• 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.

• Biotechnology and Bioprocess Engineering:BBE
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• v.7 no.3
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• pp.171-177
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• 2002

The metabolic flux pattern for L-histidine production was analyzed when glucose and/or acetate were used as carbon sources. Total L-histidine production was enhanced when mixed substrate (glucose and acetate) was used, compared wish that when either glucose or acetate was used as the sole carbon source. Theoretical maximum carbon fluxes through the main pathways for L-histldine production, cell growth, and ATP consumption for cell maintenance were obtained by the linear programming (LP) method. By comparison of the theoretical maximum carbon fluxes tilth actual ones, it was found that a large amount of glucose was actually used for maintenance of cell viability. On the other hand, acetate was used for cell growth. After depletion of acetate in the mixed substrate culture, the flux for glucose to L-histldine synthesis was markedly enhanced. A strategy for effective L-histidine production using both carbon sources was proposed.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.743-746
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• 2005

This paper proposes a novel structure of output buffer circuits for PDP data drivers. The proposed circuit is free from capacitive coupling effect from the output electrode and suppresses the short circuit currents, which improves the current driving capability and reduces the power consumption.

• International journal of advanced smart convergence
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• v.3 no.2
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• pp.14-17
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• 2014

Precision agriculture relies on information technology, whose precondition is providing real-time and accurate information. It depends on various kinds of advanced sensors, such as environmental temperature and humidity, wind speed, light intensity, and other types of sensors. Currently, it is a hot topic how to collect accurate information, the main raw data for agricultural experts, monitored by these sensors timely. Most existing work in WSNs addresses their fundamental challenges, including power supply, limited memory, processing power and communication bandwidth and focuses entirely on their operating system and networking protocol design and implementation. However, it is not easy to find the self-localization capability of wireless sensor networks. Because of constraints on the cost and size of sensors, energy consumption, implementation environment and the deployment of sensors, most sensors do not know their locations. This paper provides maximum likelihood estimators for sensor location estimation when observations are time-of arrival (TOA) range measurement.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.11 no.8
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• pp.338-348
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• 2001

A hybrid self-hearing motor, which Is a functional combination of general permanent magnet (PM) motor and hybrid active magnetic bearing(AMB), was proposed a few years ago. In this paper the hybrid self-bearing motor is modified to a disk type, in which one of two magnetic hearings was substituted for a thin yoke to make the system more compact. An outer rotors in this self-hearing motor is actively controlled only in two radial directions while the ocher motions are passively salable owing to the disk-type structure. Main advantages of the proposed self-hearing motor are simple control mechanism, low power consumption and smart structure. Mathematical model for the magnetic force Is built wish consideration of the radial displacement of the rotor. The model helps us not only to design a levitation controller but also to expect the system performance. Some experimental results show good capability and feasibility of the Proposed self-bearing motor.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.4
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• pp.181-187
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• 2013

Performance of DI diesel engine with high fuel injection method is directly related to its emission characteristics and fuel consumption. In this study, numerical model of 3rd generation piezo-driven injector was designed to analyze the hydraulic performance. Also the injection response characteristics was investigated by using the AMESim simulation code. From this study, it was shown that 3rd generation piezo-driven injector had a faster response and had better control capability due to its hydraulic bypass-circuit that has potential to higher hydraulic characteristics and improved accuracy of injected fuel quantity.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1171-1174
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• 2005

Manufacturing capability at the micro or nano scale production field is requested strongly in view of parts and product miniaturization. Miniaturized parts and products will introduce lots of benefits in terms of high precision functionality and low energy consumption. This paper presents the results of micro milling machine tool development for micro machining process. Finite element analysis has been performed to know the relationship between design dimensional variables and structural stiffness in terms of static, dynamic, thermal aspects. Performance evaluation through machining has been tested and discussed for achievable machining characteristics.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.2
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• pp.146-154
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• 2000

An $H\infty$ controller is designed for active suspensions of vehicles using 7-degree-of-freedom full-car model. Its performance robustness as well as stability robustness to system parameter variations and unmodelled dynamics are assured through the $\mu$-framework. The performance of the $H\infty$ controller is compared with that of a LQC controller in compute simulations. From the simulations it is found that the active suspension with the $H\infty$ controller reduces the acceleration and motion of the sprung mass in the heaving rolling and pitching directions when the car is driven on a normal road or through an asymmetric bump. The suspension stroke and the road holding capability are also improved with a relatively small level of power consumption. Overall the $H\infty$ controller shows a more robust performance than that of the LQG design.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.1137-1142
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• 2004

Walking training is one of the most important rehabilitation processes with paralysis patient. Walking training by using an orthosis can help advancing a patient's independent level. However, existing orthoses have some serious demerit of mechanical problem that the knee joint is locked in the state where it is completely extended, which increases energy consumption and fatigue. For this reason, it is suggested, for more practical orthosis, that the knee joint should be placed and it should have capability of suspending patient's weight. In this paper, 1-DOF walking orthosis which compensates the demerit of the existing orthosis and secures patient's mobility has been proposed. New orthosis has been designed under the following two premises. First, the knee joint of the orthosis was designed fold in order for the orthosis to move in a walking pattern similar to that of a normal person. Second, the knee joint was designed to extend during the swing phase and lock safely during the stance phase.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.4
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• pp.278-287
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• 2009

Plug-in hybrid electric vehicle (PHEV) with capability of being recharged from the power-grid will reduce oil consumption. Also, the PHEV will affect the utility operations by adding additional electricity demand for charging. In this research, the power-grid impact by demand of PHEV charging is presented and the optimal charging control strategy for utility operators is proposed with simulated data. The penetration of PHEV is assumed to be 50% in the circumstances of Korean passenger car market and Korean power-grid market limitedly. To obtain smooth load shape and utilize the surplus electricity in power-grid at midnight and dawn, the peak of charging demand should be controlled to be located before 4:00 a.m., and the time slot which can supply the electricity power to PHEV should be allowed between 1:00 a.m.$\sim$7:00 a.m.