• Journal of Pharmaceutical Investigation
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• v.39 no.3
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• pp.167-171
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• 2009

Poly(lactic-co-glycolic acid) (PLGA) microspheres have been a useful tool as a controlled drug delivery system for peptides and proteins. Recently, porous microspheres have gained great attention as inhalation drug delivery system due to their low aerodynamic densities. Here, we report highly porous PLGA microspheres, which were prepared by using a single o/w emulsification/solvent evaporation method. Two types of porogen, i.e., (i) extractable Pluronic F127 and (ii) gas foaming salt of ammonium bicarbonate, were used to induce pores on the surface of PLGA microspheres. The respective preparation conditions on dp/cp ratio and porogen concentration were determined by the previous preliminary experiments, and other preparation factors were further optimized on the basis of PLGA Mw and porogen type. The morphological features examined by scanning electron microscope (SEM) show these porous microspheres have highly porous surface structure with a diameter range of 20${\sim}$30 ${\mu}$m. These highly porous PLGA microspheres, which have much lower density, would be a practical aerosol system for pulmonary drug delivery.

• Applied Microscopy
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• v.28 no.3
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• pp.299-306
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• 1998

T-butyl alcohol (TBA) freeze-drying method originally designed by Inoue and Osadake (1989) was adopted to dry specimens for scanning electron microscopy and the results were compared with those dried using critical point dryer (CPD). Small pieces $(1\times1\times3mm)$ of liver of Sprague-Dawley rats were cut and fixed in 2% glutaraldehyde in 0.1 M sodium cacodylate buffer after anesthesia, and processed for scanning electron microscopy by several modifications of TBA freeze-drying methods and by the standard preparation method using CPD. The bile canaliculi and sinusoidal endothelial surface were observed. Tissue dehydrated with TBA before TBA freeze-drying preserved the structures best comparable to those prepared with CPD. This result suggests that combination of dehydration with TBA and TBA freeze-drying is a superior method to the original TBA freeze-drying method dehydrated with ethanol.

• Korean Journal of Human Ecology
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• v.14 no.1
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• pp.95-105
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• 2005

This study examined the factors affecting college students' money management behaviors according to credit card usage. The data were collected from 481 college students in Busan and Gyeongnam areas by a self-administered questionnaire. Frequencies, Cronbach's Alpha, factor analyses, t-test, Pearson's correlation analysis, and regression analyses were conducted by SPSS WINDOWS. The results from this study were as follows. First, there were significant differences between credit card usage group and non-usage group in the means for future preparation, stingy attitude, and planned expenditure. However, there was no significant difference in the mean of money management behaviors. Second, for the credit card usage group, the significant variables affecting money management behaviors included sex, grade, experience of consumer education, father's occupation, monthly household income, future preparation, stingy attitude, methods of emotional change, planned expenditure, and negative recognition. On the other hand, for the non-usage group, grade, experience of consumer education, father's occupation, way of success, future preparation, stingy attitude, planned expenditure, and conditional permission were significant. These results imply that financial management education including values about money and consumption patterns should be conducted.

• Restorative Dentistry and Endodontics
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• v.22 no.1
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• pp.220-227
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• 1997

The purpose of our study is to evaluate the ability of nickel-titanium(NiTi) files in maintaining the original curvature of a curved root canal during canal preparation. Curved canals on translucent resin blocks were prepared with NiTi and stainless steel files, and they were placed at the platform which can reproduce the same position. The unprepared and prepared canal forms were accurately compared by double exposure technique of photography. By finite element methods we also analyzed stress distributions of NiTi and stainless steel files in a curved canal. The results were as follows : 1. NiTi files were excellent in maintaining the original curvature of a curved canal than stainless steel files after canal preparation. 2. The results of canal preparation with these files were well verified by the analysis of stress distributions using finite element methods.

• Journal of Pharmaceutical Investigation
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• v.22 no.1
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• pp.17-29
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• 1992

• Proceedings of the PSK Conference
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• 2000.10a
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• pp.263.2-263.2
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• 2000

• Journal of the Ergonomics Society of Korea
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• v.29 no.3
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• pp.375-382
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• 2010

The purpose of this study was to analyze the risk factors of the musculoskeletal workload of mid-old-age food preparation workers by identifying the differences in the complaints of subjective symptoms between mid-old-age housewives and mid-old-age food preparation workers. This study was carried out on a total of 83 subjects from April 2009 through July 2009: 43 food preparation workers at the catering department of general hospital A, with a high rate of mid-old-age food preparation staff, and 40 full-time housewives (40~59 years old). The analysis of the relationship between the rates of the subjective symptoms of the two groups showed that the mid-old-age food preparation workers had a 7.8-fold higher risk of developing musculoskeletal diseases than the full-time housewives. The musculoskeletal workload of the mid-old-age food preparation workers included repetitive motions, uncomfortable postures, and heavy lifting. It is hoped that this study will help provide mid-old-age people with opportunities for appropriate economic activity and labor and will help improve their work postures and methods as well as their environmental-risk factors.

• Phonetics and Speech Sciences
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• v.9 no.4
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• pp.1-7
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• 2017

It was shown in speech production studies that the preparation unit of spoken word production is language particular, such as onset phonemes for English and Dutch, syllables for Mandarin Chinese, and morae for Japanese. However, there have been inconsistent results on whether the onset phoneme is a planning unit of spoken word production in Korean. In this study, two sets of experiments investigated possible influences of task demands on the phonological preparation in native Korean adults, namely, implicit priming and word naming with the form preparation paradigm. Only the word naming task, but not the implicit priming task, showed a significant onset priming effect, even though there were significant syllable priming effects in both tasks. Following the attentional theory ($O^{\prime}S{\acute{e}}aghdha$ & Frazer, 2014), these results suggest that task demands might play a role in the absence/presence of onset priming effects in Korean. Native Korean speakers could maintain their attention to the shared onset phonemes in word naming, which is not very demanding, while they have difficulties in allocating their attention to such units in a more cognitive-demanding implicit priming, even though both tasks involve accessing phonological codes. These findings demonstrate that there are cross-linguistic differences in the first selectable unit in preparation of spoken word production, but within a single language, the preparation unit might not be immutable.

• Journal of Korean Clinical Health Science
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• v.6 no.2
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• pp.1180-1188
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• 2018

Purpose. This study was to effects of major satisfaction of dental hygiene students and students on self-efficacy and career preparation behavior by investigation to provide basic data for developing a systematic career customized employment support program. Methods. The data were collected from 249 students from December 1 to 10 day 2016 in Yeongnam region. Data analysis was performed using descriptive statistics frequency, t-test(One-way ANOVA), logistic regression by SPSS WIN 18.0 program. Results. According to the general characteristics department dental hygiene students were major satisfied with 59.8%. Satisfaction with career decision self-efficacy and career preparation self-efficacy was found to $68.30{\pm}10.21$ statistically significant(p<.001). Satisfaction was also found to statistically significant ($32.65{\pm}6.05$) in career preparation behavior(p<.05). Satisfactory scores were found to 1.306 times higher than the dissatisfied students in the career decision self-efficacy goal setting. It was found that 8.423 times in satisfaction of career planning in career preparation. Conclusion. Considering the effects of dental hygiene students' major satisfaction on career decision self - efficacy and career preparation behavior, it would be good if we could develop and use various programs to improve the satisfaction of students in their majors.

• Restorative Dentistry and Endodontics
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• v.27 no.5
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• pp.521-529
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• 2002

The purpose of this study was to compare the shaping time of two shaping methods and the leakage of three different obturation techniques. Ninty three canaled human molar teeth were used, which were randomly divided into two groups of forty teeth each and ten control teeth. After working length determination, the one group was prepared crown-down technique using rotary root canal instruments of GT rotary files .12/20, .10/20, .08/20 and .06/20 taper(Maillefer Instrument SA. Switzerland). The other group was instrumented with Gates Glidden burs(#1, #2, and #3) to coronal preparation and GT rotary files .08/20 and .06/30 taper to apical preparation. Shaping time was measured. After root canals were instrumented, they were divided to three subgroups and obturated as follows : Subgroup 1, obturated with single cone method Subgroup 2, obturated with lateral condensation : Subgroup 3, obturated with continuous wave technique. Three subgroups were obturated using non-standardized gutta-percha cone(Diadent, Korea, .06 or .08 taper) and AH-26(Dentsply DeTrey, Germany) as a root canal cement. Ten unobturated teeth served as positive and negative controls. After immersion in 2% methylene blue solution for 1 month, the teeth were washed during 24h. The teeth were demineralized in 10% nitric acid and dehydrated by immersion in 80, 90 and 100% ethyl alcohol. The teeth were finally cleared and stored in 100% methylsalicylate, and apical dye penetration was evaluated under stereomicroscope(Leica M420, LC, U.S.A)at $\times$8.75 magnification. Liner measurement of dye penetration was assessed with the use of digitalized image analysing system (analySIS, GmbH, Germany) The data were analysed statistically using independent T-test and Two-way ANOVA and Tukey test. The result were as follows 1. In canal prepared with GT$^{TM}$ rotary file, shaphing time taked more than the group of using Gates Glidden drill to coronal preparation without statistical significance (p>0.05) 2. The group of single cone obturation using canal preparation of GT$^{TM}$ rotary files showed significantly more apical leakage than those of lateral condensation and continuous wave technique regardless of shaping method (p<0.05). 3 The group of single cone obturation using canal preparation of GT$^{TM}$ rotary files and Gates Glidden drill showed significantly more apical leakage than those of continuous wave technique regardless of shaping method (p<0.05). 4. Regardless of shaping method, The group of continuous wave obturation showed less apical leakage than those of lateral condensation without statistical significance (p>0.05). 5. The group of single cone obturation using canal preparation of GT$^{TM}$ rotary files and Gates Glidden drill showed more apical leakage than the group of lateral condensation using same shaping method with-out statistical significance (p＞0.05).