• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.7 s.337
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• pp.63-70
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• 2005

We investigated the phase noise of an oscillator with a extremely high-Q resonator used as the resonant element. A TE$_{011}$ mode rutile-loaded resonator with high-temperature superconductive (HTS) $YBa_2Cu_3O_{7-\delta}$(YBCO) films used as the endplates is prepared for this purpose. At 23.5 K, the unloaded Q and the loaded Q are 863000 and 180000, respectively. The phase noise of -104.8 dBc/Hz at 1 KHz offset was observed for the oscillator having a resonator with $Q_{L}$ =180000 at the $TE_{01\delta$ mode resonant frequency of 8.545 GHz at 23.5 K Such oscillators with very low phase noise are expected to be used for building up communication systems capable of efficient use of the frequency band and high-speed data transmission as well as for Doppler radars. Frequency tuning could be realized for the resonator by using a piezoactuator Applicability of the tunable rutile resonator for fabricating tunable oscillators of high performances is discussed.

• The Journal of Society for e-Business Studies
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• v.13 no.1
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• pp.21-32
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• 2008

RFID systems provide technologies of automatic object identification through wireless communications in invisible ranges and adaptability against various circumstances. These advantages make RFID systems to be applied in various fields of industries and individual life. However, it is difficult to use tags with distinction as tags are increasingly used in life because a tag usually stores only one object identifier in common RFID applications. In addition, RFID systems often make serious violation of privacy caused by various attacks because of their weakness of radio frequency communication. Therefore, information sharing methods among applications are necessary for expansive development of RFID systems. In this paper, we propose efficient RFID scheme. At first, we design a new RFID tag structure which supports many object identifiers of different applications in a tag and allows those applications to access them simultaneously. Secondly, we propose an authentication protocol to support the proposed tag structure. The proposed protocol is designed by considering of robustness against various attacks in low cost RFID systems. Especially, the proposed protocol is focused on efficiency of authentication procedure by considering security levels of applications. In the proposed protocol, each application goes through one of different authentication procedures according to their security levels. Finally, we prove efficiency of th proposed scheme compared with the other schemes through experiments and evaluation.

• The KIPS Transactions:PartC
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• v.17C no.6
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• pp.471-484
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• 2010

In the wireless communication systems, the power consumption of a mobile device is very important issue due to its battery limitations. Hence most of the standards for wireless networks including a mobile WiMAX system are supporting their own power saving mode in way that a mobile device is able to reduce its energy usage while in the mode. However, those standards just define the arrangement of special time intervals, called a paging listening interval, during which the device needs to receive the paging-related control messages, and they do not specify how to effectively reduce the power in many different network environments. This means the amount of power spent by the device is very dependent on the implementations of individual device-vendors, and undesirable paging loss may happen according to the channel conditions. To reduce unnecessary power usage and the risk of paging loss, this paper proposes the effective frequency/BS selection algorithm applicable to a mobile device operating in the power saving mode, which serves the device with better BS based on the tracking for channel variation. This algorithm consists of the channel estimation phase during each paging listening interval, the tracking phase for the measured results, the frequency reselection phase based on the tracking activity, and the preferred BS reselection phase. Thus the proposed method can improve the paging performance while the device is moving in the network. Also the simulation result shows that the presented scheme is superior to other candidates in energy efficiency due to the channel-adaptive frequency/BS selection.

• Journal of Engineering Education Research
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• v.9 no.2
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• pp.34-51
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• 2006

In knowledge based society of 21c, engineers require not only their own speciality but also engineering basic competency such as creative thinking, the ability of working together, the ability of communication. Engineering colleges responsible for educating engineers consider developing curriculum including Engineering Basic Competency which is reflecting the needs of the times. By utilizing the accreditation programs of engineering education, UK-SPEC of UK Engineering Council, EA(Engineering Australia) standards/handbook of the Institute of Engineers Australia, O*NET of U.S. Occupational Network, this study generates core elements of engineering basic competency to prove the capability of engineering basic competency required to desired engineers. Core constituents derived from the study were categorized into 3 major areas of the basic engineering literacy in Humanities and Social Sciences(HSS), the ability of Creativity Engineering Design, Career development and each category and constituents were surveyed and checked by engineers in the field to deduce engineering basic competency that should be educated in the engineering college.

• Proceedings of the Korea Contents Association Conference
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• 2004.11a
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• pp.327-332
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• 2004

USB(Universal Serial Bus) is one of the most popular communication interfaces. When USB is used in an extended range, especially configurating In-home network by connecting multiple digital devices each other, USB interface uses the bandwidth in the way of TDM(Time Division Multiplexing) so that the bottleneck of bus bandwidth can be brought. In this paper, the more effective usage of bus bandwidth to overcome this situation is introduced. Basically, in order to realize the system for transferring realtime moving picture data among digital information devices, we analyze USB transfer types and Descriptors and introduce the method to upgrade detailed performance of Isochronous transfer that is one of USB transfer types. In the case that Configuration descriptor of a device has Interface descriptor that has two AlternateSetting, if Isochronous transfers are not processed smoothly due to excessive bus traffic, the application of the device changes AlternateSetting of the Interface descriptor and requires a new configuration by SetInterface() request. As a result of this adaptive configuration, the least data frame rate is guaranteed to a device that the sufficient bandwidth is not alloted. And if the bus traffic is normal, the algorithm to return to the original AlteranteSetting is introduced. this introduced method resolve the bottleneck of moving picture transfer that can occur in home network connected by multiple digital devices.

• Journal of Advanced Navigation Technology
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• v.19 no.5
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• pp.423-432
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• 2015

This paper shows that design, manufacture and the performance of FC-NIC (fibre channel network interface card) for network unit configuration which is based on one of the 5 main configuration items of the common functional module for IMA (integrated modular Avionics) architecture. Especially, FC-NIC uses zynq SoC (system on chip) for host load reductions. The host merely transmit FC destination address, source memory location and size information to the FC-NIC. After then the FC-NIC read the host memory via DMA (direct memory access). FC upper layer protocol and sequence process at local processor and programmable logic of FC-NIC zynq SoC. It enables to free from host load for external communication. The performance of FC-NIC shows average 5.47 us low end-to-end latency at 2.125 Gbps line speed. It represent that FC-NIC is one of good candidate network for IMA.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.2
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• pp.47-55
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• 2010

The power line communication channel has characteristic variation problems which are caused by load. The spread spectrum technique has been used to overcome these problems. One of that is the direct sequence spread spectrum(DS/SS) system which is not necessary to additional hardwares. The BER of DS/SS system is decreased by longer length of PN code, but data transfer rate is decreases, so data transfer rate is hard to satisfies their own specifications especially in narrowband PLC systems. Spread Spectrum system with Dual-processing Gain tries to reflect cyclic characteristics of power line noise. But that system assumes that shapes of power line channel are symmetrical with respect to the 1/4 point of main frequency(60Hz in Korea), therefore cannot achieves various shapes of real power line noise. Thus in this paper, noise adaptive DS/SS system which PN code is changed by noise levels for various channel noises is proposed and simulated. The different kinds of noises are modeled and measured for simulation, the proposed system is verified that has lower data transfer rate and lower error rate than conventional system by simulation results.

• The Korean Journal of Elementary Counseling
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• v.11 no.3
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• pp.427-446
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• 2012

The purpose of this study was to investigate the influence of stress in families of children with disabilities upon a problem-solving ability based on a buffering effect of family resilience through life cycle. To achieve this purpose, the subjects in this study was 546 parents who have kindergarten, elementary, middle & high school students in special schools. The date for this study were derived from questionaries and the answer sheet was analyzed by SPSS(VER. 14). A descriptive statistics, correlation analysis, hierarchical moderating regression analysis were used to investigate the general information and the difference of perception between groups. The findings of this study were as follows: Higher belief system, higher organization type, higher communication process of the family with disabled children tend to appear more positive influences on buffering effects for stresses of family and solving-problem abilities. Findings from the current study demonstrate that the buffering effect of family resilience indicate to have positive influences on the relationship between the stress and the problem-solving ability in the family with disabled children.

• KIPS Transactions on Computer and Communication Systems
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• v.2 no.1
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• pp.7-14
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• 2013

Presently, there are many different technologies used for position detection. However, as signal-receiving devices operating in different locations must detect the precise position of objects located at long distances, it is essential to know the precise time at which an object's or a user's terminal device sends a signal. For this purpose, the existing time of arrival (ToA) technology is not sufficiently reliable, and the existing time difference of arrival (TDoA) technology is more suitable. If a TDoA-based electric surveillance system and other tracking devices fail to achieve precise time-synchronization between devices with separation distance operation, it is impossible to obtain correct TDoA values from the signals sent by the signal-receiving devices; this failure to obtain the correct values directly affects the location estimation error. For this reason, the technology for achieving precise time synchronization between signal-receiving devices in separation distance operation, among the technologies previously mentioned, is a core technology for detecting TDoA-based locations. In this paper, the accuracy of the proposed time synchronization and the measurement error in the TDoA-based location detection technology is evaluated. The TDoA-based location measurement error is significantly improved when using the proposed method for time-synchronization error reduction.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.10
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• pp.14-27
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• 2009

Polar Code was proposed by Turkish professor Erdal Arikan in 2006 as an idea that splitted input channel is increasing the cutoff rate. The channel polarization consisted of code sequences with symmetric high rate capacity in a given B-DMC(Binary-input Discrete Memoryless Channel) W. The symmetric capacity is the highest rate achievable subject to using the input letters of the channel with equal probability. The channel polarization is said to a set of given N independent outputs of B-DMC W. In other word, N increases when N is a set of binary-input channels {$W^{(i)}_N\;:\;1{\leq}\;i\;{\leq}\;N$}, in I{WN(i)} as the fraction of indices is near to 1, which is approaching to I(W), and it is near to 0, then to 1-I(W), where I(W) presents high rates in reliable wireless communication channel as inputs of W with equal frequences. After all, {WN(i)} is shown to be a state of channel coding. On the based on this Polar codes, this paper analyzes Polar coding and decoding of Arikan and propose Radix4 Polar coding newly.