• Applied Chemistry for Engineering
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• v.7 no.3
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• pp.597-604
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• 1996

Resin-type neutron shielding materials, KNS-115A, 115B and 115C have been fabricated to be used for spent fuel shipping cask. The base material is epoxy resin, and polypropylene, aluminium hydroxide and boron carbide are added. These shielding materials offer good fluidity at processing, which makes it possible to apply this resin shield to complicated geometric shapes such as shipping cask. Several measurements were made for the shielding materials to evaluate the shielding property, combustion characteristics, fire resistance, thermal and mechanical properties. The neutron shielding ability of the shielding materials is estimated to be better than that of foreign's shielding material, NS-4-FR, due to higher hydrogen atomic density. Other properties of the shielding materials are as follows: Onset temperatures; $267{\sim}270^{\circ}C$, thermal conductivities; $0.62{\sim}0.72W/m{\cdot}K$, combustion characteristics; <$800^{\circ}C$, ATB(average time of burning); <5sec, AEB(average extent of burning) ; <5mm, tensile strengths; $2.3{\sim}3.0kg/mm^2$, compressive strengths; $5.3{\sim}13.3kg/mm^2$, flexural strengths; $4.4{\sim}5.4kg/mm^2$.

• Korean journal of food and cookery science
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• v.17 no.4
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• pp.391-398
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• 2001

This study was carried out to investigate the effects of storage temperature(5$\^{C}$ and 25$\^{C}$) and time(1, 24, 48 and 72hours) on the retrogradation characteristics of mungbean starch gels by using differential scanning calorimeter, rapid visco-analyzer, $\beta$-amylase method, X-ray diffractometer and scanning electron microscope. Endothermic peaks of gels stored at 5$\^{C}$ were shifted to the lower temperature than those stored at 25$\^{C}$ and endothermic enthalpy of gels stored at 5$\^{C}$ was greater than that stored at 25$\^{C}$. DSC thermograms showed that the retrogradation rate of gels stored at 5$\^{C}$ was higher than that shored at 25$\^{C}$. The pasting properties of the gels such as peak viscosity and final viscosity increased with increasing storage time except the gels stored at 25$\^{C}$ for 72 hours and this trend was more apparent at the storage temperature of 5$\^{C}$. The digestibility measured by $\beta$-amylase method decreased with increasing storage time and this trend was more apparent at the storage temperature of 5$\^{C}$. X-ray diffraction patterns of the gels stored at 5$\^{C}$ showed more distinct peak than those stored at 25$\^{C}$, but no difference was detected by the storage time. The microstucture of all the gels showed a well developed three dimensional network The network structure of the gels stored at 25$\^{C}$ formed a thick matrix after 72 hours and those stored at 5$\^{C}$ from the early stage of storage.

• Korean Journal of Agricultural and Forest Meteorology
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• v.1 no.2
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• pp.119-126
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• 1999

A numerical model using soil surface energy balance and soil heat flow equations to estimate mulched soil temperature was developed. The required inputs data include weather data, such as global solar radiation, air temperature, wind speed, atmospheric water vapor pressure, the optical properties of mulching material, and soil physical properties. The observed average soil temperature at 50 cm depth was used as the initial value of soil temperature at each depth. Soil temperature was simulated starting at 0 hour at an interval of 10 minutes. The model reliably described the variation of soil temperature with time progress and soil depth. The correlation between the estimated and measured temperature yielded coefficient values of 0.961, 0.966 for 5cm and 10cm depth of the bare soil, respectively, 0.969, 0.965 for the paper mulched soil, and 0.915, 0.938 for the black polyethylene film mulched soil. The percentages of absolute differences less than 2$^{\circ}$C between soil temperatures measured and simulated at 10 minute interval were 97.4% and 98.5% for 5 cm and 10cm for the bare soil, respectively, and 95.8% and 97.4% for the paper mulched soil, and 70.1% and 92.5% for the polyethylene film mulched soil. The results indicated that the model was able to predict the soil temperature fairly well under mulched condition. However, in the night time, the model performance was a little poor as compared with day time due to the difficulty of accurate determination of the atmospheric long wave radiation.

• Journal of the Korean Magnetics Society
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• v.26 no.6
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• pp.179-184
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• 2016

For an industrial spin-transfer torque (STT) MRAM, low switching current and high thermal stability are required, simultaneously. For this point of view, it is essential to find magnetic materials which satisfy high spin polarization and strong perpendicular magnetocrystalline anisotropy (MCA). In this paper, we investigate electronic structures and MCA energies of perovskite $CoFeX_3$ (X = O, F, S, Cl). For X = F and Cl, spin polarization at the Fermi level are 97 % and 96 %, respectively, which are close to a half metal. Furthermore, Co-terminated 5-monolayer (ML) $CoFeX_3$ (X = O, F, S, Cl) films show perpendicular MCA. In particular, the MCA energy of the Co-terminated $CoFeCl_3$ is about 1.0 meV/cell which is three times larger than that of a 5-ML CoFe film. Therefore, we expect to realize a magnetic material with high spin polarization and strong perpendicular MCA energy by utilizing group 6 and 7 elements in the periodic table, and to contribute to commercializing of the STT-MRAM.

• Applied Chemistry for Engineering
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• v.28 no.1
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• pp.80-86
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• 2017

In this study, nitrogen functional groups were introduced on graphite fiber (GF) to modify their electrical properties, and heating properties were investigated according to the treatment conditions. GF was prepared by a thermal solid-state reaction at $200^{\circ}C$ for 2 h. Surface properties of the nitrogen doped GF were examined by XPS, and its resistance and heating temperature were measured using a programmable electrometer and thermo-graphic camera, respectively. The XPS result showed that the nitrogen functional groups on the GF surface were increased with increasing of urea contents, and the heating property of the GF was also improved as nitrogen functional groups were introduced. The maximum heating temperature of GF treated by urea was $53.8^{\circ}C$ at 60 V, which showed 55% improved heating characteristics compared to that of non-treated GF. We ascribe this effect to introduced nitrogen functional groups on the GF surface by thermal solid-state reaction, which significantly affects the heating characteristics of GF.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2012.11a
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• pp.32-32
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• 2012

화석연료의 남용으로 지구 온난화가 심화되어 환경과 생태계변화가 가속화되고 있고, 급속한 산업의 발달과 인류 삶의 질 향상에 따른 에너지 수요가 급증하고 있는 실정에 있으며, 일본 후쿠시마 원전사태로 원자력 에너지의 위험성으로 지구 인류환경은 심각한 국면을 맞이 하고 있어 대체 에너지의 하나로 핵융합 에너지 필요성이 증대되고 있다. 핵융합 에너지 연구 개발은 우리나라에서 KSTAR가 1997년부터 건설하기 시작하여 지난 2007년에 완공되어 지금 운용 중에 있고, 국제적으로 미국, EU, 러시아, 중국, 한국, 일본 인도가 참여하는 ITER 국제 공동프로젝트가 2004년에 건설을 시작하여 프랑스 카다라쉬에 실증 플란트를 건설 중에 있다. 이러한 핵융합 반응을 위해서는 10e-7이상의 높은 진공과 1억$^{\circ}C$ 이상에서 중수소와 삼중수소가 반응하여 발생하는 플라즈마를 제어 할 필요가 있으며, 초고온의 핵융합 플라즈마를 가두고 가동시키기 위해서는 약 12Tesla이상의 고자장 마그넷이 필요하다. 현재 ITER 실증 플란트에 사용되는 고자장 마그넷은 TF (Toroidal Field)코일과 CS (Central Field)코일에 Nb3Sn 초전도선재가 핵심부품으로 사용되고 있으며 ITER프로젝트에서는 약 850톤의 Nb3Sn 초전도선재가 사용될 전망이다. 그 중에서 일본 25%, EU, 러시아와 한국이 각각 20%, 중국7%, 미국8% 할당되어 참여국 대부분은 초전도선재를 전략적으로 공급하고 있다. 초전도 선재의 크롬도금은 1~2 마이크로미터 이하의 균일하고 얇은 도금 두께와 밀착성이 우수한 품질이 요구된다. 일반적으로 크롬도금은 산업현장에서 컨베이어 벨트 방식으로 장식이나, 내식성 및 내마모성의 특성을 필요로 할 때 사용되고 있으나, 선재에 크롬도금을 릴투릴(Reel to Reel) 방식으로 적용되는 경우는 세계적으로 아주 드물다. 핵융합 마그넷의 CICC(Conduct In Cable Conduit)도체를 만들기 위해서는 초전도선재를 이용, 3(Sc 2+OFC 1)$^*3^*5^*5^*6$형태로 연선과 케이블링을 하게 되며, 초전도 선재를 연선하고 케이블링을 할 때 크롬 도금층이 박리될 가능성이 있어 크롬도금 방법과 프로세스를 특별히 고안할 필요가 있다. ITER핵융합로 마그넷의 TF코일은 높이 14m, 폭 9m 최대자장 12Tesla, 최대전류 68kA, CICC도체 직경이 40mm로서 그 초전도 조관/도체 내부에 0.82mm 직경의 Nb3Sn 초전도 선재가 약 1350가닥으로 연선과 케이블링으로 구성되어 있다. ITER 핵융합 마그넷용 초전도 선재의 크롬도금은 마그넷 권선 후 Nb3Sn 초전도물질을 형성하기 위해서 $650^{\circ}C$에서 500시간 열처리를 실시하며 열처리 시 초전도 선재의 소선들 사이에 발생할 수 있는 소착을 방지하고, 초전도 선재에서 발생하는 AC loss를 감소시키며, Quench시 발생되는 열을 쉽게 확산시킴으로써, 초전도 마그넷의 열적 안정성(Thermal Stability) 향상과 필요에 따라서 소선간 통전울 가능하게 한다. 고려제강의 자회사인 케이에이티는 크롬도금 밀착성이 우수하고 도금두께 0.1마이크로 미터 이내 제어가 가능한 얇고 균일한 도금품질을 개발하여 한국형 핵융합 실험로인 KSTAR에 65톤 전량 공급하였고, 크롬 도금된 무산소동 선재 32톤과 초전도 선재 93톤을 전량 ITER 프로젝트에 공급하고 있으며, 2013년도 상반기에는 공급을 마무리할 예정이다.

• Journal of the Institute of Convergence Signal Processing
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• v.19 no.2
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• pp.61-67
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• 2018

Welding preheating means that the surface of the base material to which the metal is welded before the main welding is heated to a constant temperature. It prevents the cracks of the adjacent influences such as reduction of material hardening degree by controlling the cooling rate, suppression of segregation of impurities, prevention of thermal deformation, and moisture removal. For this reason, it is a necessary operation for high quality welding. Induction heating is an efficient heating method that converts electric energy into heat energy by applying electromagnetic induction phenomenon. Compared with combustion heat generated by gas and liquid, it is clean, stable, and economical as well as rapid heating. It can be heated regardless of the shape, depth and material of the heating body by modifying the shape of the frequency and the coil with a simple structure. In this paper, we implemented a low frequency welding preheating system using induction heating technique and observed the temperature changes of coil resistance, inductance and automotive transmission parts according to the height of each transmission in winding coil for three kinds of automotive transmission parts. We confirmed that the change of current is a very important factor in the low frequency heating.

• Journal of Korean Society for Geospatial Information Science
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• v.23 no.2
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• pp.3-9
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• 2015

Since changes in land use in urban space cause traffic volume and it is closely related to traffic accidents. Therefore, an analysis on the causes of traffic accidents is judged to be an essential factor to establish the measure to reduce traffic accidents. In this regard, the analysis was conducted on the clustering by using the nearest neighbor indexes with regard to the occurrence frequencies of commercial and residential zone based on traffic accident data of the past five years (2009-2013) with the target of local small-medium sized city, Jinju-si. The analysis results, obtained in this study, are as follows: the occurrence frequency of traffic accidents was the highest in spring and the lowest in winter respectively. The clustering of traffic accident occurrence at nighttime was stronger than at daytime. In addition, terms of the analysis on the clustering of traffic accident according to land use, changes according to the seasons was not significant in commercial areas, while clustering density in winter tended to become significantly lower in residential areas. The analysis results of traffic accident types showed that the side-right angle collision of cars was the highest in frequency occurrence, and widespread in both commercial areas and residential areas. These results can provide us with important information to identify the occurrence pattern of traffic accidents in the structure of urban space, and it is expected that they will be appropriately utilized to establish measures to reduce traffic accidents.

• Journal of the Korean Geographical Society
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• v.48 no.5
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• pp.651-666
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• 2013

The objective of this study is to introduce the characteristics and establishing process of national regional policy for the sunbelt developmentr initiative of the southern coastal area in Korea. Discussion on the development of southern coastal area of Korea with some members of the Korea Society of Future Studies began in the early 1990s, and its discussion was continued with the activities by the Committee on Regional Unity of the Grand National Party and Namhaean Forum. The sunbelt development initiative was selected as one of the major commitments of the Grand National Party in the 17th presidential election of Korea. Since the launching of the Lee Myung-bak government, the Presidential Committee on Balanced National Development made a comprehensive plan for sunbelt development of southern coastal area(CPSD), and this plan was confirmed by central governmental planning in May 2010. CPSD is meaningful in terms of the fir first national regional planning and legal plan in Korea. The target year of CPSD is 2020, and some projects by CPSD started in 2010. However, there are many negative views that CPSD will not be going too well. Therefore, new efforts and roles of geographers who participated in the process of planning of CPSD are required for the success of CPSD.

• Korean Chemical Engineering Research
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• v.50 no.1
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• pp.35-40
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• 2012

In this study, 1-(2-methoxyethyl)-3-methylimidazolium methanesulfonate ionic liquid has been synthesized, characterized and tested with respect to carbon dioxide absorption with the aim to use it as advanced absorbent materials in fossil fuel processing. The ionic liquid was synthesized by a one step method, low cost. The thermal and chemical stability of selected ionic liquid has been investigated by DSC, TGA and the structure was verified by $^1H$-NMR spectroscopy. The solubility of carbon dioxide in the methanesulfonate-based ionic liquids were measured using a high-pressure equilibrium apparatus equipped with a variable-volume view cell at 30, 50 and $70^{\circ}C$ and pressure up to 195 bar. The results show that carbon dioxide solubilities of 1-(2-methoxyethyl)-3-methylimidazolium methanesulfonate increased with pressure increasing and temperature decreasing, and the carbon dioxide absorption capacity showed 27.6 $CO_2/IL$(g/kg) at $30^{\circ}C$, 13 bar.