• Resources Recycling
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• v.15 no.1 s.69
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• pp.20-27
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• 2006

PVC is the thermoplastic offering excellent material properties. PVC has been used in wide variety of applications, however, it causes environmental problems when it is discarded because of its high chlorine content. Since dechlorination reaction of PVC is taking place at relatively low temperature compared to the pyrolysis temperature of plastics, study on the dechlorination reaction has been carried out as a pre-treatment process. Twin screw reactor which shows excellent mixing capabilities is employed. Experimental variables are the first and second reactor temperature, PVC content in mixed plastics, viscosity of mixed plastics, feeding rate, rotational speed or the second reactor. Over $90\%$ of dechlorination ratio can be obtained under proper operation conditions. Chlorine gas evolved from reactor is absorbed in water and can be recovered as a hydrochloric acid. Analysis had been done on chlorine flows by taking material balance over realtor.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2005.10a
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• pp.83-96
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• 2005

PVC is the thermoplastic offering excellent material properties. PVC is used in wide variety of applications, however, it causes environmental problems when it is discarded because of its high chlorine content. Since dechlorination reaction of PVC is taking place relatively low temperature compared to the pyrolysis temperature of plastics, study on the dechlorination reaction has been carried out as a pre-treatment process. Twin screw reactor which shows excellent mixing capabilities is employed. Experimental variables are first and second reactor temperature, PVC content in mixed plastics, viscosity of mixed plastics, feeding rate, rotational speed of the second reactor. Over 90% of dechlorination rate can be obtained under proper operation conditions. Chlorine gas evolved from reactor is absorbed in water and can be recovered as a hydrochloric acid. Analysis had been done on chlorine flows by taking material balance over reactor.

• Journal of Korean Clinical Nursing Research
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• v.15 no.2
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• pp.91-102
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• 2009

Purpose: This study was done to examine the effect of a urinary incontinence management program on physical symptoms, daily life problems, and sexual life problems for women with mixed urinary incontinence. Methods: This study was conducted using a one group pre-test and post-test design. For the survey, 28 women having mixed urinary incontinence were chosen by convenience sampling and agreed to participate in this study. Their physical symptoms (urinary symptoms, maximum vaginal contraction pressure, and duration of vaginal contraction), daily life problems, and sexual life problems were measured. For descriptive statistics and Wilcoxon signed-rank test were used with SPSS Win 14.0. Results: There were statistically significant differences in the mean scores of physical symptoms (urinary symptoms and maximum vaginal contraction pressure), daily life problems, and sexual life problems. Conclusion: This urinary incontinence management program showed improvements in physical symptoms, daily life, and sexual life of women in the sample. The study results indicate that for effective urinary incontinence management programs nurses should recognize the importance of continual treatment and also develop coping strategies that have sensitivity and are appropriate for patients' daily and sexual problems.

• Geomechanics and Engineering
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• v.29 no.5
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• pp.567-582
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• 2022

In the present study, a series of physical experiments and numerical simulations were conducted to investigate the effects of mode I and mixed-mode I/II cracks on the fracture modes and stability of roadway tunnel models. The experiments and simulations incorporated different inclination angle flaws under both static and dynamic loads. The quasi-static and dynamic testing were conducted by using an electro-hydraulic servo control device and drop weight impact system (DWIS), and the failure process was simulated by using rock failure process analysis (RFPA) and AUTODYN software. The stress intensity factor was also calculated to evaluate the stability of the flawed roadway tunnel models by using ABAQUS software. According to comparisons between the test and numerical results, it is observed that for flawed roadways with a single radical crack and inclination angle of 45°, the static and dynamic stability are the lowest relative to other angles of fractured rock masses. For mixed-mode I/II cracks in flawed roadway tunnel models under dynamic loading, a wing crack is produced and the pre-existing cracks increase the stress concentration factor in the right part of the specimen, but this factor will not be larger than the maximum principal stress region in the roadway tunnel models. Additionally, damage to the sidewalls will be involved in the flawed roadway tunnel models under static loads.

• Journal of the Korean Chemical Society
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• v.65 no.5
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• pp.333-346
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• 2021

In this study, we developed education materials using history of science related to the experiment of 'Boyle's air pump' and the Boyle and Hobbs' debate of vacuum to find out the perceptions of NOS by pre-service chemistry teachers. For the study, 29 pre-service chemistry teachers at a college of education in Chungcheongbuk-do were selected. As RFN items that were related to the contextual situation developed in this study, items in the categories of 'Aims and Values', 'Scientific practices', 'Scientific Methods among Educational Applications' and 'Social-Institutional Aspects among Educational Applications' were selected. Through the items of RFN, the perceptions of pre-service teachers in non-contextual situations were investigated. Then we presented the pre-service teachers with the situation related to Boyle's experiment on air pump and Boyle and Hobbes' debate over vacuum. In addition, their perception of NOS was examined in contextual situations related to RFN items. Responses to the items, experimental results related to Boyle's Law, group discussion, and interview data were collected as data. As a result of the study, it was found that pre-service teachers had informed perceptions in most of the items, but cases with naive views or mixed views were found in context experimental situations. This study can contribute to the NOS education for pre-service chemistry teachers by development of context situation education materials related to NOS and by finding out their perceptions in the non-contextual and contextual situation.

• Safety and Health at Work
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• v.9 no.2
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• pp.172-179
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• 2018

Background: Insufficient training in infection control and occupational health among healthcare workers (HCWs) in countries with high human immunodeficiency virus (HIV) and tuberculosis (TB) burdens requires attention. We examined the effectiveness of a 1-year Certificate Program in Occupational Health and Infection Control conducted in Free State Province, South Africa in an international partnership to empower HCWs to become change agents to promote workplace-based HIV and TB prevention. Methods: Questionnaires assessing reactions to the program and Knowledge, Attitudes, Skills, and Practices were collected pre-, mid-, and postprogram. Individual interviews, group project evaluations, and participant observation were also conducted. Quantitative data were analyzed using Wilcoxon signed-rank test. Qualitative data were thematically coded and analyzed using the Kirkpatrick framework. Results: Participants recruited (n = 32) were mostly female (81%) and nurses (56%). Pre-to-post-program mean scores improved in knowledge (+12%, p = 0.002) and skills/practices (+14%, p = 0.002). Preprogram attitude scores were high but did not change. Participants felt empowered and demonstrated attitudinal improvements regarding HIV, TB, infection control, and occupational health. Successful projects were indeed implemented. However, participants encountered considerable difficulties in trying to sustain improvement, due largely to lack of pre-existing knowledge and experience, combined with inadequate staffing and insufficient management support. Conclusion: Training is essential to strengthen HCWs' occupational health and infection control knowledge, attitudes, skills, and practices, and workplace-based training programs such as this can yield impressive results. However, the considerable mentorship resources required for such programs and the substantial infrastructural supports needed for implementation and sustainability of improvements in settings without pre-existing experience in such endeavors should not be underestimated.

• Food Science and Preservation
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• v.11 no.1
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• pp.17-21
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• 2004

The antimicrobial effect of mixed solution of botanical antimicrobial agent-citrus product (BAAC) and such a natural additive as aloe, ginseng or Prunus mume extract on the spoilage microorganisms of soybean sprouts were investigated by paper disk method. The mixture (BAAG) of BAAC and ginseng extract showed the remarkable antimicrobial activity in the result of the experiment. Therefore, we used BAAG as pre-soaking and cultivating solution of soybean sprouts. Total bacterial and Escherichia coli cell count of soybean sprouts pre-soaked and cultivated in the BAAG-diluted solution (50 ppm) showed 2.5 ${\times}$ 10 CFU/mL and 1.3 ${\times}$ 10 cfu/mL in comparison with 3.5 ${\times}$ 10$^3$ cfu/mL and 5.8 ${\times}$ 10$^3$ cfu/mL of the control, respectively. BAAG-treated soybean sprouts also showed no slimy brown product and undesirable odor characterized in the control. It was confirmed that BAAG could be a proper pre-soaking and cultivating solution of soybean sprouts.

• The Journal of the Convergence on Culture Technology
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• v.8 no.5
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• pp.423-429
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• 2022

This study is a study on the perceptions of pre-primary early childhood teachers on teaching and learning methods for infants and toddlers in the early childhood teacher training process. This is a mixed study using word cloud analysis and qualitative case analysis on the subject, focusing on literature research and understanding of pre-primary early childhood teachers' 'teaching and learning methods for infants and toddlers'. The purpose of this study was to find out the meaning of a early childhood teacher through thoughts on teaching and learning methods for infants, difficulties, points to be learned, teaching competency to be good as a teacher, and experiences for teaching professionalism. Through the results of this study, it is expected to find a way to increase their sense of efficacy on teaching and learning methods when conducting classes for young children in the future, and to provide basic data for improving the quality of early childhood education.

• The Korean Journal of Pesticide Science
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• v.15 no.3
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• pp.269-277
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• 2011

Recent outbreak of new diseases and pests which were introduced from abroad, seriously hampered both quality and safety of paprika fruits. This study has been carried out to aid an establishment of guideline for safe use of pesticides and reduction of their residues on paprika. Systemic fungicides boscalid and pyraclostrobin of either mixed (a.i.; 13.6+6.8%) or single (a.i.; 47 and 18.8%, respectively) water dispersible granule formulation(WG) products were sprayed with recommended or double dosage on paprika grown in green house at March and June. To draw pre-harvest residue limit, residues of each fungicide were analyzed from fruits collected eight times from 18 to 1 day pre-harvest. The biological half-lives of both boscalid and pyraclostrobin in mixed formulation in March and June were slightly shorter than those of single formulation which ranged from 14.4 to 20.1 days. Residue levels of both fungicides of single formulation in fruits in June were about one lower compared to those in March. However, application of double dosage frequently exceeded MRLs from fruits grown both seasons. These results showed that residue levels on fruits persisted longer period of time, more than two weeks, and so the case applied in winter season. The dissipation of fungicides on leaves and fruits was compared. The distribution of both fungicides in leaves was 20-200 times higher than that of fruits and persisted up to 18 days of pre-harvest period at the concentration of 10-40 ${\mu}g\;g^{-1}$. This study indicated that the mixed formulation product exhibited low residues in fruits, but high and long enough to pathogen growth in leaves.

• Journal of The Korean Association For Science Education
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• v.31 no.6
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• pp.887-900
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• 2011

Teachers use explanations to communicate important scientific ideas to students. Consequently, all biology teachers should be evaluated to determine how effective they are at constructing and communicating biological explanations. Open response questions are required to detect pre-service biology teachers' abilities to communicate robust and accurate scientific explanations. Nevertheless, multiple-choice questions are typically preferred by educators because of the common drawbacks of using open-response instruments, such as scoring time, inter-rater scoring disagreements, and delayed feedback to test takers. This study aims to measure pre-service biology teachers' competence in building scientific explanations and to investigate how accurately multiple-choice questions predict the results of open-response questions. One hundred twenty four pre-service biology teachers participated in the study and were administered 20 multiple-choice items and three open-response items designed to measure the accuracy and quality of their explanations of evolutionary change. The results demonstrated that pre-service teachers displayed higher competence when tested with multiple choice items than when tested with open response items. Moreover, scores derived from multiple-choice items poorly predicted the scores derived from open-response items. Multiple-choice items were also found to be poor measures of the consistency, purity and abundance of conceptual elements in teachers' evolutionary explanations. Additionally, many teachers held mixed-models composed of both scientific and naive ideas, which were difficult to detect using multiple-choice formats. Overall, the study indicates that multiple-choice formats are poorly suited to measuring several aspects of biology teachers' knowledge of evolution, including their ability to generate scientific explanations. This study suggests that open-response items should be used in teacher education programs to assess pre-service teachers' explanatory competency prior to being permitted to teach science to children.