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소상공인 점포의 분포와 환경요인의 공간적 영향관계에 관한 실증연구
유무상 ( Mu-sang Yoo ),최돈정 ( Don-jeong Choi ) 한국지리정보학회 2019 한국지리정보학회지 Vol.22 No.1
본 연구에서는 천안시, 아산시의 100m×100m격자 내에 집계된 소상공인 분포가 가지는 공간적 의존성(Spatial Dependency)과 공간적 이질성(Spatial Heterogeneity)을 전역적(Global), 국지적(Local) 공간 자기상관(Spatial Autocorrelation)을 통해 측정 및 가시화하였다. 먼저 탐색적 공간데이터 분석방법(ESDA: Explotory Spatial Data Analysis)인 Moran’s I Index를 통해 연구지역에서 소상공인 분포의 정적(Positive)공간자기상관이 발생하는 것을 확인하였으며, 국지적 공간자기상관 지표(LISA : Local Indicators of Spatial Association) 중 하나인 Getis-Ord GI*를 통해 공간자기상관의 국지적 패턴을 가시화하였다. 이를 통해 소상공인 상가점포의 입지요인 분석 시 적용할 변수와의 관계에 대해 공간회귀모형의 적용이 타당함을 증명하였으며, 소상공인의 분포와 모바일 트래픽 기반의 시간대별 유동인구, 토지이용 혼합성 지수 그리고 주거지, 상점, 도로망, 교통결절점과의 공간영향관계를 지리가중 회귀분석(GWR : Geographically Weighted Regression)을 통해 분석하였다. 최종적으로 다중공선성(Multicollinearity)이 발생했던 버스정류장 접근성, 오후시간대 유동인구, 저녁시간대 유동인구를 제외한 6개의 변수를 적용하였고 GWR 모형이 OLS모형보다 주요통계량에서 모형 설명력이 개선됨을 도출하였다. 분석에 최종적으로 적용된 6가지 변수의 회귀계수와 국지적 결정계수(Local R<sup>2</sup>)에 대해 연구지역 내에서 공간적으로 변화하는 변수별 영향력을 가시화하였다. 본 연구는 실질적으로 측정된 방식의 유동인구 정보를 적용함으로써 상권을 이용하는 도시민의 동적 정보를 반영한 것이 상권분석을 수행한 다른 연구들과 차별적인 성격을 가진다. 마지막으로 이러한 동적정보와 변수들의 공간적 상호작용을 구조화하기 위해 미시적 공간단위에서 공간통계학(Spatial Statistical)적 모형 적용을 통해 상권분석의 새로운 프레임을 제시하였다는 점에서 연구적 의의를 가진다. This research measured and visualized the spatial dependency and the spatial heterogeneity of the small business in Cheonan-si, Asan-si with 100m×100m grids based on global and local spatial autocorrelation. First, we confirmed positive spatial autocorrelation of small business in the research area using Moran’s I Index, which is ESDA(Exploratory Spatial Data Analysis). And then, through Getis-Ord GI*, one kind of LISA(Local Indicators of Spatial Association), local patterns of spatial autocorrelation were visualized. These verified that Spatial Regression Model is valid for the location factor analysis on small business commercial buildings. Next, GWR(Geographically Weighted Regression) was used to analyze the spatial relations between the distribution of small business, hourly mobile traffic-based floating population, land use attributes index, residence, commercial building, road networks, and the node of traffic networks. Final six variables were applied and the accessibility to bus stops, afternoon time floating population, and evening time floating population were excluded due to multicollinearity. By this, we demonstrated that GWR is statistically improved compared to OLS. We visualized the spatial influence of the individual variables using the regression coefficients and local coefficients of determinant of the six variables. This research applied the measured population information in a practical way. Reflecting the dynamic information of the urban people using the commercial area. It is different from other studies that performed commercial analysis. Finally, this research has a differentiated advantage over the existing commercial area analysis in that it employed hourly changing commercial service population data and it applied spatial statistical models to micro spatial units. This research proposed new framework for the commercial analysis area analysis.
유무상(Mu-Sang Yoo),한승우(Seung-Woo Han),노철우(Cheol-Woo Roh),류길수(Kil-Su Ryu),오승태(Seung-Tae Oh) 한국소음진동공학회 2014 한국소음진동공학회 학술대회논문집 Vol.2014 No.10
Generator is the main equipment of a power plant that generates electric power. The line frequency is 60Hz, since that is operated at 3600rpm in fossil power plant. Therefore, the specific frequency 120Hz by the electromagnetic excitation force is generated inherently. If the looseness of stator at generator happens, abnormal sound that has 120Hz and the harmonic frequency is emitted from generator frame. In that case, binding of end-winding or re-wedging is needed for the reduction of sound level. In case of severe level of sound, belly band can be additionally installed at core. In this paper, the characteristics of generator sound is described and modal data is analyzed after installation of belly band.
진동 감시용 위치 결정 센서의 위상오차에 대한 실험적 고찰과 비교평가
오승태(Seung-Tae Oh),유무상(Mu-Sang Yoo),봉석근(Suk-Keun Bong) 한국소음진동공학회 2014 한국소음진동공학회 학술대회논문집 Vol.2014 No.10
Field balancing is required in any kind of phase information for the determination location balancing mass toward a rotor unbalance mass. Phase or phase angle is a measurement of the relationship of how one vibration signal which relates to another vibration signal and is commonly used to calculate the placement of balance weight. In this paper, A right guideline shows the photo optical speed sensor as the external keyphasor is a very useful when diagnosing machinery vibration problems on considering a phase lag comparing to the laser optical speed sensor. Some experimental results generate the interesting phase errors when appling to a wrong conditions. So, Usage of photo optical speed sensor which is used primarily to measure the shaft rotating speed serves as a reference for measuring vibration phase information has effect on the placement of phase angle how it was misunderstood. This paper will help a right method to search for the position of balancing weight and serves as baseline for further measurements using low cost and much easier user convenience. It is concluded that the propose baseline is likely to be applicable to apply to the practical field balancing weight.
한승우(Han, Seung-Woo),노철우(Roh, Cheol-Woo),유무상(Yoo, Mu-Sang),김인철(Kim, In-Chul),주인국(Joo, In-Gouk),김명식(Kim, Myong-Shik) 한국소음진동공학회 2008 한국소음진동공학회 논문집 Vol.18 No.2
This case study refers to turbine-generator with retrofitted turbine rotor. Vibration problem occurring after the retrofit was mainly due to high vibration from exciter side. However, repeated test run and operation during scheduled maintenance caused high vibration from generator bearing, and post-overhaul test run before turbine vibration correction caused oil whip on the bearing. This case study shows how to analyze vibration condition of high turbine generator vibration detected during the post-overhaul test run and vibration condition of offline and online data to reflect it on establishing maintenance schedule and overhaul correction procedure. Vibration data could be acquired during steady load operation or even with varying speed and load. Each data is important for machinery condition evaluation. This case study shows that the vibration data during extreme condition is the key factor in analysis, which helps to find the machinery problem.
편심 가진기를 이용한 기계설비 공진 진단 기법에 대한 고찰
오승태(Seung-Tae Oh),류길수(Kil-Su Ryu),한승우(Seung-Woo Han),노철우(Chul Woo Rho),주인국(In Gook Joo),오경환(Kyong Hwan Oh),유무상(Mu-Sang Yoo),조철환(Chul-Hwan Cho) 한국소음진동공학회 2015 한국소음진동공학회 학술대회논문집 Vol.2015 No.4
One of the most important things is to investigate and to resolve the resonance problem with vibration diagnostics for machinery and power plant equipment using CBM (Condition-based maintenance) within a short time and with low cost. The objective of this paper is to introduce the diagnosis technique for resonant machinery equipment using eccentricity shaker with mechanical unbalance mass. When comparing to impact hammer method, the results of natural frequency for measure objects such as machine structures and rotating machinery show good agreement within 3 % of variation. Through the experimental verification using the proposed vibration diagnosis, it is helpful and useful for site experts and practical engineers to evaluate the vibration resonance in fields. So, the use of eccentricity shaker is much more useful and available to investigate the natural frequency than the hammer impact.