• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.4
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• pp.214-214
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• 2004

This paper describes a busbar current differential relay in conjunction with a current transformer(CT) compensating algorithm irrespective of the level of the remanent flux. The compensating algorithm detects the start of first saturation if the third-difference function of the current exceeds the threshold; it estimates the core flux at the first saturation start by inserting the negative value of the third-difference function of the current into the magnetization curve; thereafter, it calculates the core flux during the fault and compensates the distorted current using the magnetization curve. The algorithm estimates the correct secondary current irrespective of the level of the remanent flux and needs no saturation point of the magnetization curve. The proposed relay can improve not only security of the relay on an external fault with CT saturation but sensitivity of the relay on an internal fault; the relay can improve the operating speed on n internal fault with CT saturation. This paper concludes by implementing the relay into a digital signal processor based prototype relay.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.09a
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• pp.29-32
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• 2004

Gaseous partitioning tracer test has been used for determining the volume and spatial distribution of residual non-aqueous phase liquid (NAPL) in the unsaturated soils. In this study, an experimental method for measuring the content of gas-exposed NAPL as well as that of total NAPL in a sand during air sparging was developed. Two different gaseous phase NAPL-partitioning tracers were used; n-pentane, with very low water solubility, was used as the tracer that partitions into NAPL that is only in contact with the mobile gas, and chloroform, with fairly good water solubility, was selected for detecting total NAPL content in the sand. Helium and difluromethanewere used as the non- reactive tracer and water-partitioning tracers, respectively. Using n-decane as a model NAPL (NAPL saturation of 0.018), 25.6% of total NAPL was detected by n-pentane at the water saturation of 0.68. Oniy 9.1% of total NAPL was detected by n-pentane at the water saturation of 0.84. This result implies that the quantity of gas-exposed NAPL increased about three times when the water saturation decreased from 0.84 to 0.68. At the water saturation of 0.68, more than 90% of total NAPL was detected by chloroform while 65.8% of total NAPL was detected by chloroform at the water saturation of 0.84. Considering that the removal rate of NAPL during air sparging for NAPL-contaminated aquifer is expected to be greatly dependent upon the spatial arrangement of NAPL phase with respect to the mobile gas, this new approach may provide useful information for investigating the mass transfer process during air-driven remedial processes fer NAPL-contaminated subsurface environment.

• Journal of the Korean Geotechnical Society
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• v.24 no.3
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• pp.53-63
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• 2008

The aim of this study was to validate the suitability of an digital image analysis (DIA) method to measure the degree of saturation in the unsaturated conditions. This study was carried out on the Joo-Mun-Jin standard sand. A one-dimensional sand column test was used in the constant water level condition to get the correlation equation between the color number ($C_n$) and the measured degree of saturation (5). In addition, the hanging wale. column technique to determine the soil-water charactenstic curve (SWCC) was performed in a Buchner funnel. The average degree of saturation ($S_{ave}$) in the SWCC could be obtained by substituting average color number at each suction head value with the $C_n\;-\;S$ correlation equation. Comparisons were made between the measured results by the hanging water column test and those obtained from DIA method. Results showed that the DIA method tested here provided fairly good saturation distribution values in the drying and wetting processes.

• The Journal of Engineering Geology
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• v.31 no.2
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• pp.165-178
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• 2021

The influence of Soil-Water Characteristic Curve (SWCC) fitting parameters for an unsaturated natural slope was evaluated through seepage and slope stability analysis as a function of rainfall. Soil samples were collected from the study area in Jirisan National Park and the physical and mechanical characteristics of unsaturated soil layers were measured in laboratory tests. The saturation depth was calculated via seepage analysis by changing fitting parameters α, the parameter related to the Air Entry Value (AEV) and n, the parameter related to the slope of the SWCC in the range of natural conditions. Slope stability analysis using the limit equilibrium method considered the calculated depth of saturation. Results from seepage analysis for various rainfall conditions indicate the saturation depth in the soil layer suddenly increased as the fitting parameter α decreased; the saturation time for the entire soil layer also decreased. Slope stability analysis considering the calculated depth of saturation shows that the slope safety factor rapidly decreased as the fitting parameter α decreased, whereas the variation in slope safety factor was very small when n increased. Hence, fitting parameter α has a large effect on saturation depth during rainfall and therefore on slope stability, whereas slope stability is relatively unaffected by the fitting parameter n.

• Journal of Ecology and Environment
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• v.29 no.3
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• pp.305-321
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• 2006

Atmospheric Acid Deposition: Nitrogen Saturation of Forests: Volume weighted annual average wet deposition of nitroge at 33 sites in Korea during 1999-2004 ranged 7.28 to $21.05kgN{\cdot}ha^{-1}{\cdot}yr^{-1}$ with average $12.78kgN{\cdot}ha^{-1}{\cdot}yr^{-1}$, which values are similar level with nitrogen deposition of Europe and North America. The temperate forests that suffered long-term high atmospheric nitrogen deposition are gradually saturated with nitrogen. Such nitrogen saturated forest watersheds usually leach nitrate ion ($NO_3^-$) in stream water and soil solution. It may be likely that Korean forest ecosystems are saturated by much nitrogen deposition. In leaves with nitrogen saturation ratios of N/P, N/K and N/Mg are so enhanced that mineral nutrient system is disturbed, suffered easily frost damage and blight disease, reduced fine-root vitality and mycorrhizal activity. Consequently nitrogen saturated forests decrease primary productivity and finally become forest decline. Futhermore understory species are replaced the nitrophobous species by the nitrophilous one. In soil with nitrogen saturation uptake of methane ($CH_4$) is reduced and emission of nitrogen monoxide (NO) and nitrous oxide ($N_{2}O$) are increased, which gases are greenhouse gas accelerating global warming.

• Journal of the Korean institute of surface engineering
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• v.50 no.2
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• pp.119-124
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• 2017

Due to the high saturation magnetization (~2.4 T), $Fe_{16}N_2$ is interesting for the thin film application such as an actuator, data record storage and sensor etc. In this study, Fe-N thin films were deposited on Si(001) substrate with various power and deposition time by DC magnetron sputtering, in order to get high portion of $Fe_{16}N_2$ phase. Surface morphology, phase formation and magnetic properties were measured. As a result, Saturation magnetization and Remanence magnetization reach to ~2.45 T and 1.41T. But, Coercivity was not enough in this experiments. Its value lower than 100 Oe. Which is very close to theoretical value.

• Journal of Korean Society of Water and Wastewater
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• v.12 no.1
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• pp.62-69
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• 1998

To remove nitrogen from wastewater, ammonia nitrogen has to be oxidized to nitrate nitrogen before denitrification reaction which converts nitrate nitrogen to nitrogen gas. In order to understand nitrification, several mathematical models had been proposed and Monod type model has been accepted internationally. Since Monod type model consists of maximum substrate utilization rate, substrate concentration and half-saturation coefficient, these values have to be addressed before using Monod type model. Several experimental procedures to determine half-saturation coefficient have been developed, however, Infinite dilution method was known to be time saving procedure. In this study, the mathematical equations and experimantal procedures for Infinite dilution method are presented and this method is used to determine half-Saturation coefficient for nitrifying bacteria. As results, Infinite dilution method is proved that this coefficient can be determined within 8 hours and the values of half-saturation coefficient has a range of 0.728 and $0.455gNH_4{^+}-N/m^3$ and the average has $0.580gNH_4{^+}-N/m^3$ through 5 sets of experiments.

• Archives of Craniofacial Surgery
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• v.12 no.1
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• pp.22-27
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• 2011

Purpose: Packing the nose is a common procedure after the closed reduction of a nasal bone fracture to prevent postoperative complications, such as bleeding and adhesion formation as well as to stabilize the framework of the nasal bone. On the other hand, it is difficult for a patient to endure nasal packing because of breathing difficulties, headaches, chest discomfort, insomnia, general weakness and hypoxia. This study examined the availability of a bronchodilator to improve the decreased oxygen saturation and postoperative symptoms on nasal packing. Methods: From February, 2010 to July, 2010, a prospective randomized comparison of the incidence of a range of postoperative signs and symptoms was conducted on 60 patients, who did (n=30) and did not (n=30) undergo bronchodilator infusion (aminophylline 250 mg/10 mL + normal saline 100 mL IV qd) following nasal packing. The postoperative symptoms and oxygen saturation in the two groups were compared. Results: Patients who had infused the bronchodilator showed improved oxygen saturation. Nevertheless, there were no significant differences in the postoperative uncomfortable symptoms (dyspnea, headache, chest discomfort, insomnia, general weakness) between the two groups. Conclusion: A bronchodilator after nasal packing improves oxygen saturation by dilating the airway tract but it cannot reduce the uncomfortable symptoms caused by nasal obstruction. Overall, the bronchodilator is a useful medication for improving the level of oxygen saturation.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.4
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• pp.214-220
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• 2004

This paper describes a busbar current differential relay in conjunction with a current transformer(CT) compensating algorithm irrespective of the level of the remanent flux. The compensating algorithm detects the start of first saturation if the third-difference function of the current exceeds the threshold; it estimates the core flux at the first saturation start by inserting the negative value of the third-difference function of the current into the magnetization curve; thereafter, it calculates the core flux during the fault and compensates the distorted current using the magnetization curve. The algorithm estimates the correct secondary current irrespective of the level of the remanent flux and needs no saturation point of the magnetization curve. The proposed relay can improve not only security of the relay on an external fault with CT saturation but sensitivity of the relay on an internal fault; the relay can improve the operating speed on n internal fault with CT saturation. This paper concludes by implementing the relay into a digital signal processor based prototype relay.

• Journal of Soil and Groundwater Environment
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• v.16 no.5
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• pp.42-52
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• 2011

In this laboratory study, the changes in gas-exposed perchloroethene (PCE) saturation in sand during a PCE removal process were measured using gaseous tracers. The flux of fresh air through a glass column packed with PCEcontaminated, partially water-saturated sand drove the removal of PCE from the column. During the removal of PCE, methane, n-pentane, difluoromethane and chloroform were used as the non-reactive, PCE-partitioning, water-partitioning, and PCE and water-partitioning tracers, respectively. N-pentane was used to detect the PCE fraction exposed to the mobile gas. At water saturation of 0.11, only 65% of the PCE was found to be exposed to the mobile gas prior to the removal of PCE, as calculated from the n-pentane retardation factor. More PCE than that detected by n-pentane was depleted from the column due to volatilization through the aqueous phase. However, the ratio of gas-exposed to total PCE decreased on the removal of PCE, implying gas-exposed PCE was preferentially removed by vaporization. These results suggest that the water-insoluble, PCE-partitioning tracer (n-pentane in this study), along with other tracers, can be used to investigate the changes in fluid (including nonaqueous phase liquid) saturation and the removal mechanism during the remediation process.