• 대한전자공학회논문지TC
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• 제46권8호
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• pp.16-21
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• 2009

앞으로 다가올 4G 셀룰러 시스템에서는 OFDM (Orthogonal Frequency Division Multiplexing)이 가장 핵심적인 기술이다. 그러나 셀룰러 시스템 환경에 적용된 OFDM은 인접 셀간의 간섭문제가 심각하게 발생하고 있다. 본 논문에서는 셀룰러 시스템 환경에 적용된 OFDM 기법의 문제점인 인접 셀간의 간섭을 줄이고 4G 시스템 환경에도 적용할 수 있는 ICIC (Inter-Cell Interference Coordination) 기법을 제안하였다. 그리고 최종적으로 제안된 기법의 성능은 모의실험 결과를 통해 분석한다 모의실험은 3GPPP LTE (Long-Term Evolution)의 시스템 레벨 시뮬레이션을 기준으로 간략화하여 수행하였다. 그 결과 약 4dB 정도의 Geometry 성능 향상을 확인할 수 있었다.

• Molecules and Cells
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• 제43권11호
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• pp.899-908
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• 2020

Intrinsically disordered proteins or regions (IDPs or IDRs) are widespread in the eukaryotic proteome. Although lacking stable three-dimensional structures in the free forms, IDRs perform critical functions in various cellular processes. Accordingly, mutations and altered expression of IDRs are associated with many pathological conditions. Hence, it is of great importance to understand at the molecular level how IDRs interact with their binding partners. In particular, discovering the unique interaction features of IDRs originating from their dynamic nature may reveal uncharted regulatory mechanisms of specific biological processes. Here we discuss the mechanisms of the macromolecular interactions mediated by IDRs and present the relevant cellular processes including transcription, cell cycle progression, signaling, and nucleocytoplasmic transport. Of special interest is the multivalent binding nature of IDRs driving assembly of multicomponent macromolecular complexes. Integrating the previous theoretical and experimental investigations, we suggest that such IDR-driven multiprotein complexes can function as versatile allosteric switches to process diverse cellular signals. Finally, we discuss the future challenges and potential medical applications of the IDR research.

• 한국CDE학회논문집
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• 제9권2호
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• pp.122-132
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• 2004

Progressive mesh representation and generation have become one of the most important issues in network-based computer graphics. However, current researches are mostly focused on triangular mesh models. On the other hand, solid models are widely used in industry and are applied to advanced applications such as product design and virtual assembly. Moreover, as the demand to share and transmit these solid models over the network is emerging, the generation and the transmission of progressive solid models depending on specific engineering needs and purpose are essential. In this paper, we present a Cellular Topology-based approach to generating and transmitting progressive solid models from a feature-based solid model for internet-based design and collaboration. The proposed approach introduces a new scheme for storing and transmitting solid models over the network. The Cellular Topology (CT) approach makes it possible to effectively generate progressive solid models and to efficiently transmit the models over the network with compact model size. Thus, an arbitrary solid model SM designed by a set of design features is stored as a much coarser solid model SM/sup 0/ together with a sequence of n detail records that indicate how to incrementally refine SM/sup 0/ exactly back into the original solid model SM = SM/sup 0/.

• 대한전자공학회논문지TC
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• 제44권3호
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• pp.51-60
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• 2007

셀룰러 OFDMA 시스템에서는 인접 셀 간섭이 각 부반송파별로 다른 값을 가진다. 만일 각 부반송파의 간섭의 양의 추정이 가능하다면 채널 복호기에 입력되는 데이터의 크기를 간섭의 양에 반비례하도록 조절함으로써 성능을 향상시킬 수 있다. 전통적인 셀룰러 시스템들이 셀간 간섭의 영향을 완화시키기 위하여 간섭의 평균화 기술을 선호하는데 반해서 본 논문에서는 셀간 간섭 추정이 가능하다고 가정할 때 적은 수의 부반송파에 간섭을 집중시킴으로써 시스템 성능을 크게 향상시킬 수 있음을 보인다. 셀간 간섭의 추정이 이루어지지 않는 경우, 특정 부반송파에 큰 간섭이 오지 않도록 간섭을 평균화하는 것이 유리한 반면, 셀간 간섭의 추정이 가능한 경우에는 간섭의 평균화를 사용하는 것보다 간섭의 집중화를 사용하는 것이 더 이득을 얻을 수 있다.

• Journal of Communications and Networks
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• 제2권1호
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• pp.46-57
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• 2000

Ongoing standardization effort on 3G cellular system in 3GPP (UNTS) is based on GPRS core network and promises a global standard for systems capable of offering ubiquitous access to internet for mobile users. Considered radio access systems(FDD CDMA, TDD CDMA, and EDGE) are optimized for robust mobile use. However, there are alternative relatively high-rate radio interfaces being standardized for WLAN (IEEE802.11 and HIPER-LAN/2) which are capable of delivering significantly higher data rates to static or semi-static terminals with much less overhead. Also WPANs(BLUETOOTH, IEEE802.15), which will be present in virtually every mobile handset in the near future, are offering low cast and considerable access data rate and thus are very attractive for interworking scenarios. The prospect of using these interfaces as alternative RANs inthe modular UMTS architecture is very promising. Additionally, the recent inclusion of M-IP in the UMTS R99 standard opens the way for IP-level interfacing to the core network. This article offers an overview into WLAN-Cellular interworking. A brief overview of GPRS, UMTS cellular architectures and relevant WLAN standards is given. Possible interworking architectures are presented.

• BMB Reports
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• 제29권5호
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• pp.417-422
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• 1996

In clonal sublines with different metastatic ability derived from Dunning rat prostate tumor, phosphoamino acid levels of cellular proteins were determined. Cell lines with high metastatic ability exhibited 5-fold higher phosphotyrosine level than did cell lines with low metastatic ability, while the contents of phosphoserine and phosphothreonine were similar among cell lines examined, All cell lines showed similar activities of protein tyrosine kinases as well as overall protein kinases. Phosphotyrosine protein phosphatase (PTPP) activities of the cells with high metastatic ability were very low, compared to those of the cells with low metastatic ability, suggesting that the different phosphotyrosine levels among the cell lines were due to the difference in PTPP activities rather than protein tyrosine kinase activities. Cellular activities of prostatic acid phosphatase (PAcP), which has been reported to possess phosphotyrosine protein phosphatase activity, were shown to be inversely related to the phosphotyrosine levels and metastatic abilities of the prostate tumor cells, These results suggest that cellular PAcP activity, regulating phosphotyrosine levels of cellular proteins, is closely connected with the metastatic process in prostate tumor cells and can be utilized as a good biochemical marker for the diagnosis of metastasis of prostate tumor.

• 한국통신학회논문지
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• 제28권3C호
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• pp.327-335
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• 2003

Cellular Automata는 자연계의 현상 현상이 국부적인 관계에 의해 완전히 표현될 수 있는 이상적인 동적 시스템이다. 본 논문에서는 Cellular Automata의 특성을 가지는 Potts Automata를 이용한 잡음 제거 및 에지 추출 알고리즘을 제안한다. 본 방법은 대상영상에 대한 특징을 그대로 보존하면서 천이규칙에 따라 국부적으로 밝기값의 차이를 증가 및 감소시킨다. 이러한 Automata는 순차적이고 병렬적인 움직임을 가지고 Lyapunov 함수를 만족한다. 제안한 천이규칙은 랜덤잡음을 가진 대상영상에 대해 빠른 수련속도를 가지고 안정적인 결과를 나타낸다. 실험을 통해 본 방법의 유효성을 확인한다.

• Molecules and Cells
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• 제42권7호
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• pp.546-556
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• 2019

Protein phosphatase 4 (PP4) is a crucial protein complex that plays an important role in DNA damage response (DDR), including DNA repair, cell cycle arrest and apoptosis. Despite the significance of PP4, the mechanism by which PP4 is regulated remains to be elucidated. Here, we identified a novel PP4 inhibitor, protein phosphatase 4 inhibitory protein (PP4IP) and elucidated its cellular functions. PP4IP-knockout cells were generated using the CRISPR/Cas9 system, and the phosphorylation status of PP4 substrates (H2AX, KAP1, and RPA2) was analyzed. Then we investigated that how PP4IP affects the cellular functions of PP4 by immunoprecipitation, immunofluorescence, and DNA double-strand break (DSB) repair assays. PP4IP interacts with PP4 complex, which is affected by DNA damage and cell cycle progression and decreases the dephosphorylational activity of PP4. Both overexpression and depletion of PP4IP impairs DSB repairs and sensitizes cells to genotoxic stress, suggesting timely inhibition of PP4 to be indispensable for cells in responding to DNA damage. Our results identify a novel inhibitor of PP4 that inhibits PP4-mediated cellular functions and establish the physiological importance of this regulation. In addition, PP4IP might be developed as potential therapeutic reagents for targeting tumors particularly with high level of PP4C expression.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권5호
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• pp.1929-1943
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• 2021

Millimeter wave (mmWave) communication based on the wide bandwidth of >28 GHz is one of the key technologies for cellular-connected unmanned aerial vehicles (UAVs). The selection of mmWave beams in such cellular-connected UAVs is challenging and critical, especially when downlink transmissions toward aerial user equipment (UE) suffer from poor signal-to-interference-plus-noise ratio (SINR) more often than their terrestrial counterparts. This study proposed a coordinated mmWave beam selection scheme using fingerprint for cellular-connected UAV. The scheme comprises fingerprint database configuration and coordinated beam selection. In the fingerprint database configuration, the best beam index from the serving cell and interference beam indexes from neighboring cells are stored. In the coordinated beam selection, the best and interference beams are determined using the fingerprint database information instead of performing an exhaustive search, and the coordinated beam transmission improves the SINR for aerial UEs. System-level simulations assess the UAV effect based on the third-generation partnership project-new radio mmWave and UAV channel models. Simulation results show that the proposed scheme can reduce the overhead of exhaustive search and improve the SINR and spectral efficiency.

• Molecules and Cells
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• 제45권1호
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• pp.26-32
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• 2022

Living cells generate, sense, and respond to mechanical forces through their interaction with neighboring cells or extracellular matrix, thereby regulating diverse cellular processes such as growth, motility, differentiation, and immune responses. Dysregulation of mechanosensitive signaling pathways is found associated with the development and progression of various diseases such as cancer. Yet, little is known about the mechanisms behind mechano-regulation, largely due to the limited availability of tools to study it at the molecular level. The recent development of molecular tension probes allows measurement of cellular forces exerted by single ligand-receptor interaction, which has helped in revealing the hitherto unknown mechanistic details of various mechanosensitive processes in living cells. Here, we provide an introductory overview of two methods based on molecular tension probes, tension gauge tether (TGT), and molecular tension fluorescence microscopy (MTFM). TGT utilizes the irreversible rupture of double-stranded DNA tether upon application of force in the piconewton (pN) range, whereas MTFM utilizes the reversible extension of molecular springs such as polymer or single-stranded DNA hairpin under applied pN forces. Specifically, the underlying principle of how molecular tension probes measure cell-generated mechanical forces and their applications to mechanosensitive biological processes are described.