육상교통환경 위성항법 성능 예측을 위한 Sky-View-Factor 기반 Dilution of Precision 분석

홍운기,최광식,이은성,임성헉,허문범 韓國航行學會 2012 韓國航行學會論文誌 Vol.16 No.6

위성항법의 가시성, Dilution of Precision (DOP), 신호대잡음비 등과 같은 위치결정 성능지표는 개활지 환경과 같이 항법위성의 가시성이 좋은 지역에서 그 활용도가 높으며, 육상교통환경의 경우 그 활용도가 낮다. 본 논문은 육상교통환경에서 위성항법 신호를 활용하여 위치결정을 수행하는 경우 활용도가 높은 성능지표로 Sky View based DOP (SVDOP)을 제안한다. SVDOP은 Sky-View Factor(SVF)를 응용하여 개발되었으며, 기존의 SVF의 문제점을 극복할 수 있다. Sky-View 영상을 활용하여 특징점을 선택하고 이를 활용하여 DOP를 계산할 수 있다. 제안된 방법을 이용하는 경우 SVF 사용보다 육상교통환경에서 위치결정 성능 예측에 용이함을 확인할 수 있다. The conventional indexes for describing the GNSS positioning performance such as satellite visibility, dilution of precision (DOP) and signal to noise ratio is very useful in open sky, however, they are not useful in the land road environment. In this paper new index is suggested for describing the GNSS positioning performance for the road environment. The new index is called Sky View based DOP (SVDOP). SVDOP is derived referring the Sky-View-Factor (SVF). The usefulness is analyzed by comparing the SVDOP and SVF in land road environment after the singularity points are selected and SVDOP is calculated.

도시규모 고해상도 하늘시계지수 지도의 구축 및 활용방향 고찰: 수원특례시를 대상으로

안승만 국토연구원 2022 국토연구 Vol.113 No.-

A sky view factor (SVF) is a dimension-reduced urban canopy parameter (UCP) that captures three-dimensional urban surface morphologic form through a horizontal fraction. This study developed an urban scale high-resolution (2 m) sky view factor (SVF) raster mapping method and discussed it for further applications. The study site is Suwon administrative area, South Korea (121.04 km²), with a population of close to 1.3 million. In this study, airborne LiDAR-based three-dimensional point cloud (3DPC) data were used as an input to build urban scale high-resolution SVF raster maps. Two types of SVF maps (GB and GBH) are compared to describe the tree effect using Zonal statistics quantitatively. Results visually and statically explain a relationship between land-use-based urban surface form and the SVF difference map derived from two SVF raster (GB - GBH). The SVF difference average value explains the tree effect which mitigates micro-climate as a land cover lessens solar radiation on hot summer days. A further application research study about the high-resolution SVF map should follow to develop scientific knowledge and support climate-friendly urban planning. 하늘시계지수(Sky View Factor: SVF)는 도시의 토지이용으로 만들어지는 피복의 외형과 미기후 상호작용을 설명하는 지표이다. 이 연구에서는 도시 규모의 고해상도(2m) 하늘시계지수 지도를 개발하고 활용 방향을 모색하였다. 연구대상지는 인구 130만 명에 육박하는 수원특례시 행정구역(121.04 km²)으로 항공 라이다 기반 3차원 점군 자료가 입력 자료로 적용되었다. 높이 2m 이상의 수목을 반영하지 않은 사례(GB)와 반영한 사례(GBH)로 고해상도 하늘시계지수를 구축하고, 이 두 자료의 차이로부터 수목의 효과(Diff)를 계량적으로 구하고 공간적 분포를 조사하였다. 결과적으로, 이 연구를 통해서 작성된 각각의 도시 규모의 고해상도 하늘시계지수 지도는 도시의 토지이용 형태 및 이로 인한 미기후 영향을 시각적·통계적으로 잘 보여주고 설명하고 있었다. 건물·식생의 입체적인 외형은 기후변화 적응 관리 측면에서 중요하게 고려할 요소이지만 지금까지는 과학적 도시계획·관리 방법론을 적용하기가 어려웠다. 향후 고해상도 하늘시계지수 지도를 활용한 다양한 응용영역들이 과학적 지식을 발전시키고 기후 친화적으로 도시를 계획할 수 있도록 지원해야 할 것이다.

Analysis of GNSS Performance Index Using Feature Points of Sky-View Image

Woonki Hong,Kwangsik Choi,Eunsung Lee,Sunghyuck Im,Moonbeom Heo IEEE 2014 IEEE transactions on intelligent transportation sy Vol.15 No.2

<P>When sky-view factor (SVF) is used to predict the positioning performance of the global navigation satellite system (GNSS), it is easy to use the SVF as a performance index without a specific database, as it is used for topographic maps, not only in an open-sky land but also in regions where there are many tall buildings. However, conventional SVF is only able to express the degree of openness of the sky as a ratio, and it is limited to being used as a performance index for the positioning that uses the GNSS. When the conventional SVF is used in a land transportation environment, the predicted value for the positioning performance of the GNSS is often not consistent with the actual positioning error, but when sky-view-based dilution of precision (SVDOP) is applied, we confirmed that it was substantially close to the actual positioning error. This confirms our expectation that the utilization of the proposed method rather than the utilization of SVF alone in land transportation environments will make the analysis easier. In this paper, the SVDOP is calculated with real Global Positioning System data, and its usefulness is validated by comparing it with the conventional SVF and the DOP.</P>

도시 차원의 건물 음영을 고려한 일사량 계산 모듈 개발에 관한 연구

김의종(Kim, Eui-Jong) 대한건축학회 2014 대한건축학회논문집 Vol.30 No.7

Recently, development of detailed urban energy consumption prediction tools becomes a rising issue as it can provide more quantitative and qualitative information for planning a sustainable city. One of the target physical phenomena related to the urban case is to correctly calculate the solar irradiance on building envelops with taking into account the shading and mask effects. The sunlit fraction(SF) is commonly used to calculate the effective beam solar irradiance, and the sky-view factor(SVF) is used for the precise diffuse irradiance in the urban context. Both indicators are also employed in this work, and they are calculated using the polygon clipping method. The proposed solar insolation calculation module is implemented in Python, and results from the module are compared with existing SketchUp Plug-in tools. Results show that SF and SVF obtained from the module are almost the same as the existing tools, giving only less than 2% errors over the year. A case study is also carried out for comparison between the urban case and the single building case. As expected, total monthly insolation in the single building case is overestimated with a mean difference of about 20%.

하계 그늘쉼터 유형별 장·단파복사 관측과 해석

백창현,최동호,이부용,이인규 한국태양에너지학회 2019 한국태양에너지학회 논문집 Vol.39 No.6

In this study, we analyzed the relationship between five factors: long-wave radiation, short-wave radiation, cloudiness, SVF and summer shelters. In the previous study, we recognized the correlation between single building SVF and long-wave radiation. Furthermore, this study attempted to confirm the relationship at the summer shelter with high solar radiation blocking rate. The observations are as follows. ① Cooling in summer shelters was not the effect of temperature but the effect of radiation reduction due to short-wave radiation shielding. ② In the case of the canopy tent with low heat capacity, the long-wave radiation was observed to be 16.7% higher per hour than the comparison control point due to the increase in surface temperature. ③ The long-wave radiation increase rate was different according to SVF, but showed very similar pattern according to the material characteristics of the summer shelters. ④ Passive Cooling effect on the type of summer shelters are determined by the size of the total long and short-wave radiation at that point.

도시의 물리적 환경이 시간대별 대기온도에 미치는 영향 분석

하재현,이수기,박철영 한국도시행정학회 2015 한국도시행정학회 학술발표대회 논문집 Vol.2015 No.12

도시의 성장과 공간적 확장은 불투수면의 증가와 오픈스페이스의 감소를 가져왔고 개발밀도가 높은 도시지역이 주변지역보다 대기온도가 상승하는 도시열섬현상을 야기하였다. 도시의 열섬저감과 열환경 개선을 위해 입체적인 도시공간 특성인 천공개폐율(Sky View Factor)개념이 분석에 활용되고 있으며, 고층·고밀 개발로 조성된 도시공간의 미기후를 설명하는 중요한 요소로 주목받고 있다. 그러나 천공개폐율과 대기온도간의 관계는 분석지역 및 시점에 따라 다르게 나타나고 있어 천공개폐율이 대기온도에 미치는 영향에 대한 확증적인 연구가 부족한 실정이다. 본 연구는 천공개폐율 개념에 집중하여 도시의 물리적인 환경 및 미기후 특성이 주간‧야간시간대 대기온도에 미치는 영향을 살펴보았다. 이와 함께 용적률에 따라 분석대상지를 유형화하여, 유형별로 천공개폐율 특성이 대기온도에 미치는 영향이 어떠한 차이를 보이는지에 대해 파악하였다. 전체유형을 대상으로 한 분석의 경우, 천공개폐율은 주간 및 야간시간대의 대기온도 저감에 기여하는 것으로 파악되었다. 그러나 유형별로 각각 분석을 시행한 결과, 용적률 및 시간대에 따라 천공개폐율이 대기온도에 미치는 영향이 차이를 보이는 것으로 나타났다. 이러한 결과는 도시지역의 용적률, 천공개폐율, 바람속도가 종합적으로 대기온도에 영향을 미친다는 점에서 설명될 수 있다. 본 연구의 결과는 용적률에 따른 천공개폐율의 대기온도에 대한 영향을 파악하고, 이를 통해 건축물 규제 또는 도시계획 및 설계 지침마련에 있어 그 활용가능성이 높다는 점에서 의의를 가진다. During the past several decades, metropolitan areas in Korea have experienced significant urbanization and industrialization, which increased impervious surfaces and decreased green space. The results of substantial urbanization and high-density development have caused the urban heat island(UHI) effect which increases urban air temperature compared to surrounding areas. The city of Seoul, which has high-density built environment, has shown UHI effect during the summer. Therefore, many researchers are interested in the determinant factors of UHI. Recently, sky view factor(SVF) which indicates the built environmental properties including the characteristics of buildings and open space, is taken on notice as an important three dimensional urban factor that may influence urban thermal environments. However, the relationship between SVF and air temperature has not clearly addressed in the previous literature. The previous studies show inconsistent results by its study area and time period. This study examines the relationship between SVF and air temperature considering built environments such as floor area ratio(FAR), elevation, humidity, and wind speed using the data from “SK Weather Planet API”. The SK Weather Planet data includes the meteorological observation from the 277 Automatic Weather Stations(AWS) located in Seoul. The results of this study indicate that SVF has a negative effect on air temperature, both in day and night time. In other words, as SVF increases, air temperature decreases. However, the results of the analysis for the each type of urban area classified by FAR showed that SVF can both increase and decrease air temperature depending on the level of FAR. This study has verified different spatial and temporal effects of SVF on air temperature. This study suggests policy implications to improve the urban thermal environment regarding development density and SVF in urban design practices.

Three‐dimensional point cloud based sky view factor analysis in complex urban settings

An, S. M.,Kim, B. S.,Lee, H. Y.,Kim, C. H.,Yi, C. Y.,Eum, J. H.,Woo, J. H. John Wiley Sons, Ltd 2014 International journal of climatology Vol.34 No.8

<P><B>ABSTRACT</B></P><P>Quantitatively describing effects caused by trees is a challenging issue for sky view factor (SVF) studies. The complex geometrical shapes of trees and the seasonally changing canopy volume caused by leaf growth and defoliation have forced SVF users to disregard trees in their analyses or to apply a simple geometric object, such as a rectangular pole or vertically elongated ellipsoid. The three‐dimensional point cloud (3DPC) method is useful for quantitative analysis of urban settings by describing the structured spatial complex in detail, not only by shape itself but also with many meaningful indices such as SVF. We here proposed a new SVF analysis method based on 3DPC. Stereoscopic projection was applied to project 3DPC on the virtual hemisphere. From intensive analysis of 3DPC SVF in a normal urban complex area, we discerned the effects caused by trees. The results showed that the tree effect derived from 3DPC SVF in an urban complex is clearly described by a comparison between two cases (trees and no trees). Trees with topography play an important role and contribute to the heat balance in an urban complex.</P>

하늘시계지수 비교 및 도시기온 상관성 연구: 강남 선정릉지역을 중심으로

이채연,신이레,안승만 한국기상학회 2017 대기 Vol.27 No.4

Sky view factor can quantify the influence of complex obstructions. This study aims to evaluate the best available SVF method that represents an urban thermal condition with land cover in complex city of Korea and also to quantify a correlation between SVF and mean air temperature; the results are as follows. First, three SVF methods comparison result shows that urban thermal study should consider forest canopy induced effects because the forest canopy test (on/off) on SVF reveals significant difference range (0.8, between maximum value and minimum value) in comparison with the range (0.1~0.3) of SVFs (Fisheye, SOLWEIG and 3DPC) difference. The significance is bigger as a forest cover proportion become larger. Second, Rsquare between SVF methods and urban local mean air temperature seems more reliable at night than a day. And as the value of SVF increased, it showed a positive slope in summer day and a negative slope in winter night. In the SVF calculation method, Fisheye SVF, which is the observed value, is close to the 3DPC SVF, but the grid-based SWG SVF is higher in correlation with the temperature. However, both urban climate monitoring and model/analysis study need more development because of the different between SVF and mean air temperature correlation results in the summer night period, which imply other major factors such as cooling air by the forest canopy, warming air by anthropogenic heat emitted from fuel oil combustion and so forth.

도시지역의 물리적 환경요소가 복사에너지 흐름에 미치는 영향

송봉근 ( Bong Geun Song ),박경훈 ( Kyung Hun Park ) 한국환경영향평가학회 2014 환경영향평가 Vol.23 No.6

The purpose of this study is to develop urban planning for mitigating thermal comfort by analyzing the relationship between various physical environmental factors and radiation fluxes focused on urban areas of Changwon city, Gyeongsangnam-do. Physical environmental factors were analyzed by sky view factor (SVF), land cover and land use types using GIS program. Radiation fluxes were measured upward and downward in solar and terrestrial radiation by mobile measurement during 3 days (2 daytime and 1 nighttime) in summer season. SVF is high in urban park less around buildings. High dense building sites were low. Downward solar radiation fluxes were the highest about 700W/m2 at daytime, and decreased in spatial type arranged dense buildings. Upward solar and terrestrial radiations was affected by land cover types that have thermal features such as reflectivity, emissivity, and heat capacity. Therefore, urban space needs appropriate planning with building arrangement, green walls and land cover replacement for mitigating thermal comfort in urban area.

수치표고모델과 태양복사모델을 이용한 기상청 일사 관측소 관측환경 분석

지준범,조일성,김부요,이규태 한국지구과학회 2019 韓國地球科學會誌 Vol.40 No.2

In order to analyze the observational environment of solar radiation stations operated by the Korea Meteorological Administration (KMA), we used the digital elevation model (DEM) and the solar radiation model to calculate a topographical shading, sky view factor (SVF) and solar radiation by surrounding terrain. The sky line and SVF were calculated using high resolution DEM around 25 km of the solar stations. We analyzed the topographic effect by analyzing overlapped solar map with sky line. Particularly, Incheon station has low SVF whereas Cheongsong and Chupungryong station have high SVF. In order to validation the contribution of topographic effect, the solar radiation calculated using GWNU solar radiation model according to the sky line and SVF under the same meteorological conditions. As a result, direct, diffuse and global solar radiation were decreased by 12.0, 5.6, and 4.7% compared to plane surface on Cheongsong station. The 6 stations were decreased amount of mean daily solar radiation to the annual solar radiation. Among 42 stations, eight stations were analyzed as the urgent transfer stations or moving equipment quickly and more than half of stations (24) were required to review the observational environment. Since the DEM data do not include artifacts and vegetation around the station, the stations need a detail survey of observational environment. 기상청 일사관측소 관측환경 분석을 위하여 수치표고모델(DEM)과 태양복사모델을 이용하여 주변지형에 의한 차폐와 하늘시계요소(SVF) 및 일사량을 산출하였다. 지형고도자료(10 m 해상도)를 통해 관측소를 중심으로 주변 25km내의 지형들을 이용하여 스카이라인과 SVF를 계산하였다. 또한, 일사관측소별 산출된 천기도와 스카이라인을 중첩하여 지형에 의한 차폐를 분석하였다. 특히 인천 관측소는 주변지형의 차폐가 적었고 청송군과 추풍령 관측소는 주변 지형에 의한 차폐가 큰 관측소로 나타났다. 태양복사모델을 이용하여 동일 조건에서 지형 특성에 따른 일사량을 산출하여 지형에 의한 기여도를 분석하였다. 연누적 일사량 계산결과, 청송군 관측소의 경우 수평면 일사량과 비교하였을 때 직달일사량은 12.0% 이상 차폐되었고 산란일사량은 5.6% 그리고 전천일사량은 4.7% 감소하였다. 평균 일누적 일사량을 기준으로 편차를 분석하였을 때 0.3% 이상 전천일사량이 감소되는 지점은 6개 관측소였다. 42개 관측소 중 8소는 관측소의 이전 또는 관측장비의 이동설치가 시급한 것으로 분석되었고 1/2 이상(24소)의 관측소는 일사관측환경에 대한 검토가 필요한 것으로 분석되었다. DEM자료는 관측소 주변의 인공구조물과 식생 등이 포함되지 않기 때문에 더 상세한 관측환경분석이 요구된다.