• Journal of Korea Spatial Information System Society
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• v.11 no.3
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• pp.55-62
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• 2009

Location based Services in the ubiquitous computing environment, namely u-LBS, use very large and skewed spatial objects that are closely related to locational information. It is especially essential to achieve fast search, which is looking for POI(Point of Interest) related to the location of users. This paper examines how to search large and skewed POI efficiently in the u-LBS environment. We propose the Dynamic-level Grid based R-Tree(DGR-Tree), which is an index for point data that can reduce the cost of stationary POI search. DGR-Tree uses both R-Tree as a primary index and Dynamic-level Grid as a secondary index. DGR-Tree is optimized to be suitable for point data and solves the overlapping problem among leaf nodes. Dynamic-level Grid of DGR-Tree is created dynamically according to the density of POI. Each cell in Dynamic-level Grid has a leaf node pointer for direct access with the leaf node of the primary index. Therefore, the index access performance is improved greatly by accessing the leaf node directly through Dynamic-level Grid. We also propose a K-Nearest Neighbor(KNN) algorithm for DGR-Tree, which utilizes Dynamic-level Grid for fast access to candidate cells. The KNN algorithm for DGR-Tree provides the mechanism, which can access directly to cells enclosing given query point and adjacent cells without tree traversal. The KNN algorithm minimizes sorting cost about candidate lists with minimum distance and provides NEB(Non Extensible Boundary), which need not consider the extension of candidate nodes for KNN search.

• Journal of Forest and Environmental Science
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• v.29 no.2
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• pp.157-164
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• 2013

The campus of Chittagong University in Bangladesh is rich in forest ecosystem. The campus has large area with vast tract of land planted with valuable timber tree species. The present study identifies and discovers the potential growing stock of the plantations in the campus area. This Growing stock was measured in three parameters viz. volume, biomass and organic carbon stock. Study identified thirty three economically valuable forest tree species in the plantations of Chittagong University. Out of three growing stock parameters, volume of timber was found to be low in indigenous tree species in the plantation sites other than exotic species. This might be due to their slow growth rate and low density in the plantation sites. However, biomass and organic carbon stock of trees per hactre area showed that indigenous species gather and sequester more timber and carbon respectively than introduced species. Plantations of Chittagong University campus can acquire $25.51m^3/ha$ volume of economically important tree species, where biomass and organic carbon stock is 222.33 tonne/ha and 107.48 tonne/ha respectively. This result shows a positive impression on the plantation site to be considered as good forest reserve.

• Korean Journal of Environment and Ecology
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• v.35 no.4
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• pp.398-407
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• 2021

This study intended to identify causes of poor tree vigor in the Hanbando coastal forest by investigating its geographical environment, climate condition, soil physicochemical characteristics, and growth condition of Pinus thunbergii. It divided the forest into an area with poor tree vigor or dead standing trees and a control area with good tree vigor and examined them separately. The survey showed that stand density was significantly higher in the area with poor tree vigor. In contrast, the crown width in the area with good tree vigor was wider. The number of dead standing trees and the stand density showed a negative correlation. The stand density and diameter at breast height (DBH), tree height, crown height, and crown width also showed a negative correlation. The result indicated that, as the tree's stand density increases, the crowns of individual trees overlapped and the lower branches died. Then crown height and crown width decreased, and the number of leaves and photosynthesis was reduced, leading to lower tree height and weaker growth of breast diameter. As a result, tree vigor weakened, and combined with environmental pressures from the lack of moisture and nutrients in coastal soil and salty wind, P. thunbergii in coastal areas is expected to die massively. Although the causes of dead standing trees and poor tree vigor of P. thunbergii in the Hanbando coastal forest are complicated, poor management of adequate tree density in response to the growth of P. thunbergii is the primary cause. The secondary cause is external environmental pressures, including unfavorable soil conditions and salty and strong wind that obstruct the growth of P. thunbergii.

• Journal of Multimedia Information System
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• v.6 no.4
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• pp.179-184
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• 2019

This paper introduces a study for procedurally generating the behavior of objects in a virtual environment at runtime. This study was initiated to enable the behavioral model of objects in virtual reality applications to evolve in response to user behavior at runtime. Our approach is to describe the behavior of an object as a behavior tree, and to make a node of the behavior tree change to another type if a certain condition is satisfied. We defined four types of node changes: "parameterized", "probabilistic", "alternate", and "variant". We experimented with a virtual environment that includes a variety of simple procedural elements to explore the possibilities of our approach. As a result of the implementation, if an optimization algorithm that can select and apply the optimized procedural elements in response to the user's behavior is complemented, it is confirmed that more intelligent objects and agents can be implemented in virtual reality applications.

• Journal of the Korean Institute of Educational Facilities
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• v.14 no.2
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• pp.5-15
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• 2007

In modern society, the role of university becomes diversified and the concerns on building construction or landscape architecture considering beautiful landscape and scene are increasing caused by increasing interest on external environment of campus. But relative importance of concerns for the context of landscape architecture in campus is neglected rather than other facilities. So the landscape architecture service could not be conducted well. Therefore the computerization of system or management program will be needed for effective landscape architecture tree management and sufficiency of concerns on continuously increasing landscape architecture in campus. The computerization of landscape architecture tree management will be important roles not only to raise the efficiency of landscape architecture management and the view of outdoor environment but also to increase the competitive power of rapidly changing university environment and the quality of education.

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 2004.11a
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• pp.72-75
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• 2004

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.2
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• pp.203-210
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• 2015

The ecological environment monitoring system configured with Sensor Node, Gateway, Service Platform, and Web Browser. In this paper, we designed gateway resource tree and service function to do handling in the ecological environment monitoring service. Gateway Service Function based on oneM2M Common Service Function, Gateway Resource Tree configured with Application Part handling Sensor Data and Gateway link handling. lastly Device Registration, Sensing, Control, Profile Management.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.1174-1176
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• 2003

Recently 3D city models are required for many applications such as urban microclimate, transportation navigation, landscape planning and visualization to name a few. The existing 3D city models mostly target on modeling buildings, but vegetation also plays an important role in the urban environment. To represent a more realistic urban environment through the 3D city model, in this research, an investigation is conducted to extract the position of trees from high resolution IKONOS imagery along with Airborne Laser Scanner data. Later, a tree growth model is introduced to simulate the growth of trees in the identified tree-positions.

• The Korean Journal of Ecology
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• v.22 no.2
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• pp.65-68
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• 1999

In December-January of 1996-1997 and 1997-1998, information was gathered about vertical distribution of foraging sites of tits in 34 flocks in coniferous and deciduous forests. There was a significant effect of forest type on the distribution of foraging sites of each species. Habitat was classified into 5 height layers vertically: ground, bushes (usually＜1.5 m, up to 3 m), tree layer 1 (up to 1/3 of tree height), tree layer 2 (1/3-2/3 tree height). and tree layer 3 (＞2/3 tree height). There were differences among species: great tit (Parus major) foraged mostly on the ground, coal tit (P. ater) and long-tailed tit (Acrocephalus caudatus) - on the highest tree layer, marsh tit (P. palustris) was often seen on bushes, and varied tit (P. varius) - in tree layer 2. Smaller species used upper and outer parts of trees. suggesting that, like in most other similar studies. larger dominant species prevented smaller species from using inner parts of trees.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.3
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• pp.87-92
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• 2008

In this paper, certain scaling functions are generated using the dyadic subband tree structure and applied to a time-hopping, pulse position modulation, ultra-wideband (TH-PPM UWB) system. Scaling functions can be obtained by iterating a lowpass filter at each level using a critically sampled dyadic tree. The performance of the TH-PPM UWB system employing scaling functions as the mono-cycle waveform is evaluated through computer simulations in a Rayleigh fading environment.