In this study, a spray dryer is used to make granules of Y2O3 and YF3, and then Y5O4F7 is synthesized following heat treatment of them under Ar gas atmosphere at 600 oC. Single and binary monomer mixtures are compared and analyzed to optimize photocurable monomer system for DLP 3D printing. The mixture of HEA and TMPTA at 8:2 ratio exhibits the highest photocuring properties and low viscosity with shear thinning behavior. The optimized photocurable monomer and synthesized Y5O4F7 are therefore mixed and applied to printing process at variable solid contents (60, 70, 80, & 85 wt.%) and light exposure times. Under optimal light exposure conditions (initial exposure time: 1.2 s, basic exposure time: 5 s), YOF composites at 60, 70 & 80 wt.% solid contents are successfully printed. As a result of measuring the size of the printed samples compared to the dimensions of the designed bar type specimen, the deviation is found to increase as the YOF solid content increases. This shows that it is necessary to maximize the photocuring activity of the monomer system and to optimize the exposure time when printing using a high-solids ceramic slurry.

An investigation is performed to clarify the manufacturing conditions of pure magnesium and AZ31 magnesium alloy thin plate using the melt drag method. By the melt drag method, suitable for magnesium molten metal, pure magnesium can be produced as a continuous thin plate with a thickness of 1.4 mm to 2.4 mm in the range of 5 m/min to 20 m/min of roll speed, and the width of the thin plate to the nozzle outlet width. AZ31 magnesium alloy is able to produce a continuous sheet of thickness in the range of 5 m/min to 30 m/min in roll circumferential speed, with a thickness of 0.6 mm to 1.6 mm and a width of the sheet matching the nozzle outlet width. In the magnesium melt drag method, the faster the circumferential speed of the roll, the shorter the contact time between the molten metal and the roll, and it is found that the thickness of the produced thin plate becomes thinner. The effect of the circumferential roll speed on the thickness of the thin plate is evident in the low roll circumferential region, where the circumferential speed is 30 m/min or less. The AZ31 thin plate manufactured by the melt drag method has a finer grain size as the thickness of the thin plate decreases, but it is currently judged that this is not the effect of cooling by the roll.

Hierarchically porous carbon materials with high nitrogen functionalities are extensively studied as highperformance supercapacitor electrode materials. In this study, nitrogen-doped porous carbon textile (N-PCT) with hierarchical pore structures is prepared as an electrode material for supercapacitors from a waste cotton T-shirt (WCT). Porous carbon textile (PCT) is first prepared from WCT by two-step heat treatment of stabilization and carbonization. The PCT is then nitrogendoped with urea at various concentrations. The obtained N-PCT is found to have multi-modal pore structures with a high specific surface area of 1,299 m2 g−1 and large total pore volume of 1.01 cm3 g−1. The N-PCT-based electrode shows excellent electrochemical performance in a 3-electrode system, such as a specific capacitance of 235 F g−1 at 1 A g−1, excellent cycling stability of 100 % at 5 A g−1 after 1,000 cycles, and a power density of 2,500 W kg−1 at an energy density of 3.593 Wh kg−1. Thus, the prepared N-PCT can be used as an electrode material for supercapacitors.

목적: 본 연구는 국내의 기성 돋보기가 광학적 기준에 부합여부와 조제가공 상태의 대칭성에 대하여 측정 평가하고자 하였다. 방법 : 국내에 유통 중인 한 종류의 기성 돋보기 100개(+1.00, +2.00,+3.00 와 +4.00 D)를 대상으로 측정하였다. 기성 돋보기의 광학적 품질은 렌즈 굴절력, 광학중심점간 거리, 광학중심점높이가 측정되었다. 측정된 값의 허용오차는 ISO 8980-1, ISO 16034:2002 그리고 RAL-RG-915를 기준으로 분석되었다. 인위적으로 발생한 수평수직 프리즘은 광학중심점간 거리와 남녀 평균동공간 거리의 오차로 프렌티스 공식으로 계산하였다. 추가적으로 기성 돋보기의 조제과정상 오류로 인한 비대칭성은 단안광학중심점간 거리와 두 렌즈간의 광학중심점간 높이의 오차로 측정하였다. 결과 : 100개의 기성 돋보기 중 23%가 ISO 8980-1의 렌즈굴절력 기준을 만족하지 못하였다. 본 연구의 기성 돋보기의 광학중심점간 거리는 62.06±1.41 mm이었으며, 남녀의 평균 동공간 거리와의 오차로 발생하는 수평프 리즘은 남성은 0.53±0.54 △ BI(0.18~1.06 △), 여성은 0.98±0.68 △ BI(0.37~1.78 △). 테의 중심에서 각 렌 즈광학중심점까지의 거리에서는 85%가 최소 1 mm이상의 오차를 보였다. 기성 돋보기 양쪽 렌즈 간 광학중심점 높이 차이는 1.26±0.83 mm이었으며, 이로 인한 발생되는 수직프리즘은 0.12~0.45 △이었다. 결론 : 많은 수의 기성 돋보기가 요구되는 광학적 품질에 미달되었다. 기성 돋보기는 착용자 개인별 안면형상을 고려하지 못하기 때문에, 광학중심점간 거리와 동공간거리의 오차가 발생하고 이로 인한 많은 정도의 수평프리 즘이 발생하였다. 따라서 광학적으로 잘못된 기성 돋보기의 사용은 시각적 편안함을 제공하는 것보다는 시각적 부담을 야기할 수 있을 것이며, 이런 문제를 방지하기 위하여 전문가를 통한 확인 과정이 반드시 필요하다.

In this study, a nanocrystalline FeNiCrMoMnSiC alloy was fabricated, and its austenite stability, microstructure, and mechanical properties were investigated. A sintered FeNiCrMoMnSiC alloy sample with nanosized crystal was obtained by high-energy ball milling and spark plasma sintering. The sintering behavior was investigated by measuring the displacement according to the temperature of the sintered body. Through microstructural analysis, it was confirmed that a compact sintered body with few pores was produced, and cementite was formed. The stability of the austenite phase in the sintered samples was evaluated by X-ray diffraction analysis and electron backscatter diffraction. Results revealed a measured value of 51.6% and that the alloy had seven times more austenite stability than AISI 4340 wrought steel. The hardness of the sintered alloy was 60.4 HRC, which was up to 2.4 times higher than that of wrought steel.

The effects of different spray angles (90°, 85°, 80°) on the microstructure and mechanical properties of a Y2O3 coating layer prepared using the atmospheric plasma spray (APS) process were studied. The powders employed in this study had a spherical shape and included a cubic Y2O3 phase. The APS coating layer exhibited the same phase as the powders. Thickness values of the coating layers were 90°: 203.7 ± 8.5 μm, 85°: 196.4 ± 9.6 μm, and 80°: 208.8 ± 10.2 μm, and it was confirmed that the effect of the spray angle on the thickness was insignificant. The porosities were measured as 90°: 3.9 ± 0.85%, 85°: 11.4 ± 2.3%, and 80°: 12.7 ± 0.5%, and the surface roughness values were 90°: 5.9 ± 0.3 μm, 85°: 8.5 ± 1.1 μm, and 80°: 8.5 ± 0.4 μm. As the spray angle decreased, the porosity increased, but the surface roughness did not show a significant difference. Vickers hardness measurements revealed values of 90°: 369.2 ± 22.3, 85°: 315.8 ± 31.4, and 80°: 267.1 ± 45.1 HV. It was found that under the condition of a 90° angle with the lowest porosity exhibited the best hardness value. Based on the aforementioned results, an improved method for the APS Y2O3 coating layer was also discussed.

In this study, an AISI 316 L alloy was manufactured using a selective laser melting (SLM) process. The tensile and impact toughness properties of the SLM AISI 316 L alloy were examined. In addition, stress relieving heat treatment (650oC / 2 h) was performed on the as-built SLM alloy to investigate the effects of heat treatment on the mechanical properties. In the as-built SLM AISI 316 L alloy, cellular dendrite and molten pool structures were observed. Although the molten pool did not disappear following heat treatment, EBSD KAM analytical results confirmed that the fractions of the low- and high-angle boundaries decreased and increased, respectively. As the heat treatment was performed, the yield strength decreased, but the tensile strength and elongation increased only slightly. Impact toughness results revealed that the impact energy increased by 33.5% when heat treatment was applied. The deformation behavior of the SLM AISI 316 L alloy was also examined in relation to the microstructure through analyses of the tensile and impact fracture surfaces.

본 연구에서는 항산화 효능과 관능적 특성이 강화된 막걸리 제조를 위해 통단호박을 직접 찐 후 비율별로 첨가하여 막걸리를 제조하였다. 단호박 막걸리 제조를 위해 단호박을 쌀 중량의 5%, 10%, 20% 및 30%를 첨가하였으며 발효 및 담금 후 9일간 단호박 막걸리의 이화학적(pH, 총산 및 알코올), 미생물학적(유산균 및 효모수) 및 항산 화 활성을 조사하였다. pH의 경우 모든 실험군에서 발효 및 저장기간이 늘어날수록 점차 낮아졌으며 9일차에는 단호박 무첨가군인 대조군(3.27)에 비해 단호박 첨가군(3.28- 3.52)이 다소 높은 결과를 보였다. 총산도는 1일차(0.09- 0.55) 및 3일차(0.81-0.86)에 급격히 증가하였으며, 그 후 서서히 증가하여 9일차에는 단호박 첨가군에서 1.16-1.32의 결과를 보였다. 알코올 함량은 9일차에 대조군 0%가 4.59로 가장 낮았고 단호박 5-30% 첨가군에서 5.20-5.77% 로 단호박 첨가량이 많아질수록 알코올 함량이 높았다. 유산균수 측정의 경우 발효초반에 증가하는 양상을 보이다가 5일차부터 다소 감소하거나 유사하여 9일차에는 단호박 첨가 0-30% 첨가군에서 7.95-8.09 log CFU/g로 나타났으며, 효모수의 경우 발효가 진행될수록 증가와 감소를 다소 반복하였으며 9일차에는 7.68-7.99 log CFU/g으로 측정되었다. DPPH 및 ABTS 라디칼 소거능은 단호박 30% 첨가군에서 85.96 및 78.97%로 각각 측정되어 단호박 무첨가군의 DPPH (48.29%) 및 ABTS (62.12%) 결과와 비교 시 높은 항산화 활성도를 보였다. 따라서 추후 단호박 첨가에 따른 각종 비타민류, 무기질 및 β-carotene 등의 영양·기능성 성분의 분석과 더불어 소비자의 관능평가 등을 통해 항산화 기능이 강화된 단호박 막걸리의 실용화를 위한 구체적인 연구개발의 확대가 필요할 것으로 사료된다.

알코올성 용제를 재활용할 수 있는 목적의 유기용제나노여과막(OSN)을 내용제성이 우수한 폴리벤지다졸 고분자를 이용하여 비용매 유도 상분리법을 이용하여 제조하였다. 제조한 나노여과막의 모폴로지와 투과특성을 조절하기 위하여 도프 용액의 농도와 물과 에탄올의 혼합용액인 응고액의 조성을 변화시키면서 제조하였다. α,α’-dibromo-p-xylene (DBX)을 이용하여 가교한 폴리벤지미다졸 분리막은 유기용제나노여과막으로 사용하기에 충분한 기계적 강도와 내용제성을 갖는 것을 확인하였다. 물로만 이루어진 응고조에서 도프용액의 농도가 20%이상인 분리막을 제조하는 경우에 분자량 696.66 g/mol을 가지는 콩고레드에 대한 제거율은 90% 이상을 나타내었고, 투과도는 5 bar의 압력에서 22.5 LMH/bar를 나타내었다. 응고액 조성에 대한 연구를 통해서 응고액 중의 에탄올 농도가 증가할수록 에탄올의 투과도가 증가하는 것을 확인하였다.

The purpose of this study is to optimize the powder formulation and manufacturing conditions for the solidification of an extract of the herb Bangpungtongseong-san (BPTS). To develop BPTS-loaded particles for the tablet dosage form, various BPTS-loaded particles composed of BPTS, dextrin, microcrystalline cellulose (MCC), silicon dioxide, ethanol, and water are prepared using spray-drying and high shear granulation (high-speed mixing). Their physical properties are evaluated using scanning electron microscopy and measurements of the angle of repose, Hausner ratio, Carr’s index, hardness, and disintegration time. The optimal BPTS-loaded particles exhibit improved flowability and compressibility. In particular, the BPTS-loaded particles containing silicon dioxide show significantly improved flowability and compressibility (the angle of repose, Hausner ratio, and Carr’s index are 35.27 ± 0.58°, 1.18 ± 0.06, and 15.67 ± 1.68%, respectively), hardness (18.97 ± 1.00 KP), and disintegration time (17.60 ± 1.50 min) compared to those without silicon dioxide. Therefore, this study suggests that particles prepared by high-speed mixing can be used to greatly improve the flowability and compressibility of BPTS using MCC and silicon dioxide.

분자각인막(MIM)은 특정 분자의 결합자리를 갖고 있는 다공성 고분자 막이다. 비용매유도 상분리(NIPS)법을 사용하여 분자각인막의 지지체로 사용될 P(AN-co-MA) 비대칭막을 제조하고, 여기에 표면 각인법을 적용하여 광활성 이니퍼터 도입과 photo-grafting을 통해 라이소자임 분자각인막을 제조하였다. P(AN-co-MA) 비대칭막을 3-chloropropyltrimethoxysilane과 광활성 이니퍼터 dithiocarbamate로 개질하고, acrylamide 단량체, N,N'-methylenebisacrylamide 가교제, 라이소자임 주형분자 혼합액을 UV 조사 환경에서 혼성중합 시켜 MIM을 제조하였다. 제조된 MIM의 FT-IR과 FE-SEM 및 EDS 분석을 실시한 결과 P(AN-co-MA) 막은 비대칭 단면 구조이었고 표면에 이니퍼터 그룹이 잘 결합되어 있어 MIM이 성공적으로 제조되었다. 제조공정의 변수 조절을 통해 라이소자임의 흡착량이 비각인막(NIM)에 비해 13배 큰 값인 2.7 mg/g을 갖는 P(AN-co-MA) 기반 MIM이 제조되었으며, 막여과 실험을 통해 라이소자임에 대한 오발부민의 투과선택도를 측정한 결과 MIM은 라이소자임의 선택적 결합력이 우수하였다.

Ni–Cr–Al metal-foam-supported catalysts for steam methane reforming (SMR) are manufactured by applying a catalytic Ni/Al2O3 sol–gel coating to powder alloyed metallic foam. The structure, microstructure, mechanical stability, and hydrogen yield efficiency of the obtained catalysts are evaluated. The structural and microstructural characteristics show that the catalyst is well coated on the open-pore Ni–Cr–Al foam without cracks or spallation. The measured compressive yield strengths are 2–3 MPa at room temperature and 1.5–2.2 MPa at 750oC regardless of sample size. The specimens exhibit a weight loss of up to 9–10% at elevated temperature owing to the spallation of the Ni/Al2O3 catalyst. However, the metal-foam-supported catalyst appears to have higher mechanical stability than ceramic pellet catalysts. In SMR simulations tests, a methane conversion ratio of up to 96% is obtained with a high hydrogen yield efficiency of 82%.