• 한국항공우주학회지
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• 제42권5호
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• pp.423-429
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• 2014

히스테리시스 댐퍼를 조합한 영구자석과 중력붐을 적용한 수동형 자세제어 안정화 방식은 시스템의 단순화가 가능하여 임무목적에 따라 큐브위성의 자세제어에 용이하게 적용되고 있다. 상기의 자세제어 안정화 방식을 적용한 경우, 큐브위성의 자세 프로파일은 상이하며, 본 논문에서는 각각의 자세제어 방식 적용에 따른 큐브위성의 열적 특성을 궤도 열해석을 통해 분석하였다. 또한, 통신용 안테나 장착 등의 목적으로 태양전지셀이 장착되지 않는 판넬 표면의 상이한 열코팅 적용에 따른 큐브위성의 열적 영향을 분석하였다.

• 한국군사과학기술학회지
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• 제11권3호
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• pp.161-168
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• 2008

The deployable space structure is necessary to minimize the satellite volume and launch cost. For the deployment, passive deployment mechanism has widely been used to attenuate a latch shock induced when the structure is just fully deployed. To reduce the latch shock, viscous damper is applied to the passive deployment mechanism and it can control the deployment speed of the structure. In this paper, dynamic analysis of the deployable space structure using the passive deployment mechanism with the viscous damper has been performed. The viscous damping values have been optimized through numerical simulation. The satellite's attitude influenced by pyro activation for the release of the structure has also been investigated.

• 항공우주시스템공학회지
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• 제7권1호
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• pp.44-49
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• 2013

Passive attitude stabilization method has been widely used for attitude determination and control of cube satellite due to its advantage of system simplicity. In this paper, permanent magnet stabilization method for application of cube satellite attitude control has been introduced and its performance with and without hysteresis damper system has been investigated through a numerical simulation. The simulation results indicate that the permanent magnet stabilization combined with hysteresis damper shows much higher stabilization performance than the system without damper system.

• 항공우주시스템공학회지
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• 제7권3호
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• pp.26-32
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• 2013

Passive attitude stabilization method has been widely usde for attitude determination and control of cube satellite due to its advantage of system simplicity. The permanent magnet installed on the cube satellite passively controls the attitude of the satellite such that the satellite is aligned with the earth magnetic field. In this paper, on-orbit thermal behavior of the cube satellite with the permanent magnet attitude stabilization method has been investigated through on-orbit thermal analysis. THe orbit profile obtained from the aforementioned attitude control method has been reflected in the analysis. The analysis results indicate that the thermal design proposed in this study is effective for satisfying the temperature requirements of the commericial mission equipments.

• International Journal of Aeronautical and Space Sciences
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• 제15권1호
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• pp.82-90
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• 2014

In this paper, the effect of Lorentz force on the stability of attitude orientation of a charged spacecraft moving in an elliptic orbit in the geomagnetic field is considered. Euler equations are used to derive the equations of attitude motion of a charged spacecraft. The equilibrium positions and its stability are investigated separately in the pitch, roll and yaw directions. In each direction, we use the Lorentz force to identify an attitude stabilization parameter. The analytical methods confirm that we can use the Lorentz force as a stabilization method. The charge-to-mass ratio is the main key of control, in addition to the components of the radius vector of the charged center of the spacecraft, relative to the center of mass of the spacecraft. The numerical results determine stable and unstable equilibrium positions. Therefore, in order to generate optimum charge, which may stabilize the attitude motion of a spacecraft, the amount of charge on the surface of spacecraft will need to be monitored for passive control.

• 한국식품영양학회지
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• 제22권2호
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• pp.177-184
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• 2009

The study investigated the eating lifestyles of female consumers and whether they influenced weight control behavior. The findings of the study can be summarized as follows. First, the eating lifestyles of the subjects were presented four types: 'active eating life pursuit type', 'safe economical type', 'gourmet type' and 'passive negligence type'. In general, most cases were of the 'passive negligence type'. Second, weight control behavior was analyzed according to eating lifestyle. The results of the analysis indicated that the female consumers of the 'active eating life pursuit type' and 'safe economy type' had high behavior levels in each aspect of weight control attitude, subjective regulation, perceived behavior control, and behavior intention. Third, the 'gourmet type', with a strong preference for taste, and the 'passive negligence type', with fewer eating considerations in general, showed weaker attitudes towards weight control and the recognition of pressure from people around them. As such, the level of consideration for food or eating was correlated with weight control. These findings impliedy that the more active, safer, and economical women are in their general eating style, the stronger they perceive weight control issues.

• Journal of Astronomy and Space Sciences
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• 제8권1호
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• pp.85-98
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• 1991

지구의 남극과 북극 주위를 저고도로 돌고 있는 소형 과학위성의 자세 조정을 위해 지구자기장을 이용하였다. 이것을 위해 소형 과학위성의 Telemetry 자료를 분석하였다. 위성에 장치된 3축 magnetometer에서 자기장 성분의 크기와 변동량을 측정하여 위성의 회전상태를 알아내는 방법이 제시되었다. 위성이 회전축에 대하여 대칭형인 경우 특정한 위치에서의 자세판단이 가능하다. 현재 자세와 원하는 자세를 비교했을 때 나타나는 차이를 각 축에 대한 회전속도의 조절로 제거할 수 있는 방법을 연구하였다. 여기에서는 자세 측정으로부터 얻은 자료를 가지고 magnetorquer에 공급되어야 할 전류의 크기(혹은 유지시간)를 계산하는 기본 알고리즘을 연구하였고 직접 프로그램으로 작성해서 수행시켜 보았다. 이러한 자세제어 방법은 위성이 초기 tumbling 운동을 할 때와 Gravity gradient boom에 의한 수동제어가 이루어진 후에 적용할 수 있다.

• 한국주거학회논문집
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• 제22권6호
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• pp.31-42
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• 2011

The purpose of the study was to investigate the characteristics of energy use behaviors and energy saving consciousness of multi-family housing residents. The energy referred to in this study includes electric energy, heating energy and water usage. This study was conducted from a survey carried out in Seoul and Gyeonggi-do. The results of the study are as follows: First, among the survey questions, the only positive energy saving behaviors shown by the occupants was turning off the lights and the television, and in the use of kitchen appliances; it could therefore be concluded that, in general, energy saving attitude and consciousness were not sufficient to reduce energy consumption. Second, the results showed high mean scores for the behaviors which were easy to control, such as turning off lights and televisions, and low mean scores for the behaviors which required extra effort to completely cut off electricity energy such as pulling out the plugs of electronic appliances. Third, it was found that the occupants generally showed the tendency to save heating energy. However, in cases where the occupants were required to continuously and directly experience indoor temperatures, they expressed passive attitudes toward saving energy. Fourth, they showed wasteful attitudes toward water usage by leaving the tap running when taking showers and washing their faces. Fifth, while they showed a strong energy saving consciousness, they also showed a passive attitude about putting this into practice; there was therefore some gap between attitude and behavior. Lastly, among the socio-demographic factors, age and family lifecycle were very important factors affecting energy use and energy saving consciousness.

• Journal of Mechanical Science and Technology
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• 제14권8호
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• pp.807-815
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• 2000

In this paper, modified discrete time preview control algorithms for active and semi-active suspension systems are derived based on a simple mathematical 4 DOF half-car model. The discrete time preview control laws for ride comfort are employed in the simulation. The algorithms for MIMO system contain control strategies reacting against body forces that occur at cornering, accelerating, braking, or under payload, in addition to road disturbances. Matlab simulation results for the discrete time case are compared with those for the continuous time case and the appropriateness of the discrete time algorithms are verified by the of simulation results. Passive, active, and semi-active system responses to a sinusoidal input and an asphalt road input are analysed and evaluated. The simulation results show the extent of performance degradation due to numerical errors related to the length of the sampling time and time delay.

• 복식
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• 제48권
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• pp.37-52
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• 1999

The purpose of this study was to find out the clothing-consumption propensity(CCP) and to classify consumption types in CCP and to classify consumption types in CCP and to compare the classfied groups on their consumer characteristics among Korean female X-generation. The survey method was conducted for this study. The subjects are 477 Koran femal X-generation whose age ranges from 18 to 29 and who reside in Seoul and its adjoined areas. The span of the survey was February through March in 1998. the results were analyzed by using of SPSS/PC+package. 1. The clothing consumption motives among the female X-generation were the sensuous satisfaction for posession motive the were practical necessity of the purcahse successively in order. The clothing consumption attitude were the practical electicism the effective value the favorable attitude on low price goods toward sale items and the self-control over their consumption. 2. According to the CCP consumers were classified into five groups: electice and practical group ostentatious and extravagant group passive and economical group sensuous and practical group and sale-fond group. The respective group showed significant difference in the nine factors of the CCP. 3. Consumtion type group had significantly difference in lifestyle among consumer factor and materialistic propensity influence of economic recession follow consumption among social influence factors.