• 한국통신학회논문지
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• 제33권6A호
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• pp.666-675
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• 2008

현재 IEEE 802.22에서는 스펙트럼 사용 효율을 높이고 새로운 무선 통신 서비스 도입을 용이하게 하기 위한 연구가 활발히 진행되고 있다. 또한 TV 대역을 대상으로 주파수를 공유하고자 하는 Cognitive Radio를 적용한 WRAN 시스템에 대한 표준화가 진행되고 있다. 본 논문에서는 WRAN 시스템에서의 주파수 효율과 채널 용량을 극대화하구 인접 셀 간 간섭을 최소화할 수 있도록 하는 효율적인 주파수 할당 기법과 최적 전력 제어 기법인 PCPWF(Partial Constant Power Water Filling)을 제시하였다. 또한 제안된 동적 셀 설계(dynamic cell plan)를 통해 가용할 수 있는 채널을 효율적으로 할당하여 전체 시스템의 데이터 처리율(throughput)과 형평성을 극대화하였으며, 제안된 기법의 효용성을 검증하기 위해서 시뮬레이션 결과도 수록하였다.

• 한국통신학회논문지
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• 제41권12호
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• pp.1721-1735
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• 2016

Power-efficient base station (BS) operation is one of the important issues in future green cellular networks. Previously well-known BS operation schemes, the cell zooming scheme and the cell wilting and blossoming scheme, require tight cooperation between cells in cellular networks. With the previous schemes, the non-cooperative BSs of a serving cell and neighboring cells could cause coverage holes between the cells, thereby seriously degrading the quality of service as well as the power saving efficiency of the cellular networks. In this paper, we propose a novel power-efficient BS operation scheme for green downlink heterogeneous cellular networks, in which the networks virtually adjust the coverage of a serving macrocell (SM) and neighboring macrocells (NMs) without adjusting the transmission power of the BSs when the SM is lightly loaded, and the networks turn off the BS of the SM when none of active users are associated with the SM. Simulation results show that our proposed scheme significantly improves the power saving efficiency without degrading the quality of service (e.g., system throughput) of a downlink heterogeneous LTE network and outperforms the previous schemes in terms of system throughput and power saving efficiency. In particular, with the proposed scheme, macrocells are able to operate independently without the cooperation of a SM and NMs for green heterogeneous cellular networks.

• Archives of Pharmacal Research
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• 제23권3호
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• pp.246-251
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• 2000

In most tissues, apoptosis plays a pivotal role in normal development and for regulating cell number, thus inappropriate apoptosis underlies a variety of diseases. Caspase-3 is one of a family of caspases that are mainly involved in the apoptotic signal transduction pathway, where caspase-3 acts as an effect molecule to proteolytically cleave intracellular substrates that are necessary for maintaining cell survival. Recent evidences show that apoptotic cell death can be blocked by inhibiting caspase-3, suggesting its inhibitors have potential to be therapeutic drugs for the diseases related with inappropriate apoptosis. We have established a screening system to search caspase-3 inhibitors from chemical libraries stocked in our institute. The enzyme assay is configured entirely in 96-well format, which is easily adapted for high throughput screening. Before performing mass screening, 80 in-house compounds were screened as a preliminary experiment, and we found that morin hydrate inhibited caspase-3 by 66.4 % at the final concentration of 20 ${\mu}g/m{\ell}$.

• Molecules and Cells
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• 제44권3호
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• pp.136-145
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• 2021

Senescent cells that gradually accumulate during aging are one of the leading causes of aging. While senolytics can improve aging in humans as well as mice by specifically eliminating senescent cells, the effect of the senolytics varies in different cell types, suggesting variations in senescence. Various factors can induce cellular senescence, and the rate of accumulation of senescent cells differ depending on the organ. In addition, since the heterogeneity is due to the spatiotemporal context of senescent cells, in vivo studies are needed to increase the understanding of senescent cells. Since current methods are often unable to distinguish senescent cells from other cells, efforts are being made to find markers commonly expressed in senescent cells using bulk RNA-sequencing. Moreover, single-cell RNA (scRNA) sequencing, which analyzes the transcripts of each cell, has been utilized to understand the in vivo characteristics of the rare senescent cells. Recently, transcriptomic cell atlases for each organ using this technology have been published in various species. Novel senescent cells that do not express previously established marker genes have been discovered in some organs. However, there is still insufficient information on senescent cells due to the limited throughput of the scRNA sequencing technology. Therefore, it is necessary to improve the throughput of the scRNA sequencing technology or develop a way to enrich the rare senescent cells. The in vivo senescent cell atlas that is established using rapidly developing single-cell technologies will contribute to the precise rejuvenation by specifically removing senescent cells in each tissue and individual.

• Journal of Communications and Networks
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• 제13권1호
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• pp.32-42
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• 2011

Frequency reuse among relay stations (RSs) in a down-link access zone is widely adopted for throughput enhancement in IEEE 802.16j relay networks. Since the areas covered by the RSs or the base station (BS) may overlap, some mobile stations (MSs) at the border between two neighboring transmitting stations (RS or BS) using an identical frequency band may suffer severe interference or outage. This co-channel interference within the cell degrades the quality of service (QoS) fairness among the MSs as well as the system throughput. Exclusive use of a frequency band division (orthogonal resource allocation) among RSs can solve this problem but would cause degradation of the system throughput. We observe a trade-off between system throughput and QoS fairness in the previously reported schemes based on frequency reuse. In this paper, we propose a new frequency reuse scheme that achieves high system throughput with a high fairness level in QoS, positioning our scheme far above the trade-off curve formed by previous schemes. We claim that our scheme is beneficial for applications in which a high QoS level is required even for the MSs at the border. Exploiting the features of a directional antenna in the BS, we create a new zone in the frame structure. In the new zone, the RSs can serve the subordinate MSs at the border and prone to interference. In a 3-RS topology, where the RSs are located at points $120^{\circ}$ apart from one another, the throughput and Jain fairness index are 10.64 Mbps and 0.62, respectively. On the other hand, the throughput for the previously reported overlapped and orthogonal allocation schemes is 8.22 Mbps (fairness: 0.48) and 3.99 Mbps (fairness: 0.80), respectively. For a 6-RS topology, our scheme achieves a throughput of 18.38 Mbps with a fairness of 0.68; however, previous schemes with frequency reuse factors of 1, 2, 3, and 6 achieve a throughput of 15.24 Mbps (fairness: 0.53), 12.42 Mbps (fairness: 0.71),8.84 Mbps (fairness: 0.88), and 4.57 Mbps (fairness: 0.88), respectively.

• Journal of Microbiology and Biotechnology
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• 제26권2호
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• pp.213-225
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• 2016

To reduce attrition in drug development, it is crucial to consider the development and implementation of translational phenotypic assays as well as decipher diverse molecular mechanisms of action for new molecular entities. High-throughput fluorescence and confocal microscopes with advanced analysis software have simplified the simultaneous identification and quantification of various cellular processes through what is now referred to as high-content screening (HCS). HCS permits automated identification of modifiers of accessible and biologically relevant targets and can thus be used to detect gene interactions or identify toxic pathways of drug candidates to improve drug discovery and development processes. In this review, we summarize several HCS-compatible, biochemical, and molecular biology-driven assays, including immunohistochemistry, RNAi, reporter gene assay, CRISPR-Cas9 system, and protein-protein interactions to assess a variety of cellular processes, including proliferation, morphological changes, protein expression, localization, post-translational modifications, and protein-protein interactions. These cell-based assay methods can be applied to not only 2D cell culture but also 3D cell culture systems in a high-throughput manner.

• 한국위성정보통신학회논문지
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• 제12권4호
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• pp.162-165
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• 2017

최근 데이터 처리용량 증대에 대한 수요를 만족시키기 위해서, 전파 자원을 효율적으로 사용하고 네트워크 용량을 증대시키는 연구가 진행되고 있다. 현재 차세대 5G 이동통신망의 핵심적인 기술로서 소형 셀 네트워크, 밀리미터파대역 그리고 빔포밍이 존재한다. 그러나 밀리미터파대역의 전파특성이 기존에 사용되고 있는 대역의 것과 상이하기 때문에, 기존 대역을 사용하는 무선통신시스템이 재설계되어야 할 필요가 있다. 본 연구에서는 실외환경에서 60GHz의 셀 네트워크에 대한 3D 시뮬레이션 모델을 논의한다. 거리 협곡 시뮬레이션 환경 등을 포함한 일반적인 도심 환경에서 소형 셀 시스템에 대한 커버리지와 시스템 성능을 분석한다. 또한, 데이터 처리용량의 개선을 분석하기 위해 빔포밍의 적용을 고려하였다. 시뮬레이션 결과, 밀리미터파 소형 셀 기반의 시스템이 데이터 전송속도 측면에서 5G의 요구사항을 충족시킬 수 있는 주요 후보 기술 중의 하나가 될 것으로 기대된다.

• BMB Reports
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• 제44권11호
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• pp.705-712
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• 2011

Advances in the fields of proteomics and genomics have necessitated the development of high-throughput screening methods (HTS) for the systematic transformation of large amounts of biological/chemical data into an organized database of knowledge. Microfluidic systems are ideally suited for high-throughput biochemical experimentation since they offer high analytical throughput, consume minute quantities of expensive biological reagents, exhibit superior sensitivity and functionality compared to traditional micro-array techniques and can be integrated within complex experimental work flows. A range of basic biochemical and molecular biological operations have been transferred to chip-based microfluidic formats over the last decade, including gene sequencing, emulsion PCR, immunoassays, electrophoresis, cell-based assays, expression cloning and macromolecule blotting. In this review, we highlight some of the recent advances in the application of microfluidics to biochemistry and molecular biology.

• 한국통신학회논문지
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• 제38A권4호
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• pp.360-370
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• 2013

하향링크 스몰셀 네트워크 환경에서 최선형 서비스를 지원해야 할 때, 기존 기법들에서는 각 기지국 기준으로 동일 채널간섭이 가장 적게 수신되는 채널들만을 선택하게 되는데 이 채널들은 해당 기지국에 인접한 사용자의 하향링크 수율 성능만을 향상시킨다. 따라서 기존의 분산 주파수 재사용 기법들은 전체 최선형 서비스 사용자들을 공정하게 지원하지 못한다. 이 논문에서는 하향링크 스몰셀 네트워크 환경에서 기지국으로부터의 거리와 관계없이 최선형 서비스 사용자들의 수율 성능을 공정하게 향상시킬 수 있는 분산 주파수 재사용 기법을 제안한다. 각 기지국은 기존의 분산재사용 기법을 수행하여 주위 기지국들에서 가장 적게 사용되는 채널들을 선택한 다음, 전체 수율 성능의 감소를 줄이면서도 수율성능이 낮은 사용들의 수율성능을 향상시킬 수 있는 채널들로 일부채널들을 교체한다. 모의실험을 통해 제안된 기법은 수율성능 기준 하위 10%에 해당되는 사용자들의 수율성능을 기존기법에 비해 최대 15% 정도 향상시키면서 전체 수율 성능 감소는 3% 정도 허용함을 확인하였다.

• 전자공학회논문지
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• 제51권6호
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• pp.9-17
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• 2014

이종 네트워크(HetNet)란 매크로셀 내에 소형셀이 혼재한 네트워크이다. 이종 네트워크에서는 대형셀로부터 소형셀 사용자에게 미치는 간섭이 소형셀 사용자의 성능을 열화시키는 주 원인 중 하나이며, 이 간섭을 줄이기 위해 향상된 셀간 간섭 조정기법(eICIC)이 필요하다. 기존의 eICIC 관련 연구에서는 프레임별 채널 변화를 거의 고려하지 않고 네트워크의 장기 처리율을 최대화하는 데 치중되어 성능 향상이 제한적이었다. 이 논문에서는 네트워크 전체 효용을 최대화하기 위해 매 프레임마다 동적으로 셀간 간섭을 제어하고 사용자를 스케줄링하며, 전수검색보다 계산 복잡도가 낮은 새로운 알고리즘을 제안한다. 제안된 알고리즘이 기존 알고리즘보다 네트워크 전체 처리율을 향상시키며, 사용자의 수가 많을 때 사용자간 공평성을 향상시킴을 컴퓨터 모의실험을 통해 보인다.