• 한국지능시스템학회논문지
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• 제14권6호
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• pp.726-731
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• 2004

본 논문은 비선형 시스템을 위한 효율적인 펄스 폭 변조 (PWM: pulse-width-modulation) 제어기 설계 기법을 제안한다. 이를 위하여 우선 지능형 디지털 재설계 기법을 사용하여 잘 설계된 아날로그 제어기를 상태 정합(state-matching) 이라는 측면에서 그 제어 성능을 보장하도록 일반적인 펄스 크기 변조(PAM: pulse-amplitude-modulation) 디지털 제어기로 변환한다. 재설계된 지능형 PAM 디지털 제어기는 등가 영역의 원리(equivalent area principle)를 사용하여 PWM 제어기로 변환된다. 제안된 PWM 제어기법의 효용성을 검증하기 위하여 인공위성의 자세제어 시스템의 모의실험의 예를 보인다.

• Journal of Power Electronics
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• 제6권1호
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• pp.18-28
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• 2006

The Electric Power Subsystem (EPS) is one of the most critical systems on any satellite because nearly every subsystem requires power. This makes the choice of power systems the most important task facing satellite designers. The main purpose of the Satellite EPS is to provide continuous, regulated and conditioned power to all the satellite subsystems. It has to withstand radiation, thermal cycling and vacuums in hostile space environments, as well as subsystem degradation over time. The EPS power characteristics are determined by both the parameters of the system itself and by the satellite orbit. After satellite separation from the launch vehicle (LV) to its orbit, in almost all situations, the satellite subsystems (attitude determination and control, communication and onboard computer and data handling (OBC&DH)), take their needed power from a storage battery (SB) and solar arrays (SA) besides the consumed power in the EPS management device. At this point (separation point, detumbling mode), the satellite's angular motion is high and the orientation of the solar arrays, with respect to the Sun, will change in a non-uniform way, so the amount of power generated by the solar arrays will be affected. The objective of this research is to select satellite EPS component types, to estimate solar array illumination parameters and to determine the efficiency of solar arrays during both detumbling and normal operation modes.

• 동아시아식생활학회지
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• 제2권1호
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• pp.69-82
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• 1992

The purpose of this study is to analyze the cooker's regnition and real attitude abut standard cost system who are engazing in hotel restaurants in Seoul area. The sample was consisted of 307 cookers(male ; 82.7%, female ; 17.3%_ and the used method in analyzing is surveying method and statistical analysis(SPSS PC Package ; Version 3.0). The results of this study are summarized as follows ; 1. Standard cost system, mass purchase and proper recipe were presented in order to economize on real cost and the purchase and preservation of food were presented as important control factor to econimize cost. 2. Most coolers were recognizing the necessity of standard cost system and they relyed the purpose of standard cost calculation on standard cost control. They also thought standard cost accounting information system as good method to economize cost and they were favorable abut the usage of computer in improving working ability. 3. Most of cookers(80%) wanted to be independant restaurant manager and they were favorable Korean restaurant and Western restaurant. 4. The cookers represented the oder of importance by nutrition, preferance of food, economy in composing cooking menu and by taste, odor, variety, decoration in cooking.

• 정보교육학회논문지
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• 제18권4호
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• pp.521-528
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• 2014

오늘날 학생들의 스마트폰 보급률이 높아졌다고는 하나 대부분은 채팅, 게임용으로 사용하고 있는 현실에서 스마트기기를 이용한 학습 방법을 탐구해보고자 하는 의도로 본 연구에서는 '스마트기기를 이용한 웹 2.0 환경에서의 협동학습이 학습자의 학업성취도와 자기 주도적 학습 태도에 미치는 영향'에 대해 초등학교 5학년 사회과를 바탕으로 실험 집단은 스마트기기를 이용한 구글 드라이브의 문서 작성 기능을 활용하여 협동학습을, 통제집단은 전통적 일제 수업을 실시하였다. 총 7주간 실험하고 그 결과를 분석한 결과 실험집단이 통제집단보다 학업 성취도 및 학습 태도의 한 영역인 자기 주도적 학습 태도가 더 신장되었다. 이를 통해 스마트기기를 이용한 웹 2.0 환경의 협동학습이 학습자의 학업 성취와 자기 주도적 학습 태도 신장에 효과적임을 알 수 있다.

• 대한기계학회논문집A
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• 제40권4호
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• pp.343-352
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• 2016

멀티로터 비행체는 여러 개의 로터로 이루어진 무인 비행로봇으로서, 로터의 개수에 따라서 트라이로터, 쿼드로터, 헥사로터, 옥토로터 등으로 나누어 진다. 멀티로터는 수직이착륙 및 정지비행과 같은 높은 기동성으로 인하여 다른 무인 비행로봇에 비하여 험준한 산학지역 및 건물이 밀집되어 있는 도심과 같은 지역의 정찰 및 감시 등 여러 응용분야에 유용하게 활용될 수 있다. 하지만, 멀티로터는 불확실한 외부 환경 및 외란의 영향에 쉽게 노출될 수 있어 강건한 자세 및 비행제어 기법의 적용을 필요로 한다. 본 논문에서는 강인제어기법 중 하나인 슬라이딩 모드제어기를 설계 및 임베디드 알고리듬을 구현을 통하여 실시간 실내 비행실험을 위한 시스템을 구성하고, 실시간 위치제어 및 자세 안정화에 대한 실내 비행실험을 수행하였다. 특히, 불확실한 외부환경에 대한 강건한 비행특성을 검증하기 위하여 외란을 삽입하여 비행시험을 통해 성능을 검증하였다.

• 한국산학기술학회논문지
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• 제11권2호
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• pp.414-419
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• 2010

본 논문은 호버링 무인잠수정 'NOAH'의 설계과정을 언급하였고 그 성능을 확인하기 위한 수학모델을 정립하고 실험을 실시하였다. 시뮬레이션과 수조실험을 통해 성능을 검증하였으며, 무인잠수정 NOAH의 설계목표인 자세 및 위치제어를 위한 기본실험을 실시하였다. 설계된 무인잠수정은 일반적인 ROV형태의 외형을 갖고 있으며, 이러한 외형은 NOAH의 제작목적에 따라 다양한 장비를 설치하여 실험하기가 용이하며 크기는 $0.75m{\times}0.5m{\times}0.5m$이다. 추진을 위한 450watt의 용량을 갖는 4개의 추진기가 주행방향, 횡방향, 수직방향으로 설치되어져 있고 수심을 측정하기 위한 압력센서와 방향각을 측정하기 위한 자력컴파스가 설치되었다. 잠수정의 주행을 제어하기 위해 펜티엄 III의 소형 온보드 컴퓨터에 운영체제는 윈도우 XP를 탑재하였다. 제작된 호버링 무인잠수정 NOAH는 다양한 환경에서 여러 가지 제어알고리즘을 적용하여 성능을 개선하고 실험을 하기 위한 테스트베드로 운영된다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.1386-1391
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• 2004

It is known that an aircraft with delta-wings which are attached to the body at a large angle like a kite or a hang glider has a measure of maneuverability and stability. Aircrafts of this kind can fly stably. Even if engine trouble occurs, it will not fall and might be able to land. In this paper, one of the conventional control methods, PID control, is applied to the aircraft with LQ local control block. This is based on an idea that the aircraft flies so stably that the automatic control system might be realized by a simple controller. The proposed PID controller consists of several sub-controllers which are constructed to each system neglecting the interference. In addition, the LQ control is involved as a local loop of the aileron and rudder control in order to increase stability of the attitude when circling. The effectiveness of the proposed method is shown through 3D computer simulations and experiments of the flight path control.

• 한국가정과학회지
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• 제4권2호
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• pp.94-109
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• 2001

The purpose of this study was to explore dietary attitude among middle school students by sex. The subjects were collected from 211 boy students and 198 girl students in the city of Kunsan, Jeonbuk province. The mean age of the subjects was 13.7 years old. The average score of food habit was 4.61 $\pm$ 1.92. The average score of food habit of boy students was higher than the score of girl students. The correlations between the score of food habit and father's education level. family income, and nutritional supplements were positive. The correlation between the scores of the nutrition knowledge and father's education level was also positive. On the other hand the mother's occupation did not have any influence on the scores of food habits and the scores of the nutrition knowledge. As a staple food, cooked rice was preferred on boy and girl students at breakfast(82.7%) and supper(94.3%). The preference of snacks was fruit and fruit juice. The reason of skipping breakfast was the lack of time and no appetite, and skipping lunch was due to no appetite. Lastly the main reason of skipping supper was playing computer on boys. on the other hand no appetite and weight control on girls. In order to improve the nutritional status of the middle school students, they must establish good food habits by eating three regular meals per day and balancing their diet. Also they should be notified that severe weight control is very harmful for health. This study indicate that nutrition education and correct information for body image. balanced diet. regularity of meals and food selection are required for middle school students at both school and home.

• 한국간호교육학회지
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• 제9권2호
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• pp.264-275
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• 2003

The purpose of this study were to develop a smoking preventive education program for elementary students and evaluate it's effectiveness. This study was a quasi experimental study under the nonequivalent control group with pretest-posttest design. The subjects of this study were 62 who are attending elementary school(31 for each group), 2 different district elementary school. The subjects were matched by grade, similar in anti-smoking educational background of smoking, as well as their residence and income level of their families. The instruments used in this study was 18 criterion referenced test items modeled by Dick & Carey that were developed by researchers for evaluating the subjects' knowledge and attitude about smoking. A pretest was administered a week before treatment The program given to the experimental group is composed of the texts explaining the poisonous substances in tobacco, social and cultural harmfulness of smoking to the body and psychology, indirect smoking, smoking of pregnant women, motives of smoking, refusal skills of smoking; and for the subjects' understanding and the better results of study - pictures, role play, discussion, text through computer based multi-media, puzzle searching for hidden pictures, cross-word puzzle, and finally compensation. The data were collected for 50 days form mid- September to the end of October in the year of 2000, composed of formative evaluation, pre-test and summative evaluation via 2 sessions. Accordingly, the collected data were analysed by t-test, paired t-test, repeated measure ANOVA by the SAS program. This research summarize the findings as follows; 1. There was a significant difference in knowledge between the experimental group(after 1 wks t=10.4680, p=.0001; after 4 wks t= 9.310, p=.0001) and control group(after 1 wks t=0.0420, p= .9669; after 4 wks t= -0.378 p=.7079) in between the results of 1 and 4 week after education in summative evaluation (F=27.45, P=.0001). 2. There was non statistical significant difference in attitude between the experimental group (after 1 wks t=1.2292, p=0.2286 ; after 4 wks t=1.330, p=0.1935) and control group (after 1 wks t=0.1819, p=0.8569 ; after 4 wks t=0.2970, p=0.7685) in between the results of 1 and 4 week after education in summative evaluation(F=0.71, P=0.494). To sum up, the statistics of conclusive analysis evaluative for the children under school age of the 'knowledge acquisition' about smoking harmfulness. On the other hand, as there was already sound attitude about smoking, the evaluation of attitude was non significant difference between control group and experimental group, just there was partially significant difference.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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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.