• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.21 no.2
• /
• pp.179-187
• /
• 2010

The use of high frequency band, broad band and MIMO antenna is expected in the next generation mobile communication system. By the rapid increase of demand for wireless communications and the explosive increase of the mobile communication services, researches for optimization of next-generation mobile communication system are required. In the existing MIMO channel models, propagation-environments are commonly classified into urban, suburban, rural area, etc. However such approaches can have drawbacks in that many different morphologies may exist even in the urban area, for example. In this paper, we introduced path morphology concept, and proposed the method of morphology classification considering the building height, density, etc. Delay spread(DS), angular spread(AS) of AoD and AoA analyzed for each environment using the ray tracing technique. Based on the analysis, a MIMO channel model appropriate in domestic environment was suggested.

• Journal of the Korea Concrete Institute
• /
• v.18 no.5 s.95
• /
• pp.677-685
• /
• 2006

Control of the temperature difference across a section is an effective strategy to minimize the hydration-heat-induced cracks for the structures where internal restraint is dominant. The domestic code, however, overestimates probability of the crack occurrence judging from the foreign codes and construction experiences of real structures. Therefore, the background of the equation presented in the domestic code was investigated step by step to examine validity of the equation, and, as a result, it was found that the equation is established on a basis of simple elastic model where the change of elastic modulus in an early age is not considered. An advanced assessment strategy was proposed taking into account the hypoelastic model which corresponds to an incremental constitutive equation. The presented procedure resulted in an increased crack index, i.e. decreased crack risk, the value of which depends on various conditions of the mix and structures. Also, a prediction equation of the temperature difference was proposed which can readily consider the effect of the curing condition and ambient temperature in a hand calculation. For further study, the assessment equation may be more classified to strictly consider the characteristics of the mix and structures if the analytical and experimental data are accumulated.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.17 no.8 s.111
• /
• pp.773-787
• /
• 2006

An airborne radar is an essential aviation electronic system for the aircraft to perform various civil and/or military missions in all weather environments. This paper presents the design, development, and test results of the multi-mode X-band pulsed Doppler radar system test model for helicopter-borne flight test. This radar system consists of 4 LRUs(Line-Replacement Unit), which include antenna unit, transmitter and receiver unit, radar signal & data processing unit and display Unit. The developed core technologies include the planar array antenna, TWTA transmitter, coherent I/Q detector, digital pulse compression, MTI, DSP based Doppler FFT filter, adaptive CFAR, moving clutter compensation, platform motion stabilizer, and tracking capability. The design performance of the developed radar system is verified through various ground fixed and moving vehicle test as well as helicopter-borne field tests including MTD(Moving Target Detector) capability for the Doppler compensation due to the moving platform motion.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.33 no.4
• /
• pp.1433-1446
• /
• 2013

In this study, we proposed a methodology to develop Rating Curves for high water level using rainfall generation by the Monte Carlo Simulation (MCS) technique, optimized rainfall-runoff model, and flood routing model in an urban stream. The developed stage discharge Rating Curve based on observed data was contained flow measurement errors and uncertainties. The standard error ($S_e$) for observations was 0.056, and the random uncertainty ($2S_{mr}$) was analyzed by ${\pm}1.43%$ on average, and up to ${\pm}4.27%$. Moreover, it was found that the Rating Curve extensions by way of logarithmic and Stevens methods were overestimated to compare with the urban basin scale. Finally, we confirmed that the high water level extension by random generation of hydrological data using MCS can be reduced uncertainty of the high water level, and it will consider as a more reliable approach for high water level extension. In the near future, this results can be applied to real-time flood alert system for urban streams through construction of the high water level extension system using MCS procedures.

• Journal of the Korean Society of Radiology
• /
• v.11 no.4
• /
• pp.235-240
• /
• 2017

The purpose of this study is to confirm the safety of the clinical application of image co - registration in steteotactic radiosurgery by evaluating the 3D positioning of magnetic resonance imaging using image co-registration. We performed a retrospective study using three-dimensional coordinate measurement of 32 patients who underwent stereotactic radiosurgery and performed magnetic resonance imaging follow-up using image co-registration. The 3 dimensional coordinate errors were $1.0443{\pm}0.5724mm$ (0.10 ~ 1.89) in anterior commissure and $1.0348{\pm}0.5473mm$ (0.36 ~ 2.24) in posterior commissure. The mean error of MR1 (3.0 T) was lower than that of MR2 (1.5 T). It is necessary to minimize the error of magnetic resonance imaging in the treatment planning using the image co - registration technique and to confirm it.

• Journal of the Korea Society of Computer and Information
• /
• v.16 no.9
• /
• pp.69-76
• /
• 2011

According to the related reports, about 60 percents of ship collisions have resulted from operating mistake caused by human factor. Specially, the report said that negligence of observation caused 66.8 percents of the accidents due to a human factor. Hence automatic detection and tracking of an object from an IR images are crucial for safety navigation because it can relieve officer's burden and remedies imperfections of human visual system. In this paper, we present a method to detect an object such as ship, rock and buoy from a sea IR image. Most edge directions of the sea image are horizontal and most vertical edges come out from the object areas. The presented method uses them as a characteristic for the object detection. Vertical edges are extracted from the input image and isolated edges are eliminated. Then morphological closing operation is performed on the vertical edges. This caused vertical edges that actually compose an object be connected and become an object candidate region. Next, reference object regions are extracted using horizontal edges, which appear on the boundaries between surface of the sea and the objects. Finally, object regions are acquired by sequentially integrating reference region and object candidate regions.

• Korean journal of applied entomology
• /
• v.32 no.3
• /
• pp.307-316
• /
• 1993

The potential of using GIS in analyzing pest surveillance data was explored. The Spatial Analysis System (SPANS) was used to construct a spatial data base to study pest distributions using pest surveillance data collected from 152 stations in South Korea. The annual spatIal distributions of the striped rice borer(SRB), Chdo suppressalis, showed that high densities started to expand in the early 1980s, reaching a peak in 1988. The pattern change appears to be related to cultivation of japonica and indica-japonica hybrid varieties in South Korea. Japo7l!ca varieties have longer duration resulting in the SRB haVlng more time to mature and hibernate in wmter. The locus of SRB spread appears to be located in the mid-west region near lri, Chun~ Buk Province. High brown planthopper (BPH) populations in South Korea are often related to the early immigration and temperature. The simulated distribution of PPH densities in September using these two factors was compared with the actual distribution obtained using 1990 data. The two density maps corresponded closely excepL for differences in the south eastern valley. By overlaying the simulated map layer with the elevation and rice area maps, more specific BPH risk zones could be identified.

• Proceedings of the KSR Conference
• /
• 2007.11a
• /
• pp.1099-1104
• /
• 2007

The visual implementation of 3-dimensional national environment is focused by the requirement and importance in the fields such as, national development plan, telecommunication facility deployment plan, railway construction, construction engineering, spatial city development, safety and disaster prevention engineering. The currently used DEM system using contour lines, which embodies national geographic information based on the 2-D digital maps and facility information has limitation in implementation in reproducing the 3-D spatial city. Moreover, this method often neglects the altitude of the rail way infrastructure which has narrow width and long length. There it is needed to apply laser measurement technique in the spatial target object to obtain accuracy. Currently, the LiDAR data which combines the laser measurement skill and GPS has been introduced to obtain high resolution accuracy in the altitude measurement. In this paper, we first investigate the LiDAR based researches in advanced foreign countries, then we propose data a generation scheme and an algorithm for the optimal manage and synthesis of railway facility system in our 3-D spatial terrain information. For this object, LiDAR based height data transformed to DEM, and the realtime unification of the vector via digital image mapping and raster via exactness evaluation is transformed to make it possible to trace the model of generated 3-dimensional railway model with long distance for 3D tract model generation.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.5 no.4
• /
• pp.106-118
• /
• 2002

In recent years, synthetic and systematic management with conservation-oriented strategy for Baekdu-daegan, which is the greatest chine as well as the major ecological axis of the Korean Peninsula, is being required to cope adequately with the various kinds of developmental urge. For this, spatially definite zoning for the managerial area on Baekdu-daegan has to be completed first. This study is to take into consideration the traditional concepts of stream and watershed as well as the actual disturbance on Daegan area, and to propose the process for reasonably establishing the managerial boundary adjacent to the Ridges. The case site with topographically diverse characteristics was selected, and the analyses on watershed, road network and land use were carried out using the digital maps and Landsat TM images. Based on these analyses results, the managerial boundaries as alternatives from the Ridges were produced by watershed expansion process, and used for tracing the changes of road occupancy rate and the areal ratio of various land use types to the relevant watersheds to search out the adequate managerial boundary. The results show that watershed expansion process could be effective tool for establishing the managerial boundary, and the fourth expanded watershed would be included for the adequate managerial boundary of the case site.

• The Journal of the Korea Contents Association
• /
• v.20 no.2
• /
• pp.581-593
• /
• 2020

The purpose of this study was to examine the eye-fixation times on different parts of a student avatar and the virtual presence with two scenarios in the virtual reality-based teaching simulation. This study was to identify user attention while he or she is interacting with a student avatar. By examining where a user is gazing during a conversation with the avatar, we have a better understanding of non-verbal communication. For this study, forty-five college students (21 females and 24 males) participated in the experiment. They had a conversation with a student avatar in a virtual reality-based teaching simulation. The participants had verbal interactions with the student avatar with two scenarios. While they were having a conversation with the virtual character in the teaching simulation, their eye-movements were collected through a head-mounted display with an eye-tracking function embedded. The results revealed that there were significant differences in eye-fixation times. Participants gazed a longer time on facial expression than any other area. The fixation time on the facial expression was more prolonged than on gestures (F=3.75, p<.05). However, the virtual presence was not significantly different in two scenario levels. This result suggested that users focus on the face more than the gesture when they emotionally interact with the virtual character.