• Korean Journal of Materials Research
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• v.10 no.3
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• pp.184-190
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• 2000

We investigated the effect of filler content on the thermo-mechanical properties of modified ACA composite materials by incorporation of non-conducting fillers and the reliability of flip chip assembly on organic substrates using modified ACA composite materials. For the characterization of modified ACA s composites with different content of non-conducting fillers, differential scanning calorimeter (DSC), and thermo-gravimetric analyzer (TGA), dynamic mechanical analyzer (DMA), and thermo-mechnical analyzer (TMA) were utilized. As the non-conducting filler content increased, CTE values decreased and storage modulus at room temperature increased. In addition, the increase in the content of filler brought about the increase of Tg^{DSC}$ and $Tg^{TMA}$. However, the TGA behaviors stayed almost the same. Contact resistance changes were measured during reliability tests such as thermal cycling, high humidity and temperature, and high temperature at dry condition. It was observed that reliability results were significantly affected by CTEs of ACA materials especially at the thermal cycling test. Results showed that flip chip assembly using modified ACA composites with lower CTEs and higher modulus by loading non-conducting fillers exhibited better contact resistance behavior than conventional ACAs without non-conducting fillers.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.2
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• pp.160-165
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• 2009

Contact dermatitis is induced by allergy response from a lot of chemical substances brought on by environmental contamination. In this study, we investigated allergy prevention effect of baicalein which is Scutellaria radix extract. Scutellaria radix is the dried roots of Scutellaria baicalensis Georgi (Labiatae). It has been used in oriental traditional medicine for treatment of fever, diarrhea and inflammation. We have induced allergy by PCL after oral administration of 0 mg/kg, 50 mg/kg or 100 mg/kg baicalein dose for 8 times during 8 days in BALB/c mice and measured ear thickness, IgE level, histamine level, mast cell number and histopathological changes. The ear thickness of the 100 mg/kg baicalein group was thinner than that of the 0 mg/kg baicalein group. IgE level and histamine level of the 100 mg/kg baicalein group were lower than those of 0 mg/kg baicalein group. The number of mast cells of 0 mg/kg baicalein group more than that of 100 mg/kg baicalein group in the ear tissue. In addition, intradermal edema with prominent inflammatory cell infiltration was observed at 0 mg/kg baicalein group more than 100 mg/kg baicalein group in the ear tissue. These results suggest that baicalein has allergy prevention effect in BALB/c mice.

• Journal of Astronomy and Space Sciences
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• v.23 no.2
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• pp.105-116
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• 2006

New eight times of minimum light of the near-contact binary EG Cep were presented. All times of minimum light for EG Cep, including ours, were collected and analyzed to study it's orbital period variation. It was found that the orbital period have varied in a cyclical way superposed on an upward parabola. A secular period increase of $3.22{\times}10^{-8}d/y$ was calculated. Under the assumption of a conservative mass transfer, it implied that the stellar gaseous material of about $3.18{\times}10^{-8}M_{\odot}$ /year is transferring from the less massive secondary component to the primary. The cyclical period variation was interpreted as light-time effect due to an unseen third body in the system. The resultant period, semi-amplitude and eccentricity of the light time orbit were calculated to be $38.^y4,\;0.^d0034$ and 0.29, respectively. The mass range of the tertiary proposed in the system is deduced to be quite small as $0.10M_{\odot}{\leq}M_3{\leq}0.21M_{\odot}$ for $i_3{\geq}30^{\circ}$.

• Management & Information Systems Review
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• v.36 no.4
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• pp.187-209
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• 2017

Service industry performance and competitive advantage depend on the attitudes and behavior of customer service employees who produce and deliver services through contact with customers. Most studies on customer service employees so far have concentrated on kindness, attitudes, or benefits. This study focuses on the increasing importance of customer service employees and intends to study them from the viewpoint of human brands that recognize customer service employees as a brand. In addition to the role of the employee at the service contact point, the customer participation behavior affects the interaction process with the customer service employee. Ultimately, customers could no longer be excluded from control to improve service quality. This study based on theory that the human brand characteristics of the customer service employees lead the customer's participation, which has a positive effect on the relationship with the service brand and the service brand attitude surveyed and analyzed customers who use service brand. This study is summarized as follows. First, the relationship between the service brand and the customer is examined. Second, this study also expands prior studies by examining the human brand characteristics of customer service employees and customers' willingness to participate in providing information on the impact of the consumer-brand relationship. The results of the study indicate that among the customer service employees' human brand characteristics reliability, familiarity, and empathy were found to affect the relationship between customers, the service brand, and the attitude toward the service brand the most. This study provides important implications for theoretical and practical strategies by examining the qualities and characteristics of customer service employees, which are the most important agents of marketing.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.10
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• pp.1267-1274
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• 2012

A guide vane plays a key role in controlling the flow rate of water supplied to the turbine of a hydropower plant. It has been reported that guide vane bearing bushings are subjected to considerable wear, which requires them to be maintained. An ancillary service such as frequency control and black start causes cyclic low opening operation of the guide vanes. It is empirically well known that such operation increases the wear rate of the guide vane bearing bushing. In this study, the effect of low opening operation on the increasing wear of the guide vane bearing bushing is quantitatively assessed via finite element flow analysis, finite element stress analysis, and relative wear evaluation. As a result of the assessment, it is identified that the pressure applied on the guide vane surface increases and the contact length between the outer surface of the guide vane stem and the inner surface of the bearing bushing decreases with a decrease in the opening of the guide vane. In addition, low opening of the guide vanes results in an increase in the relative wear owing to the generation of high contact pressure on the bearing bushing surfaces.

• Journal of Korean Ophthalmic Optics Society
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• v.20 no.1
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• pp.51-60
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• 2015

Purpose: To determine the effect of marketed multipurpose contact lens solutions (MPSs) on human corneal epithelial cells (HCEpiCs) toxicity by using image analysis. Methods: HCEpiCs were exposed six MPSs (product A-F) at 0.05~50% for 2h, 12h, 24h, and 48h respectively. HCEpiCs were fixed and stained with Draq5 after exposure with MPSs, and the cell viability and apoptosis were evaluated by using confocal microscope and ImageXpress UltraTM. Results: Viabilities of HCEpiCs exposed to MPS A-F for a 2h were not affected, while reductions (52~75%) in cell viability over a 12h exposure of MPS B, MPS C, MPS D and MPS F, and significant more reductions (29~73%) over a 24h and 48h-exposure. Apoptosis of HCEpiC was not affect over a 12h MPS exposure, however was significantly increased (199~526%) over 24h and 48h MPS exposure. Among the products MPS D, E and F reduced viability of HCEpiCs and apoptosis increased more than MPS A (p<0.05). Conclusions: Lower concentration of MPSs have not an cytotoxic effect on HCEpiCs, however higher concentration of MPSs induce apoptosis and reduce viability of HCEpiCs. Therefore, it need to develop MPS having antimicrobial effectiveness with low cytotoxicity.

• Journal of the Korean Society of Clothing and Textiles
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• v.39 no.3
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• pp.369-378
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• 2015

Various forms of wearable bio-signal monitoring systems have been developed recently. Acquisition of stable bio-signal data for health care purposes needs to be unconscious and continuous without hindrance to the users' daily activities. The garment type is a suitable form of a wearable bio-signal monitoring system; however, motion artifacts caused by body movement degrade the signal quality during the measurement of bio-signals. It is crucial to stabilize the electrode position to reduce motion artifacts generated when in motion. The problems with motion artifacts remain unresolved despite their significant effect on bio-signal monitoring. This research creates a foundation for the design of garment-type wearable systems for everyday use by finding a method to reduce motion artifacts through modular design. Two distinct garment-type wearable systems (tee-shirt with a motion artifact-reducing module (MARM) and tee-shirt without a MARM) were designed to compare the effects of modular design on the measurement of heart activity in terms of electrode position displacement, signal quality index value, and morphological quality. The tee-shirt with MARM showed superior properties and yielded higher quality signals than the tee-shirt without MARM. In addition, the tee-shirt with MARM showed a better repeatability of the heart activity signals. Therefore, a garment design with MARM is an efficient way to acquire stable bio-signals while in motion.

• Journal of the Korean Wood Science and Technology
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• v.33 no.6 s.134
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• pp.87-94
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• 2005

This study was carried out to investigate the effect of soil types and soil properties on wood preservative leaching. Radiata pine (Pinus radiata Don.) sapwood stakes, which had been treated with 2.0%(w/v) CCA, were leached for 12 weeks by a common laboratory method in four different soils and for 14 days by the AWPA standard leaching method in water. The physical and chemical properties of the four soils were determined, and the percent leaching of the individual component of CCA was correlated with the various soil properties. The data show that leaching of preservative chemicals from treated wood exposed to soil is influenced by the type of soil. The preservative leaching was greater when wood was exposed to water than when the wood was in contact with water-saturated soil. The greatest chromium, copper and arsenic leaching from CCA-treated stakes were observed in the sandy loam, loam, and sand, respectively, and the least amount of leaching of CCA components occurred in the silty loam. The leaching of preservative components from treated wood is extremely complex and appears to be influenced differently by the soil properties. The extent of copper leaching from CCA treated wood appears to be related to exchangeable Mg and sum of bases. There is a reasonably good relationship between chromium leaching and exchangeable Mg, and between arsenic leaching and exchangeable K, soil Ni, Mn, Fe, Cr, or Cu content. Since this study was conducted based on laboratory leaching method using small cross-sectional dimensions; thus, data obtained from this experiment should not be used to predict leaching characteristics from commercial-size wood used in real situation. Accordingly, further studies are necessary using outdoor ground-contact leaching.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.1 no.2
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• pp.79-93
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• 1991

With the advent of ULSI, many problems in previous metallization techniques and interconnection materials have become more serious. In this work, selective deposition of copper to fill the submicron contact has been tried. After forming electro-deposited copper films on p-type (100) silicon wafer using 0.75M $CuSO_4{\cdot}$5H_2O$ as an electrolyte, the effect of deposition time, current density and concentration of an additive on film properties were investigated. Film thickness, particle size and resistivity were analyzed by Alpha Step, SEM and 4 - point probe measurement respectively. The deposition rate was about $0.5-0.6\mu\textrm{m}$/min at $2A/dm^2$ and the particle size increased with increasing current density. The resistivities of electro-deposited copper films were about $3-6{\mu}{\Omega}{\cdot}$cm for the particle size above $4000{\AA}$. By the addition of 0.2 g/l gelatin, the particle size was reduced to less than $0.1{\mu}m $ and selective plugging of copper on submicron contacts could be successfully achieved.

• Korean Journal of Materials Research
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• v.27 no.10
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• pp.518-523
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• 2017

In commercial solar cells, the pattern of the front electrode is critical to effectively assemble the photo generated current. The power loss in solar cells caused by the front electrode was categorized as four types. First, losses due to the metallic resistance of the electrode. Second, losses due to the contact resistance of the electrode and emitter. Third, losses due to the emitter resistance when current flows through the emitter. Fourth, losses due to the shading effect of the front metal electrode, which has a high reflectance. In this paper, optimizing the number of finger on a $4{\times}4$ solar cell is demonstrated with known theory. We compared the short circuit current density and fill factor to evaluate the power loss from the front metal contact calculation result. By experiment, the short circuit current density($J_{sc}$), taken in each pattern as 37.61, 37.53, and $37.38mA/cm^2$ decreased as the number of fingers increased. The fill factor(FF), measured in each pattern as 0.7745, 0.7782 and 0.7843 increased as number of fingers increased. The results suggested that the efficiency(Eff) was measured in each pattern as 17.51, 17.81, and 17.84 %. Throughout this study, the short-circuit current densities($J_{sc}$) and fill factor(FF) varied according to the number of fingers in the front metal pattern. The effects on the efficiency of the two factors were also investigated.