• Korean Journal of Optics and Photonics
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• v.20 no.5
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• pp.276-280
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• 2009

A Cr:YAG crystal was used as a saturable absorber for passive Q-switching of a Nd:$YVO_4$ laser which was pumped by a 1-W continuous wave laser diode. The first surface of the Cr:YAG was high-reflection coated for the pump wavelength. The high-reflection coating improved the absorption efficiency of the pump beam in the Nd:$YVO_4$ through double pass absorption. It also prevented pump beam induced partial bleaching of the Cr:YAG. The peak-to-peak pulse fluctuation of passively Q-switched laser output was approximately 4 %. The minimum pulse-width was measured to be 7.11 ns. Also, the average pulse repetition rate was 9 kHz and the maximum output power was 16.27 mW.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.3
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• pp.859-865
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• 2010

We have designed and assembled a saturated absorption-spectroscopy system of $^{127}I_2$ for the frequency stabilization of the 543 nm He-Ne laser. The frequency of a internal-mirror 543 nm He-Ne laser was swept by utilizing the temperature and PZT change of the laser cavity length. Frequency modulation was applied to the output laser mirror with a PZT modulator for the third harmonic signal. A portion of the hyperfine spectrum originated from the R(12)26-0 and R(106)28-0 transitions of the B-X system of $^{127}I_2$ was observed as the third-derivative signal using a saturated absorption spectroscopy. The signal-to-noise ratio of a typical hyperfine spectrum signal was estimated to be 30:1.

• Journal of the Korean GEO-environmental Society
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• v.24 no.10
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• pp.15-23
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• 2023

In this study, the infiltration behavior of slopes composed of mixed soils with clay contents of 0%, 5%, and 10% in weathered Gneiss soil, which is a representative weathered soil in Korea, was investigated, and the stability of unsaturated slopes due to rainfall infiltration was examined. For this, in this study, the soil water characteristic curve was obtained through the water retention test, and the strength constant was obtained through the triaxial compression test. Based on the obtained results, the influence of clay content and antecedent rainfall effect (i.e., initial suction) on the formation of saturated zone (i.e., wetting band) and slope stability due to rainfall infiltration was examined through infiltration and stability analyses. As a result, it was found that the hig her the initial suction, the slower the formation of the saturated zone on the slope. In addition, it was found that as the clay content increases, the shear strength of the ground increases and the resistance to rainfall infiltration increases, and eventually the slope stability is greatly improved.

• Proceedings of the Optical Society of Korea Conference
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• 2001.02a
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• pp.42-43
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• 2001

Nd：YVO$_4$ 결정은 들뜬 상태의 발광 평균 수명이 90-100 $\mu\textrm{s}$로 아주 짧아서 Nd：YAG나 Nd：YLF 레이저 매질에 비해 짧은 펄스폭과 빠른 반복율을 가진 펄스들을 만들어 내는 Q-switching에 적합한 레이저 매질이다. 또한 Nd：YAG 결정에 비해 아주 큰 흡수 계수 및 이득 단면적을 지니고 있어 반도체 레이저로 펌핑하는 고체 레이저에 아주 적합한 레이저 이득 매질이다. (중략)

• The Korean Journal of Zoology
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• v.10 no.2
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• pp.1-8
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• 1967

토끼의 골격근 homogenate에서 23,000$\times$G, 60 분간의 원심분리와 얻은 근 microsome의 ATPase 활성, 근수축에 대한 이완작용, 및 Ca 의 흡수작용을 여러 가지 조건에서 측정하였다. ATPase 활성은 Ca++ Mg++ 양 이온의 존재에 의하여 활성화되며 , 5 mM Mg++ 의 존재하에서는 Ca++ 의 최적농도는 0.1mM이다. Oxalate의 존재하에서는 1 mM 의 Ca++ 이 최적농도이므로 oxalate의 작용은 불용성 Ca-oxalate의 작용은 불용성 Ca-oxalate를 microsome vesicle so 및 medium 내에 침전시켜 유리 Ca++ 농도를 저하시키는 것이라고 생각된다. Microsome의 이완작용은 조제후 120 시간까지 시간에 따라 감소되어 가나, 그이 ATPase 활성은 거의 변화가 없는 것으로 보아 Ca++ + Mg++ -의존성 ATPase 는 이완작용에는 직접 관련이 없는 것으로 해석된다. Oxalatedmlwhswo는 microsome의 Ca++ 흡수량을 현저히 증대시키며 동시에 흡수포화에 도달하는 시간을 지연시킨다. Oxalate의 이러한 효과도 Ca-oxalate의 형성에 기인하는 것으로 해석된다. Microsome 내에 축적되는 Ca 의 량은 ATP 농도가 커질수록 많아진다. 그러나 축적된 Ca 의 량과 ATP 농도사이에 화학정량론적 관계는 없는 것같다.

• Journal of the Korean Geotechnical Society
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• v.27 no.8
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• pp.31-37
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• 2011

In order to evaluate the effect of matric suction on the strength and deformation characteristics, the unsaturated unconfined compression test is performed for the statical1y compacted silty sand. Specimens used were made under conditions with various initial degrees of saturation. The initial matric suction, matric suction at the peak shear strength and the volumetric deformation during the shear process were measured. From these results, it was found that the initial degree of saturation exerts the influence on the behaviors of suction, peak shear strength and the volumetric deformation. Furthermore, the suction stress($P_s$) which means the apparent cohesion due to matric suction in the unsaturated shear strength could be derived.

• Journal of the Korean Geotechnical Society
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• v.32 no.7
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• pp.15-24
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• 2016

To investigate the unsaturated characteristics of the Boeun granite weathered soil, matric suction and volumetric water content were measured in both drying and wetting paths using Automated Soil-Water Characteristics Curve Apparatus. Based on the measured results, Soil-Water Characteristics Curve was estimated by van Genuchten (1980) model. The relationship between effective degree of saturation and matric suction showed the non-linear curve with S-shape and the hysteresis phenomenon occurred during drying and wetting paths. Suction Stress Characteristics Curve was estimated by the Lu and Likos (2006) model. The suction stress in drying path was constantly maintained and that in wetting path tended to increase when the effective degree of saturation was low. But the suction stress in drying path was larger than that in wetting path at the same degree of saturation when the effective degree of saturation became larger. Meanwhile, Hydraulic Conductivity Function was evaluated by the van Genuchten (1980) model which is one of the parameter estimation methods. The unsaturated hydraulic conductivity decreased with increasing the matric suction, and the decreasing velocity regarding to the matric suction in drying path was larger than that in wetting path.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.905-906
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• 2013

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.907-908
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• 2013

• 전기의세계
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• v.53 no.6
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• pp.49-54
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• 2004

현재의 철도, 도로망 등의 각 중심측 및 간선측의 주요 교통시설은 이미 포화 상태가 되어 물류비용의 증가를 초래하고, 배기 가스를 비롯한 환경오염 문제를 유발하고 있기 때문에 이에 대한 해결방안이 시급한 실정이다. 이러한 상황에서 고속전철은 대기 오염을 일으키지 않으면서 신속$.$대량 수송이 가능하여 교통량을 대량으로 흡수할 수 있는 주요 교통 수단으로 인식되고 있다.(중략)