• Journal of Electrical Engineering and Technology
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• v.7 no.6
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• pp.834-844
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• 2012

Nonlinear electronic loads draw harmonic currents from the power grids that can cause energy loss, miss-operation of power equipment, and other serious problems in the power grids. This paper proposes a harmonic compensation method using multiple distributed resources (DRs) such as small distributed generators (DGs) and battery energy storage systems (BESSs) that are integrated to the power grids through power inverters. For harmonic compensation, DRs should inject additional apparent power to the grids so that certain DRs, especially operated in proximity to their rated power, may possibly reach their maximum current limits. Therefore, intelligent coordination methods of multiple DRs are required for efficient harmonic current compensation considering the power margins of DRs, energy cost, and the battery state-of-charge. The proposed method is based on fuzzy multi-objective optimization so that DRs can cooperate with other DRs to eliminate harmonic currents with optimizing mutually conflicting multi-objectives.

• Journal of Power Electronics
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• v.18 no.4
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• pp.1190-1200
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• 2018

A current sourced bi-directional wireless power transfer (WPT) system is proposed to solve the problems that exist in the bi-directional WPT for vehicle-to-grid (V2G) systems. These problems include the fact that these systems are not safe enough, the output power is limited and the control methods are complicated. Firstly, the proposed system adopts two different compensation and control methods on both the primary and secondary sides. Secondly, based on an AC impedance analysis, the working principle is analyzed and the parameter configuration method with frequency stability is given. In order to output a constant voltage, a bi-directional DC/DC circuit and a controllable rectifier bridge are adopted, which are based on the "constant primary current, constant secondary voltage" control strategy. Finally, the effectiveness and feasibility of the proposed methods are verified by experimental results.

• Korean Journal of Clinical Pharmacy
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• v.27 no.1
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• pp.30-37
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• 2017

Background: We investigated the impact of financial compensation on patients' decision of participation in clinical trials and the related factors with patients' attitudes and considerations. Methods: A survey questionnaire was placed from October 31 to November 16, 2017 to the subjects who were enrolled in the trials of chronic diseases. Patients' socio-demographic characteristics were collected and the potential reasons for participating in the trials were assessed using 5-likert scores. Results: Sixty eight of 110 respondents (61.8%) indicated to participate clinical trials regardless of financial compensation. The differences were found between patients who were unwilling to participate without compensation and those who were willing to participate regardless of compensation in mean ages (43.9 years vs. 52.0 years, p<0.05), marital status (married, 47.6% vs 79.4%, p<0.01), religions (yes, 45.2% vs 67.6%, p<0.05) and monthly income (${\geq}3$ million won, 19.0% vs 45.6%, p<0.01). The potential reasons for participation in the trials between two groups were doctor's suggestion (52.4% vs. 77.9%, p<0.01), the expectation of health improvement (54.8% vs. 73.5%, p<0.05), the types and numbers of procedure (33.3% vs. 16.2%, p<0.05) and the duration of clinical trials (59.5% vs. 27.9%, p=0.001). In regression analysis, the monthly income of ${\geq}3$ million won (odd ratio, OR=3.221, p=0.026,) and the duration of trials (OR=0.290, p=0.017) were related to the group with the willingness to participate regardless of compensation. Conclusion: This stady showed that more than half of study subjects would participate in the clinical trials of chronic diseases regardless of financial compensation.

• Safety and Health at Work
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• v.4 no.2
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• pp.95-99
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• 2013

Background: Work-related stress is one of the major causes of occupational ill health. In line with the regulatory framework on occupational health and safety (OSH), adequate models for assessing and managing risk need to be identified so as to minimize the impact of this stress not only on workers' health, but also on productivity. Methods: After close analysis of the Italian and European reference regulatory framework and workrelated stress assessment and management models used in some European countries, we adopted the UK Health and Safety Executive's (HSE) Management Standards (MS) approach, adapting it to the Italian context in order to provide a suitable methodological proposal for Italy. Results: We have developed a work-related stress risk assessment strategy, meeting regulatory requirements, now available on a specific web platform that includes software, tutorials, and other tools to assist companies in their assessments. Conclusion: This methodological proposal is new on the Italian work-related stress risk assessment scene. Besides providing an evaluation approach using scientifically validated instruments, it ensures the active participation of occupational health professionals in each company. The assessment tools provided enable companies not only to comply with the law, but also to contribute to a database for monitoring and assessment and give access to a reserved area for data analysis and comparisons.

• Proceedings of the KIPE Conference
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• 2018.11a
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• pp.95-97
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• 2018

The power quality of Single Phase Grid-Connected Inverters (GCIs) has received much attention with the increasing number of Distributed Generation (DG) systems. However, the performance of single phase GCIs get degraded due to several factors such as the grid voltage harmonics, the dead time effect, and the turn ON/OFF of the switches, which causes the harmonics at the output of GCIs. Therefore, it is not easy to satisfy the harmonic standards such as IEEE 519 and P1547 without the help of harmonic compensator. To meet the harmonic standards a certain kind of harmonic controller needs to be added to the current control loop to effectively mitigate the low order harmonics. In this paper, the harmonic compensation is performed using a novel robust harmonic compensation method based on Digital Lock-in Amplifier (DLA). In the proposed technique, DLAs are used to extract the amplitude and phase information of the harmonics from the output current and compensate it by using a simple PI controller in the feedforward manner. In order to show the superior performance of the proposed harmonic compensation technique, it is compared with those of conventional harmonic compensation methods in terms of the effectiveness of harmonic elimination, complexity, and implementation. The validity of the proposed harmonic compensation techniques for the single phase GCIs is verified through the experimental results with a 5kW single phase GCI. Index Terms -Single Phase Grid Connected Inverter (SPGCI), Harmonic Compensation Method, Total Harmonic Distortion (THD) and Harmonic Standard.

• Proceedings of the Optical Society of Korea Conference
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• 2008.07a
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• pp.207-208
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• 2008

In this study, we present the error compensation effect of optical monitoring methods for apply of narrow band pass filter and IR-cutoff filter. Then we show the optimization process for apply of optical monitoring methods.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.331-334
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• 2004

A new measurement scheme is proposed to generate an optimized boost table for video rate LCD response time compensation. This method, which closely follows basic theory, enables up to a 90% reduction in the lookup table creation time compared to conventional methods. Furthermore, while conventional approaches require all measurements to be repeated in order to load the entire LUT whenever key parameters such as refresh rate or boost intensity are modified, the method proposed in this paper allows the new table to be calculated by utilizing saved waveform data without the need for any repeated measurements.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.19 no.40
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• pp.233-240
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• 1996

A fixed amount compensator is proposed for a process with a linear tool wear function. A Cost model is constructed which involve process adjustment cost and quality loss. Symmetric and asymmetric quadratic functions of the deviation of a quality measurement from the nominal target value are considered as the quality loss functions. Methods of finding optimal values of initial setting and compensation limit are presented and a numerical example is given.

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.243-246
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• 1998

A predictive controller is designed based upon stochastic methods for compensation of network time delay which caused by the spatial separation between controllers and actuators. Current commands are generated by using time varying probability functions which can be defined according to the values of previous control inputs and actual outputs. To demonstrate the effect of this control methodology, simulation experiments are performed. The results show that even an unstabilized system by a long time delay can be stabilized with this predictive controller.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.558-563
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• 2007

Walking passenger injury accidents in and around stations have increased in recent years, and passengers are now more aware of being able to claim compensation for such accidents. Therefore, it is anticipated that station managers and owners will need to take measures to improve the condition of walking areas so that performance objectives are met an the compensation paid for passenger accidents is limited. The aim of this study covers the following: accidents statics and contributory factors, station flooring and footway material, guidance for flooring, and test methods for slipperiness and surface profile.