• The KIPS Transactions:PartD
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• v.9D no.4
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• pp.677-686
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• 2002

Recently, the Open-Development-Tool-Environment becomes a basic requirement of RTOS (Real Time Operating System) for embedded systems with restricted memory and CPU power in order to develop applications effectively. A remote interactive shell is one of the basic software components which makes users develop, test and control softwares without burdening target systems. In this paper, we have implemented the remote interactive shell with the following functions : loading object modules, spawning and manipulating tasks facilities thru a remote host. Comparing information reference methods with nonredundant overhead, we have achieved the system with easy maintenance. The shell has been developed with Q-PLUS RTOS under ARM EBSA285 target board and NT host.

• Journal of the Korean Solar Energy Society
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• v.32 no.6
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• pp.106-112
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• 2012

As a fuel cell converts the chemical energy of the fuel cell into electrical energy by electrochemical reaction, the fuel cell system is uniquely integrated technique including fuel processor, fuel cell stack, power conditioning system. The residential fuel cell-PCS(Power Conditioning System) needs to convert efficiently the DC current produced by the fuel cell into AC current using single-phase DC-AC inverter. A single-phase DC-AC inverter has naturally low frequency ripple which is twice frequency of the output current. This low frequency(120Hz) ripple reduces the efficiency of the fuel cell. This paper presents notch filter with IP voltage controller to reject specific 120Hz current ripple in single-phase inverter. The notch filter is designed that suppress just only specific frequency component and no phase delay. Finally, the proposed notch filter design method has been verified with computer simulation and experimentation.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.519-526
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• 2010

The construction site for $\bigcirc\bigcirc$ transformer substation was located at a mountain valley. In order to prepare the site, the valley was first filled with crushed rock debris up to 63m. Since the main concern of this project is to minimize differential settlement of the foundation of transformer facilities, dynamic compaction was performed every 7m followed by reinforcement with EMP(Ez-Mud Piling). The EMP is one of bored piling methods, in which a hole is bored by means of air percussion and maintain by injecting Ez-Mud. Then a PHC pile (Pretensioned spun High strength Concrete pile) is embedded and finalized with a hammer. In this study, bearing capacities and long term behavior of a pile installed by EMP were investigated. To achieve these objectives, a series of tests such as static and dynamic load tests were conducted. In addition, a construction quality control standard was proposed based on the test results.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.3
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• pp.580-585
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• 2009

Real Time Locating Systems (RTLS) are used to track and identify the location of objects in real time using simple, inexpensive tags attached to or embedded in objects and readers that receive the wireless signals from these tags to determine their locations. A tag is powered an internal source such as a battery. The blink frequency of a tag affects the energy efficiency and the locating accuracy of RTLS. The mobility of a tag also affects the locating accuracy. In this paper, we introduce a RTLS tag design which improves the locating accuracy and the power efficiency. We propose an adaptive transmission-rate control algorithm using a motion sensor. By analyzing the signal pattern of the motion sensor, we can build a model to estimate the speed of the motion. Using this model, our algorithm can achieve better locating accuracy and lower power consumption than those of the conventional method. In our experiments, the number of transmission reduced as 40%, keeping similar locating accuracy.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.7
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• pp.949-955
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• 2018

Hardware-in-the-loop (HIL) simulation is a technique that can be employed for developing and testing complex real-time embedded systems. HIL simulation provides an effective platform for verifying power management system (PMS) performance of liquefied natural gas carriers, which are high value-added vessels such as offshore plants. However, HIL tests conducted by research institutes, including domestic shipyards, can be protracted. To address the said issue, this study proposes a field programmable gate array (FPGA) based PMS-HIL simulator that comprises a power supply, consumer, control console, and main switchboard. The proposed HIL simulation platform incorporated actual equipment data while conducting load sharing PMS tests. The proposed system was verified through symmetric, asymmetric, and fixed load sharing tests. The proposed system can thus potentially replace the standard factory acceptance tests. Furthermore, the proposed simulator can be helpful in developing additional systems for vessel automation and autonomous operation, including the development of energy management systems.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.7
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• pp.52-60
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• 2010

In this paper, we propose a dynamic power management framework for multi-core systems. We reduced the power consumption of multi-core processors such as Intel Centrino Duo and ARM11 MPCore, which have been used at the consumer electronics and personal computer market. Each processor uses a different technique to save its power usage, but there is no embedded multi-core processor which has a precise power control mechanism such as dynamic voltage scaling technique. The proposed dynamic power management framework is suitable for smart phones which have an operating system to provide multi-processing capability. Basically, our framework follows an intuitive idea that reducing the power consumption of idle cores is the most effective way to save the overall power consumption of a multi-core processor. We could minimize the energy consumption used by idle cores with application-targeted policies that reflect the characteristics of active workloads. We defined some properties of an application to analyze the performance requirement in real time and automated the management process to verify the result quickly. We tested the proposed framework with popular processors such as Intel Centrino Duo and ARM11 MPCore, and were able to find that our framework dynamically reduced the power consumption of multi-core processors and satisfied the performance requirement of each program.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.41 no.1
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• pp.25-32
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• 2004

Nowadays image processing is very useful for some field of traffic applications. The one reason is we can construct the system in a low price, the other is the improvement of hardware processing power, it can be more fast to processing the data. In traffic field, the development of image using system is interesting issue. Because it has the advantage of price of installation and it does not obstruct traffic during the installation. In this study, 1 propose the traffic monitoring system that implement on the embedded system environment. The whole system consists of two main part, one is host controller board, the other is image processing board. The part of host controller board take charge of control the total system interface of external environment, and OSD(On screen display). The part of image processing board takes charge of image input and output using video encoder and decoder, Image classification and memory control of using FPGA, control of mouse signal. And finally, for stable operation of host controller board, uC/OS-II operating system is ported on the board.

• Journal of Periodontal and Implant Science
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• v.32 no.2
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• pp.315-324
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• 2002

The purpose of this in vitro study was to evaluate the efficiency of Er:YAG laser on calculus removal and the morphologic changes and hardness of the irradiated surface at different power settings. This experiment used human teeth which were extracted due to periodontal disease and had a band of calculus. Forty root slabs ($5{\times}5mm$) were made and divided into control group and irradiated groups. Experimental groups were as follows; Control group (root planing), Group1 (irradiated with laser at 30mJ), Group2 (irradiated with laser at 60mJ), Group3 (irradiated with laser at 100mJ). Twelve root slab embedded in resin block were used in each group. Er:YAG laser was applied under water irrigation with the tip held perpendicular to the root surface in contact mode. The treatment time was measured until the calculus was removed completely under naked eyes. The efficiency of calculus removal was evaluated by the time for removal. Morphological changes of laser irradiated site were observed under SEM and the surface hardness was measured using a VH tester. The results were as follows; 1. The efficiency of laser scaling was increased with increasing the energy level of irradiation(p<0.05). 2. The morphological changes such as carbonization, crater and scale-like defects in the irradiated root surface were frequently observed with increasing the energy level. 3. The surface hardness tended to increase at 60mJ and 100mJ irradiated groups than that of control group. From the results evaluting on the efficiency, morphological change and surface hardness, lower energy level was suggested for the clinical application of the Er:YAG laser in scaling.

• Journal of Biosystems Engineering
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• v.38 no.4
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• pp.255-263
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• 2013

Purpose: It is not easy to drive a rice-transplanter avoiding underlapped or overlapped transplanting in paddy fields. An automated guidance system for the riding-type rice-transplanter would be necessary to operate the rice-transplanter autonomously or to assist the beginning drivers as a driving aid. Methods: A prototype of guidance system was composed of embedded computers, RTK-GPS, and a power-steering mechanism. Two Kalman filters were adopted to overcome sparse positioning data (1 Hz) from the RTK-GPS. A global Kalman filter estimated the posture of rice-transplanter every one second, and a local Kalman filter calculated the posture from every new estimation of the global Kalman filter with an interval of 200 ms. A PID controller was applied to the row-following mode control. A control method of U-turning mode was developed as well. A stepping motor with a reduction gear set was used to rotate the shaft of steering wheel. Results: Test trials for U-turning and row-following modes were done in a paddy field after some parameters have been tuned at the ground speed range of 0.3 ~ 1.2 m/s. The minimum RMS error of offset was 3.13 cm at the ground speed of 0.3 m/s while the maximum RMS error was 13.01 cm at 1.2 m/s. The offset RMS error tended to increase as the ground speed increased. The target point distance, LT also affected the system performance and PID controller parameters should be adjusted on different ground speeds. Conclusions: A target angle-based PID controller plus stationary steering angle controller made it possible for the rice-transplanter to steer autonomously by following a reference line accurately and even on U-turning mode. However, as condition in paddy fields is very complicated, the system should control the ground speed that prevents it from deviating too much due to ditch and slope.

• Journal of the Korea Society of Computer and Information
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• v.12 no.5
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• pp.103-112
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• 2007

In this paper, we implement a hypervisor that runs multiple uC/OS-II real-time kernels on one microprocessor. The hypervisor virtualizes microprocessor and memory that are main resources managed by uC/OS-II kernel. Microprocessor is virtualized by controlling interrupts that uC/OS-II real-time kernel handles and memory is virtualized by partitioning physical memory. The hypervisor consists of three components: interrupt control routines that virtualize timer interrupt and software interrupt, a startup code that initializes the hypervisor and uC/OS-II kernels, and an API that provides communication between two kernels. The original uC/OS-II kernel needs to be modified slightly in source-code level to run on the hypervisor. We performed a real-time test and an independent computation test on Jupiter 32-bit EISC microprocessor and showed that the virtualized kernels run without problem. The result of our research can reduce the hardware cost, the system space and weight, and system power consumption when the hypervisor is applied in embedded applications that require many embedded microprocessors.