• The Transactions of the Korean Institute of Electrical Engineers B
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• v.50 no.10
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• pp.530-535
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• 2001

Resonant-type electronic ballast for a metal halide discharge(MHD) lamp is proposed and implemented for 400W MHD lamp. HID lamps have good color rendition, long life and good focusing capability but they have flickers by acoustic resonance when driven at high frequency. A new control method is employed to remove acoustic resonance related instability in HID lamp. By using the amplitude modulation, a spread spectrum effect is employed on the ballast. The control loop of resonant inverter is analyzed and a current is designed. The ballast consists of a power factor controller, an half-bridge resonant inverter, a simple ignitor and an integrator with OP-amps. The experimental results show the good performance as PF 0.93, ballast loss 22W at output 400W and the conducted EMI level is below 60dBuV.

• The Journal of the Acoustical Society of Korea
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• v.18 no.2
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• pp.40-47
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• 1999

Focusing is widely used to increase the resolution in ultrasound transmit field. It increases signal levels returning from the mainlobe direction and decreases those due to sidelobe directions. However, when the sidelobes cannot be completely canceled, the resulting image resolution is greatly deteriorated. This paper proposes a method of improving the resolution by scaling the received signal according to the difference between the mainlobe and sidelobe levels computed in the frequency domain by the use of Fourier transform. The proposed method is verified by computer simulation and experiments, and is shown to be highly effective in narrowing the mainlobe width and decreasing the sidelobe levels.

• Journal of Information Technology Applications and Management
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• v.17 no.3
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• pp.99-119
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• 2010

The Radio Frequency IDentification (RFID), once used widely, is expected to provide improved convenience in our everyday life. Crude observations of RFID consumption show that there is a wide variation in the adoption of this technology across different individuals. One plausible explanation is that consumers with challenging mind who seek for new technologies and have a good grasp of the new RFID technology should have higher propensity to use the technology. A better understanding of such acceptance pattern of RFID is of high importance in establishing technology providers' marketing strategies. This study is aimed to explain differences in the level of RFID acceptance focusing on cognitive styles of potential RFID users. By presenting potential RFID users' discriminative propensity toward RFID technology, this study hopes to provide guidelines for the design of service strategies that facilitate consumers' acceptance of RFID.

• Speech Sciences
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• v.7 no.1
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• pp.203-216
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• 2000

The purpose of this study is to revisit the property of the Korean plain stops in intervocalic position. More specifically, focusing on a word-internal, intervocalic position, this study investigates 1) how often speakers pronounce intervocalic. stops as fully voiced, 2) in what amount each speaker voice the plain stops during the stop closure, 3) whether the preceding or the following vowel influences the voicing of target consonants, and 4) the fundamental frequency pattern at the vowel onset after the target consonant shows any consistent pattern, regardless of whether voicing is present during the closure. The results of this study give strong support for the phonetic account of the voicing distinction in Korean. (Jun 1995, 1996).

• Journal of the Korean Home Economics Association
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• v.45 no.7
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• pp.17-33
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• 2007

The purpose of this study was to examine the relationships between aggression and moral emotion including guilt, shame, and empathy in early adolescence. In a sample of 359 early adolescents (187 boys, and 172 girls) in Daejeon city, data were analyzed by frequency, t-test, Pearson's correlations, and multiple regressions. The following study results were obtained: 1. Boys showed more linguistic and roundabout aggression, and girls showed more anger, guilt and empathy. Older adolescents showed more shame than younger adolescents did, whereas younger adolescents showed more guilt and empathy than did older adolescents. 2. Shame had significant relationships with all types of aggression, whereas guilt and empathy had significant relationships with different types of aggression. 3. Moral emotions - guilt, shame, and empathy - showed significant effects on aggression among early adolescents. The degree of the effectiveness of moral emotions on aggression depends on the types of aggression, gender, and age of participants.

• Korean Journal of Biological Psychiatry
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• v.23 no.3
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• pp.102-107
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• 2016

This review will summarize EEG studies of learning and memory based on frequency bands including theta waves (4-7 Hz), gamma waves (> 30 Hz) and alpha waves (7-12 Hz). Authors searched and reviewed EEG papers especially focusing on learning and memory from PubMed. Theta waves are associated with acquisition of new information from stimuli. Gamma waves are connected with comparing and binding old information in preexisting memory and new information from stimuli. Alpha waves are linked with attention. Eventually it mediates the learning and memory process. Although EEG studies of learning and memory still have controversial issues, the future EEG studies will facilitate clinical benefits by virtue of more developed and encouraging prospects.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.618-621
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• 2001

The proposed lever actuator has no friction and mass balance characteristics in motion, which are adapt to high-speed and high-density optical disk system. This paper discussed about the theoretical analysis of the lever structure. The modeling of the lever actuator is found. Using the Newton's method, the motion of equation is deduced through the constraint equations and equilibrium equations in three directions (focusing, tracking and tilting). From the above analysis, we know that the shape of the hinge is the very important parameter on determining the performance of the lever actuator, and the actuator has the 2nd order system characteristics. And the first resonant frequency in transmissibility is dependent to the rigidity of the lever while the first transmissibility resonance of conventional actuators is dependent to the first natural resonance of those actuators. This means that the lever actuator is more stable to the external vibration.

• Asia pacific journal of information systems
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• v.14 no.2
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• pp.21-36
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• 2004

Since IT industry has changed very rapidly in technology, market environments, the cyber communities raise new social space. In spite of such growth of cyber communities, academic discussion is relatively limited. This Paper suggested several factors that affect the level of participator's loyalty on cyber communities. Participator's loyalty was classified into two categories, the psychological loyalty, which measure the psychological responses, and the behavior loyalty, which measure the absorption of time, the volume and frequency of visit to cyber communities. Consequently, this research has showed social awareness about cyber community culture and suggested the strategy directions for customer-oriented cyber Community Company.

• Journal of KSNVE
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• v.6 no.6
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• pp.763-770
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• 1996

This paper proposes a method to determine the initial shape and size of the suspension beam of an optical pickup actuator subjected to specified dynamic characteristics. For the analysis, a simplified model consisting of a concentrated mass, rotational springs and beams is developed. Based on this model, the key dimensionless design parameters are introduced, which govern low-frequency vibration characteristics i. e., the resonant frequencies in the tracking and focusing directions. A systematic procedure for sizing and shaping the actuator suspension beams is described and applied to a sample case. The effectiveness of the present technique is verified through the comparison of the present and the finite element results.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.2 s.245
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• pp.128-134
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• 2006

Topology optimization is an effective scheme to obtain the initial design concept: however, it is hard to apply in case of non-linear or multi-objective problems. In this study, a modified topology optimization method is proposed to generate a structure of a swing arm type actuator satisfying maximum compliance as well. as maximum stiffness using the multi-objective optimization. approach. The multi-objective function is defined to maximize the compliance in the direction of focusing of the actuator and the second eigen-frequency of the structure. The design of experiments are performed and the response surface functions are formulated to construct the multi-objective function. The weighting factors between conflicting functions are determined by the back-error propagation neural network and the solution of multi-objective function is acquired using the genetic algorithm.