• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 1991년도 제1차 학술발표초록집
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• pp.29-29
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• 1991

• 대한기계학회논문집B
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• 제38권8호
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• pp.695-700
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• 2014

본 논문에서는 수정된 증발법을 이용하여 제작된 주석(Sn) 나노입자의 녹는점 강하 특성에 대한 연구를 진행하였다. 이를 위해 대량생산이 가능한 수정된 증발법을 이용하여 10nm 급 주석 나노입자를 제조하였다. 주석 나노입자 표면의 산화 방지를 위하여 Benzyl Alcohol 을 기본유체로 사용하였으며, 제작된 주석 나노입자의 형상과 입자크기를 알아보기 위하여 투과전자현미경(TEM)을 사용하였다. 제작된 나노입자의 녹는점은 시차주사열량계(DSC)를 통해 측정하였으며, 광전자분광분석기(XPS)를 사용하여 제작된 주석 나노입자의 성분 분석을 진행 하였다. 주석 나노입자의 녹는점은 주석의 녹는점인 $232^{\circ}C$보다 44% 감소한 $129^{\circ}C$로 측정되었다. 녹는점 측정 결과는 Gibbs-Thomson 식 및 Lai 의 식과 비교하였으며, 그 결과 Lai의 식이 실험결과를 잘 예측함을 확인할 수 있었다.

• Bulletin of the Korean Chemical Society
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• 제18권1호
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• pp.38-43
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• 1997

Poly(ethylene 2, 6-naphthalate-co-tetramethylene 2, 6-naphthalate) (PEN/PBN) copolymers were synthesized and studied by 13C NMR spectroscopy, DSC analysis and X-ray diffraction. A minimum in the melting point vs. composition curve was found at approximately 60 mol% tetramethylene 2, 6-naphthalate. The PEN/PBN copolymers were shown to be statistically random throughout the range of 1, 4-butanediol compositions. The melting point depression behavior of annealed PEN/PBN copolymers depended upon the sequence propagation probability, PS, which is suggested by indivisual crystal formation of two pure comonomers; that is, ethylene-naphthalate-ethylene, EE, and tetramethylene-naphthalate-tetramethylene, BB. However, it can be seen from the X-ray curve that the peaks of PEN/PBN copolymers appear from a crystal lattice which is governed only by the rich component between two different aliphatic units in the copolymer composition.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.376-376
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• 2012

Semiconductor nanowires (NWs) are future building block for nano-scale devices. Especially, Ge NWs are fascinated material due to the high electrical conductivity with high carrier mobility. It is strong candidate material for post-CMOS technology. However, thermal stability of Ge NWs are poor than conventional semiconductor material such as Si. Especially, when it reduced size as small as nano-scale it will be melted around CMOS process temperature due to the melting point depression. Recently, Graphene have been intensively interested since it has high carrier mobility with single atomic thickness. In addition, it is chemically very stable due to the $sp^2$ hybridization. Graphene films shows good protecting layer for oxidation resistance and corrosion resistance of metal surface using its chemical properties. Recently, we successfully demonstrated CVD growth of monolayer graphene using Ge catalyst. Using our growth method, we synthesized Ge/graphene core/shell (Ge@G) NW and conducted it for highly thermal stability required devices. We confirm the existence of graphene shell and morphology of NWs using SEM, TEM and Raman spectra. SEM and TEM images clearly show very thin graphene shell. We annealed NWs in vacuum at high temperature. Our results indicated that surface melting phenomena of Ge NWs due to the high surface energy from curvature of NWs start around $550^{\circ}C$ which is $270^{\circ}C$ lower than bulk melting point. When we increases annealing temperature, tip of Ge NWs start to make sphere shape in order to reduce its surface energy. On the contrary, Ge@G NWs prevent surface melting of Ge NWs and no Ge spheres generated. Furthermore, we fabricated filed emission devices using pure Ge NWs and Ge@G NWs. Compare with pure Ge NWs, graphene protected Ge NWs show enhancement of reliability. This growth approach serves a thermal stability enhancement of semiconductor NWs.

• Macromolecular Research
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• 제13권4호
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• pp.297-305
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• 2005

The compatibilizing effect of maleic anhydride (MA) in the immiscible blends of EVA22 (vinyl acetate content 22%)/ethylene-${\alpha}$-olefin copolymers with 1-butene (EtBC) and 1-octene (EtOC)) comonomers was studied. By adding 1, 2, and 3 phr of MA in the presence of dicumylperoxide, the morphology, tensile strength at break, and 100 and 300 % modulus of EVA22/EtBC and EVA22/EtOC blends were significantly enhanced. The melting point and crystallization point depression were observed upon the addition of MA. The changes in the ${\beta}$ transition and glass transition temperature of ethylene-${\alpha}$-olefin copolymers and ethylene-vinyl acetate copolymers, respectively, indicate that MA plays a role of compatibilizer for these immiscible blends. The TGA thermograms, measured from the blends with MA, show that thermal stability is slightly enhanced with MA, indicating that MA acts as a reinforcing agent either by grafting or crosslinking with other copolymers.

• Bulletin of the Korean Chemical Society
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• 제10권2호
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• pp.123-128
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• 1989

Calorimetric study in conjunction with Fourier-transform infrared (FTIR) spectroscopic study was carried out on the blends of poly(ethylene oxide) (PEO) with isotactic, atactic and syndiotactic poly(methyl methacrylate) (i-, a-, and s-PMMA). From the differential scanning calorimetric (DSC) measurements, the three types of blends show a depression of the melting temperatures. This indicates that PEO is compatible with i-, a-, and s-PMMA. But the largest melting point depressions of PEO are always found in the blends with s-PMMA. For PEO/a-PMMA and PEO/s-PMMA, the degree of crystallinity as a function of composition deviates substantially from that of the ideal blend in which no interaction between the components exists. The FTIR spectra of all three types of blends are recorded. In order to observe the microstructural changes of PEO in blends, we analyzed the spectra using digital weighted subtraction and addition techniques. It was concluded that the microstructures of PEO are strongly perturbed by the PMMA's. Among these blends PEO microstructure in PEO/s-PMMA blends is most greatly influenced. It indicates that the blending is most preferred with s-PMMA than a- and i-PMMA. It can be explained on the basis of the molecular structure of PMMA's.

• Elastomers and Composites
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• 제36권3호
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• pp.169-176
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• 2001

2몰% 에틸가지를 포함하는 에틸 가지화 폴리에틸렌[(PE(2)]과 에틸렌-프로필렌 몰비가 50:50으로 같지만 입체규칙성이 서로 다른 랜덤-에틸렌-프로필렌 고무(r-EPR), 교호-에틸렌-프로필렌 고무(alt-EPR) 및 이소탁틱-교호-에틸렌-프로필렌 고무(iso-alt-EPR)를 에틸렌-프로필렌 고무의 입체규칙성에 대한 혼화성과 물성의 차이를 조사하기 위하여 혼합하였다. 이 세가지 블렌드들은 상온에서 상호간에 혼화성이 없었고, 밀도 측정에서 단순한 첨가 효과를 보여 주었다. 블렌드 조성에 따른 폴리에틸렌의 녹는점 감소는 PE(2)/r-EPR>PE(2)/alt-EPR>PE(2)/iso-alt-EPR의 순서로 증가하였다. 인장시험에서 이 블렌드계는 혼합 조성이 50:50 일때 가장 낯은 파난강도의 값을 보여 주어 이 블렌드 조성에서 두 고분자 상(phase)이 가장 분리된 형태학(morphology)을 가지고 있음을 알았다.

• 대한치과의사협회지
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• 제11권1호
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• pp.45-52
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• 1973

Ketamine HC1(Phencyclidine derivative) is a white, crystalline substance with melting point 259℃. It is soluble in water to a 20% clear, colorless solution. a 10% aqueous solution has a pH 3.5. The chemical structure is 2-(O-chlorophenyl)-2-(methylamino) cyclohexanone hydrochloride. It is a rapid acting, nonhypnotic, nonbarbiturate drug with a wide safety margin. The author used the anesthetic ketamine hydrochloride for oral surgery procedure in 16 patients(2 to 33 years). Anesthesia was achieved with a single intramuscular injection by introduction of manufacture. Result obtained as follows : 1. It was easily administered. 2. Onset time was rapid and duration was short. 3. The mild cardiac stimulation resulted in moderate increase in the blood pressure and pulse. 4. There was no significant respiratory depression. 5. The airway can be maintained without artificial support or endotracheal intubation. 6. All protective reflex maintained, which was important in oral surgery. 7. The best results were achieved in pediatric patients than adults.

• 마이크로전자및패키징학회지
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• 제18권4호
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• pp.27-32
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• 2011

Tin(II) acetate와 tin(II) chloride의 주석 precursor를 사용하여 상온에서의 강제 환원 반응으로 주석 나노 입자를 합성시켰다. 0.015 g의 동일한 PVP 양을 첨가한 조건에서 PVP의 분자량이 클수록 비정상적으로 큰 입자들의 생성율이 증가되어 입도 범위가 매우 넓은 주석 나노 입자들이 생성됨을 확인할 수 있었다. 합성된 주석 나노 입자를 함유하는 DEG 용액의 DSC 분석 결과 1차 가열에서는 35 nm 미만 특정 크기 입자들의 수가 충분한 경우에서 DEG의 증발 흡열피크 외에도 특정 크기 입자들의 융점 강하 흡열 피크가 구분되게 검출되었다. 1차 DSC 측정 중 용융된 주석 나노 입자들은 서로 접촉하며 뭉쳐지는 현상이 발생하므로 2차 가열시에는 벌크 주석의 용융 피크에 해당하는 $232^{\circ}C$ 흡열 피크만이 관찰되었다.

• 한국포장학회지
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• 제5권2호
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• pp.1-8
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• 1999

The state of compatability of poly(vinyl alcohol)(PVA) and methyl cellulose(MC), prepared by an aqueous solution casting, were investigated over the entire compositions by dynamical mechanical analyzer(DMA) and differential scanning calorimetry(DSC). The glass transition temperatures of the blends, estimated by DMA, indicate that the blends of PVA and MC showed a definite degree of partial miscibility by showing two glass transition temperatures below 80 wt % MC contents in the blends and one glass transition temperature above 80 wt % of MC contents. The DSC results show a depression of melting point and crystallization temperature of PVA in the blends containing more than 80 wt % MC. This indicates that a considerable compatibility in the blend above 80 wt % MC contents may be attribute to the presence of interaction of hydroxyl groups of component polymers through hydrogen bonding. The DMA study of the effect of plasticizer on the polymers showed that water was a good plasticizer for PVA and PEG400 for MC. The addition of water and PEG400 in the blends showed a synergic plasticizing effect on these blends, which resulted in the large extent of the improvement of the compatibility. The elongation of PVA, MC and blonds was found to increase with addition of PEG400 in the blends, but the tensile strength to decrease with addition of plasticizer.