• Journal of Korean Society of Industrial and Systems Engineering
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• v.32 no.1
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• pp.34-43
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• 2009

In this thesis, we explain developing processes of the power transmission system for lift truck. Conventional power transmission system had some problems such as spatial constraints or low speed and high torque problem. Because conventional power transmission system was mainly designed for high speed vehicles. In this paper we developed power shift drive axle specialized for $2.0{\sim}3.5$ ton lift truck. Innovative structure of transmission which is built in inside axle, enables to reduce system weight and size by 40% compared to the conventional power transmission system. Also, it is possible to do additional functions such as auto parking system and anti-roll back system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.6C
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• pp.603-613
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• 2006

Low-power design is one of the most important challenges encountered in maximizing battery life in portable devices as well as saving energy during system operation. In this paper we propose a low-power DCT (Discrete Cosine Transform) architecture using a modified Computation Sharing Multiplication (CSHM). The overall rate of Power consumption is reduced during DCT: the proposed architecture does not perform arithmetic operations on unnecessary bits during the Computation Sharing Multiplication calculations. Experimental results show that it is possible to reduce power dissipation up to about $7\sim8%$ without compromising the final DCT results. The proposed low-power DCT architecture can be applied to consumer electronics as well as portable multimedia systems requiring high throughput and low-power.

• The Transactions of the Korean Institute of Power Electronics
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• v.8 no.6
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• pp.569-575
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• 2003

This paper present a new fully-automated PC-based instrumental system that could quickly measure and analyze the efficiency of switching power supplies for the entire operating range. In the proposed system, we applied an Indirect method for high-voltage low-current measurements and a direct method for low-voltage high-current measurements, in order to obtain a high accuracy with minimum equipment requirement. Compared to the conventional methods, the newly proposed system offers more accurate and much faster real-time assessment of the efficiency with minimum measurement error. The performance and accuracy of the proposed system are verified using a 50 W switching power supply intended for telecommunication applications.

• Proceedings of the KIEE Conference
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• 1999.07f
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• pp.2568-2571
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• 1999

Recently, new trend in telecommunication device is to apply low voltage, about 3.3V-1.5V. However, it is undesirable in view of high efficiency and power desity which is the most important requirement in the distributed power system. Rectification loss in the output stage in on-board converter for distributed power system are constrained to obtain high efficience at low output voltage power suppies. This paper is investigated conduction power loss in synchronouss rectifier with a parallel -connected Schottky Barrier Diode(SBD). Conduction losses are calculated for both MOSFET and SBD respectively. The SBD conduction power loss dissipates more than the MOSFET rectifier conduction power loss.

• Journal of Sensor Science and Technology
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• v.32 no.2
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• pp.105-109
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• 2023

In this study, we present a power-efficient driving method for gas sensor systems based on the analysis of input signal characteristics. The analysis of the gas sensor output signal characteristics in the frequency domain shows that most of the signal portions are distributed in a relatively low frequency region when extracting the gas sensor signal, which can lead to further performance improvement of the gas sensor system. Therefore, the proposed gas signal extracting technique changes the operating frequency of the read-out circuit based on the frequency characteristics of the output signal of the gas sensor, resulting in a reduction of power consumption at the whole system level. The proposed sensing technique, which can be applied to a general-purpose commercial gas sensor system, was implemented in a printed circuit board (PCB) to verify its effectiveness at the commercial level.

• The Journal of the Acoustical Society of Korea
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• v.43 no.5
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• pp.584-591
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• 2024

This paper investigates the reduction of low-frequency noise emitted from the machine room of a built-in refrigerator using perforated plate system composed of perforated panels and sound-absorbing materials. The study employs theoretical methods, Finite Element Analysis (FEA), and impedance tube experiments to compare and analyze absorption characteristics across different shapes of perforated panels, aiming to propose an optimal configuration. Simulation of radiated sound power levels demonstrates a decrease in the low-frequency band of the Sound Power Level (PWL) upon implementing perforated plate system. Experimental noise tests conducted in a semi-anechoic chamber validate the effectiveness of the perforated plate system.

• Smart Structures and Systems
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• v.6 no.5_6
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• pp.689-709
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• 2010

In this paper, a low cost, low power but multifunctional wireless sensor node is presented for the impedance-based SHM using piezoelectric sensors. Firstly, a miniaturized impedance measuring chip device is utilized for low cost and low power structural excitation/sensing. Then, structural damage detection/sensor self-diagnosis algorithms are embedded on the on-board microcontroller. This sensor node uses the power harvested from the solar energy to measure and analyze the impedance data. Simultaneously it monitors temperature on the structure near the piezoelectric sensor and battery power consumption. The wireless sensor node is based on the TinyOS platform for operation, and users can take MATLAB$^{(R)}$ interface for the control of the sensor node through serial communication. In order to validate the performance of this multifunctional wireless impedance sensor node, a series of experimental studies have been carried out for detecting loose bolts and crack damages on lab-scale steel structural members as well as on real steel bridge and building structures. It has been found that the proposed sensor nodes can be effectively used for local wireless health monitoring of structural components and for constructing a low-cost and multifunctional SHM system as "place and forget" wireless sensors.

• Journal of Power Electronics
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• v.16 no.6
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• pp.2243-2257
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• 2016

This paper presents a two stage three-phase proton exchange membrane fuel cell (PEMFC) generation system. When the system is connected to a three-phase load, it is very sensitive to the characteristics and type of the load. Especially unbalanced three-phase loads, which result in a pulsating power that is twice the output frequency at the inverter output, and cause the dc-link to generate low frequency ripples. This penetrates to the fuel cell side through the front-end dc-dc converter, which makes the fuel cell work in an unsafe condition and degrades its lifespan. In this paper, the generation and propagation mechanism of low frequency ripple is analyzed and its impact on fuel cells is presented based on the PEMFC output characteristics model. Then a novel method to evaluate low frequency current ripple control capability is investigated. Moreover, a control scheme with bandpass filter inserted into the current feed-forward path, and ripple duty ratio compensation based on current mode control with notch filter is also proposed to achieve low frequency ripple suppression and dynamic characteristics improvement during load transients. Finally, different control methods are verified and compared by simulation and experimental results.

• Proceedings of the KIEE Conference
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• 1999.07f
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• pp.2647-2649
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• 1999

Electric power system is consisted of power supply and power enable circuit. Power supply provides operating voltage with internal chip. Depending on the operating voltage, power enable circuit provides operating signal, PWREN. Because energy is obtained from signal of external station, passive transponder must have the low power consumption. In this paper, the power supply module of the low power transponder is designed and analyzed.

• Proceedings of the IEEK Conference
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• 2002.06b
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• pp.101-104
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• 2002

This paper propose that is algorithm of power dissipation reduction in the high level synthesis design for DSP(Digital Signal Processor), as the portable terminal system recently demand high power dissipation. This paper obtain effect of power dissipation reduction and switching activity that increase correlation of operands as input data of function unit. The algorithm search loop or repeatedly data to the input operands of function unit. That can be reduce the power dissipation using the new low power high level synthesis algorithm. In this Paper, scheduling operation search same nodes from input DFG(Data Flow Graph) with correlation coefficient of first input node and among nodes. Function units consist a multiplier, an adder and a register. The power estimation method is added switching activity for each bits of nodes. The power estimation have good efficient using proposed algorithm. This paper result obtain more Power reduction of fifty percents after using a new low power algorithm in a function unit as multiplier.