• 전기화학회지
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• 제10권4호
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• pp.265-269
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• 2007

일산화탄소탈수소화효소를 이용한 이산화탄소의 전기화학적 환원 반응의 최적화를 위해 pH와 온도의 영향을 살펴보았다. pH는 이산화탄소의 환원반응 용이성과 효소의 안정도 효과가 함께 반영되는 6.3에서 최적의 조건을 보였고, 온도는 이산화탄소의 용해도가 적어지더라도 효소의 활성이 가장 좋은 60도에서 최적 조건을 보였다. 일산화탄소탈수소화효소의 안정성 및 활성이 가장 중요한 조건임을 알 수 있었다.

• The Korean Journal of Physiology
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• 제16권1호
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• pp.31-40
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• 1982

The present experiment was carried out to elucidate interrelation between the vestibular canals and the extraocular oblique muscles. In urethane anesthetized rabbits, excitatory or inhibitory effect of the canal was produced by three different methods; selective electrical stimulation of the ampullary nerve, bidirectional (ampullofugal or ampullopetal) lymphatic fluid flow, and rapid freezing of the canal. Changes of isometric tension as well as electro-myographic activity of the oblique muscles were recorded in the ipsilateral and contralateral eyes, by means of a polygraphic recorder, and the following results were obtained. 1) Electrical stimulation of a unilateral vertical or horizontal nerve caused contraction of superior oblique muscle and relaxation of inferior oblique muscle in the ipsilateral eye, and contraction of inferior oblique muscle and relaxation of superior oblique muscle in the contralateral eye. 2) Ampullofugal flow in a vertical canal and ampullopetal flow in a horizontal canal caused the oblique muscle responses which were identical to those responses produced by the electrical stimulation of the same canal nerve. 3) Rapid freezing of a vertical canal elicited the oblique muscle responses which were opposite to those caused by electrical stimulation of the same canal nerve. From the above experimental results, functional interrelation between the individual vestibular canal and bilateral extraocular oblique muscles were better elucidated. When these results were compared to those reported by previous investigators (Utzumi, Suzuki et al.), some important discrepancies were found between them. We ascribed such discrepancies to experimental errors of the previous investigators, since their results reflected theoretical contradictions in terms of vestibular eye movements.

• The Journal of Korean Physical Therapy
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• 제2권1호
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• pp.35-46
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• 1990

The right hip adbuctor musculature has been reported to demonstrate 'stretch weakness' attributable to chronic elongation imposed by standing posture common to right-handed healthy persons. Kendall and associates have described the concept of 'stretch weakness'. The purpose of this study was to assess isometric hip abduction torque and surface electro-myographic activity (using MYOMED 432) in a sample of 40 healthy right-handed persons (20 male, 20 female), all of whom agreed to participate in the study, and compare side difference in the hip abductor musculature. In order to assure the statistical significance of the results, the paired t-test was applied at the .05 level of significance. The results were as follows : 1. The difference in apparent leg length of right and left legs was significant at the .05 leve1. 2. There was a significant difference between right and left pelvic height (standing position) at the .005 level measurements, and scapula height at the .05 level. 3. Power measurements and action potentials of right hip adbuctor were greater than the left hip adbuctor regardless of the range of joint motion (inner range, outer range). 4. The difference in muscle power and action potentials according to inner or outer range of both hip abductor were significant at the .05 level. 5. In supine during active left hip abduction, the appearance of action potentials in the right hip abductors is indicative of contra-lateral effect (p<.005). These results suggest : In healthy right-handed persons. the apparent leg length on the right is longer than on the left, and pelvic height is elevated on the right side. Muscle torque and muscle action potentials of the right hip adbuctor art higher than those of the hip abductor in the lengthened position. Therefore, the results in this study are contrary to Kendall's. This type of study should be carried out in many physical therapy departments.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.403-403
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• 2010

The Pt-Ni alloy is an electro-catalyst of interest in the low temperature direct methanol fuel cells(DMFCs). It has been already reported that the Pt-Ni alloy catalysts may even have enhanced activity compared to pure platinum catalyst, depending on how the surfaces are prepared. The order-disorder transition in bimetallic alloy such as $\beta$-CuZn, Cu3Au, and CuAu have been investigated greatly by x-ray diffraction. After annealing the bimetallic alloy, the crystal structure changes as observed in the order-disorder transition of Cu3Au which changes from the face centered cubic to a simple cubic structure. Pt-Ni bimetallic alloy has been already reported to have the face centered cubic structure. However, in nano-scale Pt-Ni bimetallic alloy crystals the crystal structures changes to a simple cubic structure. In this experiment, we have studied the order-disorder transition in Pt-Ni bimetallic nanocrystals. Pt/Ni thin films were deposited on sapphire(0001) substrates by e-beam evaporator and then Pt-Ni alloy were formed by RTA at 500, 600, and $700^{\circ}C$ in a vacuum environment and Pt-Ni nano particles were formed by RTA at $1059^{\circ}C$ in a vacuum environment. We measured the structure of Pt-Ni bimetallic alloy films using synchrotron x-ray diffraction and SEM.

• 대한기계학회논문집A
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• 제25권6호
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• pp.996-1003
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• 2001

In order to investigate the fatigue fracture characteristics by corrosion degradation of 12Cr alloy steel, both the fatigue characteristics in air of them artificially degraded during long period and the corrosion fatigue characteristics were experimentally evaluated in various environments which were determined from electro-chemical polarization tests. And also, their fracture mechanisms were analyzed and compared, fractographyically. From their results, the fracture mechanical characteristics of it artificially degraded during long period in the distilled water, 3.5 wt.% NaCl solution and 12.7wt.%(1M) Na$_2$SO$_4$solution of 25, 60 and 90$\^{C}$ did not show distinguishable difference comparing with non-corroded one in regardless of temperature and degradation period. It means that degradation of the material by just surface corrosion does not remarkably affect to fatigue crack growth. On the other hand, the crack growth rates by corrosion fatigue increased due to activity increase of corrosive factors such as OH(sub)-,Cl(sup)- and SO$_4$(sup)- at the crack tip with temperature increase. Therefore, the crack growth rates by corrosion fatigue were more faster than that in air of the artificially degraded specimen due to the such difference of crack growth mechanism.

• The Korean Journal of Pain
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• 제34권4호
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• pp.437-446
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• 2021

Background: Non-invasive painless signaling therapy (NPST) is an electro-cutaneous treatment that converts endogenous pain information into synthetic non-pain information. This study explored whether pain improvement by NPST in failed back surgery syndrome (FBSS) patients is related to cerebral modulation. Methods: Electroencephalography (EEG) analysis was performed in 11 patients with FBSS. Subjects received daily NPST for 5 days. Before the first treatment, patients completed the Brief Pain Inventory (BPI) and Beck Depression Inventory and underwent baseline EEG. After the final treatment, they responded again to the BPI, reported the percent pain improvement (PPI), and then underwent post-treatment EEG. If the PPI grade was zero, they were assigned to the ineffective group, while all others were assigned to the effective group. We used standardized low-resolution brain electromagnetic tomography (sLORETA) to explore the EEG current-source distribution (CSD) associated with pain improvement by NPST. Results: The 11 participants had a median age of 67.0 years, and 63.6% were female. The sLORETA images revealed a beta-2 CSD increment in 12 voxels of the right anterior cingulate gyrus (ACG) and the right medial frontal area. The point of maximal CSD changes was in the right ACG. The alpha band CSD increased in 2 voxels of the left transverse gyrus. Conclusions: Pain improvement by NPST in FBSS patients was associated with increased cerebral activity, mainly in the right ACG. The change in afferent information induced by NPST seems to be associated with cerebral pain perception.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.143.1-143.1
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• 2010

고분자 전해질막 연료전지(Polymer Electrolyte Membrane Fuel Cell; PEMFC)는 수소를 이용하여 전기를 발생시키는 친환경적이고 이상적인 발전장치로 고효율과 높은 전류밀도를 가지며 그 응용분야가 다양하다. 저온에서 작동하는 PEM fuel cell은 전극에서 효과적인 산화환원반응을 위해 그 촉매로 활성이 우수한 Pt(Platinum)을 사용하고 있으나, Pt의 높은 가격은 연료전지의 상용화에 걸림돌이 되고 있다. 본 연구에서는 연료전지의 Pt/C 촉매 층에서 Pt의 분산성을 높여 Pt의 담지량을 줄이고 작동 중 발생하는 Pt의 응집 현상을 방지하여 Pt의 수명을 연장시킬 목적으로, Au(gold) 나노입자를 첨가한 Pt-Au/C 복합나노촉매를 제조하였다. 본 발표에서는 합성된 Pt-Au/C 복합촉매 중 Au 첨가량이 Pt 촉매의 활성에 미치는 영향을 조사하기 위하여, 복합촉매 중에 금속(Pt+Au)의 총 함량이 30 wt.%와 40 wt.% 인 Pt-Au/C 촉매에 대하여 각각 Au 첨가량을 변화시켜, cyclic voltammetry 법에 의해 Au 첨가 효과를 조사한 결과에 대하여 보고하고자 한다. Au 나노입자를 제조하기 위한 출발 물질로는 $HAuCl_4{\cdot}4H_2O$를 이용하였고 trisodium citrate와 $NaBH_4$를 환원제로 하여, 입경이 5~8 nm 인 Au 콜로이드를 제조하였다. Pt-Au/C 복합나노촉매를 제조하기 위하여 먼저 Au/C 복합분체가 제조되었다. 0.03g의 carbon이 첨가된 carbon 현탁액에 합성된 Au 콜로이드 수용액을 첨가한 후 24시간 동안 교반하여 Au/C 복합분체를 제조하였다. 이 Au/C 복합분체에 $H_2PtCl_6{\cdot}6H_2O$ 수용액을 현탁하고 methanol 을 환원제로 사용해 Pt를 환원 석출시켜 Pt-Au/C 복합촉매를 제조하였다. Pt-Au/C 복합 나노촉매에서 Pt와 Au를 다양한 비율(3:1, 2.5:1.5, 2:2)로 합성하였으며 Pt-Au/C 복합촉매 중 금속(Pt+Au) 촉매의 총 함량은 30 wt.%와 40 wt.%로 각각 제조되었다. Au 나노입자 콜로이드의 분산성은 UV-visible spectrum의 흡광도에 의해 관찰되었고, Pt-Au/C 복합 나노촉매의 형상 및 분산성 분석은 transmission electron microscopy(TEM)에 의해 이루어졌다. 또한, 촉매의 전기화학적 특성평가는 cyclic voltammetry(CV)에 의해 조사되었다.

• 한국안전학회지
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• 제31권4호
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• pp.111-119
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• 2016

This study aimed to analyze postures that were frequently conducted in manufacturing industry. To find grip strength and muscle activities of each posture, Maximum Voluntary Contraction (MVC) and ElectroMyoGraphy (EMG) were measured. Based on the results of this study, the most appropriate posture could be suggested and used as a basic information for preventing musculoskeletal disorders. Most work-related musculoskeletal disorders have been occurred in the fields of manufacturing industry. According to previous studies, it was reported that the rate of musculoskeletal diseases of upper extremity was higher than that of other body parts. Accordingly, there were many studies about discomfort and grip strength of upper extremity. However, these studies dealt with single selection of wrist, elbow and shoulder. So, it was insufficient for comprehensive studies about upper extremity. And in order to improve the work posture, the physiological changes being generated by the combination of wrist, elbow and shoulder postures should be observed and analyzed. In order to conduct this study, thirty university students who had no records of MSDs involved were recruited. Independent variables were postures of wrist(pronation, neutral, supination), postures of elbow(flexion $45^{\circ}$, $90^{\circ}$) and postures of shoulder(flexion $0^{\circ}$, $90^{\circ}$). And dependent variables were MVC values and EMG values. Jamar dynamometer and TeleMyo 2400T G2 was used to measure MVC and EMG. MVC and EMG for 12 postures were measured for three second and for three times. Experiment was performed randomly. A 10 minutes rest period was provided after each t. To measure muscle load, the EMG signals of eight muscles (Biceps, Medial triceps, Lateral triceps, Brachioradialis, Extensor carpi ulnaris, Extensor carpi radialis, Flexor carpi ulnaris and Flexor carpi radialis) were evaluated. MVC values and EMG values were analyzed using Minitab ver. 14. The results showed that MVC value was the highest at shoulder $0^{\circ}$, elbow $45^{\circ}$ and wrist supination. In case of wrist postures, MVC of supination is the highest. In case of elbow and shoulder postures, MVC of flexion $45^{\circ}$ and $0^{\circ}$ was the highest. It was found that there were interaction between wrist and elbow posture under shoulder flexion and between shoulder and wrist under elbow flexion $45^{\circ}$. In case of the angle of shoulder $0^{\circ}$, elbow $45^{\circ}$ and wrist supination, the EMG values of four muscles(Medial Triceps, Extensor carpi ulnaris, Extensor carpi radialis, Flexor carpi ulnaris) were the highest. Based on this study, it is worth to note that the combination postures of upper extremity have a large impact on the MVC and EMG. The optimal condition upper extremity was shoulder flexion $0^{\circ}$, elbow flexion $45^{\circ}$ and wrist supination for preventing work-related musculoskeletal disease.

• Computers and Concrete
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• 제32권3호
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• pp.287-302
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• 2023

Corrosion of reinforcing bars in reinforced concrete structures due to chloride attack in environments containing chloride ions is one of the most important factors in the destruction of concrete structures. According to the abundant reports that the corrosion rate around the repair area has increased due to the macro-cell current known as the incipient anode, it is necessary to understand the effective parameters. The main objective of this paper is to investigate the effect of the kinetic parameters of corrosion including the cathodic Tafel slope, exchange current density, and equilibrium potential in repair materials on the total corrosion rate and maximum corrosion rate in the patch repair system. With the numerical simulation of the patch repair system and concerning the effect of parameters such as electromotive force (substrate concrete activity level), length of repair area, and resistivity of substrate and repair concrete, and with constant other parameters, the sensitivity of the macro-cell current caused by changes in the kinetic parameters of corrosion of the repairing materials has been investigated. The results show that the maximum effect on the macro-cell current values occurred with the change of cathodic Tafel slope, and the effect change of exchange current density and the equilibrium potential is almost the same. In the low repair extant and low resistivity of the repairing materials, with the increase in the electromotive force (degree of substrate concrete activity) of the patch repair system, the sensitivity of the total corrosion current reduces with the reduction in the cathode Tafel slope. The overall corrosion current will be very sensitive to changes in the kinetic parameters of corrosion. The change in the cathodic Tafel slope from 0.16 to 0.12 V/dec and in 300 mV the electromotive force will translate into an increase of 200% of the total corrosion current. While the percentage of this change in currency density and equilibrium potential is 53 and 43 percent, respectively. Moreover, by increasing the electro-motive force, the sensitivity of the total corrosion current decreases or becomes constant. The maximum corrosion does not change significantly based on the modification of the corrosion kinetic parameters and the modification will not affect the maximum corrosion in the repair system. Given that the macro-cell current in addition to the repair geometry is influenced by the sections of reactions of cathodic, anodic, and ohmic drop in repair and base concrete materials, in different parameters depending on the dominance of each section, the sensitivity of the total current and maximum corrosion in each scenario will be different.

• Restorative Dentistry and Endodontics
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• 제25권4호
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• pp.561-574
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• 2000

Poly-P has been used to prevent decomposition of foods and has been shown to have inhibitory effect on the growth of gram positive bacteria. The purpose of this study was to evaluate the effect of poly-P on the growth of Porphyromonas endodontalis, a gram negative obligate anaerobic rod, endodontopathic bacterium. P. endodontalis ATCC 35406 was in BHI broth containing hemin and vitamin K with or without poly-P. Inhibitory effect of each poly-P which was added at the beginning(lag phase) or during(exponential phase) the culture, MIC(minimum inhibitory concentration) was determined by measuring the optical density of the bacterial cell at 540nm. Viable cell counts were measured to determined whether poly-P has a bactericidal effect. Leakage of intracellular nucleotides from P. endodontalis was determined at 260nm and morphological change of P. endodontalis was observed under the TEM(transmission electron microscope). Binding of 32P-labeled poly-P to P. endodontalis was examined. SDS-polyacrylamide gel electrophoresis and zymography were performed to observe the changes in protein and enzyme profiles of P. endodontalis, respectively. The results from this study were as follows : 1. The minimal inhibitory concentration(MIC) of poly-P to P. endodontalis appeared to be 0.04~0.05%. 2. Poly-P added to the P. endodontalis culture during the exponential phase of P. endodontalis was as much effective as poly-P added at the begining of the culture, suggesting that the antibacterial effect of poly-P is not much dependent on the initial inoculum size of P. endodontalis. 3. Poly-P are bactericidal to P. endodontalis, demonstrating the decrease of the viable cell counts. 4. Intracellular nucleotide release from the P. endodontalis, was not increased in the presence of poly-P and was not reversed by the addition of divalent cations like $Ca^{2+}$ and $Mg^{2-}$. 5. Under the TEM, it was observed that fine electro-dense materials were prominent in the poly-P grown P. endodontalis, appearing locally in the cell, and the materials were more abundant and more dispersed in the cell as the incubation time with poly-P increased. In addition, highly electron dense granules accumulated in many poly-P grown cells, most of which were atypical in their shape. 6. Binding of 32P-labeled poly-P to P. endodontalis appeared to be 32.8 and 45.5 and 53.4% at 30 minutes, 1 hours and 2 hours, respectively. 7. In the presence of poly-P. the synthesis of proteins with apparent molecular masses of 25, 27, 35, 45 was lost or drastically decreased whereas expression of a protein with an apparent molecular mass of 75 was elevated. 8. Proteolytic activity of P. endodontalis was decreased by poly-P. The overall results suggest that use of poly-P may affect the growth of P. endodontalis, and the anti-bacterial activity of poly-P seems largely bactericidal. Changes in shape, protein expression, and proteolytic activity of P. endodontalis by poly-P may be directly and indirectly attributed to the antibacterial effect of poly-P. Further studies will be needed to confirm the effect of poly-P.