• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.2
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• pp.128-133
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• 2009

This paper describes the development of a miniature high voltage power supply for driving an image intensifier tube (IIT). The IIT is used for portable night vision devices to observe an object in the dark. A small-sized high voltage power supply generating thousands volts from the battery power source is needed to drive the IIT. This paper presents the design and implementation of the high voltage power supply for the IIT. The experimental results are provided to verify the operation of the developed power supply.

• Journal of Korea Society of Digital Industry and Information Management
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• v.12 no.2
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• pp.1-6
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• 2016

Several efforts to replace the use of existing fossil energy resources have already been made around the world. As a result, a new industry of renewable energy has been created, and efficient energy distribution and storage has been promoted intensively. Among the newly explored renewable energy sources, the most widely used one is solar energy generation, which has a high market potential. An energy storage system (ESS) is a system as required. In this paper, the design and implementation of an ESS for the efficient use of power in stand-alone street lights is presented. In current ESS applied to stand-alone street lights, either 12V~24V DC (from solar power) or 110V~220V AC (from commercial power) is used to recharge power in systems with lithium batteries. In this study, an ESS that can support both solar power and commercial power was designed and implemented; it can also perform emergency recharge of portable devices from solar powered street lights. This system can maximize the scalability of ESSes using lithium batteries with efficient energy conversion, with the advantage of being an eco-friendly technology. In a ripple effect, it can also be applied to smart grids, electric vehicles, and new, renewable storage markets where energy storage technology is required.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.72-72
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• 2012

Lithium rechargeable batteries have been widely used as key power sources for portable devices for the last couple of decades. Their high energy density and power have allowed the proliferation of ever more complex portable devices such as cellular phones, laptops and PDA's. For larger scale applications, such as batteries in plug-in hybrid electric vehicles (PHEV) or power tools, higher standards of the battery, especially in term of the rate (power) capability and energy density, are required. In PHEV, the materials in the rechargeable battery must be able to charge and discharge (power capability) with sufficient speed to take advantage of regenerative braking and give the desirable power to accelerate the car. The driving mileage of the electric car is simply a function of the energy density of the batteries. Since the successful launch of recent Ni-MH (Nickel Metal Hydride)-based HEVs (Hybrid Electric Vehicles) in the market, there has been intense demand for the high power-capable Li battery with higher energy density and reduced cost to make HEV vehicles more efficient and reduce emissions. However, current Li rechargeable battery technology has to improve significantly to meet the requirements for HEV applications not to mention PHEV. In an effort to design and develop an advanced electrode material with high power and energy for Li rechargeable batteries, we approached to this in two different length scales - Atomic and Nano engineering of materials. In the atomic design of electrode materials, we have combined theoretical investigation using ab initio calculations with experimental realization. Based on fundamental understanding on Li diffusion, polaronic conduction, operating potential, electronic structure and atomic bonding nature of electrode materials by theoretical calculations, we could identify and define the problems of existing electrode materials, suggest possible strategy and experimentally improve the electrochemical property. This approach often leads to a design of completely new compounds with new crystal structures. In this seminar, I will talk about two examples of electrode material study under this approach; $LiNi_{0.5}Mn_{0.5}O_2$ based layered materials and olivine based multi-component systems. In the other scale of approach; nano engineering; the morphology of electrode materials are controlled in nano scales to explore new electrochemical properties arising from the limited length scales and nano scale electrode architecture. Power, energy and cycle stability are demonstrated to be sensitively affected by electrode architecture in nano scales. This part of story will be only given summarized in the talk.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.8
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• pp.1795-1801
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• 2009

In this study, a portable flashlight which can manually generate the electricity by using sunlight was developed so that it can be used in the extreme environmental condition such as no-electricity condition. Battery is charged by using solar battery during the day, but when sunlight is not avalible during the night or rainy day, a handle is rotated to generate the electricity in order to charge the battery manually. To improve the brightness of the light, light is concentrated by using the optical lens. Low electric consumption circuit is used for the longer operating time by suppress electrical consumption while lamp is discharged. A circuit is designed and used for steady electrical curris dand voltage to insure steady battery charging. Super-discharge circuit and protection circuit are used for the super discharge of battery when it is not used for a long time. Also the constant charge is possible by using houseware adapter. As a result, a portable flashlight is designed to charge with sunlight during day, and with houseware adapter during night. A portable flashlight is also designed to irradiate longer distances by improvement of the brightness of the light using the optical lens. Thus, it forms white natural ray of light making possible for night reading.

• Proceedings of the IEEK Conference
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• 2004.06b
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• pp.593-596
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• 2004

This paper presents a low power design of the embedded 3D graphics rendering processor with the double span processing stage. The increase of hardware complexity by using the double span processing stage is ignorable. And the performance is equal to the rendering processor with the single span processing stage. It reduces the power consumption by using different clock frequencies.

• Proceedings of the KIEE Conference
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• 2007.11b
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• pp.92-94
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• 2007

This article describes a thermoelectric converter, which is powered by thermoelectric (TE) power modules. This system uses TE devices that directly convert heat energy to electricity to power a converter using direct methanol fuel ceil (DMFC) system. The characteristics of the TE module were tested at different temperatures. A boost BC-DC converter was designed and controlled by a power-supply controller chip. Efficiency of about 80% can be achieved and because the thermoelectric converter system has not moving parts and has a small volume, the system can be carried about easily and conveniently to supply portable electric equipment and this is very important for some mobile equipment.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.113-116
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• 2007

The fuel cell which converts directly chemical energy of fuel into electric energy has higher efficiency than the conventional power generation which involves several additional processes. Especially, polymer electrolyte membrane fuel cell (PEMFC) of which the electrolyte is a thin proton conductive polymer membrane is affordable for portable power applications and small-scale distributed power generation including household and small building. It is very important to not only increase the efficiency of FC itself but determine the optimal operation mode. The optimal operational planning of lkW household PEMFC system based on the daily electricity and heat demand patterns was performed. The estimated economic gain was up to 20% by adoption of PEMFC system.

• Journal of Satellite, Information and Communications
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• v.11 no.3
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• pp.127-132
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• 2016

This paper presents the design of a palm-sized metamaterial antenna system having reconfigurable polarization as well as dual-band characteristics. Basically, three antennas are laid by 45 degrees in order and excited by a compact metamaterial dual-band power-divider of the in-phase outputs, and the radiated fields of the antennas are mixed to turn the vector of the polarization to another. The validity of the proposed method is verified by observing the in-phase outputs from the odd-numbered power-dividing device for both 900 MHz and 2.4 GHz, and checking the changeable polarization with the antenna gain over 2 dBi for all the polarizations.

• Proceedings of the KIPE Conference
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• 2014.11a
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• pp.60-61
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• 2014

Lithium-Ion batteries have become the best tradeoff between energy, power density and cost of the energy storage system in many portable high electric power applications. In order to manage the battery efficiently State of Charge (SOC) of the battery needs to be estimated accurately. In this paper a model-based approach to estimate the SOC of the Lithium-Ion battery based on the estimation of the battery impedance is proposed. The validity and feasibility of the proposed algorithm is verified by the experimental results.

• 유체기계공업학회:학술대회논문집
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• 2001.11a
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• pp.367-372
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• 2001

A fuel cell is an electrochemical energy conversion device tint converts hydrogen and oxygen into electricity and heat for hot water and heating room A fuel cell provides a DC voltage tint can be used to power motors, lights or any number if electrical appliances. There are several different types if fuel cells, each using a different chemistry. Some types if fuel cells show promise for use in DC (distributed generation) because fuel cell is very clean and efficient energy device. CETI (Clean Energy Technologies, Inc.) is developing PEMFC and DMFC for residential power generation, portable and battery. It is anticipated tint RPG is advantageous over current power generation by utility In terms if economics assuming the lifetime of major components is at least five years.