• Journal of the Korean Institute of Navigation
• /
• v.18 no.4
• /
• pp.11-21
• /
• 1994

Final aim of this paper is a study on simulation of automatic steering of a ship in random seas. In order to achieve this aim, we need excitation due to random seas. The excitation may be estimated from energy spectrum of irregular waves and response functions of manoeuvring motion of a ship in regular waves. This paper deals with response functions of manoeuvring motion of a ship in regular waves. We discussed New Strip Method(NSM) of sway-yaw-roll coupled motions in regular waves. NSM is defined in space axes system and that has been used to predict seakeeping performance of a ship in waves. But ship manoeuvring is defined in body fixed axes system. So we cannot use NSM theory itself in predicting manoeuvring performance of a ship in waves. We introduced relationship between space axes system and body fixed axes system. And we developed modified NSM which was defined in body fixed axes system and was able to be used in manoeuvring motion of a ship in waves. We calculated sway and yaw response functions of manoeuvring motion of a bulk carrier in regular waves.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2004.11a
• /
• pp.958-961
• /
• 2004

This paper presents a plant control panel model for the analysis. Seismic qualification analysis for the plant control panel is carried out to confirm the structural integrity under the seismic conditions represented by required response spectra(RRS). For the analysis finite element method(FEM) is used. And mode combinations are adopted to obtain the reliability of the spectrum analysis. The analysis results shows that the plant control panel system is designed as a dynamically rigid assembly, without any resonance frequency below 33Hz. The calculated stress of the plant control panel system is much less than yield stress of used steel.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2004.11a
• /
• pp.129-133
• /
• 2004

This paper is the result of a experimental study about non-linear one to one modal coupling of a flexible circular cantilever beam which was transversely excited with harmonic excitation. It was proved that 2 order jumping in out of plane was caused by jump phenomenon in in-plane of flexible circular cantilever beam, because of non-linear coupling. In addition, cantilever beam showed hardening spring characteristics in in-plane and softening spring characteristics in out-of-plane.

• Proceedings of the Korean Society of Computer Information Conference
• /
• 2023.07a
• /
• pp.101-103
• /
• 2023

기존의 제설작업은 인력에 의존하여 시간과 비용이 많이 소요되고, 작업 중 발생할 수 있는 안전사고의 위험성이 존재한다. 본 논문은 제설작업의 효율성과 안전성 그리고 신속성을 높이기 위해 임베디드시스템을 활용한 드론용 제설장치의 설계에 대해 다루고 있다. 임베디드시스템은 RF모듈을 구성하고 무선으로 제어조종이 가능하도록 고안하였다. 드론에 장착되는 제설장치의 임베디드시스템으로는 아두이노메가2560을 채택하였다. 아두이노메가2560은 제설장치의 제어에 필요한 실시간 데이터수집, 처리, 응답을 처리와 RF모듈에서 오는 데이터에 대한 연산 및 제어 수행을 할 수 있다. 제설장치를 장착한 드론은 기존의 제설작업보다 안전하고 신속하게 수행될 것으로 기대된다.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.34 no.6
• /
• pp.83-91
• /
• 2006

An advanced method of Relaxed Static Stability (RSS) is utilized for improving the aerodynamic performance of modern version supersonic jet fighter aircraft. The flight control system utilizes RSS criteria in longitudinal axis to achieve performance enhancements and improve stability. The flight control law of T-50 advanced trainer employs RSS concept in order to improve the aerodynamic performance and guarantee aircraft stability. The longitudinal center of gravity(X-c.g) varies as a function of external stores, fuel state and gear position. Shifts in X-c.g relate directly to longitudinal static margin in aircraft stability. This paper deals the maximum aft X-c.g for critical aircraft loadings and checks static margin limits using sensitivity such as damping, natural frequency, gain and phase margin. And nonlinear analysis was conducted for such as short period input. And also, this paper shows the T-50 aircraft stability based on the result of high angle of attack flight such as upright and inverted departure.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.33 no.2
• /
• pp.54-59
• /
• 2005

Nonlinear aeroelastic analyses of a missile control fin are performed considering backlash and dynamic stiffness of actuator. Doublet-Hybrid method is used for the calculation of subsonic unsteady aerodynamic forces, and aerodynamic forces are approximated by the minimum-state approximation. For nonlinear flutter analysis backlash is represented by a free-play and is linearized by using the describing function method. Also, dynamic stiffness is function of frequency and is calculated by solving equation of motion for actuator. The linear and nonlinear flutter analyses show that the aeroelastic characteristics are significantly dependent on the backlash and dynamic stiffness. From the nonlinear flutter analysis, various types of limit cycle oscillations are observed in a range of air speeds below the linear divergent flutter boundary. The nonlinear flutter characteristics and the nonlinear aeroelastic responses are also investigated in the time domain.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.34 no.3
• /
• pp.81-86
• /
• 2006

This paper deals with a driving current fault monitor design methodology for a DDV actuation system which has a dual hydraulic power supply system, and triplex electric control capability. A fault existing among these redundant channels should be detected accurately and removed timely, and the remaining channels are to be reconfigured in order to compensate the role of a removed faulty channel. An integrated analysis on the aerodynamics, flight control laws, and DDV actuation system is essential for the design of an actuation system fault monitor. A method to define a fault transient boundary which specifies a maximum travel of an actuation system caused by the first faulty operation is proposed based on the top level requirement on the fault effect specified in MIL-F-8785C.

• Bulletin of the Society of Naval Architects of Korea
• /
• v.27 no.3
• /
• pp.31-37
• /
• 1990

To obtain the values of linear stability derivatives, both analytical and experimental methods are now proposed and in use. The experimental method is well known as the planar motion mechanism(PMM) test. Its concept is to drive the model with a prescrived frequency and amplitude of the motion and pick up the hydrodynamic forces. But this kind of method is inconvenient in case we want to know the stability derivatives in wider range of the frequencies. So a different method is attempted that with one test run, we can get the derivatives in wider range of the frequencies. This technique forces the impulsive motion on the model, using the power of the oil pressure pump. This kind of method was originated by Scragg, C.A., Cummins, W.E, or Frank, T., This resarch is a further development of such preceding works. Todd's series 60(Cb=0.7) 2.00M model is chosen for the test and the results are compared with Van Leeuwen's famous PMM test results.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.40 no.3
• /
• pp.251-257
• /
• 2012

The flight controller should meet the flying qualities, stability margins, and time response requirement according to the class of a target aircraft or UAV. Classical design process of PID controller is a very time consuming process and needed trial and erros. The best way is to apply the multi-disciplinary optimization algorithm to meet the numerous constraints of controller requirements. This paper presents how multi-objective parameter optimization (CONDUIT) can be used to determine many design parameters of lateral stability and augmentation system for roll and heading controller of the small UAV. To verify the effectiveness of applying the optimization method, designed controller using optimization are compared with the baseline controller that is designed only considering the time responses.

• Communications of Mathematical Education
• /
• v.35 no.1
• /
• pp.15-36
• /
• 2021

A well-designed mathematics lesson is the foundation for effective mathematics instruction. Given this significance, this paper focused on analyzing what would be important elements for in-service teachers in planning an elementary mathematics lesson. For this purpose, a total of 27 in-service teachers were asked to write down whatever they would consider important in designing a mathematics lesson. A mathematics lesson plan prepared by a pre-service teacher was provided for the in-service teachers. They were then asked to analyze the strengths of the lesson plan and to provide detailed feedback on how to improve it. The results of this study showed that the in-service teachers tended to analyze the given mathematics lesson plan in terms of what they considered important regarding lesson design. Such elements were specified when the in-service teachers described the strengths and feedback for improvement of the lesson plan. In particular, the aspects of instructional strategies and materials were explained in detail. Based on these results, this paper is expected to provoke discussions on lesson design of in-service teachers and subsequent research.