• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.11
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• pp.27-35
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• 1994

In this paper, a modified version of PRML is discussed to reduce nonlinearity in digital high-density storage devices. We propose a PRML with a nonlinear compensator which can reduce nonlinear interaction between the stored flux regions on the storage channel, and apply it to recording channels with three different densities. By comparing its performance with the existing PRML through computer simulation, we confirm that the nonlinear intersymbol interference increasing with high-density recording channels can be reduced effectively by the PRML with a nonlinear compensator.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.10 s.241
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• pp.1119-1129
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• 2005

A new measurement system of wall pressure fluctuations on a rotating machinery, composed of digital recording device, was developed and evaluated. The small-sized digital recording device was attached on the rotating machinery and then was detached for data reduction. In order to obtain the system transfer function of the digital recording system, a dynamic calibration was performed utilizing the signal from a 1/8 inch B&K microphone as input. The time history of the unsteady pressure was then reconstructed from the output of the sensor by using this transfer function. The reconstructed pressure signals showed good agreement with the reference signal in both temporal and spectral sense. This sensor was then used to measure the wall pressure fluctuations on a rotating blade. An array of microphones were installed on the blade in the circumferential and radial directions. Various statistical moments were obtained from the measurement data set. Comparison of these quantities with the existing studies demonstrated satisfactory agreement. These tests give credence to the relevance and reliability of this device for applications in more complicated turbulent rotating machineries.

• Proceedings of the KIPE Conference
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• 2009.11a
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• pp.78-80
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• 2009

최근 화석에너지원의 고갈과 고유가 및 지구 온난화 방지를 위해 국가별로 이산화탄소 배출량을 규제하기 시작하면서 신재생 에너지의 사용에 대한 관심이 높아지고 있다. 그 중 연료전지가 한 부분을 차지하고 있으며, 연료전지는 친환경적이고 효율적인 에너지원으로서 근 미래의 새로운 대체 에너지로서 각광 받으며 여러 분야의 전기장치로 사용될 수 있다. 연료전지는 낮은 출력전압과 높은 출력전류를 갖는 특징이 있으며, 부하에 따라 출력전압이 변화하는 특성이 있기 때문에 연료전지의 사용을 위해서는 다양한 부하조건에서 연료전지와 연동된 승압 또는 강압형 컨버터의 제작이 반드시 필요하다. 본 논문에서는 DSP를 이용하여 컨버터의 디지털 제어가 가능하며, 고정 시비율로 동작하는 LLC 공진형 컨버터를 이용한 2kW급 연료전지용 양방향 컨버터를 제안하였다. 제안한 컨버터는 양방향으로 동작하며, 에너지 저장 및 재사용을 목적으로 하고, 출력은 24V 배터리가 된다.

• Journal of Korea Game Society
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• v.13 no.5
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• pp.73-80
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• 2013

NUI(Natural User Interface) allows users to directly interact with surrounding digital devices using their voices or body motions without additional input/output interface devices. Our study has been carried out on human users who play a tangible game with body motions in the NUI-applied smart space. ECG was measured for 60 seconds duration before and after playing the game to determine user stress levels, and the measured signals were analyzed through an improved Random Forest algorithm. In order to experiment by a supervised learning, users additionally input whether or not the user felt stress. Moreover, the improved algorithm showed 1.04% higher accuracy than existing algorithm.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.05a
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• pp.230-232
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• 2011

Owing to the advent of digital devices which equipped with GPS, such as smartphone and tablet pc, a number of LBSNS applications have been released and even SNS applications serve various Location-Based Services. In twitter's case, the news of interesting area is provided to user not by being subscribed them automatically, but by being searched on web-site. This paper describes the system designed for users want to subscribe the local news without procedure like searching using operators. This system uses PBSM(Partition Based Spatial-Merge Join) which has no index for batch processing and against a massive query. The results from Spatial Join are stored in Materialized View then provided to user.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.4
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• pp.143-148
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• 2017

Flash Memory which is light and strong external shock as storage of small electronics like smartphone, digital camera, car black box has been widely used. Since the operation speed of the read operation and the write operation are different from each other, and the flash memory has the feature that it is not possible to overwrite, the delete operation is added to solve these problems. Wear-leveling must also be considered, since the number of erase times of the flash memory is limited. Many studies have been conducted on the substitutional algorithms of flash memory based on these characteristics of recent flash memories. So, to solve the problem that has existing buffer replacement algorithm this thesis divide page into 6 groups and when proposed algorithm select victim page, it consider reference page frequency and page recency.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.877-879
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• 2013

Imaging device such as digital TV is being popular in a modern society based on communication technology. However, because of internal and external cause of system in the process of transmission, storage and acquisition, image is degraded by noise. Therefore, the importance of denoising technology is being increased, and a research for that is being actively made. In this paper, a weighted filter algorithm that considers different pixels of masks and estimated noise variance was proposed. in order to remove AWGN. And, PSNR(peak signal to noise ratio) was used to represent the excellence of proposed algorithm.

• Annual Conference of KIPS
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• 2005.11a
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• pp.217-220
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• 2005

VoD 시스템의 병목현상의 주요원인은 저장장치 또는 네트워크 입출력으로 인한 대역폭 요구량과 디지털 비디오의 장시간 서비스로 인한 높은 대역폭 요구량 때문이다. 패칭은 멀티캐스트 사용하여 VoD 시스템의 병목 현상을 극복한 가장 효과적인 기술 중 하나이다. 본 논문에서는 클라이언트를 이용한 프리픽스 패칭 사용과 함께 서버로부터 정규 멀티캐스트 스트림을 사용하여 기존의 패칭 기법을 개선하기 위한 P2Prefix 패칭 기법을 제안한다. 제안된 기법에서 각 클라이언트는 동일한 비디오 스트림을 요청하는 다른 클라이언트에게 프리픽스 스트림을 제공하기 위한 패칭 서버로서의 역할을 한다. 그 결과, 서버 대역폭 요구량은 서버로부터 패칭 채널을 제거하는 것으로 줄일 수 있다. 성능 평가에서 본 논문에서 제안한 패칭 기법이 기존의 패칭 기법과 비교해 볼 때 서버 대역폭 요구를 줄일 수 있음을 보인다.

• 전자공학회논문지 IE
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• v.47 no.3
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• pp.1-6
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• 2010

In this paper, it is designed a processor using embedded system so that moving picture can be expressed on LED electric sign board which has been expressed a simple message only like as a character or graphic. It has been fabricated a moving picture LED electric sign board which is composed to a video processor and LED display panel, in order to be able to express a digital moving picture of 24 bits that is transmitted from embedded system. It includes gamma adjustment, brightness, color contrast control, a schedule function, expression image conversion by the Internet and memory device. Also, an application program based Windows CE is designed so that a character, graphic, and moving picture can be expressed on a small LED electric sign board.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.927-929
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• 2015

With rapid progress in digital technology, demand for multi-media imaging devices is increasing. But noise occurs due to various reasons during the process of acquiring, transmitting or processing the image data. Filters used to remove salt and pepper noise include CWMF and AWMF. In areas where the noise density is high, the removal of noise is undermined. This paper suggests an algorithm that preserves the edge while removing noise using spatial weighted.