• Journal of the Korean Society of Propulsion Engineers
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• v.4 no.3
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• pp.64-73
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• 2000

The joint parts was composed of inner AL(aluminum) ring, FRP wedge and motor case which was manufactured by filament wound method. Where the motor case consists of helical and hoop layer. The finite element analysis was performed for the design variable of joint parts to improve the performance of motor case. Where the adhesive layer was modeled to elasto-perfect plastic material and the contact condition of AL ring and wedge was modeled by using the contact surface element of ABAQUS. And the sliding distance of AL ring and the hoop strain of composite case were compared to hydro-static test results to verify the accuracy of analysis results. When wedge and AL ring was perfect bonding, though the hoop strain of joint part was reduced, the maximum shear stress was occurred at the adhesive layer. Thus the adhesive layer had failed due to the high shear stress before the failure was occurred at the case. And as another design method, when wedge and AL ring was contact condition, the shear stress on adhesive layer was decreased. But the hoop stress of joint part increased due to the sliding behavior of AL ring. Finally, the fail was occurred at the composite case of joint part. The improved joint method reinforced by hoop layer to the joint parts under contact condition for wedge and Al. ring reduced the joint part's hoop strain by constraint the sliding behavior of AL ring.

• Korean Journal of Ecology and Environment
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• v.51 no.4
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• pp.253-258
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• 2018

Phytoplankton community was studied in relation to a typhoon at Bok-gyo Bridge area in Juam Lake, Korea. In August 31, 2000, a typhoon (Prapiroon) was passed by Juam Lake with great power enough to destroy summer stratification of Juam Lake. Destratification resulted in temporal mixing of the whole water column and changed the physical and chemical properties of water bodies, and caused the changes of the biological properties. The transparency decreased from 195 cm before the typhoon to 84 cm after the typhoon with the resuspension of the bottom sediment. In the vertical distribution of the phytoplankton population, the maximum population was measured at depth of 2 m before the typhoon. However, immediately after the typhoon, the population distributed evenly throughout the entire water layers. The carbon biomass of the phytoplankton was also highest at the depth of 2 m before the typhoon, but immediately after the typhoon, it was uniformly distributed throughout the whole water layers. The vertical profiles of the concentrations of chlorophyll a, however, did not show a significant difference before and after the typhoon. The typhoon induced destratification and restratification altered the taxa of the phytoplankton. The major dominant phytoplankton taxa before the typhoon was diatoms including Aulacoseira granulata, but the green algae overwhelmed the diatoms in cell number and biomass after the typhoon. The chlorophycean dominance was replaced by cyanophycean dominance with the heavy rain and descent of water temperture at the end of September.

• Geotechnical Engineering
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• v.1 no.2
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• pp.41-54
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• 1985

Generally, ground settlements and lateral displacements are accompanied by underground excavation associated with open-cut or tunnling. These ground movements cause a harmful influence upon nearby super.structures and sub-structures. Occasionally, the ground movements may pose serious problems as the function of the nearby structures may be disrupted. Therefore, prior to the subway construction in an urban area, it is necessary to identify the causes of ground settlements and estimating the extent St the magnitude of ground movements since any potential damage to the nearby structures such as gas lines, water mains, high buildings and cultural assets must be assessed. The research was performed mainly on ground movements such as surface settlements, lateral displacements, subsurface settlements and crown settlements to predict the maximum settlement and settlement zone, and to identify the causes of ground settlements in NATM sections of Busan subway. As a result, it was found that lateral distribution of settlements could be approximated reasonably by a Gaussian normal probability curve and longitudinal distribution of settlements by a cumulative Gaussian probability curve, and that the early closure of temporary invert was very important to minimize ground settlements.

• KSBB Journal
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• v.21 no.5
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• pp.341-346
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• 2006

This study was carried out to establish the optimum condition for cell disruption with a sonificator in the detection of the gram negative bacteria, E. coli for the purpose of developing automatic fluorometer. The efficiency of sonification on the E. coli disruption was greatly dependent on the diameter of sonificator probe tip. The larger sonificator probe diameter showed greater disruption effect. Sonificator probe of 13 mm diameter was the most efficient one for E. coli when sonificated for 20 seconds. The efficiency of the E. coli disruption differed greatly according to the depth of sonificator probe tip sank in the sample solution. The shorter the distance between probe tip end and the bottom of the container, the higher the disruption efficiency. The detection limit of E. coli was $5{\times}10^5CFU/m{\ell}$ when sample was sonificated for 20 seconds with a sonificator probe of 13 mm diameter.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.32 no.5
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• pp.451-457
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• 2014

Recently, the land degradation and pasture erosion in Tuv, located around Ulaanbaatar of Mongolia, have been increasing sharply due to escalating developments of mining sectors, well as the density of populations. Because of that, we have chosen the urban and mining area of Tuv for our study target. During the study, the temporal changes of land cover in Tuv, Mongolia were observed by the Landsat TM/+ETM satellite images from 2001 to 2009 that provided the fundamental dataset to apply NDVI and K-Mean algorithm of Unsupervised Classification and Maximum likelihood classification(MLC) of Supervised Classification in order to conclude in land cover change analyzation. The result of our study implies that the growth of mining area, the climate change, and the density of population led the land degradation to desertification.

• Journal of KIISE:Information Networking
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• v.31 no.1
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• pp.62-69
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• 2004

The cluster structure reduces the number of retransmission messages, when a broadcast to all hosts in ad hoc network is needed. A cluster maintenance scheme is employed to preserve this advantage from time to time. However, most of the cluster maintenance schemes require additional control messages for cluster reformation as well as control messages for acquiring neighbor information. This mitigates the advantages of employing cluster structure in ad hoc network. In this paper, a cluster maintenance scheme which forces only clusterheads to broadcast control messages during hello time is proposed. When the cluster reformation is needed, the proposed scheme employs a strategy to reduce the control messages to a minimum. In these processes, the proposed scheme doesn't violate the definition of 2-cluster and produces the clusters in fully distributed method. The simulation results prove that our scheme is better than LCC(1).

• Journal of the Korean Society for Nondestructive Testing
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• v.27 no.2
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• pp.164-172
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• 2007

Surface cracks in concrete are common defects that can cause significant deterioration and failure of concrete structures. Therefore, the early detection, assessment, and repair of the cracks in concrete are very important for the structural health. Among studies for crack depth assessment, self-calibrating surface wave transmission method seems to be a promising nondestructive technique, though it is still difficult in determination of the crack depth due to the variation of the experimentally obtained transmission functions. In this paper, the spectral energy transmission method is proposed for the crack depth estimation in concrete structures. To verify this method, an experimental study was carried out on a concrete slab with various surface-opening crack depths. Finally, effectiveness of the proposed method is validated by comparing the conventional time-of-flight and cutting frequency based methods. The results show an excellent potential as a practical and reliable in-situ nondestructive method for the crack depth estimation in concrete structures.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.12
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• pp.1048-1058
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• 2017

One of the failure mechanism of spaceborne electronics is a fatigue fracture on solder joint under launch random vibration. Thus, a necessity of early diagnosis through the fatigue life evaluation on solder joint arises to prevent such potential risk of failure. The conventional life prediction methods cannot assure the accuracy of life estimation results if the packaging type changes, and also requires much time and effort to construct the analysis model of highly integrated PCB with various packaging types. In this study, we performed life prediction of PCB based on a reliability and life prediction tool of sherlock as a new approach for evaluating the structural reliability on solder joint, and those prediction results were validated by fatigue tests. In addition, we also investigated an influence of solder height on the fatigue life of solder joint. These results indicated that the Sherlock is applicable tool for evaluating the structural reliability of spaceborne electronic.

• Journal of Acupuncture Research
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• v.21 no.1
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• pp.211-225
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• 2004

목적 : 류마티스 관절염 환자의 골 파괴에 중요한 역할을 하는 것으로 알려진 Matrix Metalloproteinase-1(MMP-1) 유전자의 단일 염기 다형성을 분석하고, 나아가 봉독약침 치료에 대한 반응과의 연관성을 조사하기 위하여 본 연구를 시행하였다. 방법 : 미국류마티스학회의 류마티스 관절염 기준에 해당하는 122명의 한국인 류마티스 관절염 환자와 건강한 92명의 대조군을 대상으로 pyrosequencing 방법을 이용하여 MMP-1 유전자의 -519 위치의 다형성을 비교 분석하였으며, 류마티스 관절염 환자군을 다시 유전자 유형에 따라 동통 관절수, 종창 관절수, 조기 강직, 통증 강도, 삶의 질 평가도구인 HAQ, 환자 및 의사의 전반적 질병상태 평가, ESR, CRP 등의 항목을 치료 전후 평가하여 비교 분석하였다. 결과 : 1. 류마티스 환자군과 건강한 대조군간에 MMP-1 유전자의 단일 염기 다형성의 유전자형의 분포와 대립유전자 발현 빈도에 통계적으로 유의한 차이가 나타났으며, 이는 MMP-1 유전자 다형성이 한국인 류마티스 관절염 환자의 질병 감수성과 관련이 있음을 추정할 수 있다. 2. 각 유전자형 그룹간 치료전 질병의 중증도 평가에서 임상 평가와 혈액의 급성 염증 반응물질 평가에서 통계적으로 유의한 차이는 없었다. 3. 급성 염증 반응의 지표인 ESR과 CRP level의 봉독약침 치료 전후 변화는 MMP-1의 유전자 다형성과 유의한 연관이 없었다. 4. 각 유전자형 그룹간의 치료 전후 질병 호전도 비교에서, AA 유전자형이 종창 관절수 평가에서 더나은 호전을 보였으며, 다른 모든 평가에서는 통계적으로 유의한 차이가 없었으며, 향후 관련 유전자와의 연관성 연구가 필요하다고 사료된다.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.4 no.1
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• pp.23-29
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• 2004

Cystinosis, an autosomal recessively inherited lysosomal storage disease, results from impaired transport of the amino acid cystine out of cellular lysosomes. The consequent accumulation and crystallization of cystine destroys tissues, causing growth retardation, Fanconi syndrome, renal failure, eye problems, and endocrinopathies. The gene for cystinosis, CTNS, was mapped to chromosome 17p13. The diagnosis of cystinosis is made by measuring the leukocyte cystine content and the presence of typical corneal crystals on slit-lamp examination is also diagnostic. Since treatment with cysteamine has proved extremely effective, early diagnosis and treatment are critical aspects. We experienced a typical case of cystinosis in a 12-year-old boy with growth retardation.