• Journal of Korea Foundry Society
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• v.25 no.6
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• pp.226-232
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• 2005

Contact material is widely used in the field of electrical parts. Ag-CdO material has a good wear resistance and stable contact resistance. In order to establish optimizing heat treatment condition, rolling temperature and oxidation process, we studied the microstructure of Ag-CdO material with various conditions. The experimental procedure were melting using high frequency induction, heat treatment, rolling and internal oxidation. And we experimented on difference process, Post-oxidaion. In this study, we obtained the optimizing heat treatment condition was $700^{\circ}C$ for 15 min. and the optimizing rolling temperature was $730^{\circ}C$. In investigation of the microstructure of oxidized material, coarse oxide and depleted oxidation layer existed. The hardness was average Hv 70. When we used Post-oxidation, oxides were finer than prior process and depleted oxidation layer did not exist. The hardness of Post-oxidation material was average Hv 80. And the optimizing rolling temperature was $800^{\circ}C$.

• Journal of Industrial Technology
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• v.7
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• pp.49-58
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• 1987

To investigate the effect of the Retrogression and Reaging (RRA) treatment on the strength and the stress corrosion cracking in AA 7039 the measurement of hardness, tensile properties and the time to failure in a constant rate method were measured. Transmission electron microscope was used to examine the microstructural changes within graln and grain boundary. The results show that the RRA treatment of the T6 condition results in a significant increase in the time to failure without sacrifying the original T6 strength. It is believed that high density and even distribution of precipitates in RRA condition were observed within grain so that the RRA condition could have similar strength to the T6 condition. The presence of fine dispersion of semicohernt ${\eta}^{\prime}$ transition phase is also believed to contribute to that effect. Examination of the grain boundary microstructure shows that the RRA treatments increases significantly the average size of the grain boundary preciptates. It is suggested that the benificial effect of the RRA treatment on the susceptibility to SCC be due to the increase in the size of grain boundary precipitates obtained during the retrogression treatment.

• Journal of Nutrition and Health
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• v.39 no.8
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• pp.801-807
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• 2006

To elucidate the effect of soy isoflavone supplementation on bone mineral density and antioxidant enzyme activity in 60 postmenopausal women residing in Iksan area were recruited. There were 31 participants in the treatment group and 29 in the control group. The treatment group consumed isoflavone extract capsules daily (which contained 90 mg of soy isoflavones) for 12 weeks. The study compared before and after isoflavone intake in the following areas. Physical examination, diet survey, bone mineral density (BMD) and antioxidant enzyme activity (superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT) and total antioxidant capacity (TA)). The average age of the treatment group was 64.6 years and that of the control group was 66.5 years. There were no significant differences between the two groups in terms of height, weight and body mass index. Both groups maintained a regular diet pattern in terms of their average daily nutrient intake. There were no significant differences between the treatment group (23.3 mg) and the control group (24.0 mg) in terms of daily isoflavone intake based on diet. Isoflavone supplementation of 12 weeks did not resulted in any significant changes in BMD or parameters of antioxidant enzyme activity, implying the necessity of more intensive intervention for a substantial change. In conclusion, this study revealed that antioxidant enzyme activity holds a significant relationship with the bone mineral density in postmenopausal women and further systematic research on dose and period of isoflavone supplementation is needed to clearify the positive effect of isoflavone on BMD and/or blood antioxidant capacity in postmenopausal women.

• Journal of Embryo Transfer
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• v.29 no.2
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• pp.171-175
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• 2014

This study was conducted to determine the efficacy of anthelmintics against gastrointestinal parasitic infestation in periparturient dairy cows and its effect on milk yield and quality. Sixty pregnant cows of 1st & 2nd parity were divided into four groups. The efficacy of anthelmintic treatment was evaluated by counting faecal egg per gram (EPG) compared with pre-treatment values. The milk yield of each cow was recorded in pre and post treatment lactations. Cows of group A were treated with Nitroxynil 10 mg/kg body weight subcutaneously 30 days before parturition, group B were treated with combination of triclabendazole and levamisole 19.5 mg/kg body weight orally at calving and group C treated with $Endex^{(R)}$ at calving and 42 days after. The mean change in EPG 14 days after treatment was significantly higher (p<0.05) in treated (79.1%) cows than control. Average milk yield of group C ($2.8{\pm}0.8$) was significantly higher (p<0.01) than group A ($2.6{\pm}0.7$). Similarly, the average milk yield in all the treated cows was significantly (p<0.01) higher in treated lactation ($2.5{\pm}0.7$) than in the previous lactation ($2.2{\pm}0.7$). The average milk yield in all treated cows was significantly (p<0.01) higher than the control cows. Although, milk yields were higher in second parity than the first, there was no significant difference (p>0.05). The milk protein percentage was significantly higher (p<0.05) in treated group than the control group. Therefore, it may be concluded that periparturient anthelmintic treatment effectively reduced the gastrointestinal parasitic load and improved milk yield.

• International Journal of Highway Engineering
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• v.14 no.6
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• pp.85-92
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• 2012

PURPOSES : Since expressways in South Korea are toll roads, many trumpet type interchanges exist, resulting in the installation of loop ramps very frequently. While the travel speed of the main lane is designed to be 100-110 km/h, the structure of a loop ramp is different and is designed for a minimum speed of 40 km/h. In fact, most of the actual travel speeds measured on the ramp exceed the designated speed, which has been a major problem in traffic safety. In this research, a type of pavement marking speed-reduction treatment called the "Peripheral Transverse Line" is installed on expressway loop ramps in order to study the change of driving speeds after the installation. METHODS : To verify statistically the change, this speed-reduction treatment has been installed on the Chungju interchange and the Yeoju junction. The driving speeds before the installation were compared with driving speeds both one month and five monthsafter the installation. RESULTS : As a result, the reductions of the average driving speeds after the treatment were statistically significant. More specifically, the average driving speeds of the Chungju interchange were reduced by 7.1-7.7 % for its tangent road section, and the speeds decreased by 8.5-9.5 % for its curve section. Similarly, in the Yeoju junction, an average speed reduction of 2.9-4.8 % for its tangent section was measured, along with 3.9% long-term speed reduction for its curve section. CONCLUSIONS : Since the pavement marking speed-reduction treatment has been partially proven to be effective from this research, we expect to expand this treatment and re-confirm the effect from a long-term perspective in the future.

• Speech Sciences
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• v.15 no.2
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• pp.131-141
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• 2008

The purpose of this study was to find out the acoustic variation on the pre-and post respiration and oral motor for children with cerebral palsy. Five children with spastic CP at the age of 6 in average were practiced by a caregiver at home each for 25 minutes, in total, 45 times. The sustained of vowel /a/ and vowels /a/, /i/, /u/, /e/, /o/ were recorded on CSL and MDVP and analyzed by acoustic parameters. As a result, the maximum phonation time(MPT) was increased from 2.06 to 6.31 and the formant of vowels(F1, F2, F3) had significant differences in F1(/a, i/), F2(/i.u.o/), and F3(/a/) between the controls and the children with CP in pre-treatment. The total average value of vowels had significant differences between the pre-and post-treatment (p< .05). The energy of vowels had significant differences in the vowels /i, u, e, o/ and the total average value between the pre-and post-treatment(p< .001). The jitter percent, shimmer percent, and noise to harmonic ratio had significant differences between the pre-and post-treatment(p< .05). As the respiration and the oral motor improved MPT, voice quality, and articulation of vowel, and the variation of the formant(F1, F2, F3) showed the changes in the shape of lips, the place and the height of the tongue, the various development of therapy programs and the consistent intervention of treatment is needed for the children with cerebral palsy.

• The Journal of Korean Medicine
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• v.31 no.2
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• pp.71-77
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• 2010

Objectives: We investigated whether oriental medical therapy influences the results of in vitro fertilization-embryo transfer. Methods: 19 women with infertility were treated by oriental treatment from August 1999 to June 2000 in the department of obstetrics and gynecology of an oriental medical center. The women were planning in vitro fertilization-embryo transfer after oriental medicine treatment. The data from the women was analyzed, we obtained the following results. Results: The average age of infertile women was $35.42{\pm}4.86$; infertility caused by male factor or tubal factor were the most frequent. The average number of previous failed IVF treatments was $2.21{\pm}1.81$. The number of aspirated oocytes was $9.00{\pm}6.09$ in IVF cycle before oriental therapy, increasing to $9.80{\pm}5.41$ after therapy, but it was not statistically significant. In IVF before oriental therapy, the average number of embryos transfer was $3.20{\pm}1.90$, and it significantly increased to $4.40{\pm}1.45$ after treatment. The quality points of embryos were $10.00{\pm}6.02$ before treatment, but statistically significantly improved to $14.07{\pm}4.98$ after. The characteristics of women being pregnant and non-successful women were compared with age, period of taking herbal medicine and the number of failed IVF treatments, but there was no significant difference. Conclusion: Oriental treatment before IVF could be expected to have good results in treatment of infertility.

• Asian-Australasian Journal of Animal Sciences
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• v.33 no.12
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• pp.2031-2038
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• 2020

Objective: This study aimed to determine the effect of intermittent feeding and cold water on performance and carcass traits in broiler chickens between 4 to 6 wk of age exposed to daily high temperature. Methods: Broilers were assigned to four treatment groups according to a 2×2 factorial design between 22 to 42 d of age (80 broilers per treatment, 4 replications). Broilers were divided into two main groups as feeding type (ad-libitum [AL] and intermittent [IF] for 6 h daily) and sub-groups as water temperature (normal [NW], 24.9℃ and cold [CW], 16.4℃). Heat treatment was applied between 11.00 to 17.00 h daily between 22 to 42 d of age. Results: Live weight at 6th wk was not affected by feeding type and water temperature, but the live weight was significantly higher in IF chickens at the 5th wk (p<0.05). Average weekly gain of IF broiler chickens were higher compared to AL group at 4, 5, and 6 wk of age (p< 0.05). Although feeding type did not affect feed intake in 4 and 5th wk, feed intake was higher in IF chickens at 6th wk (p<0.01). In addition, feeding type and water temperature did not affect feed conversion ratio and interactions were not significant (p>0.05). Water temperature had no significant effect on heart, liver, gizzard, and abdominal fat percentages (p>0.05). Conclusion: It is concluded that IF increased the average weekly gain in chickens reared under daily heat stress for 6 h between 22 to 42 d of age. IF in hot environmental conditions slightly increased performance without adversely affecting health, welfare, and physiological traits, whereas CW implementation had no significant effect on performance. It can also be said that IF suppresses a sudden increase in body temperature depending on age and live weight.

• Applied Chemistry for Engineering
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• v.9 no.7
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• pp.961-967
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• 1998

In order to improve the optical properties and printability of paper, various fillers are used in papermaking. This study was performed to investigate several fillers-precipitated calcium carbonate(PCC), ground calcium carbonate(GCC), and blends(PCC/talc or micro-talc(MVP) and GCC/talc or micro-talc(MVP)-for their effects on various newsprint properties. Results obtained from the study were summarized as follows ; 1) PCC treatment gave about 16.8% higher retention than GCC treatment at the filler level of 5% and the retention of filler in the handsheet increased as average particle size of mixed filler was increasing($PCC{\leq}GCC<MVP<talc$). 2) PCC treatment kept opacity more highly than no filler treatment and opacity decreased as average particle size of mixed filler was increasing. 3) Independent treatment of PCC kept tear strength more effectively than GeC did, and tear strength increased as average particle size of mixed filler was increasing. 4) Independent treatment of pee kept tensile strength more highly than other treatments and Gee treatment kept tensile strength highly than pee treatment under mixed filler treatment. 5) Burst strength under PCC treatments decreased linearly as average particle size of mixed filler was increasing. 6) Compared "With non-filler treatment, filler treatment gave much better printability.

• The Korean Journal of Applied Statistics
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• v.32 no.2
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• pp.173-185
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• 2019

Causal questions are prevalent in scientific research, for example, how effective a treatment was for preventing an infectious disease, how much a policy increased utility, or which advertisement would give the highest click rate for a given customer. Causal inference theory in statistics interprets those questions as inferring the effect of a given intervention (treatment or policy) in the data generating process. Causal inference has been used in medicine, public health, and economics; in addition, it has received recent attention as a tool for data-driven decision making processes. Many recent datasets are observational, rather than experimental, which makes the causal inference theory more complex. This review introduces key concepts and recent trends of statistical causal inference in observational studies. We first introduce the Neyman-Rubin's potential outcome framework to formularize from causal questions to average treatment effects as well as discuss popular methods to estimate treatment effects such as propensity score approaches and regression approaches. For recent trends, we briefly discuss (1) conditional (heterogeneous) treatment effects and machine learning-based approaches, (2) curse of dimensionality on the estimation of treatment effect and its remedies, and (3) Pearl's structural causal model to deal with more complex causal relationships and its connection to the Neyman-Rubin's potential outcome model.