• Journal of information and communication convergence engineering
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• v.3 no.3
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• pp.123-130
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• 2005

This study performed five methods of tests and measurements to verify the improvement of connection time and bandwidth efficient of FSS (fixed satellite service) TCP/IP network by means of the cash function and the spoofing function. Tests and measurements are performed with; 1. Not to apply the cash and spoofing function 2. Apply the cash function 4. Apply both cash and spoofing function in HUB station and VSAT 5. In a typical commercial terrestrial Internet with LAN. The study results in this paper show that application of the spoofing and cash function greatly improves the bandwidth efficiency to FSS TCP/IP Internet service.

• Korean Journal of Remote Sensing
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• v.19 no.1
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• pp.1-9
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• 2003

MODIS LAI product has been one of key variable for analyzing the quantitative aspects of terrestrial ecology at global scale. This study was designed to validate MODIS global LAI product for regional application. To examine the quality of MODIS LAI data, we developed a reference LAI surface that was derived by relating the ground LAI measurements to Landsat ETM+ reflectance. The study area, the Kwangneung Experiment Forest in Korea, covers mixed deciduous and coniferous species of temperate forest. Ground measurements of LAI were conducted at 30 sample plots by using a photo-optical instrument during the growing season of 2002. Ground measured LAI data were then related to the ETM+ reflectance to produce a continuous map of LAI surface over the study area. From the comparison between the MODIS LAI and the reference LAI, it was found that the MODIS LAI values were slightly higher at the forestland. Considering the limitations of producing the reference LAI surface and the uncertainty of the input variable for the MODIS LAI algorithm, such small discrepancy mal not be significant.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.9 no.1
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• pp.17-25
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• 1991

A foundation excavation is necessarily included in construction works of structures. Involving the dangers of collapse, large-scaled excavation walls require periodic deformation measurements. As only relative displacements and acquired and surface measurements can not be made with the conventional measuring methods, the up-to-date method which can overcome these weaknesses is required urgently. Terrestrial photogrammetry is the method by which absolute deformation amounts of many points can be taken out at a distance from object in short time. The objective of this study is to suggest application propriety of terrestrial photogrammetry to the measurement of excavation walls. For it, we devised same position photography(S.P.P) and possibility of SPP proved through basic experiment. SPP was very speedy photographing method. We found out the fact that as the degree of overlap increase, accuracies of results increase. As a result of applying to excavation side-wall, we detected consistent displacement in 3 dimension each direction within the limits expectional accuracy. If control surveying could be carried out more quickly and accurately, the deformation displacement could be analyzed more effectively.

• Journal of Communications and Networks
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• v.13 no.4
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• pp.367-376
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• 2011

In this paper, we propose self-organizing schemes for the initial configuration of the neighbor cell list (NCL), maintenance of the NCL, and physical cell identifier (PCI) allocation in heterogeneous networks such as long term evolution systems where lower transmission power nodes are additionally deployed in macrocell networks. Accurate NCL maintenance is required for efficient PCI allocation and for avoiding handover delay and redundantly increased system overhead. Proposed self-organizing schemes for the initial NCL configuration and PCI allocation are based on evolved universal terrestrial radio access network NodeB (eNB) scanning that measures reference signal to interference and noise ratio and reference symbol received power, respectively, transmitted from adjacent eNBs. On the other hand, the maintenance of the NCL is managed by adding or removing cells based on periodic user equipment measurements. We provide performance analysis of the proposed schemes under various scenarios in the respects of NCL detection probability, NCL false alarm rate, handover delay area ratio, PCI conflict ratio, etc.

• Journal of the Korean Association of Geographic Information Studies
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• v.24 no.4
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• pp.55-64
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• 2021

In this study, the operation method and accuracy of Terrestrial Laser Scanner(TLS) are reviewed and discussed by experimental measurements, and guidelines of TLS surveying operation are proposed. Ground control points and TLS station points were measured by TS and/or GPS, in TLS observation experiments, and wood targets were used which designed by this study team. RMSE accuracy of TLS scan shows that TLS surveying operation can be used in the topographic mapping of 1/250 scale and level of 1/100 BIM, the drone data also used in TLS data completeness. Additionally, as the results of the field experiment, the guidelines for TLS surveying operartions were proposed.

• Journal of Korean Society for Atmospheric Environment
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• v.12 no.2
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• pp.189-198
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• 1996

Mercury (Hg) is ubiquitous throughout the earth's atmosphere. The uniqueness of its atmospheric geochemistry is well-known with the high environmental mobility and relatively long atmospheric residence time (c.a., 1 year) associated with its high chemical stability. Despite a growing recognition of the environmental significance of its global cycling, the prexisting Korean database for atmospheric Hg is extremely rare and confined to a number of concentration measurements conducted under relatively polluted urban atmospheric environments. To help activate the research on this suvject, an in-depth analysis on the current development in the measurements of atmospheric mercury and the associated fluxes has been made using the most using the most updated data ests reported worldwide. As a first step toward this purpose, the most reliable techniques commonly employed in the measurements of its concentration in the background atmosphere are introduced in combination with the flux measurement techniques over soil surface such as: dynamic enclosure (or field flux chamber) method and field micrometeorological method. Then the results derived using these measurement techniques are discussed and interpreted with an emphasis on its mobilization across the terrestrial biosphere and atmosphere interface. A unmber of factors including air/soil temperature, soil chemical composition, soil water content, and barometric pressure are found out to be influential to the rate and amount of such exchange processes. Although absolute magnitude of such exchange processes is insignificant relative to that of the major component like the oceanic environment, this exchange process is thought to be the the predominant natural pathway for both the mobilization and redistribution of atmospheric Hg on a local or regional scale.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.91-91
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• 2011

The passage of the interplanetary discontinuity (i.e., sudden increases in the solar wind speed, density, and IMF strength) was detected by ACE near GSE (x, y, z) ~ (222, -36, 3) Re upstream of Earth around 22:48 UT on November 24, 2008. About 55 min later, this solar wind discontinuity was observed by Geotail near GSE (x, y, z) ~ (23, 18, -7) Re in front of Earth's bow shock. From the propagation time of the solar wind discontinuity between ACE and Geotail, it is expected that the discontinuity front is aligned with the Parker spiral and strikes the postnoon dayside magnetopause first. Using coordinated multi-point measurements (THEMIS and GOES) at or in geosynchronous orbit, we observed a tailward propagating sudden impulse (SI), excited by the interplanetary discontinuity, around 23:50 UT with its front retaining alignment similar to that of solar wind discontinuity. The SI event appears a negative-then-positive variation in the H component at high latitude Chokurdakh (CHD: MLAT ~ 64.7 deg) in the prenoon sector, which is opposite sense of normal SI event. During the positive deflection at CHD, the SuperDARN Hokkaido radar detected the downward motion of the ionosphere, implying westward electric field enhancement, at subauroral latitudes near CHD meridian. In our study we will discuss magnetospheric and ionospheric responses to the passage of the solar wind discontinuity using multi-point observations in space and on the ground.

• The Korean Journal of Quaternary Research
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• v.20 no.2
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• pp.30-50
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• 2006

The long-lived radionuclide, $^{10}Be$, is produced by cosmic-ray effects in the atmosphere of the earth as well as its surface and that of other planetary surfaces and atmospheres. Accelerator mass spectrometry (AMS) was developed in late 1970s, which made $^{10}Be$ terrestrial measurements more feasible. Since then, many research applications of $^{10}Be$ for both terrestrial and extraterrestrial applications have been developed, which parallel the wide range of radiocarbon ($^{14}C$) research applications. This paper summarizes production mechanisms of $^{10}Be$ both in the atmosphere and on the surface of terrestrial and extraterrestrial environments and also provides numerous $^{10}Be$ research applications in the fields of geomorphology, oceanography, archaeology, glaciology, cosmochemistry, climatology, and planetary science. We also review some $^{10}Be$ AMS research applications.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1D
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• pp.169-175
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• 2006

Recently, slope failures are disastrous when they occur in mountainous area adjoining highways. The accidents associated with slope failures have increased due to rapid urbanization of mountainous area. Therefore, the inspection of slope is conducted to maintain road safety as well as road function. In this study, we apply to the remedy which is comparing existent description to advanced technology using GIS. We utilize a Terrestrial LiDAR, one of the advanced method, to generate precise and complete road slope model from expert point of view. In result, we extract hazardous slope information from external measurements referring to the evaluation criteria of external slope stability. We suggest not only the database but also the method of road risk evaluation based on internet GIS.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.28 no.1
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• pp.57-64
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• 2010

Measurements of deflection in load testing of structures are typically obtained with contact instrumentations such as LVDT (Linear-Variable Differential Transformer). LVDT only measure 1-dimensional deformation and in destructive testing is damage to instrumentation, thus prohibiting deflection when the beam is close to failure. Measurements of deflection using non-metric digital cameras are useful for load testing because there are very little cost or beam failure except for cheap targets and measurements in 3-dimensional deflection can obtained rapidly. In this research, deflection of concrete beam was measured using Nikon D80 DSLR camera, and the accuracy was evaluated with comparing the outputs to the LVDT measurements. The results show that the accuracy of terrestrial photogrammetric measurements are ${\pm}$0.5mm, ${\pm}$0.5mm, ${\pm}$0.6mm for each X, Y, Z directions, and the RMSE of comparison to LVDT is ${\pm}$0.57mm.