• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.308-308
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• 2007

리륨이차전지의 용량의 증가를 위한 연구에 많은 노력과 재원이 투자되고 잇는 반면에, 용량과 성능증가 추세가 주춤한 최근에는 전지의 안전성에 큰 관심이 집중되고 있다. 그 이유는 전지의 성능 못지않게 안전성에 대한 의구심이 꾸준히 제기되고 있고, 대용량 고출력전지의 대표적인 예이 자동차용 전지에는 안전성에 대한 보장이 선결되어야 하기 때문이다. 본 연구에서는 유기 전해액의 발화 및 폭발을 방지할수 있는 방법 중에서 첨가제에 의한 방법을 이용하여 그 첨가제의 전기화학적 특성 및 열적 안정성을 살펴보고 리튬이온전지에의 적용 가능성을 알아보았다. 특히 포스파젠 화합물들을 소량(1~5wt.%)첨가하여, 양극소재의 발열온도를 $60^{\circ}C$ 이상 지연시키고, 사이클 특성의 향상 및 용량의 증가도 실현함으로서 포스파젠 화합물의 유효성을 증명하였다. 아래의 Fig1은 Hexamethoxy cyclo tri-phosphazene(HMTP) 이라는 화합물의 난연성을 표기한 것인데, $270^{\circ}C$ 부근의 background peak가 $340^{\circ}C$까지 지연됨을 보여주고 있다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.593-594
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• 2005

Lithium-ion batteries have used the layered $LiCoO_2$ materials as cathodes, but Co is relatively toxic and expensive. In this regard, the spinel $LiMn_2O_4$ has become appealing because manganese is inexpensive and environmentally benign. In general, cathodes for lithium ion batteries include carbon as a conductive agent that provides electron transfer between the active material and the current collector. In this work, we selected Acetylene Black and Super P Black as conducting agents, and then carried out comparative investigation for the performances of the cells using different conducting agents with different particle size. As a consequence, Li/$LiMn_2O_4$ cells with Super P Black show better electrochemical performances than those with Acetylene Black.

• PNF and Movement
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• v.19 no.3
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• pp.383-390
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• 2021

Purpose: The purpose of this study was to compare the effects of scrambler and transcutaneous electrical nerve stimulation therapy on pain, functional disability, and depression in patients with chronic low back pain. Methods: Twenty patients with chronic stroke were assigned randomly to an experimental (n=10) or control (n=10) group. The experimental group performed scrambler therapy. The control group performed electrical nerve stimulation therapy. Training was conducted once a day for 30 minutes, five days per week, for three weeks. The pain was measured using the numeric rating scale. Functional disability was measured using the Roland-Morris disability questionnaire. Depression was measured using the Beck depression inventory. Results: As a result of comparison between the groups, the experimental and control groups showed significant difference for pain, functional disability and depression after the experiment (p<0.05). In a comparison between the two groups, the experimental group, in which scrambler therapy was applied, showed a more significant reduction in pain, functional disability and depression than the control group (p<0.05). Conclusion: Based on these results, scrambler therapy shows positive effects on pain, functional disability, and depression in patients with chronic low back pain.

• The Journal of Korean Physical Therapy
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• v.31 no.2
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• pp.82-87
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• 2019

Purpose: The purpose of this study was to examine the effects of plank exercises with resistance of one-sided hip adduction on abdominal muscle thickness. Methods: Thirty subjects were divided into a group that underwent plank exercises with one-sided hip adduction resistance (n=15) and a group that underwent plank exercises only (n=15). Their changes in abdominal muscle thickness before the experiment (n=15) and three and six weeks after the experiment were analyzed using a two-way repeated analysis of variance at a statistical significance level of ${\alpha}=0.05$. When there was any interaction between the time of measurement and each group, post hoc t-tests were conducted at a statistical significance level of ${\alpha}=0.01$. Results: The results of the experiment showed statistically significant differences in the thickness of the rectus abdominis, internal oblique muscle, and transversus abdominis, depending on the time of measurement and the interaction between the time of measurement and each group (p<0.05). Statistically significant differences were observed in the thickness of the external oblique, depending on the time of measurement, the interaction between the time of measurement and each group, and variances between the groups (p<0.05). Conclusion: The results of this study indicated that plank exercises with resistance of one-sided adduction are effective for increasing abdominal muscle thickness. The study's overall findings will likely be used as basic data for lumbar stabilization exercises and rehabilitation treatment.

• PNF and Movement
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• v.19 no.2
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• pp.173-182
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• 2021

Purpose: The purpose of this study was to compare the effects of underwater and ground-based diagonal pattern exercises on the balance confidence and respiratory functions of chronic stroke patients. Methods: Thirty chronic stroke patients were assigned randomly to an experimental (n = 15) or control (n = 15) group. The experimental group performed an underwater diagonal pattern exercise. The control group performed a ground-based diagonal pattern exercise. Training was conducted once a day for 30 minutes, five days per week for six weeks. Balance confidence was measured using the Activities-Specific Balance Confidence Scale-Korea version. Respiratory function was measured using a spirometer. Results: In a comparison within groups, the experimental and control groups showed significant differences in balance confidence after the experiment (p < 0.05). In a comparison between the two groups, the experimental group showed a more significant difference in balance confidence than the control group (p < 0.05). In a comparison within groups, the experimental group showed a significant difference in respiratory functions after the experiment (p < 0.05). In a comparison between the two groups, the experimental group showed a more significant difference in respiratory functions than the control group (p < 0.05). Conclusion: Based on these results, underwater diagonal pattern exercises effectively improved the balance confidence and respiratory functions of chronic stroke patients.

• Transactions of the Korean hydrogen and new energy society
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• v.32 no.6
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• pp.477-482
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• 2021

Hydrogen production, hydrogen production cost, and utilization rate were calculated assuming four cases of hydrogen production system in combination of photovoltaic power generation (PV), water electrolysis system (WE), battery energy storage system (BESS), and power grid. In the case of using the PV and WE in direct connection, the smaller the capacity of the WE, the higher the capacity factor rate and the lower the hydrogen production cost. When PV and WE are directly connected, hydrogen production occurs intermittently according to time zones and seasons. In addition to the connection of PV and WE, if BESS and power grid connection are added, the capacity factor of WE can be 100%, and stable hydrogen production is possible. If BESS is additionally installed, hydrogen production cost increases due to increase in Capital Expenditures, and Operating Expenditure also increases slightly due to charging and discharging loss. Even in a hydrogen production system that connects PV and WE, linking with power grid is advantageous in terms of stable hydrogen production and improvement of capacity factor.

• Journal of Korean society of Dental Hygiene
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• v.21 no.6
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• pp.685-693
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• 2021

Objectives: The purpose of this study was to identify dentists' perception of work performance and scope of work of dental hygienists. Methods: A phenomenological research method was applied for the proper role performance on March 1st, 2021 and June 10th to investigation eight dentists running their own dental clinics located in Gwangju and Daejeon metropolitan city. Results: The legal scope of dental hygienists has not been properly recognized. Conflicts have been experienced due to problems between dental hygienists and staff and their differences in knowledge or proficiency in their work. The performance of dental hygienists has been evaluated based on the size of the dental clinic's profit. Reviews and improvements in dental hygienists' scope of work and new business regulations are required. Conclusions: Consequently, it is recommended that the dental business industry carry out directional discussions and negotiations to review dental hygienists' scope of practice and bring improvements so that their work can be, in the end, be stably performed within the legal system.

• Journal of Korean Physical Therapy Science
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• v.29 no.2
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• pp.48-56
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• 2022

Background: This study was to identify the effects of blood flow restriction on gluteus muscles thickness, density, and white area index for children with cerebral palsy. Design: Randomized controlled trial. Methods: Twenty children with cerebral palsy were assigned randomly to an experimental (n=10) or control (n=10) group. The experimental group performed a bicycle exercise after blood flow restriction. The control group performed a bicycle exercise. The study used an ultrasonic instrument to measure gluteus muscles thickness, density, and WAI. Wilcoxon signed ranks test was used for determination of differences before and after treatment, and a Mannn-whitney U test was used for determination of differences between treatment groups. Results: As a result of comparison within groups, the experimental and control group showed significant difference for gluteus muscles thickness, density, and WAI after the experiment (p<0.05). In comparison between two groups, the experimental group showed more significant difference in gluteus muscles thickness, density, and WAI than the control group (p<0.05). Conclusion: Based on these results, a bicycle exercise after blood flow restriction effectively improved the gluteus muscles thickness, density, and WAI of children with cerebral palsy.

• Journal of Korean Biological Nursing Science
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• v.24 no.2
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• pp.113-121
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• 2022

Purpose: The purpose of this study was to identify influence of health behavior in patients with coronary artery disease. Methods: A cross-sectional descriptive design included 150 patients treated with percutaneous coronary intervention in S hospital in S city. Data were collected by using self-questionnaires July 5-August 26, 2021 and were analyzed by descriptive statistics, t-test, ANOVA, Scheffé test, Pearson's correlation coefficients, and multiple regression with SPSS 23.0. Results: Factors significantly influencing health behavior in patients with coronary artery disease were health empowerment (β = .48, p< .001), and post-traumatic growth (β = .20, p= .013). The explanatory power of related variables was 39%. Conclusion: Based on the this study, it was found that health empowerment and post-traumatic growth had a significant effect on the health behavior of patients with coronary artery disease. Thus, it is necessary to promote the health behavior of patients with coronary artery disease through the development of intervention programs to improve health empowerment and post-traumatic growth.

• PNF and Movement
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• v.19 no.3
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• pp.311-319
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• 2021

Purpose: The study examined the effects of the proprioceptive neuromuscular facilitation pattern exercise and protein intake on balance, gait ability, and lower extremity muscular strength for sarcopenia in the elderly. Methods: A total of 30 elderly people (65~74years) with sarcopenia were recruited and randomized to Group I (n=10), Group II (n=10), and Group III (n=10). Their balance ability was measured using the functional reach test. Group I performed the proprioceptive neuromuscular facilitation pattern exercise and protein intake. Group II performed the proprioceptive neuromuscular facilitation pattern exercise. Group III performed protein intake. Their gait ability was measured using the Timed Up and Go test. Lower extremity muscular strength was measured using the Five Times Sit to Stand test. Results: As a result of comparison within groups, Group I and Group II showed a significant difference in balance, gait, and lower extremity muscular strength after the experiment (p<0.05), and Group I showed a more effectively significant difference than either Group II or Group III in balance, gait, and lower extremity muscular strength before and after the experiment (p<0.05). Conclusion: This study showed that the proprioceptive neuromuscular facilitation patterns exercise and protein intake was effective in balance, gait ability, and lower extremity muscular strength for sarcopenia in the elderly.