• Polymer(Korea)
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• v.29 no.4
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• pp.380-384
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• 2005

Fluoroalkyl methacrylate and acrylic acid were bulk radical copolymerized in the presence of pure sodium montmorillonite or macromer intercalated sodium montmorilonite to get a fluorinated acrylic ionomer/sodium montmorillonite composite, and their physical properties, such as X-ray diffraction pattern, tensile properties, and water uptake, were examined. These composites were used to preparean ionic acrylic polymer-platinum composite (IPMC). The current and deformation responses of these IPMCs by external voltage applied across the platinum electrodes deposited on both sides of IPMC showed that the cation migration from anode to cathode was suppressed in the presence of sodium montmorillonite, causing reduced current and deformation.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2007.09a
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• pp.42-54
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• 2007

${\blacksquare}$ 매엽실 세정장비의 양산적용 확대 ${\centerdot}$ 역오염 감소로 수율개선, 짧은 TAT ${\centerdot}$ Throughput 개선필요 : Process Module + Wafer Transfer ${\blacksquare}$ 향후 $2{\sim}3$년 동안 세정기술의 패러다임 변화 예상 ${\centerdot}$ 초미세 패턴에서의 입자 제거 대책 (${\sim}22.5nm$), 신재료에 따른 케미컬 대응 (에칭, 부식, 물성변화). ${\blacksquare}$ 세정기술의 통합 솔루션 필요 ${\centerdot}$ 초임계 유체세정 : 극미세 패턴까지도 대응 가능 ${\centerdot}$ 장비와 공정 측면에서 많은 연구 필요

• Polymer(Korea)
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• v.24 no.2
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• pp.237-244
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• 2000

Phenolic resin used as a precursor of carbonized matrix for carbon-carbon composites was modified by addition of molybdenum disilicide (MoSi$_2$) in various concentrations of 0, 4, 12 and 20% by weight to improve the anti-oxidation properties of the composites. The green body was manufactured by a prepreg method and was submitted to carbonization up to 110$0^{\circ}C$. In this work, the oxidation behavior of carbon-carbon composites with MoSi$_2$ as an oxidation inhibitor was investigated at the temperature range of 600-100$0^{\circ}C$ in an air environment. The carbon-carbon composites with MoSi$_2$ showed a significantly improved oxidation resistance due to both the reduction of the porosity formation and the formation of mobile diffusion barrier for oxygen when compared to those without MoSi$_2$. Carbon active sites should be blocked, decreasing the oxidation rate of carbon. This is probably due to the effect of the inherent MoSi$_2$ properties, resulted from a formation of the protective layer against oxygen attack in the composites studied.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.61.2-61.2
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• 2011

넓은 밴드갭을 가지고 있어 가시광에서 투명하며 높은 이동도를 가진 산화물 반도체는 기존의 Si 기반 TFT 소자를 대체할 차세대 디스플레이의 핵심 소재기술로 관심이 높아지고 있다. 그러나 대표적인 산화물 반도체인 In-Ga-Zn-O (IGZO)에 포함된 인듐의 수요 증가에 따른 가격 급등 문제로 이를 대체할 수 있는 새로운 산화물 반도체 재료에 대한 연구의 필요성이 대두되고 있다. 이에 비교적 저가의 물질로 구성된 Zn-Sn-O계 산화물 소재에 대한 연구가 진행된 바 있으나, 높은 수준의 캐리어 농도를 가지고 있어 TFT 채널용 반도체소재로 적용되기 위해서는 이를 $10^{17}\;cm^{-3}$ 이하로 조절할 수 있는 기술개발이 요구된다. 본 연구는 마그네트론 스퍼터링법을 이용하여 증착된 Ga-Zn-Sn-O (GZTO) 박막의 갈륨 첨가에 따른 특성변화를 조사하였다. GZO ($Ga_2O_3$ 5wt%)와 $SnO_2$ 타켓의 인가 파워를 고정한 상태에서 $Ga_2O_3$ 타켓의 인가 파워를 0~100W로 조절하여 박막 내 Ga 함량을 증가시켰다. 제조된 모든 GZTO 박막은 Ga함량에 관계없이 비정질 구조를 가지며 가시광 영역에서 약 78%의 우수한 투과율을 나타낸다. Ga 함량에 따라 박막의 구조적, 광학적 특성은 크게 변하지 않지만 전기적 특성은 뚜렷한 변화를 나타냈다. $Ga_2O_3$ 파워가 증가할수록 박막 내 캐리어 농도와 이동도의 감소로 비저항이 크게 증가하는데 특히 캐리어 농도는 $Ga_2O_3$ 파워가 0에서 100W로 증가할 때 $2{\times}10^{18}$에서 $8{\times}10^{14}\;cm^{-3}$으로 감소하였다. 이는 Ga-O의 화학적 결합 에너지가 다른 원소들(Zn 또는 In)에 비해 커서 박막 내 산소공공의 감소가 야기되었기 때문이다. 이러한 전기물성의 변화를 이해하기 위해 XPS 분석을 수행하였다. 제조된 GZTO 박막은 $Ga_2O_3$ 파워가 증가함에 따라 O 1s peak에서 산소공공과 관련된 530.8 eV peak의 intensity가 감소한다. 따라서 Ga을 첨가에 따른 캐리어 농도의 감소는 산소공공의 발생억제로 기인한 것으로 판단되며, 본 연구결과는 ZTO계 비정질 산화물 반도체의 활용가능성을 제시하였다.

• Polymer(Korea)
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• v.29 no.5
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• pp.445-450
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• 2005

Hyaluronic acid-based beads were prepared in order to develop a biomedical material for augumentation. Hyaluronic acid was crosslinked by 1,3-butadiene diepoxide in a suspension state maintained by rapid mixing of soybeen oil and hyaluronic acid solution. The particle size, surface area and swelling ratio were measured to investigate the physical properties of the synthesized beads and the bead surface was examined by scanning electron microscopy. The beads were formed in the range of $5-12vol\%$ concentration of crosslinking agent, which showed monodisperse size distribution. Both BET surface area and swelling ratio decreased as the concentration of either hyaluronic acid or crosslinking agent increased, and crosslinking temperature decreased. Bead size could be effectively controlled by mixing speed without affecting other physical property.

• Composites Research
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• v.28 no.1
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• pp.22-27
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• 2015

Although it is important to have high strength of each of fiber and matrix, interface between fiber and matrix is most important. If NaCl water penetrates the interface, that area will be weak. So experiment about increasing interfacial strength is in process. In this study, the change of properties by mechanical, interfacial and micromechanical tests was observed after NaCl and aging treatment. The changes in mechanical properties of glass fiber were investigated using single-fiber tensile test. Interfacial properties between glass fiber and epoxy resin were evaluated using nondestructive acoustic emission (AE) and micromechanical test applied to fatigue test. Through change of fatigue properties, relative interfacial properties were evaluate. In conclusion, glass fiber diameter decreased and the reduction of mechanical and interfacial was observed with NaCl solution and aging treatment.

• Journal of Adhesion and Interface
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• v.9 no.4
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• pp.24-29
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• 2008

Polypropylene-natural fiber composites have been prepared and their rheological properties during mixing and thermal properties were investigated. Two types of natural fibers (cotton fiber and wood fiber) were compared. On increasing fiber contents, the torque values of composites were increased, where the cotton fiber exhibited higher increase in torques. The torque values of composites were higher as the MI of PP decreased. X-ray diffraction and differential scanning calorimetry results showed an increase in the crystallization temperature but a decrease of crystallinity of the PP/natural fiber composites on increasing fiber contents.

• Journal of the Korean Wood Science and Technology
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• v.43 no.6
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• pp.777-783
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• 2015

Wood is an anisotropic material that shows the changes in hardness, quality and dimensions depending on the types of cells on three cross sections, size, array and so on. It can also be used in different ways according to its use, which requires a meticulous research, in order to maximize the utilization by understanding the nature and use; and by clarifying the theory and technologies. The research on relationship among wood's physical properties, density, and elasticity of modulus have been studied in Korea and abroad, but those studies were based on correlation gained through standardized specimen. Rather, the study on complete product is rare. Moreover, the previous reports are mostly concentrating on vibration mode and batting, though the wood's physical properties as a material have not been in the main focus. Therefore, this study will carried out for analyzing MOE through figuring material property out and comparing frequency adapting to the Canadian HardMaple bat. For comparison of material properties, we studied the annual ring and density of the bat; calculated the MOE with resonance frequency and formula (ASTM C1259); and verified the repulsive force of this material. As a result, the relevance of the resonance frequency and annual ring is weak, and in comparison in the grain direction in wood, the MOE value is higher when the grain direction in wood is excited horizontally than when is excited vertically, because the material is repulsive when grain direction is horizontal.

• Resources Recycling
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• v.16 no.2 s.76
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• pp.32-39
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• 2007

The measurement of physicochemical properties of ASR incineration ash has been carried dot and the preparation of light-weight material has also been performed using ASR ash for recycling point of view as building or construction materials. For this aim, chemical composition, particle size distribution, and heavy metal leachability were examined for 2 bottom ashes and 4 fly ashes obtained from the domestic ASR incinerator. In the present work, attempt has been made to prepare the lightweight material using boiler ash as a raw material, which is prepared by forming the mixture of boiler ash, lightweisht filler and inorganic binder and followed by calcination at elevated temperature. As a result, the content of Cu in bottom ash was as high as about 3wt% so that the recovery of Cu from ash was required. The major compound of SDR #5 and Bag filter #6 was found to be $CaCl_2{\cdot}Ca(OH)_2{\cdot}H_2O\;and\;CaCl_2{\cdot}4H_2O$, respectively. It is thought that heavy metal teachability of lightweight material prepared with boiler ash was significantly decreased due to the encapsulation or stabilization of heavy metal compounds.

• Journal of the Korean GEO-environmental Society
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• v.5 no.1
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• pp.75-84
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• 2004

Stone column is one of the soft ground improvement method, which can enhance ground conditions such as the settlement reduction and the increasement of bearing capacity with applying the crushed stone instead of sand. In recent, general construction material, sand is in short of supply. Therefore, the bearing capacity improvement by the stone column is considered as the alternative method needed in many cases so the bearing capacity estimation is considered as important point. Nevertheless, adequate estimation methods to predict bearing capacity of stone column considering stone column and improvement effect of ground is not yet prepared. For the analysis of above mentioned points, the behavior of stone column were simulated as numerically on various property cases of crushed stone and surrounded ground. Through the numerical analysis of simulation results, the formula for the bearing capacity estimation of stone column was suggested. This formula was verified by comparing the prediction result of in situ test.