• The korean journal of orthodontics
• /
• v.21 no.3
• /
• pp.563-580
• /
• 1991

The purpose of this study was to investigate and compare the biomechanical properties of orthodontic rubber elastic materials. Latex bands, nylon-covered elastic threads and polyurethane-based elastic modules, delivering $205{\pm}10$ grams force at 30mm stretching state were selected and stored separately in 3 environments-air ($22{\pm}3^{\circ}C$), distilled water ($37{\pm}1^{\circ}C$), or natural saliva ($37{\pm}1^{\circ}C$). And, the amount of remaining force and permanent elongation of each sample were measured on Instron at interval of 1 hour, 6 hours, 12 hours, 24 hours, 1 week, and 2 weeks. So the data derived were analyzed statistically. The results were as follows: 1. Force decay and permanent elongation of all materials increased with time lapsed; elastic module, latex band and nylon-covered elastic thread in that order of the amount of force decay; elastic module, elastic thread, latex band in that order of the amount of permanent elongation. 2. Among environmental conditions, force decay and permanent elongation in natural saliva, most increased, and those in air, least increased. 3. There was a negative correlation between force decay and permanent elongation. 4. Force decay and permanent elongation were most affected by the material itself, time and environments in that order. 5. After 24 hours in saliva, the percentage of remaining force in elastic module was 51.9% (107.37grams); in latex band, 83.2%(172.62grams); in elastic thread, 85.0%(179.25grams). After 2 weeks in saliva, the percentage of remaining force in elastic module was 42.9%(88.75grams); in latex band, 74.5%(154.50grams); in elastic thread, 77.6%(163.75grams).

• Journal of Fashion Business
• /
• v.12 no.6
• /
• pp.11-22
• /
• 2008

The goal of this study is to provide beauticians with the fundamental material to use effectively heat permanent wave in beauty industry as well as their customer's satisfaction. It carried out an experiment with damaged hair of a woman in her late twenties to investigate the change of physical and morphological characteristics by its water content when performing heat permanent wave. After spreading 0g, 1g, 2g, 3g, and 4g of water on damaged hair respectively, heat permanent wave was treated and the change of hair was observed. The change of physical characteristic was compared through permanent wave form of hair, tensile strength and elongation. The change of morphological characteristic was observed through Scanning Electron Microscope(SEM) and Transmission Electron Microscope(TEM). The result of experiment on the physical specificity revealed that permanent wave form was the most ideal when the water content was 2g, also 3g. Though the materials with much moisture content formed the results were not satisfied. The material with 0g of water content didn't make the wave. In terms of tensile strength and elongation, tensile strength was generally reduced as per the damaged degree of hair. On the contrary, elongation was increased. It observed the changes of morphological characteristic that the damage on hair cuticle was deepen, as its moisture content was decreased, and cuticle's surface was worn away. The observation of fine structure on hair section by transmission electronic microscope also certainly showed the result that damaged hair having experience with chemical treatment had got much damaged to hair cuticle as well as hair cortex. Generally chemical treatment makes hair damaged. Under consideration of this aspect, the ultimate goal of this thesis is to minimize the damage of hair caused by chemical treatment and get the satisfaction on the hair style. According to the result of experiment, the damaged hair whose moisture content was 3g showed the best permanent wave form.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.29 no.12 s.148
• /
• pp.1619-1626
• /
• 2005

The durability of a stretch fabric is mainly related to the change in the dimension and mechanical properties of elastomeric fibers during wearing and washing. In this study, we examined the effects of washing temperature, presoaking time and the number of washing cycles on the change in length, tenacity, elongation at break, and permanent elongation after six repeated cycles of $100\%$ extension and relaxation of spandex yams with varying fineness and with a different rate of extension during heat-set. The spandex yarns continued to shrink as the wash temperature and the number of wash cycles increased. In addition, the finer spandex yams decreased in length more than the thicker yams. The increase in temperature and presoaking time tended to cause a slight decrease in the tenacity and elongation at break of the spandex yarns. Permanent elongation of the spandex yams also increased as the temperature, presoaking time and the number of washing cycles increased. Moreover, an extended presoaking time followed by washing at $40\%$ like repeated washing cycles showed the great increase in the permanent elongation of spandex yams. The thinner spandex yin had a better elasticity than the thicker one, since the former had a lower permanent elongation percentage than the latter. Based on the DSC thermograms, the melting points of the spandex yarns after washing were almost the same as those of the spandex yarns before washing.

• Fashion & Textile Research Journal
• /
• v.10 no.3
• /
• pp.389-393
• /
• 2008

The purpose of this study is to provide beauticians with the fundamental material for them to use effectively heat permanent wave and satisfy their customers. It carried out an experiment with hair of a woman in her late twenties to investigate the change of physical and morphologic characteristics by its water content when performing heat permanent wave. It evaluated the water content as 0g, 1g, 2g, 3g and 4g respectively when performing the heat permanent wave on hair, then it compared and observed the wave type, tensile strength and elongation for its physical change also observed the morphologic change by scanning electronic microscope and transmission electronic microscope. The result of experiment on the physical specificity revealed that the wave was the most ideal when the water content was 2 g. The material with much water content made wave but the result was not satisfied. In the case of hair with water content of nearly 0g didn't make wave. In terms of tensile strength and elongation, the tensile strength was generally reduced as hair was damaged, on the contrary, the elongation was increased. It observed the change of morphologic characteristic and got the result that the damage on hair cuticle was deepen as its water content was decreased. It also showed the result that damage happened on hair cuticle more than hair cortex with the observation of fine structure on hair section by transmission electronic microscope. Generally chemical treatment damaged hair. Under consideration of this aspect, the ultimate goal of this thesis is to minimize the damage of hair caused by chemical treatment and get the satisfaction on the hair style. The result of experiment presented that the hair showed the best result when its water content was 2 g.

• Journal of Convergence for Information Technology
• /
• v.9 no.11
• /
• pp.254-258
• /
• 2019

To protect healthy and beautiful hair, the hair protection effect was tested by adding an aloe extract from the hair solution. The treatment groups were grouped into four categories: Group II (Famma Treatment Only), Group III (Oxidase+aloe), Group IV (Reduce+aloe), and Group V (Oxidase+aloe, Release+aloe). The test hair is collected from women's hair in their 20s, 30s and 40s who have not undergone chemical treatment such as permanent and dying for one year and use 100% aloe stock solution. In order to evaluate hair thickness, cuticles, tensile strength, elongation and formation rate, the experiment environment was 28.9 degrees and 72% humidity. All statistical tests were done at 5% significant level. Cuticle, elongation, and formation rate were significantly improved (P<.05) and cuticle was best in group V, elongation was group III. In conclusion, aloe added to perm treatment were effective in improving cuticle, elongation rate, and formation of hair.

• Fashion & Textile Research Journal
• /
• v.8 no.4
• /
• pp.441-448
• /
• 2006

This research is the hair damage as treating a permanent wave before and after that is compared and analyzed the change of physical and mechanical properties. This is the survey of women's hair in 20 years old. On the basis of this we would like to analyze a extend of hair damage. Also, we would to show a basic data for hair damage prevention and hair improvement to keep the beautiful and healthy hair. The conclusion is as follow. : The swelling degree after the treatment was found to be greater than before permanent wave treatment. For the formational characteristics wave, untreated hair certainly had more elastic S curl wave than damaged hair in all the permanent wave treatments, and damaged hair and extremely damaged hair had less elasticity and had saggy S curl wave. The protein permanent and soft permanent wave had thicker, gorgeous, and better elastic wave than the regular permanent wave and direct heating permanent wave in all the hair condition. As the degree of damage on hair got greater, the tensile strength dramatically decreased and as the degree of damage got greater, the elongation was great as well. For treatment method, direct heating permanent wave showed the greatest effect, causing the most damage.

• Journal of Fashion Business
• /
• v.12 no.6
• /
• pp.1-10
• /
• 2008

Public interest in healthy hairs gets growing as damaged hairs are seen more frequently with the generalization of heat permanent waves. For this study, experiments have been conducted to understand the influences on the changes in physical and morphological features of wave forms and damaged hairs, by collecting virgin hairs from the women in their mid-20's, who had not experienced chemical applications, and by dividing the applications of heat perm hair treatments, PPT(for pre-treatment) and LPP(for post-treatment), into the pre-treatment, the post-treatment, the pre & post-treatment, and the non-treatment. For the wave formations, curl waves were investigated by the bare eyes using the pictures taken by a digital camera. For the comparison of physical features, the experiments of tensile strength and elongation were done and their mean values were found. For the observations of morphological features, the pictures were taken by SEM for comparison. As for the findings, regarding the curl wave shapes of hairs, the most even and elastic S curl was formed in the case of non-treatment. In the physical features, both of the tensile strength and elongation showed a decreasing tendency in line with the hair damage levels, and the case of the pre & post-treatment indicated the tendency most similar to the control group. In the morphological features of the cuticle, observed with an SEM, the pre-treatment showed the higher possibility of reducing the cuticle damages than the post-treatment did. LPP was found to play the role of protective membrane for the post-treatment, and the pre & post-treatment turned out to reduce most effectively the cuticle damages.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.31 no.2
• /
• pp.150-160
• /
• 2005

Background: For normalization of displaced anatomical structure by large cyst, two-step procedure (decompression and enucleation afterward) has been recommended. However, the histological transformation after cystotomy for decompression was shown frequently in secondary enucleation. Therefore, analyses about effects and histological changes after decompression have been necessary. Methods: 48 cases diagnosed as large odontogenic cyst in the jaw and treated by decompression and secondary enucleation were retrospectively analyzed in clinical, rediographical, and histological aspects. Results: In dentigerous cyst, decompression was much useful. Impacted permanent teeth were erupted and reduction rate was higher than that of odontogenic keratocyst (OKC) and apical periodontal cyst. In OKC, among the 29 cases, 11 cases showed no-keratosis, proliferation and rete-ridge elongation after decompression. 4 cases showed no-keratosis, only. 7 cases showed orthokeratosis and rete-ridge elongation and 6 cases showed reteridge elongation, only. 1 case had no change. And the recurrence rate for OKCs was 10.3%. For all odontogenic cysts in this study, dysplasia was not found in cystic lining after decompression. Conclusions: This study implied that decompression for large odontogenic cyst was useful treatment modality because it was conservative treatment and recurrence rate was low although long treatment period was required.

• Journal of Korea Foundry Society
• /
• v.17 no.4
• /
• pp.365-370
• /
• 1997

The effects of changes in microstructure of Si phase on the thermal expansion coefficients(CTEs) and tensile properties of the hypereutectic Al-Si foundry alloy(A390) were investigated experimentally. Specimens were prepared by various fabrication processes, such as a permanent mold casting, a squeeze casting and a spray casting process, and subsequently hot-extruded. CTEs of the spray-cast specimen were found to be about 10% lower than those of the permanent mold-cast specimen, and the CTEs of the hypereutectic Al-Si alloy(A390) were changed proportionally with the size of Si phase. Ultimate tensile strength of the spray-cast and hot-extruded specimen was dramatically improved about 100% with improved elongation, compared to that of permanent mold-cast specimen. These improvements are mainly attributed to the reduction in size and aspect ratio of the brittle Si phase, and the elimination of the microvoids/porosities formed during casting.

• Journal of Korea Foundry Society
• /
• v.23 no.4
• /
• pp.195-203
• /
• 2003

Hyper-eutectic Al-Si alloy is used much to automatic parts and material for the electronic parts because of the low coefficient of thermal expansion, superior thermal stability and superior wear resistance. In this work, A390 alloy specimens were fabricated for control of the Si particle size by various processes, such as spray-casting, permanent mold-casting and squeeze-casting. To minimize the effect of microporosity of the specimens, hot extrusion was carried out under equal condition. Each specimens were evaluated tensile properties at room temperature and thermal expansion properties in the range from room temperature to 400$^{\circ}C$. Ultimate tensile strength and elongation of the spray-cast and extruded specimens which have fine and well distributed Si particles were improved greatly compare to the permanent mold-cast and extruded ones. Specimens which have finer Si particles showed higher ultimate tensile strength and elongation than those having large Si particle size, and coefficient of thermal expansion of the specimens increased linearly with Si particle size. In case of the repeated high temperature exposures, thermal expansion properties of the spray-cast and extruded specimens were found to be more stable than those of the others due to the effect of fine and well distributed Si particles.