• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.1193-1195
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• 1992

A control method of constant flux which is one of the vector control of Induction Motor is discussed. We estimate and calculate the secondary flux from the state equations without a sensor for velocity or linkage flux. A design of the flux obserber that minimizes the effect of variation of the secondary resistance is discussed. The compter simulation is compared with the experimental result.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.2
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• pp.49-56
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• 2008

In order to reduce energy consumption, secondary controlled system has been applied to many types of equipments. In lifting equipments or press machines using hydraulic cylinder, a hydraulic transformer is used as a control component instead of a valve for motion control and a component for recovering potential energy of load. The transformer is a combination of a variable displacement pump/motor as a secondary controlled element and a fixed displacement pump/motor. In this paper the effect of transformer is studied. Multiple closed loop controllers with displacement feedback of variable pump/motor, speed feedback and position feedback of cylinder are used. The efficiency and energy consumption when cylinder is driven up and down is calculated by simulation. Simulation results show that considerable energy saving is achieved by choosing load ratio, circuit type and supply pressure.

• The Korean Journal of Food And Nutrition
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• v.9 no.2
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• pp.176-180
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• 1996

In order to develop new bioactive functions ginseng extract, it was studies whether the ginseng extracts on the induction of immunological tolerance In mice. Oral immunologic tolerance was induced by the secondary exposure of egg albumin + alum following gastrointestinal exposure nth egg albumin In mice, and the effect on anti EA antibody in blood, 7 cell subset in spleen were Investigated. The results obtained were as follows. EA group and EA + GE group was capable of conferring tolerance, contained a profound for 5 weeks experimental but saline group restricted to induce tolerance. GE group did not show the activity of tolerance by the first immunogens exposure, but induced the tolerance by the secondary exposure. And also spleen T cells, CD 8+ and CD 4+ were decreased. These results suggested that ginseng may affect the induction of immunological tolerance, which may be associated proliferative response of CD 4+ and CD 8+ in splenocyte.

• Journal of environmental and Sanitary engineering
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• v.24 no.3
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• pp.37-54
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• 2009

The study has analyzed impacts and intensity of weather that affect $PM_{10}$ concentration based on PM10 forecast conducted by the city of Seoul in order to identify ways to improve the accuracy of PM10 forecast. Variables that influence $PM_{10}$ concentration include not only velocity and direction of the wind and rainfalls, but also those including secondary particulate matter, which were identified to greatly influence the concentration in complicated manner as well. In addition, same variables were found to have different impacts depending on seasons and conditions of other variables. The study found out that improving accuracy of $PM_{10}$ concentration forecast face some limits as it is greatly influenced by the weather. As an estimation, this study assumed that basic research units and artificially estimated pollutant emissions, study on mechanisms of secondary particulate matter productions, observatory compliment, and enhanced forecaster's expertise are needed for better forecast.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.3
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• pp.471-478
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• 2012

Where an activated sludge system needs to be converted to biological nutrient removal(BNR) system, the secondary clarifier must handle higher MLSS from bioreactor since nitrification in BNR system that requires higher SRTs than activated sludge system. Either increase the clarifier size or modification of clarifier physical structure is required to cope with MLSS surge. One of recommended structural modification is the insertion of Lamellar within clarifier. In this study, two clarifiers - one has Lamellar structure inserted and the other does not - were used to compare the effect of Lamellar in solid/liquid separation. Same MLSS was fed to both clarifiers and concentrations of MLSS were varied. With all MLSS concentrations, attachment of MLSS on Lamellar was observed and it was found that detached MLSS caused the higher effluent SS concentrations than that of non-Lamellar clarifier effluent. From these results, Lamellar should not be inserted in clarifier to handle MLSS from BNR processes and the recommendation must be withdrawn.

• English Language & Literature Teaching
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• v.15 no.3
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• pp.353-380
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• 2009

The purpose of this study is to analyze the preconceptions Korean EFL learners have about team teaching in the field of English education at a secondary level. Team teaching is a method of teaching where a Korean English teacher works in co-junction with a native English speaker. Generally speaking, when we discuss teaching methods for a foreign language, the most important objective is to improve our communication skills. The purpose of this study is to examine the effect on communication skills when team teaching is employed, and to find ways to maximize the benefit when team teaching. The underlying issues are; firstly, what are the precedent conditions for team teaching? Secondly, what are the best teaching methods and preparations for teaching materials for improving the effectiveness of team teaching? Third, how do the programs for team teaching with native teachers assist in improving the student's communication skills? Ideally, this study will assist in overcoming the fear that foreign language learners have when communicating with real native speakers.

• Bulletin of the Korean Chemical Society
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• v.32 no.9
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• pp.3245-3250
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• 2011

The nucleophilic substitution reactions of diisopropyl chlorophosphate (3) with substituted anilines ($XC_6H_4NH_2$) and deuterated anilines ($XC_6H_4ND_2$) are investigated kinetically in acetonitrile at $55.0^{\circ}C$. The anilinolysis rate of 3 is rather slow to be rationalized by the conventional stereoelectronic effects. The obtained deuterium kinetic isotope effects (DKIEs; $k_H/k_D$) are secondary inverse ($k_H/k_D$ = 0.71-0.95) with maximum magnitude at X = H.A concerted mechanism involving predominant backside nucleophilic attack is proposed on the basis of the secondary inverse DKIEs.

• Bulletin of the Korean Chemical Society
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• v.32 no.9
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• pp.3411-3420
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• 2011

Kinetic and structural studies have been carried out on the effects of meso-tetrakis(4-sulfonatophenyl)-porphyrin ($H_2TPPS_4$) as an anionic and meso-tetrakis(3-N-methyl-pyridyl)porphyrin ($H_2TMPYP$) as a cationic porphyrin with adenosine deaminase (ADA) in 25 mM citrate/phosphate buffer, pH = 4-8, at $37^{\circ}C$ using UVvis spectrophotometry, circular dichroism (CD), fluorescence spectrophotometry as well as molecular dynamics (MD) and molecular docking. Kinetic results showed that the two porphyrins are non-competitive inhibitors. Increasing pH, increases $K_I$ and cationic porphyrin has a higher $K_I$ and lower binding constant ($K_b$) at all pH ranges. Analyzing the secondary structure revealed that both ligands decrease the secondary structure and that the anionic porphyrin is more effective.

• Journal of the Korean Ceramic Society
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• v.34 no.5
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• pp.453-460
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• 1997

Sr-ferrite having magnetoplumbite structure is similar to Ba-ferrite in magnetic characteristics, but better magnetic characteristics for using motor application. To improve remanence magnetic flux density(Br) and coercive force(iHc), it is necessary that sintered ferrites must have high density and grain size less than 1 $\mu$m. By varying n values in SrO.nFe2O3 basic composition, calcination temperature, and BaO addition, Sr-ferrite powder and sintered specimen was prepared. The n values, calcination temperature, and BaO addition affected secondary phase formation, particle size, and particle shape. BaO addition enhanced Fe2O3 secondary phase and hexagonal shape particle. Fe2O3 phase reduced sintered density which greatly decreased Br.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.7
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• pp.1309-1316
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• 2002

The purpose of this study is to analyze the effects of the parameters of the suspension system in railway rolling-stock for KT-23 type passenger vehicle. According to the results of simulation and the field test, Optimal condition was obtained for the stiffness ratio of the primary spring and the secondary of the suspension system. When the stiffness ratio was increased, the vibration was increased on the car body and decreased on the bogie, and ride quality are getting worse because of increase of the vertical natural frequency of the car body. The results of this study are usefull to improve the technology of the ride quality of KT-23 type vehicle.