• 한국통신학회논문지
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• 제30권7A호
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• pp.542-549
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• 2005

In this paper, the optimal pump light power of optical phase conjugator (OPC) and the compensation characteristics of distorted WDM channel signals are numerically investigated, when the OPC with highly-nonlinear dispersion shifted fiber (HNL-DSF) not be placed at the mid-way of total transmission length. The total dispersion of former half section and latter half section is assumed to be same each other in this approach. It is confirmed that, in WDM transmission systems with OPC deviated from the mid-way, the pump light power for best compensation must be flexible selected depending on the OPC position. This optimal pump light power is gradually increased as the OPC is gradually closer to the receiver. Consequently, it is possible to establish the compensation system independent on the OPC position by setting optimal pump light power connected with the OPC position.

• 한국기계가공학회지
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• 제21권1호
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• pp.95-101
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• 2022

This paper proposes a method to process the shape of an optical transmission road and attempts to determine the most suitable single processing method for an acrylic plate optical transmission road. In addition, by manufacturing an automatic pattern processing device to generate certain shapes on the acrylic plate at regular intervals, and measuring the illuminance of the patterned acrylic plate optical transmission road, the measured illuminance was confirmed to fall under the KS illuminance values presented in Table 1. In conclusion, when an incident light of approximately 20,000 lx is applied, the transmission illumination is approximately 200 lx, which represents a transmission rate of approximately 1% for incident light and corresponds to the KS illumination criterion F. Additionally, the right-angle triangular pyramid base size (A) processed at a temperature of 350 ℃ for one second was 2 mm, exhibiting the largest transmission illumination of 280 lx. When the transparent acrylic plate was set to a constant size of 1.6 mm at the bottom of the right-angle triangular pyramid, the fastest response occurred at a processing tip temperature of 350 ℃ (0.04 s). On the other hand, it took 10 s to process the size of the bottom of the right-angled triangular pyramid at a temperature of 200 ℃ to 1.6 mm, and it was confirmed that the optical transmission efficiency was significantly reduced because of the burr that occurred at this time.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.935-938
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• 2004

We have studied several light guide concepts for light-valve projection engines. The aim of the light guide is to replace the array of lenses and mirrors in conventional transmission-type projection engines. Volume, cost and weight can be reduced, at a similar or better performance level. Results of a first prototype are discussed.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 심포지엄 논문집 정보 및 제어부문
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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.

• 한국입자에어로졸학회지
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• 제12권1호
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• pp.21-26
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• 2016

In order to realize In-line and convenient measurement for solid-gas two phase flows, Light Transmission Fluctuation (LTF) based on the random variation of transmitted light intensity, light scattering theory and cross-correlation method was presented for online measurement of particle size, concentration and velocity. The statistical relationship among transmitted light intensity, particle size and particle number in measurement zone was described by Beer-Lambert Law. Accordingly, the particle size and concentration were determined from the fluctuation signal of transmitted light intensity. Simultaneously, the particle velocity was calculated by cross-correlation analysis of two neighboring light beams. By considering the influence of concentration variation in industrial applications, the improved algorithm based on spectral analysis of transmitted light intensity was proposed to improve measurement accuracy and stability. Therefore, the online measurement system based on LTF was developed and applied to measure pulverized coal in power station and raw material in cement plant. The particle size, concentration and velocity of powder were monitored in real-time. It can provide important references for optimal control, energy saving and emission reduction of energy-intensive industries.

• Journal of the Korean Physical Society
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• 제73권11호
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• pp.1698-1702
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• 2018

We simulate the light transmission through an extremely small nanoscale aperture having a 10 nm diameter punctured in a metal film positioned at the center of a plasmonic bull's eye grating. A considerable directive emission of transmitted light with a divergence angle of 5.7 degrees was observed at $10{\mu}m$ from the nanohole opening at the frequency of surface plasmon polariton excitation, an confirmed by measuring the distance dependent transmission amplitude. Observations of the electric field in cross-sectional, near-field, and far-field views near-field enhancement associated with the surface plasmon excitation, and the interference of the electric field light through the nanohole in the near-field region is responsible for such a considerable directive emission.

• 센서학회지
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• 제25권3호
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• pp.189-195
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• 2016

In this paper, we newly introduce a visible light communication (VLC) repeater using the LED array in an LED lamp. The LED array is used for a light source in the repeater, which radiates light both for illumination and data transmission. A VLC repeater is made by adding some electronic circuits to the LED array including a photodetector, a demodulator, and a modulator. The repeater is installed on the ceiling of a room like a conventional LED lamp, receives the VLC signal from an arbitrary transmitter, recovers data, and radiates the signal to wide area in the room. We used a carrier frequency of 100 kHz for the uplink from a transmitter to the repeater, and 500 kHz for the downlink from the repeater to a receiver. The repeater is useful for increasing the transmission path to wide area over the obstacles that may exist between VLC transmitters and receivers.

• 한국위성정보통신학회논문지
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• 제8권2호
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• pp.44-49
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• 2013

LED 통신은 LED(Light Emitting Diode)에서 나오는 가시광선을 이용해 정보를 전송하는 무선통신기술로 RF(Radio Frequency) 통신의 문제점인 주파수 할당, 인체 내 유해성, 보안의 취약성, 전자기기 간 간섭 등을 극복할 수 있는 기술이다. LED를 이용하여 조명과 통신을 동시에 사용할 수 있는 융합 기술로 유비쿼터스 환경에 적합하다. 본 논문에서는 LED, PD(Photodiode) 및 MCU(Micro Controller Unit)를 이용한 LED 통신 시스템의 데이터 전송 알고리즘을 개발하였고 구현하는 과정을 소개한다.

• Restorative Dentistry and Endodontics
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• 제43권3호
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• pp.27.1-27.9
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• 2018

Objectives: The aim of this in vitro study was to evaluate the effects of the thickness and shade of 3 types of computer-aided design/computer-aided manufacturing (CAD/CAM) materials. Materials and Methods: A total of 120 specimens of 2 shades (A1 and A3) and 2 thicknesses (1 and 2 mm) were fabricated using VITA Mark II (VM; VITA Zahnfabrik), IPS e.max CAD (IE; IvoclarVivadent), and VITA Suprinity (VS; VITA Zahnfabrik) (n = 10 per subgroup). The amount of light transmission through the ceramic specimens was measured by a radiometer (Optilux, Kerr). Light-cured resin cement samples (Choice 2, Bisco) were fabricated in a Teflon mold and activated through the various ceramics with different shades and thicknesses using an LED unit (Bluephase, IvoclarVivadent). In the control group, the resin cement sample was directly light-cured without any ceramic. Vickers microhardness indentations were made on the resin surfaces (KoopaPazhoohesh) after 24 hours of dark storage in a $37^{\circ}C$ incubator. Data were analyzed using analysis of variance followed by the Tukey post hoc test (${\alpha}=0.05$). Results: Ceramic thickness and shade had significant effects on light transmission and the microhardness of all specimens (p < 0.05). The mean values of light transmittance and microhardness of the resin cement in the VM group were significantly higher than those observed in the IE and VS groups. The lowest microhardness was observed in the VS group, due to the lowest level of light transmission (p < 0.05). Conclusion: Greater thickness and darker shades of the 3 types of CAD/CAM ceramics significantly decreased the microhardness of the underlying resin cement.

• 한국환경과학회지
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• 제28권5호
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• pp.521-526
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• 2019

In this study, a solar light collector that collects and transmits solar light required for crop production in a closed plant production system was developed. The solar light collector consisted of a Fresnel lens for collecting solar light, and a tracking actuator for tracking solar light from sunrise to sunset to increase the light collection efficiency. The optical fiber that transmitted solar light was made of Glass Optical Fiber (GOF), and it had an excellent optical transmission rate. After collecting the solar light, the amount of light was measured at 5, 10, 15, 20, 25, and 30 cm distances from the GOF through the darkroom by using a light sensor logger connected to a quantum and pyranometer sensor. Compared with solar light, the light intensity of pyranometer sensor measured at 5 cm was 114% higher than solar light, and 61% at 10 cm. In addition, it was observed that it is possible to transmit the necessary amount of light for growing crops up to about 15 cm (as over 22%) through GOF. Therefore, adding diffusers to the solar light collector should be expected to replace artificial light in plant factories or plug seedlings nurseries for leafy vegetables. More studies on the solar light collection devices and the light transmission devices that have high light collection efficiency should be conducted.