• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집A
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• pp.584-589
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• 2000

When the liquid tanks only partially filled and under translational acceleration, large quantities of liquid move uncontrollably inside the tanks and generate the liquid sloshing effect. Liquid sloshing effect could be a severe problem in launch vehicle stability and control if the liquid modes of motion couple significantly with the launch vehicle's normal modes of motion. Several methods have been employed to reduce the effect of sloshing, such as introducing baffles inside the tanks or dividing a large tank into a number of smaller ones. These techniques, although helpful in some cases, do not succeed in canceling the sloshing effects. In this paper, An attitude controller is designed for a launch vehicle with liquid sloshing effect. Both PD controller and sloshing filter are designed for the objective. PD gains and design parameters are determined by optimal algorithm. The performance of the attitude controller is evaluated via computer simulations.

• International Journal of Aeronautical and Space Sciences
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• 제14권1호
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• pp.58-66
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• 2013

This paper addresses the performance of three different types of attitude control systems for the Quad-rotor UAV to perform the flip maneuver. For this purpose, Quad-rotor UAV's 6-DOF dynamic model is derived, and it was used for designing an attitude controller of the Quad-rotor UAV. Attitude controllers are designed by three different methods. One is the open-loop control system design, another is the PD control system design, and the last method is the sliding mode control system design. Performances of all controllers are tested by 6-DOF simulation. In case of the open-loop control system, control inputs are calculated by the quad-rotor dynamic model and thrust system model that are identified by the thrust test. The 6-DOF realtime simulation environment was constructed in order to verify the performances of attitude controllers.

• 대한기계학회논문집A
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• 제39권5호
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• pp.517-526
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• 2015

본 논문은 쿼드로터 자세제어의 신뢰성 향상을 목적으로 다종 센서 구성 및 다종 센서 데이터 융합 알고리즘 적용을 연구한 결과이다. 먼저, 쿼드로터에 대한 동역학적 모델링에 관한 수식을 도출하였으며, 획득된 수식을 기초로 쿼드로터에 대한 수학적 모델링을 진행하였고 이를 기반으로 신뢰성이 향상된 다종 센서 데이터를 입력으로 하는 컴퓨터 시뮬레이션을 수행하였다. 쿼드로터 자세제어를 위해 다종 센서 데이터의 신뢰성 향상이 필요했으며 이를 위해 다종 센서 데이터 입력에 대한 칼만 필터링를 진행하였고, 이후 쿼드로터의 수학적 모델링에 적용하여 오차를 보상토록 하였다. 관련 컴퓨터 시뮬레이션 결과를 실제 쿼드로터 시스템에 적용하기 위하여 쿼드로터를 짐벌에 장착한 실제 시스템을 구성하였고 이후 쿼드로터를 호버링 상태에서 사용자가 요구하는 각도 변화에 따른 실험을 수행하였다. 실제 실험을 통한 쿼드로터 자세제어 데이터를 산출하였으며, 이를 바탕으로 추가적인 컴퓨터 시뮬레이션을 통한 설계한 다종 센서 및 쿼드로터 자세 제어 시스템의 성능 검증을 진행하였다.

• Journal of Astronomy and Space Sciences
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• 제26권1호
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• pp.31-46
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• 2009

An Unscented Kalman Filter (UKF) for estimation of the attitude and rate of a spacecraft using only magnetometer vector measurement is developed. The attitude dynamics used in the estimation is the nonlinear Euler's rotational equation which is augmented with the quaternion kinematics to construct a process model. The filter is designed for small satellite in low Earth orbit, so the disturbance torques include gravity-gradient torque, magnetic disturbance torque, and aerodynamic drag torque. The magnetometer measurements are simulated based on time-varying position of the spacecraft. The filter has been tested not only in the standby mode but also in the detumbling mode. Two types of actuators have been modeled and applied in the simulation. The PD controller is used for the two types of actuators (reaction wheels and thrusters) to detumble the spacecraft. The estimation error converged to within 5 deg for attitude and 0.1 deg/s for rate respectively when the two types of actuators were used. A joint state parameter estimation has been tested and the effect of the process noise covariance on the parameter estimation has been indicated. Also, Monte-Carlo simulations have been performed to test the capability of the filter to converge with the initial conditions sampled from a uniform distribution. Finally, the UKF performance has been compared to that of the EKF and it demonstrates that UKF slightly outperforms EKF. The developed algorithm can be applied to any type of small satellites that are actuated by magnetic torquers, reaction wheels or thrusters with a capability of magnetometer vector measurements for attitude and rate estimation.

• 대한지역사회영양학회지
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• 제3권2호
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• pp.317-328
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• 1998

In order to investigate if nutrition-related TV programs give the public correct and useful imformation, 26 producers(PD) having worked for any one of the nutirtion-related TV programs were surveyed by using questionnaire on the attitudes toward seeking an expert's advice about the issues and the panelist's constitution of one typical nutrition-related TV show program broadcasted during the last 5 years was analyzed. The most important reason for selecting the nutrition-related issues was to satisfy the interests and demands of audiences. Both being motivated by food-related accidents and to educate people for the health promotion were the second ones. In the process of nutrition-related program production, 53.9% of PDs always requested expert's advice, while 46.1% occasionally did. Professors in food and nutrition were regarded as the most proper advisor. Dietitians, physicians and physicians of Chinese medicine wer the next in order. The similar pattern were shown in the rankd of specialists actually invited as panelists to the program. Both the speciality and being well-known were less positive and favorable for participating in the program compared to experts in other areas. The number of programs about food and nutrition broadcasted on the TV show during 1993-1997(July) was 361(about 30%). The total of 1,043 specialists appeared, 2.9 persons per program on the average. Of these, only 12.9% were professors in food and nutrition as well as dietitians. The largest(20.2%) was physicians or medical professors, and 13.6% cooks and 12.6% physicians of Chinese medicine. Of 361 programs 45 were thought to be undesirable on the panelist constitution. Particualrly in 19 programs, where nutritionists were not invited, physicians or physicians of Chinese medicine explained diet therapy, food, nutrient or dietary habit.

• 대한건축학회논문집:계획계
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• 제35권1호
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• pp.107-115
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• 2019

This research explores a historical trajectory of the Milwaukee Art Museum from its establishment to the third expansion over the last six decades. After established in 1957 by the architect, Eero Saarinen, this museum underwent three expansions led by three different architects including, David Kahler, Santiago Calatrava, and James Shields. Reasons for expanding the museum were varied. A lack of exhibition space, an absence of visual identity, and path interruption problem within urban contexts were the main factors of a series of expansion. Furthermore, this research points out that there are three issues in the process of the expansion. The first is connection issues between the downtown and the lakefront in which the museum has blocked the public flow. The second, there were controversies on the allocation of the expanded space among the main body of the decision including architects, curators, and stakeholders. The last one is relationships among architects. This is related to each architect's attitude toward the museum. Drawing on historical documents and interviews with the regional architects, I argue that the identity and values of the museum have changed over time through the expansions rather than having the invariable.

• 대한건축학회논문집:계획계
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• 제36권3호
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• pp.31-38
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• 2020

The purpose of this study is to compare between professionalism in medical field(doctor) and architectural design field(architect) in Korea through synchronic and diachronic analysis, with basic requirement of expertise and systemicity, attitude requirement of the publicness, and structural requirement of exclusiveness and autonomy. The medical professionalism adapted by Korean government in the early period of modernization evolved from Western's professional expertise is highly divided as economy grew and society changed. In comparison, architecture was divided into architecture, urbanism, landscape, and interior architecture. Additionally, architectural field was subdivided with architectural design, engineering, construction, structure, and facilities, but architectural design focused on generalized education and practice system. From the systematical point of view, architectural design field has changed profoundly from architectural engineering as 5 year undergraduate educational system was introduced with Korean architectural accreditation. The publicness is approved through health service in medical field and safety and the public domain in architectural design field, but in reality the professionals are viewed as economic interest groups. Hence, the professionalism in both fields is required to reinforce ideology and ethics, and to practice concrete measures for publicness. Compared with the unified organization of medical field, architectural design professionalism faces various difficulties in unifying the organization, such as internal competition caused by tightened architect's requirements, along with external problems from architectural design permission demands of construction companies. In medical and architectural design professionalism, with the appearance of consumerism and stricter governmental regulations, the autonomy is weakened. From the result of comparative analysis, Korean medical field became extremely subdivided and specialized in each department, therefore integration of each disease and establishment of centers are proposed as solutions. By contrast, the reinforcement of expertise in architectural design professionalism might be necessary to strengthen autonomy caused by governmental restriction, and to form architectural culture and secure public architecture.