• Advanced Composite Materials
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• v.17 no.2
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• pp.157-166
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• 2008

In this study, multiwalled carbon nanotubes (MWCNTs) were compounded with the poly($\varepsilon$-caprolactone) (PCL) matrix at the solution state using chloroform. For homogeneous dispersion of MWCNTs in polymer matrix, oxygen-containing groups were introduced on the surface of MWCNTs. The mechanical properties of the PCL/MWCNTs composites were effectively increased due to the incorporation of MWCNTs. The composites were characterized using scanning electron microscopy in order to obtain information on the dispersion of MWCNT in the polymeric matrix. In case of 1.2 wt% of MWCNTs in the matrix, strength and modulus of the composite increased by 12.1% and 164.3%, respectively. In addition, the dispersion of MWCNTs in the PCL matrix resulted in substantial decrease of the electrical resistivity of the composites as the MWCNTs loading was increased from 0 to 2.0 wt%. Furthermore, thermal stability of the PCL and PCL/MWCNTs-COOH composites were investigated using the data acquired from the thermogravimetric analysis. The detailed kinetics of the thermal degradation of the composites was investigated by analyzing their thermal behavior at different heating rates in a nitrogen atmosphere. Activation energy of thermal degradation was determined by using the equations proposed by Kissinger and Flynn-Wall-Ozawa. The apparent activation energy of PCL/MWCNTs-COOH composite was considerably higher than that of neat PCL.

• Physical Therapy Rehabilitation Science
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• v.6 no.1
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• pp.1-6
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• 2017

Objective: There are many types of exercises with upper and lower-limb action for activation of abdominal muscles for trunk stabilization. A comparison of the different exercise methods been very useful to enhance the result from the exercise for treatment. The purpose of this study was to investigate through surface electromyography (EMG) the changes in abdominal muscle activity during the performance of three different dead-bug exercise methods performed at three different speeds. Design: Cross-sectional study. Methods: The subjects were 30 healthy adults (13 males and 17 females). We instructed the subjects to perform three different dead-bug exercises. We also applied three different speeds to the dead-bug exercises; 60 bpm, 90 bpm, and 120 bpm with use of a metronome. The assessment of EMG was percentage of maximal voluntary isometric contraction on the rectus abdominis (RA), external oblique (EO), and internal oblique (IO). Results: EMG activation of the RA, EO and IO muscles was significantly greater at the higher speed (p<0.05). There was a significant increase in abdominal muscle activity during the dead-bug exercise performed with both the upper and lower extremities compared to that with only the upper extremity or the lower extremities (p<0.05). Conclusions: These findings demonstrate that the performance of the dead-bug exercise with both the upper and lower extremities combined at a high speed is more effective compared to other exercises. Therefore, it is suggested that more favourable and effective outcomes may occur when the type and speed of the exercise is chosen appropriately.

• Physical Therapy Rehabilitation Science
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• v.7 no.1
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• pp.41-47
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• 2018

Objective: To investigate the effect of performing three different toe touch (TT) task condition on the activities of four different muscles using surface electromyography (sEMG) in healthy young adults. Design: Cross-sectional study. Methods: A total of 20 healthy young adults (6 males, 14 females) voluntarily participated in this study. All subject randomly performed three different TT task conditions as follows: general toe-touch (GTT) task, one side toe touch (TT) task during weight bearing, and one side foward toe touch (FTT) task during weight bearing. The muscle activities of erector spinae (ES), gluteus maximus (GM), hamstring (HAM), tibialis anterior (TA) muscles during the TT task were measured using sEMG. Subject performed each of the three conditions three time in random order and mean values were obtained. Results: With the trunk flexion period, the TT and FTT showed significantly greater muscle activity in the GM, HAM and TA compared to the GTT task (p<0.05). The TT position showed significantly greater HAM muscle activity than the GTT position. The dominant and nondominant ES muscle activity was significantly greater in the FTT compared to the GTT position (p<0.05). The dominant GM, HAM, and TA was significantly greater in the TT and FTT compared to the GTT position (p<0.05). Although the dominant ES was significantly greater in the TT and FTT compared to the GTT position (p<0.05), the dominant GM muscle activity was signifcantly greater in the TT compared with the GTT position (p<0.05). Conclusions: These findings may be applicable within the clinical field for selective trunk and lower extremity muscle activation and basic biomechanics purpose.

• Physical Therapy Rehabilitation Science
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• v.9 no.2
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• pp.113-119
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• 2020

Objective: The vibration device is one of the most commonly used warm-up devices not only for healthy athletes but also for healthy individuals. Therefore, this study aimed to investigate the immediate effects of local vibration on ankle plantar flexor muscle activation and peak torque in healthy adults. Design: One-group pretest-posttest design. Methods: This was a single-group study comprising a total of 36 (16 males and 20 females) participants. The average age of the 36 participants was 22.3 years. All the participants' concentric and eccentric peak torques of the gastrocnemius lateralis muscle were measured using an isokinetic device. Simultaneously, the participants' muscle activity was measured by surface electromyography. After the pre-experimental data were collected, the participants comfortably sat on the prepared chair with their hips and knees flexed to 90°. While in sitting position, local vibration was applied for 10 minutes using a 1:1 ratio intermittent pulsing mode device based on a previous study. Then, the post-experimental data were collected immediately after the local vibration by performing a similar process performed during the pre-experimental data collection. Results: The results showed a significant difference in muscle activity and eccentric peak torque (p<0.05). On the contrary, concentric peak torque values showed an insignificant difference with pre- and post-value. Conclusions: The results of this study demonstrated that local vibration can be possibly considered as one of the effective ways to increase ankle plantar flexor muscle activity and muscle performance, specifically the eccentric peak torque, in healthy adults.

• IMMUNE NETWORK
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• v.9 no.3
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• pp.98-105
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• 2009

Background: It has been recently noticed that type 2 diabetes (T2D), one of the most common metabolic diseases, causes a chronic low-grade inflammation and activation of the innate immune system that are closely involved in the pathogenesis of T2D. Cordyceps militaris, a traditional medicinal mushroom, produces a component compound, cordycepin (3'-deoxyadenosine). Cordycepin has been known to have many pharmacological activities including immunological stimulating, anti-cancer, and anti-infection activities. The molecular mechanisms of cordycepin in T2D are not clear. In the present study, we tested the role of cordycepin on the anti-diabetic effect and anti-inflammatory cascades in LPS-stimulated RAW 264.7 cells. Methods: We confirmed the levels of diabetes regulating genes mRNA and protein of cytokines through RT-PCR and western blot analysis and followed by FACS analysis for the surface molecules. Results: Cordycepin inhibited the production of NO and pro-inflammatory cytokines such as IL-$1{\beta}$, IL-6, and TNF-${\alpha}$ in LPS-activated macrophages via suppressing protein expression of pro-inflammatory mediators. T2D regulating genes such as $11{\beta}$-HSD1 and PPAR${\gamma}$ were decreased as well as expression of co-stimulatory molecules such as ICAM-1 and B7-1/-2 were also decreased with the increment of its concentration. In accordance with suppressed pro-inflammatory cytokine production lead to inhibition of diabetic regulating genes in activated macrophages. Cordycepin suppressed NF-${\kappa}B$ activation in LPS-activated macrophages. Conclusion: Based on these observations, cordycepin suppressed T2D regulating genes through the inactivation of NF-${\kappa}B$ dependent inflammatory responses and suggesting that cordycepin will provide potential use as an immunomodulatory agent for treating immunological diseases.

• Analytical Science and Technology
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• v.16 no.3
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• pp.232-239
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• 2003

The river sediments were collected from 4 points of Seoknam river, one point of Miho river and one point of the joining area of two rivers. For preparation of sample, three sediment samples were collected for the surface, middle and lower part of the sediment at each sampling point. The elemental concentrations were analyzed by neutron activation analysis using HANARO research reactor at Korea Atomic Energy Research Institute, and the concentrations of 30 elements were determined by the relative method using standard reference material of NIST. As a result of analysis, it was found that when the examination and prediction of contamination distribution about the site where the contamination site of river is connected to the lower river is done, the specific gravity of elements which is contained in the sediment and the speed of a current of river should be considered and also found that when the samples for concentration analysis in the river sediments are collected, for the establishment of regional representatives in samples, the range of sampling depth should be determined considering the specific gravity of elements and the speed of a current.

• Resources Recycling
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• v.25 no.3
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• pp.74-81
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• 2016

Study on chlorination of ilmenite ore were carried out by using PVC(polyvinyl chloride) as the chlorinating agent in a static bed reactor for selective removal of iron. The effect of amount of PVC and reaction temperature were investigated. It was found that the removal ratio of iron increased with amount of PVC and temperature. After reaction with HCl gas generated from PVC, porous surface of the specimens were observed. As a result, HCl gas could react with iron in the central portion of ilmenite particle through these pores. Examination of data using kinetic model suggest that the selective chlorination rate is controlled by chemical reaction at the interface of particles. The activation energy for the selective chlorination of ilmenite using PVC was calculated as 20.47 kJ/mol.

• Resources Recycling
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• v.17 no.1
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• pp.20-28
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• 2008

Leather waste discharged from Shinpyung Changrim Industrial Complex contained 46.3 percent of carbon, and weight loss of leather waste about 50 percent was observed at $500^{\circ}C$ by thermogravimetric analysis. Chemically activated carbon [LW4AC] was made at activation temperature of $800^{\circ}C$ during 30 minutes in electric furnace. Iodine value and decoloration of methylene blue was 968 mg/g and 158 mL/g, respectively. We found that pore volume was more developed according to the increase in the ratio of $K_2CO_3/LW$.

• Bulletin of the Korean Chemical Society
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• v.15 no.12
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• pp.1058-1064
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• 1994

Mn/In$_2O_3$ systems with a variety of Mn mol${\%}$ were prepared to investigate the effect of Mn-addition on the catalytic activity of Mn/In$_2O_3$ in the oxidative coupling of methane. The oxidative coupling of methane was examined on pure In$_2O_3$ and Mn/In$_2O_3$ catalysts by cofeeding gaseous methane and oxygen under atmospheric pressure between 650 and 830 $^{\circ}C$. Although pure In$_2O_3$ showed no C$_2$ selectivity, both the C$_2$ yield and the C$_2$ selectivity were increased by Mn-doping. The 5.1 mol${\%}$ Mn-doped In$_2O_3$ catalyst showed the best C$_2$ yield of 2.6${\%}$ with a selectivity of 19.1${\%}$. The electrical conductivities of pure and Mn-doped In$_2O_3$ systems were measured in the temperature range of 25 to 100 $^{\circ}C$ at PO$_2$'S of 1 ${\times}$ 10$^{-7}$ to 1 ${\times}$ 10 $^{-1}$ atm. The electrical conductivities were decreased with increasing Mn mol${\%}$ and PO$_2$, indicating the specimens to be n-type semiconductors. Electrons serve as the carriers and manganese can act as an electron acceptor in the specimens. Manganese ions doped in In$_2O_3$ inhibit the ionization of neutral interstitial indium or the transfer of lattice indium to interstitial sites and increase the formation of oxygen vacancy, giving rise to the increase of the concentration of active oxygen ion on the surface. It is suggested that the active oxygen species adsorbed on oxygen vacancies are responsible for the activation of methane.

• Physical Therapy Rehabilitation Science
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• v.7 no.2
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• pp.72-77
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• 2018

Objective: This study aimed to compare the effects of core exercise methods on muscle activation and muscle thickness in healthy young adults and to propose effective core exercise methods. Design: Three-group pretest-posttest design. Methods: A total of 30 healthy young adults (14 males, 16 females) voluntarily participated in the study. Subjects were randomized to the prone plank exercise (n=10), reverse plank exercise (n=10), or bridge exercise (n=10) groups. Muscle activity and thickness of the rectus abdominis (RA), multifidus (MF), external oblique (EO), and internal oblique (IO) muscles were measured using surface electromyography and ultrasound. Subjects from each group participated in the exercises five times a week, with five 20-second sets during week 1. The set time was increased by 10 seconds per week. Results: Muscle activity and thickness in the prone plank, reverse plank, and bridge exercise group were statistically significant different for RA, MF, EO, and IO changes over time, and interaction between time and groups were also significantly different (p<0.05). We analyzed statistically significant differences between groups using a one-way analysis of variance for each period. A significant difference was observed after 4 weeks of exercise (p<0.05). Conclusions: The results suggest that the prone plank exercise is a beneficial method for enhancing muscle activation and thickness of the RA, EO, and IO compared to the reverse plank and bridge exercises. On the other hand, the reverse plank and bridge exercises are effective methods for enhancing the MF compared to the prone plank exercise.