• The Journal of the Korea Contents Association
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• v.14 no.5
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• pp.498-511
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• 2014

This study was designed to investigate the perception of the competencies of using Importance-Performance Analysis (IPA). The subjects of the study were 318 clients and 118 consultants. Descriptive statistics, paired t-tests, and Importance-Performance Analysis (IPA) were conducted based on perception levels of clients and consultants to increase understanding of current situations and trends. Findings are expected to assist in planning. Regarding the perception of clients, Quadrant 2 (Concentrate Here) included consulting supervision expertise and content expertise, and Quadrant 4 (Possible Overkill) included skill expertise. Regarding the perception of consultants, Quadrant 1 (Keep Up the Good Work) included skill expertise; Quadrant 2 (Concentrate Here) included content expertise; and Quadrant 3 (Low Priority) included consulting supervision expertise. Results revealed that clients had no responses for Quadrant 1, but they offered 10 items associated with Quadrant 2, one item for Quadrant 3, and four items for Quadrant 4. Consultants responded with five items for Quadrant 1, three items for Quadrant 2, three items for Quadrant 3, and four items for Quadrant 4.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.06a
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• pp.310-313
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• 2005

In this paper, four quadrant CBPS(Compact Bipolar Power Supply) which development and study using universal PWM controller. The CBPS has 24V DC-link voltage, +/-5A output current, 50kHz switching frequency and 30Hz full load bandwidth using FET device. Proposed system has two independent PWM controllers for each full-bridge switch leg drive and PI control loops for current regulations. It is shown experimental results that good step response of the current output.

• Journal of Multimedia Information System
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• v.5 no.3
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• pp.155-162
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• 2018

Nowadays, the tracking technology of Quadrant Detector will become actual by new micro devices. Based on the past filed data of the reception experiment with COMETS satellite, we have studied on new device (AD8302, phase difference detector) was acquired and suspect its abilities. In 1998, we have developed a Quadrant Detector for mobile to track a weak signal from satellite on Ka band of COMETS. The Quadrant Detector is comprised of four dedicated feed components for reception under an environment of Nakagami - Rician fading, and one transmission and reception feed component. We were successful in receiving a 23 GHz beacon signal from ICE transponder of the COMETS and succeeded in tracking the satellite from a moving vehicle at speeds of approximately 10 ~ 20 Km/h on paved roads. In 2018, with new device AD8302, we have verified new QD system and performed a simulation, based on the past filed experiment. This new device shall be improving the tracking abilities from mobile body on the earth to the multimedia satellite.

• Proceedings of the KIEE Conference
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• 1998.11b
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• pp.627-629
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• 1998

We propose a robust blind equalization algorithm based on quadrant-partitioned constellations for QAM demodulation. The algorithm divides the received M-QAM constellations into simple four quadrant. The channel equalization for symbols in each quadrant can be accomplished fast and reliably using the Constant Modulus Algorithm(CMA) and the Stop-and-Go Algorithm(SGA). Test results confirm that the proposed algorithm with lower complexity outperforms both the CMA and the SGA in reducing the SER as well as the MSE at the equalizer output.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.11
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• pp.22-27
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• 2009

This paper presents a two-paralleled four quadrant DC chopper type PWM power conversion circuit in order to generate a gradient magnetic field in the Magnetic Resonance Imaging (MRI) system. This circuit has 8-IGBTs at their inputs/outputs to realize further high-power density, high speed current tracking control, and to get a low switching ripple amplitude in a controlled current in the Gradient Coils (GCs). Moreover, the power conversion circuit has to realize quick rise/fall response characteristics in proportion to various target currents in GCs. It is proposed in this paper that a unique control scheme can achieve the above objective DSP-based control system realize a high control facility and accuracy. It is proved that the new control system will greatly enlarge the diagnostic target and improve the image quality of MRI.

• Smart Structures and Systems
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• v.29 no.5
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• pp.661-675
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• 2022

In this paper, an electric vehicle drives with efficient control and low cost hardware using four quadrant DC converter with Permanent Magnet Direct Current (PMDC) motor fed by DC boost converter is presented. The main idea of this work is to improve the energy efficiency of the conversion chain of an electric vehicle by inserting a boost converter between the battery and the four quadrant-DC motor chopper assembly. Consequently, this method makes it possible to maintain the amplification gain of the 4 quadrant chopper constant regardless of the battery voltage drop and even in the presence of a fault in the battery. One of the most important control problems is control under heavy uncertainty conditions. The higher order sliding mode control technique is introduced for the adjustment of DC bus voltage and mechanical motor speed. To implement the proposed approach in the automotive field, experimental tests were carried out. The performances obtained show the usefulness of this system for a better energy management of an electric vehicle and an ideal control under different operating conditions and constraints, mostly at nominal operation, in the presence of a load torque, when reversing the direction of rotation of the motor speed and even in case of battery chamber failure. The whole system has been tested experimentally and its performance has been analyzed.

• Journal of Information Technology Services
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• v.22 no.5
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• pp.1-16
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• 2023

This study aimed to provide fundamental insights into the digital customer experience by identifying its components and analyzing their importance and satisfaction levels among youths. To achieve this objective, the components of digital customer experience were identified through a review of prior research and consultation with experts. Subsequently, a survey was conducted with 200 youths in Seoul and Gyeonggi-do. The main findings of the study are as follows: First, The components of the digital customer experience consisted of 12 items grouped into three categories. Second, an analysis of the disparity between the importance and satisfaction levels of digital customer experience revealed statistically significant differences across all items. Third, By utilizing IPA (Importance-Performance Analysis), the digital customer experience was categorized into four quadrant, each with its own characteristics and recommendations for management: The first quadrant, the "current level maintenance area," encompassed items related to "entertainment" and "recommended service." This area is currently functioning well but necessitates continuous attention and management. The second quadrant, the "area to be supported first," included items such as "personalization," "security," "inducing participation," "privacy," and "individuality expression." Intensive management and improvements are imperative in this quadrant. The third quadrant, the "long-term improvement area," consisted of items like 'consistency,' 'information quality,' and 'convenience.' These items require focus on long-term enhancement efforts. The fourth quadrant, the "areas where efforts have already been invested," encompassed items like 'accessibility' and 'deliberation.' It appears that excessive investment has been made in these areas relative to their importance, calling for selective investments while considering the specific issues associated with each factor. These research findings serve as essential data for managing the digital customer experiences of youths.

• Korean Journal of Agricultural Science
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• v.43 no.1
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• pp.144-151
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• 2016

With an aging population in rural areas, farm owners in South Korea are also aging. In particular, this phenomenon leads to the lack of human resources in rural areas and agriculture, worsening the deterioration of the rural economy. This study aimed, firstly, to analyze the criticality of the lack of human resources and high production cost issues for farmers, before using the farm as cooperative nursery of rice seedlings. Secondly, the study analyzed farmer satisfaction after using the farm cooperative. Analysis results are as follows. The motives of the research subjects for using the co-nursery were the aging of the farming population, the expected reduction of production costs, and farmers' failure in raising seedlings. Importance-performance analysis measured the importance for the farms for cooperative raising of rice seedling at 3.49 and the performance for the farms at 3.41, with a difference of 0.07 between them. The four importance-performance matrix areas, used were as follows: concentrated efforts required (Quadrant I: concentrate here), continuous maintenance (Quadrant II: keep up the good work), gradual improvement (Quadrant III: low priority), and avoiding excessive efforts (Quadrant IV: possible overkill). Based on the results, it was concluded that improvements and efforts would be necessary for each of these areas. And, there is a need to improve services through the initiation of farmer use of this rice co-nursery.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.21 no.4
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• pp.112-118
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• 2013

Air travel demand has recently been growing and establishment and operation of low-cost carriers have been increased. Against this backdrop, low-cost carriers need to figure out diversified customer demand for low-cost carriers and ways to maximize marketing efficiency before applying it to the field so that they can attain superiority to large carriers in increased intensified competition. Low-cost carriers need to be differentiated from other carriers for the purpose of improving profits. Toward this end, this study conducted analysis on importance and satisfaction with carrier choice using IPA with regard to low-cost carrier customers. In conclusion, the paper accurately examined advantages and disadvantages of low-cost carriers compared to general carriers based on results of IPA analysis and suggested managerial strategies to enhance competitiveness based on division into four parts including maintenance and enforcement (1st quadrant, Delay compensation, Booking rapidity, Check rapidity, Crew service, refund service, baggage service, punctuality, transit services, airlines images), concentrated improvement (2nd quadrant, price, Convenience of seat), passive administration (3rd quadrant, Boarding service, cabin cleanliness, flight schedule, whether local crew on board, meal service, in-flight entertainment service), and enhanced satisfaction (4th quadrant, duty-free service, Variety of routes), so that practical suggestions could be presented to employees working in the field.

• Journal of the Korean Society of Industry Convergence
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• v.6 no.1
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• pp.3-10
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• 2003

Application of matrix converter to vector control of induction motor using simplified Venturini algorithm which is capable of achieving the maximum output voltage is developed. This algorithm simplifies the control algorithm and therefor reduces the digital implementation time. Matrix converter is used as voltage-referenced voltage fed vector controlled induction motor drive. This paper describes the performance of vector controlled induction motor with four quadrant capability employing a matrix converter power circuit. The advantage of this system over the conventional rectifier-inverter arrangement are capability for regeneration into the utility, sinusoidal supply currents and minimum passive components. The steady-state and transient performance of the induction motor drive under the vector control technique is demonstrate with simulation and experiment results.