• Korean Chemical Engineering Research
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• v.55 no.5
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• pp.668-678
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• 2017

Intermolecular interactions were studied for binary mixtures of 2-propanol + cyclohexane, n-hexane, benzene, toluene, o-, m- and p-xylenes by measuring ultrasonic speeds (u) over the entire range of composition at 298.15 K and 308.15 K. From these results the deviation in ultrasonic speed was calculated. These results were fitted to the Redlich-Kister equation to derive the binary coefficients along with standard deviations between the experimental and calculated data. Acoustic parameters such as excess isentropic compressibility ($K_s^E$), intermolecular free length ($L_f$) and available volume ($V_a$) were also derived from ultrasonic speed data and Jacobson's free length theory. The ultrasonic speed data were correlated by Nomoto's relation, Van Dael's mixing relation, impedance dependence relation, and Schaaff's collision factor theory. Van Dael's relation gives the best prediction of u in the binary mixtures containing aliphatic hydrocarbons. The ultrasonic speed data and isentropic compressibility were further analyzed in terms of Jacobson's free length theory.

• Economic and Environmental Geology
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• v.33 no.2
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• pp.117-128
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• 2000

Regional evaluations of slope stability by the failure criterion and by environmental geological factors were conducted. The failure criterion is the general conditions for plane failure which consider the geometrical conditions between geological discontinuities and topographical slope planes. The factor focused in this condiction is dip and dip direction. Geostatics, named semivariogram was used for establishing structural domains in slope stability evaluation by the failure criterion. The influential range was calculated to 6 km in the case of dip direction of dominant joint set and 7 km in the case of dip of the same dominant joint set. Then applying this failure criterion to the study area produced a slope stability map using the established domains and slopes generated by TIN module of ARC/INFO GIS. This study considered another regional slope stability analysis. 5 failure-driven factors 9the unstable slope map, geology, engineering soil, groundwater, and lineament density) were selected and used as data coverages for regional slope stability evaluation by geoenvironmental factors. These factors were weighted and overlayed in GIS. From the graph of cumulatave area (%) and instability index, finding critical points classified the instability indices. The most unstable slopes are located in the southern area of Mt. Eorae, Dabul-ri, and the eastern area of Junkok-ri in the first area is plane failure. Also, the expected orientations of failure are 59/338 and 86/090 (dip/dip direction).

• Journal of Industrial Technology
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• v.24 no.A
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• pp.37-46
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• 2004

A performance analysis for newly being considered electric rail car office has been made in this study. The major purpose is to examine a proposed design in terms of its capacity and the proposed number of travels (82-84) per day. For this study we first examined the overall system configuration with detailed operational processes of cleaning and inspection. We then developed a simulation model using ARENA and designed input data from 12 selected factors and their interaction effects. A simulation run for each treatment combination of $L_{16}(2^{15})$ orthogonal array was run and 20 batch means were obtained. Through careful analyses of the results obtained, we drew a diversity of suggestions including the best factor level combination. Our confirmation experiments at the optimal level combination further validate the possibility of 82 runs and the consistency in the results.

• Journal of the Korean Chemical Society
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• v.59 no.5
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• pp.407-412
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• 2015

A preconcentration procedure for determination of palladium by laser thermal lens spectrometry (TLS) is proposed. It is based on cloud point extraction of palladium(II) ions as 2-(3,5-dichloro-2-pyridylazo)-5-dimethylaminoaniline (3,5-diCl-PADMA) complexes using octylphenoxypolyethoxyethanol (Triton X-114) as surfactant. The effects of various experimental conditions such as pH, concentration of ligand and surfactant, equilibration temperature and time on cloud point extraction were studied. Under the optimized conditions, the calibration graph was linear in the range of 0.15~6 ng mL⁻¹, and the detection limit was 0.04 ng mL⁻¹ with an enrichment factor of 22. The sensitivity was enhanced by 846 times when compared with the conventional spectrophotometric method. The recovery of palladium was in the range of 96.6%~104.0%. The proposed method was applied to the determination of palladium in water samples.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.11C
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• pp.1132-1138
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• 2002

This paper proposes a reducing power consumption of a scheduling algorithm for optimal selection of supply voltage. In scheduling of reduction power consumption, we determine the control steps of operations to be executed by exploiting the possibility of using variable voltage levels to reduce power consumption. In the optimal selection of supply voltage binding, we minimize the main factor of the power consumption of the switching activity on the registers using a graph coloring technique. From a set of experiments using high-level benchmark examples, we show that the proposed algorithm prefer to use optimal selection supply voltages rather than uniformed single voltage is effective in reducing power consumption.

• The Mathematical Education
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• v.41 no.1
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• pp.19-34
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• 2002

The 7th national mathematics curriculum lays emphasis on an interrelation of several subjects and a connection between mathematics and real life. In this reason, this study focuses on the enhancement of sound understanding nuclear energy which is one of important factor(concepts or contents) dealt with in the other subjects such as science, environment, social studies, etc.. Recently, even though it is insistent that nuclear energy be so important and request in the future society, there are still strong pro and cons regarding the use of it. In this study, teaching-and-learning materials were developed dealing with using nuclear energy, and consequently they might be used in math class for the purpose of enhancement of mathematical learning ability and of recognition on nuclear energy. In this study, Material 1 included a matter of the necessity for nuclear power plants using the ratio concept, and Material 2 did on a matter of the efficiency of nuclear energy and the unclear of nuclear power plants using ratio-graph, in the elementary and upper school mathematics. Material 3 focused on a matter of the principles of nuclear power plants using the properties of exponential law in high school mathematics. Ultimately, it is hoped in the study that more diverse instructional materials dealing with diverse situations inside and outside mathematics would be developed.

• Bulletin of the Korean Chemical Society
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• v.24 no.1
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• pp.27-31
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• 2003

A Polythiophene-quinoline/glassy carbon (PTQ/GC) modified electrode was developed for the determination of trace mercury in industrial waste water, natural water, soil, and other media. The electrode was prepared by the cyclic voltammetric polymerization of thiophene and quinoline on glassy carbon (GC) electrode by the potential application from -0.6 V to +2.0 V (50 mV/sec) in a solution of 0.1 M thiophene, quinoline and tetrabutyl ammonium perchlorate (TBAP) in acetonitrile. Optimum thickness of the polymer membrane on the GC electrode was obtained with 20 repeated potential cyclings. The redox behavior of Cu(Ⅱ) and Hg(Ⅱ) were almost identical on this electrode. The addition of 4-(2-pyridylazo)resorcinol (PAR) to the solution containing Cu(Ⅱ) and Hg(Ⅱ) allowed the separation of the components due to the formation of the Cu(Ⅱ)-PAR complex reduced at -0.8V, which was different from the Hg(Ⅱ) reduced at -0.5 V on a saturated calomel electrode (SCE). The calibration graph of Hg(Ⅱ) shows good linear relationship with the correlation factor of 0.9995 and the concentration gradient of 0.33 ㎂/㎠/ppb down to 0.4 ppb Hg. The method developed was successfully applied to the determination of mercury in samples such as river, waste water, and sea water.

• Transactions of the Korean Society of Automotive Engineers
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• v.23 no.6
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• pp.615-622
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• 2015

Recently Digital-TachoGraph(DTG) was mounted mandatorily in commercial vehicles(Taxi, Bus, etc.). DTG records accurate and detailed information of the running state of vehicles related to traffic accident, such as Time, Distance, Velocity, RPM, Brake ON/OFF, GPS, Azimuth, Acceleration. Thus those standardized data can play an important role in traffic accident investigation and reconstruction. To develope the accurate and objective method using the DTG data for the reconstruction of traffic accident, we had conducted several tests such as driving test, high speed circuit test, braking test, slalom test at Korea Automobile Testing & Research Institute(KATRI), and collision test at Korea Automobile insurance repair Research and Training center(KART) with the vehicle equipped with several DTG. Development of the program which enables the reading and analysis of the DTG data was followed. In the experiments, we have found velocity error, RPM error, brake signal error and azimuth error in several products, and also non-continuous event data. The cause of these errors was deduced to be related to the correction factor, the durability of electronic parts and the algorithm.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.3
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• pp.77-86
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• 2018

Recently, Korean construction industry is moving from quantitative growth to qualitative growth. Among the changes in the construction industry, the competency of the project manager who represents the construction project as well as the construction company has been referred to as a factor that effects qualitative growth. This research utilized previous research analysis and expert interview in order to extract essential competency factors of a construction project manager. DEMATEL method was utilized to analyze the quantitative and objective causal relationship between the competency factors. The causal relationship of the competency factors were visualized through Digraph (directed graph) and competency areas of the project manager that requires strengthening were also suggested. Analysis result showed that the important competency categories of a project manager were Internal & External Communication, Project Management Body of Knowledge, and Inspirational Leadership. The analysis results of this research can be utilized in developing competency enhancement method for future project managers and as a basic data in developing an education program.

• Educational Technology International
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• v.13 no.1
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• pp.145-173
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• 2012

The purpose of this study is to develop collaboration scripts as an instructional means to facilitate argumentation in computer-supported collaborative learning, and to analyze their effects. To develop collaboration scripts for argumentation, researchers used activity theory as a conceptual framework and refined the design principles by design-based research. Using LAMS, collaboration scripts for argumentation were developed based on the ArgueGraph. To examine their effects, 72 participants were divided into two groups by internal scripts and randomly allocated to one of three external scripts. Applying mixed methods, researchers analyzed argumentation competence related to the cognitive aspect, examined self-efficacy related to the motivational aspect, and identified the factors influencing collaborative learning processes and outcomes. Researchers found that the internal script is a critical factor to determine the dimensions, degrees, and duration of improvement in argumentation competence. That is, learners with higher internal scripts improved highly in the quality of single arguments, while learners with lower internal scripts improved continuously in the quality of argumentation sequences. The effects of the external scripts varied with the internal script levels and supporting periods. Besides, collaboration scripts for argumentation had positive effects on learners' self-efficacy, and learners with higher internal scripts had better self-efficacy. The factors influencing collaborative learning processes and outcomes showed different results depending on the learning context. Therefore, when scripting learner's interaction in CSCL, researchers should design the scripts adaptable to a natural context of activities.