• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.622-625
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• 2005

본 연구의 목적은 동해 울릉분지 천부퇴적층의 공극수와 메탄의 특징 및 상호작용을 규명하는데 있다. 울릉분지에서 채취한 코어에서 공극수를 추출하여 분석한 결과, 공극수의 황산염 농도가 퇴적물의 심도가 증가할수록 감소하며, 감소하는 경향은 크게 세 가지 (직선성, concave down, upward kink)로 나뉨을 알 수 있었다. 이는 모든 코어에서 황산염 환원작용이 일어나고 있음을 지시한다 황산염 농도의 수직적 구배를 이용하여 SMI (sulfate-methane interface) 심도를 계산하면, 남부울릉분지가 북부울릉분지보다 낮은 값을 갖는다. 반면에 메탄 농도는 퇴적물의 심도가 증가할수록 전반적으로 증가하며, 공간적으로는 남부 울릉분지가 북부울릉보지보다 높다. 또한 남부울릉분지에서 메탄가스 농도는 SMI 심도 아래에서 급격히 증가한다 메탄가스의 탄소 안정동위원소$(\delta^{13}C)$ 분석 값들은 대부분 $-60\%_{\circ}$이하로서 이는 메탄가스가 열기원 보다는 박테리아기원임을 지시해준다 또한 남부 울릉분지에서 메탄의 탄소 안정동위원소 분석 값들은 메탄농도가 증가할수록 낮은 값을 보여 주는 데 이러한 결과들은 남부 울릉분지에서 무산소 메탄 산화작용이 일어나고 있음을 지시하고, 메탄의 상향 분산 (diffusion)량이 북부 울릉분지보다 많이 일어난다는 것을 의미한다. 공극수내 황산염 이온 농도 구배와 메탄가스 농도를 종합적으로 고려할 때, 울릉분지에서 가스하이드레이트의 부존가능성은 북부 울룽분지보다 남부 울릉분지가 높은 것으로 추정된다.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.214-220
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• 2008

세계적인 화석연료사용의 급증으로 인해 지구온난화와 자원고갈의 문제가 크게 대두되어지고 있다. 이를 해결하기 위해 많은 국가와 연구기관이 재생 가능한 에너지로서 바이오연료의 개발과 사용에 관심을 기울이고 있다. 바이오에탄올은 자동차용 휘발유와 혼합하여 사용할 수 있는 연료로서 많은 국가에서 상용화하고 있다. 우리 연구그룹은 혼합비율에 따른 자동차용 휘발유의 품질특성시험(상분리 모사실험, 금속류 부식실험, 고무류 침지실험 등)을 한 결과 국내 최적의 혼합량(E3, E5)을 도출하였다. 이로부터 현재 전국 4개 시범주유소를 운영하면서 바이오에탄올 실증평가를 수행 중에 있다. 본 논문에서는 바이오에탄올 혼합연료유 도입을 위한 실증평가 연구를 통해 국내 바이오에탄올의 도입 활성화 가능성과 최적의 유통인프라 구축방안에 대해 논의하고자 한다.

• Tunnel and Underground Space
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• v.26 no.2
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• pp.120-130
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• 2016

Considering the applicability of Kuz-Ram model, which has been used extensively for predicting rock fragmentation size distribution by blasting, to domestic open-pit limestone mine, a total of 21 blasting tests have been executed at an open-pit limestone mine in eastern Gangwon of South Korea. A comparative analysis of field measured value and Kuz-Ram predicted value showed that there are a considerable amount of error in the predicted values regardless of application of various correction parameters for rock factor and uniformity factor; up to 56.45% in mean fragmentation size and 37.52% in uniformity index. Also the problem of applying different correction parameters has been derived even though a similar blasting pattern has been adopted for a same blasting bench. The authors therefore suggest that Kuz-Ram model needs to be modified for a proper application to domestic open-pit limestone mine.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.942-945
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• 2005

Micron-sized metal wires are widely used in industries such as filtration, catalyst and composite materials, etc. In the wire drawing process, the die that is used conventionally is an effective and, at the same time, sensitive component. However, a typical array of the dies has caused many problems in the wire drawing process, e.g., large frictional force on the interface between wire and the resulting high heat generation, precise adjustment of the dies, extended cooling system, die abrasion, etc.. Because of these problems, there have been many works that are aiming at improving the efficiency of wire drawing process by analyzing the die geometry and by applying advanced die material to prolong the die life or even at developing a dieless wire drawing system. This paper is dealing with developing a new wire drawing system that is applicable to reduce the wire drawing steps with high draw ratio. The new wire drawing system does not use the dies, but use the self-induced heater that works on the basis of the resonant phenomenon of wire material. The electromagnetic wave is the heating source. The results of the study on the diameter reduction and microwave flow analysis show that the heating effectiveness of the wire is influenced by the energy distribution in the microwave propagation chamber. We can obtain diameter-reduced wires by using microwave in the dieless drawing process. Microwave as a heating source is capable of producing wires without applying dies in wire drawing process.

• Journal of Photoscience
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• v.12 no.2
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• pp.67-73
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• 2005

Fluorescent probe techniques were used to evaluate the effect of dibucaine.HCl on the physical properties (transbilayer asymmetric lateral mobility, annular lipid fluidity and protein distribution) of synaptosomal plasma membrane vesicles (SPMV) isolated from bovine cerebral cortex. An experimental procedure was used based on selective quenching of 1,3-di(l-pyrenyl)propane (Py-3-Py) by trinitrophenyl groups, and radiationless energy transfer from the tryptophans of membrane proteins to Py-3-Py. Dibucaine.HCl increased the bulk lateral mobility, and annular lipid fluidity in SPMV lipid bilayers, and had a greater fluidizing effect on the inner monolayer than the outer monolayer. The magnitude of increasing effect on annular lipid fluidity in SPMV lipid bilayer induced by dibucaine.HCl was significantly far greater than magnitude of increasing effect of the drug on the lateral mobility of bulk SPMV lipid bilayer. It also caused membrane proteins to cluster. These effects of dibucaine.HCl on neuronal membranes may be responsible for some, though not all, of the local anesthetic actions of dibucaine.HCl.

• Korean Journal of Remote Sensing
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• v.29 no.1
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• pp.137-149
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• 2013

Solar insolation is essential to understand the interaction between the earth and solar system, and it is a significant parameter that is utilized in various research fields including earth science, agriculture, and energy engineering. Although solar insolation is broadly measured in the ground-based observation station, it is difficult to identify the spatial distribution of solar insolation accurately. The remote sensing approach is known to have several benefits because it can provide continuous data sets for large area. In this study, we conducted the validation of solar insolation from COMS in the South Korea by comparing with flux tower observation. The results showed that the correlations between COMS and observation were high in both 30 minutes interval data and daily average data. Thus, we can identify that COMS can provide a reasonable estimate of solar insolation.

• Tribology and Lubricants
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• v.32 no.2
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• pp.56-60
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• 2016

Sapphire has a high hardness and strength and chemical stability as a superior material. It is used mainly as a material for a semiconductor as well as LED. Recently, the cover glass industry used by a sapphire is getting a lot of attention. The sapphire substrate is manufactured through ingot sawing, lapping, diamond mechanical polishing (DMP) and chemical mechanical polishing (CMP) process. DMP is an important process to ensure the surface quality of several nm for CMP process as well as to determine the final form accuracy of the substrate. In DMP process, the material removal is achieved by using the mechanical energy of the relative motion to each other in the state that the diamond slurry is disposed between the sapphire substrate and the polishing platen. The polishing platen is one of the most important factors that determine the material removal characteristics in DMP. Especially, it is known that the geometric characteristics of the polishing platen affects the material removal amount and its distribution. This paper investigated the material removal characteristics and the effects of the polishing platen groove in sapphire DMP. The experiments were preliminarily carried out to evaluate the sapphire material removal characteristics according to process parameters such as pressure, relative velocity and so on. In the experiment, the monitoring apparatus was applied to analyze process phenomena in accordance with the processing conditions. From the experimental results, the correlation was analyzed among process parameters, polishing phenomena and the material removal characteristics. The material removal equation based on phenomenological factors could be derived. And the experiment was followed to investigate the effects of platen groove on material removal characteristics.

• Journal of Korean Society on Water Environment
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• v.28 no.1
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• pp.129-136
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• 2012

In this century, scientists realized that carbon dioxide gas in the atmosphere cause a greenhouse effect which affects the planet's temperature. Therefore lots of attempts have carried out to decrease the discharge of carbon dioxide gas in the field. The dissolved carbon dioxide flotation (DCF) process was developed as an alternative of DAF process to decrease the discharge and reuse of carbon dioxide as well as to save energy consumption. To investigate the particle separation characteristics and the flotation efficiency of carbon dioxide, SCC model was employed in the DCF process which has been applied extensively for the evaluation and simulation in the DAF process. The simulation results by the SCC model revealed the predicted curve of flotation efficiency became decreased gradually over the optimal pressure range of saturator about 1.6 atm in accordance with the experiment results of the DCF pilot plant and the size distribution and the bubble volume concentration of $CO_{2}$ bubbles depending on the operation pressure of saturator. The findings through the simulation results led to the conclusion that there was no significant difference between $CO_{2}$ bubbles and air bubbles, affecting on the practical flotation efficiency, in terms of the initial collision and attachment efficiency.

• Korean Journal of Materials Research
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• v.26 no.4
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• pp.167-172
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• 2016

The high temperature deformation behavior of $Ni_3Al$ and $Ni_3(Al,Mo)$ single crystals that were oriented near <112> was investigated at low strain rates in the temperature range above the flow stress peak temperature. Three types of behavior were found under the present experimental conditions. In the relatively high strain rate region, the strain rate dependence of the flow stress is small, and the deformation may be controlled by the dislocation glide mainly on the {001} slip plane in both crystals. At low strain rates, the octahedral glide is still active in $Ni_3Al$ above the peak temperature, but the active slip system in $Ni_3(Al,Mo)$ changes from octahedral glide to cube glide at the peak temperature. These results suggest that the deformation rate controlling mechanism of $Ni_3Al$ is viscous glide of dislocations by the <110>{111} slip, whereas that of $Ni_3(Al,Mo)$ is a recovery process of dislocation climb in the substructures formed by the <110>{001} slip. The results of TEM observation show that the characteristics of dislocation structures are uniform distribution in $Ni_3Al$ and subboundary formation in $Ni_3(Al,Mo)$. Activation energies for deformation in $Ni_3Al$ and $Ni_3(Al,Mo)$ were obtained in the low strain rate region. The values of the activation energy are 360 kJ/mol for $Ni_3Al$ and 300 kJ/mol for $Ni_3(Al,Mo)$.

• Korean Journal of Materials Research
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• v.26 no.12
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• pp.751-756
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• 2016

Graphite was diffusion-bonded by hot-pressing to W-25Re alloy using a Ti interlayer. For the joining, a uniaxial pressure of 25 MPa was applied at $1600^{\circ}C$ for 2 hrs in an argon atmosphere with a heating rate of $10^{\circ}C\;min^{-1}$. The interfacial microstructure and elemental distribution of the W-25Re/Ti/Graphite joints were analyzed by scanning electron microscopy (SEM). Hot-pressed joints appeared to form a stable interlayer without any micro-cracking, pores, or defects. To investigate the high-temperature stability of the W-25Re/Ti/Graphite joint, an oxy-acetylene torch test was conducted for 30 seconds with oxygen and acetylene at a 1.3:1 ratio. Cross-sectional analysis of the joint was performed to compare the thickness of the oxide layer and its chemical composition. The thickness of W-25Re changed from 250 to $20{\mu}m$. In the elemental analysis, a high fraction of rhenium was detected at the surface oxidation layer of W-25Re, while the W-25Re matrix was found to maintain the initial weight ratio. Tungsten was first reacted with oxygen at a torch temperature over $2500^{\circ}C$ to form a tungsten oxide layer on the surface of W-25Re. Then, the remaining rhenium was subsequently reacted with oxygen to form rhenium oxide. The interfacial microstructure of the Ti-containing interlayer was stable after the torch test at a temperature over $2500^{\circ}C$.