• Applied Biological Chemistry
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• 제44권4호
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• pp.257-261
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• 2001

Leather (skin & hide) is a body organ, comprising 3 to 5% of the animals weight. The cross-section of a leather is composed of two major divisions: the epidermis or grain layer and the corium or split layer. The leather is naturally covered with bacteria and fungi, because it is a particularly rich source of a wide variety of microorganisms. Stains or coatings of different colours occur in patches or over large areas, depending on the type of mould spore infestation. We examined the antibiotic effect of leather after washing. Upon applying equal fungicide, antibiotic effects increased as follows: grain layer>middle layer>flesh layer. Antibiotic effect decreased with increasing frequency of washing. Decrease in antibiotic effect was lower in OITZ fungicide than in TCMTB and CMK fungicides. Sulfated fatliquor showed higher antibiotic effect than phosphated fatliquor.

• Journal of Korean Society of Transportation
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• 제23권2호
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• pp.37-50
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• 2005

This study analyzes the effect of airport investment on GRDP(Gross Regional Domestic Product) using Regional Production Function with public investment on social infrastructure. Particularly it includes the spillover effect of airport investment on the economies of neighbor regions beyond border. We estimate regional production function with the independent variable of airport investment stock using panel data with regional cross-section and time-series data. In the analysis with aggregate data of all industries, it shows the positive relationship between airport investment and GRDP which implies the affirmative effect of airport investment on regional economy in the aspects of direct and indirect spill-over effects. On the contrary, the research results of each industry do not appear to be the same. With the different characteristics of each industry, the direct and indirect effect may not be the same and the SOC investment contributes to the restructuring of regional economy by altering the industrial organizations of any specific region and its neighbors.

• The Korean Journal of Pain
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• 제37권3호
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• pp.211-217
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• 2024

Background: Tolerance to the analgesic effects of opioids and non-steroidal anti-inflammatory drugs (NSAIDs) is a major concern for relieving pain. Thus, it is highly valuable to find new pharmacological strategies for prolonged therapeutic procedures. Biguanide-type drugs such as metformin (MET) are effective for neuroprotection and can be beneficial for addressing opioid tolerance in the treatment of chronic pain. It has been proposed that analgesic tolerance to NSAIDs is mediated by the endogenous opioid system. According to the cross-tolerance between NSAIDs, especially sodium salicylate (SS), and opiates, especially morphine, the objective of this study was to investigate whether MET administration can reduce tolerance to the anti-nociceptive effects of SS. Methods: Fifty-six male Wistar rats were used in this research (weight 200-250 g). For induction of tolerance, SS (300 mg/kg) was injected intraperitoneally for 7 days. During the examination period, animals received MET at doses of 50, 75, or 100 mg/kg for 7 days to evaluate the development of tolerance to the analgesic effect of SS. The hot plate test was used to evaluate the drugs' anti-nociceptive properties. Results: Salicylate injection significantly increased hot plate latency as compared to the control group, but the total analgesic effect of co-treatment with SS + Met50 was stronger than the SS group. Furthermore, the effect of this combination undergoes less analgesic tolerance over time. Conclusions: It can be concluded that MET can reduce the analgesic tolerance that is induced by repeated intraperitoneal injections of SS in Wister rats.

• Journal of Digital Convergence
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• 제18권6호
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• pp.513-522
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• 2020

The purpose of this study is to analyze the auto-regression effect between the elderly's assets and depression and life satisfaction, and to approach the influence of assets and depression on the elderly's life from a longitudinal perspective. For this purpose, the data for the 9th year (2014), 11th year (2016), and 13th year (2018) of the Korea Welfare Panel were used. As a result of the analysis, First, the assets, depression and life satisfaction of the elderly have a lasting effect on the passage of time, and the assets, depression and life satisfaction of the previous point in time (B=.694, B=.725, p<.001), depression (B=.258, B=.331 and p<.001) and life satisfaction (B=.264, B=.265, p<.001). Second, cross-recursion coefficients show how the relationship between the assets of the elderly and depression and the satisfaction of life affects each other over time, and the assets of the older person at the previous point in time (B=.010, B=.011, p<.001), the assets of the older persons at previous times are subsequently satisfied with their lives (B=.128, B=.124, p<.001). Based on the results of the above analysis, it is necessary to support the elderly's asset management service and education to prevent depression, such as continuous asset utilization education.

• Corrosion Science and Technology
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• 제9권4호
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• pp.147-152
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• 2010

Conventional paints for conversion coating applications in steel production derived mainly from water-based polymer dispersions containing several additives actually show good general performance, but suffer from poor scratch and abrasion resistance during use. The reason for this is because the relatively soft organic binder matrix dominates the mechanical surface properties. In order to maintain the high quality and decorative function of coated steel sheets, the mechanical performance of the surface needs to be improved significantly. In fact the wear resistance should be enhanced without affecting the optical appearance of the coatings by using appropriate nanoparticulate additives. In this direction, nanocomposite coating compositions (Nanomer$^{(R)}$) have been derived from water-based polymer dispersions with an increasing amount of surface-modified nanoparticles in aqueous dispersion in order to monitor the effect of degree of filling with rigid nanoparticles. The surface of nanoparticles has been modified for optimum compatibility with the polymer matrix in order to achieve homogeneous nanoparticle dispersion over the matrix. This approach has been extended in such a way that a more expanded hybrid network has been condensed on the nanoparticle surface by a hydrolytic condensation reaction in addition to the quasi-monolayer type small molecular surface modification. It was expected that this additional modification will lead to more intensive cross-linking in coating systems resulting in further improved scratch-resistance compared to simple addition of nanoparticles with quasi-monolayer surface modification. The resulting compositions have been coated on zinc-galvanized steel and cured. The wear resistance and the corrosion protection of the modified coating systems have been tested in dependence on the compositional change, the type of surface modification as well as the mixing conditions with different shear forces. It has been found out that for loading levels up to 50 wt.-% nanoparticles, the mechanical wear resistance remains almost unaffected compared to the unmodified resin. In addition, the corrosion resistance remained unaffected even after $180^{\circ}$ bending test showing that the flexibility of coating was not decreased by nanoparticle addition. Electron microscopy showed that the inorganic nanoparticles do not penetrate into the organic resin droplets during the mixing process but rather formed agglomerates outside the polymer droplet phase resulting in quite moderate cross linking while curing, because of viscosity. The proposed mechanisms of composite formation and cross linking could explain the poor effect regarding improvement of mechanical wear resistance and help to set up new synthesis strategies for improved nanocomposite morphologies, which should provide increased wear resistance.

• Korea journal of population studies
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• 제20권2호
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• pp.135-159
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• 1997

Education effect on women's participation in the labor market has been known to be small in Korea. Then, the meaning of women's education as human capital needs to be questioned. Both the increasing desire for working among women and the criticism to under-utilization of women's education in the labor market reflect that women's education is surely perceived as human capital. However, women's education dose not seem to function well as human capital in the labor market. According to previous studies, it is pointed out that educational effect on women's participation in the labor market is weak but the effect on earnings is evident. There were few attempts to evaluate economic returns to women's education over the life-cycle analyzing both working and non-working women. Considering that the economic behaviors of women in nonagricultural sector have changed little until the mid-1980s, I tried to examine the meaning of education as human capital over the women's life cycle using cross - sectional data. This study shows that the educational effect on women's participation in the labor market does not exist and the working period is very short. Although the educational effect on earnings among working women is clearly shown, it tends to limited to younger women. Despite the educational effect on earnings among younger women, the meaning of education as human capital among Korean women does not hold well due to short working period and the low participation of the educated in the labor market.

• Restorative Dentistry and Endodontics
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• 제20권2호
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• pp.508-526
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• 1995

This experiment was performed to study mechanisms of desensitization by chemical desensitizing agents in hypersensitive dentin and compare effects of these agents by measuring the activity of intradental nerves and observing their occluding aspects on dentinal tubules with SEM over time after application of chemical desensitizing agents to the exposed dentinal surfaces. Canines of adult cats weighing 2-3 kg were cross-sectioned at 1.5 mm from incisal apex, and the smear layer of the exposed dentinal susface was removed by 32 % $H_3PO_4$ for 15 sec. Chemical desensitizing agents such as 10% $SrCl_2$, 5% $KNO_3$ and 30% $K_2C_2O_4$, were applied to the exposed dentin surfaces for 2 minutes. Intradental nerve activity was measured immediately after application of the agents, at 15 minutes and at 30 minutes by stimulating with 4M NaCl. To compare occluding ability of desensitizing agents on dentinal tubules in vivo and in vitro, the structures of the exposed dentinal surfaces of nonvital and vital teeth were morphologically observed by SEM. The results obtained were as follows : 1. Intradental nerve activity was decreased immediately after the application of 10 % $SrCl_2$, 5% $KNO_3$ and 30% $K_2C_2O_4$. (p<0.01), among which 30% $K_2C_2O_4$. showed the highest desensitizing effect(p<0.01). 2. The immediately decreased intradental nerve activity after application of 10 % $SrCl_2$ and 5% $KNO_3$ was increased over time. 10% $SrCl_2$ and 5% $KNO_3$ showed no desensitizing effect respectively at 30 minutes and at 15 minutes after application. 3. The immediately decreased intradental nerve activity after application of 30 % $K_2C_2O_4$ was persistently continued during the period of observation (p<0.01). 4. Precipitates of $SrCl_2$ and $KNO_3$ were not noted on the exposed dentinal surfaces and within dentinal tubules by SEM examination. On the other hand, 30 % $K_2C_2O_4$ produced precipitates on the exposed dentinal surfaces and openings of dentinal tubules without any formed preciptates within dentinal tubules. 5. Ten percent $SrCl_2$, 5 % $KNO_3$ and 30 % $K_2C_2O_4$ showed no differences in their occluding aspects on dentinal tubules either in vivo or in vitro studies and either immediately following application or at 30 minutes. These results suggest that the desensitizing effect of $SrCl_2$ and $KNO_3$ is resulted from their reducing effect on the intradental nerve activity rather than from their precipitates' occluding the dentinal tubules. However, desensitizing effect of 30 % $K_2C_2O_4$, is probably resulted from its precipitates' occluding the openings of the dentinal tubules as well as from it's reducing effect on the intradental nerve actibity.

• Physical Therapy Korea
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• 제4권2호
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• pp.1-9
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• 1997

Skeletal muscle fatigue is often associated with diminished athletic performance and inability to maintain an expected force output as a function of time. The purpose of this study was to compare the effect of duration of exercise on skeletal muscle fatigue between Weight Lifters(WL) and Non-Weight Lifters(NWL). There were twelve normal healthy adult volunteers, ranging in age from 18 to 35 years. The group consisted of six NWL and six WL. Randomized cross-over design was set up and work-rest cycle was 8 minutes work and 1 minute rest based on 15% MVC. Muscle fatigue was measured by the amount of force produced by the wrist flexor muscle and EMG amplitude over time. Repeated measures ANOVAs($2{\times}4$) were used to determine two types of subjects(WL, NWL) during four different duration of exercises(16, 32, 48, 64 minutes). The force decreased over time in NWL and WL, but there was no significant difference(F=2.83, p>0.05). However, the EMG amplitude increased in WL(0.8200) and NWL(0.6348). The WL exhibited an increase in EMG at the end of the period, especially at 48 minutes of exercises than did the NWL(F=9.58, p<.05). This suggests the WL were able to adjust to prolonged effort with adaptations in neural effect over time, resulting in higher EMG amplitude. That is, WL may be able to learn to recruit more motor units with training. It is important to the degree of neuromuscular fatigue and the time needed for recovery may differ considerably between WL and NWL, there is a need to plan proper strength training or rehabilitation protocols to match with the requirements in different characteristics of groups.

• Journal of Information Technology Services
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• 제9권3호
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• pp.25-43
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• 2010

The speed and magnitude of mobile phone adoption is a recent worldwide phenomenon akin to those of the television in the middle of the 20th century and the Internet in the late 20th century. During the 2000s, mobile phone adoption was exploded and subscriptions reached 3 billion around the globe. Korea and Japan have been ahead of the rest of the world in introducing new handset and service capabilities. They were the first markets to launch 3G services and are currently the only markets to have achieved mainstream adoption of 3G with over one-third of customers in both markets subscribing to 3G services. The purpose of this article is to explore the cultural similarities and differences associated with mobile mail by presenting findings from a cross-cultural comparison of perceptions and uses of the technology. The results of the study are as follows：Of the characteristics that make up the mobile text-messaging service in Korea, a person's perceived ease of use and perceived enjoyment was found to have a positive effect on use attitude. Among the characteristics that make up a person's perceived ease of use, perceived enjoyment was found to have a positive effect on use intention. And use attitude was found to have positive effects on use intention. But, of the characteristics that make up the mobile text-messaging service in Japan, a person's perceived usefulness, perceived ease of use and perceived enjoyment were found to have a positive effect on use attitude. Among the characteristics that make up a person's perceived usefulness, perceived ease of use and perceived enjoyment were found to have a positive effect on use intention. And use attitude was found to have positive effects on use intention. This study contributes to telecommunications research by delineating the various stimuli to consider for successful technology acceptance in a global setting, which can account for differential impacts across regions. The findings of this study can assist telecommunications operators in formulating an effective region-specific strategy when launching a wireless data service in a particular environment.

• The korean journal of orthodontics
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• 제53권6호
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• pp.374-392
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• 2023

Objective: Assess and evaluate the different indicators of oral health-related quality of life (OHRQoL) among patients treated with clear aligners (CAs) versus those treated with conventional fixed orthodontics (FAs). Methods: An electronic search was performed on the database is Web of Science, Scopus, and Embase databases. Randomized and non-randomized control trials, cross-sectional, prospective cohort and retrospective trials were included. Quality was assessed with risk of bias tool and risk of bias in non-randomised studies. Meta-analyses were performed with random effects models, estimating the standardized and non-standardized mean differences, odds ratio and risk ratio as the measure of effect. The effect on time was determined using a meta-regression model. Results: Thirty one articles were included in the qualitative synthesis and 17 in the meta-analysis. CAs had a significantly lower negative impact on QoL, with an "important" effect size, while the influence of time was not significant. Periodontal indicators plaque index (PI), gingival index (GI), probing depth (PD), and bleeding on probing show significantly better values in patients treated with CAs, with moderate to large effect sizes. PI and GI have a significant tendency to improve over time. In microbiological indicators, CAs present a lower biofilm mass without differences in the percentage of patients with high counts of Streptococcus mutans and Lactobacilli bacteria. The risk of white spot lesion onset is ten times lower in carriers of CAs. Conclusions: Patients wearing CAs show better periodontal indicators, less risk of white spot development, less biofilm mass and a better QoL than patients with FAs.