• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.4
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• pp.104-111
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• 2008

The objective of this study is to evaluate micro end-milling characteristics and tool wear behavior of AlN-hBN composites. First, AlN based composites with hBN contents in the range of 10 to 20vol% were prepared by hot-pressing. Vickers hardness and flexural strength of the prepared composite specimens were measured and compared according to the vol% of hBN variations. Then, cutting force variations were measured and analyzed using a tool dynamometer during the micro end-milling experiments; and machined surface shapes and roughness were investigated using a 3D non-contact type surface profiler. After micro end-milling, worn tools were investigated using a tool microscope and SEM images. From the experimental results, it can be observed that the cutting forces decreased, and surface qualities were improved with increasing hBN contents. At low content of hBN, tool chipping was observed; and tool wear rate decreased with increasing hBN contents. The results of this study insist that proper machining conditions, including tool wear behavior investigation, should be determined for the micro end-milling of AlN-hBN composites for its further application.

• Korean Journal of Crystallography
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• v.6 no.2
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• pp.111-117
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• 1995

TiO2 thin films were prepared on a (100)silicon wafer using a chemical vapor deposition(CVD) method. The deposition experiments were performed using the TTIP in the deposition temperature ransing from 200 content. The deposition rate of TiO2 was increased with the substrate temperature and the oxygen content. The thickness of the deposited thin film and the compositional analysis of this thin films with theoxygen content were measured using Ellipsometry, SEM and ESCA, respectively. The deposited thin film was composed of a bilayer, external TiO2 and internal Ti. Carbon as a residual impurity was found to remain when zero sccm O2 was purged into a reaction chamber and the composition of the deposited thin film was found to change Ti into TiO in a deeper layer. However, when 600sccm O2 was supplied to a reaction chamber, it has been found to reside less carbon content than without O2. Finally, in the condition of 1200sccm O2, no impurity level of carbon was observed and a deeper layer consisted of the Ti composite, even though the deposited surface was composed of TiO2.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2013.11a
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• pp.105-105
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• 2013

본 연구는 산불피해 후 주민들의 시설물 안전성에 대한 인식을 분석하기 위하여 2013년 3월 9일부터 10일 이틀 동안 280ha의 산림 피해면적과 57동의 시설물 피해를 입은 울주산불지역과, 79ha의 산림피해와 111동의 시설물 피해를 입은 포항산불지역의 주민들을 대상으로 산불피해 후 시설물에 대한 안전성과 당시 격었던 심리상태를 알아보고자 울주 주민 60명, 포항 주민 60명 총 120명에 대하여 설문조사를 실시하였다. 조사항목은 일반현황, 산림 내 주요시설 및 주변 안전성 인식, 교육훈련에 대한 인식, 심리상태에 대해 4개의 항목으로 조사한바, 일반형황으로는 120명중 28명(23.3%)을 제외한 92(76.7%)명이 산불을 1~2회 이상 목격했으며, 24명(20%)이 산불 진화에 참여하였고, 41~60세가 66명(55%)으로 가장 많은 것으로 나타났다. 현재 거주하고 있는 건물은 콘크리트 가옥이 84명(70%)으로 가장 많았고, 현재 거주하고 있는 곳의 안전성에 대해서는 68명(56.7%)이 '안전하지 않다'고 인식하였다. 또한, 가옥주변 가연물질 관리 상태는 57명(47.5%)이 관리가 '잘 되어 있지 않다'고 인식하였다. 또한, 산불발생 대응 피난 및 교육훈련의 필요성에 대한 5점 척도 분석결과 4.2점으로 교육훈련이 필요하다고 인식하고 있었고, 필요한 교육훈련 과목으로는 산불피난대응훈련이 44명(36.7%)으로 가장 높은 비율을 나타냈다. 또한, 산불경험 후 심리적 불안에 대한 5점 척도 분석결과 4.0점으로 불안을 느끼고 있었고, 산불발생 후 느끼는 고통으로는 불면증, 불안감, 상실감, 혼란감, 신경과다 중 불안감이 89명(65.0%)으로 가장 높은 비율을 나타냈다.

• Journal of Korean Biological Nursing Science
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• v.17 no.1
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• pp.37-43
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• 2015

Purpose: Stress, depending on its intensity and duration, results in either adaptive or maladaptive physiological and psychological changes in humans. Also, it was found that stressful experiences increase the signs of behavioral despair in rodents. On the other hand, exercise and melatonin treatment is believed to have many beneficial effects on health. Thus, this study was designed to evaluate the anti-depressant effects of physical activity and melatonin against chronic stress-induced depression in rats. Methods: Adult male Sprague-Dawley(SD) rats(200-250g, 7 weeks of age) were subjected to depression induced by chronic stress. Chronic depression was induced with forced-swim stress (FSS) and repeated change of light-dark cycle for 4 weeks. In the last 2 weeks, some rats were confined in a cage enriched with a running wheel, seesaw and chewed a ball from 19:00 to 07:00 every day. Melatonin was injected intra-peritoneally (I.P), and the rats received intraperitoneal injections of melatonin (15 mg/kg). The Forced Swim Test (FST) was performed to evaluate the immobility behaviors of rats for a 5 min test. Results: It was found that, the immobility time in FST was significantly (p<.05) lower in physical exercise ($M=58.83{\pm}22.73$) and melatonin ($M=67.33{\pm}37.73$) than in depressive rats ($M=145.93{\pm}63.16$) without physical activity. Also, TPH positive cell in dorsal raphe was significantly (p<.05) higher in exercise ($M=457.38{\pm}103.21$) and melatonin ($M=425.38{\pm}111.56$) than in depressive rats ($M=258.25{\pm}89.13$). Conclusion: This study suggests that physical activity and melatonin produces antidepressant-like effect on stress-induced depression in rats. So, physical exercise and melatonin may be a good intervention in depression patients.

• Journal of the Korean Home Economics Association
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• v.26 no.4
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• pp.43-52
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• 1988

This study is intended to reveal the nutritional realities of school children due to their box lunch. The samples were chosen at random from the third grade to the sixth grade children in an elementary school in Seoul : 122 male and 111 female children, 233 children in all. among the subjects, 44.3% have a family of four, 34.3% have over 500,000 won of family income a month, and 44.3% of their mothers graduated from a high school. The average intake of calories is 573.6 Kcal, and the ratios of the calory intakes to the recommended amounts are 90.6% in the third grade children and from the fourth grade to the sixth grade, 79.5% in the male children and 82.9% in the female children. The average consumption of protein is 21.0g and the ratio of animal protein is 41.4%. the ratio of energy yield nutrients is 67.4% : 14.5 : 18.0 (carbohydrate : protein " fat). Considering the recommended amounts, the intake of protein is enough; the consumption of vit, A, thiamine, niacin are appropriate;and the intake of calories, Riboflabin and ascorbic acid, calcium, iron are deficient. Even though there is no significant difference between the socioeconomic factors (the standard of education of the subjects' mothers and family income0 and the intakes of calories and protein, there is a tendency that the consumption of protein intake si more abundant in the middle class than in any other class. The subjects' distribution of the physical growth index, is as follows; A (6.9%), B(19.3%), C(48.5%), D(13.7%) and E (11.6%). As the subjects' intake of calcium increases, the weight shows significant improvement (p<0.001). As the consumption of calories increases, the physical development shows significant improvement (p<0.05), and the weight shows significant increase (p<0.001).

• Korean Journal of Oriental Medicine
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• v.16 no.1
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• pp.111-118
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• 2010

Objectives : We identified the applicability of Sasang constitution for the enhancement of job satisfaction, job performance and organizational commitment in office workers. Methods : We conducted a survey using a Sasang constitution questionnaire to identify the Sasang types, and several questionnaires to identify organizational commitment, job performance and job satisfaction of 205 office workers who live in D city. Data were analyzed with ANOVA test. Results 1. In organizational commitment, Sasang constitution showed a significant correlation in the question of "I feel that I am not a real member of this company" and the order of score was Soeumin, Taeeumin, and Soyangin. 2. In job performance, Sasang constitution showed significant correlations in the questions of "I always achieve my goals" and "I am recognized as a person who has a good job performance" and the order of score was Soeumin, Taeeumin, and Soyangin. 3. In job satisfaction, Sasang constitution showed a significant correlation in the questions of "I am forced to go to the office" and the order of score was Soeumin, Soyangin, and Taeeumin. Sasang constitution also showed significant correlations in the questions of "I am usually passionated in my work", and "I was disappointed when I got at my job" and the order of score was Soeumin, Taeeumin, and Soyangin. Conclusions : Sasang constitution. had significant correlation in organizational commitment, job performance and job satisfaction in office workers.

• Restorative Dentistry and Endodontics
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• v.18 no.1
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• pp.122-132
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• 1993

The aim of this study was to investigate the level of radiopacity of glass ionomer cements and to determine the optimum level of radiopacity that is the most compatible with the radiographic diagnosis of secondary caries. The experiments were performed in two parts. In the first part, the radiopacities of 9 glass ionomer cements (FI, FII, FI-LC, FII-LC, SI, SII, Vit, B-VLC, AC) and base materials(Ultra-Blend, Zinc phoaphate cements, Cavitec, Dycal) were measured by densitometer. Then all experimental materials were divided into 5 groups based on the level of radiopacity of enamel and dentin. In the second part, class III cavities with or without secondary caries were prepared in extracted anterior teeth. The representative materials of each group with different radiopacities were inserted into each cavity. The radiographs were interpreted by 15 dentists and seconsary caries were diagnosed according to a five-point confidence rating. Sensitivity and ROC analysis were used to compare observer performance. The following results were obtained : 1. The radipacity of glass ionomer cements varied between 1.111mm Al and 6.011mm Al equivalent. 2. Among experimental materials, three materials in group I had lower radiopacity than that of dentin. The radiopacity of two materials in group II slightly exeeded that of dentin. Three materials in group III had slightly lower radiopacity than that on enamel. The radiopacity of one material in group W was slightly higher than that of enamel. Four materals in group V had the radiopacity that exeeded over 2.0mm AI equivalent to that of enamel. 3. The group IV was the highest for sensitivity and the group V was the highest for ROC area. However, no significant differences were obtained among group II, III, IV and V (P<0.05) but only group I was significantly lower(P<0.01). 4. In comparison with the observer performance for the radiographic diagnosis of secondary caries, the group II, III, IV, and V were superior to the group I (P<0.01). And so the optimum level of radiopacity to detect the secondary caries was the radiopacity that is higher than that of dentin.

• Journal of the Korean institute of surface engineering
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• v.38 no.3
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• pp.106-111
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• 2005

Ternary Ti-B-C coatings were synthesized on WC-Co and Si wafers substrates by a PECVD technique using a gaseous mixture of $TiCl_4,\;BCl_3,\;CH_4,\;Ar,\;and\; H_2$. The effects of deposition variables such as substrate temperature, gas ratio, $R_x=[BCl_3/(CH_4+BCl_3)]$ on the microstructure and mechanical properties of Ti-B-C coatings were investigated. From our instrumental analyses, the synthesized Ti-B-C coatings was confirmed to be composites consisting of nanocrystallites TiC, quasi-amorphous TiB2, and amorphous carbon at low boron content, on the contrary, nanocrystallites $TiB_2$, quasi-amorphous TiC, and amorphous carbon at relatively high boron content. The microhardness of the Ti-B-C coatings increased from $\~23 GPa$ of TiC to $\~38 GPa$ of $Ti_{0.33}B_{0.55}C_{0.11}$ coatings with increasing the boron content. The $Ti_{0.33}B_{0.55}C_{0.11}$ coatings showed lower average friction coefficient of 0.45, in addition, it showed relatively better wear behavior compared to other binary coatings of $TiB_2$ and TiC. The microstruture and microhardness value of Ti-B-C coatings were largely depend on the deposition temperature.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.8 s.185
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• pp.171-177
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• 2006

This study was performed as a part of the research on the development of a maskless and electroless process for fabricating metal micro/nanostructures by using a nanoindenter and an electroless deposition technique. $2-{\mu}m$-deep indentation tests on Ni and Cu samples were performed. The elastic recovery of the Ni and Cu was 9.30% and 9.53% of the maximum penetration depth, respectively. The hardness and the elastic modulus were 1.56 GPa and 120 GPa for Ni and 1.51 GPa and 104 GPa for Cu. The effect of single-point diamond machining conditions such as the Berkovich tip orientation (0, 45, and $90^{\circ}$ ) and the normal load (0.1, 0.3, 0.5, 1, 3, and 5 mN), on both the deformation behavior and the morphology of cutting traces (such as width and depth) was investigated by constant-load scratch tests. The tip orientation had a significant influence on the coefficient of friction, which varied from 0.52-0.66 for Ni and from 0.46- 0.61 for Cu. The crisscross-pattern sample showed that the tip orientation strongly affects the surface quality of the machined are a during scratching. A selective deposition of Cu at the pit-like defect on a p-type Si(111) surface was also investigated. Preferential deposition of the Cu occurred at the surface defect sites of silicon wafers, indicating that those defect sites act as active sites for the deposition reaction. The shape of the Cu-deposited area was almost the same as that of the residual stress field.

• Molecules and Cells
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• v.21 no.1
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• pp.104-111
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• 2006

Gene therapy with nonviral vectors using the suicide gene/prodrug activating system of herpes simplex virus type-1 thymidine kinase (HSV1-TK)/ganciclovir (GCV) is inefficient in killing malignant tumor cells due to two major factors: (a) an unsatisfactory bystander effect; (b) short-lived expression of the protein. To study the capacity of the protein transduction domain (PTD) of HIV-1 TAT protein to enhance HSV1-TK/GCV cancer gene therapy, we constructed three fusion proteins TAT-TK, TK-TAT and TK. TAT-TK retained as much enzyme activity as TK, whereas that of TK-TAT was much lower. TAT-TK can enter HepG2 cells and much of it is translocated to the nucleus. The transduced HepG2 cells are killed by exogenously added GCV and have bystander effects on untransduced HepG2 cells. Most importantly, the introduced recombinant protein is stable and remains functional for several days at least, probably because nuclear localization protects it from the cytoplasmic degradation machinery and provides access to the nuclear transcription machinery. Our results indicate that TAT fusion proteins traffic intercellularly and have enhanced stability and prodrug cell killing activity. We conclude that TAT has potential for enhancing enzyme prodrug treatment of liver cancers.