• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.11
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• pp.2205-2217
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• 2015

Bio-inspired routing protocol uses a principle of swarm intelligence, which finds the optimal path to the destination in a distributed and autonomous way in dynamic environments, so that it can maximize routing performances, reduce control overhead, and recover a path failure quickly according to the change of network topology. In this paper, we propose a bio-inspired routing protocol for mobile ad hoc networks. The proposed scheme uses a function of overhearing via wireless media in order to obtain the routing information without additional overhead. Through overhearing, the pheromone is diffused around the shortest path between the source and destination. Based on this diffused pheromone, a probabilistic path exploration is executed and the useful alternative routes between the source and destination are collected. Therefore, the proposed routing protocol can ensure the up-to-date routing information while reducing the control overhead. The simulation results show that the proposed scheme outperforms the typical AODV and AntHocNet protocols in terms of routing performances and significantly decreases the routing overhead against the AntHocNet.

• Journal of the Institute of Convergence Signal Processing
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• v.8 no.1
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• pp.78-83
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• 2007

Robot collects surrounding information to recognize tile unknown environment by using various sensors such as visual, infrared ray and ultra sonic sensors. Although visual sensor is the most popular one, it has some difficulties in collecting data in dark or too bright environment due to sensitivity of the light. It also requests significant amount of calculation on collecting data from certain images with marked, straight and curved ones. As an alternative, ultra sonic sensor can simply overcome this visual sensing system's flaw and easily be used. It is easier than visual system, especially in case of collecting data on object and distance in dark environment. Ultra sonic sensor can replace the expensive visual sensing system not only in avoiding obstacles but also in reaching to the target area smoothly. The purpose of this paper is to develop the algorithm to optimize the environmental recognition, path planning and free-ranging by minimizing errors caused by inaccurate information and by considering characteristics of the ultra sonic rays such as refraction and diffusion. This paper also realizes the system that can recognize the environment and make the appropriate path planning by applying the algorithm on this moving robot.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.9
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• pp.1216-1223
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• 2018

As field of application of AMI, AMR uses the power line as the primary means of communication. PLC has a big merit without installation of the new network for communication in a field using the power line which is the existing equipment. However, there is a serious obstacle in commercialization for the instability by noise and communication environment. Therefore, the technical method for maintaining the communication state which overcome such demerit and was stabilized is required essentially. PLC routing technology is applied with the alternative plan now. The routing technology currently managed by field includes many problems by applying the algorithm of an elementary level. PLC routing path search problem can be modeled with the problem of searching for optimal solution as similar to such as optimal routing problem and TSP(Travelling salesman problem). In this paper, in order to search for a PLC routing path efficiently and to choose the optimal path, GA(Genetic Algorithm) was applied. Although PLC was similar in optimal solution search as compared with typical GA, it also has a difference point by the characteristic of communication, and presented the new methodology over this. Moreover, the validity of application technology was verified by showing the experimental result to which GA is applied and analyzing as compared with the existing algorithm.

• Journal of the Korean Society of Hazard Mitigation
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• v.11 no.3
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• pp.49-56
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• 2011

This paper deals with a methodology for searching optimal route of hazard material (hazmat) vehicles. When we make a decision of hazmat optimal paths, there is a conflict between the public aspect which wants to minimize risk and the private aspect which has a goal of minimizing travel time. This paper presents Efficient Vector Labeling algorithm as a methodology for searching optimal path of hazmat transportation, which is intrinsically one of the multi-criteria decision making problems. The output of the presented algorithm is a set of Pareto optimal paths considering both risk and travel time at a time. Also, the proposed algorithm is able to identify non-dominated paths which are significantly different from each other in terms of links used. The proposed Efficient Vector Labeling algorithm are applied to test bed network and compared with the existing k-shortest path algorithm. Analysis of result shows that the proposed algorithm is more efficient and advantageous in searching reasonable alternative routes than the existing one.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.17 no.6
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• pp.211-223
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• 2018

Mobile relay systems have been adopted by $4^{th}$ generation mobile systems as an alternative method to extend cell coverage as well as to enhance the system throughput at cell-edges. In order to achieve such performance gains, the mobile relay systems require path selection and resource allocation schemes that are specifically designed for these systems which make use of additional radio resources not needed in single-hop systems. This paper proposes an integrated path selection and resource allocation scheme for LTE-Advanced relay systems using collaborative communication. We first define the problem of maximizing the downlink throughput of LTE-Advanced relay systems using collaborative communication and transform it into a multi-dimensional multi-choice backpacking problem. The proposed Lagrange multiplier-based heuristic algorithm is then applied to derive the approximate solution to the maximization problem. It is shown through simulations that the approximate solution obtained by the proposed scheme can achieve a near-optimal performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.5B
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• pp.539-548
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• 2011

We propose an efficient cooperative ARQ (Automatic Repeat reQuest) scheme for single-hop and multi-hop underwater acoustic communications, in which cooperative nodes are used to provide more reliable alternative paths for a specific source-to-destination connection. This alternative path has higher channel quality than that of the direct source-destination path. In addition, during a packet-relay through multiple hops, the typical acknowledgement (ACK) signal is replaced with overhearing data packet returned back from the next hop. The usage of overhearing as an ACK improves the system performance. In this paper, we evaluate the proposed scheme by comparing it with a conventional S&W ARQ in terms of throughput efficiency. Computer simulation results show that the proposed cooperative retransmission scheme can significantly improve the throughput by increasing the probability of successful retransmission.

• The Journal of Korean Academy of Prosthodontics
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• v.28 no.2
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• pp.217-229
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• 1990

The Applegate-Kennedy classification, the drawing of removable partial denture design using color coding, the selective tissue placement impression method in case of Class I and Class II removable partial dentures, the design of the swing lock attachment of an alternative approach to conventional removable partial denture, the design of the intracoronal or extracoronal attachment, and the removable partial denture design using a rotational path were presented. The following conclusions from the above things were presented : 1. The swing lock attachment removable partial denture can be effective to an alternative approach when the design of conventional removable partial denture is improper with markedly mobile remaining teeth or missing key abutments. 2. Intracoronal or extracoronal attachments must be selected care-fully considering the conditions of the abutment teeth and alveolar ridge whether more occlusal loads to the abutment teeth or to the alveolar ridge are distributed. 3. It must be almost prerequisite that a functional impression is taken in case of Class I and class II removable partial dentures and in case of tooth-borne removable partial dentures, a removable partial denture using rotational path is strong, hygienic, esthetic, and can be accomplished successfully in the clinical aspect when it is properly designed and fabricated through the complete understanding of an indication and a principle. 4. All necessary informations must be achieved with carefully investigated surveying procedure according to each clinical case by Applegate-Kennedy classification which can be helpful and useful in the clinical application and it is important that dentists themselves must be in the habit of drawing a reasonable partial denture design using a color coding in the paper sheet.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.5
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• pp.69-77
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• 2017

This paper introduces an optical encoder using the reflection in the slit. The digital optical encoder is a sensor to generate a pulse according to the displacement. An optical encoder is composed of 3 parts: light source, slit plate and light-receiving element. In a conventional encoder, one slit produces one signal. The resolution of the digital optical encoder is determined by the number of slits in the encoder plate. The small slit size is most important among the factors that determine the resolution in a generic-type optical encoder. However, a small slit has low productivity and technical difficulties, so analog optical encoders have emerged as an alternative. Nonetheless, this alternative requires additional circuitry and equipment because of the noise and drafts in the analog signals. A new sensor is presented in this paper with a high resolution and a slit of the same size using the reflection in the slit. Then, the path of the light that passes through the slit ccording to the shape was analyzed, and some paths were expressed in the mathematical expressions. In addition, the optical paths were analyzed in the rectangular, octagonal, and circular encoders, and shown the obtained number of signals per slit by using them. Thus, we confirm that this method has the best performance in circle-shaped slits.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.5
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• pp.825-834
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• 2021

With the development of various devices and Internet platforms, production and demand for content are increasing rapidly. However, effective response to exponentially increasing data usage is difficult in current TCP/IP schemes. As a result, with the emergence of an alternative called CCN, data can be transmitted and received from the host-centered to the content-oriented, and large-capacity content can be handled with more mitigated network resources. In this paper, we will address intermediate node mobility, which is one of the areas studied in CCN. In CCN, real-time services are a very important factor for information providers as well as requestors. However, when a node departure situation occurs, packet transmission and transmission speed decreases. Therefore, to ensure these numbers, even if the intermediate node deviates using a dual path, it provides a complete QoS (Quality of Service) using an alternative path.

• Structural Engineering and Mechanics
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• v.70 no.4
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• pp.381-394
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• 2019

If an alternative path would not be considered for redistribution of loads, local failure in structures will be followed by a progressive collapse. When a vertical load-bearing element of a steel structure fails, the beams connected to it will lose their support. Accordingly, an increase in span's length adds to the internal forces in beams. The mentioned increasing load in beams leads to amplifying the moments there, and likewise in their corresponding connections. Since it is not possible to reinforce all the elements of the structure against this phenomenon, it seems rational to use other technics like specified strengthened connections. In this study, a novel connection is suggested to handle the stated phenomenon which is introduced as a passive connection. This connection enables the structure to tolerate the added loads after failing of the vertical element. To that end, two experimental models were constructed and thereafter tested in half-scale, one-story, double-bay, and bolted connections in three-dimensional spaces. This experimental study has been conducted to compare the ductility and strength of a frame that has ordinary rigid connections with a frame containing a novel passive connection. At last, parametric studies have been implemented to optimize the dimensions of the passive connection. Results show that the load-bearing capacity of the frame increased up to 75 percent. Also, a significant decrease in the displacement of the node wherein the column is removed was observed compared to the ordinary moment resisting frame with the same loads.