• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2008.05a
• /
• pp.374-378
• /
• 2008

The analysis about cases which does not correspond in electric equipment technical standard and judgement standard while doing pre inspection, it improves the technical specifications and the draft of construction plan. The analysis of the reform cases prevents the electric disaster and propagates the electrical safety. Hereafter the reform cases will improve the electric technical ability and help the electrical safety of the yard.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.26 no.4
• /
• pp.88-94
• /
• 2012

The government has pushed ahead with the establishment of a connection system among education-task-qualification with regards to the promotion of engineering industry, but there has been a lack of pertinent data. In this regard, this study investigated the ways of connecting universities' engineering education with Electrical Professional Engineer examination. The results show that the tendency of questions consists of 30[%] of transmission, 16[%] of basic theory, 14[%] of transformer, 14[%] of generation, 9[%] of new technology, 11[%] of other relevant fields. This study also presents a survey on the relationship between the engineer's license and college curriculum. The curriculum of Electrical Engineering Department of a leading National University in Seoul is investigated in relation to the Examination. Some learning materials for successful completion of the university curriculum and acquisition of the Professional Engineer license are also recommended.

• Journal of the Korea Society of Computer and Information
• /
• v.26 no.10
• /
• pp.93-100
• /
• 2021

In this paper, the possibility of a UE (User Equipment) incarceration attack using RRCRejecet and RRCRelease in 5G SNPN (Standalone Non-Public Network) is analyzed based on the 3GPP standard document. First, the cell selection and reselection procedures of the UE are analyzed, and then the processing process of the false base station and the UE before and after transmission of RRCReject and RRCRelease is analyzed. As a result of the analysis, it is possible that the false base station that transmits a strong signal causes the victim UE to establish an RRC connection to the false base station itself. In addition, if the false base station transmits an RRCReject message without integrity protection in response to the victim UE's attempt to establish an RRC connection, it is determined that the victim UE can continue to stay in the RRC connection attempt process. On the other hand, it is determined that it is impossible to incarcerate the victim UE by inducing an attempt to establish an RRC connection to another false base station using RRCRelease.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.14 no.5
• /
• pp.1109-1116
• /
• 2010

In this paper, some performance characteristics of VoIP(Voice over Internet Protocol) for MANET(Mobile Ad-hoc Networks) with simulation is studied and appropriate condition for implementation of VoIP service is suggested. VoIP simulator is implemented with NS(Network Simulator)-2. VoIP traffic for simulation is generated with some codecs of G.711, G.723.1, G.726-32, G.729A, GSM.AMR and iLBC. As simulation results for traffic transmission under $670{\times}670m$ 50node MANET environment, performance data for MOS(Mean Opinion Score), network delay, packet loss rate and transmission bandwidth are measured. Normalized analysis about measured results shows that maximum VoIP connection satisfying VoIP service quality condition is 15.

• The Journal of the Acoustical Society of Korea
• /
• v.24 no.7
• /
• pp.387-394
• /
• 2005

In this paper, we propose a new transmission technique of audio signals for the serial connection of the speakers of multiple-channel audio systems. Analog audio signals from a multi-channel audio system are converted into digital signals with signal processing steps and transferred to each speaker through a serial line. The signal processing steps contain data compression and packet generation in association with audio signal characteristics. Each speaker gets its corresponding digital audio signals from the transmitted packets and converts the signals into analog audio signals to make sounds with the speaker All the proposed functions in this paper are modeled in VHDL. implemented with FPGA chips, and tested for actual multi-channel audio systems.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.27 no.12C
• /
• pp.1207-1214
• /
• 2002

A scheduling scheme for high speed networks requires a low time complexity to schedule packets in a packet transmission time. High speed networks support a number of connections, different rates for each connection and variable packet length. Conventional round robin algorithms have a time complexity of O(1), but their short time fairness, latency and burstiness depend on the quantum of a connection due to serving several packets for a backlogged connection once a round. To improve these properties, we propose in this paper an efficient packet scheduling scheme which is based on the credits of a connection and has a time complexity of O(1). We also analyzed its performance in terms of short time fairness, latency and burstiness. The analysis results show that the proposed scheme can improve the performance compared with traditional round robin schemes. The proposed scheme can be easily utilized in high speed packet networks.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.18 no.10
• /
• pp.2339-2344
• /
• 2014

of a microstrip transmission line, this transmission line can operate as the microstrip line or the coplanar line according to open or short connection between the ungrounded copper plane and grounded plane on the base plane. Two different type operation of the transmission line means that one transmission line can have two different characteristic impedances. This paper proposes and fabricates the circuit to be operated 2-ports power transmission line or 2-way power divider with the stable input matching characteristic by using this dual-impedance transmission line. The proposed circuit operates 2-ports power transmission line in case of the coplanar line or 2-way power divider line in case of the microstrip line. The fabricated circuit shows $S_{21}$ > -0.2 dB and $S_{11}$ < -15 dB above 700 MHz when the circuit operates 2-ports power transmission line. And, it is $S_{21}$ > -3.8 dB, $S_{11}$ < -10 dB and $S_{21}/S_{31}$ < ${\pm}0.3dB$ above 700 MHz when the circuit operates 2-way power divider.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.23 no.10
• /
• pp.1282-1289
• /
• 2019

In order to measure the transfer characteristic(S21) of the impedance transformer, two impedance transformers must be symmetrically connected. However, the transfer characteristic of two symmetrically connected impedance transformers is influenced by the length of the intermediate connection line. This paper theoretically examines closely the length of the intermediate connection line to obtain the accurate transfer characteristic of the impedance transformer. The electrical length of the intermediate connection line for obtaining the accurate transfer characteristic of the 4:1(50-Ω:12.5-Ω) impedance transformer is calculated about 45°. Using the calculated length of the connection line, The λ/4-microstrip impedance transformer is fabricated at 1 GHz to measure the transfer characteristic. The symmetrically connected impedance transformer is measured the reflection characteristic(S11) of -40.64dB and the transfer characteristic(S21) of -0.154dB at 0.980GHz. This value is approximately equal to the theoretical calculated 987MHz center frequency and -0.15dB transfer loss value of the λ/4-microstrip impedance transformer.

• Journal of international Conference on Electrical Machines and Systems
• /
• v.3 no.4
• /
• pp.433-445
• /
• 2014

Single phase voltage source converter (VSC) is an important power electronic converter (PEC), including single-phase voltage source inverter (VSI), single-phase voltage source rectifier (VSR), single-phase active power filter (APF) and single-phase grid-connection inverter (GCI). As the fundamental part of large scale PECs, single-phase VSC has a wide range of applications. In the paper, as first, on the basis of the concept of the discontinuous pulse-width modulation (DPWM) for three-phase VSC, a new DPWM of single-phase VSR is presented by means of zero-sequence component injection. Then, the transformation from stationary frame (abc) to rotating frame (dq) is designed after reconstructing the other orthogonal current by means of one order all-pass filter. Finally, the presented DPWM based single-phase VSR is established analyzed and simulated by means of MATLAB/SIMULINK. In addition, the DPWMs presented by D. Grahame Holmes and Thomas Lipo are discussed and simulated in brief. Obviously, the presented DPWM can also be used for single-phase VSI, GCI and APF. The simulation results show the validation of the above modulation algorithm, and the DPWM based single-phase VSR has reduced power loss and increased efficiency.

• Proceedings of the Korea Contents Association Conference
• /
• 2007.11a
• /
• pp.126-129
• /
• 2007

Recently the use of wireless network increases according to it solves the hand-off and with path loss, pading, noise etc of wireless network the research for transmission error improvement is developed. TCP and SCTP of standard where it guarantees the reliability of wire network apply in wireless network the congestion control, flow control mechanism used it decreases the efficiency of data transfer throughputs. In this paper, It mixes SCTP and SNOOP for SCTP apply on wireless network, to improve BS(Basic Station) operation processes when the transmission error occurs in wireless network. BS send ZWP(Zero Window Probe) to MN(Mobile Node) when the transmission error occurs so, check path and status and update RWND and error status checked. It selects the new path, send ZWA(Zero Window Advertisement) to FH(Fixed Host) and the prevents call to congestion control or flow control and it does to make wait status standing. Continuously of data transfer after the connection of wireless network is stabilized, it make increase about 10% the transmission throughput of data.