• 한국세라믹학회지
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• 제32권8호
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• pp.901-908
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• 1995

In aqueous slurry processing of silicon nitride, the interaction of dispersant and binder used as polymeric processing additives on the silicon nitride particle surface was studied to identify the effect of these processing polymeric additives on the ceramic powder processing. The adsoprtion isotherm study of anionic organic molecule as dispersant and nonionic organic molecules as binder of silicon nitricde was studied to investigate the effect of these processing organic additives on the physicochemical properties of silicon nitride particles. As anionic molecule adsorbed onto silicon nitrice surface, the IEP of silicon nitride shifted toward acidic pH and changed the stability of silicon nitride particle. However, the adsorption of binder as nonionic organic molecule onto silicon nitride surface did not changed the IEP but caused the decrease of electrostatic potentials of silicon nitride. These distinctive adsorption behaviors of organic additives on silicon nitride particles can be closely correlated to the stability of silicon nitride particles suspended in aqueous media.

• Journal of Pharmaceutical Investigation
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• 제31권1호
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• pp.43-47
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• 2001

Sterically stabilized liposomes (SSL) have been introduced for longer circulation in blood than conventional liposomes (CL). However, there are a couple of problems in SSL preparation due to the instability of phospholipid and the degradation of drug in aqueous conditions. To solve these problems, it is necessary to go through lyophilization process. Therefore, in this study, effects of lyophilization on SSL were evaluated for physical characteristics changes upon rehydration of lyophilized SSL such as the particle size, efficiency of drug entrapment, turbidity and drug release. SSL containing streptozocin, a water-soluble anticancer drug as a model compound, were prepared with DSPC and DSPE-PEG 2000. The size was controlled to 100 nm by extrusion with polycarbonate membrane, and sucrose was used as a cryoprotectant for lyophilization at the 1:3 (lipid:sucrose) ratio. Upon rehydration of lyophilized SSL, the average size was in the range of $50{\sim}200\;nm$ which is adequate for longer circulation in blood, and the encapsulation efficiency was kept as its initial state. Rehydrated SSL were not adsorbed to rat plasma protein and revealed a similar drug release profile to that of fresh SSL before lyophilization. Therefore, lyophilization could be introduced efficiently to overcome aqueous instability problems of SSL.

• 한국재료학회지
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• 제16권7호
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• pp.422-429
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• 2006

Studies were performed on preparation of organic-inorganic hybrid silica dye in a dispersing ink system. The silica was subjected to surface modification using 3-aminopropyltrimethoxysilane (APTMS) in order to promote the chemical reactivity of the raw silica. On the surfaces of the aminosilane-functionalised silica, red vinylsulfone-containing azo dye was adsorbed. The dye was found to have chemically reacted with the aminosilane-grafted silica surface, which was proven by FT-IR spectra. Studies on morphology and microstructure were performed employing scanning electron microscopy. The SEM micrographs and particle size distributions showed that a homogeneous pigment can be obtained employing silica as a core. Particle size distribution was also examined using the technique of dynamic light scattering. The ensuing pigment was subjected to various physicochemical evaluation such as inkjet property, storage stability, color change as inkjet ink using printer, spectrophotometric, microscopic techniques. Studies on hybrid dyes from the silica surface demonstrated that, in general, stable pigments for inkjet dispersion ink were obtained.

• Nuclear Engineering and Technology
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• 제54권5호
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• pp.1597-1605
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• 2022

A porous silica-based adsorbent was prepared by impregnating the pores of a silica support with the extractant 1,3-[(2,4-diethylheptylethoxy)oxy]-2,4-crown-6-calix[4]arene (Calix[4]arene-R14) and an additive agent 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (C₂mim ⁺ NTf^-₂) as the materials to remove cesium(I) (Cs⁺) ions from seawater. The as-prepared adsorbent showed excellent adsorption performance toward Cs⁺ ions, with adsorption equilibrium reached within 2 h and an adsorption amount of 0.196 mmol/g observed. The solution pH, temperature, and the presence of coexisting metal ions were found to have almost no effect on Cs⁺ adsorption. The adsorption mechanism was considered to proceed via ion exchange between Cs⁺ and C₂mim⁺. In addition, the particle-induced X-ray emission analysis results further clarified that the adsorbed Cs⁺ ion species on the adsorbent was in the form of both CsCl and CsBr.

• 한국결정성장학회지
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• 제33권1호
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• pp.37-44
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• 2023

Transition metal (Me = Cu, Fe, Ni) doped (Pr, Ba)Co₂O_5+𝛿 (PBCO) material were investigated in terms of electronic structure change and electrochemical properties. It was confirmed that (Pr, Ba)(Co, Cu)O_5+𝛿 (PBCCu) and (Pr, Ba)(Co, Fe)O_5+𝛿 (PBCFe) showed cubic and orthorhombic structures, respectively, but (Pr, Ba)(Co, Ni)O_5+𝛿 (PBCNi) showed secondary phases. PBCCu has an average particle diameter of 1093 nm, and PBCO and PBCFe have an average particle diameter of 495.1 nm and 728 nm, respectively. The average oxidation values of B site ions in PBCMe were calculated to be 3.26 (PBCO), 2.48 (PBCCu), 3.32 (PBCFe), and valence band maximum (VBM) was -0.42 eV (PBCO), -0.58 eV (PBCCu), -0.11 eV (PBCFe). It is expected that PBCCu easily interacts with adsorbed oxygen due to the lowest oxidation value and the highest VBM. The polarization resistance was 0.91 Ω cm² (PBCO), 0.77 Ω cm² (PBCCu), 1.06 Ω cm² (PBCFe) at 600℃, showing the lowest polarization resistance of PBCCu.

• 실천공학교육논문지
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• 제15권1호
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• pp.209-221
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• 2023

반도체 제조 공정에서 사용되는 제품의 외관 검사 및 포장 단계에서 정전기에 의해 particle이 제품 자체나 운반용 도구 등에 흡착되는 문제가 발생한다. 본 연구는 실용 트리즈 기법을 활용하여 제품에 particle이 흡착되는 문제를 개선할 수 있는 방법론을 제시한다. 제시한 실용 트리즈 기반의 방법론을 적용하여 문제를 정의하고, 제품 대기 시간으로 인해 발생하는 모순을 도출하였다. 도출된 모순 중 물리적 모순을 설정하고 '공간분리'의 개념을 적용하여 '이오나이저 설치' 및 '작업실 Layout 개선'이라는 해결방안을 도출하였다. 실용 트리즈 적용을 통해 도출한 '이오나이저 설치' 및 '작업실 Layout 개선'을 적용하여 실험한 결과, 제품이 대기하는 시간에서 발생되는 particle 흡착 문제를 해결할 수 있음을 확인하였다. 본 연구를 통해, 제조현장에서 근무하는 작업자, 설비 엔지니어, 기술 엔지니어들이 실용 트리즈 기법을 활용하여 창의적 사고, 발상의 전환을 통해 직면한 문제를 효과적으로 해결하고 혁신적인 기술개발 및 생산성 향상에 기여할 수 있을 것이다.

• Bulletin of the Korean Chemical Society
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• 제33권9호
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• pp.2855-2860
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• 2012

The coating N-acetyl cysteine (NAC) on gold surfaces may be used to design the distribution of either gold particle adsorbed to the $ZrO_2$ surface or vice versa by adjusting the electrostatic interactions. In this study, it was performed to find out electrostatic properties of the NAC-coated-gold surface and the $ZrO_2$ surface. The surface forces between the surfaces were measured as a function of the salt concentration and pH value using the AFM. By applying the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory to the surface forces, the surface potential and charge density of the surfaces were quantitatively acquired for each salt concentration and each pH value. The dependence of the potential and charge density on the concentration was explained with the law of mass action, and the pH dependence was with the ionizable groups on the surface.

• 전기화학회지
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• 제13권1호
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• pp.10-18
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• 2010

Nanostructured metal oxides have been widely used in the research fields of photoelectrochemistry, photochemistry and opto-electronics. Dye-sensitized solar cell is a typical example because it is based on nanostructured $TiO_2$. Since the discovery of dye-sensitized solar cell in 1991, it has been considered as a promising photovoltaic solar cell because of low-cost, colorful and semitransparent characteristics. Unlike p-n junction type solar cell, dye-sensitized solar cell is photoelectrochemical type and is usually composed of the dye-adsorbed nanocrystalline metal oxide, the iodide/tri-iodide redox electrolyte and the Pt and/or carbon counter electrode. Among the studied issues to improve efficiency of dye-sensitized solar cell, nanoengineering technologies of metal oxide particle and film have been reviewed in terms of improving optical property, electron transport and electron life time.

• 대한의용생체공학회:의공학회지
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• 제15권1호
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• pp.51-56
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• 1994

Protein adsorption on the polyurethane surface was modelled by a modified random sequential adsorption(RSA) process. In this model, polyurethane surface was modelled as a mixed domain of hydrophobic and hydrophilic parts which was implemented by a 2 dimensional $150{\times}150$ lattice in the computer. Protein adsorption was simulated using a small box which represents a particle of the protein, and polyurethane lattice by considering their hydrophobic interaction. In order to validate the model, we perfonned fibrinogen adsorption on polyurethane surface. Isotherms of the adsorbed protein were calculated and compared to the experimental data. The protein adsorption on the polyurethane surface could be well described using this computer model.

• 대한화학회지
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• 제6권2호
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• pp.104-107
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• 1962

It is thought that the adsorption isotherms in dyeing of cellulose by the direct cotton dyes are consisted of combined type of Langmuir and Freundlich as the opinion of Fujino, et al;$[D]_F=ab[D]_S/(1+b[D]_S)+k[D]_S$where a,b,k; constants, $[D]_F$; dye adsorption on the fiber, $[D]_S$; dye concentration in the bath. This means that the dyes adsorbed in cellulose present in the state of partly mono molecular and partly aggregate; the characteristic fading order curve will be expressed as the combined system of uniform particle size distribution and assumed that the slope of the theoretical models of Baxter, et al., and assumed that the slope of curve will be changed near the point of a, the saturation value of Langmuir isotherms in the above equation. Firstly, the theoretical fading rate curve was treated with small colour difference as the one step of experimental of above consideration.