• Journal of KIISE:Computer Systems and Theory
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• v.27 no.7
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• pp.619-628
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• 2000

Abstract Perspective views provide a powerful depth cue and thus aid the interpretation of complicated images. The main drawback of current perspective volume rendering is the long execution time. In this paper, we present an efficient perspective volume rendering algorithm based on coherency between rays. Two sets of templates are built for the rays cast from horizontal and vertical scanlines in the intermediate image which is parallel to one of volume faces. Each sample along a ray is calculated by interpolating neighboring voxels with the pre-computed weights in the templates. We also solve the problem of uneven sampling rate due to perspective ray divergence by building more templates for the regions far away from a viewpoint. Since our algorithm operates in object-order, it can avoid redundant access to each voxel and exploit spatial data coherency by using run-length encoded volume. Experimental results show that the use of templates and the object-order processing with run-length encoded volume provide speedups, compared to the other approaches. Additionally, the image quality of our algorithm improves by solving uneven sampling rate due to perspective ray di vergence.

• Korean Journal of Agricultural and Forest Meteorology
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• v.11 no.1
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• pp.27-38
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• 2009

The multi-level profile system is designed to measure the vertical profile of $H_2O$ and $CO_2$ concentrations in the surface layer to estimate the storage effects within the plant canopy. It is suitable for long-term experiments and can be used also in advection studies for estimating the spatial variability and vertical gradients in concentration. It enables the user to calculate vertical fluxes of water vapor, $CO_2$ and other trace gases using the surface layer similarity theory and to infer their sources or sinks. The profile system described in this report includes the following components: sampling system, calibration and flow control system, closed path infrared gas analyzer(IRGA), vacuum pump and a datalogger. The sampling system draws air from 8 inlets into the IRGA in a sequence, so that for 80 seconds air from all levels is measured. The calibration system, controlled by the datalogger, compensates for any deviations in the calibration of the IRGA by using gas sources with known concentrations. The datalogger switches the corresponding valves, measures the linearized voltages from the IRGA, calculates the concentrations for each monitoring level, performs statistical analysis and stores the final data. All critical components are mounted in an environmental enclosure and can operate with little maintenance over long periods of time. This report, as a practical manual, is designed to provide helpful information for those who are interested in using profile system to measure evapotranspiration and net ecosystem exchanges in complex terrain.

• Journal of Korean Society of Forest Science
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• v.102 no.4
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• pp.515-521
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• 2013

The objective of this study was to estimate the changes of stand structure before and after applying the three different silvicultural treatments such as selection cutting system, two-storied system, and shelterwood system. This study has been conducted in the natural deciduous forests in Pyeongchang of Gangwon Province, Korea. Nine permanent sampling plots of 0.09 ha were established in the forests and each of the three silvicultural treatments was applied to three sampling points. Some tree variables were measured in each stand before and after the silvicultural treatments were applied. With these data, stand attributes were estimated in each stand before and after applying the silvicultural treatments. In this study, a competition index was used to analyze the differences among structures of stands managed by three different silvicultural treatments. Hegyi's distance-dependent competition index was estimated and compared to analyze the differences of stand structures among the stands before and after silvicultural treatments. A method using a height angle $50^{\circ}$ from the base of the subject tree was adopted as the selection method of competitor trees. Duncan's multiple range test and t-test were then employed to statistically analyze the difference of stand structure among the stands. The results revealed that competition status among trees in the stand seems to be improved after applying the silvicultural treatments. There are significant differences in the competition index between before and after silvicultural treatments for each stand. According to the evaluation of competition index, it was confirmed that spatial structure of the stands was improved by applying the silvicultural treatments.

• Journal of Wetlands Research
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• v.15 no.4
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• pp.441-451
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• 2013

Samples for estimating concentrations of polycyclic aromatic hydrocargons(PAHs), total petroleum hydrocarbons(TPHs), and benzene-toluene-ethylbenzene-xylene(BTEX) were collected at the tidal flat sediments of 8 coastal sites in Incheon, at seventy-two sampling stations for the surface sediment and twenty-four stations for the sediment core, twice in the spring and fall in 2011. This study was performed to evaluate the distributions of seasonal and spatial concentrations of PAHs, TPHs, and BTEX in the tidal flat sediments. The source origin of PAHs were carried out. The total average concentration of PAHs in the tidal flat sediment was $95.62{\mu}g/kg$. The characteristic of PAHs concentration distributions was observed that the average concentration in the autumn was lower than that in the spring, and higher concentration in the sediment core than the surface sediment, and greater vertical concentration at the top rather than the bottom in the sediment core. The total average concentration of TPHs at all sampling sites was in the value of 46 mg/kg. The characteristic of the TPHs concentration distribution was observed that the average concentration in the fall was much higher than that in the spring, and higher concentration in the surface sediment than the sediment core. The possible source of PAHs inputs were mainly derived from both pyrogenic and petrogenic origin at the surface sediment at Janghwari site and the sediment cores of both Sorae and Okyeon sites, while the rest sites of study areas originated with pyrogenic combustion.

• Journal of Environmental Impact Assessment
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• v.27 no.5
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• pp.475-488
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• 2018

Surveying urban tributary vegetation is based mainly on field sampling at present. The tributary vegetation survey integrating UAV NIR(Unmanned Aerial Vehicle Near Infrared Radiance) imagery and in-situ point photo has received only limited attentions from the field ecologist. The reason for this could be the largely undemonstrated applicability of UAV NIR imagery by the field ecologist as a monitoring tool for urban tributary vegetation. The principal advantage of UAV NIR imagery as a remote sensor is to provide, in a cost-effective manner, information required for a very narrow swath target such as urban tributary (10m width or so), utilizing very low altitude flight, real-time geo-referencing and stereo imaging. An exhaustive and realistic comparison of the two techniques was conducted, based on operational customer requirement of urban tributary vegetation survey: synoptic information, ground detail and quantitative data collection. UAV NIR imagery made it possible to identify area-wide patterns of the major plant communities subject to many different influences (e.g. artificial land use pattern), which cannot be acquired by traditional field sampling. Although field survey has already gained worldwide recognition by plant ecologists as a typical method of urban tributary vegetation monitoring, this approach did not provide a level of information that is either scientifically reliable or economically feasible in terms of urban tributary vegetation (e.g. remedial field works). It is anticipated that this research output could be used as a valuable reference for area-wide information obtained by UAV NIR imagery in urban tributary vegetation survey.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.2
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• pp.206-218
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• 2020

Located mostly inside the megacity of Busan, the Busan Southern Port is a multifunctional port with various nearby industry activities, including a joint fish market, ship repair facilities, and fishing boat facilities. If toxic chemicals generated by the industrial activities continue to flow into and accumulate in the sediment of the port, they can affect aquatic ecosystems and humans. Therefore, in this study, distribution levels and potential influent sources of organic pollutants, including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and butyltin compounds (BTs), in the sediment were investigated. The sediment samples were collected from eight sampling sites in November 2013 (first phase) and November 2014 (second phase). The mean concentrations of PAHs, PCBs, and BTs in the first and second sampling phages were 4174.0 ng/g-dry wt. and 1919.0 ng/g-dry wt., 166.3 ng/g-dry wt. and 21 ng/g-dry wt., and 50.9 ng/g-dry wt. and 30.8 ng/g-dry wt., respectively. The concentrations of the organic pollutants detected in the seabed sediments were lower in the second phase than in the first phase. In this study, the inflow sources of PAHs, PCBs, and BTs were found to be combustion, land, and municipal sewage or industrial wastewater, respectively.

• Journal of Korean Society of Forest Science
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• v.103 no.4
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• pp.613-621
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• 2014

This study was conducted to estimate the changes of stand diversity before and after applying three different silvicultural treatments such as selection cutting system, two-storied system, and shelterwood system. Data were collected in the natural deciduous forests in Pyungchang of Gangwon Province, Korea. Nine permanent sampling plots of 0.09 ha were established in the forests and the each of silvicultural treatments was applied to three sampling plots, respectively. Some tree variables were measured in each stand before and after the silvicultural treatments were applied. With these data, stand attributes were estimated in each stand before and after the silvicultural treatments. In this study, two different indices related to each of stand diversity indices such as contagion, DBH-difference, height-difference, and mingling were estimated and compared to analyze the differences of stand diversity among the stands before and after silvicultural treatments. As a result, total eight stand diversity indices were used to analyze the differences among structures of stands managed by three different silvicultural treatments. Duncan's multiple range test and t-test were then employed to statistically analyze the difference of stand diversity among the stands. The results revealed that stand structures seem to be improved after applying the silvicultural treatments. There are significant differences in the stand diversity indices between before and after silvicultural treatments for each stand. According to the evaluation of stand diversity indices, it was confirmed that spatial structure of the stands was improved by applying the silvicultural treatments.

• Korean Journal of Environment and Ecology
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• v.29 no.5
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• pp.729-735
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• 2015

This study was carried out to analyze the community structure and distribution of macrobenthos in Hakampo sandy shore. As for the environmental factors of sampling stations, the average grain size of the sediments from the sampling stations was $2.37{\phi}$ with the range of $1.90{\phi}{\sim}2.52{\phi}$, which represents the typical medium sand sedimentary facies of sandy beach. The average sediment organic content was 1.15% with the range of 0.90%~1.46%. Most stations had low sediment organic content which is typical of sandy beach. The number of species were total 59 from 6 taxa and the individuals was $668inds./m^2$ in the 10 stations of the study area. Based on the Bray-Curtis similarity analysis, the 10 stations of the study area were broadly divided into 3 groups. The highest part of intertidal zone was St. 2~St. 4, the middle part of intertidal zone was St. 5~St. 8, and the lower part of intertidal zone was St. 9~St. 10. A spatial community structure was observed which is divided into the highest, middle, and lower parts.

• Journal of Korean Society for Atmospheric Environment
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• v.23 no.5
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• pp.596-611
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• 2007

Resuspended dust from paved roads in Seoul and Incheon metropolitan areas is regarded as one of the major $PM_{10}$ sources in these areas, according to the recent emission estimates using the emission factors compiled in AP-42. It is well known that the AP-42 model for estimating $PM_{10}$ emissions from paved roads requires information on silt loadings of particular paved roads. The conventional AP-42 method (vacuum swept method) for road silt sampling, however, is expensive, time consuming, and dangerous. These drawbacks led us to develop a Mobile Dust Monitoring System (MDMS) capable of doing real time measurements of silt loading of paved roads, thereby we could get higher resolution silt loading data both in terms of time and space without too much human efforts and danger. In this study, for the real-time measurement of silt loading of paved roads, the principle used in the TRAKER method of U.S. Desert Research Institute was employed and the entire sampling systems including data acquisition system were designed for theses purpose and mounted on a SUV. The correlation between the silt loading measured by vacuum swept method and the speed corrected ${\Delta}Dust$ was derived for the vehicle-based silt loading measurements, and then the variations of silt loading on paved roads were surveyed using the MDMS in test routes of Seoul and Incheon. From the results of real-time measurements, temporal and spatial variations of silt loading data together with the existence of hot spots were observed for paved roads in Seoul and Incheon. The result of this study will be employed to estimate fugitive dust emissions from paved roads.

• Korean Journal of Environmental Biology
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• v.23 no.3 s.59
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• pp.238-249
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• 2005

The present study was carried out to apprehend that the pollutants originating from Jinhae Industrial Complex affect benthic polychaetous community in the northern Jinhae bay. An investigation on the macrobenthic community in Jinhae bay was conducted in September, December of 2002 and March of 2003. The benthic fauna showed mean density of 2,151 ind. $m^{-2}$ in September of 2002, 2,427 ind. $m^{-2}$ in December of 2002 and 2,394 ind. $m^{-2}$ in March of 2003. Major faunal groups are polychaetes, crustaceans and mollusks, corresponding to $73.7\%,\;12.0\%\;and\;11.7\%,$ in total mean density during all of the sampling season, respectively. The most abundant species was Lumbrineris longifolia $(24.85\%),$ followed by Tharyx sp. $(21.70\%),$ Mesochaetopterus sp. $(6.20\%),$ Heteromastus filiformis $(5.39\%),$ Prionospio sp. $(5.18\%),$ Clycinde sp. $(4.29\%),$ etc. Tharyx sp. was the highest abundant species in September of 2002, and Lumbrineris longifolia was the dominant species in another sampling seasons. The density and the species number of polychaetes were high around Chori Is. and poor near Jinhae Industrial Complex area. Cluster analysis based on the species composition showed that Jinhae bay could be divided into three regions except in March of 2003. In December of 2002, there are very distinct regions by the cluster analysis. The density of benthic polychaetes in Jinhae bay was higher than that in the other coastal area of Korea, due to the predominance by some of opportunistic species, such as Lumbrineris longifolia, Tharyx sp. and Heteromastus filiformis, etc. It means that the study area were in the process of organic enrichment.