• International Journal of Computer Science & Network Security
• /
• 제21권9호
• /
• pp.1-10
• /
• 2021

The Internet of things (IoT) is the main advancement in data processing and communication technologies. In IoT, intelligent devices play an exciting role in wireless communication. Although, sensor nodes are low-cost devices for communication and data gathering. However, sensor nodes are more vulnerable to different security threats because these nodes have continuous access to the internet. Therefore, the multiparty security credential-based key generation mechanism provides effective security against several attacks. The key generation-based methods are implemented at sensor nodes, edge nodes, and also at server nodes for secure communication. The main challenging issue in a collaborative key generation scheme is the extensive multiplication. When the number of parties increased the multiplications are more complex. Thus, the computational cost of batch key and multiparty key-based schemes is high. This paper presents a Secure Multipart Key Distribution scheme (SMKD) that provides secure communication among the nodes by generating a multiparty secure key for communication. In this paper, we provide node authentication and session key generation mechanism among mobile nodes, head nodes, and trusted servers. We analyzed the achievements of the SMKD scheme against SPPDA, PPDAS, and PFDA schemes. Thus, the simulation environment is established by employing an NS 2. Simulation results prove that the performance of SMKD is better in terms of communication cost, computational cost, and energy consumption.

• 전기학회논문지
• /
• 제58권7호
• /
• pp.1263-1269
• /
• 2009

Stable and sustainable power supply means maintaining a certain level of power quality and service while securing energy resource and resolving environmental issues. Distributed generation (DG) has become an essential and indispensable element from environmental and energy security perspectives. It is known that voltage violation is the most important constraint for load variation and the maximum allowable DG. In distribution system, sending voltage from distribution substation is regulated by ULTC (Under Load Tap Changer) designed to maintain a predetermined voltage level. ULTC is controlled by LDC (Line Drop Compensation) method compensating line voltage drop for a varying load, and the sending voltage of ULTC calls for LDC parameters. The consequence is that the feasible LDC parameters considering variation of load and DG output are necessary. In this paper, we design each LDC parameters determining the sending voltage that can satisfy voltage level, decrease ULTC tap movement numbers, or increase DG introduction. Moreover, the maximum installable DG capacity based on each LDC parameters is estimated.

• 한국컴퓨터정보학회논문지
• /
• 제22권11호
• /
• pp.57-63
• /
• 2017

The recent sudden increase of big data has characteristics such as continuous generation of data, large amount, and unstructured format. The existing relational database technologies are inadequate to handle such big data due to the limited processing speed and the significant storage expansion cost. Thus, big data processing technologies, which are normally based on distributed file systems, distributed database management, and parallel processing technologies, have arisen as a core technology to implement big data repositories. In this paper, we propose a design methodology for large-scale database based on MongoDB by extending the information engineering methodology based on E-R data model.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
• /
• pp.139.2-139.2
• /
• 2011

Compared with a traditional power system of electricity providers, distributed power systems consist of power suppliers which are small and demand-oriented. Each small power supplier tends to utilizes renewable energy sources such as solar and wind power. It is because that home renewable energy systems do not need a large scale infrastructure which is required for traditional power plants. In this work we study an economic feasibility of such a renewable energy source. We describe how renewable power generation works and what it brings in terms of economic benefits. Also, we analyze limitations by the current policy and their possible solutions.

• 한국멀티미디어학회논문지
• /
• 제18권7호
• /
• pp.864-872
• /
• 2015

The purpose of this study is to design the algorithm, Predictive Service Component - PSC, for forecasting and judging obsolescence of solar system that is implemented based on the micro-inverter. PSC proposed in this study is suitable for monitoring of distributed power generation systems. It provides a diagnosis functionality to detect failures and anomaly events. It also can determine the aging of PV systems. The conclusion of this study shows the research and development of this kind of integrated system using PSC will be needed more and varied in the near future.

• 한국컴퓨터정보학회논문지
• /
• 제24권8호
• /
• pp.1-8
• /
• 2019

Modern computers provide tremendous computing capability and a large memory system. Hybrid memories consist of next generation memory devices and are adopted in high performance systems. However, the increased complexity of the microprocessor makes it difficult to operate the system effectively. In this paper, we propose a simple data migration method called Bandwidth-aware Data Migration (BDM) to efficiently use memory systems for high performance processors with hybrid memory. BDM monitors the status of applications running on the system using hardware performance monitoring tools and migrates the appropriate pages of selected applications to High Bandwidth Memory (HBM). BDM selects applications whose bandwidth usages are high and also evenly distributed among the threads. Experimental results show that BDM improves execution time by an average of 20% over baseline execution.

• 한국정보통신학회:학술대회논문집
• /
• 한국정보통신학회 2016년도 춘계학술대회
• /
• pp.220-223
• /
• 2016

스마트 폰을 중심으로 하는 이동단말들의 폭발적인 증가로 인해 모바일 데이터 트래픽 또한 기하 급수적으로 증가해 왔으며 이로 인해 발생되는 네트워크의 부하를 줄이면서 동시에 이동단말의 이동시에도 서비스 제공에 영향을 주지 않기 위한 여러 이동성 관리 방안들이 Internet Engineering Task Force (IETF) 및 Third Generation Partnership Project (3GPP)를 통해 제안되어 왔다. 최근에는 이동성 관리의 주체가 되는 네트워크 시스템들을 가능한 분산시킴으로써 네트워크의 확장성 및 신뢰성을 높이기 위한 노력들이 진행 중에 있다. IETF에서는 분산형 이동성 관리 방법으로 Distributed Mobility Management (DMM) 방식을 표준화 중에 있으며 세부적으로는 부분 분산형 방식과 완전 분산형 방식을 포함하고 있다. 본 논문에서는 Proxy Mobile IPv6 (PMIPv6) 기반의 네트워크를 대상으로 Neighbor Discovery Protocol (NDP)를 확장, 적용하는 완전 분산형 이동성 관리 방법 (FuDMM)을 제안하였으며, 기존 방식들과의 정성적 비교를 통해 FuDMM에 대한 성능 측면의 장단점을 분석하였다.

• 전력전자학회논문지
• /
• 제11권1호
• /
• pp.72-78
• /
• 2006

분산발전시스템에 비상부하 등의 전용부하가 접속되어 있는 경우, 주전원에 고장이 발생하러라도 비상전용부하에는 지속적인 전력을 공급하기 위하여 의도적인 단독운전을 하게 된다. 기존의 계통연계형 인버터는 주전원에 전력을 주입하기 위하여 평소에 전류제어모드로 운전을 하기 때문에, 의도적인 단독운전 상황이 발생하는 경우 비상부하에 안정된 전압을 공급해 주기 위하여 전압제어모드로 운전을 전환하여야한다. 이러한 운전모드의 전환시 인버터의 출력단 전압에 심각한 과도문제가 발생된다. 본 논문에서는 의도적인 단독운전 발생시 인버터 운전모드 전환에 따른 출력전압의 과도현상을 최소화하기 위한 인버터 토폴로지와 제어알고리즘을 제안한다. 제안된 간접전류제어 알고리즘에 적합한 LCL필터 설계방법과 설계데이터를 제시한다.

• 조명전기설비학회논문지
• /
• 제22권9호
• /
• pp.111-119
• /
• 2008

본 논문에서는 최근 분산전원 확대보급에 따라 계량오차 발생, 변전소 CB 또는 Recloser, 수전설비 VCB의 OCGR 오동작, 배전자동화 시스템 거짓FI 정보발생 등 한전 배전계통에서 발생되는 오동작 현상에 대해서 원인분석을 수행하였고 그 원인은 변압기 결선에 의한 역 조류현상임을 규명하였다. 이러한 역 조류현상의 영향으로 배전계통의 3상 기본파 전류가 N상에서 동상이 되어 3배의 전류로 합산되었으며, 이 현상을 근거로 새로운 계통해석 방법을 제시하였다. 새로운 계통해석 방법을 적용하여 구간별 고장전류를 해석하였고, 역 조류현상 규명을 위해 변압기 결선형태 별로 역 조류 발생여부를 실험하였다. 또한 PSCAD/EMTDC로 실제 계통을 모의함으로써 역 조류에 의한 오동작 현상을 줄이기 위한 방법으로 중성선의 영상임피던스를 조절하는 방법을 제시하였다.

• Journal of Electrical Engineering and Technology
• /
• 제7권4호
• /
• pp.480-485
• /
• 2012

Use of photovoltaic (PV) power generation system will become more widespread in the future due to anticipated cost reduction in PV technology. As the capacity of PV systems increases, a variation of power system frequency may prevent the stable output of PV system. However, the standard for the frequency protection of distributed generation in Korea Electric Power Corporation (KEPCO)'s rule does not include the setting of frequency protection. Therefore, this paper analyzes the correlation between the frequency protection requirements and the stability of grid-connected PV system for the adjustable operating setting of frequency protection. The distribution system interconnected with 3 MW PV system is modeled by Matlab/Simulink. The various values of frequency are simulated. For studied cases, the stability of PV system is analyzed. It is concluded that the setting of frequency protection is necessary to consider the stability of PV system.