• 치위생과학회지
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• 제18권2호
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• pp.130-135
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• 2018

본 연구는 osteomac과 골세포가 골조직 개조과정에서 하는 역할을 조사하고자 수학적 모델링 방법을 사용하였다. 2013년에 발표된 Graham's model을 기반으로 하고 osteomac을 해당 네트워크에 추가하여 각 링크의 파라미터와 상미분방정식을 작성하였다. 컴퓨터 시뮬레이션 결과 osteomac과 골세포의 효율성이 일정 수치 이하인 경우 골조직 개조가 안정적이지 않고 감소하는 방향으로 이동하였다. 골세포의 효율성은 일정 수치 이상이 되어야 골조직 개조에도 골량이 유지되었으며 osteomac의 효율성의 수치가 증가함에 따라 골량도 함께 증가하는 것을 볼 수 있었다. Osteomac의 효율성이 골조직 개조와 골량 유지에 많은 영향을 미칠 수 있음을 제안한다.

• 한국정보통신학회논문지
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• 제6권7호
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• pp.1069-1072
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• 2002

고도로 발달된 정보화 시대에서 우리가 원하는 정보를 짧은 시간, 적은 비용으로 서로 주고 받기 위해서는 이것에 맞는 시스템이 요구된다. 반도체 chip의 대용량과 고속화됨으로써 TTL, ,LVTTL등이 data 100Mbps 정도를 안전하게 전달 할 수 있는 능력이 있으므로 그 이상을 전달할 수 있는 새로운 Logic level이 필요하게 되었다. 이에 맞추어 신호 level의 여러 가지 중 본 논문에서는 Virtex II XC2V 1000 FF896을 이용하여 Differential I/O LVDS( Low Voltage Differential Signaling ) level 특성을 clock, Data와의 전송관계를 Eye_Pattern을 통해 살펴보았다.

• ETRI Journal
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• 제35권5호
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• pp.827-837
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• 2013

In this paper, we present wideband common-mode (CM) noise suppression using a vertical stepped impedance electromagnetic bandgap (VSI-EBG) structure for high-speed differential signals in multilayer printed circuit boards. This technique is an original design that enables us to apply the VSI-EBG structure to differential signals without sacrificing the differential characteristics. In addition, the analytical dispersion equations for the bandgap prediction of the CM propagation in the VSIEBG structure are extracted, and the closed-form expressions for the bandgap cutoff frequencies are derived. Based on the dispersion equations, the effects of the impedance ratio, the EBG patch length, and via inductances on the bandgap of the VSI-EBG structure for differential signals are thoroughly examined. The proposed dispersion equations are verified through agreement with the full-wave simulation results. It is experimentally demonstrated that the proposed VSI-EBG structure for differential signaling suppresses the CM noise in the wideband frequency range without degrading the differential characteristics.

• BMB Reports
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• 제41권6호
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• pp.479-484
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• 2008

In the present study, we demonstrate that ephrin-A5 is able to induce a transient increase of MAP kinase activity in PC12 cells. However, the effects of ephrin-A5 on the MAP kinase signaling pathway are about three-fold less than that of EGF. In addition, we demonstrate that EphA4 is the only Eph member expressed in PC12 cells, and that tyrosine phosphorylation induced by ephrin-A5 treatment is consistent with the magnitude and longevity of MAP kinase activation. Experiments using the Ras dominant negative mutant N17Ras reveal that Ras plays a pivotal role in ephrin-A5-induced MAP kinase activation in PC12 cells. Importantly, we found that the EphA4 receptor is rapidly internalized by endocytosis upon engagement of ephrin-A5, leading to a subsequent reduction in the MAP kinase activation. Together, these data suggest a novel regulatory mechanism of differential Ras-MAP kinase signaling kineticsexhibited by the forward signaling of EphA4 in PC12 cells.

• 한국전자파학회논문지
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• 제20권2호
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• pp.193-199
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• 2009

본 논문에서는 microstrip line 구조를 가지는 differential pair의 2 drop 구조에 대한 임피던스 해석을 reflection theory를 바탕으로 분석하였다. 또한 시뮬레이션을 통한 transient 해석을 통해 임피던스 해석의 타당성을 검증하였다. 위와 같은 해석 과정을 통하여 다양한 drop 구조의 신호 전달 특성을 이해할 수 있다. 임피던스 해석을 바탕으로 2 drop 구조 해석을 통하여 최적의 signal integrity를 가지는 설계 기법을 제안하였고, circuit 시뮬레이션 해석(Ansoft designer)을 통해 signal integrity 효과를 검증하였다.

• 대한의생명과학회지
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• 제18권3호
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• pp.181-192
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• 2012

Toll-like receptors (TLRs) induce innate immune responses that are essential for host defense against invading microbial pathogens. In general, TLRs have two major downstream signaling pathways; myeloid differential factor 88 (MyD88) and Toll/IL-1R domain-containing adaptor inducing IFN-${\beta}$ (TRIF) leading to the activation of NF-${\kappa}B$ and IRF3. Numerous studies demonstrated that certain phytochemicals possessing anti-inflammatory effects inhibit NF-${\kappa}B$ activation induced by pro-inflammatory stimuli including lipopolysaccharide and tumor necrosis factor-${\alpha}$ ($TNF{\alpha}$). However, the direct molecular targets for such anti-inflammatory phytochemicals are not fully identified. In this paper, we will discuss about the molecular targets of phytochemicals in TLRs signaling pathways. These results present a novel anti-inflammatory mechanism of phytochemicals in TLRs signaling.

• Mycobiology
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• 제39권4호
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• pp.249-256
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• 2011

Microorganisms are significantly affected when the ambient pH of their environment changes. They must therefore be able to sense and respond to these changes in order to survive. Previous investigators have studied various fungal species to define conserved pH-responsive signaling pathways. One of these pathways, known as the Pal/Rim pathway, is activated in response to alkaline pH signals, ultimately targeting the PacC/Rim101 transcription factor. Although the central signaling components are conserved among divergent filamentous and yeast-like fungi, there is some degree of signaling specificity between fungal species. This specificity exists primarily in the downstream transcriptional targets of this pathway, likely allowing differential adaptation to species-specific environmental niches. In this review, the role of the Pal/Rim pathway in fungal pH response is discussed. Also highlighted are functional differences present in this pathway among human fungal pathogens, differences that allow these specialized microorganisms to survive in the various micro-environments of the infected human host.

• 한국정보통신학회논문지
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• 제12권5호
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• pp.879-886
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• 2008

본 논문에서는 저전압 차동 신호(Low-Voltage Differential Signaling, LVDS) 전송방식의 응용을 위한 차동 전송 접속 경로의 분석 및 설계 최적화 방법을 제안한다. 차동 전송 경로 및 저전압 스윙 방법의 발전으로 인해 LVDS 방식은 데이터 통신 분야, 고해상도 디스플레이 분야, 평판 디스플레이 분야에서 매우 적은 소비전력, 개선된 잡음 특성 및 고속 데이터 전송률을 제공한다. 본 논문은 차동 유연성 인쇄회로 보드(flexible printed circuit board, FPCB) 전송선에서 선폭, 선두께 및 선 간격과 같은 전송선 설계 변수들의 최적화 기법을 이용하여 직렬 접속된 전송선에서 발생하는 임피던스 부정합과 신호왜곡을 감소시키기 위해 개선 모델과 새로이 개발된 수식을 제안한다. 이러한 차동 FPCB 전송선의 고주파 특성을 평가하기 위해 주파수 영역에서 전파(full-wave) 전자기 시뮬레이션, 시간영역 시뮬레이션 및 S 파라미터 시뮬레이션을 각각 수행하였다. $17.5{\mu}m$과 $35{\mu}m$의 전송선의 경우, 전극 폭에서의 약 10% 변화가 차동 임피던스에서의 약 6%와 5.6%의 변화를 각각 보였으나, 전송선 간 간격은 차동 및 특성 임피던스에서의 영향을 주지 않음을 확인하였다. 또한 전송선 간격이 증가할수록 상호 인덕턴스 및 커패시턴스가 감소하기 때문에 누화 잡음을 감소시키기 위해 신호 전송선간의 간격을 $180{\mu}m$ 이상 유지 해야함을 확인하였다.

• Molecular & Cellular Toxicology
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• 제4권4호
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• pp.267-277
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• 2008

Benzene and ethylbenzene (BE), the volatile organic compounds (VOCs) are common constituents of cleaning and degreasing agents, paints, pesticides, personal care products, gasoline and solvents. VOCs are evaporated at room temperature and most of them exhibit acute and chronic toxicity to human. Chronic exposure of benzene is responsible for myeloid leukemia and also ethylbenzene is also recognized as a possible carcinogen. To evaluate the BE effect on human, whole human genome 35 K oligonucleotide microarray were screened for the identification of the differential expression profiling. We identified 280 up-regulated and 201 down-regulated genes changed by more than 1.5 fold by BE exposure. Functional analysis was carried out by using DAVID bioinformatics software. Clustering of these differentially expressed genes were associated with immune response, cytokine-cytokine receptor interaction, toll-like signaling pathway, small cell lung cancer, immune response, apoptosis, p53 signaling pathway and MAPKKK cascade possibly constituting alternative or subordinate pathways of hematotoxicity and immune toxicity. Gene ontology analysis methods including biological process, cellular components, molecular function and KEGG pathway thus provide a fundamental basis of the molecular pathways through BEs exposure in human lymphoma cells. This may provides a valuable information to do further analysis to explore the mechanism of BE induced hematotoxicity.

• Journal of applied mathematics & informatics
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• 제31권3_4호
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• pp.457-467
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• 2013

There exist many deterministic models for signaling pathways in systems biology. However the models do not consider the stochastic properties of the pathways, which means the models fit well with experimental data in certain situations but poorly in others. Incorporating stochasticity into deterministic models is one way to handle this problem. In this paper the way is used to produce stochastic models based on the deterministic differential equations for the published extracellular signal-regulated kinase (ERK) pathway. We consider strong convergence and stability of the numerical approximations for the stochastic models.