• Communications of the Korean Mathematical Society
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• v.25 no.3
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• pp.349-364
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• 2010

P. M. Cohn called a ring R reversible if whenever ab = 0, then ba = 0 for a, $b\;{\in}\;R$. Commutative rings and reduced rings are reversible. In this paper, we extend the reversible condition of a ring as follows: Let R be a ring and $\alpha$ an endomorphism of R, we say that R is right (resp., left) $\alpha$-shifting if whenever $a{\alpha}(b)\;=\;0$ (resp., $\alpha{a)b\;=\;0$) for a, $b\;{\in}\;R$, $b{\alpha}{a)\;=\;0$ (resp., $\alpha(b)a\;=\;0$); and the ring R is called $\alpha$-shifting if it is both left and right $\alpha$-shifting. We investigate characterizations of $\alpha$-shifting rings and their related properties, including the trivial extension, Jordan extension and Dorroh extension. In particular, it is shown that for an automorphism $\alpha$ of a ring R, R is right (resp., left) $\alpha$-shifting if and only if Q(R) is right (resp., left) $\bar{\alpha}$-shifting, whenever there exists the classical right quotient ring Q(R) of R.

• Journal of Aquaculture
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• v.7 no.2
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• pp.97-107
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• 1994

Experimental diets containing 5 different levels of a-cellulose $(0\%,\;5\%,\;10\%,\;15\%\;or\;20\%)$ were fed to juvenile Korean rockfish (20.5g of initial mean weight) for 10 weeks to study their ability to utilize dietary $\alpha-cellulose$. Weight gain, feed efficiency, and protein and energy retention efficiency in the fish fed diets containing $0\%,\;5\%,\;or\;10\%$ of $\alpha-cellulose$ were significantly higher than those in the fish fed diets containing $15\%\;or\;20\%$ of $\alpha-cellulose$ (P<0.05). Whole body lipid content of the fish fed $10\%$ $\alpha-cellulose$ diet were significantly higher than that of fish fed other diets (P<0.05). The results suggest that the optimum dietary fiber levels for Korean rockfish would be less than $10\%$.

• Korean Journal of Mathematics
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• v.18 no.2
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• pp.119-132
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• 2010

P. M. Cohn called a ring R reversible if whenever ab = 0, then ba = 0 for $a,b{\in}R$. In this paper, we study an extension of a reversible ring with its endomorphism. An endomorphism ${\alpha}$ of a ring R is called strong right (resp., left) reversible if whenever $a{\alpha}(b)=0$ (resp., ${\alpha}(a)b=0$) for $a,b{\in}R$, ba = 0. A ring R is called strong right (resp., left) ${\alpha}$-reversible if there exists a strong right (resp., left) reversible endomorphism ${\alpha}$ of R, and the ring R is called strong ${\alpha}$-reversible if R is both strong left and right ${\alpha}$-reversible. We investigate characterizations of strong ${\alpha}$-reversible rings and their related properties including extensions. In particular, we show that every semiprime and strong ${\alpha}$-reversible ring is ${\alpha}$-rigid and that for an ${\alpha}$-skew Armendariz ring R, the ring R is reversible and strong ${\alpha}$-reversible if and only if the skew polynomial ring $R[x;{\alpha}]$ of R is reversible.

• Development and Reproduction
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• v.17 no.4
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• pp.421-426
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• 2013

In this study, oocyte steroidogenesis are investigated in relation to oocyte development in the starry flounder, Platichthys stellatus, a marine multiple spawner. Vitellogenic (0.52 and 0.55 mm oocyte diameter) and mature oocytes (0.63, 0.66 and 0.71 mm oocyte diameter) were incubated in vitro in the presence of $[^3H]17{\alpha}$-hydroxyprogesterone ($[^3H]17{\alpha}$-OHP) as a precursor. Steroid metabolites were extracted from the incubated media and oocytes, the extracts were separated and identified by thin-layer chromatography (TLC), high performance liquid chromatography (HPLC) and gas chromatographymass spectrometry (GC-MS). The major metabolites produced from $[^3H]17{\alpha}$-OHP were androgens [androstenedione ($A_4$) and testosterone (T)] and estrogens [$17{\beta}$-estradiol ($E_2$) and estrone ($E_1$)] and progestins [$17{\alpha},20{\alpha}$-dihydroxy-4-pregnen-3-one ($17{\alpha}20{\alpha}P$) and $17{\alpha},20{\beta}$-dihydroxy-4-pregnen-3-one ($17{\alpha}20{\beta}P$)] in vitellogenic and mature oocytes. The results from this study suggest the potential roles of $E_1$ in the oocytes with diameter 0.52-0.71 mm, $17{\alpha}20{\alpha}P$ and $17{\alpha}20{\beta}P$ at the oocytes of 0.63, 0.66 and 0.71 mm.

• Korean Journal of Food Science and Technology
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• v.24 no.4
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• pp.393-395
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• 1992

The ${\alpha}-lactalbumin({\alpha}-la)$ concentration in raw and laboratory-heated milks by HPLC was 1.20 mg/ml (unheated), 1.17 mg/ml ($63^{\circ}C$, 30min), 1.13 mg/ml ($72^{\circ}C$, 15sec) and 0 mg/ml ($100^{\circ}C$, 10min), respectively. Whereas, ${\alpha}-lactalbumin$ concentration ranges of commercial milks were $1.00{\sim}1.02\;mg/ml$ (pasteurized), $0.23{\sim}0.68\;mg/ml$ (UHT-pasteurized) and $0.77{\sim}0.89\;mg/ml$ (UHT-sterilized), respectively. It was supposed that the ${\alpha}-lactalbumin$ content of sterilized milk will be lower than that of UHT milk, but the opposite occurred. This discrepancy would be caused by the different heating system in the milk plants, where indirect UHT-treatment had more heat intensity than direct UHT-processing. The HPLC determination of ${\alpha}-lactalbumin$ may be an indicator to evaluate correctly and rapidly heated milks.

• Journal of the Korean Data and Information Science Society
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• v.6 no.1
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• pp.1-11
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• 1995

The parameters in the multiplicative model $Y_{1}={\alpha}_{0}{\prod}^{p}_{k=1}X_{kj}^{{\beta}_K}v_{j}$ are usually estimated by the least squares method after logarithmic transformation, and the least square Estimator of ${\alpha}_{0}$ is known to be biased, i.e., $E(e xp(\hat{\beta}_{0})){\neq}{\alpha}_{0})$. In the present study the unbaised estimators of ${\alpha}_{0}$ are examined(1) by modifying the least squares estimator and (2) by applying the Finney's results. The variances are also compared. In addition it has been observed that multiplicative model can be used to express the relationship beetween rice yield and yield components.

• Korean Journal of Animal Reproduction
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• v.16 no.2
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• pp.133-139
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• 1992

The study was conducted to find out the changes of progesterone and 20$\alpha$-dihydroprogesterone (20$\alpha$-OHP) levels during the oestrous cycle in Korean native goats. 4 cyclic goats were offered for this experiment. Blood samples were taken from jugular vein on day 0, 1, 3, 5, 7, 9, 11, 13, 15, 17 and 19 during the oestrous cycle, then the next oestrous day. The serum levels of progesterone and 20$\alpha$-OHP were measured by radioimmunoassay. The progesterone concentration in seurm of the cyclic goats was 0.29$\pm$0.06ng/ml on the first day of oestrous (day 0), increased to 5.29$\pm$0.73ng/ml on day 9, reached to a peak level of 5.73$\pm$0.61ng/ml on day 13, and thereafter decreased to 0.35$\pm$0.30ng/ml on day 1. The serum level of 20$\alpha$-OHP during the oestrous cycle was 0.42$\pm$0.33ng/ml on day 0 and then decreased to 0.28$\pm$0.01ng/ml on day 5. This basal level was maintained until day 13, increased gradually, and reached a peak level of 0.62$\pm$0.05ng/ml on day 19. From the above results, it was suggested that the enzyme 20$\alpha$-hydroxysteroid dehydrogenase(20$\alpha$-HSD) catalyzing the conversion of progesterone to a biologically inactive steroid, 20$\alpha$-OHP, should be active in the luteal cells during the oestrous cycle in Korean native goats.

• Korean journal of food and cookery science
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• v.14 no.3
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• pp.261-265
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• 1998

The activity and characteristics of ${\alpha}$-amylase in soy milk as well as in Jeungpyun batters were determined to investigate the enzyme system related to Jeungpyun preparation. ${\alpha}$-Amylase activity was detected in soy milk as well as in Jeungpyun batters. Soy milk had ${\alpha}$-amylase activity of 0.79 units/mg protein for gelatinized starch and 0.036 units/mg protein for raw starch. ${\alpha}$-Amylase in soy milk showed maximum activities at pH 5.92∼6.87 and at 60$^{\circ}C$ for both gelatinized starch and raw starch. ${\alpha}$-Amylase activities of Jeungpyun batters containing soy milk were 25.59 units/mg protein for gelatinized starch and 1.37 units/mg protein for raw starch. Jeungpyun batters without soy milk demonstrated ${\alpha}$-amylase activities of 3.37 units/mg protein for gelatinized starch and 0.49 units/mg protein for raw starch. ${\alpha}$-Amylase of Jeungpyun batters showed an optimal activity at pH 5.25 and at 60$^{\circ}C$ for both gelatinized and raw starch. The results demonstrated that Jeungpyun batters with soy milk showed significantly higher ${\alpha}$-amylase activity than the ones without soy milk.

• Clinical and Experimental Pediatrics
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• v.45 no.2
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• pp.240-246
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• 2002

Purpose : It is not clear that the development of glomerular injury and aggravation by tumor necrosis factor alpha($TNF-{\alpha}$) is related to intrarenal or serum concentration of $TNF-{\alpha}$. So, we studied the relationship between the concentration of $TNF-{\alpha}$ and aggravation of glomerular damage in the Henoch-$Sch{\ddot{o}}nlein$ nephritis(HSN) and idiopathic nephrotic syndrome(INS). Methods : We collected the sera and urines of 21 patients with Henoch-$Sch{\ddot{o}}nlein$ purpura(HSP) and 22 patients with INS visited Chungbuk National University hospital from March 1998 to March 2001. The concentration of $TNF-{\alpha}$ in the sera and urines were measured by sandwich ELISA. Results : Serum $TNF-{\alpha}$ levels in the HSP patients with renal involvement were significantly higher than those without renal involvement(P=0.009). But urine $TNF-{\alpha}$ levels have no correlation with renal involvement(P=0.088). In the HSN patients, proteinuria have a significant correlation with serum $TNF-{\alpha}$ levels(P=0.004) but less correlation with urine $TNF-{\alpha}$ levels(P=0.053). Otherwise, proteinuria have no correlation with serum $TNF-{\alpha}$ levels(P=0.763) but have a significant correlation with urine $TNF-{\alpha}$ levels(P=0.007) in INS. Conclusion : These result suggest that the serum concentration of $TNF-{\alpha}$ would be important to glomerular involvement in HSP. And, it is interesting that proteinuria shows a significant relation with serum $TNF-{\alpha}$ levels in the HSN, but with urine $TNF-{\alpha}$ levels in the INS. This means the major production of $TNF-{\alpha}$ may be originated by extrarenal inflammation in the HSN and by intrarenal tubulo-interstitial damage due to proteinuria in the INS.

• Journal of Veterinary Clinics
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• v.19 no.3
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• pp.342-349
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• 2002

Vitamin D is one of important factors involved in the regulation of bone metabolism. In osteoporosis, the therapeutic effect of vitamin D on the healing process has still been controversial. To conform the effect of $1{\alpha}$, 25 dihydroxy-vitamin $D_3$ on osteoporosis, the change of serum calcium, serum phosphorus, serum alkaline phosphatase, bone mineral density and bone mineral content of osteoporotic tibia were examined comparatively in normal control group(positive control), CFA control(negative control), CFA+$1{\alpha}$, 25 dihydroxy-vitamin $D_3$ 0.01 ug/kg group and CFA+$1{\alpha}$, 25 dihydroxy-vitamin $D_3$ 0.1 ug/kg group after osteoporosis was induced by single injection of complete Freund's adjuvant(CFA) in rats. In change of serum calcium. the significantly increased value was shown on 2nd and 5th week(P< 0.05) after treatment in $1{\alpha}$, 25 dihydroxy-vitamin D$_3$ 0.01 ug/kg group and on 3rd week(P<0.05) after treatment in $1{\alpha}$, 25 dihydroxy-vitamin $D_3$ 0.1 ug/kg group than CFA control. In change of serum phosphorus, the significantly increased value was shown on 2nd week(P<0.05) after treatment in $1{\alpha}$, 25 dihydroxy-vitamin $D_3$ 0.01 ug/kg group and on 3rd and 4th week(P<0.05) after treatment in $1{\alpha}$, ,25 dihydroxy-vitamin $D_3$ 0.1 ug/kg group than CFA control. The value of bone mineral density and bone mineral content of tibia was increased in both $1{\alpha}$,25 dihydroxy-vitamin $D_3$ 0.01 ug/kg group and $1{\alpha}$, 25 dihydroxy-vitamin $D_3$ 0.1 ug/kg group than CFA control, and the increase rate of that was higher in $1{\alpha}$, 25 dihydroxy-vitamin $D_3$ 0.1 ug/kg group than $1{\alpha}$, 25 dihydroxy-vitamin $D_3$ 0.01 ug/kg group. Considering above findings collectively, it was considered that $1{\alpha}$, 25 dihydroxy-vitamin $D_3$ was effective in preventing the complete Freund's adjuvant-induced osteoporotic decrease of bone mass.