• Journal of Power Electronics
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• v.19 no.1
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• pp.234-243
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• 2019

Studying the control strategy of a microgrid under the load unbalanced state helps to improve the stability of the system. The magnitude of the power fluctuation, which occurs between the power supply and the load, is generated in a microgrid under the load unbalanced state is called negative sequence reactive power $Q^-$. Traditional power distribution methods such as P-f, Q-E droop control can only distribute power with positive sequence current information. However, they have no effect on $Q^-$ with negative sequence current information. In this paper, a stationary-frame control method for power sharing and voltage unbalance compensation in islanded microgrids is proposed. This method is based on the proper output impedance control of distributed generation unit (DG unit) interface converters. The control system of a DG unit mainly consists of an active-power-frequency and reactive-power-voltage droop controller, an output impedance controller, and voltage and current controllers. The proposed method allows for the sharing of imbalance current among the DG unit and it can compensate voltage unbalance at the same time. The design approach of the control system is discussed in detail. Simulation and experimental results are presented. These results demonstrate that the proposed method is effective in the compensation of voltage unbalance and the power distribution.

• Asian Journal of Business Environment
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• v.13 no.2
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• pp.21-28
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• 2023

Purpose: This study aims to analyze the determinants of Green Total Factor Productivity (Green TFP) growth in the agricultural sector in Indonesia from 1980-2018. Research design, data, and methodology: The growth of Green TFP in the agricultural sector is calculated using the Growth Accounting Method. Moreover, this study uses multiple linear regression to analyze the determinants of the growth of Green TFP in the agricultural sector in Indonesia. Results: The survey results show that the average growth of Green TFP in the agricultural sector in Indonesia is still negative, which indicates that the efficiency of production factor or mastery of technology is still low. Inflation and patent applications are variables that significantly affect the growth of Green TFP in the agricultural sector, where the inflation variable has a negative effect. In contrast, the variable growth of patent applications has a positive impact. Conclusions: The government needs to continue to improve efficiency by organizing various programs related to increasing mastery of technology in the agricultural sector. The government also needs to advance research and development by promoting patents to become research incentives and impact the improvement of new technologies, especially those related to the environment. Moreover, economic stability needs to be maintained through inflation control.

• The Journal of Asian Finance, Economics and Business
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• v.10 no.1
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• pp.133-143
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• 2023

The detrimental impacts of financial instability on the world economy during the financial crisis highlighted the requirement to understand the existing financial circumstances. Stability and developments in financial conditions are important for economic prosperity. This study analyses the impact of geopolitical risk on the economic conditions of some specific emerging economies using monthly data from January 1999 to September 2016 by applying a fixed-effects panel data model. The estimation results demonstrated that geopolitical risk has a significant, negative impact on financial conditions. It shows geopolitical risk could be seen as a key factor that contributes towards financial conditions. Further, it implies that negative shocks of high geopolitical risk experienced by emerging economies are one of the primary reasons for the financial conditions' deterioration. The findings provide important insights for governments, policymakers, and investors. For instance, governments and politicians should refrain from expressing or producing tension, economic discomfort, or news that is likely to increase a high geopolitical risk. Maintaining a close eye on geopolitical risk and its sources may also help to stabilize financial conditions and develop a well-functioning financial system. As a result, investors would be better informed about an economy's economic and financial conditions, allowing them to diversify their international portfolios and devise investing strategies during uncertain economic times.

• Structural Engineering and Mechanics
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• v.87 no.2
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• pp.117-127
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• 2023

To efficiently attenuate seismic responses of a structure, a novel pneumatic-driven active dynamic vibration absorber (PD-ADVA) is proposed in this study. PD-ADVA aims to realize closed-loop control using a simple and intuitive control algorithm, which takes the structure velocity response as the input signal and then outputs an inverse control force to primary structure. The corresponding active control theory and phase control mechanism of the system are studied by numerical and theoretical methods, the system's control performance and amplitude-frequency characteristics under seismic excitations are explored. The capability of the proposed active control system to cope with frequency-varying random excitation is evaluated by comparing with the optimum tuning TMD. The analysis results show that the control algorithm of PD-ADVA ensures the control force always output to the structure in the opposite direction of the velocity response, indicating that the presented system does not produce a negative effect. The phase difference between the response of uncontrolled and controlled structures is zero, while the phase difference between the control force and the harmonic excitation is π, the theoretical and numerical results demonstrate that PD-ADVA always generates beneficial control effects. The PD-ADVA can effectively mitigate the structural seismic responses, and its control performance is insensitive to amplitude. Compared with the optimum tuning TMD, PD-ADVA has better control performance and higher system stability, and will not have negative effects under seismic wave excitations.

• Journal of Korea Society of Digital Industry and Information Management
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• v.20 no.2
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• pp.125-139
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• 2024

High turnover and short tenure in the gaming industry has been a problem since the 2000s. Although high turnover can increase the flexibility of working hours, it has a negative impact on labor stability, and the negative effects of turnover outweigh the positive effects for companies, so efforts are needed to reduce turnover intention, an antecedent of turnover. Therefore, this study investigated the factors affecting turnover intention of employees in the game industry, focusing on organizational commitment and job satisfaction, which are factors that affect turnover intention through previous studies. The results of the regression analysis and mediation effect verification by conducting a questionnaire survey on 221 employees in the game industry showed that emotional engagement among the components of organizational commitment influences turnover intention through job satisfaction. Therefore, it is important to provide goals such as game release and rewards to keep employees emotionally engaged in order to reduce turnover intention.

• 한국사회정책
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• v.19 no.2
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• pp.9-38
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• 2012

Little research has empirically examined cross-sector job mobility between non-profit and for-profit sector despite the rise and increased importance of this phenomenon in Korea. Using the panel data of Graduates Occupational Mobility Survey(GOMS) by the Korea Employment Information Service, this study attempts to examine changes in job satisfaction(overall score and 10 facet scores) associated with four types(retention at non-profits, turnover from non-profits to for-profits, turnover from for-profits to non-profits, and retention at for-profits) of cross-sector job mobility among college graduates by employing a first difference model. Major results reveal that (1) in the group of retention at non-profits, 'overall job satisfaction' is consistently higher; (2) in the group of retention at non-profits, negative change in 'overall job satisfaction' is the largest; (3) in the group of 'for-profits to non-profits,' negative change in 'stability of employment' is the smallest; (3) in the group of 'non-profits to for-profits,' negative change in 'job contents' is the smallest; (4) in the group of 'non-profits to for-profits,' negative change in 'weekly work hours' is the largest; (5) in the group of retention at non-profits, negative change in 'potential growth & development' is the largest; and (6) in the group of retention at non-profits, negative change in 'social reputation' is the smallest;. This study has made a start in a new area of inquiring attempting to explain cross-sector job mobility and raises implications for future research.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.6
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• pp.654-659
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• 2016

Recently, the passenger ship 'Sewol' capsized with an abrupt inclination while she was making a small angle alteration. It is very important to fully understand the concepts, causes and relevant corrections for a ship's transverse inclination, which is classified into heel, list and loll. In this study, the concept, development and calculation of loll were well considered and the actual magnitude of the angle of loll was simulated in a box-shaped model-ship experiment. The experimental values and its development according to different values of negative stability were compared with calculated values. In the results, experimental values for the angle of loll coincided closely with calculated values and the model inclined symmetrically on both port and starboard sides indicating an outstanding feature of loll. This study is expected to expand the concept of loll and help in the analysis of capsize incidents with unknown causes. Further experimental research or case studies concerning the risk of inappropriate correction for loll arising from misunderstandings will be needed.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.419-420
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• 2012

Lithium-ion battery (LIB) usually used for valuable electronic devices are extended to applications. High stability negative electrode materials for LIB were investigated using electrodeposition of nanoparticles (NPs) on the nanostructured carbon. NPs with about 70 nm diameters were evenly prepared on the graphitic carbon materials using electrodeposition process at room temperature. It was observed that the NPs were homogeneously embedded into not only external surface but bottom part of the graphitic carbon network. The graphitic carbon material covered with NPs enables facile electron transport owing to the network structure and improves structural collapse during cycling. This facile room temperature process is expected to be applicable to other anode materials such as Sn and Al for the anode of LIB.

• Bulletin of the Korean Chemical Society
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• v.31 no.2
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• pp.275-280
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• 2010

Actinobacillus actinomycetemcomitans is a gram-negative, nonmotile coccobacillus bacterium that is associated with several human diseases, including endocarditis, meningitis, osteomyelitis, subcutaneous abscesses and periodontal diseases. A full-length Omp1-like protein gene from A. actinomycetemcomitans was cloned into a pQE30 vector and overexpressed in Escherichia coli BL21(DE3) cells. The protein revealed sequence homologies to Seventeen kilodalton proteins (Skp) from Pasteurella multocida and E. coli that have been characterized as periplasmic chaperones. This soluble Omp1-like protein was successfully purified to homogeneity for further folding and functional studies. The purity, identity, and conformation of the protein were determined using sodium dodecyl sulfate polyacrylamide gel electrophoresis, matrix-assisted laser desorption ionization mass spectrometry, circular dichroism, fluorescence spectroscopic, and differential scanning calorimetric studies. We showed that the protein formed an oligomer larger than a tetramer. We found, further, that it is comprised of mostly $\alpha$-helices and boasts high thermal stability.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.6
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• pp.173-183
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• 2020

The paper investigates the determinants of foreign direct investment (FDI) in Vietnam in 2000-2019 period. This study uses difference Generalized Methods of Moments (GMM) and Pooled Mean Group (PMG) to analyse panel data officially provided by General Statistical Office of Vietnam. The results show that market size impacts positively significant on FDI attraction: 1% -1.45% (PMG) and 1% -1.25% (GMM). Besides, some other factors have positive influences as labor force, macroeconomic policy, macroeconomic stability and skilled labor. Meantime, the trade openness negatively affects FDI inflows in the short-term, while not being statistically significant in the long-term. Moreover, economic shocks often have a negative impact on FDI inflows. The findings of this study lead to the following recommendations. First, authorities should pay special attention to encourage economic growth rate in Vietnam to expand market size because this is the first priority of foreign investors. Second, authorities need to continue increasing the rate of skilled labor, especially highly qualified management force, engineers and well-skilled workers. Third, the authorities should adjust trade openness to boost the role of its determinant in attracting FDI inflows. Fourth, macroeconomic stability needs to be governed by international standards in order to secure the belief of foreign investors in the long-term.