• Journal of Digital Convergence
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• v.15 no.10
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• pp.307-314
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• 2017

In this study, a minimum amount of the vertical occlusion was secured differently in each type of mandibular advance devices snoring and Class I malocclusion patients wore these devices. This study analyzes, after the use of devices, a different amount of the vertical occlusion results in a change of the area of upper airway by additional changes such as mandibular position, muscle changes, tongue position. The higher the vertical amount, the area of the upper airway was shown smaller, And if the patient's tongues was prevented from the distal movement, the area of the upper airway had increased, To reduce snoring, doctors should accurately diagnose patients' occlusal relationships and select a MAD snoring that is appropriate for the occlusion. The dental technician who builds the selected device should also consider design settings such as the amount of vertical occlusion, the finish lines, and the thickness of the device to increase the effectiveness of the device.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.9
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• pp.1527-1537
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• 2006

The server system of digital contents has to how the context information about client devices to provide the appropriate contents for each device effectively. CC/PP standard specification is an agreement for describing and transmission of the information related with a client device. In this case, the information on device hardware and software, networks and user's preference is included here. In the mean time, WAP forum defined W-HTTP protocol to transmit the CC/PP profile information of a client device to a server system. However, the client devices which use existing HTTP protocol to transmit their information cannot provide the CC/PP profile information to a server. In this paper, we propose an effective method to create and provide the CC/PP profile in the clients which use not only HTTP protocol but also W-HTTP protocol to transmit device information.

• Journal of Digital Contents Society
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• v.14 no.3
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• pp.349-356
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• 2013

Products of Wi-Fi devices in recent years offer higher throughput and have longer signal coverage which also bring unnecessary signal interference to neighboring wireless networks, and result in decrease of network throughput. Signal interference is an inevitable problem because of the broadcast nature of wireless transmissions. However it could be optimized by reducing signal coverage of wireless devices. On the other hand, smaller signal coverage also means lower transmission power and lower data throughput. Therefore, in this paper, we analyze the relationship among signal strength, coverage and interference of Wi-Fi networks, and as a tradeoff between transmission power and data throughput, we propose a range-aware Wi-Fi network scheme which controls transmission power according to positions and RSSI(Received Signal Strength Indication) of Wi-Fi devices and analyze the efficiency of the proposed scheme by simulation.

• Journal of Digital Contents Society
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• v.10 no.1
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• pp.1-10
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• 2009

One important issue to generalize the ubiquitous paradigm is the development of user-centralized and intelligent ubiquitous computing systems. Sharing knowledge and correct communication between users and devices are needed to be aware of continuous changed context information and infer services for which users are suited. The goal of this paper is to describe and manage effectively the meaning of services or data which each device offers for interaction between users and devices based on semantic relationships and reasoning. In this paper, we represent semantic data using OWL and design a ubiquitous based intelligent system. We propose some index structures and strategies to process queries classified by each subsystem and adopt labeling schemes to identify classes and resources in the semantic data. We can find devices which satisfies various user's requests exactly and quickly using the proposed strategies.

• Journal of the Korea Society of Computer and Information
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• v.12 no.3
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• pp.59-65
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• 2007

In this paper, we proposed the DRM(Digital Rights Management) system that allows to redistribute contents safely based on home domain. This DRM system for contents redistribution within home domain can solve the restriction and the inconvenience occuring in using contents and at the same time protect the right of contents producer and provider as well. To play contents using home digital device, we must build home domain for contents redistribution among devices. That is to say, devices that are registered with home domain can redistribute contents to other devices at same domain. The domain must send redistribution-specifics to DRM server, so that user can pay reasonable amount for using the contents. Futhermore, by restricting within domain the right of contents redistribution, one can strictly prohibit the illegal redistribution.

• Journal of Digital Convergence
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• v.14 no.12
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• pp.193-199
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• 2016

MR(magnetorheological) devices for vehicle applications requires the consistent control performance and the reliable operation. However, the corrosion of iron particles consisting the MR fluid can significantly affect on MR properties. This paper presents an effect of the MR particle corrosion on the performance of MR fluids such as shear stress magnitude which is directly concerned with control performance. As a first step, MR particles are corroded by water-calcium chloride solution. The resulting MR particles are examined by scanning electron microscope (SEM) and their molar ratios are analyzed by the energy dispersive X-ray analysis (EDAX). By dispersing the corroded MR particles into silicone oil, the corroded MR fluid is synthesized for evaluation of MR effect change. A rotational viscometer is adopted to measure shear stress magnitude. Finally, it is demonstrated how much the corrosion affect on performances by comparing the normal MR fluid to the corroded MR fluid, from which performance investigation of the MR devices containing the corroded MR particles will be studied in the second phase of this study.

• Journal of Digital Contents Society
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• v.14 no.1
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• pp.7-14
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• 2013

As mobiles devices with high-spec camera built in are used widely, the visual quality enhancement of the high-resolution images turns out to be one of the key capabilities of the mobile devices. Due to the limited computational resources of the mobile devices and the size of the high-resolution images, we should choose an image processing algorithm not too complex and use an efficient implementation technology. One of the simple and widely used image quality enhancement algorithms is contrast stretching. Java libraries running on a virtual machine, JNI (Java Native Interface) based native C/C++, and NEONTM SIMD (Single Instruction Multiple Data) are common implementation technologies in the case of Android smartphones. Using these three implementation technologies, we have implemented two image contrast stretching algorithms - linear and equalized, and compared the computation times. The native C/C++ and the NEONTM SIMD outperformed the native C/C++ implementation by 56-78 and 50-76 time faster respectively.

• Journal of Digital Convergence
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• v.17 no.12
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• pp.219-228
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• 2019

Thanks to the development of information technology and the vitalization of smart services, the Internet of Things (IoT) technology, in which various smart devices are connected to the network, has been continuously developed. In the legacy IoT architecture, data processing has been centralized based on cloud computing, but there are concerns about a single point of failure, end-to-end transmission delay, and security. To solve these problems, it is necessary to apply decentralized blockchain technology to the IoT. However, it is hard for the IoT devices with limited computing power to mine blocks, which consumes a great amount of computing resources. To overcome this difficulty, this paper proposes an IoT architecture based on the edge computing technology that can apply blockchain technology to IoT devices, which lack computing resources. This paper also presents an operaional procedure of blockchain in the edge computing-based IoT architecture.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.30 no.3
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• pp.417-428
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• 2020

With the rapid development of information and communication technology, mobile devices have become an essential tool in our lives. Mobile devices are used as important evidence in criminal proof, as they accumulate data simultaneously with PIM functions while working with users most of the time. The mobile forensics is a procedure for obtaining digital evidence from mobile devices and should be collected and analyzed in accordance with due process, just like other evidence, and the integrity of the evidence is essential because it has aspects that are easy to manipulate and delete. Also, the adoption of evidence relies on the judges' liberalism, which necessitates the presentation of generalized procedures. In this paper, a mobile forensics model is presented to ensure integrity through the generalization of procedures. It is expected that the proposed mobile forensics model will contribute to the formation of judges by ensuring the reliability and authenticity of evidence.

• Journal of Sensor Science and Technology
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• v.15 no.4
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• pp.223-230
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• 2006

An FIR filter for digital voice signal processing has been designed and implemented using a microcontroller in implantable middle ear hearing devices (IMEHDs). The designed digital voice signal processing filter which has fast and accurate filtering operation and controllable filter characteristics has been implemented using a hardware multiplier and a direct memory access (DMA) in the low power microcontroller, MSP430F169. It has been confirmed that each of the implemented 6-orders Remez FIR filters with 1 channel and 2 channels can be applied to the voice signal processing module of IMEHDs based on the evaluation results of the filtering performance experiment.