• 전기의세계
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• v.23 no.6
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• pp.49-55
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• 1974

Amorphous semiconductor from As 30 Te 48 Ge 10 Si 12 was prepared, and studied electron microscopy, X-ray analysis and resistivity measurement. It's resistivity is 1.56*10$^{6}$ .ohm.-cm when small ampule is used for preparing sample it is found that no phase separation has occurced by electron microscopy, and that phase transition temperature is 232.deg. C by differential Thermal Analysis. The specimen showed threshold switching that the low resistance state occur at critical electric field and the resistance recover at low applied field. Critical electric field of the switching is 10$^{5}$ V/cm at room temperature. Threshold voltage secreace exponentially with increasing ambient temperature and at that each voltage resistance of the switching device increase exponentially. According to the series resistance and applied vottage current slope on the V-I curve is varied. When applied voltage is decreased after switching, the resistance of the switching device is increased. By this result the origin of the switching is the Joule's heating.

• Journal of the Semiconductor & Display Technology
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• v.19 no.3
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• pp.36-42
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• 2020

Silver nanowire (AgNW) random-meshes with high transmittance, low sheet resistance, and high oxidation stability and flexibility were fabricated using solution-based processes. The random-mesh structure was obtained by forming bubbles whose sizes and densities were controlled using a corona treatment of polyethylene terephthalate (PET) substrates. To reduce the sheet resistance of the fabricated AgNW electrode, a washing process using ethanol solution was performed. In addition, nickel (Ni) was coated on AgNW to improve resistance to oxidation. The effects of corona treatment and Ni-coating on the transmittance, sheet resistance, oxidation stability, and flexibility of the AgNW electrodes were investigated.

• Journal of Veterinary Clinics
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• v.17 no.2
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• pp.490-494
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• 2000

2달령의 수컷 로트와 일러가 4일간 설사와 통증.보행 실조 등의 증상을 보여 (주)해 마루 소동물 임상 의자 연구소에 의뢰되었다 흉부 방사선 검사에서 폐야 전반에 걸친 페포성 침윤과 흉벽의 심란 비후가 관찰되어 흉막폐렴으로 진단하였으며 복강 초음파 검사에서 상 복부에서 소량의 복수가 관찰되었고 전반적인 간 echogenicity가 증가되어 있었다. 치료 후 설사 증상은 사라지고 전신 상태가 다소 호전되어 내원 후 7일째에 흉부 방사선 검사를 재 실시하였다. 흉막과 폐의 병변은 변화가 없었으나 상완골과 요골의 골간단 부분에 이상 소견 이 발견되어 골격계 방사선 검사를 실시한 결과 상완골, 요골, 대퇴골 그리고 경골의 골간단에 경화성 변화와 무정형의 골막 반응이 관찰되었고 요골, 척골과 경골의 골간단 부분에 성 장판 외의 방사선 투과성 선이 관찰되었다. 이상의 특이적인 방사선 소견을 바탕으로 비록 본 질환의 정확한 원인은 밝힐 수 없었으나, 감염성 원인에 의한 비대성 골이형성증으로 진단하였다.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2000.05a
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• pp.1-4
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• 2000

본 논문에서는 패턴 데이터(pattern data) 의 분할(partitioning)위하여, 계산량의 단축할 수 있는 효과적인 퍼지 클러스터링 알고리즘(fuzzy clustering algorithm)을 제시한다. 본 논문에 제시된 알고리즘은 두 단계로 수행된다. 첫번째 단계는, 개선된 FCM(Fuzzy C-means)방법에 의해 입력 패턴틀에 대해, 단지 두 번의 반복 수행과정만을 거쳐, 충분히 많은 개수의 초기 클러스터 중 심(center)를 결정한다. 다음 단계에서는, 본 논문에 제시될 클러스터 합치기 알고리즘(cluster merging algorithm)을 통해 각 클러스터의 부피(volume)에 따라 클러스터들을 합치는 과정(merging process)을 하게 된다. 결과적으로 일정한 제한된 개수의 무정형(amorphous)의 클러스터틀의 효과적으로 표현될 수 있다. 본 논문의 마지막에 제시될 실험 결과들은 제시된 방법의 유용성을 보여줄 것이다.

• Electrical & Electronic Materials
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• v.4 no.4
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• pp.338-343
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• 1991

활성화된 반응성 증발법을 이용하여 비저항 .rho.=1*$10^{-3}$.OMEGA..cm, 이동도 .mu.=4*$10^{3}$$cm^{2}$/V.sec이고 두께가 약 400.angs.인 In$_{2}$O$_{3}$ 박막을 실온에서 유리기판에 생성시켰다. 광투과율은 파장 400-800nm범위에서 80% 이상으로 나타났고 구조는 무정형인 것으로 나타났다. 낮은 저항의 In$_{2}$O$_{3}$ 박막은 Ar과 $O_{2}$의 압력을 적적히 조절함으로서 얻을 수 있을 것으로 분석되었고 약 350.deg.C의 온도로 30분간 열처리로서 정형화할 수 있는 것으로 판단되었다. 또한 증발율, 이동도 및 저항과 캐리어 농도와의 상관관계도 고찰하여 보았다.

• Journal of Powder Materials
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• v.30 no.1
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• pp.47-52
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• 2023

The purpose of this study is to develop and evaluate amorphous spray-dried microparticles (SDM) containing levosulpiride to increase its solubility. SDM are prepared via solvent evaporation using polyvinylpyrrolidone (PVP) as the water-soluble polymer and Cremophor RH40 as the surfactant. The SDM is prepared by varying the amounts of PVP and Cremophor RH40, and its physicochemical properties, solubility, and dissolution are confirmed. All levosulpiride-loaded SDMs converted the crystalline drug into an amorphous form, significantly improving drug solubility and dissolution compared with the drug alone. SDM consisting of drug/PVP/Cremophor RH40 in a weight ratio of 5:10:3, with increased solubility (720 ± 36 vs. 1822 ± 51 ㎍/mL) and dissolution rate (10.3 ± 2.2 vs. 92.6 ± 6.0%) compared with drug alone, shows potential as a commercial drug for improved oral bioavailability of levosulpiride.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1B
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• pp.107-111
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• 2006

The samples collected from two reactors are analyzed by X-ray diffraction and M$\ddot{o}$ssbauer spectroscopy in this study. It is concluded that the iron oxide crystal attached on anthracite media which possesses catalytic ability is identified to be Ferrihydrite, regardless of the value of pH from the analysis of the iron oxide. Iron oxide in Batch reactor is identified to be Microcrystalline goethite.

• Resources Recycling
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• v.17 no.6
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• pp.34-42
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• 2008

The properties of sodium silicate solution were surveyed by using the yellow silicomolybdic method, and the formation of silica sol from sodium silicate solution and the growth of silica sol were investigated in this study. The $SiO_2$ content of 2 wt% in sodium silicate solution was proper to oxidize sodium silicate with sulfuric acid. After the removal of sodium ions in sodium silicate solution, the pH of silicate solution had to be controlled above 9 for the stabilization of silicate solution. The condensation between silicic acid species and silica nuclei surfaces has been studied at $20{\sim}80^{\circ}C$ and pH 10 in silicate solutions with silica nuclei. The reaction falls into two kinetics regimes, limited at high silicic acid species concentration by polymerization, but at lower concentration by a process whereby deposited silicic acid species condenses further to silica. The overall condensation is first-order in silicic acid species concentration, proceeded toward to pseudo equilibrium concentration, $C_x$, rather than the solubility of amorphous silica. The heat of solution of amorphous silica was 3.34 kcal/mol and exhibits an Arrhenius temperature dependence with an apparent activation energy of 3.16 kcal/mol in the range of $20{\sim}80^{\circ}C$.

• Applied Chemistry for Engineering
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• v.27 no.1
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• pp.86-91
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• 2016

Three amorphous silicas and SBA-15 were employed as supports, which were capable of confining ionic liquid (IL) and metallocene in the nanopore. Ionic liquid functionalized silica was prepared by the interaction between the chloride anions of 1,3-bis(cyanomethyl)imidazolium chloride and the surface OH groups. Metallocene and methylaluminoxane (MAO) were subsequently immobilized on the ionic liquid functionalized silica for ethylene polymerization. The metallocene supported on ionic liquid functionalized XPO-2412 and XPO-2410 having a larger pore diameter compared to SBA-15 showed higher activity than that of using supported catalyst without ionic liquid functionalization. However, the activity of metallocene supported on SBA-15 decreased after ionic liquid functionalization, suggesting that the diffusion of ethylene monomer and cocatalyst to the active site of nanopore was restricted during ethylene polymerization. This could be resulted from significant reduction of the pore diameter due to the immobilization of ionic liquid and $(n-BuCp)_2ZrCl_2$ and MAO. The effect on polymerization activity in accordance with the concentration of hydroxyl groups on the surface was also investigated. The polymerization activity increased as the concentration of hydroxyl groups on amorphous silica increased. The polymerization activities of metallocene supported on silica showed the similar trend after ionic liquid functionalization.

• Membrane Journal
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• v.17 no.2
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• pp.81-92
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• 2007

Membrane-based separation processes are receiving increasing attention in the scientific community and industry since they provide a desirable alternative to processes that are not easy to achieve by conventional separation technologies. In particular, gas separation using polymeric membranes have annually grown so fast owing to advantages such as easy installation, no moving parts, small footprint and low energy process. The key element is definitely a polymer membrane exhibiting high permeability and high selectivity to compete with other gas separation technologies. Current polymer membranes used for commercial gas separation are a family of hydrocarbon polymers for hydrogen separation, air separation and carbon dioxide separation from natural gas sweetening. Relatively, gas or vapor separation properties of fluoropolymers are not known so much as compared with those of hydrocarbon polymers. Accordingly, in this study, membranes prepared from amorphous perfluoropolymers are of particular interest because of the unique properties of these polymers. The advantages offered by these amorphous perfluoropolymers for use in gas and vapor separation will be discussed. In addition, membrane properties and separation performance will be compared with other membranes available on the market.