• Composites Research
• /
• v.20 no.2
• /
• pp.10-16
• /
• 2007

The 2-step manufacturing method consisting of preforming and stamping processes was developed to manufacture composite bipolar plates for PEMFCS. The preform was composed of expanded graphite, graphite flake and phenol resin. Procuring conditions were optimized by checking the electrical conductivity, flexural strength and microstructure. Procuring temperature $(100^{\circ}C)$ slightly above the melting point of phenol powders $(90^{\circ}C)$ induced moderate curing, but also prevented excessive curing. Preforms utilizing the tangled structure of expanded graphite were easily fabricated at low pressure of 0.07-0.28MPa. The proper procuring time, 5min, was determined to fabricate the preform stably because insufficient and excessive procuring deteriorated the flexural strength of composite bipolar plates.

• Science of Emotion and Sensibility
• /
• v.15 no.2
• /
• pp.177-182
• /
• 2012

Automotive sub-mat carpet for convenience and comfort of floor administration is additional supplemented floor mat. Sub Mat Backing of the current vehicle's materials reclaimed rubber, PVC, etc. are used, but secondary rubber and PVC Backing have bad sound absorption. Also rubber is heavy too. Contact surfaces between PET staple fiber, PET non-woven, PVC backing and car's floor carpet was measured the coefficient of friction for each sub-mat's non-slip evaluation. A surface of PET non-woven sub-mat has the highest coefficient of friction. Each of sample was observed by optical microscope the contact surfaces before and after. Contact surfaces of PET staple fiber sub-mat was changed increasingly to non-woven. This fact is shown that the sub-mat would be tangled between its contact surface and top of the floor carpet. It is expected to be highly non-slip. In case of PET non-woven sub-mat had not different for contact surfaces between before and after. And PVC backing was shown lower non-slip than other samples. The result of optical microscope and coefficient of friction is seems to be related.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.15 no.1
• /
• pp.63-79
• /
• 1993

To repair bony defects with tansplanted bone in the body, fresh autogenous bone is undoubtly, the most effective bone graft for clinical applications. But the demineralized bone has the matrix-induced bone formation which was suggested by Urist in 1965. Many authors assisted that demineralized bone powder induces phenotypic conversion of mesenchymal cells into osteoblasts, with high-density bone formation. The process of inducing differentiated cells becomes osteogenic properties. The purpose of this study was to evaluate the osteoinductive capacity of allogenic freeze-dried demineralized bone block (FDD, $7{\times}7mm$) and to compare FDD with the same sue of deep-frozen allogenic bone(DF), fresh autogenous bone (A) after implantation. The histological and ultrastructural features of tissue responses were examined after 1, 2, 4, 6, 8 weeks implantation of each experimental groups in the operative site of the New Zealand white rabbits. The results were as follows : 1. Inflammatory cell infiltration generally has appeared at 1 week, but reduced at 4 weeks in each group, but most severe in DF group. 2. Osteoblastic activity has increased for 4 weeks, but decreased at 6 weeks in each group and there was no significant difference among experimental groups. 3. New bone formation has begun at 1week, least activations in A groups, and showed the revesal line of bone formation among each group at 6 to 8 weeks. 4. Bone resorption has appeared at 1 week, but disappeared at 4 weeks in both A and DF groups, but more severe in DF than A groups. 5. In ultrastructural changs, the DF group have showed the most remarkable osteoclastic activities among experimental groups. 6. Osteoid or tangled collagen fibrils near the implanted sites were replaced by more mature, lamellated bony trabeculae during bone remodeling. There was little difference among each experimental groups. 7. During the convertion osteoblasts to osteocytes which embedded within the bone matrix, there was organ-less-poor cytoplasm, increased nuclear chromatin, abundant rough endothelial reticulum (RER) in each groups. From the above the findings, the DF group shored more bone resorption and foreign body reaction than FDD and A groups, and FDD group showed more new bone formation or osteoblastic activity than DF and A groups in early stage. There was no significant difference of cellular activities among the FDD DF, and A groups according to the time.

• Journal of Korean Society of Environmental Engineers
• /
• v.22 no.7
• /
• pp.1273-1284
• /
• 2000

In this study, ultrafiltration was performed to remove humic acid from aqueous solution. Since the effects of system variables on the ultrafiltration were tangled with non-linearly. Response Surface Methodology(RSM) was used to know optimum conditions of ultrafiltration process, relations among system variables, and the effects of system variables such as pressure difference across the membrane, concentration of humic acid, and feed flow rates. As concentrations of humic acid were 10ppm, 40ppm, and 70ppm in feed stream, permeation fluxes were 2.56, 2.27, and $2.10({\times}10^{-2}cc/cm^2{\cdot}min)$ respectively ; in other words, permeation fluxes of 10ppm, 40ppm and 70ppm feed concentration decreased by 17.7%, 26.7% and 32.2% of pure water permeation flux respectively. Concentration of humic acid in permeate side were 0.5ppm, 1.2 ppm, and 2.1ppm respectively. When pressure difference(${\Delta}P$) increased from 1atm to 2atm and 3atm, permeation fluxes of 40ppm feed concentration increased by 66% and 152% of permeation rate at 1atm respectively. However, concentrations of humic acid in permeate side increased from 0.5ppm to 1.5ppm and 3.5ppm. RSM showed that the optimum condition of system variables is 38.5~40ppm of humic acid concentration in feed stream, 30~30.7cc/min of feed flow rate, and 2atm of pressure difference.

• Cartoon and Animation Studies
• /
• s.49
• /
• pp.493-519
• /
• 2017

Looking back at the last 10 years of the enactment of the Game Industry Act, the law was revised as a regulation rather than a promotion of the game. The objective of this study is to investigate where game regulation originated and derived through the history of those, and to find out what areas were missed, and to solve the tangled threads by regulation. For this purpose, we reviewed the implications of 10,000 won per hour, and discussed alternatives. Data were collected and analyzed on the basis of a review of regulatory literature and in - depth interviews with experts. When regulating games, we found that the side effects were further amplified by simply regulating the amount. Especially, we found that the vicious cycle in which functions such as indication, hit repeatedly, and automatic progress are made and immediately following prohibited is repeated. The point at which there is a sharp interest between the game user and the game operator in the game progression is the 'reward ratio for betting'. This is the key to protecting users. This could be a regulation considering the mechanism of the game. If the regulatory paradigm shifts in the future due to game regulations that take into account the 'reward ratio for betting' in the future, it is expected to minimize the side effects of price regulation and create a sound game ecosystem.

• Journal of Veterinary Clinics
• /
• v.26 no.6
• /
• pp.659-662
• /
• 2009

The Korea Institute of Oriental White Stork Rehabilitation Research (KIOWSRR) is breeding oriental white storks for residential rehabilitation in South Korea. Three oriental white storks were referred with anorexia and depression. Two storks were died before examinations and one stork was died after 1 day of fluid therapy. On necropsy, salmon-colored subcutaneous and visceral fats were examined in all storks. Multiple focal necroses on liver surface were also examined. In gizzards, many gravels and grasses were severely tangled; therefore, it produced a large mass that blocked digestive system of the storks. Small intestinal segments of the stork, which was dead after the fluid therapy, were severely adhesive. On histopathology, diffuse necroses with/without inflammation were examined in the liver, gizzard and intestine in all storks. Bile stasis was additionally examined in the liver. According to the results of the examinations, all storks were diagnosed as gizzard impaction caused by parorexia.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.16 no.6
• /
• pp.1121-1140
• /
• 1992

In metal cutting the shape of generated chip varies according to cutting conditions, characteristics of workpiece and geometry of cutting tool. The best surface roughness of machined workpiece is obtained when generating flow type contrinuous chip. If the generated chip is not broken, that is not only tangled workpiece and cutting tool, but also may give damage on the machined surface of workpiece or danger for a operator. The flow type continuous chip may bring the low productivity in high speed any heavy cutting, automatic machining process and non-human factory. There are two type of chip break process ; controlling cutting condition and using chip breaker. In present study we carried out the experiment on new type chip breaker compared with conventional type and proved the efficiency of a new type and showed the chip break condition to be applied in actual metal cutting. In the experiment SM 20 C as a workpiece material and WC as a tool material were used and cutting speed of 30-150m/min, feed of 0.071-0.210mm/rev and depth of cut of 1mm were applied as cutting condition. The results of the experiment are as follows : (1) The mechanism of chip curl can be explained more clearly by plastic flow of workpiece material and moment of shearing force. (2) The most effective radius of curled chip and flat distance from cutting edge is 2.0-2.5mm and 1.5mm in both types. (3) The effective inclination angle of chip break surface and side cutting edge angle are 30.deg.- 45.deg. and 20.deg. in conventional type, while the radius of arc surface, lower arc angle A, upper arc angle B and side cutting edge angle are 3mm, 20.deg.- 45.deg., 0.deg.- 45.deg. and 10.deg.- 20.deg. in new type. (4) The probability to be obtained 100% chip breaking ratio is much higher in new type than in conventional type.

• Journal of the Korean Geographical Society
• /
• v.50 no.4
• /
• pp.431-449
• /
• 2015

Philosophical roots and discussion frames of neoliberalism are very heterogeneous and approaches to neoliberalism including anarchism, post-neoliberalism also take diverse stances. Even if neoliberalism is losing legitimacy and stability through the global financial crisis, 2008, spatial perspective is becoming more and more important as neoliberalism constantly evolve with creating immense variations. Especially, urban space has become strategically crucial arenas as spatio-temporal strategies and generative nodes for reproduction of neoliberalism. Urban enclosure plays a key role in the specific process of neoliberal urbanization as a kind of capitalist formal and real subsumption. Contemporary capitalism continuously has been sustaining the accumulation by dispossession based on urban enclosure through reshaping the primitive accumulation mechanism. These enclosures are embodied by the change of public use concept from public ownership to economic benefits and public-private taking for private capital. Urban enclosure promotes reification deepening the separation and alienation of workers from the means of production and survival, and interdiction from free place appropriation, transformation of urban economy to patrimonial forms. Also it is pervasive in a daily life space and everyday experience in the city, and private tangled social rules dominate public space and the publicity of space.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.30 no.4
• /
• pp.333-344
• /
• 2008

The objectives of this study was to explore the growth pattern of the oral squamous cell carcinoma when overexpressed COX was inhibited, explore the pathway that COX inhibitors suppressed the proliferation of cancer cells, and then hereafter investigate the potential of COX as chemopreventive target for oral squamous cell carcinoma. For confirming the COX-dependent effect and mechanisms on growth of the oral cancer cells, we treated the nonselective NSAID, Mefenamic acid and COX-2 selective inhibitor, Celecoxib in HN4 cell line. And then the cell line was evaluated with MTT assay and growth curve, the production of PGE2, total RNA extraction and RT-PCR analysis, and TEM The results were obtained as follows: 1. After administration of medication, in the result of MTT assay, Celecoxib inoculated group inhibit the cell growth rather than Mefenamic acid inoculated group. 2. The growth curve of cell line showed as time passes by there was a dramatic cell growth in the control group, and gradual growth inhibition was found in medication inoculated group and, in Celecoxib inoculated group there was more inhibition of cell growth. 3. After the administration of medication, Celecoxib tend to inhibit the synthesis of PGE2 more than Mefenamic acid. Mefenamic acid inhibit the synthesis of PGE2 more as the concentration gets high, but Celecoxib inhibited the synthesis of PGE2 even in low concentration. 4. After the administration of medication, the revelation of COX mRNA in cell line, there was a 50% decrease in COX-1, 60% decrease in COX-2 as in $50{\mu}M$ Mefenamic acid, and in Celecoxib $50{\mu}M$ there was not much difference in COX-1 and 90% decrease in COX-2 was found. 5. HN4 cell line showed broken nucleus and tangled cytoskeleton bundles in cytoplasm which meant apoptotic features after the treatment of Celecoxib in TEM view. Depending on the above results, we estimate that the inhibition of the expression of COX-2 cause the growth suppression of the oral squamous cell carcinoma, and it get achieved through pathway of reduced PGE2 production and increased apoptosis. In addition to, because COX-2 selective inhibitor specifically act to COX-2, it is considered that COX-2 selective inhibitor has the adequate potential as chemopreventive agent for oral squamous cell carcinoma.

• Journal of the Microelectronics and Packaging Society
• /
• v.17 no.1
• /
• pp.63-68
• /
• 2010

CNT and permalloy composite plating was investigated. CNTs were pretreated prior to electroplating to disassemble the tangled CNT lumps. The ball milling as a physical pretreatment and the acid treatment as a chemical pretreatment were used. 10M nitric acid and 10 M sulfuric acid were used for the chemical pretreatment. Sulfuric acid was more effective than nitric acid to disassemble CNT lumps. To disperse CNT in the solution, surfactants were used. SDS, Triton X-100 and PAA were used for this purpose. More CNTs were incorporated in permalloy coating when PAA was used as a surfactant. The surface morphologies were observed with FESEM after electroplating CNT and permalloy. The current densities were varied from 10 to $80\;mA/cm^2$ and the concentration of PAA was fixed at 2 g/L. The optimum current density without surface cracks was $20\;mA/cm^2$. The crystallinity of the deposit was analyzed with XRD and the surface hardness was analyzed with Vicker's hardness tester. The corrosion behavior was analyzed with polarization plot. The physical properties of permalloy were not improved with CNT composite plating.