• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.11
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• pp.409-415
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• 2017

This study examines the effect of pay dispersion on labor productivity by focusing on the inflow of newcomers into the tournament and the outflow of stayers from the tournament. According to tournament theory, the expansion of pay dispersion within the organization contributes to enhanced organizational performance by attracting high performers externally and by removing low performers internally within the organization. However, previous studies regarding tournament theory have overlooked the participant aspects. Therefore, this study explores how external hiring and involuntary turnover influence the effect of pay dispersion on labor productivity. This paper hypothesizes that pay dispersion will have a positive effect on labor productivity. Moreover, this paper predicts that the inflow of new competitors will strengthen the positive effects of pay dispersion on labor productivity, whereas the outflow of incumbents will weaken this relationship. Empirical results showed that pay dispersion increased labor productivity and the inflow of newcomers strengthened this positive relationship. However, contrary to our prediction, the outflow of incumbents weakened the positive effect between pay dispersion and labor productivity. These theoretical arguments and empirical findings highlight the proper conditions should be equipped to practically achieve the positive effect of pay dispersion on labor productivity.

• Journal of Korea Water Resources Association
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• v.52 no.4
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• pp.235-243
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• 2019

Recently, urban inundation was frequently occurred due to the intensive rainfall exceeding marginal capacity of the flood control facility. Furthermore, needs for the underground storage facilities to mitigate urban flood are increasing according to rapidly accelerating urbanization. Thus, in this study, drainage efficiency in drain tunnel connecting to underground storage was investigated from the air-core measurements in the drop shaft against two types of inlet structure. In case of the spiral inlet, the multi-stage structure is introduced at the bottom of the inlet to improve the vortex induction effect at low inflow discharge (multi-stage spiral inlet). The average cross-sectional area of the air-core in the multi-stage spiral inlet is 10% larger than the tangential inlet, and show the highly air emission effect and the highly inflow efficiency at the high inflow discharge. In case of the tangential inlets, the air emission effect decreased after exceeding the maximum inflow discharge, which is required to maintain the inherent performance of the tangential inlet. From the measurements, the empirical formula for the cross-sectional area of the air-core according to locations inside the drop shaft was proposed in order to provide the experimental data available for the inlet model used in experiments.

• Journal of Korean Tunnelling and Underground Space Association
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• v.10 no.1
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• pp.49-57
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• 2008

One of the most important design concerns for undersea tunnels is to establish design water load and flow rate. These are greatly dependent on the hydraulic factors such as water head, cover depth, hydraulic boundary conditions. In this paper, the influence of the hydraulic design factors on the ground loading and the inflow rate was investigated using the coupled finite element method. A horse shoe-shaped tunnel constructed 30 m below sea bottom was adopted to evaluate the water head effect considering various water depth for varying hydraulic conditions and relative permeability between lining and ground. The effect of cover depth was analysed for varying cover depth with the water depth of 60 m. The results were considered in terms of pore water pressure, ground loading and flow rate. Ground loading increases with an increase in water head and cover depth without depending on hydraulic boundary conditions. This points out that in leaking tunnels an increase in water depth increases seepage force which consequently increases ground loading. Furthermore, it is identified that an increase in water head and cover depth increases the rate of inflow and a decrease in the permeability ratio reduces the rate of inflow considerably.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.5
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• pp.1039-1049
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• 2015

The inflow estimation at large multipurpose dam reservoir is carried out by considering the water balance among the discharge, the storage change during unit time interval obtained from the observed water level near dam structure and area-volume curve. This method can be ideal for level pool reservoir but include potential errors when the inflow is influenced by the water level slope due to backwater effects from upstream flood inflows and strong wind induced by typhoon. In addition, the other uncertainties arisen from the storage reduction due to sedimentation after the dam construction and water level noise due to mechanical vibration transmitted from the electric power generator. These uncertainties impedes the accurate hydraulic inflow measurement requiring exquisite hydrometric data arrangement for reservoir waterbody. In this study, the distributed hydrologic model using UBC-3P boundary setting was applied and its feasibility was evaluated. Finally, the modeling performance has been verified since the calculated determination coefficient has been in between 0.96 to 0.99 after comparing with observed peak inflow and total inflow at Namgang dam reservoir.

• The Journal of Engineering Geology
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• v.23 no.3
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• pp.227-234
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• 2013

The vertical shaft of a selective intake structure, which is constructed in a large reservoir, is required to be impermeable and to employ a grouting technology to prevent water inflow from the reservoir or surrounding ground. In this study, groundwater inflow is estimated using a numerical model for two cases (i.e., grouting or non-grouting cases at the exterior of a vertical shaft) and compared with data measured during an excavation at the construction site of a selective intake structure in the Soyang reservoir, Korea. Groundwater inflow is estimated to range from 444 to 754 $m^3/d$ in the case of non-grouting and from 58 to 95 $m^3/d$ in the case of grouting. The groundwater inflow measured in a vertical shaft, which ranges from 30 to 100 $m^3/d$, is similar to the simulated amount. It is recommended that before the excavation of a shaft, water inflow is estimated using a numerical model and a grouting test to ensure excavation stability and improve excavation efficiency.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1571-1580
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• 2008

Subsea tunnels that link land to island and among nations for transportation, efficient development of limited surface and pursuit of economic development should be designed to support pore water pressure on the lining. It is generally constructed in the bed rock of the sea bottom. When the tunnel excavation face meets fractured-zones below sea bottom, collapse may occur due to an increase of pore water pressure and large inflow. Such an example can be found in the Norwegian subsea tunnel experiences in 1980's. In this study hydraulic behavior of tunnel heading is investigated using numerical method based on the collapse of Norwegian subsea tunnel. The effect of pore water pressure and inflow rate were mainly concerned. Horse-shoe shaped model tunnel which has 50 m depth from the sea bottom is considered. To evaluate hydraulic performance, parametric study was carried out for varying relative permeability. It is revealed that pore water pressure has increased with an increase of sea depth. Especially, at the fractured-zone, pore water pressure on the lining has increased significantly. Inflow rate into tunnel has also increased correspondingly with an increase in sea depth. S-shaped characteristic relation between relative permeability and normalized pore water pressure was obtained.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.2
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• pp.121-130
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• 2009

An unsteady numerical simulation method for an autorotating rotor in forward flight was developed. The flapping and rotational equations of motion of autorotation are continuously integrated for given time steps, meanwhile the induced velocity field at disc plane is obtained by the dynamic inflow theory embodying the unteadiness. The transitions from arbitrary initial states to equilibrium states were simulated. Steady autorotations as numerical solutions of equations were predicted by using two sources of blade airfoil data. The simulations using airfoil data which were obtained by a two dimensional Navier-Stokes solver in terms of angles of attack and Reynolds numbers have shown good agreements with wind tunnel experimental results.

• Journal of the Korean Society of Visualization
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• v.21 no.2
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• pp.24-33
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• 2023

This work is to observe the wake flow generated behind a ramp. We have conducted a large eddy simulation with two ramp models having different heights with two different inflow conditions. Reynolds number based on the height of the large ramp (LR) and small ramp (SR) are Re_h = 2.8×10⁴ and 1.4×10⁴ respectively. The wake flow visualization shows the formation of streamwise counter-rotating vortices pairs at the downstream of the obstacle. These primary vortices are stretched and lifted up when moving downstream. In order to observe the effect of the inflow condition on the wake transition, two different inlet flow conditions are given on the inlet section as an inlet boundary condition. Induced counter-rotating vortices pairs due to sharp-edged triangular ramp obstacles are developed and propagated downstream. In the result, the large ramp shows a more complicated wake structure of the boundary layer than the small ramp.

• Journal of Ocean Engineering and Technology
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• v.22 no.5
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• pp.61-68
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• 2008

In Jinhae-Masan bay, a typical semi-dosed bay in Korea, the water quality is severely deteriorated because of the dosed topographic character and the inflow of nutrients from the land. There have been attempts to apply a water quality model dealing with the entrophication phenomenon and the oxygen-deficient mass in the bay in summer, but there have been few examples of models that have considered the phenomenon of stratification in the proper order, and then it is performed the model of water quality. Therefore, this study collected and analyzed the pre-observed water temperature data from Jinhae-Masan bay in summer and then constructed a density model using the topographic heat accumulation effect and inflow from the river to examine the temperature stratification. The simulation results show that this model could demonstrate the temperature stratification in the Jinhae-Masan bay very well.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.6
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• pp.757-764
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• 2011

In this study, we analysed the influence of the performance and inflow flow of a radial inflow turbine with the variation of vane nozzle exit angles for a 100kW class turbine applicable in the waste heat recovery system. For this, three-dimensional CFD analysis was performed using commercial code called ANSYS Fluent 12.1. As the vane nozzle exit angle was more increased the reattachment region near blades of the vane nozzle got smaller, and also the Mach number at vane nozzle exit was observed to be 1 due to the effect of the cross section reduction. Through this study, we expect that the analysed results will be used as the design material for the composition of the turbine optimal design parameters corresponding to the target output power.