• 한국분말재료학회지
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• 제18권5호
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• pp.437-442
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• 2011

The present study focused on the synthesis of Bi-Te-Se-based powder by an oxide-reduction process, and analysis of the thermoelectric properties of the synthesized powder. The phase structure, chemical composition, and morphology of the synthesized powder were analyzed by XRD, EPMA and SEM. The synthesized powder was sintered by spark plasma sintering. The thermoelectric properties of the sintered body were evaluated by measuring its Seebeck coefficient, electrical resistivity, and thermal conductivity. $Bi_2Te_{2.7}Se_{0.3}$ powder was synthesized from a mixture of $Bi_2O_3$, $TeO_2$, and $SeO_2$ powders by mechanical milling, calcination, and reduction. The sintered body of the synthesized powder exhibited n-type thermoelectric characteristics. The thermoelectric properties of the sintered bodies depend on the reduction temperature. The Seebeck coefficient and electrical resistivity of the sintered body were increased with increasing reduction temperature. The sintered body of the $Bi_2Te_{2.7}Se_{0.3}$ powder synthesized at $360^{\circ}C$ showed about 0.5 of the figure of merit (ZT) at room temperature.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 춘계학술대회 논문집
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• pp.617-620
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• 1999

In this study, the polarization e(fecal and the birefringence effect of amorphous germanium (a-Ge) thin films were investigated by using linearly polarized He-Ne laser beam. The a-7e thin films were deposited on the quarts substrate by plasma enhanced chemical vapor deposition (PECVD) and thermal vacuum evaporation In order to obtain the optimum grating arrays, inorganci resists such as Si$_3$N$_4$ and a-Se$_{75}$ Ge$_{25}$ , were prepared with the optimized thickness by Monte Carlo (MC) simulation. As the results of MC simulation, the thickness ofa-Se$_{75}$ Ge$_{25}$ resist was determined with Z$_{min}$ of 360$\AA$ . The resists were exposed to Ga$^{+}$-FIB with accelerating energies of 50 keV, developed by wet etching, and a-Ge thin film was etched by reactive ion-etching (RIE). Finally, we were obtained grating arrays which grating width and linewidth are 0.8${\mu}{\textrm}{m}$, respectively and we studied the polarization and birefringence effect in transmission grating array made of high refractive amorphous material, and the applicability as waveplates and polarizers in optical device.e.e.

• 한국진공학회지
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• 제6권2호
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• pp.103-108
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• 1997

본 연구에서는 2단계 실리콘 건식식각 공정과 게이트 절연막으로 열산화막과 tetraethylorthosilicate(TEOS) 산화막의 이중막을 사용하고, 스핀-온-그래스 (Spin-on-glass:SOG) 에치백(etch-back) 공정에 의하여 게이트를 제작하는 새로운 방법을 통하여 실리콘 전계방출소자를 제작하고 그 특성을 분석하였다. 게이트 절연막의 누설전류 를 감소시키면서 팁과 게이트의 간격을 줄이는 구조인 이중 게이트 절연막을 형성하기 위하 여 팁 첨예화 산화 공정후 낮은 점도의 감광막(photo resist)을 시료에 도포한 후, $O_2$ 플라 즈마 에싱(ashing)하는 공정을 채택하였다. 이러한 공정으로 제작된 에미터 팁의 높이와 팁 반경은 각각 1.1$\mu\textrm{m}$와 100$\AA$정도이었으며, 256개 팁 어레이에서 전계방출의 문턱전압은 40V 이하이었다. 60V의 게이트전압에서 23$\mu\textrm{A}$(즉, 90nA/팁)의 높은 아노드 전류를 얻을 수 있었 다. 이때, 게이트 전류는 아노드전류의 약0.1%이하였다. 개발된 공정기술로 게이트 개구도 크게 감소시켰을 뿐 아니라, 게이트 누설전류를 현저히 감소시켰다.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2005년도 학술대회 논문집
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• pp.151-155
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• 2005

지금까지의 핵융합 장치는 자기우물과 열역학을 바탕으로 한 토카막 장치가 수소핵융합을 하였으나 고온의 플라스마를 장시간 동안 가둠이란 현실적으로 불가능하여 성공사례가 없었다. 본 핵융합 촉진 방법을 이용한 새로운 핵융합 장치는 토카막 장치의 토로이달 자기장용 알루미늄코일 내에 토러스 철심 C형 Core Block과 토로이달 알루미늄코일을 넣어 토로이달 자기장을 모으고 토로이달 전류 흐르도록 하여 토러스 Core의 일부가 절개된 간극사이에 핵융합로를 배치하고 융합원료(전해액)를 토로이달 전류로 전기분해 한다. 전원과 토로이달 자계용 코일, 토로이달 코일 융합원료로 직렬회로로 이루어져 있어 토로이달 전류는 필라멘트 전류로 되어 융합원료에 투입된다. 필라멘트 전류사이에는 자기흡입력이 외부의 입력전력으로 계속 증대되어 쿨롱에 힘을 넘어 핵융합에 이르고 그로인해 질량결손이 생겨 아인슈타인의 질량에너지$(E=mC^2)$가 빛에너지와 열에너지로 방출됨을 확인했다.

• 한국재료학회지
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• 제30권7호
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• pp.350-358
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• 2020

A variety of composite powders having different aluminum and carbon contents are prepared using various organic solvents having different amounts of carbon atoms in unit volume as ball milling agents for titanium and aluminum ball milling. The effects of substrate temperature and post-heat treatment on the texture and hardness of the coating are investigated by spraying with this reduced pressure plasma spray. The aluminum part of the composite powder evaporates during spraying, so that the film aluminum content is 30.9 mass%~37.4 mass% and the carbon content is 0.64 mass%~1.69 mass%. The main constituent phase of the coating formed on the water-cooled substrate is a non-planar α₂ phase, obtained by supersaturated carbon regardless of the alloy composition. When these films are heat-treated at 1123 K, the main constituent phase becomes γ phase, and fine Ti₂AlC precipitates to increase the film hardness. However, when heat treatment is performed at a higher temperature, the hardness is lowered. The main constitutional phase of the coating formed on the preheated substrate is an equilibrium gamma phase, and fine Ti₂AlC precipitates. The hardness of this coating is much higher than the hardness of the coating in the sprayed state formed on the water-cooled substrate. When hot pressing is applied to the coating, the porosity decreases but hardness also decreases because Ti₂AlC grows. The amount of Ti₂AlC in the hot-pressed film is 4.9 vol% to 15.3 vol%, depending on the carbon content of the film.

• 공업화학
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• 제27권2호
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• pp.165-170
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• 2016

본 연구에서는, 실제 $150000Nm^3/hr$ 규모의 연소로에서 운전된 $VO_x/TiO_2$ SCR 촉매의 활성저하 원인을 규명하고자 XRD, BET, AES ICP, $H_2$-TPR, $NH_3$-TPD 분석을 수행하였다. $TiO_2$의 상전이 및 $VO_x$의 결정화가 발생하지 않았기 때문에 열에 의한 촉매의 활성저하는 없는 것으로 나타났다. 반면, 성분 분석결과 S의 함량이 검출되지 않고 Ca이 다량 검출됨에 따라 $SO_2$에 의한 피독이 아닌 Ca에 의한 피독이 발생하였음을 확인하였으며 이러한 Ca의 피독은 $NH_3$의 흡착량을 감소시켜 반응활성을 감소시키는 것으로 나타났다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2010년도 제39회 하계학술대회 초록집
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• pp.145-145
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• 2010

In this paper, we report that the effects of hydrogen doping on the electrical and optical properties of typical transparent conducting oxide films such as ZnO and $SnO_2$ prepared by magnetron sputtering. Recently, density functional theory (DFT) calculations have shown strong evidence that hydrogen acts as a source of n-type conductivity in ZnO. In this work, the beneficial effect of hydrogen incorporation on Ga-doped ZnO thin films was demonstrated. It was found that hydrogen doping results a noticeable improvement of the conductivity mainly due to the increases in carrier concentration. Extent of the improvement was found to be quite dependent on the deposition temperature. A low resistivity of $4.0{\times}10^{-4}\;{\Omega}{\cdot}cm$ was obtained for the film grown at $160^{\circ}C$ with $H_2$ 10% in sputtering gas. However, the beneficial effect of hydrogen doping was not observed for the films deposited at $270^{\circ}C$. Variations of the electrical transport properties upon vacuum annealing showed that the difference is attributed to the thermal stability of interstitial hydrogen atoms in the films. Theoretical calculations also suggested that hydrogen forms a shallow-donor state in $SnO_2$, even though no experimental determination has yet been performed. We prepared undoped $SnO_2$ thin films by RF magnetron sputtering under various hydrogen contents in sputtering ambient and then exposed them to H-plasma. Our results clearly showed that the hydrogen incorporation in $SnO_2$ leads to the increase in carrier concentration. Our experimental observation supports the fact that hydrogen acting as a shallow donor seems to be a general feature of the TCOs.

• 한국초전도ㆍ저온공학회논문지
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• 제21권2호
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• pp.36-39
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• 2019

Effects of the spherically shaped Ge and the rod-like carbon-coated Ge on the superconducting properties of $MgB_2$ were investigated. Pure Ge and carbon-coated Ge nano-powders were synthesized under the different amount of $CH_4$ (0 to 5 kPa) by using DC thermal plasma method. When the $CH_4$ was added ~100 nm sized Ge with a spherical shape changed to rod-like morphology with a diameter of ~30-70 nm and a length of ~400-500 nm. Also it was confirmed that thin carbon layers of a few nanometers were formed along the rod length and the agglomerated carbons were found on the edges of rods. Pure spherical Ge and Ge/C rods were mixed and milled with Mg & B precursor to form the doped $MgB_2$ bulk samples by the solid-state reaction method. Almost no change of $T_c$ was noticed for the pure Ge-added $MgB_2$, whereas $T_c$ was found to decrease with the Ge/C-added $MgB_2$ samples. It was found that the pure spherical Ge showed to have a negative effect on the flux pinning of $MgB_2$. However, Ge/C rods can enhance the flux pinning property of $J_c$ due to the coated carbon on Ge rods.

• 대한화장품학회:학술대회논문집
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• 대한화장품학회 2003년도 IFSCC Conference Proceeding Book I
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• pp.601-610
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• 2003

Biotin is a water-soluble vitamin used as a skin conditioning agent and promotes the formation of intercellular lipid layers through increased lipid synthesis, which improves the skin's natural barrier function. The anti-inflammatory effects of biotin have been investigated using in vitro assay models, such as MTT assay, measurements of concentrations of nitric oxide(NO), prostaglandin E2(PGE$_2$), and inhibition rate of 5-lipoxygenase(5-LOX). In comparison with biotin, other plant extracts were tested at the same time which were kudzu vine extract, sage extract, paeonia extract, and dipotassium glycyrrhetinate. Nitric oxide is a signal molecule with functions such as neurotransmission, local vascular relaxation, and anti-inflammation in many physiological and pathological processes. NO can cause apoptosis and necrosis of target cells such as keratinocytes and is generated from L-arginine by nitric oxide synthase (NOS). Prostanoids, including prostaglandins and thromboxanes, are generated by the phospholipase $A_2$/cyclooxygenase(COX) pathway, and leukotrienes are generated by the 5-lipoxygenase pathway from arachidonic acid. Prostaglandin E2 recently have been shown to be beneficial in the resolution of tissue injury and inflammation, also has been implicated as an immunosuppressive agent and plasma levels of PGE$_2$ are elevated in patients sustaining thermal injury. Lipoxygenase metabolites from arachidonic acid have been implicated in inflammation, anti-inflammatory activity of the raw materials was evaluated in vitro by the offered inhibition of lipoxygenase.

• Journal of Digestive Cancer Research
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• 제2권1호
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• pp.1-4
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• 2014

Palliative care for cancer aims to relieve the discomfort and pain from the cancer itself and associated conditions. Gastrointestinal cancers originate from the tube like structure of gastrointestinal tract and cause complications such as obstruction, bleeding, adhesion, invasion, and perforation to adjacent organ. Recent advances in interventional endoscopy enables endoscopy physicians to do safe and effective care for gastrointestinal cancer patients. Endoscopic palliation includes stent, hemostasis, nutritional support and targeted drug delivery. Self expandable metallic stent is one of the most important modalities in gastrointestinal palliation. Through the endoscopy or over the wire pre-placed by endoscopy, stents restore the gastrointestinal luminal patency and relieve the obstructive condition. Endoscopic hemostasis is another important palliation in gastrointestinal cancer patients. Epinephrine injection, argon plasma coagulation and thermal cauterization are usual modalities for hemostasis. Histoacryl glue and fibrin glue are also available. Hemostatic nanopowder spray is newly reported effective in benign disease and is supposed to be effective also in cancer bleeding. Enteral feeding tubes including gastro- or jejunostomy and nosoduodenal tubes are placed by using endoscopic guidance. Enteral feeding tubes role as the route of easily absorbable or semi-digested nutrients and effectively maintain both patients calorie requirements and gut microenvironment. Photodynamic therapy is the one of the outstanding medical employments of photo-physics. Especially for superficial cancers in esophagus, photodynamic therapy is very useful in cancer removal and maintaining organ structure. In biliary neoplasm, photodynamic therapy is well known to be effective in cancer ablation and biliary ductal patency restoration. Targeted drug delivery is the lastest issue in palliative endoscopy. Debates and questions are still on the table. In this article, the role of endoscopic interventions in palliative care for the gastrointestinal tumors will be thoroughly reviewed.