• Journal of the Computational Structural Engineering Institute of Korea
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• v.15 no.2
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• pp.209-218
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• 2002

The Vector Random Decrement technique has been developed as an efficient method for transforming ambient responses into free decays of linear structures. It is shown that the VRD functions nay contain as much information about the modes as the really measured free decay responses. In this paper, the theory of the VRD technique is extended by applying the concept of the mode shape ratio into the Ibrahim Time Domain modal parameter identification algorithm. The VRD function is not shifted in the correction procedures for constant time shifts of the proposed VRD technique. Thus, a number of points equal to the largest of the time shifts used in the vector triggering condition are not deleted. In the VRD functions, any influence of the input to the system is averaged out. The proposed technique is compared with the traditional VRD technique by assessment of the modal parameters. The applicability of the VRD technique has been justified through a simulation study and a study of the response of a laboratory beam model subject to ambient loads.

• Journal of the Korean Association of Geographic Information Studies
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• v.19 no.3
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• pp.61-74
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• 2016

The purpose of this paper is to analyze the relationship between the location of the epicenter of a medium-sized earthquake(magnitude 4.8) that occurred on January 20, 2007 in the Odaesan area with lineament features using a shaded relief map(1/25,000 scale) and satellite images from LANDSAT-8 and KOMPSAT-2. Previous studies have analyzed lineament features in tectonic settings primarily by examining two-dimensional satellite images and shaded relief maps. These methods, however, limit the application of the visual interpretation of relief features long considered as the major component of lineament extraction. To overcome some existing limitations of two-dimensional images, this study examined three-dimensional images, produced from a Digital Elevation Model and drainage network map, for lineament extraction. This approach reduces mapping errors introduced by visual interpretation. In addition, spline interpolation was conducted to produce density maps of lineament frequency, intersection, and length required to estimate the density of lineament at the epicenter of the earthquake. An algorithm was developed to compute the Value of the Relative Density(VRD) representing the relative density of lineament from the map. The VRD is the lineament density of each map grid divided by the maximum density value from the map. As such, it is a quantified value that indicates the concentration level of the lineament density across the area impacted by the earthquake. Using this algorithm, the VRD calculated at the earthquake epicenter using the lineament's frequency, intersection, and length density maps ranged from approximately 0.60(min) to 0.90(max). However, because there were differences in mapped images such as those for solar altitude and azimuth, the mean of VRD was used rather than those categorized by the images. The results show that the average frequency of VRD was approximately 0.85, which was 21% higher than the intersection and length of VRD, demonstrating the close relationship that exists between lineament and the epicenter. Therefore, it is concluded that the density map analysis described in this study, based on lineament extraction, is valid and can be used as a primary data analysis tool for earthquake research in the future.

• Economic and Environmental Geology
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• v.39 no.2 s.177
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• pp.111-128
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• 2006

Three dimensional crustal structure and source features of earthquake hypocenters on the Korean peninsula were investigated using P and S-wave travel time tomography. The main goal of this research was to find Vp/Vs anomalies at earthquake hypocenters as well as those of crustal structure of basins and deep tectonic settings. This allowed fer the extrapolation of more detailed seismotectonic force from the Korean peninsula. The earthquake hypocenters were found to have high Vp/Vs ratio discrepancies (VRD) at the vertical sections. High V/p/Vs ratios were also found in the sedimentary basins and beneath the Chugaryong Rift Zone (CRZ), which was due to mantle plume that subsequently solidified with many fractures and faults which were saturated with connate water. The hypocenters of most earthquakes were found in the upper crust for Youngwol (YE), Kyongju (KE), Hongsung (HE), Kaesong (KSE), Daekwan (DKE), and Daehung (DHE) earthquakes, but near the subcrust or the Moho Discontinuity for Mt. Songni (SE), Sariwon (SRE) and Mt. Jiri (JE) earthquakes. Especially, we found hot springs of the Daekwan, Daehung and Unsan regions coincide with high VRD. Also, this cannot rule out the possibility that there are some partial meltings in the subcrust of this region. High VRD might indicate that many faults and fractures with connate water were dehydrated when earthquakes took place, reducing shear modulus in the hypocenter areas. This is can be explained by due to the fact that a point source which is represented by the moment tensor that may involve changes in volume, shear fracture, and rigidity. High Vp/Vs ratio discrepancies (VRD) were also found beneath Mt. Backdu beneath 40 km, indicating that magma chamber existed beneath Mt. Backdu is reducing shear modulus of S-wave velocity.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.852-855
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• 2012

A DC-DC converter for EEPROM IPs which perfom erasing by the FN (Fowler-Nordheim) tunneling and programming by the band-to-band tunneling is designed in this paper. For the DC-DC converter for EEPROM IPs using a low voltage of $1.5V{\pm}10%$ as the logic voltage, a scheme of using VRD (Read Voltage) instead of VDD is proposed to reduce the pumping stages and pumping capacitances of its charge pump circuit. VRD ($=3.1V{\pm}0.1V$) is a regulated voltage by a voltage regulator using an external voltage of 5V. The designed DC-DC converter outputs VPP (=8V) and VNN (=-8V) in the write mode.

• Journal of Preventive Medicine and Public Health
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• v.36 no.2
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• pp.171-178
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• 2003

Objective : The aim of this study was to identify the validity of recruiting medical checkup participants of Vietnam veterans using a mail survey, and to identify the 'Vietnam service related characteristics' and 'general characteristics' of Vietnam veterans groups, Method : In this study, a total 900 veterans were randomly selected from the list of Vietnam veterans from f964 to 1973. The veterans were classified into 5 groups, taking into consideration their registered status in the Ministry of Patriots and Veterans Affairs: the VRD (veterans who have agent orange-related diseases), VSD (veterans who have agent orange-suspected disease), VM (veterans who peformed meritorious deeds during the war), VR (veterans who were registered with the Ministry of Patriots and Veterans Affair) and OV (other veterans) groups. By means of postal surveys, the veterans' intention to participate in the medical checkup for our research, and their socioeconomic and general characteristics were investigated. 52 surveys were returned due to the subjects not residing at the listed address, and were excluded from the analysis. Result : 699 of the 848 veterans (82.4%) responded to the survey, of which 619 (88.6%) intended to participate in the medical checkup for our research. The S veterans groups all had similar ages, Vietnam service period, Agent Orange exposure, troop characteristic and wartime class, with the exception of VM, who were older, and with a greater number of officers than the other 4 groups, There was a big difference in the health statius among the Vietnam veterans group. The VM and OV were much healthier than VRD, VSD and VR groups, The socioeconomic stati of the VRD, VSD and VR groups were lower than those of the VM and OV groups. Conclusion : Although there were some limitations, the recruitment, by mail, of medical checkup participants from Vietnam veterans is a valid and feasible method. The VM and OV groups were much healthier, and with higher socioeconomic stati, than the VRD, VSD, and VR groups.

• Proceedings of the Membrane Society of Korea Conference
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• 2002.07a
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• pp.47-57
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• 2002

• Korean Journal of Environmental Agriculture
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• v.37 no.3
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• pp.151-159
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• 2018

BACKGROUND: In this review paper, the effects of surface cover (SCV), vegetative filter strip (VFS), and vegetated ridge (VRD) on the pollutant runoff from steep-sloping uplands were analyzed to compare the pollutant reduction efficiency in runoff ($PRE_{runoff}$) of the practices and to investigate how slope and rainfall parameters affect the $PRE_{runoff}$. METHODS AND RESULTS: The $PRE_{runoff}$ of SCV, VFS, and VRD for pollutants including suspended solids and biological oxygen demand was compared by analysis of variance. The effect of slope and rainfall parameters on the $PRE_{runoff}$ was explored by either mean comparison or regression analysis. It was found that the $PRE_{runoff}$ differs with the practices due to different pollutant reduction mechanisms of the practices. Though the $PRE_{runoff}$ was likely to be affected by site condition such as slope and rainfall (amount and intensity), more comprehensive understanding was not possible due to the limited data set. CONCLUSION: The $PRE_{runoff}$ of SCV, VFS, and VRD differed due to the distinctive mechanisms of pollutant removal of the practices. It is necessary to accumulate experimental data across a variety of gradient of slope and rainfall for comprehensive understanding of the effects of the practices on pollutant runoff from steep-sloping uplands.

• ETRI Journal
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• v.42 no.3
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• pp.399-410
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• 2020

Detecting visual relationships in an image is important in an image understanding task. It enables higher image understanding tasks, that is, predicting the next scene and understanding what occurs in an image. A visual relationship comprises of a subject, a predicate, and an object, and is related to visual, language, and spatial cues. The predicate explains the relationship between the subject and object and can be categorized into different categories such as prepositions and verbs. A large visual gap exists although the visual relationship is included in the same predicate. This study improves upon a previous study (that uses language cues using two losses) and a spatial cue (that only includes individual information) by adding relative information on the subject and object of the extant study. The architectural limitation is demonstrated and is overcome to detect all zero-shot visual relationships. A new problem is discovered, and an explanation of how it decreases performance is provided. The experiment is conducted on the VRD and VG datasets and a significant improvement over previous results is obtained.