• 한국환경교육학회지:환경교육
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• 제24권3호
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• pp.18-25
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• 2011

This study was conducted to evaluate the effects of volatile organic compounds and formaldehyde of newly-built school classroom indoor air on the neurobehavioral functions of students. The elementary schools that were opened in September 2008(as of September 2008) was selected for newly-built school and the elementary school that were opened in March 2006 was selected for control group schools. The concentration of formaldehyde(HCHO), a hazardous organic compound that exists in the air of classrooms, exceeded the standard value of $108.2{\mu}g/m^3$ in newly-built schools while it was $60.8{\mu}g/m^3$ in control group schools, which is around 60% of the standard concentration. However, the concentration of the total volatile organic compounds(TVOCs) was $788.9{\mu}g/m^3$ and $756.1{\mu}g/m^3$ in newly-built schools and control group schools respectively, which are approximately two times higher than the standard concentration. In newly-built schools, the mean reaction time of additions and symbol digit, respectively 3,020ms and 2,398ms in pre-exposure were increased to 3,167ms and 2,514ms respectively in post-exposure. The difference of mean reaction time between pre and post exposure was 146.8 ms, or 4.6%, and 116.7ms, or 4.8%, respectively, showing statistically-significant increase of reaction time(p<0.05). On the contrary, the difference of reaction time of both tests were not statistically significant in the control group schools. These results showed that the neurobehavioral performance of newly-built schools students were affected by volatile organic compounds and formaldehyde of classroom indoor air.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1998년도 춘계학술대회 논문집
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• pp.298-303
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• 1998

Most of mechanical structures are combined of substructures such as beam and/or plates. There are few system with unibody structures but are not a few systems with united body structures. Generally the dynamic analysis of whole structures is perform ed under alternating load. However, the analysis of each joint area is more important than others for zero severity. This paper presents the results of analysis of concentration stress in bolt jointed structure with variable preload. At frist, a static vibration test was performed to find out a nominal stress of bolt joint ed plates from the relationship between natural frequency and nominal stress. Then a concentration stress was computed at contact point between bolt and plate in the structure. It is believed that the proposed method has promising implications for safer design with fatigue quality index of stress concentration factor and has merit for cost down and saving time at the beginning of vehicle development.

• 한국의류산업학회지
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• 제6권3호
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• pp.393-398
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• 2004

This research offers recycling method of NaOH from mercerizing process of cotton fabric. The measuring system of NaOH concentration was designed for the mercerizing process and tested for various conditions which can be occurred in factory. The accuracy of the system was varied as the testing condition was changed. As the concentration of sulfuric acid used for titrating NaOH decreased, the accuracy of measuring system increased. The concentration of NaOH for waste water collected from mercerizing process was measured by 5.2%. As the ratio of newly mixed NaOH increased, moisture regain. water absorbency and whiteness of the specimen increased. The bending rigidity(B) and shear rigidity(G) decreased, as the ratio of newly mixed NaOH increased.

• 한국수학교육학회지시리즈A:수학교육
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• 제52권4호
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• pp.517-529
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• 2013

The purpose of this study is to investigate pre-service teachers' perceptions and their difficulties of mathematics instruction. Pre-service teachers have positive perceptions about teaching students and teaching profession through teaching practicum. In addition, they have perceived that teaching practicum can enhance teaching methods for their students. Especially, they suggested that cooperating teachers' instruction and mathematics teachers and their colleagues' classroom observation are important factors to improve their teaching methods. In other hands, they have difficulties in application of questions encouraging mathematical thinking, attention concentration considering students' interest and planning and performing for mathematics instruction class according to levels of students' study abilities. Based upon this study's findings, teacher education institutes should make efforts to alleviate difficulties in mathematics instruction through effective teaching practicum such as regular reflection activities for their classes, programs development associated with schools, pre-training and education programs for guidance teachers.

• Clinical and Experimental Reproductive Medicine
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• 제40권1호
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• pp.12-22
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• 2013

Objective: We investigated the norepinephrine transporter (NET) expression in normal and pre-eclamptic placentas and analyzed the invasion activity of trophoblastic cells based on norepinephrine (NE)-NET regulation. Methods: NET and NE expression levels were examined by western blot and enzyme-linked immunosorbent assay, respectively. Trophoblast invasion activity, depending on NE-NET regulation, was determined by NET-small interfering RNA (siRNA) and NET transfection into the human extravillous trophoblast cells with or without NE treatment and invasion rates were analyzed by zymography and an invasion assay. Results: NET mRNA was expressed at a low level in pre-eclamptic placentas compared with normal placentas and NE concentration in maternal plasma increased significantly in pre-eclamptic women compared to normal pregnant women (p<0.05). NET gene upregulation and NE treatment stimulated trophoblast cell invasion up to 2.5-fold (p<0.05) by stimulating matrix metalloproteinase-9 activity via the phosphoinositol-3-kinase/AKT signaling pathway, whereas NET-siRNA with NE treatment reduced invasion rates. Conclusion: NET expression is reduced by inadequate regulation of NE levels during placental development. This suggests that a complementary balance between NET and NE regulates trophoblast cell invasion activities during placental development.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 추계학술대회 논문집 Vol.15
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• pp.387-390
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• 2002

SiC direct bonding technology is very attractive for both SiCOI(SiC-on-insulator) electric devices and SiC-MEMS(micro electro mechanical system) fields because of its application possibility in harsh environments. This paper presents pre-bonding techniques with variation of HF pre-treatment conditions for 2 inch SiC wafer direct bonding using PECVD(plasma enhanced chemical vapor deposition) oxide. The PECVD oxide was characterized by XPS(X-ray photoelectron spectrometer) and AFM(atomic force microscopy). The characteristics of the bonded sample were measured under different bonding conditions of HF concentration and an applied pressure. The bonding strength was evaluated by the tensile strength method. The bonded interface was analyzed by using IR camera and SEM(scanning electron microscope). Components existed in the interlayer were analyzed by using FT-IR(fourier transform infrared spectroscopy). The bonding strength was varied with HF pre-treatment conditions before the pre-bonding in the range of $5.3 kgf/cm^2$ to $15.5 kgf/cm^2$

• Journal of Ginseng Research
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• 제35권1호
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• pp.45-51
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• 2011

Wild ginseng has been used as a traditional medicine for thousands of years and for increase physical strength in Korea, China and Japan. This study reports that cultivated wild ginseng (CWG) inhibits adipocyte differentiation of 3T3-L1 pre-adipocytes in a concentration-dependent manner. Inhibition of adipocyte differentiation is one possible anti-obesity strategy. CWG inhibits the expression of the adipocyte differentiation regulator peroxisome proliferators-activated receptor (PPAR)${\gamma}$ and CCAAT/enhancer-binding protein ${\alpha}$mRNA. It also inhibited the expression of PPAR${\gamma}$ and adiponectin at the protein level during the differentiation of pre-adipocytes into adipocytes. Additionally, CWG blocked the cell cycle at the sub-$G_1$ phase transition, causing cells to remain in the pre-adipocyte state. These results indicate that CWG inhibits adipocyte differentiation and adipogenesis through pre-adipocyte cell cycle arrest in cultured 3T3-L1 cells.

• 한국의상디자인학회지
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• 제10권3호
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• pp.173-180
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• 2008

Cotton, wool, cotton/wool blended (80:20) and tencel fabrics were treated with low temperature oxygen plasma, enzymes (cellulase or protease), or oxygen plasma-enzyme and they were examined for dyeing and handling properties for environment friendly finishing. The appropriate conditions for cellulase treatment were enzyme concentration of 3g/l, pH of 5, and $60^{\circ}C$ for one hour, and for protease treatment were enzyme concentration of 4g/l, pH of 8, and $60^{\circ}C$ for one hour. The equilibrium uptake of a direct dye on cotton changed with plasma treatment and plasma-cellulase treatment, and the rate of dyeing slightly decreased. When wool was dyed with acid dye, the equilibrium dye uptake did not change with plasma, protease treatment nor plasma-protease treatment, however, the rate of dyeing had increased with plasma-protease treatment. From these results, it is assumed that plasma attacks the surface of the fiber, and enzyme mainly affects the inner part of the fiber. Plasma treatment did not affect mechanical properties related to the handling of fabrics. The handling test showed increased extension at maxmum load(EM), tensile energy(WT) with decreased tensile resilience (RT), and the fabrics became softer but resilience decreased slightly with enzyme treatment. The bending recidity(B), hysteresis of bending moment(2HB), and hysteresis of shear force at five degrees(2HG5) decreased, however, shear stiffness(G) increased. I knew the plasma pre-treatment made fabrics softer with lower koshi(stiffness). The handling of plasma pre-treated fabrics was better than that of enzyme-treated fabrics. When we pre-treated fabrics, the handling test showed decreased coefficient of friction(MIU), geometrical roughness(SMD), while the surface of fabrics became smoother and numeri increased. Even though compression resilience(RC) increased, fukurami(bulky property) and compressive elasticity, decreased due to the linearity of compression-thickness curve(LC) and compression energy(WC).

• 한국의류학회지
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• 제33권2호
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• pp.256-265
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• 2009

The purpose of this study is to check color change, color fastness, increase wt., antibiosis, and UV-protection efficiency depending on gallnut concentrations and mordanting methods, when silk fabrics dye with gromwell according to pH. This results will contribute in developing of natural mordant with multi function. The results are as follows. ${\lambda}_{max}$ of Gallnut extracts was near 299 nm. When gallnut was used as a mordant, at all pH levels, pre-mordanted fabrics had red color and post-mordanted ones had red-purple color which was closed to natural color of gromwell. Brightness of post-mordanted fabrics was higher than that of pre-mordanted fabrics. In the case of chroma, pre-mordanted fabrics was higher than post-mordanted fabrics. There was no significant difference of color, brightness, and chroma depending on gallnut concentration. As mordanting concentration increased, fabric weight gradually went up and increase weight reached maximum $17{\sim}19%$. At all pH levels, color fastness improved by pre-mordanting and post-mordanting, and it showed the maximum $4{\sim}5$ grade of wet fastness and 5 grade of dry cleaning. Antibiosis of silk fabric was improved by gromwell dyeing and synthetic tannin mordanting. Antibiosis of gallnut extracts was excellent. The color fastness and antibiosis were preserved after 10 cycle dry cleaning. UV-protection efficiency was excellent by dyeing with gromwell and mordanting with gallnut.

• 한국임상수의학회지
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• 제1권1호
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• pp.11-23
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• 1984

Epizootiolosical factors of 166 cows with abomasal displacement were studied and in 21 out of 166 cows, the functions of liver and kidney were also tested. 1. Incidence of abomasal displacement was perdominant in small sized dairy herd less than 15 cows, using area of paddock below 165㎡. 2. Out of 166 cows with abomasal displacement, 116 cows (70%) were found left sided displacement and 50 cows (30%) were right. 3. Generally, one to two weeks were taken before treatment of veterinarian following onset of sign of the diseases. Therefore many cases were found to be severe in their illness. 4, Incidence rate of abomasal displacement was predominant in summer season (June, July and Au-gust). However, occurence of the disease was continuous throughout the year. About 80 percent of abomasal displacement was distributed from first to third purturition. 5. High milk production and feeding with high concentrates and low roughage showed a tendendy to occurs the disease. 6. Approximately 75% of abomasal displacement was distributed within 1 month pre and post partum. 7. Cows with abomasal displacement consumed little concetrates and 75% of cows with abomasal displacement passed abnormal fecal material. 8. Sixty six out of 166 cows with abomsal displacement were coincident with diseases such as retained placenta, metritis, traumatic reticulo-peritonitis and mastitis. 9. In many cass of abomasal displacement, abomasum was extended with gas. 10. Activities of AST ana LDH showed the trends to reduce after surgical intervention comparing with pre-surgery. Bilirubin concentration markedly decreased after surgical treatment comparing with pre-surgery. 11. The concentration of BUN and creatinine moderatly decreased after surgery compared with pre-surgery.