• 한국표면공학회지
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• 제43권6호
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• pp.260-265
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• 2010

STD 61 steel has been widely used for tools, metallic mold and die for press working because of its favorable mechanical properties such as high toughness, and creep strength as well as excellent oxidation resistance. The STD 61 tool steel coated with TiN and ZrN by sputtering results in improvement of wear and corrosion resistance. In this study, surface characteristics of TiN and ZrN film coated STD 61 by sputtering were studied by using FE-SEM, EDS, XRD, and XRR and nanoindentation tests. From the results of surface characteristics of coated specimen, the ZrN coated surface showed finer granular than that of TiN coated surface. The coated layer structures of ZrN and TiN were grown to (111) and (200) preferred orientation. From the results of XRR test for surface roughness, density and growth rate of coating film, surface roughness and growth rate of ZrN coated film revealed lower values those of TiN coated film, whereas density of ZrN coated film showed higher values than that of TiN coated film. From the nanohardness and elastic modulus test, nanohardness value and elastic modulus of ZrN coated film became higher than those of TiN coated film.

• Bulletin of the Korean Chemical Society
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• 제30권10호
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• pp.2351-2354
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• 2009

A series of N-arylsuccinanilic acids, N-arylsuccinimides, N-arylmaleanilic acids, and N-arylmaleimides was prepared and their NMR spectra were examined by correlating the $^1H\;and\;^{13}C$ chemical shift values with the corresponding Hammett $\sigma$ values. The carbonyl carbons of the amides show a normal correlation with $\sigma$ but those of the imides show an inverse correlation.

• 공업화학
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• 제7권3호
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• pp.401-409
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• 1996

Sodium N-lauroyl-N-methyl taurate의 cmc에 대한 온도효과를 검토하였다. cmc값들은 처음 $20^{\circ}C{\sim}40^{\circ}C$의 온도 범위에서는 감소하다가 더욱 온도가 증가되면 다시 증가하는 경향이었다. cmc에 대한 온도의 의존성으로부터 여러가지 열역학적 파라미터들(${\Delta}H_m$, ${\Delta}G_m$, ${\Delta}S_m$)을 산출하였다. Sodium N-lauroyl-N-methyl taurate의 cmc에 대한 여러 전해질들의 첨가효과를 또한 검토하였고, 소수성결합 형성에너지 및 미셀의 해리도를 log cmc와 log conc.의 곡선으로부터 산출하였다. ${\Delta}H_m$값들은 온도가 증가함에 따라 감소하였고, $40^{\circ}C{\sim}50^{\circ}C$의 온도범위에서 부호가 양에서 음으로 변하였다. ${\Delta}G_m$값들은 전해질 농도 및 온도가 증가할수록 감소하였다.

• 충청수학회지
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• 제26권2호
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• pp.269-273
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• 2013

We prove a characterization of the power function distribution by lower record values. We prove that $F(x)=(\frac{x}{a})^{\alpha}$ for all $x$, 0 < $x$ < $a$, ${\alpha}$ > 0 and $a$ > 0 if and only if $\frac{X_{L(n)}}{X_{L(m)}}$ and $X_{L(m)}$ are independent for $1{\leq}m$ < $n$.

• 충청수학회지
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• 제27권2호
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• pp.243-247
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• 2014

Let {$X_n$, $n{\geq}1$} be a sequence of i.i.d. random variables with absolutely continuous cumulative distribution function(cdf) F(x) and the corresponding probability density function(pdf) f(x). In this paper, we give characterizations of Pareto and Weibull distribution by considering conditional expectations of record values.

• 충청수학회지
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• 제30권3호
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• pp.285-289
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• 2017

Let $\{X_n,\;n{\geq}1\}$ be a sequence of independent and identically distributed random variables with cdf F(x) which is absolutely continuous with pdf f(x) and F(x) < 1 for all x in ($-{\infty},\;{\infty}$). In this paper, we obtain the characterizations of the Gumbel distribution by lower record values.

• Asian-Australasian Journal of Animal Sciences
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• 제12권6호
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• pp.871-880
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• 1999

The effects of dry roasting (110, 130, $150^{\circ}C$ for 15, 30, 45 min) on potential ruminant protein nutritional values in terms of: a), rumen bypass protein (BCP); b), rumen bypass starch (BST); c), fermented organic matter (FOM); d), true absorbed bypass protein (ABCP); e) microbial protein synthesized in the rumen based on available energy (E_MP); f), microbial protein synthesized in the rumen based on available nitrogen (N_MP); g), true protein supplied to the small intestine (TPSI); h), true absorbed rumen synthesized microbial protein (AMP); i), endogenous protein losses (ENDP); j), true digested protein in the small intestine (DVE); k), degraded protein balance (OEB) of whole lupin seeds (WLS) and faba beans (WFB) were evaluated by the new Dutch DV/OEB protein evaluation system. Dry roasting significantly increased BCP, BST, TPSI, ABCP, DVE (p<0.001) and decreased FOM, E_MP, AMP, N_MP and OEB (p<0.001) with increasing temperatures and times except that when temperature was at $110^{\circ}C$. The values of BCP, BST, TPSI, ABCP and DVE at $150^{\circ}C/45min$ for WLS and WFB were increased 2.2, 3.7; -, 2.0; 1.7, 1.7; 2.3, 3.7 and 1.7, 1.7 times and the values of FOM, E_MP, AMP, N_MP and OEB at $150^{\circ}C/45min$ for WLS and WFB were decreased by 15.3, 25.8; 18.1, 25.8; 18.7, 25.8; 54.6, 41.6 and 82.3% 54.7%, respectively, over the raw WLS and WFB. The results indicated that though dry roasting reduced microbial protein synthesis due to reducing FOM, TPSI didn't decrease but highly increased due to increasing BCP more than enough for compensation of the microbial protein decreasing. Therefore the net absorbable DVE in the small intestine was highly increased. The OEB values were significantly reduced for both WLS and WFB but not to the level of negative. It indicated that microbial protein synthesis might not be impaired due to the sufficient N supplied in the rumen, but the high positive OEB values in the most treatments except of $150^{\circ}C$ for 30 and 45 min of WLS (The OEB values: 54.8 and 26.0 g/kg DM) indicated that there were the large amounts of N loss in the rumen. It was concluded that dry roasting at high temperature was effective in shifting protein degradation from rumen to intestines and it increased the DVE values without reaching the negative OEB values. No optimal treatment was found in WLS due to the too high OEB values in all treatments. But dry roasting at $150^{\circ}C$ for 30 and 45 min might be optimal treatments for WLS due to the very lower OEB values.

• Journal of Applied Biological Chemistry
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• 제44권3호
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• pp.135-139
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• 2001

To observe the changes in isotopic composition (${\delta}^{15}N$) of $NO_3{^-}$ during denitrification, an incubation experiment using soil treated with nitrification inhibitor (2-chloro-6-trichloromethyl-pyridine) under water-saturated condition was conducted for 153 h. The $NO_3-N$ concentration decreased from 73.3 to $20.6mg\;kg^{-1}$ during the incubation period, with denitrification rate constant of $0.00905h^{-1}$, and ${\delta}^{15}N$ values of $NO_3-N$ increased from +0.9 to +25.5‰ with decreasing the $NO_3-N$ concentration. The increase in the ${\delta}^{15}N$ values of $NO_3-N$ is due to kinetic isotope fractionation, which always results in $^{15}N$ enrichment of the substrate. The isotopic fractionation factor calculated in this study was 1.0196, an indication that 1.96% more $^{14}NO_3{^-}$ reacted at a given time interval than a comparable number of $^{15}NO_3{^-}$. The ${\delta}^{15}N$ values measured through the incubation study showed a good agreement with the results calculated from the Fochts isotope fractionation model. Our results suggest that when the ${\delta}^{15}N$ of $NO_3{^-}$ is used for tracing the fate of N, the kinetic isotope fractionation associated with denitrification must be taken into consideration.

• Journal of Chest Surgery
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• 제27권9호
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• pp.738-745
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• 1994

In order to evaluate the myocardial injury in cardiac valvular and coronary surgery, variables of creatine kinase[CK], myocardial band of CK[CK-MB], lactate dehydrogenase[LDH], aspartate aminotrasferase[AST] were measured in the preoperative[Preop], the operation day[POD0], and the first[POD1], third[POD3], fifth[POD5], seventh[POD7], ninth[POD9] day after operation in 29 patients. The subjects were divided into two groups according to the diseases: group V [valvular disease, n=16] and group C[coronary artery disease, n=13]. Each group was subdivided into two subgroups according to the duration of aortic crossclamping time[ACT]; group VI[ACT 120min, n=7] and group VII[ACT>120min, n=9]; group CI[ACT 120min, n=6] and group CII[ACT>120min, n=7]. The results were as followed 1. The values of CK between group V and group C had no significant difference. The values of CK in group CII were significantly greater than those in group CI and the values of CK in group VII were significantly greater than those in group VI. 2. Percentages of CK-MB between groups had no significant difference. 3. The serum levels of LDH in group V were significantly greater than those in group C. The serum levels of LDH in group VII were significantly greater than those in group VI. 4. The serum levels of AST in group VII were significantly greater than that in group VI. We were concluded that myocardial injury was more related with the duration of aortic cross clamping time rather than the type of diseases.

• 대한치과보철학회지
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• 제45권3호
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• pp.329-338
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• 2007

Purpose. The aim of this study is to evaluate the effect of TiN coating of abutment screw on the unscrewing torque. Material and methods. Titanium and Gold-Tite abutment screws were classified into two groups, Group A and C respectively, as control groups. Titanium abutment screws with TiN coatings were also classified into two groups, Group B and D, as experimental ones. Group A and B were tightened to 20 Ncm input torque, and Group C and D were tightened to 32 Ncm torque. Detorque values were measured with digital torque gauge during repeated closing and opening experiment. Results. Abutment screws with TiN coating (Group B and D) showed statistically significant higher mean detorque values than those of Group A and C. Discussion. Physical properties of TiN coating, such as low friction coefficient, high hardness and wear resistance, might contribute to higher detorque values. Conclusion. It is suggested that TiN coating of abutment screw help to reduce the risk of screw loosening and improve the stability of screw joint.