• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1075-1080
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• 2007

In order to reduce energy consumption, secondary controlled system has been applied to many types of equipments. In lifting equipments or press machines using hydraulic cylinder, a hydraulic transformer is used as a control component instead of a valve for motion control and a component for recovering potential energy of load. The transformer is a combination of a variable displacement pump/motor as a secondary controlled element and a fixed displacement pump/motor. In this paper the effect of transformer is studied. Multiple closed loop controllers with displacement feedback of variable pump/motor, speed feedback and position feedback of cylinder are used. The efficiency and energy consumption when cylinder is driven up and down is calculated by simulation. Simulation results show that considerable energy saving is achieved by choosing load ratio, circuit type and supply pressure.

• Journal of the Korean Society of Clothing and Textiles
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• v.39 no.6
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• pp.838-851
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• 2015

This study explores the level of designer brands' market oriented attitude through a conceptual framework of market orientation. Designer brands have rapidly increased in the Korean fashion market with a competitive environment that pushes designers to improve market oriented attitudes and strategy. Designers working for 20 brands that the government designated as 'promising creative designer brands' were invited for in-depth interviews, 19 designers from 18 brands participated in this study. The generation of market intelligence that composes market orientation meant that the designers were confirmed to collecting different types of information according to information sources. They showed interest in collecting information on the exploration of design trends from overseas designers as well as operational and managerial information from domestic designers. Fashion-related stakeholders mainly collected feedback on design concepts from the press and public institutions. They collected customer feedback from buyers; however, appropriate feedback was inadequate. Designers generally appeared to place less value on the collection of customer responses and opinions; however, two groups of designers showed customer-oriented attitudes according to accumulated experience. The market-oriented attitude of top designers had an important role in designer brands; consequently, top designers should be properly trained to improve market-oriented attitudes to increase market performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.8
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• pp.867-880
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• 1992

In this paper, a circuit design techniques for Improving the voltage gain of the GaAs MESFET single amplifier is presented. Also, various types of existing current mirror and proposed current mirror of new configuration are compared. To obtain the high differential mode gain and low common mode gain, bootstrap gain enhancement technique Is used and common mode feedback Is employed In the design of differential amplifier. The simulation results show that designed differential amplifier has differential gain of 57.66dB, unity gain frequency of 23.25GHz. Also, differential amplifier using common mode feedback with alternative negative current mirror has CMRR of 83.S8dB, stew rate of 3500 V /\ulcorners.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.8 no.3
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• pp.88-95
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• 1994

A scheme of IESFVSC(Integral Error State Feedback Variable Structure Controller) is proposed for a DC servo position control system with the disturbances which do not satisfy the matching condition. The proposed control system is composed of servo compensator and state feedback VSC. The servo compensator enhances the robustness of the control system against various types of disturbance, and makes effective tracking possible without using error dynamics. The IESFVSC is applied to the practical design of a robust DC servo control system and the control performances are verified through theoretical analyses and simulations.

• Journal of Fisheries and Marine Sciences Education
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• v.23 no.1
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• pp.130-139
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• 2011

The purpose of this study is to examine the effects of soccer club teachers' leadership behavior types on elementary and middle school students' psychological factors. The subjects in this study were 561 students who consisted of 245 elementary and 316 middle school students - from 15 elementary and 17 middle school teams. All the teams are registered in the Busan Sports Club. The findings of the study were as follows : Autocratic behavior must be used rarely because it causes great anxiety. Positive feedback behavior is needed to improve students' confidence. Positive feedback behavior and training and instruction behavior are needed for achievement motivation. For this reason, teachers must coach students through positive feedback behavior, training and instruction behavior and social support behavior to build confidence, achievement motivation and cohesion. Since confidence, achievement motivation and cohesion depend on careers, coaching student's early helps students perform better.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.9
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• pp.995-1004
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• 2010

In the channel-varying environment, it is very important to estimate the signal to noise ratio(SNR) of received signal and to transmit the signal effectively for the modern communication system. The performance of existing non-data-aided (NDA) SNR estimation methods are substantially degraded for high level modulation scheme such as M-ary APSK or QAM. In this paper, we propose a SNR estimation method which uses zero point auto-correlation of received signal per block and auto-/cross- correlation of decision feedback signal in OFDM system. Proposed method can be studied into two Types; Type 1 can estimate SNR by zero point auto-correlation of decision feedback signal based on the second moment property. Type 2 uses both zero point auto-correlation and cross-correlation based on the fourth moment property. In block-by-block reception of OFDM system, these two SNR estimation methods can be possible for the practical implementation due to correlation based the estimation method and they show more stable estimation performance than the previous SNR estimation methods. Also, we mathematically derive the SNR estimation expression according to computational difference of auto-/cross-correlation. Finally, Monte Carlo simulations are used to verify the proposed method.

• Journal of Gifted/Talented Education
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• v.20 no.3
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• pp.721-741
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• 2010

This study was to analyze verbal interactions between teachers and students after observations on teachers' questioning and feedback, students' response types and frequency analysis at middle-school class of average and gifted students. As for the verbal interaction between teachers and students of science class of general students, it was dominant for teachers to utilize questions for summarizing or guiding for textbook contents as they are. They were focused on immediate feedback in a restatement form. The students used simple responses like yes/no in general. The most high frequency of verbal interaction models expressed were in the order of cognitive-memory thinking question-short answer-immediate feedback. On the other hand, teachers of gifted students' science class threw divergent and evaluative thinking questions of open question, such as 'what's the reason?' or 'why is it?' Immediate feedback in explanatory form was mainly provided as well. The level of feedback delay was higher than general class and that of immediate feedback was lower than general class. The students preferred short words or a not-complicated sentence when they replied and their participation was more attentive and positive. Hence, The high frequency of verbal interaction models expressed were in order of cognitive-memory thinking questions－elaborative short answer－delayed feedback.

• Korean Journal of Child Studies
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• v.35 no.4
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• pp.123-143
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• 2014

This research was based on achievement goal theory which categorizes young children's motivation into three types: mastery, the performance-approach, and performance-avoidance motivation. The participants consisted of forty-eight pairs of children aged 3-4 and their mothers. The participants completed two tasks in order to indentify their motivational types. The short form of the Child Behaviour Questionnaire(CBQ-SF), modified scales from Kim and Kim(2001), and the GIPEPS were also employed. The major findings of the research are as follows: First, in terms of the motivational types of the given sample, performance-approach motivation was ranked first followed by mastery motivation. Second, it was found that the temperament of young children was not related with their motivational types. Third, there were some differences in mother-child interaction between groups based on the frequency of feedback, questions, and the percentage of commands. Fourth, the mood of the relationship appeared to be the only factor of maternal interaction quality which related to children's mastery motivation.

• ETRI Journal
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• v.30 no.5
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• pp.707-717
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• 2008

This paper presents two types of high-speed hardware architectures for the block cipher ARIA. First, the loop architectures for feedback modes are presented. Area-throughput trade-offs are evaluated depending on the S-box implementation by using look-up tables or combinational logic which involves composite field arithmetic. The sub-pipelined architectures for non-feedback modes are also described. With loop unrolling, inner and outer round pipelining techniques, and S-box implementation using composite field arithmetic over $GF(2^4)^2$, throughputs of 16 Gbps to 43 Gbps are achievable in a 0.25 ${\mu}m$ CMOS technology. This is the first sub-pipelined architecture of ARIA for high throughput to date.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.14 no.3
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• pp.32-37
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• 2005

Several types of smart materials and control scheme are available to adjust the structure actively in various external disturbances. A control scheme was introduced for a specific material. But the effectiveness of the control scheme has some limitation according to the choice of the smart materials and the response of the structure. The ER(Electrorheological) fluid is adequate for a large control force, and the PZT(lead zirconate titanate) patches are suitable for small but arbitrary control force at any point of the structure. It can be used for active control of structure by changing the dynamic characteristics of the structure. But it has some difficulty in suppressing the excited vibration in broad band. To compensate this resonance of the controlled structure, a hybrid controller was constructed using PPF(Positive position feedback) control with PZT and ER fluid control.