• Journal of the Korea Institute of Military Science and Technology
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• v.26 no.3
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• pp.214-226
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• 2023

A transfer alignment is used to initialize, align, and calibrate a SINS(Slave INS) using a MINS(Master INS) in motion. This paper presents an airborne transfer alignment with velocity and azimuth matching to estimate inertial sensor biases under the wing flexure influence. This study also considers the lever arm, time delay and relative orientation between MINS and SINS. The traditional transfer alignment only uses velocity matching. In contrast, this paper utilizes the azimuth matching to prevent divergence of the azimuth when the aircraft is stationary or quasi-stationary since the azimuth is less affected by the wing flexibility. The performance of the proposed Kalman filter is analyzed using two factors; one is the estimation performance of gyroscope and accelerometer bias and the other is comparing aircraft dynamics and attitude covariance. The performance of the proposed filter is verified using a long term flight test. The test results show that the proposed scheme can be effectively applied to various platforms that require airborne transfer alignment.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.519-524
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• 2003

In this report, a longitudinal adaptive flight control law is presented for the automatic landing system of a Japanese automatic landing flight experiment vehicle (ALFLEX). The longitudinal adaptive flight control law is designed to track an output of the vehicle to a guidance signal from the guidance portion of the automatic landing system. The proposed adaptive control law in the attitude control portion adjusts the controller gains continuously online as flight conditions change, in spite of the existence of unmodeled dynamics. The number of the controller gains to be adjusted is decreased to 1/2 from the previous studies. Computer simulation involving six-degree-of-freedom (DOF) nonlinear flight dynamics is performed to examine the effectiveness of the proposed adaptive control law. In order to verify the influence of the dispersion of the initial conditions, the Monte Carlo simulation is also applied. The initial conditions are more widely dispersed than the previous studies. As a result, except under the unsuitable initial conditions, the ALFLEX successfully landed on the runway.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.12
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• pp.1059-1068
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• 2017

Space exploration spacecraft carry large amounts of liquid fuel, often more than half. In such cases, the liquid fuel sloshing must be considered in the design of the spacecraft since the sloshing can affects the stability of the spacecraft. In this paper, we present the results of analyzing the sloshing of fuel and the dynamic behavior of the spacecraft. For the purpose, a model in which the maneuvering of the spacecraft causes the sloshing and a model in which the reaction force and moment due to the sloshing are transmitted to the spacecraft are developed. The dynamical behavior of the spacecraft are analyzed using a simulation program coded by Modelica.

• Korean Journal of Construction Engineering and Management
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• v.18 no.2
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• pp.38-48
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• 2017

Finding causes of workers' unsafe behaviors is important to prevent construction accidents because 80 percent of accidents occur by workers' unsafe behaviors. In this regard, this research aims to investigate possible reasons of workers' unsafe behaviors based on workers' cognitive process model using System dynamics. This study is based on two ways of workers' cognitive process which are in relation to hazard perception and failure of hazard perception. Based on existing literature, causal loops for workers' cognitive process are developed to explain workers' habituation by staying out of accidents, safety learning by experience, failure of hazard perception, and attitude change by accidents. The interactions between the developed loops provide managerial insights to reduce workers' unsafe behaviors from a safety manager's perspective including increasing the probability of workers' hazard perception through knowledge management, maintaining workers' positive attitude toward safety, and controlling first-line supervisors to eliminate workers' unsafe behavior. The research allows us to better understand the causes and solutions of workers' unsafe behaviors in workers' cognitive perspectives.

• Journal of Astronomy and Space Sciences
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• v.33 no.4
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• pp.323-333
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• 2016

In this study, the uncertainty requirements for orbit, attitude, and burn performance were estimated and analyzed for the execution of the $1^{st}$ lunar orbit insertion (LOI) maneuver of the Korea Pathfinder Lunar Orbiter (KPLO) mission. During the early design phase of the system, associate analysis is an essential design factor as the $1^{st}$ LOI maneuver is the largest burn that utilizes the onboard propulsion system; the success of the lunar capture is directly affected by the performance achieved. For the analysis, the spacecraft is assumed to have already approached the periselene with a hyperbolic arrival trajectory around the moon. In addition, diverse arrival conditions and mission constraints were considered, such as varying periselene approach velocity, altitude, and orbital period of the capture orbit after execution of the $1^{st}$ LOI maneuver. The current analysis assumed an impulsive LOI maneuver, and two-body equations of motion were adapted to simplify the problem for a preliminary analysis. Monte Carlo simulations were performed for the statistical analysis to analyze diverse uncertainties that might arise at the moment when the maneuver is executed. As a result, three major requirements were analyzed and estimated for the early design phase. First, the minimum requirements were estimated for the burn performance to be captured around the moon. Second, the requirements for orbit, attitude, and maneuver burn performances were simultaneously estimated and analyzed to maintain the $1^{st}$ elliptical orbit achieved around the moon within the specified orbital period. Finally, the dispersion requirements on the B-plane aiming at target points to meet the target insertion goal were analyzed and can be utilized as reference target guidelines for a mid-course correction (MCC) maneuver during the transfer. More detailed system requirements for the KPLO mission, particularly for the spacecraft bus itself and for the flight dynamics subsystem at the ground control center, are expected to be prepared and established based on the current results, including a contingency trajectory design plan.

• Journal of the Korean Society of School Health
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• v.13 no.1
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• pp.85-96
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• 2000

This study was conducted to examine the effect of family environment on smoking behavior, smoking knowledge and smoking attitude in primary school students. For the purpose of the study, a questionnaire-based examination was made with 1,476 sixth-grade students in Taegu from November 1st to 30th, 1998. The results of the study are summarized as follows. Out of 22 points for smoking knowledge, the male student group got 12.9 points, and the female student group 13.0 points. For both groups, students with better school achievement showed a significantly higher score (p<0.01). For the female student group, those who had nonsmoking fathers showed a significantly higher score(p<0.05). A perfect score for smoking attitude was 20 points. The male student group received 14.9 points and the female student group 16.3. For both groups, the score appeared to be significantly higher in the students who had better school achievement and no smoking experience. For the female group, the score was higher if they were living with widowed mothers or had nonsmoking parents. The percentage of smoking experience was 22.0% for the male group and 4.7% for the female group. The present smoking percentage of both groups accounted for 0.3% and 0.1%, respectively. The percentage of the male group's smoking experience was significantly higher if school achievement was poor, if the mother has religious, and if her occupation belonged to significantly different category. For the female group, it was significantly higher if a mother's educational background was less than the primary school level, or if a mother smokes. Family adaptability and cohesion were not significant variables for both groups. The score for smoking knowledge according to family cohesion was highest if male and female members were in an enmeshed state. For the female group, the higher the family adaptability, the significantly higher the score for smoking knowledge. The score for smoking attitude according to family cohesion showed a significant difference for both groups. The family adaptability was not a significant variable for both groups. The results of multiple regression analysis, with the scores for smoking knowledge and smoking attitude were used as a dependent variable, revealed that, for both groups, the better the school achievement. For the female group, the higher the family cohesion, the significantly higher the score(p<0.01). For the male group, the score for smoking attitude was significant1y higher if school achievement was better, if students were living with a widowed mother or father, if they had drinking mothers, if family adaptability was low, if family cohesion was high, or if the score for smoking knowledge was high. For the female group, the score for smoking attitude was higher if school achievement was better. Also, if famale student had nonsmoking fathers, if the family adaptability was lower, on the higher the score for smoking knowledge, a smoking attitude scored higher. The results of a multiple logistic analysis, with smoking experience as a dependent variable, revealed that, for the male student group, the worse the school achievement, the higher the score for smoking knowledge, the lower the score for smoking attitude, or the lower the family adaptability, the higher the percentage of smoking experience. For the female student group, the higher the score for smoking knowledge or the lower the score for smoking attitude, the higher the percentage of smoking experience. In conclusion, family environment, including smoking of parents and family functions, had a great effect on smoking knowledge, smoking attitude and smoking experience of students, and it is required to adjust subjects and methods for smoking and nonsmoking education as smoking attitude and smoking behavior greatly differ according to sex.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.969-974
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• 2004

For a maneuvering unmanned autonomous helicopter, it is necessary to design a proper controller of each flight mode. In this paper, overall helicopter dynamics is derived and hovering model is linearized and transformed into a state equation form. However, since it is difficult to obtain parameters of stability derivatives in the state equation directly, a linear control model is derived by time-domain parametric system identification method with real flight data of the model helicopter. Then, two different controllers - a linear feedback controller with proportional gains and a robust controller - are designed and their performance is compared. Both proposed controllers show outstanding results by computer simulation. These validated controllers can be used to autonomous flight controller of a real unmanned model helicopter.

• Journal of Advanced Research in Ocean Engineering
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• v.3 no.1
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• pp.25-31
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• 2017

Generally, underwater gliders do not have separate propellers for their forward movement. They derive a propulsive force due to the difference between their buoyancy and gravity. The attitude of an underwater glider is controlled by changing the relative position of the buoyancy center and mass center. In this study, we derived nonlinear 6-DOF dynamic and mathematical models for the motion controller and buoyancy controller. Using these equations, we performed dynamic underwater glider simulations and verified the suitability of the design and dynamic performance of the proposed underwater glider.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.13 no.2
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• pp.14-26
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• 2005

A tilt-rotor aircraft has various flight modes : helicopter, airplane, and conversion. Each of flight mode has unique and nonlinear flight characteristics. Therefore the gain schedules for whole flight envelope are required for effective flight performance. This paper proposes collective, flap, and nacelle angle scheduler for whole flight envelope of the Smart UAV(Unmanned Air Vehicle) based on CAMRAD(Comprehensive Analytical Model of Rotorcraft Aerodynamics and Dynamics) II analysis results. The scheduler designs are improved so that the pitch attitude angle of helicopter mode was minimized. The range of scheduler are reduced inside of engine performance limits. The conversion corridor and rotor governor are suggested also.

• Korean Institute of Interior Design Journal
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• v.17 no.1
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• pp.93-101
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• 2008

One of the big difference between Aalto and other modem architects lies in an attitude that Aalto went beyond the principle of dogmatic functionalism. As an architect of Northern Europe, Aalto made unique architecture that showed both the language of modem architecture and vernacular architecture. He presented the best example which showed modernity in architecture without losing the meaning of the context including site, region and cultural tradition. With this background, Aalto developed his own typological design approach. As Wolfsburg church was designed in his prime of time, it showed the origin and evolutionary process of religious architecture as well as general features of Aalto's design. Clustered site plan, dynamic space of interior, the adequate control of natural light are representative characteristics found in Aalto's religious architecture. Wolfsburg church also demonstrate these features in more specific way including the continuity of wall and ceiling that showed spatial dynamics, free opening of wall which reflects on functions, and careful adjust of natural light. As a result, Aalto showed his typological design strategy that added new design ideas to the accumulated design vocabularies in the design of Wolfsburg church.