• Journal of the Korean GEO-environmental Society
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• v.22 no.12
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• pp.33-40
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• 2021

The deterioration of underground facilities, disturbance of the ground due to underground development activities, and changes in ground water can cause ground subsidence accidents in the urban areas. The investigation on the geotechnical and hydraulic factors affecting the ground subsidence accident is very significant to predict the ground subsidence risk in advance. In this study, an analysis DB was constructed through 3D ground modeling to utilize the currently operating geotechnical survey information DB and ground water behavior information for risk prediction. Additionally, using these results, the relationship between the actual ground subsidence occurrence history and ground conditions and ground water level changes was confirmed. Furthermore, the methodology used to visualize the risk of ground subsidence was presented by reconstructing the engineering characteristics of the soil presented according to the Unified Soil Classification System (USCS) in the existing geotechnical survey information into the internal erosion sensitivity of the soil, Based on the result, it was confirmed that the ground in the area where the ground subsidence occurred consists of more than 40% of sand (SM, SC, SP, SW) vulnerable to internal erosion. In addition, the effect of the occurrence frequency of ground subsidence due to the change in ground water level is also confirmed.

• 한국정보통신설비학회:학술대회논문집
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• 2007.08a
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• pp.227-230
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• 2007

In this paper, we have analyzed the change characteristics of induced noise due to the impedance change of the ground in both ends of telecommunication line. As what affects the induced noise, there are power influence or longitudinal transverse voltages and its weighted filtered voltage. In the result of measurement, we can see the noise level change due to the change of the ground impedance, that is, as the ground impedance at either end of the telecommunication line become grower, the noise level is increased, and as the ground impedance at either end of the telecommunication line become smaller, the noise level is decreased. However, we can't define the relation between ground impedance size and PIF in these measurement results, so we will have to carry out the measurement more deeply and more practically with various conditions in environmental viewpoint and/or experimental viewpoint to establish the definition between ground impedance size and PIF.

• Proceedings of the KSRS Conference
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• 2002.10a
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• pp.810-814
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• 2002

According to the image level definition for KOMPSAT-2 in KOMPSAT-2 Ground Station Specification, the level 0 is frame formatted, unprocessed data at full resolution; any and all communications artifacts (e.g., synchronization frames, communications headers) removed. The level 0 is used for two purposes: 1) exchange of imagery between image receiving & processing element (IRPE), and 2) image transfer from the Receiving & Archiving Subsystem to Search & Processing Subsystem. On-board processing of imagery data of KOMPSAT-2 includes JPEG-like compression and encryption besides conventional CCSDS packetization. The encryption is used to secure imagery data from any intervention during downlink and compression allows real-time downlink of image data reducing data rate produced from the camera. While developing ground receiving system for KOMPSAT-2, it was necessarily to define level 0 products. In this paper, we will suggest level 0 product definition for KOMPSAT-2 and explain reasons of the decisions made. The key factor used while defining the level 0 products is the efficiency of whole ground receiving system. The latter half of the paper will explain the implementation of software that generates level 0 products. The necessary steps to produce level 0 products will be explained, and the performance achieved will be presented.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.19 no.5
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• pp.408-417
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• 2007

Recently, an artificial beach has been constructed compensating for loss of the natural one caused by the development of coastal area, as well as serving as a location for recreational activities such as sea bathing. It is well known that some structure should be constructed to protect an artificial beach from the outflow due to wave action of the reclaimed sand. In general, dike is utilized as the structure to protect an artificial beach. And, one of the factors which may need to be taken into consideration for stability of dike on seabed foundation is the ground water behavior behind dike. However, the interrelated phenomena of nonlinear wave and ground water response have relatively little attention although these interactions are important for stability of structure and sand suction to the artificial beach. In this paper, the numerical wave tank was developed to clarify nonlinear wave, dike and ground water dynamic interaction, which can simulate the difference of ground water and mean water level. Using the developed numerical wave tank, the present study investigates how variation of ground water level influences hydrodynamic characteristics in seabed around dike and numerically simulates the wave fields, pore flow patterns, pore water pressures and vorticities according to variation of ground water level. Numerical results explain well how hydrodynamic characteristics in seabed around dike is affected by the variation of ground water level.

• Korean Journal of Applied Biomechanics
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• v.25 no.3
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• pp.241-248
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• 2015

Objective : The purpose of this study was to investigate the theta on the components of ground reaction force according to the ground conditions during gait. Method : Six healthy women(mean age: 22 yrs, mean height: $166.14{\pm}2.51cm$, mean body weights: $56.61{\pm}4.58kg$) participated in this study. The medial-lateral GRF(Fx 1), anterior-posterior GRF(Fy 1, Fy 2), vertical GRF(Fz 1, Fz 2, Fz 3), and impact loading rate were determined from time function and frequency domain. Also, GRF theta were time function and forces. Results : Fx 1, Fy 1 and Fy 2 of stair descending showed significant statistically higher forces than that of level walking, and ascending. Fz 1 of stairs descending showed significant statistically higher forces than that of level walking and stairs ascending(theta $88.62^{\circ}$). Also, Fz 2 of level walking showed significant statistically higher forces than that of stairs ascending and descending(theta $65.78^{\circ}$). Fz 3 of stairs ascending showed significant statistically higher forces than that of level walking and stairs descending($65.26^{\circ}$). Impact loading rate of stairs descending showed significant statistically higher forces than that of level and ascending walking. The GRF showed similar correlation with GRF theta(r=.603) according to the ground conditions during gait. Conclusion : These results suggest that the GRF theta can be used in conjunction with a gait characteristics, prediction of loading rate and dynamic stability.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2000.04a
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• pp.97-104
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• 2000

Evaluating a Review-Level Ground Motion is a key to efficiently perform Seismic Margin Assessment of nuclear power plants whose purpose is to determine a ground motion level for which a plant has high-confidence-of-a-low-probability of seismic-induced core damage and to identify any weaker-link components. In this study a method to obtain RLGMs is reviewed which is recommended by Electric Power Research Institute and implemented to be applied to Limerick site in eastern and central U. S as a case study. This method provides reasonable and site-specific RLGMs as minimum required plant HCLPF for SMA that meet a target mean seismic core-damage frequency based on seismic hazard results and generic values of uncertainty and randomness parameters of the core-damage fragility curves. In addition high-frequency RLGM is justifiably modified to reflect the increased seismic capacity of high-frequency components and spatial variation and incoherence of input ground motion on a basemat of large structures by establishing a method to obtain high0-frequency reduction factors according to EPRI guidelines.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.1120-1125
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• 2006

Larger area will be constructed in a harbor land and container terminal which are constructed in reclaimed land using the dredged materials. Soil improvement work is to be carried out including constructibility, in which is monitoring devices, measuring frequency, installations etc. The ground water tables in the reclaimed area are affected by the several factors which are design reclamation level, consolidation settlement, remaining surcharge pressure and remaining excess pore water pressure. The plan wii be drawn up in which monitoring results for the ground water tables are capable to provide the reliable ground water table when designers and civil engineers construct the harbor structures considering constructibility.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.521-526
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• 2004

In order to evaluate the effect of blasting vibration in buildings and it's resident located around blasting construction field in urban area, blasting vibration characteristics were measured the vibration level, vibration velocity. The 250g and 750g of charged powder were used at the apartment and at the ground, respectively. In the measurement of the ground, Z(perpendicularity) axis was the highest value in vibration level, but vertical axis was the highest value at 25m point and longitudinal axis was the highest value at 50m point in vibration velocity. The amount of measurement was high value when measuring point is higher than blasting source, while that of measurement was low value when measuring point is lower than blasting source. In the measurement of the apartment, 2 axis was the highest value in vibration level, but in vibration velocity transverse axis was the highest value at ground, was vertical axis at 1st floor, was longitudinal axis at 3rd floor and was vertical and longitudinal axis at 5th floor. The vibration level and the vibration velocity of 50m point showed higher correlation value than 25m point at the ground, but those of 25m point showed higher correlation value than 50m point at the apartment.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.7
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• pp.632-638
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• 2004

In order to evaluate the effect of blasting vibration in buildings and it's resident located around blasting construction field in urban area, blasting vibration characteristics were measured by the vibration level, vibration velocity. The 250g and 750g of charged powder were used at the apartment and at the ground, respectively. In the measurement of the ground, 2 (perpendicularity) axis was the highest value in vibration level, but vertical direction was the highest value at 25 m point and longitudinal direction was the highest value at 50 m point in vibration velocity. The amount of measurement was high value when measuring point is higher than blasting source, while that of measurement was low value when measuring point is lower than blasting source. In the measurement of the apartment, Z axis was the highest value in vibration level, but in vibration velocity transverse direction was the highest value at ground, was vertical direction at 1st floor, was longitudinal direction at 3rd floor and was vertical and longitudinal direction at 5th floor. The vibration level and the vibration velocity of 50 m point showed higher correlation value than 25 m point at the ground, but those of 25 m point showed higher correlation value than 50 m point at the apartment.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.39 no.6
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• pp.585-593
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• 1994

This study was conducted to know optimum ground water level for maize(Suwon 19) and sorghum-sudangrass hybrid(Pioneer855F) and investigated effect of different soil types and ground water levels on growth of above two crops at containers were controlled so as to be 25, 35, 50, 70 and 100cm from the soil surface. Both crops showed better growth in sandy loam soil. Optimum ground water level for maize was l00cm and for sorghum-sudangrass hybrid was 70cm in sandy loam soil. Clay loam was unfavorable for both crops even though low ground water level maintained. Sorghum-sudangrass hybrid was adapted better to clay loam soil and high ground water levels. In microscopic study on root anatomy of both crops, destructed cortical tissues were observed. Frequency of the tissues was higher in maize than in sorghum-sudangrass hybrid and higher at mid or tip parts than basal parts of roots in both crops. Arrangement of cortical cells of roots in sorghum-sudangrass hybrid were more regular than those of maize. In root anatomy, no consistent trend with soil types or ground water levels was detcted.