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19세기 남병철 『의기집설(儀器輯說)』 혼천의 용법 분석
최홍순,김상혁,민병희,남경욱,유경한,김용기,HONG SOON CHOI,SANG HYUK KIM,BYEONG-HEE MIHN,KYOUNG-UK NAM,GEOYOUNG-HAN YOO,YONGGI KIM 한국천문학회 2024 天文學論叢 Vol.39 No.1
The armillary sphere, an astronomical observation device embodying the Orbital Heaven Theory of the Later Han Dynasty in China, holds both historical and scientific significance. It has been produced in various forms by many individuals since its inception in the era of King Sejong in the Joseon Dynasty. A prominent figure in this field was Nam Byeong-cheol (南秉哲, 1817-1863), known for his work 'Uigijipseol' (儀器輯說), published in 1859, which detailed the history, production methods, and usage of the armillary sphere. This text particularly highlights 21 applications of the armillary sphere, divided into 33 measurements, covering aspects like installation, time, and positional measurements, supplemented with explanations of spherical trigonometry. Despite numerous records of the armillary sphere's design during the Joseon Dynasty, detailed usage information remains scarce. In this study, the 33 measurements described in 'Uigijipseol' (儀器輯說) were systematically classified into six for installation, nineteen for position measurement, seven for time measurement, and one for other purposes. Additionally, the measurement methods were analyzed and organized by dividing them into the ecliptic ring, moving equatorial ring, and fixed equatorial ring of the armillary sphere. In other words, from a modern astronomical perspective, the results of schematization for each step were presented by analyzing it from the viewpoint of longitude, right ascension, and solar time. Through the analysis of Nam's armillary sphere, this study not only aims to validate the restoration model of the armillary sphere but also suggests the potential for its use in basic astronomical education based on the understanding of the 19th-century Joseon armillary sphere.
[진동·소음부문] 음향 홀로그래피를 이용한 자동차 타이어의 전연과 후연 소음의 구분 가능성에 대한 연구
남경욱(Kyoung-Uk Nam),김양한(Yang-Hann Kim) 한국자동차공학회 1999 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Tire noise is generated by several noise sources. For the effective control of the tire noise, it is necessary to separate the contributions of the sources to sound field. However, it is difficult to separate the leading edge and trailing edge noise of tire, because they have the same frequency band. This paper performed the basic experiment for the separation of the leading and trailing edge noise. The experiment on two incoherent speakers showed the possibility to separate of leading and trailing edge noise.
김무상(Moosang Kim),남경욱(Kyoung-Uk Nam) 한국유체기계학회 2006 유체기계 연구개발 발표회 논문집 Vol.- No.-
This paper introduces the process of reducing the automobile wind noise by using acoustic holography. First, a microphone array scans a side or plane under an automible step-by-step. Second, a pressure on a source plane is calculated. Third process is to analyze how much individual sources contribute to interior noise. Fourth process is to control important noise sources determined by the contribution analysis. This paper deals with the entire process, theoretical and experimental problems.
이강덕(Kang-Duck Ih),남경욱(Kyoung-Uk Nam) 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Image blurring caused by mirror vibration are studied. Possible causes of image blurring are reviewed, including road inputs and engine vibration inputs through vehicle body, and a variety of aerodynamic inputs. Experiments are carried out to understand the relative influence of the causes of vibration with real ear. Influence of experimental noise factor such as mass of accelerometers, mounting positions and mirror setting angles are studied. On road test and wind tunnel test are carried out to differentiate the mechanical vibration and aerodynamic vibration from the real vibration of on road driving. Strategic countermeasure is roughly proposed in this paper.
국형석(Hyung-Seok Kook),김형건(Hyoung-Gun Kim),남경욱(Kyoung-Uk Nam),이강덕(Kang-Duck Ih) 한국소음진동공학회 2017 한국소음진동공학회 논문집 Vol.27 No.7
Road roughness is known to be one of the most influential factors affecting road-noise level. A one-dimensional road-roughness profile can be measured by a laser profilometer attached to theside of a vehicle. The mean profile depth (MPD), which can be calculated from this profile, is commonly used to correlate the road-noise level and the road roughness; however, the MPD has little correlation with road-noise levels. The purpose of this study is to find reliable parameters other than MPD from the road-profile signal that are well-correlated with road noise, allowing surfaces to be quantified in terms of noise level. In this study, these parameters are obtained from the octave-band road-texture levels. To validate this approach, road-profile signals and interior road noises are measured from constant-speed-driving tests performed on various domestic and foreign roads. Interior noises are bandpass filtered to yield various road noises in different frequency bands, including booming noise, tympanic noise, and rumble noise. The road-roughness-profile signals measured with the laser profilometer during the constant-speed-driving tests are processed to yield the texture levels in eight octave bands. A principal-component analysis is then performed to reduce redundant information in the texture levels, and it turns out that the texture levels for the eight octave bands can be represented with high accuracy by two principal components. Finally, the correlation between various road-noise levels and road roughnesses is found by a regression analysis.