• Journal of the Korea Society of Computer and Information
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• v.12 no.4
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• pp.69-75
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• 2007

On the wireless communication between RFID Tag and Reader, there are some existing problems with weaknesses of security such as spoofing, replay, traffic analysis, position tracking, etc., in the established hash lock related algorithm. This paper has presented the comparison and analysis of the established hash lock related algorithm for privacy and in order to make up for this, also suggested a new security authentication algorithm based on hash which has an authentication protocol and creates hash function by using random numbers received from the reader on real time and every session. The algorithm suggested here can offer a several of usefulness for RFID authentication system and it has an advantage to reduce the amount of calculations compared to established algorithm. It also uses the tags needed among a lot of tags around which are expected later and it is expected to reduce a responsibility of the server by ending unnecessary tags' operation with time based.

• Journal of Korean Physical Therapy Science
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• v.29 no.1
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• pp.41-46
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• 2022

Background: The purpose of this study was to develop a sit-to-stand transfer assistive device, and to conduct a feasibility test. Design: A technical note. Methods and results: In this study, we developed a sit-to-stand transfer assistive device for the elderly and the disabled who have difficulty standing up independently from sitting positions. The sit-to-stand transfer assistive device allows the user to transfer the weight from a sitting position to a standing position while shifting the weight forward by grabbing and pulling a support stand. Ten healthy adults participated in the feasibility test of the device. Each participant used the developed sit-to-stand transfer assistive device and investigated supplementation through a brief interview. As a result of the feasibility test, the opinion was that the device could assist the sit-to-stand transfer to some extent. There were opinions that it needed a function to adjust the height of the knee protective plate in the sitting position according to the user's physical characteristics. Because of the inconvenience of operating the lock device for fixing the position and adjusting inclination, there was an opinion that the improvement for a locking device is needed. There were opinions that it would be better to reduce the size of the device due to its inconvenience of portability. Conclusion: In this study, we developed the sit-to-stand transfer assistive device for the elderly and the disabled who have difficulty standing up independently from sitting positions. In addition, it is considered that the upgrade of the device is necessary for the future since there are supplementary opinions on some points.

• 유체기계공업학회:학술대회논문집
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• 2004.12a
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• pp.329-336
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• 2004

The lock-up position of the floating ring seal affects the leakage flowrate and the stability. And it is changed depending on the operating and geometry condition. In this paper, the leakage flowrate and stability with change of the height and length were investigated by theoretical analysis and experiment. The parameter of the height and length is expressed to the b and L. The decreasing of the b resulted in the increasing of equivalent whirl frequency ratio in the experimental result at the low speed and high pressure not such as theoretical analysis. As the L increased the leakage flowrate decreased and stiffness and direct damping coefficient increased in the experimental result. That was similar to the theoretical analysis.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.292-292
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• 2008

The superconducting fault current limiter(SFCL) can be used to limit fault current level in electrical transmission line and power system. Up to now, there are several kinds of SFCL that have proposed and it is expects that they will be applied to appropriated position considering their own properties; initial fault current limiting instant and the current limiting characteristics. In this paper, we investigated the initial fault current limiting instant and the amplitude of initial fault current in the resistive type, the flux-lock type, the flux-coupling type and the transformer type SFCL. Experiment results show that the initial fault current limiting instant and the amplitude of initial fault current of the SFCLs are dependant on the ratio of inductance of primary and secondary coils.

• The Journal of Korean Physical Therapy
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• v.20 no.4
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• pp.71-78
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• 2008

Purpose: This study standardizes the position and direction of devices based on general user expectations and stereotypes. Population stereotypes are cognitive structures that contain the perceiver's knowledge, beliefs, and expectations about human groups. In this paper, the stereotypes that people typically expect when manipulating 'cylindrical key-in-knob locks' and 'lever-type water faucet handles' were investigated and data regarding their expectations were collected. Methods: Two sets of 600 participants, between 13 and over 60 years old, were recruited for the experiment. Each group was evenly subdivided into six age groups. Each participant was presented with cylindrical door locks mounted on a miniature door and actual lever-type water faucet handles mounted on a mockup sink. Results: If the cylindrical lock was positioned 'vertically,' 59.2% of the participants expected the device to be locked, and if the lever type faucet handle was positioned 'up,' 63.0% of the participants expected the device to be turned on. Thus, daily-use devices should be designed consistent with user expectations of operation. There was a significant difference between genders for manipulating the faucet handle between up and down. Conclusion: A more general stereotype may be defined by repetitive measurements under the same test conditions with fixed time intervals, as well as accounting for people with cognitive problems.

• Progress in Medical Physics
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• v.19 no.1
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• pp.42-48
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• 2008

Bio-implantable devices such as heart pacers, gastric pacers and drug-delivery systems require power for carrying out their intended functions. These devices are usually powered through a battery implanted with the system or are wired to an external power source. This paper describes an inductive power transmission link, which was developed for an implantable stimulator for direct stimulation of denervated muscles. The carrier frequency is around 1MHz, the transmitter coil has a diameter of 46mm, and the implant coil is 46mm. Data transmission to the implant with amplitude shift keying (ASK) and back to the transmitter with passive telemetry can be added without major design changes. We chose the range of coil spacing (2 to 30mm) to care for lateral misalignment, as it occurs in practical use. If the transmitter coil has a well defined and reliable position in respect to the implant, a smaller working range might be sufficient. Under these conditions the link can be operated in fixed frequency mode, and reaches even higher efficiencies of up to 37%. The link transmits a current of 50 mA over a distance range of 2-15 mm with an efficiency of more than 20% in tracking frequency. The efficiency of the link was optimized with different approaches. A class E transmitter was used to minimize losses of the power stage. The geometry and material of the transmitter coil was optimized for maximum coupling. Phase lock techniques were used to achieve frequency tracking, keeping the transmitter optimally tuned at different coupling conditions caused by coil distance variations.