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실험 4단자정수를 이용한 저소음 흡기계의 강건 최적 설계
조용구(Joe, Yong-Goo),오재응(Oh, Jae-Eung),이유엽(Lee, You-Yub),김흥섭(Kim, Heung-Seob) 한국소음진동공학회 2002 한국소음진동공학회 논문집 Vol.12 No.6
Recently, regulations of the government and concerns of people give rise to the interest in exhaust and intake noise of passenger car as much as other vehicles. In these demands, performance prediction software with hybrid method was developed at first. Secondly, robust design was used for improving the noise reduction capacity of intake system with the performance prediction software. On the basis of the existing design, length and radios of each component that was thought to effect on the capacity of intake system was selected. The factors were arranged by using L18 table of orthogonal array and optimum value was obtained.
마찰기인 접촉 강성을 가지는 2-자유도계 면외 방향 진동 시스템의 선형 안정성 해석
조용구(Joe, Yong-goo),신기홍(Shin, Ki-hong),이현영(Lee, Hyun-young),오재응(Oh, Jae-Eung),이수갑(Lee, Su-Gab) 한국소음진동공학회 2005 한국소음진동공학회 논문집 Vol.15 No.3
A two-degree-of-freedom out-of-plane model with contact stiffness is presented to describe dynamical interaction between the pad and disc of a disc brake system. It is assumed that the out-of-plane motion of the system depends on the friction force acting along the in-plane direction. Dynamic friction coefficient is modelled as a function of both in-plane relative velocity and out-of-plane normal force. When the friction coefficient depends only on the relative velocity, the contact stiffness has the role of negative stiffness. The results of stability analysis show that the stiffness of both pad and disc is equally important. Complex eigen value analysis is conducted for the case that the friction coefficient is also dependent on the normal force. The results further verify the importance of the stiffness. It has also been found that increasing the gradient of friction coefficient with respect to the normal force makes the system more unstable.
2 자유도계 모델을 이용한 디스크 브레이크의 면외방향 운동에 대한 접촉강성의 영향
조용구(Yong-Goo),신기흥(Ki-Hong Shin),차병규(Byung-Gyu Cha),이충휘(Choong-Hwi Lee),이정윤(Jung-Yoon Lee),오재웅(Jae-Eung Oh) 한국자동차공학회 2003 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
A two degree-of-freedom mathematical model is presented to investigate the friction mechanism of a disc brake system. A contact parameter is introduced to describe the coupling between the in-plane and the out-of-plane motions. In order to describe the relationship between the in-plane motion and the out-of plane motion, the contact friction coefficient is considered as a function of both relative velocity and normal force. The out-of-plane motion is then investigated by numerical analysis for various parametric conditions. The results of numerical analysis show the existence of limit cycle of an out-of-plane motion caused by the effect of intermittent contact stiffness. Also Frequency analysis shows that the motion due to the contact nonlinearity produces frequency unification and frequency modulation.
Student Team-Achievemenl Division(STAD) 모형의 협동학습이 고등학교 학생들의 천문영역에 대한 학업성취도와 과학적 태도에 미치는 영향
박홍서,조용구,Park, Hong-Seo,Cho, Yong-Goo 한국지구과학회 2002 한국지구과학회지 Vol.23 No.8
본 연구의 목적은 천문영역에서 STAD 모형의 협동학습이 고등학생들의 학업 성취도와 과학적 태도에 미치는 영향을 밝히는데 있다. 본 연구의 또 다른 목적은 천문영역에 있어서 향상 점수에 근거한 협동 학습과 교사 주도로 수업이 이루어지는 전통적 학습 사이의 영향을 비교해 보는 것이다. 본 연구는 인천시 소재 일반계 고등학교 1학년 남학생 2개 반을 대상으로 하였다. 협동학습 집단의 학생들은 협동학습 방법으로 주당 4시간씩 4주 동안 수업을 받았다. 협동학습을 받는 동안에 학생들은 매주 ‘태양계 탐사와 별’ 단원에 대한 형성 평가를 받았다. 그 결과, 위의 두 가지 접근 방법은 학생들의 천문학적 지식에 있어서 상당히 다른 영향을 주었으며, 학생들이 전통적인 학습방법보다는 협동적인 학습방법에 보다 긍정적인 과학적 태도를 취하는 것을 보여주고 있다. 결론적으로 협동 학습은 천문학적 지식의 학습과 과학적 태도에 있어서 전통적인 학습보다 보다 효과적이고 긍정적인 것으로 나타났다. The purposes of this study is to examine the effects of cooperative teaming through student team-achievement division (STAD) model on high school students’ leaming achievements and scientific attitudes in the field of astronomy. It is another aim to compare effects of cooperative learning based on improvement scores with traditional teaching method done only by teachers in astronomy field. This study was conducted on two tenth grade classes in a boy’s high school in Incheon. Students had four classes a week in cooperative learning way for four weeks. During cooperative learning classes, formative evaluation was given to students every week oil Stars and Exploring the Solar System. The results show that these two approaches have great different effects on students’ astronomical knowledge and that students adopt more positive scientific attitude toward cooperative learning classes than traditional ones. In conclusion, the cooperative learning is more effective and positive than traditional one in learning astronomical knowledge and in students scientific attitude for science classes.
2자유도계 모델을 이용한 디스크 브레이크 스퀼 소음에 대한 댐핑의 영향에 관한 연구
신기홍(Shin, Ki-Hong),조용구(Joe, Yong-Goo),오재응(Oh, Jae-Eung) 한국소음진동공학회 2003 한국소음진동공학회 논문집 Vol.13 No.12
A two-degree-of-freedom model is suggested to describe basic dynamical behaviors of the interaction between the pad and the disc of a disc brake system. Although a pad (and a disc) has many modes of vibration in practice, only one mode of each component Is considered. In this paper, a linear analysis is performed by means of the stability analysis to show various conditions for the system to become unstable, and is based on the assumption that the existence of limit cycle (this corresponds to an unstable equilibrium point inside the limit cycle) represents the squeal state of the disc brake system. The results of the stability analysis show that the damping of the disc is as much Important as that of the pad, whereas the damping of the pad only is considered In most practical situations.