• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.64 no.12
• /
• pp.1810-1817
• /
• 2015

The railway vehicle has an auxiliary power unit for supplying power to the associated electronic control devices and passenger service unit. Typically, input voltage from the catenary for rolling stock is highly fluctuating according to the substation capacity, vehicle propulsion and regeneration. Especially, the frost and freezing on contact wire in winter can cause a blackout inside vehicle, and also brings about electronic components damaging and the system down. To prevent this problem, a large filter and capacitor is used. But this is not a perfect solution, because it is increasing weight of the unit. In this paper, a new algorithm is proposed to suppress the disturbance without adding devices. Simulation and experimental results show that the proposed algorithm has performance to suppress the disturbance at the sudden input voltage variations.

• Proceedings of the KIPE Conference
• /
• 2020.08a
• /
• pp.205-208
• /
• 2020

This paper examines the approach, enabled by using SiC power devices, to unify the inverter design for central air conditioning (CAC) system for both single- and 3-phase input, and reduce the PFC inductor size to be PCB-mountable. By using SiC-instead of Si-diode in PFC stage, it is possible to increase the switching frequency from 16kHz to 60kHz to reduce the required PFC inductance from 0.93mH to 0.25mH, thus enable PCB-mounting of inductor. With the next step of using 1200V SiC MOSFET instead of Si-IGBT, the DC link voltage can be boosted from 311Vdc to 550Vdc in PFC stage, allowing the inverter and compressor used in 3-phase input CAC be used for single-phase input as well. Furthermore, using SiC MOSFET in inverter stage can further reduce total loss system total loss to 200.8 W. Simulation and experimental results are presented in the paper.

• Proceedings of the KIEE Conference
• /
• 1988.11a
• /
• pp.403-405
• /
• 1988

Recently, Power change devices using thyristor and transistor have grown with the rapid development of power electronics. But the devices using these semiconductors generate harmonics from the non-linear load, which gives rise to various obstacles. In this paper, therefore, as 3 taps are connected in input line, we can multiply the pulse in input line, by which harmonics is reduced.

• Journal of Korean Physical Therapy Science
• /
• v.27 no.2
• /
• pp.80-87
• /
• 2020

Background: The purpose of this study was to investigate the effect of the use of an alternative input device on the patient's work performance and satisfaction in patients with cerebral palsy who cannot use computers. Design: Case Series Description. Methods: The participant was one adult cerebral palsy. The three tasks were applied with an alternative input device (Quick-Glance), 1 session an hour, 3 times a week, a total of 12 times for 4 weeks. The assessment was using the Canadian Occupational Performance Measure (COPM). The evaluation was performed pre-test before the intervention, post-test after the last intervention, and follow-up after one month. Results: The COPM(Satisfaction and performance scores) showed 3 points for pre-test, 7 points for post-test, and 7 points for follow-up. Conclusion: Purposeful computer work activity, which is an alternative input device, has a positive effect on work performance and satisfaction of cerebral palsy patients who are difficult to use computer.

• Journal of Advanced Navigation Technology
• /
• v.19 no.5
• /
• pp.452-457
• /
• 2015

Recently, wearable devices have gained popularity with familiar form factors and designs of eye-wear and watch to satisfy wearers' various preferences. Since UI/UX of smartphones can not be applied directly on smaller wearable devices, text entry on wearable devices is still problematic. In this paper, we first identify UI/UX problems of existing input methods and propose a new input method for wearable devices specifically targeting smartwatch platforms. We design and implement an efficient text entry method for wearable devices using trackball sensor and evaluate its performance and usability.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.20 no.3
• /
• pp.93-104
• /
• 2010

The advent of various mobile devices and mobile services has caused diversification of information stored in a mobile device, e.g., SMS, photos, movies, addresses, e-mails, digital certificates, and so on. Because mobile devices are lost or stolen easily, user authentication is critical to protect the information stored in mobile devices. However, the current user authentication methods using Personal Identification Numbers (PINs) and passwords are vulnerable to Shoulder Surfing Attacks (SSAs), which enables an attacker to obtain user's information. Although there are already several SSA-resistant authentication methods in the literature, most of these methods lack of usability. Moreover, they are not suitable for use in mobile devices. In this paper, we propose a user friendly password input method for mobile devices which is secure against SSA. We also perform user tests and compare the security and usability of the proposed method with those of the existing password input methods.

• Journal of Korea Multimedia Society
• /
• v.19 no.1
• /
• pp.60-67
• /
• 2016

PC users have long been controlling their computers using input devices such as mouse and keyboard. To improve inconveniences of these devices, the method of screen-touching has widely been used these days, and devices recognizing human gestures are being developed one after another. Fox example, Kinect, developed and distributed by Microsoft, is a non-contact input device that recognizes human gestures through motion-recognizing sensors, thus replacing the mouse as an input device. However, when controlling the mouse on a large screen, it suffers from the problem of requiring large motions in order to move the mouse pointer to the edges of the screen. In this paper, we propose a joystick-driven mouse-controlling method which enables the user to move the mouse pointer to the corners of the screen with small motions. The experimental results show that movements of the user's palm within the range of 30 cm ensure movements of the mouse pointer to the edges of the screen.

• Proceedings of the KIEE Conference
• /
• 2002.11c
• /
• pp.290-293
• /
• 2002

For small capacity rectifier circuits such as these for consumer electronics and appliances, capacitor input type rectifier circuits are generally used. Consequently, various harmonics generated within the power system become a serious problem. Various studies of this effect have been presented previously. However, most of these employ switching devices, such as FETs and the like. The absence of switching devices makes systems more tolerant to over-load, and brings low radio noise benefits. We propose a power factor connection scheme using a LC resonant in commercial frequency without switching devices. In this method, It makes a sinusoidal wave by widening conduction period using the current resonance in commercial frequency, Hence, the harmonic characteristics can be significantly improved, where the lower order harmonics, such as the fifth and seventh orders are much reduced. The result are confirmed by the theoretical and experimental implementations.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2003.11a
• /
• pp.403-406
• /
• 2003

For small capacity rectifier circuits such as these for consumer electronics and appliances, capacitor input type rectifier circuits are generally used. Consequently, various harmonics generated within the power system become a serious problem. Various studies of this effect have been presented previously. However, most of these employ switching devices, such as FET and the like. The absence of switching devices mattes systems more tolerant to over-load and brings low radio noise benefits. We propose a power factor correction scheme using a LC resonant in commercial frequency without switching devices. In this method It makes a sinusoidal wave by widening conduction period using the current resonance in commercial frequency, Hence, the harmonic characteristics can be significantly improved, where the lower order harmonics, such as the fifth and seventh orders are much reduced The result are confirmed by the theoretical and experimental implementations.

• 제어로봇시스템학회:학술대회논문집
• /
• 2002.10a
• /
• pp.51.5-51
• /
• 2002

In this paper, we propose and developed a keyglove using the touch-typing method as new solutions to the problem of text input into the mobile computing devices. This device recognizes that character is typed in though the hand's movements analysis and requires no additional space on a person's desktop or work surface, and can be easily used with computers of any size, even the smallest mobile computer, and is designed as an input device for wearable computers and virtual environment. The concept of the wearable input device based on human hand-molies recognition.