• Journal of Digital Convergence
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• v.11 no.4
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• pp.221-227
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• 2013

RFID is an automatic identification technology that can control a range of information via IC chips and radio communication. Also known as electronic tags, smart tags or electronic labels, RFID technology enables embedding the overall process from production to sales in an ultra-small IC chip and tracking down such information using radio frequencies. Currently, RFID-based application and development is in progress in such fields as health care, national defense, logistics and security. RFID structure consists of a reader that reads tag information, a tag that provides information and the database that manages data. Yet, the wireless section between the reader and the tag is vulnerable to security issues. To sort out the vulnerability, studies on security protocols have been conducted actively. However, due to difficulties in implementation, most suggestions are concerned with theorem proving, which is prone to vulnerability found by other investigators later on, ending up in many troubles with applicability in practice. To experimentally test the security of the protocol proposed here, the formal verification tool, CasperFDR was used. To sum up, the proposed protocol was found to be secure against diverse attacks. That is, the proposed protocol meets the safety standard against new types of attacks and ensures security when applied to real tags in the future.

• Journal of Internet Computing and Services
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• v.18 no.4
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• pp.43-50
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• 2017

Embedded System includes touch, GPS, motion, and acceleration sensor, and can communicate with neighbor devices using wireless communication. Because Arduino with embedded system provides good environment for development and application, developers, engineers, designers, as well as artists, students have a great interest. They utilize Arduino in the robot, home appliances, fashion, culture and so on. In this paper, we design and implement a game using Arduino with embedded system which recognizes the human movement by moving away from one-dimensional game of the existing touch method. Implemented embedded system game measures gyro-sensor to recognize human movement and detects the attack success of the opponent by using touch sensor. Moreover, health of the game player is updated in the real time through the android phone-based database. In this paper, implemented embedded system-based game provides GUI screen of android phone. It is possible to select watching mode and competition mode. Also, it has low energy consumption and easy to expand because it send and receive data packet through recent Bluetooth communication.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.05a
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• pp.465-469
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• 2000

This paper describes a single-chip full-custom implementation of pipelined adaptive decision-feedback equalizer (PADFE) using a 0.25-${\mu}{\textrm}{m}$ CMOS technology for wide-band wireless digital communication systems. To enhance the throughput rate of ADFE, two pipeline stage are inserted into the critical path of the ADFE by using delayed least-mean-square (DLMS) algorithm Redundant binary (RB) arithmetic is applied to all the data processing of the PADFE including filter taps and coefficient update blocks. When compared with conventional methods based on two's complement arithmetic, the proposed approach reduces arithmetic complexity, as well as results in a very simple complex-valued filter structure, thus suitable for VLSI implementation. The design parameters including pipeline stage, filter tap, coefficient and internal bit-width and equalization performance such as bit error rate (BER) and convergence speed are analyzed by algorithm-level simulation using COSSAP. The singl-chip PADFE contains about 205,000 transistors on an area of about 1.96$\times$1.35-$\textrm{mm}^2$. Simulation results show that it can safely operate with 200-MHz clock frequency at 2.5-V supply, and its estimated power dissipation is about 890-mW.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.12
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• pp.831-841
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• 2014

The attacker can access the RFID systems illegally because authentication operation on the RFID systems are performed in wireless communication. Authentication methods based on the PUF were presented to defend attacks. Because of Hash and AES, the cost is expensive for the low-cost RFID tag. In this paper, the PUF-based encryption processor and the mutual authentication protocol are proposed for low-cost RFID authentication. The challenge-response pairs (PUF's input and output) are utilized as the authentication key and encrypted by the PUF's characteristics. The encryption method is changed each session and XOR operation with random number is utilized. Therefore, it is difficult for the attacker to analyze challenge-response pairs and attack the systems. In addition, the proposed method with PUF is strong against physical attacks. And the method protects the tag cloning attack by physical attacks because there is no authentication data in the tag. Proposed processor is implemented at low cost with small footprint and low power.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.2
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• pp.9-17
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• 2010

Recently, there has been much interest in orthogonal frequency division multiplexing (OFDM) for next generation wireless wideband communication systems. OFDM is a special case of multicarrier transmission, where a single data stream is transmitted over a number of lower-rate subcarriers. One of the main reasons to use OFDM is to increase robustness against frequency-selective fading or narrowband interference. However, in the radio systems it is also important to distortion introduced by high power amplifiers (HPA's) such as solid state power amplifier (SSPA) considered in this paper. Since the signal amplitude of the OFDM system is Rayleigh-distributed, the performance of the OFDM system is significantly degraded by the nonlinearity of the HPA in the OFDM transmitter. In this paper, we propose a canonical piecewise-linear (PWL) model based digital predistorter to prevent signal distortion and spectral re-growth due to the high peak-to-average power ratio (PAPR) of OFDM signal and the nonlinearity of HPA's. Computer simulation on an OFDM system under additive white Gaussian noise (AWGN) channels with QPSK, 16-QAM and 64-QAM modulation schemes and modulator/demodulator implemented with 1024-point FFT/IFFT, demonstrate that the proposed predistorter achieves significant performance improvement by effectively compensating for the nonlinearity introduced by the SSPA.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.48 no.6
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• pp.63-70
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• 2011

A bicycle is different from vehicles in the structure that a rider is fully exposed to the surrounding environment. Therefore, it needs to make use of prior information about local weather, air quality, trail road condition. Moreover, since it depends on human power for moving, it should acquire route property such as hill slope, winding, and road surface to improve its efficiency in everyday use. Recent mobile applications which are to be used during bicycle riding let us aware of the necessity of development of intelligent bicycles. This study aims to develop a riding state (up-hill, down-hill, accelerating, braking) recognition algorithm using a low-power wrist watch type embedded system which has 3-axis accelerometer and wireless communication capability. The developed algorithm was applied to 19 experimental riding data and showed more than 95% of correct recognition over 83.3% of the total dataset. The altitude and temperature sensor also in the embedded system mounted on the bicycle is being used to improve the accuracy of the algorithm. The developed riding state recognition algorithm is expected to be a platform technology for intelligent bicycle interface system.

• Culinary science and hospitality research
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• v.20 no.6
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• pp.254-261
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• 2014

In order to optimize process conditions for manufacturing retorted Kimchi soup by using stationary and rotary types systems were applied for sterilization process. For investigating the differences in heat penetration characteristics during sterilization, Kimchi soup was packed into retort pouches, and sterility ($F_0$ value) at various positions in the product was measured through a wireless $F_0$ sensor. Heat penetration characteristics were significantly affected by sterilization method. From data analysis, optimum ranges of sterilization temperature and time was determined to be $120.7^{\circ}C$, 13 min for rotary type and $120.7^{\circ}C$, 20 min for stationary type. At those conditions, they had similar sterility ($F_0$ value). The results showed that rotation provides faster heat penetration and more uniform sterility than various positions of the product. These results derived a lot of advantages from related industry. For instance, many of the more viscous semi-liquid products and heat sensitive natural products could be sterilized in the lager pouch sizes without overcooking or scorching. Hence, current study suggests that rotary type retort would make it possible not only to reduce processing times as 35~45%, but also to improve the quality of product as overall taste, flavor, color, and texture with significant difference (p<0.05).

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.7
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• pp.97-103
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• 2004

In this paper, we propose a high speed block turbo code decoding algorithm and an efficient hardware architecture. The multimedia wireless data communication systems need channel codes which have the high-performance error correcting capabilities. Block turbo codes support variable code rates and packet sizes, and show a high performance due to a soft decision iteration decoding of turbo codes. However, block turbo codes have a long decoding time because of the iteration decoding and a complicated extrinsic information operation. The proposed algorithm using the threshold that represents a channel information reduces the long decoding time. After the threshold is decided by a simulation result, the proposed algorithm eliminates the calculation for the bits which have a good channel information and assigns a high reliability value to the bits. The threshold is decided by the absolute mean and the standard deviation of a LLR(Log Likelihood Ratio) in consideration that the LLR distribution is a gaussian one. Also, the proposed algorithm assigns '1', the highest reliable value, to those bits. The hardware design result using verilog HDL reduces a decoding time about 30% in comparison with conventional algorithm, and includes about 20K logic gate and 32Kbit memory sizes.

• Information Systems Review
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• v.9 no.2
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• pp.15-39
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• 2007

Mobile games have emerged as the most innovative entertainment technology, adding new revenue streams, taking advantage of the potential of wireless applications and service offerings. Mobile games, like any other types of computer game, offer a unique value for users in providing an exciting digital experience in virtual worlds. In this paper, we attempt to investigate the demographic factors which play critical roles in determining the level of playing times; classify mobile gamers based on their motives for playing games; and empirically test differences in their demographic factors and mobile game usage. Statistical results show that significant differences in playing times exist, depending upon their age, gender, mobile device, mobile phone usage, mobile game experiences, and preferred games genres. Applying Factor analysis, we have identified Escape, Social interaction, Challenge and Competition, Fantasy, Diversion and Relaxation, Ease of Accessibility as key motivators for playing mobile games. Additional cluster analysis shows that the categorization of gamers, according to their usage habits and the key motivators for playing, can be made as follows: Multi-gamers, Communication-focused gamers and Mobile active-gamers. Further correlation of these grouping with socio-economic data shows the significant differences in gaming habits and patterns of mobile phone use.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.2
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• pp.263-267
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• 2015

current mine detector can't division the section if it is conducted and it needs too much labor force and time. in addition to, if the user don't move the head of sensor in regular speed or move it too fast, it is hard to detect a mine exactly. according to this, to improve the problem using one direction ultrasonic wave sensing signal, that is made up of human body antenna part, main micro processor unit part, smart glasses part, body equipped LCD monitor part, wireless data transmit part, belt type power supply part, black box type camera, Security Communication headset. the user can equip this at head, body, arm, waist and leg in removable type. so it is able to detect the powder in a 360-degree on(under) the ground whether it is metal or nonmetal and it can express the 2D or 3D film about distance, form and material of the mine. so the battle combats can avoid the mine and move fast. also, through the portable battery and twin self power supply system of the power supply part, combat troops can fight without extra recharge and we can monitoring the battle situation of distant place at the command center server on real-time. and then, it makes able to sharing the information of battle among battle combats one on one. as a result, the purpose of this study is researching a smart wearable mine detector which can establish a smart battle system as if the commander is in the site of the battle.