• 대한전기학회:학술대회논문집
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• 대한전기학회 1987년도 정기총회 및 창립40주년기념 학술대회 학회본부
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• pp.484-485
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• 1987

The characteristics of leader development in rod -to- plane air gap (20cm gap length) under positive impulse potentials have been studied by means of 2-photomultiplier technique and image intensifier camera. It was shown that the streamers radiate relatively short wavelength light (${\sim}340nm$) while the leaders radiate a plenty of long wave length light ($400{\sim}800nm$). It was also known that the streamers propagate very fast with a velocity of $6{\times}l0^7cm/sec$ but the leaders have average velocity of $5{\times}10^6cm/sec$ and they proceed gradually fast by step-wise development.

• Journal of the Optical Society of Korea
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• 제3권2호
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• pp.51-54
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• 1999

A Nd:YLF laser has been actively mode-locked at the third-order harmonic cavity frequency using a lithium niobate phase modulator. Self-oscillating pulses of 14 ps duration, 1 GHz repetition rate, and 10mV average power at 1053 nm wavelength have been obtained. A 1GHz rf signal to drive a phase modulator was obtained by using 1GHz pulse train without rf synthesizer as a driver of an active mode locker.

• 약학회지
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• 제25권3호
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• pp.101-108
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• 1981

Quantitative determination of capsaicin in biological fluid was investigated. The pharmacokinetic study of capsaicin in rabbits was performed by high-pressure liquid chromatography, equipped with a microparticulate reversed-phase column and a fixed wavelength detector. Elution was carried out using methanolwater(70:30). It allows the quantitative determination at 8-400 ng level. When single dose of capsaicin(4mg/kg) was given to rabbits intravenously, the elimination phase was extremely short with average half-life to 17.35 minute. Urine excretion of capsaicin itself during first 2 hours after intravenous administration (4mg/kg) was 0.004-0.04% of the administered amount. The maximum plasma concentration of capsaicin after oral administration (300mg/kg) was $4{\times}10^{-7}$g/ml at 40 minutes. The $LD_{50}$ of capsaicin in mouse was 0.40mg/kg (i.v.) and 47.2 mg/kg (p.o.) which was determined by Litchfield and Wilcoxon's method, suggesting that the gastrointestinal absorption of capsaicin is poor.

• Journal of the Optical Society of Korea
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• 제18권5호
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• pp.466-471
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• 2014

An asynchronous optical packet-switching (AOPS) node with load-balancing capability can achieve better performance in reducing the high packet-loss ratio (PLR) and time delay caused by unbalanced traffic. This paper proposes a novel dynamic load-balancing algorithm for an AOPS node with limited buffer and without wavelength converters, and considering the data flow distribution and service levels. By calculating the occupancy state of the output ports, load state of the input ports, and priorities for data flow, the traffic is balanced accordingly. Simulations demonstrate that asynchronous variant data packets and output traffic can be automatically balanced according to service levels and the data flow distribution. A PLR of less than 0.01% can be achieved, as well as an average time delay of less than 0.46 ns.

• 통합자연과학논문집
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• 제2권2호
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• pp.82-85
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• 2009

Distributed Bragg reflector (DBR) porous silicon (PSi) was generated by an electrochemical etching a bragg structure into a silicon wafer through electrode current in aqueous ethanolic HF solution. DBR PSi exhibiting unique reflectivity was successfully obtained by an electrochemical etching of silicon wafer using square current waveform. The multilayered photonic crystals of DBR PSi exhibited the reflection of a specific wavelength with high reflectivity in the optical reflectivity spectrum. In this work, we have developed a method to create refractive index in Si substrate through intensity of an electric current. The electrochemical process allows for precise control of the structural properties of DBR PSi such as thickness of the porous layer, porosity, and average pore diameter. The number of reflection peak of DBR PSi and its pore size increased as the intensity of electric current increased. This might be a demonstration for the fabrication of specific reflectors or filters.

• 한국세라믹학회지
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• 제34권7호
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• pp.774-780
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• 1997

Porous low reflective coating films of SiO2.ZrO2 system were prepared from the mixed alkoxide solutions of Zr(O-nC3H7)4 and partially prehydrolyzed TEOS by the sol-gel method using the dip-coating technique. In the case of 90SiO2.10ZrO2 porous coating films with HCl and H2O content was 0.3 mole and 4 mole, 378 m2/g of the specific surface area, 0.254 cm3/g of total pore volume, 30-50$\AA$ of average pore diameter. The transmittance of 90SiO2.10ZrO2 porous coated films was 95.38% at the wavelength of 550 nm, compared with the parent glass, the transmittance was increased with 4.38%.

• ETRI Journal
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• 제34권3호
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• pp.319-329
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• 2012

Closed-loop transmit diversity is considered an important technique for improving the link budget in the third generation and future wireless communication standards. This paper proposes several transmit diversity algorithms suitable for small wireless terminals and presents performance assessment in terms of average signal-to-noise ratio (SNR) and outage improvement, convergence, and complexity of operations. The algorithms presented herein are verified using data from measured indoor channels with variable antenna spacing and the results explained using measured radiation patterns for a two-element array. It is shown that for a two-element array, the best among the proposed techniques provides SNR improvement of about 3 dB in a tightly spaced array (inter-element spacing of 0.1 wavelength at 2 GHz) typical of small wireless devices. Additionally, these techniques are shown to perform significantly better than a single antenna device in an indoor channel considering realistic values of latency and propagation errors.

• 한국광학회지
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• 제16권2호
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• pp.143-145
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• 2005

본 논문은 5.12-Tb/s(128 채널 ${\times} 43 Gb/s$) WDM 신호의 200 km 전송실험에 관한 것이다. 본 실험에서는 Medium Dispersion Fiber를 사용하여 0.8-(bits/s)/Hz의 스펙트럼 효율을 구현하였다. 전송 후 측정된 평균 Q-factor값은 15.2 dB이었다.

• 한국세라믹학회지
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• 제33권7호
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• pp.735-742
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• 1996

Antimony-doped Tin oxide (ATO) thin films were deposited on soda-lime glass substrates by DC magnetron sputtering technique. Effects of DC power film thickness and post heat-treatment on electrical conductivity of ATO film were investigated. Other properties of ATO film such as optical anti-chemical and wear properties were also reported in this work. The obtained ATO films showed electrical resistivities ranging from 5$\times$10-3 $\Omega$cm to 3$\times$10-3 $\Omega$cm with the average optical transparency above 80% in visible wavelength range and excel-lent anti-chemical properties where the electrical resistivity was not changed even after soaking the films in 1M HCl or 1M NaOH solution for 10 days. These properties were found to be related to the crystallinity of ATO film and the films having higher crystallinity showed better properties.

• 한국분말재료학회지
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• 제19권1호
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• pp.55-59
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• 2012

In this work, the silver nanoparticles have been synthesized by electrical explosion of wire in three liquid mediums: deionized water (DIW), polyvinylpyrrolidone (PVP) and sodium dodecyl benzene sulfonate (SDBS) solutions. Absorption in the UV-visible region of these suspensions was measured in the range of 300-800 nm. A surface plasmon peak was observed at ~400 nm in all suspensions in measured wavelength range. Particle size was analyzed by transmission electron microscope. It showed that the particles had nearly spherical shape in all samples. The average particle sizes prepared in DIW, PVP and SDBS solution were 37, 31 and 27 nm, respectively. Stability of the suspensions was estimated by multiple light scattering method. The presence of PVP and SDBS surfactants in the exploding medium resulted in enhanced stability of the silver suspensions.