• Journal of Power Electronics
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• v.17 no.2
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• pp.358-367
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• 2017

This paper presents a novel filtering method for speed measurements to improve the low-speed performance of the direct-drive permanent magnet traction machines for elevators. Based on the theory of nonlinear tracking differentiator (NTD), this method, which can act as a high performance filter of a raw speed signal, obtains a more accurate speed feedback signal when applying a low-resolution encoder. In addition, it can relieve the interference caused by the position derivative for speed sampling. By analyzing the frequency response of the NTD, the influence of its parameters on the performance of the speed filtering is investigated. Compared with different types of low-pass filters, the proposed method shows a shorter time delay and a stronger ability in terms of noise suppression when the parameters are selected carefully. In addition, when using the measured speed signal through a nonlinear tracking differentiator as the feedback of the system, the motor runs more steadily at low speeds. As a result, the riding comfort of a direct-drive elevator can be improved. The feasibility of the proposed strategy was verified on an 11.7kW elevator traction machine using a commercial inverter.

• The Journal of the Korea Contents Association
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• v.9 no.12
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• pp.940-947
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• 2009

The study aims at investigating frequency of the stuttering of stutterers according to FAF pitch alternation level, examining a stuttering group. The study has collected spoken language samples by making each 10 people of a stuttering group carry out a reading and monologue task using NAF and FAF. The results of this study were as follows. In stuttering frequency, both reading and monologue task, there was significant difference of stuttering frequency according NAF and FAF pitch alternation level. But, There was significant difference of stuttering frequency according FAF pitch alternation level. NAF levels than FAF on type of stuttering decreased at the level of all the core behavior. The decrease was a lot of block, core behavior has changed as often repeated.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.11
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• pp.3507-3515
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• 1996

This paper presents an attempt to find the physical structure of dynamic systems which achieves the behavior of a given system function. The scheme pursued by the paper would be regarded as synthesizing dynamic systems, and a method to synthesize them analytically is proposed by means of bond graph prototypes. The method adopts several conceptsused to synthesize networks in the electrical field, but yet deconstrates its own strengths such as the freedom from assigning causality and determining junction types. Also, itis shown that this method has further advantages in reticulating a given specification into feedforward and feedback components relative to network synthesis and the method is examined though an example to trace the outline of the analytical synthesis of dynamic systems using bond graph prototypes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.1
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• pp.68-79
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• 1992

In the high speed analog system satellite communication system, video signal processing and optical fiber interface circuits, GaAs high gain operational amplifier is advantageous due to obtain a high gain because of its low transconductance and other drawbacks, such as low frequency dispersion and process variation. Therefore in this paper, a circuit techniques for improving the voltage gain for GaAs MESFET amplifier is presented. Also, various types of existing current mirror and current mirror proposed are compared.To obtain the high differential gain, bootstrap gain enhancement technique is used and common mode feedback is employed in differential amplifier.The simulation results show that gain is higher than that of basic amplifier about 18.6dB, and stability and frequency performance of differential amplifier are much improved.

• Science of Emotion and Sensibility
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• v.20 no.1
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• pp.41-48
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• 2017

This study was conducted to develop wearable products with visual and auditory feedback aimed at promoting exercise interest in children. Here we determined the theoretical characteristics of cognitive and motor function development during childhood, empirical characteristics of children's motor functions, and factors that encourage exercise using natural observation and in-depth interview research methods. The questionnaire assessed children's motor ability, intensively trained body parts in sports programs, types of training or classes that improve the motor ability of each muscle group, significantly considered aspects of children's sports programs, and factors that promote children's interest in exercise. Our results suggest that the development of sport programs comprising varied exercise options that enhance body and limb movements are needed for balanced growth. Furthermore, it is very important to provide motivation for regular exercise and appropriate feedback, such as praise and encouragement, to maintain interest in exercise. This study identifies the standards for developing products that peak children's interest in exercise and the basis for a physically and mentally healthy society.

• Journal of Korea Society of Digital Industry and Information Management
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• v.7 no.3
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• pp.123-136
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• 2011

Arts gains a new relation as the new academic area that deals with living organisms and through this technology, it affects everything, such as the body, entity, consciousness and unconsciousness to bring an overall change. Based on this premise, arts require a different interpretation from the previous product-focused interpretation or the analysis focusing on the aesthetics. As the result of arts using the scientific methods, I examined the changes of the arts semantics and how it evolved with what kind of contents and characteristics. The net art with the internet base also form a close relationship with the social and cultural codes. In categorizing the social issues and the topical discussions with semantic factors that evolve from the digital biological perspective, it can be divided into four types of complex interaction, positive feedback negative feedback, and amplification of unsettledness. Based on the characteristics of the multimedia and the interactive reaction, the technique and the imagery amplify the message through a spatial and timely meeting in a mutual repletion. In other words, the emotional communication is used to attempt the messages from the products and the expression in various methods.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.28 no.2
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• pp.69-74
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• 2016

Most hot water heating valves for apartments are constant-flow types, which limit the flow rate through an individual household for even distribution of heating water to other households. The constant-flow type is implemented by an on-off control. As a result, heating water is supplied intermittently and hence, indoor air temperature also fluctuates. Returning water temperature is also high, which reduces energy efficiency. To implement continuous feedback control, the indoor temperature dynamics was simulated to fit a measured temperature history by a state-of-the-art physical model. From the model, it was found that the most important disturbance is outdoor temperature and its effect on indoor temperature lasts about an hour. To cope with the slow response and the significant disturbance, a prediction control with proportional feedback is proposed. The control was found to be successful in implementing continuous heating water flow and improved indoor temperature control.

• English Language & Literature Teaching
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• v.13 no.2
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• pp.63-90
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• 2007

The present study investigated what combination of three form-focused options - explicit explanation, production practice, and corrective feedback - may be effective in helping low-proficiency learners improve accuracy in communicative writing. The subjects were 34 Korean university students enrolled in 'Business English 1' and the study lasted 11 weeks. The relative clause structure was selected as the target structure. The study found that the combination of explicit explanation, sentence-level production practice, communicative writing practice, and recasts had a significantly greater effect on improved accuracy than the combination of communicative writing practice and recasts and that of explicit explanation, communicative writing practice, and recasts. Because the second and third combinations didn't lead to significantly improved accuracy, it can be concluded that of the form-focused options forming the first combination sentence-level production practice made a decisive contribution to the significant increase in accuracy. It also found that the provision of self-correcting opportunities before providing recasts on errors committed in sentence-level production practice resulted in significantly greater accuracy in communicative writing than the provision of recasts alone on them. The results of the study suggest that we should make low-proficiency Korean learners have sentence-level production practice which is intensive and focused and make them self-correct targeted errors before providing them with narrowly focused recasts in order to help them to improve writing accuracy.

• Journal of the Ergonomics Society of Korea
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• v.32 no.4
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• pp.363-370
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• 2013

Objective: This study investigates the influences of vibrations on hedonic satisfaction based on four kinds of perceptions (perceived ease of use, perceived usefulness, perceived enjoyment, cognitive concentration) when mobile gaming. Background: As mobile gaming is becoming more and more popular for smartphone users, they might want to have more hedonic satisfaction instead of focusing on traditional usability criteria such as efficiency, effectiveness, and satisfaction. Method: We conducted a human-factors experiment with 35 male subjects to evaluate hedonic satisfaction in the mobile game configured by 7 vibration types having different levels of intensity and length. Results: The results revealed that the use of vibration significantly increases the perceived ease of use, perceived usefulness, and cognitive concentration. In addition, the intensity of vibration makes differences of perceived usefulness and cognitive concentration. Conclusion: Vibration can be effectively used to improve hedonic satisfaction of smartphone users in mobile gaming when they are not allowed to turn the sound effects on. Application: This study helps game designers effectively provide vibration feedback of mobile games for smartphone users.

• Fashion & Textile Research Journal
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• v.21 no.4
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• pp.401-411
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• 2019

Non-contact judgment and evaluation for products are increasingly needed along with a rapid environmental change in fashion that sows urgency in the need to implement services that allows users to judge and experience a tactile sense in a fashion product without actual contact. Technological development is required to provide users with syn-aesthetic experiences that integrate the visual, tactile and the auditory. There is also a need to conduct research to increase immersion that provides users with ICT-related experiences communicated through fashion images. The study analyzed demands for haptic communication technology by Korean users in immersive VR fashion product shopping. Accordingly, it defined haptic communication through literature research, investigated immersion in the VR environment and conducted in-depth interviews for haptic communication applicable to VR shopping. Findings show that hedonic reactions by fantasy, emotion and fun function are an important motive in selecting VR shopping. VR fashion product shopping steps were divided into 4: move to store, search in store, search of product and purchase based on offline store shopping experience. It defined the haptic communication by steps and analyzed the types of the haptic feedback to be implemented. The study results provide basic data for developing haptic communication technology that can enhance e a sense of the presence and immersion experiences that can help lay a groundwork for pilot studies on the convergence of the virtual and the real.