• Journal of the Korean Society for Precision Engineering
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• v.25 no.11
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• pp.126-133
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• 2008

Rapid Prototyping (RP) has been widely used for rapid development of prototypes in various industrial fields. In recent years, a new requirement in RP industry has issued so as to directly manufacture a functional prototype which has enough mechanical properties to be used as a functional part. The RP prototype, however, has a limitation in mechanical properties due to its layer-by-layer manufacturing process. This manufacturing process results in anisotropy of the prototype, especially showing weakness in the building direction. In the present work, we performed tensile tests for RP prototypes in order to determine directional mechanical properties. The test specimens were made by using $Eden330^{TM}$ by Object Geometries Ltd. Finite element analyses considering material anisotropy were then carried out for RP prototypes with various building directions. Effect of the building direction on the mechanical strength was investigated through the analysis, and compared with experimental results.

• Applied Chemistry for Engineering
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• v.1 no.2
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• pp.133-139
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• 1990

Methacrylate functional silanes with different methylene spacer groups have been synthesized and the orientation effect and absorption behavior of these silane coupling agent were investigated by Fourier transform infrared spectroscopy(FT-IR). The mechanical properties of glass bead/polyester composites are found to be dependent on the spacer group of treated silane coupling agent. The absorption rate of the silane coupling agent onto the fumed silica surface decreases with increasing the number of the methylene spacer in methacrylate functional silanes. Silane molecules containing long spacer groups are adsorbed onto silica slightly bowed with respect to the substrate surface. The relationship between silane molecular structure and mechanical properties of polymer composites is also investigated in order to improve hot/wet properties of glass fiber/polyester composites.

• The Journal of Korean Physical Therapy
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• v.27 no.2
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• pp.112-117
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• 2015

Purpose: The purpose of this study was to examine the effects of a task-specific obstacle crossing rehabilitation program on functional gait ability in patients with cerebellar ataxia. Overall, we sought to provide ataxia-specific locomotor rehabilitation guidelines for use in clinical practice based on quantitative evidence using relevant analysis of gait kinematics including valid clinical tests. Methods: Patients with cerebellar disease (n=13) participated in obstacle crossing training focusing on maintenance of dynamic balance and posture, stable transferring of body weight, and production of coordinated limb movements for 8 weeks, 2 times per week, 90 minutes per session. Throughout the training of body weight transfer, the instructions emphasized conscious perception and control of the center of body stability, trunk and limb alignment, and stepping kinematics during the practice of each walking phase. Results: According to the results, compared with pre-training data, foot clearance, pre-&post-obstacle distance, delay time, and total obstacle crossing time were increased after intervention. In addition, body COM measures indicated that body sway and movement variability, therefore posture stability during obstacle crossing, showed improvement after training. Based on these results, body sway was reduced and stepping pattern became more consistent during obstacle crossing gait after participation in patients with cerebellar ataxia. Conclusion: Findings of this study suggest that task-relevant obstacle crossing training may have a beneficial effect on recovery of functional gait ability in patients with cerebellar disease.

• Genomics & Informatics
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• v.13 no.4
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• pp.112-118
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• 2015

The intron has been a big biological mystery since it was first discovered in several aspects. First, all of the completely sequenced eukaryotes harbor introns in the genomic structure, whereas no prokaryotes identified so far carry introns. Second, the amount of total introns varies in different species. Third, the length and number of introns vary in different genes, even within the same species genome. Fourth, all introns are copied into RNAs by transcription and DNAs by replication processes, but intron sequences do not participate in protein-coding sequences. The existence of introns in the genome should be a burden to some cells, because cells have to consume a great deal of energy to copy and excise them exactly at the correct positions with the help of complicated spliceosomal machineries. The existence throughout the long evolutionary history is explained, only if selective advantages of carrying introns are assumed to be given to cells to overcome the negative effect of introns. In that regard, we summarize previous research about the functional roles or benefits of introns. Additionally, several other studies strongly suggesting that introns should not be junk will be introduced.

• Carbon letters
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• v.16 no.2
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• pp.93-100
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• 2015

Surface modified carbon felts were utilized as an electrode for the removal of inorganic ions from seawater. The surfaces of the carbon felts were chemically modified by alkaline and acidic solutions, respectively. The potassium hydroxide (KOH) modified carbon felt exhibited high Brunauer-Emmett-Teller (BET) surface areas and large pore volume, and oxygen-containing functional groups were increased during KOH chemical modification. However, the BET surface area significantly decreased by nitric acid ($HNO_3$) chemical modification due to severe chemical dissolution of the pore structure. The capability of electrosorption by an electrical double-layer and the efficiency of capacitive deionization (CDI) thus showed the greatest enhancement by chemical KOH modification due to the appropriate increase of carboxyl and hydroxyl functional groups and the enlargement of the specific surface area.

• Polymer(Korea)
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• v.30 no.2
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• pp.108-111
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• 2006

In this work, the effect of the hydrophobicity of acrylic polymers on the membrane morphology was investigated. The membranes were prepared with poly(methyl methacrylate) (PMMA), poly(ethyl methacrylate) (PEMA), poly (butyl methacrylate) (PBMA), poly(isobutyl methacrylate), and their blends using the wet phase inversion method. PMMA and PEMA having a relatively less hydrophobicity formed the channel-like structure, whereas PBMA and PIBMA having more hydrophobic units formed the finger-like structure. These morphological changes were attributed to differences in the solidification process of the polymer-rich phase determine d by the polymer/solvent/nonsolvent ternary phase diagram. The membrane structures of the blends were controlled by the main component of their blends.

• 한국균학회소식:학술대회논문집
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• 2014.10a
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• pp.48-48
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• 2014

Arbuscular Mycorrhizal Fungi(AMF) is widespread symbiont forming mutualistic relationship with plant root in terrestrial forest in ecosystem. They provide improved absorption of nutrient and water, and enhance the resistance against plant pathogen or polluted soil, therefore AM fungi are important for survival and maintaining of individual or community of plant. For last decade, many studies about the functional variation of AM fungi on host plant growth response were showed that different geographic isolates, even same species, have different effect on host plant. However, little was known about functional variation of AM fungal isolates originated single population, which provide important insight about intraspecific diversity of AMF and their role in forest ecosystem. In this study, four AM fungal isolates of Rhizophagus clarus were cultured in vitro using transformed carrot (Daucus carota) root and they showed the difference between isolates in ontogenic characteristics such as spore density and hyphal length. The plant growth response by mycorrhizas were measured also. After 20 weeks from inoculation of these isolates to host plants, dry weight, Root:Shoot ratio, colonization rates and N, P concentration of host plant showed host plant was affected differently by AM fungal isolates. This results suggest that AM fungi have high diversity in their functionality in intraspecific level, even in same population.

• Journal of Magnetics
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• v.16 no.2
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• pp.104-107
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• 2011

In the present study, we systematically investigated the effect of mechanical milling on the magnetic properties of $Sm_2Fe_{17}N_x$ powders produced by the reduction-diffusion process. The Sm-Fe powders obtained by the reduction-diffusion process were composed of an $Sm_2Fe_{17}N_x$ single phase. After nitrogenation, the coercivity and saturation magnetization of the powders were 0.48 kOe and 13.32 kG, respectively. The particle size largely decreased down to less than $2\;{\mu}m$ in diameter after ball milling for 30 hours. However, there is no evidence that the $Sm_2Fe_{17}N_x$ was decomposed to Sm-N and ${\alpha}$-Fe even after ball milling for 30 hours. The coercivity was significantly improved up to 8.82 kOe after milling for 60 hours. However, the magnetization decreased linearly with the ball milling time.

• Korean Institute of Interior Design Journal
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• v.16 no.3 s.62
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• pp.58-65
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• 2007

The residential space of super high-rise buildings, having a form of a huge three-dimensional vertical city, affect the residents psychologically and qualitatively according to the line of flow. Because of these affects, the system of the line of flows is a very important factor. In this study, we recognize the super high-rise apartment's line of flow as a semantic network system based on case studies. And we also understand the mutual relationship by analyzing each space to recognize what effect it does on the residential environment. Furthermore, to bring up a better semantic network system for super high-rise apartment's line of flows is our goal. According to the case studies, the semantic network of the line of flow consists of 3 parts: the functional network, economical network and unit network. The functional network is composed of the 'need' and 'has', while the economical network includes variable walls that can be changed following the user's taste and eccentric positioned living rooms that protect personal privacy. Therefore the economical network started to appear while the personal value changed according to the improvement of the social condition. Finally, the unit network is a network that effects each unit that has ambiguous boundaries due to the appropriate arrangement between transitional spaces. And the unit network is based on the functional network.

• Proceedings of the Korean Society of Food Science and Nutrition Conference
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• 2001.12a
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• pp.140-151
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• 2001

This study was performed to examine a possible application of the beverage as a bad breath controlling food. To achieve this objective, methods of gas chromatography, electronic nose, sensory analysis and halimeter were used to detect reduction in odor intensities of bad breath caused by the functional beverage as well as its active ingredients. According to results of GC and electronic nose, adding green tea and champignon extracts to bad breath indicators, methylmercaptan and trimethylamine, resulted in significant reduction in headspace concentrations of two indicators. GC results revealed that headspace concentrations of 5 ug/ml of methylmercaptan and 30 ug/ml of trimethylamine added to various concentrations of two extracts were reduced up to $100\%$ after incubating mixtures at $37^{\circ}C$ for 5min. When the functional beverage was properly formulated with green tea extract, champignon extract and $\alpha$-cyclodextrin and evaluated for its deodorizing effect systematically, it also showed distinctive deodorizing activities against bad breath indicators. Conclusively, results obtained from this study might encourage introduction of a new type of bad breath control food in near future.