• 한국산업융합학회 논문집
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• 제9권2호
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• pp.123-131
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• 2006

The subject of this study is to find out the characteristics of spacial expression in 'Le Carceri' of Giovannibattista Piranesi. Piranesi was the classicist from using classical motif. But for using itself he was not absolute canon of classical but playing tool. Because his etchings of perspective were presented the modernity not fixed the frame. The etchings of Le Carceri were characterized the dark, deep, heavy and devastating. In conclusion, the characteristics of spacial composition in his etchings were presented the simultaneity of time both classic and contemporary time. And it could represented the nonexistent of structurality for visual rationality. Architectural & de-architectural elements of his drawing were become in fragments. So the fragmented elements, his etchings have shawn the off-center to cast off the classical concept. And also the body of human was become the thing of object in his drawing. That is, it was inverted the subject and the object and the function of prison depicted in canvas is disappeared. This is the point of evocation in Piranesi' idea.

• 대한기계학회논문집
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• 제12권1호
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• pp.163-172
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• 1988

본 논문에서는 GAC방법을 이용하여 공작기계의 안내면오차를 수치제어 공작기계가 가지고 있는 가공조건의 조절 능력을 이용하여 가공오차를 보상제어 함으로써 규명(identification)할 수 있는 방법을 제시한다.

• Journal of Electrical Engineering and Technology
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• 제12권1호
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• pp.198-206
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• 2017

This paper presents a novel scheme to estimate the rotor position of a single-phase hybrid switched reluctance motor (HSRM). The back-EMF generated by the permanent magnet (PM) field whose performance is motor parameter independent is adopted as an index to achieve the sensorless control. The differential value of back-EMF is calculated by hardware and processed by DSP to capture a fixed rotor position four times for every mechanical cycle. In addition, to accomplish the normal starting of HSRM, the determination method of the turn-off time position at the first electrical cycle is also proposed. In this way, a sensorless operation scheme with adjustable turn on/off angle can be achieved without substantial computation. The experimental verification using a prototype drive system is provided to demonstrate the viability of the proposed position estimation scheme.

• ETRI Journal
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• 제45권1호
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• pp.119-130
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• 2023

We propose a quantized gradient search algorithm that can achieve global optimization by monotonically reducing the quantization step with respect to time when quantization is composed of integer or fixed-point fractional values applied to an optimization algorithm. According to the white noise hypothesis states, a quantization step is sufficiently small and the quantization is well defined, the round-off error caused by quantization can be regarded as a random variable with identically independent distribution. Thus, we rewrite the searching equation based on a gradient descent as a stochastic differential equation and obtain the monotonically decreasing rate of the quantization step, enabling the global optimization by stochastic analysis for deriving an objective function. Consequently, when the search equation is quantized by a monotonically decreasing quantization step, which suitably reduces the round-off error, we can derive the searching algorithm evolving from an optimization algorithm. Numerical simulations indicate that due to the property of quantization-based global optimization, the proposed algorithm shows better optimization performance on a search space to each iteration than the conventional algorithm with a higher success rate and fewer iterations.

• 한국병원경영학회지
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• 제18권2호
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• pp.81-103
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• 2013

This study is to research cost accounting practice and to analyze propriety of patients' medical payment in artificiality kidney center. The researched cost datum of the year 2012 are as follows. - Hemodialysis medical treatment was reimbursed as much as 158,001 won in case of health insured patients, but payed-off as much as 135,810 won. - The average figure of the total hospitals and clinic center is 1,603,303 won, and one time cost of hemodialysis treatment is 154,487 won. Optimal treatment pay are suggested as follows. First, Regardless of the notified classification from MOHW(Ministry of Health and Welfare), 136,000 won of fixed price payment classification needs to be reclassified by patients, severity and tobe rearranged by fixed price payment system of hospitals. Second, Fixed payment code notified by the Ministry of Health and Welfare is recommended to be simplifies and to reflect according to contents of the medical treatment rendered to patients. Third, Establishment of artificial kidney center has to be risk managed because of its huge investment. Fourth, Cost analysis model has to be maintained as basis together with appropriate application of conversion index model mixed with SGR model.

• 한국전자통신학회논문지
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• 제10권2호
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• pp.275-282
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• 2015

NAND 플래쉬메모리는 전원이 꺼져도 데이터를 유지할 수 있고 저비용, 고용량의 특징을 가지기 때문에 휴대용 기기에서 많이 활용되고 있다. 플래쉬메모리에서 대용량의 데이터를 효과적으로 처리하기 위하여 색인을 필수적으로 사용해야 한다. 그러나 플래쉬메모리는 쓰기 연산의 비용이 크고 덮어쓰기 연산을 지원하지 않기 때문에 기존의 디스크기반 색인을 사용하면 성능이 저하되는 문제가 발생할 수 있다. 본 논문에서는 플래쉬메모리에서 고정그리드화일 색인을 구현하고 다양한 조건에서 성능 평가를 수행한다. 이를 위하여 질의연산과 변경 연산의 비율에 따른 평균 수행 시간을 측정한다. 그리고 디스크에서의 수행 시간과 비교한다.

• 정보과학회 논문지
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• 제45권1호
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• pp.86-93
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• 2018

다수의 클라이언트가 대역폭을 공유해 스트리밍 서비스를 받는 경우 HTTP 적응적 스트리밍(HTTP Adaptive Streaming)은 세그먼트 요청의 ON-OFF 패턴으로 인해 대역폭을 부정확하게 측정하는 문제가 있다. ON-OFF 패턴으로 인한 문제를 해결하기 위해 제안된 PANDA (Probe AND Adapt)는 목표 대역폭을 증가시키면서 요청할 세그먼트의 품질을 결정한다. 하지만 목표 대역폭을 고정된 양만큼 증가시키기 때문에 대역폭 활용도가 낮고 대역폭 변화에 느리게 반응하는 문제가 있다. 본 논문에서는 PANDA의 낮은 대역폭 활용도와 느린 반응성을 개선하기 위한 비디오 품질 조절 기법을 제안한다. 제안하는 기법은 세그먼트 다운로드 시간과 요청 간격을 비교해 대역폭 활용도를 판단한 후 대역폭 활용도에 따라 목표 대역폭을 증가시키는 양을 조절한다. 실험을 통하여 제안하는 기법이 대역폭을 충분히 활용하고 대역폭 변화에 빠르게 반응하는 것을 확인하였다.

• 한국정보과학회논문지:컴퓨팅의 실제 및 레터
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• 제12권1호
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• pp.66-77
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• 2006

본 논문에서는 ON/OFF 스위치 및 ON/OFF 센서만을 이용하여 홈 거주자의 위치탐색 및 추적하고, 이 과정을 원격으로 실시간 모니터링 서비스를 제공할 수 있는 시스템을 설계하였다. 구현환경으로 본 시스템은 우리가 개발해온 분산객체그룹 프레임워크 기반에서 구현되었다. 홈 거주자의 위치를 파악하기 위해서 우리는 개폐기능을 가지는 실내 고정된 위치에 있는 구조/시설물 및 가전제품 등에 ON/OFF스위치 및 ON/OFF 센서들을 부착한 한 흠 구조를 보인다. 홈 거주자에 의해 이들이 개폐(ON/OFF)될 때, ON/OFF 스위치 및 ON/OFF 센서로부터 발생된 신호를 흠 서버 시스템에서 수신한다. 이때 신호가 발생한 실위치가 곧 홈 거주자의 위치가 된다. 홈 서버시스템에서는 실제공간에서 검출된 홈 거주자의 위치를 원격 데스크 탐 시스템이나 이동 단말기의 화면인 가상공간상에 이를 사상(mapping)하여 홈 거주자의 위치를 표현하고, 또한, 탐색된 위치를 시간별로 분석하여 홈 거주자의 이동패턴과 이동영역, 운동량 등을 얻어 헬스케어 정보를 구축하도록 하였다. 마지막으로 본 시스템은 이들 정보를 원격 모니터링 서비스를 위해 제공하도록 하였다.

• 제어로봇시스템학회논문지
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• 제2권3호
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• pp.174-180
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• 1996

The friction is one of the nonlinearities to be considered in the precise position control of a system which has electromechanical components. The friction has complicated nonlinear characteristics and depends on the velocity, the position and the time. The conventional fixed friction compensator and the controller based on linear control theory may cause the steady state position error or oscillation. The plant to be controlled in this study is a positioning system with a linear brushless DC motor(LBLDCM). The system behaves like a 4th-order model including the compliance and the friction. In this study, the plant model is simplified to a 2nd-order model to reduce the computation in on- line estimation. Also, to reduce the computation time, only the friction is estimated on-line while the mass and the viscous damping coefficient are fixed to the values obtained from off-line estimation. The validity of the proposed scheme is illustrated with the computer simulation and the experiment where the friction is compensated by using the estimation.

• 반도체디스플레이기술학회지
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• 제3권1호
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• pp.21-26
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• 2004

Recently with the development of power switching device and DSP which has peripheral devices to control AC servo system, the servo technology has met a new development opportunity. Those things make it possible to reduce the time of developing a AC servo system. Fixed point DSP such as TMS320F240x, and TMS320F28x series have a disadvantage in calculating floating number where TMS320C32 or TMS320C31 are floating point DSP. However they usually become a complex hardware system to implement the AC servo system and it increases the cost. In this study, a DSP based AC servo system with a 3-phase PMSM is proposed. The newly produced DSP TMX320F28l2-version C which has the performance of fast speed, 150MIPS, and a rich peripheral interface such as a 12bit high speed AD converter, QEP(Quadrature Encoder Pulse) circuit, PDPINT(Power Drive Protect Interrupt), SVPWM module and dead time module are used. This paper presents a method to overcome fixed point calculating using scaling all parameters. Also space vector pulse width modulation (SVPWM) using off-set voltage and a digital PI control are implemented to the servo system.