• Bulletin of the Korean Chemical Society
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• 제30권10호
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• pp.2393-2397
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• 2009

Second-order rate constants ($k_{HOO}$‒) have been measured spectrophotometrically for nucleophilic substitution reactions of Y-substituted phenyl benzenesulfonates (1a-g) with $HOO^-$ ion in $H_2O$ at $25.0\;{\pm}\;0.1\;{^{\circ}C}$. The Br$\phi$nsted-type plot is linear with ${\beta}_{lg}$ = ‒0.73. The Hammett plot correlated with with ${\sigma}^-$ constants results in much better linearity than ${\sigma}^o$ constants, indicating that expulsion of the leaving group occurs in the rate-determining step (RDS) either in a stepwise mechanism or in a concerted pathway. However, a stepwise mechanism in which departure of the leaving group occurs in the RDS has been excluded since $HOO^-$ ion is more basic and a poorer leaving group than the leaving Y-substituted phenoxide ions. Thus, the reactions of 1a-g with $HOO^-$ ion have been concluded to proceed through a concerted mechanism. The $\alpha$-nucleophile $HOO^-$ ion is more reactive than its reference nucleophile $OH^-$ ion although the former is ca. 4 p$K_a$ units less basic than the latter (i.e., the $\alpha$-effect). TS stabilization through intramolecular H-bonding interaction has been suggested to be irresponsible for the $\alpha$-effect shown by $HOO^-$ ion, since the magnitude of the $\alpha$-effect is independent of the electronic nature of substituent Y in the leaving group. GS destabilization through desolvation of $HOO^-$ ion has been concluded to be responsible for the $\alpha$-effect found in the this study.

• 근관절건강학회지
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• 제21권2호
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• pp.125-134
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• 2014

Purpose: The purpose of this study was to identify factors associated with quality of life of nursing students during clinical practice. Methods: A convenience sample of 332 nursing students completed the questionnaire from July to September, 2013. A self-reported questionnaire was used to obtain data on quality of life, stress related to clinical practice, and health promotion behavior. Data was analyzed with independent t-test, one way ANOVA and Scheff${\acute{e}}$'s post hoc test, Pearson correlation coefficients, and hierarchical multiple regression by using SPSS version 20.0. Results: There were significant differences in quality of life scores by age, economic status, interpersonal relationships, daytime somnolence, number of visits in pharmacy and/or healthcare center, health status, and stress management. Quality of life had positive correlation with health promotion behavior but had negative correlation with the level of stress related to clinical practice. Models including these variables explained 34.3% (F=9.77, p<.001) of the variance for quality of life. Age, economic status, sleep amount, numbers of pharmacy/hospital visits, health status, stress during clinical practice, and health promotion behavior were significantly associated with quality of life in nursing students. Conclusion: There is a need to develop and implement new strategies that will result in improvement in nursing students' quality of life.

• Journal of Microbiology and Biotechnology
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• 제27권2호
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• pp.226-233
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• 2017

Jeung-pyun, a fermented rice cake, is prepared by fermenting rice sourdough using makgeolli, a traditional Korean rice wine, in the presence of yeast and lactic acid bacteria (LAB). The goal of this study was to conduct biochemical and microbial analyses of five different rice sourdoughs, each fermented with a different commercial makgeolli, using culture-dependent and culture-independent approaches. All sourdough samples fermented with different makgeolli for 6.5 h showed different profiles in pH, total titratable acidity, organic acid concentration, and microbial growth. LAB belonging to different genera were identified based on colony morphology on modified MRS and sourdough bacteria agar medium. PCR-denaturing gradient gel electrophoresis analyses of the five sourdoughs showed different bands corresponding to LAB and yeast. 16S/26S rRNA gene sequence analyses of the samples confirmed that the predominant LAB in the five fermented rice doughs was Lactobacillus plantarum, Lb. pentosus, and Lb. brevis. Various other Lactobacillus spp. and Saccharomyces cerevisiae were common in all five fermented samples. This study provides comprehensive and comparative information on the microflora involved in fermentation of rice sourdough and signifies the need to develop effective starters to enrich the quality of jeung-pyun.

• 한국전문물리치료학회지
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• 제22권4호
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• pp.44-50
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• 2015

This study compared the effects of the initial head position (i.e., a HHP versus a relaxed head position) of subjects with and without a FHP on the thickness of the deep and superficial neck flexor muscles during CCF. The study recruited 6 subjects with a FHP and 10 subjects without a FHP. The subjects performed CCF in two different head positions: a HHP, with the head aligned so that the forehead and chin formed a horizontal line, and a relaxed head position (RHP), with the head aligned in a self-selected comfortable position. During the CCF exercise, the thickness of the longus colli (LCo) and the thickness of the sternocleidomastoid (SCM) were recorded using ultrasonography. The thickness of each muscle was measured by Image J software. The statistical analysis was performed with a two-way mixed-model analysis of variance. The thickness of the SCM differed significantly (p<.05) between the subjects with and without FHP. According to a post $h^{\circ}C$ independent t-test, the change in thickness of the SCM increased significantly during CCF in the subjects with FHP while adopting a HHP compared to that in the subjects without FHP. The change in thickness of the SCM was not significantly different between the two positions in subjects without FHP, and there was no significant change in thickness of the LCo muscle during the CCF exercise according to the initial position in both subjects with and without FHP. The results suggest that CCF should be performed in RHP to minimize contraction of the SCM in subjects with a FHP.

• Journal of Gastric Cancer
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• 제17권2호
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• pp.154-161
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• 2017

Purpose: This study aimed to investigate the correlation between multiple early gastric cancer (MEGC) and multiple primary malignancies during the follow-up of patients with gastrectomy. Materials and Methods: The number of primary tumors detected in other organs after gastrectomy for early gastric cancer (EGC) has been increasing because of improved survival and surveillance programs. A total of 3,129 patients underwent radical gastrectomy for treatment of EGC at Samsung Medical Center from January 2000 to December 2005. Of these, 3,057 patients were selected and their medical records were retrospectively analyzed. Results: Among the 3,057 patients, 148 (4.8%) had MEGC, 84.5% were male, 57.4% were over 60 years old, 42.6% had a macroscopic type EGC IIb main lesion, and 68.9% had well-differentiated tumors with a significantly high incidence of MEGC. There were no differences between patients with solitary early gastric cancer (SEGC) and those with MEGC with regard to overall survival or recurrence-free survival, but MEGC was an independent risk factor for metachronous primary malignancies in other organs (P=0.004, hazard ratio [HR]=2.444). Conclusions: MEGC is not a risk factor for poor prognosis after curative gastrectomy, but it is a risk factor for metachronous primary malignancies in other organs during postoperative follow-up; therefore, careful surveillance is needed.

• Restorative Dentistry and Endodontics
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• 제39권1호
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• pp.12-16
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• 2014

Objectives: Extensively destroyed teeth are commonly restored with composite resin before cavity preparation for indirect restorations. The longevity of the restoration can be related to the proper bonding of the resin cement to the composite. This study aimed to evaluate the microshear bond strength of two self-adhesive resin cements to composite resin. Material and Methods: Composite discs were subject to one of six different surface pretreatments: none (control), 35% phosphoric acid etching for 30 seconds (PA), application of silane (silane), PA + silane, PA + adhesive, or PA + silane + adhesive (n = 6). A silicone mold containing a cylindrical orifice ($1mm^2$ diameter) was placed over the composite resin. RelyX Unicem (3M ESPE) or BisCem (Bisco Inc.) self-adhesive resin cement was inserted into the orifices and light-cured. Self-adhesive cement cylinders were submitted to shear loading. Data were analyzed by two-way ANOVA and Tukey's test (p < 0.05). Results: Independent of the cement used, the PA + Silane + Adhesive group showed higher microshear bond strength than those of the PA and PA + Silane groups. There was no difference among the other treatments. Unicem presented higher bond strength than BisCem for all experimental conditions. Conclusions: Pretreatments of the composite resin surface might have an effect on the bond strength of self-adhesive resin cements to this substrate.

• 한국의류학회지
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• 제34권6호
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• pp.902-912
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• 2010

This study compares and contrasts the consumer decision-making styles (CDMS) of South Korean and American Generation Y females. A total of 117 American female and 206 Korean female consumers completed self-report survey questionnaires to assess their consumer decision making styles. Exploratory principal components factor analysis using varimax rotation was used to categorize the items into an underlying set of American and Korean decision-making characteristics. Two-tailed independent t-tests were conducted to examine the differences between the two groups when items appeared to have common factors. Factor analysis identified five common factors between the two samples (i.e., enjoyment, shopping aversion, price consciousness, brand consciousness, and quality consciousness). The t-test results report significant differences in the items reported in each factor between American and Korean females. Some of the factors are more indicative of American female Generation Y consumers than Korean female Generation Y consumers. For example, the American female sample seemed to enjoy shopping and prefer brand names more than the female Korean sample. Koreans females seem to have a higher aversion to shopping than Americans; in addition, Koreans females seem to be more accepting of discount and outlet stores, will wait until the price is low before buying a product, and prefer sales when shopping. Based on the findings, the instrument identified varying CDMS between the two samples used. Previous studies using the Sproles and Kendall (1986) instrument experienced the same issue (Bakewell & Mitchell, 2004, 2006; Bauer et al., 2006; Durvasula et al., 1996; Fan & Xiao, 1998; Hanzaee & Aghasibeig, 2008; Mitchell & Walsh, 2004; Siu et al., 2001; Walsh et al., 2001). The results support the idea that no single instrument can be used to examine CDMS in different cultures. This suggests that each country has a CDMS with internal characteristics. Limitations and research for future studies are also discusse.

• 한국의류학회지
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• 제32권6호
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• pp.968-979
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• 2008

농촌 지역사회의 지속적인 성장과 활성화는 지역경제에 의해 좌우되고, 마찬가지로 지역주민들의 생필품 공급은 지역소매업자들에게 의해 이루어진다. 이러한 현실에서, 농촌지역의 영세소매업자에 대해 관심을 가지고 이들을 연구하는 것은 지역공동체의 지속적인 성장에 중요할 것이다. 본 연구의 목적은 대규모의 할인점들과의 경쟁에 직면하고 있는 미국 농촌 지역의 영세소매업자들(의류, 보석, 꽃, 철물 등)중에서 대규모의 할인점들과의 치열한 경쟁에 성공을 거둔 영세소매업자들이 어떠한 마케팅, 머천다이징, 고객서비스, 경영전략을 실시하고 있는지를 살펴보는 것이다. 또한, 영세소매업자들의 성공을 가능케 한 사업전략으로 사회적 자본인 지역사회참여가 어떻게 사용되고 있는지도 고찰하고자 한다. 본 연구에서는 미국 중서부 지역의 세 도시를 대표하는 27명의 농촌소매업자들과의 인터뷰 및 내용분석방법을 사용하였다. 연구결과, 이들은 몇 가지 효과적인 경영전략들을 실시하고 있지만, 아직도 미흡한 부분들이 있었다. 결과부분에서는 이들이 사용하고 있는 주요 경영관행들에 대해 논의하였다.

• Environmental Analysis Health and Toxicology
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• 제26권
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• pp.11.1-11.6
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• 2011

Objects: The prevalence of asthma has increased in recent decades globally. The objective of the present study is to elucidate whether hospitalization for bronchiolitis in infancy and low socioeconomic status interact for bronchial hyperreactivity during teenage years. Method: We studied 522 children age 13-14 years attending schools in rural and urban areas to investigate the risk factors for bronchial hyperreactivity (BHR), defined as a provocation concentration of methacholine that causes a decrease of 20% ($PC_{20}$) in forced expiratory volume within 1 second. Clinical examination, skin prick test, spirometry, and methacholine challenge were performed on all study subjects, who provided written consent. We used multivariate logistic regression to investigate the risk factors for BHR, and analyze the interaction between hospitalization for bronchiolitis in infancy and low socioeconomic status. Results: Forty-six (10.3%) positive BHR cases were identified. In the multivariate logistic analysis, as independent predictors of BHR, adjusted odds ratio of bronchiolitis diagnosed before 2 years of age in low income families was 13.7 (95% confidence interval, 1.4 to 135.0), compared to reference group, controlling for age, gender, parental allergy history, skin prick test, and environmental tobacco smoke (ETS) exposure. Interaction was observed between bronchiolitis before 2 years old and low socioeconomic status on children's bronchial hyperreactivity (p-interaction=0.025). Conclusions: This study showed that bronchiolitis diagnosed before 2 years of age and low socioeconomic status interacted on children's bronchial hyperreactivity. Prevention of acute respiratory infection in early childhood in low socioeconomic status is important to prevent BHR as a precursor of asthma.

• 한국재료학회지
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• 제11권2호
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• pp.151-154
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• 2001

상부전극, Pt, Ir, 그리고 $IrO_2$, 에 따라 수소 열처리전과 후, 그리고 회복열처리시 누설전류특성을 고찰하였다. Pt/PLZT/Pt 케페시터는 수소열처리 후에 다시 회복열처리를 수행하면 완전히 이력곡선의 회복을 보이며 또한 피로특성도 거의 회복 된다. Pt과 IrO$_2$ 상부전극의 경우의 진 누설전류 특성은 열처리조건에 관계없이 강한 시간 의존성을 갖는 space-charge influenced injection모델에 적합하다. 반면에 Ir 상부전극의 경우는 Ir과 PLZT 사이의 계면에 헝성된 전도성 상인 $IrO_2$로 인해 높은 누설전류 밀도를 보이면서 relaxation current 영역이 없이 steady state 영역을 보이는, 주로 Schottky barrier 모델에 의해 설명된다.