• Biomolecules & Therapeutics
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• v.31 no.2
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• pp.168-175
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• 2023

Tramadol is an opioid analog used to treat chronic and acute pain. Intradermal injections of tramadol at hundreds of millimoles have been shown to produce a local anesthetic effect. We used the whole-cell patch-clamp technique in this study to investigate whether tramadol blocks the sodium current in HEK293 cells, which stably express the pain threshold sodium channel Na_v1.7 or the cardiac sodium channel Na_v1.5. The half-maximal inhibitory concentration of tramadol was 0.73 mM for Na_v1.7 and 0.43 mM for Na_v1.5 at a holding potential of -100 mV. The blocking effects of tramadol were completely reversible. Tramadol shifted the steady-state inactivation curves of Na_v1.7 and Na_v1.5 toward hyperpolarization. Tramadol also slowed the recovery rate from the inactivation of Na_v1.7 and Na_v1.5 and induced stronger use-dependent inhibition. Because the mean plasma concentration of tramadol upon oral administration is lower than its mean blocking concentration of sodium channels in this study, it is unlikely that tramadol in plasma will have an analgesic effect by blocking Na_v1.7 or show cardiotoxicity by blocking Na_v1.5. However, tramadol could act as a local anesthetic when used at a concentration of several hundred millimoles by intradermal injection and as an antiarrhythmic when injected intravenously at a similar dose, as does lidocaine.

• International Journal of High-Rise Buildings
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• v.12 no.1
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• pp.93-105
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• 2023

Seismic isolation and vibration control techniques have been developed and put into practical use by challenging researchers and engineers worldwide since the latter half of the 20th century, and after more than 40 years, they are now used in thousands of buildings, private residences, highways in many seismic areas in the world. Seismic isolation and vibration control structures can keep the structures undamaged even in a major earthquake and realize continuous occupancy. This performance has come to be recognized not only by engineers but also by ordinary people, becoming indispensable for the formation of a resilient society. However, the dynamic characteristics of seismically isolated bearings, the key elements, are highly dependent on the size effect and rate-of-loading, especially under extreme loading conditions. Therefore, confirming the actual properties and performance of these bearings with full-scale specimens under prescribed dynamic loading protocols is essential. The number of testing facilities with such capacity is still limited and even though the existing labs in the US, China, Taiwan, Italy, etc. are conducting these tests, their dynamic loading test setups are subjected to friction generated by the large vertical loads and inertial force of the heavy table which affect the accuracy of measured forces. To solve this problem, the authors have proposed a direct reaction force measuring system that can eliminate the effects of friction and inertia forces, and a seismic isolation testing facility with the proposed system (E-isolation) will be completed on March 2023 in Japan. This test facility is designed to conduct not only dynamic loading tests of seismic isolation bearings and dampers but also to perform hybrid simulations of seismically isolated structures. In this paper, design details and the realization of this system into an actual dynamic testing facility are presented and the outcomes are discussed.

• Fashion & Textile Research Journal
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• v.25 no.4
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• pp.497-507
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• 2023

This study measured the effect 3D printing products comprised of different materials and shapes on heat transfer in clothing to derive fundamental data on thermal comfort among clothing comfort. The variables were three types of material (EVA foam, TPU-10%, TPU-10%+EVA), two types of shape (without holes, with holes), and two types of covers(without cover, with cover). All samples (12 types) prepared by combining these variables were placed on the hot plate set at 36℃, and the surface temperature was measured at three points for 10 minutes. The surface temperature change was dependent on the material, shape, and cover of the sample. The sample printed with TPU exhibited higher temperature transfer compared to the EVA foam sample after 10 mins. In addition, the temperature transfer was better when there were holes, and rate decreased when the sample was covered with fabric. We confirmed that material selection of the pad and thermal conductivity of the cover are extremely important in solving thermal stress to the human body caused by functional clothing with protectors. Additionally, as the protector, it is recommended to design the outer shell with a passage, such as a hole, to allow the rapid transfer of heat to the external environment.

• Journal of The Korean Society of Integrative Medicine
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• v.11 no.2
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• pp.149-157
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• 2023

Purpose : In this study, to prove the antibacterial effect of Disocorea batatas, which is widely used for food, and to confirm the growth inhibitory effect, the antibacterial activity against L. gasseri, S. mutans, and P. gingivalis was verified. Based on this, it is intended to verify the utility as a preventive and therapeutic composition for dental caries and periodontal disease. Methods : RAW 264.7 cells were used to verify the cell survival rate and NO (Nitric Oxide) inhibitory effect on Disocorea batatas ethanol extract (DBEE). In order to verify the antibacterial effect against L. gasseri, S. mutans, and P. gingivalis, concentrations of 125, 250, and 500 ㎎/㎖ of DBEE were used and measured by the disk diffusion method. In order to confirm the growth inhibitory effect, the absorbance was measured at 600 ㎚ at 3, 6, 12, 18, and 24 hours using the liquid medium dilution method, and the growth inhibitory effect was measured compared to the control group. Results : The cell viability for DBEE was 91 % at 50 ㎎/㎖, and there was no cytotoxicity. The NO production inhibitory effect was shown from 10 ㎍/ml, and the higher the concentration, the greater the inhibitory effect. As for the antimicrobial effect using the disk diffusion method, the higher the concentration, the higher the antibacterial effect. At 125 ㎎/㎖ and 250 ㎎/㎖, S. mutans and L. gasseri showed high antimicrobial activity, and at 500 ㎎/㎖, the antibacterial effect was higher in L. gasseri. The growth inhibitory effect in DBEE was concentration-dependent as the higher the concentration, the higher the growth inhibitory effect, and all of them began to show growth inhibitory effects from 6 hours. Conclusion : Considering that it is widely used as an edible and medicinal material, Disocorea batatas has shown the potential to be used as a substance to prevent and alleviate dental caries and periodontal diseases, and it is believed that further research can be applied to oral health care products.

• Korea Trade Review
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• v.43 no.1
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• pp.177-197
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• 2018

This paper aims to analyze the effects of external uncertainty on the entry modes decision of multinational firms. On the basic assumption that the entry modes of the firms are dependent on ex-ante or ex-post perceived risk, we empirically analyzed the impacts of perceived risk factors on the investment patterns of firms. We found that the larger the population, the higher the level of GDP per capita, and the larger the trade volume as a ratio of GDP resulted in increased M&A FDI and greenfield FDI. The economic growth rate variables were found to be significantly positive effect on only greenfield entry mode. Regarding the main variables, lower levels of corruption and increased stability regarding political issues resulted in the host country receiving increased M&A investment. However, we found only a positive statistical significance of the political stability variable on the explaining greenfield FDI. Results show that M&A entry mode is affected by both corruption and political instability level. However, the greenfield FDI featuring sunk costs, seems more responsive to political instability.

• 한국벤처창업학회:학술대회논문집
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• 2021.04a
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• pp.33-42
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• 2021

Based on the findings of Lee et al.(2020) and Lee & Oh(2021), this paper aims to fill the gap in our knowledge regarding the relationship between strategic choices and corporate growth by utilizing a novel dataset of 'Unicorn' and 'Hyper-growing' companies. Two previous studies provide coherent findings that the relationship between firms' strategies and their performance should be explored under a more comprehensive framework with consideration of both internal and external factors. Therefore, in this study, we apply a single conceptual framework to two different datasets, which considers the strategy factors as independent variables, and the industry(market) and the firm age as moderating variables. For our dependent variables, valuations for unicorn companies and revenue CAGR for hyper-growing companies are used after categorizing them into three uniform groups. The strategy variables include 'Generic (Cost-leadership, Differentiation, focus) strategies', 'Growth(Organic, M&A) strategies', 'Leading(Pioneer, Fast-follower) strategies', 'Target market(B2B, B2C, B2G, C2C) strategies', 'Global(Global, Local) strategies', 'Digital(Online, Offline) strategies.' For industry(market) factors, it consists of historical growth rate for industries and economic, demographic, and regulatory aspects of states and countries. To overcome the differences in their units, they are also uniformly categorized into multiple groups. Before we conduct a regression analysis, we analyze the industry distribution of the 'Unicorn' and the 'Hyper-growing' companies with descriptive statistics at the integrated and individual levels. Next, we employ hierarchical regression models on Study A('Unicorn' companies in 2019) and Study B('Hyper-growing' companies in 2019) under the same comprehensive framework. We then analyze the relationship between the 'strategy' and the 'performance' factors with two different approaches: 1) an integrated regression model with both the sample of Study A and B and 2) respective regression models on Study A and B. This empirical study aims to provide a complete understanding and a reference to which strategy factors should be considered to promote firms' scale-up and growth.

• Journal of dental hygiene science
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• v.23 no.2
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• pp.132-141
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• 2023

Background: The purpose of this study was to identify the connection between handwashing and toothbrushing, focusing on eating habits, and to verify whether eating habits can be used as an action cue for forming health habits. Methods: This was a cross-sectional study using secondary data from the 2019 community health survey. The participants included 229,099 adults aged 19 years or older, representative of the South Korean people. We employed two dependent variables: one was washing hands, and the other was brushing teeth. Eating habits was a major independent variable. Socioeconomic variables, such as age, gender, income, occupation, economic activity, education, and residence were adjusted as confounders. Multivariate logistic regression was performed to calculate adjusted odds ratio and 95% confidence intervals. Results: Most of the participants had good health behaviors: those who wash their hands and brush their teeth were each approximately 80%. Our finding indicated that brushing teeth and washing hands can be connected with eating habits. After adjusting for confounders, it was found that people who wash their hands before meals (compared to those who did not wash their hands before meals) had a higher toothbrushing rate after meals (i.e., socioeconomic status) (Adjusted Odds Ratio: 2.0, Confidence Intervals: 1.9 to 2.1). Conclusion: Those who practice either washing hands before meals or brushing teeth after meals were found to have a connection between washing hands and brushing teeth based on the results of practicing other health behaviors. This implies that eating habits can be connected as a behavior cue to promote health habits, such as washing hands before meals and brushing teeth after meals.

• The Journal of the Korea Contents Association
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• v.22 no.5
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• pp.424-434
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• 2022

This study is to verify the mediating effect of self-esteem on the effect of the elderly's smart device use on life satisfaction. To this end, secondary data analysis was conducted using the Korea Media Panel Survey conducted by the Information and Communication Policy Institute in 2021. The responses of 3,211 people in their 60s or older who are the subjects of this study were utilized. For analysis, descriptive statistics, correlation, and multiple regression analysis were performed using SPSS, and the Sobel test was conducted to verify mediating effects. As a result, smart device utilization averaged 2.13 points out of 5, indicating that the actual utilization level was less than half. The use of smart devices, an independent variable, had a positive effect on the dependent variable, life satisfaction. Self-esteem, which is a parameter, has been verified as a partial mediating effect in that smart device use affects life satisfaction. Based on the results of this study, various policy and practical measures were proposed to increase the smart device utilization rate of the elderly in Korea, improve self-esteem and life satisfaction, so that they can spend a happy old age.

• Korean Journal of Exercise Nutrition
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• v.23 no.2
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• pp.45-50
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• 2019

[Purpose] The purpose of this study was to confirm that the difference in excess post-exercise oxygen consumption (EPOC) during exercise of the spending the same calories between the continuous and interval exercise. [Methods] Thirty-four healthy college students who did not regularly exercise volunteered to participate in our study. Continuous exercise was performed on an ergometer for 30 min at 60% of maximal oxygen consumption (VO_{2 max}). Interval exercise was performed on a cycle ergometer at 80% VO_{2 max} for 2 min initially, followed by 40% VO_{2 max} for 1 min, and 80% VO_{2 max} for 3 min. This was repeated six times for a total of 26 min. [Results] The major findings were as follows: (1) energy consumption during exercise was not significantly different between continuous exercise and interval exercise groups; (2) EPOC was higher in interval exercise than in continuous exercise for all dependent variables (i.e., total oxygen consumption, total calories, summation of heart rate); and (3) there were no significant differences in the lipid profile between continuous and interval groups. [Conclusions] Our study confirmed that after equalizing energy expenditure for continuous and interval exercise on a cycle ergometer in subjects in their twenties, interval exercise results in higher EPOC than continuous exercise. These data suggest that interval exercise may be more effective than continuous exercise in reducing body fat, for a given amount of energy expenditure.

• Biomedical Science Letters
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• v.29 no.4
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• pp.321-329
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• 2023

Anaplastic thyroid cancer has the highest mortality rate of all thyroid cancers and shows low responsiveness to most treatments. Hongyoung, a reddish-colored potato, is an excellent source of dietary polyphenol containing a large amount of anthocyanins, which has anti-cancer and anti-inflammatory effects. This study investigated the effects of Hongyoung extract on apoptosis and invasiveness in SNU-80 anaplastic thyroid cancer cells. The quantification of the total polyphenol content was done by spectrophotometric measurement. Cell growth was measured by using 2-(2-methoxy-4-nitrophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl) 2H tetrazolium, monosodium salt (MTS) assay. Cell cycle was analyzed through FACS analysis. Induction of apoptosis in cells was investigated by annexin V staining using flow cytometer and the expression of caspase-3 and Poly (ADP-ribose) polymerase (PARP) through western blot. mRNA expression and protein activation of matrix metalloproteinases (MMP)-2/-9 were examined by RT-PCR and zymography. As a result, the TPC of Hongyoung was 292.43±8.42 mg gallic acid equivalent (GAE)/100 g dry extract. Hongyoung showed a dose-dependent cell growth inhibition, and the IC₅₀ values was 1,000 ㎍/mL. sub-G1 phase was more than doubled compared to the control group, and S and G2/M phase arrest were also induced. Hongyoung induced apoptosis by increasing FITC-Annexin V-positive cells and increased the activation of caspase-3 (cleaved caspase-3) and PARP (fragmented PARP). Hongyoung significantly inhibited mRNA expression and protein activation of MMP-2/-9 in phorbol 12-myristate 13-acetate (PMA)-treated SNU-80 cells. Therefore, this study suggests the possibility of development of Hongyoung extract as an anti-cancer agent.