• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.4
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• pp.503-508
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• 2012

Among the high distribution voltage consumers, high-capacity consumers are often applying the grounding resistance method in order to overcome demerits such as erroneous operation of the ground reply or potential increase in the battery at the accident of the isolated neutral system. In this paper, to prevent damage to CLR and GPT in the delay to block the breakdown in the resistance grounded neutral system, this study aims to provide a proper suggestion for continuous rating capacity of GPT to check the appropriateness of CLR size and reduce GPT burden. Thereupon, this study comparatively analyzes CLR current applied in general GPT and the current gained when CLR demanded in the system is used and analyzes the simulated system through simulation using PSCAD/EMTDC in order to suggest GPT's proper continuous rating capacity.

• Proceedings of the Korea Contents Association Conference
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• 2007.11a
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• pp.817-821
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• 2007

A technique which uses the energy for a long time have been recognized as a important problem in embedded system with restricted battery. Recently the energy consumption is increased by using a large size of TFT-LCD and touch screen in embedded system. In this paper, we studied the frame buffer monitoring which can be reduced an energy consumption in GUI. The frame buffer monitoring technique is the energy degrade plan which adjusts Refresh-rate and Backlight. The technique must guarantee the quality of screen.

• Proceedings of the KIPE Conference
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• 2004.07b
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• pp.592-596
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• 2004

This paper deals with the operation of a flywheel energy storage UPS. The ups has good features such as long life-time, improved efficiency, no environment problems, reduced size and space, and low maintenance cost compared with the conventional UPS using battery. The operating principle of the UPS is analysed in each mode including charging, voltage compensation, discharging, and voltage unbalance compensation. Especially, the tracking characteristic of the disturbed phase of the source voltage after outage is analysed. The usefulness of the operation is proved through simulations.

• Proceedings of the KIPE Conference
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• 2012.11a
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• pp.50-51
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• 2012

The paper presents a non-isolated bidirectional DC-DC converter for use in renewable power generation, battery, electric vehicles (EV) and small scale DC-UPS systems. In the propose design, the conventional interleaved operation of two-inductor boost structure is modified to accommodate bidirectional operation, and zero-voltage-transition (ZVT) is applied, where both the switch and the rectifier diode achieve soft condition without increasing their voltage and current stresses. The proposed converter has the merits of simple circuitry, reduced size, low cost and high efficiency. The operation principle of the converter is analyzed and verified. Also, simulation results of the proposed bidirectional dc-dc converter is shown.

• Journal of Electrochemical Science and Technology
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• v.3 no.4
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• pp.172-177
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• 2012

Mo-doped $LiFePO_4$ was synthesized via co-precipitation method using sucrose as the carbon source. Structure, surface morphology, and the electrochemical properties of the synthesized olivine compounds were investigated using Rietveld refinement of X-ray diffraction data (XRD), scanning electron microscopy (SEM), and electrochemical charge-ischarge tests. Spherical morphology with the particle size of ${\sim}8{\mu}m$ authenticated the enhanced tap density and volumetric energy density of the synthesized materials. Charge-discharge behavior of $LiFePO_4$ and Mo-doped $LiFePO_4$ cells demonstrated a specific capacity of 130 and 145 mAh $g^{-1}$, respectively. Mo-doped $LiFePO_4$ cells exhibited an excellent discharge capacity at 96 mAh $g^{-1}$ at 7 C-rate.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.27 no.5
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• pp.268-273
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• 2017

In this study, nickel hydroxide crystalline powders were synthesized by continuous reaction in the taylor fluid flow using nickel chloride, nickel sulphate and sodium hydroxide as raw materials and compared with those prepared by a conventional batch type reaction. The crystallinity of nickel hydroxide prepared by the Taylor fluid flow reaction was higher than that of nickel hydroxide obtained by batch reaction. The particle size of nickel hydroxide decreased about 2.5 to 3.6 times, and the specific surface area was increased.

• Electrical & Electronic Materials
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• v.8 no.3
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• pp.254-260
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• 1995

A method is described for the design and fabrication of the sensor interface circuits on the Clark electrodes for the dissolved oxygen(DO). The discussion includes a method for the +5 V single-supply driving for the sensor circuits, which has low power comsumption for the front-end electronics. DO probe under test is composed of the Clark electrode with silver anode, gold cathode and the electrolyte of half saturated KCI solution and the FEP teflon memtrance for the oxygen penetration. Typical polarograms for the DO probes by using this sensor circuit reveals high accuracy over 99% of the I to V conversion. Partial pressure of oxygen obtained from the polarograms are well suited to the results calculated. It is expected that the proposed sensor circuits can be utilized into the customized IC for the battery-driven small-size DO meters.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.370-372
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• 2005

Inconveniences which might arise in transmitting measured biological data based on cable protocols generally are recognized critical points in tele-monitoring environment and also restrict the mobility of the user. a. Especially, activity monitoring which is importantly recognized as a core parameter in ubiquitous healthcare arena and weight management, pervasive and wireless measuring technology is most needed. In this paper, we would like to suggest lower power, miniaturized communication system in order to solve the above problems. The suggested system is powered by small coin-size battery. Also, The suggested system is compared with a blue-tooth module which is generally available in the commercial market. Even though, the suggested system didn't have higher transmission rate, its low power consumption make the suggested system would be feasible in ubiquitous monitoring of biological signals in ubiquitous healthcare arena.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.537-538
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• 2008

A step-down DC-DC converter with On-chip Compensation for battery-operated portable electronic devices which are designed in 0.18um CMOS standard process. In an effort to improve low load efficiency, this paper proposes the PFM (Pulse Frequency modulation) voltage mode 1MHz switching frequency step-down DC-DC converter with on-chip compensation. Capacitor multiplier method can minimize error amplifier compensation block size by 20%. It allows the compensation block of DC-DC converter be easily integrated on a chip and occupy less layout area. But capacitor multiplier operation reduces DC-DC converter efficiency. As a result, this converter shows maximum efficiency over 87% for the output voltage of 1.8V (input voltage : 3.3V), maximum load current 500mA, and 0.14% output ripple voltage. The total core chip area is $mm^2$.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.8 no.1
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• pp.76-81
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• 2009

The transmitting node in WSN for ITS would be small and operated by battery, and the MCU in the node would be low speed with small sized memory and low power consumption. In this paper, the post-checksum method in which the checksum field is added to the tail of the TCP segment for ITS applications, is proposed to reduce data processing time and power consumption, and so there is no limitation of the transmitting data size.