육성되고 있다. LED를 활용한 조명등은 현재까지 활발한 연구개발이 진행되었으며 백열전구를 능가하는 조명 효율을 확보하여 조명 광원으로서 이용되고 있다. 그런데 선박용 조명등의 경우에는 아직 관련 기술개발이 초기단계에 머물러있어 대부분의 선박들이 기존의 백열등 및 형광등과 같은 조명등을 사용하고 있다. 이러한 유리 조명등은 고소비전력과 제한된 수명에 따른 높은 유지비 및 제품 누수나 파손 등과 같은 안전성의 문제가 있다. 이에 따라 장기적인 관점에서 선박용 LED 조명 등에 대한 기술 개발이 필요할 것으로 보이며 기술 개발을 저해하는 요소인 방열, 가격 등에 대한 추가적인 기술개발이 뒷받침 되어야 할 것으로 보인다. 한국생산기술연구원에서는 부산광역시 지원사업의 일환으로 선박용 LED 조명등을 개발하고 있으며, 체계적인 연구를 위하여 선박용 LED 조명등의 요소기술에 대한 연구동향과 기술특성을 분석하고 있다. 본 논문에서는 선박용 LED 조명등 개발에서 요구되는 요소기술에 대한 기술개발동향을 살펴보고자 한다. 고효율의 선박용 LED 조명등 개발에 필요한 요소기술로는 방열, SMPS, 광학, 제품 내진동, 제품 방수 등의 설계 및 제작기술이 있다. 이러한 요소기술을 알아보고 선박용 LED 조명등 개발의 방향을 제시하고자 한다.