• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.729-734
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• 2005

One of the important research issues in mobile robot is how to detect the 3D environment fast and accurately, and recognize it. Sensing methods of utilizing laser structured light and/or stereo vision are representatively used among a number of methodologies developed to date. However, the methods are still in need of achieving high accuracy and reliability to be used for real world environments. In this paper to implement a new robotic environmental sensing algorithm is presented by combining the information between intensity image and that of laser structured light image. To see how effectively the algorithm applied to real environments, we developed a sensor system that can be mounted on a mobile robot and tested performance for a series of environments.

• Proceedings of the KIPE Conference
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• 2006.06a
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• pp.485-487
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• 2006

Speed and torque controls of permanent magnet synchronous motors are usually attained by the application of position and speed sensors. However, speed and position sensors require the additional mounting space, reduce the reliability in harsh environments and increase the cost of a motor. Therefore, many studies have been performed for the elimination of speed and position sensors. This paper investigates an Improved sliding mode observer for the speed sensorless control of a permanent magnet synchronous motor. The proposed control strategy is the sliding mode observer with a variable boundary layer for a low-chattering and fast-reponse control. The proposed algorithm is verified through the simulation and experimentation.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.9
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• pp.1552-1554
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• 2008

Recently, sensorless induction motor drives have been much studied due to several advantages. Sensorless drives eliminate the additional mounting space, increase the reliability in harsh environments, and reduce the cost of a motor. This paper investigates an improved sliding mode observer for the sensorless speed control of an induction motor. The proposed control strategy is the sliding mode observer with a variable boundary layer for a low-chattering and fast-response control. The proposed sensorless-algorithm is verified through the simulation and experimentation.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.11
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• pp.687-690
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• 2004

Many studies have been performed for the elimination of speed and position sensors which require the additional mounting space, reduce the reliability in harsh environments and increase the cost of a motor. This paper investigates an improved sliding mode observer for the sensorless speed control of a permanent magnet synchronous motor. The proposed control strategy is the sliding mode observer with a variable boundary layer for a low-chattering and fast-response control. The proposed algorithm is verified through the simulation and experimentation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.10a
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• pp.424-429
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• 2013

The trolley carrying the pod moves along by the airfield runway. The pod through the trolley are subjected to vibration arising from the ground state, the precision optical components in the pod can have a significant impact. The road tests were conducted by using the measurement pod to remove the risk for the project. The measurement pod was composed with the ACRA, sensors, battery. The accelerometers were attached to get the acceleration through the road condition. The PSD envelop was calculated by FFT from the acceleration. The driving safety was proven through comparing the measurement data and MIL-STD-810G specification.

• Journal of Positioning, Navigation, and Timing
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• v.9 no.4
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• pp.387-395
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• 2020

Accuracy of an integrated Global Positioning System (GPS) / Inertial Navigation System (INS) relies heavily on the visibility of GPS satellites. Especially, its accuracy is dramatically degraded in urban canyon due to signal obstructions due to large structures. In this paper, we propose a new integrated positioning system that effectively combines INS, GPS, ultrasonic sensor, and barometer in GPS-denied environments. In the proposed system, the ultrasonic sensor provides velocity information along the forward direction of moving vehicle. The barometer output provides height information compensated for the pressure variation due to fast vehicle movements. To evaluate the performance of the proposed system, an experiment was carried out by mounting the proposed system on a test car. By the experiment result, it was confirmed that the proposed system bears good potential to maintain positioning accuracy in harsh urban environments.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.12
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• pp.8350-8356
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• 2015

The demand for user convenient devices in automotive applications are fast growing, mainly driven by the customer's requirement for higher efficiency and more features. In important such feature is the cold module for cars, which are convenient luxuries that warm or cool drinks placed in the cup holder by means of a thermoelectric element. In present study, we would like to find out the optimal thickness of the cup holder and mounting position of the thermoelectric element through experiments under various testing conditions and thermal analysis. The resulting thermal distribution of the primary area of thermal analysis was found to be lowest when the thickness was 2.5 mm. The temperature distribution was also lowest when the thermal element was positioned underneath the holder (A-type).

• IEMEK Journal of Embedded Systems and Applications
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• v.13 no.5
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• pp.235-243
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• 2018

NAND flash memory has been widely used for embedded systems as storage device and the flash memory file systems such as JFFS2, YAFFS/YAFFS2 have been adopted by these embedded systems. The flash memory file systems provide the high performance and overcome the limitations of flash memory. However, these file systems don't solve the slow mount time problem when a sudden power failure happens. In this paper, we proposed a flash memory management method for enhancing the recovery performance. The proposed method manages the flash memory block type and stores the block type information at recovery image block. When file operations are occurred, our method stores the file information at the metadata block before and after the file operation. When mounting the flash memory, our method only scans the recovery image blocks and metadata blocks. The proposed method reduces the mount time by seeking the metadata block locations fast by using the recovery image blocks. We implemented the proposed method and evaluation results show that our method reduces the mount time 13 ~ 46 % compared with YAFFS2.

• Journal of the Korea Society of Computer and Information
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• v.8 no.1
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• pp.97-102
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• 2003

In this paper it Is to suggest that beyond the Previous communication concept of exchange, transmission mounting. and terminal , the call control system function should be added to the call control exchange server, to make an external telephone call available through the internet by connecting the interior line and the Internet. The function evaluation of call control system is found to become stable when the callers are 10 rather than 20 above, as a result of the more than ten times repeated concurrent calls. Furthermore, the evaluation shows that the program responds Quickly within a second, even when there are more than 100 callers as well as secures a stable system operation and mutual inter-feasibility due to a fast connectivity and a superb function.

• Journal of KIISE:Computer Systems and Theory
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• v.35 no.11
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• pp.497-508
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• 2008

Mobile Multimedia File System, MNFS, is a file system which extensively exploits NAND FLASH Memory, Since general Flash file systems does not precisely meet the criteria of mobile devices such as MP3 Player, PMP, Digital Camcorder, MNFS is designed to guarantee the optimal performance of FLASH Memory file system. Among many features MNFS provides, there are three distinguishable characteristics. MNFS guarantees, first, constant response time in sequential write requests of the file system, second, fast file system mounting time, and lastly least memory footprint. MNFS implements four schemes to provide such features, Hybrid mapping scheme to map file system metadata and user data, manipulation of user data allocation to fit allocation unit of file data into allocation unit of NAND FLASH Memory, iBAT (in core only Block Allocation Table) to minimize the metadata, and bottom-up representation of directory. Prototype implementation of MNFS was tested and measured its performance on ARM9 processor and 1Gbit NAND FLASH Memory environment. Its performance was compared with YAFFS, NAND FLASH File system, and FAT file system which use FTL. This enables to observe constant request time for sequential write request. It shows 30 times faster mounting time to YAFFS, and reduces 95% of HEAP memory consumption compared to YAFFS.