• The Transactions of the Korean Institute of Power Electronics
• /
• v.7 no.6
• /
• pp.524-530
• /
• 2002

A control of the body posture and movement is maintained by the vestibular system, vision, and proprioceptors. Afferent signals from those receptors are transmitted to the vestibular nuclear complex, and the efferent signals from the vestibular nuclear complex control the eye movement and skeletal muscle contract. The postural disturbance caused by loss of the vestibular function results in nausea, vomiting, vertigo and loss of craving for life. The purpose of this study is to develop a off-vertical rotatory system for evaluating the function of semicircular canals and otolith organs, selectively, and visual stimulation system for- stimulation with horizontal, vortical and 3D patterns. The Off-vortical axis rotator is composed of a comportable chair, a DC servo-motor with reducer and a tilting table controlled by PMSM. And a double feedback loop system containing a velocity feedback loop and a position feedback loop is applied to the servo controlled rotatory chair system. Horizontal, vertical, and 3D patterns of the visual stimulation for applying head mounted display are developed. And wireless portable systems for optokinetic stimulation and recording system of the eye movement is also constructed. The gain, phase, and symmetry is obtained from analysis of the eye movement induced by vestibular and visual stimulation. Detailed data were described.

• Journal of Engineering Education Research
• /
• v.12 no.4
• /
• pp.38-45
• /
• 2009

The purpose of this study is to explore improvable proposal of instruction through analyzing learners' needs and satisfaction for college of engineering. Based on the online survey date with undergraduate students in Seoul National University, recognition difference between students in college of engineering and all students in SNU was identified. Among several factors influenced on learners' satisfaction in class, it is shown that satisfaction to facilities is higher than any other factor related to instruction. Generally, satisfaction with teaching in class is lower while satisfaction to an extrinsic support to students is high. Therefore, instructors should be more concerned about teaching in class. Learners' satisfaction with instructors' feedback to assignments and tests is significantly higher in college of engineering. However, learners' satisfaction with the progress of classwork and assignment students should perform regularly is lower than one in other colleges.

• The Journal of the Korea Contents Association
• /
• v.7 no.4
• /
• pp.66-73
• /
• 2007

Internet is a part of our common life and tremendous information is cumulated. In these trends, the personalization becomes a very important technology which could find exact information to present users. Previous personalized services use content based filtering which is able to recommend by analyzing the content and collaborative filtering which is able to recommend contents according to preference of users group. But, collaborative filtering needs the evaluation of some amount of data. Also, It cannot reflect all data of users because it recommends items based on data of some users who have similar inclination. Therefore, we need a new recommendation method which can recommend prefer items without preference data of users. In this paper, we proposed the apparel coordination system using personalized preference on the semantic web. This paper provides the results which this system can reduce the searching time and advance the customer satisfaction measurement according to user's feedback to system.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.46 no.2
• /
• pp.15-23
• /
• 2009

This paper presents a novel high-speed, low-complexity flexible 128/64-point $radix-2^4$ FFT/IFFT processor for the applications in high-throughput MIMO-OFDM systems. The high radix multi-path delay feed-back (MDF) FFT architecture provides a higher throughput rate and low hardware complexity by using a four-parallel data-path scheme. The proposed processor not only supports the operation of FFT/IFFT in 128-point and 64-point but can also provide a high data processing rate by using a four-parallel data-path scheme. Furthermore, the proposed design has a less hardware complexity compared with traditional 128/64-point FFT/IFFT processors. Our proposed processor has a high throughput rate of up to 560Msample/s at 140MHz while requiring much smaller hardware expenditure satisfying IEEE 802.11n standard requirements.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2008.04a
• /
• pp.442-448
• /
• 2008

This paper presents an approach to define an optimal piezoactuator length to actively control structural vibration. The optimal ratio of the piezoactuator length against beam length when a pair of piezoceramic actuator and accelerometer is used to suppress unwanted vibration with direct velocity feedback (DVFB) control strategy is not clearly defined so far. It is well known that direct velocity feedback (DVFB) control can be very useful when a pair of sensor and actuator is collocated on structures with a high gain and excellent stability. It is considered that three different collocated pairs of piezoelectric actuators (20, 50 and 100 mm) and accelerometers installed on three identical clamped-clamped beams (300 * 20 * 1 mm). The response of each sensor-actuator pair requires strictly positive real (SPR) property to apply a high feedback gain. However the length of the piezoactuator affects SPR property of the sensor-actuator response. Intensive simulation and experiment shows the effect of the actuator length variation is strongly related with the frequency range of SPR property. A shorter actuator gave a wider SPR frequency range as a longer one had a narrower range. The shorter actuator showed limited control performance in spite of a higher gain was applied because the actuation force was relatively small. Thus an optimal length ratio (actuator length/beam length) was suggested to obtain relevant performance with good stability with DVFB strategy. The result of this investigation could give important information in the design of active control system to suppress unwanted vibration of smart structures with piezoelectric actuators and accelerometers.

• Journal of the Korea Computer Graphics Society
• /
• v.23 no.5
• /
• pp.57-66
• /
• 2017

In this paper, we suggest a novel physics-based real-time animation technique for vehicles, and introduce an easy and intuitive animation authoring tool which uses our proposed technique. After a user specifies a trajectory of a virtual car as input, our system produces a more accurate simulation faster than a previous research result. This is achieved by a trajectory splitting method based on directional features and a trajectory library. As a result, the user can create not only a car animation including lane changing and passing, but also a crash animation which is a rarely researched topic. Also, we propose a virtual car structure that approximates a real car's structure for real-time simulation, the resulting animation shows high plausibility such as a small vibration which occurs when the virtual car breaks and a deformation of when a car accident happens.

• Journal of IKEEE
• /
• v.18 no.4
• /
• pp.509-516
• /
• 2014

CRC feature in a high-speed semiconductor memory devices such as DDR4/GDDR5 increases the data reliability. Conventional CRC method have a massive area overhead and long delay time. It leads to insufficient internal timing margins for CRC calculation. This paper, presents a CRC code method that provides error detection and a real-time matrix type CRC. If there are errors in the data, proposed method can alert to the system in a real-time manner. Compare to the conventional method(XOR 6 stage ATM-8 HEC code), the proposing method can improve the error detection circuits up to 60% and XOR stage delay by 33%. Also the real-time error detection scheme can improve the error detection speed to agerage 50% for the entire data bits(UI0~UI9).

• Transactions of the KSME C: Technology and Education
• /
• v.1 no.2
• /
• pp.205-210
• /
• 2013

In this research, we have developed a ski-simulation system based on a physics-based simulation model using Newton's second law of motion. Key parameters of the model, which estimates skier's trajectory, speed and acceleration change due to skier's control on ski plate and posture changes, were derived from a field test study performed on real ski slope. Skier's posture and motion were measured by motion capture system composed of 13 high speed IR camera, and skier's control and pressure distribution on ski plate were measured by acceleration and pressure sensors attached on ski plate and ski boots. Developed ski-simulation model analyzes user's full body and center of mass using a depth camera(Microsoft Kinect) device in real time and provides feedback about force, velocity and acceleration for user. As a result, through the development of interactive ski-simulation motion recognition system, we accumulated experience and skills based on physics models for development of sports simulator.

• Journal of Korea Multimedia Society
• /
• v.16 no.5
• /
• pp.629-636
• /
• 2013

Nowadays, many interface devices or training systems have been developed with recent developments in IT technology but only a few training systems for developmentally disabled people have been introduced. In this paper, we present a real-time, interactional and situational training system based on augmented reality in order to improve cognitive capability and adaptive ability in the daily life of developmentally disabled people. Our system is specifically based on serving food in restaurants. This augmented reality based system provides them to experience various different situations safely and take the training session as much as they want under any circumstances. When they use our system, they are able to look around with Head Mounted Display(HMD) and take training sessions easily based on various situational scenarios. After experimenting on our system for 3 months, we found they had no aversion about wearing HMD and learned quicker as they practiced over and over and improved their cognitive capability and adaptive ability. We also got a positive feedback that it had an excellent educational value from teachers in special-education-school.

• Journal of The Korean Association of Information Education
• /
• v.17 no.1
• /
• pp.9-21
• /
• 2013

The purpose of this paper is to develop and implement a mobile application system to improve arithmetical operations for low achievers. The proposed system has the following characteristics. First, the system provides individual study for low achievers based on their different study levels. Second, instant feedback can be provided to students for maintaining study motivation. Third, the system enables students to study arithmetical operations in persistent and repetitive manner. This is due to that, in the literature, arithmetical operation capacity can be increased by persistent and repetitive practices. The proposed system is applied to mathematics low achievers and the following results are obtained. First, interests and intrinsic motivation are increased through use of the proposed system. Second, arithmetical operation speed is increased. Also, accuracy of arithmetical operation is improved. Thus, it is concluded that arithmetical operation capacity of low achievers is improved using the proposed system.