• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.49 no.3
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• pp.208-217
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• 2013

Decoys for automatic jigging machines, the body part of a squid hook, have been developed in small and existing sizes in consideration of squid food, color blindness, and retinomotor responses and in utilization of pearl pigment, PP of high transparency, and combined mixture. In comparison of the developed silver-white decoy and existing decoys, the optical characteristics were examined, and the fishing performance of small size silver-white squid hooks was assessed in application of 4 fishing boats with the squid automatic jigging machine and metal halide fishing lamp in July, 2012. The luminances of the three squid hook colors-green, dark green and silver-white-increased as the intensity of illumination increased. Among these, the increase of silver-white was particularly distinguished. As to the average contrast of squid hooks, that of silver-white was 10.33, which was the highest, and then green 1.86 and dark green -0.10 in the order. As to the fishing performance of the silver-white hook, that of the 202 Geumyeong-ho and 101Yongjin-ho which caught squids were similar to that of the existing green hook and was relatively low in the case of the Dongbu-ho. However, that of the Haengbok-ho which caught relatively small squids whose average length was 19.9cm and installed silver-white hook in all automatic jigging machines was significantly excellent. In order to enhance the fishing performance of small size silver-white hooks, therefore, it would be effective to install in every automatic jigging machines of fishing boat and to start fishing before July by which small squids are caught.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.2
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• pp.116-122
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• 2012

The purpose of this study is to investigate the overall spray behavior characteristics for various injection conditions in a gasoline direct injection(GDI) injector with multi-hole. The spray characteristics, such as the spray penetration, the spray angle, and the injection quantity, were studied through the change of the injection pressure, the ambient pressure, and the energizing duration in a high-pressure chamber with a constant volume. The n-heptane with 99.5% purity was used as the test fuel. In a constant volume chamber, the injected spray was visualized by the spray visualization system, which consisted of the high-speed camera, the metal-halide lamp, the injector control device, and the image analysis system with the image processing program. It was revealed that the injection quantity was mainly affected by the difference between the injection pressure and the ambient pressure. For low injection pressure conditions, the injection quantity was decreased by the increase of the ambient pressure, while it nearly maintained regardless of the ambient pressure at high injection pressure. According to the increase of the ambient pressure in the constant volume chamber, the spray development became slow, consequently, the spray tip penetration decreased, and the spray area increased. In additions, the circular cone area decreased, and the vortex area increased.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.3
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• pp.259-265
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• 2013

The marine microalgae Nannochloropsis sp. was cultured under a metal halide lamp (MH) or light-emitting diodes (LEDs) of various wavelengths (blue, LB; red, LR; yellow, LY; green, LG; white, LW); changes in growth, total carotenoid, chlorophyll a, amino acid and fatty acid profiles were investigated. LB-exposed cultures exhibited the highest specific growth rate (SGR) (0.32), whereas LY-exposed cultures showed the lowest SGR (0.18). After cultivation for 9 days, the maximum dry cell weight (g/L) of LB-exposed cultures was significantly higher than that of those exposed to other light conditions (LB>MH>LW$${\geq_-}LG{\geq_-}$$LR>LY). The essential amino acid (EAA, %) contents of cultures exposed to LG, LB, LR and MH were higher than those exposed to LY and LW (P<0.05). Eicosapentaenoic acid and n-3 highly unsaturated fatty acid levels were significantly higher in MH-exposed cultures compared to those exposed to LY (P<0.05), with no marked difference compared to those exposed to LB, LG, LR and LW (P>0.05). The total carotenoid content was highest in LR-exposed cultures (18.0 mg/L), whereas MH showed the lowest (11.8 mg/L; P<0.05). Chlorophyll a content was highest in cultures exposed to LR compared to other light sources. These results suggest consistent differences in growth and biochemical composition after exposure to light of different wavelengths.

• Journal of Bio-Environment Control
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• v.17 no.2
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• pp.132-137
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• 2008

This experiment was conducted to investigate the effect of supplemental lighting of low light intensities on growth and yield of rose 'Vital' in a forcing culture. Metal halide lamp (MH), High pressure sodium lamp (HSP), and MH+HSP were used as the light sources, and they were set up at a $310\;cm{\times}450\;cm$ interval and at 120cm above the culture beds. Light intensity at 1m point distance from supplemental lighting sources was $32{\sim}34\;{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$. Days to the 1st and 2nd harvests decreased by $5{\sim}8$ and $3{\sim}5$days, respectively in supplemental lighting treatment as compared to the control. Days to harvesting was the shortest in MH+HPS treatment, followed by BPS and MH, although there was no significant difference between HPS and MH treatments. The growth was better and incidence of blind shooting decreased by $5{\sim}7%$ in supplemental lighting treatments than the control, increasing marketable cut flowers. The incidence of blind shoot was the lowest in MH+BPS treatment, and there were no significant difference between MH and BPS treatments. In conclusion, supplemental lighting of low light intensities was effective in reducing days to flowering and reduced occurrence of blind shoots.

• Korean Journal of Optics and Photonics
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• v.17 no.1
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• pp.81-88
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• 2006

Delayed luminescence from human hands after illumination by light at different wavelength bands was studied. A delayed luminescence measurement system equipped with photomultiplier tube (PMT), fiber optics and automatic mechanical shutter system was developed. Three spectrum band-pass filters, fer which transmissions are on 350${\~}$450 nm, 450${\~}$550 nm and 550${\~}$650 nm, were used to select irradiation wavelength, and 150W metal-halide lamp was used as an illumination source. Six volunteers put their palms (dorsa) onto the measurement system, and after light illumination, delayed luminescence were measured for 10 minutes. The results show that delayed luminescence after shorter wavelength illumination was higher than that a(ter longer wavelength one. These results indicate the existence of accepters in human skin which can be excited at short wavelengths. Furthermore, each subjects showed different delayed luminescence curve patterns. Reactive oxygen species (ROS) are known to have important roles on delayed luminescence, and this research suggests that ROS concentration can be measured noninvasively with optical methods.

• Korean Journal of Environmental Agriculture
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• v.34 no.1
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• pp.38-45
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• 2015

BACKGROUND: For commercial production of greenhouse crops under shorter day length condition, supplementary radiation has been usually achieved by the artificial light source with higher electric consumption such as high-pressure sodium, metal halide, or incandescent lamps. Light-Emitting Diodes (LEDs) with several characteristics, however, have been considered as a novel light source for plant production. Effects of supplementary lighting provided by the artificial light sources on growth of Kale seedlings during shorter day length were discussed in this experiment. METHODS AND RESULTS: Kale seedlings were grown under greenhouse under the three wave lamps (3 W), sodium lamps (Na), and red LEDs (peak at 630 nm) during six months, and leaf growth was observed at intervals of about 30 days after light exposure for 6 hours per day at sunrise and sunset. Photosynthetic photon flux (PPF) of supplementary red LEDs on the plant canopy was maintained at 0.1 (RL), 0.6 (RM), and $1.2(RH){\mu}mol/m^2/s$ PPF. PPF in 3 W and Na treatments was measured at $12{\mu}mol/m^2/s$. Natural light (NL) was considered as a control. Leaf fresh weight of the seedlings was more than 100% increased under the 3 W, Na and RH treatment compared to natural light considering as a conventional condition. Sugar synthesis in Kale leaves was significantly promoted by the RM or RH treatment. Leaf yield per $3.3m^2$ exposed by red LEDs of $1.2{\mu}mol/m^2/s$ PPF was 9% and 16% greater than in 3W or Na with a higher PPF, respectively. CONCLUSION: Growth of the leafy Kale seedlings were significantly affected by the supplementary radiation provided by three wave lamp, sodium lamp, and red LEDs with different light intensities during the shorter day length under greenhouse conditions. From this study, it was suggested that the leaf growth and secondary metabolism of Kale seedlings can be controlled by supplementary radiation using red LEDs of $1.2{\mu}mol/m^2/s$ PPF as well as three wave or sodium lamps in the experiment.

• Korean Journal of Environmental Agriculture
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• v.32 no.3
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• pp.193-200
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• 2013

BACKGROUND: Plant factory system of an artificial light type using Light-Emitting Diodes (LEDs), fluorescent light, or metal halide lamp instead of sun light is an ultimated method for plant production without any pesticides regardless of seasonal changes. The plant factory is also completely isolated from outside environmental conditions such as a light, temperature, or humidity compared to conventional greenhouse. Light-environment control such as a quality or quantity in the plant factory system is essential for improving the growth and development of plant species. However, there was little report that the effects of various light qualities provided by LEDs on Ledebouriella seseloides growth under the plant factory system. METHODS AND RESULTS: Ledebouriella seseloides seedlings transplanted at urethane sponge were grown in the plant factory system of a horizontal type with LED artificial lights for 90 days. Yamazaki solution for hydroponic culture of the seedlings was regularly irrigated by the deep flow technique (DFT) system on the culture gutters. Electrical Conductivity (EC) and pH of the solution was recorded at 1.4 ds/m and 5.8 in average, respectively during the experimental period. Number of unfolded leaves, leaf length, shoot fresh and dry weight of the seedlings were three times measured in every 30 days after beginning of the experiment. Blue LEDs, red LEDs, and fluorescent lights inside the plant factory were used as light sources. Conventional fluorescent lamps were considered as a control. In all the treatment, light intensity was maintained at $100{\mu}mol/m^2/s$ on the culture bed. Fresh weight of the seedlings was 3.7 times greater in the treatment with the mixture radiation of fluorescent light and blue+red LEDs (1:3 in energy ratio; Treatment FLBR13) than in fluorescent light treatment (Treatment FL). In FLBR13 treatment, dry weight per seedling was two times greater than in FL or BR11 treatment of blue+red LEDs (1:3 in energy ratio; Treatment BR11) during the culture period. Increasing in number of unfolded leaves was also significantly affected by the FLBR13 treatment comparing with BR11 treatment. CONCLUSION(S): Hydroponic culture of Ledebouriella seseloides seedlings was successfully achieved in the plant factory system with mixture lights of blue, red LEDs and fluorescent lights. Shoot growth of the seedlings was significantly promoted by the FLBR13 with the mixture radiation of fluorescent light, blue, and red LEDs under 1:3 mixture ratio of blue and red LEDs during the experimental period compared to conventional light conditions.

• Journal of Bio-Environment Control
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• v.27 no.4
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• pp.341-348
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• 2018

To investigate the effect of light sources on the growth and photosynthesis of the dwarf apple rootstock M.9 for the production of standard seedlings, the plants were cultivated in a controlled environment for 6 weeks. The sources of light are six treatments [Red (R), Blue (B), White (W), RBUV (R7B3 containing UV-A), RBW (R3B1W1), SMF (high pressure sodium + metal halide + fluorescent lamp) under $154{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$. Growth characteristics of apple seedlings varied depending on artificial light source at 3 weeks and 6 weeks. The plant height of apple seedling was high in the R, RBUV, RBW, and SMF light sources at 3 weeks, and in the R light at 6 weeks. There was no significant difference on stem diameter among the treatments at 3 weeks, but showed high in RBUV and RBW light at 6 weeks. Leaf number was the highest in RBUV light at 3 and 6 weeks. The chlorophyll content (SPAD value) was high in the B and RBUV light at 3 weeks, but it was not significant at 6 weeks. The growth rate to height of the R light (1.12mm/day) was the highest among the treatments, followed by RBUV, RBW, SMF, W and then B. Leaf area was the highest in RBUV and RBW lowest in B. Specific leaf area was high in W and fresh and dry weight were high in RBUV. The photosynthetic rate at 6 weeks was highest in the B and lowest in the R. Stomatal conductivity and transpiration rate were higher in the B and W compared to the other light sources. Therefore, we are considered that light sources for growth of dwarf apple rootstock M.9 seedlings are suitable the R, RBUV, and RBW light sources with a high mixing ratio of Red and Red +Blue.