• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.8
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• pp.3529-3550
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• 2016

In heterogeneous networks (HetNets), energy saving is vital for a sustainable network development. Many techniques, such as spectrum allocation, network planning, etc., are used to improve the network energy efficiency (EE). In this paper, micro BSs utilizing cell range expansion (CRE) and spectrum allocation are considered in multi-channel heterogeneous networks to improve EE. Hotspot region is assumed to be covered by micro BSs which can ensure that the hotspot capacity is greater than the average demand of hotspot users. The expressions of network energy efficiency are derived under shared, orthogonal and hybrid subchannel allocation schemes, respectively. Particle swarm optimization (PSO) algorithm is used to solve the optimal ratio of subchannel allocation in orthogonal and hybrid schemes. Based on the results of the optimal analysis, we propose three service control strategies on the basis of large-scale user behaviors, i.e., adjust micro cell rang expansion (AmCRE), adjust micro BSs density (AmBD) and adjust micro BSs transmit power (AmBTP). Both theoretical and simulation results show that using shared subchannel allocation scheme in AmBD strategies can obtain maximal EE with a very small area ratio. Using orthogonal subchannel allocation scheme in AmCRE strategies can obtain maximal EE when area ratio is larger. Using hybrid subchannel allocation scheme in AmCRE strategies can obtain maximal EE when area ratio is large enough. No matter which service control strategy is used, orthogonal spectrum scheme can obtain the maximal hotspot user rates.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1713-1715
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• 2007

Measurement of network traffic have shown that the self-similarity is a ubiquitous phenomenon spanning across diverse network environments. In previous work, we have explored the feasibility of exploiting the long-range correlation structure in a self-similar traffic for the congestion control. We have advanced the framework of the multiple time scale congestion control and showed its effectiveness at enhancing performance for the rate-based feedback control. Our contribution is threefold. First, we define a modular extension of the TCP-a function called with a simple interface-that applies to various flavours of the TCP-e.g., Tahoe, Reno, Vegas and show that it significantly improves performance. Second, we show that a multiple time scale TCP endows the underlying feedback control with proactivity by bridging the uncertainty gap associated with reactive controls which is exacerbated by the high delay-bandwidth product in broadband wide area networks. Third, we investigate the influence of the three traffic control dimensions-tracking ability, connection duration, and fairness-on performance.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.4
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• pp.346-352
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• 2006

In a networked control system (NCS), time delays which are larger than one sampling period can change the control period. As a result, it may cause system instability. This paper presents a control method for an NCS using the controller area network (CAN), where time delays arise in the control loop. Specifically, a simple yet efficient method is proposed to improve control performance in the presence of time delays. The proposed method, which can be regarded as a gain scheduling method, selects a suitable LQ control gain among several gains to deal with the problems due to the change of control period. It is found that the gain can be scheduled in terms of the relation between the gain and the sampling period, which is represented by first-order algebraic equations. The proposed method is evaluated with an inverted cart pendulum system where the actuator and sensors are connected through the CAN. Experiment results are presented to show the efficiency of the proposed method.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.12
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• pp.4385-4399
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• 2021

The Internet of Things (IoT) eHealth systems composed by Wireless Body Area Network (WBAN) has emerged recently. Sensor nodes are placed around or in the human body to collect physiological data. WBAN has many different applications, for instance health monitoring. Since the limitation of the size of the battery, besides speed, reliability, and accuracy; design of WBAN protocols should consider the energy efficiency and time delay. To solve these problems, this paper adopt the end-edge-cloud orchestrated network architecture and propose a transmission based on reinforcement algorithm. The priority of sensing data is classified according to certain application. System utility function is modeled according to the channel factors, the energy utility, and successful transmission conditions. The optimization problem is mapped to Q-learning model. Following this online power control protocol, the energy level of both the senor to coordinator, and coordinator to edge server can be modified according to the current channel condition. The network performance is evaluated by simulation. The results show that the proposed power control protocol has higher system energy efficiency, delivery ratio, and throughput.

• Journal of Ocean Engineering and Technology
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• v.12 no.3 s.29
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• pp.96-102
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• 1998

This paper presents to create a SAC(Sectional Area Curve) using an ANFIS(Adaptive-Network-based Fuzzy Inference System). First, it defines SACs of parent ships by using a B-spline approximation and a genetic algorithm and accumulates a database about SAC's control points. Second, it learns an ANFIS from parent ship data, which are related with principal dimensions and SAC's control points. This process is to model an ANFIS for SAC inferreice. When an ANFIS modeling is completed, we can determine a SAC through an ANFIS inferring.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.10
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• pp.1051-1058
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• 2011

Unmanned autonomous forklifts have a great potential to enhance the productivity of material handling in various applications because these forklifts can pick up and deliver loads without an operator and any fixed guide. Especially, automation of pallet loading and unloading technique is useful for enhancing performance of logistics and reducing cost for automation system. There are, however, many technical difficulties in developing such forklifts including localization, map building, sensor fusion, control, and so on. This is because the system requires numerous sensors, actuators, and controllers that need to be connected with each other, and the number of connections grows very rapidly as the number of devices grows. This paper presents a vision sensorbased autonomous loading and unloading for network-based unmanned forklift where system components are connected to a shared CAN network. Functions such as image processing and control algorithm are divided into small tasks that are distributed over a number of microcontrollers with a limited computing capacity. And the experimental results show that proposed architecture can be an appropriate choice for autonomous loading in the unmanned forklift.

• Korean Journal of Psychosomatic Medicine
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• v.4 no.2
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• pp.226-244
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• 1996

This study was designed to evaluate the social support network of schizophrenic patients. 64 schizophrenic patients being treated as out-door patient were compared with 30 neurotic control patients. Schizophrenics were divided into positive, subpositive, subnegative and negative subgroups by present symptom and social network of both schizophrenics and control group were evaluated. The results are as follows: 1) Social network of schizophrenics was smaller than that of control group. Size of social network of schizophrenics was 10.6 and that of control group was 23.5. 2) In both kin and nonkin, social network of schizophrenics was smaller than that of control group. Of the kin, schizophrenics were more supported by wife or husband, father, and mother, but were less supported by brother, son and other relatives. 3) There was no difference in the kin or nonkin or total supporters between the four subgroups of schizophrenics. But, subgroup of schizophrenics which was divided as having negative symptom had smaller network than control group in active formal and informal supporters. 4) When divided into 4 support areas, schizophrenics was remarkably less supported in emotional, instrumental and appraisal support area than control group, but there was no difference in the informational support areas. 5) Compared with control group, schizophrenics more often mentioned parent and ten often mentioned nonkin supporter as the one that is most important to him. 6) Schizophrenics had smaller cluster and less leisure activity than control group. Subgroup of schizophrenics who was divided as having negative symptom had less frequency of leisure activity than other subgroups.

• Journal of Korea Society of Digital Industry and Information Management
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• v.8 no.1
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• pp.9-15
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• 2012

Multiple convenience features have been getting installed in recently released cars. However, the control of them has many uncomfortable matters yet. To resolve them, it is needed to study how to use easier the convenience features and control them remotely. Currently, wide range of convergence services are being released in various industries by using smartphone and smartphones with its state-of-the-art functions also are being released. In this paper, we design and implement smartphone-based applications for controling the vehicle's convenience features to control the vehicle convenience features with smartphone. To do this, we configure CAN (Controller Area Network) communication between the vehicle's various convenience features, and establish MCU (Micro Controller Unit) to control each feature. We also connect between the MCU and smartphones to make them available for the remote control. We can control lights, turn signals, audio, windows, air conditioner, and so on with the implemented smartphone-based control service of vehicle's convenience features using CAN remotely.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.43 no.4 s.310
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• pp.15-22
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• 2006

Nowadays, there is called energy saving, that it is accomplished with a lot study and application development as according to demand of all around world. It is using to network device of wire or wireless such as internet, lan, plc, and zigbee and that we should be accomplished to study about method that spending a little cost to fatal error in control system that be expected of frequent occurrence on network, and that have method to do construction a little bit tried out. Also, in that such a embedded system with network function case, there is important thing that it is remote management to network node and control methods to trust because firmware upgrade have the advantage of more than the other device. In this paper, we have verified through a result of experiment for efficient remote management and control method as previously stated in this paper, that it is area of the PLC for sensor node and doing management to relay, and implementation of the LACC which is core part of the ESS, and in order to get a result to trust from doing analysis of capacity and test.

• International Journal of Computer Science & Network Security
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• v.23 no.1
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• pp.71-77
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• 2023

In the current Internet system, there are many problems using anonymity of the network communication such as personal information leaks and crimes using the Internet system. This is why TCP/IP protocol used in Internet system does not have the user identification information on the communication data, and it is difficult to supervise the user performing the above acts immediately. As a study for solving the above problem, there is the study of Policy Based Network Management (PBNM). This is the scheme for managing a whole Local Area Network (LAN) through communication control for every user. In this PBNM, two types of schemes exist. As one scheme, we have studied theoretically about the Destination Addressing Control System (DACS) Scheme with affinity with existing internet. By applying this DACS Scheme to Internet system management, we will realize the policy-based Internet system management. In this paper, to realize it, concept of the Internet PBNM Scheme is proposed as the final step.