• 대한공업교육학회지
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• v.32 no.1
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• pp.55-72
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• 2007

The purpose of this study is to improve specialized high school of electrical field-to-work transition by a SWOT Analysis. The subject analyzed the curricula of 12 special highschool and surveyed 192 vocational teachers of them. In this study, a SWOT matrix was filled to improve transition from electric special high school to work, and the results was gotten as follows: First, the government should offer the military service special case for students of electric special high school, strengthen the course of CEO for the school master, and make the system to expand job training. Second, the provincial office of education should aid a functional training with a administrative ability and financial support, offer a list of industry visiting teachers to specialized high school, and promote a modification of the department according to a growth industry of the area. Third, each school should present a school education goal agreed with the purpose of specialized department and intensify the counselling of job selection and the application of the approved textbook.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.3
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• pp.611-621
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• 2016

This study examined the effects of collagen peptide intake extracted from the tilapia fish (TFCP) on UVB-induced skin in hairless mice. To cause photoaging, the hairless mice were exposed to UVB irradiation three times a week and TFCP was administered with 545 and 1090 mg/kg once a day for 12 weeks. The level of wrinkle formation, thickness of the skin, acute erythema, skin hydration, amount of hydroxyproline, expression of MMPs and filaggrin were measured. Wrinkle formation, thickness of the skin, and acute erythema were significantly lower and skin hydration was higher in the TFCP intake group compared to the UVB-control mice group. In addition, the amount of the collagen and hydroxyproline of the collagen peptide intake group were much higher than the UVB-control group. Oral administration of TFCP inhibited the expression of the MMP-3 and MMP-13 mRNA level as well as activated MMP-2 and MMP-9 induced by UV irradiation, and increased the protein expression of filaggrin in hairless mice skin. In summary, the oral administration of TFCP can inhibit wrinkle formation and protect the skin from UV-damage. Therefore, this study suggests that TFCP is a potential candidate material for skin functional foods.

• Journal of the Korean Applied Science and Technology
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• v.35 no.3
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• pp.702-708
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• 2018

Hydrogels are natural polymer networks that can contain huge quantities of water and many cosmetical ingredients. Their hydrophilic functional groups creates a matrix, which allows high efficacy in delivering active ingredients into the skin. In industry, hydrating properties and strength of the hydrogels are of great interest in manufacturing hydrogel mask packs. We have used the cellulose in various forms such as powder, cotton fiber and cellulase treated cotton fiber to investigate the property changes of cellulose/hydrogel sheets. When 0.1% and 0.3% of cellulose powder were added to hydrogels, tensile strength of hydrogel sheets were decreased by 10% and 14% respectively. Vise versa, when 0.5 ~ 2 cm of cotton fibers were added, tensile strength of hydrogel sheets were significantly increased by about 20%. The hydrogels which contain cotton fibers also gave an excellent moisturizing effect. Especially cellolose/hydrogels containing cellulase-treated cotton fibers showed the best effect on retaining moisture content increasing upto 380% in comparison with the one containing untreated cotton as well as excellent dispersibility.

• Korean Chemical Engineering Research
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• v.52 no.4
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• pp.530-537
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• 2014

Moisture is a major factor causing the deteriorative physical change, microbial growth, and chemical reaction of the products. In this study, the moisture absorbing composite films have been prepared with moisture absorbing material of polyacrylic acid partial sodium salt (PAPSS) impregnated on LLDPE polymer for the functional packaging applications. The results showed that PAPSS impregnated film illustrated uniformly dispersed PAPSS particles in the LLDPE polymer matrix. The transparency of the PAPSS impregnated film decreased slightly at higher PAPSS concentrations. An increase in the PAPSS content for moisture-absorbing films showed a similar decrease in tensile strength, percent elongation at break, and tear strength. Their values of films impregnated with PAPSS of 0.5, 1, and 2% showed no significant difference. Meanwhile, 4% PAPSS films significantly decreased the values of mechanical properties compared to the films impregnated with different PAPSS levels. Values of the oxygen permeability and water vapor permeability for PAPSS impregnated films decreased significantly with greater PAPSS. The results indicate that 4% PAPSS impregnated in LLDPE films had high affinity of moisture absorbencies compared to the other films. The mathematical equation that best described the moisture sorption isotherm of each film sample was the GAB equation at $25^{\circ}C$. The crystallization and melting temperatures of PAPSS films were influenced by the addition of PAPSS material, but showed good thermal stability.

• Journal of Periodontal and Implant Science
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• v.31 no.1
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• pp.163-180
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• 2001

The aim of this study was to evaluate the effects of chitosan coating on the attachment, proliferation, functional and morphological change of periodontal ligament cells. Primary human periodontal ligament cells were cultured in dulbecco's modified Eagle's medium with 10% fetal bovine serum and 1% antibiotics. In experimental group, cells of 4th to 7th passage were inoculated in the multiwell plates coated with chitosan in concentration of 0.22, 0.2, and $2mg/m{\ell}$. Cell counting and MTT assay were done after 0.5, 1.5, 3, 6 and 24 hours of incubation to evaluate the cell attachment, and then after 2 and 7 days of culture to evaluate the cell proliferation. The alkaline phosphatase activity was measured after 4 and 7 days of culture and the ability to produce mineralized modules was evaluated after 21 days of culture. The results were as follows : 1. The morphology of periodontal ligament cells on the chitosan coating was round or spheric. Round cells were aggregated after 6 hours of culture. Aggregated cells on the chitosan coated surface showed nodule-like appearance after 24 hours of culture and not achieved confluency at 7 days. 2. During early period of culture, the attachment of periodontal ligament cells were inhibited by chitosan coating. Inhibition of cell attachment tended to increase with the concentration of chitosan. 3. At the chitosan concentration of 0.02 and $0.2mg/m{\ell}$, periodontal ligament cells were more rapidly proliferated at 7 days, compared to the control group. At the concentration of $2mg/m{\ell}$, the proliferation of periodontal ligament cells was inhibitied(p<0.01). 4. Alkaline phosphatase activity of periodontal ligament cells was increased in chitosan coated group, especially at the concentration of $0.02mg/m{\ell}$after 4 days of culture.5. Periodontal ligament cells produced mineralized nodules on chitosan coated wells without the addition of mineralized nodule forming materials (ascorbic acid, ${\beta}-glycerophosphat$, dexamethasone). With the addition of mineralized nodule forming materials, periodontal ligament cells produced more mineralized nodules at the concentration of $0.02mg/m{\ell}$, compared to the control. In summary, the attachment, proliferation, cell activity, and alkaline phosphatase activity of periodontal ligament cells depended on the concentration of coated chitosan. Chitosan stimulated mineralized nodule formation by periodontal ligament cells. At the appropriate concentration($0.02mg/m{\ell}$), chitosan could increase alkaline phosphatase activity and stimulate the formation of mineralized nodule by periodontal ligament cells. These results suggest that chitosan can be used as an adjunct for bone graft material, and the matrix of tissue engineering for periodontal regeneration, especially bone regeneration.

• The Journal of Korean Academy of Prosthodontics
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• v.42 no.3
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• pp.307-326
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• 2004

Statement of problem. The long-term success of implants is the development of a stable direct connection between bone and implant surface, which must be structural and functional. To improve a direct implant fixation to the bone, various strategies have been developed focusing on the surface of materials. Among them, altering the surface properties can modify cellular responses such as cell adhesion, cell motility and bone deposition. Purpose. This study was to evaluate the cellular behaviors on the surface-modified titanium by morphological observation, cellular proliferation and differentiation. Material and methods. Specimens were divided into five groups, depending on their surface treatment: electropolishing(EP) anoclizing(AN), machining(MA), blasting with hydroxyapatite particle(RBM) and electrical discharge machining(EDM). Physicochemical properties and microstructures of the specimens were examined and the responses of osteoblast-like cells were investigated. The microtopography of specimens was observed by scanning electron microscopy(SEM). Surface roughness was measured by a three-dimensional roughness measuring system. The microstructure was analyzed by X-ray diffractometer(XRD) and scanning auger electron microscopy(AES). To evaluate cellular responses to modified titanium surfaces, osteoblasts isolated from neonatal rat were cultured. The cellular morphology and total protein amounts of osteoblast-like cell were taken as the marker for cellular proliferation, while the expression of alkaline phosphatase was used as the early differentiation marker for osteoblast. In addition, the type I collagen production was determined to be a reliable indicator of bone matrix synthesis. Results. 1. Each prepared specimen showed specific microtopography at SEM examination. The RBM group had a rough and irregular pattern with reticulated appearance. The EDM-treated surface had evident cracks and was heterogeneous consisting of broad sheet or plate with smooth edges and clusters of small grains, deep pores or craters. 2. Surface roughness values were, from the lowest to the highest, electropolished group, anodized group, machined group, RBM group and EDM group. 3. All groups showed amorphous structures. Especially anodized group was found to have increased surface oxide thickness and EDM group had titaniumcarbide(TiC) structure. 4. Cells on electropolished, anodized and machined surfaces developed flattened cell shape and cells on RBM appeared spherical and EDM showed both. After 14 days, the cells cultured from all groups were formed to be confluent and exhibited multilayer proliferation, often overlapped or stratified. 5. Total protein amounts were formed to be quite similar among all the group at 48 hours. At 14 days, the electropolished group and the anodized group induced more total protein amount than the RBM group(P<.05). 6. There was no significant difference among five groups for alkaline phosphatase(ALP) activity at 48 hours. The AN group showed significantly higher ALP activity than any other groups at 14 days(P<.05). 7. All the groups showed similar collagen synthesis except the EDM group. The amount of collagen on the electropolished and anodized surfaces were higher than that on the EDM surface(P<.05).

• Korean Chemical Engineering Research
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• v.51 no.1
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• pp.98-105
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• 2013

The NaA zeolite particles were dispersed in a poly(vinyl alcohol) (PVA) matrix to prepare a composite membrane. The nano sized zeolite particles of NaA were synthesized in the laboratory and the mean size was approximately 60 nm. Pervaporation characteristics such as a permeation flux and a separation factor were investigated using the membrane as a function of the feed concentration from 0.01 to 0.05 mole fraction and the weight % of NaA particles between 0 wt% and 5 wt% in the membrane. Also, the micro sized particles of $5{\mu}m$ were dispersed in the membrane for a comparison purpose. When the ethanol concentration in the feed solution was 0.01 mole fraction, the flux of water significantly increased from $600g/m^2/hr$ to $2000g/m^2/hr$ as the content of the nano NaA particles in the membrane increased from 0 wt% to 5 wt%, while the NaA particles improved the separation factor from 1.5 to 7.9. When the flux of water through the membrane containing nano sized particles was roughly 15% increased compared to the micro sized particles, whereas the separation factor of water was found to be approximately 5% increased. It can be said that the role of the nano sized NaA particles is quite important since both the flux and the separation factor are strongly affected.

• Journal of the korean academy of Pediatric Dentistry
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• v.36 no.3
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• pp.433-439
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• 2009

The purpose of this study was to assess the effect on mandibular growth of botulinum toxin type A (BTXA) injection into the unilateral massester muscle of growing rats at three different growing stages. Thirty six male Sprague-Dawley rats were divided into three groups according to the age (group 1: 4 week-old, group 2: 5week-old, group 3: 6week-old). Then each group was randomly divided into 3 subgroups (control group, unilateral injection group, bilateral injection group). Experimental animals were sacrificed after 4 weeks. Then the jaw measurements were evaluated. The results were as follows: 1. In the group 1, mandibular body length, condylar height and coronoid process height of the unilateral group(BTXA side) and the bilateral group were shorter than those of the control group (p<0.05). 2. In the group 2, anterior region height, condylar height, coronoid process height of the unilateral group(BTXA side) and the bilateral group were shorter than those of the control group (p<0.05). 3. In the group 3, mandibular body length, condylar height, coronoid process height of the unilateral group(BTXA side) and the bilateral group were shorter than those of the control group (p<0.05). 4. There was no significant difference in mandibular measurements between the control side and the injection side in the unilateral group in all age groups (p>0.05).

• Journal of Technology Innovation
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• v.22 no.3
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• pp.1-35
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• 2014

This study analyzed convergence status among input technologies used in technology development with Technology I-O analysis. It was another version of industry input-output analysis which is used in technology planning. This case is an analysis of association between technology an product. The subjects of analysis were 401 tasks that applied to '2012 Convergence Technology Development Project for Small and Medium Businesses' promoted by Korea Technology & Information Promotion Agency for Small and Medium Enterprises. The process of analysis is as followed. First step, we made a matrix table as an input of technology input-output analysis. Input was defined by technology and output was defined by the product. Input technology was defined in a 3-digit code under National Science Technology Classification and output products were defined in a 5-digit under National Standard Industry Code. Second, the Spillover ratio among technologies were calculated and was used to make a picture of technology linkage. As a result of analysis, technology spillover of embedded S/W was the highest in IT convergence, mold product in ET convergence, and functional cosmetics development technology in BT convergence. In general, IT convergence had many element technologies with high technology spillover, and ET had a small number of element technologies with high technology spillover. Therefore, investment effect of element technology is expected to be large if investment on element technologies with high technology spillover is important for vitalizing convergence.

• Membrane Journal
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• v.27 no.2
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• pp.154-166
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• 2017

Polymeric films for gas barrier applications such as food packaging and electronic devices have attracted great interest due to their cheap, light and easy processability among gas barrier materials. Especially in electronic devices, extremely low gas permeance is necessary for maintaining the device performance. However, current polymeric barrier films still suffer from relatively high gas permeance than other materials. Therefore, there have been strong needs to enhance the gas barrier performance of polymeric barrier films while keep their own advantages. Recently, graphene is highlighted as a 2D-layered material for gas barrier applications. However, owing to the poor workability and difficulty to produce in engineering scale, graphene oxide (GO) is on the rise. GO consists of oxygen-containing functional groups on surface with intrinsic 2D-layered structure and high aspect ratio, and it can be well-dispersed in aqueous polar solvents like water, resulting in scalable mass production. Here, we prepared GO incorporated polyimide (PI) nanocomposites. PI is widely used barrier polymer with high mechanical strength and thermal and chemical stability. We demonstrated that PI/GO nanocomposites could perform as a gas barrier. Furthermore, surfactants (Triton X-100 (TX) and Sodium deoxycholate (SDC)) are introduced to enhance the gas barrier performance by improving the degree of dispersion of GO in PI matrix. As a result, TX enhanced the gas barrier performance of PI/GO nanocomposites which is similar to predicted value. This finding will provide new insight to polymer nanocomposites for gas barrier applications.