• Journal of the Korean earth science society
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• v.42 no.1
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• pp.39-54
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• 2021

Damyang Wetland, a riverine wetland, has been designated as the first wetland protection area in South Korea and is a candidate area for the Mudeungsan Area UNESCO Global Geopark. The Damyang Wetland area is the upstream part of the Yeongsan River and is now a relatively wide plain. To reconstruct the sedimentary environment around the Damyang Wetland, core samples were obtained, and sedimentary facies analysis, AMS and OSL age dataings, grain size, and geochemical analyses were carried out. In addition, comprehensive sedimentary environment changes were reconstructed using previous core data obtained from this wetland area. In the Yeongsan River upstream area, where the Damyang Wetland is located, fluvial terrace deposits formed during the late Pleistocene are distributed in an area relatively far from the river. As a gravel layer is widely distributed throughout the plains, Holocene sediments were likely deposited in a braided river environment when the sea level stabilized after the middle Holocene. Then, as the sedimentary environment changed from a braided river to a meandering river, the influx of sand-dominated sediments increased, and a floodplain environment was formed around the river. In addition, based on the pollen data, it is inferred that the climate was warm and humid around 6,000 years ago, with wetland deposits forming afterward. The the trench survey results of the river area around the Damyang Wetland show that a well-rounded gravel layer occurs in the lower part, covered by the sand layer. The Damyang Wetland was likely formed after the construction of Damyang Lake in the 1970s, as muddy sediments were deposited on the sand layer.

• Journal of the Korean Geosynthetics Society
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• v.12 no.4
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• pp.1-10
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• 2013

Recently, the closed landfills are usually converted into parks or playground by the check the stability of landfill because they settle unevenly making them unsuitable for structures. When the closed landfill reuse, environmental and structural stability is important. To increase the bearing capacity and reduce the probable settlement of a foundation on waste disposal ground, a layer of geosynthetics(Geocell) is placed on the waste disposal ground. In this paper, the analysis of long-term settlement parameter correlation was performed, also the evaluation of bearing capacity reinforcement effect was conducted by field test. The settlement measured in the field, and input the same ground index when an integer to identify each model were compared by calculating the settlement. In addition, by adjusting the parameters of each model to identify the most similar to the value of field measurement parameters were calculated. Based on the analysis results, when the using the Park's model C(intermediate) = 0.0678, the expected settlement is similar to the field measurement results. Also, the bearing capacity of geocell reinforced ground is 1.193~1.554 times higher than that of unreinforced ground.

• The Journal of the Acoustical Society of Korea
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• v.21 no.8
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• pp.708-718
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• 2002

In this paper, the problems in identifying the noise sources by using the sound intensity technique are dealt with for the general radiated near-field from vibro-acoustic sources. For this purpose, a three-dimensional model structure resembling the engine room of a car or heavy equipment is considered. Similar to the practical situations, the model contains many mutually coherent and incoherent noise sources distributed on the complicated surfaces. The sources are located on the narrow, connected, reflecting planes constructed with rigid boxes, of which a small clearance exists between the whole box structure and the reflecting bottom. The acoustic boundary element method is employed to calculate the acoustic intensity at the near-field surfaces and interior spaces. The effects of relative source phases, frequencies, and locations are investigated, from which the results are illustrated by the contour map, vector plot, and energy streamlines. It is clearly observed that the application of sound intensity technique to the reactive or reverberant field, e.g., scanning over the upper engine room as is usually practiced, can yield the detection of fake sources. For the precise result for such a field, the field reactivity should be checked a priori and the proper effort should be directed to reduce or improve the reactivity of sound field.

• Journal of Dental Rehabilitation and Applied Science
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• v.34 no.2
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• pp.116-126
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• 2018

Purpose: The purpose of this study was to analyze the factors affecting the survival rate and the marginal bone level of dental implants that have functioned over 7-years. Materials and Methods: In 92 patients, 178 dental implants were included. Implant-related factors (diameter, length, prosthetic splint), patient-related factors (gender, smoking, plaque index, compliance to supportive periodontal therapy) and surgery-related factors (proficiency of surgeon, bone graft) were evaluated via clinical and radiographic examination. The marginal bone level was determined by intraoral standard radiography at the mesial and distal aspects of each implant using an image analysis software program. Results: The survival rate of all the implants was 94.94% and the marginal bone level was $0.89{\pm}1.05mm$, these results are consistent with other studies that present long-term good clinical results. Implant length and plaque index among several factors were statistically significant for implant survival rate (P < 0.05). Smoking and the presence of regeneration surgery were statistically significant for the marginal bone level (P < 0.05). Conclusion: Dental implant that have functioned over 7-years showed favorable long-term survival rates and marginal bone level. Implant length and plaque control should be considered for improving the long-term clinical results. It is needed that careful application of bone regeneration technique and smoking control for maintaining of marginal bone level.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.9 no.1
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• pp.13-21
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• 2011

To characterize the site specific properties of a study area for high-level radioactive waste disposal research in KAERI, the several geological investigations such as surface geological surveys and borehole drillings were carried out since 1997. Especially, KURT (KAERI Underground Research Tunnel) was constructed to understand the further study of geological environments in 2006. As a result, the first geological model of a study area was constructed by using the results of geological investigation. The objective of this research is to construct a hydrogeological model around KURT area on the basis of the geological model. Hydrogeological data which were obtained from in-situ hydraulic tests in the 9 boreholes were estimated to accomplish the objective. And, the hydrogeological properties of the 4 geological elements in the geological model, which were the subsurface weathering zone, the log angle fracture zone, the fracture zones and the bedrock were suggested. The hydrogeological model suggested in this study will be used as input parameters to carry out the groundwater flow modeling as a next step of the site characterization around KURT area.

• Journal of Korean Tunnelling and Underground Space Association
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• v.22 no.1
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• pp.23-46
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• 2020

In the current work, a series of three-dimensional finite element analyses have been carried out to understand the behaviour of pre-existing single piles to adjacent tunnelling by considering the tunnel face pressures and the relative location of pile tips with respect to the tunnel. The numerical modelling has analysed the effect of the face pressures on the pile behaviour. The analyses concentrate on the ground settlements, the pile head settlements, the axial pile forces and the shear stress transfer mechanism at the pile-soil interface. The head settlements of the pile (the vertical distance between the pile and the tunnel: 0.25D, where D is the tunnel diameter) directly above the tunnel crown with the face pressure 50% of the in-situ horizontal soil stress at the tunnel springline decreased by about 38% compared to corresponding settlements with a face pressure 25% of the in-situ horizontal soil stress at the tunnel springline. Furthermore, it was found that the smaller the face pressure, the larger the tunnelling-induced ground movements and the axial pile forces were and the higher the degree of the shear strength mobilisation at the pile-soil interface. When the piles were outside the tunnel influence zone, compressive pile forces were developed due to tunnelling. It has been found that the ground settlements and the pile settlements are heavily affected by the face pressures and the position of the pile tip relative to the tunnel. In addition, the computed results have been compared with relevant studies previously reported in literature. The behaviour of the piles has been extensively examined and analysed by considering the key features in great detail.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.7 no.4
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• pp.191-205
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• 2009

To characterize the geological features in the study area for high-level radioactive waste disposal research, KAERI (Korea Atomic Energy Research Institute) has been performing several geological investigations such as geophysical surveys and borehole drillings since 1997. Especially, the KURT (KAERI Underground Research Tunnel) constructed to understand the deep geological environments in 2006. Recently, the deep boreholes, which have 500 m depth inside the left research module of the KURT and 1,000 m depth outside the KURT, were drilled to confirm and validate the results from a geological model. The objective of this research was to investigate hydrogeological conditions using a 3-D geological model around the KURT. The geological analysis from the surface and borehole investigations determined four important geologicla elements including subsurface weathered zone, low-angled fractures zone, fracture zones and bedrock for the geological model. In addition, the geometries of these elements were also calculated for the three-dimensional model. The results from 3-D geological model in this study will be beneficial to understand hydrogeological environment in the study area as an important part of high-level radioactive waste disposal technology.

• Journal of the Earthquake Engineering Society of Korea
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• v.6 no.5
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• pp.59-66
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• 2002

Long-rails in railways and high-speed railway are subjected to additional stresses resulted from the displacements inconsistence between upper structures, and this phenomenon is more remarkable in continuous bridges than in simple bridges. For the sake of safety, railways have to guarantee trains to stop safely without derailment even in the event of earthquake. The influences of acceleration, braking, and temperature were analyzed by static nonlinear method. But earthquake loads that require dynamic nonlinear analysis are not considered in these methods. Because linear relation between relative displacements of decks and rail stresses is not guaranteed at the nonlinear systems such as long rails on the bridges, it is required compute to rail stresses considering both braking and earthquake load by nonlinear dynamic analysis method. In this study, dynamic analysis method with material non-linearity for rails on continuous bridges according to the Taiwan High Speed Railway(THSR) Design Specification volume 9 was developed. And additional stresses and displacements of long rails for acceleration, braking, and earthquake loads were analyzed by this method.

• Journal of Bio-Environment Control
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• v.15 no.4
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• pp.406-411
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• 2006

New Guinea impatiens (Impatiens hawkeri) shows very sensitive responses to different light conditions. Due to these phenomena, testers of DUS (distinctness, uniformity and stability) for granting plant variety protection right often have problems distinguishing genetic or physiological differences. New Guinea impatiens 'Fishlimp 149' was grown under several light intensities in a rain-sheltered vinyl house to observe differences of plant growth and flowering. As compared with the control (avg. $1,010{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$), treatments of shade-1 (avg. $599{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$) and shade-2 (avg. $88{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$) showed increased plant height, plant width, leaf size and pedicel length. On the contrary, these growth parameters decreased in shade-3 (avg. $30{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$) with the lowest light intensity. Shade-1 treatment enhanced flower characteristics such as flower diameter, upper petal width, side petal width and lower petal length. However, these characteristics were suppressed by lower light intensities than that in shade-1. Anthocyanin contents of shoot, leaf and pedicel decreased with increasing shading, but that of flower petal was the greatest of the shade-1 treatment. Shade-1 treatment showed the greatest Hunter a value analyzed by a colorimeter, and L and b values increased with increasing shading. Shade-1 treatment seemed to be provided the most proper light condition for DUS test of New Guinea impatiens. Additionally, anthocyanin accumulation on New Guinea impatiens during DUS test was due to not genetic differences but physiological phenomenon.

• Journal of Bio-Environment Control
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• v.19 no.4
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• pp.195-202
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• 2010

Cooling air-conditioning of APC (Agricultural Products processing Center) workplace is important to improve the working environment in the summer season. As existing cooling systems for air-conditioning of whole workplace are inefficient because of their high equipment operating costs, relatively inexpensive cooling system is required. The objectives of this study were to simulate the thermal flow fields in APC workplace having the positive and negative pressure type fan and pad systems and spot cooling system by using CFD software (FLUENT, 6.2) and estimate the cooling effectiveness of respective cooling systems. The results showed that the negative pressure type fan and pad system was inappropriate for the present APC workplace because of excessive outside air influx from open gateway and the positive pressure type fan and pad system created relatively low temperature field but non-uniform velocity field at worker positions. The spot cooling system could supply cool air to worker positions with relatively constant air velocity and temperature.