• 전자공학회논문지
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• 제52권9호
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• pp.125-131
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• 2015

함정용 전자광학추적장비의 종속추적 표적지향 성능 개선을 위해 칼만 필터를 제안하였다. 전자광학추적장비의 추적기능 수행 시 표적지향 성능 저하의 주요 요인인 전송 지연 및 측정 오차를 칼만 필터를 활용할 경우 최소화할 수 있는 장점이 있다. 칼만 필터를 활용하여 방위각, 고각 방향으로의 표적지향 오차가 감쇄됨을 확인하고 전자광학추적장비에 적용해봄으로써 전자광학장비에서 빈번하게 발생하는 표적 추적 오차 개선 시스템으로 적합성을 제시하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.465-468
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• 2001

An aerostatic stage has frictionless behavior, so it has a advantage of investigation into positioning characteristics. A one-dimensional aerostatic ceramic stage with ballscrew driven and laser scale feedback system is manufactured, aiming at investigating positioning characteristic of ultra-precision stage. We confirm, this ceramic aerostatic stage has a 10nm micro resolution, and can be reduced mean of position error by compensation of numeric control command. By means of analyzing relationship of position error and change of temperature, we build a on-line compensation algorithm of position error from the measured temperature data. So we can improve repeatability of ultra-precision stage up to 34%($0.095{\mu}$) of the normal condition.

• 한국통신학회논문지
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• 제39A권6호
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• pp.333-342
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• 2014

본 논문은 OFDM 블록에 파일럿 심볼들이 빗 형태의 패턴에 따라 배치된 경우, 가상 부반송파를 가지는 OFDM 시스템의 channel frequency response (CFR)를 추정하는 여러 방식들을 서로 비교한다. 채널 임펄스 응답을 먼저 예측하는 것이 목적인 minimum mean square error (MMSE) 기반의 채널추정 방식과 누설현상의 억제가 목적인 MMSE 기반의 채널추정 방식이 지금까지 비교되지 않았기 때문에, 본 논문에서는 후자 방식과 전자 방식의 mean square error (MSE) 값들의 차이가 양수가 됨을 유도함으로써 전자 방식의 우수성을 논리적으로 증명한다. 아울러 본 논문에서는 파일럿 수의 변화가 MMSE 기반 채널추정 방식과 least-square (LS) 기반 채널 추정 방식의 성능에 미치는 영향을 조사한다. 컴퓨터 시뮬레이션을 통해 채널추정 방식들의 성능을 정량적으로 확인한다.

• 한국전산유체공학회지
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• 제20권1호
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• pp.99-104
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• 2015

Aero-optic phenomena cause the image position displacement on an imaging plane of the airborne optical/IR systems. Particularly, the aero-optic boresight error(BSE) is important factor for homing, positioning and aiming applications of hypersonic flight interceptor missile. In this paper, an estimating method of aero-optic BSE for a hypersonic flight vehicle is studied. A ray tracing method and a transform method of refractive index fields from flow density fields are combined with computational fluid dynamics(CFD) method.

• Communications for Statistical Applications and Methods
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• 제3권1호
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• pp.243-255
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• 1996

The number of neutron signals from a neutral particle beam(NPB) at the detector, without any errors, obeys Poisson distribution, Under two assumptions that NPB scattering distribution and aiming errors have a circular Gaussian distribution respectively, an exact probability distribution of signals becomes a Poisson-power function distribution. In this paper, we show that the error rate in simple hypothesis testing for the limiting Poisson-power function distribution is not zero. That is, the limit of ${\alpha}+{\beta}$ is zero when Poisson parameter$\kappa\rightarro\infty$, but this limit is not zero (i.e., $\rho\ell$>0)for the Poisson-power function distribution. We also give optimal decision algorithms for a specified error rate.

• Journal of Electrical Engineering and Technology
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• 제13권6호
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• pp.2168-2177
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• 2018

The unavoidable forecast error of wind power is one of the biggest obstacles for wind farms to participate in day-ahead electricity market. To mitigate the deviation from forecast, installation of energy storage system (ESS) is considered. An accurate model of wind power forecast error is fundamental for ESS sizing. However, previous study shows that the error distribution has variable kurtosis and fat tails, and insufficient measurement data of wind farms would add to the difficulty of modeling. This paper presents a comprehensive way that makes the use of mixed skewness model (MSM) and copula theory to give a better approximation for the distribution of forecast error, and it remains valid even if the dataset is not so well documented. The model is then used to optimize the ESS power and capacity aiming to pay the minimal extra cost. Results show the effectiveness of the new model for finding the optimal size of ESS and increasing the economic benefit.

• Smart Structures and Systems
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• 제3권3호
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• pp.299-320
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• 2007

Smart sensors densely distributed over structures can provide rich information for structural monitoring using their onboard wireless communication and computational capabilities. However, issues such as time synchronization error, data loss, and dealing with large amounts of harvested data have limited the implementation of full-fledged systems. Limited network resources (e.g. battery power, storage space, bandwidth, etc.) make these issues quite challenging. This paper first investigates the effects of time synchronization error and data loss, aiming to clarify requirements on synchronization accuracy and communication reliability in SHM applications. Coordinated computing is then examined as a way to manage large amounts of data.

• 대한기계학회논문집A
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• 제30권8호
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• pp.897-905
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• 2006

This study considers an experimental design of disturbance compensation control to improve stabilization performance of main battle tanks. An adaptive non-parametric design technique based on the Filtered-x Least Mean Square(FXLMS) algorithm is applied in the consideration of model uncertainties. The optimal compensator is designed by two-step design procedures: determination of frequency response function of the disturbance compensator which can cancel the disturbance of series of single harmonics by using the FXLMS algorithm and determination of the compensator polynomial which can fit the frequency response function obtained in the first step optimally by using a curve fitting technique. The disturbance compensator is applied to a simple experimental gun-torsion bar-motor system which simulates gun driving servo-system. Along with experimental results, the feasibility of the proposed technique is illustrated. Experimental results demonstrate that the proposed control reduces the standard deviation of stabilization error to 47.6% that by feedback control alone. The directional properties of the FXLMS Algorithm such as the direction of convergence and its convergence speed are also verified experimentally.

• 전기전자학회논문지
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• 제7권1호
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• pp.97-106
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• 2003

ARQ 기반의 오류 제어에서 불완전한 오류 검출로 인해 패킷에 오류가 잔류하게 된다. 본 논문에서는 사본 중복 전송 ARQ에서 잔류 오류를 감소시키기 위한 재전송 요청 및 오류없는 사본의 결정 규칙을 제안한다. 이러한 $(m, \;{\sigma})$ 규칙을 사본 중복 전송 ARQ에 적용할 때, 잔류 오류는 감소하나 기존의 단일 사본만을 전송하는 ARQ에 비해 지연 및 throughput 성능은 열화될 수 있다. 따라서 $(m, \;{\sigma})$ 규칙이 적용된 사본 중복 전송 ARQ에서 야기되는 성능의 trade-off를 평가하기 위한 해석적 방법을 개발한다. 이러한 해석적 방법으로 구한 계량적 결과로부터 $(m, \;{\sigma})$ 규칙의 파라미터, 채널의 성질, 트래픽 부하가 오류 잔류 확률, 패킷 상실, 패킷 지연, throughput 등에 미치는 영향을 검토하여 다양한 QoS 요구 조건을 용이하게 수용할 수 있는 $(m, \;{\sigma})$ 규칙의 적응성을 확인한다.

• 한국군사과학기술학회지
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• 제10권2호
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• pp.21-30
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• 2007

A practical method to design the input shaping which generates control command is proposed in this paper, We suggest an experimental technique considering human operator's target tracking error to improve aiming accuracy which significantly affects hit probability. It is known that stabilization performance is one of the most important factors for ground combat vehicle system. In particular, stabilization error of the manual target tracking system mounted on moving vehicle directly affects hit probability. To reduce this error, we applied input command shaping method using preprocessing filtering and functional curve fitting. First of all, we construct the human operator model to consider effects of human operator on our system. Input shaping curve is divided into several regions to get rid of the above problems and to improve the system performance. At example design part, we chose three steps of functional command curve and determine the parameters of the function by the proposed design method. In order to verify the proposed design method, we carried out the experiments with real plant of a fighting vehicle.