• Ecology and Resilient Infrastructure
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• 제3권2호
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• pp.126-129
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• 2016

도시화로 인해 불투수 면적이 증가하면서 지하 침투량이 감소하고 강우 유출량이 증가하여 도시 침수 발생 가능성이 커지고 지하수 고갈 문제를 발생시키고 있다. 본 연구에서는 가로수 주위에 수분 및 영양을 공급할 수 있는 신개념 특수 가로수 보호판의 설치가 도시 내 침투량 개선에 미치는 효과를 평가하고, 시설의 배치에 따른 침투량 변화를 조사하였다. 침투관이 설치된 신개념 가로수 보호판은 토양으로는 빗물 침투량을 증가시키고 지면 위 수위 상승을 억제하였다. 따라서 개발된 신개념 가로수 보호판은 도시 도로변에서 저영향개발 (LID) 시설로서 효과적으로 적용될 수 있을 것으로 판단되었다.

• Nuclear Engineering and Technology
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• 제55권11호
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• pp.3940-3955
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• 2023

A new method of numerical simulating prediction and decontamination effect evaluation for abrasive jet decontamination to radioactively contaminated metal is proposed. Based on the Computational Fluid Dynamics and Discrete Element Model (CFD-DEM) coupled simulation model, the motion patterns and distribution of abrasives can be predicted, and the decontamination effect can be evaluated by image processing and recognition technology. The impact of three key parameters (impact distance, inlet pressure, abrasive mass flow rate) on the decontamination effect is revealed. Moreover, here are experiments of reliability verification to decontamination effect and numerical simulation methods that has been conducted. The results show that: ⁶⁰Co and other homogeneous solid solution radioactive pollutants can be removed by abrasive jet, and the average removal rate of Co exceeds 80%. It is reliable for the proposed numerical simulation and evaluation method because of the well goodness of fit between predicted value and actual values: The predicted values and actual values of the abrasive distribution diameter are Ф57 and Ф55; the total coverage rate is 26.42% and 23.50%; the average impact velocity is 81.73 m/s and 78.00 m/s. Further analysis shows that the impact distance has a significant impact on the distribution of abrasive particles on the target surface, the coverage rate of the core area increases at first, and then decreases with the increase of the impact distance of the nozzle, which reach a maximum of 14.44% at 300 mm. It is recommended to set the impact distance around 300 mm, because at this time the core area coverage of the abrasive is the largest and the impact velocity is stable at the highest speed of 81.94 m/s. The impact of the nozzle inlet pressure on the decontamination effect mainly affects the impact kinetic energy of the abrasive and has little impact on the distribution. The greater the inlet pressure, the greater the impact kinetic energy, and the stronger the decontamination ability of the abrasive. But in return, the energy consumption is higher, too. For the decontamination of radioactively contaminated metals, it is recommended to set the inlet pressure of the nozzle at around 0.6 MPa. Because most of the Co elements can be removed under this pressure. Increasing the mass and flow of abrasives appropriately can enhance the decontamination effectiveness. The total mass of abrasives per unit decontamination area is suggested to be 50 g because the core area coverage rate of the abrasive is relatively large under this condition; and the nozzle wear extent is acceptable.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2005년도 추계학술발표대회 논문집
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• pp.31-34
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• 2005

For the damage tolerance improvement of conventional laminated composites, stitching process has been utilized for providing through-thickness reinforcements. 2D prefonl1S were stacked with S-2 glass plain weave, and 3D preforms were fabricated using the stitching process. For the matrix system, epoxy and phenol resins were considered. To examine the damage resistance performance the low velocity drop weight impact test has been carried out, and the impact damage was examined by scanning image. CAI (Compressive After Ih1paet) tests were also conducted to evaluate residual compressive strength. Compared with 2D epoxy composites, 2D phenol composites showed drastic reduction in the compressive strength prior to impact because of the higher contents of voids. The damage area of 2D phenol composites were also larger than that of 2D epoxy composites. However, by introducing the stitching, the damage area of 3D phenol composites was reduced by 60%, while the CAI strength improvement was negligible.

• Journal of Forest and Environmental Science
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• 제36권3호
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• pp.233-242
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• 2020

The Lake (Victoria) zone of Tanzania, which has the least forest resources in the country, is a potential economic growth zone in the country. Therefore, this study analyses the impact of implemented forest policies on the status of forest resources in the area, given the unique features. The study identifies the status of forested lands in the area, and then fits binary logistic regression to identify the impact of policies related elements (i.e. type of forest, type of management) on the status; forest area and location (region) are used as control variables. Results show that 63% of the forested land in the area is destructed; main activities being agriculture, residential, firewood, and charcoal burning activities. Logistic results showed natural forests, forests located in Geita region, forests managed by municipal councils are more likely to be destructed; while plantation forests, forests located in Kagera region, privately managed forests are less likely to be destructed. Thus, the study concludes that policies and measures are not enough for the preservation of forest resources in the area; some of the economic activities in the area are occurring at the expenses of the forests; hence recommend more sustainable development plans and incorporating different crossing cutting sectors in the policies.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2005년도 춘계학술발표대회 논문집
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• pp.71-75
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• 2005

For the damage tolerance improvement of conventional laminated composites, stitching process have been utilized for providing through-thickness reinforcements. 2D preforms were stacked with S-2 glass plain weave and S-2 glass MWK (Multi-axial Warp Knit) L type. 3D preforms were fabricated using the stitching process. All composite samples were fabricated by RTM (Resin Transfer Molding) process. To examine the damage resistance performance the low speed drop weight impact test has been carried out. For the assessment of damage after the impact loading, specimens were examined by scanning image. CAI (Compressive After Impact) tests were also conducted to evaluate residual compressive strength. Compared with 2D composites, the damage area of 3D composites was reduced by 20-30% and the CAI strength showed 5-10% improvement.

• 환경영향평가
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• 제21권5호
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• pp.789-799
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• 2012

The major causes of environmental and social conflicts were analyzed through the samples of the construction and the management for tidal power plant abroad and inland. Based on the results, the eco-friendly and socially acceptable policy instruments for decreasing the scope and intensity of the conflicts were explored. Regarding environment issues, it was found that the tidal power project resulted in decreasing in tidal range and area of intertidal zone and in damaging to tidal flat and wetland conservation area. Also there are the characteristic change of tidal current and biological effect, etc. The major environmental and social conflicts were resulted from the distrust of environmental results to environmental impact assessment and prior environmental review and the distrust of project feasibility study, and insufficient activities of public participation. In this study, introduction to joint fact-finding(JFF) was reviewed as the measure of minimizing environmental and social conflicts.

• Structural Engineering and Mechanics
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• 제60권5호
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• pp.829-849
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• 2016

In this paper, experimental as well as numerical analysis of Glass Fiber Reinforced Polymer (GFRP) laminated composite has been presented under ballistic impact with varying projectile nose shapes (conical, ogival and spherical) and incidence velocities. The experimental impact tests on GFRP composite plate reinforced with woven glass fiber ($0^{\circ}/90^{\circ}$)s are performed by using pneumatic gun. A three dimensional finite element model is developed in AUTODYN hydro code to validate the experimental results and to study the ballistic perforation characteristic of the target with different parametric variations. The influence of projectile nose shapes, plate thickness and incidence velocity on the variation of residual velocity, ballistic limit, contact force-time histories, energy absorption, damage pattern and damage area in the composite target have been studied. The material characterization of GFRP composite is carried out as required for the progressive damage analysis of composite. The numerical results from the present FE model in terms of residual velocity, absorbed energy, damage pattern and damage area are having close agreement with the results from the experimental impact tests.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집A
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• pp.244-249
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• 2000

Recently, composite material which has much excellent mechanical characteristics has been applied in many industries. However, it has a brittle characteristic under impact event. Especially, its invisible characteristics of the damaged area has been the motivation of many engineers investigation, and the nonlinearity of the impact mechanism is one of the main reason to assume the damaged area too simple. The damage mechanism of the composite laminated plate subjected to low velocity impact using ABAQUS/Standard & user subroutine was presented here.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2019년도 춘계 학술논문 발표대회
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• pp.65-66
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• 2019

In this study, flexural strength and impact resistance were evaluated to investigate the fiber length effect of amorphous metallic fiber. As a result, in the case of 30AFRCC, cutoff behavior due to excellent bonding performance by large specific surface area has greatly influence on the flexural and impact resistance performance. In the case of 15AFRCC, the bonding efficiency is relatively low, because the specific surface area is smaller than that of 30AFRCC and the number of fiber is large, so the effect of improving the flexural and impact resistance performance is smaller than that of 30AFRCC.

• International Journal of Advanced Culture Technology
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• 제11권2호
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• pp.381-388
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• 2023

Small-scale environmental impact assessments have limitations in terms of survey duration and evaluation resources, which can hinder the assessment and analysis of the current situation. In this study, we propose the use of drone technology during the environmental impact assessment process to supplement these limitations in the current situation analysis. Drone photography can provide rapid and accurate high-resolution images, allowing for the collection of various information about the target area. This information can include different types of data such as terrain, vegetation, landscape, and real-time 3D spatial information, which can be collected and processed using GIS software to understand and analyze the environmental conditions. In this study, we confirmed that terrain and vegetation analysis and prediction of the target area using drone photography and GIS analysis software is possible, providing useful information for environmental impact assessments.