• Journal of Communications and Networks
• /
• 제17권6호
• /
• pp.549-557
• /
• 2015

Mobile cellular networks are becoming increasingly complex to manage while classical deployment/optimization techniques and current solutions (i.e., cell densification, acquiring more spectrum, etc.) are cost-ineffective and thus seen as stopgaps. This calls for development of novel approaches that leverage recent advances in storage/memory, context-awareness, edge/cloud computing, and falls into framework of big data. However, the big data by itself is yet another complex phenomena to handle and comes with its notorious 4V: Velocity, voracity, volume, and variety. In this work, we address these issues in optimization of 5G wireless networks via the notion of proactive caching at the base stations. In particular, we investigate the gains of proactive caching in terms of backhaul offloadings and request satisfactions, while tackling the large-amount of available data for content popularity estimation. In order to estimate the content popularity, we first collect users' mobile traffic data from a Turkish telecom operator from several base stations in hours of time interval. Then, an analysis is carried out locally on a big data platformand the gains of proactive caching at the base stations are investigated via numerical simulations. It turns out that several gains are possible depending on the level of available information and storage size. For instance, with 10% of content ratings and 15.4Gbyte of storage size (87%of total catalog size), proactive caching achieves 100% of request satisfaction and offloads 98% of the backhaul when considering 16 base stations.

• International journal of advanced smart convergence
• /
• 제12권4호
• /
• pp.104-110
• /
• 2023

In the user-centered design paradigm, information systems are created entirely tailored to the users who will use them. When the functions of a complex system meet a simple user interface, users can use the system conveniently. While web personalization services are emerging as a major trend in portal services, portal companies are competing for a second service, such as introducing 'integrated communication platforms'. Until now, the role of the portal has been content and search, but this time, the goal is to create and provide the personalized services that users want through a single platform. Personalization service is a login-based cloud computing service. It has the characteristic of being able to enjoy the same experience at any time in any space with internet access. Personalized web services like this have the advantage of attracting highly loyal users, making them a new service trend that portal companies are paying attention to. Researchers spend a lot of time collecting research-related information by accessing multiple information sources. There is a need to automatically build interest information profiles for each researcher based on personal presentation materials (papers, research projects, patents). There is a need to provide an advanced customized information service that regularly provides the latest information matched with various information sources. Continuous modification and supplementation of each researcher's information profile of interest is the most important factor in increasing suitability when searching for information. As researchers' interest in unstructured information such as technology markets and research trends is gradually increasing from standardized academic information such as patents, it is necessary to expand information sources such as cutting-edge technology markets and research trends. Through this, it is possible to shorten the time required to search and obtain the latest information for research purposes. The interest information profile for each researcher that has already been established can be used in the future to determine the degree of relationship between researchers and to build a database. If this customized information service continues to be provided, it will be useful for research activities.

• 한국광학회지
• /
• 제22권6호
• /
• pp.283-290
• /
• 2011

수증기의 혼합비를 측정하기 위하여 라만 라이다 시스템을 설계 제작하였다. 시스템을 검증하기 위하여 가강수량과 분포에 대하여 상용 마이크로파 라이오메터(MWR)와 GPS 신호를 이용하는 방법과 비교 연구를 수행하였다. GNSS 방법으로 측정한 총가강수량과 본 라이다 방법에서는 작은 차이를 보였는데, 이는 라이다 방법으로 얻을 수 있는 수증기의 측정고도가 제한적이기 때문이다. 반면에 MWR 방법과 라이다 방법으로 얻은 고도에 따른 수증기량은 수증기량이 급격하게 변하는 구름 경계나 경계고도 근처에서 심한 차이를 보이고 있었다. MWR은 그 밀도가 급격하게 변하는 곳에서 취약한 점을 보였으나 개발된 라만 라이다의 경우는 그 밀도가 급격히 변하는 곳에서도 측정이 원활하게 이루어지고 있음을 알 수 있었다.

• 정보처리학회논문지:컴퓨터 및 통신 시스템
• /
• 제12권3호
• /
• pp.93-102
• /
• 2023

클라우드를 통한 데이터 처리는 통신 과정에서 지연시간과 통신비용 증가 등 같은 많은 문제가 발생한다. 사물인터넷 분야에서는 이러한 문제를 해결하기 위해 엣지 컴퓨팅 연구가 활발히 이루어지고 있고, 대표적인 응용 분야로 자율주행이 있다. 실내 자율주행에서는 실외와 달리 GPS와 교통정보를 이용할 수 없기 때문에 센서를 활용하여 주변 환경을 인식해야 한다. 그리고 자원이 제약된 모바일 환경이기 때문에 효율적인 자율주행 시스템이 필요하다. 본 논문에서는 실내 환경에서 자율주행을 위해 신경망을 사용하는 기계학습을 제안한다. 신경망 모델은 LiDAR 센서에서 측정된 거리 데이터를 바탕으로 현재 위치에 가장 적절한 주행 명령을 예측한다. 신경망의 입력 데이터의 수에 따른 성능 평가를 수행하기 위해 6가지의 학습 모델을 설계하였다. 주행과 학습을 위해 Raspberry Pi 기반의 자율주행 차량을 제작하였고, 학습 데이터 수집과 성능평가를 위한 실내 주행 트랙을 제작하였다. 6가지의 신경망 모델들은 정확도와 응답시간 그리고 배터리 소모에 대한 성능 비교를 하였고, 입력 데이터의 수가 성능에 미치는 영향을 확인하였다.

• 경영정보학연구
• /
• 제26권2호
• /
• pp.155-167
• /
• 2024

본 연구는 인공지능 분야의 공동연구 중요성을 인식하고 특허를 중심으로 산·학·연 기술협력 특성을 TES(Techno-Economic Segment) 분석으로 파악하였다. 이를 위해 2012년 이후 미국, 중국 등 5개국 특허청에 출원된 10년의 인공지능 특허 113,289건 가운데 7,062건을 공동연구 대상으로 하여 기업, 대학, 연구기관 등의 경제 주체를 식별하고, 기술협력 주제와 특성을 파악하였다. 분석결과 인공지능 분야 기술협력이 증가하는 가운데 전체 협력 가운데 산업계와 산업계(40%), 산업계와 대학(25.2%)의 협력이 상대적으로 높은 비중을 차지하였다. 그리고 자금과 분석데이터에 강점을 가진 산업계와 대학(9.8%), 우수한 인력을 보유한 대학 간 협력(1.9%) 비율이 증가하는 추세를 확인하였고, 이를 통해 대학의 역할이 강화되고 있음을 볼 수 있었다. 또한 토픽모델링과 네트워크 분석을 통해 협력특허 관심 분야와 연구 주체 간 협력 관계를 파악한 결과 협력 유형에 상관없이 유사한 관심 연구 주제가 도출되는 가운데, 자율주행, 엣지 컴퓨팅, 클라우드, 마케팅 및 소비자 행동 분석 등의 응용 영역으로 연구범위가 확대되고, 협력 주체는 다양해지며, 중국 대학이 중심이 되는 대규모 네트워크가 발현되는 현상을 확인할 수 있었다.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제11권10호
• /
• pp.4717-4737
• /
• 2017

Today, smart grids, smart homes, smart water networks, and intelligent transportation, are infrastructure systems that connect our world more than we ever thought possible and are associated with a single concept, the Internet of Things (IoT). The number of devices connected to the IoT and hence the number of traffic flow increases continuously, as well as the emergence of new applications. Although cutting-edge hardware technology can be employed to achieve a fast implementation to handle this huge data streams, there will always be a limit on size of traffic supported by a given architecture. However, recent cloud-based big data technologies fortunately offer an ideal environment to handle this issue. Moreover, the ever-increasing high volume of traffic created on demand presents great challenges for flow management. As a solution, flow aggregation decreases the number of flows needed to be processed by the network. The previous works in the literature prove that most of aggregation strategies designed for smart grids aim at optimizing system operation performance. They consider a common identifier to aggregate traffic on each device, having its independent static aggregation policy. In this paper, we propose a dynamic approach to aggregate flows based on traffic characteristics and device preferences. Our algorithm runs on a big data platform to provide an end-to-end network visibility of flows, which performs high-speed and high-volume computations to identify the clusters of similar flows and aggregate massive number of mice flows into a few meta-flows. Compared with existing solutions, our approach dynamically aggregates large number of such small flows into fewer flows, based on traffic characteristics and access node preferences. Using this approach, we alleviate the problem of processing a large amount of micro flows, and also significantly improve the accuracy of meeting the access node QoS demands. We conducted experiments, using a dataset of up to 100,000 flows, and studied the performance of our algorithm analytically. The experimental results are presented to show the promising effectiveness and scalability of our proposed approach.

• 대한원격탐사학회지
• /
• 제40권4호
• /
• pp.319-341
• /
• 2024

The utilization of multispectral imaging systems (MIS) in remote sensing has become crucial for large-scale agricultural operations, particularly for diagnosing plant health, monitoring crop growth, and estimating plant phenotypic traits through vegetation indices (VIs). However, environmental factors can significantly affect the accuracy of multispectral reflectance data, leading to potential errors in VIs and crop status assessments. This paper reviewed the complex interactions between environmental conditions and multispectral sensors emphasizing the importance of accounting for these factors to enhance the reliability of reflectance data in agricultural applications.An overview of the fundamentals of multispectral sensors and the operational principles behind vegetation index (VI) computation was reviewed. The review highlights the impact of environmental conditions, particularly solar zenith angle (SZA), on reflectance data quality. Higher SZA values increase cloud optical thickness and droplet concentration by 40-70%, affecting reflectance in the red (-0.01 to 0.02) and near-infrared (NIR) bands (-0.03 to 0.06), crucial for VI accuracy. An SZA of 45° is optimal for data collection, while atmospheric conditions, such as water vapor and aerosols, greatly influence reflectance data, affecting forest biomass estimates and agricultural assessments. During the COVID-19 lockdown,reduced atmospheric interference improved the accuracy of satellite image reflectance consistency. The NIR/Red edge ratio and water index emerged as the most stable indices, providing consistent measurements across different lighting conditions. Additionally, a simulated environment demonstrated that MIS surface reflectance can vary 10-20% with changes in aerosol optical thickness, 15-30% with water vapor levels, and up to 25% in NIR reflectance due to high wind speeds. Seasonal factors like temperature and humidity can cause up to a 15% change, highlighting the complexity of environmental impacts on remote sensing data. This review indicated the importance of precisely managing environmental factors to maintain the integrity of VIs calculations. Explaining the relationship between environmental variables and multispectral sensors offers valuable insights for optimizing the accuracy and reliability of remote sensing data in various agricultural applications.