• Geophysics and Geophysical Exploration
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• v.9 no.1
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• pp.30-36
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• 2006

Japan's first pilot-scale $CO_2$ sequestration experiment has been conducted in Nagaoka, where 10400 t of $CO_2$ have been injected in an onshore aquifer at a depth of about 1100 m. Among various measurements conducted at the site for monitoring the injected $CO_2$, we conducted time-lapse crosswell seismic tomography between two observation wells to determine the distribution of $CO_2$ in the aquifer by the change of P-wave velocities. This paper reports the results of the crosswell seismic tomography conducted at the site. The crosswell seismic tomography measurements were carried out three times; once before the injection as a baseline survey, and twice during the injection as monitoring surveys. The velocity tomograms resulting from the monitoring surveys were compared to the baseline survey tomogram, and velocity difference tomograms were generated. The velocity difference tomograms showed that velocity had decreased in a part of the aquifer around the injection well, where the injected $CO_2$ was supposed to be distributed. We also found that the area in which velocity had decreased was expanding in the formation up-dip direction, as increasing amounts of $CO_2$ were injected. The maximum velocity reductions observed were 3.0% after 3200 t of $CO_2$ had been injected, and 3.5% after injection of 6200 t of $CO_2$. Although seismic tomography could map the area of velocity decrease due to $CO_2$ injection, we observed some contradictions with the results of time-lapse sonic logging, and with the geological condition of the cap rock. To investigate these contradictions, we conducted numerical experiments simulating the test site. As a result, we found that part of the velocity distribution displayed in the tomograms was affected by artefacts or ghosts caused by the source-receiver geometry for the crosswell tomography in this particular site. The maximum velocity decrease obtained by tomography (3.5%) was much smaller than that observed by sonic logging (more than 20%). The numerical experiment results showed that only 5.5% velocity reduction might be observed, although the model was given a 20% velocity reduction zone. Judging from this result, the actual velocity reduction can be more than 3.5%, the value we obtained from the field data reconstruction. Further studies are needed to obtain more accurate velocity values that are comparable to those obtained by sonic logging.

• Journal of the Korean Society for information Management
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• v.4 no.1
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• pp.154-169
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• 1987

The Computerizing Record Management System(RMS) has been developed for ULJIN Nuclear Power Plant in Korea on the basis of the Manual System. By means of review and analysis of processing flow & project requirements, system logics such as Receiving system, Logging system, Distribution system, Filing system, Indexing & Retrieval system and Output system of statistic and various reports, have been established for computerizing. Structure of Masterfile has been designed so as to include Bibliographic data, Transmittal data, Distribution data, Area data, RMS data for operation of Plant. The RMS data have been designed for construction and operation of the plant by adding index parameters for operation such as System code, KEPCO No., Component link code and Retention period on the point of receiving. The RMS has turned out an easy access to cross-reference between RMS and Material Control System.

• Journal of the Korean Society for information Management
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• v.4 no.2
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• pp.139-151
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• 1987

The Computerizing Record Management System(RMS) has been developed for ULJIN Nuclear Power Plant in Korean on the basis of the Manual System. By means of review and analysis of processing flow & project requirements, system, logies such as Receiving system, Logging system, Distribution system, Filing system, Indexing & Retrieval system and Output system of statistic and various reports, have been established for computerizing. Structure of Masterfile has been designed so as to include Bibliographic data, Transmittal data, Distribution data, Area, data, RMS data for operation of Plant. The RMS data have been designed for construction and operation of the plant by adding index parameters for operation such as System code, KEPCO No., Component link code and Retention period on the point of receiving. The RMS has turned out an easy access to cross-reference between RMS and Material Control System.

• Convergence Security Journal
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• v.2 no.2
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• pp.189-198
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• 2002

In this paper, we have designed the Web_based Home Gateway Management System using SSL, which can manage subscribers using Home Gateway device in home networking technology. To manage Home Gateway devices with SNMP, management elements are classified into system. performance. fault functional area based on MIB objects from Home Gateway devices MIB. System analysis provides configuration information of each Home Gateway, and Performance analysis provides device's traffic information and state. And fault analysis provides fault logging for the unexpected events and trap message from devices. HGMS uses SSL (Secure Socket Layer) to enforce the security of communication which is between server and client, and it improved the stability of HGMS.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.7
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• pp.1401-1407
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• 2002

This paper represents an investigation of the vehicle-to-vehicle distance control system using Hardware-in-the-Loop Simulation(HiLS). Control logic is primarily developed and tested with a specially equipped test vehicle. Establishment of an efficient and low cost development tool is a very important issue, and test vehicle approach is costly and time consuming. HiLS method is useful in the investigation of driver assistance and active safety systems. The HiLS system consists of a stepper motor for throttle control, a hydraulic brake system with an electronic vacuum booster, an electronic controller unit, a data logging computer which are used to save vehicle states and signals of actuator through a CAN and a simulation computer using mathematical vehicle model. Adaptation of a CAN instead of RS-232 Serial Interface for communication is a trend in the automotive industry. Since this environment is the same as a test vehicle, a control logic verified in laboratory can be easily transferred to a test vehicle.

• Journal of the Korean Geophysical Society
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• v.5 no.3
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• pp.219-231
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• 2002

Single beam echo sounding was used to delineate bathymetry sea bottom in the area of hydrography and marine navigation. This research was aimed at measuring the thickness of floating silty clay sediment with dual frequencies echo sounding system. There occur discrepancies in penetrating depth through sea beds between high frequency(200 KHz) and low(33 KHz) frequency. RI density logging was employed to characterize the floating silty clay sediment of Guangyang bay, which was chosen to investigate the proposed site for reclamation field. The volume of floating silty clay sediment was used to design by estimating size of reclamation site. The estimation strategies developed in this study will be readily applicable to measure the Pattern of sedimentation via regular hydrographic survey in the future.

• 한국지구물리탐사학회:학술대회논문집
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• 2003.11a
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• pp.455-458
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• 2003

A combination of drilling, hydrogeochemical survey, geophysical survey and the numerical modelling for the flow and transport of groundwater was performed to evaluate the seawater intrusion in Baeksu-eup, Yeonggwang-gun, Korea. The survey area extends to over 24 $km^2$. Twelve wells were also drilled for the collection of geologic, geochemical, hydrologic, and geophysical logging data to delineate the degree and vertical extent of seawater intrusion. To evaluate and map the salinity in a coastal aquifer, geophysical data and hydrogeochemical results were used. Layer parameters derived from VES data, various in situ physical properties from geophysical well loggings, and the estimated equivalent NaCl concentration were used as the useful input parameters for the numerical simulation with density-dependent flow. Our multidisciplinary approach for evaluating the seawater intrusion can be considered as a valuable attempt to enhancing the utilization of various data and the reliability of numerical ground modelling.

• Nuclear Engineering and Technology
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• v.44 no.7
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• pp.781-790
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• 2012

The HyperGam program was developed for the analysis of complex HPGe ${\gamma}$-ray spectra. The previous version of HyperGam was mainly limited to the analysis of ${\gamma}$-ray peaks and the manual logging of the result. In this study, it is specifically developed into a tool for the isotopic analysis of spectra. The newly developed features include nuclide identification and activity determination. An algorithm for nuclide identification was developed to identify the peaks in the spectrum by considering the yield, efficiency, energy and peak area for the ${\gamma}$-ray lines emitted from the radionuclide. The detailed performance of nuclide identification and activity determination was accessed using the IAEA 2002 set of test spectra. By analyzing the test spectra, the numbers of radionuclides identified truly (true hit), falsely (false hit) or missed (misses) were counted and compared with the results from the IAEA 2002 tests. The determined activities of the radionuclides were also compared for four test spectra of several samples. The result of the performance test is promising in comparison with those of the well-known software packages for ${\gamma}$-ray spectrum analysis.

• Geosciences Journal
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• v.22 no.6
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• pp.1027-1039
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• 2018

Seismic attributes are often used to identify lithology and evaluate reservoir properties. However, interpretation based only on structural attributes and without knowledge of the Vp/Vs ratio can limit the ability to evaluate changes in heavy oil reservoirs. These limitations are often due to less obvious impedance differences. In order to investigate pieces of evidence of a heavy-oil shaly-sand reservoir from seismic data, besides geochemistry, we studied seismic attributes and characterized the reservoir using seismic stack data and well logging data. The study area was the Muglad rift basin in South Sudan. We conducted a seismic complex analysis to evaluate the target reservoir. To delineate the frequency responses of the different lithological units, we applied the spectral decomposition method to the target reservoir. The most unexpected result was continuous bands of strong seismic reflectors in the target reservoir, which extended across the borehole. Spectral decomposition analysis showed that the low-frequency zone of 25 Hz dominant frequency was consistent with instantaneous attributes. This approach can identify lithology, reveal frequency anomalies, and filter the stacked section into low- and high-frequency bands. The heavy-oil reservoir zones exhibited velocity attenuation and the amplitude was strongly frequency dependent.

• Journal of Forest and Environmental Science
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• v.39 no.4
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• pp.203-212
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• 2023

Directional felling is a felling method practised by the Forestry Department in Peninsular Malaysia as prescribed in Field Work Manual (1997) for Selective Management Systems (SMS) in forest harvesting. Determining the direction of tree felling in Peninsular Malaysia is conducted during the pre-felling inventory 1 to 2 years before the felling operation. This study aimed to predict and analyze the direction of tree felling using the vector-based path distance back link method in Geographic Information Systems (GIS) and compare it with the felling direction observed on the ground. The study area is at Balah Forest Reserve, Kelantan, Peninsular Malaysia. A Path Distance Back Link (spatial analyst) function in ArcGIS Pro 3.0 was used in predicting tree felling direction. Meanwhile, a binary classification was used to compare the felling direction estimated using GIS and the tree felling direction observed on the ground. Results revealed that 61.3% of 31 trees predicted using the vector-based projection method were similar to the felling direction observed on the ground. It is important to note that dynamic changes of natural constraints might occur in the middle of tree felling operation, such as weather problems, wind speed, and unpredicted tree falling direction.