• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.14 no.5
• /
• pp.2544-2549
• /
• 2013

In prepaparation of the high performance polymer/clay nanocomposite, it is essential to modify the hydrophillic $Na^+$-MMT to hydrophobic alkyl ammonium-MMT via organic surfactant. The organic surfactant, VDAC (vinylbenzyldimethyl-dodecylammonium chloride) was synthesized from two primary chemicals and $VDA^+$-MMT was prepared from $Na^+$-MMT through a cation exchange reaction between $Na^+$ and $VDA^+$ (vinylbenzyldimethyl-$dodecylammonium^+$) cation. $VDA^+$-MMT was then dispersed in styrene and polystyrene/$VDA^+$-MMT nanocomposite was fabricated by in-situ polymerization reaction. The clay dispersion and barrier property of the nanocomposite were investigated. From the investigations, it was confirmed that dispersion of the $VDA^+$-MMT was enhanced compared with that of $Na^+$-MMT and as a consequency of better dispersion, barrier property of organic solvent was improved in a great extent.

• Natural Product Sciences
• /
• v.19 no.4
• /
• pp.303-310
• /
• 2013

Velvet deer antler (VDA) is well known oriental medicine claimed to have tonic activities as improving bone mineral density (BMD), immune-enhancing, rejuvenating and many other medicinal activities. Ossified deer antler (ODA) is bony product produced by over-calcification of deer antler due to late harvesting. The extraction efficiency of ODA by conventional boiling in water must be very poor due to bony nature, hence the reputations for the medicinal efficacies of ODA has been highly under-evaluated compared to that of VDA without any experimental evidences. Employing our new efficient water extraction process ($135^{\circ}C$), the extracts of ODA and VDA were analysed to compare the contents of bioactive components and the potencies of pharmacological activities. The results showed that; 1) The $135^{\circ}C$ extraction (autoclaving) of ODA gave highly increased amount of biomass, 120% more than the conventional extraction by 100-boiling, whereas the same treatment for VDA showed only 15% increased amount of biomass. 2) Feeding the ODA- or VDA-extracts to oophorectomized rats showed very potent BMD-recovering activity. 3) During the ossification of deer antler, the total collagen content was found to be increased by addition of type-1 to pre-existing type-2 collagen, but not replacement of type-2 to type-1 collagen. High titer of peptide hormones like growth hormone and IGF-1 were detected in the ODA- and VDA-extracts and also in the serum of ODA- or VDA-treated oophorectomized animals dose-dependently. Present experimental data will give a conclusion that folkloric poor reputations on ODA must be concerned only with poor extraction efficiency of conventional $100^{\circ}C$ water extraction and not based on the composition of bioactive substances of ODA.

• Structural Engineering and Mechanics
• /
• v.76 no.2
• /
• pp.163-173
• /
• 2020

As a vehicle moves on multiple equal-span beams at constant speed, the running vehicle would be subjected to repetitive excitations from the beam vibrations under it. Once the exciting frequency caused by the vibrating beams coincides with any of the vehicle's frequencies, resonance would take place on the vehicle. A similar resonance phenomenon occurs on a beam subject to sequential moving loads with identical axle-intervals. To reduce both resonant phenomena of a vehicle moving on guideway girders, this study proposed an additional feedback controller based the condensed virtual dynamic absorber (C-VDA) scheme. This condensation scheme has the following advantages: (1) the feedback tuning gains required to adapt the control currents or voltages are directly obtained from the tuning forces of the VDA; (2) the condensed VDA scheme does not need additional DoFs of the absorber to control the vibration of the maglev-vehicle/guideway system. By decomposing the maglev vehicle-guideway coupling system into two sub-systems (the moving vehicle and the supporting girders), an incremental-iterative procedure associated with the Newmark method is presented to solve the two sets of sub-system equations. From the present studies, the proposed C-VDA scheme is a feasible approach to suppress the interaction response for a maglev vehicle in resonance moving on a series of guideway girders.

• Journal of the Korea Fashion and Costume Design Association
• /
• v.22 no.2
• /
• pp.61-70
• /
• 2020

This study aims to explore whether the consumers' perceptions of fashion social enterprises' motives for seeking social value affects the consumers' purchase behavior. Specifically, the relationships among the egoistic and strategic driven attribution (ESDA), value-driven attribution (VDA), positive authenticity (PA), negative authenticity (NA), anticipated satisfaction (ANS), and willingness to pay a premium price (WPP) were examined. 151 respondents participated in an online survey. The collected data was analyzed using path analysis. The results revealed that PA, which was positively affected by VDA, was negatively affected by ESDA. However, NA, which was positively affected by ESDA, was negatively affected by VDA. In addition, ANS affecting WPP was influenced by both VDA and PA. In conclusion, this study clearly shows that prioritizing the inherent purposes of social enterprises can lead to more consumers buying products, even though social enterprises set fashion products at higher prices.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.21 no.9
• /
• pp.1649-1654
• /
• 2017

The route request (RREQ) packet of the GAODV is propagated in a unicast-manner using the location of the destination, but the application of the GAODV is restricted by the assumption for the known destination's location. In this paper, we propose a virtual destination aided GAODV (VDA-GAODV) that alleviates the uncertainty of the destination's location due to the mobility. Instead of the known location of the destination, the VDA-GAODV disseminates a RREQ packet to an imaginary location on the line connecting the source and the destination. We derive an optimal imaginary destination that makes RREQ rebroadcasts cover the possible locations of the destination as much as possible. The VDA-GAODV enables the RREQ propagation to cover 95 % of the one-hop communication area centered at the originally known location of the destination, which is larger than that of the original GAODV by 23 %.

• Journal of the Korea Safety Management & Science
• /
• v.15 no.3
• /
• pp.61-69
• /
• 2013

According to ISO 26262 (the international standard on functional safety for automotive industry), the functional safety should be considered during the whole automotive systems life cycle from the design phase throughout the production phase. In order to satisfy the standard, the automotive and related industry needs to take appropriate actions while carrying out a variety of development activities. This paper presents an approach to coping with the standard. Analyzing the standard indicates that the safety issues of the automotive systems should be handled with a system's view whereas the conventional approach to solving the issues has been practiced with focus on the component's level. The aforementioned system's view implies that the functional safety shall be incorporated in the system design from both the system's life-cycle view and the hierarchical view for the structure. In light of this, the systems engineering framework can be quite appropriate in the functional safety development and thus has been taken in this paper as a problem solving approach. Of various design issues, the analysis and verification of the safety requirements for functional safety is a key study subject of the paper. Note, in particular, that the conventional FMEA (failure mode effects analysis) and FTA (fault tree analysis) methods seem to be partly relying on the insufficient experience and knowledge of the engineers. To improve this, a systematic method is studied here and the result is applied in the design of an ABS braking system as a case study.

• Tribology and Lubricants
• /
• v.35 no.4
• /
• pp.206-214
• /
• 2019

This study investigates alternative refrigerants and refrigerant oils as well as the tendency of protecting the global environment in view of automobile air-conditioning systems. Since decades, the R12 refrigerant is not used in automobile air-conditioners because of the ozone depletion potential (ODP) problem, and for the last 20 years, the ODP-free R134a refrigerant is leading the new automotive air-conditioning market. However, owing to its high global warming potential (GWP), the R134a refrigerant use in automobile air-conditioning system is also prohibited by law, and alternative refrigerants with a low GWP need to be proposed. Therefore, recently, the application of R1234yf, R152a, or other alternative refrigerants has started worldwide. By contrast, natural refrigerant R744 was introduced in the market several years ago by VDA (Verband Der Automobilindustrie), which is a German association in the automotive industry. This study also deals with refrigerant oils. For a long time, polyalkylene glycol (PAG) oil has been traditionally used with automobile air-conditioners, and polyolester (POE) oil is suitable for HEV, PHEV, and EV air-conditioning systems, where it is used by the electrically driven compressor owing to its excellent electrical insulation properties. Finally, PAG is an excellent lubricant for all the R134a, R152a, R1234yf, and R744 refrigerants, and has the advantage that it can be applied rapidly to alternative refrigerant air-conditioning systems.

• Convergence Security Journal
• /
• v.22 no.5
• /
• pp.49-59
• /
• 2022

Cyber security in the automobile sector is a key factor in the life cycle of automobiles, and cyber security evaluation standards are being strengthened worldwide. In addition, not only manufacturers who design and produce automobiles, but also due to the nature of automobiles consisting of complex components and various parts, the safety of cybersecurity can be secured only when the implementation level of the cybersecurity management system of companies participating in the entire supply chain is evaluated and managed. In this study, I analyzed the requirements of ISO/SAE 21434 and TISAX, which are representative standards for evaluating automotive cybersecurity. Through a survey conducted on domestic/overseas company security officers and related experts, suitability and feasibility were reviewed according to priorities and industries, so 6 areas and 45 evaluation criteria were derived and presented as final evaluation items. This study is meaningful as a study in that it presented a model that allows companies participating in the automotive supply chain to evaluate the current cybersecurity management level of the company by first applying ISO/SAE 21434 and TISAX overall control processes before uniformly introducing them.

• Proceedings of the KOR-BRONCHOESO Conference
• /
• 1983.05a
• /
• pp.12.2-13
• /
• 1983

Corrosive injuries of the esophagus by accident or suicidal attempt, though decreasing in number, still represent an important problem of our national pathology. One of the most difficult problems facing any physician is the diagnosis and management of caustic ingestion. In order to determine the extent of esophageal bums, to prevent the potential complication, to increase the therapeutic effect, the use of esophagoscopy is an essential step, and it has lessened an unnecessary admission and treatment. The authors have found the value of early esophagoscopy in selected 41 corrosive esophagitis patient who were admitted to Dept. of ENT, Wonju medical college, Yonsei university between 1980. 1-1982. 12

• Journal of Yeungnam Medical Science
• /
• v.12 no.2
• /
• pp.282-291
• /
• 1995

We investigated HBV markers in serum and cerebrospinal fluid of 50 subjects with neurologic disorders or other disorders, who visited Dept. of neurology, college of medicine, Yeungnam University, from April-1 to August-31 1994 and were performed cerebrospinal fluid analysis to investigate the detection rate of HBV markers in cerebrospinal fluid and the possibility of neurologic disorders associated with HBV infection. The results were as follows. The positivity of HBsAg and HBV prevalence rate in serum were 6(12.0%) and 37(74.0%). The number of patient with HBsAg, only anti-HBV and no markers were 6(12.0%), 31(62.0%) and 13(26.0%), respectively. The positivity of HBsAg and HBV prevalence rate in cerebrospinal fluid were 3(6%) and 18(36.0%). The number of patient with HBsAg, only anti-HBV and no markers were 6(100.0%), 12(38.7%) and 0(0.0%) respectively. The number of patient with virus associated diseases(VAD) and non virus associated diseases(NVAD) were 26(52%) and 24(48%). The HBV prevalence rate in serum of VAD and NVAD groups were 88.5% and 58.3% (p<0.05). The HBV prevalence rate in CSF of VAD and NVAD groups were 53.8% and 16.7%(P<0.05). The HBV prevalence rate in serum and CSF of VAD and NVAD groups were 60.9% and 28.6%. Aa a conclusion, the HBV markers in the CSF were partially detected at the presence of the HBV markers in serum. The prevalance rate of HBV in the CSF was increased at the HBsAg positive in the serum and the serum and the CSF was significantly increased at the VAD group than the NVAD group.