• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.5
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• pp.35-42
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• 2014

Thermal analysis properties and adhesive properties of self-healing agents were evaluated through differential scanning calorimetry, reaction heat measurement, and adhesive shear test. D1E0, D3E1, D1E1, D1E3, and D0E1, depending on the mixing ratio of DCPD and ENB, were considered as self-healing agents. The amount of Grubbs' catalyst, depending on the type of self-healing agents, was varied from 0.1 wt% to 1.5 wt%. In the case of DCPD, the polymerization reaction occurred faster and the stabilized adhesive strength increased as the amount of catalyst increased; however, a large amount of catalyst was required. ENB had excellent reactivity with a small amount of the catalyst; however, high reaction heat was observed at the early stage of polymerization. Thermal analysis properties and adhesive properties of self-healing agents can be controlled by varying a mixing ratio of DCPD and ENB. Among the self-healing agents used for this study, the D3E1 would be one of the most preferable candidates with regard to maximum adhesive strength, reaching time to maximum adhesive strength, stabilized adhesive strength, and reaction heat.

• Journal of the Korean Institute of Landscape Architecture
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• v.40 no.6
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• pp.173-179
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• 2012

The experiments, which analyze the injury symptoms and diagnose growth conditions utilizing IRVT and analyzing each parts of H. helix L., had been held under a low temperature. Greenhouse and outdoor growing Genus hedera had been prepared and compared with each Genus hedera's peak and bottom leaves' surface temperature under the experimental categories $-6^{\circ}C$ and $-12^{\circ}C$. As results, analyzing the surface thermal property of peak part leaves' of outdoor growing Genus hedera, at experimental categories $-6^{\circ}C$, $-12^{\circ}C$ were ranged from $-2^{\circ}C{\sim}-7^{\circ}C$ and $-2^{\circ}C{\sim}-15^{\circ}C$. On the other hand, the surface thermal property of bottom part leaves at experimental categories $-6^{\circ}C$, $-12^{\circ}C$ were ranged $-2^{\circ}C{\sim}-11^{\circ}C$ and $-1^{\circ}C{\sim}-12^{\circ}C$. It appears that the thermal properties of leaves' surface on $-6^{\circ}C$ peaks and $-12^{\circ}C$ bottoms were more broadband than bottoms and peaks. It means that the peaks were more sensitive than bottoms, as like $-2^{\circ}C{\sim}-15^{\circ}C$, $-1{\sim}-12^{\circ}C$. Moreover, as similar results had seen to leaves surface temperature added to cold wind conditions. How the cold wind damaged the outdoor growing Genus hedera, analyzed the surface thermal property by IRVT data under $0^{\circ}C$, $-2^{\circ}C$, $-4^{\circ}C$ condition, it resulted to $-6.2^{\circ}C$, $-6.8^{\circ}C$, $-7.5^{\circ}C$. It appeared more $3.5{\sim}6.2^{\circ}C$ low temperature than experimental setting point. In addition, each parts thurmal property of peaks and bottoms was not similar, it referred to each parts' sensitivities of low temperature were different on the peak and bottom leaves surface temperature.

• The Journal of Korean Academy of Prosthodontics
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• v.49 no.2
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• pp.168-176
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• 2011

Purpose: This study aims at investigating the influence of various insertion torques on thermal changes of bone. A proper insertion torque is derived based on the thermal analysis with two different implant designs. Materials and methods: For implant materials, bovine scapula bone of 15 - 20 mm thickness was cut into 35 mm by 40 - 50 mm pieces. Of these, the pieces having 2 - 3 mm thickness cortical bone were used as samples. Then, the half of the sample was immersed in a bath of $36.5^{\circ}C$ and the other half was exposed to ambient temperature of $25^{\circ}C$, so that the inner and surface temperatures reached $36.5^{\circ}C$ and $28^{\circ}C$, respectively. Two types of implants ($4.5{\times}10\;mm$ Br${\aa}$nemark type, $4.8{\times}10\;mm$ Microthread type) were inserted into bovine scapula bone and the temperature was measured by a thermocouple at 0.2 mm from the measuring point. Finite element method (FEM) was used to analyze the thermal changes at contacting surface assuming that the sample is a cube of $4\;cm{\times}4\;cm{\times}2\;cm$ and a layer up to 2 mm from the top is cortical bone and below is a cancellous bone. Boundary conditions were set on the basis of the shape of cavity after implants. SolidWorks was used as a CAD program with the help of Abaqus 6.9-1. Results: In the in-vitro experiment, the Microhead type implant gives a higher maximum temperature than that of the Br${\aa}$nemark type, which is attributed to high frictional heat that is associated with the implant shape. In both types, an Eriksson threshold was observed at torques of 50 Ncm (Br${\aa}$nemark) and 35 Ncm (Microthread type), respectively. Based on these findings, the Microthread type implant is more affected by insertion torques. Conclusion: This study demonstrate that a proper choice of insertion torque is important when using a specific type of implant. In particular, for the Microthread type implant, possible bone damage may be expected as a result of frictional heat, which compensates for initial high success rate of fixation. Therefore, the insertion torque should be adjusted for each implant design. Furthermore, the operation skills should be carefully chosen for each implant type and insertion torque.

• Tunnel and Underground Space
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• v.30 no.4
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• pp.306-319
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• 2020

Characterizations of Excavation Damage Zone (EDZ), which is hydro-mechanical degrading the host rock, are the important issues on the geological repository for the spent nuclear fuel. In the DECOVALEX 2019 project, Task G aimed to model the fractured rock numerically, describe the hydro-mechanical behavior of EDZ, and predict the change of the hydraulic factor during the lifetime of the geological repository. Task G prepared two-dimensional fractured rock model to compare the characteristics of each simulation tools in Work Package 1, validated the extended three-dimensional model using the TAS04 in-situ interference tests from Äspö Hard Rock Laboratory in Work Package 2, and applied the thermal and glacial loads to monitor the long-term hydro-mechanical response on the fractured rock in Work Package 3. Each modelling team adopted both Finite Element Method (FEM) and Discrete Element Method (DEM) to simulate the hydro-mechanical behavior of the fracture rock, and added the various approaches to describe the EDZ and fracture geometry which are appropriate to each simulation method. Therefore, this research can introduce a variety of numerical approaches and considerations to model the geological repository for the spent nuclear fuel in the crystalline fractured rock.

• Horticultural Science & Technology
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• v.29 no.2
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• pp.81-86
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• 2011

The effects of girdling on fruit quality and cold resistance of 'Kyoho' grapes were investigated. Girdling treatment was conducted on the trunk at 10 cm above ground with 1 cm width and grapes were harvested at 90 and 110 days after full bloom to compare the fruit quality. First harvesting rate in girdling treatment was higher than that in non-girdling treatment and coloration was also higher in girdled vines at the final harvest. In other words, coloring process of grape was promoted and enhanced by girdling, but this effect of coloring improvement was decreased after successive girdling treatment. Fruit quality showed no difference between the treated and non-treated berries, but fruit cracking rate was lower in girdled treated berries. Girdled trees were weakened and suffered from freezing damage. Especially, most grapevines withered up after being girdled for three consecutive years. Although girdling had effect on improving the berry coloring significantly, the effect wore off with continuous girdling. And it was possible that consecutive girdling leaded to wither and growth suppression especially in grapevines. These adverse effects may make the continuous girdling technique unsuitable in practice for 'Kyoho' grape.

• Journal of the Korean Geographical Society
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• v.51 no.5
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• pp.633-649
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• 2016

Exposure to high temperatures during the reproductive period of crops decreases their productivity. The Intergovernmental Panel on Climate Change's (IPCC) fifth Assessment Report predicts that the frequency of high temperatures will continue to increase in the future, resulting in significant impacts on the world's food supply. This study evaluate climate change-induced heat stress on four major agricultural crops (rice, maize, soybean, and wheat) at a global level, using the coupled atmosphere-ocean model of Hadley Centre Global Environmental Model version 2 (HadGEM2-AO) and FAO/IIASA Global Agro-Ecological Zone (GAEZ) model data. The maximum temperature rise ($1.8-3.5^{\circ}C$) during the thermal-sensitive period (TSP) from the baseline (1961-1990) to the future (2070-2090) is expected to be larger under a Representative Concentration Pathway (RCP) 8.5 climate scenario than under a RCP2.6 climate scenario, with substantial heat stress-related damage to productivity. In particular, heat stress is expected to cause severe damage to crop production regions located between 30 and $50^{\circ}N$ in the Northern Hemisphere. According to the RCP8.5 scenario, approximately 20% of the total cultivation area for all crops will experience unprecedented, extreme heat stress in the future. Adverse effects on the productivity of rice and soybean are expected to be particularly severe in North America. In Korea, grain demands are heavily dependent on imports, with the share of imports from the U.S. at a particularly high level today. Hence, it is necessary to conduct continuous prediction on food security level following the climate change, as well as to develop adaptation strategy and proper agricultural policy.

• Korean Journal of Agricultural and Forest Meteorology
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• v.16 no.3
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• pp.213-218
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• 2014

Effects of elevated $CO_2$ on leaf phenology of Quercus acutissima were examined using open-top chambers, which had ambient and elevated $CO_2$ concentrations (ambient ${\times}1.4$, ambient ${\times}1.8$). To analyze the effect of chamber, non-treatment block was established near outside of the chambers. In 2013, budburst, leaf unfolding, coloring, and shedding were surveyed, and spring phenology was surveyed in 2014. Thermal sum (base temperature $+5^{\circ}C$) of each phenological event occurred was recorded. In addition, bud samples were collected and analyzed for carbohydrate contents in March 2014. Elevated $CO_2$ concentration advanced budburst and leaf unfolding, and delayed shedding in 2013. However, in 2014, the temperature of the spring season was high, and there was no significant effect of elevated $CO_2$ concentration on spring phenology. Carbohydrates content, such as starch, total non-structural carbohydrate and total soluble sugar, were significantly increased in response to elevated $CO_2$ concentration. It has been proposed that elevated $CO_2$ concentration could extend the growing season of temperate species with increased possibility of frost damage due to early bud opening and leaf unfolding. However, our analysis showed that the increased carbohydrate concentration in bud under elevated $CO_2$ would reduce the possibility of early spring frost damage by acting as cryoprotectant.

• Journal of the Korean Institute of Gas
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• v.3 no.1
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• pp.21-26
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• 1999

Chemical plant's fire and explosion does not only damage to the chemical plants themselves but also damage to people in or near of the accident spot and the neighborhood of chemical plant. For that reason, Chemical process safety management has become important. One of safety management methods is called 'the quantitative analysis', which is used to reduce and prevent the accident. The results of the quantitative analysis could be used to arrange the equipments, evaluate the minimum safety distance, prepare the safety equipments. In this study we make the computer program to make easy to do Quantitative analysis of the accident. The output of the computer program is the magnitude of fire(pool fire and fireball) and explosion(UVCE and BLEVE) effects. We used the thermal radiation as a measure of fire magnitude and used the overpressure as a measure of explosion magnitude. In case of BLEVE, the fly distance of fragment can be evaluated. Also probit analysis was done in every case. As the case study, Buchun LPG explosion accident in Korea was analysed by the program developed. The simulation results showed that the permissible distance was 800m and probit analysis showed that 1st degree bum, 2nd degree burn, and death distances are 450, 280, 260m, respectively the simulation results showed the good agreement with the results from SAFER PROGRAM made by Dupont.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.16 no.2
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• pp.243-260
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• 2018

A literature review on the effects of high temperature and radiation on radiation shielding concrete in Spent Fuel Dry Storage is presented in this study with a focus on concrete degradation. The general threshold is $95^{\circ}C$ for preventing long-term degradation from high temperature, and it is suggested that the temperature gradient should be less than $60^{\circ}C$ to avoid crack generation in concrete structures. The amount of damage depends on the characteristics of the concrete mixture, and increases with the temperature and exposure time. The tensile strength of concrete is more susceptible than the compressive strength to degradation due to high temperature. Nuclear heating from radiation can be neglected under an incident energy flux density of $10^{10}MeV{\cdot}cm^{-2}{\cdot}s^{-1}$. Neutron radiation of >$10^{19}n{\cdot}cm^{-2}$ or an integrated dose of gamma radiation exceeding $10^{10}$ rads can cause a reduction in the compressive and tensile strengths and the elastic moduli. When concrete is highly irradiated, changes in the mechanical properties are primarily caused by variation in water content resulting from high temperature, volume expansion, and crack generation. It is necessary to fully utilize previous research for effective technology development and licensing of a Korean dry storage system. This study can serve as important baseline data for developing domestic technology with regard to concrete casks of an SF (Spent Fuel) dry storage system.

• Journal of Environmental Impact Assessment
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• v.28 no.3
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• pp.312-331
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• 2019

An offshore waste disposal facility refers to a landfill site for final landfilling of stabilized inorganic solid waste such as land and marine waste incineration materials, and the aim of such a facility is to solve the problem of insufficient waste disposal space on land and create and develop environmentally friendly marine spaces. The purpose of this study is to prepare guidelines for the construction of offshore waste disposal facilities, which reflect the need and importance of paying sufficient heed to environmental considerations from the initial stage of the project, in order to investigate, predict, and assess how such guidelines will affect the marine environment in relation to the construction of offshore waste disposal facilities, with the goal of minimizing the impact on and damage to the environment. For the purpose of this research, guidelines focusing on the construction of offshore waste disposal facilities were derived through an analysis of domestic cases and similar foreign cases and an assessment of their level of compliance with existing EIA guidelines through the operation of a discussion forum. In order to review the EIA report on similar cases in Korea, 17 EIA documents (2005~2016) for dredged soil dumping areas and ash ponds of thermal power plants were analyzed to investigate the status of marine organisms, marine physics, marine water quality, and marine sediment and to understand what types of problems can occur and what improvement measures can be taken. The purpose of these guidelines were to minimize damage to the marine environment by promoting EIA protocols in accordance with scientific and systematic procedures, to reduce the consultation period related to projects, to resolve social conflicts, and to reduce economic costs.