• Journal of Korea Water Resources Association
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• v.34 no.1
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• pp.91-103
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• 2001

In this studs, hydraulic routing model has been developed to predict the water level and discharge in each river section with considering the full interaction between surface runoff and river flow. It improved the computation of flood runoff by reflecting the shape of hydrograph that was determined by the geological and flood characteristics, and the excessive computation of the peak discharge was eliminated by considering the effect of infiltration. The Inflow from surface runoff to river flow was applied to the equation of continuity by implementing effectively the flow in a number of river section, and resulted in a numerical stability at the rapid variation of rainfall. Measurements were conducted during heavy rain in the watershed area of Yang-Yang Namdae-Chun. The present model was tested to the field, and the computed results were compared to the observed data. Its applicability was confirmed with its verification.

• Journal of Advanced Research in Ocean Engineering
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• v.1 no.1
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• pp.1-13
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• 2015

Post-Katrina investigations revealed that most earthen levee damage occurred on the levee crest and landward-side slope as a result of either wave overtopping, storm surge overflow, or a combination of both. In this paper, combined wave overtopping and storm surge overflow of a levee embankment strengthened with high performance turf reinforcement mat (HPTRM) system was studied in a purely Lagrangian and meshless approach, two-dimensional smoothed particle hydrodynamics (SPH) model. After the SPH model is calibrated with full-scale overtopping test results, the overtopping discharge, flow thickness, flow velocity, average overtopping velocity, shear stress, and soil erosion rate are calculated. New equations are developed for average overtopping discharge. The shear stresses on landward-side slope are calculated and the characteristics of soil loss are given. Equations are also provided to estimate soil loss rate. The range of the application of these equations is discussed.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1997.12a
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• pp.255-262
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• 1997

A low-cost and precise metering device, which is suitable to automatic mixing of nutrient-solution for hydroponic culture, was developed for small-scale growers. The metering device was composed of three parts those were supply pumps, metering cylinders and venturi tube. Those parts were controlled by personal computer with time-based odoff control method. To verify the performance of the developed metering device, the relationship between operating time and discharge was examined and the accuracy of the developed metering device was compared with commercial metering pumps. The results of this study are as follows. 1. The correlation coefficient between the flow rate and operating time was 0.9999, and the linear regression equation computed was y=21.759x, where y is the discharge(g) and x is the operating time(s). 2. The developed device has greater accuracy than commercial metering pumps in terms of the full-scale error. Calculated errors for the developed metering device and two commercial pump were $\pm$0.3 %, $\pm$2.45 % and $\pm$1.38 % respectively. 3. Above results show developed metering device is a useful tool for nutrient-solution control system.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.1286-1293
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• 2010

The ground anchor used in domestic area, which resists by adhesion between anchor body and the ground to the external force, seems not to be adequate for soft ground and urban area where the boundary between structures is close because the ground is disturbed and lost its strength during boring. In order to overcome such a shortcoming an expanded anchor system has been developed. The ground expansion is accomplished by means of Pulse Discharge Technology. In this technology, a high voltage of electricity is stored and discharged in milliseconds which induces high pressure acting on the ground. By making a couple of bulbs, a passive resistance as well as shaft resistance are mobilized, and therefore a higher pullout resistance comparing existing ground anchors is developed.In this study, a couple of full scale tests were conducted in order to figure out how much the resistance of an expanded anchor increases comparing to the straight. As a result, it was found that a remarkable increase in ultimate pullout capacity is observed for the soft ground and as the number of bulb increases. In addtion, as a result of applying to a cut slope reinforcement, it appeared that the length of fixed zone of anchor can be reduced effectively.

• The Transactions of the Korean Institute of Power Electronics
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• v.23 no.3
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• pp.174-181
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• 2018

This study introduces a systematic approach to selecting the internal parameters applied to the equivalent electrical-circuit model (EECM) of a lithium titanium oxide ($Li_4Ti_5O_{12}$; LTO) rechargeable cell. Based on the dynamic characteristic of the cell, a simplified EECM consisting of an open-circuit voltage (OCV), an ohmic resistance, and an RC ladder is fabricated. To select the internal parameters of a simplified EECM, experiments on discharge capacity, OCV, and discharge/charge resistances are performed using hybrid pulse power characterization and direct current internal resistance (DCIR) measurements over the full state-of-charge (SOC) range. The experimental results of the LTO rechargeable cell highlight the importance of correct selection of internal parameters that can reduce EECM errors. This study clearly provides experimental procedures, internal parameters results, and EECM guidelines for adaptive control-based SOC estimation for LTO rechargeable cells.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2005.10a
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• pp.534-539
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• 2005

The purpose of this study is the introduction of pollutant loads's estimation into Saemangeum watershed area with M.E.'s guidebook for TMDL and GIS tool. To estimate reliable pollutants loads, it is necessary to think about characteristic of removal, discharge and runoff as time series. In this study, it was calculated for generation loads which be came from pollutant source, discharge loads which be reduced in the treatment facilities and delivery loads which be considered the self purification parameter and delivery distance. To assess the delivery distance handily, it was particularly estimated using Arc-GIS. It was met with good results that delivery loads of BOD, T-N and T-P was reflected to seasonal precipitation. Lastly to verify the estimated pollutant loads, HSPF developed by USEPA was applied to it. It was showed a relativity of observed to simulated data for flow, Temperature, DO, BOD, $NO_3^--N$ TN and TP. Consequantly, this delivery loads can make full use of model input data for prediction of pollutant loads.

• Proceedings of the KIEE Conference
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• summer
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• pp.1193-1195
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• 2004

Ozone gas is one of the strongest oxidizing and bleaching agents which leave no residues harmful to the global environment. In recent years, the ozone generator has been widely utilized, However, it has been known that a broader application of ozone is hindered primarily because of its low efficiency of generation. Thus, it is more indispensable to improve actual system efficiency of the silent discharge type ozonizer using high frequency inverter. This paper presents a multi level resonant ozone power regulation by association of high frequency transformers and full bridge invert. And proposed resonant inverter system can generate continuous output voltage. can control linearly quantity of ozone gas. This invert that add PWM forms within square forms of output voltage about one level range. The power regulation characteristics and operating performances of silent discharge (SD)type ozone generating tube load driven by this load proposed inverter using FET modules are illustrated from a practical point of view, which can operate under stable conditions of basic level and PWM hybrid control strategy implemented DSP(2406). The effectoveness of propsed invert type ozonizer is proved by experiment results.

• Journal of the Society of Disaster Information
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• v.15 no.2
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• pp.214-222
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• 2019

Purpose: The purpose of this study is to develop a sprinkler head that can be controlled and initial suppressed by installing it in a rack-type warehouse. Method: Considering the spray radius and spray pattern, various deflectors were designed, and the spray angle, discharge characteristics and protection performance test was conducted, and these results were compared and analyzed. Results: An optimal sprinkler head was developed to protect full load, front side of a commodity with minimum water volume 115L/min. Conclusion: The developed head of K-115 and 1Bar pressure was tested with one tier storage confirming that the fire control is carried out without burning all the loadings. In addition, the vertical distance from the top of the load to the deflector shall be separated by 450mm and installed to allow sufficient discharge to the outer part of the commodity.

• Journal of Electrochemical Science and Technology
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• v.15 no.4
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• pp.476-483
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• 2024

Lithium-ion (Li-ion) batteries are essential to modern society, but pose safety risks because of thermal runaway and ignition. This study explores the use of hybrid aqueous electrolytes to enhance the safety and performance of Li-ion batteries, focusing on the solid-electrolyte interface (SEI) formed on lithium titanate (Li₄Ti₅O₁₂; LTO) electrodes. We employed high-resolution transmission electron microscopy (HRTEM) and density functional theory (DFT) calculations to analyze the microstructure and stability of the SEI layer. Further, we prepared LTO and LiMn₂O₄ (LMO) electrodes, assembled full cells with hybrid aqueous electrolytes, and carried out electrochemical testing. The HRTEM analysis revealed the epitaxial growth of a LiF SEI layer on the LTO electrode, which has a coherent lattice structure that enhances electrochemical stability. The DFT calculations confirmed the energetic favorability of the LiF-LTO interface, indicating strong adhesion and potential for epitaxial growth. The full cell demonstrated excellent discharge performance, showing a notable improvement in coulombic efficiency after the initial cycle and sustained capacity over 100 cycles. Notably, the formation of a dense, crystalline LiF SEI layer on the LTO electrode is crucial for preventing continuous side reactions and maintaining mechanical stability during cycling. The experimental results, supported by the DFT results, highlight the importance of the orientational relationship between the SEI and the electrode in improving battery performance. The integration of experimental techniques and computational simulations has led to the development of an LTO/LMO full cell with enhanced discharge capabilities and stability. This study provides insights into the growth mechanisms of the SEI layer and its impact on battery performance, demonstrating the potential of hybrid aqueous electrolytes in advancing lithium-ion battery technology. The findings affirm the viability of this approach for optimizing next-generation Li-ion batteries, which can promote the development of safer and more reliable energy storage solutions.

• Archives of Craniofacial Surgery
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• v.21 no.2
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• pp.127-131
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• 2020

A 60-year-old woman with a history of diabetes mellitus and chronic renal failure was admitted to the hospital with severe pain in the upper lip, which began 4 days prior to admission, accompanied by a bullous lesion and suspected cellulitis in the upper lip. Immediately after admission, as the patient's general condition worsened, tests revealed a non-ST elevated myocardial infarction, septic embolism of the lung, as well as septic shock. Her upper lip suddenly presented a gangrenous and necrotic change, which the tissue and blood culture confirmed to be a Klebsiella pneumoniae infection. After a quick response, the patient's general condition improved. Subsequently, serial debridement was performed to effectively clear away the purulent discharge. While under general anesthesia, the process confirmed full-layer necrosis of the upper lip including the orbicularis oris muscle. Almost half of the entire upper lip sustained a full-layer skin and soft tissue defect, with scar contracture. Six months later, to correct the drooling and lip sealing following the defects, a scar release and an Abbe flap coverage were performed considering both functional and aesthetic aspects. The follow-up revealed a favorable corrective result of the upper lip drooling, and the patient was satisfied from a functional perspective.