• Corrosion Science and Technology
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• 제19권5호
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• pp.265-280
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• 2020

External corrosion of buried pipes can be controlled using both coating and cathodic protection. However, deterioration of the coating can occur due to several reasons. The detection reliabilty of coating flaw detection methods is affected by interference such as metal objects connected to rectifiers and copper grids. When performing parallel direct current voltage gradient (DCVG) inspection, a sine wave form without potential reversal in voltage gradient appears in the area where the interference exists. However, this area may be not identified using existing methods. The objective of this study was to determine the effect of analyzing direction on the reliability of coating flaw detection of pipes buried in soil using a multi-electrode detector. DCVG on the buried pipe was measured along the buried pipe. This measurement parallel to the pipe was repeated. Measured data were analyzed for parallel, vertical, and diagonal directions. The reliability of coating flaw detection was improved by up to 46.4% compared to the conventional method.

• 한국발생생물학회지:발생과생식
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• 제12권2호
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• pp.159-168
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• 2008

Nanog is a newly identified member of the homeobox family of DNA binding transcription factors that functions to maintain the undifferentiated state of stem cells. However, molecular mechanisms underlying the function of Nanog remain largely unknown. To elucidate the regulatory roles of Nanog involved in maintenance of P19 embryonal carcinoma (EC) stem cells, we transfected three small interfering RNA (siRNA) duplexes targeted against different regions of the Nanog gene into P19 cells. The Nanog siRNA-100 duplexes effectively decreased the expression of Nanog up to 30.7% compared to other two Nanog siRNAs, the Nanog siRNA-400 (67.9 %) and -793 (53.0%). When examined by RT-PCR and real-time PCR, the expression of markers for pluripotency such as Fgf4, Oct3/4, Rex1, Sox1 and Yes was downregulated at 48 h after transfection with Nanog siRNA-100. Furthermore, expression of the ectodermal markers, Fgf5 and Isl1 was reduced by Nanog knockdown. By contrast, the expression of other markers for pluripotency such as Cripto, Sox2 and Zfp57 was not affected by Nanog knockdown at this time. On the other hand, the expression of Lif/Stat3 pathway molecules and of the endoderm markers including Dab2, Gata4, Gata6 and the germ cell nuclear factor was not changed by Nanog knockdown. The results of this study demonstrated that the knockdown of Nanog expression by RNA interference in P19 cells was sufficient to modulate the expression of pluripotent markers involved in the self-renewal of EC stem cells. These results provide the valuable information on potential downstream targets of Nanog and add to our understanding of the function of Nanog in P19 EC stem cells.

• Asian-Australasian Journal of Animal Sciences
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• 제23권4호
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• pp.456-464
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• 2010

RNA interference (RNAi) is an acknowledged useful and effective tool to study gene function in various cells. Here, we suppressed the Connexin 43 (Cx 43) gene expression during in vitro development of ovine pre-implantation embryos using the RNAi method. The 353 bp Cx 43 double-stranded RNA was microinjected into in vitro fertilized ovine zygotes, and the levels of target mRNA and protein were investigated. Control groups included uninjected zygotes or those injected with RNase-free water. The dsRNA injection resulted in the specific reduction of Cx 43 transcripts as analyzed by quantitative real-time RT-PCR and decreased protein levels as shown by Western blot analysis at the blastocyst stage. Microinjection of Cx 43 dsRNA led to 20.3%, 21.7% and 34.5% blastocyst rates and 19.2%, 37.5% and 41.3% hatched blastocyst rates in Cx 43 dsRNA-injected, water-injected and uninjected groups, respectively. Then the RNAi could not significantly affect cell number and cell death rates of blastocysts. Therefore, suppression of Cx 43 dsRNA and proteins did not apparently affect the development potential of ovine pre-implantation embryos but may play a role in embryo quality. RNAi technology is a promising approach to study gene function in early ovine embryogenesis.

• Journal of Microbiology and Biotechnology
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• 제22권8호
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• pp.1133-1140
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• 2012

Ribonucleic acid interference (RNAi) inhibits the expression of target genes in a sequence-specific manner, and shows potential for gene knockdown in filamentous fungi, in which the locus-specific gene knockout occurs in low frequency. In this study, the function of the repressor of cellulase expression I (ACEI) was verified in Trichoderma koningii (T. koningii) YC01 through RNAi, and ace1-silenced strains with improved cellulase productivity were obtained. An expression cassette that transcribed the interfering double-stranded RNA (dsRNA) of ace1 was constructed and transformed into T. koningii, and the transformants, in which the expression of ace1 was successfully silenced, were selected. As a result of the ace1 gene silencing, the expression levels of the main cellulase and xylanase genes were elevated, and the enhanced production of total proteins, cellulase, and xylanase was observed in the cultivation. In addition, the down-regulation of ace1 resulted in an increasing expression of xyr1, but no clear variation in the expression of cre1, which suggested that ACEI acted as a repressor of the xyr1 transcription, but was not involved in the regulation of the cre1 expression. The results of this work indicate that ace1 is a valid target gene for enhancing enzyme production in T. koningii, and RNAi is an appropriate tool for improving the properties of industrial fungi.

• Asian Pacific Journal of Cancer Prevention
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• 제17권8호
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• pp.3711-3719
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• 2016

Drawbacks of conventional cancer treatments, with lack of specificity and cytotoxicity using current approaches, underlies the necessity for development of a novel approach, gene-directed cancer therapy. This has provided novel technological opportunities in vitro and in vivo. This review focuses on a member of an apoptosis inhibitor family, survivin, as a valuable target. Not only the gene but also its promoter are applicable in this context. This article is based on a literature survey, with especial attention to RNA interference as well as tumor-specific promoter action. The search engine and databases utilized were Science direct, PubMed, MEDLINE and Google. In addition to cell-cycle modulation, apoptosis inhibition, interaction in cell-signaling pathways, cancer-selective expression, survivin also may be considered as specific target through its promoter as a novel treatment for cancer. Our purpose in writing this article was to create awareness in researchers, emphasizing relation of survivin gene expression to potential cancer treatment. The principal result and major conclusion of this manuscript are that survivin structure, biological functions and applications of RNA interference systems as well as tumor-specific promoter activity are of major interest for cancer gene therapy.

• Asian Pacific Journal of Cancer Prevention
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• 제15권4호
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• pp.1823-1829
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• 2014

Aims: Much evidence suggests that increased glucose metabolism in tumor cells might contribute to the development of acquired chemoresistance. However, the molecular mechanisms are not fully clear. Therefore, we investigated a possible correlation of mRNA expression of HIF-$1{\alpha}$ and GLUT1 with chemoresistance in acute myeloid leukemia (AML). Methods: Bone marrow samples were obtained from newly diagnosed and relapsed AML (M3 exclusion) cases. RNA interference with short hairpin RNA (shRNA) was used to stably silence GLUT1 or HIF-$1{\alpha}$ gene expression in an AML cell line and HIF-$1{\alpha}$ and GLUT1 mRNA expression was measured by real-time quantitative polymerase chain reaction assay (qPCR). Results: High levels of HIF-$1{\alpha}$ and GLUT1 were associated with poor responsiveness to chemotherapy in AML. Down-regulation of the expression of GLUT1 by RNA interference obviously sensitized drug-resistant HL-60/ADR cells to adriamycin (ADR) in vitro, comparable with RNA interference for the HIF-$1{\alpha}$ gene. Conclusions: Our data revealed that over-expression of HIF-$1{\alpha}$ and GLUT1 might play a role in the chemoresistance of AML. GLUT1 might be a potential target to reverse such drug resistance.

• 한국통신학회논문지
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• 제23권7호
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• pp.1677-1688
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• 1998

본 논문에서는 DS-CDMA 시스템의 기지국에 배열안테나를 사용함으로 시스템의 성능향상을 기할 수 있음을 보 여 주고자 한다. 이를 위해 배열안테나를 사용하는 DS-CDMA시스템의 핵심부분인 빔조향장치의 수신기 구조를 제안하고, 이 수신기 구조에서 신호대간섭잡음비(SINR)을 유도하고자 한다. 여기서, 배열안테나에 기인한 CDMA 시스템의 역방향채널의 성능향상은 기지국에서 관찰되는 이동국의 각분포(angular distribution)를 분해할 수 있는 배열안테나를 사용함으로써 주위의 타 이동국으로 부터 오는 간섭의 양을 줄이는 형태로 묘사된다. 각 이동국 혹은 그룹의 이동국들에 관련된 안테나빔의 에너지는 지정된 공간에 제한되며, 이 현상은 배열 안테나의 빔 내부에 존재하는 이동국들에게 타 이동국들이 주는 간섭의 양을 대폭 줄여 주는 효과를 보여 준다. 이러한 배열안테나의 장점을 확인하기 위해, 대표적인 하나의 이동통신 전파환경올 고려하여 신호를 모델링하고 제안된 배열안테나의 수신기에 모델링된 가상신호를 인가한 후 신호대간섭잡음비를 이론적으로 구하였다. 마지막으로 배열안테나의 빔형성 메카니즘의 이해증진과 이 안테나의 사용에 의한 성능향상을 살펴보기 위해, 지향성빔이 어떻게 형성되는가와 이러한 지향성빔이 형성되었을 때 주위 간섭에 의한 신호대간섭잡음비에 관한 컴퓨터 시뮬레이션 결과를 보여준다.

• Elastomers and Composites
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• 제42권3호
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• pp.151-158
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• 2007

최근 들어 전기적, 기계적 성질이 우수한 다중벽탄소나노튜브(Multi-Walled Carbon Nanotubes)/고분자 복합재료에 대한 연구가 활발히 진행 중이다. 본 연구에서는 모듈라 치합형 동방형 회전 이축 압출기(Modular Intermeshing Co-Rotating Twin Screw Extruder, L/D=42)를 이용하여 PMMA/MWNT 복합체를 제조하였다. 이렇게 제조된 PMMA/MWNT 복합체의 표면저항을 측정한 결과 MWNT의 함량이 4 wt% 일 때 $10^4{\Omega}/sq$를 나타내어 전자파차폐(Electronic Magnetic Interference) 물질로 응용할 수 있는 가능성을 확인하였다. 그리고 열중량 분석기 (Thermogravimetric Analysis), 시차주사열량계(Differential Scanning Calorimeter)를 이용한 열적특성, 주사전자현미경(Scanning Electron Microscopy)을 통하여 형태학적 변화를 분석하였다. 또한 유변학적 특성을 알아보기 위해 용융흐름지수(Melt Flow Index)를 측정하였다.

• Nuclear Engineering and Technology
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• 제47권7호
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• pp.791-803
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• 2015

The effective cross sections (XSs) in the direct whole core calculation code nTRACER are evaluated by the equivalence theory-based resonance-integral-table method using the WIMS-based library as an alternative to the subgroup method. The background XSs, as well as the Dancoff correction factors, were evaluated by the enhanced neutron-current method. A method, with pointwise microscopic XSs on a union-lethargy grid, was used for the generation of resonance-interference factors (RIFs) for mixed resonant absorbers. This method was modified by the intermediate-resonance approximation by replacing the potential XSs for the non-absorbing moderator nuclides with the background XSs and neglecting the resonance-elastic scattering. The resonance-escape probability was implemented to incorporate the energy self-shielding effect in the spectrum. The XSs were improved using the proposed method as compared to the narrow resonance infinite massbased method. The RIFs were improved by 1% in $^{235}U$, 7% in $^{239}Pu$, and >2% in $^{240}Pu$. To account for thermal feedback, a new feature was incorporated with the interpolation of pre-generated RIFs at the multigroup level and the results compared with the conventional resonance-interference model. This method provided adequate results in terms of XSs and k-eff. The results were verified first by the comparison of RIFs with the exact RIFs, and then comparing the XSs with the McCARD calculations for the homogeneous configurations, with burned fuel containing a mixture of resonant nuclides at different burnups and temperatures. The RIFs and XSs for the mixture showed good agreement, which verified the accuracy of the RIF evaluation using the proposed method. The method was then verified by comparing the XSs for the virtual environment for reactor applicationbenchmark pin-cell problem, as well as the heterogeneous pin cell containing burned fuel with McCARD. The method works well for homogeneous, as well as heterogeneous configurations.

• 한국정보과학회논문지:정보통신
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• 제36권4호
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• pp.286-296
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• 2009

고밀도 파장 분할 다중화 방식(DWDM: Dense-Wavelength Division Multiplexing) 기반 차세대 광 인터넷 백본망(NGOI: Next Generation Optical Internet)의 주요 연구주제 중 하나는 다양한 멀티미디어 응용 서비스들의 서비스 품질(QoS: Quality-of-Service)을 고려한 멀티캐스트 서비스용 효율적인 라우팅 및 파장할당(RWA: Routing and Wavelength Assignment) 문제이다. 특히, 차세대 광 인터넷 백본망에서 망 대역폭의 효율적인 사용 측면의 RWA 문제는 매우 중요한 요소이다. 그러나 기존의 RWA 알고리즘들은 멀티캐스트 트리 형성 시 발생하는 혼잡상황과 경로에 대한 우선순위를 고려하지 않아 성능이 매우 제한적이다. 따라서 본 논문에서는 이러한 문제를 해결하기 위한 방안으로 멀티캐스트 트리 형성시 발생하는 혼잡경로를 피하고 노드의 우선순위를 고려하는 효율적인 우선순위기반 최소간섭 경로 멀티캐스트 라우팅(PMIPMR - Priority-based Minimum Interference Path Multicast Routing) 알고리즘을 제안한다. 제안된 알고리즘은 시뮬레이션 결과를 통해 파장 사용률과, 파장 채널 사용률 측면에서 기존의 알고리즘과 비교, 제안된 알고리즘의 효율성을 검증한다.