• Journal of the korean academy of Pediatric Dentistry
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• v.28 no.4
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• pp.683-693
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• 2001

The purpose of this study was to evaluate the effects of Er:YAG laser on cutting efficacy and its histologic findings. Dentin specimens of human premolars and molars were used and irradiated by Er:YAG laser with noncontact handpiece type delivery system under different treatment condition of irradiation time. Cavity pattern and volume were evaluated to determine the cutting efficacy and following results were obtained. 1. Cutting volume of sound dentin was getting larger with time immersed in water increase 2. With the condition of irradiation (150mJ, 10Hz, 30sec), surface irregularity was more increased in sound dentin comparing to carious dentin. For the light microscopic examination, dentinal tubules were opened and ash flecks and cracks were noted with inconsistence of dentinal tubules. 3. In case of 30 sec. irradiation in carious dentin, dark zone was limited to small focus whereas 1 min. irradiation, more wider, and cracks were noted in the perpendicular to direction of dentinal tubules. For the 2 min. irradiation, cavity was the widest and more cracks were found.

• Weed & Turfgrass Science
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• v.4 no.2
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• pp.124-128
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• 2015

Large patch, caused by Rhizoctonia solani AG2-2 IV, is a soil-born disease that is the most important of warm season turfgrass such as zoysia and Bermuda grass. This study was conducted to analysis of the soil microbial community structure on large patch. Center of the large patch (CLC), edge (CLE) and healthy (CLH) part of microbial communities were examined using metagenomics in Phylum level. Distribution trends of the rhizosphere microorganisms were similar to the order Proteobacteria, Acidobacteria, Chloroflexi, Firmicutes, Planctomycetes, Gemmatimonadetes, Nitrospira, Cyanobactria and Verrucomicrobia in soil collections. Contrastively Actinobacteria was more 56% abundant in healthy part soil (16%) than in the center (9.28%) or edge (10.84%) parts. Taxonomic distributions were compared among the CLC, CLE and CLH, total 6,948 OTUs were detected in the CLC, 6,505 OTUs for the CLE and 5,537 OTUs were detected in the CLE. Distributions of Actinobacteria OTUs were appeared 615 OTUs in the CLC, 709 OTUs in the CLE and 891 OTUs in the CLH. Among Actinobacteria, 382 OTUs were overlapped in the all soils. Not matched OTUs of CLH (286 OTUs) was detected 23 times higher than CLC (91 OTUs) and CLE (126 OTUs).

• Journal of KSNVE
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• v.6 no.6
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• pp.827-834
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• 1996

The effect of pipe breaks in the secondary side is investigated as a part of the fuel assembly qualification program. Using the detailed dynamic analysis of a reactor core, peak responses for the motions induced from pipe breaks are obtained for a detailed core model. The secondary side pipe breaks such as main steam line and economizer feedwater line braksare considered because leak-before-break methodology has provided a technical basis for the elimination of double ended guillotine breaks of all high energy piping systems with a diameter of 10 inches or over in the primary side from the design basis. The dynamic responses such as fuel assembly shear force, bending moment, axial force and displacement, and spacer grid impact loads are carefully investigated. Also, the stress analysis is performed and the effect of the secondary side pipe breaks on the fuel assembly structural integrity under the faulted condition is addressed.

• Journal of the Korean GEO-environmental Society
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• v.16 no.8
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• pp.21-35
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• 2015

Electrical resistivity survey (2D and 3D) were employed for detection of possible weak zone of core zones of three central core earth-rockfill dams in Korea. In the 2D results, the core zones is lower resistivity zone with less than $50{\sim}400ohm{\cdot}m$, and the basement is relatively higher resistivity zone with over $1,000ohm{\cdot}m$. In the 3D results, especially, the weak zone with under $100ohm{\cdot}m$ was detected spatial distribution area in the dam. We also drilled boreholes to collect soil samples of core zones of each dam. Water was not used during boring, because water for rotary wash boring could cause structural damages in earth dams. We found that the soil samples of core zones from all of the boreholes correspond to CL (USCS), but we also found that the fluidized or water-saturated soil samples were found in lower resistivity zones. Therefore, the electrical resistivity survey and drilling method without water are a quick and efficient method for structural-health evaluation which is detection of possible weak zones in earth core rockfill dams.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.17 no.2
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• pp.167-181
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• 2019

Currently, the development of evaluation technology for vibration and shock load characteristics and spent nuclear fuel structural integrity under normal conditions of transport is being conducted in the Republic of Korea. This is the first such research conducted in the Republic of Korea and, thus, previous international studies need to be investigated and will be referred to in the ongoing project. Before 2000, several studies related to measurement of vibration and shock loads on spent nuclear fuel were conducted in the US. US national research institutes conducted uniaxial fuel assembly shaker tests, concrete block tests, and multi-axis fuel assembly tests between 2009 and 2016. In 2017, multi-modal transportation tests including road, sea, and rail transport were also performed by research institutes from the US, Spain and the Republic of Korea. Therefore, test preparation procedures, acceleration and strain measurement results, and finite-element and multi-body dynamics analysis were investigated. Based on the measured strain data, the preliminary conclusion was obtained that the measured strain was too small to cause damage to spent nuclear fuel rods. However, this conclusion is a preliminary conclusion that only reviews part of the results; a detailed review is being conducted in the US. The investigation of international studies on spent nuclear fuel structural integrity tests considering vibration and shock loads under normal conditions of transport in the US will be useful data for the project being conducted in the Republic of Korea.

• Food Industry
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• s.148
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• pp.55-71
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• 1999

방사선 식품조사기술은 마침내 세계 여러 나라에서 실용화되고 있다. 식품조사 (food irradiation)는 식품의 위생적 품질개선, 수확 후 손실감소, shelf-life의 연장 등의 목적으로 이용되고 있다. 관련 규정에 따라 방사선 조사된 식품은 안전(safe)하고 건전(wholesome)하지만, 소비자들은 방사선 조사된 식품과 조사되지 않은 식품을 자유롭게 선택할 수 있기를 바란다. 이를 위해서는 조사된 식품에서 labelling이 필수적이다. 식품조사기술에 관련된 규정의 준수를 유도하기 위하여 피조사체 식품 자체를 분석하여 조사 여부를 검지$\cdot$확인하는 것은 아주 바람직한 방법이라 할 수 있다. 최근 몇 년 사이에 방사선 조사시 야기되는 식품의 물리적, 화학적 및 생물학적 변화를 바탕으로 방사선 조사식품을 검지하는 방법에 많은 발전이 거듭되고 있으며, 이에 본 고에서는 최근의 연구동향에 대하여 소개하고자 한다.

• Nuclear industry
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• v.28 no.12
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• pp.73-78
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• 2008

• Journal of the KSME
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• v.55 no.10
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• pp.31-35
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• 2015

이 글에서는 원자력발전소의 안전성 확보를 위한 원자로 압력용기 재료의 신뢰성 평가 및 향상기술에 대해 개괄적으로 기술하였다. 압력용기 소재의 중요성과 가동 중 건전성 평가기술에 대해 다뤘으며 특히, 조사취화특성 평가와 관련한 기술현황을 중점적으로 소개하였다.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2005.10a
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• pp.115-129
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• 2005

• Proceedings of the Materials Research Society of Korea Conference
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• 2001.11a
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• pp.193-193
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• 2001