• KCID journal
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• v.21 no.1
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• pp.64-77
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• 2014

This study evaluated the soil loss considering the R-Factor value following the climate change. To calculate the soil loss of the basin in Jaun-ri, Hongcheon-gun which is the study area, the future climate change scenario and convenience revision were used to build the past 30 years, future 30 years R-Factor and it was applied to USLE model. As a result, as the R-Factor value declined a little in the future, the soil loss was also reduced but it corresponds to the 'very high' according to the OECD soil loss grade so the solution to reduce the soil loss is necessary and it can be used for another study material.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.1137-1142
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• 2008

In this paper, an effect on power conversion unit in high-speed railway vehicle by loss of contact between a catenary system and pantograph suppling electrical power to high-speed railway vehicle are investigated. One of the most important needs accompanied by increasing the speed of high-speed railway vehicle is reduced that arc phenomenon by loss of contact brings out EMI. in case of high-speed railway vehicle using electrical power, as comparison with diesel rolling stock, PLD(Power Line Disturbance) such as harmonic, transient voltage and current, EMI, dummy signal injection etc usually occur. To analysis the effect on loss of contact, it is necessary electrical modeling system between the contact line and the pantograph according to the loss of contact. Therefore analytical model of a contact line and a pantograph is constructed to simulate the behaviour of loss of contact. The reliability of the modeling system is verified by simulation implementation on kinds of loss of contact.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.9
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• pp.1325-1334
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• 1998

The objectives of the present study are to develop a systematic method rather than a conventional trial-and-error method for an optimal shape design using a mathematical theory, and to apply it to engineering problems. In the present study, an optimal condition for a minimum pressure loss in a two-dimensional curved duct flow is derived and then an optimal shape of the curved duct is designed from the optimal condition. In the design procedure, one needs to solve the adjoint Navier-Stokes equations which are derived from the Navier-Stokes equations and the cost function. Therefore, a computer code of solving both the Navier-Stokes and adjoint Navier-Stokes equations together with an automatic grid generation is developed. In a curved duct flow, flow separation occurs due to an adverse pressure gradient, resulting in an additional pressure loss. Optimal shapes of a curved duct are obtained at three different Reynolds numbers of 100, 300 and 800, respectively. In the optimally shaped curved ducts, the separation region does not exist or is significantly reduced, and thus the pressure loss along the curved duct is significantly reduced.

• Proceedings of the Korea Concrete Institute Conference
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• 1993.10a
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• pp.11-17
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• 1993

In this study, the fundamental properties of High-Strength Concrete(HSC), such as the slump loss, the temperature increment, the strength development, are considered by experiment. In reducing the temperature and the slump loss, and developing the strength of HSC, the application of silica fume as an admixtures is very effective. And when gypsum is added, the slump loss is reduced and the strength of HSC is improved remarkably, but the temperature of concrete is increased, thus a more study to reduce the temperature increment is required

• Proceedings of the Korea Concrete Institute Conference
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• 1997.04a
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• pp.124-128
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• 1997

In order tohave a betterunderstanding of thefavorable effect ofground granulated blast-furnace slag and fly ash, slump loss, temperature risingand compressive strength of concrete were investigated into diffrent conditions. When slag was mixed with ordinary portland cement as30%, slump loss gotto some 18% at 60min, maximum temperatureto some $43^{\cire}C$ at 180min, compressive strength similar to that of ordinary portland concrete at 28 days. Therefore it wasnoted thatslump loss andmaximum teaperaturerising of concrete were very reduced according to ground granulated blast-furnace slag and fly ash mixed with ordinary portland cement.

• CELLMED
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• v.13 no.5
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• pp.19.1-19.3
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• 2023

Objective: A case report on the improvement of bald crown by Ortho-Cellular Nutrition Therapy (OCNT). Methods: A 61-year-old Korean male suffering from bald crown, male pattern baldness, and reduced hair thickness Results: Bald crown improved after Ortho-Cellular Nutrition Therapy (OCNT). Conclusion: Ortho-Cellular Nutrition Therapy (OCNT) is effective in relieving the symptoms of hair loss patients.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.35 no.4
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• pp.269-280
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• 2017

Recently, in the United States, there has been short-term intensive rainfall due to El Ni?o and Rania. The Rim Fire was a wildland fire that was started in a remote canyon in Stanislaus National Forest in California. This portion of the central Sierra Nevada spans Tuolumne and Mariposa counties. This study is about estimating unsteady soil loss due to rainfall impact according to Rim Fire at California. It implies that caution needs to be taken in selecting the grid size for estimating soil loss using numerical modeling approach. Soil loss increased in all duration times before Rim fire. But it increased until 7 days and reduced or kept stable after that. Based on the 2014 average rainfall 1388 mm/yr, soil loss was estimated to be 247,518 ton/ha/yr before Rim Fire, and 9,389,937 ton/ha/yr after that.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.2
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• pp.268-275
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• 2015

This paper proposes a method of switching to improve power loss for the single-phase three-level NPC inverter. The conventional switching methods, which are called as the bipolar and unipolar switching methods, are used for single phase inverters using three-level topology. However, these switching method have disadvantage in the power loss. Because all of the switch are operated. To reduce the power loss of the three-level NPC inverter, clamp switching method is introduced in this paper. This way, one of the lag is fixed that switching loss is reduced. This paper analyzes and compares power losses of unipolar method and clamp method. The validity of the power loss analysis is verified through the simulation and experimental results.

• Journal of Electrical Engineering and Technology
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• v.8 no.3
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• pp.428-435
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• 2013

Flexible AC Transmission System (FACTS) application study on enhancing the flexibility of AC power system has continued to make progress. A thyristor-controlled series capacitor (TCSC) is a useful FACTS device that can control the power flow by adjusting line impedances and minimize the loss of power flow and voltage drop in a transmission system by adjusting line impedances. Reduced power flow loss leads to increased loadability, low system loss, and improved stability of the power system. This study proposes the optimal location and compensation rate method for TCSCs, by considering both the power system loss and voltage drop of transmission systems. The proposed method applies a multi-objective function consisting of a minimizing function for power flow loss and voltage drop. The effectiveness of the proposed method is demonstrated using IEEE 14- and a 30-bus system.

• Journal of Mechanical Science and Technology
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• v.18 no.3
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• pp.481-490
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• 2004

Steady state flow calculations are executed for turbo-pump inducers of modern design to validate the performance of Tascflow code. Hydrodynamic performance of inducers is evaluated and structure of the passage flow and leading edge recirculation are also investigated. Calculated results show good coincidence with experimental data of static pressure performance and velocity profiles over the leading edge. Upstream recirculation, tip leakage and vortex flow at the blade tip and near leading edge are main sources of pressure loss. Amount of pressure loss from the upstream to the leading edge corresponds to that of whole pressure loss through the blade passage. The viscous loss is considerably large due to the strong secondary flow. There appears more stronger leading edge recirculation for the backswept inducer, and this increases the pressure loss. However, blade loading near the leading edge is considerably reduced and cavitation inception delayed.