• Journal of the Mineralogical Society of Korea
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• v.28 no.1
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• pp.51-60
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• 2015

We applied gemological analytical approaches on Aquamarine from the Gilgit-Baltistan of Northern Areas, Pakistan. The standard gemological testing indicates that they are consistent with general characteristics of natural aquamarines. We have identified the inclusions of Tantalite-Mn by Raman analysis. It indicates that they occurs in association with the veins of Be-rich coarse pegmatite. And the results of chemical analyses, infrared absorption spectroscopy and Raman spectroscopy indicate that $H_2O$ molecules in channel mostly exist in Type-I and a little Type-II with low alkali ion. The comparison of relative peak intensity of FT-IR analysis can be used for prediction of $Na_2O$ content within not only emerald but also aquamarine.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.25 no.2
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• pp.56-61
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• 2015

The effects of the growth temperature on the properties of a-plane GaN epi-layer on r-plane sapphire by HVPE were studied, when the constant V/III ratio and the flow rate of HCl for the Ga source channel was fixed at 10 and 700 sccm, respectively. Additionally the effects of V/III ratios for source gasses were studied when growth temperature and the flow rate of HCl for the Ga source channel was fixed at $1000^{\circ}C$ and 700 sccm, respectively. As the growth temperature was increased, the values of Full Width Half Maximum (FWHM) for Rocking curve (RC) of a-plane GaN (11-20) epi-layer were decreased and thickness of a-plane GaN epi-layer were increased. As V/III ratios were increased at $1000^{\circ}C$, the values of FWHM for RC of a-plane GaN (11-20) were declined and thickness of a-plane GaN epi-layer were increased. The a-plane GaN (11-20) epi-layer grown at $1000^{\circ}C$ and V/III ratio = 10 showed the lowest value FWHM for RC of a-plane GaN (11-20) for 734 arcsec and the smallest dependence of Azimuth angle for FWHM of (11-20) RCs.

• Journal of Arbitration Studies
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• v.18 no.2
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• pp.201-233
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• 2008

러시아와 한국간의 공식적인 접촉은 1990년 6월 샌프란시스코에서 개최된 정상회담이다. 동년 9월 뉴욕에서 개최된 양국의 외무장관 회담에서 러시아와 한국의 외교관계가 수립되었다. 그간 양국간에는 협정을 통한 협력의 법적기반이 조성되었는데 주요 분야를 보면 무역, 투자보장, 어업, 이중과세방지, 군사기술분야, 원자력의 평화적 이용, 문화교류에 관한 협정들이 있다. 역시 양국간의 주요 관심사항은 무역과 경제협력 분야이다. 2007년도 러시아와 한국의 무역액은 150억 달러를 초과함으로써 전년도에 비해 55.5% 증가하였다. 러시아의 한국으로의 수출은 약 70억 달러로서 전년도에 비해 52.6% 증가했고 한국으로부터의 수입은 80억 달러를 초과함으로써 전년도에 비해 56.1% 증가하였다. 그리하여 러시아는 한국의 10대 교역국으로 성장하였다. 가스와 오일 프로젝트 추진과 관련하여 사할린지역에서 사용하기 위해 한국으로부터 수입하는 드릴기계장비, 탱커, 자동차, 휴대전화는 한국과 러시아 양국간 경제성장의 주요요인이 되고 있다. 2008년 1/4 분기 양국간 무역액은 42억 달러를 초과했는데 이는 전년도 동기와 비교해서 72.1% 증가한 것이다. 이 중 한국에의 수출은 17억 달러를 초과했는데 이는 전년도 1/4분기에 비해 91.7% 성장한 것이다. 한국으로부터의 수입은 약 25억 달러로서 전년도 1/4 분기와 대비해서 60.6% 성장했다. 러시아와 한국간의 경제교류가 크게 증대하게 된 배경에는 러-한경제과학기술협력공동위원회가 큰 역할을 담당했다. 이 논문에서 필자는 무역과 투자측면에서 본 양국간 경제협력의 특징을 고찰하는 한편 러시아의 동부지역(러시아 극동 및 바이칼횡단지역)과 한국과의 협력과 관련된 역동성과 과제를 제시하는데 연구의 목적을 두었다. 한국은 외국기업과 함께 러시아 극동지역의 무역과 경제협력 증진에 상당한 공헌을 함으로써 러시아 극동경제권에서 주요 무역파트너가 되고 있다. 또한 본 연구에서는 한국과 러시아간의 주요 협력프로젝트에 관하여 고찰하는 한편 앞으로의 전망을 제시하였다. 이 문제는 무엇보다도 한-러간의 공동 에너지프로젝트 및 에너지자원의 무역과 관련되어 있다. 한국과 러시아는 이미 많은 분야에서 상당한 정도로 상호 협력관계를 발전시켜왔다. 여기에는 정책, 에너지, 경제, 문화, 과학기술 분야가 포함되어 있다. 현재 러시아와 한국간에는 에너지 분야에서의 전략적 대화채널 구축에 관한 문제와 함께 연료 및 에너지공단 건설과 관련하여 협력문제가 논의되고 있다. 에너지 분야에서의 전략적 대화개념 구축을 위해서는 전략, 예측 및 투자환경의 문제가 양국간에 집중논의 되어야 하고 법제상의 조화문제도 논의되어야 한다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.6
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• pp.709-714
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• 2018

This study researched the reasons for changing polarity in accordance with junction properties in an interface of semiconductors. The contact properties of semiconductors are related to the effect of the semiconductor's device. Therefore, it is an important factor for understanding the junction characteristics in the semiconductor to increase the efficiency of devices. For generation of various junction properties, carbon-doped silicon oxide (SiOC) was deposited with various argon (Ar) gas flow rates, and the characteristics of the SiOC was varied based on the polarity in accordance with the Ar gas flows. Tin-doped zinc oxide (ZTO) as the conductor was deposited on the SiOC as an insulator to research the conductivity. The properties of the SiOC were determined from the formation of a depletion layer by the ionization reaction with various Ar gas flow rates due to the plasma energy. Schottky contact was good in the condition of the depletion layer, with a high potential barrier between the silicon (Si) wafer and the SiOC. The rate of ionization reactions increased when increasing the Ar gas flow rate, and then the potential barrier of the depletion layer was also increased owing to deficient ions from electron-hole recombination at the junction. The dielectric properties of the depletion layer changed to the properties of an insulator, which is favorable for Schottky contact. When the ZTO was deposited on the SiOC with Schottky contact, the stability of the ZTO was improved by the ionic recombination at the interface between the SiOC and the ZTO. The conductivity of ZTO/SiOC was also increased on SiOC film with ideal Schottky contact, in spite of the decreasing charge carriers. It increases the demand on the Schottky contact to improve the thin semiconductor device, and this study confirmed a high-performance device owing to Schottky contact in a low current system. Finally, the amount of current increased in the device owing to ideal Schottky contact.

• Geophysics and Geophysical Exploration
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• v.17 no.2
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• pp.74-87
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• 2014

Analysis of multi-channel seismic reflection profiles collected from the Ulleung Basin reveals that the Quaternary sequence consists of four stratigraphic units separated by erosional unconformities. Individual stratigraphic unit includes eighteen mass transport deposits which are variable in geometric characteristics and spatial distribution. Each mass transport deposit on the seismic profile is acoustically characterized by chaotic or transparent seismic facies, and shows wedge or lens-shaped external geometry. The mass transport deposits, which comprise a succession of stacked wedges, mainly occur on the southern slope, and their thickness gradually decreases toward the basin plain. The time structure map of erosional unconformities shows that a tectonic-induced structural high and troughs toward the northwest and northeast are developed at the central part of the basin. Based on the isochron map, the mass transport deposits, originated from southern part of the study area, transported to the basin plain and can be divided into two groups by the structural high. Consequently, the mass transport deposits within the Quaternary sequence in the Ulleung Basin are largely controlled by the large amounts of sediment supply, dissociation of gas hydrate during the lowstands, and central structural high.

• KEPCO Journal on Electric Power and Energy
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• v.1 no.1
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• pp.169-174
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• 2015

In this research, pristine graphene was synthesized using methane ($CH_4$) gas, and N-doped graphene was synthesized using pyridine ($C_5H_5N$) liquid source by chemical vapor deposition (CVD) method. Basic optical properties of both pristine and N-doped graphene were investigated by Raman spectroscopy and XPS (X-ray photoemission spectroscopy), and electrical transport characteristics were estimated by current-voltage response of graphene channel as a function of gate voltages. Results for CVD grown pristine graphene from methane gas show that G-peak, 2D-peak and C1s-peak in Raman spectra and XPS. Charge neutral point (CNP; Dirac-point) appeared at about +4 V gate bias in electrical characterization. In the case of pyridine based CVD grown N-doped graphene, D-peak, G-peak, weak 2D-peak were observed in Raman spectra and C1s-peak and slight N1s-peak in XPS. CNP appeared at -96 V gate bias in electrical characterization. These result show successful control of the property of graphene artificially synthesized by CVD method.

• Membrane Journal
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• v.31 no.3
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• pp.212-218
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• 2021

It is inevitable to generate incomplete combustion gases when mankind utilizes fossil fuels. From this point of view, gas separation process of combustion gas suggests the possibility of recycling CO gas. In this study, we fabricated a facilitated transport polymeric composite membrane for CO separation using AgBF₄ and HBF₄. The copolymer was synthesized via free-radical polymerization of poly(vinyl alcohol) (PVA) as a main chain and acrylic acid (AA) monomer as a side chain. The polymer synthesis was confirmed by FT-IR and the interactions of graft copolymer with AgBF₄, and HBF₄ were characterized by TEM. PVA-g-PAA graft copolymer membranes showed good channels for facilitated CO transport. In this perspective, we suggest the novel approach in CO separation membrane area via combination of grafting and facilitated transport.

• Journal of the Microelectronics and Packaging Society
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• v.31 no.1
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• pp.43-48
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• 2024

The discovery of a two-dimensional electron gas (2DEG) at the interface of LaAlO₃ (LAO) and SrTiO₃ (STO) substrates has sparked significant interest, providing a foundation for cutting-edge research in electronic devices based on complex oxide heterostructures. However, conventional methods for producing LAO thin films, typically employing techniques like pulsed laser deposition (PLD) within physical vapor deposition (PVD), are associated with high costs and challenges in precisely controlling the La and Al composition within LAO. In this study, we adopted a cost-effective alternative approach-solution-based processing-to fabricate LAO thin films and investigated their electrical properties. By adjusting the concentration of the precursor solution, we varied the thickness of LAO films from 2 to 65 nm and determined the sheet resistance and carrier density for each thickness. After vacuum annealing, the sheet resistance of the conductive channel ranged from 0.015 to 0.020 Ω·s^-1, indicating that electron conduction occurs not only at the LAO/STO interface but also into the STO bulk region, consistent with previous studies. These findings demonstrate the successful formation and control of 2DEG through solution-based processing, offering the potential to reduce process costs and broaden the scope of applications in electronic device manufacturing.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.10
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• pp.23-28
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• 2010

In this paper, we investigated the polarization effects on the electrical and structural characteristics of AlGaN/GaN HEMT. Both the Al mole-fraction and the barrier thickness of AlGaN, which determine the profiles of a two-dimensional electron gas, were simulated to obtain the optimum HEMT structure affecting the polarization effect. As a results, we found that the amount of bound sheet charges was increased by 16% and the maximum drain current density ($I_D$,max) was increased by more than 37%, while AI mole fractions are changed from 0.3 to 0.4. We also observed a 37% improvement in maximum drain current density ($I_D$,max) by increasing AIGaN layer thickness from 17 to 38 nm. However when AlGaN layer thickness reached the critical thickness, DC characteristics were dramatically lowered due to 'bulk' relaxation in AlGaN layer.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• v.y2005m4
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• pp.299-304
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• 2005

The design procedures of full-scale combustion chamber with chamber pressure of 53bara, mass flow rate of 90kg/s, combustion efficiency of $94\%$ and specific impulse at ground of 253sec were described. The details of combustion performance and geometrical parameters were also given. Full-scale combustion chamber consists of the combustor head with injector/baffle and the chamber/nozzle with regenerative cooling channels. The design results of combustion chamber with ablative materials, detachable injector head with SUS baffle or baffle injector and chamber body for ground hot firing tests were given in this paper.