• 한국전자파학회논문지
• /
• 제28권8호
• /
• pp.603-609
• /
• 2017

전개형 솔리드 안테나에서 패널 전개 시 발생할 수 있는 구조적인 오차가 안테나 성능에 미치는 영향을 분석하였다. 위성에서 활용되는 전개형 안테나는 지상에서 접힌 상태로 발사되어 우주 공간에서 펼쳐지며, 전개 시 발생할 수 있는 오차의 형태를 분류하여 각각의 경우에 성능에 미치는 영향을 분석하였다. 패널 하나에만 전개 오차가 있을 때는 불완전 전개 패널에 해당하는 쪽에서 안테나 성능의 열화가 발생하였다. 패널 전개 오차가 코사인 함수의 형태로 분포한다고 가정하여 오차의 크기와 오차 형태에 따른 영향을 계산하고 분석하였다. 안테나 패널 오차가 균일한 경우에는 오차크기에 비례하여 이득이 감소하고, 패턴은 대칭이다. 코사인 1 또는 3주기의 패널 오차에 대해서는 주엽의 기울어짐이 나타나며, 코사인 2 또는 4주기의 패널 오차에 대해서는 패턴은 대칭이며, 이득이 감소한다.

• 정보처리학회논문지C
• /
• 제18C권6호
• /
• pp.423-432
• /
• 2011

최근 네트워크 가상화 기능 및 망에 대한 프로그래밍의 용이성을 제공해 줄 수 있는 기반 기술로 오픈플로우 기술이 주목 받고 있다. 국내에서는 캠퍼스 실험실 수준의 로컬 망에서 오픈플로우 기술의 적용 및 Layer 3을 경유한 캠퍼스 망 간의 연동이 이뤄지고 있지만 IP 계층에서의 네트워크 지연 등으로 인한 성능 저하가 문제되고 있다. 본 논문에서는 로컬 망 수준이 아닌 국가과학기술연구망 기반의 광역 규모 오픈플로우 망을 순수 Layer 2상에서 설계 및 구축하고 종단간 Round-trip Time 측정, TCP/UDP 성능 테스트를 통해 오픈플로우 망과 오픈플로우 적용 전 일반 망의 성능을 비교 분석한다. 분석 결과, 광역 규모의 오픈플로우 망은 일반 망과 비교할 때, UDP 스트림에 대한 초반 패킷 손실 문제를 제외하고 대등한 수준의 성능을 보였다. 또한, 초반 UDP 패킷 손실로 인한 성능 저하 현상은 컨트롤러 상에 반복 유입되는 동일한 "Packet_in" 이벤트에 대한 예외 처리를 구현함으로써 개선시킬 수 있었다.

• International Journal of Computer Science & Network Security
• /
• 제24권6호
• /
• pp.207-215
• /
• 2024

Cloud computing is now used by most companies, business centres and academic institutions to embrace new computer technology. Cloud Service Providers (CSPs) are limited to certain services, missing some of the assets requested by their customers, it means that different clouds need to interconnect to share resources and interoperate between them. The clouds may be interconnected in different characteristics and systems, and the network may be vulnerable to volatility or interference. While information technology and cloud computing are also advancing to accommodate the growing worldwide application, criminals use cyberspace to perform cybercrimes. Cloud services deployment is becoming highly prone to threats and intrusions. The unauthorised access or destruction of records yields significant catastrophic losses to organisations or agencies. Human intervention and Physical devices are not enough for protection and monitoring of cloud services; therefore, there is a need for more efficient design for cyber defence that is adaptable, flexible, robust and able to detect dangerous cybercrime such as a Denial of Service (DOS) and Distributed Denial of Service (DDOS) in heterogeneous cloud computing platforms and make essential real-time decisions for forensic investigation. This paper aims to develop a framework for digital forensic for the detection of cybercrime in a joined heterogeneous cloud setup. We developed a Digital Forensics model in this paper that can function in heterogeneous joint clouds. We used Unified Modeling Language (UML) specifically activity diagram in designing the proposed framework, then for deployment, we used an architectural modelling system in developing a framework. We developed an activity diagram that can accommodate the variability and complexities of the clouds when handling inter-cloud resources.

• 전자공학회논문지
• /
• 제52권4호
• /
• pp.106-114
• /
• 2015

수중 음파 센서 네트워크의 다각적인 발전에도 불구하고 네트워크상에서의 연결이 손실되는 경우가 여전히 존재한다. 특히 해양 환경에서 네트워크상의 연결 중에 발생할 수 있는 연결 단절을 유발하는 많은 다양한 문제점으로 인해 이를 보완하기 위해서 수중 음파 통신 네트워크를 위한 새로운 테스트 메커니즘이 필요하다. 본 논문에서는 통신 프로세스의 문제점 및 에러가 발생하는 위치를 식별하기 위해서 장애 없이 네트워크 배포시 가장 중요한 부분들에 대해 조사할 수 있는 방법을 제안한다. 수중 음파 통신 네트워크(UWASN)를 위한 Step-wised Out-test 메커니즘을 도입하고 실험을 통하여 out-test 기능을 이용한 수중 단말의 작동을 엄격하게 점검하였다. 구현 및 실험 결과를 통해서 Out-test 기능의 유용성 및 우수성을 입증하였고 향후 가능한 개선을 제시하였다.

• 한국IT서비스학회지
• /
• 제19권4호
• /
• pp.63-84
• /
• 2020

With the recent announcement of the WCAG2.2 Work Draft of the W3C, revision of the WCAG2.2 guidelines will be made soon. Consequently, the revision of KWCAG2.1 in response to changes in the domestic and international environment of web accessibility is urgent. The revision primarily involves development and selection of web accessibility evaluation items. In this study, the efficient procedures and useful methodologies for developing and selecting the evaluation items are to be presented. FGI (Focus Group Interview) has been devised to reflect every stakeholders opinion fairly. GT (Group Technology) has been applied to expedite the revision processes particularly in the FGI. QFD (Quality Function Deployment) method plays an important role in investigating the relationship between evaluation items and its characteristics, and in analyzing the importance and priorities of each item. This study proposes 5 principles, 17 guidelines and 39 evaluation items which can be used for the revision of KWCAG 2.1. This study is expected to be of great help in establishing the KWCAG 2.2 in the near future.

• 산업공학
• /
• 제15권2호
• /
• pp.114-125
• /
• 2002

The objective of this paper is to describe a systematic accident scenario analysis method(SASA) adept at creating accident scenarios for the design of safer products. This approach was inspired by the Quality Function Deployment(QFD) method, which is conventionally used in quality management. In this study, the QFD provides a formal and systematic scheme to devise accident scenarios while maintaining objectivity. SASA consists of three key stages to be broken down into a series of consecutive steps:(1) developing an accident analysis tableau,(2) devising the accident scenarios using the accident analysis tableau,(3) performing a feasibility test, a clustering process and a patterning process, and finally(4) performing quantitative evaluation of each accident scenario. The SASA was applied to a case study of child safety seats. The accident analysis tableau devised 2828(maximum) accident scenarios from all possible relationships between the hazard factors and situation characteristics. Among them, 270 scenarios were devised through the feasibility test and the clustering process. The patterning process reduced them to 29 patterns representative of all accident scenarios. Based on an intensive analysis of the accident patterns, design guidelines for a safer child safety seat were recommended. The implications of the study on the child safety seat case were then discussed.

• 한국군사과학기술학회지
• /
• 제16권5호
• /
• pp.666-674
• /
• 2013

This paper studied about the design and implementation of tactical communication network simulator in order to obtain tactical communication network parameter, such as link capacity and routing plan, and a number of exceptional cases that may occur during actual deployment by conducting simulation of a large-scale tactical communication networks. This tactical communication network simulator provides equipment models and link models of commercial OPNET simulator for tactical communication network. In addition, 6 types of simulation scenario writings convenience functions and traffic generation models that may occur in situations of tactical communication network environment were implemented in order to enhance user friendliness. By taking advantages of SITL(System-In-The-Loop) function of OPNET, the tactical communication network simulator allows users to perform interoperability test between M&S models and actual equipment in operating simulation of tactical communication network, which is run on software. In order to confirm the functions and performance of the simulator, small-scale of tactical communication network was configured to make sure interoperability between SITL-based equipment and a large-scale tactical communication network was simulated and checked how to cope with traffic generated for each network node. As the results, we were able to confirm that the simulator is operated properly.

• International Journal of Computer Science & Network Security
• /
• 제21권11호
• /
• pp.216-222
• /
• 2021

Advances in technology have given educators a tool to empower them to assist with developing the best possible human resources. Teachers at universities prefer to use more modern technological advances to help them educate their students. This opens up a necessity to research the capabilities of cloud-based learning services so that educational solutions can be found among the available options. Based on that, this essay looks at models and levels of deployment for the e-learning cloud architecture in the education system. A project involving educators explores whether gement Systems (LMS) can function well in a collaborative remote learning environment. The study was performed on how Blackboard was being used by a public institution and included research on cloud computing. This test examined how Blackboard Learn performs as a teaching tool and featured 60 participants. It is evident from the completed research that computers are beneficial to student education, especially in improving how schools administer lessons. Convenient tools for processing educational content are included as well as effective organizational strategies for educational processes and better ways to monitor and manage knowledge. In addition, this project's conclusions help highlight the advantages of rolling out cloud-based e-learning in higher educational institutions, which are responsible for creating the integrated educational product. The study showed that a shift to cloud computing can bring progress to educational material and substantial improvement to student academic outcomes, which is related to the increased use of better learning tools and methods.

• 인터넷정보학회논문지
• /
• 제22권6호
• /
• pp.1-8
• /
• 2021

With the rapid growth of intelligent devices and communication technologies, 5G network environment has become more heterogeneous and complex in terms of service management and orchestration. 5G architecture requires supportive technologies to handle the existing challenges for improving the Quality of Service (QoS) and the Quality of Experience (QoE) performances. Among many challenges, traffic steering is one of the key elements which requires critically developing an optimal solution for smart guidance, control, and reliable system. Mobile edge computing (MEC), software-defined networking (SDN), network functions virtualization (NFV), and deep learning (DL) play essential roles to complementary develop a flexible computation and extensible flow rules management in this potential aspect. In this proposed system, an accurate flow recommendation, a centralized control, and a reliable distributed connectivity based on the inspection of packet condition are provided. With the system deployment, the packet is classified separately and recommended to request from the optimal destination with matched preferences and conditions. To evaluate the proposed scheme outperformance, a network simulator software was used to conduct and capture the end-to-end QoS performance metrics. SDN flow rules installation was experimented to illustrate the post control function corresponding to DL-based output. The intelligent steering for network communication traffic is cooperatively configured in SDN controller and NFV-orchestrator to lead a variety of beneficial factors for improving massive real-time Internet of Things (IoT) performance.

• 벤처창업연구
• /
• 제7권3호
• /
• pp.17-25
• /
• 2012

반도체를 제작하는데 있어 Wire bonding 공정은 가장 정밀한 관리와 핵심품질특성(CTQ)을 필요로 한다. 포장과정에 있어서 가장 필수적인 단계로 간주된다. 이 과정에서는 순금 와이어가 칩과 PCB를 연결하기 위해서 사용된다. 금의 가격은 오랜 기간 동안 꾸준히 증가하여왔고, 근래에도 더 증가할 것으로 예상된다. 이러한 상황에서, 많은 반도체 제조 회사들은 새로운 종류의 와이어를 개발했다. 합금와이어가 그 중 하나이고 그것에 많은 연구가 이루어지고 있다. 본 연구는 Wire bonding 공정에서의 parameter를 6sigma와 품질기능전개(QFD)를 사용해 최적화시키고자 한다. 6sigma 과정은 그 문제를 해결하는데 뿐만이 아니라 생산성을 향상시키는데 좋은 기법이다. 중요한 요인을 찾기 위해서 고객의 소리에 초점을 두었다. 고객의 소리의 주요 요인들은 CTQ라고 불린다. 본 연구는 CTQ의 목표수준을 설정 한 후 중요인자를 선정하기 위하여 QFD 활동을 하였으며, 최적 조건 설정하기 위해 실험계획법을 이용하였다. 따라서 본 논문에서는 품질기능전개에서 신제품 개발 시 공정 조건을 최적화 하는 과정을 제시 하여 양산에서 발생될 수 있는 품질 위험요소를 사전에 제거 시킬 수 있게 되었다.