• Annual Conference of KIPS
• /
• 2003.11c
• /
• pp.1501-1504
• /
• 2003

네트워크 환경의 변화로 광전송로 관련 장비에 대한 투자가 증가하였다. 투자된 광전송로 장비를 효율적으로 관리하고 사용하기 위하여 광전송로 데이터에 대한 관리가 이루어져야 한다. 기존의 광전송로 데이터 관리 및 망 설계 작업 대부분은 일부 작업을 제외하고는 수작업에 의존하고 있었다. 이러한 작업 여건으로 효율적인 광전송로 데이터의 관리와 활용이 이루어지지 않아 많은 자원이 낭비되고 있는 실정이었다. 이러한 문제점을 해결하기 위해 본 연구에서는 효율적인 광전송로 데이터의 관리와 빠르고 정확한 망 설계를 지원하는 광전송로 틀과 광전송로 데이터를 관리, 저장하기 위한 데이터베이스를 설계하였다.

• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.32A no.11
• /
• pp.86-93
• /
• 1995

An optical transmitter was designed and implemented using a commercially available LiNbO$_{3}$ Mach-Zehnder modulator and the power amplifiers. We have adopted a new method to stabilize the bias voltage of the modulator using the second order harmonic component of the dithering signal. This technique has been applied successfully to the 2.5 Gbit/s external modulator for more than 6 hours without bit error rate degradaton. We demonstrated a repeaterless transmission of a 2.5 Gbit/s signal over 150 km nondispersion-shifted fiber using the transmitter. The receiver sensitivity was -34.5 dBm at 10$_{-10}$ bit error rate. No appreciable BER degradation due to fiber dispersion were observed after transmission.

• Journal of the Korean Institute of Telematics and Electronics S
• /
• v.34S no.5
• /
• pp.25-34
• /
• 1997

Relatively slow tuning speed of optical device causes the unwanted delay in high speed single-hop multiwavelength networks. To lessen the overhead, we present a channel access protocol with dynamjic message scheduling. Th eframe structure of proposed protocol adopts hybrid multiaccess scheme in which WDMA is used as a basic multiaccess technique and TDMA is used to provide subchannels within a wavelength band. This architecture has two merits : the network extention is not limited by available number of wavelengths, and the transmission delay caused by optical device tuning time can to minimize the number of tunings. It schedules messages that require same wavelength channels sequencely, so the total transmission delay is reduced by decreasement of wavelength changes. The performance of proposed protocol is evaluated through numerical analysis based on probability and queueing theory. The peformance of proposed protocol is evaluated through numerical analysis based on probability and queueing theory. The numeric results show that the peformance of proposed protocol is better than that of previous one.

• Journal of Ocean Engineering and Technology
• /
• v.32 no.2
• /
• pp.143-150
• /
• 2018

In this study, we designed and developed an underwater LED communication system composed of an LED and a photo sensor. In addition, we experimented with video data transmission in a water tank. Two communication modules were installed in the 3 m water tank, and the image data transmission test was successfully performed at a rate of 20 frames per second(FPS), image resolution of $480{\times}272$, and data communication speed of 4 Mbps.

• Journal of Sensor Science and Technology
• /
• v.29 no.2
• /
• pp.75-81
• /
• 2020

We introduce a new visible light communication (VLC) method in which three-level return-to-zero (RZ) modulation is used for flicker-free transmission. In the VLC transmitter, the three-level RZ modulation ensures that the average optical power is constant; thus, a flicker-free light-emitting diode (LED) light is achieved. In the VLC receiver, a resistor-capacitor high-pass filter is used for generating spike signals, which are used for data recovery while eliminating the 120 Hz optical noise from adjacent lighting lamps. In transmission experiments, we applied this method for wireless transmission of an air quality sensor message using the visible light of an LED array. This configuration is useful for the construction of indoor wireless sensor networks for air pollution monitoring using LED lights.

• Proceedings of the KIEE Conference
• /
• 2006.07d
• /
• pp.1901-1902
• /
• 2006

In recent years, it has been a worldwide trend that many power utilities gave their attention to develop and operate their power plants, substation and distribution systems. Following this trend, KEPCO(Korea Electric Power Corporation) has developed many electric automation systems with various communication networks. It has been natural that the automation systems are just focused on to remote devices when they come to be designed. But, we have to shift the focus to the automation system itself. We have developed the Multi-service Optical Transmission System (M-OTS) for electrical power systems. It can be adopt to not only distribution power field but also the transmission power field. The result strongly shows that the system is potentially beneficial in reliability, speed, and expandability. This paper presents some of initial design efforts and results toward a KEPCO's communication system in distribution areas.

• Proceedings of the Optical Society of Korea Conference
• /
• 2000.02a
• /
• pp.76-77
• /
• 2000

Very narrow transmission peaks are generated by the phase-shifted fiber Bragg grating with phase-shift region. The width of the transmission peaks are about ～0.5nm. The characteristics of multi-wavelength source using the phase-shifted fiber Bragg grating are designed and analyzed. The source with two and three transmission peaks is analyzed (omitted)

• Journal of the Optical Society of Korea
• /
• v.6 no.1
• /
• pp.13-17
• /
• 2002

We demonstrated 1.28-Tb/s (64 ch $\times$ 20 Gb/s) WDM transmission with 50-GHz channel spacing over 320 km of conventional single mode fibers. The spectral efficiency was 0.4 (bit/s)/Hz. Thus, we could accommodate all the sixty-four WDM channels within the C-band of EDFA The average Q-factor was measured to be better than 17.8 dB after transmission over 320 km.

• Proceedings of the KIEE Conference
• /
• 1994.07a
• /
• pp.91-93
• /
• 1994

Recently, for improving the power supply reliability and for rationslizing maintenance, new maintenance and monitoring systems are stornagly desired for use in the field of electric power transmission. In this paper, we describes the optical fault detecting method of underground power transmission lines using bareearth doped YIG Faraday sensors which are very light, small size and fast response. As regarding, we use the zero phase current detecting algorithm at insulated joints.

• ETRI Journal
• /
• v.29 no.1
• /
• pp.116-119
• /
• 2007

In this letter, we design a collision resolution protocol for optical burst switching ring networks to avoid burst collision. We define the offset time condition for no burst transmission collision and manage the free time list of nodes for no burst reception collision. In order to improve the throughput, we use a fiber delay line, void-filling, and void-compression. This protocol does not require any additional procedures for bandwidth reservation such as centralized assignment of bandwidth, lightpath setup of WDM ring networks, or token capturing for the burst transmission. The simulation results show that the proposed protocol can achieve high throughput while saving 70% of wavelengths when compared to round robin with random selection, round robin with persistent, and round robin with non-persistent with only destination delay.