• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.1A
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• pp.104-112
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• 2005

Some design techniques for high speed and low power pipelined 8-bit ADC are described. To perform high-speed operation with relatively low power consumption, open loop architecture is adopted, while closed loop architecture (with MDAC) is used in conventional pipeline ADC. A distributed track and hold amplifier and a cascading structure are also adopted to increase the sampling rate. To reduce the power consumption and the die area, the number of amplifiers in each stage are optimized and reduced with proposed zero-crossing point generation method. At 500-MHz sampling rate, simulation results show that the power consumption is 210mW including digital logic with 1.8V power supply. And the targeted ADC achieves ENOB of about 8-bit with input frequency up to 200-MHz and input range of 1.2Vpp (Differential). The ADC is designed using a $0.18{\mu}m$ 6-Metal 1-Poly CMOS process and occupies an area of $900{\mu}m{\times}500{\mu}m$

• Journal of Korean Society of Forest Science
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• v.85 no.1
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• pp.107-119
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• 1996

To understand vegetation changes along environmental gradients in the natural forests in the east side of the Cascade Range in Washington state, USA, line transects were used to sample six different forest environments in the Wenatchee National Forest in the north-facing and south-facing sites at 975, 1280 and 1700m elevation. Data were analyzed using ordination by detranded correspondence analysis. Pseudotsuga menziesii was found as one of the dominant species on all the six sites regardless of elevation or aspect, while Pinus ponderosa was dominant on south slopes only. Abies grandis and A. lasiocarpa were dominant species on north slopes at elevations of 1280 and 1700m, respectively. Moisture, as it related to aspect, was identified as one of the most important environmental gradients for explaining the variation of vegetation types. On north-facing slopes, compared to south-facing slopes, where moisture was not as limiting and canopies could grow denser, probably, elevation or competitive interaction was more important. Species diversity tended to decrease with increasing environmental severity, with south slopes having less diversity than north slopes due to extended water stress and harsher temperature extremes on south slopes. The age structure on north-facing and south-facing slopes was different. Light intensity, moisture and climate were different between these two slopes. Large scale disturbances(e.g., big fire or insects) were major causes in changing age structure. Younger trees showed a closer relationship between size and age than adult trees. DBH values of shade intolerant species in south-facing slope were bigger than those of north-facing slope, which suggested that aspect of stands be the most important factor for age and size.

• Journal of the Society of Naval Architects of Korea
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• v.54 no.5
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• pp.406-414
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• 2017

An experimental study in a recirculating water channel was carried out to investigate the effect of large coherent structures to the skin friction on a flat plate. Particle Image Velocimetry (PIV) technique was used to quantify characteristic features of coherent structures growing to the boundary layer. In the PIV measurement, it is difficult to calculate the friction velocity near the wall region due to laser deflection and uncertainty so that Clauser fitting method at the logarithmic region was adopted to compute the friction velocity and compared with the one directly measured by the dynamometer. With changing the free-stream velocity from 0.5 m/s to 1.0 m/s, the activity of coherent structures in the logarithmic region was increased over three times in terms of Reynolds stress. The flow field was separated by Variable Interval Time Averaging (VITA) technique into the weak and the strong structure case depending on the existence large coherent structures in order to validate its effectiveness. The stream-wise velocity fluctuation was scanned through at the boundary thickness whether it had a large deviation from background flow. With coherent structures connected from near-wall to the boundary layer, mean wall shear stress was higher than that of weak structure case. Proper Orthogonal Decomposition (POD) analysis was also applied to compare the energy budget between them at each free-stream velocity.

• Asian-Australasian Journal of Animal Sciences
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• v.21 no.4
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• pp.499-509
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• 2008

Foxo1 plays an important role in the integration of hormone-activated signaling pathways with the complex transcriptional cascade that promotes preadipocyte differentiation of clonal cell lines from rodents. We isolated the full-length cDNA of porcine FoxO1 gene using RACE, confirmed by visual Northern blotting. The deduced amino acids indicated 94% and 90% identities with the corresponding human and mice aa. Analysis of the aa sequence, showed that it included a Forkhead domain (aa 167-247), a transmembrane structure domain (aa 90-113), a LXXLL motif (aa 469-473), and 51 Ser, 8 Thr, and 4 Tyr phosphorylation sites, indicating a potential important role for FoxO1 transcriptional activity in vivo. Using the IMpRH panel, we mapped FoxO1 gene to chromosome 11p13. Our data provide basic molecular information useful for the further investigation on the function of FoxO1 gene. Time-course analysis of FoxO1 expressions indicated that levels of mRNA and protein gradually increased from day 0 to 3, and it reached almost maximal level at day 3, then decreased from day 5 to 7 in porcine primary preadipocyte differentiation. After induction by IGF-1, GPDH activity and accumulation of lipid increased, however, expressions of FoxO1 mRNA and protein were inhibited in a dose dependent manner. These results suggest that FoxO1 takes part in porcine preadipocyte differentiation and expressions of FoxO1 were regulated by IGF-1.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.2
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• pp.257-267
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• 2001

This paper presents a design for a single-layer feeder waveguide array using $\pi$-junctions with the inductive wall. The feed structure consists of a single waveguide placed on the same layer as radiating waveguide and is characterized by the unit divider, called a $\pi$-junction. This $\pi$-junction with an inductive wall splits part of the power into two branchs waveguide through one coupling window, and can excite densely arrayed waveguide at equal phase and amplitude. The power dividing characteristics of the cascade of $\pi$ -junctions are analyzed by Galerkin's method of moments. The numerical results show reasonable agreement with the experimental results. From the optimum simulation results based on the feeder waveguide using $\pi$-junction, we obtained the scattering matrices of the feeder divided power at 3.95 GHz.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1997.11a
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• pp.47-50
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• 1997

Drug development began with the finding of biologically active compounds which are obtained by chemical synthesis or from natural sources. The advent of Combinatorial Chemistry is recognized as a strategy which has a potential to change the methodology of research and development(R&D) of new drugs. Drug development has been carried out with diverse strategies. In the past several decades a variety of new methodology have been introduced in R&D. Random screening of accumulated synthetic samples which had been synthesized for development of other drugs led to the discovery of new drugs. The typical examples are anti-asthma drug trimethoquinol and calcium antagonist diltiazem. (herbesser). In particular the latter drug has been used as a calcium antagonist worldwide, however it was first synthesized to find new tranquilizer and this is the reason why diltiazem has benzodiazepam skeleton. The random screening contributed in the finding of new drugs were carried out with whole animal test and it is a standard methodology in R&D of new drugs. Aspirin is the first synthetic non-steroidal antiinflammatory drug(NSAID) and has been used for more than one hundred years. It is the first example of drug developed from natural product. Salicin is the main constituent of willow bark which had been used in Europe for a long time to treat arthritis and aspirin was developed from salicin. Most of NSAID used clinically were developed from the structure of aspirin, however it took 70 years to clarify why aspirin exhibits its antiinflammatory, analgesic and antipyretic activities. The target of aspirin is cyclooxygenase(COX)which is the first enzyme involved in arachidonate cascade leading to the production of prostaglandins(PG) and thromboxan(TX). Side effect of aspirin causing ulcer in stomach is rather serious problem, since aspirin is so popular drug easily obtained in drug store(OTP). This problem is now going to be solved by a new finding on COX, which have two different types, one is constitutionally expressed COX 1 in almost all organs and the other is inducible COX 2. COX 2 is the responsible enzyme in inflammation etc and now the search of COX 2 specific inhibitors is the target of R&D of next generation NSAID.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.4
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• pp.14-23
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• 2011

In this paper, a 7-bit 2GSPS folding/interpolation A/D Converter(ADC) with a Self-Calibrated Vector Generator is proposed. The ADC structure is based on a folding/interpolation architecture whose folding/interpolation rate is 4 and 8, respectively. A cascaded preprocessing block is not only used in order to drive the high input signal frequency, but the resistive interpolation is also used to reduce the power consumption. Based on a novel self-calibrated vector generator, further, offset errors due to device mismatch, parasitic resistors. and parasitic capacitance can be reduced. The chip has been fabricated with a 1.2V 0.13um 1-poly 7-metal CMOS technology. The effective chip area including the calibration circuit is 2.5$mm^2$. SNDR is about 39.49dB when the input frequency is 9MHz at 2GHz sampling frequency. The SNDR is improved by 3dB with the calibration circuit.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.2 s.93
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• pp.134-138
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• 2005

In this paper, we have developed a new type of the microwave phase conjugator for the active retrodirective antenna array. The circuit topology is consisted of a 2-port structure to avoid the complexity of LO and RF signal combination and matching, using the cascade connection of two single-ended mixers. The operating frequencies are 4.0 GHz, 2.01 GHz and 1.99 GHz for LO, RF, and IF, respectively. Conversion loss is measured to be -7 dB and 1-dB compression point 15 dBm with the LO power of 9 dBm. For the most important parameter, the isolation between RE leakage and IF signal is as high as 25 dB.

• Proceedings of the Korean Society of Applied Pharmacology
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• 2000.04a
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• pp.10-14
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• 2000

The cycloooxygenase enzymes catalyze the oxidative conversion of arachidonic acid into prostag1andin H$_2$Which mediates both benificial and pathological effects. The COX-1 is constitutively expressed in most tissues and in blood platelets wherease the expression of COX-2 isoform is induced in response to inflmmatory stimuli such as cyctokynes. Thus the identification of a novel COX-2 selective inhibitor should offer excellent antiinflammatory activity with minimal side effects such as gastrointestinal toxicity. Recently, a group of structurally unique and biologically active pimarane diterpenoids has been isolated from indigenous Korean medicinal plants. These new diterpenoids turned out to be potential analgesic and antiinflammatory agent due to their potent inhibitory activities of prostaglandin synthesis. We have also found that the inhibition of PGE$_2$synthesis is attributed to the potent COX inhibition by pimarane diterpenoid in arachidonic acid cascade. In conjunction with development of new analgesic and nonsteroidal antiinflammatory agent, a series of works on these diterpenoids have been extensively carried out in our laboratories. These efforts involve the structure-activity relationship of pimaradienoic acid, molecular modelings and COX inibitory activities as well as actiinflammatory effects of its structural analogues. In addition, the total syntheses of the new natural pimarane diterpenoids, their stereoisomers and other structural variants were intensively investigated.

• Journal of electromagnetic engineering and science
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• v.11 no.2
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• pp.76-82
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• 2011

In this paper, a novel design for a dual-band negative group delay circuit (NGDC) is proposed. Composite right/left-handed (CRLH) ${\lambda}/4$ short stubs are employed as a dual-band resonator. A CRLH ${\lambda}/4$ short stub is composed of a typical transmission line element as the right-handed component and a high-pass lumped element section as the left-handed component. It is possible to simultaneously obtain open impedances at two separate frequencies by the combination of distinctive phase responses of the right/left-handed components. Negative group delay (NGD) can be obtained at two frequencies by using dual-band characteristics of the CRLH stub. In order to achieve a bandwidth extension, the proposed structure consists of a two-stage dual-band NGDC with different center frequencies connected in a cascade. According to the experiment performed, with wide-band code division multiple access (WCDMA) and worldwide interoperability for microwave access (WiMAX), NGDs of $-3.0{\pm}0.4$ ns and $-3.1{\pm}0.5$ ns are obtained at 2.12~2.16 GHz and 3.46~3.54 GHz, respectively.