• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.10
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• pp.776-783
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• 2008

The object of this paper is to study on the thermal performance of a micro channel water block for computer CPU cooling. The effects of liquid flow rate, micro channel width and height on the thermal performances of water block are investigated experimentally. The water block was fabricated Al and machined with a micro milling. The water block consisted of rectangular micro channels 0.5 to 0.9 mm width and 1.5 to 4.5 mm height. The experiments were conducted using deionized water, over a liquid flow rate ranging from 0.2 to 2.0 kg/min. The base temperature and thermal resistance decrease with increasing of liquid flow rate. The increase of a channel height is more effective on the thermal resistance than the decrease of a channel width. At the flow rate of 0.7 kg/min, input power of 100 W, the base temperature and thermal resistance of sample 6 is $33^{\circ}C$ and $0.13\;^{\circ}C/W$ respectively.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.1
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• pp.149-156
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• 2017

Graphene nanoplatelet (GNP)-reinforced alumina ($Al_2O_3$) is a promising material for micro-partapplications, particularly micro-nozzle shapes, because of its excellent wearresistance. In this study, a $Al_2O_3$/GNPcomposite with 15 vol% graphene nanoplatelets (GNP) was highly densified and fabricated via spark plasma sintering for micro-electrical discharge drilling (Micro-ED drilling) and the wear resistance property of the composite is evaluated via the ball-on-disk method. In addition, the diameter and shape of the micro-electrodes machined by wire electrical discharge grinding (WEDG), block electrical discharge grinding (BEDG), and new linear block moving electrical discharge grinding (LBMEDG) methods are systematically compared and analyzed to observe the micro-hole machining in the micro-ED drilling of the $Al_2O_3$/15vol% GNP composite.

• Smart Structures and Systems
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• v.13 no.6
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• pp.959-974
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• 2014

Hand-Arm Vibration Syndrome (HAVS) is a group of diseases caused by exposure of the hands to vibration while operating the hand held power tools such as road breaker, drilling machine, demolition hammer in construction works. In this paper, area-changed capacitive micro-accelerometer is designed to measure the vibration exposure on worker's hand when operating a drilling machine on various blocks such as clay block, paver block and solid cement block. The design process includes mathematical modelling of micro-accelerometer and simulations are done using INTELLISUITE 8.6. Experimental results are taken for various blocks surfaces using conventional and micro-accelerometer. Comparisons show that usage of area-changed micro-accelerometer for Hand-arm vibration monitoring provides better sensitivity, which in turn reduces the risk of HAVS in workers.

• Korean Journal of Optics and Photonics
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• v.19 no.2
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• pp.140-143
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• 2008

The integrated external cavity laser has been fabricated with a 1550 nm FP-LD, an optical filter, a micro ball lens and accurate ceramic blocks using a micro-block stacking (MBS) technique. The integrated external cavity laser module whose size is only $2.0{\times}2.1{\times}0.7\;mm^3$ has been mounted on the TO-CAN package. For the case of the 1.8% transmission filter, the single mode characteristic has been obtained with the optical power of -27.1 dBm and the SMSR of 31.7 dB.

• Korean Journal of Optics and Photonics
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• v.23 no.5
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• pp.217-221
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• 2012

In this paper, we have fabricated by means of the "Micro-Block Stacking (MBS)" method the 8 pin mini DIL integrated Triplexer, which can transmit CATV and voice/data at the same time in a single fiber. Our MBS technique is a novel scheme of compact optical module packaging which secures precision positioning of the components on the optical beam path by prefixed stacks of ceramic blocks. The subassembly in which a laser diode, two receiver photodiodes, two WDM filters, and four micro lenses are integrated is only $5.40mm{\times}2.15mm{\times}1.05mm$ in size. As the Triplexer is aligned to the single mode fiber, the transmitter power of -14.5 dBm and the receiver sensitivities of 0.83 A/W, 0.73 A/W for 1550 nm, 1490 nm, respectively are obtained.

• Journal of the Speleological Society of Korea
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• no.68
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• pp.75-98
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• 2005

Korea physiographic province is divided into two provinces which is northern Chugaryung graben zone and southern Chugraryung graben zone. Northern Chugraryung is also divided in to Gema block and Kohan block, and southern Chugraryung dividedinto Han block, Yongnam basin and Honam plain. The above mentioned macro geomorophic units is divided, mainly on the geotectonics. The meso geomorphic units is divided, based upon the regional distribution of topographic characteristic that is plateaus, mountains, mountain range, basins and great plain etc. Micro geomorphic units id into a mountain, a hill, a plain, and a lowland, and then it is formed by selfreliant topographic unit. And micro topographic (fan, peneplain, delta, etc) dealt with a characteristics unit. In this article has a disregarded amallest scale that is included flood plait natural levee, back marsh and oxbow lake etc. Accordingly, it shows macro units are meso units are 5, meso units are 53, micro units are 299. A study method of physiographic provincs prefered to aufsteigende and abstergands methoy. How to organically combine topographic factors can be seen in regional distribution of the peculiar topographic characteristics, for charage teristic of topographic makes a study on the topographic of micro unit such understanding as aufsteigende method. At the same time, since it can be studied systematically from marco unit to micro unit like the absteigende methods, I used both methods. And this establishment of physiographic province based on the scientific method depend on the base map of climate classification. Geology, Soil, Biology. I feel confident that it will be used the basic map for land use map, land classification map, study of geomorphology of Korea. And will be used for study of a topographic standard data.

• International Journal of Railway
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• v.2 no.3
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• pp.127-130
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• 2009

The system improves the safety and efficiency of railway transport, combining the advanced axle-counter with single-track semiautomatic block. Using computer, to accomplish relay-based semiautomatic block logic operation and axle-counter to check section status, it will further increase the performance of railway transport. Safety-related communication is one of the important topics in railway signal system. By referring to relevant safety-related communication standards, to research on safety-related communication of Micro-computer automatic block between Railway Stations System, the thesis introduces the basic requirements, concept model, codes, and the process, etc.

• Journal of the Korea Society of Computer and Information
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• v.9 no.3
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• pp.127-133
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• 2004

This study was carried out develope a temperature control system of temperature control by used K-thermocouple. This system was producted a stable voltage regulator 22Bit of digital converter and 22Bit of resolution. It was producted a micro voltage of 25 times amplification and controlled a DC0.1V~DC4.7V within 0～120$0^{\circ}C$. We designed block-diagram of hardware and software by PIC16C74 in a micro-controller, we are made up of a VFD function and can be used interface of a power block.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.7
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• pp.902-909
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• 2012

This study is aimed to develop a new type of micro cross-flow hydro turbine which has very simple structure and relatively high efficiency. Micro eco cross-flow hydro turbine (ECFT) is proposed to apply in the ranges of very low and middle specific speeds in order to extend the operational range of the turbine. In order to not only obtain a basic data for a new design method of ECFT but also improve the turbine efficiency, experiments and CFD analysis on the performance and internal flow characteristics of the turbine model are conducted. According to the present study results, anti-recirculation block (ARB) and relatively wide turbine width with high flow rate improve the turbine efficiency.

• Journal of Welding and Joining
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• v.33 no.4
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• pp.44-49
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• 2015

The structural epoxy adhesive used in car body assembly needs the highest level of joint mechanical strength under lap shear, T-peel and impact peel conditions. In this study, the effect of nano functionalized block copolymer addition on the impact peel strength of epoxy adhesive was investigated. DSC analysis showed that the addition of nano functionalized block copolymer did not affect the curing reaction of epoxy adhesive. From single lap shear test, it was found out that the addition of nano functionalized block copolymer slightly decreased the cohesive strength of cured adhesive layer. The addition of nano functionalized block copolymer showed beneficial effect on T-peel strength by changing the adhesive failure mode to the mixed mode. However, the addition of nano functionalized block copolymer just decreased the room temperature impact peel strength. It was considered that the addition of nano functionalized block copolymer could have effect on disturbing the crack propagation only for the case of slow strain rate.