• Geophysics and Geophysical Exploration
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• v.11 no.4
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• pp.350-360
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• 2008

Electrical resistivity is one of physical property of the earth and measured by electrical resistivity survey, electrical resistivity logging and laboratory test. Recently, electrical resistivity is widely used in determination of rock quality in support pattern design of road and railway tunnel construction sites. To get more reliable rock quality data from electrical resistivity, it needs a lot of test and study on correlation of resistivity and rock quality. Firstly, we did rock property test in laboratory, such as P wave velocity, Young's modulus, uniaxial compressive strength (UCS) and electrical resistivity. We correlate each test results and we found out that electrical resistivity has highly related to P wave velocity, Young's modulus and UCS. Next, we accomplished electrical resistivity survey in field site and carried out electrical resistivity logging at in-situ area. We also performed rock classification, such as RQD, RMR and Q-system and we correlate electrical resistivity to RMR data. We found out that electrical resistivity logging data are highly correlate to RMR. Also we found out that electrical resistivity survey data are lower than electrical resistivity logging data when there are faults or fractures. And it cause electrical resistivity survey data to lowly correlate to RMR.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.12 s.354
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• pp.15-22
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• 2006

In this paper, 1.8V 8-bit 500MSPS Low-power CMOS Digital-to-Analog Converter(DAC) for UWB(Ultra Wide Band) Communication Systeme is proposed. The architecture of the DAC is based on a current steering 6+2 full matrix type which has low glitch and high linearity. In order to achieve a high speed and good performance, a current cell with a high output impedance and wide swing output range is designed. Further a thermometer decoder with same delay time and low-power switching decoder for high efficiency performance are proposed. The proposed DAC was implemented with TSMC 0.18um 1-poly 6-metal N-well CMOS technology. The measured SFDR was 49dB when the output frequency was 50MHz at 500MS/s sampling frequency. The measured INL and DNL were 0.9LSB and 0.3LSB respectively. The DAC power dissipation was 20mW and the effective chip area was $0.63mm^2$.

• Journal of the Korean Association of Geographic Information Studies
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• v.17 no.3
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• pp.93-103
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• 2014

Regarding to the cadastral information and building information as a spatial information, studies on linking between cadastral records and building information, or integration methodology on 2D based building map and land information were proposed. Cadastral information has grown its values by cadastral resurvey project and cadastral confirmation survey. There is a tendency of BIM in the design stage which is not just simple 3D dataset and BIM is spreading in public and private sectors. However, studies on the linkage between building information and cadastral information is relatively weak comparing to the BIM spreading. One of the main features that have been improved in IFC4 is the interoperability with GIS. In this regards, the researcher propose several revision methods to link cadastral information to building information. Cadastral information needs to improve the quality of the dataset's such as unifying the different coordinate systems and preparing continuous cadastral map. For buildings, standardization of BIM in the public and private sectors is urgent task. IFC4 and upcoming IFC5 are international standards which need to be considered and BIM reverse engineering for the existing buildings is necessary for the public utilization in the near future.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.1
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• pp.17-27
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• 2014

Numerical model became one of most important tools for identifying the state of an existing structure in accordance with development of numerical analysis techniques. A numerical model should be updated based on the measured responses from the existing structure to accurately use the model for identifying the state of the bridge and executing numerical experiments. In this study, a new model updating method based on repetition method without a differential function is introduced and applicability for high speed railway bridge is verified with dynamic stability analysis. A fine measurement based on measurement points roaming method was executed with an wireless measurement system for precise dynamic characteristic analysis. The natural frequencies and mode shapes were estimated by correlation analysis and a mode decomposition technique. An initial numerical model was constructed based on design drawings and the model have been updated in accordance with the introduced model updating method. The results from numerical experiment and field test have been compared for verifying the applicability of the model updating method. And the dynamic stability analysis has been executed to verify the usability of the updated numerical model and the model updating method. It seems that the model updating method can be used for various bridges after evaluation of applicability for other type bridges in further studies.

• Journal of The Korean Association For Science Education
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• v.30 no.8
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• pp.1097-1109
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• 2010

The purpose of this study is to analyze the ERF components patterns of observers who have different cognitive styles using magneto-encephalography (MEG). The task was developed based on the CSA (Cognitive Style Analysis) program. Eight right-handed, healthy male college students participated in voluntarily. To investigate college students' ERF components during the task, an MEG system with block design was used to measure magnetic signals in their brains. For examining the observation characteristic by cognitive style, MEG ERF components were analyzed. As a result, four ERF components (M1, M2, M3, M4) were observed. Through the results of this study, the reason for different observation characteristics by cognitive styles was verified in the neurophysiological methods. This study will have implications to establish theories on scientific observation and cognitive styles.

• Journal of the Korean Society for Advanced Composite Structures
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• v.3 no.1
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• pp.29-34
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• 2012

Even though the longitudinally stiffened laminated composite plates with closed section ribs should be an effective system for axially compressed members, the existing researches on the applications of closed-section ribs, especially for the laminated composite plates, are not sufficient. This study is aimed to examine the influence of the sectional stiffness of U-shaped ribs on the buckling modes and strengths of laminated composite plates. Applying the orthotropic plates with eight layers of the layup $[(0^{\circ})_4]_s$ and $[(0^{\circ}/90^{\circ})_2]_s$, 3-dimensional finite element models for the U-rib stiffened plates were setup by using ABAQUS and then a series of eigenvalue analyses were conducted. From the parametric studies, the minimum required ply thicknesses as well as the buckling strengths were presented for the analysis models. The buckling strengths were compared with the theoretical critical stress equation for simply supported plates based on the Classical laminated plate theory. This study will contribute to the future study for evaluating the minimum required stiffness and optimum design of U-rib stiffened plates.

• Korean Journal of Remote Sensing
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• v.34 no.3
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• pp.481-494
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• 2018

The accurate radiative transfer model simulation is essential for an accurate ozone profile retrieval using optimal estimation from backscattered ultraviolet (BUV) measurement. The input parameters of the radiative transfer model are the main factors that determine the model accuracy. In particular, meteorological parameters such as temperature and surface pressure have a direct effect on simulating radiation spectrum as a component for calculating ozone absorption cross section and Rayleigh scattering. Hence, a sensitivity of UV ozone profile retrievals to these parameters has been investigated using radiative transfer model. The surface pressure shows an average error within 100 hPa in the daily / monthly climatological data based on the numerical weather prediction model, and the calculated ozone retrieval error is less than 0.2 DU for each layer. On the other hand, the temperature shows an error of 1-7K depending on the observation station and altitude for the same daily / monthly climatological data, and the calculated ozone retrieval error is about 4 DU for each layer. These results can help to understand the obtained vertical ozone information from satellite. In addition, they are expected to be used effectively in selecting the meteorological input data and establishing the system design direction in the process of applying the algorithm to satellite operation.

• Journal of Korean Society of Transportation
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• v.32 no.2
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• pp.83-92
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• 2014

Weather condition is one of the crucial factors affecting travelers' mode choice. Nevertheless, there are numerous indefinite traffic phenomena under various weather conditions. This study was conducted to verify the hypothesis that transit riderships decrease as precipitation increases. To clarify the relationship between precipitation and transit ridership, a seemingly unrelated regression model was employed with data such as daily precipitation and daily transit riderships of 3 transit modes (bus, metro, and shuttle bus) collected in Busan for recent 24 months. The estimation results show that transit riderships decreased as the daily precipitation increased when the daily precipitation is greater or equal to 10mm/day (0.169%, 0.101%, and 0.172% reduction in bus, metro, and shuttle bus riderships, respectively, when the daily precipitation increased by 1mm). When comparing the impact of precipitation on transit riderships by modes using a cross-equation parameter restriction test, the decrease in metro ridership is relatively insensitive to the change in precipitation. However, the negative coefficient of precipitation in the metro ridership estimation model indicates that the transit users in Busan may alter their mode to taxi or automobile and/or may give up the trip itself in bad weather condition.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.11
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• pp.770-777
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• 2017

Building information modeling (BIM) has been receiving attention as an integrated information model instead of CAD since the 2000s. BIM technology was first used in the architectural field and was later introduced to the civil engineering field. However, the government announced a plan for the application of BIM to 20% of all SOC projects from 2020, so the adoption of BIM technology is expected to accelerate. In order to successfully adopt BIM, a systematic structure should be supported for integrated design information and implementation technology. Also, it is important to establish the relationship between information systems because many complicated factors are intertwined in the construction industry. In this study, we propose a framework for constructing integrated information through identifying the information relations for introducing BIM in the civil engineering industry. We applied this framework to a bridge project to confirm its effectiveness. This study can be applied to the integrated management of the construction process and costs by introduction of a work breakdown structure (WBS) to BIM. In addition, this study is expected to contribute to the adoption of BIM in the civil engineering field through the proposal of information system standardization in this field.

• Journal of Advanced Navigation Technology
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• v.6 no.1
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• pp.37-43
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• 2002

This paper describes the performance evaluation and analysis of Wireless Local Area Network (W-LAN) in the 5 GHz ISM-band in compliance with IEEE 802.11a. At present, most W-LAN products are based on 2.4 GHz band, but low speed (11Mbps) has the limitation to serve systems demanding high-speed data transmission. To solve this problem, it is necessary to design next generation W-LAN system with 54Mbps in the 5GHz. It is sure that implementation of next generation W-LAN will bring competitive advantages. In particular, it will support telecommunications for high-speed mobile environments as well as for fixed places such as a school zone, a lecture room, a hospital and other premises. A few simulation methods are applied to more accurate and reliable performance analysis of next generation W-LAN. To verify if continuous data service is supported for a high-speed mobile notebook, multi-path fading channels between wireless Access Point (AP) and wireless Network Interface Card (NIC) are modeled. In addition, low interference is analyzed via convolutional codes and Orthogonal Frequency-Division Multiplexing (OFDM). Also, to obtain reliable Bit Error Rate (BER), a single tap Least Mean Square (LMS) equalizer is applied. Given the above simulation, next generation W-LAN is an ideal solution for continuous data transmission in high-speed mobile environments.