• 청정기술
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• 제22권1호
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• pp.9-15
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• 2016

Al/(Al+Zr)의 몰 비를 달리하여 xAl-yZr 산화물 촉매를 공침법으로 제조하였고, 모델반응으로 이소프로판올 탈수반응을 수행하였다. 제조된 촉매는 X-선 회절분석, 시차 열분석법, 질소 흡착법, 암모니아 승온탈착법, 이소프로판올 승온탈착법 등의 특성분석을 수행하였다. 지르코니아에 알루미늄 종을 첨가하면 상대적으로 넓은 비표면적을 갖는 작은 입자를 얻을 수 있으며 지르코니아의 결정상변화를 억제시켰다. 암모니아 승온탈착으로 알루미늄의 몰 비가 증가함에 따라 상대적인 산양이 증가함을 확인하였고, 이소프로판올탈수반응에서 촉매 활성 또한 증가하였다. 이러한 촉매활성은 촉매의 비표면적, 산점, 상대적으로 용이한 이소프로판올의 탈착과 연관시킬 수 있었다.

• Journal of the Korean Wood Science and Technology
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• 제33권4호통권132호
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• pp.15-22
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• 2005

현악기용 도료가 현악기의 음향성능에 미치는 영향을 조사하기 위해 음향분석장치(FFT)와 점탄성 분석장치(DMTA, dynamic mechanic thermal analyzer)를 이용하여 목재악기용 도료의 음향적 성능을 평가하였다. 목재악기용으로 사용된 도료는 악기용 우레탄계 상도도료, 오일 스테인계 도료, 천연바니쉬, 캐슈 도료 및 자외선 경화형 에폭시 도료를 사용하였다. 형성된 도막의 음향적인 특성은 FFT 분석기에서 측정된 공명주파수와 댐핑값(damping factor)과 DMTA에서 측정된 tan ${\delta}$를 통하여 유추하였다. FFT에서 측정된 공명주파수와 댐핑값으로부터 도막이 가지는 음향특성에 대해 분석하였다. 측정된 도막의 점탄성적인 특성과 음향적 특성을 검토한 결과 악기용으로서의 적정도료를 결정하였다.

• 한국수소및신에너지학회논문집
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• 제25권2호
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• pp.105-113
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• 2014

Performance tests on $Ni/Ce-ZrO_2/Al_2O_3$ catalysts with additives (MgO, $La_2O_3$) were investigated in the combined reforming processes (SCR, ATR, TRM) in order to produce hydrogen and carbon monoxide (it is called "syngas".). The catalyst characterization was conducted using the BET surface analyzer, X-ray diffraction (XRD), SEM, TPR and TGA. The combined reforming process was developed to adjust the syngas ratio depending on the synthetic fuel (methanol, DME and GTL) manufacturing processes. Ni-based catalysts supported on alumina has been generally recommended as a combined reforming reaction catalyst. It was found that both free NiO and complexed NiO species were responsible for the catalytic activity in the combined reforming of methane conversion, and the $Ce-ZrO_2$ binary support employed had improved the oxygen storage capacity and thermal stability. The additives, MgO and $La_2O_3$, also seemed to play an important role to prevent the formation of the carbon deposition over the catalysts. The experimental results were compared with the equilibrium data using a commercial simulation tool (PRO/II).

• Biomaterials and Biomechanics in Bioengineering
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• 제1권2호
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• pp.105-116
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• 2014

Synthesis of interpenetrating polymer network (IPN) of chitosan-gelatin (Cs-Ge) (as a primary network) and N-isopropylacrylamide (NIPAAm) monomer (as the secondary network) was carried out with different ratio. Its structure was characterized by FT-IR, which indicated that the IPN was formed. The memberanes were studied by swelling, weight loss with time. The interior morphology of the IPN hydrogels was revealed by scanning electron microscopy (SEM); the IPN hydrogels showed a interpenetrated network of NIPAAm/chitosan has layers with more minute stoma and canals compared to interpenetrated network of NIPAAm/gelatin. Lower critical solution temperature (LCST), equilibrium swelling ratio (ESR) and deswelling kinetics were measured. The DSC results noticed that LCST of IPN hydrogels with different ratio of Cs/Ge/PNIPAAm are around $33{\pm}2^{\circ}C$. The ESR obtained results showed that with a ratio of Cs/Ge/NIPAAm: 1/1/6, the swelling ratio increased drastically from room temperature to $36^{\circ}C$ but with a ratio of Cs/Ge/PNIPAAm: 1/3/6, decrease significantly at the same condition. Therefore the hydrogels have been changed from a hydrophilic structure to a hydrophobic structure. Furthermore with an increase in temperature from room to the LCST, the ESR of IPN with higher concentration of (PNIPAAm) and (Ge) decreases but de-swelling kinetics of them are faster. Due to the suitable and different kinetics of de-swelling and the equilibrium swelling ratio (ESR) in various proportions, and because of the morphology inside the mass which confirms other tests, these hydrogels are very appropriate as a smart thermosensitive hydrogels with rapid response.

• 한국응용과학기술학회지
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• 제32권1호
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• pp.85-92
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• 2015

생분해성 고분자인 셀룰로오스 아세테이트(CA)를 매트릭스로 용액 중합된 HCl이 50% 정도 도핑된 PAni를 첨가하여 도전성 PCA 복합 필름을 제조하여 기계적, 전기적 특성 및 표면 morphology를 고찰하였다. PCA 복합 필름의 인장강도는 PAni 함유량 5 wt% 인 경우 순수 CA 필름($377.1kg_f/cm^2$)에 비해 27% 정도 감소된 $275.2kg_f/cm^2$를 나타내었으며, 신율도 7.65%에서 4.35% 정도로 감소하였다. 표면저항은 PAni의 함량에 따라 감소하였으며, PAni 함유량이 5 wt%인 PCA05의 경우 $7.0{\times}10^9{\Omega}/sq$로 정전기 방지용 필름으로 사용이 가능할 정도였다. 표면 정전기량의 소멸 속도도 PAni 함량에 따라 비례하여 빨라짐을 확인하였다. PCA 복합 필름의 열적 안정성은 PAni 함량이 늘어남에 따라 분해온도가 낮아졌으며, 최종 재(char)의 함량은 PAni의 함량에 비례하였다. 최종 재의 함량을 이용하여 미지의 PCA 복합 필름 중의 PAni의 분율을 계산할 수 있을 것으로 판단된다.

• 유기물자원화
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• 제27권4호
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• pp.83-90
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• 2019

본 연구에서는 중유회의 고형연료로써 활용 가능성을 평가하기 위해 첨가제별 성형 특성과 조성을 분석하고, 제조한 SRF(Solid Refuse Fuel)의 발열량을 비교하였다. SRF 성형을 위해 함께 첨가한 첨가제는 귤박, 폐목재, 석탄이었으며, 함수율 30%를 기준으로 각각의 첨가제를 혼합하여 압출방법을 통해 펠렛 형태로 제조하였다. 실험결과, SRF의 성형성은 중유회와 석탄 또는 귤박을 혼합한 조건에서 우수하였으며, 발열량은 석탄을 혼합한 SRF가 4,274 kcal/kg 으로 가장 높았다. 따라서 중유회를 활용한 고형연료의 합성 조건은 20 wt%의 석탄을 혼합하여 함수율 30%로 제어하였을 때, 높은 성형성과 발열량의 향상을 나타내는 것을 확인하였다. 이 결과로부터 J 화력발전소의 중유회를 활용하여 첨가제(귤박, 폐목재, 석탄)를 일정 비율로 주입하였을 때 고형연료의 제조 가능성을 확인할 수 있었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.304.1-304.1
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• 2014

Flat-panel displays have been growing as an essential everyday product in the current information/communication ages in the unprecedented speed. The forward-coming applications require light-weightness, higher speed, higher resolution, and lower power consumption, along with the relevant cost. Such specifications demand for a new concept-based materials and applications, unlike Si-based technologies, such as amorphous Si and polycrystalline Si thin film transistors. Since the introduction of the first concept on the oxide-based thin film transistors by Hosono et al., amorphous oxide thin film transistors have been gaining academic/industrial interest, owing to the facile synthesis and reproducible processing despite of a couple of shortcomings. The current work places its main emphasis on the binary oxides composed of ZnO and SnO2. RF sputtering was applied to the fabrication of amorphous oxide thin film devices, in the form of bottom-gated structures involving highly-doped Si wafers as gate materials and thermal oxide (SiO2) as gate dielectrics. The physical/chemical features were characterized using atomic force microscopy for surface morphology, spectroscopic ellipsometry for optical parameters, X-ray diffraction for crystallinity, and X-ray photoelectron spectroscopy for identification of chemical states. The combined characterizations on Zn-Sn-O thin films are discussed in comparison with the device performance based on thin film transistors involving Zn-Sn-O thin films as channel materials, with the aim to optimizing high-performance thin film transistors.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.356.1-356.1
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• 2014

The Isolation of few-layered transition metal dichalcogenides has mainly been performed by mechanical and chemical exfoliation with very low yields. in particular, the two-dimensional layer of molybdenum disulfide (MoS2) has recently attracted much interest due to its direct-gap property and potential application in optoelectronics and energy harvesting. However, the synthetic approach to obtain high-quality and large-area MoS2 atomic thin layers is still rare. In this account, a controlled thermal reduction-sulfurization method is used to synthesize large-MoOx thin films are first deposited on Si/SiO2 substrates, which are then sulfurized (under vacuum) at high temperatures. Samples with different thicknesses have been analyzed by Raman spectroscopy and TEM, and their photoluminescence properties have been evaluated. We demonstrated the presence of mono-, bi-, and few-layered MoS2 on as-grown samples. It is well known that the electronic structure of these materials is very sensitive to the number of layer, ranging from indirect band gap semiconductor in the bulk phase to direct band gap semiconductor in monolayers. This synthetic approach is simple, scalable, and applicable to other transition metal dichalcogenides. Meanwhile, the obtained MoS2 films are transferable to arbitrary substrates, providing great opportunities to make layered composites by stacking various atomically thin layers.

• 한국재료학회지
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• 제27권2호
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• pp.89-93
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• 2017

A thin film thermoelectric generator that consisted of 5 p/n pairs was fabricated with $1{\mu}m$-thick n-type $In_3Sb_1Te_2$ and p-type $Ge_2Sb_2Te_5$ deposited via radio frequency magnetron sputtering. First, $1{\mu}m$-thick GST and IST thin films were deposited at $250^{\circ}C$ and room temperature, respectively, via radio-frequency sputtering; these films were annealed from 250 to $450^{\circ}C$ via rapid thermal annealing. The optimal power factor was found at an annealing temperature of $400^{\circ}C$ for 10 min. To demonstrate thermoelectric generation, we measured the output voltage and estimated the maximum power of the n-IST/p-GST generator by imposing a temperature difference between the hot and cold junctions. The maximum output voltage and the estimated maximum power of the $1{\mu}m$-thick n-IST/p-GST TE generators are approximately 17.1 mV and 5.1 nW at ${\Delta}T=12K$, respectively.

• 폴리머
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• 제29권4호
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• pp.357-362
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• 2005

중합체의 공액길이를 제어하고 이들이 갖는 에너지 준위를 조절하며, 발광성능향상과 발광파장을 조절하려는 목적으로 설폰기가 포함된 페닐렌-비닐렌계의 새로운 전기발광 고분자들을 Witting 중합을 통해 합성하였다. 합성된 고분자들은 일반 유기 용매에 좋은 용해성을 보였고 $400^{circ}C$ 정도의 초기분해온도와 $200^{circ}C$ 전후의 높은 유리전이온도를 가짐으로써 열적 안정성이 매우 높음을 확인하였다. 각각의 고분자는 용액과 필름상태에서 모두 설폰기의 꺾임에 의해 공액길이가 짧아질수록 UV 흡수와 발광 스펙트럼이 단파장으로 이동하였고 이를 통해 설폰기가 효율적으로 발광파장을 제어하는 것을 확인하였다. 또한 CV측정과 이론적인 계산을 통해 전자친화도가 큰 설폰기에 의해서 합성된 고분자들의 HOMO 및 LUMO 에너지 준위가 상대적으로 낮아짐으로써 소자의 전기발광특성이 향상됨을 확인하였다.