• Journal of KIISE:Information Networking
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• v.33 no.1
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• pp.16-27
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• 2006

The wireless transmission medium inherently broadcasts a signal to all neighbor nodes in the transmission range. Existing asynchronous MAC protocols do not provide a concrete solution for reliable broadcast in link layer. This mainly comes from that an omni-directional broadcasting causes to reduce the network performance due to the explosive collisions and contentions. This paper proposes a reliable broadcast protocol in link taller based on directional antennas, named MDB(MAC protocol for Directional Broadcasting). This protocol makes use of DAST(Directional Antennas Statement Table) information and D-MACA(Directional Multiple Access and Collision Avoidance) scheme through 4-way handshake to resolve the many collision problem wit]1 omni-directional antenna. To analyze its performance, MDB protocol is compared with IEEE 802.11 DCF protocol [9] and the protocol 2 of reference [3], in terms of the success rate of broadcast and the collision rate. As a result of performance analysis through simulation, it was confirmed that the collision rate of the MDB protocol is lower than those of IEEE 802.11 and the protocol 2 of reference [3], and that the completion rate of broadcast of MDB protocol is higher than those of IEEE 802.11 and the protocol 2 of reference [3].

• Proceedings of the IEEK Conference
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• 2004.08c
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• pp.658-662
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• 2004

This paper proposes an orthogonal reception structure for OS/SS communication with time-shifted m-sequences, and compares the performances of the proposed and conventional receiver. This structure provides two important characteristics to reference user signal with not only increment of auto-correlation value but also cancel of the cross-correlation value out to zero between the reference user and other user signals. In addition, the structure can be easily implemented with the conventional receiver adding an additional integrator path in parallel and an adder that sums the conventional path output and the new path output signal. Hence, the proposed structure can be applied for channel impulse response measurement, and efficiently used for multi-user interference signal cancellation and channel capacity increment by flexible structural inter-working operation, connection or disconnection, of the new path to conventional receiver structure.

• International journal of advanced smart convergence
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• v.6 no.2
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• pp.65-71
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• 2017

Fingerprints are increasingly used for user authentication in small devices such as mobile phones. Therefore, it is important for Fingerprint authentication systems in personal devices to protect the user's fingerprint information while performing efficiently with a lightweight matching algorithm. In this paper, we propose a new method to extract strong minutiae with unique numbers from fingerprint images. Strong minutiae are at all times obtained from fingerprint images, and can be useful for secure and rapid fingerprint authentication. The binary information of strong minutiae of a fingerprint can be transformed securely and can create cancelable fingerprint templates. Also the bit-strings of strong minutiae decrease computing time necessary for the matching procedure between two fingerprints due to the simplicity of bitwise operations. First, we enroll several fingerprints images of a finger. From these images we select a reference fingerprint and put a number on each minutia. Following this procedure, we search for mated-minutiae between the reference fingerprint and other fingerprints one by one. Finally we derive unique numbers of strong minutiae of the finger. In the experiment with the FVC2004 fingerprint database, we show that using the proposed method, strong minutiae can be extracted successfully.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.2120-2125
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• 2005

The principal idea of vibration isolation is to filter out the response of the system over the corner frequency. The isolation objectives are to transmit the attitude control torque within the bandwidth of the attitude control system and to filter all the high frequency components coming from vibration equipment above the bandwidth. However, when a reaction wheels or control momentum gyros control spacecraft attitude, vibration inevitably occurs and degrades the performance of sensitive devices. Therefore, vibration should be controlled or isolated for missions such as Earth observing, broadcasting and telecommunication between antenna and ground stations. For space applications, technicians designing controller have to consider a periodic vibration and disturbance to ensure system performance and robustness completing various missions. In general, past research isolating vibration commonly used 6 degree order freedom isolators such as Stewart and Mallock platforms. In this study, the vibration isolation device has 3 degree order freedom, one translational and two rotational motions. The origin of the coordinate is located at the center-of-gravity of the upper plane. In this paper, adaptive notch filter finds the disturbance frequency and the reference signal in filtered-x least mean square is generated by the notch frequency. The design parameters of the notch filter are updated continuously using recursive least square algorithm. Therefore, the adaptive filtered-x least mean square algorithm is applied to the vibration suppressing experiment without reference sensor. This paper shows the experimental results of an active vibration control using an adaptive filtered-x least mean squares algorithm.

• Journal of Positioning, Navigation, and Timing
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• v.7 no.1
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• pp.43-52
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• 2018

In recent years, the need of high accuracy navigation for vehicles has increased due to the development of autonomous driving vehicles and increase in land transportation convenience. This study is performed for vehicle users to achieve a performance of centimeter-level positioning accuracy by utilizing Compact Network Real-time Kinematic (RTK) that is applicable as a national-level infrastructure. To this end, medium-baseline RTK was implemented in real time to estimate accurate integer ambiguities between reference stations for reliable generation of Network RTK correction using the linear combination of carrier-phase observations and L1/L2 pseudo-range measurements. The residual tropospheric error was estimated in real time to improve the accuracy of double-differenced integer ambiguity resolution between network configuration reference stations that have at least 30 km or longer baseline distance. In addition, C++ based software was developed to enable real-time generation and broadcasting of Compact Network RTK correction information by utilizing an accurately estimated double-differenced integer ambiguity values. As a result, the horizontal and vertical 95% accuracy was 2.5cm and 5.2cm, respectively, without performance degradation due to user's position change within the network.

• Proceedings of the KIEE Conference
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• 2006.04a
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• pp.75-77
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• 2006

In this paper, the technology of the conformance test for Broadcast Web Site Service (BWS) which is one of the data services of the T-DMB (Terrestrial Digital Multimedia Broadcasting) is proposed. First, the standard of the BWS Service is introduced and then the method of the conformance test of BWS bitstream and BWS receiver module is provided. A BWS bitstream analyzer is implemented for use in verifying the transmitted BWS bitstreams. To provide a means for the receiver manufactures to verify their own BWS receiver modules, a receiver test suite is developed including BWS test bitstreams and a BWS reference receiver module. The BWS bitstream analyzer includes the analysis function for the conformance test of MOT protocol, HTML, PNG, MNG, JPEG, and Ecma Script. Also, it was actually used for verifying the BWS test bitstreams. In the course of developing a HWS receiver module, 4he BWS receiver module under test can be verified by comparing the results of the BWS reference receiver module with those of the receiver module under test. when the same BWS test bitstreams are fed into the two receiver modules.

• International journal of advanced smart convergence
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• v.11 no.2
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• pp.118-127
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• 2022

Barrage language is a new media language based on Internet video. It is a representative expression of the Internet environment regardless of its format and content. As a unique movie viewing characteristic provided by the barrage function, the timeliness of feedback, entertainment, and interactivity of the content are excellent. Characteristic. Barrage language itself is closely related not only to the value of linguistic research, but also to the spread of the Internet in the Internet environment. Based on the current situation of Chinese video sites, this thesis explores how Barrage is an organic cycle of culture and consumption in a specific platform and group, and analyzes its propagation methods and effects. By analyzing the characteristics of content production patterns unique to the barrage culture, implications and reference values for production activities of other cultures, the effect of popularization on viewers and the production and consumption of the 'barrage' culture of the industry is studied, and furthermore, the 'barrage' culture is It was designed to be a reference for the development of the platform, internet culture, and animation industry culture.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.61 no.2
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• pp.103-109
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• 2012

This paper analyzed major factors affecting video quality in IPTV (Internet Protocol TV) services in multicasting under our lab network environment similar to practical IPTV service networks. We measured video qualities for the broadcasting traffics in IPTV multicasting with or without applying QoS (Quality of Service) technique. The measurements allowed us to extract thresholds of network measurement factors affecting the quality for the service. It will be a good choice that the factors can be a reference to ensure stable video quality for practical IPTV services in multicasting.

• ETRI Journal
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• v.31 no.1
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• pp.80-82
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• 2009

In this letter, a new intra-block coding mode is presented to improve the coding efficiency for band-limited signals. A band-limited block is sub-sampled, and the sub-sampled signal is coded on the basis of the conventional prediction/transform coding. The rest of the samples are reconstructed by interpolation at the decoder side without any side information. Experimental results show that the proposed algorithm achieves coding gains of 2.7% for common intermediate format (CIF), 4.29% for quarter CIF, and 6.39% for 720p60 sequences against the H.264/AVC JM10.2 reference software.

• ETRI Journal
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• v.31 no.4
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• pp.466-468
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• 2009

In this letter, we propose a one-way ranging algorithm that is based on wireless synchronization with measured timestamps and clock frequency offsets. In our proposed algorithm, an active mobile node initiates a ranging procedure by transmitting a ranging frame, and the anchor nodes report their timestamps for the received ranging frame to a reference anchor node. The synchronization of a pair of nodes is provided with instantaneous time information, and the corresponding difference of distances can be calculated.