• 한국정보통신학회논문지
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• 제22권2호
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• pp.354-361
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• 2018

본 논문은 비행제어 비행체 관리 시스템 대신 한국형 기동헬기 임무컴퓨터의 비행운용 프로그램에서 구현한 측면 항법 알고리즘 설계 및 검증에 대하여 기술하였다. 구현된 측면항법 기능은 비행제어 시스템으로 롤 명령을 보내고 롤 명령 값은 임무컴퓨터의 제어 알고리즘에서 계산한다. 임무컴퓨터에서 제어 알고리즘 계산 시 항공기의 자세 및 위치에 대한 측정값을 이용한다. 이 입력 값들을 이용하여 임무컴퓨터에 탑재된 비행운용 프로그램은(선택한 비행계획 등)항법 요구를 롤 명령으로 자동조종으로 보낸다. 체계통합리그에서의 통합시험, 지상 및 비행시험을 통해 측면 항법 알고리즘을 검증하였다.

• 한국통신학회논문지
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• 제21권11호
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• pp.2942-2953
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• 1996

This paper studies the effect of intersymbol interference due to sampling-time jitter on the worst-case bit error probability in a digital modultation over an additive white Gaussian noise channel, with the squared-root raised-cosine filters in the transmitter and the receiver. It derives approximation formulas using the Taylor series approximations. the principal results of this paper is the relationship between the worst-casse bit error probability, the degree of jitter, the roll factor of the raised cosine filter, and other quantities. Numerical results show, as expected, that the intersymbol interference decreases as the roll-off factor increases and the jitter decreases. They also show that the approximation formulas are accurate for smally intersymbol interference, i.e., for large roll-noise ratio $E_{b/}$ $N_{0}$.leq.7 dB and begin to lose accuracy for larger signal-to-noise ratio.o.o.

• 한국산학기술학회논문지
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• 제8권6호
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• pp.1381-1387
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• 2007

현재까지 다양한 연속적인 공정시스템은 섬유, 제지 및 인쇄 등 많은 산업응용 분야에서 사용되고 있다. 이러한 응용분야에서 공정처리를 받고 있는 제품에 가해지는 장력은 원료의 공급속도와 생산되는 제품의 방출 속도간의 속도차에 의해 변화될 수 있다 특히, 섬유공정에서 공급속도와 방출 속도간의 속도차나 관성효과에 의해 발생되는 장력변동은 제품의 품질을 저하시킬 수 있다. 따라서 섬유공정에서 이러한 요인들에 의해 발생되는 장력 변동을 적절한 방법에 의해 보상하는 것은 매우 중요한 문제이다. 본 논문에서는 이러한 문제를 해결하기 위하여 섬유공정에서 많이 사용되고 있는 환편기 시스템에서의 장력제어 문제를 다루고자 한다. 먼저 일반적인 연속공정의 권취 메커니즘에 대한 장력 관계식을 모델링한다. 다음은 환편기 시스템에서 풀림롤과 감김롤을 효율적으로 구동하기 위하여 풀림롤과 감김롤간의 속도차와 관성특성을 고려한 새로운 장력제어 방법을 제시한다. 다양한 실험을 통하여 제안된 장력제어 방법이 주어진 환편기 시스템의 공정구간에서의 장력제어 성능을 향상시킬 수 있음을 보인다.

• 한국자동차공학회논문집
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• 제18권5호
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• pp.56-61
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• 2010

This paper presents dynamic clearance verification considering engine movement for vehicle engine room package and validates through physical vehicle test. Traditionally, static clearance guide has been used for engine room package, but it's only 2-dimension criteria that results in requiring unnecessary space and it's not possible to conduct engine movement with real driving conditions. Thus, the dynamic DMU considers engine movement based on 28 load cases that are Roll Data analyzed by CAE for maximum engine movement and visualizes part-to-part dynamic clearance into virtual space. The dynamic DMU enables to develop compact engine room package without unnecessary space. The result of comparison between simulation and physical test has 0.892 correlation coefficient.

• 한국정밀공학회지
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• 제15권1호
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• pp.160-168
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• 1998

In this paper. the Joint reaction forces in the suspension system of a passenger car are determined to calculate the deflections and stresses in the damper strut. A mathematical model of the Roll Stabilizer Bar(RSB) is developed to include the RSB forces in the dynamics analysis. Using these RSB forces, the variations of the damper forces and spring forces due to the wheel strokes are determined in a McPherson strut suspension. The graphs of shear force diagram, bending moment diagram, bending stress and deflections are drawn by the calculated joint reaction forces.

• 한국해양공학회지
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• 제32권6호
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• pp.440-446
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• 2018

The effects of an anti-rolling tank (ART) on vessel motions were numerically investigated. The potential-based BEM vessel motion simulation program and particle-based computational fluid dynamics program were dynamically coupled and used to perform a simulation of vessel motions with ART. From the time domain simulation results, the response amplitude operators for sway and roll motions were obtained and compared with the corresponding experimental and numerical results. Because the main purpose of ART was only to reduce roll motions, it was important to show that the natural properties of a floating vessel were not changed by the effects of ART. Various ART filling ratios and several ART positions were considered. In conclusion, ART only reduced the roll motion regardless of its filling ratio and position.

• International Journal of Aeronautical and Space Sciences
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• 제8권1호
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• pp.32-45
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• 2007

The T-50 advanced supersonic jet trainer employs the Relaxed Static Stability (RSS) concept to improve the aerodynamic performance while the flight control system stabilizes the unstable aircraft and provides adequate handling qualities. The T-50 flight control laws employ a proportional-plus-integral type controller based on a dynamic inversion method in longitudinal axis and a proportional type controller based on a blended roll system with simple roll rate feedback and beta-betadot feedback system. These control laws are verified by flight tests with various maneuver set flight envelopes and the control laws are updated to resolve flight test issues. This paper describes several concepts of flight control laws used in T-50 to resolve those flight test issues. Control laws for solving the roll-off problem during pitch maneuver in asymmetric loading configurations, improving the departure resistance in negative angle of attack conditions and enhancing the fine tracking performance in air-to-air tracking maneuvers are described with flight test data.

• 한국정밀공학회지
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• 제26권11호
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• pp.70-76
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• 2009

Web tension control system recently have been applied to OLED(Organic Light-Emitting Diode), RFID of flexible material, e-Paper and PLED(Polymeric LED) and various web control algorithms have being developed for higher productivity and product quality These system need an accuracy model to design and implement controller. In this paper, the web tension control system with dancer roll is mathematically modeled. Mathematical model consists of 8 subsystems and each subsystems can be described as impedance structure which connected by velocity and tension. Mathematical model is different from the estimated model at high frequency range because of structure dynamics which is ignored on mathematical model. The estimated model is derived using ARMAX model. The controller is designed using the estimated model. The step response of the estimated model are compared with that of physical model for a validation of estimated model. The experimental results show a good match between them.

• 대한기계학회논문집A
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• 제22권4호
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• pp.723-730
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• 1998

With the introduction of edge drop control system in Tandem Cold Rolling Mill, it is necessary to develop te numerical expression for the set-up and edge drop automatic control of cold rolled sheet. As a first step we developed a simulation program which predicts profile and the amounts of edge drop at the delivery side of each stand by using roll deformation anlysis with the slit roll model. And by using the program the effect of various rolling conditions on edge drop was investigated. As a result the relations were obtained between the amounts of edge drop and rolling conditions. Based on above relations, the numerical expression was developed for the set-up and automatic control of edge drop by multi-regression of simulation results for the variation of edge drop amount with each rolling condition.

• 수산해양교육연구
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• 제11권2호
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• pp.184-202
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• 1999

The roll damping characteristics of the three models of a small fishing(3 ton class fishing vessel), such as the bare hull, hull with bilge keels, and hull with bilge keels and a central wing are investigated by the free roll and head waves tests in calm water in a towing tank with the various forward speeds, initial angles and OG's. The experimental results are compared with the numerical results of mathematical modelings by the energy method for these three models and the energy dissipation patterns are also compared. And the wave length variations are also included. The experimental results are compared with the numerical results of mathematical modelings by the energy method for these three models and the energy dissipation patterns are also compared. The roll damping moment of the models is increased for zero speed cases, but as the speed increases, the effect of the waves on the roll damping of the models with the additional devices is negligible due to the much increased damping caused by the lift increase.