수평방향의 가진을 받는 강체 블록의 로킹진동 특성

정만용,김정호,김기형 朝鮮大學校 機械技術硏究所 2002 機械技術硏究 Vol.5 No.1

This research concentrated on the influence of non-linearities associated with impact upon the rocking behavior of a rigid body block subjected to one dimensional horizontal direction excitation. The non-linearities in the vibration produced were found to be strongly dependent on the impact effect between the block and its base, which abruptly reduces kinetic energy. In this study, the rocking vibration system of two types are considered. The first was the undamped rocking vibration system, predicted by distregarding the energy dissipation at impact, and the seconded involved a damped rocking system. which included energy dissipation and sliding motion. The complex behaviors of chaos response, in the phase space, were illustrated by Poincare map. The bifurcation diagram and Poincare map will be a significant material in order to understand chaos of rocking system.

2차원 정현파 가진을 받는 강체 블록의 로킹진동

정만용,김기형 朝鮮大學校 機械技術硏究所 2001 機械技術硏究 Vol.4 No.2

This research deals with the non-linearities associated with impact and sliding for the rocking behavior of rigid body block subjected to two dimensional excitation of horizontal and vertical direction. The non-linearities examined of impact between block and base; The transition of two governing rocking equations, the abrupt reduction in kinetic energy associated with impact. In this study, the rocking vibration system of two types are considered for several friction condition. One is the undamped rocking vibration system, disregarding energy dissipation at impact and the other is the damped rocking system, including energy dissipation at impact. The response analysis by non-dimensional rocking equation is carried out for the change of excitation amplitude.

Characterization on the Rocking Vibration of Rigid Blocks under Horizontal Harmonic Excitations

정만용,양인영 한국정밀공학회 2012 International Journal of Precision Engineering and Vol. No.

This investigation deals with characteristics of rocking vibration of rigid block subjected to the horizontal harmonic excitations. Nonlinear rocking system may include minute changes of system parameters, such as friction and restitution coefficients depending on contact conditions between the block and the base, and friction force that may vary as the block moves. This paper is the first part of the examination how minute changes of the above system parameters are related with minute changes of friction coefficients. A numerical analysis program has been developed to solve nonlinear motion equations for rocking motion of a rigid block subjected to horizontal base excitation. Natural changes of friction coefficient are simulated by random numbers with a normal probability distribution. Analytical results have shown that rocking responses are very sensitive to small changes of friction conditions between the block and the base. Minute changes of the friction coefficients make rocking response unstable and greatly change the response distribution itself. Because of the dynamic nature of friction coefficients changes, experimental rocking responses are not recurring.

수평방향의 정현파 가진을 받는 강체 블록의 비선형 록킹진동특성

정만용,김정호,김지훈,정낙규,양인영 한국안전학회 1999 한국안전학회지 Vol.14 No.4

This research concentrates on the influence of non-linearities associated with impact for the nonlinear rocking behavior of rigid block subjected to one dimensional sinusoidal excitation of horizontal direction. The transition of two governing rocking equations, the abrupt reduction in the kinetic energy associated with impact, and sliding motion of block. In this study, two type of rocking vibration system are considered. One is the undamped rocking vibration system, disregarding energy dissipation at impact and the other is the damped rocking system, including energy dissipation and sliding motion. The response analysis using non-dimensional rocking equation is carried out for the change of excitation parameters and friction coefficient. The chaos responses were discovered in the wide response region, particularly, for the case of high excitation amplitude and their chaos characteristics were examined by the time history, Poincare map, power spectra and Lyapunov Exponent of rocking responses. The complex behavior of chaos response, in the phase space, were illustrated by Poincare map. The bifurcation diagram and Poincare map were shown to be effective in order to understand chaos of rocking system.

Wavelet해석을 이용한 타음 진단법의 개발

정만용(Manyong Jeong),양인영(Inyoung Yang) 한국자동차공학회 2011 한국자동차공학회 학술대회 및 전시회 Vol.2011 No.11

This study is related with an approach for the diagnosis of defects or peculiar on structures using hammering test that is one of the non-destruction inspection methods of the structure. In this paper, the detection method of the defects as a non-destruction inspection method has been suggested and the efficiency of the diagnosis method based on the hammering sounds has been estimated in a simple structure model, an aluminum bar with free end. According to the simulation by FEM model, it became obvious that the natural frequencies for the relating vibration mode of the aluminum bar decrease when the crack is at the abdomen of the vibration mode. On the contrary, the natural frequencies may not be changed or the change may be small when the crack is at near the nodes of natural vibration mode. The diagnosis of the existence of the defect was done from the correlation of the Wavelet coefficient between the two sound signals from aluminum bar without and with crack. The rough position of the crack is estimated from the relationship among the natural frequencies.

학동 전기 소아에서 폐활량 측정의 질관리와 성공률

서현경,장선정,정다운,위영선,지혜미,서지영,한만용 대한소아청소년과학회 2009 Clinical and Experimental Pediatrics (CEP) Vol.52 No.11

Purpose:We examined the ability of preschool aged children to meet the American Thoracic Society (ATS) and European Resiratory Society (ERS) goals for spirometry quality and tried to find out the major factor for improving the rate of success of spiromety test in this age group. Methods:Spirometry was performed in 2-6 aged 155 children with chronic cough or suspicious asthma with the recording of maneuver quality measures of forced expiratory time, end-of-test volume, back-extrapolated volume (Vbe), and forced vital capacity (FVC), as well as flow-volume curve. The subjects were tested several times and the two best results in each subject were selected. All criteria for quality control were suggested by ATS/ERS guidelines. The criteria for starting of the test was Vbe <80 mL and Vbe/FVC <12.5%. The criteria for repeatability of the test was that second highest FVC and FEV1 are within 100 ml or 10% of the highest value, whichever is greater. For the criteria for termination of the test for preschool aged children, we evaluated the flow-volume curve Results:As getting older, the success rate of spirometry increased and rapidly increased after 3 years old. Total success rate of the test was 59.4% (2 years old - 14.3%, 3 years old - 53.7%, 4 years old - 65.1%, 5 years old - 69.7%, 6 years old- 70.8%). The percentage of failure to meet the criteria for starting the test was 6.5%, repeatability of the test was 12.3% and end of the test was 31%. There was a significant difference only in age between success group and failure group. Evaluating the quality control criteria of previous studies, the success rate increased with age. Conclusion:About 60% of preschool aged children met ATS/ERS goals for spirometry test performance and the success rate was highly correlated with age. It is clearly needed that developing more feasible and suitable criteria for quality control of spirometry test in preschool aged children. 목 적:국내 학동 전기 소아를 대상으로 폐활량 측정법을 시행하여 기존에 제시된 여러 지표를 기준으로 검사 결과의 적정성을 평가함으로써 이 연령대에서의 폐기능 검사의 성공률을 알아보고자 하였다. 방 법:만성 기침이나 천식이 의심되어 내원한 2세 이상 6세 이하의 176명을 대상으로 폐활량 측정법을 시도하여 총 155 명에서 측정 결과를 얻을 수 있었다. ATS/ERS 에서 제시한 기준에 따라 후외삽용적(Vbe)이 80 mL 미만이고 FVC의 12.5% 미만일 때를 시작 기준에 적합하다고 정의하였다. 검사의 반복성을 확인하기 위해 선별한 두개의 유량-용적 곡선에서 FVC, FEV1 의 차이를 구하여 FVC와 FEV1의 절대적 차이값이 100 mL 또는 10% 미만인 경우를 적합하다고 정하였다. 검사의 종료에 대한 기준은 학동 전기 연령에서 수치적으로 정의되어 있지 않지만 유량-용적 곡선이 초기에 급격하게 증가해서 후기에 완만하게 감소하는 것을 합당하다고 보았다. 또한 유량-용적 곡선이 적절하게 나온 대상자(107명)를 선별하여 다른 문헌에 발표된 여러 정도 관리 기준에 맞추어 각 항목별로 성공률을 비교하였다 결 과:전체 폐기능 검사의 성공률은 59% 이었고 연령이 증가할수록 폐활량 측정법의 성공률이 증가하였으며, 특히 3세부터 급격하게 성공률이 증가하였다(2세 14.3%, 3세 53.7%, 4세 65.1%, 5세 69.7%, 6세 70.8%). 폐활량 측정법의 실패 원인으로는 시작 기준에 맞지 않는 경우가 전체의 6.5%, 반복성 기준에 맞지 않는 경우가 12.3% 또 최대 호기량의 부족, 조기 종료 등으로 인해 검사 종료 기준에 맞지 않는 경우가 전체의 31% 로 가장 높았다. 폐활량 측정법 성공군와 실패군을 비교하였을 때 나이에서만 유의한 차이가 있었다(P<0.01). 정도 관리에 대한 몇몇 연구결과에 따라 각 항목별로 성공률을 보았을 때 연령이 증가할수록 성공률도 증가하였다. 결 론:학동 전기 소아에서도 약 60% 정도 폐활량 측정법을 성공적으로 수행하였다. 성공률은 연령에 따라 급격히 변화하므로 각 연령에 적합한 정도 관리 기준을 개발하여 이용한다면 검사의 성공률을 높일 수 있을 것으로 사료된다.

한국 근현대 과학사 연구의 성과와 과제: ‘한국 과학’에서 ‘과학 한국’까지

문만용 ( Moon Manyong ),신향숙 ( Shin Hyangsuk ) 한국과학사학회 2020 한국과학사학회지 Vol.42 No.3

This paper reviews the achievements of Korea’s modern and contemporary history of science research and presents some tasks to be solved. First, the English abstracts of 106 modern and contemporary papers published in The Korean Journal for the History of Science are categorized into five topics through text mining. It also examines the central themes of the literatures in five periods: the late 19th century, the Japanese colonial era, liberation to the 1950s, the 1960s to the 1970s, after the 1980s, and North Korea’s science and technology. In particular, it introduces recently published articles and books. We argue that an understanding of the times should be fully reflected upon, and that comparative studies are necessary to overcome a mononational perspective. Furthermore, we propose expanding the scope of research by increasing contacts with adjacent areas and introducing quantitative methodologies that can handle vast amounts of data. In addition, while studies so far have focused on the formation and identity of ‘Korean science’, future research should clarify the ‘scientific Korea’ created by such science.

정현파 가진을 받는 강체 블록의 비선형 로킹 진동특성

김정호,정만용,양인영,김기형,전형주 국립7개대학공동논문집간행위원회 2001 공업기술연구 Vol.1 No.-

In this study, two type of rocking vibration system are considered. One is the undamped rocking vibration system, disregarding energy dissipation at impact and the other is the damped rocking system, including energy dissipation and sliding motion. The response analysis using non-dimensional rocking equation is carried out for the change of excitation parameters and friction coefficient. The chaos responses were discovered in the wide response region, particularly, for the case of high excitation amplitude and their chaos characteristics were examined by the time history, Poincare map, power spectra and Lyapunov Exponent of rocking responses. The complex behavior of chaos response, in the phase space, were illustrated by Poincare map. The bifurcation diagram and Poincare map were shown to be effective in order to understand chaos of rocking system.

미끄럼운동을 동반하는 강체 블록 구조물의 로킹진동- 수평방향과 수직방향의 여진진동수가 다른 경우에 대하여 -

김정호,정만용,양인영 대한기계학회 2003 大韓機械學會論文集A Vol.27 No.6

학동기 소아에서 impulse oscillometry system로 측정한 폐기능 정상치

위영선,김형윤,정다운,박혜원,신윤호,한만용 대한소아청소년과학회 2007 Clinical and Experimental Pediatrics (CEP) Vol.50 No.9

목 적 : IOS는 호흡 노력을 요하지 않으며 호흡기 저항을 측정하는 비침습적인 방법이다. IOS를 이용하여 국내 학동기 소아에서의 표준치를 알아보고자 하였다. 방 법 : 7-12세의 건강한 소아 92명을 대상으로 IOS를 시행하였다. IOS 결과 값과 키, 몸무게, 체표 면적, 신체 질량 지수 및 나이 등의 연관성에 대하여 선형 회귀 분석을 시행하였다 결 과 : IOS 성공률은 92.4%였다. 키, 몸무게, 체표 면적, 신체 질량 지수, 나이 등 5가지 변수값과 Rrs 및 Xrs를 분석한 결과, 키가 의미 있는 예측 인자였으며, 5가지 변수 모두 적용한 경우 가장 설명력이 높았다. 각각의 주파수에 따라 회귀 곡선 공식을 구하였으며, 이는 이전 연구들의 표준 공식과 비슷하였다. 결 론 : IOS의 표준치를 구하였으며 이를 활용하여 다양한 호흡기 질환의 진단에 활용될 수 있을 것이라 여겨진다. Purpose : The impulse oscillometry (IOS) is applicable to young children because it requires minimal cooperation and a non-invasive method to measure the mechanics of respiratory system. This study aimed to develop the reference values in school-aged children in Korea, using IOS which is a modification of forced oscillation technique (FOT). Methods : Measurements were performed in 92 previously untrained healthy children, aged 7 to 12 years old, using IOS. We analyzed the relationships between the data about their age, height, weight, body surface area (BSA), body mass index (BMI) and the result of IOS using the linear regression test. Results : The success rate of IOS was 92.4%. Stepwise multiple regression of resistance of respiratory system (Rrs) and reactance of respiratory system (Xrs) in natural form for age, height, weight, BSA, BMI showed that height was the most significant predictor and altogether of 5 variables explained the Rrs and Xrs most. Our regression equations at multiple frequencys were comparable to published reference values, especially about the Rrs obtained at 5 Hz. Conclusion : IOS is a feasible method to measure the respiratory resistance in untrained children. We got the reference values using IOS and it seems to be useful to diagnose a variety of respiratory diseases.