Yonghwan Kim

PUF-based Encryption Processor for the RFID Systems

The attacker can access the RFID systems illegally because authentication operations on the RFID systems are performed in wireless communication. Authentication methods based on the PUF were presented to defend attacks. Because these utilize Hash and AES, the cost is expensive for the low-cost RFID tag. In this paper, the PUF-based encryption processor and the low-cost RFID authentication protocol are proposed. The challenge-response pairs (PUF’s input and output) are encrypted by the PUF’s characteristics, not by Hash and AES. Besides, the encryption method is changed by the instruction code. Therefore, it is difficult for the attacker to analyze challenge-response pairs. The proposed scheme defends several kinds of attacks, which are physical, modeling, spoofing and location tracking attacks. We implemented the PUF-based encryption processor at low cost with small footprint and low power.

Improved 4-ary Query Tree Algorithm for Anti-Collision in RFID System

In RFID system, because a collision occurs while a reader attempts to identify multiple tags at the same time, the anti-collision algorithm is necessary. This paper uses the tree based algorithm expressed in the form of a B-ary tree, in which the time required to indentify all tags varies according to the value of B(B≥2). An increase in the value of B will decrease the number of collision cycles, while increasing the number of idle cycles. In order to solve this problem in previous algorithms, an Improved 4-ary Query Tree Algorithm (I4QTA) is suggested. If a collision occurs, the I4QTA uses the Bits Change Method (BCM) to remove idle cycles by only detecting the tag IDs that actually exist. In other words, it can quickly identify all tags by reducing the number of query-responses.

An Improved Anti Collision Algorithm using Parity Bit in RFID System

The RFID (radio frequency identification) is a technology that automatically identifies objects containing the electronic tags by using radio frequency. In RFID system, the reader needs the anti collision algorithm for fast identifying all of the tags in the interrogation zone. This paper proposes the tree based anti collision algorithm using parity bit (ACPB) to arbitrate the tag collision. The proposed algorithm identifies tags without checking all the bits in the tags. The reader uses the parity bit which is added to the tag IDs. If there are two collided bits in tags, then reader identify tags by the parity concept. The reader can identify two tags using ACPB algorithm. ACPB can reduce the number of the requests from the reader, thus it shortens the time of identifying all of the tags in the interrogation zone.

An Enhanced Slotted Binary Tree Algorithm with Intelligent Separation in RFID systems

In RFID systems, identifying the tag attached to the subject begins with the request from a reader. When the reader sends a request, multiple tags in the readers interrogation zone simultaneously respond to it, resulting in collision. The reader needs the anti collision algorithm which can quickly identify all the tags in the interrogation zone. We propose the Enhanced Slotted Binary Tree Algorithm with Intelligent Separation (IS-ESBT). In IS-ESBT, a collision can be prevented because the tags which match with the prefix of the readers request respond as followings; the group of tags with an even number of 1s in the bits to the prefix + 2nd bits responds in slot 0, while the group of tags with an odd number of 1s responds in slot 1. The IS-ESBT generates the request prefix so that the only existing tags according to the response in the corresponding slot. That is, it decreases the tag identification time by reducing the overall number of requests.

A remote monitoring and control of home appliances on ubiquitous smart homes

The goal in this paper is to design and implementation the service agent society mechanism of home network community by using Jini platform. On Ubiquitous smart homes environment, this mechanism can make various services to be used among service agents. Based on the mobility of service agent on the Jini platform and instant messaging system (IMS), the mobile device can receive the real time notify from its federation leader in order to download the necessary service, to remove the unnecessary service, or to update the newly service without reconfiguring the system. Moreover, using the Natural Language Processing, the client is possible to express smoothly the order. Therefore, our proposed agent-based management system for ubiquitous smart homes provides a user-friendly interface, and can make use of add-on functionalities of the IMS such as voice chatting, SMS, and multimedia.

An anti-collision algorithm without idle cycle using 4-ary tree in RFID system

This paper proposes an anti-collision algorithm needed in the process of recognizing data of the tags when one reader and multiple passive tags simultaneously have data communications in RFID system. QTA And 4-ary QTA which are based on the Tree algorithm, have the problem that the numbers of query - response are many and the idle cycle (requesting about non-existent tag) exists in the process of recognizing the tags. Advanced 4-ary Query Tree Algorithm(A4QTA) has a 4-ary tree structure and when tag responses according to query of the reader, it applies a digital coding method, the Manchester code, in order to detect the collision point. Also, this algorithm reduces the number of query-response compared to QTA and 4-ary QTA by devising a method for one bit collision and series two bit?s collision in these bits as well as improves the performance by removing the idle cycle.

A tag prediction anti-collision algorithm using extra bits for RFID tag identification

Tags have their own unique identifiers and information, and send such information to a reader; thereby the reader identifies the ID. The proposed algorithm predicts the tag ID by using the number of collided bits and the number of 1s in tag response signal. Even if tag collision occurs in the identification process, the reader identifies the RFID tag through prediction based on information provided by the extra bits. If the number of 1s to be included in collided bits is 1 or collided bits -1, the reader identifies tags as many as the number of collided bits.

A Non-Volatile Memory Management Scheme for Automotive Electronic Control Units

Recently, the number of automotive electrical and electronic system has been increased due to growth of the requirements for safety and convenience for drivers and passengers. In most cases, the data for either user or system to be used in runtime should be stored on internal or external nonvolatile memory. However, the non-volatile memory has a constraint with write limitation. The limit causes fatal accidents or unexpected results. In this paper, we proposed a management algorithm for using none-volatile memory to prolong the writing access times. Our proposal uses an algorithm which swaps a frequently modified block for a least modified block. In the resorting to our experimental results, the proposed scheme can extend the lifetime of non-volatile memory about 1.78 to 2.56 times.

A Tag Prediction Algorithm using Upper Bit in RFID systems

In RFID (Radio Frequency IDentification) system, the reader needs the anti collision algorithm for fast identifying all of the tags in the interrogation zone. This paper proposes the tree based Tag Prediction Algorithm using Upper Bit (TPAUB) to arbitrate the tag collision. A TPAUB can identify tags without identifying all the bits in the tag ID. The reader uses the upper bit which is added to the tag ID and if there are two collided bits or multiple collided bits, it checks the upper bit and grasps the number the number of identified dasia1psilas. A TPAUB can reduce the number of the requests transmitted from the reader, thus it shortens the time of identifying all of the tags in the interrogation zone.

Performance Analysis of Flash File System for the Efficient I/O on Smart Device

Recently NAND flash memory has been found to be the primary cause of low performance in the smart device. NAND flash memory is different from each other the execution time of I/O operations that flash file system is required. Therefore, it is necessary to compare and analyze the flash file system I/O performance for the efficient I/O on smart device. In this paper, it was tested and analyzing the I/O performance of the YAFFS2, JFFS2, UBIFS. Experimental results most read I/O performance is good, but the writing I/O performance is not good. For UBIFS, showed a more good I/O performance compared to other flash file system.