• Journal of the Korean Magnetics Society
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• v.17 no.2
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• pp.81-85
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• 2007

MnTe layers of high crystalline quality were successfully grown on Si(100) : B and Si(111) substrates by molecular beam epitaxy (MBE). Under tellurium-rich condition and the substrate temperature around $400^{\circ}C$, a layer thickness of $700{\AA}$ could be easily obtained with the growth rate of $1.1 {\AA}/s$. We investigated the structural, magnetic and transport properties of MnTe layers by using x-ray diffraction (XRD), superconducting quantum interference device (SQUID) magnetometry, and physical properties measurement system (PPMS). Characterization of MnTe layers on Si(100) : B and Si(111) substrates by XRD revealed a hexagonal structure of polycrystals with lattice parameters, ${\alpha}=4.143{\pm}0.001{\AA}\;and\;c=6.707{\pm}0.001{\AA}$. Investigation of magnetic and transport properties of MnTe films showed anomalies unlike antiferromagnetic powder MnTe. The temperature dependence of the magnetization data taken in zero-field-tooling (ZFC) and field-cooling (FC) conditions indicates three magnetic transitions at around 21, 49, and 210 K as well as the great irreversibility between ZFC and FC magnetization in the films. These anomalies are attributable to a magnetic-elastic coupling in the films. Magnetization measurements indicate ferromagnetic behaviour with hysteresis loops at 5 and 300 K for MnTe polycrystalline film. The coercivity ($H_c$) values at 5 and 300 K are 55 and 44 Oe, respectively. In electro-transport measurements, the temperature dependence of resistivity revealed a noticeable semiconducting behaviours and showed conduction via Mott variable range hopping at low temperatures.

• Journal of Soil and Groundwater Environment
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• v.13 no.1
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• pp.13-23
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• 2008

The triaxial compression tests and consolidation tests using NaCl solution and leachates as substitute pore (or saturated) water in samples were carried out to find out the behavior characteristics of strength, deformation and permeability coefficient of contaminated clay. Also, the chemical property analysis on the clay samples using scanning electron microscope and energy dispersive x-ray spectrometer were involved. The magnitudes of composition ratio were shown in the order of O, C, Si, Al, and Fe as a result of chemical composition analysis for clay samples. Besides, as the results of triaxial compression tests and consolidation tests, the shear strength, compression and permeability properties were increased with increasing in the concentration of contaminant (NaCl). It may be considered that these circumstances be caused by the changes of soil structure to flocculent structure due to the decrease in the thickness of diffuse double layer with increasing in the concentration of electrolyte. MT3D model was also using to grasp the procedures that the groundwater may be contaminated by the leachates permeated through the clay liner. The results of contaminant transport analysis showed a tendency that the predicted concentration of groundwater was higher with increasing in the initial concentration of $Cl^-$ ion and increased as a nonlinear curves with time. The transportation distance calculated by the use of regression equation between the distance from contaminant source and the concentration of $Cl^-$ ion was increased with increasing the initial concentration.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.12 no.6
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• pp.54-67
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• 2013

The main purpose of this study is to analyze the diversion rate by the levels of delay and the types of display. For this study, we developed the logit model by analyzing the result of SP survey of drivers who have driver's licence after manipulating a virtual driving simulator. The result of analysis was that the types of display was not statistically significant to the diversion rate. On the other hand, the levels of delay was very meaningful factor with the diversion rate. When the main road was flowing smoothly, drivers started to detour at the levels of delay 125% under the traffic free flow state. Similarly, when the levels of delay got worse, the diversion rate kept the same percentage as it was at the levels of delay 125% state which represented a smooth road condition. Likewise, when the main road's traffic flow was slow, drivers appeared to make detours at the same state of the levels of delay 125%. It was found that as the levels of delay got worse, the diversion rose higher than the diversion rate at the condition of slow traffic flow situation with the levels of delay 125%. The result of this study suggests the criterion of drivers detour point. For the conclusion, the result of study would be a reasonable reference for establishing transportation strategies by reflecting drivers' detouring property and would improve the efficiency of traffic flow.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.10
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• pp.1-7
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• 2018

Tin dioxide, $SnO_2$, is applied as an anode material in Li-ion batteries and a gas sensing materials, which shows changes in resistance in the presence of gas molecules, such as $H_2$, NO, $NO_2$ etc. Considerable research has been done on the synthesis of $SnO_2$ nanostructures. Nanomaterials exhibit a high surface to volume ratio, which means it has an advantage in sensing gas molecules and improving the specific capacity of Li-ion batteries. In this study, $SnO_2$ nanostructures were grown on a Si substrate using a thermal CVD process with the vapor transport method. The carrier gas was mixed with high purity Ar gas and oxygen gas. The crystalline phase of the as-grown tin oxide nanostructures was affected by the oxygen gas flow rate. The crystallographic property of the as-grown tin oxide nanostructures were investigated by Raman spectroscopy and XRD. The morphology of the as-grown tin oxide nanostructures was confirmed by scanning electron microscopy. As a result, the $SnO_2$ nanostructures were grown directly on Si wafers with moderate thickness and a nanodot surface morphology for a carrier gas mixture ratio of Ar gas 1000 SCCM : $O_2$ gas 10 SCCM.

• Membrane Journal
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• v.26 no.4
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• pp.239-252
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• 2016

Two-dimensional materials offer unique characteristics for membrane applications to water technology. With its atomic thickness, availability and stackability, graphene in particular is attracting attention in the research and industrial communities. Here, we present a brief overview of the recent research activities in this rising topic with bringing two membrane architecture into focus. Pristine graphene in single- and polycrystallinity poses a unique diffusion barrier property for most of chemical species at broad ambient conditions. If well designed and controlled, physical and chemical perforation can turn this barrier layer to a thinnest feasible membrane that permits ultimate permeation at given pore sizes. For subcontinuum pores, both molecular dynamics simulations and experiments predict potential salt rejection to envisage a seawater desalination application. Another novel membrane architecture is a stack of individual layers of 2D materials. When graphene-based platelets are chemically modified and stacked, the interplanar spacing forms a narrow transport pathway capable of separation of solvated ions from pure water. Bearing unbeknownst permeance and selectivity, both membrane architecture - ultrathin porous graphene and stacked platelets - offer a promising prospect for new extraordinary membranes for water technology applications.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.16 no.1
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• pp.117-130
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• 2017

Bicycles are leading to serious accidents in the event of a side collision, and it is very important to prevent accidents in advance because it is difficult to actively deal with them in a dangerous situation. As a part of the bicycle safety driving support technology, this study establishes bicycle accidents dangerous zone based on bicycle accident data and road property information of digital map nationwide and provides timely safety information to cyclists. The point selected by using actual accident data was called 'dangerous zone', and the potential accident occurrence point generated by modeling based on this 'dangerous zone' was called 'logical dangerous zone'. As a result of the research on the Designation of Logical Bicycle Accident Dangerous Zone, the regional specificity of the bicycle accident points across the nation was generalized to the form of the logical dangerous zone through the network data.

• Journal of the Korean Electrochemical Society
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• v.11 no.1
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• pp.42-46
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• 2008

Even though fuel cell have high efficiency when pure hydrogen from gas tank is used as a fuel source, it is more beneficial to generate hydrogen from city gas (mainly methane) in residential application such as domestic or office environments. Thus hydrogen is generated by reforming process using hydrocarbon. Unfortunately, the reforming process for hydrogen production is accompanied with unavoidable impurities. Impurities such as CO, $CO_2$, $H_2S$, $NH_3$, $CH_4$, and $CH_4$ in hydrogen could cause negative effects on fuel cell performance. Those effects are kinetic losses due to poisoning of the electrode catalysts, ohmic losses due to proton conductivity reduction including membrane and catalyst ionomer layers, and mass transport losses due to degrading catalyst layer structure and hydrophobic property. Hydrogen produced from reformer eventually contains around 73% of $H_2$, 20% or less of $CO_2$, 5.8% of less of $N_2$, or 2% less of $CH_4$, and 10ppm or less of CO. This study is aimed at investigating the effect of carbon dioxide on fuel cell performance. The performance of PEM fuel cell was investigated using current vs. potential experiment, long run(10 hr) test, and electrochemical impedance measurement when the concentrations of carbon dioxide were 10%, 20% and 30%. Also, the concentration of impurity supplied to the fuel cell was verified by gas chromatography(GC).

• Korean Journal of Food Science and Technology
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• v.35 no.6
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• pp.1117-1123
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• 2003

The effects of heat treatment on the physical and physical and physiological properties of wax gourd (Benincasa hispida) were examined. The applied heat treatments were autoclaved at $121^{\circ}C$ for 1 hr, boiled for 30 min, and microwaved at 680 W for 5 min. The water retention capacity (WRC) of the wax gourds was 9.43 g/g for the microwaved samples, 5.12 g/g for the boiled samples, 4.63 g/g for the raw samples, and 2.61 g/g for the autoclaved samples. Heat treatment caused to increase swelling by up to $4.4{\sim}7.8\;mL/g$. Calcium binding capacity of heat-treated wax gourd increased in the order of microwaved, boiled, raw, autoclaved samples. Scanning electron microscopy (SME) showed that autoclaving caused the most severe structural modifications, while microwave treatment produced the least modifications. The retarding effect on glucose and bile acid transport depended on the heat treatment. Only boiling showed the glucose retardation effect. Bile acid retardation effect increased in order of boiling (22.9%), autoclaving (17.1%), microwave treatment (14.3%), and raw wax gourd (8.6%). The cadmium retardation effect was significantly high in all samples.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.10
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• pp.1257-1262
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• 2007

To develop basidiomycetes-fermented cereals with hypoglycemic property, inhibitory effects of basidiomycetes mycelia and basidiomycetes-fermented cereals on postprandial glucose were investigated. In vitro effect of basidiomycetes mycelia on retarding the membrane transport of glucose was compared with pectin. For basidiomycetes mycelia, $13.1{\pm}3.6{\sim}41.8{\pm}8.0%$ of total glucose remained in inner solution of dialysis membrane after dialysis for 120 min, indicating that most of basidiomycetes mycelia might effectively retard membrane transport of glucose. Glucose tolerance of basidiomycetes mycelia and basidiomycetes-fermented cereals was tested on streptozotocin-induced diabetic rats administrated with maltose. Postprandial glucose levels of basidiomycetes mycelia, $389.4{\pm}43.8{\sim}426.3{\pm}49.4mg/dL$, were considerably lower than that of control, $535.3{\pm}78.6mg/dL$, at 30 minutes after maltose administration. Namely, basidiomycetes mycelia showed better postprandial glucose lowering effect than pectin. Brown rice and barley fermented with Paecilomyces japonica showed much lower postprandial glucose level than raw brown rice and barley, especially hypoglycemic effect of barley fermented with Paecilomyces japonica was significant.

• Korean Security Journal
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• no.57
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• pp.27-55
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• 2018

The problem is that even though the cost of apartment buildings and general expenses are the same and similar tasks, there is a significant gap between them in quantity and quality. The apartment security guard needs more professional management in education and various reporting obligations. In particular, the reality of being away from the management and supervision of the National Police Agency, which is in charge of crime prevention and policing resources throughout the nation, is a task that needs to be improved quickly. Although the "security service" is a specialized area for protecting the lives and property of the people, it is managed and operated only in the category of apartment management, just because it is under the jurisdiction of the Ministry of Land, Infrastructure and Transport. This should be integrated into one cost-related law, such as the "Cost Business Act," for management and operation. Although the regulations concerning security guards under the "Joint Housing Management Act" are very limited, they should start discussing the integrated management of apartment security guards and general security guards in view of improvement of their treatment. The most realistic method would be to hire a new general security officer with a security law as a security guard in an apartment building.