• Journal of Korean Academy of Nursing
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• v.45 no.3
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• pp.449-458
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• 2015

Purpose: Maternal knowledge, positive attitudes and interest toward breastfeeding may improve the sustainability of breastfeeding. This study examined the associations of knowledge, attitudes, and interest toward breastfeeding with the duration of breastfeeding in Korean mothers who used the internet. Methods: We conducted a cross-sectional study of 604 Korean mothers who breastfed their babies. Mothers were recruited through the internet and their knowledge, attitudes and interest toward breastfeeding were assessed using a web-based self-administered questionnaire. Geometric means and odds ratio (OR) with 95% confidence intervals were calculated. Results: Higher knowledge, attitudes, and interest toward breastfeeding were associated with longer duration of breastfeeding in Korean mothers. In particular, mothers who had optimal breastfeeding duration were more likely to be aware of the easiness of breast milk stimulation and breastfeeding, the development of attachment between mother and child, and pleasure from breastfeeding compared to those mothers with shorter duration. The association with optimal breastfeeding duration was more pronounced among mothers who graduated from high school for total attitude scores and total interest scores, compared to mothers who graduated from college or above. Conclusion: The results of this study suggest that it is important to improve maternal knowledge, attitudes, and interest toward breastfeeding in Korean mothers who use the internet as a source of knowledge. Also, the study results imply that the development of strategies to target mothers with relatively low education levels may improve breastfeeding rates.

• International Journal of Industrial Entomology and Biomaterials
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• v.8 no.1
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• pp.27-32
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• 2004

With an objective of evolving quantitatively and qualitatively superior bivolitine silkworm hybrid of Bombyxmori L. for tropics with shorter larval duration without compromising on productivity traits, a breeding programme was initiated at this institute during 1997 by utilizing breeding resource material from the institutes Germplasm collection. The breed SD7 is characterized with plain larvae spinning white oval cocoons and SD12 is characterized by sex-limited larval markings spinning white dumb-bell cocoons. After fixation, these breeds along with other newly evolved breeds were subjected for hybrid evaluation in the laboratory. Based on the hybrid studies, the hybrid SD7${\times}$SD12 was selected and evaluated for one year comprising three major sea- sons (6 trials) of tropics viz., Pre-monsoon (characterized by high temperature, low humidity and without any rain fall), Monsoon (characterized by moderate temperature, heavy rain fall with high humidity) and post-monsoon season (characterized by low temperature and low humidity with frequent rain fall) to know the fluctuations in the larval duration. The evaluation studies indicated that the hybrid is having shorter larval duration with productive merits. The hybrid SD7${\times}$SD12 recorded survival percent of 92.74, shell weight of 46.7 cg, shell ratio % of 24.0 and filament length of 1,200 meters with a shorter larval duration of 24 hrs; when compared to productive hybrid CSR2${\times}$CSR5(control). The breeding methodologies and hybrids usefulness for tropics were discussed.

• Journal of Preventive Medicine and Public Health
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• v.46 no.6
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• pp.329-335
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• 2013

Objectives: To comprehensively examine the relationship between current sleep duration and past suicidal idea or attempt among Korean adolescents. Methods: Data came from the 2009 Korea Youth Risk Behavior Web-based Survey with 75 066 participants (with the participation rate of 97.6%) in 800 middle and high schools. Binary logistic regression was conducted by gender and depressed mood to identify significant factors for suicidal ideation/attempt. The dependent variable was the log odds of suicidal ideation/attempt, while the independent/control variables were sleep duration and other demographic, socio-economic and health-related factors. Results: A negative association between sleep duration and suicidal ideation or attempt was weaker for those with depressed mood than for those without such experience in Korea for Year 2009. The odds ratio of suicidal ideation/attempt regarding less than 4 hours of sleep compared to 6 to 7 hours of sleep, was smaller in a group with depressed mood than in a group without such experience, for example, 1.64 (95% confidence interval [CI], 1.29 to 2.08) vs. 2.06 (95% CI, 1.34 to 3.17) for men's suicidal ideation, 2.50 (95% CI, 1.69 to 3.69) vs. 3.89 (95% CI, 1.74 to 8.66) for men's suicidal attempt. A negative association between age (or self-rated health) and suicidal ideation/attempt was also weaker for those with depressed mood than for those without such experience in the nation for the year. Conclusions: There was a negative association between sleep duration and suicidal ideation/attempt in Korea for Year 2009 and this association was weaker for those with depressed mood than for those without such experience. Based on the findings of this study, adolescents' better mental health and longer, more comfortable sleep might help to prevent their suicidal ideation and attempt in Korea.

• Journal of Korean Society on Water Environment
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• v.29 no.4
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• pp.523-530
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• 2013

This study has been carried out to clarify the characteristics of discharge and pollutant loading according to flow conditions at jiseok stream watershed (JSW). A flow rate and pollutant load in the study watershed were estimated by equation of stage-discharge and discharge-loads rating curve. By using the methods above, I've evaluated the water quality (WQ) of the JSW if it is satisfied with the standard target. I've collected the data of BOD and T-P from the JSW every 8 days for the duration of 12 months. And then, I've schematized the data upon the load duration curve and the results showed me that the WQ of JSW was satisfied with the standard target. I've also collected the same data every each day for the duration of 12 months from JSW and have schematized the data again. And the results showed that it also was satisfied with the standard target. To be concluded, I've determined that point pollution sources of JSW gives more significant impacts to the WQ than non-point pollution sources of JSW and hence, as time goes, point pollution sources will keep depriciating the WQ of JSW. Therefore, further efforts will be required to JSW to maintain the WQ.

• Korean Journal of Schizophrenia Research
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• v.24 no.2
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• pp.60-67
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• 2021

Objectives: The optimal duration of maintenance treatment for patients with first-episode schizophrenia (FES) remains unclear. We examined the first antipsychotic treatment duration and its association with re-initiation of treatment using a nationwide claim database. Methods: Data from the Health Insurance Review and Assessment Service database in South Korea for 2007-2016 were used. Linear regression analysis and Cox proportional hazard models were used to evaluate the associations between the duration of the first antipsychotic treatment, time to re-initiation of treatment, and occurrence of treatment re-initiation. Results: Of 30,143 patients with FES, 80.4% (n=24,231) received <2 years of the first antipsychotic treatment. In patients who discontinued treatment (n=23,030), the rate of treatment re-initiation was 74.2% (n=17,086). As the duration of the first antipsychotic treatment increased, the time to re-initiation of treatment decreased (β=-0.146, p<0.001); however, the rate of treatment reinitiation was relatively constant (hazard ratio=1.001, p<0.001). Conclusion: Long-term antipsychotic treatment was not significantly associated with the rate of treatment re-initiation but showed a negative association with the time to re-initiation of treatment. Further research is needed to better understand the optimal treatment duration for FES.

• 한국연소학회:학술대회논문집
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• 2014.11a
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• pp.283-284
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• 2014

• Earthquakes and Structures
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• v.5 no.4
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• pp.461-475
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• 2013

A new experimental system of base-isolated structures is proposed. There are two kinds of dampers usually used in the base-isolated buildings, one is a viscous-type damper and the other is an elastic-plastic hysteretic-type damper. The base-isolated structure with a viscous damper and that with an elastic-plastic hysteretic damper are compared in this paper. The viscous damper is modeled by a mini piston and the elastic-plastic hysteretic damper is modeled by a low yield-point steel. The capacity of both dampers is determined so that the dissipated energies are equivalent at a specified deformation. When the capacity of both dampers is determined according to this criterion, it is shown that the response of the base-isolated structure with the elastic-plastic hysteretic damper is larger than that with the viscous damper. This characteristic is demonstrated through the comparison of the bound of the aspect ratio. It is shown that the bound of aspect ratio for the base-isolated structure with the elastic-plastic hysteretic damper is generally smaller than that with the viscous damper. When the base-isolated structure is subjected to long-duration input, the mechanical property of the elastic-plastic hysteretic damper deteriorates and the response of the base-isolated structure including that damper becomes larger than that with the viscous damper. The effect of this change of material properties on the response of the base-isolated structure is also investigated.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.10
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• pp.879-886
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• 2013

This study aims to provide helpful suggestions for understanding the effect of high EGR on DME HCCI combustion. This study determined which between oxygen partial pressure and oxygen concentration was the main factor affecting the LTHR heating ratio. Furthermore, EGR and the supercharging effect were investigated. To define the parameters for the EGR ratio and supercharging pressure, a numerical analysis of the chemical reaction was conducted under the following conditions: (1) variation of EGR ratio, oxygen concentration, and oxygen content; (2) variation of oxygen partial pressure while the oxygen concentration was almost constant; and (3) variation of oxygen concentration while oxygen partial pressure was constant with EGR and supercharging. The results show that an increase in EGR reduces the combustion duration. On the other hand, an increase in boost pressure increases the combustion duration. Finally, the EGR and boost pressure affect the amount of increase in LTHR.

• Journal of the Earthquake Engineering Society of Korea
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• v.9 no.3 s.43
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• pp.59-68
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• 2005

The energy-based seismic design method Is more rational in comparison with current seismic design code in that it can directly account for the effects of cumulative damage by earthquake and hysteretic behavior of the structure. However there are research results that don't reach a consensus depending on the ground motion characteristic and structural properties. For that reason in this study the influences of ground motion characteristics and structural properties on energy demands were evaluated using 100 earthquake ground motions recorded in different soil conditions, and the results obtained were compared with those of previous works. Results show that ductility ratios and sue conditions have significant influence on input energy. The results show that the ratio of hysteretic to input energy is considerably influenced by the ductility ratio, damping ratio, and strong motion duration, while the effect of site condition is insignificant.

• Journal of Mechanical Science and Technology
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• v.16 no.7
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• pp.935-941
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• 2002

This work is to investigate the combustion characteristics and flame propagation of the LPG (liquified petroleum gas) and gasoline fuel. In order to characterize the combustion processes of the fuels, the flame propagation and combustion characteristics were investigated by using a constant volume combustion chamber The flame propagation of both LPG and gasoline fuels was investigated by the laser deflection method and the high-speed Schlieren photography. The result of laser deflection method show that the error of measured flame propagation speed by laser method is less than 5% compared with the result of high-speed camera. The flame propagation speed of the fuel is increased with the decrease of initial pressure and the increase of initial temperature in the constant volume chamber. The results also show that the equivalence ratio has a grate effect on the flame speed, combustion pressure and the combustion duration of the fuel-air mixture.