• Journal of Korean Society of Transportation
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• v.31 no.5
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• pp.60-70
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• 2013

This study aims to develop a truck priority on left-turn algorithm that can reduce greenhouse gas emissions by reducing heavy duty truck's stops at signalized intersection. The signal priority is granted for a left-turn phase, because heavy duty trucks can deteriorate left-turn traffic flow due to the low acceleration or deceleration rate and large turn radius. Truck priority allows to provide the stable speed control for heavy duty truck, and reduces emissions at the signal intersection. Also, two signal recovery strategies are compared for various traffic conditions. This study analyzes the effectiveness of truck priority such as greenhouse gas emissions and fuel consumption reduction, and total travel time saving using the PARAMICS and Comprehensive Modal Emissions Model (CMEM). The results show that signal priority for heavy duty trucks has an effect on reducing greenhouse gas emissions and fuel consumptions at non-peak hour. Also, it shows decreasing total travel time due to reducing truck stops.

• Journal of Intelligence and Information Systems
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• v.29 no.3
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• pp.249-265
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• 2023

Recently, the satellite industry has been paying attention to the private-led 'New Space' paradigm, which is a departure from the traditional government-led industry. The space industry, which is considered to be the next food industry, is still receiving relatively little attention in Korea compared to the global market. Therefore, the purpose of this study is to explore future signals that can help determine the market entry strategies of private companies in the domestic satellite industry. To this end, this study utilizes the theoretical background of future signal theory and the Keyword Portfolio Map method to analyze keyword potential in patent document data based on keyword growth rate and keyword occurrence frequency. In addition, news data was collected to categorize future signals into first symptom and early information, respectively. This is utilized as an interpretive indicator of how the keywords reveal their actual potential outside of patent documents. This study describes the process of data collection and analysis to explore future signals and traces the evolution of each keyword in the collected documents from a weak signal to a strong signal by specifically visualizing how it can be used through the visualization of keyword maps. The process of this research can contribute to the methodological contribution and expansion of the scope of existing research on future signals, and the results can contribute to the establishment of new industry planning and research directions in the satellite industry.

• Journal of information and communication convergence engineering
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• v.4 no.4
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• pp.170-173
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• 2006

Recently, with increasing efficiency of DSC (photo-electrochemical using a nano-particle), The Performance of DSC solar generation system also needs improvement. The approach consists of a Fly-back DC-DC (transfer ratio 1:10) converter to boost the DSC cell voltage to 300VDC. The four switch (MOSFET) inverter is employed to produce 220V, 60Hz AC outputs. High performance, easy manufacturability, lower component count., safety and cost are addressed. Protection and diagnostic features form an important part of the design. Another highlight of the proposed design is the control strategy, which allows the inverter to adapt to the: requirements of the load as well as the power source. A unique aspect of the design is the use of the DSP TMS320LF2406 to control the inverter by current and voltage feed-back. Efficient and smooth control of the: power drawn from the DSC Cell is achieved by controlling the front end DC-DC converter in current mode.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.5B no.2
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• pp.189-195
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• 2005

This paper presents a new velocity estimation strategy for a non-salient permanent magnet synchronous motor drive without high frequency signal injection or special PWM pattern. This approach is based on the d-axis current regulator output voltage of the drive system, which contains the rotor position error information. The rotor velocity can be estimated through a rotor position tracking PI controller that controls the position error at zero. For zero and low speed operation, the PI gain of the rotor position tracking controller has a variable structure according to the estimated rotor velocity. Then, at zero speed, the rotor position and velocity have sluggish dynamics because the varying gains are very low in this region. In order to boost the bandwidth of the PI controller during zero speed, the loop recovery technique is applied to the control system. The PI tuning formulas are also derived by analyzing this control system by frequency domain specifications such as phase margin and bandwidth assignment.

• ETRI Journal
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• v.36 no.5
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• pp.808-818
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• 2014

To deal with the major challenges of embedded sensor networks, we consider the use of magnetic fields as a means of reliably transferring both information and power to embedded sensors. We focus on a power allocation strategy for an orthogonal frequency-division multiplexing system to maximize the transferred power under the required information capacity and total available power constraints. First, we consider the case of a co-receiver, where information and power can be extracted from the same signal. In this case, we find an optimal power allocation (OPA) and provide the upper bound of achievable transferred power and capacity pairs. However, the exact calculation of the OPA is computationally complex. Thus, we propose a low-complexity power reallocation algorithm. For practical consideration, we consider the case of a separated receiver (where information and power are transferred separately through different resources) and propose two heuristic power allocation algorithms. Through simulations using the Agilent Advanced Design System and Ansoft High Frequency Structure Simulator, we validate the magnetic-inductive channel characteristic. In addition, we show the performances of the proposed algorithms by providing achievable ${\eta}$-C regions.

• ETRI Journal
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• v.26 no.6
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• pp.565-574
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• 2004

Differential unitary space-time modulation (DUSTM) has emerged as a promising technique to obtain spatial diversity without intractable channel estimation. This paper presents a study of the application of DUSTM on multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) systems with frequency-selective fading channels. From the view of a correlation analysis between subcarriers of OFDM, we obtain the maximum achievable diversity of DUSTM on MIMO-OFDM systems. Moreover, an efficient implementation strategy based on subcarrier reconstruction is proposed, which transmits all the signals of one signal matrix in one OFDM transmission and performs differential processing between two adjacent OFDM blocks. The proposed method is capable of obtaining both spatial and multipath diversity while reducing the effect of time variation of channels to a minimum. The performance improvement is confirmed by simulation results.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.936-941
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• 2004

An Optimal Feedforward Integral Variable Structure or FIVSC approach for an electrohydraulic position servo control system is presented in this paper. The FIVSC algorithm combines feedforward strategy and integral in the conventional Variable Structure Control (VSC) and calculating the control function to guarantee the existence of a sliding mode. Furthermore, the chattering in the control signal is suppressed by replacing the sign function in the control function with a smoothing function. The simulation results illustrate that the purposed approach gives a significant improvement on the tracking performances when compared with some existing control methods, like the IVSC and MIVSC strategies. Simulation results illustrate that the purposed approach can achieve a zero steady state error for ramp input and has an optimal motion with respect to a quadratic performance index. Moreover, Its can achieve accurate servo tracking in the presence of plant parameter variation and external load disturbances.

• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.65-68
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• 2000

In CDMA, the currently used PN code acquisition methods detect the phase of the incoming PN signal on the basis of ML estimation. In serial search strategy, it takes relatively long time for PN code acquisition. A study related to reduce processing time of PN code acquisition is important. Therefore we propose a reference code design for a new algorithm that a reference code and the received PN code are fully correlated to detect the transmitted PN code, in detail, the relative phase offset j of c⒡. After choosing two weight factors, we show the mathematical analysis and derivation for the reference code design.

• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.521-522
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• 2016

This paper presents a novel scheme to estimate the rotor position of a single-phase hybrid switched reluctance motor (HSRM). The proposed method uses the differential of back-EMF within a position region to estimate rotor position. By detecting the crossing-zero signal of back-EMF differential value, the minimum position of back-EMF corresponding to an absolute rotor position can be captured and used for position estimation four times in every mechanical rotation. In this way, a sensorless operation with adjustable turn on/off angle can be achieved without substantial computation. For the starting, two current comparators are adopted. The experimental verification using a prototype drive system is provided to demonstrate the viability of the proposed sensorless scheme.

• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.166-170
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• 1997

A Single phase induction motor is the predominant fractional horsepower power rated, extensively used in domestic and industrial application. For example, these motors provide the motive power to washing machines, fans, refrigerators, etc. In this paper, single phase induction motor input current was detected by a small current transformer and determined TRIAC gate signal by using op-amp analog circuit. The soft-start strategy is based on limited auxiliary current angle during starting period in the closed-loop control. The Simulation and experimental result show the motor's starting characteristics of the proposal starting system and are compared with centrifugal switch starting motor.