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스컬용융법에 의한 패각을 이용한 큐빅지르코니아 단결정 성장
정진화,연석주,석정원,Jung, Jin-Hwa,Yon, Seog-Joo,Seok, Jeong-Won 한국결정성장학회 2013 韓國結晶成長學會誌 Vol.23 No.3
In this research, cubic zirconia is synthesized with a refined CaO from shells as a stabilizer through Skull melting method. The proper process time and concentration are defined by Hydration reaction to produce the refined CaO after two different treatments using 0.1 mol% of HCl respectively with Cockle shell. The highest purity of CaO is reached when the shell is immersed in 1 mol% HCl. In Hydration reaction step, the pure $Ca(OH)_2$ is produced at $45^{\circ}C$ for 24 hours. The highest purity of CaO is measured when the $Ca(OH)_2$ is treated by heat at $1200^{\circ}C$ for 5 hours. The single crystals are grown through Skull melting method by adding the different contents of the refined CaO from 10 mol% to 30 mol% into $ZrO_2$. The frequency of High-frequency oscillator used for Skull melting method is 3.4 MHz. The descending speed of the single crystal is 3 mm/hour. The grown length of the single crystal is 4 cm. As a result of this study, 15 mol% of CaO has the best crystallinity. 본 연구에서는 안정화제로, 패각으로부터 정제한 CaO를 사용하여 Skull melting법으로 큐빅 지르코니아를 성장시켰다. 꼬막 패각을 HCl을 0.1~1 mol%로 1차 처리한 후 수화반응을 거쳐 최적의 처리시간과 농도를 검토하였다. HCl을 1 mol%의 농도로 처리했을 때 가장 순도가 높았으며 수화반응시 $45^{\circ}C$의 온도로 24시간 동안 반응시킬 때 완전한 $Ca(OH)_2$ 를 얻을 수 있었다. $Ca(OH)_2$를 $1200^{\circ}C$에서 5시간 처리하였을 때 CaO의 순도가 가장 높게 측정되었다. 패각으로부터 얻어진 CaO를 $ZrO_2$에 첨가하여 함량을 10~30 mol% 로 변화시켜 Skull melting법으로 단결정을 성장시켰다. Skull melting법에 사용된 고주파 발진기의 주파수는 약 3.4 MHz이며 단결정의 하강속도는 시간당 3 mm로 4 cm 길이로 성장시켰다. 실험결과 CaO의 함량이 15 mol% 일 때 결정성이 가장 우수했다.
치료적 승마가 뇌성마비의 체간 고유수용성, 안정성 및 자세에 미치는 영향
정진화,유재호,Jung, Jin-Hwa,Yu, Jae-Ho 대한물리치료학회 2010 대한물리치료학회지 Vol.22 No.5
Purpose: In this study, children with cerebral palsy were treated for 8 weeks using horse riding trunk proprioception, stability and posture to investigate the effect of hippotherapy in the field of physical therapy. Methods: A total of 18 subjects were divided into an experimental group treated by horseback riding and a control group. Both groups were evaluated pre- and post-treatment. Trunk proprioception was measured three times in the sitting position with their eyes and ears closed to reach the target position the angle error of the mean was calculated. Trunk stability was measured using a forceplate and the data were used to calculate the postural sway path & postural sway velocity. Posture was evaluated using the Posture Assessment Scale (PAS). Results: After hippotherapy, the experimental group showed a significant improvement in trunk proprioception, stability and posture (p<0.05), but the control group improved in posture only (p<0.05). Trunk proprioception, stability and posture was significantly different between the two groups (p<0.05). Conclusion: Eight weeks of hippotherapy is effective in improving trunk proprioception, stability, and posture. Research using this therapy should be studied further as a possible new therapeutic approach in the field of physical therapy.
정진화 ( Jin Hwa Jung ),노재선 ( Jae Sun Roh ),조현정 ( Hyeon Jung Cho ) 한국농업경제학회 2013 農業經濟硏究 Vol.54 No.2
This paper scrutinizes the aging phenomenon of farm households in South Korea with a focus on its effect on household income. We investigate the characteristics of aging farm households in terms of the size and composition of household income. We also investigate the nexus between aging and income polarization. Census of Agriculture, Forestry and Fisheries (2000, 2010) and Farm Household Economy Survey (2003~2010) data are applied. The major findings are as follows. First, with the rapid aging of Korean farm households, old-age households tend to be occupied by petty farmers who cultivate paddy fields. Second, old-age farm households earn much less farm income-both total income and income per 10a-than middle-aged farm households. Third, old-age farm households earn low average household income with extensive income polarization. A gap in non-farm income chiefly contributes to polarization. The findings suggest a need for a customized strategy designed to enhance the overall productivity of old-age farmers while securing the income of low-income older-age farm households.
정진화 ( Jin Hwa Jung ),김새봄 ( Sae Bom Kim ) 한국농업경제학회 2015 農業經濟硏究 Vol.56 No.4
This study examined the determining factors of the return-to-farm decision and the return types of returning farmers in South Korea. The data were collected from returning farmers and potential returnees through on-line and off-line surveys and analyzed using binary and multinomial logit analyses. The return-to-farm decision was found to be affected by the factors such as urban residents’ age, educational and occupational backgrounds, spouses’ support (being accompanied by spouse), the motive of and the expected costs required for rural immigration; the effect of each factor was found to vary for differing return types. The results of the present study suggest that, in order to promote urban-to-rural migration for farming, policy measures should effectively address the various needs of potential returning farmers who have different characteristics.
귀농인 정착의 장애요인과 대응전략 : 경북 영천과 충남 청양 귀농인을 중심으로
정진화(Jin Hwa Jung),노재선(Jae-Sun Roh),박형호(Hyungho Park),임동근(DongGeun Lim),김다울(Dawool Kim) 한국농식품정책학회 2015 농업경영정책연구 Vol.42 No.4
Returning farmers mostly go through an arduous course of settlement in terms of re-adapting themselves to farming activities and rural environment. The obstacles encountered in settlement may differ according to the diverse types of returning farmers. This paper classifies returning farmers by years after migration, income level, and crop type to investigate the obstacles and countermeasures in the settlement process by the features of returning farmers. The survey data of 207 returning farmers and in-depth interviews with seven returning farmer households are analyzed. With low income as a common hindrance, clear differences are established with regard to major obstacles for different types of returning farmers. Recommended strategies to overcome such obstacles include active but prudent investment, enhancement of returning farmers’ farming capability, participation in producers’ cooperatives, and securement of nonfarm income activities.
정진화(Jin Hwa Jung),김새봄(Sae Bom Kim) 한국농업경제학회 2018 農業經濟硏究 Vol.59 No.3
The present study analyzes the factors that determine the likelihood of being beneficiaries of policy support for urban-to-rural migrant farmers and the effect of such policy support on beneficiaries’ agricultural income. The data were drawn from 2016 National Survey of Urban-to-Rural Migration (Ministry of Agriculture, Food and Rural Affairs), while the policy effect was estimated using the matching method. The empirical results indicate that urban-to-rural migrant farmers aged under 50 years old and those who participated in return-to-farm education programs are more likely to take advantage of policy supports rendered by both the central government and local governments. Furthermore, migrant farmer’s household type, main crop type, and multi-cropping also influence the likelihood of receiving selective policy supports. Depending on specific policies, the central or local government policies increase the beneficiaries’ annual agricultural income by 32 to 89 percent, suggesting a substantial contribution of these policies to the increase in agricultural income of urban-to-rural migrant farmers.
승마운동이 뇌성마비 아동의 자세동요, 체간 근지구력 및 장악력에 미치는 영향
정진화(Jung Jin-Hwa),이병희(Lee Byung-Hee),유재호(Yu Jae-Ho) 한국체육과학회 2010 한국체육과학회지 Vol.19 No.3
Rehabilitation of children with cerebral palsy(CP) who demonstrated the therapeutic effects of horseback riding and sitting balance(postural sway path and velocity), muscle endurance(sit-up test) and grip strength(dynamometer) of the subjects to examine whether any changes should bring. 18 subjects with CP participated in this study. The hippo therapy group 9 subjects received conventional rehabilitation therapy and Horse Riding, and the non-hippo therapy 9 subjects only received conventional rehabilitation therapy. In this study, the average difference between the treatment groups before and after study by the Wilcoxon rank test, the average difference between groups was evaluated by the Mann-Whitney test. In results, postural sway path and velocity in the medial-lateral(ML) and anteriorposterior(AP) were increased significantly difference(p<.05). Also hippotherapy improved muscle endurance and dominant hand grip(p<.01). 8 weeks hippo therapy of children with cerebral palsy is found to be effective in balance, muscle endurance and grip strength. In future hippo therapy research, considering the subject number, characteristics and horse riding period can make more precise results. And it will be needed more research about hippo therapy.