• The Journal of Engineering Geology
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• v.17 no.3
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• pp.359-365
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• 2007

Freezing and thawing cycle is one of the major weathering-induced factors in the mechanical weathering of the rock mass. This natural process accelerates rock weathering process by breaking down the parent rock materials and makes soil or weathered rock formation in a rock slope surface zone. It can also cause reduction of the shear strength in slopes. It is important to calculate the deterioration depth caused by freezing-thawing for a slope stability analysis. In this study, deterioration depths of rock slope due to freezing-thawing were calculated using the 1-D heat conductivity equation. The temperature distribution analysis was also carried out using collected temperature distribution data for last five years of several major cities in Korea. The analysis was performed based on the distributed rock types in study areas. Thermal conductivities, specific heats and densities of the calculation rocks are tested in the laboratory. They are thermal properties of rocks as input parameters for calculating deterioration depths. Finally, the paper is showing the calculated deterioration depths of each rock type slopes in several major cities of Korea.

• The Journal of Engineering Geology
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• v.15 no.3
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• pp.325-335
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• 2005

Deterioration depths of rock slope due to freezing-thawing were calculated using the 1-D heat conductivity equation. The temperature distribution analysis was carried out using temperature distribution data for last two years of the five major cities such as Seoul, Daejeon, Pohang, Gwangju and Cangneung. The analysis was performed based on three different types of rocks, sandstone, granite and gneiss. This study has found that the deterioration depths tend to be greater with the increase of the thermal conductivity coefficient in Seoul, Daejeon and Pohang where showing relatively greater temperature deviations. Regarding the influence of rock types, deterioration depths turned out to be greater in Gwangju and Gangneung where show relatively smaller temperature deviations among the five cities, assuming these cities are on the granite with thermal conductivity of $55,200\;cal/m\timesday\times^{\circ}C$. In contrast, for the other rock types, cities of relatively geater temperature deviations show deeper deterioration depth than the others. Deterioration depths of rock slope in Korea due to freezing-thawing fumed out to be around 8.4 m to 10.7 m.

• 보존과학연구
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• s.11
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• pp.221-233
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• 1990

4종의 상태가 좋은 그리고 2종의 열화된 수침 침엽수재(Pinus massoniana,Pinus.densiflora, Cunninghamia lanceolata, Crypto meria japonica)를 PEG400과PEG4,000용액으로 처리하였다. 모든 종이 안정화처리에 똑같게 반응을 보였다. 전체적으로 건전재나 약간 열화된 수침재는 PEG400 20%용액으로 처리한 결과 치수안정화가 달성되었다. PEG4,000의 50%용액으로 처리한 목재의 건조에 대한 수축은 심하게 열화된 목재에 대해 열화되지 않은 목재에서는 1/2에서 1/3정도 감소하였다. 엄격한 상관관계가 최적안정화를 위해 PEG와 목재의 밀도간에 존재한다. 최적으로 처리된 목재는 86%상대습도 이하에서는 축축하게 되지 않는다. PEG400과 PEG4,000으로 처리한 2단부함침이 황해에서 구조된 중국 정크선의 목재를 안정화시키는데 대해 추천된다.

• 보존과학연구
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• s.37
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• pp.43-51
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• 2016

A wooden rice chest in National Museum of Korean Contemporary History was colored by black lacquer but it was degraded and fallen apart partially. The condition of the paint of front and left sides were relatively fine, but the coat of the top, back and right sides were exfoliated. The legs at the bottom of the chest were severly degraded and turned whitish. After condition checking flakes and deterioration of film, the conservation treatment was undertaken with cleaning surface. Wet cleaning was conducted that area had lots of dust area. Apply watery animal glue to degraded lacquer layers. The legs were exfoliated a lot, so applied watery animal glue several times. Other side of rice chest except Gaepan, that was not felt sense of difference, colored centrally Gaepan.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.11
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• pp.62-69
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• 1998

The general degradation model has been applied to analyze the hot carrier induced degradation of the DC and RF characteristics of RF-nMOSFET. The degradation of cut-off frequency has been severer than the degradation of bulk MOSFET drain current. The value of the degradation rate n and the degradation parameter m for RF-nMOSFET has been equal to those for bulk MOSFET. The decrease of device degradation with the increase of fingers could be explained by the large source/drain parasitic resistance and drain saturation voltage. It has been also found that the RF performance degradation could be explained by the decrease of $g_{m}$ and $C_{gd}$ and the increase of $g_{ds}$ after stress. The degradation of the DC and RF characteristics of RF-nMOSFET could be predicted by the measurement of the substrate current.t.

• Journal of the Korean Wood Science and Technology
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• v.35 no.1
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• pp.64-72
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• 2007

The biodeterioration behaviors of square post to support the wooden printing blocks Shelves in the Janggeongpanjeon were investigated according to the positions and parts of square post, and environmental conditions. It was found that a high differences of deterioration in the progressing levels of wood decay, according to the positions and parts of square post, and environmental conditions. The decay levels were very high and still progressing in the contacted areas with stone foundation which are about up to 50 cm above it. In the decay type, white rot fungi was mainly affected in the inside of building which mainly made of softwood. The decay in the square posts to support the wooden printing block shelves inside of building was worse in the rear side, compared to front side. The insects was not found in most of square posts excluding the post which was neighboring at the infected round column by insect.

• Magazine of the Korea Concrete Institute
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• v.2 no.4
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• pp.22-30
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• 1990

• Journal of the Korean Society for Nondestructive Testing
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• v.19 no.2
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• pp.129-144
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• 1999

플랜트와 같은 장치산업은 내구성 구조물이므로 사용중에 열화가 발생하는 것은 필연적이다. 특히 고온, 고압의 부식환경하에서 사용되는 설비는 손상이 심하므로 가동중에 돌발적인 고장이 발생하여 플랜트의 가동을 중지하거나 파손사고가 일어나 생산손실은 물론 경우에 따라서는 안전사고의 발생, 환경오염 등 사회적인 문제를 일으키므로 이들 설비의 경년열화 실체를 충분히 이해하고 대책을 수립하는 것은 대단히 중요하다. 따라서 본고에서는 장치산업에서 발생하는 열화현상(재료의 연화, 경화 및 취화, 크리프, 피로, 부식, 마모 등)중 손상의 주류를 이루는 연화, 경화 및 취화, 크리프 피로에 대하여 기본적인 손상기구(damage mechanism)와 비파괴적 진단 및 평가 방법에 주안점을 두어, 현재 국내의 각종 플랜트 진단에 실용화된 기술을 해설하여 이 분야에 종사하는 관계자 여러분의 이해에 조금이라도 기여코자 한다.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.2
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• pp.13-18
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• 2007

This paper presents the experimental findings on the different degradation mechanism which depends on the gate oxide thickness in lateral DMOS transistors. For thin oxide devices, the generation of interface states in the channel region and the trapped holes in the drift region is found to be the causes of the device degradation. For thick devices, the generation of interface states in the channel region is found to be the causes of the device degradation. We confirmed the different degradation mechanism using device simulation. From the comparison of device degradation under DC and AC stress, it is found that the device degradation is more significant under DC stress than one under AC stress. The device degradation under AC stress is more significant in high frequency. Therefore the hot carrier induced degradation should be more carefully considered in the design of RF LDMOS transistors and circuit design.

• 보존과학연구
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• s.35
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• pp.121-127
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• 2014

The Vietnam homecoming box that has been collected in National Museum of Korean The Vietnam homecoming box that has been collected in National Museum of Korean Contemporary History got severely damaged such as rot, attached foreign substance, fading, color, wood decay. In particular, the bottom of the box was unstable state that deteriorated by pests and the left strut was severely damaged by some deep cracks and pests. The metal bands were remained on the side and bottom of the box, and all the bands were seriously corroded. On the bottom-right of the lid, black foreign matter was adhered to the surface. In the process of conservation treatments, the cleaning, filling cracks, reinforcing the bottom of the box, attaching the metal bands were proceed in order after the investigation of the state.