• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.378-382
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• 2008

Since the sheet metal forming of Mg alloy is perform at elevated temperature, the effect of strain rates related with the forming temperature and forming speed and R-value is very important factor for formability and forming limits and deep drawing. It is investigated that the effect of material properties such as various temperature, forming speed and strain rates on formability and R-value of Mg alloy sheet in round cup deep drawing. Therefore, the investigation for process variables is necessary to improve formability and forming limits and deep drawing. Also, the effects of strain rate and drawbility were studied by the experiment. The temperature, forming speed, and strain rates and R-value are investigated. Forming of Mg alloy takes consider into temperature, proper forming speed and strain-rate and R-value the formed parts were good without defects for forming limits and deep drawing.

• Asia Marketing Journal
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• v.22 no.3
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• pp.1-28
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• 2020

With the development of information and communication technology and spread of smart devices, online information exchange has become a daily routine. Accordingly, the management and utilization of online word of mouth (WOM) has become an important issue for companies. Numerous studies have examined the impact of online WOM on firm performance. This study analyzes the impact of negative word of mouth (NWOM) on firm value, considering the influence of corporate social responsibility (CSR) activity and research and development (R&D) investment. Using a hierarchical linear model, we find that 1) NWOM has a negative impact on firm value, 2) CSR activities do not significantly influence this impact, and 3) R&D investment reduces this negative impact. This study contributes by demonstrating the effect of NWOM on firm value, examining the influence of CSR activities and R&D investment on the impact of NWOM, and confirming that the hierarchical linear model can be applied effectively to panel data in empirical studies. As a practical implication, companies must prevent and manage NWOM, whose impact, when caused by an unavoidable incident, can be alleviated by proactively announcing that the company is striving for competitiveness, for instance, by investing in R&D.

• The Korean Journal of Applied Statistics
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• v.23 no.4
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• pp.669-681
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• 2010

Value-at-Risk(VaR) is an important part of risk management in the financial industry. This paper present a VaR forecasting for financial time series based on the quantile regression for GARCH models recently developed by Lee and Noh (2009). The proposed VaR forecasting features the direct conditional quantile estimation for GARCH models that is well connected with the model parameters. Empirical performance is measured by several backtesting procedures, and is reported in comparison with existing methods using sample quantiles.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2000.04a
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• pp.206-209
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• 2000

Groove pressing which is analogous to groove rolling in the aspect of deformation mode was designed and influence of the uncommon shear deformation on the development of texture and R value was investigated. Texture developed by the groove pressing were measured as well as predicted. It was found out that the main component in the developed texture was {40。, 45。, 0。} in ODF which was regarded as a rotated Bs component and rarely observed in a plain rolling. The maximum R value was predicted to be 3.8 in 45。 direction which might be attributed to the new component.

• Tunnel and Underground Space
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• v.11 no.4
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• pp.289-300
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• 2001

In the design of tunnel, it contains inaccuracy of data, fuzziness of evaluation, observer error and so on. The face observation during tunnel excavation, therefore, plays an important role to raise stability and to reduce supporting cost. This study is carried out to minimize the subjectiveness of observer and to exactly evaluate the natural properties of ground during the face observation. For these purpose, fuzzy set theory and neuro-fuzzy techniques in artificial intelligent techniques are applied to the inference of the RMR value from the observation data. The correlation between original RMR vague and inferred RM $R_{_FU}$ and RM $R_{_NF}$ values from fuzzy set theory and neuro-fuzzy techniques is investigated using 46 data. The results show that good correlation between original RMR value and infected RM $R_{_FU}$ and RM $R_{_NF}$ value is observed when the correlation coefficients are ｜R｜=0.96 and ｜R｜=0.95 respectively. From these results, applicability of fuzzy set theory and neuro-fuzzy techniques to rock mats classification is proved to be sufficiently high enough. enough.

• Environmental and Resource Economics Review
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• v.20 no.3
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• pp.459-487
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• 2011

A/R CDM project has properties such as irreversibility and uncertainty that Real Option Analysis can be applied to its modelling. This study tries to model A/R CDM using Real Option under CER price uncertainty, and conducts empirical test with the Posco A/R CDM Project case. For precise comparison and decision-making, l-CER's expected present value is calculated from the Spot CER price. As a result, the critical value of the project is lower than the expected l-CER price, which means that the decision to invest made by the project owner is profitable. We can also find out that the level and the range of the discount rate, where is applied to, affect the result; the critical value of the project and the decision-making.

• Asia pacific journal of information systems
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• v.32 no.4
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• pp.728-749
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• 2022

The information and communication technology (ICT) value creation process is inherently unobservable. In addition to the direct effect of ICT on productivity, some information or knowledge can create value through other knowledge activities. In this paper, we study the impact of ICT on productivity through R&D. We tested the mediating effect of R&D between ICT and productivity using panel data from 47 US industries from 1987 to 2013 from the Bureau of Labor Statistics. The results show that R&D partially mediates ICT and productivity. That is, ICT directly increases productivity, and some of its effects can be realized through R&D. Recipients who acquire knowledge through ICT have to interpret codified ideas and apply them to practice. The increased absorptive capacity that can be developed through R&D improves interpretation ability, allowing employees to share more complex ideas. Thus, ICT helps people to effectively communicate, but some information and knowledge can be realized and applied through R&D knowledge activities. This is the first study empirically examining the process of ICT value creation through R&D. It also provides practical guidelines for knowledge management, such as making decisions about ICT and R&D investments that are better done concurrently rather than individually to maximize their impact on productivity.

• Journal of the Korean Data and Information Science Society
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• v.16 no.2
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• pp.283-288
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• 2005

Value at Risk(VaR) has been proven useful in finance literature as a tool of risk management(cf. Jorion(2001)). This article is concerned with introducing VaR to various Korean financial time series. Five daily data sets with sample period ranging from 2000 and 2004 such as KOSPI, KOSPI 200, KOSDAQ, KOSDAQ 50 and won-dollar exchange rate are analyzed using GARCH modeling and in turn VaR is obtained for each data.

• Journal of Preventive Medicine and Public Health
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• v.29 no.3 s.54
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• pp.439-449
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• 1996

This study was conducted to evaluate the relationship between change in obesity indices and change in serum lipids in adult male workers. Two-hundred-eight adult male workers of an industry in Taegu city were followed-up from 1991 to 1995. Height, weight, circumferences of hip and waist, blood pressure were measured and serum lipids were analysed. Data on life style were obtained using self-administered questionnaires. Mean differences of anthropometric measurements between 1991 and 1995 were as follows: 1.63kg in weight, 3.61cm in waist circumferences, 4.23cm in hip circumferences, $0.52kg/m^2$ in BMI and -0.021 in WHR. Those of lipids were as follows; 15.09mg/dl in total cholesterol, 20.43mg/dl in triglyceride, 9.40mg/dl in HDL-cholesterol, 2.87 in MI - index (p<0.01) and 350mg/dl in LDL-cholesterol. The changed value of BMI and Katsura index were strongly correlated with that of total cholesterol(r=0.174, p<0.05), the changed value of BMI correlated with that of triglyceride(r=0.374, p<0.01) and the changed value of weight correlated with that of MI index(r=-0.173, p<0.05). The changed value of WHR was signifiantly correlated with that of total cholesterol(r=0.162, p<0.05), however, was not significantly correlated with HDL-cholesterol, LDL-cholesterol, triglyceride and MI index. The changed value of weight, BMI and Katsura index were correlated with that of triglyceride (r=0.262, p<0.01; r=0.267, p<0.01; r=0.258, p<0.01) and the changed value of MI index(r=0.143, p<0.05; r=-0.158; r=-0.144, p<0.01), adjusting the pattern of change in life style. The changed values of HDL - cholesterol and MI index between 1991 and 1995 in low WHR group were significantly higher than those in high WHR group(p<0.05, p<0.01), adjusting the baseline value of them. Similar pattern was observed when considering Katsura index. When stratifying by BMI value of 1991, in low BMI group, the changed value of HDL - cholesterol and MI index showed the same pattern as above, however that of triglyceride was statistically higher in obese group than in non obese group(p<0.05). In conclusion BMI might be a better indicator to predict serum lipids change than other obesity indices.

• Journal of the Korean Mathematical Society
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• v.43 no.6
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• pp.1199-1217
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• 2006

The main purpose of this paper is using the properties of Gauss sums, primitive characters and the mean value theorems of Dirichlet L-functions to study the hybrid mean value of the T-th hyper-Kloosterman sums Kl(h, k+1, r;q) and the hyper Cochrane sums C(h, q; m, k), and give an interesting mean value formula.