• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권8호
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• pp.3821-3841
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• 2019

Cloud radio access networks (C-RANs) have been regarded in recent times as a promising concept in future 5G technologies where all DSP processors are moved into a central base band unit (BBU) pool in the cloud, and distributed remote radio heads (RRHs) compress and forward received radio signals from mobile users to the BBUs through radio links. In such dynamic environment, automatic decision-making approaches, such as artificial intelligence based deep reinforcement learning (DRL), become imperative in designing new solutions. In this paper, we propose a generic framework of autonomous cell activation and customized physical resource allocation schemes for energy consumption and QoS optimization in wireless networks. We formulate the problem as fractional power control with bandwidth adaptation and full power control and bandwidth allocation models and set up a Q-learning model to satisfy the QoS requirements of users and to achieve low energy consumption with the minimum number of active RRHs under varying traffic demand and network densities. Extensive simulations are conducted to show the effectiveness of our proposed solution compared to existing schemes.

• 한국위성정보통신학회논문지
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• 제12권4호
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• pp.1-10
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• 2017

지진, 태풍, 호우 등 갑작스런 자연재해는 생명과 재산을 위협하기 때문에 정부는 신속하고 정확하게 재난상황을 전파하는 것이 중요하다. 따라서 본 논문에서는 재난상황 발생 시 재난방송 수신을 위해 스마트폰에 내장된 FM 라디오 수신 칩을 활성화하기 위한 방법을 제시하였다. 이를 위해 첫째는 국내 재난방송 체계와 매체별 재난방송 역할 및 한계를 분석하였고, 둘째는 스마트폰의 FM 라디오 수신 칩 활성화를 위한 분야별 개선 방안을 분석하여 대안을 제시하였다.

• 한국정보통신학회논문지
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• 제19권8호
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• pp.1901-1907
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• 2015

스마트폰을 비롯한 최신의 사용자 단말은 대체로 복수 개의 무선 인터페이스를 갖는다. 이러한 복수 개의 무선 인터페이스를 결합하여 동시에 사용함으로써 데이터 전송 속도를 향상시킬 수 있다. 하지만, 이 경우 각 인터페이스가 전력을 소모하므로 단말의 총 소비 전력은 매우 클 수 있다. 본 논문에서는 이중 무선 인터페이스를 결합하여 사용 시 단말의 버퍼 상태에 따라 무선 인터페이스를 적응적으로 활성화시키는 기법의 성능 모델을 마코브체인을 이용해 도출한다. 도출된 성능 모델은 패킷 발생률, 딜레이 성능 요구 조건, 결합으로 인한 성능 손실 등 다양한 동작 환경 및 설정에 대해 전송 딜레이 성능과 전력 소모를 예측할 수 있게 한다. 모델을 통해 적응적 활성화 기법이 일정 이하의 낮은 트래픽 발생 상황에서 기존 대비 절반 정도의 전력 소모를 하는 것을 보인다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권6호
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• pp.2513-2533
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• 2018

In cognitive radio technology, the overall efficiency of communications systems can be improved without allocating additional bands by allowing a secondary system to utilize the licensed band when the primary system, which has the right to use the band, does not use it. In this paper, we propose a fast and reliable common channel initialization protocol without any exchange of initialization messages between the cluster head and the member nodes in cognitive ad-hoc networks. In the proposed method, the cluster and member nodes perform channel-based spectrum sensing. After sensing, the cluster head transmits a system activation signal through its available channels with a predetermined angle difference pattern. To detect the cluster head's transmission channels and to join the cluster, each member node implements fast Fourier transform (FFT) and computes autocorrelation for the angle difference sequence of the received signal patterns. This is compared to the predetermined reference angle difference pattern. The join-request and channel-decision procedures are presented in this paper. Performance evaluation of the proposed method is presented in the simulation results.

• 한국항해학회지
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• 제17권2호
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• pp.75-106
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• 1993

GMDSS(Global Maritime Distress and Safety system) is a new communication system for the distress and safety at sea which is utilizing the recent advancements in satellite communication and positioning system, digital communication system, computer and microelectronic technology, etc., and will completely substitute the current communication system by 1999. Although the improvements of education for producing qualified Radio Operators as well as the establi-shments of policy for accepting the system are required, the educational institutions and relating administ-rations have not yet prepared the rational and concrete schemes on the educational methods and accepting procedures for the system. In this study, as the result of analyzing the GMDSS, courses of training and relating data, the authors suggested principles for improving the course and contents of education and rational schemes for balan-cing the demand and supply of Radio Operators. The authors expect not only the consequences of this study can be utilized as reference materials for the instruction to ratio communication in the organs of education but also that the following effects can be obtained by the study. 1. Security of distress and safety communication system at sea by the establishment of relating regula-tions. 2. Rationalization of the management of radio communication at sea and improvement of the communi-cation system on the vessel. 3. Upgrading the quality of Radio Operators and presenting schemes for current qualified persons. 4. Activation of industry producing radio instruments. 5. Balance of the demand and supply of Radio Operators and development of shipping industry.

• 한국ITS학회 논문지
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• 제4권2호
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• pp.23-31
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• 2005

고속으로 이동하는 차량에 대한 정보수집 및 제공 등의 서비스를 구현해야 하는 지능형 교통시스템(WS : Intelligent Transponation System)은 단거리전용 무선통신(RF-DSRC : Radio Frequency Dedicated Short Range Communication)과 같은 특수목적의 통신시스템이 필수적이다. RF-DSRC를 사용하기 위해서는 먼저 차량 탑재장치(OBE : On-Board Equipment)는 슬롯화된 알로하방식에 의해 할당된 접속요구슬롯(ACTS$\cdot$Activation Slot)내의 접속요구채널(ACTC$\cdot$Activation Channel)을 이용하여 링크초기접속 요구를 한다. 링크초기접속은 통신 시스템의 성능을 결정하는 중요한 요소임에도 불구하고, 링크 초기접속에 대한 수학적 모델링 연구는 미흡한 상태이다. 본 논문에서는 RF-DSRC에 대한 링크초기접속에 관한 수학적 모델링을 제시하고, 모델링의 성능을 분석하기 위한 제시된 부하(G)를 RF-DSRC의 특성에 맞게 정의하여 링크초기접속 확률을 계산하였다.

• 제어로봇시스템학회논문지
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• 제12권10호
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• pp.955-961
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• 2006

The global ultrasonic system for the self-localization of a mobile robot consists of several ultrasonic transmitters fixed at some reference positions in the global coordinates of robot environment. By activating the ultrasonic transmitters, the mobile robot is able to get the distance to the ultrasonic transmitters and compute its own position in the global coordinate. Due to the limitation on the ultrasonic signal strength and beam width as well as the environmental obstacles however, the ultrasonic signals from some generator may not be transmitted to the robot. Thus, instead of activating the all ultrasonic transmitters, it is necessary to select some ultrasonic generators to activate based on the current robot position. In this paper, we propose a selective activation algorithm for self-localization with the global ultrasonic system. The selective activation algorithm gets the meaningful ultrasonic data at every sampling instants, which results in the faster and more accurate response of the self-localization than the conventional sequential activation. Through the self-localization and path following control, we verify the effectiveness of the proposed selective activation algorithm.

• Animal cells and systems
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• 제5권4호
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• pp.267-274
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• 2001

Calpains are a family of cysteine proteases existing primarily in two forms designated by the $Ca^{2+}$ concentration needed for activation in vitro, $\mu$-calpain (calpain-I) and m-calpain (calpain-II). The physiologica1 roles of calpains remain unclear. Many groups have proposed a role for calpains In apoptosis, but their patterns of activation are not well characterized. Calpains have been implicated in neutrophil apoptosis, glucocorticoid-induced thymocyte apoptosis, as well as many other apoptotic pathways. Calpain activation in apoptosis is usually linked upstream or downstream to caspase activation, or in a parallel pathway alongside caspase activation. Calpains have been suggested to be involved in DNA fragmentation (via endonuclease activation), but also as effector proteases that cleave cellular proteins involved in DNA repair, membrane associated proteins and other homeostatic regulatory proteins. Recently, our laboratory demonstrated $\mu$-calpain activation in NAD(P)H: quinone oxidoreducatse 1 (NQO1)-expressing cells after exposure to $\beta$-lapachone, a novel quinone and potential chemo- and radio-therapeutic agent. Increased cytosolic $Ca^{2+}$ in NQO1-expressing cells after $\beta$-lapachone exposures were shown to lead to $\mu$-calpain activation. In turn, $\mu$-calpain activation was important for substrate proteolysis and DNA fragmentation associated with apoptosis. Upon activation, $\mu$-calpain translocated to the nucleus where it could proteolytically cleave PARP and p53. We provided evidence that $\beta$-lapachone-induced, $\mu$-calpain stimulated, apoptosis did not involve any of the known caspases; known apoptotic caspases were not activated after $\beta$-lapachone treatment of NQO1-expressing cells, nor did caspase inhibitors have any effect on $\beta$-1apachone-induced cell death. Elucidation of processes by which $\beta$-1apachone-stimulated $\mu$-calpain activation and calpains ability to activate endonucleases and induce apoptosis independent of caspase activity will be needed to further develop/modulate $\beta$-lapachone for treatment of human cancers that over-express NQO1.

• 대한의생명과학회지
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• 제19권2호
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• pp.98-104
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• 2013

Radiation is one of the major therapy for the removal of cancer cells. The results of the radiation therapy depend on the radio-resistance of cancer cells. For the effective treatment in these radio-resistant cancers, the use of chemicals that act on cancer cells is known to enhance the cytotoxic effects of radiation therapy. In this study, I investigated the effect of potassium cyanate (KCN) on the irradiated-colorectal cancer cell line, HCT 116 cells. KCN induces the carbamylation of proteins and can change the biological activity of various human cells. To understand the effect of KCN on the radiosensitivity of HCT 116 cells, I examined alteration of the cell cycle, generation of reactive oxygen species (ROS), cell viability, apoptosis and intracellular signaling proteins in the irradiated cells with/without KCN treatment. Combination treatment caused significant increase in sub $G_0/G_1$ and ROS generation in HCT 116 cells. KCN inhibited the proliferation and cell viability in irradiated HCT 116 cells. KCN-induced apoptosis of irradiated cells was processed via the activation of caspase 3 and caspase 9. Apoptosis-associated signal proteins, including Bax and Bcl-2 were regulated by irradiation with KCN treatment. Taken together, these results may indicate that KCN enhances the radiosensitivity of radio-resistant cell and then has a synergistic effect on radiation therapy in colorectal cancer.

• 한국가스학회지
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• 제2권3호
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• pp.60-69
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• 1998

저온 플라즈마를 이용한 메탄 직접 전환반응은 진공에서 메탄만을 원료로 마이크로웨이브나 라디오 주파수(R.F)등의 에너지를 가하여 플라즈마 상태로 반응시켜 에틸렌, 에탄, 아세틸렌 등의 C2 화합물을 생성하는 방법이다. 이러한 직접적인 메탄 전환의 장점은 산소를 가하지 않으므로 산소에 의한 부생성물이 없는 점과 저온 플라즈마를 이용하므로 저에너지 공정이라는 것을 들 수 있다. 본 연구에서는 마이크로웨이브와 라디오 주파수(R.F)를 이용하여 저온 플라즈마 반응으로 메탄 전환반응을 수행하였고 일반적인 플라즈마 반응에 사용되는 관형반응기 외에도 독자적인 시리즈 반응기를 설계하여 성능실험을 수행하였다. 또한 플라즈마와 촉매를 이용한 반응실험을 수행 촉매의 영향을 확인하였다. 저온 플라즈마를 이용한 메탄 전환 반응의 특성을 분석한 자료는 공정의 실용화를 위한 반응기 설계 및 반응속도를 분석하기 위한 기초자료로 기대된다.