• 대한원격탐사학회지
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• 제28권3호
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• pp.307-318
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• 2012

To understand forest structures, the Geoscience Laser Altimeter System (GLAS) instrument have been employed to measure and monitor forest canopy with feasibility of acquiring three dimensional canopy structure information. This study tried to examine the potential of GLAS dataset in measuring forest canopy structures, particularly maximum canopy height estimation. To estimate maximum canopy height using feasible GLAS dataset, we simply used difference between signal start and ground peak derived from Gaussian decomposition method. After estimation procedure, maximum canopy height was derived from airborne Light Detection and Ranging (LiDAR) data and it was applied to evaluate the accuracy of that of GLAS estimation. In addition, several influences, such as topographical and biophysical factors, were analyzed and discussed to explain error sources of direct maximum canopy height estimation using GLAS data. In the result of estimation using direct method, a root mean square error (RMSE) was estimated at 8.15 m. The estimation tended to be overestimated when comparing to derivations of airborne LiDAR. According to the result of error occurrences analysis, we need to consider these error sources, particularly terrain slope within GLAS footprint, and to apply statistical regression approach based on various parameters from a Gaussian decomposition for accurate and reliable maximum canopy height estimation.

• 한국산림과학회지
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• 제111권3호
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• pp.435-449
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• 2022

대면적 산림의 정확한 임분고 측정은 산림경영, 산림 탄소량 추정, 산림 생태계 관리를 위한 필수적인 지표인자로 다수의 국가에서 주기적인 현장조사를 수행하고 있다. 하지만, 현장조사는 많은 비용 및 시간 소요, 접근의 용이성이 낮은 지역의 조사의 기술적 한계성을 가지고 있다. 이를 극복하기 위한 대안으로 원격탐사 기술을 이용한 수고 및 임분고 추정 연구가 활발하다. 이에 본 논문에서는 해외 및 국내의 다양한 원격탐사기반 수고 및 임분고 추정 연구 사례를 분석하여 원격탐사기반 임분고 추정 연구의 동향을 크게 LiDAR기반, Stereo 및 SAR 이미지 점군(Image-based Point Clouds)기반, 원격탐사자료 융합기반 임분고 추정 모델로 나누어 살펴보았다. 또한, 대면적의 전국단위 산림 임분고 추정을 위한 원격탐사자료의 업스케일링(Upscaling) 기법의 사례 분석을 통해 향후 국내 산림환경 및 현황에 적합한 원격탐사기반 전국단위 산림 임분고 추정을 위한 방법의 발전 방향성을 고찰하였다.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2002년도 학술발표회 발표논문집
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• pp.21-24
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• 2002

Many methods are available to measure leaf area index(LAI) directly and are variations of either Leaf area index(LAI) and leaf angle distribution are widely used indices of canopy structure that are difficult to measure directly. Direct measurements of canopy structure are tedious and labor intensive in small canopies and nearly impossible in large forest canopies. This study introduced fundamental theories in LAI measurements and applied that for several crops.

• 한국환경복원기술학회지
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• 제18권3호
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• pp.65-77
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• 2015

The urban park has important functions as a habitat for wildlife as well as open space of rest and community for people. This study was carried out to find what factors of structure and vegetation of urban parks could affect forest bird species diversity in Cheonan city. The study surveyed bird and vegetation species in 26 urban parks, Cheonan city. A correlation analysis and multiple linear regressions were performed to test whether habitat structure and vegetation were the major correlate with species diversity. The results showed the Dujeong park was the most high bird species diversity (H' = 2.13), and the Dujeong-8 park (H' = 2.02) and the Cheongsa park (H' = 1.73) were considerably higher than the other urban parks. The variables that were strongly correlated with bird species diversity were park area, number of subtree species, canopy of shrub, number of shrub species, shape index, canopy of subtree, canopy of tree, and impervious surface ratio. The regression of bird species diversity against the environmental variables showed that 3 variables of park area, canopy of subtree, and canopy of tree were included in the best model. Model variable selection was broadly similar for the 5 optimal models. It means park area and multi-layer vegetation were the most consistent and significant predictor of bird species diversity, because urban parks were isolated by built-up areas. Especially the subtree coverage that provides shelter and food for forest birds was an important variable. Therefore, to make parks circular-shaped and abundant multi-layer vegetation, which could be a buffer to external disturbances and improve the quality of habitats, may be used to enhance species diversity in creation and management of urban parks.

• 한국산림과학회지
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• 제94권5호통권162호
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• pp.321-329
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• 2005

Based on the data representing four typical Korean pine forest types, the age structure, DBH distribution, species composition, and forking rule were systemically analyzed for old-growth Korean pine forest in Liangshui Nature Reserve, northeast China. The age structure of Korean pine trees was strongly uneven-aged with one dominated peak following normal distribution, and age of trees varied from 100 to 180 years within a stand. The DBH and height differences in same age class (20 years) varied from 28 cm~64 cm and 5 to 20 m, respectively. Many conifer and hard wood species, such as spruce, fir, costata birch, basswood, oak, and elm, were mixed with dominated trees of Korean pine. The canopy of the old-growth Korean pine forest can be divided into two layers, and differences of mean age and height between Layer I and Layer II were ranged 80~150 years and 7~13 m, respectively. The Weibull function was used to model the diameter distribution and performed well to describe size-class distribution either with a single peak in over-story canopy and inverse J-shape in under-story canopy for old-growth Korean pine stands. The forking height of Korean pine trees ranged from 16m to 24 m (mean 19.4 m) and tree age about 120 to 160 years old. The results will provide a scientific basis to protect and recover the ecosystem of natural old-growth Korean pine and also provide the model in management of Korean pine plantation.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2005년도 Proceedings of ISRS 2005
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• pp.512-514
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• 2005

Accurate DEM surface of forest floor is very important to extract any meaningful information regarding forest stand structure, such as tree heights, stand density, crown morphology, and biomass. In airborne lidar data processing, DEM data of forest floor is mostly generated by interpolating those elevation points obtained from last laser returns. In this study, we try to analyze the property of the last laser return under relatively dense forest canopy. Airborne laser data were obtained over the study area in relatively dense pine plantation forest. Two DEM data were generated by using all the points in the last laser returns and using only those points after removing non-ground points. From the preliminary analysis on these DEM data, we found that more than half of points among the last laser returns are actually hit from canopy, branches, and understory vegetation that should be removed before generating the surface DEM data.

• Journal of Biosystems Engineering
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• 제21권3호
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• pp.315-324
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• 1996

This study was one of a series of studies on application of machine vision and image processing to extract the geometrical features of plants and to analyze plant growth. Several algorithms were developed to measure morphological properties of plants and describing the growth development of in-situ lettuce(Lactuca sativa L.). Canopy, centroid, leaf density and fractal dimension of plant were measured from a top viewed binary image. It was capable of identifying plants by a thinning top viewed image. Overlapping the thinning side viewed image with a side viewed binary image of plant was very effective to auto-detect meaningful nodes associated with canopy components such as stem, branch, petiole and leaf. And, plant height, stem diameter, number and angle of branches, and internode length and so on were analyzed by using meaningful nodes extracted from overlapped side viewed images. Canopy, leaf density and fractal dimension showed high relation with fresh weight or growth pattern of in-situ lettuces. It was concluded that machine vision system and image processing techniques are very useful in extracting geometrical features and monitoring plant growth, although interactive methods, for some applications, were required.

• 수산해양교육연구
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• 제17권3호
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• pp.404-412
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• 2005

The surface energy budget depends on many factors, such as the type of surface, the soil moisture and the vegetation canopy, the geographical location, daily, monthly and seasonal variations, and weather conditions. In the coastal region, the surface is not homogeneous at various scales for instance water, sand, mud, tall grass, and crops. The energy balance over the vegetation canopy was analyzed with the optical energy balance measuring system. The latent heat flux was more intensive than the sensible heat flux. The sensible heat flux was very small in summer due to the canopy effect and higher in spring and autumn. In summer the development of the atmospheric boundary depended on rather the vertical shear of wind than the sensible heat flux.

• 한국작물학회지
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• 제49권3호
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• pp.155-159
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• 2004

This experiment was carried out to evaluate the microclimate of wheat canopy, growth and yield characteristics of wheat under north-south and east-west row orientation. The variety used in this experiment was "AG South 2000", which was developed in USA. Solar radiation, air temperature, relative humidity, and soil temperature were monitored by data logger from March to May in 2002, The ratio of light penetration to the bottom from the upper canopy was 36.8% in north-south and 21.4% in east-west row orientation. Temporal march of light penetration to the bottom from March to May decreased as wheat developed canopy structure and decreased a little from May as plant were matured. The highest light penetration to the bottom from upper canopy occurred at 13：00 in both north-south and east-west row orientations, respectively which were 36 times in north-south and 27 times in east-west row orientation, respectively. Daily maximum temperature at the bottom of canopy occurred at 14：00 with 29 times in north-south, while 19 times were obtained at 14：00 and 15：00, respectively in east-west row orientation. Relative humidity at the bottom of the canopy in east-west yow orientation showed higher than that of north-south row orientation. Occurrence of daily maximum soil temperature of north-south showed one hour later compared with east-west yow orientation. 1000 grain weight and test weight of north-south row orientation was higher than those of east-west vow orientation. Correlation coefficient between solar radiation of upper canopy and 1000 grain weight showed r=$0.8132^{*}$, and between air temperature of upper canopy and number of spikes per $\textrm{m}^{2}$ and 1000 grain weight showed significant positive correlation with r=$0.8139^{*}$, and r=$0.8293^{*}$, respectively.

• 한국측량학회지
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• 제33권6호
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• pp.605-614
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• 2015

Drone imaging, which is more cost-effective and controllable compared to airborne LiDAR, requires a low-cost camera and is used for capturing color images. From the overlapped color images, we produced two high-resolution digital surface models over different test areas. After segmentation, we performed tree identification according to the method proposed by , and computed the tree height and the canopy crown size. Compared with the field measurements, the computed results for the tree height in test area 1 (coniferous trees) were found to be accurate, while the results in test area 2 (deciduous coniferous trees) were found to be underestimated. The RMSE of the tree height was 0.84 m, and the width of the canopy crown was 1.51 m in test area 1. Further, the RMSE of the tree height was 2.45 m, and the width of the canopy crown was 1.53 m in test area 2. The experiment results validated the use of drone images for the extraction of a tree structure.