• Journal of Korea Water Resources Association
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• v.57 no.3
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• pp.165-179
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• 2024

It is crucial to have a comprehensive understanding of inundation and water cycle in urban areas for mitigating flood risks and sustainable water resources management. In this study, we developed a Cellular Automata-based integrated Water cycle model (CAW). A comparative analysis with physics-based and conventional cellular automata-based models was performed in an urban watershed in Portland, USA, to evaluate the adequacy of spatiotemporal inundation simulation in the context of a high-resolution setup. A high similarity was found in the maximum inundation maps by CAW and Weighted Cellular Automata 2 Dimension (WCA2D) model presumably due to the same diffuse wave assumption, showing an average Root-Mean-Square-Error (RMSE) value of 1.3 cm and high scores of binary pattern indices (HR 0.91, FAR 0.02, CSI 0.90). Furthermore, through multiple simulation experiments estimating the effects of land cover and soil conditions on inundation and infiltration, as the impermeability rate increased by 41%, the infiltration decreased by 54% (4.16 mm/m²) while the maximum inundation depth increased by 10% (2.19 mm/m²). It was expected that high-resolution integrated inundation and water cycle analysis considering various land cover and soil conditions in urban areas would be feasible using CAW.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.10
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• pp.1261-1266
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• 2012

In this study, salt-water immersion tests were experimentally performed for up to 12 months to investigate the hygrothermal effect of salt-water environments on the mechanical properties of carbon/epoxy composites. The composites were manufactured by laminating prepregs composed of carbon plain-woven fabric and epoxy resin. The specimens were subjected to temperatures of 35, 55, and $75^{\circ}C$ while being exposed to the salt-water environments. Mechanical test results showed that the tensile modulus and tensile strength decreased at a small rate, and the compressive modulus and compressive strength decreased at a relatively larger rate, as the exposure temperature and time increased. The rate of decrease in compressive strength became larger as the exposure temperature became higher. This is because a higher environmental temperature accelerates the salt-water uptake; this, in turn, reduces the compressive strength more rapidly.

• The Korean Journal of Mycology
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• v.14 no.3
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• pp.231-235
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• 1986

Spore production mechanism of selected lignicolous basidiomycetes was inhibited by soaking their sporocarps in water for varying periods. Depending on the duration of immersion, some species resumed spore discharge, while in others it was completely ruined. This was related to the nature and consistency of these sporocarps. All the species studied absorbed water quite readily into their sporocarps. The loss of this water through dehydration was more rapid in smaller and delicate species than the bulky and robust ones.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.5 no.4
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• pp.297-308
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• 2007

The granulation equipment of concentrated wastes is manufactured for the polymer solidification of concentrated wastes. It uses liquid sodium silicate as a granulating agent for the granulating of dried powder containing boric acid. The granulating agent is sprayed in the form of droplet and mean size of dried granules is $2{\sim}4mm$. The new technology which has been used for the polymer solidification of spent resin in U.S. and certified by Nuclear Regulatory Commission (NRC) is successfully applied to concentrated wastes. This uses in-situ solidification process within drum without mechanical mixing. Maximum loading of waste can be achieved without increasing of waste volume. Polymer waste forms were evaluated with several test such as fire test, compressive strength test, leaching test, immersion test, irradiation test, and thermal cycling test according to standard test procedures.

• The korean journal of orthodontics
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• v.30 no.4 s.81
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• pp.475-481
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• 2000

The purpose of this study was to evaluate the effect of oral environment on the strength of resin bracket wings by comparing fracture mode according to water immersion and thermocycling. Seventy-five resin brackets(Spirit MB, Ormco, California) were divided into three groups and treated for six months as follows; (1) untreated, (2) water immersion in distilled water at $37^{\circ}C$, (3) water immersion in distilled water at $37^{\circ}C$ with total 2,100 times of thermocycling taken 350 times each month. Fracture mode of the wing was tested on universal testing machine. In addition to resin brackets, 25 metal brackets were used as controls. Through the statistical analyses, following results were obtained. 1. Resin bracket wings showed significantly lower fracture strength than metal brackets(p<0.001). 2. Water immersion and water immersion with thermocycling groups showed significantly lower fracture strength than open air condition group(p<0.001). 3. Water immersion with thermocycling group showed significantly lower fracture strength than water immersion group(p<0.001). The above results suggest that the mechanical property of resin bracket wing nay be influenced by oral environment and further research is needed to improve the strength of the wing in the resin bracket.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.242-246
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• 2006

최근 들어 전 세계적으로 유량측정 분야의 큰 변화의 방향은 자동화이다. 전자, 전기 기술과 정보통신 기술의 발달을 유량측정 분야에 적용하여 자동적으로 유량측정을 수행하고 실시간으로 모든 유량자료를 수집하는 시스템을 구성하려는 연구가 활발하게 진행중이다. 최근에 초음파 유량계와 더불어 자동 유량측정 기법으로 각광을 받고 있는 기법이 유속지수법(index velocity method)이다. 유속지수법의 원리는 매우 간단하다. 수위 기록을 통하여 수위-면적 관계로부터 흐름 단면적을 구하고, 임의의 영역에서 측정된 유속이 단면 평균 유속으로 환산될 수 있다면, 흐름 단면적과 평균 유속에 의해 연속적으로 유량을 구할 수 있다. 유속지수법에서 가장 중요한 것이 전체 평균 유속을 대표할 수 있는 유속지수를 정확하고 효율적으로 측정하는 것이다. 유속지수법에 의한 연속 유량측정 목적으로 최근에 ADVM(Acoustic Doppler Velocity Meter)이 개발되어 이용되고 있다. ADVM은 수중에 초음파를 발사해서 산란체에서 반사되어 돌아오는 초음파의 주파수 편이, 즉 도플러 효과를 이용하여 유속을 측정하는 유속계이다. 본 연구에서는 ADVM을 괴산댐 하류에 위치한 시험하천에 설치하여, 유속지수법에 의한 유량측정기법을 적용하고 그 특성을 분석하였다. 유속지수법으로 측정된 유량을 괴산댐 방류량과 비교한 결과 평균 4.0%의 상대오차를 지니고 있어 비교적 정확한 연속 유량측정이 가능한 것으로 나타났다. 이와 같은 유속지수법을 하천 유량측정에 활용하면 보다 정확한 유량을 연속적으로 자동화하여 측정할 수 있을 것으로 기대된다.연계모형의 한계로 인하여 두 모형의 통합모형이 필요하다. 즉, 강우 혹은 월류유량으로 발생한 지표유량 중 일부분이 과부하가 발생하지 않는 유입구 지점을 통과할 때 배수시스템으로 유입되는 것을 고려할 수 있고, 유입된 유량은 배수시스템 내의 흐름에 반영되도록 배수시스템과 침수해석모형을 통합한 모형 개발이 필요하다. 그러기 위해서는 지표면과 배수시스템에 대한 수리학적 관계를 정립하여야 한다. 본 연구에서는 배수시스템 해석 모형과 도시침수해석 모형을 통합하고, 두 모형간의 유량의 전송과정을 수리학적 관계를 고려한 dual-drainage 도시침수해석모형을 개발하였다. 이를 위해 도시지역 배수시스템 해석 모형으로 널리 이용되고 있는 SWMM모형을 이용하여 지표면으로의 월류량을 산정하고 유입된 지표유량에 대해서 배수시스템에서의 흐름해석을 수행하였다. 그리고, 침수해석을 위해서는 2차원 침수해석을 위한 DEM기반 침수해석모형을 개발하였고, 건물의 영향을 고려할 수 있도록 구성하였다. 본 연구결과 지표류 유출 해석의 물리적 특성을 잘 반영하며, 도시지역의 복잡한 배수시스템 해석모형과 지표범람 모형을 통합한 모형 개발로 인해 더욱 정교한 도시지역에서의 홍수 범람 해석을 실시할 수 있을 것으로 판단된다. 본 모형의 개발로 침수상황의 시간별 진행과정을 분석함으로써 도시홍수에 대한 침수위험 지점 파악 및 주민대피지도 구축 등에 활용될 수 있을 것으로 판단된다. 있을 것으로 판단되었다.4일간의 기상변화가 자발성 기흉 발생에 영향을 미친다고 추론할 수 있었다. 향후 본 연구에서 추론된 기상변화와 기흉 발생과의 인과관계를 확인하고 좀 더 구체화하기

• Composites Research
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• v.18 no.4
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• pp.27-34
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• 2005

Salt water spray and immersion tests were experimentally conducted for over 6 months to investigate the durability of glass fabric/phenolic composites under salt water environment. Mechanical properties such as tensile properties, flexural properties, and shear properties were evaluated and thermal analysis properties such as storage shear modulus, loss shear moduls, and tan 6 were obtained through a DMA. A change in chemical structures was analyzed through a FTIR. According to the results, mechanical properties and thermal analysis properties were sensitive to salt water environment and these properties began to degrade in increasing in exposure times. However, tensile and flexural moduli started to decrease and then slightly increase as increasing in exposure times due to plasticization and crosslinking in matrix as well as physical swelling in composites. Beyond a certain exposure times, these properties began to decrease as further increasing in exposure times. Also the shape and location of peaks in FTIR curves were insensitive to exposure times, but the intensity of peaks would be. finally we found that the durability of glass fabric/phenolic composites were affected on salt water immersion environment rather than salt water spray environment.

• Journal of the Korean Geotechnical Society
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• v.24 no.11
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• pp.101-109
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• 2008

In order to investigate the influence of the water on compression characteristic of decomposed granite soils, a single particle crushing test and one-dimensional compression tests were carried out on three decomposed granite soils and Silica sand. The initial fracture strength for single particle reduced and variability of the strength increases due to weakening by existing water. Moreover, it was recognized that one-dimensional compression characteristic was related to the initial fracture strength characteristic, and the initial fracture strength also has the effect of weathering.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.411-413
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• 2012

This study has been investigated about hygrothermal environmental effects on the pin-joined carbon/epoxy composites through acoustic emission technique. The specimens were classified as three types for pin loading test : Base (before immersion), RT (room temperature immersion), HT ($75^{\circ}C$ immersion). As a results, the bearing strength of RT specimens was weakly decreased than that of base specimens. The bearing strength of HT specimens was greatly decreased than that of Base and RT specimens due to effects of simultaneous moisture and higher temperature. Also, the results from cumulative hit of acoustic emission indicated that AE events induced by matrix cracks of HT specimens was lower than that of base specimens.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.9
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• pp.261-268
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• 2018

The use of electric cable was limited due to the installation time and large space as the increase of power demand and load quantity in side line. In order to solve these problems, the application of busway system which can supply the large current was increasing. But it was lack of methods of performance tests to evaluate the reliability and results of test for busway system. In this paper, we presented items to evaluate the reliability test for epoxy coated busway system with reference to IEC 61349-6. In addition, we proposed items to evaluate the reliability and long term life cycle test for the epoxy coated busway system. The combined acceleration deterioration test that reflects actual conditions of the survey as much as possible was conducted considering both thermal and electrical stresses. The deterioration condition was selected to satisfy fifty years life expectation and the insulation performance verification test of the busway system confirmed the long term life prediction. Furthermore, as test items for reliability assessment of compliance with the environment for the use of temperature, humidity and load current where busway system was installed, thermal overload test, water immersion test, cold shock temperature test and thermal cycle test were performed. And we examined changes in characteristics and abnormality after tests. From results, the test items presented to evaluate performance and reliability of the epoxy insulated busway system were confirmed to be appropriate in this paper, and the performance of the product was also confirmed to be excellent for reliability tests.