• Journal of Welding and Joining
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• v.19 no.6
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• pp.622-629
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• 2001

The aim of this experiment is to establish the method that obtains symmetrically two nuggets in microresistance series spot welding. The sheets of austenite stainless steel STS304 applied to various electronic parts were experimented by the inverter welding power source of polarity controllable type and by the twin head for left and right electrode force to be controlled separately. The experimental results were obtained as follows : 1) When series spot welding was carried out by DC 1 pulse as welding current with same electrode force at left and right, the asymmetry of nuggets was resulted from the larger nugget of the (-) pole because of the Peltier effect. The dynamic resistance of weld spot at left and right was appeared differently according to the growth of nuggets. 2) When AC 1 cycle by welding power source of polarity controllable type was applied, the nuggets were almost symmetrically formed. 3) In a twin head, if the electrode force of (-) pole was larger than that of (+) pole, the diameters of two nuggets became to same. It was confirmed that the dynamic resistance of (-) pole was decreased to the same level as it of (+) pole. 4) Although the forces of left and right electrode were same, and only DC 1 pulse was applied, symmetric nuggets were obtained if the conductivity of (+) pole was lower than it of (-) pole.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.3
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• pp.31-38
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• 2021

The study investigates the diversification behavior of Islamic stocks against US financial uncertainty. Considering limitations found in the literature, a comprehensive index of financial uncertainty (FU) is used, developed by Jurado, Ludvigson, and Ng (2015). The empirical analysis uses monthly data from four Islamic markets - Saudi Arabia, Malaysia, Indonesia, and Turkey - for the period from January 2010 to September 2019. Results of the bivariate EGARCH models show that Islamic stocks can be used for diversification purpose against the financial uncertainty of the US because the volatility of US uncertainty does not propagate in the Islamic stock markets. Moreover, findings show that the spillover effect of financial uncertainty varies with the FU forecast horizon. The spillover effect of FU increases with an increase in the FU forecast horizon and becomes significant over 3-month and 12-month periods in the case of Saudi Arabia. The current volatility of Islamic stock returns is independent of the size of shocks in past volatility. The leverage effect and asymmetry have been found in Saudi Arabia and Malaysia. The findings validate the arguments of the literature that Islamic markets are resilient facing uncertainties and perform well during crisis periods. The findings are important for investors in making better portfolio decisions.

• International Area Studies Review
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• v.18 no.3
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• pp.67-88
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• 2014

The Chinese stock market has increasingly strengthened its market power on other stock markets due to rapid growth of its economy. In this context, this study investigated return spillover effect as well as asymmetric volatility spillover effect using a VAR-Bivariate EGARCH model among stock markets(China, US, Japan, Korea). Furthermore, we conjectured the impact of 2008 global financial crisis on the spillover effect of the Chinese stock market. In our empirical results, the Chinese stock market has a weak return spillover effect to other markets(US, Japan, Korea), but after the global financial crisis, its return spillover effect becomes stronger among other stock markets. In addition, the Chinese stock market have strengthened its asymmetric volatility spillover effect on other stock markets after the Global financial crisis. As a result, the Chinese stock market has an strong influence on other stock markets.

• KDI Journal of Economic Policy
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• v.36 no.4
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• pp.33-69
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• 2014

We investigate determinants of fund investment flows using Korean equity investment funds. Unlike previous studies which analyzed net-flows (inflow minus outflow), we analyze fund investment inflows and outflows separately that should properly reflect investors' fund selection and redemption decision. We find similar effects of past return, fund age on net-flows to existing studies based on US market data. The analysis of determinants of inflows shows that inflows are related to past return, fund age and sales fee as net-flows. In contrast, outflows are found to behave quite differently from inflows. Apparently, asymmetry exists between fund investment inflows and outflows at the Korean fund selection market. Specifically, high past returns increase fund investment inflows while increase, rather than decrease, fund outflows. Moreover, 'convexity' is detected both in inflows and outflows: higher past returns accelerate outflows as well as inflows. Effects of sales fee also differ between inflows and outflows. In the 'affiliated' fund sample, sales fee is negatively related to inflows while positively related to outflows. In the 'unaffiliated' fund sample, sales fee is positively related to inflows, but no significant relationship exists with outflows. Empirical findings of this paper imply that the rational investor's fund selection view cannot provide a consistent explanation of the Korean fund selection market. In particular, the positive and convex relationship between past returns and fund outflows is inconsistent with the rational investor view. The fact that investor's fund investment appears to display 'disposition effect', which has been reported by studies of individual investors' stock investment behaviour suggests that the behavioral finance view should be a part of explanation for the Korean fund selection market. In addition, the strikingly different patterns between the 'affiliated' funds and the 'unaffiliated' funds, imply that brokers' incentive structure is another prevailing factor for fund investment flows.

• Journal of Korea Entertainment Industry Association
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• v.13 no.1
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• pp.207-215
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• 2019

This study examines the effect of the height of cane that hemiplegic patients due to stroke use on their plantar pressure in standing position, gait speed. The study suggests a new standard for appropriate cane height that considers the change of average height of population. Research subjects included 12 patients hospitalized in S Medical Care Hospital located in Gwangju Metropolitan City in South Korea who were diagnosed with stroke. Group A uses a cane of the height of the greater trochanter of femur, group B uses a cane of 5cm above the height of the greater trochanter of femur, and group C is a cane of 10cm above the height of the greater trochanter of femur. In the study result, non-affected side plantar pressure and affected side plantar pressure showed a significant difference among the cases where the cane height was the same as the A group, B group, C group. In the post-hoc analysis result, a significant difference was observed between the case of A group and C group. Gait speed showed no significant difference among the case of the A group, B group, C group. The asymmetry of the stroke affects not only the posture but also the walking that is related to daily life. Changes in the height of the cane did not affect walking speed. The change in the height of the cane showed a change in the weight support ratio, which is thought to have a positive effect on the asymmetry. In future clinical setting, this study result will be able to provide fundamental data regarding the cane height in the standing or walking therapy for hemiplegic patients due to stroke with cane application.

• Journal of the Korean Society of Industry Convergence
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• v.4 no.1
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• pp.77-85
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• 2001

This paper was to investigate the preparation of polysulfone(PS), polyethersulfone(PES) and polyphenylsulfone(PPS) membrane. The thermal property of PPS was higher than that of others. From the result of SEM, the concentration of polymer was found to have a significant effect on the structure of membrane, and the structure of membrane made of PES is found to have regular micell form of asymmetry. Permeability and selectivity for oxygen and nitrogen gas in the air were analyzed by GC. Permeabilities of the membrane made of PES for oxygen and nitrogen in air, 1.5 and $0.7(x10^9[cm^3(STP)cm/cm^2seccmHg]) $, respectively was higher than that of others. and Selectivity of the membrane made of PPS for oxygen to nitrogen gas in air was 2.9.

• Bulletin of the Korean Chemical Society
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• v.35 no.5
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• pp.1501-1505
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• 2014

Molecular dynamics simulations were performed to understand the structural arrangement of water molecules around highly charged nanoparticles under aqueous conditions. The effect of two highly charged nanoparticles on the solvation charge asymmetry has been examined. We calculated the radial distribution functions of the components of water molecules around nanoparticles which have four charge types at two different salt concentrations. Even though the distributions of water molecules surrounding a sodium ion and a chloride ion are hardly affected by the charges of nanoparticles and the salt concentrations, those around highly charged nanoparticles are strongly influenced by the charges of nanoparticles, but hardly by the charges of nanoparticles and salt concentrations. We find that the distributions of hydrogen atoms in water molecules around one highly charged nanoparticle are dependent on the magnitude of the nanoparticle charge.

• Transactions of Materials Processing
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• v.14 no.4 s.76
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• pp.338-350
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• 2005

Recently, in the field of automobile industry, to solve the problem of reducing the weight of automobile for the improvement of fuel efficiency and the protection of environment, the aluminum alloy parts have been substituted for the steel parts. However, the aluminum alloy does not have as good mechanical property as the steel part. To improve the mechanical property, the semi-solid die casting process is performed to make automobile parts. In the fabrication of semisolid material the control of the liquid segregation is very important to improve the material properties of aluminum alloy. In the present paper we examine the influence of the liquid segregation by the injection conditions in the semi-solid die casting has been investigated.

• Publications of The Korean Astronomical Society
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• v.6 no.1
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• pp.38-49
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• 1991

Energy density evolution of primordial black holes(PBHs) due to quantum gravitational tunneling effect in the very early Universe is calculated for the four cases of GUTs(grand unified theories) (SM, SUSY SM, SUSY SU(5), SU(5)). For the three of them (SM, SUSY SM, SUSY SU(5)), it is confirmed that there are a considerable amount of PBHs and so it may give a firm support to Lindley's paper(1981) in which he tried to solve the baryon asymmetry problem. It is shown that the formation of PBHs increases the cosmic scale factor R and decreases the total energy density $\rho_t$ faster than in the usual radiation dominated era.

• Korean Institute of Interior Design Journal
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• v.13 no.4
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• pp.21-28
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• 2004

This study was carried out to understand the characteristics of stairs in Palladio's villa. The subject of study are selected the twenty two villas with drawing in his book ‘The four books of Architecture’. Their cases are represented the characteristics of stair in architectural composition. Accordingly, it was analyzed and classified the architectural characteristics into space, form and plan at a villa. In conclusion, in aspect of spacial plan, staircases of Palladio's villa was presented more open and light in comparison with darked space of the medieval age. And it was intended to the connection or division between spaces of different character In an aspect of formal plan, dynamic form of stairs was divided into the two types. First, it was represented the effect of articulation in form. Second, stairs were represented the diagonal with the shape of itself. In an aspect of plan, his idea is coexisted with traditional thought and rational idea through the arrangement of symmetry md asymmetry. But at any rate, his concern was sought for the reasonable position. Also, he had represented the various characteristics in stairs such as his works in Renaissance period.