• Journal of the Korean Institute of Gas
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• v.24 no.6
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• pp.28-33
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• 2020

In this study the possibility of hydrogen as a fuel in a small-sized two-stroke SI (Spark ignition) engine was investigated. For this purpose, experimental setup including an engine, a dynamometer, equipments for hydrogen and lubricant oil supply was prepared. And then preliminary experiments for the hydrogen-fueled engine combustion were conducted. In the case of hydrogen-fueled engines comparing to gasoline backfire occurs when the excess air ratio is lower than a specific value. This can cause engine power reduction and damage to the engine parts. The engine was controlled to operate at lean conditions to prevent backfire. Through the control of excess air ratio, the maximum engine brake power output of 3 kW was achieved in a 210 cc engine, while it was 6 kW in case of gasoline fuel.

• The Journal of Korean Institute of Information Technology
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• v.17 no.5
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• pp.47-55
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• 2019

As the damage caused by GPS jamming has been increased, researches for detecting and preventing GPS jamming is being actively studied. This paper deals with a GPS jamming detection method using multiple GPS receiving channels and three-types machine learning techniques. Proposed multiple GPS channels consist of commercial GPS receiver with no anti-jamming function, receiver with just anti-noise jamming function and receiver with anti-noise and anti-spoofing jamming function. This system enables user to identify the characteristics of the jamming signals by comparing the coordinates received at each receiver. In this paper, The five types of jamming signals with different signal characteristics were entered to the system and three kinds of machine learning methods(AB: Adaptive Boosting, SVM: Support Vector Machine, DT: Decision Tree) were applied to perform jamming detection test. The results showed that the DT technique has the best performance with a detection rate of 96.9% when the single machine learning technique was applied. And it is confirmed that DT technique is more effective for GPS jamming detection than the binary classifier techniques because it has low ambiguity and simple hardware. It was also confirmed that SVM could be used only if additional solutions to ambiguity problem are applied.

• Journal of KIISE:Computing Practices and Letters
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• v.9 no.1
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• pp.95-99
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• 2003

In addition to wired communication technology, wireless communication technology has had communication revolution nowadays. Bluethooth technology carries out data/voice communication within pico-net. Nowadays the various services are supported by access network connected to public network. This paper presents implementation of bluetooth protocol analyser which simulates bluetooth protocol. MS window98 and visual C are used for development environment and application program is operated over the firmware loaded on the bluetooth device connected to the PC through UART which of the maximum transmission rate is 115kbps because transmission rate less than 20kbps affects rarely the performance. The performance analysis on the propose system is carried out as simulating the signalling information for the voice test and the traffics between two bluetooth systems for file transfer. The throughput analysis for file transfer service and call processing capacity for voice service are considered as performance analysis parameters. File access time is very important parameter and throughput is 13 kbps in case breakpoint time to file access is 0.04sec. Also call processing time is about 16.6ms in case of communication with the headset. The performance analysis of simulation results satisfies with bluetooth device development.

• Aerospace Engineering and Technology
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• v.6 no.2
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• pp.40-44
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• 2007

Based on the optical design type, the large aperture payload has not only a different characteristic of design, assembly and alignment but also its own merits and demerits. The analysis of characteristic has been performed according to the optical design type and based on this result, our camera is 4 reflective mirror system based on the Korsch type. Each mirror assembly is to be verified in the mirror manufacturer and the Optical Module(OM) will be assembled, aligned and tested by KARI. The final performance of camera depends on the several factors, especially, the optical performance of its OM In parallel with the optical design the conceptual design of OM assembly and alignment has been performed. In this paper, the analysis of characteristic has been performed according to the optical design type and the conceptual design of OM assembly and alignment was described with regard to optical performance.

• Journal of the Korean Society for Railway
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• v.14 no.6
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• pp.507-514
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• 2011

Recently, we developed a new subway train with many cooperative companies. The main controller of the subway train is Control and Monitoring System (TCMS), so we conducted requirement analysis of TCMS considering system performance, easy maintenance and service oriented flexibility. Hence, we adopted new bus architecture and QNX as a Real-time Operating System (RTOS) and developed hardware systems. The functions of TCMS are employed into two computers, service computer and control/monitor computer, to increase on their performance and to yield easy maintenance and to satisfy customer needs. The TCMS controls and monitors control devices equipped in the train through various protocols which are implemented in hardware. In order to evaluate the performance of the system and to satisfy reliability, various experiments including EMC/ECI were performed. Now the TCMS is installed on the newly developed train and is under performance evaluation through test driving.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.11
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• pp.187-192
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• 2014

Various researches are performed to extract significant features from continuous images. The FAST algorithm has the simple structure for arithmetic operation and it is easy to extraction the features in real time. For this reason, the FPGA based hardware accelerator is implemented and widely applied for the FAST algorithm. The hardware accelerator needs the threshold to extract the features from images. The threshold is influenced not only the number of extracted features but also the total execution time. Therefore, the way of threshold control is important to stabilize the total execution time and to extract features as much as possible. In order to control the threshold, this paper proposes the PI controller. The function and performance for the proposed PI controller are verified by using test images and the PI control logic is designed based on Xilinx Vertex IV FPGA. The proposed scheme can be implemented by adding 47 Flip Flops, 146 LUTs, and 91 Slices to the FAST hardware accelerator. This proposed approach only occupies 2.1% of Flip Flop, 4.4% of LUTs, and 4.5% of Slices and can be regarded as a small portion of hardware cost.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.2
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• pp.154-161
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• 2013

This paper presents the signal-to-interference plus noise ratio (SINR) estimation of IEEE 802.16m WirelessMAN-Advanced mobile station with simulation and implementation results. The downlink signal of IEEE 802.16m has two kinds of A-Preambles: the PA-preamble and the SA-preamble. This paper proposes the efficient method of estimating SINR with A-Preambles, by measuring noise power from PA-preamble and measuring interference power and signal power from SA-preamble. The proposed SINR measurement block contains important features such as subcarrier phase rotation elimination and simplified dB transform. The result of this paper is integrated to ETRI's IEEE 802.16m test mobile station, used for decision of adaptive-modulation-and-coding (AMC) and hand-over. It showed good measurement performance in simulation and unified system link test also.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.10
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• pp.940-947
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• 2007

For the performance upgrade of a supersonic jet fighter, the processor and FLCC(Flight Control Computer) Architecture were upgraded from a baseline FLCC. Prior to the hardware implementation phase, the exact CPU throughput estimation is necessary. For this purpose, an experimental method for new FLCC throughput estimation was introduced in this study.　While baseline FLCC operating, the CPU address bus was collected with logic analyzer, and then decoded to get the exact access times to each memory-memory and the number of program Instruction branches. Based on these data, a throughput test in CPU demo-board of the new FLCC configuration was performed. From test results, the CPU-Memory architecture was design-changed before FLCC hardware implementation phase. To check the flight stability degradation due to power-interrupt problem due to CPU-Memory architecture change, the piloted HILS (Hardware-In-the Loop Simulator) test was conducted.

• The Transactions of the Korean Institute of Power Electronics
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• v.12 no.1
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• pp.89-97
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• 2007

This paper describes a load simulator with power recovery capability, which is based on the voltage source converter-inverter set. The load simulator can save the electric energy that should be consumed to test the operation and performance of the power quality compensator and the power equipment. The load simulator consists of a converter-inverter set with a DSP controller for system control and PWM pulse generation. The converter operates as a universal load to model the linear load and the non-linear load, while the inverter feed the energy back to the power source with harmonic compensation. the performance of proposed load simulator was analyzed with scaled-model experiment, interconnected with the active power filter. The experimental results confirms that the proposed load simulator can be utilized to test the performance of active power filter.

• Journal of Satellite, Information and Communications
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• v.11 no.4
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• pp.15-20
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• 2016

In this paper, we developed the hardware GPS signal generator for generating a GPS L1 meaconing signal with Live GPS signal signals and analyzed the performance of meaconing signal generator thorough the experiment. Deception of the signal, such as a re-broadcast, it is an object of the user to provide false information so as not to receive location information and accurate time. The signal just rebroadcast has the features that can be easily deceive the receiver via a delay of no received signal to the signal processing through an antenna. In this paper, the hardware for generating a signal only these rebroadcast designed and manufactured, by re-sending the received Live GPS signals, to confirm the effect of the receiver. The maximum delay time is possible up to about 2.6msec, also, has been successfully tested to be moved to the position of re-broadcasting based on maturity antenna the position of the receiver through a spaced antenna.