• 한국지반환경공학회 논문집
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• 제14권9호
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• pp.39-47
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• 2013

Local deformations in back filling materials of two sands and one glass bead with different particle shapes behind a rigid retaining wall were studied. Two kinds of boundary conditions were compared: active wall translation and active rotation of the wall about its toe. Effect of the speed of active wall translation was also investigated. The digital image correlation method was used to analyze local deformation developments inside the materials. Test results showed that particle shape and density mainly influence the inclination angle and width of the shear band. The general shear band pattern is strongly dependent on the wall movement mode, while it was little influenced by particle shape. Within a limited range of wall speed in this study, shear band became wider and local deformation became larger with increase of wall speed.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.721-724
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• 2006

In this study, particle size distribution of cement powder system were adjusted using the blast furnace slag powder, Blaine $2250cm^2/g\;and\;8300cm^2/g$, which easy to adjust particle size distribution to examine how particle size distribution of the binder has an effect on rheological properties of the cement paste. In addition, the relationship between n-value of Rosin-Rammler function and plastic viscosity were discussed. All measured flow curves represented thixotropy behavior and the hysteresis area was smaller for the more added coarse particle. When the combination was based on a ratio of $20{\sim}25vol%$ fine particles, $30{\sim}40vol%$ OPC and $40{\sim}45vol%$ coarse particles of the total volume, a high fluidity and low yield strength was achieved.

• 약학회지
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• 제40권5호
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• pp.522-531
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• 1996

5-fluorouracil(5-FU) derivatives synthesized with four N-acyloxycarbonyl group such as 1-(N-t-butyloxycarbonyl)glycyloxymethyl-5-FU(BGFU), 1-(N-t-butyloxycarbonyl)leucyloxymethy l-5-FU(BLFU), 1-(N-t-carbobenzyloxymethyl)glycyoxymethyl-5-FU(CGFU) and 1-(N-t-carbobenzyloxymethyl)leucyloxymethyl-5-FU(CLFU) were entrapped into liposomes with different lipid compositions. The entrapment efficiency and release rate of drugs from each liposomes were evaluated. The particle size of liposomes, cytotoxicity and stability of drug-entrapped in liposomes were evaluated. The entrapment efficiency in 5-FU derivatives liposomes was dependent on the lipophilicity of N-acyloxymethyl derivatives. The drug entrapment efficiency also increased on the content of lipid increased up to 200mcmol of lipid per milliliter of liposomal solution. However, inclusion of additives such as cholesterol, dicetylphosphate and stearylamine decreased the entrapment efficiency. The mean particle size and size distribution were varied with lipid compositions and lipophilicity of prodrugs. The release rates of drugs from liposomes were not affected by additives, but those of BGFU and CGFU entrapped in liposomes with cholesterol decreased. Cytotoxicity of BLFU and CLFU entrapped in liposomes decreased by 3~5 fold compared with those of free two prodrugs. Liposome-entrapped 5-FU prodrugs were more stable either at pH 7.4 or in human plasma. Especially, 5-FU prodrugs entrapped in liposome with dipalmitoylphosphatidylcholine(DMPC) was the most stable in human plasma. Compared with free BLFU, BLFU entrapped in DMPC liposome showed a superior antitumor activity at all doses used. In contrast, CLFU entapped in liposomes were more toxic than free prodrug.

• 한국입자에어로졸학회지
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• 제9권3호
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• pp.133-137
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• 2013

Measuring particle size distribution is one of the primary concerns in aerosol studies. For a nano-particle size distribution measurement, many scientists use a combination of a differential mobility analyzer (DMA) and a condensation particle counter (CPC) system, which is a called scanning mobility particle sizer (SMPS). Although it has a very high particle size resolution, some issues still remain. These problems include residence time between a DMA and a CPC, discontinuity of a CPC, and disturbance due to long scanning time during the precise measurement of particles. In particular, long scanning time is not adequate for measuring particle size distribution since the particle concentration is changing during the measurement. In this study, we developed radial exhaust multi-port system (REM-system) with no scanning time and high resolution to measure real-time particle size distribution. As a result of the REM-system performed using mono-disperse particle, it is expected that this system will be suitable for measuring continuously changing aerosol. If the counting efficiency of multi-condensation particle counter (M-CPC) and data inversion matrix are completed, REM-system will be a very adequate system for unsteady aerosol, which changes for SMPS scanning time.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.906-909
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• 2006

The secondary electron emission coefficient $({\gamma})$ of the cathode is an important factor for improving the discharge characteristics of AC-PDPs because of its close relationship to discharge voltage. In AC-PDPs, MgO is most widely used as a surface protective layer. In this experimental, we have investigated the electronic structure of the energy band structure of the MgO layer responsible for the high ${\gamma}$. The MgO layers have been deposited by electron beam evaporation method, where the $O_2$ partial pressures have been varied as 0, $5.2{\times}10^{-5}$ torr, $1.0{\times}10^{-4}$ torr, and $4.1{\times}10^{-4}$ torr, in this experiment. It is noted that work function that is energy gap between surface and first defect level of MgO layer has the lowest value for the highest O2 partial pressure of $4.1^{\ast}10^{-4}$ Torr.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.II
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• pp.1207-1210
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• 2005

The MgO protective layer provides protection from the discharge, lowers the discharge voltage and prolongs the AC-PDP lifetime. We have investigated the characteristics of degradation of MgO protective layer, which correlates to the image-sticking[1] and the lifetime in AC-PDP. The degraded MgO have been changed the surface morphology of MgO. It was found that panel lifetime depended on degradation of MgO protective.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.I
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• pp.263-265
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• 2005

In the alternative current plasma display panel(AC-PDP) technology, it is very important to remove the image sticking for improving an image quality. In this paper, we have investigated the driving method of alternative current plasma display panel(AC-PDP) for preventing image sticking. We have investigated the driving method of alternative current plasma display panel(AC-PDP) for preventing image sticking. The preventing method of image sticking was proposed by adopting the Sticking Remove Pulse(SRP). The variation of brightness is most affected by the MgO to be formed at the surface of the phosphor layer. As a result, the image sticking is reduced when the driving method adopted an SRP.

• Asian-Australasian Journal of Animal Sciences
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• 제31권1호
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• pp.80-85
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• 2018

Objective: This study was conducted to investigate the effect of corn grain particle size on ruminant fermentation and blood metabolites in Holstein steers fed total mixed ration (TMR) as a basal diet to explain fundamental data of corn grain for cattle in Korea. Methods: Four ruminally cannulated Holstein steers (body weight $592{\pm}29.9kg$) fed TMR as a basal diet were housed individually in an auto temperature and humidity modulated chamber ($24^{\circ}C$ and 60% for 22 h/d). Treatments in a $4{\times}4$ Latin square design were TMR only (control), TMR with whole corn grain (WC), coarsely ground corn grain (CC), and finely ground corn grain (FC), respectively. The corn feeds substituted for 20% energy intake of TMR intake. To measure the ruminal pH, ammonia N, and volatile fatty acids (VFA), ruminal digesta was sampled through ruminal cannula at 1 h intervals after the morning feeding to determine ruminal fermentation characteristics. Blood was sampled via the jugular vein after the ruminal digesta sampling. Results: There was no difference in dry matter (DM) intake between different corn particle size because the DM intake was restricted to 1.66% of body weight. Different corn particle size did not change mean ammonia N and total VFA concentrations whereas lower (p<0.05) ruminal pH and a ratio of acetate to propionate, and higher (p<0.05) propionate concentration were noted when the steers consumed CC compared with WC and FC. Concentration of blood metabolites were not affected by different particle size of corn grain except for blood triglyceride concentration, which was significantly (p<0.05) increased by FC. Conclusion: Results indicate that feeding CC may increase feed digestion in the rumen, whereas the FC group seemed to obtain inadequate corn retention time for microbial degradation in the rumen.

• 한국결정성장학회지
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• 제12권6호
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• pp.329-334
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• 2002

아나타제형 $TiO_2$, 분말과 $Ca(OH)_2$ 분말을 출발물질로 하여 광화제로 KOH 및 NaOH를 각각 첨가한 후, 오토클레이브 내에서 수열반응시켜 perovskite구조를 갖는 $CaTiO_3$, 분말을 제조하였다. $CaTiO_3$, 분말 합성 시 광화제의 종류 및 농도에 따른 결정상 변화와 입자 형상 및 크기를 고찰한 결과, 광화제로 1 N KOH 용액을 사용한 경우, 약 0.7$\mu$m 크기의 구형입자가 합성되었고, 10 N KOH 용액을 사용한 경우, 3 $\mu$m 정도의 육면체형 입자로 합성되었다. 광화제인 KOH 농도가 증가함에 따라 구형입자로부터 육면체형 입자로 형상이 변화되었으며, 입자의 크기도 증가하였다. 1 N NaOH 용액을 광화제로 사용한 경우에는 0.5~1 $\mu$m 정도의 구형입자가 합성되었고, 10 N NaOH 용액을 사용한 경우에는 1~4 $\mu$m 정도의 육면체 형상을 갖는 입자와 10$\mu$m 이상인 휘스커형 입자가 혼합된 형상으로 합성되었다. KOH 광화제와 마찬가지로 NaOH 광화제의 농도가 증가함에 따라 육면체 및 휘스커 형상을 갖는 입자로 변화하였으며, 입자의 크기도 아울러 증가하였다. 성분 분석 결과 휘스커 형상의 입자의 경우에는 육면체형 입자에서 관찰된 sodium성분이 검출되지 않았다.

• 한국응용과학기술학회지
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• 제21권2호
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• pp.132-139
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• 2004

Film forming behavior of monodispersed model composite latexes with particle size of 190 nm, which consist of n-butyl acrylate as a soft phase monomer and methyl methacrylate as a hard phase monomer with different morphology was examined. Five different types of model latexes were used in this study such as random copolymer particle, soft-core/hard-shell particle, hard-core/soft-shell particle, gradient type particle, and mixed type particle. The film forming behavior was evaluated using pseudo on-line measurements of the cumulative weight loss, the UV transmittance, and the tensile fracture energy. Each stages of film formation I, II were not sensitive to the morphology of model latexes, but stage-ill was largely dependent on the morphology of model latexes. The chain mobility of polymer which composed the shell component was found to dominantly determine the behavior of film forming stage-III.