• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.02a
• /
• pp.502-502
• /
• 2011

기존 연구에서는 단일 타겟으로부터 증착된 코팅층 내에 다상으로 이루어진 나노 복합구조를 형성하기 위하여, 나노 합금분말을 방전플라즈마 소결법 등으로 급속 소결하여 타겟을 제조하는 방법이 고려되어 왔다. 반면, 비정질 재료가 우수한 비정질 형성능을 가지는 경우 주조 방법에 의해서도 타겟 제조가 가능하며, 특히 최근 들어 금속 비정질 합금에서 합금의 주요 구성 원소들이 양의 혼합열을 가지는 경우, 액상 또는 과냉각 액상에서 상분리 현상이 발생한다는 것이 밝혀졌다. 이러한 사실에 기초하면, 우수한 비정질 형성능을 가지는 합금 시스템에 합금 구성 원소와 양의 혼합열 관계를 갖는 원소를 첨가함으로써, 비정질 기지 내에 화학적 불균일성을 유도하여 다상으로 이루어진 복합 구조를 형성시키는 것이 가능하다. 본 연구에서는 이러한 합금 설계법을 이용하여, 비정질 기지 내에 존재할 수 있는 불균일성 정도를 합금 조성과 주조 조건의 변화를 통하여 나노 크기에서 원자 크기까지 조절하고, 이에 따른 재료 특성과의 상관관계를 밝히고자 하였다. 이를 위하여 우수한 비정질 형성능을 가지는 Cu-(Zr, Hf)-Al 벌크 비정질 합금계에서 (Zr, Hf)과 (Y, Gd)간의 양의 혼합열 관계에 주목하여 Cu-(Zr, Hf)-(Y, Gd)-Al 벌크 비정질 형성 합금계를 설계하였으며, 이 합금계 내에서 조성과 냉각속도의 조절에 따라 나타나는 불균일성의 정도와 특성변화의 영향을 체계적으로 고찰하였다. 결과로서, Cu-(Zr, Hf)-Al 합금계에서 (Zr, Hf)을 (Y, Gd)으로 15 at.% 이상 치환한 경우, Cu-(Zr, Hf)-rich 와 Cu-(Y, Gd)-rich 비정질상으로 이상분리가 일어났으며, 이렇게 생성된 비정질-비정질 복합재는 응력 하에서 소성 변형을 거의 보이지 않았다. 반면, 5 at.% 이하로 (Zr, Hf)을 (Y, Gd)으로 치환한 경우에는 비정질 기지에 SAXS 혹은 WAXS로 확인 가능한 원자 크기의 불균일성이 나타났으며, 이 경우 비정질 합금의 점성 유동의 변화를 통해 합금의 연신 특성이 향상되었다. 특히, 본 연구에서는 비정질 기지내 불균일 제어를 통한 기계적 특성 향상을 위해서 조성 제어뿐 아니라 동역학적인 요소를 고려한 냉각속도 조절을 통한 원자단위 불균일성의 최적화가 필요함을 규명하였다. 이러한 연구 결과는 분말화 및 소결 과정을 배제하고 제조된 단일 타겟을 통해 코팅층에 다수의 합금원소를 혼합하고 나노/원자 스케일의 복합구조 형성 및 고집적화가 가능한, 타겟 모물질 설계의 새로운 방향을 제시함으로써 다기능성 복합소재 코팅층의 연구에 크게 기여할 것으로 사료된다.

• Polymer(Korea)
• /
• v.38 no.4
• /
• pp.530-534
• /
• 2014

Polyethylene (PE) membranes having various porosities are used as microfilters and separators in lithium ion batteries. Membranes having a high porosity are required for use as separators in a large scale lithium ion secondary battery. In this study, BET was examined for use as a new nontoxic diluent for the fabrication of highly porous PE membranes by thermally induced phase separation process. It was confirmed that BET can be used as a new diluent for the fabrication of the PE membranes by exploring upper critical solution temperature type phase behavior of PE mixtures with BET. When the porosity of the membrane prepared from the PE/PO mixture was compared with that prepared from PE/BET mixture, the latter was about 1.8 times higher than the former.

• Membrane Journal
• /
• v.27 no.5
• /
• pp.458-467
• /
• 2017

In this study, we prepared PVDF membranes via TIPS for water treatment applications. PVDF was used for its excellent chemical and mechanical properties. The effect of coagulation bath composition, temperature, and heat capacity on the overall membrane morphology was studied and observed using SEM. A mixture of DOP and DBP was used as the diluent, and silica was used as an additive. It was observed that as the heat capacity of the coagulation bath increased, the crystallization rate of PVDF decreased yielding larger pores. Also, as the heat capacity of the coagulation bath decreased, the crystallization rate of PVDF increased yielding smaller pores.

• Textile Coloration and Finishing
• /
• v.15 no.4
• /
• pp.57-64
• /
• 2003

Poly(ethylene-co-vinyl acetate)(EVA) microspheres were prepared by a thermally induced phase separation. The microsphere formation occurred by the nucleation and growth mechanism in the metastable region. The diluent used was toluene. The microsphere formation and growth was followed by the cloud point of the optical microscope measurement. The microsphere size distribution, which was obtained by SEM observation and particle size analyzer, became broader when the polymer concentration was higher, the content of vinyl acetate in EVA copolymer was higher, and the cooling rate of EVA copolymer solution was lower.

• Journal of the Korean Applied Science and Technology
• /
• v.28 no.4
• /
• pp.386-392
• /
• 2011

We are crystallized to the linear low density polyethylene(LLDPE) particles by a thermally induced phase separation(TIPS). TIPS process based on the phase separation mechanism was performed for the LLDPE system which undergoes liquid-solid phase separation. The linear low density polyethylene particle formation occurred by the nucleation and growth mechanism in the metastable region. Although the growth rates depended on the experimental conditions such as the polymer concentration and temperature, the particles were larger when the polymer concentration was higher or temperature was higher. The particles were observed by SEM. The LLDPE particle size distribution became broader when the polymer concentration was higher.

• Computational Structural Engineering
• /
• v.11 no.1
• /
• pp.96-106
• /
• 1998

본 연구에서는 복잡한 비선형시스템의 전체적 응답거동의 중요한 (그리고 잠재적으로 유익한) 특성을 상세히 분석하였다. 특히 강성도 및 여기력에 내재된 복잡한 비선형을 소유하는 수중다점계선해양시스템의 분기집합에 내재된 초구조와 혼돈거동의 가능경로에 대하여 해석적 및 수치적으로 분석하였다. 분기는 국부적 안정해석을 통하여 매개변수 영역상에서 확인되었으며, 정상 상태의 분기초구조는 수치해석을 통하여 밝혀졌다. 비선형정도와 해의 차원을 나타내는 공명수를 유도하였으며, 차수공명수를 통해 공명주위의 구조를 밝혔으며 열조화, 울트라조화, 울트라열조화 등과 같은 고도의 비선형 응답의 발생을 예측할 수 있음을 보였다. 결과에서 얻은 초구조는 시스템의 안정성과 이상끌개의 징후를 지배하는 메커니즘임도 밝혔다. 혼돈으로 가는 주기증가의 무한시퀀스에 대한 유연한 변환 외에 돌연한 격발(saddle에 의해 분리된 인접끌개의 충돌)로 인한 혼돈으로의 가능경로도 발견되었으며 이는 수치적으로도 입증되었다.

• Membrane Journal
• /
• v.23 no.5
• /
• pp.332-342
• /
• 2013

In the present study, carbon molecular sieve (CMS) hollow fiber membranes were prepared by carbonizing a methyl imide hollow fiber precursor, which was spun by non-solvent induced phase separation process. And effects of carbonization parameters such as pre-oxidation, pyrolysis, and post-oxidation on the gas permeation were systematically investigated. CMS membrane having the highest gas flux was obtained by carbonizing the precursor through a combined process of air pre-oxidation at $250^{\circ}C$ for 2h, nitrogen pyrolysis at $550^{\circ}C$ for 2h, and oxygen post-oxidation at $250^{\circ}C$ for 2h. The optimized membrane showed a considerable gas permeance : the $H_2$, He, $CO_2$ permeances were 69.72, 35.61, 31.01 GPU, respectively, and the $O_2$ and $N_2$ permeances were ignorable. Therefore, it was clear that the prepared CMS hollow fiber membrane was a promising membrane for recovering small gases such as hydrogen and hellium and carbon dioxide.

• Membrane Journal
• /
• v.28 no.4
• /
• pp.221-232
• /
• 2018

The silica containing carbon ($C-SiO_2$) membranes were fabricated using poly(imide siloxane)(Si-PI) and polyvinylpyrrolidone (PVP) blended polymer. The characteristics of porous carbon structures prepared by the pyrolysis of polymer blends were related with the micro-phase separation behaviors of the two polymers. The glass transition temperatures ($T_g$) of the mixed polymer blends of Si-PI and PVP were observed with a single $T_g$ using differential scanning calorimetry. Furthermore, the nitrogen adsorption isotherms of the $C-SiO_2$ membranes were investigated to define the characteristics of porous carbon structures. The $C-SiO_2$ membranes derived from Si-PI/PVP showed the type IV isotherm and possessed the hysteresis loop, which was associated with the mesoporous carbon structures. For the molecular sieving probe, the $C-SiO_2$ membranes were prepared with the ratio of Si-PI/PVP and the pyrolysis conditions, such as the pyrolysis temperature and the isothermal times. Consequently, the $C-SiO_2$ membranes prepared by the pyrolysis of Si-PI/PVP at $550^{\circ}C$ with the isothermal time of 120 min showed the $O_2$ permeability of 820 Barrer ($1{\times}10^{-10}cm^3(STP)cm/cm^2{\cdot}s{\cdot}cmHg$) and $O_2/N_2$ selectivity of 14.

• Journal of fish pathology
• /
• v.12 no.2
• /
• pp.89-99
• /
• 1999

New sixteen heat shock proteins (Hsps) and ten ethanol shock proteins were appeared on the analysis with SDS-PAGE when cultivation temperature for the Vibrio vulnifrcus ATCC 27562 strain was shifted-up to $42^{\circ}C$ from $30^{\circ}C$ for 20 mins and treated with of 6% ethanol for 10 mins, respectively. Even the induction of thermotolerance in V. vulnificus was coincided with the induction of Hsps if the pre-shock was adjusted to thermal temperature. Outer membrane proteins (OMPs) that were purified from the membrane of cells after heat shock showed more immunodominant pattern to the immunized rabbit anti-V. vulnificus O serum in enzyme-linked immunosorbent assay (ELISA). On the western immunoblot analysis it was confirmed that both 62 kDa IMP and 69 kDa OMP in the Hsps and 48 kDa IMP a major OMP in the ethanol shock proteins were reacted with rabbit anti-V. vulnificus O sera. Agglutination titer of the heat shocked V. vulnificus with rabbit anti-V. vulnificus O serum was higher than that of the untreated bacteria.

• Radiation Oncology Journal
• /
• v.24 no.1
• /
• pp.51-57
• /
• 2006

Puroose: We examined whether intratumoral (i.t.) administration of dendritic cells (DCs) into a treated tumor could induce local and systemic antitumor effects in a mouse tumor model. Methods and Materials: C57BL/6 mice were inoculated s.c. in the right and left thighs with MCA-102 fibrosarcoma cells on day 0 and on day 7, respectively. On day 7, the tumors (usually 6 mm in diameter) on the right thigh were heated by immersing the tumor-bearing leg in a circulating water bath at $43^{\circ}C$ for 30 min; thereafter, the immature DCs were i.t administered to the right thigh tumors. This immunization procedure was repeated on days 7, 14 and 21. The tumors in both the right and left thighs were measured every 7 days and the average sizes were determined by applying the following formula, tumor $size=0.5{\times}(length+width)$. Cytotoxicity assay was done to determine tumor-specific cytotoxic T-lymphocyte activity. Results: Hyperthermia induced apoptosis and heat shock proteins (HSPs) in tumor occurred maximally after 6 hr. For the local treated tumor, hyperthermia (HT) alone inhibited tumor growth compared with the untreated tumors (p<0.05), and furthermore, the i.t. administered DCs combined with hyperthermia (HT + DCs) additively inhibited tumor growth compared with HT alone (p<0.05). On the distant untreated tumor, HT alone significantly inhibited tumor growth (p<0.05), and also HT + DCs potently inhibited tumor growth (p<0.001); however, compared with HT alone, the difference was not statistically significant. In addition, HT + DCs induced strong cytotoxicity of the splenocytes against tumor cells compared to DCs or HT alone. Conclusion: HT + DCs induced apoptosis and increased the expression of HSPs, and so this induced a potent local and systemic antitumor response in tumor-bearing mice. This regimen may be beneficial for the treatment of human cancers.