• Journal of Institute of Control, Robotics and Systems
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• v.18 no.10
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• pp.934-939
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• 2012

This paper proposes a new algorithm for ultrasonic sensors arranged on ring frame to identify obstacles surrounding itself by TOFs (time of flight). The ring frame has multiple channels consisting of a transmitter and a receiver. When the transmitter of a selected channel transmits ultrasonic signal, the TOFs of reflected signals from obstacles are acquired by the receiver of the channel. The process continues for all channels consecutively. Then, by using parabolic curve fitting of TOFs of all channel, the proposed algorithm not only calculates distances from multiple obstacles, but also identifies if the shape of obstacles are point or plane by the coefficients of the curve. By the experiment using 16 ultrasonic transceivers on the ring frame in the environment of two poles and two planes, we show the feasibility of the proposed scheme.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.7 s.361
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• pp.53-58
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• 2007

OFDM (orthogonal frequency division multiplexing) is an effective modulation technique for high speed transmission over fading channels. However, it has a high bit error rate in the receiver if there is an error on frame synchronization because of phase rotation. A coherent OFDM system has to acquire exact timing synchronization of fraction and integer sampling positions. When a sampling offset exist the performance of a receiver will be degraded severely. In this paper, we propose an algorithm that acquires the fractional sampling offset in OFDM systems. This scheme compares the channel impulse responses with the early and late sampled signals having 0.5 sample offset from the estimated sampling positions by correlation with the received and training samples. Its performance is verified by computer simulations in multipath channels.

• Journal of Institute of Control, Robotics and Systems
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• v.3 no.6
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• pp.602-612
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• 1997

With GPS carrier phase measurements from more than two antenna which attached to the vehicle, precise attitude can be easily obtained if the integer ambiguity included in carrier phase measurement is resolved. Recently some special products which use dual frequencies or has one receiver engine with multiple antenna are announced. But there are still strong requirements for the conventional single frequency off-the-shelf receiver. To meet these requirements, an efficient integer ambiguity resolution technique is indispensable. In this paper, a new technique to resolve integer imbiguity with single frequency receivers is proposed. The proposed method utilize the known baseline length as a constraint of independent elements of integer ambiguities. With this constraints, the size of search volume can be greatly reduced. Thus the true integer ambiguity can be easily determined with less computational burden and number of measurements. The proposed method is applied to real data to show its effectiveness.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.10A
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• pp.1473-1479
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• 2000

This paper presents the performance evaluation of an adaptive QAM scheme under flat and frequency selective fading channels for indoor wireless communication systems. The QAM modulation is combined with differential encoding and the demodulation process is carried out noncoherently. The adaptation is performed by varying the modulation level of QAM, depending upon received signal strength. The adaptation mechanism allows a 2- or 3-bit increase or decrease at a time, if the channel condition is considered to be significantly good or bad. Simulation results show that the average number of bits per symbol (ABPS) for each symbol block transmitted over a flat fading channel is higher than 5.0 and the BER performance is better than 10^-4 for a SNR value higher than 30 dB. For frequency selective fading channels, an oversampling technique in the receiver was employed. The BER performance obtained for frequency selective fading channels is better than 10^-4 with a SNR value of 40 dB and ABPS is found to be approximately 5.5. Therefore, this scheme is very useful in that it provides both very high bandwidth efficiency and acceptable performance with moderate SNR values over flat and frequency selective fading channels. In addition, this scheme provides reduced receiver complexity by way of noncoherent detection.

• Journal of Korea Society of Industrial Information Systems
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• v.25 no.5
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• pp.13-21
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• 2020

This paper proposes a sign reversal channel switching method in space-frequency block code for orthogonal frequency division multiplexing system. In case of sending source data on other antenna, it is necessary for the receiver to change combining method according to the channel variation. If one does not know the predefined channel switching sequence, it is not possible to decode the received data precisely. In transmit data symbols' exchanges for a channel switching, data symbols are exchanged according to a format of space-frequency block code. In this paper, we proposes a simple sign reversal method except exchanging data symbols between transmit antennas. It is shown that this method occurs another combining method for a simple encryption in the receiver.

• Cross-Cultural Studies
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• v.19
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• pp.271-293
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• 2010

Japanese Give and Receive Verbs are divided into "YARU", "MORAU" and "KURERU". These are influenced by the subject, speaker's viewpoint and meaning. Three verbs are used in a different way depending on who is the giver and who is the taker. I analyze "YARU" and "KURERU" Verbs used in TOUSEISYOUSEIKATAGI. It focus on politeness, gender, and meaning when combined with 'TE'. As an expression of politeness, 'Yaru' is to give to a person of lower social status or an animal or plant. 'Ageru' is to give to an equal ora person of lower social status nowadays. However, 'Ageru' which is treated as elegance of the language remained expression of respect, 'Yaru' is used when the receiver is a person of lower social status and equal social status in TOUSEISYOUSEIKATAGI. 'Kureru' is used when the receiver is a person of lower social status and equal social status, 'kudasaru' is used when a person of higher social status gives the speaker something in TOUSEISYOUSEIKATAGI. Women speakers use 'oyarinasai' 'oyariyo' 'ageru' 'okureru' and men speakers use 'yaru' 'kureru'. Speech patterns peculiar to men are 'kuretamae' 'kurenka'. If the verbs are joined to "TE", they obtain abstract meaning as well as a movement of things. They express some modality for action of the preceeding verbs. The modality has the following meanings ; good will, goodness, benefits, kindness, hopeness, expectation, disadvantage, injury, ill will and sarcasm. In addition, 'TE YARU' expresses the speaker's strong will, 'TE KURERU' expresses the speaker's request.

• Asia pacific journal of information systems
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• v.32 no.4
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• pp.830-856
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• 2022

The Digital Government landscape is changing to reflect how governments try to discover innovative digital solutions, and how they transform themselves in the process. In addition, with the advent of information and communication technology (ICT), e-governance became an essential part of the government. Among the services provided by the Korean government, the Minwon24 online portal is the most used one. However, it has some processing limitations, namely: (1) it provides a cumbersome document authenticity service; (2) people cannot know what happened even if the agency handles the documents arbitrarily. To address the issues outlined above, blockchain processing can be a good alternative. It has a tremendous potential in that it has maximum transparency and a low risk of being hacked. Resource management is one of the areas where blockchain is frequently used. The present study suggests a new model based on blockchain for Minwon24; the proposed model is a type of resource management. There are three participants: issuer, owner and receiver. The proposed model has two stages: issuing and exchanging. Issuing is creating civil documents on the database, which is BigchainDB in this study. Exchanging, the next stage, is a transaction between the owner and the receiver. Based on this model, the actual program is built with the programming language Python. To evaluate the model, the study uses various criteria and it shows the excellence of the model in comparison to others in prior research.

• Journal of the Korean Wood Science and Technology
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• v.36 no.1
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• pp.61-68
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• 2008

The effect of rupture on the speed of ultrasonic wave was investigated with the PUNDIT and the effective detecting method of defects, moving transmitter and receiver. The speed of ultrasonic wave according to the course of rupture was not affected by transmitter and receiver and in the course of parallel rupture, but only in the course of vertical rupture. When rupture was not located on the ultrasonic wave progressing course, rupture was not detected. However, if rupture was formed perpendicularly to the ultrasonic wave progressing course but located on the ultrasonic wave progressing direction, rupture can be detected. Also, the rupture can be detected, when one transmitter and receiver was placed at top and the other at bottom. After detecting rupture in a part, rupture was determined accurately, placing and moving two transmitters and receivers at width.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.39 no.8
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• pp.26-32
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• 2002

In this paper, we propose a suboptimal receiver combining adaptive array antenna and orthogonal decision-feedback detector in DS/CDMA system. Adaptive way antenna can cancel out undesired signal using beamforming scheme. However, if there are interfering signals from undesired users with the same incident angle as that of a desired user, an adaptive array antenna cannot suppress them. The proposed receiver can cancel out remaining interference from users having nearly the same beam pattern. And we employ Orthogonal Decision-Feedback Detector (ODFD) as Multiuser detection. The ODFD performs as good as the decorrelating decision -feedback detector (DDFD) with much less complexity. Simulation results show that the proposed system provides a significantly enhanced performance.

• Journal of Advanced Navigation Technology
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• v.11 no.1
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• pp.17-23
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• 2007

This paper, describes the VDR physical layer design in VDL Mode-2 in order to meet the requirements of International standards. VDR's frequency band is 117.975~137MHz, and CSMA(Carrier Sense Multiple Access), D8PSK(Differential Eight Phase Shift Keyed), 25KHz's channel bandwidth use. The analysis of the isolated channel from near channels, sensitivity of the receiver, dynamic range of the receiver, linear of the transmitter and energy of spurious for linear and non-linear simulation as a requirement condition of performance of VDR and teaches the course of design. The transmitting power level should be lower than 5dB from Po1dB point and the selected IF frequency is 45MHz to suppress the spurious signals. The receiver designed has 4.5dB of Noise figure, 27.52dB of Es/No, Mixer isolation up to 30dB, IIP3 power of LNA up to +10dBm to minimize the intermodulation.