• The Journal of Korean Academy of Prosthodontics
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• v.43 no.6
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• pp.717-726
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• 2005

Statement of problem. One of the common problems of provisional crown and fixed partial denture materials is that when they are subjected to constant loads for a long period of time, they exhibit a dimensional change (creep). Purpose. The aim of this study was to investigate the viscoelastic behaviour of polymer-based provisional crown and fixed partial denture materials with time at constant compressive load. Material and methods. Three dimethacrylate-based materials (Protemp 3 Garant, Temphase, Luxatemp) and one monomethacrylate-based material (Trim) were selected. Dimensional changes of the specimens were recorded by a LVDT to evaluate their viscoelastic behavior and creep strain. For all specimens, two loading procedures were used. At first, static compressive stress of 4 MPa was applied for 30 minutes and followed by 1 hour of strain recovery. Then, after 24 hours of water storage, the specimens were loaded again. The creep values between materials were statistically analyzed using one-way ANOVA and multiple comparison $Scheff\acute{e}$ test. Independent samples t-test was also used to identify the difference of creep strain between first and secondary loading conditions at the significance level of 0.05. Results. Following application of the first loading, Trim showed the highest maximum creep strain (32.7%) followed by Luxatemp, Protemp 3 Garant and Temphase, with values of 3.78%, 2.86% and 1.77%, respectively. Trim was significantly different from other materials (P<0.05), while there were no significant differences among Luxatemp, Protemp 3 Garant and Temphase (P>0.05). The highest recovery and permanent set of Trim, were significantly different from those of others (P<0.05). At the secondary loading of the dimethacrylate-based materials, creep deformation, recovery and permanent set decreased and the percentage of recovery increased, while in Trim, all values of the measurements increased. This result showed that the secondary loading at 24 hours produced a significant creep magnitude. Conclusion. The dimethacrylate-based provisional crown and fixed partial denture materials showed significantly higher creep resistance and lower deformation than the monomethacrylate-based material. Thus, monomethacrylate-based materials should not be used in long-term stress-bearing situations.

• Journal of the Korean Electrochemical Society
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• v.14 no.2
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• pp.98-103
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• 2011

[ $Li[Ni_{0.8}Co_{0.15}Al_{0.05}]O_2$ ]cathode material for lithium secondary battery is obtained using co-precipitation method. To determine the optimal metal solution concentration value, the CSTR coprecipitation was carried out at various concentration values(1-2 mol/L). The surface morphology of coated samples was characterization by SEM(scanning electron microscope) and XRD (X-Ray Diffraction)analyses. Impedance analysis and cyclic voltammogram presented that internal resistance of the cell was dependent upon the concentration of metal solution. such data is very helpful in determining the optimal content of metal solution concentration to enhancing electrochemical property by adjusting powder size distribution and crystal structure.

• Journal of the Korean Society of Costume
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• v.52 no.5
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• pp.173-186
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• 2002

Street Style, occurred in British and America, has been expressed the character of the new generation by repeating developments and changes. Nowadays, pop music reflects the phase of society. and simultaneously it has influence on from culture to society. Rock Music was rooted in Country 8l western of America. Upon Country & Western, Afro-Americans Rhythm & Blues was added, and that was the birth of Rockabilly. Rockabilly developed to Rock'n 'roll and it started to change to various forms of Rock since 1950s. As the commercial impact and the breakthrough of teenagers emotion, the rock culture comprised the base of the youth culture. However. it formed the anti-establishment culture against the established value, accepting working class subculture. The teenager culture was affected by the Rock culture, also found relief in the opulence provided by the established generation, imitating it as it was. Simultaneously, it had a contrary aspect as anti-establishment form under the banner of revolt against languor in richness. The youth culture created street style that was escaped from high fashion, every time Rock music had changes. Since Street style was based on resistance of established culture and it fully refused vogue, it was indifferent from high fashion. The results of this study were as following. First, every time Rock music had changes, the new youth culture was concomitant with, the youth culture created street style. Secondly, rockahibilly style was characterized as diamond shaped design, embroidery, extra wide shirt collar, vivid contrast color . Rockers style was represented as metal studs, beads, denim, leather jacket, boots. Fusion of hippies style and Psychedelic, long hair, beads. worn denim were elements of headbangers style. Punks style was characterized as ripped T-shirt. rooster hair, over decorated jacket, short skirt. net or plastic T-shirt. Lastly, the firm relation between popular art and fashion was proved by examining the history of Rock Music and Street Style.

• Journal of Sensor Science and Technology
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• v.16 no.1
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• pp.24-32
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• 2007

Conductive rubber material was molded in a belt shape to measure respiration. Its resistivity was approximately $0.03{\;}{\Omega}m$ and the resistance-displacement relationship showed a negative exponent. The temperature coefficient was approximately $0.006{\;}k{\Omega}/^{\circ}C$ negligible when practically applied on the abdomen. The conductive rubber belt was applied on a normal male's abdomen with the dimensional change measured during resting breathing. The abdominal signal was differentiated ($F_{m}$) and compared with the accurate standard air flow rate signal ($F_{s}$) obtained by pneumotachometry. $F_{m}$ and $F_{s}$ differed in waveform, but the start and end timings of each breaths were clearly synchronized, demonstrating that the respiratory frequency could be accurately estimated before further processing of $F_{m}$. $F_{m}-F_{s}$ loop showed a nonlinear hysteresis within each breath period, thus 6 piecewise linear approximation was performed, leading to a mean relative error of 14 %. This error level was relatively large for clinical application, though customized calibration seemed feasible for monitoring general variation of ventilation. The present technique would be of convenient and practical application as a new wearable respiratory transducer.

• Molecules and Cells
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• v.27 no.6
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• pp.673-680
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• 2009

Conversion of the normal soluble form of prion protein, PrP ($PrP^C$), to proteinase K-resistant form ($PrP^{Sc}$) is a common molecular etiology of prion diseases. Proteinase K-resistance is attributed to a drastic conformational change from ${\alpha}$-helix to ${\beta}$-sheet and subsequent fibril formation. Compelling evidence suggests that membranes play a role in the conformational conversion of PrP. However, biophysical mechanisms underlying the conformational changes of PrP and membrane binding are still elusive. Recently, we demonstrated that the putative transmembrane domain (TMD; residues 111-135) of Syrian hamster PrP penetrates into the membrane upon the reduction of the conserved disulfide bond of PrP. To understand the mechanism underlying the membrane insertion of the TMD, here we explored changes in conformation and membrane binding abilities of PrP using wild type and cysteine-free mutant. We show that the reduction of the disulfide bond of PrP removes motional restriction of the TMD, which might, in turn, expose the TMD into solvent. The released TMD then penetrates into the membrane. We suggest that the disulfide bond regulates the membrane binding mode of PrP by controlling the motional freedom of the TMD.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.5 no.1
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• pp.5-10
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• 1994

In vivo canine model was made in two mongrel dogs under the general Ⅰ-Ⅴ anesthesia. A vertical skin incision was made on the neck, the larynx and the trachea were dissected. Two tracheal openings were made : lower one for the insertion of the anesthesia tube and upper one for the delivery of air to the larynx to induce phonation. External branch of the superior laryngeal nerves and recurrent laryngeal nerves bilaterally were identified and stimulated electrically constantly. Subglottic pressure. fundamental frequency, intensity, and open quotient were measured when the air flow rate was varying low, medium and high. Glottic resistence was calculated. As the air flow rate was increased, the subglottic pressure and the sound intensity were increased. However, glottic resistance was decreased as the air flow was increased. In falsetto register, fundamenatal frequency was increased with the increment of air flow, but in modal register fundamental frequency was not increased statistically significant Open quotient by the electroglottography was increased according to the increment of airflow.

• Toxicological Research
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• v.21 no.1
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• pp.39-43
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• 2005

The present study was carried out to investigate the antibacterial activity against Staphylococcus aureus with antibiotic-resistance in vitro and the skin irritation in rabbits with surfactin produced by Bacillus subtilus Complex BC1212. The antibacterial activities of selected antimicrobial agents (surfactin, amoxacillin, colistin, norfloxacin and streptomycin) were evaluated by using the broth microdilution method. As the results, the minimum inhibitory concentration (MIC) of the surfactin was less than 15.6 ㎍/ml. In the skin irritation test, two out of 4 rabbits showed very slight edema at 24 h after the administration of surfactin, and then recovered at 72 h. The change of body weight was normal during the skin irritation test. The primary irritation index in accordance with the Draize evaluation of topical reaction was calculated to be '0.125', which meant not irritating. Based on these results, it could be concluded that the test agent, surfactin, was a non-irritant. We could also think that the surfactin may be useful for the treatment of S. aureus infections such as bovine mastitis.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.5
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• pp.559-563
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• 2013

This study aims to quantify the effects of medication (Med) and deep brain stimulation (DBS) on resting rigidity in patients with Parkinson's disease. We tested 10 limbs of five patients under each of four treatment conditions: 1) baseline, 2) DBS, 3) Med, 4) DBS + Med. Rigidity at the wrist joint was assessed using the Unified Parkinson's Disease Rating Scale (UPDRS). The examiner randomly imposed flexion and extension movement on patient's wrist joint. Resistance to passive movement was quantified by viscoelastic properties. Not only rigidity score but also damping constant showed improvements in rigidity by DBS and Med treatments (p<0.05). This indicates that the viscosity can represent the change in rigidity due to DBS as well as Med, which was manifested by UPDRS score.

• Journal of the Korean Society of Physical Medicine
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• v.8 no.4
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• pp.627-635
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• 2013

PURPOSE: The purpose of this study is to identify how the body composition changes after jump-roping exercise. METHODS: The subjects are 40 college students, 20 females and 20 males. The subjects were selected among college students who had not taken any drug for more than 4 weeks before the experiment started. The experiment was performed for 4 weeks, from May 23rd to June 13rd, 2012. To collect the data, the vital signs such as pulse, blood pressure, weight), and the body composition were measured before and after the experiment. The data on the body composition were analyzed by the electrical resistance analyzer. RESULT: Muscle mass was increased and body fat was decreased for both females and males after the exercise. In particular the increase of the muscle mass and the decrease of the body fat for the females were statistically significant. The result that the body fat of the females was decreased significantly more than that of males is interpreted that the body fat of females are comparatively higher than that of males. Additionally the muscle mass of the left arm and leg of the subjects were significantly increased(p<.05). Correlation analysis between general characteristics such as body composition, abdominal obesity and specific muscle areas for both men and women showed generally positive between before and after the jump-roping exercise (p<.05, p<.01). However the correlation between sleeping time and each variable showed negative. CONCLUSION: A according to the result of this study, jump-roping exercise had a very positive effect on the body composition. The study suggests that college students keep jump roping for a long period to change their body composition favorably.

• Journal of Korean Society of Steel Construction
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• v.11 no.4 s.41
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• pp.373-384
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• 1999

The shell structures with composite materials have the advantages in strength, corrosion resistance, and weight reduction. The objective of this study is to analyze anisotropic composite circular cylindrical shells with shear deformation theory. In applying numerical methods to solve differential equations of anisotropic shells, this paper use finite difference method. The accuracy of the numerical method can be improved by taking higher order of interval ${\Delta}$ to reduce error. This study compares the results of finite difference method with the results of ANSYS based on finite element method. Several numerical examples show the advantages of the stiffness increasement when the composite materials aroused. Therefore, it is expected that results of this study give various guides for change of the subtended angles, load cases, boundary conditions, and side-to-thickness ratio.