• Journal of Korean Elementary Science Education
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• v.37 no.2
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• pp.147-160
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• 2018

The purpose of this study is to compare the elementary science curriculum and textbooks of Korea, the United States, Japan, and Singapore to know how the contents on particulate concept of matter is introduced and expressed. In Korea, particulate concept of matter was adopted as a term for 'molecules' in the 3rd through 6th curriculum, and the term for 'particles' was adopted in the 2009 revised curriculum. In the United States, NGSS adopted the term 'particle' in fifth grade. Japan presented the concept of 'particle' as a core concept of matter in the commentary, and the expressions 'particles' were being introduced in the textbooks. But it did not cover particulate nature of matter at the elementary school level in Singapore. An analysis of elementary textbooks in Korea, the United States and Japan except Singapore showed particulate expressions in 'dissolution', 'state change of water', 'gas pressure and volume', 'combustion and extinguishment' units. Korean textbook was only being introduced in 'dissolution' and 'gas pressure and volume', but in the textbooks of Japan and the United States, water was expressed as particles in 'state change of water' unit. Discussion and implication on the introduction of particulate concept to elementary science curriculum and textbooks were suggested based on the results.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.196.2-196.2
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• 2016

The design and development procedures of SF6 gas circuit breakers are still largely based on trial and error through testing although the development costs go higher every year. The computation cannot cover the testing satisfactorily because all the real processes arc not taken into account. But the knowledge of the arc behavior and the prediction of thermal plasmas inside SF6 interrupters by numerical simulations are more useful than those by experiments due to the difficulties to obtain physical quantities experimentally and the reduction of computational costs in recent years. In this paper, in order to get further information into the interruption process of a SF6 self-blast interrupter, which is based on the combination of thermal expansion and arc rotation, gas flow simulations with a CFD-arc modeling are performed during the whole switching process such as high-current period, pre-current zero period, and current-zero period. Through the complete work, the temperature of residual arcs as well as the breakdown index after current zero should be a good criterion to predict the dielectric capability of interrupters.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.2
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• pp.52.1-52.1
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• 2015

FIMS/SPEAR is a dual-channel far-ultraviolet imaging spectrograph on board the Korean microsatellite STSAT-1, which was launched on 2003 September 27. The primary mission goal of FIMS was to conduct a survey of diffuse far UV emissions in our Galaxy. For this purpose, FIMS completed a survey of about 84% of the sky during its operation of a year and a half. The present study aims to analyze this survey data made in the far UV wavelengths to understand the global evolution of our Galaxy. The far UV wavelength band is known to contain important cooling lines of hot gas: hence, the study will show how the hot gas in our Galaxy, produced by stellar winds and supernova explosion, evolves globally to cool down and become mixed with ambient cooler medium. One of the main findings from previous analyses of the FIMS data is that molecular hydrogen exists ubiquitously in our Galaxy. This discovery leads to another important scientific question: how is molecular hydrogen distributed in our Galaxy and how does it affect globally the evolution of our Galaxy as a cold component? Hence, the present study will cover both the hot and cold components of the ISM, which will also provide the opportunity to investigate the interactions between the two.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.2
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• pp.41.3-41.3
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• 2015

As part of the Herschel key program "Water in Star-forming Regions with Herschel (WISH)", PACS imaging spectroscopy data have been taken toward ten massive young stellar objects (YSOs): four high mass protostellar objects (HMPOs), two hot molecular cores (HMCs), and four ultracompact HII regions (UCHIIs). The spectra cover a broad range of wavelengths (55 to 210 micron) presenting various atomic and molecular lines as well as excellent dust thermal continua. By fitting the continua utilizing a modified black-body formula we estimate mass-weighted temperature and column density distributions of warm dust and find that UCHII regions are warmer and HMCs are more deeply embedded than the other types. We also estimate rotational temperature and column density distributions of warm CO gas using the rotational diagram analysis. In addition, based on the comparison of high J CO line fluxes to the RATRAN estimates of central heating envelope models, we find that majority of warm CO is originated from bipolar outflow shocks.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.04a
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• pp.73-76
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• 2002

Biofilter performance to reduce C $H_4$ emissions from MSW landfills was tested under a variety of environmental and design conditions. The optimum soil moisture content for C $H_4$ oxidation in a loamy sand was 13% by weight. The addition of N $O_3$-N did not affect the C $H_4$ oxidation rate. Soil depths of 30cm and 60cm were equally efficient in C $H_4$ oxidation. When the C $H_4$ loading rate was decreased, the percentage of C $H_4$ oxidized increased. The maximum C $H_4$ oxidation rate was 27.2 mol $m^{-2}$ $d^{-1}$ under optimum conditions (loamy sand soil, 13% moisture content, 30cm soil depth, and an loading rate of 32.8 mol $m^{-2}$ $d^{-1}$). Based on the above results, the installation of a properly sized and managed biofilter above a landfill cover should be capable of achieving a major reduction in atmospheric methane emissions from MSW landfills built with RCRA covers.

• Progress in Superconductivity and Cryogenics
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• v.4 no.2
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• pp.73-77
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• 2002

In order to derive the detailed design of Thermal Shield Cryopanel. which plays a role to make the Tokamak Nuclear Fusion Equipment work at both static and efficient conditions the commercially available software package FLUENT Version 5.3, was utilized. This study investigated the effects of thermal sources and distributions on the temperatures of Lid. Body. Base. and EH-Port Cryopanel by the numerical technique whose grid generations cover the solid and 9as region of the panel. The physical model of the Thermal Shield Cryopanel is that the 10mm diameter of the pipe with 1mm thickness is soldered on the Stainless steel Panel with 4mm thickness. The heat fluxes to the panel are assumed to be by thermal radiation in the vacuum space and by conduction through the supporters. The inlet conditions of Helium gas are 20 atmospheric Pressures and 60K temperature. The panel shapes with cooling Pipes and the operational conditions to keep appropriate temperature distribution of Thermal Shield Cryopanel Have been found and suggested.

• Corrosion Science and Technology
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• v.16 no.2
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• pp.85-89
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• 2017

One of the most challenging issues in the oil and gas industry is corrosion assessment and management in subsea structures or equipment. At present, almost all steel pipelines are sensitive to corrosion in harsh working environments, particularly in salty water and sulphur ingress media. Nowadays, the most commonly practiced solution for a damaged steel pipe is to entirely remove the pipe, to remove only a localized damaged section and then replace it with a new one, or to cover it with a steel patch through welding, respectively. Numerous literatures have shown that fiber-reinforced polymer-based composites can be effectively used for steel pipe repairs. Considerable research has also been carried out on the repair of corroded and gouged pipes incorporated with hybrid natural fiber-reinforced composite wraps. Currently, further research in the field should focus on enhanced use of the lesser and highly explored hybrid-biocomposite material for the development in corrosion prevention. A hybrid-biocomposite material from renewable resource based derivatives is cost-effective, abundantly available, biodegradable, and an environmentally benign alternative for corrosion prevention. The aim of this article is to provide a comprehensive review and to bridge the gap by developing a new hybrid-biocomposite with superhydrophobic surfaces.

• Journal of the Korean Institute of Gas
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• v.13 no.2
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• pp.30-35
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• 2009

The result of this research explains an interactive behavior of buried steel pipe located below hume pipe using concept of effective depth and effective length against their intersection angle and burial distance. The cover depth of upper rigid (hume) pipe is 1.0m and depth range of flexible (steel) pipe is 0.5m to 5m from beneath bottom of hume pipe. And one more variable is their intersection angle in this study, it was considered from $0^{\circ}$ to $90^{\circ}$. From the results of this study, the effective depth is proportionally increasing with its intersection angle and decreasing with distance increment between two pipes. Finally, the relationship between effective length and summation of occurred bending stress is defined.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.168-168
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• 2008

Dimension of a transistor has rapidly shrunk to increase the speed of device and to reduce the power consumption. However, it is accompanied with several problems like direct tunneling through the gate dioxide layer and low conductivity characteristic of poly-Si gate in nano-region. To cover these faults, study of new materials is urgently needed. Recently, high dielectric materials like $Al_2O_3$, $ZrO_2$, and $HfO_2$ are being studied for equivalent oxide thickness (EOT). However, poly-Si gate is not compatible with high-k materials for gate-insulator. Poly Si gate with high-k material has some problems such as gate depletion and dopant penetration problems. Therefore, new gate structure or materials that are compatible with high-k materials are also needed. TiN for metal/high-k gate stack is conductive enough to allow a good electrical connection and compatible with high-k materials. According to this trend, the study on dry etching of TiN for metal/high-k gate stack is needed. In this study, the investigations of the TiN etching characteristics were carried out using the inductively coupled $BCl_3$-based plasma system and adding $Cl_2$ gas. Dry etching of the TiN was studied by varying the etching parameters including $BCl_3$/Ar gas mixing ratio, RF power, DC-bias voltage to substrate, and $Cl_2$ gas addition. The plasmas were characterized by optical emission spectroscopy analysis. Scanning electron microscopy was used to investigate the etching profile.

• Journal of Environmental Impact Assessment
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• v.12 no.3
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• pp.161-170
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• 2003

To investigate the characteristics of 17 solid waste landfills in the upper drainage basin of Lake Daechong, the landfill sites were surveyed, the leachate of these landfills were analyzed, and the analysis results were assessed from standpoint of water contamination. Sanitary landfills which are now being operated are relatively well equipped with facilities such as leachate collection, daily soil cover and landfill gas treatment devices. But a few of open-dumping landfills were leaking leachate apparently and were supervised improperly and neglectfully by local governments. Some of sanitary landfills exceeded the COD permission criteria of leachate effluent, and some of open-dumping landfills exceeded SS, T-P, Pb, As, Fe, Mn permission criteria of leachate effluent. To improve the water quality of Lake Daechong which is utilized for supplying drinking water, agricultural water, and industrial water to the great part of Chungchong area, the adequate and prompt measures for preventing Daechong Lake water contamination from landfills leachate is necessary.