• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2005년도 종합학술발표회 논문집 Vol.15 No.1
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• pp.443-447
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• 2005

The SAR measurement system with stationary probes, presented in this paper, can calculate area SAR value based ell the measured 9 electric field data. By converting obtained area SAR to the volume SAR, the results can be acquired in a few seconds. The system can be very useful tool in the stages of handset development for mobile communication as well as in the handset production line because of its rapid SAR measurement. The system showed good linearity characteristics at 835 MHz of 10 $\sim$ 27 dBm input power range.

• 한국전자파학회논문지
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• 제17권2호
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• pp.221-227
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• 2006

본 논문에서 제안한 probe 고정형 SAR 측정 시스템은 9개의 프로브를 측정 대상체에 꽃아 획득한 전기장 값들로부터 수초 이내에 $1cm^2$ SAR 값을 계산하고, 그 면적 SAR 값으로부터 1g SAR 값을 도출하는 기술로서, 이동통신 단말기의 개발 단계 및 생산 라인에 투입하여 신속하게 SAR 값을 측정하게 해준다. 국제 표준 문서에서 제시한 1g 기준 SAR 값과 측정된 SAR 값을 비교함으로써 제안된 측정 시스템의 타당성을 확인하였다.

• Tribology and Lubricants
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• 제27권6호
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• pp.344-350
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• 2011

Friction and wear behavior of tungsten oxide nanorods (TONs) was investigated using friction force microscopy(FFM) employing colloidal probes instead of conventional sharp tips. Vertically well-ordered TONs with 40 nm diameter, 130 nm length and 100 nm pitch width were synthesized on an anodic aluminium oxide substrate using two step electrochemical anodizing processes. The colloidal probe (diameter 20 ${\mu}m$) attached at the free end of tipless cantilever was oscillated(scanned) against a stationary surface of vertically aligned TONs with various scan speeds (1.2 ${\mu}m/s$, 3.0 ${\mu}m/s$ and 6.0 ${\mu}m/s$) and sliding cycles (100, 200 and 400) under normal load of 800 nN. The friction force and wear depth decreased with the increase of the scan speed. Plastically deformed thin layers were formed and sparsely deposited on the worn nonorod surface. The lower wear rate of the TONs with the longer oscillating cycles was attributed to the decreased real contact pressure due to the increase of real contact area between the colloidal probe and the TONs.

• Journal of Microbiology and Biotechnology
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• 제16권12호
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• pp.1841-1848
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• 2006

Insights into gene expression have the potential for improvement of antibiotic yield and the development of robust production hosts for use in recombinant biomolecule production. $Cubicin^{TM}$ (daptomycin for injection) is a recently approved antibiotic active against many Gram(+) pathogens, including those resistant to methicillin, vancomycin, and fluoroquinolones. Daptomycin is produced as a secondary metabolite by Streptomyces roseosporus. A 128 kb region of DNA including the daptomycin biosynthetic gene cluster (dpt) has been cloned. and sequenced. Using a selected array of nucleic acid probes representing this region, we compared the expression levels of the dpt genes between S. roseosporus wild-type (WT) and derived S. roseosporus high-producer of daptomycin (HP). We observed that the majority of the biosynthetic genes were upregulated in HP compared with WT; a total of 12 genes, including those encoding daptomycin synthetase, showed consistently and significantly higher expression levels, at least 5-fold, in HP compared with WT. In contrast, some genes, flanking the dpt cluster, were expressed at higher levels in the WT strain. The expression of housekeeping genes such as S. roseosporus rpsL, rpsG, and 16S (positive controls) and presumptive intergenic regions in the dpt cluster (negative control) were identical in the two strains. In addition, we compared transcription during the early, mid-log, and early-stationary phases of growth in the HP strain. The same set of genes was upregulated and downregulated under all conditions examined; housekeeping genes showed no relative change in expression level over the periods of growth tested. Analyses of this type would be of value in studies of strain improvement and also for the identification of gene regulation processes that are important for secondary metabolite production.

• Wind and Structures
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• 제34권2호
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• pp.199-213
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• 2022

The current study investigates the dynamic effects in the tornado-structure response of an aeroelastic self-supported lattice transmission tower model tested under laboratory simulated tornado-like vortices. The aeroelastic model is designed for a geometric scale of 1:65 and tested under scaled down tornadoes in the Wind Engineering, Energy and Environment (WindEEE) Research Institute. The simulated tornadoes have a similar length scale of 1:65 compared to the full-scale. An extensive experimental parametric study is conducted by offsetting the stationary tornado center with respect to the aeroelastic model. Such aeroelastic testing of a transmission tower under laboratory tornadoes is not reported in the literature. A multiaxial load cell is mounted underneath the base plate to measure the base shear forces and overturning moments applied to the model in three perpendicular directions. A three-axis accelerometer is mounted at the level of the second cross-arm to measure response accelerations to evaluate the natural frequencies through a free-vibration test. Radial, tangential, and axial velocity components of the tornado wind field are measured using cobra probes. Sensitivity analyses are conducted to assess the variation of the structural dynamic response associated with the location of the tornado relative to the lattice transmission tower. Three different layouts representing the change in the orientation of the tower model relative to the components of the tornado-induced loads are considered. The structural responses of the aeroelastic model in terms of base shear forces, overturning moments, and lateral accelerations are measured. The results are utilized to understand the dynamic response of self-supported transmission towers to the tornado-induced loads.