• Journal of Pharmaceutical Investigation
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• 제36권2호
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• pp.109-114
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• 2006

Biodegradable poly(D,L-lactide-co-glycolide) (PLGA) nanoparticles were developed for sustained delivery of water-soluble macromolecules. PLGA nanoparticles were fabricated by spontaneous emulsification solvent diffusion method generating negatively charged particles and heterogeneous size distribution. As a model drug, blue dextran was encapsulated in PLGA nanoparticles. In addition, nanoparticles were also prepared with varying ratio of poloxamer 188 (P188) and poloxamer 407 (P407), and coating with poly(vinyl alcohol) (PVA). Then, the particle size, zeta potential and encapsulation efficiency of nanoparticles containing blue dextran were studied. In vitro release of blue dextran from nanoparticles was also investigated. The surface and morphology of nanoparticles were characterized by scanning electron microscopy (SEM). In case of nanoparticles prepared with PLGA, P407, and different organic solvents, particle size was in the range of $230{\sim}320\;nm$ and zeta potentials of nanoparticles were negative. The SEM images showed that ethyl acetate is suitable for the formulation of PLGA nanoparticles with good appearance. Moreover, ethyl acetate showed higher encapsulation efficiency than other solvents. The addition of P188 to formulation did not affect the particle size of PLGA nanoparticles but altered the release patterns of blue dextran from nanoparticles. However, PVA, as a coating material, altered the particle size with increasing the PVA concentration. The nanoparticles were physically stable in the change of particle size during long-term storage. From the results, the PLGA nanoparticles prepared with various contents of poloxamers and PVA, could modulate the particles size of nanoparticles, in vitro release pattern, and encapsulation of water-soluble macromolecules.

• 펄프종이기술
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• 제48권3호
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• pp.107-114
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• 2016

Terra Alba Wallpaper was manufactured by coating inorganic terra alba paint on white base paper, and the surface of the coated layers were microscopically observed. Eco Terra Alba used the functional wall paper in this study was prepared by mixing inorganic Terra Alba and calcium carbonate. Terra Alba showed particle shape. The concentration of inorganic components, pH, and the viscosity of the coating solution were 92.0%, 7.82, 1286 cPs, respectively. The bar coater whit No 3 wire resulted in the least thickness of wet coating layer and coating thickness such $22.5{\mu}m$ with covered all the surface. Bar coater with No. 12 wire leaded to $48.4{\mu}m$ thickness. The coating layers above $43{\mu}m$ thickness showed the cracks on the wall paper surface after coating.

• 한국분말재료학회지
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• 제21권1호
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• pp.21-27
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• 2014

In this study, diatomite based materials were investigated as a support filter for silica particle coating. The silica sol for coating was synthesized by a st$\ddot{o}$ber process. The diatomite support was dry-pressed at 10 MPa and sintered at $1200^{\circ}C$ for 1 hour. The coating sol was prepared as a mixture of EtOH and silica sol. The diatomite support was coated by a dip-coating process. Silica coated diatomite filter was sintered at $1000{\sim}1200^{\circ}C$ for 1 hour. The largest pore size was decreased with increasing concentration ratio of coating sol. The gas and water permeability of silica coated diatomite decreased with increasing of concentration ratio of the coating sol.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2010년도 춘계학술발표대회
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• pp.55.2-55.2
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• 2010

기존의 thermal spray coating은 분사시 가스와 입자가 높은 열을 동반하여 상대적으로 차가운 기판과의 충돌되는 과정에서 기판과 입자 사이에 열응력이 발생하게 되고, 이것은 코팅 특성을 저하시킨다. 또한 고온의 가연성 가스등의 사용으로 작업 시 안전문제 등의 단점이 있었다. 이러한 단점을 보완하기 위하여 분사 시 운동에너지를 주로 이용하는 cold spray coating 공정이 개발되었다. 이 공정은 코팅 입자를 임계속도 이상으로 가속시켜 입자와 기판이 충돌시 소성 변형을 통해 적층되는 코팅기술이다. Cold spray coating공정은 상온 코팅이 가능하기 때문에 주입입자의 물성이 비교적 그대로 유지되고, 고온의 열로 인한 기판의 변질을 막을 수 있다. Cold Spray coating에서 주로 원형 노즐을 사용하나 본 연구에서는 분사 효율 향상을 위한 광폭노즐을 사용하여 코팅 시간 단축을 기대하고 있다. 임계속도 이상의 입자 확보를 위하여 노즐의 expansion ratio와 노즐 shape의 변화를 주어 그에 따른 노즐내의 유동장을 수치해석을 통해 계산하였다. 분사되는 출구면과 기판 사이의 입자 속도 분포를 해석하였고, 이를 통해 임계속도 이상의 속도를 갖는 유효 입자들의 분포 및 유효 분사 면적을 예측하였다. 또한, 기존의 원형 노즐과 광폭 노즐과의 유동장 비교 및 각 노즐 분사면을 분석하여 cold spray coating공정에서의 효율적인 노즐 형상을 디자인하였다.

• 한국세라믹학회지
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• 제43권8호
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• pp.492-497
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• 2006

SiC coating has been introduced as protective layer in TRISO nuclear fuel particle of High Temperature Gas cooled Reactor (HTGR) due to excellent mechanical stability at high temperature. In order to inhibit the failure of the TRISO particles, it is important to evaluate the fracture strength of the SiC coating layer. ]n present work, thin silicon carbide coating was fabricated using chemical vapor deposition process with different microstructures and thicknesses. Processing condition and surface status of substrate.affect on the microstructure of SiC coating layer. Sphere indentation method on trilayer configuration was conducted to measure the fracture strength of the SiC film. The fracture strength of SiC film with different microstructure and thickness were characterized by trilayer strength measurement method nanoindentation technique was also used to characterize the elastic modulus and th ε hardness of the SiC film. Relationships between microstructure and mechanical properties of CVD SiC thin film were discussed.

• 한국표면공학회지
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• 제19권3호
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• pp.92-108
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• 1986

An electroplating on the lead frame fabricated from domestic copper plate was studied experimentally. In this study, nickel was plated on the thin copper lead frame and silver layer was coated on the nickel film in the cyanide electrolyte. The effect of process variables such as current density, plating time, coating thickness and flow rate of electrolytic solution on the properties of coating was investigated. Some samples on each step were fabricated during electroplating. The results obtained from polarization measurement, observation of SEM photograph, adhesion test of coating and microhardness test are as follows. On silver plating, polarization resistance of potentiostatic cathodic polarization curve is reduced as the flow rate of Ag electrolytic solution increases. And above resistance is also reduced when the minor chemicals of sodium cyanide and sodium carbonate are added in potassium silver cyanide bath. The reduced polarization resistance makes silver deposition on the cathode easy. An increase in the current density and the coating thickness causes the particle size of deposit to coarsen, and consequently the Knoop microhardness of the coating decreases. On selective plating an increase in the flow rate of plating solution lead to do high speed plating with high current density. In this case, the surface morphology of deposit is of fine microstructure with high Knoop hardness. An increasing trend of the adhesion of coating was shown with increasing the current density and flow rate of electrolytic solution.

• 반도체디스플레이기술학회지
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• 제21권2호
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• pp.38-44
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• 2022

Plasma density in semiconductor fabrication equipment becomes higher to achieve the improved the throughput of the process, but the increase of surface corrosion of the ceramic coated chamber wall has been observed by the increased plasma density. Plasma chamber wall coating with aerosol deposition prefer to be firm and uniform to prevent the potential creation of particle inside the chamber from the deformation of the coating materials, and the aerosol discharge nozzle is a good control factor for the deposited coating condition. In this paper, we investigated the design of the nozzle of the aerosol deposition to form a high-quality coating film. Computational fluid dynamics (CFD) study was employed to minimize boundary layer effect and shock wave. The degree of expansion, and design of simulation approach was applied to found out the relationship between the divergence angle and nozzle length as the key parameter for the nozzle design. We found that the trade-off tendency between divergence angle and nozzle length through simulation and quantitative analysis, and present the direction of nozzle design that can improve the uniformity of chamber wall coating.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2001년도 추계학술발표논문집
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• pp.55-56
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• 2001

지난 수년간 유럽을 중심으로 Carbonate의 PSD (Particle Size Distribution)가 도공지 의 백색도, 불투명도, Coverage등에 미치는 영향에 대하여 많은 연구가 진행되어 왔다. 현재 국내의 Coating Pigment System 역시 Carbonate 위주로 구성되어 있으나, 입자 분포에 따른 실증적 연구가 선진국에 비하여 부족한 상태이다. 본 연구는 최근 유럽에서 사용 중인 Narrow PSD Carbonate가 도공지 품질에 미치는 영향을 검토한 것으로서, 특히 Multiple Coating에서의 도공층 구조변화와 그에 따른 백지물성 및 인쇄적성의 변화를 연구한 것이다. 실험의 Case는 Broad PSD CaC03와 Narrow PSD CaC03를 비 교하였 다 .. Color F Formulation은 Pre Color에서 #1 Clay 30 p따t와 각각 CaC03 70 p따t를 사용하였다. 그리고 바인더와 첨가제는 동일하게 사용하였다 .. Top color Formulation 또한 동일하 게 사용하였다. 코팅방식은 speed 450rrνmin, pre rod coating, top blade coating 방식 으로 CLC (Cy lindrical Laboratory Coater)를 사용하여 코팅하였다. 백지품질은 백색도, 평활도 ,광택도, 거칠음도, Bum Out Test와 Coverage( SEM 사 진 Z -direction) 등을 측정하였다. 인쇄품질은 인쇄 광택도, 인쇄 Picking strength와 2 도 인쇄 농도를 측정하였다. 백색도는 Narrow PSD CaC03를 사용한 것이 Broad PSD CaC03를 사용한 것 대비 약1% 우수하였다. 이것은 Narrow PSD CaC03를 사용한 것이 filter cake이 많이 open 되 어 있어 dewatering이 빠르고, Wet void volume이 증가되 어 부동화점 의 농도가 낮 아져 원지 층으로 침 투되 는 pigment가 작고 표층에 잔류하는 pigment와 void volume의 증가로 인해 기공층이 증가한 것으로 판단된다. 그리고, 백지광택도, 거칠음도 등 또한 Narrow PSD CaC03를 사용한 것이 우수하였 다. 이는 Pre color에서 coverage의 개선으로 top color층의 도공량 uniformity가 개선 된 이유라고 생각한다. 그러나 인쇄품질은 백지와 비교하여 차이가 없었다. 이것은 top 칼라 Formulation이 동일하고, 인쇄시 잉크흡수 거동은 top color 층에 주로 영향을 받기 때문이라고 판단 된다. 향후에는 인쇄품질의 향상을 위하여 Case 2의 CaC03 100% 사용가능성 및 Pre Color 는 Case 2로 고정하고, Top칼라를 변경하는 방법을 또한 생각할 필요가 있다고 판단된다.

• 한국재료학회지
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• 제16권11호
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• pp.692-697
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• 2006

Deodorization of natural zeolites have been improved not only for polar but also for non-polar pollutants by sucessive ion exchanges of H and Ag ions starting from Korean natural zeolite with high adsorption capacity. The modified zeolites with $TiO_2$ coating on the surface revealed high deodorization and photocatalytic decomposition effects. Further modification was made with $10{\sim}20nm$ silica nano particles coating on the surface, the resulting composite particles of $SiO_2/TiO_2/modified$ natural zeolite revealed not only comparable deodorization but also better durability and resisatnce to color change compared to the $TiO_2$/modified natural zeolite without much compensation of photocatalytic decomposition effect, when the composite particles were exposed to the polypropylene non-woven fiber coated with organic binder. It is expected for the composite particle prepared here to be used as indoor building materials for indoor air quality control.

• 한국건축시공학회지
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• 제21권1호
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• pp.51-59
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• 2021

본 연구에서는 아스팔트 매스틱 도막방수재를 구성하는 원료의 종류 및 함량을 조정하여 누유발생 특성을 분석함으로써 원료와 누유발생 간 특정 상관관계를 정량적으로 파악하는 것을 목적으로 하였다. 이를 위해 아스팔트 매스틱 도막방수재의 유·무기계 체질안료인 CA(탄산칼슘)와 ASE(침강방지제) 두 개 원료를 선정하였으며, 입도 및 함량을 변수로 설정하여 배합을 통해 샘플시료를 조성하고 샘플시료별 점도 및 누유안정성(20℃, 40℃) 평가를 진행하였다. 평가결과, 누유안정성 및 점도는 CA 평균입도에 반비례하며, ASE 함량에 비례하는 상관관계가 성립하는 것을 정량적으로 증명하였다. 본 연구결과는 향후 아스팔트 매스틱 도막 방수재의 누유 개선을 위한 배합 연구 시 기초 배합설계의 핵심적인 근거자료로서 활용이 가능할 것으로 판단된다.