• 대한공업교육학회지
• /
• 제31권2호
• /
• pp.350-363
• /
• 2006

최근 마이크로 엔드밀을 이용한 가공은 소형구조물이나 소형기계의 부품과 금형산업에서 양호한 표면 거칠기와 가공시간의 단축을 위해 고정도의 기술을 요구하고 있다. 마이크로 엔드밀을 이용한 가공에 있어서 가공조건은 절삭면의 표면거칠기에 커다란 영향을 미치게 된다. 따라서 본 연구에서는 마이크로 엔드밀을 이용하여 스테인리스 강(STS 304)의 표면을 가공하였고, 실험계획법에 의해 최적의 표면거칠기를 얻기 위한 가공조건에 대해 분산분석하였다. 본 연구를 통하여 마이크로 엔드밀에 의한 가공에서 가공조건은 절삭깊이, 스핀들의 회전수, 이송속도의 순서로 표면거칠기에 영향을 미치는 것을 알았다.

• Archives of Plastic Surgery
• /
• 제32권6호
• /
• pp.683-688
• /
• 2005

The ischemia-reperfusion injury of the skeletal muscles is caused by generation of reactive oxygen during ischemia and reperfusion. Melatonin or N-Acetyl-5-methoxy- tryptamine is suggested to have antioxidant effects in several tissues. In present study, we examined the protective effect of melatonin in a rat hind limb ischemia-reperfusion injury. Dimethyl-sulfoxide(DMSO) was also tested for comparison. Ischemia was induced for 4 hours by vascular clamping and followed by 1 hour or 24 hours of reperfusion. Muscle injury was evaluated in 4 groups such as single laparotomy group(control), ischemia-reperfusion group, DMSO group, melatonin group. Eedema ratio and malondialdehyde(MDA) of muscle tissue and serum level of creatine kinase(CK), were measeured at the end of reperfusion. DMSO and melatonin group showed significant amelioration of edema and serum CK compared with ischemia-reperfusion group. The decreasing effect was more prominent in melatonin group. The muscle tissue MDA concentration is significantly lower in melatonin group than in ischemia-reperfusion group. The results show that melatonin prevents and improves ischemia-reperfusion injury more effectively in a rat hind limb than DMSO dose. Thus, clinically the melatonin may be used for a beneficial treatment of such injuries

• Journal of Nutrition and Health
• /
• 제27권4호
• /
• pp.323-335
• /
• 1994

The present study was carried out in normocholesterolemic New Zealand white(NZW) rabbit, to evaluate the effect of dietary supplementation with Korean pinenut oil, on plasma lipids, plasma lipoproteins, liver lipids and platelet aggregation. NZW rabbits were fed for 80 days on a commercial chow diet supplemented with 5% of energy as fats(soybean oil or pinenut oil) or 10% of energy as fats(soybean oil or pinenut oil). A control group was fed a commercial stock diet. There were no significant effects of pinenut oil on plasma free cholesterol, HDL-cholesterol, triglycerides, glucose and lecithin-cholesterol acyltransferase, as compared with those obtained from rabbits fed the soybean oil diet. After 80 days, the concentration of plasma free fatty acid in only the pinenut oil group was significantly decreased by about 50% relative to the control diet. At the end of the dietary treatment, liver triglycerides and phospholipids were significantly decreased in the pinenut oil group, compared to the how diet, whereas the soybean oil-consuming rabbits had only significantly decreased phospholipid levels. Cholesterol contents of liver were unaffected by type of dietary fat. At the end of 80 days, a diet containing pinenut oil resulted in a decrease in apolipoprotein B and the apo B/apo AI ratio as compared with the stock diet or soybean oil diet. Platelet aggregation induced by collagen or arachidonic acid was depressed significantily in pinenut oil diet.

• Journal of Acupuncture Research
• /
• 제24권4호
• /
• pp.1-12
• /
• 2007

Objectives : The purpose of this study is to investigate the anti-oxidative effect of electroacupuncture at Shinmaek($BL_{62}$) in rats. Methods : In order to cause oxidative stress, AAPH was administered to the abdominal cavity of rats, after we stimulated $BL_{62}$ of the rat by electroacupuncture. Blood test and anti-oxidative test(LDL-cholesterol, GOT, GPT SOD, GSH, catalase, NO, MDA) were performed at the end of treatment. Results: 1. SOD, glutathione, catalase activity were significantly increased in the $BL_{62}-EA$ group compared with the holder group. 2. NO density was significantly decreased in the $BL_{62}-EA$ group compared with the holder group. 3. Glutathione was significantly increased in the $BL_{62}-EA$ group compared with the sham-EA group. Conclusion : These results suggest that electroacupuncture at $BL_{62}$ has an anti-oxidant effect in human.

• 지식경영연구
• /
• 제12권3호
• /
• pp.59-71
• /
• 2011

This study intends to examine the effect of research and development (R&D) expenditure effects on firm value through patent and earing persistence. The patent is the representative intangible asset which objectively indicates a typical product of research and development activities to external parties. If a firm has acquired the patent, it receives amicable evaluation from the market compared to the firm which has not acquired patent. Empirical analysis is performed for non-banking firms (1,860 firm-years) listed on Korean Stock Exchange with December fiscal year-end over 2004-2009. Research results are as follows. First, the multiple pricing of patent acquiring firm and earing persistence increased group showed that they have higher prices than the other groups. Second, the multiple pricing of R&D expenditures of earing persistence increased group showed that they have higher prices than the other group. Third, the R&D expenditures of earing persistence increased group is receiving more friendly evaluation from the stock market than the other group.

• 디지털융복합연구
• /
• 제10권1호
• /
• pp.229-240
• /
• 2012

본 연구는 전산세무회계와 관련한 수요자집단별 차별화 교육이 전산세무회계 교육의 효율적 운영에 미치는 영향의 분석을 목적으로 수행되었다. 이를 위하여 본 연구에서는 전산세무회계교육의 독립변수와 종속변수를 측정하고, 회귀분석을 통하여 측정된 전산시스템의 운영만족도, 학습만족도 및 효율적 활용성을 수요자집단별로 분석하고 이를 통하여 각 수요자집단별 전산세무회계 교육에 대한 인식의 차이를 확인하였다. 본 연구를 통하여 도출된 전산세무회계에 관한 수요자집단별 차별화 교육의 필요성은 향후 전산세무회계 교육의 보다 효율적인 운영전략 모색에 있어 중요한 지침이 될 수 있을 것이며, 동시에 유사한 여러 연구에 많은 응용이 가능할 것으로 기대된다.

• 융합경영연구
• /
• 제10권5호
• /
• pp.15-24
• /
• 2022

Purpose: The purpose of this study is to find a way to improve and overcome the psychological treatment limited to the negative factors dealt with in psychology from a positive psychological point of view. To this end, this study aims to verify whether a positive psychotherapy program can improve happiness, resilience, and post-traumatic growth along with improvement of psychological symptoms such as depression. Research design, data and methodology: To this end, in this study, mean difference analysis was conducted using t-test on 10 participants in the 16th PPT program and 14 in the control group. Also, after setting the main variables, we tried to confirm the effectiveness through simple regression analysis and multiple regression analysis of the causal relationship model. Results: As a result of the independent sample t-test and the paired sample t-test, it was confirmed that the group participating in the PPT program had higher flourish, happiness, resilience, post-traumatic growth, and lower depression. In addition, as a result of regression analysis, it was confirmed that post-traumatic growth had a positive effect, and that depression was a life-threatening factor. Conclusions: Since the PPT program has a positive effect on the participants with relatively negative psychological symptoms, it is necessary to expand it. In addition, it is necessary to introduce various preventive programs such as PPT as well as traditional psychological treatment for negative symptoms such as depression.

• Archives of Plastic Surgery
• /
• 제50권4호
• /
• pp.432-442
• /
• 2023

Background Macrophages play a major role in wound healing and prevent infection from the outside. Polarization conversion of macrophages regulates aspects of inflammation, and two macrophages, M1 (classically activated) and M2 (alternatively activated), exist at both ends of broad-spectrum macrophage polarization. Thus, we aimed to investigate whether macrophage polarization can be artificially regulated. To this end, MgSO4 and small-interfering RNA (siRNA) targeting magnesium transport 1 (MAGT1) were used to investigate the effects of intracellular magnesium (Mg2+) concentrations on the differentiation of macrophages in vitro. Methods THP-1 derived macrophages maintained in a culture medium containing 5 mM MgSO4 and siRNA to inhibit the expression of MAGT1. As comparative groups, THP-1 derived macrophages polarized into M1 and M2 macrophages by treatment with M1, M2 inducer cytokine. The polarization status of each group of cells was confirmed by cell surface antigen expression and cytokine secretion. Results We found that MgSO4 treatment increased CD163 and CD206, similar to the effect noted in the M2 group. The expression of CD80 and HLA-DR was increased in the group treated with MAGT1 siRNA, similar to the effect noted in the M1 group. Functional assays demonstrated that the group treated with MgSO4 secreted higher levels of IL-10, whereas the MAGT1 siRNA-treated group secreted higher levels of IL-6 cytokines. Additionally, the conditional medium of the Mg2+ treated group showed enhanced migration of keratinocytes and fibroblasts. Conclusion Mg2+ can help to end the delay in wound healing caused by persistent inflammation in the early stages.

• Educational Technology International
• /
• 제11권2호
• /
• pp.1-24
• /
• 2010

The study aimed to investigate the differential effects of visual and verbal scaffoldings on web-based problem solving performance. A quasi-experiment with 143 high school students in South Korea was administered. Each student's visualization tendency score was obtained at the beginning of the study. Based on the visualization tendency scores, students were divided into two groups; low and high level visualization tendency groups. Then each group was split in half and randomly assigned to one of the two lessons - one with visual scaffolding and the other with verbal scaffolding. The contents of the two lessons were the same. All students' performance was measured through an essay assignment for a problem solving at the end of the lesson. The result showed that the visual scaffolding group outperformed the verbal scaffolding group (F=22.54, p<.01), regardless of each student's visualization tendency level. The effect size was 0.81, indicating high practical significance. There was no statistically significant interaction effect between scaffolding modalities and students' visualization tendency levels. These findings imply that visual scaffolding is an effective strategy to promote students' problem solving performance.

• Journal of Chest Surgery
• /
• 제15권2호
• /
• pp.139-147
• /
• 1982

In case of segmental injury of trachea, the primary repair is very difficult, because the trachea is fixed in place without movability from the surrounding tissue. In addition to special anatomical situation of trachea, any ideal artificial prosthesis for tracheal replacement is not still appeared. Many authors proposed several procedures for the tracheal repair, but satisfactory results were few. Among the proposed procedures end to end anastomosis of trachea was noted superior when both ends of trachea could be approximated by mobilization of upper and lower injured trachea. The author's experiment was designed to determine the effect about decreased tension on trachea when the hyoid bone was released downward from the surrounding muscular structures. The experimental dogs were divided into two groups, suprahyoid releasing group (SH R) and control group of intact hyoid. SH R group was subdivided into two groups accord ing to he degree of tension. The experimental results were as follow; 1. SH R group: In view of X-ray, the distance between the angle of mandible and the displaced hyoid bone was lengthened downward. And it's range was from 1.3cm (38%) minimally to 2.7cm(108%) maximally. 2. Control group: The distance between the angle of mandible and hyoid was same in both pre and postoperation. As the result of this experiment study, the suprahyoid release technique seems to be the efficient method that enable of release the trachea maximally. And it should be expected that the SH R technique is applicable clinically.