• Journal of the Korean Society of Environmental Restoration Technology
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• v.15 no.2
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• pp.137-147
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• 2012

GRS is an effective urban ecology restoration technique that can manage a variety of environmental functions such as ecological restoration, rainwater spill control and island heat effect from a low-impact development standpoint that can be utilized in new construction and retrofits. Recently, quantitative evaluation studies, both domestic and abroad, in the areas related to these functions, including near-earth surface climate phenomenon, heavy rainwater regulation, thermal environment of buildings, have been actively underway, and there is a trend to standardize in the form of technological standards. In particular, centered on the advanced European countries, studies of standardizing the specific insulation capability of buildings with green system that comprehensively includes the green roof, from the perspective of replacing the exterior materials of existing buildings, are in progress. The limitation of related studies in the difficulties associated with deriving results that reflect material characteristics of continuously evolving systems due in part to not having sufficiently considered the main components of green system, mechanisms of vegetation, soils. This study attempts to derive, through EnergyPlus, the effects that the vegetation-related indicators such as vegetation height, FCV, etc. have on building energy load, by interpreting vegetation and soil mechanisms through plant canopy model and using an ecological standard indicator LAI that represent the condition of plant growth. Through this, the interpretations that assume green roof system as simple heat insulation will be complemented and a more practical building energy performance evaluation method that reflects numerical methods for heat fluxes phenomena that occur between ecology restoration systems comprised of plants and soil and the ambient space.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.7
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• pp.937-944
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• 1999

The near-wall flow structures of turbulent boundary layer over riblets having semi-circular grooves were investigated experimentally for the drag decreasing ($s^+=25.2$) and drag increasing ($s^+=40.6$) cases. The field of view used for tho velocity field measurement was $6.75{\times}6.75mm^2$ in physical dimension, containing two grooves. One thousand instantaneous velocity fields over the riblets were extracted for each case of drag increase and decrease. For comparison, five hundreds instantaneous velocity fields over a smooth flat plate were also obtained under the same flow conditions. To see the global flow structure qualitatively, the flow visualization was also performed using the synchronized smoke-wire technique. For the drag decreasing case ($s^+=25.2$), most of the streamwise vortices stay above the riblets, interacting with the riblet tips. The high-speed in-rush flow toward the riblet surface rarely influences the flow inside tho riblet valleys submerged in the viscous sublayer. The riblet tips seem to impede the spanwise movement of the longitudinal vortices and induce secondary vortices. The turbulent kinetic energy in the riblet valley is sufficiently small to compensate the increased wetted area of the riblets. In addition, in the logarithmic region, the turbulent kinetic energy are small or almost equal to that of a smooth flat plato. For the drag increasing case ($s^+=40.6$), however, the streamwise vortices move into the riblet valley freely, interacting directly with the riblet inner surface. The penetration of the high-speed in-rush flow on the riblets increases tho skin-friction. The turbulent kinetic energy is increased in the riblet valleys and even in the outer region compared to that over a flat plate.

• Journal of Korea Water Resources Association
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• v.47 no.11
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• pp.1087-1094
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• 2014

Saltwater pumping method can be used to mitigate saltwater intrusion in coastal aquifers. However, the saltwater pumping well may discharge large freshwater along with saltwater, thereby wasting precious resources. A double negative barrier was proposed: an inland well to capture freshwater and a saltwater well near the coastline to pump saltwater. A previous study anaylzed effects of double negative barriers in dispersion-dominated coastal aquifers and determined the critical pumping rate at the saltwater well which minimized the saltwater ratio at the freshwater well. However, the study resulted in 1~15% of saltwater ratios, which were too high, for example, for drinking water standards. This study analyzed cases that were considered in the previous study, but for advection-dominated cases, and found that freshwater with sufficiently low saltwater ratios could be developed at the freshwater well. In addition, for optimal groundwater management of a watershed not only the minimum saltwater ratio at the freshwater well but also the least freshwater wasted at the saltwater well must be pursued.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.8
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• pp.1468-1484
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• 1992

In the present paper forward projection is proposed as a new approach to determine the preform shape in rib-web type forging. In the forward projection technique an optimal billet is determined by applying some mathematical relationship between geometrical trials in the initial billet shape and the final products. In forward projection a volume difference between the desired product shape and the final computed shape obtained by the rigid-plastic finite element method is used as a measure of incomplete filling of working material in the die. At first linear inter-/extrapolation is employed to find a proper trial shape for the initial billet and the method is successfully applied to some cases of different aspect ratios of the initial billet. However, when the initial guesses are not sufficiently near the optimal value linear inter-/extrapolation does not render complete die filling. For more general application, a fuzzy system is used in the forward projection technique in order to determine the initial billet shape for rib-web type forging. It has been thus shown that the fuzzy system is more reliable for the preform design in the rib-web type forging process.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 1991.06a
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• pp.45-48
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• 1991

This work aims to introduce the concept of microcomputer aided port design simulation methodology including the analysis of the mathematical models to be implemented and apply it to the Third Stage Busan Part Development Project. In the Busan case study the size of the proposed turning basin of the new terminal together with the operational stra-tegies of berthing and unberthing was examined In addition the safety of ships' entry and exit through the projection new breakwaters was as-certained. From the application of simulation to the Busan project it was found that the proposed dredging area was not sufficiently wide enough for a modelled container ship to perform A type unberthing (in which the ship turns to port as she monoeuvres away from No.1 berth with the ass-istance of tuges) especially in a strong easterly wind., It is therefore recommended that Busan pilots should be advised to use B type unberthing strategy in which the ship goes astern from No.1 berth to the turning area in front of No.2 berth(where the ship turns 180 degrees clockwise) especially when the wind is very strong. It is also recommended that a sea buoy be placed outside the new breakwaters as this was found to im-prove the safety of ship manoeuvres through the breakwaters significant-ly. Another recommendation is that the Korean Hydrodynamic Office carry out a detailed survey of the currents in the water area near the new breakwaters. once they have been constructed. In addition it is to be recommended that a current meter be placed at the recommended sea buoy pardised by erroneous current information

• International Journal of Highway Engineering
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• v.11 no.1
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• pp.37-45
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• 2009

The minimum distance between tunnel and interchange has several steps to go through for road users; when road user comes out of tunnel, he/she reads information on road sign and tries to change the lane, and then reaches the destination (interchange). So that's why that minimum distance between tunnel and interchange has to be designed to reflect human factors sufficiently for road's users. This study aims to set for minimum distance between tunnel and interchange with involved human factors. People aged from their twenties to their seventies took part in this experiment by using driving simulator. As a result, the minimum distance between them was loom long. When it comes to this study for minimum distance between tunnel and interchange, this study will be significant in some ways reason why this method can be applied to all road facilities for road safety on scientific basis. In the near future, It will make a recommendation concerning the most suitable data for road safety by contributing better guideline.

• Tunnel and Underground Space
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• v.16 no.3 s.62
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• pp.218-231
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• 2006

Anisotropic/heterogeneous rock mass shows various deformation behavior types due to tunnelling because deformation behavior is largely controlled by the spacial characteristics of geological factors such as faults, joints and fractured zone in rock mass. In this paper 2-dimensional numerical analysis on the several influencing factors is performed considering fractured zone located near tunnel. This numerical analysis shows that deformation behavior of tunnel are very different according to the width and the location of fractured zone and supper method. However, 3-dimensional analysis is necessary to consider 3-dimensional geometrical characteristics sufficiently since discontinuity and fractured zone have 3-dimensional geometry. Also flexible design/construction guidelines for tunnelling are required to cope with uncertain ground condition and circumstance for technically safe and economic tunnel construction.

• Journal of Korean Society on Water Environment
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• v.38 no.6
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• pp.282-291
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• 2022

Since the efficiency of wastewater treatment using microalgae differs depending on the metabolic characteristics of the species, it is important to understand the characteristics of target algae prior to the application in wastewater treatment. In this study, for the application of Arthrospira platensis to wastewater treatment, which is a filamentous alkaliphilic cyanobacteria, basic species specificity was identified and the possibility of application to wastewater treatment was investigated. As a result of the species specificity investigation, the specific growth rate between pH 7.0 and 11.0 showed the highest value near pH 9 at 0.25/day. The reason for the relatively low growth(0.08/day) at pH 11 was thought to be the CA(carbonic anhydrase) enzyme that is involved in carbon fixation during photosynthesis has the highest activity at pH 8.0 to 9.0, and at pH 11, CA activity was relatively low. In addition, A. platensis showed optimal growth at 400 PPFD(photosynthetic photon flux density) and 30℃, and this means that cyanobacteria such as A. platensis have a larger number of PS-I(photosystem I) than that of PS-II(photosystem II). It was speculated that it was because higher light intensity and temperature were required to sufficiently generate electrons to transfer to PS-I. Regarding the applicability of A. platensis, it was suggested that if a system using the synergistic effect of co-culture of A. platensis and bacteria was developed, a more efficient system would be possible. And different from single cocci, filamentous A. platensis expected to have a positive impact on harvesting, which is very important in the latter part of the wastewater treatment process.

• The Korean Journal of Petroleum Geology
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• v.11 no.1 s.12
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• pp.27-41
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• 2005

The hydrocarbon source rock potential of the Eocene units in the southern Oregon Coast Range was evaluated by using the Rock-Eval pyrolysis. Most Eocene units in southern Oregon Coast Range are thermally immature and contain lean, gas-prone Type III kerogen. However, some beds(coals) are sufficiently organic-rich to be sources of biogenic and thermogenic methane discovered in numerous seeps. The overall hydrocarbon source rock potential of the southern Oregon Coast Range is moderately low. Several requirements for commercial accumulations of hydrocarbon, however, probably exist locally within and adjacent areas. Three speculative petroleum systems are identified. The first includes the southern part of the Oregon Coast Range near the border with the Mesozoic Klamath Mountains and is related to a proposed subduction zone maturation mechanism along thrust faults. The second is centered in the northern part of the range and may be associated with basin-centered gas in an over-pressured zone. The third occurs near the eastern border of the range where maturation is related heating by sills and migration of hydrothermal fluids associated with mid-Tertiary volcanism in the Western cascade arc.

• Tunnel and Underground Space
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• v.22 no.5
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• pp.346-353
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• 2012

Multi-specimen uniaxial compression test has been carried out in order to find the method to determine the five independent elastic constants from a single standard specimen of a transversely isotropic rock. Total 35 specimens of 7 different angles from a large block of rhyolite presenting the flow structure obviously are used in tests. This second report is to focus on the statistical evaluation of measured strains and analyzed elastic constants. And the determination of their true or near-true values is discussed. As the result of RSD analysis, it turns out that the reliability of measured strains is sufficiently obtained and Saint-Venant approximation is well applicable except 15 degree angled specimen in tests. RSD is decreasing on the increase of the angle of anisotropy. This tendency may be caused not only by the decreasing of the deviation of measured strains, but also by the better applicability of Saint-Venant approximation on the increase of angle. It can be concluded that the analyzed values are considered the near-true ones of five independent constants on the high reliability. But the variation of the apparent Young's modulus expected by these values is not proved to match the measured tendency. It is inferred that the factor to decrease the apparent Young's modulus and/or to increase the shear strain, is present in the test or in the nature of the anisotropy in consideration of this inconsistency.