• Journal of the Society of Naval Architects of Korea
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• v.41 no.4
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• pp.77-84
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• 2004

Active control is regarded as one of the most efficient and economic countermeasures to reduce excessive vibration of ship superstructure. However, it is difficult to find its practical application in real ships in spite that many studies on such systems have been done. In this study, for the practical use of an active control system to reduce ship superstructure vibration, we have developed an active vibration compensator consisting of a mechanical actuator having compact size and expected lifetime over 20 years, its control panel including exclusive signal processing and computing board, sensors to detect phase and vibration, and its operation software providing various user-interface functions. From the performance verification test of the system at a 5,500 TEU container carrier, we have confirmed the system could reduce ship superstructure vibration of a harmonic component of main engine rotating frequency up to 0.1 mm/s.

• KSBB Journal
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• v.16 no.4
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• pp.351-355
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• 2001

The information about organic and biomass fractions in sewage is essential for the optimal operation and model calibration of biological treatment processes. In the respect of that oxygen is directly associated with respiration and growth of biomass as well as substrate reduction, the respirometry is well known as a suitable method for the analysis of wastewater composition and active biomass. Thus, the organic and biomass fractions in sewage were measured using respirometry. The fraction of readily biodegradable substrate, slowly biodegradable substrate, inert soluble substrate and inert particular substrate are about 10-16%, 1-8%, 32-50% and 2-47%, respectively. The active heterotrophic biomass fraction is about 10-24%, but the autotrophic biomass was not detected in influent sewage.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.9
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• pp.498-502
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• 1999

Harmonics and the reactive power related problems in the supply and demand side are increasing with the proliferation of nonlinear loads such as power converters in industrial applications. Filtering options such as passive, active and hybrid filters are countermeasures against these problems. In this study, a novel hybrid active filter topology with a new approach to enhance the system performance is presented. In this study, a novel hybrid active filter topology with a new approach to enhance the system performance is presented. The proposed topology comprised a parallel inverter and a hybrid active filter. It improves the system efficiency and reduces VA ratings, hence, overall filtering cost. The system operation, control and experimental verification on three phase rectifier and/or capacitor loads are presented.

• Journal of Digital Policy
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• v.2 no.1
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• pp.1-7
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• 2023

In China, commercial banks have launched mobile banking one after another, and the homogeneous products make the competition of mobile banking extremely fierce. Mobile banking monthly active users (MAU) is an important indicator to evaluate the operation results of mobile banking. How to improve mobile banking monthly active users is a problem faced by commercial banks. The purpose of this study is to explore strategies to increase monthly active customers of mobile banking with the help of vending machines. This research is carried out through the literature method and case method. The research results show that the use of vending machines can not only effectively increase the monthly active customers of mobile banking, but also realize the differentiation strategy to occupy the mobile banking terminal market. At the same time, this study is helpful and instructive for commercial banks to develop their business.

• Journal of Fashion Business
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• v.19 no.6
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• pp.74-81
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• 2015

The purpose of this study is to analyze the operation situation & academic research trends in Seoul and Gyeonggi area, based on theoretical consideration on academic credit bank system, focusing on academic credit bank system where a lifelong education institute affiliated with a university produces graduates with associate's degree. To find out about how academic credit bank institutes are operated in cosmetology field, the analysis of literature review was used, in reference to the literatures as well as administrative data from the Ministry of Education and institutes for lifelong education with respect to academic credit bank system. Further, dissertations and articles in journals were also reviewed for analysis, in order to see academic research trends with respect to academic credit bank system in cosmetology, and finally to provide the directions for a follow-up study in the future. It was found that about 120 junior colleges have cosmetology departments, while only about 20 4-year universities have them, where lifelong education systems such as lifelong education are essential for learners to have bachelor's degree to go to a graduate school in reality. Every year more people want to learn and acquire the degree through a lifelong education institute affiliated with a university. In this regard, it is thought that there should be first positive social awareness towards a degree recipient from such educations and more administrative promotion and active engagement of government, businesses and schools, in order to vitalize academic credit bank system. Meanwhile, there are only about 10 academic literatures including the dissertations on the operation of academic credit bank system with respect to cosmetology, which is not sufficient number in academic research, compared to the increasing number of people who want to acquire the degree. Most of the preceding studies have been limited to education services and learners' satisfaction level. Therefore, continuous follow-up study is required on how to improve social awareness as well as teachers and instructors' satisfaction level, as well as how to develop industry-customized curriculum, in order to ensure active academic credit bank system.

• Journal of Advanced Navigation Technology
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• v.15 no.2
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• pp.298-306
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• 2011

In this paper, the RUNCODE encoder hardware IP was designed and implemented for symbol ID code length encoding, which is one of major modules of JBIG2 encoder for FAX. ImpulseC Codeveloper and Xilinx ISE/EDK program are used for the hardware generation and synthesis of VHDL code. The synthesized hardware was downloaded to Virtex-4 FX60 FPGA on ML410 development board. The synthesized hardware utilizes 13% of total slice of FPGA. Using Active-HDL tool, the hardware was verified showing normal operation. Compared with the software operating using Microblaze cpu on ML410 board, the synthesized hardware was better in operation time. The improvement ratio of operation time between the synthesized hardware and software showed about 40 times faster than software only operation. The synthesized H/W and S/W module cooperated to succeed in compressing the CCITT standard document.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.5
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• pp.348-356
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• 2003

Active vibration control algorithms for the compensator and proto-type testing system have been developed for the suppression of vibrations from the reciprocating engines. At first, the developed algorithm determines optimal control vibration phases by detecting vibration responses of the engine without and with compensator, and then performs the continuous optimal control functions by tracking the change of the vibration frequency and phase. This algorithm is comparatively simple. robust for the external excitations and needless of supplementary operation since the control process is serially carried out. To validate the performance of compensator and algorithm, testing system including excitation device are constructed and tested, and the reductions of vibration levels are observed over than 80 % of the uncontrolled levels at various frequency ranges.

• Journal of Power Electronics
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• v.15 no.3
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• pp.796-805
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• 2015

New direct and indirect current control methods for a fault-tolerant active power filter topology are presented in this paper. Since a three-phase four-switch topology has a phase bridge current which cannot be directly controlled, a hysteresis control method in the α-β plane which controls the three-phase current in the two-phase stationary coordinate system is proposed. The improved SVPWM algorithm is able to eliminate the operation of the trigonometric functions in the traditional algorithm by rotating the α-β coordinates and alternating the sequence of the output vectors, which in turn simplifies the algorithm and reduces the switching frequency. The selection of the DC-side reference voltage and DC-side capacitor equalization strategy are also discussed. Simulation and experiments demonstrate that the proposed control method is correct and feasible.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1131-1135
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• 2004

In the virtual environment, force feedback to the human operator makes virtual experiences more realistic. However, the force feedback using active actuators such as motors can make the system active and sometimes unstable. To ensure the safe operation and enhance the haptic feeling, stability should be guaranteed. Both motors and brakes are commonly used for haptic device. A brake can generate a torque only against its rotation, but it is intrinsically stable. Consequently, motors and brakes are complementing each other. In this research, a two degree-of-freedom (DOF) haptic device equipped with both motors and brakes has been developed to provide better haptic effects. Each DOF is actuated by a pair of motor and brake. Modeling of the environment and the control method are needed to utilize both actuators. For various haptic effects, contact with the virtual wall and representation of friction effect are extensively investigated in this paper. It is shown that the hybrid haptic system is more suited to some applications than the motor-based active haptic system.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1309_1310
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• 2009

The topology of active clamp forward converter provides ZVS characteristic and also the stress of voltage and current is smaller than that of the conventional forward converters. The benefits of this technique include a higher efficiency at a high switching frequency, lower EMI/RFI. In this paper, the active clamp forward converter is designed for operation in wide range voltage and has 19.5V/120W ratings with efficiency more than 90%.