• Journal of Korean Society of Forest Science
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• v.89 no.3
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• pp.389-396
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• 2000

To determine whether the Tricholoma matsutake (pine mushroom, Songyi) is symbiotic or parasitic to Pinus densiflora, structural change in their natural ectomycorrhizas were examined. The mycorrhizal samples were collected at three progressional points in the natural hypogeous colony(shiro) : colony front edge, near the fruiting point and 20cm back. The fine roots in the colonies were typical ectomycorrhizas with fungal mantle and Hartig net. However, the T. matsutake mycorrhizas had unique characteristics compared to other types of ectomycorrhizas. That is, spatially the fungal mantle and Hartig net of the T. matsutake mycorrhizas continued to develop along the growing tip, while temporally those structures declined to shrink changing to black brown in the older part of the roots behind the actively growing tip portion. However, there was no mark that the fungal hyphae penetrated into either the cortical cells, endodermal cell layers or stele. The apical tips of the blackened roots remained alive to form new mycorrhizas with other fungi later. Therefore, we conclude that the mycorrhiza of T. matsutake+P. densiflora is rather a dynamic symbiosis that changes its position spatiotemporally as the root grows than either a simple parasitism or symbiosis.

• Journal of Digital Convergence
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• v.15 no.4
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• pp.529-536
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• 2017

The purpose of this study is to examine the immediate effects of spiral taping applied to an affected leg on gait ability in stroke patients. Forty two stroke patients were divided into a spiral taping group (n=21) and a quadriceps femoris group (n=21), and each taping method was applied. Spatiotemporal Gait Parameters (Cadence, speed, gait cycle duration, stance phase duration, double support duration) were measured using the 10-meter walk test, the dynamic gait index (DGI) and an accelerometer for both groups. Both groups showed a significant increase in a 10-minute walk, the DGI, cadence, speed before and after the intervention, whereas no significant difference was detected in stance phase duration, gait cycle duration and double support duration on the affected side in all groups. All groups revealed no significant difference in variation. It has been found that the two taping methods augment gait ability in patients with stroke. This study suggests that spiral taping can be an easily applicable method at home.

• Korean Journal of Optics and Photonics
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• v.31 no.2
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• pp.59-70
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• 2020

We discuss a modified numerical model based on the Monte Carlo radiative transfer (MCRT) method, i.e., the MCRT matrix method, for the analysis of atmospheric scattering effects in three-dimensional flash LIDAR systems. Based on the MCRT method, the radiative transfer function for a LIDAR signal is constructed in a form of a matrix, which corresponds to the characteristic response. Exploiting the superposition and convolution of the characteristic response matrices under the paraxial approximation, an extended computer simulation model of an overall flash LIDAR system is developed. The MCRT matrix method substantially reduces the number of tracking signals, which may grow excessively in the case of conventional Monte Carlo methods. Consequently, it can readily yield fast acquisition of the signal response under various scattering conditions and LIDAR-system configurations. Using the computational model based on the MCRT matrix method, we carry out numerical simulations of a three-dimensional flash LIDAR system operating under different atmospheric conditions, varying the scattering coefficient in terms of visible distance. We numerically analyze various phenomena caused by scattering effects in this system, such as degradation of the signal-to-noise ratio, glitches, and spatiotemporal spread and time delay of the LIDAR signals. The MCRT matrix method is expected to be very effective in analyzing a variety of LIDAR systems, including flash LIDAR systems for autonomous driving.

• Journal of Cadastre & Land InformatiX
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• v.50 no.1
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• pp.231-245
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• 2020

The purpose of this study was to analyze the spatiotemporal characteristics of staying places by deriving the main staying places of the elderly population in Seoul using public transportation card data. For this reason, we used public transportation card data for 7 days from October 12, 2015 to October 18, 2015. As a result of the analysis, 14 places were extracted as the main staying places. It was divided into 5 groups based on the characteristics of the visiting users and concentration time. Most of the staying places showed that the elderly users who lived near the places visited, but in the case of the group where a large number of elderly users visited had relatively wide range of residential distribution. It was possible to confirm that there was a hierarchy. And the concentration time was displayed differently. Most of the staying places' concentration time was between 10 am and 5 pm. However, in the case of Jegi-dong group and Jamsil group had different concentration time. The results of this research provide necessary suggestions for establishing a public transport policy that considers the main stay spaces of the elderly population in Seoul and the stay characteristics of each stay space.

• The KIPS Transactions:PartD
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• v.11D no.6
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• pp.1221-1230
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• 2004

In mobile environments, the locations of moving objects such as vehicles, airplanes and users of wireless devices continuously change over time. For efficiently processing moving object information, the database system should be able to deal with large volume of data, and manage indexing efficiently. However, previous research on indexing method mainly focused on query performance, and did not pay attention to update operation for moving objects. In this paper, we propose a novel moving object indexing method, named ACAR-Tree. For processing efficiently frequently updating of moving object location information as well as query performance, the proposed method is based on fixed grid structure with auxiliary R-Tree. This hybrid structure is able to overcome the poor update performance of R-Tree which is caused by reorganizing of R-Tree. Also, the proposed method is able to efficiently deal with skewed-. or gaussian distribution of data using auxiliary R-Tree. The experimental results using various data size and distribution of data show that the proposed method has reduced the size of index and improve the update and query performance compared with R-Tree indexing method.

• Journal of KIISE:Databases
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• v.31 no.6
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• pp.664-674
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• 2004

The trajectory preservation property that stores only one trajectory in a leaf node is the most important feature of an index structure, such as the TB-tree for retrieving object's moving paths in the spatio-temporal space. It performs well in trajectory-related queries such as navigational queries and combined queries. But, the MBR of non-leaf nodes in the TB-tree have large amounts of dead space because trajectory preservation is achieved at the sacrifice of the spatial locality of trajectories. As dead space increases, the overlap between nodes also increases, and, thus, the classical range query cost increases. We present a new split policy and entry relocation policies, which have no deterioration of the performance for trajectory-related queries, for improving the performance of range queries. To maximally reduce the dead space of a non-leaf node's MBR, the Maximal Area Reduction (MAR) policy is used as a split policy for non-leaf nodes. The entry relocation policy induces entries in non-leaf nodes to exchange each other for the purpose of reducing dead spaces in these nodes. We propose two algorithms for the entry relocation policy, and evaluate the performance studies of new algorithms comparing to the TB-tree under a varying set of spatio-temporal queries.

• Korean Journal of Remote Sensing
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• v.33 no.3
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• pp.257-266
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• 2017

In this study, the dust/smoke detection algorithm was developed with a multi-spectral satellite remote sensing method using Moderate resolution Imaging Spectroradiometer (MODIS) Level 1B (L1B) data and the results were validated as RGB composite images of red(R; band 1), green(G; band 4), blue(B; band 3) channels using MODIS L1B data and Cloud-Aerosol Lidar with Orthogonal Polarization Satellite Observations(CALIPSO) Vertical Feature Mask (VFM) product. In the daytime on March 30, 2007 and April 27, 2012, the consistencies between the dust/smoke detected by this algorithm and verification data were approximately 56.4 %, 72.0 %, respectively. During the nighttime, the similar consistency was 40.5 % on April 27, 2012. Although these results were analyzed for limited cases due to the spatiotemporal matching for the MODIS and CALIPSO satellites, they could be used to utilize the aerosol detection of geostationary satellites for the next generations in Korea through further research.

• Korean Journal of Ecology and Environment
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• v.49 no.4
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• pp.245-257
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• 2016

Although rivers cover only 0.5% of the total land area on the Earth, they are windows that show the integrated effects of watershed biogeochemistry. Studies on the loads and properties of riverine carbon have been conducted because they are directly linked with drinking water quality, and because regional or global net ecosystem production (NEP) can be overestimated, unless riverine carbon loads are subtracted. Globally, ${\sim}0.8-1.5Pg\;yr^{-1}$ and ${\sim}0.62-2.1Pg\;yr^{-1}$ of carbon are transported from terrestrial ecosystems to the ocean via rivers and from inland waters to the atmosphere, respectively. Concentrations, ${\delta}^{13}C$, and fluorescence spectra of riverine carbon have been investigated in South Korea to understand the spatiotemporal changes in the sources. Precipitation as well as land use/land cover can strongly influence the composition of riverine carbon, thus shifting the ratios among DIC, DOC, and POC, which could affect the concentrations, loads, and the degradability of adsorbed organic and inorganic toxic materials. A variety of analyses including $^{14}C$ and high resolution mass spectroscopy need to be employed to precisely define the sources and to quantify the degradability of riverine carbon. Long-term data on concentrations of major ions including alkalinity and daily discharge have been used to show direct evidence of ecosystem changes in the US. The current database managed by the Korean government could be improved further by integrating the data collected by individual researchers, and by adding the major components ions including DIC, DOC, and POC into the database.

• The KIPS Transactions:PartD
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• v.16D no.4
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• pp.487-496
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• 2009

This paper addresses an indexing scheme capable of efficiently processing range queries in a large-scale trajectory database. After discussing the drawbacks of previous indexing schemes, we propose a new scheme that divides the temporal dimension into multiple time intervals and then, by this interval, builds an index for the line segments. Additionally, a supplementary index is built for the line segments within each time interval. This scheme can make a dramatic improvement in the performance of insert and search operations using a main memory index, particularly for the time interval consisting of the segments taken by those objects which are currently moving or have just completed their movements, as contrast to the previous schemes that store the index totally on the disk. Each time interval index is built as follows: First, the extent of the spatial dimension is divided onto multiple spatial cells to which the line segments are assigned evenly. We use a 2D-tree to maintain information on those cells. Then, for each cell, an additional 3D $R^*$-tree is created on the spatio-temporal space (x, y, t). Such a multi-level indexing strategy can cure the shortcomings of the legacy schemes. Performance results obtained from intensive experiments show that our scheme enhances the performance of retrieve operations by 3$\sim$10 times, with much less storage space.

• Korean Journal of Optics and Photonics
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• v.28 no.5
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• pp.236-240
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• 2017

In this paper, we investigate the thermal response of skin tissue to high-intensity focused ultrasound (HIFU) by means of infrared (IR) thermal imaging. For skin tightening, a 7-MHz ultrasound transducer is used to induce irreversible tissue coagulation in porcine skin. An IR camera is employed to monitor spatiotemporal changes of the temperature in the tissue. The maximum temperature in the tissue increased linearly with applied energy, up to $90^{\circ}C$. The extent of irreversible tissue coagulation (up to 3.2 mm in width) corresponds well to the spatial distribution of the temperature during HIFU sonication. Histological analysis confirms that the temperature beyond the coagulation threshold (${\sim}65^{\circ}C$) delineates the margin of collagen denaturation in the tissue. IR thermal imaging can be a feasible method for quantifying the degree of thermal coagulation in HIFU-induced skin treatment.