• Journal of Radiation Protection and Research
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• v.13 no.2
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• pp.1-8
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• 1988

The energy losses of ${\alpha}$-particle with 3 to 5.4 MeV energy were measured as a function of gas absorber thickness and ${\alpha}$-particle energy in three light gaseous media; He, Ar, and $N_2$. The stopping powers and stopping cross-sections were determined by analyzing these data. For Ar gas, the experimental values are very well consistent with the corresponding values of Srivastava's stopping-power theory with the condition of the completely and partially stripped ion. For $N_2$ and He gases, these experimental values express the inconsistencies of about $13{\sim}36%$ and $27{\sim}28%$, respectively.

• Journal of the Korean Ceramic Society
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• v.41 no.4
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• pp.289-296
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• 2004

Whisker and short rod shaped hydroxyapatite (Ca$_{10}$(PO$_4$)$_{6}$(OH)$_2$ with stoichiometric composition (Ca/P=1.62 -1.67, molar ratio) has been synthesized by hydrolysis and hydrothermal reaction of aqueous $\alpha$-Ca$_3$(PO$_4$)$_2$($\alpha$-TCP) solution (pH 11), respectively. The shape of resultant HAp was mainly dependent on synthetic route and the microstructural development was on processing condition. In hydrolysis processing, the degree of intersection of whiskerlike particles and agglomeration in the apsis line increased with increasing reaction time. In hydrothermal synthesis, the reaction product obtained under excessive reaction time ($\geq$3 h at 20$0^{\circ}C$) was severely agglomerated without further grain growth above certain critical size (0.75 ${\mu}{\textrm}{m}$ in length, 0.3${\mu}{\textrm}{m}$ 11m in diameter).

• Journal of the Korean Applied Science and Technology
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• v.30 no.2
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• pp.251-257
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• 2013

The influences of Methotrexate as fluorophor, scatterer, absorber in turbid material by light scattering were interpreted for the scattered fluorescence intensity and wavelength, it has been studied the molecular properties by laser induced fluorescence spectroscopy. It has been found that the effects of optical properties in scattering media by the optical parameters((${\mu}_s$, ${\mu}_a$, ${\mu}_t$). The value of scattering coefficient ${\mu}_s$ is large by means of the increasing particles of L-${\alpha}$-Phosphatidylcholine, it has been found that the slope decays exponentially as a function of depth from laser source to detector. It may also aid in designing the best model for oil chemistry, laser medicine and application of medical engineering.

• Applied Chemistry for Engineering
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• v.25 no.4
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• pp.368-373
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• 2014

Coencapsulation of hydrophilic L-ascorbic acid and hydrophobic ${\alpha}$-tocopherol in ethosome vesicles was attempted and their properties were investigated in this study. The size of vesicles decreased with increasing concentration of L-ascorbic acid solution encapsulated in ethosome. The vesicle size and encapsulation efficiency of ethosomes increased slightly when ${\alpha}$-tocopherol was added into the HPC-forming liquid crystalline membrane of ethosome. However, the vesicle size increased highly and the encapsulation efficiency decreased abruptly at mixing ratios above 25 wt% due to the formation of an imperfect liquid crystalline structure within a vesicle membrane. It was observed that antioxidant activity was maintained for 5 weeks at $40^{\circ}C$ when L-ascorbic acid and ${\alpha}$-tocopherol were coencapsulated in ethosome. The L-ascorbic acid in ethosome was stable compared to that in aqueous solution under UV radiation.

• Electrical & Electronic Materials
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• v.6 no.2
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• pp.161-167
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• 1993

ZnO 바리스터의 비선형 전도특성은 입자의 구조로부터 설명할 수 있다. 본 논문에서는 ZnO 바리스터의 입자구조에 트랩된 캐리어를 분석하기 위해서 TSC 측정 기법을 사용하였다. 측정 결과로 부터 네개의 TSC피크를 얻었다. 고온으로 부터 첫번째 두번째와 세번째 TSC피크의 기원은 각각 트랩, 도너 밀도 및 입계층의 트랩으로 나타나고 네번째 피크의 기원은 공핍층에 있는 도너 이온의 탈분극에 의해서 기인하는 것으로 사료된다. .alpha.$_{1}$피크의 활성화 에너지는 약 0.33-1.42eV였다. 또한 바리스터의 예비동작 영역에서의 전도특성은 .alpha.$_{1}$과 .alpha.$_{2}$피크의 값에 지배된다는 것을 확인하였다.

• Journal of the Korean Vacuum Society
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• v.1 no.1
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• pp.96-99
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• 1992

The microanalysics by the direct observation of 180 (P, a)'" nuclear reactions on tungsten (110) surfaceare investigated using a 2MeV Van de Graaff accelerator. This method allows the determination of very smallquantities of nuclei near the surface of samples. The yields increase with oxygen exposure. The oxygen coverage, 0, is 0.5 at 5 Langmuir and 1.0 at 15 Langmuir.5 Langmuir.

• Journal of the Korean Society of Clothing and Textiles
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• v.17 no.3
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• pp.380-390
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• 1993

Effect of interfacial electrical conditions on adhesion of ${\alpha}-Fe_2O_3$ particles to PET fabric and the removal of ${\alpha}-Fe_2O_3$ particles from PET fabric, were investigated as functions of pH, electrolyte and ionic strength. The ${\zeta}$ potential of PET fiber and ${\alpha}-Fe_2O_3$ particles in the electrolyte solution were measured by streaming potential and microelectrophoresis methods respectively. The potential energy of interaction between ${\alpha}-Fe_2O_3$ particles and PET fabric were calculated by using the heterocoagulation theory for a sphere-plate model. The negative ${\zeta}$ potential of ${\alpha}-Fe_2O_3$ particle and PET fiber increased with pH, and then decreased certain pH and isoelectric points of ${\alpha}-Fe_2O_3$ particles and PET fiber were pH 6.5 and pH 3.5, respectively. The negative ${\zeta}$ potential of ${\alpha}-Fe_2O_3$ particle and PET fiber affected by electrolytes, were relatively high with polyanion electrolytes in solutions and were low with neutral salts. However, at surfactant solution, ${\zeta}$ potential was levelled off. The influence of the ionic strength on the ${\zeta}$ potential of ${\alpha}-Fe_2O_3$ particle was small but the negative ${\zeta}$ potential of PET fiber increased with the ionic strength. In the presence of anionic surfactant, the ${\zeta}$ potential of ${\alpha}-Fe_2O_3$ particle and PET fiber increased regardless of solution conditions. The interaction energy between ${\alpha}-Fe_2O_3$ particle and PET fabric increased with pH. The interaction energy was relatively high with polyanion electrolytes in solution, and the influence of ionic strength on the interaction energy was small, and the effective thickness of electrical double layer increased with decreasing the ionic strength.

• Korean Journal of Ecology and Environment
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• v.41 no.spc
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• pp.21-26
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• 2008

The in situ incubation experiment was carried out using $^{13}C$ tracer to determine primary productivity and fatty acid production rate in the shallow, eutrophic Shingu reservoir on 4th July. Particulate organic matter (POM) accounted for 76% in suspended particulate matter (SPM), and average concentration of chlorophyll-${\alpha}$ was $89{\mu}g\;L^{-1}$ in the euphotic layer. Total amount of chlorophyll-${\alpha}$ (Chl-${alpha}$), primary productivity and Chl-${alpha}$ specific productivity in euphotic layer were 112 mg Chl-${alpha}m^{-2}$, 3.53 g C $m^{-2}\;d^{-1}$, 32mg C mg Chl-${\alpha}^{-1}\;d^{-1}$, respectively. The fatty acid composition in newly produced organic matter and suspended organic matter didn't show any significant difference, demonstrating that autochthonous organic matter should be a major source of POM pool. In addition, the fatty acids of bacterial origin were increased through extracellular release of newly photosynthesized DOC, and closely coupled with bacterial assimilation. This result suggests that organic carbon should be actively cycled through the microbial loop in Shingu reservoir in summer.

• Journal of the Korean Ceramic Society
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• v.41 no.8
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• pp.610-617
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• 2004

For preparation $\alpha$-Al$_2$O$_3$ platelets having 20 $\mu$m in average diameter and 0.2∼0.3 $\mu$m in thickness, we have prepared aluminum hydroxides gel by using aluminum sulfate and sodium sulfate as starting materials. In this study, we investigated the effect of the amount of sodium phosphate on particle size, morphology and thickness of $\alpha$-Al$_2$O$_3$ platelets. When sodium phosphate was not added to aluminum hydroxides gel, most of $\alpha$-Al$_2$O$_3$ platelets had hexagonal shape but the thickness was over 1.0 $\mu$m, and this sample was not adequate for pearlescent pigment. On the other hand, introduction of sodium phosphate caused an increase of aspect ratio (particle diameter/thickness) with a decrease in $\alpha$-Al$_2$O$_3$ platelet thickness.

• Journal of the Korean Society of Clothing and Textiles
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• v.22 no.8
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• pp.1132-1140
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• 1998

The adhesion and removal of $\alpha$-Fe2O3 particles on the from PET fabric in NPE solution with different ionic strength were discussed in terms of interaction of surface charge of particle and substrate. The adhesion of $\alpha$-Fe2O3 particles to PET fabric and its removal from PET fabric were carried out by using water bath shaker and Terg-O-Tometer under various solution conditions. The ζ potential of PET fiber and $\alpha$-Fe2O3 particles in the detergent solution were measured by steaming potential and microelectrophoresis methods, respectively. The adhesion and removal amount of $\alpha$-Fe2O3 particles on the from PET fabric increased with increasing time of adhesion and removal, and the rates of adhesion and removal were high at the initial stage of adhesion and removal, and then the rates decreased with passing time. The adhesion and removal amount of $\alpha$-Fe2O3 particles on and from PET fabric increased with increasing pH of solution regardless ionic strength. The tendencies and degree of adhesion and removal were very similar regardless interaction of surface charge of particle and fiber. Therefore, in the presence of a surfactant and electrolyte, the influence of interaction of surface charge of particle and substrate on the detergency of particulate soil was small.