• Journal of the Korean institute of surface engineering
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• v.39 no.6
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• pp.295-301
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• 2006

Hard chrome plating has been used in surface hard coating over 50 years both for applying hard coating and re-building of worn components. Hard chrome plating solution and mist pollute environment with very toxic $Cr^{6+}$(hex-Cr) known as carcinogen which causes lung cancer, High velocity oxy-fuel (HVOF) thermal spray coatings of WC base cermet and Co-alloy powders are the most promising candidates for the replacement of the traditional hard chrome plating. Surface properties, wear, and friction behaviors of micron size Co-alloy (T800) and micron size WC-l2Co (WC-Co) have been studied for the application as hard coatings. The temperature dependence of wear and friction behaviors of T800 and WC-Co have been investigated at the temperature of $25^{\circ}C$ and $538^{\circ}C$ for the application to high speed spindle.

• Physical Therapy Korea
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• v.22 no.4
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• pp.1-7
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• 2015

This case report describes the effectiveness of cervical corrective exercises in a patient with cervical radiculopathy (CR) who experienced radicular pain, upper limb paresis, and limited functional activity. A 39-year-old male with cervical radiculopathy performed the cervical corrective exercises for reducing pain. Pain intensity, cervical posture, and active range of motion of cervical intersegmental spine motion were measured baseline, after 4 weeks, and after 8 weeks with self-reported questionnaire and radiographs. After 8 weeks of intervention, the patient demonstrated alleviated radicular symptoms, improved neck posture and active range of flexion and extension of the cervical intersegmental spine. Especially in the angle between the cervical vertebra 6 and 7, the angle was changed from $-4.69^{\circ}$ to $3.30^{\circ}$ during resting position after intervention. The present case indicates that the cervical corrective exercises might be a possible treatment to effectively reduce radicular symptoms, improve neck posture, and active cervical intersegmental motion for patient with CR.

• Nuclear Engineering and Technology
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• v.9 no.1
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• pp.39-44
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• 1977

The configuratior and conformation of N-methyl-C-phenylalkyl-ketimine isomers, Ph-CR=N$CH_3$ (R=H, $CH_3$, $CH_3$CH$_2$), have been studied from extended Huckel molecular orbital calculations. The result shows that the E-configuration of the C=N double bond is favored compared with that of the Z-configuration. The most preferable conformation of the phenyl ring rotamer in N-methyl-C-phenylaldimine and N-methyl-C-phenylmethylketimine are the coplanar forms with regard to the C=N plane, but the conformation of the $CH_3$CH$_2$-rotamer, in N-methyl-C-phenylethyl-ketimine, the gauche form (dihedral angle between C=N and $CH_3$CH$_2$- plane=90$^{\circ}$) is favored.

• Korean Journal of Animal Reproduction
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• v.20 no.2
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• pp.163-170
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• 1996

The effect of several potential antioxidants and amino acids were examined as a means of increasing the development of in vitro matured and in vitro fertilized oocytes into morulae or blastocysts. Bovine embryos developed to the 2~8 cell stage after in vitro fertilization were cultured for 5 to 6 days at 39$^{\circ}C$ in CR1aa containing varing concentraton of the antioxidants and amino acid in a gas phase consisting of 5% CO2, high humidified air. At 5~6 days, embryo developments were reduced, and embryos were fixed and stained with Hochest 33342 DNA stain to facilitate counting of cells. In experiment 1, the proportion of embryos developed to morulae and blastocysts in CR1aa containing 1mM, 2.5mM taurine (22.6% and 20.4%) was slightly higher than those of 0, 5 and 10mM Taurine (5.7, 5.7 and 3.9%, P<0.05). In experiment 2, addition of glutathione did not improve blastocyst development (P>0.05). In experiment 3, concentations of superoxide dismutase(SOD) ranging from 300 to 1,000 U did not affect the propotion of embryos developing into blastocysts (P>0.05). In experiment 4, addition of 250 U catalase(38.5%) was slighty higher than those of 0, 500 and 1,000U. In experiment 5, the proportion of embryo developed beyond morula stage in CR1aa with taurine plus EDTA was slighty higher than other treatments(15.7, 26.0 and 29.2%), there were no significantly increases in cell number among treatments(P>0.05). These results are indicating that antioxidants and amino acids can increase the proportion of embryos that develop into morulae and blastocysts, but did not increas in cell number of blastocysts.

• Proceedings of the KSAR Conference
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• 2001.03a
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• pp.65-65
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• 2001

본 연구는 칡소 귀세포를 공여핵으로 이용한 체세포 복제송아지 생산에 있어서 배양방법이 배발생 및 배반포 발달율에 미치는 영향과 체세포 복제란의 이식후 수태율에 미치는 영향을조사하여 복제송아지의 생산 효율을 제고하고자 실시하였다. 실험에 공시된 공여핵은 칡소 의 귀세포를 회수하여 10%FBS가 첨가된 DMEM배지에서 3-4일 동안 배양하여 monolayar Confluent 형성 후 0.25% trypsin을 처리하여 준비하였으며 공여세포는 적어도 passage가 5회 이상의 세포만을 사용하였다. 복제수정란의 생산은 18-20시간 동안 체외성숙 된 난자의 핵을 제거하고 공여핵을 주입하여 2.2kv/cm, 10$\mu\textrm{s}$의 전압으로 2회 자극함으로 융합하였으며, 융합된 난자는 5$\mu\textrm{g}$/$m\ell$ ionomycin에서 4분간, 1.9mM 6-dimethyl aminopurine에서 4시간동안 배양하여 활성화처리를 하였다. 핵이식수정란의 배양은 39$^{\circ}C$, 5%$CO_2$ incubator에서 처리구 I은 CRlaa에서 4일간 배양 후 CR2aa배지에서 배양, 처리구II는 CRlaa에 4일간 배양후 CR2aa배지에 cumulus cell과 공배양, 처리구III은 CR2aa 배지에 camulus cell과 함께 배양하였다. 수정란이식은 발정발현 7일째에 비외과적 방법으로 젖소 미경산우에 이식하였으며 이식란수는 2~4개의 핵이식된 수정란을 이식하였다. 임신진단은 45~60일 사이에 직장검사 및 초음파 진단기를 이용하여 실시하였다. 배양방법에 따른 배발생율은 처리구 I에서 92.2 %(83/90)으로 처리구II와 III의 62.4%(63/101)와 77.8%(144/185)에 비하여 높게 나타났으나 배반포 발달율은 처리구II와III에서 65.1%(41/63)와 50.0%(72/144)로 처리구 I의 30.1%(25/83)보다 높게 나타났다. 각 처리구에 따른 수정란 이식후 수태율은 처리구II와 III에서 공히 20%의 수태율을 나타낸 반면 처리구 I에서는 수태가 되지 않았다. 따라서 체세포 복제수정란의 생산에 있어서 배반포 발달율과 수태율을 높이기 위해서는 단순배양보다 공배양이 더 효과적인 것으로 사료되지만 이런 결과가 복제송아지 생산효율에 있어서도 효과적일지는 향후 더 많은 연구가 있어야 할 것으로 사료된다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.8
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• pp.664-670
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• 2002

The electrical characteristics of $ZnO-Pr_6O_{11}-CoO-Cr_2O_3-Y_2O_3$(ZPCCY)-based varistors were investigated with $Y_2O_3$ content in the range of 0.0~4.0 mol%. As $Y_2O_3$ content is increased, the average grain size was markedly decreased in the range of 18.6~3.2 $\mu m$ and the density of the ceramic was decreased in the range of 5.53 ~3.74 $g/\textrm{cm}^3$. While, the varistor voltage was increased in the range of 39.4~748.1 V/mm and the nonlinear exponent was in the range of 4.5~51.2 with increasing $Y_2O_3$ content. The addition of $Y_2O_3$ greatly enhanced the nonlinear properties of varistors, compared with the varistor without $Y_2O_3$. In particular, the varistors with $Y_2O_3$content of 0.5 mol% exhibited the highest nonlinearity, in which the nonlinear exponent is 51.2 and the leakage current is 1.3 $\mu A$. The donor concentration and the density of interface states were decreased in the range of (4.19~0.14) $\times$10$^{18}$ /㎤ and (5.38~1.15)${\times}10^{18}/\textrm{cm}^3$, respectively, with increasing $Y_2O_3$ content.

• Journal of Technologic Dentistry
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• v.42 no.2
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• pp.81-89
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• 2020

Purpose: This in vitro study was conducted to evaluate the marginal and internal fit of three-unit Co-Cr frameworks fabricated by computer-aided metal milling and direct metal laser sintering(DMLS) systems in comparison to conventional casting method. Methods: Three-unit Co-Cr frameworks were fabricated by conventional wax up with casting(CWC), computer-aided metal milling(MM) and direct metal laser sintering(DMLS)(n=10 each). The marginal and internal fit of specimens were examined using a light-body silicone impression material. The thickness of light-body silicone was measured at eight reference points each, divided in the mesio distal and bucco lingual directions. All measurements were conducted by a stereomicroscope. Digital photos were taken at 150× magnification and then analyzed using a measurement software. The Kruskal-Wallis test and Bonferroni correction were used for analyzing the results. Results: The mean(SD) is ㎛ for fabrication methods, the mean marginal fit were recorded respectively, DMLS 39(27), followed by CWC 63(38), MM 220(128). and the mean internal fit CWC 95(47), DMLS 116(49), MM 210(152). In addition, the largest gap was found in the occlusal surface area among the internal measurement areas of all groups. Conclusion: As a result, the direct metal laser sintering method showed better marginal and internal fit than the metal milling method. The marginal and internal fit were statistically different according to the three fabrication methods(p<0.001). Except the MM group, the marginal fit of the CWC and DMLS groups was below the clinical standard of 120 ㎛. Based on the results of this study, it can be applied to clinical use in the future.

• Journal of Environmental Health Sciences
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• v.38 no.4
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• pp.323-331
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• 2012

Objectives: The objective of this study was to investigate the possible effects of environmental cadmium (Cd) exposure on of bone mineral density (BMD) levels. Methods: A total of 171 residents around abandoned mines in Chungcheongnam-do were surveyed in 2008-2011. Urinary Cd and BMD were analyzed by atomic absorption spectrometry and Dual-Energy X-ray absorptionmetry, respectively. Osteoporosis and osteopenia were defined by T-scores set by the WHO; Tscore ${\geq}$ -1.0, normal; -1.0 > T-score > -2.5, osteopenia; and T-score ${\leq}$ -2.5, osteoporosis. Logistic and multiple linear regressions were applied to estimate the association between U-Cd levels and BMD. Results: The U-Cd geometric mean of 171 Koreans was 2.79 ${\mu}g/g{\cdot}cr$. The U-Cd concentration was significantly higher among women (2.98 ${\mu}g/g{\cdot}cr$) than men (2.39 ${\mu}g/g{\cdot}cr$). With the multiple regression model, the BMD was influenced by U-Cd, BMI, and monthly income. With the logistic regression model, osteoporosis was associated with U-Cd levels (OR = 3.239, 95% CI = 1.770-5.927). Conclusions: We conclude that exposure to cadmium is associated with an increased risk of osteoporosis.

• The Korean Journal of Nuclear Medicine
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• v.3 no.1
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• pp.33-39
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• 1969

The conventional triolen absorption test has its defect in that the stool collection was cumbersome, time and energy-wasting. In the present study, the triolen absorption test was carried out using double tracer technique with $^{125}I-triolen\;and\;^{51}Cr_2O_3$ to determine if it can overcome the defect of the conventional method also with satisfactory results. Following were the results: 1. The clinical significance of this double tracer method was essentially the same with that previously done by radioactive. triolen alone. With the fractional fecal samples, the equation, y=0.626x+2.010 was substantiated, hence, this method appears to be clinically valuable if the appropriate correction is applied. With the mixed fecal samples, the equation y=0.642x+1.468 was substantiated (p<0.005) which appears to be also clinically valuable. When these two data were compared, the equation y=0.975x+0.090 (P<0.05) was substantiated, hence, $x{\fallingdotseq}y$. 2. The normal ranges of the fecal triolen excretion rate in this double tracer method were $3.46{\pm}1.69%$, namely, less than 6.9%. 3. The samplings were done from the first to third defecation in cases of clinically normal, and from the first to second defecation in cases of diarrhea or malabsorption. 4. The intestinal malabsorption of triolen was not observed in whom the triolen absorption was supposed to be clinically normal, however. a good number of suspicious malabsorptive cases showed the normal values.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.10
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• pp.897-901
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• 2003

The microstructure and varistor characteristics of ZnO-Pr$_{6}$O$_{11}$-CoO-Cr$_2$O$_3$-Dy$_2$O$_3$(ZPCCD)-based ceramics were investigated with Dy$_2$O$_3$ content in the range of 0.0∼2.0 mol%. As Dy$_2$O$_3$ content is increased, the average grain size was decreased in the range of 18.6∼4.7 $\mu$m and the density was decreased in the range of 5.53∼4.34 g/cm$^3$. While, the varistor voltage was increased in the range of 39.4∼436.6 V/mm and the nonlinear exponent was in the range of 4.5-66.6 with increasing Dy$_2$O$_3$ content. The addition of Dy$_2$O$_3$ highly enhanced the nonlinear properties of varistors, compared with the ceramics without Dy$_2$O$_3$ Particularly, the ceramics with Dy$_2$O$_3$ content of 0.5 mol% exhibited the highest nonlinearity, in which the nonlinear exponent is 66.6 and the leakage current is 1.2 $\mu$A.A.A.