• 한국재료학회지
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• 제30권11호
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• pp.573-580
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• 2020

YAG (Yttrium Aluminum Garnet, Y₃Al₅O₁₂) has excellent plasma resistance and recently has been used as an alternative to Y₂O₃ as a chamber coating material in the semiconductor process. However, due to the presence of an impurity phase and difficulties in synthesis and densification, many studies on YAG are being conducted. In this study, YAG powder is synthesized by an organic-inorganic complex solution synthesis method using PVA polymer. The PVA solution is added to the sol in which the metal nitrate salts are dissolved, and the precursor is calcined into a porous and soft YAG powder. By controlling the molecular weight and the amount of PVA polymer, the effect on the particle size and particle shape of the synthesized YAG powder is evaluated. The sintering behavior of the YAG powder compact according to PVA type and grinding time is studied through an examination of its microstructure. Single phase YAG is synthesized at relatively low temperature of 1,000 ℃ and can be pulverized to sub-micron size by ball milling. In addition, sintered YAG with a relative density of about 98 % is obtained by sintering at 1,650 ℃.

• Archives of Pharmacal Research
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• 제18권3호
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• pp.141-145
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• 1995

Omeprazole, a proton pump inhibitor, was given intravenously (iv), orally (po), intraperitoneally (ip), hepatoportalvenously (pv), and intrarectally (ir) to rats at a dose of 72mg/kg in order to investigate the bioavailability of the drug, The extent of bioavailabilities of omeprazole administered through pv, ip, po, and ir routes were 88.5, 79.4, 40,8, and 38.7%, respectively. Pharmacokinetic analysis in this study and literatures (Regardh et al., 1985 : Watanabe et al., 1994) implied significant dose-dependency in hepatic first-pass metabolism, clearance and distribution, and acidic degradation in gastric fluid. The high bioavailability from the pv administration (88.5%) means that only 11.5% of dose was extracted by the first-pass metabolism through the liver at this dose (72 mg/kg). The low bioavailability from the oral administration (40.8%) in spite of minor hepatic first-pass extraction indicates low transport of the drug from GI lumen to portal vein. From the literature (Pilbrant and Cederberg, 1985), acidic degradation in gastric fluid was considered to be the major cause of the low transport. Thus, enteric coating of oral preparations would enhance the oral bioavailability substantially. The bioavailability of the drug from the rectal route, in which acidic degradation and hepatic first-pass metabolism may not occur, was low (38.7%) but comparable to that from the oral route (40.8 %) indicating poor transport across the rectal membrane. In this case, addition of an appropriate absorption enhancer would improve the bioavailability. Rectal route seems to be an possible alternative to the conventional oral route for omeprazole administration.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.318.1-318.1
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• 2013

Nowadays Cu2ZnSnS4 (CZTS) solar cell is attracting a lot of attention as a strong alternative to CIGS solar cell due to nontoxic and inexpensive constituent elements of CZTS. From various processes for the fabrication of CZTS solar cell, solution-based deposition of CZTS thin films is well-known non-vacuum process and many researchers are focusing on this method because of large-area deposition, high-throughput, and efficient material usage. Typically the solution-based process consists of two steps, coating of precursor solution and annealing of the precursor thin films. Unlike vacuum-based deposition, precursor solution contains unnecessary elements except Cu, Zn, Sn, and S in order to form high quality precursor thin films, and thus the precise control of precursor thin film preparation is essential for achieving high efficient CZTS solar cells. In this work, we have investigated the effect of preparation condition of CZTS precursor thin films on the performance of CZTS solar cells. The composition of CZTS precursor solution was controlled for obtaining optimized chemical composition of CZTS absorber layers for high-efficiency solar cells. Pre-annealing process of the CZTS precursor thin films was also investigated to confirm the effect of thermal treatment on chemical composition and carbon residues of CZTS absorber layers. The change of the morphology of CZTS precursor thin film by the preparation condition was also observed.

• Journal of Advanced Marine Engineering and Technology
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• 제28권1호
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• pp.109-115
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• 2004

The spatter and porosity could be occurred during$CO_2$CW laser welding of Primer- coated steel for shipbuilding. This study has suggested an alternative idea by examining of weld-defect formation mechanism. The primer-coated plate induced the spatter humping bead and porosity and these are main part of the welding defect. attributed to the powerful vaporizing pressure of primer attached on the base metal The zinc of Primer has a boiling point that is the lower temperature than melting point of steel zinc vapor will build up at the interface between the two sheets and this tends to deteriorate the quality of the weld by ejecting weld material from lap position or leaving porosity. Therefore introducing a small gap clearance in the lap position. the zinc vapor could escape through it and sound weld beads can be acquired. In conclusion, we suggested the occurred and prevented mechanism of weld defects with searching the factor.

• 한국표면공학회지
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• 제54권6호
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• pp.324-330
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• 2021

As energy harvesting technology becomes important in relation to environmental issues, piezoelectric materials that convert mechanical energy into electrical energy are attracting attention. However, PZT, a representative material for piezoelectricity, is becoming difficult to use due to the problem that its components can cause environmental pollution. For this reason, recent research suggests a triboelectric nanogenerator (TENG) that generates energy through the combined effect of triboelectricity and electric induction for alternative piezoelectric devices. In TENG, electrical power is determined by the dielectric constant, thickness, and grain generation of the charged material. Therefore, in this study, a Rutile phase TiO₂ thin film with high dielectric constant was formed using the spin-coating process and the effect of annealing was investigated. For electrical analysis, a TENG device was fabricated using PTFE as a material with an opposite charge, and electrical output according to film thickness and grain formation was comparatively analyzed.

• 한국표면공학회지
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• 제52권1호
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• pp.37-42
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• 2019

Electrodeposited zinc layer is widely used as a sacrificial anode for a corrosion protection of steel. In this study, we modified the surface of electrodeposited zinc to have a hydrophobicity, which shows various advanced functionalities, such as anti-corrosion, anti-biofouling, anti-icing and self-cleaning, due to its repellency to liquids. Superhydrophobicity was realized on electrodeposited zinc layer with a hydrothermal treatment, creating nanostructures on the surface, and following Teflon coating. The superhydrophobic surface shows a great repellency to water with high surface tension, while liquid droplets with low surface tension easily adhered on the superhydrophobic surface. However, immiscible lubricant-impregnated superhydrophobic surface shows a great repellency to various liquids, regardless of their surface tension. Therefore, it is expected that the lubricant-impregnated surface can be an alternative of superhydrophobic surface, which have a drawback for some liquids with a low surface tension.

• 센서학회지
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• 제32권6호
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• pp.335-339
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• 2023

Skin-compatible electronics have evolved to achieve both conformality and stretchability for stable contact with deformable biological skin. While existing research has largely concentrated on alternative materials, the potential of Parylene-based thin-film electrodes for stretchable on-skin applications remains relatively untapped. This study proposes an engineering strategy to achieve stretchability using the Parylene thin-film electrode. Unlike the conventional Parylene thin-film electrode, we introduce morphological adaptability via controlled microscale slits in the Parylene electrode structure. The slits-containing device enables unprecedented stretchability while maintaining critical electrical insulation properties during mechanical deformation. Finally, the demonstration on human skin shows the mechanical adaptability of these Parylene-based bioelectrodes while their electrical characteristics remain stable during various stretching conditions. Owing to the ultra-thinness of the Parylene coating, the wearable bioelectrode not only achieves stretchability but also conforms to the skin. Our findings broaden the practical use of Parylene thin-film bioelectrodes.

• 한국표면공학회지
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• 제57권1호
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• pp.49-56
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• 2024

Superhydrophobic surfaces have been expected to be able to provide considerable performance improvements and introduce innovative functions across diverse industries. However, representative methods for fabricating superhydrophobic surfaces include etching the substrate or attaching nanosized particles, but they have been limited by problems such as applicability to only a few materials or low adhesion between particles and substrates, resulting in a short lifetime of superhydrophobic properties. In this work, we report a novel coating technique that can achieve superhydrophobicity by electrophoretic deposition of aluminum nitride (AlN) nanopowders and their self-bonding to form a surface structure without the use of binder resins through a hydrolysis reaction. Furthermore, by using a water-soluble adhesive as a temporary shield for the electrophoretic deposited AlN powders, hierarchical aluminum hydroxide structures can be strongly adhered to a variety of electrically conductive substrates. This binder-free technique for creating hierarchical structures that exhibit strong adhesion to a variety of substrates significantly expands the practical applicability of superhydrophobic surfaces.

• 한국자원식물학회지
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• 제27권4호
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• pp.380-391
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• 2014

작물을 비롯한 식물체들은 작물 생산량 감소에 중요한 요인인 고온 건조풍에 의해 영향을 받는다. 이러한 영향으로부터 식물체들을 보호할 수단으로 코팅재를 고려할 수 있다. 이 연구에서 다양한 요인들에 의해 일어나는 급격한 증산작용으로부터 작물을 보호할 코팅소재를 탐색하기 위한 실내 선발법들을 확립했다. 강낭콩 유묘 포트의 무게 변화를 6일 동안 측정한 시험에서 아비온 처리구는 무처리구에 비해 유의하게 무게 감소를 억제하였다(P = 0.05). 하지만 이 방법은 장시간이 소요되는 단점이 있어 보다 단순한 방법으로 염화코발트지가 수분 접촉 시 푸른색에서 붉은색으로 변화는 색 변화법을 이용하였다. 밀납, 구아검, 유동파라핀, 콩오일 및 PE-635가 처리 30분 및 1시간 후 각각 37%와 43%의 방수력을 나타냈다. 하지만 이들 소재들도 2시간 후에는 유의할만한 방수효과를 보이지 않았다. 비록 이들 방법들이 코팅 소재를 탐색하는데 적절하다 할지라도, 보다 과학적이고 객관적인 자료들을 도출해 낼 선발법이 필요하다. 그래서 고안한 방법이 광합성측정기를 이용하여 증산율을 측정하는 방법이었다. 야외에서 재배한 보리 잎을 이용한 시험에서 2% 콩오일과 아비온 10배 희석액 처리가 증산율 억제효과를 나타냈다. 또한 옥수수 유묘 및 살구나무 신초를 이용한 시험에서 2% 유동파라핀액과 살구씨오일, 아마씨오일, 올리브오일 및 콩오일과 같은 식물체 정유들이 유의할만한 증산율 억제효과를 나타냈다(P = 0.05). 특히, 유동파라핀 및 콩오일 2%를 출수 후 2주 이상된 벼에 처리하였을 때 비슷한 증산율 억제력을 보였다. 또한 2% 콩오일과 전착제 혼합물을 옥수수 유묘에 처리 시 전착제 단독으로 처리한 것에 비해 증산율 억제효과가 증가했다. 이는 전착제가 식물체 잎 표면에서 이들 소수성 소재들이 보다 더 균일하게 확산하는데 도움을 주기 때문으로 보인다. 이 소수성 소재가 잎 표면의 기공들을 효과적으로 잘 도포하고 있음도 전자현미경으로 확인하였다. 이상의 결과는 이들 소수성 소재들이 식물체 코팅재로서 활용될 수 있음을 시사한다.

• 한국식품위생안전성학회지
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• 제38권2호
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• pp.55-62
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• 2023

돈육에 sodium carboxymethyl cellulose (CMC) 및 귤 과피 분말을 첨가한 피막제를 코팅하여 저장기간 중 돈육의 저장성에 미치는 영향을 조사하였다. 처리구는 대조구, CMC 0.1% 처리구 및 CMC 0.1%+M(귤 과피 분말) 5% 처리구로 나누었으며, 피막제의 코팅이 돈육의 품질에 미치는 영향을 조사하기 위하여 pH와 색도, TBARS, VBN 및 일반세균 수를 측정하였다. 돈육을 4℃에서 저장한 모든 처리구의 pH는 처리구 간 차이가 적어 피막제의 처리효과가 저온에서는 적은 것으로 나타났다. 돈육을 25℃에서 저장했을 때 CMC 0.1% 처리구 및 CMC 0.1%+M 5% 처리구의 돈육은 저장 12일까지 명도(L)의 변화가 비슷한 경향을 보였다. 적색도(a)의 경우 CMC 0.1%+M 5% 처리구에서 대조구 및 CMC 1% 처리구보다 저장기간에 따른 감소가 적은 것으로 나타났다. 돈육의 TBARS를 측정한 결과 4℃와 25℃에서 저장했을 때 모든 처리구에서 저장기간 중 증가하는 경향이 나타났으며 대조구, CMC 0.1% 처리구, CMC 0.1%+M 5% 처리구 순으로 높아 귤 과피로 코팅한 돈육에서 지질의 산화가 가장 많이 억제되는 것으로 나타났다. 4℃ 및 25℃에서 저장한 돈육의 VBN을 측정한 결과 CMC 0.1%+M 5% 처리구에서 모두 대조구 및 CMC 0.1% 처리구보다 낮은 값을 나타냈다. 피막제로 코팅된 돈육을 4℃에서 저장했을 때 CMC 0.1%+M 5% 처리구의 일반세균 수는 저장 12일째에 7.13±0.96 log CFU/g을 나타내어 다른 처리구보다 3일 정도 일반세균의 증식을 지연시켰다. 25℃에서 저장했을 때 CMC 0.1% 처리구와 CMC 0.1%+M 5% 처리구의 저장 14일째 일반세균 수는 각각 10.61±0.65 log CFU/g, 8.60±0.87 log CFU/g으로 나타나 CMC 0.1%+M 5% 처리구에서 저장기간 동안 일반세균의 증식이 억제되는 것을 확인하였다. 따라서 CMC와 귤 과피 분말을 첨가한 피막제로 돈육을 코팅했을 때 돈육의 저장 중 품질 변화를 적게 하면서 일반세균수의 증가도 지연시키는 효과가 있는 것으로 확인되어 가식성 필름으로서 신선식품의 저장성을 향상시킬 수 있는 효과적인 대안이라 판단된다.