• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.2
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• pp.253-270
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• 2013

To achieve accurate localization information, complex algorithms that have high computational complexity are usually implemented. In addition, many of these algorithms have been developed to overcome several limitations, e.g., obstruction interference in multi-path and non-line-of-sight (NLOS) environments. However, localization systems those have complex design experience latency when operating multiple mobile nodes occupying various channels and try to compensate for inaccurate distance values. To operate multiple mobile nodes concurrently, we propose a localization system with both low complexity and high accuracy and that is based on a chirp spread spectrum (CSS) radio. The proposed localization system is composed of accurate ranging values that are analyzed by simple linear regression that utilizes a Big-$O(n^2)$ of only a few data points and an algorithm with a self-calibration feature. The performance of the proposed localization system is verified by means of actual experiments. The results show a mean error of about 1 m and multiple mobile node operation in a $100{\times}35m^2$ environment under NLOS condition.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.3
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• pp.327-332
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• 2017

As Internet of Things (IoT) technology advances, there is a growing demand for location-based services (LBSs) to identify users' mobility and identity. The initial LBS system was mainly used to measure position information by measuring the phase of a signal transmitted from a global positioning system (GPS) satellite or by measuring distance to a satellite by tracking the code of a carrier signal. However, the use of GPS satellites is ineffective, because it is difficult to receive satellite signals indoors. Therefore, research on wireless communications systems like ultra-wide band (UWB), radio frequency identification (RFID), and ZigBee are being actively pursued for location recognition technology that can be utilized in an indoor environment. In this paper, we propose an LBS system that includes the 2.45GHz band for chirp spread spectrum (CSS), and the 3.1-10.6GHz band and the 250-750MHz bands for UWB using the IEEE 802.15.4a standard for low power-based location recognition. As a result, we confirmed that the 2.45GHz Industrial, Scientific and Medical (ISM) band RF transceiver and the ranging function can be realized in the hardware and has 0dBm output power.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.28 no.2
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• pp.109-116
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• 2005

In the previous C/S publishing system, the editor or contributor can arbitrarily modify the document created by the author, in which case it is difficult to identify the changes made in the document. Another shortcoming is in that when the document is in need of tracking or editing, the client must have the respective editing system. To solve this problem, the gist of the document must be preserved along with the document itself, and the process of handling the document must be standardized. Publishing on the web ensures a more stable and accurate result in processing documents. The significance of web publishing is made clear, when we consider the importance of information per se and the growing demand for immediate publication in the present day. The need for a simple and straightforward apache-based PDF publishing system, in which HTML and CSS are supported, and a converting engine provides PDF standard security application support, is prominent. This provides a library in which one can directly create a PDF via Windows, Linux, or Unix without having to rely on a client, allowing high-speed PDF creation. The development of a web-accessed PDF converting engine forms the basis for e-transactions, online brochures, electronic B/L, and many other industrial sectors.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.930-935
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• 2001

The experimental characterization of hydrodynamic bearing spindle motor is performed for the practical implementation of high-performance hard disk drive system. Firstly, the design concept of hydrodynamic bearing for the disk drive system is addressed including the herringbone grooved journal bearing, the spiral grooved thrust bearing, capillary seal design, and the viscous pumping of fluid. Secondly, the experimental evaluation is performed for the disk drive system in which the hydrodynamic bearing spindle motor is implemented and its dynamic performances are compared with conventional ball-bearing spindle motor. The key parameters include NRRO(Non Repeatable Run-Out), disk dynamics, acoustics, and resultant PES (Position Error Signal). Finally, the external gyro-exciting test results including 200k CSS(Continuous Start-Stop) on three angular attitudes(0,90, 180 degree) are presented in order to verify the practical reliability of disk drive system subject to the gyro-motion of hydrodynamic bearing spindle motor.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1999.11a
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• pp.303-309
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• 1999

Optimum tribological performance of the head/disk system is critical in maintaining reliable data processing in a hard disk drive. Particularly, as the flying height of the slider continues to decrease with increasing recording density, frictional interaction between the slider and the disk need to be better understood. In this work the effect of reduced ambient pressure on the tribological behavior of the head/disk interface is presented. It is found that surface damage of the components can be accelerated by reducing the ambient pressure. This method may be utilized to assess slider/disk compatibility of newly developed systems in short time.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.551-552
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• 2007

Coating films were prepared from silane-terminated Colloidal silaca(CS) and UV-curable acrylate resin. The silane-terminated CSs were synthesized from CS and methyltrimethoxysilane(MTMS) and then treated with 3-methacryloxypropyltrimethoxysilane(MAPTMS)/3-glycidoxypropyltrimethoxysilane( GPTMS)/vinyltrimethoxysilane(VTMS) by sol-gel process, respectively. The silane-terminated CS and acrylate resin were hybridized using UV-curing system. Thin films of hybrid material were prepared using spin coater on the glass. Their hardness, contact angle and transmittance improved with the addition of silane-terminated CS.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• fall
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• pp.322-324
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• 2021

최근 고주사율 디스플레이 시장 확대와 실감콘텐츠에 대한 요구에 따라, 높은 프레임율의 동영상 콘텐츠에 대한 관심이 증가하고 있다. 본 논문은 이용자의 비디오를 초슬로우 비디오로 변환해주는 웹 기반 서비스 시스템을 제안한다. 이는 사용자가 웹을 통해 비디오를 업로드하면, 딥러닝 기반의 비디오 프레임 보간 알고리즘을 이용하여 초고프레임율의 동영상으로 변환하며. 변환된 초저속 비디오를 웹을 통해 보여주거나 파일 포맷으로 제공한다. 제안 시스템은 복잡한 연산을 요구하는 딥러닝 네트워크 모듈과 사용자와의 상호작용을 위한 웹 페이지 모듈로 구성되었다. 프레임 보간을 위해서, State-of-the-art 기술인 딥러닝 기반의 Real-Time Intermediate Flow Estimation for Video Frame Interpolation 방법이 활용되었으며, 웹페이지는 HTML, CSS, Javascript, Flask를 사용하여 구축되었고, Flask를 활용하여 두 모듈이 연동되었다. 제안 웹 기반 시스템을 통해, 사용자는 딥러닝 네트워크 구동에 필요한 별도의 지식 없이 통신 자원만으로 고실감의 경험과 편의성을 제공받을 수 있다.

• Journal of Advanced Research in Ocean Engineering
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• v.2 no.3
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• pp.112-128
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• 2016

Capsize and sinking of a coastal car ferry has occurred in a Korean offshore area and has caused hundreds of human casualties. The rapid turn and improper cargo loading are inferred as the main reasons of the accident. It has motivated to develop a new system of cargo securing with improved safety of Korean coastal ferries. This paper provides a new approach regarding cargo securing safety assessment which is purely based on force equilibrium conditions, because IMO CSS is suitable for the ocean-going vessels. The mathematical formulations are presented for the new approach. This paper also introduces a newly developed safety assessment system based on the new approach. Most outstanding features are that it can utilize acceleration data produced from hydrodynamic motion analyses or assumed maximum extents of ship motion components and that securing safety assessment is simultaneously possible for unlimited number of cargoes with finite number of lashings.

• Earthquakes and Structures
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• v.7 no.6
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• pp.1119-1139
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• 2014

A damage-based seismic design procedure for steel frame structures is formulated as an optimization problem, in which minimization of the initial construction cost is treated as the objective of the problem. The performance constraint of the design procedure is to achieve "repairable" damage state for earthquake demands that are less severe than the design ground motions. The Park-Ang damage index is selected as the seismic damage measure for the quantification of structural damage. The charged system search (CSS) algorithm is employed as the optimization algorithm to search the optimum solutions. To improve the time efficiency of the solution algorithm, two simplifying strategies are adopted: first, SDOF idealization of multi-story building structures capable of estimating the actual seismic response in a very short time; second, fitness approximation decreasing the number of fitness function evaluations. The results from a numerical application of the proposed framework for designing a twelve-story 3D steel frame structure demonstrate its efficiency in solving the present optimization problem.

• Proceedings of the Korea Information Processing Society Conference
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• 2001.04b
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• pp.1225-1228
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• 2001

ASP는 동적인 대화형 웹 서버 응용 프로그램을 작성하고 실행하기 위해 사용할 수 있는 '서버 측 스크립트' 환경이다. ASP를 사용하면 HTML 페이지와 스크립트 명령 및 ActiveX 구성요소를 조합하여 대화형 웹 페이지나 강력한 웹 기반의 응용 프로그램을 만들 수 있다. 사용자가 HTML에 익숙한 사람이라면 ASP 스크립트가 동적인 페이지의 작성을 위한 좋은 방법임을 알 수 있을 것이다. 또한 HTML 파일 작성에 필요한 자바 스크립트나 비쥬얼 베이직 스크립트는 물론이고 그 외 HTML 파일의 내용을 요구에 맞게 배치하기 위해 사용하는 CSS1의 기본적인 내용 정도는 알고 있어야 한다고 본다. 뿐만 아니라 CGI 프로그래밍과 웹 서버와 클라이언트의 상호 작용 관계, 그리고 웹 서버 관리하는 방법 등의 내용을 완벽하게 갖추고 있다고는 생각하지는 않는다. 하지만 앞으로 진행해 나가면서 직접 설명을 하지는 않겠지만 이와 같은 기술들이 모두 사용이 될 것이고, ASP는 다른 웹 애플리케이션 언어보다 쉽고, 웹에서의 많은 응용과, 무한한 가능성을 내포하고 있다는 것을 말하고 싶다. 그러므로 ASP에 접근하는 방법에 있어서 운영하는 방법을 연구하였다.