• Journal of Microbiology and Biotechnology
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• v.29 no.9
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• pp.1453-1459
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• 2019

Zeaxanthin is an important pigment in the photo-protection mechanism of microalgae. However, zeaxanthin epoxidase, an enzyme involved in the accumulation and conversion of zeaxanthin, has not been extensively studied in microalgae. In this work, we report the expression pattern of zeaxanthin epoxidase in Dunaliella tertiolecta (DtZEP) at different light and diverse salinity conditions. To confirm the responsiveness to light conditions, the ZEP expression pattern was investigated in photoperiodic (16 h of light and 8 h of dark) and continuous (24 h of light and 0 h of dark) light conditions. mRNA expression levels in photoperiodic conditions fluctuated along with the light/dark cycle, whereas those in continuous light remained unchanged. In varying salinity conditions, the highest mRNA and protein levels were detected in cells cultured in 1.5 M NaCl, and ZEP expression levels in cells shifted from 0.6 M NaCl to 1.5 M NaCl increased gradually. These results show that mRNA expression of DtZEP responds rapidly to the light/dark cycle or increased salinity, whereas changes in protein synthesis do not occur within a short period. Taken together, we show that DtZEP gene expression responds rapidly to light irradiation and hyperosmotic stress. In addition, ZEP expression patterns in light or salinity conditions are similar to those of higher plants, even though the habitat of D. tertiolecta is different.

• Korean Journal of Agricultural and Forest Meteorology
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• v.5 no.3
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• pp.208-212
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• 2003

Extended light illumination by street lamp and automobile light has provoked problem in farmland. Night break was imposed by incandescent lamp (50∼60 lux) for 10 minutes every three hours during 12 hours dark period increased culm length compared to continuous dark of 12 hours, and decreased the number of grains per spike in rice. However, these characters were increased by 12 hours dark period with and without night break as compared to 9 hours continuous dark condition. Compared to 12 hours continuous dark condition, night break delayed heading by 9 and 26 days and 9 hours continuous dark condition delayed it by 47 and 41 days in Ilpumbyeo and Hwaseongbyeo, respectively. Night break increased stem length and node number, while decreased pods of soybean cultivar Hwanggeumkong. The stem length and node number were increased by 9 hours continuous dark condition compared to 12 hours dark condition with and without night break. Compared to 12 hours continuous dark rendition, night break delayed flowering by 4 days and to 9 hours continuous dark condition by 19 days.

• Journal of Korean Society of Water and Wastewater
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• v.29 no.3
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• pp.319-323
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• 2015

This study investigated the effects of the light conditions on the productivity of scenedesmus dimorphus in the continuous mass cultivation system. To compare the algal productivity according to the light conditions, S. dimorphus was cultivated continuously under the wide range of light intensity(200-600 PPFD) and various light wavelength(white light and red-blue mixed light). After 100 days of cultivation under the different light intensity, the productivity of S. dimorphus increased as light intensity decreased. So, the productivity was maximized as 100 mg/L/d when light intensity was 200 PPFD. In case of light wavelength, the productivity of S. dimorphus was enhanced about 20% with the white light compared to that of the red-blue mixed light. Consequently, the optimal light conditions for the continuous mass cultivation of S. dimorphus were 200 PPFD as light intensity and white light as light wavelength.

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.478-481
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• 2006

Energy is vital to global prosperity, yet dependence on fossil fuels as our primary energy source contributes to global climate change environmental degradation, and health problems. Hydrogen $(H_2)$ offers tremendous potential as a clean renewable energy currency. Hydrogen has the highest gravimetric energy density of any known fuel and is compatible with electrochemical and combustion processes for energy conversion without producing carbon-based emission that contribute to environmental pollution and climate change. Numerous methodologies have been developed for effective hydrogen production. Among them, the biological hydrogen production has gained attention, because hydrogen can be produced by cellular metabolismunder the presence of water and sunlight. The green alga Chlamydomonas reinhardtii is capable of sustained $H_2$ photoproduction when grown under sulfur deprived condition. Under sulfur deprived conditions, PSII and photosynthetic $O_2$ evolution are inactivated, resulting in shift from aerobic to anaerobic condition in the culture. After anaerobiosis, sulfur deprived algal cells induce a reversible hydrogenase and start to evolve $H_2$ gas in the light. According to above principle, we investigated the effect of induction parameters such as cell age, cell density. light intensity, and sulfate concentration under sulfur deprived condition We also developed continuous hydrogen production system by sulfate re-addition under sulfur deprived condition.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.8
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• pp.151-161
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• 2013

An active power factor correction (PFC) circuit is presented which employs a newly proposed input voltage sensor-less control technique operated in continuous conduction mode (CCM) and critical conduction mode (CRM). The conventional PFC circuit with input voltage sensor-less control technique degrades the power factor (PF) under the light load condition due to DCM operation. In the proposed PFC circuit, the switching frequency is basically 70KHz in CCM operation. In light load condition, however, the PFC circuit operates in CRM and the switching frequency is increased up to 200KHz. So CCM/CRM operation of the PFC circuit alleviates the decreasing of the PF in light load condition. The proposed PFC controller IC has been implemented in a $0.35{\mu}m$ BCDMOS process and a 240W PFC prototype is built. Experimental results shows the PF of the proposed PFC circuit is improved up to 10% from the one employing the conventional CCM/DCM dual mode control technique. Also, the PF is improved up to 4% in the light load condition of the IEC 61000-3-2 Class D specifications.

• Current Photovoltaic Research
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• v.6 no.3
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• pp.69-73
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• 2018

PV system is consisted with PV module, inverter and BOS(balance of system). To have robustic operation more than 20 years, the expected and guaranteed durability and reliability of products should be met. Almost components of PV system are qualified through IEC standards at test laboratory. But the qualification certificate of product does not ensure long-term nondefective operation. PV module's expected life time is nowadays more than 20 years and annual maximum power degradation ratio would be less than -1%. But the power degradation ratio is basically based on real data more than several years' record. Developing test method for ensuring annual maximum power degradation ratio is very need because there are many new products every month with new materials. In this paper, we have suggested new test method under continuous artificial light irradiation test condition for analyze expected maximum power drop ratio.

• Natural Product Sciences
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• v.2 no.2
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• pp.90-95
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• 1996

When reserpine-producing cell strains of Rauwolfia serpentina were transferred from the dark to the light irradiation, the production of reserpine was extremely enhanced whereas the cell growth was suppressed. In an incubation period of 20 days, the most effective culture condition for reserpine production was the combination of 8 days of dark culture and following 12 days of light culture. The time courses of both cell growth and reserpine production were measured in vitro in order to clarify the effect of wave length range of light on the biosynthesis of reserpine. Although the growth of cultured cells which had been incubated under continuous red, yellow, and green lights, respectively, was similar to that of the cultured cells subcultured in the dark. The cells cultured under red light irradiation produced less reserpine than dark-grown cultures. Both blue and near-ultraviolet light inhibited the growth of cultured cells. The production of reserpine was strikingly enhanced by blue light, but was strongly inhibited by near-ultraviolet light.

• Transactions of the Korean Society of Automotive Engineers
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• v.25 no.1
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• pp.111-115
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• 2017

This forged piston is proposed with a lighter weight and higher durability than a gravity casting piston for gasoline engines. However, a forged piston is very difficult to develop and mass-produce due to lack of basic technologies such as design, material and forging technique. First, we benchmarked existing forged pistons according to database design parameters. Second, we evaluated two solidification processes, continuous casting and spray forming, to produce heat-resistant alloy billets for forging. The spray forming process gives better mechanical properties at all temperatures, particularly at elevated temperatures except when poor formability is present. We used DEFORM simulation to determine the optimum process condition with billet from spray forming and successfully commercialized it with LF Sonata HEV.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.655-659
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• 2001

Resident time of the continuous and Instantaneous centrifugal separator using that separates the light and heavy liquids by use of density difference is the orptical factor that affects significantly the chemical metial extraction and the productivity in the chemical and mechanical process. In this paper, the overflow of the device is investigated under consideration of the relationships between inclination angle of liquid feeding screw and the centrifugal force. From the design of the length of a centrifugal separator, the radiuses of rotor and housing, theoretical formulation on the contact radius of separation weir is established through the experiments. From the experiments, it is identified that how much the capacity of inlet impeller and the emulsion phenomenon depend on the screw angle of inlet impeller. Also, we investigate the separation condition and the resident times that are functions of the phase ratio and density.

• Journal of Industrial Technology
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• v.15
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• pp.5-13
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• 1995

Natural gas, which is getting more important as a fuel, should be liquefied and shipped in a special tank. During transportation, a spill of liquefied natural gas(LNG) could occur by a collision or even an accident. As a result, violent explosion called the superheat-limit explosion(SLE) can take place in some cases, unexpectedly. Such explosion may result from the formation of a superheated liquid which has attained the superheat-limit temperature when hot(water) and cold(LNG) liquids come into contact. Natural gas mixtures can be considered as discrete light components plus continuous heavy fractions where several continuous distribution function can be adopted. This work is aiming at prediction of the superheat-limit explosion condition by suing continuous thermodynamics development of algorithm to predict.