• Proceedings of the Korea Information Processing Society Conference
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• 2007.11a
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• pp.579-582
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• 2007

최근 들어 더욱 UCC(User Created Contents)등과 같은 대용량 멀티미디어(multimedia) 서비스에 대한 요구가 나날이 증가되면서 부하분산에 중점을 둔 웹 클러스터링 시스템(Web Clustering System) 에서 기존의 작은 크기의 스트림 데이터(Stream Data)나 조금 더 다양한 데이터를 위한 읽기 성능을 대용량 데이터에 초점을 맞춘 방안으로 최적화 시키는 것이 중요시되고 있다. 본 논문에서는 대용량 멀티미디어를 중심으로 실제 서비스시 간과 되어질 수 있는 운영체제(Operating System, O/S)에서의 I/O 인식, 디스크 제어 프로그램에서의 I/O, 웹 클러스터의 부하분산정책의 파라미터(Parameter)를 개선함으로써 읽기성능 향상 방안을 제시한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.4
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• pp.659-666
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• 2006

Servo-motors are used as key components of automated system by performing precise motion control as accurate positioning and accurate speed regulation in response to the commands from computers and sensors. Especially, the linear brushless servo-motors have numerous advantages over the rotary servo motors which have connection with the friction induced transfer mechanism such as ball screws, timing belts, rack/pinion. This paper proposes an estimation method of unknown motor system parameters using the informations from the sinusoidal driving type linear brushless DC motor dynamics and outputs. The estimated parameters can be used to tune the controller gain and a disturbance observer. In order to meet this purpose high performance Digital Signal Processor, TMS320F240, designed originally for implementation of a Field Oriented Control(FOC) technology is adopted as a controller of the liner BLDC servo motor. Having A/D converters, PWM generators, rich I/O port internally, this servo motor application specific DSP play an important role in servo motor controller. This linear BLDC servo motor system also contains IPM(Intelligent Power Module) driver and hail sensor type current sensor module, photocoupler module for isolation of gate signals and fault signals.

• Journal of the Korea Concrete Institute
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• v.13 no.2
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• pp.107-113
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• 2001

This study was conducted preliminarily to develop the crack source location technique for plain concrete beam using acoustic emission(AE). Before the main experiment, the test of virtual An source location was achieved in plain concrete block. The sensor layout was mutually compared between triangular layout and rectangular layout. As the results of test, AE source location by triangular layout was evaluated more effective than that by rectangular layout. The specimen to apply he source location technique was man in total nine specimens (each three in 40 %, 50%, 60% of W/C ratio) which the experiment variable was the compressive strength level(W/C ratio). The bending loading method is selected by cyclic loadings to evaluate the degree of concrete damage. It is seen that Kaiser effect and Felicity effect exists through analysis of AE parameters in coming failure experiment. As a result of analyzing the felicity ratio(FR) values, it is shown that this values can be used for evaluating the degree of concerto damage. AE activity is started highly at the 70% of failure load without the compressive strength level. Thus considered by a index in constructing the system of the failure warning at application of the field structure. And the results compared the real cracking location with the source location has perceived by AE monitoring before it is appeared the primary crack by visual observation.

• Journal of Sensor Science and Technology
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• v.8 no.1
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• pp.69-79
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• 1999

The research and implementation was preformed on high-resolution CCTV camera with CCD exclusive DSP conventional analog signal processor CCTV camera has its limit on auto exposure(AE), auto white balance(AWB), back light compensation(BLC) processing, severe distortion and noise of image, manual control parameter setting, etc. In our study, to resolve the problems in conventional CCTV camera, we made it possible to control AE, AWB, BLC automatically by the use of the DSP, which are used exclusively in the CCD camera produced domestically, and the microcontroller. And we utilized the function of screen display of microcontroller for the user-friendly interface to control CCD camera. And the electronic variable resister(EVR) was used to avoid setting parameters manually in the level of manufacturing process. As the result, It became possible to control parameters of the camera by program. And the cost-down effect was accomplished by improving the reliability of parameter values and reducing the efforts in setting parameters.

• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.1
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• pp.39-55
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• 2022

This study carried out the laboratory tests for AE signal attenuation to determine the attenuation coefficient (α) of silo concrete in Gyeongju low and intermediate-level disposal environments. The concrete samples were prepared by satisfying the concrete mixing ratio used in the Gyeongju disposal silo, and these samples were additionally exposed depending on the temperature conditions and saturation and, dry condition. As a result of attenuation tests according to the transmission distance on three concrete specimens for each disposal condition, the AE amplitude and absolute energy measured on the saturated concrete were higher than that of the dry concrete in the initial range of the signal transmission distance, but the α of the saturated concrete was higher than that of the dry concrete. Regardless of the saturation and dry conditions, the α tended to decrease as the temperature increases. The α had a more major influence on the saturation and dry condition than the temperature condition, which means that the saturation and dry condition is the main consideration in measuring the signal attenuation of a concrete disposal structure. The α of concrete in the disposal environment expect to be used to predict the integrity of silos concrete in Gyeongju low and intermediate-level disposal environments by estimating the actual AE parameter values at the location of cracks and to determine the optimum location of sensors.

• Journal of the Korean Chemical Society
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• v.39 no.7
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• pp.538-542
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• 1995

The stability constant and the thermodynamic parameters of the hydrazide Schiff base ligands such as N,N'-oxalylbis(salicylaldehydehydrazone)(OBSH), N,N'-malonylbis(salicylaldehydehydrazone)(MBSH), and N,N'-succinylbis(salicylaldehydehydrazone)(SBSH) with dioxouranium(Ⅵ) ion have been determined by potentiometry in 95% DMF solution at various temperatures. The order of stability constants increased SBSH

• Journal of Power System Engineering
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• v.6 no.2
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• pp.40-47
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• 2002

In this paper, friction welding optimization for 1Cr0.5Mo-STS304 (${\phi}14\;mm$), AE applications for the weld quality evaluation and the applications of various life prediction methods such as LMP (Larson-Miller Parameter) and ISM (initial strain method) were investigated : The creep behaviors of those steels and the friction welded joints under static load were examined by ISM combined with LMP at 400, 500, 550 and $600^{\circ}C$, and the relationship between these two kinds of phenomena was studied. The real-time predicting equations of elevated-temperature creep life (rupture time) under any creep stress at any elevated-temperature could be developed by LMP and LMP-ISM. It was confirmed that the life prediction equations by LMP and LMP-ISM are effective only up to 102 h and can not be used for long times of 103-106 h, but by ISM it can be used for long times creep prediction of more than 104 h with most reliability.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.303-303
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• 2011

최근 세포 포집 소자 제작에 있어 세포의 종류와 크기의 다양성을 고려하여 정확하게 포집하기 위한 고정밀화, 소형화 된 도구 제작 기술 개발이 중요한 현안으로 떠오르고 있다. 본 연구에서는 선행 기술에서의 세포 포집 한계를 극복하기 위한 방안으로 펨토초 레이저 가공을 통한 미세 세포 포집 장치 제작에 관한 실험을 진행하였다. 펨토초 레이저의 짧은 파장의 대역 범위와 전력 특성이 미세 소자 제작을 가능하게 함에 따라 수백, 수천 개의 세포 포집에 있어 보다 안정적이고 신뢰도 높은 포집 장치 구현을 실현시킬 수 있다. 실험에서는 펨토초 레이저의 가공 조건을 가변하며 MEMS 소자에 홀(hole)을 형성시켰다. flatness 200인 Polycarbonate 재질의 기판 위에 CNC공작기계를 사용하여 유로를 제작하고 상부에 젤라틴 코팅 부분 2를 포함한 총 두께 12의 membrane 필름을 부착하였다. 이후 775 nm 파장의 펨토초 레이저를 사용하여 10${\times}$10 개수의 홀을 형성 한 후 홀 주위의 thermal damage와 레이저의 파워에 따른 홀의 형태와 크기 변화를 비교하였다. 실험 결과 membrane 막의 젤라틴 코팅 측면 홀의 평균 직경은 레이저의 파워와 비례하여 증가하였으며, 레이저 파워가 일정한 임계치에 도달하면 특정 시점에서 수렴됨을 확인하였다. 또한 PET 측면의 직경은 서서히 증가하고 빠르게 일정한 값으로 수렴됨을 확인하였다. 본 실험에서는 펨토초 레이저의 특성 파라미터와 레이저의 가공 조건을 수립함으로써 실험에서 사용 된 레이저를 이용한 드릴링 방안을 제시한다.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2001.05a
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• pp.307-313
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• 2001

In this Paper, friction welding optimization for 1Cr0.5Mo-STS304($\Phi$14mm), AE applications for the weld quality evaluation and the applications of various life prediction methods such as LMP(Larson-Miller Parameter) and ISM(initial strain method) were investigated : the creep behaviors of those steels and the friction welded joints under static load were examined by ISM combined with LMP at 400, 500, 550 and $600^{\circ}C$, and the relationship between these two kinds of phenomena was studied. The real-time predicting equations of elevated-temperature creep life(fracture time) under any creep stress at any elevated- temperature could be developed by LMP and LMP-ISM, It was confirmed that the life prediction equations by LMP and LMP-ISM are effective only up to 10$^2$hrs and can not be used for long times of 10$^3$-10$^{6}$ hrs, but by ISM it can be used for long times creep prediction of more than 10$^4$hrs with most reliability.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2016.11a
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• pp.187-189
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• 2016

미디어 이용 패턴이 TV 에서 다양한 스마트 기기로 넓어지고 있으며, 인터넷이 가능한 환경에서 광범위한 미디어 콘텐츠 제공이 가능하다. 최근에는 실감형 콘텐츠를 위해 360도 카메라와 이를 제어하는 방식들이 소개 되고 있다. 하지만 이러한 기술들을 활용해 더 많은 콘텐츠를 생성하기 위해서 콘텐츠의 특성을 고려한 실감 시청 체험 기술 서비스의 제공이 필요하다. 본 논문에서는 실감 시청 체험을 극대화할 수 있는 개인방송용 실감형 콘텐츠 제작 기술 서비스에 제안한다. 사용자와 상호작용이 가능한 실감 미디어 서비스를 제공하기 위해 카메라들의 배치, 뷰포인트 선택, 다양한 시청체험을 가능하게 할 파라미터 종류들을 정의한다. 본 연구를 통해 다양한 유형의 실감형 개인방송 콘텐츠를 제공할 수 있을 것으로 기대된다.