• Progress in Superconductivity and Cryogenics
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• v.24 no.1
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• pp.18-22
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• 2022

The effect of electron beam (EB) irradiation on superconducting properties and microstructures of MgB₂ bulk superconductors were investigated. At E-beam doses of 1×10¹⁶ e/cm² and 1×10¹⁷ e/cm², the effect of irradiation on a superconducting transition temperature (T_c) of MgB₂ was weak. As a dose increases to 5×10¹⁷ e/cm², T_c decreases by 0.5 K. The critical current density (J_c) measured at 4.2 K and 20 K, and 0 T - 5 T increases slightly as exposure time increases. X-ray diffraction for the irradiation surface of MgB₂ shows that the diffraction intensity of (hkl) peaks decreases proportionally as the exposure time increases. This indicates that the crystallinity of MgB₂ was degraded by irradiation. TEM investigation for the irradiated sample showed distorted lattice structure, which is consistent with the XRD results. The J_c increase and T_c reduction of MgB₂ by irradiation are believed to be caused by the lattice distortion.

• Asian-Australasian Journal of Animal Sciences
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• v.20 no.4
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• pp.598-604
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• 2007

The current study was conducted to evaluate carcass characteristics, objectives and sensory meat qualities of Hanwoo longissimus muscle as affected by ultimate pH. Twenty-four steers and bulls ($556{\pm}53$ kg and $0.63{\pm}0.32$cm for live weight and backfat thickness, respectively) were used. As there was a linear relationship (r = 0.77) between lean meat color and ultimate pH, cattles were thus segregated into normal $pH{\leq}5.8$, Normal, n = 13) and DFD (pH>5.8, n = 11) groups. Normal pH group had significantly (p<0.05) higher carcass weight, marbling score and backfat thickness than those for high pH group, while fat color and lean meat color were inverse. In principle component analysis for co-ordinates of DFD and normal meats, fat color, lean meat color, texture, time to pH 6.2 and pH at 24 h postmortem were associated with the positive range of the first factor (67.5%) while backfat thickness marbling score and temperature at 24 h were placed in negative values. The rate constant of decline in pH (pH k) did not differ between the two groups, implying that initial pH (i.e., pH at slaughtering) differed between two groups. Contour mapping of pH k between pH at 1 and 24 h postmortem indicated that high pH k was related to lower pHs at 1 and 24 h postmortem. This suggested that the high pH cattles (i.e., DFD cattle) resulted from their own potential. Although the time to reach pH 6.2 was significantly (p<0.05) shorter for normal meat (i.e., 3.2 h) than that for DFD one (i.e., 19.8 h), there were no significantly differences in both WB-shear force and sensory attributes. Given that the experimental animals were sampled from a similar group, which implies a similar myoglobin pigment content, the current data suggested that pre- and post-slaughter animal handling likely had a significant effect on ultimate pH and consequently meat color of Hanwoo longissimus muscle, and also small animals with lower marbling score and backfat thickness had a higher risk for DFD meat.

• The Korean Journal of Physiology and Pharmacology
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• v.10 no.1
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• pp.19-24
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• 2006

The intermediate conductance $Ca^{2+}-activated$ $K^+$ channels (SK4, IKCa1) are present in lymphocytes, and their membrane expression is upregulated by various immunological stimuli. In this study, the activity of SK4 was compared between Bal-17 and WEHI-231 cell lines which represent mature and immature stages of murine B lymphocytes, respectively. The whole-cell patch clamp with high-$Ca^{2+}$ ($0.8{\mu}M$) KCl pipette solution revealed a voltage-independent $K^+$ current that was blocked by clotrimazole (1 mM), an SK4 blocker. The expression of mRNAs for SK4 was confirmed in both Bal-17 and WEHI-231 cells. The density of clotrimazole-sensitive SK4 current was significantly larger in Bal-17 than WEHI-231 cells ($-11.4{\pm}3.1$ Vs. $-5.7{\pm}1.15$ pA/pF). Also, the chronic stimulation of B cell receptors (BCR) by BCR-ligation (anti-IgM Ab, $3{\mu}g$/ml, 8∼12 h) significantly upregulated the amplitude of clotrimazolesensitive current from $-11.4{\pm}3.1$ to $-53.1{\pm}8.6$ pA/pF in Bal-17 cells. In WEHI-231 cells, the effect of BCR-ligation was significantly small ($-5.7{\pm}1.15$ to $-9.0{\pm}1.00$ pA/pF). The differential expression and regulation by BCR-ligation might reflect functional changes in the maturation of B lymphocytes.

• Korean Journal of Materials Research
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• v.30 no.10
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• pp.502-508
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• 2020

This paper focuses on the electrical properties and stability against DC accelerated aging stress of ZnO-V₂O₅-MnO₂-Nb₂O₅-Bi₂O₃-Co₃O₄-Dy₂O₃ (ZVMNBCD) varistor ceramics sintered at 850 - 925 ℃. With the increase of sintering temperature, the average grain size increases from 4.4 to 11.8 mm, and the density of the sintered pellets decreases from 5.53 to 5.40 g/㎤ due to the volatility of V₂O₅, which has a low melting point. The breakdown field abruptly decreases from 8016 to 1,715 V/cm with the increase of the sintering temperature. The maximum non-ohmic coefficient (59) is obtained when the sample is sintered at 875 ℃. The samples sintered at below 900 ℃ exhibit a relatively low leakage current, less than 60 mA/㎠. The apparent dielectric constant increases due to the increase of the average grain size with the increase of the sintering temperature. The change tendency of dissipation factor at 1 kHz according to the sintering temperature coincides with the tendency of the leakage current. In terms of stability, the samples sintered at 900 ℃ exhibit both high non-ohmic coefficient (45) and excellent stability, 0.8% in 𝚫E_B/E_B and -0.7 % in 𝚫α/α after application of DC accelerated aging stress (0.85 E_B/85 ℃/24 h).

• Asian-Australasian Journal of Animal Sciences
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• v.24 no.5
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• pp.655-661
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• 2011

Two experiments were conducted to investigate the effect of dietary supplementation of Bacillus, Saccharomyces and lactic acid bacteria (LAB) on performance and nutrient digestibility in grower and finisher pigs. In Exp. 1, 80 pigs (32 females and 48 males), $28.7{\pm}0.9\;kg$ body weight (BW), were randomly divided into 4 treatment groups balanced for sex and weight (5 pigs per pen, 4 pens per treatment). They were fed one of four diets: a basal grower (20-50 kg BW) and finisher (>50 kg BW) diet without any addition of probiotic or antibiotic (diet C), the basal diet supplemented with Bacillus subtilis H4 (diet B), diet B supplemented with Saccharomyces boulardi Sb (diet BS) and diet BS supplemented with a LAB complex (diet BSL). The LAB complex consisted of Enterococcus faecium 6H2, Lactobacillus acidophilus C3, Pediococcus pentosaceus D7, and Lactobacillus fermentum NC1. In Exp. 2, 16 male pigs, $29.2{\pm}0.8\;kg$ BW, were kept in individual pens and divided into 4 groups (4 pigs in each group). All 4 groups were given exactly the same growing-period diets (diet C, B, BS and BSL) as in Exp 1. The total faeces and urine were collected during 5 days (day 20-24) to determine nitrogen retention and total tract digestibility. In the growing period, average daily feed intake (ADFI), average daily gain (ADG) and feed conversion ratio (FCR) were not affected by diet B and BS (p>0.05), but ADG increased (+5.9%) (p<0.05) and FCR improved (+5.9%) (p<0.05) on diet BSL compared with the control, although ADFI was not different (p>0.05). Digestibility of crude protein and organic matter was higher (p<0.05) in diet BSL and digestibility of crude fibre was higher (p<0.05) in diet BS and BSL than in diet C. Nitrogen retention was not affected by diet (p>0.05). The faecal LAB counts were increased in grower pigs fed diet BSL (p<0.05) and faecal E. coli counts were decreased in pigs fed diets BS and BSL (p<0.05). In the finishing period, no effects of diet were found in ADFI, ADG, FCR, nutrient digestibility, and nitrogen retention (p>0.05). Faecal LAB and E. coli counts in the finisher pigs were not affected by diet (p>0.05). In conclusion, the current study demonstrates that a mixture of bacteria and yeast has the potential to be used as a probiotic dietary supplement in grower pigs.

• Current Photovoltaic Research
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• v.7 no.4
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• pp.103-110
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• 2019

Cu(In,Ga)₃Se₅ (β-CIGS) has a band gap of 1.35 eV, which is an optimum value for high solar-energy conversion efficiency. The effects of Cu and Ga content on the cell performance were investigated previously. However, the effect of Se content on the cell performance is not well understood yet. In this work, β-CIGS films were fabricated by three-stage co-evaporation of elemental sources with various Se fluxes at the third stage instead of at all stages. The average composition of five samples was Cu_1.05(In_0.59,Ga_0.41)3Se_y, where the stoichiometric y value is 5.03 and the stoichiometric Se/metal (Se/M) ratio is 1.24. We varied the Se/metal ratio in a range from 1.18 to 1.28. We found that the best efficiency was achieved when the Se/M ratio was 1.24, which is exactly the stoichiometric value where the CIGS grains on the CIGS surface were tightly connected and faceted. With the optimum Se/M ratio, we were able to enhance the cell efficiency of a β-CIGS solar cell from 9.6% to 12.0% by employing a Na₂S post deposition treatment. Our results indicate that Na₂S post deposition treatment is very effective to enhance the cell efficiency to a level on par with that in α-CIGS cell.

• Journal of Animal Science and Technology
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• v.46 no.1
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• pp.97-106
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• 2004

The study was conducted to investigate the effects of practical variations in feed restriction, pre-slaughter handing and chilling regime on pork quality during ageing. A total of twenty male landraces were allocated into three treatments(i.e., pre-slaughter feeding, stress and chilling regime) in a factorial arrangement. pH, temperature, free calcium ions, WB-shear force, sarcomere length, cooking loss, drip loss and objective color were determined during rigor development and/or 1, 3, 7 d postmortem. Pre-slaughter chasing stress for approximately 15 min had no effects on pH/temperature profile and objective meat quality. There was an interaction(P < 0.05) between the fasting treatment and chi1ling regime for muscle temperature at pH 6.2. Sarcomere length indicated that the current experiment conditions did not induce muscle shortening, with 1.7 to 1.8 ${\mu}m$, in spite of a significant effect of the fasting treatment (P<0.01). Pigs fed until the morning of slaughter showed a low WB-shear force(P < 0.05) until 3 d at I "C. The treatment also resulted in a higher Hunter L* and a*(P < 0.05) at 24 h and 7 d. Fasted pigs showed a significantly(P < 0.05) reduced cooking loss. The current results indicated that feeding upon the morning of slaughter became detrimental on meat color and the negative effect on cooking loss were linearly elevated with increased ageing time. On the other hand, WB-shear force did not distinguishable after 3 d. Collectively, it appeared that feed restriction from a day before slaughter could produce more a desirable meat quality at the time of consuming. However, the limited effect of animal handling and chilling rate on meat quality is not necessarily to extend to that these do not affect pork quality, as that largely depends on experimental design.

• The Korean Journal of Physiology and Pharmacology
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• v.14 no.3
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• pp.119-125
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• 2010

We investigated the effects of a hot-water extract of Artemisia iwayomogi, a plant belonging to family Compositae, on cardiac ventricular delayed rectifier $K^+$ current ($I_K$) using the patch clamp technique. The carbohydrate fraction AIP1 dose-dependently increased the heart rate with an apparent $EC_{50}$ value of $56.1{\pm}5.5\;{\mu}g/ml$. Application of AIP1 reduced the action potential duration (APD) in concentration-dependent fashion by activating $I_K$ without significantly altering the resting membrane potential ($IC_{50}$ value of $APD_{50}$: $54.80{\pm}2.24$, $IC_{50}$ value of $APD_{90}$: $57.45{\pm}3.47\;{\mu}g/ml$). Based on the results, all experiments were performed with $50\;{\mu}g/ml$ of AIP1. Pre-treatment with the rapidly activating delayed rectifier $K^+$ current ($I_{Kr}$) inhibitor, E-4031 prolonged APD. However, additional application of AIP1 did not reduce APD. The inhibition of slowly activating delayed rectifier $K^+$ current ($I_{Ks}$) by chromanol 293B did not change the effect of AIP1. AIP1 did not significantly affect coronary arterial tone or ion channels, even at the highest concentration of AIP1. In summary, AIP1 reduces APD by activating $I_{Kr}$ but not $I_{Ks}$. These results suggest that the natural product AIP1 may provide an adjunctive therapy of long QT syndrome.

• The Korean Journal of Ecology
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• v.24 no.5
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• pp.297-301
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• 2001

The objectives of this study were to evaluate the extent of heavy metals(As, Pb, Cd, Hg)accumulated in sediments of the Kwangyang Bay, and to investigate bioaccumulation of heavy metals(As, Pb, Cd, Hg) in shellfish(Ruditapes philippinarum) commonly found in the intertidal zone of the Kwangyang Bay. The data was also compared with that of Namhae and Kohung intertidal zones, which were regarded as control stations in this study. Substantial geographical variations in heavy metal concentrations in the sediment samples were found. However, heavy metal concentrations in the sediment collected from the intertidal zones of Yochon(stations I, J) and Myodo(stations G, H) close to Yochon Industrial Area exhibited relatively higher heavy metal concentrations, compared to those from other intertidal zones(stations A, B, C) adjacent to POSCO at Kwangyang Bay. In addition, stations A, B, C showed lower heavy metal concentrations in the sediments than controls(K, L). The annual mean concentrations of the heavy metals in the shellfish from the stations(G, H, I, J) were significantly higher than those from other stations(A, B, C, D, E, F). Nevertheless, heavy metal accumulation in sediments was not reflected in bioaccumulation of heavy metals in shellfish, probably indicating that interactions between the heavy metals in sediment and shellfish might be poor in the current study area, Kwangyang Bay.

• The Korean Journal of Emergency Medical Services
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• v.8 no.1
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• pp.71-86
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• 2004

This study selected emergency medical technicians at 24 fire police boxes in Jeonnam in order to examine the relationship between job stress, fatigue and job satisfaction of 119 emergency medical technicians. Data were collected from Apr. 10 to May 9, 2004, questionnaires were mailed and returned by mail. Total 109 questionnaires were distributed and 89 questionnaires were collected and 80 except 9 omitting answers and showing inappropriate answers were used for final analysis. The results of this study are as follows. A. The total mean of areas composing job stress in the degree of job stress of 119 emergency medical technicians was over the average as 2.54 (SD .44) of 4 full marks. According to the degree of job stress by each area, the highest area of job stress was crisis situation (2.98), followed by role conflict as professional job (2.58), social factors (2.57), involvement in organization (2.55). To the contrary, the areas of the lowest job stress were professional knowledge and technique (2.35), psychological burden of medical limitation (2.38), conflicts in personal relationship and services (2.45) and improper treatment (2.53). B. The degree of fatigue of 119 emergency medical technicians by areas was over mean as 2.09(SD .49) of 4 full scores and physical fatigue was highest (2.18), followed by mental fatigue (2.11) and neurosensory fatigue (1.99). C. The degree of job satisfaction of 119 emergency medical technicians was 2.71 of 5 full scores and working condition area (3.70) showed the highest job satisfaction, followed by requirement of organization (2.85) and the lowest job satisfaction area was job itself (2.18), followed by desire for job (2.49). D. According to differences in demographical characteristics of 119 emergency medical technicians, there was no variable of statistical difference at job stress and job satisfaction in significance level .05, but fatigue showed statistical difference at final education (F=2.393, p=.046). E. According to differences related to job characteristics of 119 emergency medical technicians, job stress showed statistical differences at motif of current services (F=4.935, p=.003), fatigue showed those at health conditions (F=2.732, p=.008), job satisfaction at overtime (F=3.038, p.034) and the greatest reason of having job (F=3.217, p=.017), F. As a result of analyzing correlations between job stress. fatigue and job satisfaction of the subject, job stress showed positive correlations (r=.411, p=.000) with fatigue and negative correlation (r=-.267, p=.008) with job satisfaction. Fatigue showed negative correlation (r=-.287, p=.005) with job satisfaction. Therefore, the hypothesis of this study. "There will be relationship between degree of stress, fatigue and job satisfaction of subjects." was supported.