• Journal of Biosystems Engineering
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• v.28 no.2
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• pp.151-156
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• 2003

This study was performed to investigate the effect of light quality on evapotranspiration and graft-taking characteristics of watermelon grafted seedlings using blue, red and far-red light-emitting diodes (LED). At initial stage of graft-taking, blue light increased the evapotranspiration rate (EVTR) of grafted seedlings as compared to effects of red and far-red on EVTR of grafted seedlings. Grafted seedlings graft-taken under red and blue LED showed the high graft-taking of 100% and 96%, respectively. However, grafted seedlings graft-taken under far-red LED showed the graft-taking of 80% and survival of 60% with low seedlings quality after hardening. The stem of grafted seedlings graft-taken under red light was elongated but blue light suppressed the stem elongation. The leaf area of grafted seedlings graft-taken under red light was increased. It is concluded that the effect of light quality using LED on graft-taking of watermelon grafted seedlings was significantly recognized. Considering the duration of quality of grafted seedlings graft-taken under artificial lighting, LED could be used as an effective lighting sources to validate the continuance of seedling quality.

• Journal of Applied Biological Chemistry
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• v.55 no.4
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• pp.273-275
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• 2012

The attraction effects of light emitting diode (LED) trap to Spodoptera exigua adults were evaluated in greenhouse and compared with those of no light trap and black-light trap, which is typical used in commercial trap. 7 days later, white LED trap ($83.0{\pm}0.7$) was 2.4 times more attractive than black-light trap ($34.0{\pm}2.6$), whereas the no light trap was little attractive to S. exigua. These results suggest that white LED traps could be used for environmental insect control.

• IEIE Transactions on Smart Processing and Computing
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• v.3 no.4
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• pp.226-233
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• 2014

This paper presents an external light evasion method that rectifies the problem of misrecognition due to external lighting. The fundamental concept underlying the proposed method involves recognition of the differences between two images and elimination of the desynchronized external light by synchronizing the image sensor and inner light source of the optical touch screen. A range of artificial indoor light sources and natural sunlight are assessed. The proposed system synchronizes with a Vertical Synchronization (VSYNC) signal and the light source drive signal of the image sensor. Therefore, it can display synchronized light of the acquired image through the image sensor and remove external light that is not from the light source. A subtraction operation is used to find the differences and the absolute value of the result is utilized; hence, the order is irrelevant. The resulting image, which displays only a touched blob on the touchscreen, was created after image processing for coordination recognition and was then supplied to a coordination extraction algorithm.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.4
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• pp.30-35
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• 2020

The light guide plate (LGP) provides a surface light source on the back of the liquid crystal display (LCD), which is not self-emitting; thus, it is an essential component of display units requiring sufficient brightness. To maximize the light-emitting effect of an LGP, enough incident light, from the light source, should enter into its side. However, the current trend in LCD panels is represented by larger and thinner screens and this smaller thickness prevents the accordingly thin LGPs from providing sufficient brightness. This paper proposes a process for manufacturing wedge-type LGPs, which might increase the amount of incident light and, consequently the surface light emission, for applications in large LCDs. The proposed method was validated by building a dedicated manufacturing machine and performing illuminance experiments on the fabricated LGP.

• Journal of Korean Society of Transportation
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• v.21 no.6
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• pp.67-73
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• 2003

This study preformed a research about the traffic signal light that is adding supplementary green light to prevent driver's cognitive errors and plan safe driving through improving visual cognitivity of present traffic signal light. The result of comparing the present traffic signal light(three colors, four colors) with the traffic signal light(three colors, four colors) adding supplementary green light through car simulator has a significant difference. This result shows possibility that the traffic signal light adding supplementary green light can contribute in safety driving at a point that the traffic signal light advances a point of braking time when drivers didn't recognize by themselves. The findings in this study ca say that there is the meaning in showing a actual application possibility of this study finding by investigating a action of subjective response the moment compare driver's actual response.

• Proceedings of the KIEE Conference
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• 2007.04a
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• pp.73-76
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• 2007

Photodynamic diagnosis(PDD) is a method to diagnose the possibility of cancer, both by the principle that if a photosensitizer is injected into an organic tissue, it is accumulated in the tissue of a malignant tumor selectively after a specific period, and by a comparison of the intensity of the fluorescence of normal tissue with abnormal tissue after investigating the excitation light of a tissue with accumulated photosensitizer. Since the selection of the wavelength band of excitation light has an interrelation with fluorescence generation according to the selection of a photosencitizer, it plays an important role in POD. This study aims at designing and evaluating light source devices that can stably generate light with various kinds of wavelengths In order to make possible PDD using a photosensitizer and diagnosis using auto-fluorescence. The light source device was a Xenon lamp and filter wheel, composed of an optical output control through Iris and filters with several wavelength bands It also makes the inducement of auto-fluorescence possible because it is designed to generate a wavelength band of 380-400. The transmission part of the light source was, developed to enhance the efficiency of light transmission. To evaluate this light source device, the characteristics of the light output and wavelength band were verified. To validate the capability of this device as PDD the detection of auto-fluorescence using mouse was performed.

• Journal of Acupuncture Research
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• v.32 no.3
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• pp.211-220
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• 2015

Objectives : We report two cases of pressure ulcer patients to show the efficacy of treatment with acupuncture and Light Enitting Diode(LED) light therapy. Methods : We treated two pressure ulcer patients with acupuncture, LED light therapy, herbal medication and with a simple dressing. LED light with up to $4J/cm^2$ of energy irradiated the pressure ulcer site once a day for fifteen minutes. All patients received acupuncture treatment and simple dressing for wound care. We measured phase change of the pressure ulcer in terms of ulcer size, The National Pressure Ulcer Advisory Panel(NPUAP) stage and with the The Pressure Ulcer Scale for Healing(PUSH) tool(3.0). Results & Conclusions : In each of the two cases, pressure ulcer size and total score of the PUSH tool decreased and NPUAP stage was improved from II to I. This shows that acupuncture treatment and LED light therapy may have a considerable effect in healing on the pressure ulcer.

• KSBB Journal
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• v.28 no.3
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• pp.170-176
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• 2013

The purpose of this study was to determine optimum condition of Pavlova lutheri and Phaeodactylum tricornutum. Detailed studies were carried out on the effects of various wavelengths of light-emitting diodes (LEDs), light intensities and air flow rations. For the Pa. lutheri, cell growth rates and maximum cell concentrations were similar regardless of wavelengths and air flow rates. Among the different light intensities, cell concentration increased when light intensity of red LED increased. For Ph. tricornutum, red LED was found to be the most effective light source, and light intensity of 3,100 Lux resulted in the most effective for the cultivation of Ph. tricornutum. Different air flow rates were tested to overcome shading effects due to denser cell concentration in the solution. Aeration of 0.8 vvm was determined to be the optimum aeration rate for the cultivation of Ph. tricornutum. Especially, five and two times greater cell concentrations of Pa. lutheri and Ph. tricornutum, respectively, were observed when air was applied.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.1
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• pp.296-305
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• 2012

In this paper, we develop about glare phenomenon at security light caused by light source's straight characteristic, maintaining uniformity ratio of illuminance as high, have long light distribution not by symmetry of rotation but a single axis. we develop second lens for security light that lack of light distribution phenomenon at each of security light can be solved. Our developed light system design satisfies lighting standard of security light's and shape of lens is single lens. so our lens optimizes designing or analysis by using lighting design and interpretation program. Making a Mock-up to do real measure, we have intensity of illumination and maintaining uniformity ratio of illuminance measurement data.

• Proceedings of the KIEE Conference
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• 1999.11d
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• pp.997-999
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• 1999

We fabricated white light-emitting organic electroluminescent device which have a mixed single emitting layer containing poly(N-vinylcarbazole)[PVK], tris(8-hydroxyquinoline)aluminum[Alq3] and poly(3-hexylthiophene)[P3HT] and investigated the emission properties of it. We expect to obtain a blue light from PVK, green light from Alq3 and red light from P3HT The fabricated device emits white light over 18V with slight orange light. We think that the energy transfer in a mixed layer occurred from PVK to $Alq_3$ and P3HT resulted in decreasing the blue light intensity from PVK. With mixing of N, N'-diphenyl-N, N'-(3-methylphenyl)-[1,1'-biphenyl]-4, 4'-diamine[TPD], hole transport material, to the emitting layer, the luminance intensity of device was increased 50 times than that of the device which not contain TPD. We find that the efficiency of the white light electroluminescent device can be improved by injecting electron more effectively and blue light need to improve the color purity of white light.