• Title/Summary/Keyword: Attitude Control System

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EFL College Students' Learning Experiences during Film-based Reading Class: Focused on the Analysis of Students' Reflective Journals

  • Baek, Jiyeon
    • International Journal of Advanced Culture Technology
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    • v.7 no.4
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    • pp.49-55
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    • 2019
  • In the age of information, newly produced knowledge is mostly written in English. Therefore, there has been a strong demand for English language learning in the EFL context. However, most EFL learners possess a lack of interest and motivation in the text-based reading class. In this educational context, film is one of the most widely used materials in English reading classes considering that modern learners are predominantly familiar with various audiovisual materials. The purpose of this study is to investigate how Korean EFL learners experienced in the film-based reading class. Specifically, this study aims to analyze the EFL students' perceptions about the class and learning strategies that they used during the class. In order to comprehensively interpret the EFL learners' experiences in the classroom, a coding system consisting of five categories was developed: report, emotion, reflection, evaluation, future plans. The results of data analysis showed that the use of movies in English reading classes had positive effects on reading comprehension and inference of word meaning. The most frequently used learning strategies were affective strategies which helped them control their emotion, attitude, motivations and values, whereas memorization strategies were rarely used. In this respect, this study suggests that the use of movies in the EFL reading classroom encourage students' attention and help them obtain and activate schema which is useful in gaining a better understanding of text-based reading materials.

Study on Optimization of Propellant Shape with Two-side Burning Surface for Continuous Variable Thruster (연속가변형 추력기용 이면연소 추진제 형상 최적화 연구)

  • Heo, Junyoung;Park, Iksoo;Jin, Jungkun
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2017.05a
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    • pp.364-367
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    • 2017
  • The basic design concept of the DACS(Divert and Attitude Control System) propellant is presented and the geometry optimization of the DACS propellant with limited outer diameter and maximum burning rate of the propellant is performed. Two-side burning surface conditions burned at the core and the one side of the propellant are applied to the propellant. And the optimized values for the radius of core, length of propellant, angle of end-side surface are obtained by the PSO algorithm. The direction for DACS propellant design is suggested by analyzing optimized design points for various burning rate.

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Development Status of the SPICA/FPC

  • Pyo, Jeonghyun;Jeong, Woong-Seob;Lee, Dae-Hee;Matsumoto, Toshio;Moon, Bongkon;Tsumura, Kohji;Park, Kwijong;Park, Sung-Joon;Park, Youngsik;Kim, Il-Jung;Park, Won-Kee;Han, Wonyong;Im, Myungshin;Lee, Hyung Mok;Lee, Jeong-Eun
    • The Bulletin of The Korean Astronomical Society
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    • v.38 no.2
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    • pp.82.1-82.1
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    • 2013
  • The SPICA (SPace Infrared Telescope for Cosmology & Astrophysics) project is a next-generation infrared space telescope optimized for mid- and far-infrared observation with a cryogenically cooled 3m-class telescope. Owing to unprecedented sensitivity and high spatial resolution, the focal plane instruments are expected to perform the confusion-limited observation. The SPICA will challenge to reveal many astronomical key issues from the star-formation history of the universe to the planetary formation. The Korean 5contribution to SPICA as an international collaboration is the development of the near-infrared instrument, FPC (Focal Plane Camera). The Korean consortium for FPC proposed a key system instrument for the purpose of a fine guiding (FPC-G) complementing the AOCS (Attitude and Orbit Control System). The back-up instrument of FPC-G, FPC-S will be responsible for the scientific observations as well. Through the international review process, we have revised the scientific programs and made the feasibility study for the fine guiding system. Here, we report the current status of SPICA/FPC project.

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On-orbit Analysis of Power Generation Efficiency of Concentrating Photovoltaic System Using Commercial Fresnel Lens for Pico Satellite Applications (상용 프레넬렌즈를 이용한 극초소형 위성용 집광형 태양전력 시스템의 궤도 전력생성효율 분석)

  • Park, Tae-Yong;Chae, Bong-Geon;Oh, Hyun-Ung
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.43 no.4
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    • pp.318-325
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    • 2015
  • Pico satellite has limited surface to install the solar cells due to its extremely limited size. Also, the sun incidence angle with respect to the solar panel continuously varies according to the attitude control strategy and its important parameter for the power generation. In this study, a concentrating photovoltaic system for pico satellite application has been proposed that can enhance the power generation efficiency in case of the unfavorable condition of the sun incidence angle with respect to the solar panel of the satellite using the fresnel lens. To prove the possibility of maximizing the power generation efficiency of the proposed concentrating power system, we have performed the power measurement test using a solar simulator and commercial fresnel lens. And on-orbit analysis of the power generation efficiency using the STK which is a commercial S/W has also been performed based on the test results.

System Design of SIGMA(KHUSAT-3) CubeSat Mission

  • Lee, Seongwhan;Lee, Junkyu;Kum, Kanghoon;Lee, Hyojeong;Seo, Junwon;Shin, Youra;Jeong, Seonyoung;Shin, Jehyuck;Cheon, Junghoon;Kim, Hanjun;Jin, Ho;Nam, Uk-Won;Kim, Sunghwan;Lee, Regina;Lessard, Marc R.
    • The Bulletin of The Korean Astronomical Society
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    • v.39 no.1
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    • pp.54.1-54.1
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    • 2014
  • Kyung Hee University has been developing a CubeSat for the space science mission called SIGMA (Scientific cubesat with Instrument for Global Magnetic field and rAdiation), which includes TEPC (Tissue Equivalent Proportional Counter) and a magnetometer. SIGMA has a 3-unit CubeSat, and the weight is about 3.2 kg. The main payload is TEPC which can measure the Linear Energy Transfer (LET) spectrum and calculate the equivalent dose for the complicated radiation field in the space. The magnetometer is a secondary payload using a miniaturized fluxgate magnetometer. We expect it to have a 1 nT resolution in the dynamic range of ${\pm}65535$ nT. An Attitude Control System (ACS) spins the SIGMA spacecraft 4 rpm with the spin axis perpendicular to the ecliptic plane. Full duplex communication is consists of VHF uplink and S-band and UHF downlink. In this paper, we introduce the system design and the scientific purpose of the SIGMA CubeSat mission.

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Analysis Model for Design Based on Stiffness Requirement of Direct Drive Electromechanical Actuator (직구동 전기기계식 구동기의 강성요구규격에 기반한 설계용 해석모델)

  • Oh, Sang Gwan;Lee, Hee Joong;Park, Hyun Jong;Oh, Dongho
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.47 no.10
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    • pp.738-746
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    • 2019
  • Instead of hydraulic actuation systems, an electromechanical actuation system is more efficient in terms of weight, cost, and test evaluation in the thrust vector control of the 7-ton gimbal engine used in the Korea Space Launch Vehicle-II(KSLV-II) $3^{rd}$ stage. The electromechanical actuator is a kind of servo actuator with position feedback and uses a BLDC motor that can operate at high vacuum. In the case of the gimballed rocket engine, a synthetic resonance phenomenon may occur due to a combination of a vibration mode of the actuator itself, a bending mode of the launcher structure, and an inertial load of the gimbals engine. When the synthetic resonance occurs, the control of the rocket attitude becomes unstable. Therefore, the requirements for the stiffness have been applied in consideration of the gimbal engine characteristics, the support structure, and the actuating system. For the 7-ton gimbal engine of the KSLV-II $3^{rd}$ stage, the stiffness requirement of the actuation system is $3.94{\times}10^7N/m$, and the direct drive type electromechanical actuator is designed to satisfy this requirement. In this paper, an equivalent stiffness analysis model of a direct drive electromechanical actuator designed based on the stiffness requirements is proposed and verified by experimental results.

Dynamic Developmental Factors and their Problem Solving of Patients that Abuse Marihuana (마리화나 남용환자의 역동적인 발달요인과 문제해결)

  • 원정숙
    • Journal of Korean Academy of Nursing
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    • v.4 no.3
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    • pp.105-116
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    • 1974
  • This study was made on patients who were Hospitalized due to sickness caused by the abuse of marihuana at the Psychiatric Section of a hospital during the period from Feb. to Oct., 1974. The following conclusion was obtained by reviewing the literature with respect to the nursing, and problem solving of those patients. 1. It appears that marihuana is a comparatively mild intoxicant in ordinary preparation without causing physical dependence or tolerance. 2. According to the status of men who are marihuana smokers, approximately 20% of them were college students, those preparing to retake college entrance examinations, non-employed and pharmacists. The men belong mostly to the middle foreigner′s mistress of higher, income bracket, and in the case of women, most of the smokers were US. servicemen entertainers. 3. Dynamic developmental factors: Case 1. : The patient had a characteristic, hysterical and emotionally unitable character, and was of low intelligence, In addition, to this already existing problem, the added uses of marihuana caused a mental illness to develope. Case 2 : The character, was reserved and introspective, her creative power and sentiment was fading and his ability of self-control was weakened. She used the smoking of marihuana to get rid of her own feeling of inferiority complex and tensions coming from interpersonal relationships. Case 3 : The patient was unconditionally resistive to the authoritativeness of superiors and irresponsible in his relationship with women, in his attitude concerning sex in general. He smoked marihuana because he felt become peace-loving and get enchanted experience through smoking it. 4. The points of issue appearing from the above case; (1) Movement of anti-social feelings against the "established system" by the youngsters. (2) Family problem. (3) Shamelessness, loss of motivation, disorderly attitude toward the sex, (4) Worries concerning the future. (5) Lack of knowledge concerning smoking of cigarette and marihuana. Chronic use of marihuana made, those youngman who had originally been ambitions to achieve something in life, lazy, inefficient, unable to make long-term plans, are such weak mined persons that they did not try to overcome problems when encountered. This will pose a great and important question in the mental health of the society, 5. Treatment and Problem sieving According to the literature, we will have to place importance upon hospitalized treatment The phases of treatment were divided into five parts. (1) Prehospital phase (2) Withdrawal Phase (3) Rehabilitation phase (4) Transitional phase (5) After-care phase The experiments have proved that there was much progress in the recovery of patients through environment therapy, supportive therapy and group psychotherapy. This was the above mentioned 5 phases of treating process in accordance with the weekly schedule of the hospital. It was thought that the patients would require prolonged after care management even after they were released from the hospital and that they will also require periodic visit, to the hospital and doctor′s interview with their family. In conclusion, the question of the young generation and marihuana smoking is becoming a great social problem in which their resistances to the "established system" and society is growing in the from of antiestablishment movements. In our country, the smoking of marihuana is gradually developing, therefore, I think, that it would be a very fortunate thing for us, if this report could be helpful for the motivation of further study on the questions of the young generation and its problems.

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The Effects of the Number, Ratio of Advanced Courses, and Variety in Science Elective Subjects on the Growth of High School Science Course Students' Attitude Towards Science (고등학교에서 과학 선택 과목의 수, 심화(II) 과목 비율, 교과 다양성이 이과 학생의 과학에 대한 태도 성장에 미치는 효과)

  • Lee, Gyeong-Geon;Hong, Hun-Gi
    • Journal of Science Education
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    • v.46 no.1
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    • pp.80-92
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    • 2022
  • We fitted latent growth models of attitude towards science using the Korea Education & Employment Panel 2004-2007 data with 343 high school students. The growth model show better fit indices compared to the no growth model. The intercept and slope showed significant variances, and thus, we added control variables of the number, ratio of advanced courses, and variety in science elective subjects, and the achievement percentile for middle school. In the conditional growth model, the previous achievement has significant positive effects on the intercept and the ratio of the advanced courses and variety of science subjects show significantly positive effects on the slope. Based on the results, it supports the 2022 Revised Science Curricular that high school credit system should provide students with basic 'Physics,' 'Chemistry,' 'Biology,' and 'Earth Science,' credits in 'general electives', various integrated subjects in 'converged electives', and highly advanced subjects in 'career electives.'

Aerodynamic control capability of a wing-flap in hypersonic, rarefied regime: Part II

  • Zuppardi, Gennaro;Vangone, Daniele
    • Advances in aircraft and spacecraft science
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    • v.4 no.5
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    • pp.503-514
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    • 2017
  • The attitude control of an aircraft is usually fulfilled by means of thrusters at high altitudes. Therefore, the possibility of using also aerodynamic surfaces would produce the advantage of reducing the amount of fuel for the thrusters to be loaded on board. For this purpose, Zuppardi already considered some aerodynamic problems linked to the use of a wing flap in a previous paper. A NACA 0010 airfoil with a trailing edge flap of 35% of the chord, in the range of angle of attack 0-40 deg and flap deflections up to 30 deg was investigated. Computer tests were carried out in hypersonic, rarefied flow by a direct simulation Monte Carlo code at the altitudes of 65 and 85 km of Earth Atmosphere. The present work continues this subject, considering the same airfoil and free stream conditions but two flap extensions of 45% and 25% of the chord and two flap deflections of 15 and 30 deg. The main purpose is to compare the influence of the flap dimension with that of the flap deflection. The present analysis is carried out in terms of: 1) percentage variation of the global aerodynamic coefficients with respect to the no-flap configuration, 2) increment of pressure and heat flux on the airfoil lower surface due to the Shock Wave-Shock Wave Interaction (SWSWI) with respect to the same quantities with no SWSWI or in no-flap configuration, 3) flap hinge moment. Issues 2) and 3) are important for the design of the mechanical and thermal protection system and of the flap actuator, respectively. Under the above mentioned test and geometrical conditions, the flap deflection is aerodynamically more effective than the flap extension, because it involves higher variation of the aerodynamic coefficients. However, tests verify that a smaller deflection angle involves the advantage of a smaller increment of pressure and heat flux on the airfoil lower surface, due to SWSWI, as well as a smaller hinge moment.

Dynamic Modeling of Autonomous Underwater Vehicle for Underwater Surveillance and Parameter Tuning with Experiments (수중정찰용 자율무인잠수정의 운동 모델링 및 시험을 통한 계수 조정)

  • Lee, Phil-Yeop;Park, Sung-Kook;Kwon, Soon Tae;Park, Sangwoong;Jung, Hunsang;Park, Min-Soo;Lee, Pan-Mook
    • Journal of Ocean Engineering and Technology
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    • v.29 no.6
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    • pp.488-498
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    • 2015
  • This paper presents the dynamic model of an AUV called HW200 for underwater surveillance. The mathematical model of HW200 is briefly introduced, considering its shape. The maneuvering coefficients were initially estimated using empirical formulas and a database of vehicles with similar shapes. A motion simulator, based on Simulink of Mathworks, was developed to evaluate the mathematical model of the vehicle and to tune the maneuvering coefficients. The parameters were finely tuned by comparing the experimental results and simulated responses generated with the simulator by applying the same control inputs as the experiment. The velocity of HW200 in the tuning process was fixed at a constant forward speed of 1.83 m/s. Simulations with variable speed commands were conducted, and the results showed good consistency in the motion response, attitude, and velocity of the vehicle, which were similar to those of the experiment even under the speed variation. This paper also discusses the feasibility of its application to a model-based integrated navigation system (INS) using the auxiliary information on the velocities generated by the model.