• 반도체디스플레이기술학회지
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• 제4권1호
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• pp.43-48
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• 2005

Metaloganic chemical vapor deposition, also known as metalorganic vapor phase epitaxy has become one of the main techniques for growing thin, high purity films for compound semiconductors such as GaAs, InP, and InGaAsP. In this study, the distribution of growth rate and composition of InGaAsP, InGaP, and InGaAs films are studied using computational method. The influences of process parameters such as pressure, temperature and precursors' partial pressure on the growth rate and composition distributions are analyzed. The film growth rate is increased in the upstream part according to the increase of temperature but not in the downstream part. The Ga composition in InGaAsP film shows an asymptotic behavior for temperature variation but As composition varies significantly within the temperature range considered in the present study. The overall film growth rates of InGaP, InGaAs and InGaAsP are decreased with increasing the Ga/In ratios of the source gases. Pressure variation does not seem to be a significant parameter to the film growth. Film growth characteristics of tertiary films such as InGaP and InGaAs show similar trends to the quaternary film, InGaAsP.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.382-382
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• 2012

CIGS thin films have received great attention as a promising material for solar cells due to their high absorption coefficient, appropriate bandgap, long-term stability, and low cost production. CIGS thin films are deposited by various methods such as co-evaporation, sputtering, spray pyrolysis and electro-deposition. The deposition technique is one of the most important processes in preparing CIGS thin film solar cells. Among these methods, co-evaporation is one of the best technique for obtaining high quality and stoichiometric CIGS films. However, co-evaporation method is known to be unsuitable for commercialization. The sputtering is known to be very effective and feasible process for mass production. In this study, CIGS thin films have prepared by rf magnetron sputtering using a $Cu(In_{1-x}Ga_x)Se_2$ single quaternary target without post deposition selenization. This process has been examined by the effects of deposition parameters on the structural and compositional properties of the films. In addition, we will explore the influences of substrate temperature and additional annealing treatment after deposition on the characteristics of CIGS thin films. The thickness of CIGS films will be measured by Tencor-P1 profiler. The crystalline properties and surface morphology of the films will be analyzed using X-ray diffraction and scanning electron microscopy, respectively. The optical properties of the films will be determined by UV-Visible spectroscopy. Electrical properties of the films will be measured using van der Pauw geometry and Hall effect measurement at room temperature using indium ohmic contacts.

• 대한지리학회지
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• 제39권6호
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• pp.845-862
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• 2004

본 연구는 경기, 강원 지역을 대상으로 감입곡류절단 지형의 공간적 분포 특성을 검토하였다. 강원도에서도 높은 산지지역인 정선군 및 인제군을 주로 흐르는 내린천 및 동대천 등의 하천에서 곡류절단면의 분포 밀도가 가장 높았다. 곡류절단의 발생은 제4기 동안 반복적으로 나타났으며. 빙기와 간빙기 사이의 기후 변동기에 집중된 것으로 추정된다. 지질별로는 퇴적암에서 분포 빈도가 가장 높고, 화성암에서 가장 낮았다. 지질구조로 볼 때, 태백산맥으로부터 서쪽 $11{\sim}20km$ 거리에 가장 많이 분포하며. 적종하천이나 적종하천에 유입하는 지류의 하구부, 즉 단층선에 직교하는 하천에서 곡류절단이 가장 활발하였다. 태백산맥에서의 거리와 해발고도와의 관계는 영서하천에서 매우 뚜렷하고, 하상비고 및 절단면 면적과의 관계에서는 태백산맥에서 서쪽 12km를 기준으로 동서로 갈수록 값이 작아진다. 기반암 종류에 대한 해발고도. 하상비고, 하천차수와의 관계는 공통적으로 퇴적암 지역에서 값이 가장 높으며, 화산암 지역에서 가장 낮다.

• 한국지형학회지
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• 제28권3호
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• pp.51-61
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• 2021

Following the previous study, we report a complementary dating data on the silty layers deposited in paleo-tidal conditions of the study area, Dangjeong-ri, Seocheon-gun and suggest coastal terrain development processes over the past 200,000 years. Based on the dating results, the silty layers distributed up to 25 m above mean sea level were deposited between 171 and 183 ka, and the gravel layer deposited in a fluvial environment of a paleo-Dangjeong stream was found to have formed between 78 and 83 ka. Considering relative altitudes of distribution, an uplift rate of the study area in the western coast is judged to be relatively 0.5~0.7 low to that of Pohang area in the eastern coast. Compared to Busan and Sacheon areas in the southern coast, it is assumed that an uplift rate of the study area shows a similar level with those during the late Quaternary.

• Animal Systematics, Evolution and Diversity
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• 제28권4호
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• pp.279-290
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• 2012

Plecoglossus altivelis (ayu) is an amphidromous fish widely distributed in Northeastern Asia from the East China Sea to the northern Japanese coastal waters, encompassing the Korean Peninsula within its range. The shore lines of northeastern region in Asia have severely fluctuated following glaciations in the Quaternary. In the present study, we investigate the population genetic structure and historical demographic change of P. altivelis at a population level in East Asia. Analysis of molecular variance (AMOVA) based on 244 mitochondrial control region DNA sequences clearly showed that as the sampling scope extended to a larger geographic area, genetic differentiation began to become significant, particularly among Northeastern populations. A series of hierarchical AMOVA could detect the genetic relationship of three closely located islands between Korea and Japan that might have been tightly connected by the regional Tsushima current. Neutrality and mismatch distribution analyses revealed a strong signature of a recent population expansion of P. altivelis in East Asia, estimated at 126 to 391 thousand years ago during the late Pleistocene. Therefore it suggests that the present population of P. altivelis traces back to its approximate demographic change long before the last glacial maximum. This contrasts our a priori expectation that the most recent glacial event might have the most crucial effect on the present day demography of marine organisms through bottleneck and subsequent increase of effective population size in this region.

• 한국표면공학회지
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• 제45권6호
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• pp.232-241
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• 2012

Cr-Ti-B-N coatings were synthesized by a hybrid coating system combining high power impulse magnetron sputtering (HIPIMS) and DC pulse magnetron sputtering from a $TiB_2$ and a Cr target in argon-nitrogen environment, respectively. By changing the power applied on the Cr and $TiB_2$ cathodes, the Cr-Ti-B-N coatings with various Ti/Cr ratio and B content were deposited. The phase structure, microstructure and chemical compositions of the Cr-Ti-B-N coatings were studied by X-ray diffraction (XRD), transmission scanning electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). With increase of Cr element in the coatings, the nanocomposite microstructure consisting of nano-sized (Cr, Ti) N crystallites and amorphous BN phase were obtained in the coatings. The microhardness of the Cr-Ti-B-N coatings exhibited a peak value of ~41 GPa for the $CrTi_{0.1}B_{0.4}N_{1.3}$, and then decreased with further increase of Cr content in the coatings, and all the coatings exhibited low friction coefficient. The oxidation and corrosion behavior of the Cr-Ti-B-N coatings revealed better properties due to the formation of a nanocomposite microstructure.

• 자원환경지질
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• 제18권3호
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• pp.239-246
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• 1985

Uranium-thorium separation technique from shallow sediment and ${\alpha}$-source electrodeposition technique are established in the present work, and uranium series disequilibrium dating method is applied to the quaternary piston core from Sangback-do, South Sea of Korean Peninsula. The age of the piston core (depth 200~300cm) sampled from Latitude $34^{\circ}06^{\prime}37^{{\prime}{\prime}}$, Longitude $127^{\circ}37^{\prime}37^{{\prime}{\prime}}$ was determined as ranging from $9.0{\pm}2.2$ to $22.9{\pm}3.3$ Ky B.P, i.e., Later Pleistocene, older than Holocene which was stratigraphically known in the previous study. The sedimentation rate in the area is regularly increased according to the depth of the sedimentation layer. Except a few split sections of the piston core the sedimentation rates are avarage 7.2cm/1,000 years. Where sedimentation layer is deeper, then sedimentation rate tend to be slower. It must be pointed in age calculation that initial $^{230}Th/^{234}U$ radioactivity ratio is much influenced when detrital material was introduced in the sample. The $^{230}Th/^{234}U$ activity ratio measured in the present work is 0.06 at $^{232}Th=0$, and this value shows higher analytical errors because of the low· radioactivity of $^{230}Th$ in the samples.

• 한국재료학회지
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• 제31권5호
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• pp.296-300
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• 2021

Al-Cr-Si ternary quench ribbons are fabricated using a single roll method and investigated for their structural and thermal properties. In particular, the sinterability is examined by pulse current sintering to obtain the following results. The Al₇₄Cr₂₀Si₆ composition becomes a quasicrystalline single phase; by reducing the amount of Cr, it becomes a two-phase mixed structure of Al phase and quasicrystalline phase. As a result of sintering of Al₇₄Cr₂₀Si₆, Al₇₇Cr₁₃Si₁₀ and Al₉₀Cr₆Si₄ compositions, the sintering density is increased with the large amount of Al phase; the sintering density is the highest in Al₉₀Cr₆Si₄ composition. In addition, as a result of investigating the effects of sintering temperature and pressurization on the sintered density of Al₉₀Cr₆Si₄, a sintered compact of 99% or more at 513 K and 500 MPa is produced. In particular, since the Al-Cr-Si ternary crystal is more thermally stable than the Al-Cr binary quaternary crystal, it is possible to increase the sintering temperature by about 100 K. Therefore, using an alloy of Al₉₀Cr₆Si₄ composition, a sintered compact having a sintered density of 99 % or more at 613 K and 250 MPa can be manufactured. It is possible to increase the sintering temperature by using the alloy system as a ternary system. As a result, it is possible to produce a sintered body with higher density than that possible using the binary system, and at half the pressure compared with the conventional Al-Cr binary system.

• 암석학회지
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• 제24권4호
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• pp.307-321
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• 2015

미얀마 북서부 깔레이 시 근처에 보피붐 크롬 광화대가 발달하고 있다. 이 지역에는 크롬광체를 포함하는 백악기의 초염기성암이 서쪽의 제3기 퇴적층을 드러스트 하고 있다. 크롬광체는 초염기성암인 듀나이트와 하즈버자이트 내에 발달하며, 주로 듀나이트 암체 내에 배태되어져 있다. 듀나이트와 크롬광체의 분포방향은 북서-남동 방향이며, 이 지역의 일반적인 지구조 방향인 남-북 방향과는 사교하는 특성을 보이고 있다. 광체의 연장과 발달특성을 파악하기 위해 5개소에서 트렌치조사를 실시하였다. 트렌치에서 관찰되는 크롬광체와 주변의 듀나이트, 하즈버자이트는 심한 연성변형을 보인다. 광체는 m 규모 내외의 폭과 수 m 규모 내외의 연장성을 보이며, 시그모이드나 렌즈상으로 부딘화되어져 있다. 연성변형의 특징은 상부가 동에서 서로 이동한 전단감각을 보이고 있어, 지역 규모의 드러스트 존재와 부합하고 있다. 광체가 북서-남동 방향의 배열을 보이는 것은 남-북 방향을 따른 우향의 주향이동에 의한 S자 모양의 전단구조에 의한 것, 서가형전단에 따른 지괴의 회전에 기인한 것, 또는 이들이 복합적으로 중첩된 결과로 해석된다.

• 자원환경지질
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• 제19권spc호
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• pp.73-94
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• 1986

필자(筆者)는 1981년(年) 파리, 1983년(年) 마닐라에서 개최되었던 CGMW 회의(會議)에 참석(參席)함을 계기로 세계공통(世界共通)의 제작규약(製作規約)을 준수(遵守)해 가면서 대한지질도(大韓地質圖) 및 한국의 지체구조도(地體構造圖)를 기본도(基本圖)로 하여 그간의 광상조사연구자료중(鑛床調査硏究資料中) 444개(個) 주요대상광상(主要對象鑛床)을 선정(選定), 이들 자료(資料)를 정리종합(整理綜合) 분류(分類)하여 1983년(年)에 한국의 광상생성도(鑛床生成圖)를 발간(發刊)(한국동력자원연구소(韓國動力資源硏究所))한 바 있다. 처음 시도(試圖)된 일이었을 뿐 아니라 대상개개(對象個個) 광상(鑛床)의 정밀조사자료(精密調査資料)가 부족(不足)하여 흡족(洽足)하지 못하였음에 차후(次後) 보다 보완(補完)된 충실(充實)한 내용(內容)의 광상생성도(鑛床生成圖)를 기대(期待)하여 마지 않는다.