• Korean Journal of Computational Design and Engineering
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• v.10 no.1
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• pp.40-48
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• 2005

A hydraulic hose is an important part of the hydraulic system which transmits power using pressurized fluids. It allows relative motion between components at each end of the hose assembly, and it is much easier to route a hose assembly than it is to bend and install a rigid tubing assembly. Unnecessary loads, which drop the hose's pressure capability and shorten service life, depend on a hose-routing. Therefore, the Hydraulic system designers must be aware to consider unnecessary load does not affect the here. For this consideration in an early stage of the design process, CAD system must support the hose assembly routing design function which is to generate routing path and design fitting angle properly. This paper proposes 2 methods. One is to generate curves that are similar to routing paths of the real hose assembly using the energy minimization method and the optimization method. The other is to design fitting angles that are important design elements of a hose assembly using the Parallel Transport Frame. To implement the proposed methods above, commercial CAD software, CATIA has been integrated with our program.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.7
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• pp.3018-3040
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• 2018

The mobility model is one of the most important factors that impacts the evaluation of any transportation vehicular networking protocols via simulations. However, to obtain a realistic mobility model in the dynamic urban environment is a very challenging task. Several studies extract mobility models from large-scale real data sets (mostly taxi GPS data) in recent years, but they do not consider the statuses of taxi, which is an important factor affected taxi's mobility. In this paper, we discover three simple observations related to the taxi statuses via mining of real taxi trajectories: (1) the behavior of taxi will be influenced by the statuses, (2) the macroscopic movement is related with different geographic features in corresponding status, and (3) the taxi load/drop events are varied with time period. Based on these three observations, a novel taxi mobility model (T-START) is proposed with respect to taxi statuses, geographic region and time period. The simulation results illustrate that proposed mobility model has a good approximation with reality in trajectory samples and distribution of nodes in four typical time periods.

• Journal of the Korea Society of Computer and Information
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• v.22 no.7
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• pp.101-108
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• 2017

A wireless image sensor node collecting image data for environmental monitoring or surveillance requires a large amount of energy to transmit the huge amount of video data. Even though solar energy can be used to overcome the energy constraint, since the collected energy is also limited, an efficient energy management scheme for transmitting a large amount of video data is needed. In this paper, we propose a method to reduce the number of blackout nodes and increase the amount of gathered data by selecting an appropriate video coding method according to the energy condition of the node in a solar-powered wireless video sensor network. This scheme allocates the amount of energy that can be used over time in order to seamlessly collect data regardless of night or day, and selects a high compression coding method when the allocated energy is large and a low compression coding when the quota is low. Thereby, it reduces the blackout of the relay node and increases the amount of data obtained at the sink node by allowing the data to be transmitted continuously. Also, if the energy is lower than operating normaly, the frame rate is adjusted to prevent the energy exhaustion of nodes. Simulation results show that the proposed scheme suppresses the energy exhaustion of the relay node and collects more data than other schemes.

• Computers and Concrete
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• v.25 no.4
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• pp.327-341
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• 2020

Advanced forms of structural design (e.g., displacement-based methods) require knowledge of the non-linear force-displacement behavior of both the overall building and individual lateral load resisting elements, i.e., walls or building cores. Similarly, understanding the non-linear behaviour of the elements in a structure can also allow for a less conservative structural response to be calculated by better understanding the cracked (i.e., effective) properties of the various RC elements. Calculating the non-linear response of an RC section typically involves using 'black box' analysis packages, wherein the user may not be in complete control nor be aware of all the intricate settings and/or decisions behind the scenes. This paper introduces a user-friendly and transparent analysis program for predicting the back-bone force displacement behavior of slender (i.e., flexure controlled) RC walls, building cores or columns. The program has been validated and benchmarked theoretically against both commonly available and widely used analysis packages and experimentally against a database of 16 large-scale RC wall test specimens. The program, which is called WHAM, is written using Microsoft Excel spreadsheets to promote transparency and allow users to further develop or modify to suit individual requirements. The program is available free-of-charge and is intended to be used as an educational tool for structural designers, researchers or students.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.2
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• pp.494-513
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• 2019

A multi-channel access problem based on hypergraph model in ultra-dense small cell networks is studied in this paper. Due to the hyper-dense deployment of samll cells and the low-powered equipment, cumulative interference becomes an important problem besides the direct interference. The traditional binary interference model cannot capture the complicated interference relationship. In order to overcome this shortcoming, we use the hypergraph model to describe the cumulative interference relation among small cells. We formulate the multi-channel access problem based on hypergraph as two local altruistic games. The first game aims at minimizing the protocol MAC layer interference, which requires less information exchange and can converge faster. The second game aims at minimizing the physical layer interference. It needs more information interaction and converges slower, obtaining better performance. The two modeled games are both proved to be exact potential games, which admit at least one pure Nash Equilibrium (NE). To provide information exchange and reduce convergecne time, a cloud-based centralized-distributed algorithm is designed. Simulation results show that the proposed hypergraph models are both superior to the existing binary models and show the pros and cons of the two methods in different aspects.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.11
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• pp.3603-3618
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• 2022

The offloading method is important when there are multiple mobile nodes and multiple edge servers. In the environment, those mobile nodes connect with edge servers with different bandwidths, thus taking different time and energy for offloading tasks. Considering the system load of edge servers and the attributes (the number of instructions, the size of files, deadlines, and so on) of tasks, the energy-aware offloading problem becomes difficult under our mobile edge environment (MCE). Most of the past work mainly offloads tasks by judging where the job consumes less energy. But sometimes, one task needs more energy because the preferred edge servers have been overloaded. Those methods always do not pay attention to the influence of the scheduling on the future tasks. In this paper, first, we try to execute the job locally when the job costs a lower energy consumption executed on the MD. We suppose that every task is submitted to the mobile server which has the highest bandwidth efficiency. Bandwidth efficiency is defined by the sending ratio, the receiving ratio, and their related power consumption. We sort the task in the descending order of the ratio between the energy consumption executed on the mobile server node and on the MD. Then, we give a "suffrage" definition for the energy consumption executed on different mobile servers for offloading tasks. The task selects the mobile server with the largest suffrage. Simulations show that our method reduces the execution time and the related energy consumption, while keeping a lower value in the number of uncompleted tasks.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.7
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• pp.1296-1306
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• 2015

Nowadays the research of energy saving on the IP networks have been studied the various methods in many research institutes. This paper suggests the energy saving method in IP networks which have the various energy profiles, and analyzes its energy saving characteristics in detail. Especially this paper proposes the energy profile based OSPF routing method which have the selectable weighted value in OSPF metric and energy consumption in IP network. This paper analyzes the energy saving effects of the various situations to minimize the energy consumption using the various weighted value on the proposed scheme. The results show that the energy saving efficiency can get about 67% at in ingress input load ${\rho}=0.5$ by using random energy profiles in IP networks. Although the number of hops is a slight increased due to routing the paths for the minimum energy consumption in the algorithm of this method, the increment hop number is limited the mean 1.4 hops. This paper confirms that the energy profile of core router has the large effects of energy saving than the energy profile of edge router, and the proposed method has the excellent energy saving characteristics in IP networks.

• Journal of the Korea Fashion and Costume Design Association
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• v.19 no.4
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• pp.105-121
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• 2017

This study determined the reality of how middle school students are doing with their free learning semester and what they think about it. Also, the study looked at how many parts of Home Economics and the area of clothing curriculum are being taken and, especially, how many parts of this curriculum content are being required as free learning semester activities. This study aims to not only develop free learning semester activities according to student demand but also at providing a basic resource that can help activate the area of clothing curriculum in subject of Home Economics. In short: 1) Middle school students are attending activities such as career exploration activities, student selection activities, club activities, arts activities and physical education activities thoroughly through the free learning semester. These mostly take place in school and most of the students were taught by teachers from their own school. 2) The students are aware that the free learning semester's activities are helpful for them. The most helpful part was that it reduces the load they get from the school's exam and also the fact that they can investigate areas in which they are interested. 3) The number of students who have already taken or are taking activities related to Home Economics were 145, which is about 1/3 of the 451 students overall. The area where the most of the activities were held out of those activities related to Home Economics was the domain of food while the clothing curriculum accounted for a very small part compared to it. 4) The study found that need for a clothing curriculum for middle school student free learning semesters was about 2.79 on a scale from 1 to 5. The areas of most interest in this topic were highly related to 'making and mending clothes'.

• International Journal of Control, Automation, and Systems
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• v.3 no.spc2
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• pp.315-321
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• 2005

Interactions among multiple control functions of a UPFC installed in a power system have been observed in power system simulation and been reported in authors' previous publications [1,2]. This paper presents new analytical results about these observed interactions and concludes that they are due to the control conflict between the series and shunt part of the UPFC, which are connected through the internal common capacitor inside the UPFC. Investigation in the paper reveals, for the first time as far as the authors are aware of, that the linkage pattern of UPFC series and shunt part decides whether the control functions implemented by the UPFC series and shunt part conflict each other or not. This linkage pattern of UPFC series and shunt part can be described by the flow of active power through the UPFC at steady-state operation of the power system. Hence in order to predict the possible interactions among multiple control functions of the UPFC, an interaction indicator is proposed in the paper which is the direction and amount of active power flow through the internal link of the UPFC series and shunt part at steady-state operation of the power system. This proposed interaction indicator can be calculated from power system load flow solution without having to run simulation of the power system with UPFC controllers installed. By using the indicator, the interactions among multiple control functions of the UPFC caused by badly set controller's parameters are excluded. Therefore the indicator only identifies the possible existence of inherent control conflict of the UPFC.

• Computational Structural Engineering
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• v.10 no.3
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• pp.167-174
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• 1997

Engineers must be aware of possible sources of chaotic behavior. They may render conventional design predictions untrustworthy and potentially unsafe because of the sensitivity to initial conditions. Dynamic responses of a spherical shell subjected to impulsive loading which act on the center are analyzed using the finite element method. The chaotic responses are identified by the standard methods, such as displacement-time histories, Poincare maps, and phase diagrams. The responses are chaotic, but, not so sensitive to the initial conditions, and the characteristics of responses are not changed with time, in contrast to the case of the responses of beam. The Poincare points scattered in the limited area represent that the responses are chaotic, but do not show the geometric structures. The snap-through phenomena of the shell to the side of the direction of the load or of the opposite direction, is analysed by using the energy diagram.