Resistance switching memory cells were fabricated using atomically dispersed Pt-SiO2 thin film prepared via RF co-sputtering. The memory cell can switch between a low-resistance-state and a high-resistance-state reversibly and reproducibly through applying alternate voltage polarities. Percolated conducting paths are the origin of the low-resistance-state, while trapping electrons in the negative U-center in the Pt-SiO2 interface cause the high-resistance-state. Intermediate resistance-states are obtained through controlling the compliance current, which can be applied to multi-level operation for high memory density. It is found that the resistance value is related to the capacitance of the memory cell: a 265-fold increase in resistance induces a 2.68-fold increase in capacitance. The exponential growth model of the conducting paths can explain the quantitative relationship of resistance-capacitance. The model states that the conducting path generated in the early stage requires a larger area than that generated in the last stage, which results in a larger decrease in the capacitance.

본 논문에서는 대두(soybean)의 외관 검사를 위해 명암도, 지역분산 및 지역 명암도 차이에 기초한 대두 선 별 알고리즘과 이를 적용한 대두 선별 장치의 구현 방법을 제안한다. 제안한 선별 장치는 4개의 채널로 구분된 벨트 컨베이어를 이용하여 대두 시료를 정렬된 형태로 이송하고, 종단에서 낙하하는 대두들에 대해 배후조명(back-light)과 흑백의 라인스캔(line-scan) 카메라를 이용하여 영상을 획득한 후 실시간으로 대두의 외관을 양품과 불량으로 선별하 였다. 실시간 선별을 위해서 각 채널별로 전용의 DSP를 사용하였으며, 각각의 DSP에서는 채널별로 얻은 대두 영상 으로부터 명암도, 명암도의 지역분산, 지역명암도 차이에 기초하여 양품으로부터 얻은 10개의 판별 문턱치와 대두 클 래스별 3개의 특징벡터를 찾아 4개의 클래스로 구분된 대두 영상에 대한 양품과 불량 선별을 실시하였다. 선별 결과 처리량은 약 520kg/hour였고, 양품 선별 정확도 즉, 양품에 대한 양품 인식률은 97%이며 불량 선별 오류, 즉 불량을 양품으로 인식하는 비율은 4.3%를 나타냈다.

NiO catalysts/Al2O3/FeCrAl alloy foam for hydrogen production was prepared using atomic layer deposition (ALD)and subsequent dip-coating methods. FeCrAl alloy foam and Al2O3 inter-layer were used as catalyst supports. To improve thedispersion and stability of NiO catalysts, an Al2O3 inter-layer was introduced and their thickness was systematically controlledto 0, 20, 50 and 80nm using an ALD technique. The structural, chemical bonding and morphological properties (includingdispersion) of the NiO catalysts/Al2O3/FeCrAl alloy foam were characterized by X-ray diffraction, X-ray photoelectronspectroscopy, field-emission scanning electron microscopy and scanning electron microscopy-energy dispersive spectroscopy. Inparticular, to evaluate the stability of the NiO catalysts grown on Al2O3/FeCrAl alloy foam, chronoamperometry tests wereperformed and then the ingredient amounts of electrolytes were analyzed via inductively coupled plasma spectrometer. We foundthat the introduction of Al2O3 inter-layer improved the dispersion and stability of the NiO catalysts on the supports. Thus, whenan Al2O3 inter-layer with a 80nm thickness was grown between the FeCrAl alloy foam and the NiO catalysts, it indicatedimproved dispersion and stability of the NiO catalysts compared to the other samples. The performance improvement can beexplained by optimum thickness of Al2O3 inter-layer resulting from the role of a passivation layer.

Fe-base superalloy powders with Y2O3 dispersion were prepared by high energy ball milling, followed by sparkplasma sintering for consolidation. High-purity elemental powders with different Fe powder sizes of 24 and 50mm were usedfor the preparation of Fe-20Cr-4.5Al-0.5Ti-O.5Y2O3 powder mixtures (wt%). The milling process of the powders was carriedout in a horizontal rotary ball mill using a stainless steel vial and balls. The milling times of 1 to 5 h by constant operation(350 rpm, ball-to-powder ratio of 30:1 in weight) or cycle operation (1300 rpm for 4 min and 900 rpm for 1 min, 15:1) wereapplied. Microstructural observation revealed that the crystalline size of Fe decreased with an increase in milling time by cyclicoperation and was about 15nm after 3 h, forming a FeCr alloy phase. The cyclic operation had an advantage over constantmilling in that a smaller-agglomerated structure was obtained. The milled powders were sintered at 1100oC for 30 min invacuum. With an increase in milling time, the sintered specimen showed a more homogeneous microstructure. In addition, ahomogenous distribution of Y-compound particles in the grain boundary was confirmed by EDX analysis.

Electronic products are a major part of evolving industry and human life style; however most of them are known to emit electromagnetic waves that have severe health hazards. Therefore, different materials and fabrication techniques are understudy to control or limit transfer of such waves to human body. In this study, nanocomposite powder is dispersed into epoxy resin and shielding effects such as absorption, reflection, penetration and multiple reflections are investigated. In addition, nano size powder (Ni, Fe2O3, Fe-85Ni, C-Ni) is fabricated by pulsed wire evaporation method and dispersed manually into epoxy. Characterization techniques such as X-ray diffraction, Scanning electron microscopy and Transmission electron microscopy are used to investigate the phase analysis, size and shape as well as dispersion trend of a nano powder on epoxy matrix. Shielding effect is measured by standard test method to investigate the electromagnetic shielding effectiveness of planar materials, ASTM D4935. At lower frequency, sample consisting nano-powder of Fe-85%Wt Ni shows better electromagnetic shielding effect compared to only epoxy, only Ni, Fe2O3 and C-Ni samples.

본 연구는 폴리프로필렌(PP) 수지의 Co 및 Mo 촉매에 의한 반응시간과 농도변화에 따른 저온열분해 액화특성을 파악하고자 회분식 반응기를 이용하여 특정 온도(425, 450, 475℃)에서의 전환율을 측정하였다. 열분해 시간은 20~80분으로 설정하였고 생성물은 산업통상자원부에서 고시한 증류성상 온도에 따라 가스, 가솔린, 등유, 경유, 중유로 분류하였다. 그리고 450℃ 반응온도에서 촉매 사용에 따른 전환율은 모든 반응시간에 있어 Mo 촉매 > Co 촉매 > 무촉매 순이었다. Co 및 Mo 촉매 농도별 PP 전환율 및 열분해 생성물 수율은 Co:Mo=50:50 혼합시 가장 우수한 것으로 나타났다.

최근들어 에너지 고갈로 인해 에너지 저장 및 대체 에너지에 대한 관심이 점차 높아 지고 있다. 이로 인해 상변화 물질을 이용한 에너지 저장 및 이동에 대한 연구가 활발히 진행 되고 있다. 본 연구에서는 SPG막(Shirasu porous glass membrane)을 통한 막유화법을 이용하여 상변화 물질인 파라핀계 루비덤® (RT-21과 RT-24)을 분산상으로 하여 단분산성 마이크로 입자를 제조하고, 외부를 실리카로 코팅하여 열정 안정성을 향상시키고 열적 특성을 조사하였다. 단분산성 루비덤® 입자의 제조를 위해 분산상 압력, 유화제 농도, 루비덤®과 실리카의 비율을 변수로 하여 평균 입자 크기 7-8 μm를 얻었다. Differential scanning calorimetry (DSC)와 Thermogravimetry analysis (TGA)를 이용하여 열적 안정성과 잠열 등의 열적 특성을 조사하였고, Particle size analyzer (PSA), Scanning electron microscopy (SEM), optical microscopy를 이용하여 입자 분포와 캡슐화 유무를 확인하였다. 또한, Fourier transform infrared spectroscopy (FT-IR)를 통하여 정성분석을 시행하였다. 결과적으로, 막유화법을 이용하여 얻은 실리카 코팅된 단분산성 루비덤® 입자는 향상된 열적 안정성을 보였으며, 순수한 루비덤®의 80% 이상의 잠열을 유지하는 것을 보여 기존의 상변화 물질의 상안정성을 보완하여 열저장성 기능성 벽지와 건축물, 인테리어 제품에 사용 가능함을 알 수 있었다.

SPAE (Sulfonated poly(arylene ether sulfone), SPAES) copolymers exhibit a lot of advantages such as a relatively low production cost, and easy control of ionic conductivity and gas barrier properties, when they are used as membrane materials for polymer electrolyte fuel cells, redox flow batteries, and electrolysis. SPAES copolymer membranes are fabricated by evaporating polar aprotic solvents from their concentrated solutions. This conventional process, however, is needed to be excluded, owing to additional production cost associated with the organic solvent separation and hazardous issues. In this study, a benign membrane fabrication method is developed based on SPAES nanodispersions in water-alcohol mixtures. Their fundamental characteristics are systematically investigated in comparison with those made from the conventional method.

최근 분리, 흡착과 같은 물리적인 수처리 공정이 중요해졌고, 본 연구에서는 Track-etched polycarbonate(PC) membrane이 친수성이며 균일한 기공크기를 가지고 기계적강도가 우수하다는 점을 이용하여 하전 된 균일한 크기의 나노입자를 포함한 콜로이드 용액의 제거능력에 대해 조사하여 분리특성을 파악하였다. 유화중합을 이용하여 양전하, 음전하로 각각 하전 된 균일하며 착색된 나노입자(70 ~200nm)를 다양한 조건으로 제조하고, SEM, DSC, FT-IR 및 제타 전위를 측정하여 라텍스의 특성을 파악하였다. 또, PC membrane의 표면전하 및 기공크기와 입자의 표면전하 및 입자크기에 따른 수투과도 및 배제율을 조사하였다.

단일막이 가지는 저유량 한계성과 복합막이 가지는 용질 역확산 현상을 완화하기 위한 방법으로 지지층 내 금속 착물이 균일하게 정착된 PSF 고분자 지지층을 제조하였다. 부직포의 두께와 밀도를 조절하였으며 지지층 제조법 최적화 이후 Fe(II)-chelate 착물을 포함하는 정삼투 분리막을 제조하였다. 지지층 제조방법에 있어 고분자의 부직포 함침 속도 조절이 정삼투 분리막 지지층의 구조결정에 가장 중요한 역할을 함을 볼 수 있었다. 고분자의 상 전이 과정에 있어서 금속 착물과 같은 극성물질의 존재가 용매 -비용매 치환 속도에 영향을 주어 지지층 구조 조절을 유도하였으며 그 결과, 용질 역확산이 약 0.07 - 0.11 GMH의 값을 가지는 높은 제거효율의 FO막을 제조할 수 있었다.

Alumina dispersion strengthening copper(ADSC) alloy has great potential for use in many industrial applications such as contact supports, frictional break parts, electrode materials for lead wires, and spot welding with relatively high strength and good conductivity. In this study, we investigated the oxidation behavior of ADSC alloys. These alloys were fabricated in forms of plate and round type samples by surface oxidation reaction using Cu-0.8Al, Cu-0.4Al-0.4Ti, and Cu-0.6Al-0.4Ti(wt%) alloys. The alloys were oxidized at 980 oC for 1 h, 2 h, and 4 h in ambient atmosphere. The microstructure was observed with an optical microscope(OM) and a scanning electron microscope(SEM) equipped with energy-dispersive X-ray spectroscopy(EDS). Characterization of alumina was carried out using a 200 kV field-emission transmission electron microscope(TEM). As a result, various oxides including Ti were formed in the oxidation layer, in addition to γ-alumina. The thickness of the oxidation layer increased with Ti addition to the Cu-Al alloy and with the oxidation time. The corrected diffusion equation for the plate and round type samples showed different oxidation layer thickness under the same conditions. Diffusion length of the round type specimen had a value higher than that of its plate counterpart because the oxygen concentration per unit area of the round type specimen was higher than that of the plate type specimen at the same diffusiondepth.

Vegetable leather 표면 코팅에 사용된 폴리우레탄 수지는 glycerol의 함유를 mole% 비로 달 리하면서 합성하였다. 합성된 폴리우레탄 수지의 기계적 특성은 SEM, FT-IR, UTM 등을 이용하여 측 정하였다. 친환경적인 고분자 수지의 관심이 고조됨에 따라 용제의 사용을 최소화한 vegetable leather 코팅에 사용되는 수분산 수지를 합성하였다. 지방족 3가 알콜인 glycerol의 mole% 비가 증가함에 따라 내마모도, 인장강도가 증가함을 알 수 있었다. 반대로 연신율, 내굴곡 물성은 감소함을 알 수 있었다. Toluene을 이용한 내용제성 물성측정 결과에는 glycerol의 mole% 증가에 따른 물성 증감 효과는 없었 다.

The blending schemes of Saengshik powder with water were established to retain the dispersion stability of the Saengshik beverage in order to develop a ready-to-drink type product. The effect of the blending on the rheological properties and the dispersion stability of Saengshik beverage were determined. The Saengshik beverages, blended with low shear force for a short time, showed dilatant fluid characteristics, while those with high shear force for a long time had pseudoplastic fluid ones. The consistency of Saengshik beverage increased with the blending speed and time. Saengshik beverage blended at low shear showed rheopexy while becoming time independent by a highshear blending action. A logarithmic model fitted well to the changes in backscattering light flux with the rest time of Saengshik beverage. Based on sedimentation kinetics, the migration speed of clear front, and the thickness of sedimented layer, Saengshik beverage with maximum dispersion stability was obtained by a high shear blending at 15,120 rpm for 25 s.

To perform long-term sewer monitoring, It is important to understand the nature of the wastewater flow that occurs at the point on early stage of the monitor and to prevent in advance a problem which may caused. We can infer the flow properties and external factors by analyzing the scatter graph obtained from the measured data flow rate monitoring data since an field external factor affecting the sewage flow is reflected in the flow rate monitoring data. In this study, Selecting the three points having various external factors, and we Inferred the sewer flow characteristics from depth-velocity scatter graph and determined the analysis equation for the dry-weather flow rate data. At the‘point 1’expected non-pressure flow, we were able to see the drawdown effect caused by the free fall in the manhole section. At the‘point 2’, existed weir and sediments, there was backwater effect caused by them, and each of size calculated from the scatter graph analysis were 400 mm and 130 mm. At the‘Point 3’, there is specific flow pattern that is coming from flood wave propagation generated by the pump station at upstream. In common, adequate equations to explain the dry weather flow data are flume equation and modified manning equation(SS method), and the equations had compatibility for explaining the data because all of R2 values are over 0.95.

본 논문에서는 피혁에 사용되는 수용성 폴리우레탄 사슬 연장제인 1,4-butanediol(1,4-BD)의 함유에 따른 물성변화를 조사하였다. 합성에 사용된 시약은 poly propylene glycol(PPG), isoporon diisocyanate((IPDI), dimethylolpropionic acid(DMPA), 1,4-BD를 사용하였다. 1,4-BD의 함유에 따른 내용제성과 내굴곡성 측정값은 시료 전부 우수한 물성을 보였다. 인장강도, 내마모성 측정결과 1,4-BD가 많이 함유된 시료들이 각각 1.80kgf/mm2, 49.54 mg.loss로 우수한 물성을 확인하였다. 연실율 측정결과 1,4-BD가 적게 함유된 시료가 364%로 가장 우수한 측정값을 나타냈다.

Pt nanopowder-dispersed SiO2 (SOP) films were prepared by RF co-sputtering method using Pt and SiO2 targets in Ar atmosphere. The growth rate and Pt content in the film were controlled by means of manipulating the RF power of Pt target while that of SiO2 was fixed. The roughness of the film was increased with increasing the power of Pt target, which was mainly due to the increment of the size and planar density of Pt nanopowder. It was revealed that SOP film formed at 10, 15, 20 W of Pt power contained 2.3, 2.7, and 3.0 nm of spherical Pt nanopowder, respectively. Electrical conductivity of SOP films was exponentially increased with increasing Pt power as one can expect. Interestingly, conductivity of SOP films from Hall effect measurement was greater than that from DC I-V measurement, which was explained by the significant increase of electron density.

수원을 비롯한 전국 29개 지역에서 썩덩나무노린재를 채집하여 미토콘드리아 의 Cytochrome Oxidase I 유전자를 분리, 염기서열을 조사하여, 각 지역 계통 간 DNA의 염기서열과 비교, 분석하였다. 또한 미국 5개 지역으로부터 수집된 표본도 분석에 포함하여 유전적 근친도를 분석하였다. 분석 결과, 우리나라의 썩덩나무노 린재 유전자 근친도는 미국에 비해 국내 지역 계통간 서로 매우 가까운 것으로 밝혀 졌다. 발원지는 경기도 북부 지역으로 추정되며, 이 후 남쪽으로 계속 확대해간 것 으로 추정된다. 미국 종과 비교해 보면 차이가 많으나, 일부 지역에서는 미국 종과 유사성을 보이고 있다. 썩덩나무노린재가 국내 고유종으로 인정되고 있으나 미국 종들 보다 유전적 변이가 적고, 일부 중북부 지역에서 채집한 지역종이 미국 종과 유전적 근친도가 높은 점, 그리고 국내 지역 종들 간 유전적 친화도가 매우 높은 점 은 이들의 원산지에 대해 다시 한 번 생각하게 한다. 우리나라에서는 중북부 지역에 서 속하는 계통이 비교적 짧은 시간에 전국적으로 퍼져나간 것으로 추정된다. 따라 서 썩덩나무노린재는 북쪽에서 남쪽으로 전파한 것으로 생각되어 북쪽의 썩덩나 무노린재의 유전적 다양성 연구가 필요한 상황이며, 보다 면밀한 연구를 위해 개체 변이를 측정할 수 있는 마커를 가지고 심도 있는 집단 유전 연구가 필요하다.

15Cr-1Mo base oxide dispersion strengthened (ODS) steel which is considered to be as a promising candidate for high- temperature components in nuclear fusion and fission systems because of its excellent high temperature strength, corrosion and radiation resistance was fabricated by using mechanical alloying, hot isostatic pressing and hot rolling. Torsion tests were performed at room temperature, leading to two different shear strain routes in the forward and reverse directions. In this study, microstructure evolution of the ODS steel during simple shearing was investigated. Fine grained microstructure and a cell structure of dislocation with low angle boundaries were characterized with shear strain in the shear deformed region by electron backscattered diffraction (EBSD). Grain refinement with shear strain resulted in an increase in hardness. After the forward-reverse torsion, the hardness value was measured to be higher than that of the forward torsion only with an identical shear strain amount, suggesting that new dislocation cell structures inside the grain were generated, thus resulting in a larger strengthening of the steel.

In this study, we prepare polymer solar cells incorporating organic ligand-modified Ag nanoparticles (O-AgNPs) highly dispersed in the P3HT:PCBM layer. Ag nanoparticles decorated with water-dispersible ligands (W-AgNPs) were also utilized as a control sample. The existence of the ligands on the Ag surface was confirmed by FT-IR spectra. Metal nanoparticles with different surface chemistries exhibited different dispersion tendencies. O-AgNPswere highly dispersed even at high concentrations, whereas W-AgNPs exhibited significant aggregation in the polymerlayer. Both dispersion and blending concentration of the Ag nanoparticles in P3HT:PCBM matrix had critical effects onthe device performance as well as light absorption. The significant changes in short-circuit current density (JSC) of thesolar cells seemed to be related to the change in the polymer morphology according to the concentration of AgNPsintroduced. These findings suggested the importance of uniform dispersion of plasmonic metal nanoparticles and theirblending concentration conditions in order to boost the solar cell performance.