• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2010년도 추계학술대회 논문집
• /
• pp.297-298
• /
• 2010

• 한국공간구조학회논문집
• /
• 제4권3호
• /
• pp.49-56
• /
• 2004

본 논문은 철근콘크리트 건물의 전단해석을 위하여 변환각 트러스 모델(TATM)을 사용하여 전단철근변형률과 전단균열폭과 같은 철근콘크리트 부재의 전단변형을 예측하였다. 철근콘크리트 부재의 전단변형에 대한 TATM의 타당성을 검토하기 위하여 서로 다른 전단경간비를 가지는 4개의 RC 보를 제작하고 전단 실험하였으며, 이 실험결과를 MCFT(Response- 2000), RA-STM, FA-STM 및 TATM에 의한 해석결과와 비교하였다. 제안된 모델 TATM은 다른 트러스 모델보다 전단응력-전단철근변형률 관계와 전단응력-전단균열폭 관계를 더 잘 예측하였다.

• Journal of Microbiology and Biotechnology
• /
• 제26권9호
• /
• pp.1605-1612
• /
• 2016

Quinolone-resistant Salmonella strains were isolated from patient samples, and several quinolone-sensitive strains were used to analyze mutations in the quinolone resistance-determining region (QRDR) of gyrA, gyrB, parC, and parE and to screen for plasmid-mediated quinolone resistance. Among the 21 strains that showed resistance to nalidixic acid and ciprofloxacin (MIC 0.125-2.0 μg/ml), 17 strains had a mutation in QRDR codon 87 of gyrA, and 3 strains had a single mutation (Ser83 → Phe). Another cause of resistance, efflux pump regulation, was studied by examining the expression of acrB, ramA, marA, and soxS. Five strains, including Sal-KH1 and Sal-KH2, showed no increase in relative expression in an analysis using the qRT-PCR method (p < 0.05). In order to determine the genes involved in the resistance, the Sal-9 isolate that showed decreased susceptibility and did not contain a mutation in the gyrA QRDR was used to make the STM (MIC 8 μg/ml) and STH (MIC 16 μg/ml) ciprofloxacin-resistant mutants. The gyrA QRDR Asp87 → Gly mutation was identified in both the STM and STH mutants by mutation analysis. qRT-PCR analysis of the efflux transporter acrB of the AcrAB-TolC efflux system showed increased expression levels in both the STM (1.79-fold) and STH (2.0-fold) mutants. In addition, the expression of the transcriptional regulator marA was increased in both the STM (6.35-fold) and STH (21.73-fold) mutants. Moreover, the expression of soxS was increased in the STM (3.41-fold) and STH (10.05-fold) mutants (p < 0.05). Therefore, these results indicate that AcrAB-TolC efflux pump activity and the target site mutation in gyrA are involved in quinolone resistance.

• Bulletin of the Korean Chemical Society
• /
• 제27권3호
• /
• pp.403-406
• /
• 2006

The surface structure and electrochemical behavior of self-assembled monolayers (SAMs) formed by aromatic thiols on Au(111) were investigated by scanning tunneling microscopy (STM) and cyclic voltammetry. Benzenethiol (BT) forms disordered phases on Au(111) which are composed of many bright domains, while benzyl mercaptan (BM), with a methylene unit between the aromatic group and sulfur atom, forms twodimensional ordered SAMs on Au(111). In addition, two phase-separated domains consisting of disordered and ordered phases were observed in binary SAMs formed from a 1 : 1 mixed ethanol solution of BT and BM. From STM and CV measurements, we found that the blocking efficiency of aromatic thiol SAMs coated on an Au(111) electrode for an electron transfer reaction decreases as the structural order of the SAMs increases. Molecular-scale STM and CV results obtained here will be very useful in designing functional SAMs for further applications, such as the improvement of corrosion passivation of Au(111) on an aromatic thiolmodified Au(111) surface.

• Bulletin of the Korean Chemical Society
• /
• 제32권8호
• /
• pp.2623-2627
• /
• 2011

We investigated the surface structure and wetting behavior of octaneselenolate self-assembled monolayers (SAMs) on Au(111) formed in a 50 ${\mu}M$ ethanol solution according to immersion time, using scanning tunneling microscopy (STM) and an automatic contact angle (CA) goniometer. Closely-packed, well-ordered alkanethiol SAMs would form as the immersion time increased; unexpectedly, however, we observed the structural transition of octaneselenolate SAMs from a molecular row phase with a long-range order to a disordered phase with a high density of vacancy islands (VIs). Molecularly resolved STM imaging revealed that the missing-row ordered phase of the SAMs could be assigned as a $(6{\times}{\surd}3)R30^{\circ}$ superlattice containing three molecules in the rectangular unit cell. In addition, CA measurements showed that the structural order and defect density of VIs are closely related to the wetting behaviors of octaneselenolate SAMs on gold. In this study, we clearly demonstrate that interactions between the headgroups and gold surfaces play an important role in determining the physical properties and surface structure of SAMs.

• 대한기계학회논문집
• /
• 제17권7호
• /
• pp.1731-1739
• /
• 1993

An application of Scanning Tunneling Microscopy(STM) is investigated for the measurement of 3-dimensional profiles of the macro-machined patterns of which critical dimensions lie in the range of submicrometers. Special emphasis of this investigation is given to extending the measuring ranges of STM upto the order of several micrometers while maintaining superb nanometer measuring resolution. This is accomplished by correcting hysteresis effects of piezoelectric actuators by using non-linear compensation models. Detailed aspects of design and control of a prototype measurement system are described with some actual measuring examples in which fine It patterns can successfully be traced with a resolution of 1 nanometer over a surface range of $4{\times}2$ micrometers.

• Bulletin of the Korean Chemical Society
• /
• 제22권2호
• /
• pp.213-218
• /
• 2001

Presented are the STM images of self-assembled monolayer of 2-mercaptoethanol on Au(111). Striped structures of ($6{\times}3_{\frac{1}{2}}$), ($5{\times}3_{\frac{1}{2}}$), ($4{\times}3_{\frac{1}{2}}$) and compact-($5{\times}3_{\frac{1}{2}}$) were observed after annealing at $80^{\circ}C.$ Analysis of the ordered structures revealed that the basic fundamental units of the ordered structures were three crystallographically non-equivalent ($3_{\frac{1}{2}}{\times}3_{\frac{1}{2}}$) $R30^{\circ}$ assemblies, and that the way of combination of the assemblies produced the four different structures. The($6{\times}3_{\frac{1}{2}}$) structure ( $\theta$ = 0.33) was composed of one ($3_{\frac{1}{2}}{\times}3_{\frac{1}{2}}$)$R30^{\circ}$ assembly, while the ($5{\times}3_{\frac{1}{2}}$) ( $\theta$ = 0.30) and ($4{\times}3_{\frac{1}{2}}$) ( $\theta$ = 0.38) structures were consisted of two ($3_{\frac{1}{2}}{\times}3_{\frac{1}{2}}$) $R30^{\circ}$ assemblies, separated by 5a and 4a, respectively. Furthermore, the compact-(5X 3½) structure ( $\theta$ = 0.50) was obtained by overlapping three ($3_{\frac{1}{2}}{\times}3_{\frac{1}{2}}$) $R30^{\circ}$ assemblies. In spite of the diversity in the adsorption structures, all the adsorption sites of 2-mercaptoethanol were fundamentally identical. On the other hand, the unannealed primitive SAM of 2-mercaptoethanol was characterized by two observations: a short-range order keeping the adsorbed molecules at approximately $3_{\frac{1}{2}}$ a and the small domains of the striped structures supporting that the observed surface structures on the annealed surface were the extension of the primitive layer of 2-mercaptoethanol. Comparing these observations with the already published structures of ethanthiol, it was concluded that the interaction between the hydroxyl groups of 2-mercaptoethanol might play a significant role in the adsorption step of 2-mercaptoethanol on Au(111) to organize the adsorption structures different from those of ethanthiol.

• 한국통신학회논문지
• /
• 제19권11호
• /
• pp.2081-2093
• /
• 1994

본 연구에서는 DMR(Digital Microwave Radio) STM-1 신호전송을 위한 CCTTT G. 707 SDH(Synchronous Digital Hierachy) 제 1 레벨인 155Mbps 속도의 64 QAM 복조기를 설계, 구현하였다. 복조기 전반의 성능을 좌우하는 carrier recovery는 8 비트 A/D 변환기를 이용한 decision feedback carrier recovery 방식을 이용하였다. 또한 PSF(Pulse Shaping Filter)는 7차의 elliptic 필터를 이용하였다. Carrier recovery 회로는 8bit의 변환 데이터 중에서 MSB 3 bit는 데이타로 이용하고 나머지 하위 비트들은 에러성분 검출을 위한 제어신호로 이용되는 디지틀방식 및 전압제어 수정발진기와 적분기는 아나로그 방식을 이용하는 hybrid 형태로 설계, 구현하여 안정한 복조성능을 얻었다.

• 전자공학회논문지A
• /
• 제33A권3호
• /
• pp.18-27
• /
• 1996

By integrating WDM to OPS unit which plays an improtant role for the reliability of CPN, we made it possible to provide CATV, VOD, and high-speed data services simultaneously and to meet easily the requirements for new services in the future. For the design of optimal system, the link analysis of power budget has been perfomred. Also, the prototyped system has been tested with STM-1 level signals to confirm functions such as transmission, distribution, and protection. The results proved that when occurred out-of-order or recovery of ONU, the system did the pertinent switching with minimum loss for high-speed data services. Also for video distribution services, the system has distributed STM-1 level signals sucessfully.

• 한국정보시스템학회지:정보시스템연구
• /
• 제30권3호
• /
• pp.201-216
• /
• 2021

Purpose The purpose of this study is to analyze the trend of patent technology in textile materials using text mining methodology based on Dynamic Embedded Topic Model and Structural Topic Model. It is expected that this study will have positive impact on revitalizing and developing textile materials industry as finding out technology trends. Design/methodology/approach The data used in this study is 866 domestic patent text data in textile material from 1974 to 2020. In order to analyze technology trends from various aspect, Dynamic Embedded Topic Model and Structural Topic Model mechanism were used. The word embedding technique used in DETM is the GloVe technique. For Stable learning of topic modeling, amortized variational inference was performed based on the Recurrent Neural Network. Findings As a result of this analysis, it was found that 'manufacture' topics had the largest share among the six topics. Keyword trend analysis found the fact that natural and nanotechnology have recently been attracting attention. The metadata analysis results showed that manufacture technologies could have a high probability of patent registration in entire time series, but the analysis results in recent years showed that the trend of elasticity and safety technology is increasing.