Earticle

미래의 창의적인 문제해결력을 지닌 인재 양성을 위해, 본 연구는 초등학생들에게 지도하기 어렵고 학생들이 이해하기 힘든 컴퓨터과학원리 중 라우팅알고리즘에 대한 교수․학습방법을 설계해 이를 지도해 보고 이러한 학습내용이 초등학교 학생들이 이해할 수 있는지를 알아보고자 하는데 그 목적이 있다. 사전․사후 동형 검사지를 통해 지적인 영역을 평가하고, 수업 후의 소감문을 통해 정의적인 영역을 평가하였다. 그 결과 네트워크 중 라우팅알고리즘이 초등학생에게 가르쳐질 수 있음을 확인하고 초등학교 컴퓨터교육의 학습요소로서의 가능성을 제시한다.

The purpose of this study is to design and practice teaching and learning method for routing algorithm among computer science principle which is difficult to be taught to elementary school students and understood by students. And we find out whether elementary school students can understand those learning contents. Intellectual area was assessed through equivalent test paper before and after the test and emotional area was assessed through students' impressions after class. The test showed that routing algorithm could be taught to children. Therefore, this study presents the learnability of routing algorithm as a learning element of elementary school computer education.

무선 IoT 네트워크는 낮은 전력을 사용하여 장거리에서도 통신이 가능하도록 설계되어야 한다. 이를 위한 기존의 라우팅 프로토콜은 상향 링크로의 데이터 전송만을 고려하였다. 그러나 IoT 기기들을 제어해야 하는 경우에는 하향 링크로의 전송 또한 필요하며 제어 메시지 전송은 일반 데이터 전송과 달리 100% 신뢰성을 보장해야 하는데 양방 향 전송으로 인해 트래픽이 많아질 경우 경쟁기반의 MAC 프로토콜로는 안정적인 데이터 전송이 불가능하다. 따라 서 본 논문에서는 중앙 통제하의 스케줄링 기반 라우팅 프로토콜을 사용한 IoT 네트워크 설계 방법을 제안한다. 제 안한 방법은 중앙의 스케줄링 기반으로 경로 설정과 패킷 전송을 제어하여 패킷 충돌을 사전에 방지한다. 또 경로 설정 시 양방향 모두 PER, RSSI, LQI 등의 파라미터를 고려하고, 간섭에 강하고 장거리 통신이 가능한 424MHz 대역을 사용하여 안정적인 링크를 설정한다. 시뮬레이션이 아닌 필드실험을 위하여 PCB 제작된 통신모듈로 실험 을 하였으며, 실험 결과 제안한 방법이 매우 안정적으로 데이터를 전송함을 확인할 수 있었다.

Communication over long distance using low power are the basic requirements for wireless IoT network. Current IoT network routing protocols only handles uplink transmissions. However, to control these IoT devices, downlink data transmissions are required. For the control message transmissions, it should have 100% reliability unlike other data transmission. Moreover, since traffic will be increased by bi-directional transmission, stable data transmission will not be possible with a contention-based MAC layer alone. Therefore, this paper proposes IoT network design using centralized scheduling-based routing protocol. The proposed method sets the path, and sends packets based on the central scheduling to prevent packet collision in advance. Bi-directional reliable links are established by considering parameters such as PER, RSSI and LQI using 424MHz band which is strong against interference and available for long distance communication. Experimental results show that the proposed method transmits data with high reliability.

본 논문은 P2P 시스템에서 분산 데이터 저장과 획득을 위한 신뢰성 있는 라우팅 방법인 KTree의 설계와 실험 평가를 다룬다. 많은 노드들이 시스템에 들어오고 나가는 상황에서도 KTree는 효율적인 라우팅을 가능하게 하여 자료 공유를 포함한 다양한 응용에 이상적인 선택이다. KTree에서 각각의 노드는 식별자 공간에 속하는 고유한 식별자를 갖는다. KTree는 식별자 공간을 층과 칸으로 나누고 각 칸마다 관리 노드를 정한다. 질의를 전달하기 위해서 각 노드는 다음 층의 일정한 숫자의 노드들과의 연결을 유지한다. 또한 시스템 전체에 대한 시야 확보를 위해서 각 노드는 꼭대기 층에 있는 노드와의 연결도 유지한다. 이러한 방법으로 KTree는 질의를 목적지까지 보내기 위해서 log(n) 개의 노드를 거치게 된다. 삽입 연산은 데이터를 여러 노드에 저장한다. 검색 연산은 이렇게 저장된 데이터를 효율적이고 안정적으로 되찾는다. PeerSim에 구현한 KTree의 시험적 구현을 통해서 신뢰성과 효율성을 확인할 수 있었다. 50,000 노드의 네트워크를 대상으로 한 실험 결과에서 노드들의 잦은 상태 변경에도 메시지를 잘 전달 할 수 있음을 확인할 수 있었다.

This paper discusses the design and evaluation of KTree, a reliable constant degree distributed hash table (DHT) for distributed data storage and retrieval for peer-to-peer systems. KTree’s ability to route efficiently even when a large number of nodes are joining and/or leaving the system makes it an ideal choice for different sort of applications including data sharing. Each node in KTree has a unique node identifier belonging to an identifier space. In KTree, we partition the identifier space into levels and segments and fix the manager of every segment. A node in KTree maintains links with a constant number of nodes at the next level to forward queries. A node also creates a link with a node at the top level to get the global view of the system. This way KTree traverses a logarithmic number of nodes to route a query to its destination. An insert operation stores a key on a number of diverse nodes. The lookup operation, on the other hand, retrieves the stored data efficiently and reliably. A prototype implementation of KTree on PeerSim proves its reliability and efficiency. The experimental results achieved with a network of 50,000 nodes confirm its self-configurability and ability to route messages even under a high rate of churn.

The ubiquitous computing system is expected to be widely utilized in digital home, logistics control, environment/disaster management, medical/health-care services and other applications. The ubiquitous sensor network (USN) is a key infra-structure of this system. Nodes in the USN are exposed to adverse environments and required to perform their missions with very limited power supply only. Also the sensor network is composed of much more nodes. In case some node consumes up its power capacity under a certain required level, the network topology should change and re-routing/re-transmission of data is necessitated. Resultantly communication protocols studied for conventional wireless networks or ad-hoc networks are not suitable for the sensor network. Schemes should be devised to control the efficient usage of node power in the sensor network. This paper proposes a routing algorithm to enhance the efficiency of power consumption for USN node and analyzes its performance by simulation.

Nodes in mobile networks change position randomly and quickly so modify their attachment point to the network. A most suitable method for handoff in core of the network is MPLS. For MPLS-TE, the most critical issue is LSP configuration. The goal of the routing algorithms in MPLS-TE is resource management and satisfy QoS metrics. The promising new SDN architecture can be a useful help to MPLS-TE due to its good features. This paper introduces a novel and low complexity SDN-MPLS algorithm. The proposed algorithm advances bandwidth-restricted routing as it trade-offs between network load balancing, route length, energy-saving with low complexity in mobile networks.

Wireless sensor networks are susceptible to a variety of network attacks. Due to the limited energy of nodes and selfish nodes in the network, the packet delivery rate is lower. To address these issues, we innovatively propose an energy-harvesting Q-learning secure routing algorithm with authenticated-encryption. The algorithm uses physical unclonable functions and optimized Q-learning to ensure that the transmission path is reliable. Meanwhile, we combine the LSTM-based prediction model to predict the energy value that the nodes replenish. In addition, simulations are performed to compare the performances of the proposed algorithm with other algorithms under different attacks. The proposed algorithm has greater improvements in the packet delivery rate, filtering selfish nodes, and reducing node energy consumption.

이 논문은 IPTV, 원격 교육/건강과 같은 다중 사용자와 인터넷 브로드 캐스팅의 통신을 제공하고 멀티캐스트 라우팅 네트워크의 공유 경로를 구성하는 휴리스틱 알고리즘을 제안 한다. 노드 사이의 최대 지연의 측정, 평균 지연, 지연된 측정은 성능 분석을 위해 도입하였다. 알고리즘 성능의 열거 방법은 최저 지연과 함께 공유된 경로를 찾기 위한 최적된 솔루션을 사용하여 비교하였다. 라우팅 네트워크 하단의 노드들 사이의 지연을 균등하게 분배하고, 다른 알고리즘 보다 지연 추정을 이용한 알고리즘이 우수한 시뮬레이션 결과를 보여준다.

This paper proposes a heuristic algorithm to construct a shared-route in multicast routing networks that provide communications between multi-users such as IPTV, remote educations/health, and internet broadcasting. The measures of maximum delay, average delay, estimated delay between nodes are adopted for performance analysis. The performance of algorithm is compared with the optimal solution in which enumeration method is used to find the shared-route with minimum delay. Under the routing network with the uniformly distributed delay between nodes, the simulation results show that the algorithm using the estimated delay outperforms the other algorithms.

최근 무선 센서 네트워크에서 센서 노드의 에너지 효율성을 향상시켜 네트워크의 수명을 향상시키는 라우팅기법의 연구가 많이 수행되고 있다. 무선 센서 네트워크는 제한된 에너지 및 하드웨어 성능 때문에 배터리, 메모리 및 프로세서 등 모든 자원을 효율적으로 사용해야 하며, 이를 위해 관련 통신 프로토콜도 저-전력 소모를 달성할 수 있도록 설계하고 구현해야 한다. 센서 네트워크에 많이 사용되는 LEACH, HEED등과 같은 클러스터 기반의 라우팅 방식들은 클러스터 헤더들과 해당 멤버 노드들 간의 데이터 전달을 통하여 에너지의 효율성을 얻는다. 이 논문에서는 에너지를 효율적으로 사용할 수 있는 클러스터 라우팅 알고리즘을 제안하고 시뮬레이션을 이용하여 성능 결과를 제시한다.

Recently, a lot of researches have been done to increase the life span of network using the energy efficient sensor node in WSN. In the WSN environment, we must use limited amount of energy and hardware. Ther efore, it is necessary to design energy efficient communication protocol and use limited resources. Cluster b ased routing method such as LEACH and HEED get the energy efficient routing using data communication between cluster head and related member nodes. In this paper, we propose an energy efficient routing algori thm as well as performance result using simulation.

최근 무선 센서 네트워크(WSN : Wireless Sensor Network)에서 센서노드의 에너지 소모를 균등화 하고 효율성을 향상시켜 전제 네트워크의 수명을 최대화하기 위한 다양한 계층적 라우팅 프로토콜들이 제안되고 있다. 특히, 멀티-홉 기법이 향상된 에너지 효율성과 실제 적용 가능한 모델로 많은 각광을 받고 있다. 멀티-홉 기법에서는 센서 노드사이 거리에 따라 전송 에너지를 효율적으로 조절하는 것이 가능하다고 가정한다. 이 논문에서는 대표적인 클러스터 알고리 즘인 LEACH에 대하여 분석하고 이 알고리즘의 단점을 보완하고 에너지를 효율적으로 사용할 수 있는 지역-중앙 클러 스터 라우팅 알고리즘을 제안한다. 제안한 클러스터 라우팅 알고리즘과 LEACH의 성능을 시뮬레이션을 통해 성능을 평가하고 분석하고 NS-2 시뮬레이션을 이용하여 성능 결과를 제시한다.

Recently, lot of researches for the multi-level protocol have been done to balance the sensor node energy consumption of WSN and improve the node efficiency to extend the life of the entire network. Especially in multi-hop protocol, a variety of models have been proposed to improve energy efficiency and apply it to WSN protocol. In this paper, we analyze LEACH algorithm and propose new method based on center of local clustering routing algorithm in wireless sensor networks. We also perform NS-2 simulation to show the performance of our model.

VANET(Vehicular Ad-hoc Network)는 차량 간 네트워크를 구성하는 기술로 전송 노드 기준으로 전송 범위내의 이웃 노드들의 정보를 이용하여 목적지까지의 경로를 설정한다. 지리적 정보를 이용한 기존의 라우팅 프로토콜은 송신 노드 기준으로 중계 노드 및 목적지 노드까지 거리만 고려하기 때문에 통신에 필요한 노드의 밀도가 충분하지 못하면 네트워크 지연 및 단절을 초래할 수 있다. 이러한 문제점을 해결하기 위해 본 논문에서는 도시 기반의 VANET 환경에서 차량 간 안정적인 통신을 위해 구역 기반의 라우팅 알고리즘을 제안한다. 실제 도시 환경을 구역으로 나누고 목적지까지 거리뿐만 아니라 차량 밀도를 고려하여 최적의 통신 환경을 선택함으로써 패킷 손실률을 최소화 하였다. 성능을 평가하기 위해 구현한 결과 기존 연구 결과 보다 우수한 성능 결과를 보였다.

VANET(Vehicular Ad-hoc Network), which is a technology to create a network among vehicles, decides the route to the destination using information of neighbors within the transmission range as transmission nodes. The existing routing protocol which uses geographical information can cause delay and disconnection of the network when the density of nodes is not high enough to communicate because it only considers the distance of the relay nodes or destination nodes from the source nodes. To solve the problem, this dissertation suggests a routing algorithm based on zones for stable communications among vehicles in the environment of VANET. I minimize the packet loss rate by dividing the city environment into zones and taking into account not only the distance of the destination but also the density of vehicles to choose the best communications environment. This results in a better performance than the established research when the performance evaluation is implemented.

운행시간표 기반 대중교통 경로 탐색 알고리즘은 운행계획에 따른 정류장별 출·도착 시각 을 이용하여 최소 이동 시간이 소요되는 단일 경로를 산출한다. 다만, 경로 계산 과정에서 환승 저항, 대안 경로 선택 등의 추가 요소들을 반영하는데 한계가 있다. 본 연구는 환승 저 항 및 다중 경로 탐색이 반영된 개선된 RAPTOR 알고리즘을 제안한다. 환승 저항은 환승 시 점에 적용되며, 교통수단 유형을 구분하여 적용하였다. 본 연구에서는 수도권 대중교통 이용 승객의 실제 이동 경로를 기준으로 개선 전·후의 알고리즘 결과를 분석하였다. 이를 통해 제 시한 알고리즘이 승객의 다양한 경로 선택 기준을 반영한다는 것을 확인하였다.

Schedule-based public transit routing algorithm computes a single route that calculated minimum travel time using the departure and arrival times for each stop according to vehicle operation plan. However, additional factors such as transfer resistance and alternative route choice are not reflected in the path finding process. Therefore, this paper proposes a improved RAPTOR that reflected transfer resistance and multi-path searching. Transfer resistance is applied at the time of transfer and different values can be set according to type of transit mode. In this study, we analyzed the algorithm's before and after results compared with actual route of passengers. It is confirmed that the proposed algorithm reflects the various route selection criteria of passengers.

무선 센서 네트워크에서 에너지 효율성을 높이려는 연구가 많이 진행되어 왔다. 그러나 현재 이루어지고 있는 대부분의 연구는 클러스터 헤드와 싱크 노드들 사이의 직접적인 통신에 바탕을 두고 있다. 앞에서 이루어진 연구들은 노드들 사이의 거리에 따라 에너지를 계산하는 방식에 기초를 두고 있다. 거리에 따라 에너지를 계산하여 알고리즘을 구현하는 것은 어려운 문제가 된다. 이 논문에서는 싱크 노드에서 다른 모든 노드들까지 고정된 전파 파장의 반경을 갖는다단계 라우팅 알고리즘을 제안한다. 이 논문에서는 시뮬레이션을 이용하여 WSN이 에너지를 효율적으로 줄이는 것과WSNdp 활용 방안을 제시한다.

A lot of researches have been done to improve the energy efficiency of Wireless Sensor Networks. But all thecurrent researches are based on the idea of direct communication between cluster head and sink node. Previousresults assume that node can intelligently regulate signal energy according to the distance between nodes. It isdifficult to implement algorithms based on this assumption. We present a multi-level routing algorithm from thesink node to all other nodes which have fixed radio wave radius. We also show the energy saving efficiency andthe implementation in real WSN using the simulation result.

The large-scale disasters occur to unexpected accidents such as natural disasters(earthquake, typhoon, tsunami, etc.), and human-caused accidents(fire, collapse, terror etc.). Rescue teams perform rescue activities to save many lives in large-scale disaster area. The main purpose of this study is to compose a optimal routing planning for rescue of multiple victims in disaster area. A realistic routing planning with rescue limit time which considers rehabilitation and reconstruction will be suggested in this study. A mathematical programming model and a hybrid genetic algorithm will be suggested to minimize the total spending time. By comparing the result, the suggested algorithm gives a better solution than existing algorithms.

Wireless sensor network (WSN) is a distributed self-organizing network which contains a large number of tiny multi-functional sensor nodes. The network life time is an important issue in WSN because every sensor node has a constraint on electric supply. In this paper, an energy consumption model is described and a GA-based algorithm will be used to optimize the energy consumption by analyzing the working model of sensor nodes. The model will provide an effective reference of working pattern for WSN. This algorithm is evaluated through analysis and simulations.

According to Genetic algorithms principle, the new hybrid evolutionary algorithm (HEA) is proposed in this paper by combining the Immune algorithm, Genetic algorithm and Pareto optimal solutions. The HEA has high convergence precision and improved the diversity of population. Multiple near optimization paths can be developed by the algorithm with multi‐objective restriction, and satisfy to minimize the routing of transportation and the numbers of the vehicles. The HEA has been used to solve the vehicle routing problem, the results of simulation experiment show that the HEA can gain higher global convergence rate and higher speed.

Recently, a multi facility, multi product and multi period industrial problem has been widely investigated in Supply Chain Network(SCN). One of keys issues in the current SCN research area involves minimizing both production and distribution costs. This study deals with finding an optimal solution for minimizing the total cost of production and distribution problems in supply chain network. First, we presented an integrated mathematical model that satisfies the minimum cost in the supply chain. To solve the presented mathematical model, we used a genetic algorithm with an excellent searching ability for complicated solution space. To represent the given model effectively, the matrix based real-number coding schema is used. The difference rate of the objective function value for the termination condition is applied. Computational experimental results show that the real size problems we encountered can be solved within a reasonable time.

As the rapid increasing of Internet users from all over the world, it is necessary to enhance the reliability and compatibility of network when large number of data transferred frequently. One of the most important services is routing method since enormous data are transferred and exchanged within the network. This paper introduces an improved OSPF routing algorithm which uses the quotient and granularity space theory. Based on the simulation and experiments, several key findings are observed. Firstly, using the improved algorithm, the convergence time is much less than the no hierarchical network and the performance is better in terms of OSPF response. Secondly, it is found that the bandwidth utilization reaches 30Kbit/s, comparing with the network without hierarchy, the improvement is 40% that the bandwidth utilization increased from 18Kbit/s to 30 Kbit/s. The hierarchical network outperforms the one without layers.

Emergencies and disasters can happen any time without any warning, and things can change and escalate very quickly, and often it is swift and decisive actions that make all the difference. It is a responsibility of the building facility management to ensure that a proven evacuation plan in place to cover various worst scenario to handled automatically inside the facility. To mapping out optimal safe escape routes is a straightforward undertaking, but does not necessarily guarantee residents the highest level of protection. The emergency evacuation navigation approach is a state-of-the-art that designed to evacuate human livings during an emergencies based on real-time decisions using live sensory data with pre-defined optimum path finding algorithm. The poor decision on causalities and guidance may apparently end the evacuation process and cannot then be remedied. This paper propose a cloud connected emergency evacuation system model to react dynamically to changes in the environment in emergency for safest emergency evacuation using IoT based emergency exit sign system. In the previous researches shows that the performance of optimal routing algorithms for evacuation purposes are more sensitive to the initial distribution of evacuees, the occupancy levels, and the type and level of emergency situations. The heuristic-based evacuees routing algorithms have a problem with the choice of certain parameters which causes evacuation process in real-time. Therefore, this paper proposes an evacuee routing algorithm that optimizes evacuation by making using high computational power of cloud servers. The proposed algorithm is evaluated via a cloud-based simulator with different “simulated casualties” are then re-routed using a Dijkstra’s algorithm to obtain new safe emergency evacuation paths against guiding evacuees with a predetermined routing algorithm for them to emergency exits . The performance of proposed approach can be iterated as long as corrective action is still possible and give safe evacuation paths and dynamically configure the emergency exit signs to react for real-time instantaneous safe evacuation guidance.

With the development of Internet technology, network based activities such as e-commerce, internet voting and e-government, etc. have become increasingly frequent, People are increasingly concerned about the identity of network activity, content and other private information. In order to protect user privacy in network communications, governments, companies, universities and research institutes are pushing the research and development of the onion routing systems (TOR). Tor is the most popular anonymous communication system currently, which is based on technology of the second-generation onion routing. Tor has a low latency, encrypted data transmission, secure channel, etc., which are widely used in anonymous Web browsing, instant messaging, Secure Shell Client (SSH), etc. However, the development of the onion routing systems is constrained by complicated code factors. According to this situation, this paper put forward an overall architecture of TOR code, which contains Application Needs, Code Analysis and Improvement. This paper summarizes the overall framework of tor code structure, in order to make the code structure clearer, the whole code module is divided into several sub modules, using the function call diagram and UML diagram illustrates the main function of each module and call relation between each module. This paper gives code analysis for anonymous architecture of TOR. Finally, this paper put forward the improvement of routing algorithms of TOR. Based on this paper, a method has been created which is used to understand the tor code easily. Furthermore, systematic analysis of the tor code provided in this paper aims to research the working principle and promote the further development of the onion routing.