• The Journal of the Korea Contents Association
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• v.19 no.2
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• pp.508-515
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• 2019

The purpose of this study is to reanalyze the impact of college education in the Korean economic growth during the period 1971-2017. The study estimates the impacts of monthly average income per worker without college education with respects to the ratio of workers with college education to worker without college education, capital per worker without college education, and the number of patients per worker with college education. The results showed that the effect of the ratio of workers who had college education was 0.433 at 5% of significant level. In addition, it was estimated that the effect of the capital for each worker who didn't have college education was 0.45646 at 1% of significant level. These findings are similar to the results in the previous study of Kim and Lim. Finally, the number of patents per worker who had college education was estimated. Unfortunately, the coefficients on these were not statistically significant except for one period. Therefore, it is concluded that there is a positive spillover effect from the college education in the Korean economic growth.

• Environmental and Resource Economics Review
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• v.22 no.4
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• pp.671-689
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• 2013

Transmission mechanisms of volatility between two crude oil markets (WTI and Brent markets) have drawn the attention of numerous academics and practitioners because they both play crucial roles in portfolio and risk management in crude oil markets. In this context, we examined the volatility linkages between two representative crude oil markets using a VECM and an asymmetric bivariate GARCH model. First, looking at the return transmission through the VECM test, we found a long-run equilibrium and bidirectional relationship between two crude oil markets. However, the estimation results of the GARCH-BEKK model suggest that there is unidirectional volatility spillover from the WTI market to the Brent market, implying that the WTI market tends to exert influence over the Brent market and not vice versa. Regarding asymmetric volatility transmission, we also found that bad news volatility in the WTI market increases the volatility of the Brent market. Thus, WTI information is transmitted into the Brent market, indicating that the prices of the WTI market seem to lead the prices of the Brent market.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.12
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• pp.683-692
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• 2020

The primary purpose of the study is to investigate the volatility spillovers from global economic policy uncertainty and macroeconomic factors to the Islamic stock market returns. The study focuses on the Islamic stock indices of emerging economies including Indonesia, Malaysia, and Turkey. The Macroeconomic factors are industrial production, consumer price index, exchange rate. EGARCH model is employed for investigation of volatility spillovers. The results show that the global economic policy uncertainty has a significant spillover effect only on the returns of Turkish Islamic stock index. Similarly, the shocks in macroeconomic factors have little influence on the volatility of Islamic indices returns. The volatility of Indonesian and the Turkish Islamic stock indices returns is not influenced from the fluctuations in macroeconomic factors. However, there is significant volatility spillover only from industrial production to the returns of Malaysian Islamic index. The results suggest that the Islamic stock markets are less likely to influence from the global economic policies and macroeconomic factors. The stability of Islamic stocks provide opportunity for diversification of portfolios, particularly in stressed market conditions. The major price factors of Islamic markets could be firms' specific factors or investors' behaviors. The findings are helpful for policy makers and investors in formulating policies and portfolios.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2000.04a
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• pp.154-157
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• 2000

Distributed piezoelectric sensor and actuator system has been designed for the active vibration control of shell structure. PVDF is used for the materials of sensor/actuator. To prevent the adverse effect of spillover, distributed modal sensor/actuator system is established. Although shell structure is three-dimensional structure, the PVDF sensor/actuator system can be treated as two-dimensional Finite element programs are developed to consider curved structures having PVDF modal sensor/actuator. The nine-node Mindlin shell element with five nodal degree of freedoms is used for finite element discretization. The electrode patterns and lamination angle of PVDF sensor/actuator are optimized to design the modal sensor/actuator system Genetic algorithm is used for optimization. Sensor is designed to minimize the observation spillover, and actuator is designed to minimize the system energy of the control modes under a given initial condition. Modal sensor/actuator for the first and second modes of singly curved cantilevered shell structure are designed using mentioned methods. Discrete LQG method is used as a control law. Experimental demonstrations of the active vibration control with designed sensor/actuator system have been performed successfully.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.6
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• pp.923-934
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• 1987

A flexible one-link robotic manipulator is modelled as a rotating cantilever beam with a hub and tip mass. An active control law is developed with consideration of the distributed flexibility of the arm. Equation of motion is derived by Hamilton's principle and, for modal control, represented as state variable form using Galerkin's mode summation method. Feedback coefficients are chosen to minimize the linear quadratic performance index(PI). To reconstruct the complete state vector from the measurements, an observer is proposed. In order to suppress vibration of the manipulator arm to desirable extent and to obtain accuracy of the positioning, weighting factor of input in PI is adjusted. Spillover effect due to the controller which controls several important modes is examined. Experiment is also performed to validate the theoretical analysis.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.508-514
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• 2005

This paper is concerned with the active vibration control of a grid structure equipped with piezoceramic sensors and actuators. The grid structure is a replica of the solar panel commonly mounted on satellites, which contains complex natural mode shapes. The multi input and multi output positive position feedback controller is considered as an active vibration controller for the grid structure. A new concept, the block-inverse technique, is proposed to cope with more modes than the number of actuators and sensors. This study also deals with the stability and the spillover effect associated with the application of the multi-input multi-output positive position feedback controller based on the block inverse technique. It was found that the theories developed in this study are capable of predicting the control system characteristics and its performance. The new multi-input multi-output positive position feedback controller was applied to the test structure using a digital signal processor and its efficacy was verified by experiments..

• Journal of Distribution Science
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• v.15 no.1
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• pp.15-20
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• 2017

Purpose - Other customers within the same service environment do influence a customer' attitude and behavior toward a service firm. Specially, other customers' misbehaviour and various service problems stemmed from them could make the other customers suffer some bad experiences. However, there are few studies to answer how the spillover effect of a service failure arisen from other customers' misbehavior. This study is aimed to examine how service failure due to the dysfunctional behavior of other customers has negative effects on customer evaluation with the service provider. Research design, data, and methodology - Data were collected from a survey based on consumers' retrospective experiences in airline service context. The hypothesized relationships were tested conducting structural equation modeling. Results - Our results show that the attribution of a firm responsibility for other-customer failure has a positive influence on customer's recovery expectation, in turn, it is negatively related to customer satisfaction. Furthermore, perceived service provider's efforts positively influence customer satisfaction. Conclusions - Although a service failure was caused by other customer's misbehavior, employees should be able to alleviate any bad feelings of the affected customers. Furthermore, service providers should provide proper recovery efforts for solving problems caused by the other customers for the wounded customers.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.9 s.102
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• pp.1037-1044
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• 2005

This paper is concerned with the active vibration control of a grid structure equipped with piezoceramic sensors and actuators. The grid structure is a replica of the solar panel commonly mounted on satellites, which contains complex natural mode shapes. The multi-input and multi-output positive position feedback controller is considered as an active vibration controller for the grid structure. A new concept, the block-inverse technique, is proposed to cope with more modes than the number of actuators and sensors. This study also deals with the stability and the spillover effect associated with the application of the multi-input multi-output positive position feedback controller based on the block-inverse technique. It was found that the theories developed in this study are capable of predicting the control system characteristics and its performance. The new multi-input multi-output positive position feedback controller was applied to the test structure using a digital signal processor and its efficacy was verified by experiments.

• International Journal of Aeronautical and Space Sciences
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• v.7 no.1
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• pp.106-117
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• 2006

The active vibration control of composite shell structure has been performed with the optimized sensor/actuator system. For the design of sensor/actuator system, a method based on finite element technique is developed. The nine-node Mindlin shell element has been used for modeling the integrated system of laminated composite shell with PVDF sensor/actuator. The distributed selective modal sensor/actuator system is established to prevent the effect of spillover. Electrode patterns and lamination angles of sensor/actuator are optimized using genetic algorithm. Continuous electrode patterns are discretized according to finite element mesh, and orientation angle is encoded into discrete values using binary string. Sensor is designed to minimize the observation spillover, and actuator is designed to minimize the system energy of the control modes under a given initial condition. Modal sensor/actuator for the first and the second mode vibration control of singly curved cantilevered composite shell structure are designed with the method developed on the finite element method and optimization. For verification, the experimental test of the active vibration control is performed for the composite shell structure. Discrete LQG method is used as a control law.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2000.11a
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• pp.228-231
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• 2000

The active vibration control of laminated composite shell has been performed with the optimized sensor/actuator system. PVDF film is used fur the material of sensor/actuator. Finite element method is utilized to model the whole structure including the piezoelectric sensor/actuator system, The distributed selective modal sensor/actuator system is established to prevent the adverse effect of spillover. In the finite element discretization process, the nine-node shell element with five nodal degrees of freedoms is used. Electrode patterns and lamination angles of sensor/actuator are optimized using genetic algorithm. Sensor is designed to minimize the observation spillover, and actuator is designed to minimize the system energy of the control modes under a given initial condition. Modal sensor/actuator profiles are optimized for the first and the second modes suppression of singly curved cantilevered composite shell structure. Discrete LQG method is used as a control law. The real time vibration control with profile optimized sensor/actuator system has been performed. Experimental result shows successful performance of the integrated structure for the active vibration control.