• Journal of Korean society of Dental Hygiene
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• v.20 no.2
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• pp.209-220
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• 2020

Objectives: Although dental hygienists have a high employment rate as professional workers, turnover and retirement rates are very high. This study analyzed the factors related to work life of dental hygienists to prepare an alternative for life extension. Methods: From August 1 to December 31, 2019, 224 dental hygienists and 446 dental hygiene students were examined. Results: The expected working years for dental hygienists were 10-14 years (25.4%) and over 31 years (22.4%) for dental hygiene students. The recognized working years for dental hygienists were 10-14 years (22.4%) and 20-24 years (26.0%) for dental hygiene students. Work values of dental hygienists and dental hygiene students averaged 3.85 and 3.86, respectively. Furthermore, the average motive for selecting a major in dental hygienists was 3.08 points and in dental hygiene students, 3.24 points. The average career identity of dental hygienists and dental hygiene students were 2.82 and 2.91 points, respectively. Conclusions: The perception difference between dental hygienists and dental hygiene students was compared, and the factors that could play a positive role in prolonging life were identified. Based on this study, further systematic comparative studies and preparation of alternatives for life extension are required.

• Journal of Agricultural Extension & Community Development
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• v.13 no.2
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• pp.313-327
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• 2006

This study aims to examine the operating status of the Farmer's Health Center Project and the validity of its business using the benefit-cost analysis. As the pilot project of the Rural Development Adminstration from 1996, a total of 884 Farmer's Health Centers were established until 2004. Internal information of the RDA management unit was used for the analysis. A questionnaire with an interview was also performed with 70 over 468 Centers that had been established from 2001 to 2004. Results were as follows. 1) The Center was mainly used by elderly over 60 years, which took 71.4%. Winter was the most popular season for visiting. 2) Approximately 71% of the manager of the Center pointed out the deficiency of fuel cost as the most difficulty in operating the Center. 3) Users were moderately satisfied with facility and the effect of its use, which took 3.5 point over 5 scale. 4) For the cost-benefit analysis on the Centers, both 5% of social discount rate and 15 years of use term were assumed. Subsequently, the Net Present Value was 3,134 million won, which certified the validity of the business.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.2
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• pp.221-228
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• 1989

The objective of this paper is to develop a numerical technique for analyzing crack driving forces in multi-phase materials. The analysis was based on finite element method coupled with a virtual crack extension technique which is known as the most efficient tool in computational fracture mechanics analysis. The modified J-integral method, proposed by Miyamoto and Kikuchi for the analysis of dual-phase material was carried out by subtracting the J-values for contours surrounding each phase boundary from the J-values for overall contour. It was shown that the proposed numerical procedure, based on the modified J-integral coupled with a virtual crack extension technique, can be used as an effective numerical tool for determining crack driving forces in multi-phase materials.

• International Journal of Aeronautical and Space Sciences
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• v.12 no.4
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• pp.305-317
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• 2011

This paper presents an overview on flutter boundary prediction in tests which is principally based on a system stability measure, named Jury's stability criterion, defined in the discrete-time domain, accompanied with the use of autoregressive moving-average (AR-MA) representation of a sampled sequence of wing responses excited by continuous air turbulences. Stability parameters applicable to two-, three- and multi-mode systems, that is, the flutter margin for discrete-time systems derived from Jury's criterion are also described. Actual applications of these measures to flutter tests performed in subsonic, transonic and supersonic wind tunnels, not only stationary flutter tests but also a nonstationary one in which the dynamic pressure increased in a fixed rate, are presented. An extension of the concept of nonstationary process approach to an analysis of flutter prediction of a morphing wing for which the instability takes place during the process of structural morphing will also be mentioned. Another extension of analytical approach to a multi-mode aeroelastic system is presented, too. Comparisons between the prediction based on the digital techniques mentioned above and the traditional damping method are given. A future possible application of the system stability approach to flight test will be finally discussed.

• Transactions of Materials Processing
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• v.20 no.4
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• pp.296-302
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• 2011

The objective of this paper is to determine the effect of process parameters on the behavior of a 18Cr-10Mn-$0.44N_2$ nitrogen steel sample deformed by hot rolling. Compression tests were carried out at high temperatures to determine the flow stresses needed for a finite element(FE) analysis. The strain rate, ranging from 0.1 to $1.0s^{-1}$, significantly affected the flow stress at temperatures higher than $1,000^{\circ}C$. Non-isothermal rolling simulations and laboratory rolling tests were performed with plate specimens 14.5mm thick, 135mm wide and 226mm long. A rolling reduction of 15% per pass leading to a cumulative rolling reduction of 60% was determined as optimal. The extension ratio of 176.5% in the length direction was about 30.4 times greater than the extension ratio of 5.8% in the width direction. Isotropic properties for tensile strength, microstructure and grain size were measured after mock-up hot rolling tests. The results from the mockup tests were found to be in good agreement with those of the simulations.

• Fashion & Textile Research Journal
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• v.2 no.3
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• pp.227-233
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• 2000

The purpose of this study was to develop the High Functional Covering machine and the Compound Twister to produce the high value added textile goods and to meet the consumer's needs. For the study, 8 yarns and 12 fabrics were made with two developed machines and the tensile characteristics of the samples were tested and analysed. The result indicated that the sample fabrics kept their elongation regardless of buffering process. Elongation of the sample yarns was higher than those of yarns made with a traditional covering method. Elastic recovery of the sample fabrics was more effected by the recovery rate than by the number of extension and the characteristics of the sample yarns and fabrics were comparable to the yarns and fabrics made with a traditional covering method in terms of the position of Spandex yarns in their yarn structure and buffering effect.

• Journal of Agricultural Extension & Community Development
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• v.18 no.3
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• pp.569-590
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• 2011

The purpose of this study is to examine the local farmers' perceptions toward the use of local food for school meals from the suppliers' perspectives. Data was collected from 12 school-meal management centers which provide the name list of local farmers. from the provided list, 167 people were selected, who were asked to answer the self-administerd questionnaires by post. 87 responses were returned, having shown the response rate was 50.1%. The data were analyzed by using SPSS 15.0 for descriptive analysis. The findings from this study are as follows: First, the local farmers has a positive attitude toward certified and supply methods for local food whereas price and selling quantity of local food were dissatisfying; Second, local farmers prefer to use public supplying chains such as school-meal support centers rather than private ones. Furthermore, they like to directly contact with a school in terms of supplying local food. To establish self-selling systems, computer programs like ERP should be adopted to effectively manage the production process of local food. On conclusion, implications and limitations were discussed.

• Journal of Agricultural Extension & Community Development
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• v.18 no.4
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• pp.861-877
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• 2011

The purpose of this study is to survey job stress and Musculoskeletal Disorder(MSDs) of workers in small plants with agricultural products. The subjects were comprised of 69 workers participated in "Helping the rural women to get the small businesses" project. The questionnaire surveys were Korean Occupational Stress Scale(KOSS), and Legal Risk Assessment of Musculoskeletal Disorders(KOSHA CODE H-30-2003). As a result of the survey, scores of KOSS 8 sub-items except for job demand were similar to that of Korea workers. Prevalence of MSDs symptoms of small plants workers was high percent (44.9%). And the rate according to kinds of product was significant difference at neck (p<0.01), lumbar (p<0.01), and leg (p<0.01). There was no significant difference between view person sign of MSDs and non MSDs according to sex, year, the number of workers, working years, working time per one day, rest time per one day, and subjective working intensity, but there were significant difference between high stress group and low stress group about MSDs at interpersonal conflict(p<0.05). Job stress and MSDs were important factor to workers of small plants producted agricultural products. Therefore, starting a business with small plats, workers consider interpersonal conflict and body part showing MSDs.

• Journal of Periodontal and Implant Science
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• v.27 no.3
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• pp.549-559
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• 1997

The purpose of this study was to evaluate clinical changes in graft size after treatment with strip gingival autograft in human. 57 premolar teeth in 27 patients having the following mucogingival problems were selected. The width of extension, attached gingiva including free marginal gingiva, width of transplant and clinical sulcus depth were measured at the initial examination, 2, 12 and 24 weeks following the strip gingival autograft and free gingival autograft. The change of width of extension, attached gingiva including free marginal gingiva, width of transplant and clinical sulcus depth according to healing process in both graft procedures was statistically analyzed by repeated measure ANOVA test and independent t-test using SPSS program. The results were as follows : 1. The change of keratinized gingiva in both graft procedures was increased significantly at 24 weeks post-op. 2. The clinical sulcus depth exhibited no marked changes throughout the entire investigation in both graft procedures. 3. No dimensional variation was seen in graft size in both graft procedures. 4. Shrinkage did not differ significantly in both graft procedures. From the day of grafting to 24 weeks after surgery the percentages of shrinkage were : strip gingival autograft 28% and free gingival autograft 29%.

• Journal of Korean Physical Therapy Science
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• v.9 no.4
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• pp.35-44
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• 2002

The purpose of this study was to compare the effect of heat therapy, stretching exercise and to verify which method was most effective for lumbar flexibility improvement. Subjects were 20 apparantly healthy person(male10, female10) who did not have any medical problem. They were randomly divided and assigned into 2 groups: heat therapy, stretching exercise. For testing flexibility, trunk flexion, bunk extension, and Schober-test were performed. Pre-test was done prior to the each group's treatment. Test was done at 2nd week, 4th week and 6th week. There were no significant difference in improvement of trunk flexion and trunk extension after 6 weeks treatment among 2 methods. However in all 2 groups, there were statically significant improvement in flexibility as time go on. The rate of improvement was highest at 2nd week, while this was attenuated afterwards. The Schober-test score changed significantly from pre-test to the mid-test and to the post-test, while there were no significant difference among 2 methods of treatment. With the results above, it was concluded that heat therapy, stretching-exercise were all effective for improving flexibility without any significant priorities.