• 한국통신학회논문지
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• 제25권1A호
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• pp.104-113
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• 2000

본 연구는 전파트리 기반으로 하여 중첩된 그룹의 멤버를 고려한 메타-그룹(MG)을 노드로 하여 멀티캐스트 트리를 구성하여 트리의 깊이가 작아지고, 순서화를 이루기가 쉬워 지게 하며, 메타-그룹에 대표 수신자의 역할을 하는 Designated Manager(DM)을 두어 송신자를 대신하여 DM이 속한 메타-그룹의 멤버들에 대한 ACK 처리와 재전송을 담당하는 멀티캐스트 프로토콜을 설계한다. 시뮬레이션 분석을 통해서 송신자의 ACK 처리를 분산시키고, Commit delay를 줄이고 송신자의 overhead를 줄일 수 있어서, 기존의 프로토콜보다 우수한 성능을 보였다.

• 한국통신학회논문지
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• 제34권10B호
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• pp.1004-1012
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• 2009

다양한 무선 네트워크상에서 멀티미디어 멀티캐스트 서비스에 대한 기대가 날로 높아지고 있는데, 이는 IP 멀티캐스트 그룹 관리가 무선 환경에서도 효과적이면서 효율적으로 동작하여야 함을 가정하고 있다. 하지만, IGMPv3/MLDv2는 무선상에서 신뢰성이 없는 시그널링, 느린 상태의 전환, 낮은 주파수당 전송 효율, Bulk Report, Dormant 모드를 방해하는 등의 문제가 있어 무선 환경에서 그대로 사용하기에 비효율적이다. 본 논문에서는 무선 호스트 에이전트(Wireless Host Agent; WHA)를 도입하여 무선 링크 사이에서의 시그널링을 줄이고 그룹 관리의 효율성과 신뢰성을 높이는 기법을 소개한다. 또한 시그널링 비용 모델을 제시하고, 그 성능을 비교하였다.

• 한국정보통신학회논문지
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• 제14권4호
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• pp.795-802
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• 2010

오늘날 기업 경영 환경은 글로벌 환경과 정보기술의 발전 등으로 갈수록 빠른 속도로 복잡하게 변하고 있으며, 수많은 기업들은 급변하는 경영환경에 대응한 경쟁력 확보를 위하여 끊임없는 노력과 변화, 혁신을 추구하고 있다. 이러한 부문별 자동화와 함께 기업 경영의 전체적 최적화를 이루려는 취지에서 등장한 것이 전사적 자원관리(ERP: Enterprise Resource Planning)이다. 특히, ERP 시스템에서 관리회계는 보다 효율적인 내부관리를 위한 부가적인 기능들로 구성되어 있어 많은 시스템을 적극적으로 활용하고 있다. 본 연구에서는 Oracle ERP관리회계 분야의 표준원가를 살펴보고 표준원가에서 발생하는 실제원가와의 변량차이 분석을 시도하였다. 이를 통하여 실제 발생된 재료비와 간접재료비에 가까운 원가요소를 얻는 방법을 구현하여 Oracle ERP 시스템의 원가운영에 적용하였다.

• 정보처리학회논문지C
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• 제12C권3호
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• pp.323-330
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• 2005

버퍼 오버플로우 공격은 가장 흔하고 위협적인 취약점 중의 하나이다. 최근 이러한 버퍼 오버플로우 공격을 막기 위하여 많은 연구가 이루어지고 있으나 실행시 발생하는 오버헤드 때문에 이를 적용하는 문제가 있다. 본 논문은 이진코드 형태의 파일에서 사용자 정의 함수를 변환하여 리턴 주소의 복사본을 스택의 특정 구역에 저장하고 공격 위험이 있는 문자열 함수를 재작성하고, 재작성된 함수 종료시 리턴 주소와 복사된 리턴 주소의 비교와 ebp 레지스터 값의 비교를 통해 오버플로우 공격을 탐지하는 방법을 제안한다.

• 한국전기전자재료학회논문지
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• 제32권6호
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• pp.507-511
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• 2019

The purpose of an electric railway system contact wire is to supply electric energy to trains through a contacted pantograph. This energy is then converted into mechanical energy. Recent developments in overhead contact lines include the increase in the tension force up to 34 kN according to train speeds that reach up to 400 km/h with a verified safety. Rigid conductor catenary (R-Bar) for high speeds of up to 250 km/h have been developed in tunnels to save on construction costs. This is significant because minor defects in R-bars in aspects, such as height and stagger affect installation conditions. In this study, we propose the use of a detector that measures the static characteristics to reduce the R-bar installation errors. This detector has been developed to measure the height and stagger of the contact wire using video images.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권8호
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• pp.2805-2826
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• 2021

In most cases, the routing policy of networks shows a preference for a static one-to-one mapping of communication pairs to routing paths, which offers adversaries a great advantage to conduct thorough reconnaissance and organize an effective attack in a stress-free manner. With the evolution of network intelligence, some flexible and adaptive routing policies have already proposed to intensify the network defender to turn the situation. Routing mutation is an effective strategy that can invalidate the unvarying nature of routing information that attackers have collected from exploiting the static configuration of the network. However, three constraints execute press on routing mutation deployment in practical: insufficient route mutation space, expensive control costs, and incompatibility. To enhance the availability of route mutation, we propose an OpenFlow-based route mutation technique called Polymorphic Path Transferring (PPT), which adopts a physical and virtual path segment mixed construction technique to enlarge the routing path space for elevating the security of communication. Based on the Markov Decision Process, with considering flows distribution in the network, the PPT adopts an evolution routing path scheduling algorithm with a segment path update strategy, which relieves the press on the overhead of control and incompatibility. Our analysis demonstrates that PPT can secure data delivery in the worst network environment while countering sophisticated attacks in an evasion-free manner (e.g., advanced persistent threat). Case study and experiment results show its effectiveness in proactively defending against targeted attacks and its advantage compared with previous route mutation methods.

• 한국기계가공학회지
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• 제18권2호
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• pp.52-57
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• 2019

To develop a stirring device that can automatically measure the viscosity of a fluid, the impeller type of the device must be recognized without making contact. In this study, we propose a method to discriminate the type of impellers using the changes in the magnetic field. Permanent magnets are inserted into a hollow hole of the impellers, and the change of the magnetic field is measured by a hall sensor. All experimental results are compared with the FEM analysis results. The results show that with the increase in diameter and length of the magnet inserted into the impeller, the magnitude of the magnetic flux density increases. The magnetic field is more sensitive to the change in the magnet diameter than to the change in magnet length. In order to reduce the machining costs, however, it is advantageous to change the magnet length instead of the magnet diameter.

• International Journal of Computer Science & Network Security
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• 제22권3호
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• pp.236-244
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• 2022

Network Mobility Basic Support (NEMO BS) protocol has been accredited and approved by Internet Engineering Task Force (IETF) working group for mobility of sub-networks. Trains, aircrafts and buses are three examples of typical applications for this protocol. The NEMO BS protocol was designed to offer Internet access for a group of passengers in a roaming vehicle in an adequate fashion. Furthermore, in NEMO BS protocol, specific gateways referred to Mobile Routers (MRs) are responsible for carrying out the mobility management operations. Unfortunately, the main limitations of this basic solution are pinball suboptimal routing, excessive signaling cost, scalability, packet delivery overhead and handoff latency. In order to tackle shortcomings of triangular routing and Quality of Service (QoS) deterioration, the proposed scheme (Diff-FH NEMO) has previously evolved for end-users in moving network. In this sense, the article focuses on an exhaustive analytic evaluation at Home Agent (HA) entity of the proposed solutions. An investigation has been conducted on the signaling costs to assess the performance of the proposed scheme (Diff-FH NEMO) in comparison with the standard NEMO BS protocol and MIPv6 based Route Optimization (MIRON) scheme. The obtained results demonstrate that, the proposed scheme (Diff-FH NEMO) significantly improves the signaling cost at the HA entity in terms of the subnet residence time, number of mobile nodes, the number of DMRs, the number of LFNs and the number of CNs.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제16권10호
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• pp.3373-3389
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• 2022

Exploration of mobile robot without prior data about environments is a fundamental problem during the SLAM processes. In this work, we propose improved version of previous Rmap algorithm by modifying its Exploration submodule. Despite the previous Rmap's performance which significantly reduces the overhead of the grid map, its exploration module costs a lot because of its rectangle following algorithm. To prevent that, we propose a new Rmap+ algorithm for autonomous path planning of mobile robot to explore an unknown environment. The algorithm bases on paired frontiers. To navigate and extend an exploration area of mobile robot, the Rmap+ utilizes the inner and outer frontiers. In each exploration round, the mobile robot using the sensor range determines the frontiers. Then robot periodically changes the range of sensor and generates inner pairs of frontiers. After calculating the length of each frontiers' and its corresponding pairs, the Rmap+ selects the goal point to navigate the robot. The experimental results represent efficiency and applicability on exploration time and distance, i.e., to complete the whole exploration, the path distance decreased from 15% to 69%, as well as the robot decreased the time consumption from 12% to 86% than previous algorithms.

• 산경연구논집
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• 제14권1호
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• pp.29-37
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• 2023

Purpose: This study is to explore how to enhance an organizational citizenship behavior (OCB) for private companies, boosting their employees; performance. With OCB in place, businesses won't have to worry about employees engaging in harmful or counterproductive actions. Better coordination will benefit employees' skill sets and the company's overall performance. Research design, data and methodology: We used a data extraction form and present it as an appendix. These forms could demonstrate to the reader what the present authors looked for and how they found it. We also investigated to obtain text datasets whether any extractions were carried out in duplicate, and, if so, whether duplicate abstraction was carried out independently. Results: There are four solutions to boost employees' OCB for HR practitioners: 'Creating an Environment that Supports Constructive OCB', 'Encouraging Productive Behavior in the Workplace and Reward properly, 'Integrating Corporate Citizenship into Performance Evaluations', and 'Training to Use OCB and Educating on its Benefits'. Conclusions: Based on the research findings of the current study, this study strongly concludes that OCB should be encouraged, and employers and employees should collaborate on efforts to boost morale and increase productivity. As a direct result of their efforts, their firms enjoy improved earnings while experiencing reduced overhead costs.