• Journal of the Korean Society for Precision Engineering
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• v.17 no.4
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• pp.7-21
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• 2000

This paper describes an overview of the thixoforming and thixomolding processes. Semi-solid metalworking (SSM), which is called the thixoforming process of aluminium materials, incorporates the elements of both casting and for the manufacture of near net shape parts. The SSM has some advantages such as net shape or near net shape manufacturing, the ability to form thin walls, excellent surface finish, tight tolerance, and excellent dimensional precision. The thixomolding process of Mg alloy (AZ9l) is a combination of two technologies both conventional die casting and plastic injection molding. The feed material used is a machined chip with a geometry of approximately 1 mm square and a length of 2~3 mm. The semi-solid forming (SSF) of high quality aluminium and magnesium parts will be established in the automotive and electronic industry, in the future. The hybrid method of casting/forging has been caused attention. This process uses a preformed material made by casting instead of the wrought material and finishes it by a single forging process. This process is expected to lower costs without sacrificing the mechanical and finishes it by a single forging process. The process is expected to lower costs without sacrificing the mechanical properties. The authors, intending that the casting/forging process contributes to a reduction in production cost of aluminum automotive parts in Korea, describes the feature of the casting/forging process, aluminum alloys suitable for the cast preform, microstructure and mechanical properties of the cast preform, application examples of cast/forging, and further study.

• Proceedings of the KIEE Conference
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• 2003.11b
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• pp.211-214
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• 2003

Current VOD embodiment way is embodied using PC base. However, achieved research that embody this by Embedded System that PC base is not. OS of this system used WindowsCE.net and x86core used having built-ined SC1200(National company's Geode's familys) by CPU and memory used 128MByte SDRAM. Used Mpeg Decoder for processing of video data, and used Enthernet Controller for Internet. Composite, component, S-Video of video output section of this system is and select one of these and connect on TV and did so that get into action. Actuality implementation manufactured necessary BIOS, WinodwsCE.NET Porting, DeviceDriver in system development and necessary simple Application in action confirmation, and Video Player used Window Media Player had included to WindowsCE.net. Therefore, treatise that see to supplement shortcomings of VOD service been embodying in current PC in Embedded System's form embody that there is sense do can.

• Microbiology and Biotechnology Letters
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• v.16 no.3
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• pp.231-237
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• 1988

Several methods to produce ethanol from tapioca starch were examined. Among four methods tested, alcohol fermentation with extruded tapioca starch was the most effective, which alcohol yield was 460.5 f/ton. After 69hours reaction with Rhizopus sp. glucoamylase, 108.7mg/$m\ell$ of reducing sugar were produced from extruded tapioca and 43.8mg/$m\ell$ from raw tapioca starch. In alcohol fermentation with extruded tapioca, the high concentration of alcohol at early stage prevented bacterial contamination and the fermentation rate was increased due to the high saccharifying power of glucoamylase on the extruded starch, but extrusion temperature had no influence on the fermentability, Scanning electron microscopy showed that the extrusion process changed the structure of tapioca starch granule to more susceptible form to glucoamylase attack than the raw starch. And glucoamylase of Rhizopus sp. had stronger digestion activity on both extruded tapioca and raw tapioca starch than that of Aspergillus usamii.

• Korean Journal of Oriental Medicine
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• v.6 no.1
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• pp.89-98
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• 2000

Cerebral ischemia, the most prevalent form of clinical stroke, is a medical problem of the first magnitude. Substantial efforts are being made to develop drugs which will protect the brain from the neurodegeneration followed by an ischemic stroke. A key factor in this process is the development of animal models that mimic the neuropathological consequences of stroke. Recently, there is increasing an evidence that free radical is involved in the mechanisms of ischemic brain damage. We investigated the macro scale gene expression analysis on the global ischemia induced by 4-vessel occlusion in Wister rats. The recent availability of microarrays provides an attractive strategy for elaborating an unbiased molecular profile of large number of genes during ischemic injury. This experimental approach offers the potential to identify molecules or cellular pathways not previously associated with ischemia. Ischemia was induced by 4-vessel occlusion for 10 minutes and reperfused again. RNA from sham control brain and time-dependent ischemed brain were hybridized to microarrays containing 4,000 rat genes. 589 genes were found to be at least 2 fold regulated at one or more time points. These survey data provide the foundation studies that should provide convincing proof for ischemia and oxidative stress on gene expression.

• Journal of Electrical Engineering and information Science
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• v.3 no.2
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• pp.239-244
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• 1998

Piezoelectric pressure sensors and pyroelectric infrared detectors based on ZnO thin film have been integrated with GaAs metal-semiconductor field effect transistor (MESFET) amplifiers. Surface micromachining techniques have been applied in a GaAs MESFET process to form both microsensors and electronic circuits. The on-chip integration of microsensors such as pressure sensors and infrared detectors with GaAs integrated circuits is attractive because of the higher operating temperature up to 200 oC for GaAs devices compared to 125 oC for silicon devices and radiation hardness for infrared imaging applications. The microsensors incorporate a 1${\mu}$m-thick sputtered ZnO capacitor supported by a 2${\mu}$m-thick aluminum membrane formed on a semi-insulating GaAs substrate. The piezoelectric pressure sensor of an area 80${\times}$80 ${\mu}$m2 designed for use as a miniature microphone exhibits 2.99${\mu}$V/${\mu}$ bar sensitivity at 400Hz. The voltage responsivity and the detectivity of a single infrared detector of an area 80${\times}$80 $\mu\textrm{m}$2 is 700 V/W and 6${\times}$108cm$.$ Hz/W at 10Hz respectively, and the time constant of the sensor with the amplifying circuit is 53 ms. Circuits using 4${\mu}$m-gate GaAs MESFETs are fabricated in planar, direct ion-implanted process. The measured transconductance of a 4${\mu}$m-gate GaAs MESFET is 25.6 mS/mm and 12.4 mS/mm at 27 oC and 200oC, respectively. A differential amplifier whose voltage gain in 33.7 dB using 4${\mu}$m gate GaAs MESFETs is fabricated for high selectivity to the physical variable being sensed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.10
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• pp.1553-1571
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• 1993

A significant amount of research has focused on the development of highly parallel architectures to obtain far more computational power than conventional computer systems. These architectures usually comprise of a large number of processors communicating through an interconnection network. The VLSI (Very Large Scale Integration) and WSI (Wafer Scale Integration) cellular arrays form one important class of those parallel architectures, and consist of a large number of simple processing cells, all on a single chip or wafer, each interconnected only to its neighbors. This paper studies three fundamental issues in these arrays : fault-tolerant reconfiguration. functional reconfiguration, and their integration. The paper examines conventional techniques, and gives an in-depth discussion about fault-tolerant reconfiguration and functional reconfiguration, presenting testing control strategy, configuration control strategy, steps required f4r each reconfiguration, and other relevant topics. The issue of integrating fault tolerant reconfiguration and functional reconfiguration has been addressed only recently. To tackle that problem, the paper identifies the relation between fault tolerant reconfiguration and functional reconfiguration, and discusses appropriate testing and configuration control strategy for integrated reconfiguration on VLSI and WSI cellular arrays.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.5
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• pp.509-516
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• 2004

High-performance Si integrated passive process was developed using thick oxidation process and Cu-BCB process. This passive process leads to low-cost and high-quality RF module with a small form factor. The fabricated spiral inductor with 225 um inner diameter and 2.5 turns showed the inductance of 2.7 nH and the quality factor more than 30 in the frequency region of 1 ㎓ and above. Also WLCSP-type integrated passive devices were fabricated using the high-performance spiral inductors. The fabricated low pass filter had a parallel-resonance circuit inside the spiral inductor to suppress 2nd harmonics and showed about 0.5 ㏈ insertion loss at 2.45 ㎓. And also the high/low-pass balun had the insertion loss less than 0.5 ㏈ and the phase difference of 182 degrees at 2.45 ㎓.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2003.11a
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• pp.84-87
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• 2003

Since Pb-free solder alloys have been used extensively in microelectronic packaging industry, the interaction between UBM (Under Bump Metallurgy) and solder is a critical issue because IMC (Intermetallic Compound) at the interface is critical for the adhesion of mechanical and the electrical contact for flip chip bonding. IMC growth must be fast during the reflow process to form stable IMC. Too fast IMC growth, however, is undesirable because it causes the dewetting of UBM and the unstable mechanical stability of thick IMC. UP to now. Ni and Cu are the most popular UBMs because electroplating is lower cost process than thin film deposition in vacuum for Al/Ni(V)/Cu or phased Cr-Cu. The consumption rate and the growth rate of IMC on Ni are lower than those of Cu. In contrast, the wetting of solder bumps on Cu is better than Ni. In addition, the residual stress of Cu is lower than that of Ni. Therefore, the alloy of Cu and Ni could be used as optimum UBM with both advantages of Ni and Cu. In this paper, the interfacial reactions of Sn-3.5Ag-0.7Cu solder on Ni-xCu alloy UBMs were investigated. The UBMs of Ni-Cu alloy were made on Si wafer. Thin Cr film and Cu film were used as adhesion layer and electroplating seed layer, respectively. And then, the solderable layer, Ni-Cu alloy, was deposited on the seed layer by electroplating. The UBM consumption rate and intermetallic growth on Ni-Cu alloy were studied as a function of time and Cu contents. And the IMCs between solder and UBM were analyzed with SEM, EDS, and TEM.

• Proceedings of the Korean Society for Bioinformatics Conference
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• 2000.11a
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• pp.53-55
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• 2000

Xenie is the JAVA application software that integrates and represents 'gene to function'information of human gene. Xenie extracts data from several heterogeneous molecular biology databases and provides integrated information in human readable and machine usable way. We defined 7 semantic frame classes (Gene, Transcript, Polypeptide, Protein_complex, Isotype, Functional_object, and Cell) as a common schema for storing and integrating gene to function information and relationship. Each of 7 semantic frame classes has data fields that are supposed to store biological data like gene symbol, disease information, cofactors, and inhibitors, etc. By using these semantic classes, Xenie can show how many transcripts and polypeptide has been known and what the function of gene products is in General. In detail, Xenie provides functional information of given human gene in the fields of semantic objects that are storing integrated data from several databases (Brenda, GDB, Genecards, HGMD, HUGO, LocusLink, OMIM, PIR, and SWISS-PROT). Although Xenie provide fully readable form of XML document for human researchers, the main goal of Xenie system is providing integrated data for other bioinformatic application softwares. Technically, Xenie provides two kinds of output format. One is JAVA persistent object, the other is XML document, both of them have been known as the most favorite solution for data exchange. Additionally, UML designs of Xenie and DTD for 7 semantic frame classes are available for easy data binding to other bioinformatic application systems. Hopefully, Xenie's output can provide more detailed and integrated information in several bioinformatic systems like Gene chip, 2D gel, biopathway related systems. Furthermore, through data integration, Xenie can also make a way for other bioiformatic systems to ask 'function based query'that was originally impossible to be answered because of separatly stored data in heterogeneous databases.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.10
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• pp.1392-1399
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• 2001

The flow fields inside a molten Zn pot of continuous hot-chip galvanizing process were investigated experimentally. With varying several parameters including the strip speed Vs, flow rate Q of induction heater. scrapper location and baffle configuration, instantaneous velocity fields were measured using a PIV velocity field measurement technique. Inside the strip region, counter-clockwise rotating flow is dominant. The general flow pattern inside the strip region is nearly not influenced by the strip speed Vs, flow rate Q and the scrapper location. In the exit region, the flow separated from the moving strip due to the existence of a stabilizing roll ascends to the free surface, for the cases of no scrapper and scrapper detached form the roll. On the other hand, the ascending flow to the free surface is decreased, as the flow rate Q of induction heater increases. By installing a baffle around the uprising strip, the flow moving up to the stabilizing roll decreases. In addition, B-type baffle is better than A-type baffle in reducing speed of flow around the stabilizing rolls. However, the flow ascended to the free surface is largely influenced by changing the flow rate Q, and the scrapper location, irrespective of the baffle type.