• Economic and Environmental Geology
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• v.39 no.5 s.180
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• pp.567-581
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• 2006

The Au-Ag lode deposits in South Korea are closely associated with the Mesozoic granitoids. Namely, the Jurassic deposits formed in mesozonal environments related to deep-seated granitoids, whereas the Cretaceous ones were developed in porphyry-related environments related to subvolcanic granitoids. The time-space relationships of the Au-Ag lode deposits in South Korea are closely related to the changing plate motions during the Mesozoic. Most of the Jurassic auriferous deposits (about $165{\sim}145$ Ma) show fluid characteristics typical of an orogenic-type gold deposits, and were probably generated in a compressional to transpressional regime caused by an orthogonal to oblique convergence of the Izanagi Plate into the East Asian continental margin. On the other hand, strike-slip faults and caldera-related fractures together with subvolcanic activity are associated with major strike-slip faults reactivated by a northward (oblique) to northwestward (orthogonal) convergence, and probably have played an important role in the formation of the Cretaceous Au-Ag lode deposits (about $110{\sim}45$ Ma) under a continental arc setting. The temporal and spatial distinctions between the two typical Mesozoic deposit styles in South Korea probably reflect a different thermal episodes (i.e., late orogenic and post-orogenic) and ore-forming fluids related to different depths of emplacement of magma due to regional changes in tectonic environment.

• Journal of the Korean earth science society
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• v.27 no.4
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• pp.425-432
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• 2006

A seismic tomography using refraction waves is applied to provide information on depth of basement rocks and leachate distribution of the Noeun waste landfill site for the stage of preliminary environmental survey. This method is generally applied to civil and environmental areas. Three lines, apparently perpendicular to the potential leachate flow direction in this site, were installed to investigate the waste landfill site in pseudo three dimensional geometry. The results show that the site is composed of 3 layers and depth of basement becomes shallower at the upstream area of the landfill site than that of the downstream area. Moreover, some parts of the second layer and the basement at the down stream area are partially infiltrated by the leachate, probably related to the disturbed distribution of the different velocity materials within the second layer. In Conclusion, refraction wave tomography is found to be one of the most efficient way to investigate waste landfill site.

• Journal of the Korean Society for Marine Environment & Energy
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• v.1 no.2
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• pp.82-95
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• 1998

In this paper, two series of numerical simulations are performed using LS/DYNA3D: The first series of numerical simulations are collision events between a 310,000 DWT double hull VLCC (struck ship) and two 35,000 and 105,000 DWT tankers (striking ships). Collisions are assumed to occur at the middle of the VLCC with the striking ships moving at right angle to the YLCC centerline. The second ones, grounding accidents of two 40,000 DWT Conventional and Advanced Double Hull lanker bottom structures, CONV/PD328 and ADH/PD328 models. The overall objective of this study is to understand the structural failure and energy absorbing mechanisms during collision and grounding events for double hull tanker side and bottom structures, which lead to the initiation of inner shell rupture and cause the kinetic energy dissipation to bring the ship to a stop. These numerical simulations will contribute to the estimation of damage extents of collision and grounding accidents and the future improvements in lanker safety at the design stage.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.10 no.6
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• pp.1-14
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• 2011

The surrogate safety assessment model which was developed based on the conflict theory by FHWA in the US is software to analyze traffic conflicts using the individual vehicle trajectory data from a microscopic traffic simulation model. This study aims at assessing the safety of different signal control strategies, including pre-time and actuated signal control, using the SSAM. To this end, this study effort has developed a microscopic traffic simulation model using VISSIM through a field study, and then produced the surrogate measures, including TTC, PET, DR, MaxS and DeltaS, and the numbers of conflicts, including rear-end, right angle and lane-changing conflicts. The assessment results indicated that the actuated signal control may produce more conflicts in terms of rear-end conflicts. The use of SSAM in the safety assessments for diverse traffic alternatives in a safe and fast way may contribute to the improvement of safety in the roadway transportation.

• Journal of Radiation Protection and Research
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• v.28 no.2
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• pp.97-108
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• 2003

A three-dimensional wind field model based on the variational technique has been developed for estimating the overall wind patterns over a complex terrain. The three-dimensional elliptic partial differential equations on Cartesian and terrain-following coordinates have been established to obtain the Lagrangian multiplier and the adjusted wind velocity. The simulations were performed to evaluate the variations of the velocity vectors on the hemisphere, half-cylinder, and saddle type obstacles. Also, the wind field model in the terrain-following coordinate has been applied for evaluating the characteristics of wind patterns according to the variations of Gauss precision moduli on the hemispheric topography. The results showed that the horizontal and vertical wind components were strongly governed by the selection of the values of Gauss precision moduli.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.23 no.3
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• pp.248-257
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• 2011

In the present study, we proposed a new numerical wave tank model to analyze the vertical tension-leg circular floating bodies, using a 2-D Navier-Stokes solver. An IBM(Immersed Boundary Method) capable of handling interactions between waves and moving structures with complex geometry on a standard regular Cartesian grid system is coupled to the VOF(Volume of Fluid) method for tracking the free surface. Present numerical results for the motions of the floating body were compared with existing experimental data as well as numerical results based on FAVOR(Fractional Area Volume Obstacle Representation) algorithm. For detailed examinations of the present model, the additional hydraulic experiments for floating motions and free surface transformations were conducted. Further, the versatility of the proposed numerical model was verified via the numerical and physical experiments for the general rectangular floating bodies. Numerical results were compared with experiments and good agreement was archived.

• Korean Journal of Environment and Ecology
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• v.1 no.1
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• pp.46-65
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• 1987

This study was excuted to measure the user's impact area of the Bukhan Mountain National Park. Eighteen sites of the campsite and the picnic area were sample to measure the impact rating of soil and vegetation. And three belt transects were sampled to analyze soil properties and vegetational change by the user's impact. Also user's psychology was investigated through questionnaires with the visitor and 726 answers were collected from May to June in 1987. The regression equation was significant between the distance and the soil hardness. individual number per 100$m^2$, herb coverage and similarity index from the center of picnic area to the non-use site. The tolerant tree against user's impact are Lespedza maximowiczii. Stephanandra insica, Actinidia arguta Symplocos chinensis for. pilosa and the sensitive trees were Fraxinus rhy chophylla Sorbus alnifolia. and Rhodadendron mucronulatun. The facilities factor and social factor are the most affecting factors to User's psychology by the varimax rotated factor analysis. The carrying capacity of the picnic area was 25$m^2$ per man by the degree of psychological satisfaction.

• Journal of Korea Water Resources Association
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• v.46 no.2
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• pp.205-218
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• 2013

The likelihood of rip current at Haeundae beach according to wave parameters, such as wave height, period, direction, and tidal elevation, was estimated by using numerical simulations with a Boussinesq model, FUNWAVE. To examine the estimation, the rip current occurred on 12th June, 2011 at Haeundae beach was simulated based on observations. For the estimation, the following procedure was carried out. First, extensive numerical simulations of nearshore circulations are performed under various random sea conditions according to the wave parameters. Second, from the numerical results, cross shore components of two-wave-period averaged velocities over the nearshore area were computed, and their seawardly maximum was defined as rip current velocity of the area. Third, using time series of the rip current velocity, we computed the ratio of the simulation time and the time period in which the rip current velocity exceed a threshold velocity for rip-current accidents, and thus the ratio was quantified as the likelihood of rip current at Haeundae beach for the input wave parameters. From the resultant estimations, it was found that the rip current likelihood increases as wave height and period increase, and tidal elevation decreases.

• Journal of Korean Society of Forest Science
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• v.77 no.4
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• pp.401-413
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• 1988

To investigate the users' activity, impact and psychology in Naejang Temple district at Mt. Naejang National Park in Korea, users' density and questionnaire survey at three major picnic areas and passenger counting at major pass were executed and environmental impacton on the site was surveyed. The total number of visitors showed stability at the level of one million persons every year after 1984. Users' impact was much severe along the main trail, the upper cablecar station and the slope from the observatory to Keumsun Valley, The maximum momentary number of users was estimated as 53,000 persons in autumn. Approximately 20% of the total number of visitor used Keumsun Valley and Weonjeok Valley area and 80% of visitors left after using only grassland and cablecar. The visitors' characteristics was similiar to the type of long-distanced national park and the main visiting purpose was to see autumn leaves. The psychological satisfaction did not very significantly as to increasing user's speace. As a result of varimax rotated factor analysis, the 1st factor, most affecting users' psychological satisfaction, was related to landscape and consisted of nature disturbance, crowdedness, noisiness, cleanness, in order of importance. The 2nd factor was related to facilities and consisted of number of toilet, number of waste-baskets, amount of drinking water, safety, in order of importance.

• Journal of the Korean Geotechnical Society
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• v.16 no.1
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• pp.117-129
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• 2000

This paper discusses the lateral behavior of group pile in homogeneous and non- homogeneous (two layered) soil. In the group pile, the model tests were to investigate the effects on spacing-to-diameter ratio of pile, pile array, ratio of pile spacing, constraint condition of pile tip, eccentric load and ground condition. The group efficiency and lateral deflection induced in active piles were found to be highly dependent on the spacing-to-diameter ratio of pile, number of pile. Lateral bearing capacities in the group piles of fixed tip, in the case of 6D spacing and $3\times3$ array, were 40-100% higher than those in the group pile of free tip. Based on the results obtained, a spacing-to-diameter of 6.0 seems to be large enough to eliminate the group effect for the case of relative density of 61.8% and 32.8%, and then each pile in such a case behaves essentially the same as a single pile. However, in the case of dense sand, it can be estimated that a spacing-to-diameter of 8.0 seems to be large enough to eliminate the group effect. In this study the group efficiency is illustrated in experimental function with spacing-to-diameter, S/D, relative density and number of pile. The distribution of shear force in lead row piles, in the case of 3$\times$3 array group pile, was 41.6-52.4% for 3D spacing and 34-40% for 6D spacing, respectively. The shadowing effect for the parallel direction of lateral loading appears to be more significant than the one for the perpendicular direction of lateral loading.