Major environmental factors and traits of invasive alien plants determining their spatial distribution

오민우,허윤정,이은주,이효혜미 한국생태학회 2021 Journal of Ecology and Environment Vol.45 No.4

Background: As trade increases, the influx of various alien species and their spread to new regions are prevalent and no longer a special problem. Anthropogenic activities and climate changes have made the distribution of alien species out of their native range common. As a result, alien species can be easily found anywhere, and they have nothing but only a few differences in intensity. The prevalent distribution of alien species adversely affects the ecosystem, and a strategic management plan must be established to control them effectively. To this end, hot spots and cold spots were analyzed according to the degree of distribution of invasive alien plants, and major environmental factors related to hot spots were found. We analyzed the 10,287 distribution points of 126 species of alien plants collected through the national survey of alien species by the hierarchical model of species communities (HMSC) framework. Results: The explanatory and fourfold cross-validation predictive power of the model were 0.91 and 0.75 as AUC values, respectively. The hot spots of invasive plants were found in the Seoul metropolitan area, Daegu metropolitan city, Chungcheongbuk-do Province, southwest shore, and Jeju island. Generally, the hot spots were found where the higher maximum temperature of summer, precipitation of winter, and road density are observed, but temperature seasonality, annual temperature range, precipitation of the summer, and distance to river and sea were negatively related to the hot spots. According to the model, the functional traits accounted for 55% of the variance explained by the environmental factors. The species with higher specific leaf areas were more found where temperature seasonality was low. Taller species preferred the bigger annual temperature range. The heavier seed mass was only preferred when the max temperature of summer exceeded 29 °C. Conclusions: In this study, hot spots were places where 2.1 times more alien plants were distributed on average than non-hot spots (33.5 vs 15.7 species). The hot spots of invasive plants were expected to appear in less stressful climate conditions, such as low fluctuation of temperature and precipitation. Also, the disturbance by anthropogenic factors or water flow had positive influences on the hot spots. These results were consistent with the previous reports about the ruderal or competitive strategies of invasive plants instead of the stress-tolerant strategy. The functional traits are closely related to the ecological strategies of plants by shaping the response of species to various environmental filters, and our result confirmed this. Therefore, in order to effectively control alien plants, it is judged that the occurrence of disturbed sites in which alien plants can grow in large quantities is minimized, and the river management of waterfronts is required. Background: As trade increases, the influx of various alien species and their spread to new regions are prevalent and no longer a special problem. Anthropogenic activities and climate changes have made the distribution of alien species out of their native range common. As a result, alien species can be easily found anywhere, and they have nothing but only a few differences in intensity. The prevalent distribution of alien species adversely affects the ecosystem, and a strategic management plan must be established to control them effectively. To this end, hot spots and cold spots were analyzed according to the degree of distribution of invasive alien plants, and major environmental factors related to hot spots were found. We analyzed the 10,287 distribution points of 126 species of alien plants collected through the national survey of alien species by the hierarchical model of species communities (HMSC) framework. Results: The explanatory and fourfold cross-validation predictive power of the model were 0.91 and 0.75 as AUC values, respectively. The hot spots of invasive plants were found in the Seoul metropolitan area, Daegu metropolitan city, Chungcheongbuk-do Province, southwest shore, and Jeju island. Generally, the hot spots were found where the higher maximum temperature of summer, precipitation of winter, and road density are observed, but temperature seasonality, annual temperature range, precipitation of the summer, and distance to river and sea were negatively related to the hot spots. According to the model, the functional traits accounted for 55% of the variance explained by the environmental factors. The species with higher specific leaf areas were more found where temperature seasonality was low. Taller species preferred the bigger annual temperature range. The heavier seed mass was only preferred when the max temperature of summer exceeded 29 °C. Conclusions: In this study, hot spots were places where 2.1 times more alien plants were distributed on average than non-hot spots (33.5 vs 15.7 species). The hot spots of invasive plants were expected to appear in less stressful climate conditions, such as low fluctuation of temperature and precipitation. Also, the disturbance by anthropogenic factors or water flow had positive influences on the hot spots. These results were consistent with the previous reports about the ruderal or competitive strategies of invasive plants instead of the stress-tolerant strategy. The functional traits are closely related to the ecological strategies of plants by shaping the response of species to various environmental filters, and our result confirmed this. Therefore, in order to effectively control alien plants, it is judged that the occurrence of disturbed sites in which alien plants can grow in large quantities is minimized, and the river management of waterfronts is required.

Monitoring trends in global vegetation fire hot spots using MODIS data

C. Sudhakar Reddy,N. Sarika 대한공간정보학회 2022 Spatial Information Research Vol.30 No.5

We identified hot spots trends in global vegetation fires based on 10-year long MODIS fire products. Additionally, we analyzed the occurrence of fire hot spots across climate zones, global land cover and global biodiversity hot spots. Fire hot spot zones were delineated by combining annual fire data with spatial statistics and space– time pattern mining. Spatial analysis shows no statistically significant trends of increase or decrease of vegetation fires from 2011 to 2020. Within the global vegetation fire hot spots, intensifying hot spots (38.1%) dominate followed by consecutive hot spots (30.5%), persistent hot spots (14.2%), sporadic hot spots (6.2%), oscillating hot spots (4.6%) and new hot spots (3.5%). The results shows that Africa has the highest fire hot spot area in the world which was dominated by a tropical savanna and hot semi-arid (steppe) climates. Future efforts should be focused towards the standardization of the techniques to enable identification of near real time vulnerable zones, predict fire risk areas, and evaluation of the management effectiveness for climate change mitigation and conservation policies.

Reexamination of Photovoltaic Hot Spotting to Show Inadequacy of the Bypass Diode

Kim, Katherine A.,Krein, Philip T. IEEE 2015 IEEE journal of photovoltaics Vol.5 No.5

<P>Hot spotting is a reliability problem in photovoltaic (PV) panels where a mismatched cell heats up significantly and degrades panel performance. High temperatures due to hot spotting can damage cell encapsulant and lead to second breakdown; both cause permanent damage to the PV panel. Although bypass diodes are used for protection and qualification tests are used to reduce cell mismatch, these strategies are shown to be insufficient for hot spot prevention. This paper reexamines the hot spot problem in PV strings through simulation and load-line analysis. Results show that cells in typical panel string lengths are susceptible to hot spotting because of reverse bias behavior. A number of existing and emerging solutions aimed at hot spot prevention are discussed and evaluated. Commercially available active bypass switches are an improvement over passive diodes but do not prevent hot spotting. Cells with low breakdown voltages limit power dissipation but are not fully vetted as a long-term solution. A combination of hot spot detection and open-circuit protection is a complete solution to hot spotting.</P>

도시 열환경 개선을 위한 바람길 관리 전략 - 김해시를 사례로 -

엄정희,손정민,서경호,박경훈 한국지리정보학회 2018 한국지리정보학회지 Vol.21 No.1

This study aims to propose management strategies of ventilation paths for improving urban thermal environments. For this purpose, Gimhae-si in Gyeongsangnamdo was selected as a study area. We analyzed hot spots and cool spots in Gimhae by using Landsat 8 satellite image data and spatial statistical analysis, and finally derived the vulnerable areas to thermal environment. In addition, the characteristics of ventilation paths including wind direction and wind speed were analyzed by using data of the wind resource map provided by Korea Meteorological Administration. As a result, it was found that a lot of hot spots were similar to those with weak wind such as Jinyoung-eup, Jillye-myeon, Juchon-myeon and the downtown area. Based on the analysis, management strategies of ventilation paths in Gimhye were presented as follows. Jinyoung-eup and Jillye-myeon with hot spot areas and week wind areas have a strong possibility that hot spot areas will be extended and strengthened, because industrial areas are being built. Hence, climate-friendly urban and architectural plans considering ventilation paths is required in these areas. In Juchon-myeon, where industrial complexes and agricultural complexes are located, climate-friendly plans are also required because high-rise apartment complexes and an urban development zone are planned, which may induce worse thermal environment in the future. It is expected that a planning of securing and enlarging ventilation paths will be established for climate-friendly urban management. and further the results will be utilized in urban renewal and environmental planning as well as urban basic plans. In addition, we expect that the results can be applied as basic data for climate change adaptation plan and the evaluation system for climate-friendly urban development of Gimhye. 본 연구는 경상남도 김해시를 사례지역으로 선정하여, 열환경을 지속적으로 개선하기 위한 바람길 관리 방안을 제시하고자 한다. 이를 위해, Landsat 8 위성영상자료 및 공간통계 분석을 통해김해시 열섬의 Hot spot과 Cool spot 지역을 도출하고, 김해시의 열환경 취약지역을 파악하였다. 또한, 기상청에서 제공하는 풍력자원지도를 활용하여 김해시 바람길의 풍향 및 풍속을 분석을 하였다. 그 결과, Hot spot 지역인 진영읍, 진례면, 주촌면, 도심지 일대가 바람이 약한 지역과 유사한 것으로 나타났으며, 이는 도시의 기온과 바람 형성이 지형 및 토지이용의 변화에 따라 영향을많이 받기 때문인 것으로 판단된다. 분석을 바탕으로 김해시의 바람길 관리 전략을 제시하면 다음과 같다. Hot spot 지역과 바람이 약한 지역에는 공통적으로 농업 및 공업단지가 분포하고 있었는데, 산업단지가 조성되어 있거나 조성중인 진영읍과 진례면에서 Hot spot 지역이 확대·강화될 우려가 있으므로, 바람길을 고려한 도시 및 건축계획이 요구된다. 산업단지 및 농공단지가 위치해 있는 주촌면은 고층 아파트 및 주촌선천지구 도시개발지구가 들어설 예정이므로, 현재에도 취약한열환경이 향후 더 악화될 수 있으므로 이를 고려한 계획이 요구된다. 본 연구를 바탕으로 기후친화적 도시개발을 위한 바람길 계획을 수립하여 도시기본계획뿐만 아니라 도시재생 및 환경계획 분야에서 활용할 수 있을 것으로 기대한다. 또한, 김해시의 기후변화 적응계획 수립을 위한 기초자료 및 기후친화적인 도시개발을 위한 평가시스템을 구축하는데 적용할 수 있을 것으로 기대한다.

Hot Spot Detection of Thermal Infrared Image of Photovoltaic Power Station Based on Multi-Task Fusion

Xu Han,Xianhao Wang,Chong Chen,Gong Li,Chang-hao Piao 한국정보처리학회 2023 Journal of information processing systems Vol.19 No.6

The manual inspection of photovoltaic (PV) panels to meet the requirements of inspection work for large-scalePV power plants is challenging. We present a hot spot detection and positioning method to detect hot spots inbatches and locate their latitudes and longitudes. First, a network based on the YOLOv3 architecture wasutilized to identify hot spots. The innovation is to modify the RU_1 unit in the YOLOv3 model for hot spotdetection in the far field of view and add a neural network residual unit for fusion. In addition, because of themisidentification problem in the infrared images of the solar PV panels, the DeepLab v3+ model was adoptedto segment the PV panels to filter out the misidentification caused by bright spots on the ground. Finally, thelatitude and longitude of the hot spot are calculated according to the geometric positioning method utilizingknown information such as the drone's yaw angle, shooting height, and lens field-of-view. The experimentalresults indicate that the hot spot recognition rate accuracy is above 98%. When keeping the drone 25 m off theground, the hot spot positioning error is at the decimeter level.

Major environmental factors and traits of invasive alien plants determining their spatial distribution

Oh, Minwoo,Heo, Yoonjeong,Lee, Eun Ju,Lee, Hyohyemi The Ecological Society of Korea 2021 Journal of Ecology and Environment Vol.45 No.1

Background: As trade increases, the influx of various alien species and their spread to new regions are prevalent and no longer a special problem. Anthropogenic activities and climate changes have made the distribution of alien species out of their native range common. As a result, alien species can be easily found anywhere, and they have nothing but only a few differences in intensity. The prevalent distribution of alien species adversely affects the ecosystem, and a strategic management plan must be established to control them effectively. To this end, hot spots and cold spots were analyzed according to the degree of distribution of invasive alien plants, and major environmental factors related to hot spots were found. We analyzed the 10,287 distribution points of 126 species of alien plants collected through the national survey of alien species by the hierarchical model of species communities (HMSC) framework. Results: The explanatory and fourfold cross-validation predictive power of the model were 0.91 and 0.75 as AUC values, respectively. The hot spots of invasive plants were found in the Seoul metropolitan area, Daegu metropolitan city, Chungcheongbuk-do Province, southwest shore, and Jeju island. Generally, the hot spots were found where the higher maximum temperature of summer, precipitation of winter, and road density are observed, but temperature seasonality, annual temperature range, precipitation of the summer, and distance to river and sea were negatively related to the hot spots. According to the model, the functional traits accounted for 55% of the variance explained by the environmental factors. The species with higher specific leaf areas were more found where temperature seasonality was low. Taller species preferred the bigger annual temperature range. The heavier seed mass was only preferred when the max temperature of summer exceeded 29 ℃. Conclusions: In this study, hot spots were places where 2.1 times more alien plants were distributed on average than non-hot spots (33.5 vs 15.7 species). The hot spots of invasive plants were expected to appear in less stressful climate conditions, such as low fluctuation of temperature and precipitation. Also, the disturbance by anthropogenic factors or water flow had positive influences on the hot spots. These results were consistent with the previous reports about the ruderal or competitive strategies of invasive plants instead of the stress-tolerant strategy. The functional traits are closely related to the ecological strategies of plants by shaping the response of species to various environmental filters, and our result confirmed this. Therefore, in order to effectively control alien plants, it is judged that the occurrence of disturbed sites in which alien plants can grow in large quantities is minimized, and the river management of waterfronts is required.

L-function과 KDE를 이용한 서울시 보행교통사고 잦은 곳의 공간적 범위 설정과 특성 분석

황정현(HWANG, Junghyun),고준호(KO, Joonho) 대한교통학회 2024 대한교통학회지 Vol.42 No.3

본 연구는 보행교통사고 잦은 곳의 적정 공간적 범위 설정을 위해 보행교통사고에 대한 점 패턴 분석과 보행교통사고 잦은 곳의 공간적 특성을 분석하였다. 분석은 광역자치단체 중 전체 교통사고 사망자 대비 보행자 사망자 비율이 가장 높은 서울특별시의 2016년에서 2022년까지 발생한 보행교통사고를 대상으로 하였다. 보행교통사고 데이터의 점 패턴 간 공간 의존성을 분석하기 위해 Ripley의 K-function 및 L-function을 사용하여 거리별 군집화 정도를 분석한 결과, 각 연도별 보행교통사고는 개별 사고 간의 공간적 의존성을 지닌 군집화된 상태이며 공간적 패턴의 군집화는 30.7m 거리까지 L-function 값이 급격히 증가되고 그 이상의 거리에서는 서서히 완화되는 것으로 나타났다. 또한, 동일한 방법으로 차대차 및 차량단독 교통사고의 군집화를 분석한 결과는 35.7m의 거리로 나타나 보행교통사고의 군집 패턴보다 1.16배 큰 것으로 나타났다. L-function에 의해 선정된 결과의 적용 가능성을 Buffer 반경 5m에서 50m까지 5m 간격의 Kernel Density Estimation로 분석한 보행사고 Hot Spot을 통해 검증한 결과, Hot Spot의 총량은 Buffer 반경 30m~35m에서 10% 미만으로 완만하게 증가하고 있으며 해당 거리 이상에서 총량 증가 폭은 더 완만해졌다. 하지만, Buffer 반경이 커질수록 인접도로의 교통사고를 포함하는 결과를 보여주고 있어 Hot Spot을 식별하는 최소 거리로 30m를 선택하는 것은 중요한 의미를 지닌다. 30m 반경 보행교통사고 잦은 곳의 공간적 특성 분석을 위해 교차로, 도로폭, 토지이용 등의 자료와 공간분석한 결과, 광로 및 대로 보다는 중로, 소로에서 보행교통사고 잦은 곳의 비율이 더 높으며, 교차로보다는 무신호 도로에서의 보행교통사고 위험성이 더 높은 것으로 분석되어 주거생활권 도로에 대한 보행안전정책이 지속적으로 추진되어야 함을 시사하고 있다. This study aimed to undertake a comprehensive spatial analysis to delineate optimal spatial ranges for identifying frequent pedestrian crash locations. The analysis focused on pedestrian crashes that occurred within the seoul metropolitan government area between 2016 and 2022, selected due to its significantly high ratio of pedestrian fatalities compared to overall traffic accident fatalities among metropolitan jurisdictions. To investigate the spatial dependence among point patterns of pedestrian crash data, ripleys k-function and l-function were employed to analyze the degree of clustering by distance. The findings indicate that pedestrian crashes each year exhibited clustered patterns characterized by spatial dependence among individual crash points, with clustering evident within distances of 30.7 meters as indicated by the rate of increases in l-function values, gradually tapering off beyond this range. Furthermore, a similar analysis conducted on non-pedestrian crashes revealed clustering within distances of 35.7 meters, approximately 1.16 times the observed clustering range for pedestrian crashes. Based on the application of l-function selected results, which identified pedestrian crash hot spots, and reviewing the kernel density estimation within 5 meter increments up to a 50 meter radius, the total count of hot spots shows a gradual increase, with less than 10% within buffer radius of 30 to 35 meters. Beyond this distance, the rate of increase diminishes more steeply. Moreover, the results indicate that expanding the buffer radius includes accidents on adjacent roads. Therefore, selecting a minimum distance of 30 meters for hot-spot analysis is meaningful. Spatial analysis of pedestrian crash hot spots based on intersection, road width, and land use metrics revealed higher proportions of hot spots along secondary and tertiary roads compared to main arteries, with higher risk associated with unsignalized roads than signalized intersections. This underscores the necessity for ongoing pedestrian safety policies targeting residential roadways.

Hot Spot의 시각적 분석을 통한 Hot Judder 저감의 실험적 연구

조상운(Sangwoon Cho),황선덕(Sunduk Hwang),장진성(Jinsung Jang),이정주(Jungju Lee),권성욱(Sungwook Kwon) 한국자동차공학회 2011 한국자동차공학회 학술대회 및 전시회 Vol.2011 No.11

This paper introduces hot judder, among the issues of NVH braking system, caused by hot spot on disc that generates unpleasant, anxious experience to the driver. Hot Judder generates around low frequency, effected by order analysis from the velocity of disc rotation. It is a phenomenon, which caused by occurrence of hot spot due to friction between disc and pad. Hot spot is the cause of the hot judder vibration. It transferred chassis, brake pedal and steering that is generated judder vibration. This study analyzes the cause of hot judder, according to the shape and property of a brake pad (type of slot, size of chamfer, compression rate and under layer). Thermal IR camera was used to visual analysis thermal behaviour and hot spot generation of disc. Correlation of DTV, BTV and thermal visual analysis were studied to analyze the cause of hot judder reduction.

비 공간적 임대료규제 이후 전ㆍ월세시장의 공간적 결과: 발생 핫스팟 분석을 통한 시공간 패턴 유형화를 중심으로

신혜영,강승범 SH공사 도시연구원 2023 주택도시연구 Vol.13 No.3

이 연구는 전국적인 임대료규제 시행 이후 전ㆍ월세 시장의 시공간적 패턴을 통하여 비 공간적 임대료규제의공간적 결과에 대한 실증적 근거를 제공한다. 연구 과정은 다음과 같다. 첫째, 서울을 대상으로 월세와 전세시장에서 표준화 된 거래 데이터를 통해 행정동 단위의 17개 시공간 패턴으로 분류하였다. 둘째, 특정 패턴에서나타나는 공간 특성을 탐구하기 위해 로지스틱 회귀분석을 실시하였다. 그 결과 임대료규제 실시 후 시공간패턴이 행정동과 주택시장에 따라 이질성이 강하다는 증거를 도출하였다. 일반적으로 월세시장은 전세시장에비해 전셋값이 빠르게 상승하는 경향을 보이며, 상당수의 행정동에서 통계적으로 유의한 핫스팟 및 콜드스팟패턴으로 분류되어, 임대료규제 시행 후 서울의 가격 동향이 시간이 지남에 따라 공간적으로 이질적이라는것을 시사한다. 구체적으로, 전세시장에서는 저층 주거지와 대규모 아파트가 밀집한 동네에 핫스팟이, 강남권역세권을 중심으로 고가 아파트가 밀집한 동네에 콜드스팟의 결과가 도출되었다. 월세시장의 경우 서울 구도심과 가까운 동네, 외국인 밀집지역에 핫스팟이 도출되었으며, 반면 저층 주거지와 대학이 밀집한 동네에는콜드스팟이 도출되었다. 한편, 기초생활수급자의 저소득인구의 규모는 전세와 월세 모두 연속적 핫스팟 지역이형성될 가능성이 높은 것으로 나타났다. 이는 임대차 상승이 저소득임차인 거주지역과 공간적으로 중첩됨을시사한다. 해당 연구는 비 공간적 임대규제로 인해 공간적으로 불균등한 결과와 함께 정책적 기대와 달리특정 취약계층의 주거비 부담을 악화시킬 수 있음을 시사하는 증거를 도출하였다. This study aimed to provide empirical evidence on spatiotemporal patterns of rental transaction prices in Seoul after the implementation of rent regulations, widely referred to as the Lease 3 Law, in July 2020. We first conducted the emerging hot-spot analysis at a neighborhood level by analyzing rent transaction data for two distinct rental submarkets: (1) the market for monthly paying renters and (2) the market for Jeonse renters (those who only pay a deposit to landlords). This study analyzed data for 18 months following the implementation of the new legislation. Through emerging hot-spot analysis, we classified all 424 neighborhoods in Seoul into 17 spatiotemporal types. After the classification, we estimated a series of binomial logistic models to explore the characteristics of the neighborhoods that belong to a certain hot- or cold-spot type. The results indicated that, after the implementation, spatiotemporal patterns of rent prices substantially varied across neighborhoods. We identified multiple statistically significant hot- or cold-spot neighborhoods, suggesting that, after the implementation, the direction and the magnitude of rent price changes varied across different neighborhoods. In the case of the Jeonse market, hot-spot neighborhoods tend to be located where low-rise dwellings and large-scale apartments are concentrated, whereas cold spots tend to be located in neighborhoods with expensive apartments near subway stations in the Gangnam area. In the case of the market for monthly-paying renters, hot spots tend to be foreigner-heavy neighborhoods around old city cores. Cold spots are typically found in neighborhoods where low-rise dwellings and universities are concentrated. The findings also indicated that some hot-spot neighborhoods are positively associated with poverty, while some cold-spot neighborhoods are negatively associated with poverty. While acknowledging the preliminary nature of these findings and the need for further research, this study underscores the potential for geographically disparate consequences arising from nonspatial rent regulations.

컨시스턴스 해슁을 이용한 분산 웹 캐싱 시스템의 성능 향상을 위한 Hot Spot 예측 방법

정성칠,정길도 한국통신학회 2004 韓國通信學會論文誌 Vol.29 No.5B

월드 와이드 웹에서 사용자의 요청에 대한 웹 서버의 신속하고 정확한 서비스는 매우 중요하다. 그러나 최근에 는 인터넷 사용자의 급속한 증가로 인하여 신속한 서비스가 어려운 상황이다. 이러한 문제를 해결하기 위해 분산 웹 캐싱이 사용되고 있다. 분산 웹 캐싱의 성능은 히트 율에 의해서 결정되며 히트 율은 메모리 사이즈, 서버의 처리속도, 로드밸런싱 등의 영향을 받는다. 기존의 로드밸런싱은 주로 현재의 시스템 상태를 기준으로 실시하고 있으나, 미래에 발생할 서비스를 예측하는 방법을 이용하여 로드밸런싱을 실시함으로써 히트 율의 향상이 가능하다. 본 연i레서는 웹 서버 또는 프록시에 요청하는 가장 빈번한 hot spot을 예측하구 예측된 hot spot을 공유하고 있는 프록시에 미리 패치함으로써 프록시의 활용을 개선하는 Hot Spot Prediction Method (HSPM)을 제안한다. 시뮬레이션을 통하여 제안한 방법이 기존의 consistent hashing보다 로드밸런싱, 히트 율 측면에서 우수함을 확인하였다. The fast and Precise service for the users request is the most important in the World Wide Web. However, the lest service is difficult due to the rapid increase of the Internet users recently. The Shared Web Caching (SWC) is one of the methods solving this problem. The performance of SWC is highly depend on the hit rate and the hit rate is effected by the memory size, processing speed of the server, load balancing and so on. The conventional load balancing is usually based on the state history of system, but the prediction of the state of the system can be used for the load balancing that will further improve the hit rate. In this study, a Hot Spot Prediction Method (HSPM) has been suggested to improve the throughputs of the proxy. The predicted hot spots, which is the item most frequently requested, should be predicted beforehand. The result show that the suggested method is better than the consistent hashing in the point of the load balancing and the hit rate.