• 대한조선학회지
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• 제2권1호
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• pp.15-19
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• 1965

The stability curves are very important data to decide the seaworthiness of all kinds of ships among waves. Both statical and dynamical stability curves on a rectangular coordinate system have broadly been handled at ship yards or at the government concerned, up to data. As concerns a method of obtaining a statical stability curve on polar coordinate system, the papers were presented once. Also, it is of use to research the dynamical stability curve on polar coordinate system. Author treated of the dynamical stability curve by four different methods, and tried to set the stability indicator inboard, adopted those proposals, in order to give some aids for good navigation on the sea. Fig. 1. shows a drawing method in case of the position of centre of buoyancy can be previously pointed out on the line corresponding to its inclination. Fig. 2. shows a method used a statical stability curve on polar coordinate. Fig. 3. shows a method obtained by the most simplified means. Fig. 4. shows dynamical stability curve made by geometrical expression method, instead of dynamical lever. A simple stability indicator which was mechanized above characteristics is attempted by author as shown Fig. 5 and Fig.6. It is demanded at hand, for more advanced improvement of such indicator.

• 대한의용생체공학회:의공학회지
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• 제14권4호
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• pp.379-386
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• 1993

This paper describes design of a Chaos analyser and its applications to analysis of nonlinear characteristirs of ECG. The proposed system can easily distinguish chaotic system among the various dynamical systems by chaotic quantitative and qualitative analysis and also chaotic characteristics which represents states of nonlinear dynamical system. And we have also proposed new possibilities to recognize abnormal state of ECG signal using the chaotic characteristics.

• 대한전자공학회논문지
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• 제27권5호
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• pp.793-801
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• 1990

A single mode fiber-optic Mach-Zehnder interferometer for the measurement of strain is described. A fiber-optic strain gauge with great resolution and wide measurement range is realized. In order to varify the dynamic response, the measurements of strain below 1涅 with frequency range 5-50Hz are compared with a semiconductor strain gauge. We report theoretical evaluation for mechanical analysis, PZT-plate, the phase change in a fiber-optic strain gauge and a semiconductor strain gauge. The dynamical characteristics of a fiber-optic strain gauge and a semiconductor strain gauge output siganl show equivalent behavior. This result is shown in very good usage as the dynamical measurement of the low strain below 1涅 by this system.

• 대한기계학회논문집
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• 제14권3호
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• pp.755-760
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• 1990

본 연구에서는 Lindstedt-Poincare 방법을 이용하여, Duffing 진동계에 5차항 을 포함시킴으로써 진폭이 더 큰 운동에도 타당성이 있는 근사해를 구하고자 한다. VAXIMA를 사용하여 해석하는 과정은 부록에 첨부되어 있으며 이 작업은 VAX 11/750 컴 퓨터에서 수행된 것이다.

• International Journal of Aerospace System Engineering
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• 제2권1호
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• pp.24-30
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• 2015

In helicopter bearingless rotor design, the flexbeam is the key component of rotor system, which plays an importantrole in the blade flapping, lead-lag movement, torsion, and load transfer. Flexbeam must have the minimum torsion stiffness with enough tension strength. In this paper, we first investigated the torsion stiffness of different cross section configurations of the flexbeam through some simple experiments. Then we analyzed a rotor's dynamical characteristics with finite element method and got the rotor's fan plot. After that, we studied the relationship between the frequency changes with the spanwise distribution of mass and stiffness in bearingless rotor. Finally, we analyzed the influence of the flexbeam on dynamical characteristics of the bearingless rotor system, and completed the design of this type of rotor flexbeam.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국제학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.401-405
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• 1993

This paper presents a neuro adaptive control method for nonlinear dynamical systems based on artificial neural network systems. The proposed neuro adaptive controller consists of 3 layers artificial neural network system and parallel PD controller. At the early stage in learning or identification process of the system characteristics the PD controller works mainly in order to compensate for the inadequacy of the learning process and then gradually the neuro contrller begins to work instead of the PD controller after the learning process has proceeded. From the simulation studies the neuro adaptive controller is seen to be robust and works effectively for nonlinear dynamical systems from a practical applicational points of view.

• 대한토목학회논문집
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• 제26권5B호
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• pp.439-446
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• 2006

본 연구에서는 강수량 및 기온과 같은 수문기상자료의 비선형 동역학적 성분을 추출하기 위해 웨이블렛 변환을 적용하여 대상자료를 재현기간별 성분으로 분리하였다. 변환을 위한 기저함수로는 Daubechies의 9번 ('db9') 웨이블렛 함수를 사용하였다. 또한 웨이블렛 변환의 스케일의 증가에 따른 각 분리단계에서 추출된 상세성분과 근사성분이 비선형 동역학적 특성을 지니는지를 판단하기 위하여 상관차원분석을 이용하였다. 즉 수문기상자료내에 비선형 동역학적 성질을 지니는 성분을 추출하기 위한 방법론으로써 웨이블렛 변환과 상관차원분석의 결합을 제안하였으며, 도출된 결과는 일반적으로 원자료를 이용할 경우에는 파악하기 어려운 대상자료의 시간에 따른 비선형적 변화를 분리 추출하기 위해 본 연구에서 제안한 방법이 적합함을 보이고 있다.

• Structural Engineering and Mechanics
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• 제44권3호
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• pp.305-323
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• 2012

Structural defects such as cracks are the source of local flexibilities and cause deficiencies in structural resistance. In the engineering constructions, structural elements sometimes are subjected to axial loading. Therefore, besides crack ratios and locations, influence of applied load on the stability and dynamical characteristics should also be explored. This study offers a numerical technique for the vibration and stability analysis of axially loaded cracked beams. The model merges finite element and component mode synthesis methods. Initially, stability analysis is completed and then dynamical characteristics of beams are found. Very good conformities between outcomes of the current study and those in literature, give the confidence that proposed method is reliable and effective.

• 천문학회보
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• 제19권
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• pp.7.2-8
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• 1994

• International Journal of Advanced Culture Technology
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• 제11권2호
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• pp.10-29
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• 2023

Grit or perseverance as a factor for student success and life has gained increasing attention. Statistical methods have been the norm in analyzing various aspects of grit, but they do not address the transient and dynamic behavior well. We, for the first time, developed two linear dynamical models that specifically address the feedback structure of a child's desire to achieve a high grade point average (GPA) and the necessary effort that will increase stress between parents and a child. We call the dynamical model as GSES (Goal, Status, Effort & Stress). The two dynamical models incorporate the positive (i.e., achieving a high GPA) and the negative sides (i.e., effort and elevated stress and thus unhappiness) for being gritty or perseverant. Different types of parenting style and a child's characteristics were simulated whether parents and a child are empathetic or stubborn to their expectations and stress (i.e., willing or unwilling to change). Simulations show that when both parents and a child are empathetic to each other's expectation and stress, the most stable situations with minimal stress and effort occur. When a stubborn parent's and a stubborn child were studied together, this resulted in the highest elevation of stress and effort. Stubborn parents and a complying or empathetic child resulted in considerably high stress to a child. Interference from parents may unexpectedly result in a situation in which a child's stress is seriously elevated. The GSES model shows the U-shaped happiness curve (i.e., reciprocal of stress) caused by the increasing and then decreasing goal