• Journal of information and communication convergence engineering
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• v.8 no.4
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• pp.377-382
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• 2010

With the advent of flash memory based new storage device (SSD), there is considerable interest within the computer industry in using flash memory based storage devices for many different types of application. The dynamic index structure of large text collections has been a primary issue in the Information Retrieval Applications among them. Previous studies have proven the three approaches to be effective: In- Place, merge-based index structure and a combination of both. The above-mentioned strategies have been researched with the traditional storage device (HDD) which has a constraint on how keep the contiguity of dynamic data. However, in case of the new storage device, we don' have any constraint contiguity problems due to its low access latency time. But, although the new storage device has superiority such as low access latency and improved I/O throughput speeds, it is still not well suited for traditional dynamic index structures because of the poor random write throughput in practical systems. Therefore, using the experimental performance evaluation of various index maintenance schemes on the new storage device, we propose an efficient index structure for new storage device that improves significantly the index maintenance speed without degradation of query performance.

• Journal of Internet Computing and Services
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• v.20 no.3
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• pp.69-75
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• 2019

The safety and performance of medical device software is managed through life-cycle processes, which represent the entire process of research and development (R&D). The life-cycle process of medical device software is represented by an international standard called IEC 62304, ISO/IEC 12207. In order to license the product, the manufacturer must have document artifacts that comply with the IEC 62304 standard. However, these standards only describe the content of the activity and do not provide a method or procedure for documentation. Therefore, this paper suggests R&D documentation guidelines that assist medical device software developers to have R&D documents conforming to the standards. For this purpose, this study identifies the requirements related to documentation among the requirements existing in the standard and extracts them in the form of guidelines showing only the core information of the requirements. In addition, through the Web framework implemented based on this research, the developer can evaluate whether the technical documents are written in accordance with the R&D document guidelines. Medical device software manufacturers can efficiently produce high-quality research and development documents through R&D documentation guidelines, and they can have standards-compliantresearch and development documentation required for licensing procedures.

• Journal of KIISE:Information Networking
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• v.32 no.3
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• pp.291-300
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• 2005

The Ubiquitous computer environment is thing which invisible computer that is not shown linked mutually through network so that user may use computer always is been pervasive. Intend computing environment that can use easily as user wants and it is the smart environment that user provides context awareness that is wanting computing environment. This Ubiquitous computing contains much specially weak side in security. Masquerade attack of that crawl that is quoted to user or server among device that is around user by that discrete various computing devices exist everywhere among them become possible. Hereupon, in this paper, proposed method that have following characteristic. Present authentication model through transfer or device. Suggest two method that realize authentication through device in case of moved to method(MD: Multi Domain) and user ownself space(SD: Single Domain) that realize authentication through device in case of moved user's direct path who device differs.

• Proceedings of the KIEE Conference
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• 2007.11a
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• pp.154-155
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• 2007

This paper describes frequency response of two-mass system for gyroscope applications. The two-mass system of the proposed device is adapted to the sensing part of the gyroscope in this research. Two-mass system has two resonant peaks and wide flat region between two resonant peaks. The resonant frequency of driving part is in this flat region. Therefore, frequency tuning is not necessary for mode matching. In the proposed device, resonant frequency is designed as 7183 Hz in driving part. Mass ratio of two masses in sensing part is 0.1 and device size is 6 mm $\times$ 6 mm. The device is fabricated by SiOG process. The fabricated spring width is increased from $4{\mu}m$ to $4.5{\sim}4.7{\mu}m$, and the measured resonant frequency is 8392 Hz in driving mode. We operated the sensing part using parallel plate of proof mass to verify the sensing part. It is confirmed the device has a wide fiat region in frequency response curve and the resonant frequency of the driving part is in the wide flat region of sensing mode.

• Journal of the Korea Society of Computer and Information
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• v.19 no.11
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• pp.127-135
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• 2014

Interactive-typed devices and contents that have been often applied in the field of entertainment and game are the technology that allows you to maximize the enjoyment and participation of users through the interaction of each. In this paper, we designed an interactive-typed smartphone app that is based on the Android platform, implemented the wearable Bluetooth device to control via a interactive interface with a vibration sensor and three-axis acceleration sensor. We tested the functionality and 3-axis motion's operability by using smartphone app, interface interactive-typed device that has been developed, prove useful as a wearable Bluetooth device that has the convenience of the user. Further, it is shown that by implementing the optimized protocol of the sensor data transfer over Bluetooth, it is possible to reduce the malfunction of the content of the smart phone.

• Journal of the Korea Society of Computer and Information
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• v.27 no.2
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• pp.61-69
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• 2022

As the delivery industry grew around the restaurant industry along with the COVID-19 situation, the number of delivery workers increased significantly. Along with that, new forms of delivery using personal mobility (PM) also emerged and two-wheeled or PM-related accidents are steadily increasing. This study manufactures a PM's driving analysis device to establish a safe delivery monitoring environment. This system was constructed to process data collected from the driving analysis device and through a cloud server, which would recognize and record special situations (acceleration/deceleration, speed bump) that could occur during the PM's driving situation. As a result, the angular speed, acceleration, and geomagnetic values collected from the IMU in the device were able to determine whether to drive, drive on the sidewalk, and drive on the speed bump. This technology was able to achieve approximately 1600 times more driving information storage efficiency than conventional image-based recording devices.

• JSTS:Journal of Semiconductor Technology and Science
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• v.8 no.2
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• pp.156-163
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• 2008

We proposed a new $p^+/n^+$ gate locally-separated-channel (LSC) bulk FinFET which has vertically formed oxide region in the center of fin body, and device characteristics were optimized and compared with that of normal channel (NC) FinFET. Key device characteristics were investigated by changing length of $n^+$ poly-Si gate ($L_s$), the material filling the trench, and the width and length of the trench at a given gate length ($L_g$). Using 3-dimensional simulations, we confirmed that short-channel effects were properly suppressed although the fin width was the same as that of NC device. The LSC device having the trench non-overlapped with the source/drain diffusion region showed excellent $I_{off}$ suitable for sub-50 nm DRAM cell transistors. Design of the LSC devices were performed to get reasonable $L_s/L_g$ and channel fin width ($W_{cfin}$) at given $L_gs$ of 30 nm, 40 nm, and 50 nm.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.4
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• pp.1837-1860
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• 2020

We propose a general framework for studying resource allocation problem and the tradeoff between spectral efficiency (SE) and energy efficiency (EE) for downlink traffic in power domain-non-orthogonal multiple access (PD-NOMA) and device to device (D2D) based heterogeneous cloud radio access networks (H-CRANs) under imperfect channel state information (CSI). The aim is jointly optimize radio remote head (RRH) selection, spectrum allocation and power control, which is formulated as a multi-objective optimization (MOO) problem that can be solved with weighted Tchebycheff method. We propose a low-complexity algorithm to solve user association, spectrum allocation and power coordination separately. We first compute the CSI for RRHs. Then we study allocating the cell users (CUs) and D2D groups to different subchannels by constructing a bipartite graph and Hungrarian algorithm. To solve the power control and EE-SE tradeoff problems, we decompose the target function into two subproblems. Then, we utilize successive convex program approach to lower the computational complexity. Moreover, we use Lagrangian method and KKT conditions to find the global optimum with low complexity, and get a fast convergence by subgradient method. Numerical simulation results demonstrate that by using PD-NOMA technique and H-CRAN with D2D communications, the system gets good EE-SE tradeoff performance.

• Proceedings of the KAIS Fall Conference
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• 2010.11a
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• pp.267-271
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• 2010

Zigbee는 단말에 대한 경제성이 뛰어나고 저 전력통신을 이용하기 때문에 수명이 길다. Mesh, Tree, Star 등 다양한 방식의 토플리지 구조를 지원 하며 확장성이 뛰어나 군사적인 용도, 환경 모니터링 시스템 등 많은 분야에 사용되고 있다. 최근 스마트그리드환경을 구축함에 있어 Zigbee는 HAN(Home Area Network)에 표준으로 사용될 예정이며 현재는 Zigbee를 이용한 AMR(Automatic Meter Reading)을 시범 중에 있다. 일반적으로 ZIgbee Network은 ZC(Zigbee Coordinator), ZCH(Zigbee Cluster Head), ZE(Zigbee End Device) 3가지로 구성되며, Zigbee Network에서 발생할 수 있는 취약점은 허가되지 않은 디바이스의 접근, 라우터의 흐름을 조작하는 방법, ZC(Zigbee Coordinator)와 ZE(Zigbee End Device)사이의 키 전송 시 안전하지 않은 채널을 이용하여 전송되는 문제가 발생된다. 본 논문에서는, TCP(Third Party Center)를 이용함으로써, ZE와 ZC간의 키 생성 시 발생하는 취약점을 보완하였다. 또한 인증절차를 강화함으로써 ZE(Zigbee End Device)에서 발생 할 수 있는 취약점을 보완하고자 하였으며 RS(Register Server)를 이용하여 HAN에 존재하는 디바이스에 대하여 실시간 모니터링이 가능하게 하였다.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1533_1534
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• 2009

This paper presents an atmospheric micro glow plasma-jet device. The device consists of four components; a thin Ni anode, a porous alumina insulater, a stainless steel cathode and an aluminum case. The Ni anode is fabricated using micromachining technology. The anode has 10 holes, of which the hole diameter and the depth are $250{\mu}m$ and $60{\mu}m$, respectively. The discharge test is performed in nitrogen gas at atmospheric pressure for 20 kHz AC bias. The breakdown voltage is 3.5 kV at gas flow rate of 4 L/min and the the plasma-jet is blown out to ambient at 5.5 kV. In order to verify the characteristics of plasma, the current and the voltage of device are measured. The maximum temperature of plasma is $37^{\circ}C$. The plasma is well generated and stable at high voltage.