• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.4
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• pp.257-265
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• 2013

In this paper, we proposed a Dynamic Channel Assignment (DCA) scheme called Graph Coloring based DCA (GC-DCA) to improve system performance for downlink femtocell networks with high density femto Access Point (AP) deployments. The proposed scheme consists of two steps: one is a femto AP grouping step considering interference and the other is a DCA step considering Signal to Interference plus Noise Ratio (SINR) for femto User Equipments (UEs). Simulation results show that the proposed GC-DCA outperforms other schemes in terms of the mean femto UE capacity and probability of femto UEs which have capacities less than a given transmit rate.

• Archives of design research
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• v.17 no.2
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• pp.5-14
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• 2004

Introducing human capacities of control and sensation which have been overlooked into Human-Computer Interaction(HCI), Ubiquitous computing, Augmented Reality and others have been researched recently. New vision of HCI has embodied in Tangible User Interface(TUI). TUI allows users to grasp and manipulate bits with everyday physical object and architectural surface and also TUI enables user to be aware of background object at the periphery of human perception using ambient display media such of light, sound, airflow and water movement. Tangibles, physical object which constitutes TUI system, is the physical object embodied digital bit. Tangibles is not only input device but also the configuration of computing. To get feedback of computing result, user controls the system with Tangibles as action and the system represents reaction in response to User's action. User appreciates digital representation (sound, graphic information) and physical representation (form, size, location, direction etc.) for reaction. TUI's characters require the consideration about both user's action and system's reaction. Therefore we have to need the method to be concerned about physical object and interaction which can be combined with action, reaction and feedback.

• Proceedings of the Korea Information Processing Society Conference
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• 2017.04a
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• pp.326-329
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• 2017

We argue that the one potential solution is creating a drone or quadcopter that could be used to detect the network hacking attempts and even have the capability to disconnect illegal drones from their user's jamming signals, or de-authenticate them from networks. This could be used as a direct countermeasure, or would at least provide monitoring capacities, for these criminally-purposed drones. In this paper, we focus on implementing the device that can detect intrusion.

• Journal of Information Technology Applications and Management
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• v.14 no.2
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• pp.11-26
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• 2007

In this paper we suggest a context-driven configuration model of virtual businesses to form a business network model consisting of role-based, interaction-centered business partners. The model makes use of the subcontext concept which explicitly represents actors and interactions in virtual business (VB) context. We separate actors who have capacities on tasks in a specific kind of role and actor subcontext which models requirements in specific interaction subcontext. Three kinds of actors are defined in virtual service chains, service user, service provider, and external service supporter. Interaction subcontext models a service exchange process between two actor subcontexts with consideration of context dependencies like task and quality dependencies. Each subcontext may be modeled in the form of a situation network which consists of a finite set of situation nodes and transitions. A specific situation is given in a corresponding context network of actors and interactions. It is illustrated with a simple example.

• Journal of the Korea Safety Management & Science
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• v.8 no.5
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• pp.151-166
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• 2006

To solve the traffic problems of small cities like Chung Ju City, electronic communications equipment and the introduction of advanced technologies are being used or promoted. Other local areas with developed systems in place are being investigated for applicability. Systems like these will be introduced. This system will embody an organized, efficient transportation and safety system within this study At the moment, to solve the problem of reoccurring traffic in small towns in our country, we must develop an ITS service. We are now in the process of selecting and establishing the most adaptable ITS service to a small city For this purpose, we have studied existing records; taken a poll of the citizens of Chung Ju; examined present traffic conditions, examined road capacities; and reviewed available means of transportation. To accomplish the purpose of a thesis like this, we will research and analyze developed nations' and domestic cities' existing systems, construction and operation. We are in the process of building an ITS System which is the most adaptable to a small city like Chung Ju.

• Journal of Communications and Networks
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• v.14 no.2
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• pp.151-161
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• 2012

This paper considers a two-user Gaussian interference channel with energy harvesting transmitters. Different than conventional battery powered wireless nodes, energy harvesting transmitters have to adapt transmission to availability of energy at a particular instant. In this setting, the optimal power allocation problem to maximize the sum throughput with a given deadline is formulated. The convergence of the proposed iterative coordinate descent method for the problem is proved and the short-term throughput maximizing offline power allocation policy is found. Examples for interference regions with known sum capacities are given with directional water-filling interpretations. Next, stochastic data arrivals are addressed. Finally, online and/or distributed near-optimal policies are proposed. Performance of the proposed algorithms are demonstrated through simulations.

• Journal of Drive and Control
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• v.16 no.2
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• pp.1-7
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• 2019

Jaw crusher is a device that breaks rock collected from mines or quarries to produce aggregates of the size desired by user. A representative method for measuring load is to measure them by attaching force sensors directly to the part where the load is generated. However, the direct method has many limitations such as high-impact loads generation in equipment or space constraints, sensor capacities and costs. Therefore, Transfer Path Analysis (TPA) was used to indirectly measure impact loads by attaching acceleration sensors. In this study, both direct and TPA methods were used to measure the impact load of Jaw crusher. This study finally quantifies the impact of the load generated by the Jaw crusher using direct method and TPA method, and comparing the impact load measured calculated the derive the error rate.

• International Journal of Computer Science & Network Security
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• v.22 no.4
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• pp.394-400
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• 2022

The radio resources available in a wireless network system are limited. Therefor, job of managing resources is not easy task. Because the resources are shared among the UEs that are connected, the process of assigning resources must be carefully controlled. The packet scheduler in an LTE network is in charge of allocating resources to the user equipment (UE). Femtocells networks are being considered as a promising solution for poor channel performance for mulitple environments. The implementation of femtocells into a macrocell (traditional base station) would boost the capacities of the cellular network. To increase femtocells network capacity, a reliable Packet Scheduler mechanism should be implemented. The Packet Scheduler technique is introduced in this paper to maximize capacity of the network while maintaining fairness among UEs. The proposed solution operates in a manner consistent with this principle. An analysis of the proposed scheme's performance is conducted using a computer simulation. The results reveal that it outperforms the well-known PF scheduler in terms of cell throughput and average throughput of UEs.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.10
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• pp.654-663
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• 2014

Heterogeneous network (HetNet) with the various types of cells, e.g., with the different cell size and transmit power, has been introduced to improve the cell coverage and areal capacity in cellular mobile communication system. In this paper, we consider a practical situation in which all cells share the same wireless resource while some of them have a limited backhaul capacity. More specifically, we formularize a cell association problem that utilizes the minimum wireless resource while satisfying the quality of service (QoS) of all users in terms of their transmission time constraint, and propose a distributed algorithm to find the optimal solution. In the event of bottleneck at the backhaul link in some small cells, the proposed algorithm off-loads some users to the adjacent cell with the less congested backhaul capacity. Finally, we verify that the proposed algorithm supports the more numbers of users to satisfy the specified level of QoS than the conventional user association scheme under the limited access and backhaul capacities.

• Journal of the Ergonomics Society of Korea
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• v.28 no.4
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• pp.35-49
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• 2009

This study investigated perceived discomforts and those reasons of the young and middle-aged, the aged, the disabled and the pregnant in various daily activities, and elicited universal design factors based on human capacities (physical, sensory, cognitive and affective). A total of eighty people (twenty subjects for each user group) participated in one-to-one interviews about thirty six items of daily activities. A degree of discomfort of the daily activities was measured using Borg's CR10 scale. As a result, the disabled and the pregnant complained about almost all of the daily activities, and their degrees of discomforts were significantly higher than those of the youth and middle-aged and the aged. However, the youth and middle-aged and the aged only complained about some specific items. The major reasons of discomforts were related to physical and affective capabilities in general, where the detailed reasons of each user group were comparatively different. Finally, the universal design factors were elicited for each daily activity item based on the results of each user group. This study can be used to understand the discomforts and characteristics of the aged, the disabled and the pregnant in the various daily activities. The universal design factors elicited can also be applied to design related products and facilities universally.