• Journal of the Korean Geographical Society
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• v.50 no.5
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• pp.527-541
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• 2015

The purpose of this study is to investigate the changes in the inter-city passenger flows since adapting the express rail system in Korea(KTX). For the purpose, we analyze the express bus and rail passenger annual flow data of the before and after adapting KTX. In first, we examine the changes in the time-distance parameters in the inter-city passenger flows of the express bus, general rail, and KTX by applying gravity model. The results reveal that express bus passenger flows are less sensible to the time-distance compare to the rail passenger flows, and the trends have been intensified over time. However, the time-distance parameters for the KTX passenger flows reveal the reverse relationships with the gravity model. The KTX passenger flows expand between the long distance cities. We also apply the MST(Maximum Spanning Tree) method to find out the spatial structural changes in the inter-city passenger flows. The number of hierarchies has been increased in the express bus and general rail passenger flows, while single hierarchical structure has been lasted in the KTX passenger flows.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.10
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• pp.1708-1712
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• 2008

This paper describes a linear matrix inequality (LMI) approach to the design of robust low-order power system stabilizers (PSSs), which are used to damp out local-mode oscillations of synchronous generators. The performance of a PSS is expressed as the location of the closed-loop poles, and a single fixed-gain pole-placement controller is synthesized for a wide range of operating conditions. The synthesis results in simultaneous regional pole-placement stabilization. and is formulated as an LMI feasibility problem with a rank condition. A penalty method is applied to solve the rank-constrained LMI problem. Numerical experiments with a single-machine connected to an infinite bus system were performed to demonstrate the proposed method.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.32B no.6
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• pp.849-861
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• 1995

In this paper, a new trace driven simulation algorithm is proposed to evaluate the bus traffic and the miss ration of the various sector cache memories, which have various sub-block sizes and block sizes and associativities and number of sets, with a single pass through an address trace. Trace-driven simulaton is usually used as a method for performance evaluation of sector cache memories, but it spends a lot of simulation time for simulating the diverse cache configurations with a long address trace. The proposed algorithm shortens the simulation time by evaluating the performance of the various sector cache configurations. which have various sub-block sizes and block sizes and associativities and number of sets , with a single pass through an address trace. Our simulation results show that the run times of the proposed simulation algorithm can be considerably reduced than those of existing simulation algorithms, when the proposed algorithm is miplemented in C language and the address traces obtained from the various sample programs are used as a input of trace-driven simulation.

• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.6
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• pp.817-824
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• 2016

A simultaneous bidirectional transceiver over a single wire has been developed in a 65 nm CMOS technology for a command and control bus. The echo signals of the simultaneous bidirectional link are cancelled by controlling the decision level of receiver comparators without power-hungry operational amplifier (op-amp) based circuits. With the clock information embedded in the rising edges of the signals sent from the source side to the sink side, the data is recovered by an open-loop digital circuit with 20 times blind oversampling. The data rate of the simultaneous bidirectional transceiver in each direction is 75 Mbps and therefore the overall signaling bandwidth is 150 Mbps. The measured energy efficiency of the transceiver is 56.7 pJ/b and the bit-error-rate (BER) is less than $10^{-12}$ with $2^7-1$ pseudo-random binary sequence (PRBS) pattern for both signaling directions.

• Proceedings of the KIPE Conference
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• 2003.07b
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• pp.671-676
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• 2003

This paper presents 3-phase current regulation of SR motor by only single current sensor. The conventional drive system of SR motor has a current sensor per each phase. In this paper, The asymmetric bridge converter which Is able to control independently phases and be excited simultaneously is used fs the driver system for 6/4 poles SR motor. And the sensor Is replaced 3 sensors of each phase with only one on bus line of converter so as to detect current of every phase. A drive logic circuit is designed on EPLD with Delta modulation using a fixed frequency This technique is verified through simulation and experiment.

• Proceedings of the KIEE Conference
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• 2002.11d
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• pp.200-203
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• 2002

This paper presents Continuous-current mode of $S^4$-PFC(Single-Stage Single-switch Power Factor Correction) converter. Proposed converter operates in the continueous current mode(CCM) at full load and discontinuous current mode(DCM) at light load. So, characteristic of proposed converter is no bus voltage stress and Zero Voltage Switching(ZVS) using resonant auxiliary circuit. And. This paper presents characteristic of $S^4$-PFC converter and effect of circuit parameter of proposed converter through the input inductor, PFC capacitor's variation. All of these theory and characteristic verified through the experiment with a 72W(12V, 6A), $90^{kHz}$ prototype converter.

• Journal of the Korean Institute of Telematics and Electronics
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• v.24 no.5
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• pp.777-785
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• 1987

In this paper, a tightly-coupled multiprocessor system is implemented with four processing elements based on MC68000 CPU, a common menory (128KB), and a single time-shared bus. The multi-tasking operating system, MTOS, is modified so that the multiprocessor system can support multitasking and multiprocessing. The performance of the proposed system is evaluated by stochastic Petri Net system modeling. The efficiency and the processing power are simulated for various load factors and up to 16 PEs. By running benchmark programs, such as quicksort, FFT, and matrix-multiplication, the speed of parallel processing is compared with that of a single processor.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.5
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• pp.1087-1095
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• 2014

A recent major development in computer technology is the advent of the wearable computer system that is based on human-centric interface technology trends and ubiquitous computing environments. Wearable computer systems can use the wireless universal serial bus (WUSB) that refers to USB technology that is merged with WiMedia PHY/MAC technical specifications. In this paper, we focus on an integrated system of the wireless USB over the IEEE 802.15.6 wireless body area networks (WBAN) for wireless wearable computer systems supporting U-health services. And a communication structure that can differentiate QoS of U-health WBAN and WUSB traffic with different priorities is proposed for WUSB over IEEE 802.15.6 hierarchical protocol. In our proposal and performance evaluation, throughputs of U-health WBAN and WUSB traffic are analyzed under single and multiple QoS classes to evaluate the effectiveness of proposed QoS differentiating structure in WUSB over IEEE 802.15.6.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.865-870
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• 2003

A motion controller has been used variously in industry such as semiconductor manufacture equipment, industrial robot, assembly/conveyor line applications and CNC equipment. There are several types of controller in motion control. One of these is a PC-based motion controller such as PCI or ISA, and another is stand-alone motion controller. The PC bus-based motion controller is popular because of improving bus architectures and GUI (Graphic User Interface) that offer convenience of use to user. There are some problems in this. The PC bus-based solution allows for only one of the form factors, so it has a poor flexibility. The overall system package size is bigger than other motion control system. And also, additional axes of control require additional slot, however the number of slots is limited. Furthermore, unwieldy and many wirings come to connect plants or I/O. The stand-alone motion controller has also this limit of axes of control and wiring problems. To resolve these problems, controller must have capability of operating as stand-alone devices that resides outside the computer and it needs network capability to communicate to each motion device. In this paper, a network-based stand-alone motion system is proposed. This system integrates PC and motion controller into one stand-alone motion system, and uses CAN (Controller Area Network) as network protocol. Single board computer that is type of 3.5" FDD form factor is used to reduce the system size and cost. It works with Windows XP Embedded as operating system. This motion system operates by itself or serves as master motion controller that communicates to slave motion controller. The Slave motion controllers can easily connect to master motion system through CAN-network.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.32 no.9
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• pp.315-324
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• 1983

Dynamic stability problems have been experienced with a generator connected to an infinite bus through a long transmission line. Nuclear turbine-generator units #1 and #2 at the Winsconsin Electric Power Point Baech Station were found to be dynamically unstable when one unit is isolated on one of the lines to Milwaukee or when two units are isolaed on the lines to milwaukee. Power System Stabilizers(PSS) were applied to the excitation system to provide stable operation under these conditions. Suitable settings for the PSS were predetetermined analytically by computer method and root licus analysis of an equivalent single machine-infinite bus configuration. This procedure allows graphical approach to the design of power stabilizers and serves as assynthesis procedure when the design constraints are relaxed so the the speed stabilizer is required ro provide animprovement in system damping. A simplified model of the complete exciter generator system is shown to be adequate for this type of analysis.