• Korea-Australia Rheology Journal
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• v.21 no.1
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• pp.59-69
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• 2009

The prediction of pressure drop for a droplet flow in a confined micro channel is presented using FE-FTM (Finite Element - Front Tracking Method). A single droplet is passing through 5:1:5 contraction - straight narrow channel - expansion flow domain. The pressure drop is investigated especially when the droplet flows in the straight narrow channel. We explore the effects of droplet size, capillary number (Ca), viscosity ratio ($\chi$) between droplet and medium, and fluid elasticity represented by the Oldroyd-B constitutive model on the excess pressure drop (${\Delta}p^+$) against single phase flow. The tightly fitted droplets in the narrow channel are mainly considered in the range of $0.001{\leq}Ca{\leq}1$ and $0.01{\leq}{\chi}{\leq}100$. In Newtonian droplet/Newtonian medium, two characteristic features are observed. First, an approximate relation ${\Delta}p^+{\sim}{\chi}$ observed for ${\chi}{\geq}1$. The excess pressure drop necessary for droplet flow is roughly proportional to $\chi$. Second, ${\Delta}p^+$ seems inversely proportional to Ca, which is represented as ${\Delta}p^+{\sim}Ca^m$ with negative m irrespective of $\chi$. In addition, we observe that the film thickness (${\delta}_f$) between droplet interface and channel wall decreases with decreasing Ca, showing ${\delta}_f{\sim}Ca^n$ Can with positive n independent of $\chi$. Consequently, the excess pressure drop (${\Delta}p^+$) is strongly dependent on the film thickness (${\delta}_f$). The droplets larger than the channel width show enhancement of ${\Delta}p^+$, whereas the smaller droplets show no significant change in ${\Delta}p^+$. Also, the droplet deformation in the narrow channel is affected by the flow history of the contraction flow at the entrance region, but rather surprisingly ${\Delta}p^+$ is not affected by this flow history. Instead, ${\Delta}p^+$ is more dependent on ${\delta}_f$ irrespective of the droplet shape. As for the effect of fluid elasticity, an increase in ${\delta}_f$ induced by the normal stress difference in viscoelastic medium results in a drastic reduction of ${\Delta}p^+$.

• Journal of the Earthquake Engineering Society of Korea
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• v.8 no.5 s.39
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• pp.15-24
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• 2004

The purpose of this study is to investigate the inelastic behavior and ductility capacity of reinforced concrete bridge piers including P-delta effects. A computer program, named RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology), for the analysis of reinforced concrete structures was used. Material nonlinearity is taken into account by comprising tensile, compressive and shear models of cracked concrete and a model of reinforcing steel. The smeared crack approach is incorporated. In addition to the material nonlinear properties, the algorithm for large displacement problem that may give an additional deformation has been formulated using total Lagrangian formulation. The proposed numerical method for the inelastic behavior and ductility capacity of reinforced concrete bridge piers is verified by comparison with reliable experimental results.

• Journal of Ginseng Research
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• v.34 no.3
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• pp.219-226
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• 2010

In the present study, we investigated whether a gross deletion in the nef gene ($g{\Delta}nef$) is induced by Korean red ginseng (KRG) intake. Ten patients were treated with KRG powder for 3 years in the absence of antiretroviral drug therapy. On average, $3,555{\pm}1,042\;g$ KRG was administered per person over $36.1{\pm}2.4$ months. There was a mild decrease in CD4 T cell count ($75{\pm}110/{\mu}L$) over the $36.1{\pm}2.4$ months (p = 0.059). We obtained 355 nef amplicons using 71 peripheral blood mononuclear cell samples over a 3-year period. All ten patients exhibited g${\Delta}$nef (range, 3.2 to 45.9%). At baseline, 3 of 78 amplicons (3.8%) exhibited $g{\Delta}nef$, whereas 18.8% (52/277) revealed $g{\Delta}nef$ during KRG-intake (p<0.001). The proportion of $g{\Delta}nef$ was significantly correlated with monthly dose of KRG (r=0.89, p<0.001). The median time for first detection of $g{\Delta}nef$ was 13 months. In conclusion, our data show that $g{\Delta}nef$ is inducible by KRG intake and its proportion is dependent on the duration of KRG intake and dose of KRG.

• Journal of the Korean Chemical Society
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• v.32 no.5
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• pp.464-475
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• 1988

The complex formation of p-aminoazobenzene and its derivatives with Fe(III) and Mn(II) has been studied by UV and IR spectroscopy and conductometry. The effects of solvents, donor basicity, and other factors on the formation of these complexes have been examined. The vatio of metal to ligand for the complexes formed is 1 : 1, both in the solid state and in solution. The stability constants of Fe(III)-donor and Mn(II)-donor complexes are in the range of 10$^2$∼10$^4$ and 0.1∼1, respectively. The absorptivities are ~10$^4$ and ∼10$^3$ l/mol${\cdot}$cm respectively. Thermodynamic properties such as ${\Delta}H^{\circ}$, ${\Delta}G^{\circ}$ and ${\Delta}S^{\circ}$ are calculated from their stability constants utilizing Van't Hoff equation.

• Bulletin of the Korean Chemical Society
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• v.21 no.12
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• pp.1202-1206
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• 2000

Transmission of substituent effects through 5-membered heteroaromatic rings is investigated theoretically at the RHF/6-31+G and B3LYP/6-31+G levels using the equilibria for the $OH^- addition to five-membered heteroaromatic aldehydes (5MHA). The transmission efficiency (S) in 5MHA(A) increases in the order NH>O>S>PH but the order exactly reverses in 5MHA($T^-$). This is originated by the delocalizability of the ${\pi}$ lonepair on Y, $$n_\pi$(Y)$. A better correlation is obtained with ${\sigma}_p^-$ in the Hammett plots with positive slope, $p_z$ > 0, indicating that the substituent (Z) effects are not transmitted by a direct conjugation. The magnitude of $p_z$ for Y=NH is the largest among the heteroaromatic systems, which is consistent with the largest transmission efficiency change $({\Delta}S)$. The equilibria for the addition processes are favorable in the gas phase $({\Delta}G^o<0)$, which reverses to unfavorable in aqueous solution $({\Delta}G^o>0)$ due to the relatively large salvation energy of $OH^-$ in the initial state in aqueous solution. The orders of ${\Delta}G^o$ and $p_z$ in the gas phase are almost maintained in solution.

• Journal of the korean academy of Pediatric Dentistry
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• v.38 no.3
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• pp.244-249
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• 2011

This in vitro study compared the remineralization of incipient interproximal caries in the presence of three glass ionomer cements(highly-filled glass ionomer cement, resin-modified glass ionomer cement, compomer) and a resin composite(control). Thirty-two extracted premolars were selected based upon the lack of any visible demineralization. The teeth were coated in a transparent acid resistant nail varnish leaving $3{\times}3$ mm square. The teeth were subjected to the demineralizing buffer for 3 days and quantitative light-induced fluorescence(QLF) images of the subjects were taken. Proximal restoration was simulated by placing tooth specimens and the various glass ionomer cements in closed containers with artificial saliva at $37^{\circ}C$ and pH 7.0 with constant circulation. Further QLF images were subsequently taken at 30, 60, and 90 days. The changes of mineral loss(${\Delta}Q$) were evaluated by QLF and the change of ${\Delta}Q$(${\Delta}{\Delta}Q$) were compared between groups in order to evaluate the effects of remineralization. All data were analyzed using ANOVA and the post-HOC Dunnett C multiple comparison test at p<0.05. While ${\Delta}Q$(changes of mineral loss) increased for all treatments, the increases for three glass ionomer groups were significantly higher than that for the resin group at first month period. As time went on, the amount of ${\Delta}{\Delta}Q$ decreased.

• The Korean Journal of Pain
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• v.14 no.2
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• pp.164-170
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• 2001

Background: Infrared Thermal Imaging (ITI) is an effective tool for the diagnosis of disease and evaluation of the therapeutic effects following pain treatment. Patients who were treated for pain in pain clinic described the intensity of pain and the degree of change of their pain using a visual analogue scale (VAS). In this study, the usefulness of ITI following multimodal methods for pain management were compared with the change of VAS. Methods: 1119 patients were evaluated. The patients were treated with stellate ganglion block, epidural block or trigger points injection. Before treatment, the temperature difference (${\Delta}T$) of the involved area and the corresponding area on the opposite side of the body was measured using ITI and VAS was assessed. After treatment, the temperature difference (${\Delta}T$) between the normal and involved areas, the change of ${\Delta}T$ (${\Delta}dT$), VAS and the change of VAS (${\Delta}VAS$) were measured. Statistic correlations between ${\Delta}dT$and ${\Delta}VAS$ were calculated in all groups. Results: Correlation of the ${\Delta}dT$ and ${\Delta}VAS$ was significant by contingency coefficient test. (SGB group, C = 0.358, Epi group, C = 0.377, TPI group, C = 0.374, P < 0.05) Conclusions: ITI is a reliable tool for the assessment of therapeutic effects following multidimensional management of painful disease.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.10
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• pp.1606-1610
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• 2004

This study was. conducted to investigate the effects of $\delta$-aminolevulinic acid supplementation on growth. performance, nutrient digestibility and hematological changes in weaned pigs. Seventy five Duroc${\times}$Yorkshire${\times}$ Landrace pigs (7.21$\pm$0.02 kg average BW) were used in a 20 d growth assay. Dietary treatments included 1) NC (negative control; basal diet), 2) PC (positive control; NC diet + 0.1% Apramycin + 0.1% Oxytetracycline), 3) ALA0.l (NC diet+0.l% $\delta$-aminolevulinic acid), 4) ALA0.2 (NC diet+0.2% $\delta$-aminolevulinic acid) and 5) ALA + AB (PC diet+0.2% $\delta$-aminolevulinic acid). In entire experimental period, ADG (Average Daily Gain) was greater in pigs fed ALA + AB diet than in pigs fed NC diet (p<0.05). However, there was no significant difference in ADG for pigs fed PC, ALA0.l or ALA0.2 diets. Also, ADFI (Average Daily Feed Intake) and G/F (Gain/Feed) were not affected by treatments. For 20 d, fecal digestibilities of DM (Dry Matter) and N (Nitrogen) were higher (p<0.05) for pigs fed ALA + AB diet than for pigs fed NC and ALA0.l diets. Total protein concentration of serum was increased in ALA + AB treatment compared to NC and PC treatments (p<0.05). In iron concentration of serum, pigs fed $\delta$-aminolevulinic acid supplementation diets were greater than for pigs fed NC and PC diets (p<0.05). TIBC (Total Iron Binding Capacity) concentration of serum was increased in ALA + AB treatment compared to NC, PC and ALA0.l treatments (p<0.05). Pigs fed ALA + AB and ALA0.2 diets were higher hemoglobin (Hb) and hematocrit (HCT) concentration of blood than pigs fed NC and PC diets (p<0.05). RBC and WEC concentrations of blood were significantly higher (p<0.05) for the pigs fed ALA0.2 and ALA + AB diets than for pigs fed NC diet. Lymphocyte concentration of blood was increased in $\delta$-aminolevulinic acid supplementation treatment compared to NC treatment (p<0.05). In conclusion, $\delta$-aminolevulinic acid supplementation for weanling pigs had improved growth performance and nutrient digestibilities and had increased total protein, iron, hemoglobin and lymphocyte concentration of blood. Also, feeding for dietary $\delta$-aminolevulinic acid and antibiotic mixture supplementation may have more higher effective growth performance in weanling pigs.

• Molecules and Cells
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• v.37 no.8
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• pp.605-612
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• 2014

The p73 gene contains an extrinsic P1 promoter and an intrinsic P2 promoter, controlling the transcription of the pro-apoptotic TAp73 isoform and the anti-apoptotic ${\Delta}Np73$ isoform, respectively. The DNA methylation status of both promoters act equally in the epigenetic transcriptional regulation of their relevant isoforms. The aim of this study was to analyze the different effects of these p73 isoforms in 5-aza-2'-deoxycytidine (5-aza-dC)-induced apoptosis in breast cancer cells. We investigated the effects of the DNA demethylation agent, 5-aza-dC, on the T-47D breast cancer cell line, and evaluated the methylation status of the p73 promoters and expression of TAp73 and ${\Delta}Np73$. Furthermore, we assessed the expression of p53 and p73 isoforms in 5-aza-dC-treated T-47D cells and p53 knockout cells. 5-aza-dC induced significant anti-tumor effects in T-47D cells, including inhibition of cell viability, G1 phase arrest and apoptosis. This was associated with p73 promoter demethylation and a concomitant increase in TAp73 mRNA and protein expression. In contrast, the methylation status of promoter P2 was not associated with ${\Delta}Np73$ mRNA or protein levels. Furthermore, demethylation of P2 failed to inhibit the expression of ${\Delta}Np73$ with 5-aza-dC in the p53 knockdown cell model. Our study suggests that demethylation of the P1 and P2 promoters has opposite effects on the expression of p73 isoforms, namely up-regulation of TAp73 and down-regulation of ${\Delta}Np73$. We also demonstrate that p53 likely contributes to 5-aza-dC-induced ${\Delta}Np73$ transcriptional inactivation in breast cancer cells.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.3
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• pp.110-118
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• 2000

For reasonable fatigue design and estimation of fatigue durability considered fatigue strength and stiffness of the automotive body structure, many fatigue data must be insured according to the shapes, materials, and welding conditions of the spot welded lap joints. However, because it is actually difficult problem, there is need to establish a new method to be able to predict its fatigue life without any additional fatigue tests. Therefore, In order to improve such problems, in this study, the maximum stress function presenting the $\delta\sigma_{1max}―\delta P$ relation was defined form the relation between $\delta\sigma_{1max}-N_f$ and ${\delta}P-N_f$. By using the fatigue data on the IB type spot-welded lap joints previously obtained from the fatigue test results, fatigue life of the spot-welded lap joint previously obtained from the fatigue test results, fatigue life of the spot-welded lap joint having a certain dimension was tried to predict without any additional fatigue tests. And, its result was verified by ${\delta}P-$N_f$ curves. Obtained conclusion are as follows, 1) a maximum stress function considered the relation of the maximum principal stress, fatigue load, and the effects of geometrical factors of the IB type spot-welded lap joint was suggested. 2) the fatigue life predicted by the maximum principal stress function and the relation of $\delta\sigma_{1max}-N_f$ was well agreed with the fatigue life obtained through the actual fatigue test result. 3) the fatigue life of the IB type spot-welded lap joint having a certain dimension is able to be predicted without any additional fatigue tests from the fatigue life prediction method by the maximum principal stress function.