• Tribology and Lubricants
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• v.21 no.6
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• pp.268-271
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• 2005

In this study, the wear characteristics of five different dental composite resins cured by conventional halogen light and LED light sources were investigated. Five different dental composite resins of Surefil, Z100, Dyract AP, Fuji II LC and Compoglass were worn against a zirconia ceramic ball using a pin-on-disk type wear tester with 15N contact force in a reciprocal sliding motion of sliding distance of 10mm/cycle at 1Hz under the room temperature dry condition. The wear variations of dental composite resins were linearly increased as the number of cycles increased. It was observed that the wear resistances of these specimens were in the order of Dyract AP > Surefil > Compoglass > Z100 > Fuji II LC. On the morphological observations by SEM, the large crack formation on the sliding track of Fuji II LC specimen was the greatest among all resin composites. Dyract AP showed less wear with few surface damage. There is no significant difference in wear performance between conventional halogen light curing and light emitting diodes curing sources. It indicates that a light emitting diodes (LED) source can replace a halogen light source as curing unit for composite resin restorations.

• Proceedings of the Ginseng society Conference
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• 1980.09a
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• pp.151-170
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• 1980

Physiological response of Panax ginseng var. atropurpureacaulo (purple stem variety, Pg) to light was reviewed through old literatures and recent experiments. Canopy structure, growth, pigment, leaf anatomy, disease occurence, transpiration, photosynthesis (PS), leaf saponin, photoperiodism and nutrient uptake were concerned. P. ginseng var. xanthocarpus (yellow berry variety, Px) and Panax quinquefolius(Pq) were compared with Pg if possible. Compensation point(Cp) increased with increase of light and ranged from 110 to 150 at $20^{\circ}C$ but from 140 to 220 at $30^{\circ}C$ with 4 to 15 Klux indicating occurence of light and temperature-dependent high photorespiration. Characteristics of Korea ginseng to hate high temperature was well accordance with an observation 2000 years ago. Korea ginseng showed lower Cp and appeared to be more tolerant to high light intensity and temperature than American sheng although the latter showed greater PS, stomata frequency and conductance, chlorophyll and carotenoids. Px showed lower PS than Pg probably due to higher Cp. Total leaf saponin was higher in leaves grown under high light. Ratio or diol saponin and triol saponin(PT/PD) decreased with increase of light intensity during growing mainly due to decrease of ginsenoside $Rg_1$ but increase of ginsenoside Rd. Leaves of Pg and Px had $Rg_1$ but no $Rb_3$ which was only found as much as $20\%$ of total in Pq leaves, and decreased with increase of light intensity. Re increased in Pg and Px but decreased in Pq with increase of light. PT/PD in leaf ranged 1.0-1.5 in Pg and Px but around 0.5 in Pq. Korea ginseng has Yang characteristics(tolerant to high light and temperature), cultured under Eum(shade) condition and long been used for Yang efficacy (to build up energy) while Pq was quite contrary. Traditional low light $intensity(3-8\%)$ for Korea ginseng culture appeared to be strongly related to historical unique quality. Effect of light quality and photoperiodism was not well known. Experiences are long but scientific knowledge is short for production and quality assessment of ginseng. Recent scientific knowledge of ginseng should learn wisdom from old experiences.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.860-863
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• 2005

Dynamic model of the Korea standardized rubber-tired AGT light rail vehicle, and boundary conditions between vehicle and infrastructures (running track, guidance rail) were defined to analyze vehicular vibration behaviors occurred at the worst condition. Using the commercialized software RecurDyn, vibration accelerations of car body and bogies were analyzed. Based on the Korea performance test criteria for urban transit, vertical and lateral vibration of car body were calculated and evaluated. As the results, the Korea standardized rubber-tired AGT light rail vehicle satisfied the performance criteria and design requirement.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1990.11a
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• pp.58-62
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• 1990

The size and concentration of wear debris in lubricating oil often reveal the operating condition of the rotating machinery. To evaluate the possible application of light attenuation measurement for the estimation of wear debris concentration in the lubricating oil, the light transmittance through the lubricating oil cell contaminated with various concentrations of diatomite particles was measured, the attenuation coefficient was estimated from the transmittance measurement and the coefficients were compared with those obtained from the scattering theory. The comparision showed good agreements between them. It is also noted that the experimentally determined attenuation coefficient showed almost linear relation with particle weight concentrations for the concentrations within the range of 2000 ppm. For the case of 0 ppm weight concentration of diatomite particles in the lubricating oil cell, the thickness of the cell required to give $100 \mu W$ light attenuation is 7.75 mm. This result indicates that the light attenuation method will be one of the possible candidates of machine failure diagnostic sensors for the estimation of wear debris concentration in the lubricating oil.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.5
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• pp.312-316
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• 2014

Photoemission is a process in which photons are converted into free electrons. Photocathodes are the typical materials for the process. They emit electrons when a light is irradiated upon. The traditional method of manufacturing photocathodes is complicated, requires specialized equipment, and is limited very small sized samples. $Cs_3Sb$ photocathode was formed on a substrate in $N_2$ atmospheric conditions. The photocathode formation was a gas phase reaction with the substrate. Vacuum devices were made to test electron emission characteristics of the formed photocathode. Visible light of wavelength 475 nm was used for the primary light source. The results showed high current density and long term stability of the photoelectron emission.

• Journal of Microbiology and Biotechnology
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• v.16 no.3
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• pp.381-385
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• 2006

The production of astaxanthin by Xanthophyllomyces dendrorhous mutant depended on the culture conditions. Therefore, a cultivation strategy, including effective chemical and light induction, for the high-level production of astaxanthin by X. dendrorhous mutant JH1 was explored. Effective chemicals such as ethanol, acetic acid, and hydrogen peroxide, which are known inducers or precursors of astaxanthin synthesis, were investigated for their increase of astaxanthin production. Each of 1.0% ethanol, 1.0% acetic acid, and 1.0% hydrogen peroxide increased the astaxanthin concentration to 49.77 mg/l, 46.33 mg/l, and 45.61 mg/l, respectively. Among these chemicals, 1.0% ethanol showed the best effect on increasing astaxanthin concentration after 48 h of cultivation. Under 1.0% ethanol feeding condition, high light intensity (2,400 lux) stimulated astaxanthin production to 59.67 mg/l, compared with that in the dark-grown cultivation.

• Journal of the Korean Professional Engineers Association
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• v.42 no.5
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• pp.41-45
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• 2009

The last century of lighting has been dominated by incandescent, fluorescent and high-intensity discharge(HID)light sources. In the late 1970's, after green LEDs were invented, Dr. Ching Tang at Eastman Kodak discovered that sending an electrical impulse through carbon compound caused such material glow. Present day LED commercial packages have reached 100 lm/W, comparable to the efficacies of fluorescent and certain HID lamps. LED products available today are market as "Green-Industry" but actually low light output compared to typical light sources. The combination of high price and low light output make them a poor replacement for current technology. It is very important to compare new LED products to the most efficient conventional technology that could be used for any specific application. As LED technology advances, costs decrease, and efficiency improves, LEDs will build market share in the general illumination market.

• Tribology and Lubricants
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• v.6 no.2
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• pp.94-98
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• 1990

The size and concentration of wear debris in lubricating oil often reveal the operating condition of the rotating machinery. To evaluate the possible application of light attenuation measurement for the estimation of wear debris concentration in the lubricating oil, the light transmittance through the lubricating oil cell contaminated with various concentrations of diatomire particles was measured, the attenuation coefficient was estimated from the transmittance measurement and the coefficients were compared with those obtained from the scattering theory. The comparision showed good agreements between them. It is also noted that the experimentally determined attenuation coefficient showed almost linear relation with particle weight coucentrations for the concentrations within the range of 2000 ppm. For the case of 0 ppm weight concentration of diatomire particles in the lubricating oil cell, the thickness of the cell required to give $100 \muW$ light attenuation is 7.75 mm. This result indicates that the light attenuation method will be one of the possible candidates of machine failure diagnostic sensors for the estimation of wear debris concentration in the lubricating oil.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.28A no.11
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• pp.894-901
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• 1991

Contact-type linear image sensors have been fabricated by means of RF glow discharge decomposition method of silane and hydrogen mixtures. The dependences of the electrical and optical properties of these sensor on thickness, RF power, substrate temperature and ambient gas pressure have been investigated. the ITO/i-a-Si:H/Al structure film shows photosensitivity of 0.85 and photocurrent to dark current ratio ($I_{ph}/I_{d}$) of 150 at 5V bias voltage under 200${\mu}W/cm^[2}$ red light intensity. Under 200${\mu}W/cm^[2}$ green light intensity, the ratio is 100. In order to investigate photocarrier transport mechanism and to obtain ${\mu}{\gamma}$ product we have measured the I-V characteristics of these sensors favricated with several different deposition parameters under various light sources. The linear inage sensor for document reading has been operated under reverse bias condition with green light source, resulting in ${\mu}{\gamma}$ product of about 1.5$[\times}10^{-9}cm^{2}$/V.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.637-638
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• 2008

In this paper, we describe a new guard lamp and traffic light controller using Zigbee one of near field communication. It can control guard lamp and traffic light system by wireless system. Also, it can definite in the sever system New guard lamp and traffic light using zibee system improved for waste power, an accident and management condition.