• Analytical Science and Technology
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• v.8 no.4
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• pp.739-744
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• 1995

The two main methods to prepare water samples for analyzing volatile organic compounds(VOC's) were investigated. One is the purge and trap(PT) method and another is the head space(HS) sampling method. Both methods were effective to transfer the low boiling point components from the water sample onto the capillary column. The cryo-focusing at the top of the main capillary column was an effective way to obtain the sharpness of the chromatographic peaks but could be avoided when a semi-wide bore column was used. The recovery from the same amount of the sample was better in PT than in HS but a larger sample volume in HS method could compensate the lower efficiency. Therefore PT is suitable to the analysis of drinking water where the very low concentration must be determined. HS is suitable to waste water analysis because of the easiness of the operation. The repeatability was good and similar in both methods. For the contamination of the former sample, both methods were tough and could be used without any problems. The matrix effect which could change the equilibrium parameters in HS method was find negligible in many components. The actual samples such as tap water and river water were analyzed with both methods concerning 16 components regulated in Korea.

• Applied Chemistry for Engineering
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• v.5 no.4
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• pp.657-661
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• 1994

A method to analyse the concentration of mixture (AC/urea) and the concentration of urea or AC alone was developed. In this study, the decomposition of AC solution to ammonium bicarbonate was suppressed by using of 15% w/v ammonia as a solvent and the error of equilibrium point was maintained less than 1 %. Strong peaks at $1600cm^{-1}$ for urea and at $1405cm^{-1}$ for AC, corresponding to the N-H bending and symmetric carboxylate ion stretch were used to construct calibration graph and equations for the measurement of concentration. The errors of calculated concentration were ${\pm}0.1%$ w/v for AC and ${\pm}0.3%$ w/v for urea.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.10
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• pp.863-870
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• 2002

Fossil fuels have been depleted gradually and new energy resource which can solve this shortage is needed now. Methane hydrate, non-polluting new energy resource, satisfies this requirement and considered the precious resource prevent the global warming. Fortunately, there are abundant resources of methane hydrate distribute in the earth widely, so developing the techniques that can use these gases effectively is fully valuable. the work presented here is to develop the skill which can transport and store methane hydrate. As a first step, the equilibrium point experiment has been carried out by increasing temperatures in the cell at fixed pressures. The influence of gas consumption rates under variable degree of subcooling, stirring and water injection has been investigated formation to find out kinetic characteristics of the hydrate. The results of present investigation show that the enhancements of the hydrate formation in terms of the gas/water ratio are closely related to operational pressure, temperature, degrees of subcooling, stirring rate, and water injection.

• Korean Journal of Crystallography
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• v.14 no.1
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• pp.35-38
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• 2003

A simple multistep-concentration setting in capillaries was used to control the water-evaporation rate in vapor-diffusion protein crystallization. In the method used, a variety of evaporation rate curves were obtained by using the secondary precipitant solution referred to as “regulatory solution”, which is not directly exposed to the protein solution. The curves were applied to the crystallization of lysozyme as a model protein. The results clearly showed that crystal growth is dependent on the evaporation rate. Especially, the decoupling curves in which precipitant concentration in protein solutions increases to a certain point and then decreases to the equilibrium concentration gave the best crystals.

• Journal of the Korean Society of Tobacco Science
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• v.8 no.1
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• pp.23-31
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• 1986

The water content, physical property and sensory of cigarette brands lave been studied from the view point of the individual and inner packages. It was found that the cigarettes had absorbed the moisture from alto more than 56% of a relative humidity (RH) and lost it under RH, 56%. The critical moisture contents for the optimum quality of cigarette maintenance were 7.7% through 14.595 in the range of equilibrium relative humidity (ERH) 52.2%-63.5%. The ERH at the initial moisture content of 12.1% showed 58.8% When cigarettes were storaged in 9095 of RH and 4$0^{\circ}C$, the shelf life of the Inner package was respectively shown 18.8 days In cellophane, 33.3 days In PET(25u), 69.8 days in OPP and 73.5 days in OPP film coated with PVDC. As shown above, the longest life time was found in the OPP film coated with PVDC. In the individual packages, the shelf life of packaging materials used above was significantly short in the same conditions as of the inner packages. Each shelf life of the individual packages was same In order comparing with that of the inner Packages.

• Environmental Engineering Research
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• v.25 no.3
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• pp.426-438
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• 2020

In this study, cherry kernel shell pyrolytic charcoal was synthesized (CKSC) and composite beads were obtained by blending this pyrolytic charcoal with chitosan and Fe₂O₃ nanoparticles (Fe-C-CKSC). Cr(VI) adsorption from aqueous solutions by Fe-C-CKSC composite beads and CKSC adsorbents was studied comparatively. The effects of Cr(VI) initial concentration, adsorbent dosage, contact time, pH and temperature parameters on Cr(VI) adsorption were investigated. Adsorption reached an equilibrium point within 120 min for CKSC and Fe-C-CKSC adsorbents. The maximum Cr(VI) removal was obtained at the initial pH value of 1.56 for CKSC and 2.00 for Fe-C-CKSC. The optimum adsorbent dosage was found to be 5 g/L for CKSC and 3 g/L for Fe-C-CKSC. Based on the Langmuir model, the maximum adsorption capacities were calculated as 14.455 mg/g and 47.576 mg/g for CKSC and Fe-C-CKSC, respectively. Thermodynamic and kinetic studies were performed. As a result of adsorption kinetics calculations, adsorption was found to be consistent with the pseudo second order kinetic model. Characterization of the synthesized adsorbents was performed by SEM, BET, FTIR and elemental analysis. This study has shown that low cost adsorbents CKSC and Fe-C-CKSC can be used in Cr(VI) removal from aqueous solutions.

• Journal of the Korean Chemical Society
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• v.26 no.2
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• pp.107-113
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• 1982

Addition of dimedone to thioxanthylium ion generated from the oxidation of thioxanthene by thianthrene cation radical perchlorate in acetonitrile gave 9-(4,4-dimethylcyclohexane-2,6-dionyl)thioxanthylium perchlorate (2), whereas from the reverse addition between two reactants was obtained initially 9-(4,4-dimethylcyclohexane-2,6-dionyl)thioxanthene (1), which then underwent further reaction to give 2. The compound 2 was readily deprotonated in aq acetone to give 9-(4,4-dimethylcyclohexane-2,6-dionylidene)thioxanthene (3). However, 3 turned out to be in equilibrium with 2 in which three isosbestic points at 219, 289, and 348 nm were recorded in aq acetonitrile. The intensity and the position of the maximum absorption of 3 near 380 nm vary depending on the solvents which has been explained in terms of the solvent-solute interactions.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2000.05a
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• pp.249-255
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• 2000

HRIV(Hybrid Rule-Interval Variation) method is presented to stabilize a class of nonlinear systems, where SMC(Sliding Mode Control) and ADC (ADaptive Control) schemes are incorporated to overcome the unstable characteristics of a conventional FLC(Fuzzy Logic Control). HRIV method consists of two modes: I-mode (Integral Sliding Mode PLC) and R-mode(RIV method). In I-mode, SMC is used to compensate for MAE(Minimum Approximation Error) caused by the heuristic characteristics of FLC. In R-mode, RIV method reduces interval lengths of rules as states converge to an equilibrium point, which makes the defined Lyapunov function candidate negative semi-definite without considering MAE, and the new uncertain parameters generated in R-mode are compensated by SMC. In RIV method, the overcontraction problem that the states are out of a rule-table can happen by the excessive reduction of rule intervals, which is solved with a dynamic modification of rule-intervals and a transition to I-mode. Especially, HRIV method has advantages to use the analytic upper bound of MAE and to reduce Its effect in the control input, compared with the previous researches. Finally, the proposed method is applied to stabilize a simple nonlinear system and a modified inverted pendulum system in simulation experiments.

• Journal of the Korean Home Economics Association
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• v.40 no.12
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• pp.1-11
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• 2002

This paper is intended as an analysis of the Chapter on Family in textbooks of a Middle school course at the aspect of Parson's Structural Functionalism Theory. In this analysis, We'd like to explore how the value of family is expressed in the Art-Home Economics textbooks. Generally, family is a subsystem in the structural system of whole society and family has two main functions to promote stability and equilibrium from the Parson's Structural Functionalism Theory point of view. Today, the concern with the Structural Functionalism Theory is dominantly reflected in textbooks, even though it has been proposed that the Structural Functionalism is not appropriate to explain family of modem society. Like that, the question now arises: the family history and interaction is ignored in the Structural Functionalism Theory. That is to say, There are limitations of Structural Functionalism Theory. The textbooks of Art-Home Economics was based on the revised curriculum has been severely changed in terms of external system of textbooks. But, we didn't know how much the view of the Structural Functionalism Theory is involved in textbooks. In this article, we analyze the view of the Structural Functionalism Theory in the Art- Home Economics textbooks using the Contents Analysis. At the same time, we find the confusion of family value revealed in textbooks.

• Industrial Engineering and Management Systems
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• v.15 no.4
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• pp.385-395
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• 2016

Game theory is a powerful tool for analyzing the Supply chain (SC) with different conflicting elements. Among them, the Stackelberg game is the one in which a player as leader has more power than the other ones as followers. Since in many SC systems one element has, in essence, more power than the others; the Stackelberg game has found many applications in SC studies. In this paper, we apply the Stackelberg game-theoretic approach and the corresponding equilibrium point to formulate and analyze a two echelon VMI SC. Comprehensive computational results on an experimental case are conducted to numerically analyze the performance of VMI system against three groups of critical parameters. Moreover, a critical comparison demonstrates the poorer performance of decentralized VMI system than centralized one. This naturally necessitates designing proper contracts between VMI partners in order to more effectively implement the realistic decentralized system.