• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.4
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• pp.93-103
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• 2002

A new current mirror for high-accuracy current-mode signal processing and integrated circuit design was proposed. The current mirror adopts the technique of an adaptive feedback to reduce the input impedance and the output stage of regulated cascode current mirror to increase the output impedance. Simulation results show that the current mirror has input impedance of 0.9Ω, the output impedance of 415 MΩ, and current gain of 0.96 at the supply voltage Vcc=5V. The power dissipation is 1.5㎽. In order to certify the applicability of the proposed current mirror, a voltage-to-current converter using the current mirror is designed. Simulation results show that the converter has good agreement with theoretical equation and has three times better conversion characteristics when compared with voltage-to-current converter using Wilson current mirror.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.3 no.4
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• pp.73-80
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• 2004

A dual purpose robot automation system is developed for both arc welding and spot welding by one robot within a cell. The need for automation of both arc welding and spot welding processes is urgent while the production volume is not so big as to accommodate separate station for the two processes. Also, space is too narrow for separate station to be settled down in the factory. A spot welding robot is chosen and the function for arc welding are implemented in-house at cost of advanced functions. For the spot welding, a single pole type gun is used and the robot has to push down the plate to be welded, which causes the robot positioning error. Therefore, position error compensation algorithm is developed. The basic functions for the arc welding processes are implemented using the digital I/O board of robot controller, PLC, and A/D conversion PCB. The weaving pattern is taught in meticulously by manual teach. A fixture unit is also developed for dual purpose. The main aspects of the system is presented in this paper especially in the design and implementation procedure. The signal diagrams and sequence logic diagrams are also included. The outcome of the dual purpose welding cell is the increased productivity and good production stability which is indispensable for production volume prediction. Also, it leads to reduction of manufacturing lead time.

• International Journal of Oral Biology
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• v.39 no.4
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• pp.193-199
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• 2014

Fluoride has been accepted as an important material for oral health and is widely used to prevent dental caries in dentistry. However, its safety is still questioned by some. Autophagy has been implicated in cancer cell survival and death, and may play an important role in oral cancer. This study was undertaken to examine whether sodium fluoride (NaF) modulates autophagy in SCC25 human tongue squamous cell carcinoma cells. NaF demonstrated anticancer activity via autophagic and apoptotic cell death. Autophagic vacuoles were detectable using observed to form by monodansylcadaverine (MDC) and acridine orange (AO). Analysis of NaF-treated SCC25 cells for the presence of biochemical markers revealed direct effects on the conversion of LC-3II, degradation of p62/SQSTM1, cleavage formation of ATG5 and Beclin-1, and caspase activation. NaF-induced cell death was suppressed by the autophagy inhibitor 3-methyladenine (3-MA). NaF-induced autophagy was confirmed as a pro-death signal in SCC25 cells. These results implicate NaF as a novel anticancer compound for oral cancer therapy.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.15-16
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• 2012

General lighting will be replaced into LED due to the high efficiency, low power consumption, long life than conventional light, moreover, since it is a basically semiconductor device that can convert the electric energy to visible light at a very high speed, using these characteristics can be performed communication modulation via the high-speed ON-OFF switching. Recently, visible light communication (VLC: Visible Light Communication) technology is received attention and there have been many researches. This paper is implemented media signal transmission by combining LED with VLC, a transmitter used the LED light-emitting device and receiver used an infrared sensor. In order to increase the efficiency of the communication system to improve the existing LED visible light communication driver of power conversion efficiency and thermal issues that is applied to the visible light communication in order to improve the speed of transmission media to research a new way of LED driver.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.7A
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• pp.794-806
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• 2004

This paper deals with correction of frequency offset and analysis of quantization angle noise in the IEEE 802.1la OFDM system. The rotation phase per symbol due to the carrier frequency offset is estimated from auto-correlation of the short Preambles, which are over-sampled for the reduction of noise in OFDM signals. The pilot signals are introduced to estimate the rotation phase per OFDM symbol due to estimation error of the carrier frequency offset and the sampling frequency onset. During the estimation and correction of the frequency onsets, a CORDIC processor and a look-up table are used for the conversion between a rotation phase and its complex number. Being calculated by a limited number of bits in the CORDIC processor and the look-up table, the rotation phase and its complex number have quantization angle errors. The quantization errors are analyzed as SNR (signal to noise ratio) due to the quantization bit numbers. The minimum bit number is suggested to meet the specification of IEEE 802.1la properly. Finally, the quantization errors are evaluated through simulations on number of quantization bits and SNR of received signals.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.8A
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• pp.712-719
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• 2012

This paper presents Single-bit Third order Delta-Sigma Modulator, which can be applied to the Low speed High resolution ADC in Audio signal Process System. Whereas the Operational Amplifier in modulator consumed static power dissipation in operating, this modulator used Switching on/off techniques, which makes the Power dissipation of the modulator reduced. Also proposed modulator minimizes frequency characteristic variation by optimizing switch position. And this modulator chooses Single-bit type to guarantee stability. The designed ADC went through 0.35um CMOS n-well 1-poly 4-metal process to be a final product, and the final product has shown 17.1mW of power dissipation with 3.3V of Supply Voltage, 6.4MHz of conversion rate. And 84.3dB SNDR and 13.5bit ENOB with 20KHz of input frequency.

• Journal of Microbiology and Biotechnology
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• v.23 no.12
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• pp.1791-1801
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• 2013

Diketopiperazine is produced by various organisms, including bacteria, fungi, and animals, and has been suggested as a novel signal molecule involved in the modulation of genes with various biological functions. Vibrio vulnificus, which causes septicemia in humans, produces cyclo($\small{L}$-phenylalanine-$\small{L}$-proline) (cFP). To understand the biological roles of cFP, the effect of the compound on the expression of the total mRNA in V. vulnificus was assessed by next-generation sequencing. Based on the transcriptomic analysis, we classified the cFP-regulated genes into functional categories and clustered them according to the expression patterns resulted from treatment with cFP. From a total of 4,673 genes, excepting the genes encoding tRNA in V. vulnificus, 356 genes were up-regulated and 602 genes were down-regulated with an RPKM (reads per kilobase per million) value above 3. The genes most highly induced by cFP comprised those associated with the transport and metabolism of inorganic molecules, particularly iron. The genes negatively regulated by cFP included those associated with energy production and conversion, as well as carbohydrate metabolism. Noticeably, numerous genes related with biofilm formation were modulated by cFP. We demonstrated that cFP interferes significantly with the biofilm formation of V. vulnificus.

• Journal of Korean Society of Transportation
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• v.27 no.4
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• pp.41-53
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• 2009

For 5 years and 6 months, ranging from January 2003 to June 2008, SPSS 12.0 Statistical Program was used to analyze the overall analysis, analysis of center line encroachment, analysis of signal violations, analysis of drinking while intoxicated, analysis of driving without license, analysis of two-wheel vehicle, analysis of pedestrian, analysis of safety equipment, analysis of traffic publicity or education and automobile registration accounts, and casualty of traffic accidents that are determined as having statistical implication based on the statistics available from the policy to take a look at traffic accident in the Daejeon area, and there were some meaningful results. With the proof that there is a certain level of ratio for the correlations between traffic control and traffic accident that the effect of traffic control has shown with certain time interval. The relationship of traffic control and the casualty of traffic accident has very low coefficient of correlations that it is not statistically noticeable that traffic control of the police has almost no effect in preventing traffic accident. This is a display of the fact that the conversion of direction for traffic safety measure undertaken to this point is rather urgent that there is a dire need of establishing the effective alternatives.

• Journal of the Korean Society for Nondestructive Testing
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• v.16 no.3
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• pp.155-161
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• 1996

For the condition monitoring of the journal bearing in rotating machinery, a system for their diagnosis by acoustic emission(AE) was developed. AE has been used to detect abnormal conditions in the bearing system. It was found from the field application study as well as the laboratory experiment using a simulated journal bearing system that AE RMS voltage was the most efficient parameter for the purpose of current study. Based on the above results, algorithms and judgement criteria for the diagnosis system was established. The system is composed of four parts as follows: the sensing part including AE sensor and preamplifier, the signal processing part for RMS-to-DC conversion to measure AE ms voltage, the interface part for transferring RMS voltage data into PC using A/D converter, and the software part including the graphic display of bearing conditions and the diagnosis program.

• Molecules and Cells
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• v.28 no.2
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• pp.125-130
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• 2009

Tacrolimus is a widely used T cell targeted immunosuppressive drug, known as a calcineurin inhibitor. However, the exact pharmacological effects of tacrolimus on $CD4^+$ T cells have yet to be elucidated. This study investigated the effects of tacrolimus on $CD4^+$ T cell subsets. Mouse or human $CD4^+$ T cells were cultured with immobilized anti-CD3/CD28 antibodies in the presence of tacrolimus. The cell division of $CD4^+$ T cells was analyzed using a flow cytometer according to the expression of Foxp3. The gene expression patterns of tacrolimus-exposed T cells were examined by quantitative PCR. In the case of conventional $CD4^+$ T cells (Tconv cells), tacrolimus inhibited T cell receptor stimulation-induced cell division. In contrast, the cell division of regulatory $CD4^+$ T cells (Treg cells) was even promoted in the presence of tacrolimus, especially in humans. Tacrolimus did not promote conversion of Tconv to Treg cells in mice. Furthermore, tacrolimus modified the expression levels of Foxp3-regulated T cell receptor signal related-genes, PTPN22 and Itk, in human Treg cells. Immunosuppressive effect of tacrolimus may be attributed to the relatively enhanced proliferation of Treg cells in association with altered gene expression levels of TCR signaling molecules.