• Membrane Journal
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• v.24 no.4
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• pp.285-291
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• 2014

The PTMSP[Poly(1-trimethylsilyl-1-propyne)]-NaY zeolite composite membranes were prepared by adding 0~50 wt% NaY zeolite to PTMSP. In order to investigate the characteristics of these membranes, we used the analytical methods such as FT-IR, $^1H$-NMR, GPC, DSC, TGA, and SEM. Gas permeation experiments were carried out at $23{\sim}26^{\circ}C$, $2kgf/cm^2$, and the permselectivity of $H_2$ and $N_2$ gases through the composite membranes was studied as a function of the NaY zeolite contents. According to TGA measurements, when NaY zeolite was inserted within the PTMSP, thermal stability of PTMSP was enhanced. Based on SEM observation, NaY zeolite was dispersed in the PTMSP-NaY zeolite composite membrane with a size of $1.5{\mu}m$. The permeability of $H_2$ and $N_2$ through the PTMSP-NaY zeolite composite membranes increased as NaY zeolite content increased. On the contrary, the selectivity($H_2/N_2$) of the PTMSP-NaY zeolite composite membranes decreased as zeolite content increased.

• Membrane Journal
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• v.27 no.2
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• pp.154-166
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• 2017

Polymeric films for gas barrier applications such as food packaging and electronic devices have attracted great interest due to their cheap, light and easy processability among gas barrier materials. Especially in electronic devices, extremely low gas permeance is necessary for maintaining the device performance. However, current polymeric barrier films still suffer from relatively high gas permeance than other materials. Therefore, there have been strong needs to enhance the gas barrier performance of polymeric barrier films while keep their own advantages. Recently, graphene is highlighted as a 2D-layered material for gas barrier applications. However, owing to the poor workability and difficulty to produce in engineering scale, graphene oxide (GO) is on the rise. GO consists of oxygen-containing functional groups on surface with intrinsic 2D-layered structure and high aspect ratio, and it can be well-dispersed in aqueous polar solvents like water, resulting in scalable mass production. Here, we prepared GO incorporated polyimide (PI) nanocomposites. PI is widely used barrier polymer with high mechanical strength and thermal and chemical stability. We demonstrated that PI/GO nanocomposites could perform as a gas barrier. Furthermore, surfactants (Triton X-100 (TX) and Sodium deoxycholate (SDC)) are introduced to enhance the gas barrier performance by improving the degree of dispersion of GO in PI matrix. As a result, TX enhanced the gas barrier performance of PI/GO nanocomposites which is similar to predicted value. This finding will provide new insight to polymer nanocomposites for gas barrier applications.

• Journal of the Mineralogical Society of Korea
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• v.16 no.4
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• pp.295-305
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• 2003

This study aims to provide the physicochemical properties of three kinds of organo­smectites which can be diversely used in industries. Some properties of them were compared with Na­smectite. Three kinds of organo­smectites such as Hexadecyltrimethylammonium(HDTMA), Benzyldimethyltetradecylammonium(BDTDA), and Cetylpyridinium(CP) exchanged smectites were manufactured for this study. Three types of organo­smectites showed the alkaline character(pH 9), very low swelling property and viscosity, and a fast flocculation behavior because of strong hydrophobic property in contrast to hydrophilic Na­smectite. Three organo­smectites showed the strong interlayer expansion with basal spacing from $19\AA$ to $23\AA$ compared with the Na­smectite of about 12 $\AA$. Organic cations such as HDTMA, BDTDA, and CP exchanged into smectite were completely decomposed in the temperature range from $250^{\circ}C$ to $400^{\circ}C$. Generally, three organo­smectites showed the similar mineralogical, physicochemical and thermal properties. But their properties are quite different from Na­smectite. Considering economically, CP exchanged smectite would be used for the diverse utilization field in the future time.

• Journal of the Mineralogical Society of Korea
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• v.24 no.2
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• pp.101-110
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• 2011

Charcoal burning in the process of manufacture and ordinary use often release many constituent chemical species. As a result of open burning, the chemical composition as well as the physical properties of original material changes through the modification of surface properties of charcoal. Surface modification could be more responsible toward the outside elements for surface adsorption, it becomes easy to adsorb more toxic elements through surface adsorption. In this study, four kinds of commercially available charcoal were studied against the chemical and thermal stability along with the heavy metals and organic hazardous substances. Thermo gravimetric analysis (TGA) and differential scanning calorimetry, from room temperature to $400^{\circ}C$, were performed to study the weight loss and the changes in the behavior of those substances. According to TGA analysis, about 10% of weight loss was happened before $200^{\circ}C$. It was found that related weight loss of this temperature region may responsible to the gas phase organic matter. Natural charcoal, K1 and C1 show 15% of loss during the reaction heated to $400^{\circ}C$, while the artificial charcoal K2, C2 show the weight loss of about 20% was found. This is consistent with the main organic matter and VOC analysis results shown. Chemical composition based on the x-ray diffraction analysis was carried out. X-ray diffraction analysis reveals the existence of chemical additive in the forms of $Ba(NO_3)_2$, $BaCO_3$, and $NaNO_3$.

• Korean Journal of Materials Research
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• v.2 no.2
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• pp.126-132
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• 1992

Experiment has been performed to investigate the thermal and magnetic properties of Mn-ferrite by electrolysis. Using the 0.2%C mild steel as soluble anode and SUS 304 stainless steel as cathode, Mn-ferrite could be made from the sulfuric acid leaching of the wasted manganese dry cell and $MnSO_4$reagent by electrolysis. As the result of X-ray diffraction, thermal analysis and magnetic measurement, Mn-ferrite was the spinel type in $Mn_{x}Fe_{3-x}O_4$ (X=1), the weight loss rate of $Mn_{x}Fe_{3-x}O_4$ were linearly increased up to the $200^{\circ}C$. Ms, Mr and Hc values were decreased with increasing Mn content and heating temperature. When Mn-ferrite was formed by $MnCl_2$reagent electrolysis, Ms values were higher than those formed from the sulfuric acid leaching of the wasted manganese dry cell and $MnSO_4$reagent by electrolysis. In Mn-ferrite, which was formed from the sulfuric acid leaching of the wasted manganese dry cell by electrolysis, Ms and Mr values were higher, Hc values were lower than which was formed by $MnSO_4$ reagent electrolysis at $200^{\circ}C\;and\;300^{\circ}C, while the same values at $100^{\circ}C$. The shape of particles was spherical type, the sizes of them were about $0.1{\mu}m$ sub-micron in $MnSO_4$reagent electrolysis, $0.5{\mu}m$ in the sulfuric acid leaching of the wasted manganese dry cell by electrolysis.

• Korean Journal of Materials Research
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• v.4 no.2
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• pp.194-205
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• 1994

In this research, we attempt to fabricate an excellent CFRC(Carbon Fiber Reinforced Carbon), which has good thermal and mechanical properties, with 8H/satin woven fabric prepreg, high modulus and high strength type continuous carbon fiber and raw coal tar pitch(RCTP) matrix or THF soluble fraction(THFSP) matrix which has good graphitizability. Green bodies were fabricated with hot press molding technique and CFRC samples were made after carbonization, impregnation, recarbonization and graphitization steps. For the purpose of characterization of the physical properties, SEM, polarized light microscope, TGA were observed, and tested flexural strength, modulus and ILSS. After heat treating the THFSP matrix up to $2300^{\circ}C$, the value of $C_0$/2 was 3.380$\AA$, which is analogous to the structure of natural graphite and the value of 2$\theta$ is $26.276^{\circ}$ approached to the Bragg's angle of natural graphite. As a result of TGA to test the high temperature air oxidation, the THFSP matrix, graphitized up to $2300^{\circ}C$, exhibited the best air oxidation resistance. And mechanical properties were increased up to 65~70% as fiber volume fraction increased. Because of the good orientation graphitizability, the fracture surface of THFSP matrix CFRC is very good.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.83-83
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• 2012

금속 실리사이드는 낮은 비저항, 실리콘과의 좋은 호환성 등으로 배선 contact 물질로 널리 연구되고 있다. 특히 $CoSi_2$는 선폭의 축소와 관계없이 일정하고 낮은 비저항과 열적 안정성이 우수한 특성 등으로 배선 contact 물질로 활발히 연구되고 있다. 금속 실리사이드를 실리콘 평면기판에 형성시키는 방법으로는 열처리를 통한 금속박막과 실리콘 기판 사이에 확산작용을 이용한 SALICIDE (self-algined silicide) 기술이 대표적이며 CoSi2도 이와 같은 방법으로 형성할 수 있다. Co 박막을 증착하는 방법에는 물리적 기상증착법 (PVD)과 유기금속 화학 증착법 등이 보고되어있지만 최근 급격하게 진행 중인 소자구조의 나노화 및 고 단차화에 따라 기존의 증착 기술은 낮은 단차 피복성으로 인하여 한계에 부딪힐 것으로 예상되고 있다. ALD(atomic layer deposition)는 뛰어난 단차 피복성을 가지고 원자단위 두께조절이 용이하여 나노 영역에서의 증착 방법으로 지대한 관심을 받고 있다. 앞선 연구에서 본 연구진은 CoCp2 전구체과 $NH_3$ plasma를 사용하여 Plasma enhanced ALD (PE-ALD)를 이용한 고 순도 저 저항 Co 박막 증착 공정을 개발 하고 이를 SALICIDE 공정에 적용하여 $CoSi_2$ 형성 연구를 보고한 바 있다. 하지만 이 연구에서 PE-ALD Co 박막은 플라즈마 고유의 성질로 인하여 단차 피복성의 한계를 보였다. 이번 연구에서 본 연구진은 Co(AMD)2 전구체와 $NH_3$, $H_2$, $NH_3$ plasma를 반응 기체로 사용하여 Thermal ALD(Th-ALD) Co 및 PE-ALD Co 박막을 증착 하였다. 고 단차 Co 박막의 증착을 위하여 Th-ALD 공정에 초점을 맞추어 Co 박막의 특성을 분석하였으며, Th-ALD 및 PE-ALD 공정으로 증착된 Co 박막의 단차를 비교하였다. 연구 결과 Th-ALD Co 박막은 95% 이상의 높은 단차 피복성을 가져 PE-ALD Co 박막의 단차 피복성에 비해 크게 향상되었음을 확인하였다. 추가적으로, Th-ALD Co 박막에 고 단차 박막의 증착이 가능한 Th-ALD Ru을 capping layer로 이용하여 CoSi2 형성을 확인하였고, 기존의 PVD Ti capping layer와 비교하였다. 이번 연구에서 Co 박막 및 $CoSi_2$ 의 특성 분석을 위하여 X선 반사율 분석법 (XRR), X선 광전자 분광법 (XPS), X선 회절 분석법 (XRD), 주사 전자 현미경 (SEM), 주사 투과 전자 현미경 (STEM) 등을 사용하였다.

• Korean Journal of Agricultural and Forest Meteorology
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• v.22 no.3
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• pp.194-204
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• 2020

Cultivar parameters, which are key inputs to a crop growth model, have been estimated using observation data in good quality. Observation data with high quality often require considerable labor and cost, which makes it challenging to gather a large quantity of data for calibration of cultivar parameters. Alternatively, data in sufficient quantity can be collected from the reports on the evaluation of cultivars by region although these data are of questionable quality. The objective of our study was to assess the quality of crop and management data available from the reports on the regional adaptation trials for rice cultivars. We also aimed to propose the measures for improvement of the data quality, which would aid reliable estimation of cultivar parameters. DatasetRanker, which is the tool designed for quantitative assessment of the data for parameter calibration, was used to evaluate the quality of the data available from the regional adaptation trials. It was found that these data for rice cultivars were classified into the Silver class, which could be used for validation or calibration of key cultivar parameters. However, those regional adaptation trial data would fall short of the quality for model improvement. Additional information on management, e.g., harvest and irrigation management, can increase the quantitative quality by 10% with the minimum effort and cost. The quality of the data can also be improved through measurements of initial conditions for crop growth simulations such as soil moisture and nutrients. In addition, crop model improvement can be facilitated using crop growth data in time series, which merits further studies on development of approaches for non-destructive methods to monitor the crop growth.

• Journal of the Korean association of regional geographers
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• v.11 no.3
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• pp.381-394
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• 2005

There is a little agreement about the characteristics of the company town proposed by the Federation of the Korean Industries(FKI). So the purpose of this study is to figure out the FKI's company town, It is begun with the history and the characteristics of the Western company town and the company town of Japanese type. The process of the company town issue from the first proposal of the FKI is examined. Particularly, the definitions, the examples and the expected effects of the company town in the reports supporting the FKI's proposal are explored. Western company town could be characterized by the economic simplicity and the important role of single firm for supply of jobs, houses, etc. In the light of the results of this study, the FKI's company town was based on the western company town especially in definition, influenced by the company town of Japanese type and then identified with industrial clusters. Consequently there is some disaccordance among the definitions, the examples and the expected effects of the FKI's company town. Giving shape to the FKI's company town project in desirable way, it should be developed in small scale at first, with many related enterprises and public institutions to meet their spatial demand and in related with the other new town projects, for example, future innovative city and innovative cluster.

• Journal of the Korean association of regional geographers
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• v.17 no.4
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• pp.432-442
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• 2011

Climatic variables such as temperature and precipitation tend to vary both in space and in time simultaneously. Thus, it is necessary to include space-time autocorrelation into conventional spatial interpolation methods for reliable time-series mapping. This paper introduces and applies space-time variogram modeling and space-time kriging to generate time-series temperature maps using hourly Automatic Weather System(AWS) temperature observation data for a one-month period. First, temperature observation data are decomposed into deterministic trend and stochastic residual components. For trend component modeling, elevation data which have reasonable correlation with temperature are used as secondary information to generate trend component with topographic effects. Then, space-time variograms of residual components are estimated and modelled by using a product-sum space-time variogram model to account for not only autocorrelation both in space and in time, but also their interactions. From a case study, space-time kriging outperforms both conventional space only ordinary kriging and regression-kriging, which indicates the importance of using space-time autocorrelation information as well as elevation data. It is expected that space-time kriging would be a useful tool when a space-poor but time-rich dataset is analyzed.