• 한국지반신소재학회논문집
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• 제14권4호
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• pp.129-137
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• 2015

최근 해상풍력발전 단지 조성은 많은 양의 에너지를 창출할 수 있어 그 기대는 점차적으로 증가하고 있다. 특히 제주도는 풍황이 우수하여 해상풍력발전 시스템 운영을 위한 최적의 대상지이기는 하나, 화산활동에 의해 형성된 지형으로 육지부와 달리 현무암층 사이에 연약층인 화산쇄설물 및 공동이 불규칙하게 발달된 층상구조로 이루어져 있다. 이에 본 연구에서는 프레셔미터 시험으로부터 제주 현무암에 근입된 수평재하말뚝의 p-y 곡선을 유도하기 위하여 프랑스석유협회(IFP, 1983)과 Briaud et al.(1983)의 방법을 이용하였다. 이들의 방법을 이용하여 유도된 p-y 곡선을 LPILE 프로그램에 입력하여 말뚝두부에서 하중-변위 관계를 분석한 후 재하시험으로 측정된 하중-변위 곡선과 비교하였다. 결과, pressuremeter test로부터 제주 현무암에 근입된 수평재하말뚝의 p-y 곡선을 유도할 때 IFP 방법은 매우 합리적인 결과를 도출할 수 있을 것으로 판단된다.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2009년도 추계학술발표대회
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• pp.30.1-30.1
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• 2009

정보화가 급속히 진전됨에 따라 보다 많은 양의 정보를 전송, 처리, 저장하게 되면서 이를 위해 대용량, 고속, 비휘발성의 특징을 갖는 차세대 메모리의 개발이 절실히 요구되고있다. 이 중 저항 변화 메모리(ReRAM)는 일반적으로 TiO2, Al2O3, NiO2, HfO2, ZrO2 등의 전이금속산화물을 이용한 MIM 구조로서 적당한 전기 신호를 가하면 저항이 높아서 전도되지 않는 상태(Offstate)에서 저항이 낮아져 전도가 가능한 상태(On state)로 바뀌는 메모리 특성을가진다. ReRAM은 비휘발성 메모리이며 종래의 비휘발성 기억소자인 Flash memory 보다 access time 이105 배 이상 빠르고, 5V 이하의 낮은 전압에서도 동작이 가능하다. 또한 구조가 간단하여 공정 단순화가 가능하고 소자의 집적화도 쉽다는 점 등 많은 장점들이 있어서 Flash memory를 대체할 수 있는 유력한 후보로 여겨지고 있다. 본연구에서는 DC-magnetron Sputtering 방법으로 전이금속 박막을 증착하고, Dry furnace로 산화시켜 전이금속산화물 박막을 제작한 후 저항변화 특성을 연구하였다. 두 개의 전이금속산화물 박막을 dual-layer로 형성시켜 저항변화특성을 관찰하였으며 또한, 전이금속산화물 박막의 조성을 달리 하여 저항변화를 관찰 하였다. 전이금속산화물 박막의 전기적 특성을 알아보기 위해 Si(100) wafer 위에 Pt를 이용 MIM 형태로 capacitor 시편을 제작 하여, probe station으로 I-V 측정을 하였고 조성 및 표면 분석을 위해서는 AES와 AFM을, 미세구조를 분석을 위해서는 TEM과 SEM 을 사용하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.104-104
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• 2009

Critical dimensions has rapidly shrunk to increase the degree of integration and to reduce the power consumption. However, it is accompanied with several problems like direct tunneling through the gate insulator layer and the low conductivity characteristic of poly-silicon. To cover these faults, the 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-silicon gate is not compatible with high-k materials for gate-insulator. To integrate high-k gate dielectric materials in nano-scale devices, metal gate electrodes are expected to be used in the future. Currently, metal gate electrode materials like TiN, TaN, and WN are being widely studied for next-generation nano-scale devices. The TaN gate electrode for metal/high-k gate stack is compatible with high-k materials. According to this trend, the study about dry etching technology of the TaN film is needed. In this study, we investigated the etch mechanism of the TaN thin film in an inductively coupled plasma (ICP) system with $O_2/BCl_3/Ar$ gas chemistry. The etch rates and selectivities of TaN thin films were investigated in terms of the gas mixing ratio, the RF power, the DC-bias voltage, and the process pressure. The characteristics of the plasma were estimated using optical emission spectroscopy (OES). The surface reactions after etching were investigated using X-ray photoelectron spectroscopy (XPS) and auger electron spectroscopy (AES).

• 한국전자파학회논문지
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• 제14권5호
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• pp.536-541
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• 2003

본 논문에서는 다이아몬드 표면에의 산소흡착을 억제함으로써 양호한 전기적특성을 가지는 다이아몬드 MISFET를 제작하기 위해 초고진공 프로세스(ultrahigh vacuum process)에 의해 A1/Ca $F_2$/diamond MISFET를 제작하였다. 박막반도체 다이아몬드의 표면도전층으로서는 불소종단에 의해 형성되는 표면 도전층을 이용하였다. 초고진공 프로세스에 의해 제작된 A1/Ca $F_2$/diamond MISFET로부터 상용화된 실리콘 MOSFET와 동등한 레벨인~$10^{11}$ /$cm^2$ eV의 저농도의 표면준위밀도가 관측되었고, 유효이동도 $\mu$ $e_{ff}$ 는 이제까지 발표된 박막반도체 다이아몬드 FET중 최고치인 300 $cm^2$/Vs 이었다. 본 논문에서는 또한 초고진공 프로세스에 의해 제작된 Al/Ca $F_2$/diamond MISFET를 이용하여 인버터회로(inverter circuit)를 제작하였으며, 고온고주파 환경에서 양호한 전기적 특성을 관찰하였다. 본 논문의 특징은 초고진공 프로세스에 의해 제작된 불소화 다이아몬드 박막반도체 MISFET에 관한 최초의 보고이며, 또한 다이아몬드 박막반도체 MISFET의 인버터회로(inverter circuit)동작에 관한 최초의 보고이다.다.

• Journal of Mechanical Science and Technology
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• 제15권5호
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• pp.630-638
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• 2001

The electrical resistivity of sinter dusts generated from the steel industry and coal fly ash from the coal power plant has been investigated using the high voltage conductivity cell based on JIS B 9915 as a function of temperature and water content. Dust characterization such as the chemical composition, size distribution, atomic concentration, and surface structure has been conducted. Major constituents of sinter dusts were Fe$_2$O$_3$(40∼74.5%), CaO (6.4∼8.2%), SiO$_2$(4.1∼6.0%), and unburned carbon (7.0∼14.7%), while the coal fly ash consisted of mainly SiO$_2$(51.4%), Al$_2$O$_3$(24.1%), and Fe$_2$O$_3$(10.5%). Size distributions of the sinter dusts were bi-modal in shape and the mass median diameters (MMD) were in the range of 24.7∼137㎛, whereas the coal fly ash also displayed bi-modal distribution and the MMD of the coal fly ash was 35.71㎛. Factors affecting resistivity of dusts were chemical composition, moisture content, particle size, gas temperature, and surface structure of dust. The resistivity of sinter dusts was so high as 10(sup)15 ohm$.$cm at 150$\^{C}$ that sinter dust would not precipitate well. The resistivity of the coal fly ash was measured 1012 ohm$.$cm at about 150$\^{C}$. Increased water contents of the ambient air lowered the dust resistivity because current conduction was more activated for absorption of water vapor on the surface layer of the dust.

• 열처리공학회지
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• 제12권1호
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• pp.31-39
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• 1999

In the present study, oxidation behavior of 304 and 316 stainless steels was investigated. After solution treatment, specimens were polished up to $1{\mu}m$ $Al_2O_3$ grade and then subjected to oxidation treatment in dry air. The range of temperature was used for oxidation treatment at $300^{\circ}C{\sim}500^{\circ}C$ and TEM was used for analyzing the components and structure of oxide film. Also, these results were compared with the results of ESCA and TG. According to the results of TEM analysis, it was found that Cr oxide film was formed on top of the surface after room temperature oxidation but amorphous Fe oxide was formed on top of the surface and polycrystalline $(Cr,Fe)_2O_3$ was formed below the amorphous Fe oxide layer after $500^{\circ}C$ oxidation treatment. The oxidized specimens at $500^{\circ}C$ showed that 316 stainless steel resists more strongly to grain and grain boundary oxidation than 304 stainless steel. These results suggested that Mo component resolved in 316 stainless steel matrix suppressed the formation of Cr carbide which may results in local Cr deplete area.

• Journal of Biosystems Engineering
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• 제34권5호
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• pp.351-357
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• 2009

This study was conducted to verify the simulation model through the drying test, and investigate effect of factors, such as temperature of drying air, airflow rate, and velocity of the airflow, on the drying. The low temperature drying simulation model was developed based on the circulation dry simulation model presented by Keum et al. (1987), and by modifying low temperature thin layer drying model, equilibrium moisture content model, latent heat of vaporization model, and crack ratio prediction model. The heat pump and experimental dryer with a capacity of 150kg were used for the test. The RMSE between the predicted and measured value was 0.27% (drying temperature), 0.15% (crack ratio), and 2.08% (relative humidity), so the relevance of the model was verified. In addition, the effect of drying temperature, airflow rate, and velocity of the airflow on the drying was examined. The experimental results showed that the crack ratio at drying temperature of $25{\sim}40^{\circ}C$ was allowable. Moreover, at below $30^{\circ}C$, variation of the crack ratio was slight, but drying time was delayed. Given these results, the drying temperature of over $30^{\circ}C$ was effective. As the airflow rate increased, required energy dramatically increased. Whereas drying rate slowly increased, so loss of drying efficiency was caused. Considering these results, the dryer needed to be designed and adjusted to lower than $30\;m^3/min{\cdot}ton$. As velocity of the airflow increased, required drying energy increased when the velocity of the airflow was over $5\;m^3$/hr, while crack ratio and drying rate showed little variation.

• 한국구조물진단유지관리공학회 논문집
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• 제8권2호
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• pp.123-136
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• 2004

Terzaghi의 1차원 압밀이론은 그 유도과정에 있어 몇 가지 중요한 가정사항을 내포하고 있으며, 이로인해 이 이론을 연약 점토지반의 압밀거동에 적용하는데는 많은 모순이 발생할 수 밖에 없다. 특히, 미소변형 및 선형 물질함수에 대한 가정은 실제 현장의 압밀현상과 비교할 때 많은 오류를 발생시키는 원인으로 작용한다. 이러한 이유에서, Gibson 등은 물질함수의 비선형성을 고려할 수 있는 1차원 비선형 유한변형률 압밀이론에 대한 엄밀해를 발표하였다. 그러나, 이 이론은 연직배수공법이 적용된 일반적인 연약 점토지반의 압밀현상에는 적용시킬 수 없다는 단점을 내포하고 있다. 본 연구에서는 포화된 지반의 수직 및 수평방향 배수를 고려하며 지반의 자중 및 투수성과 압축성에 대한 물질함수의 비선형적 특성을 반영할 수 있는 압밀모델을 제안하였다. 또한 제안된 모델을 실제 압밀현상에 적용하기 위한 수치해석 기법을 개발하였다. 수치해석에 이용된 물질함수의 특성은 표준압밀 시험 및 로우셀 시험, 개량 표준압밀 시험등을 이용하여 산정되었다.

• 한국재료학회지
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• 제20권11호
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• pp.600-605
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• 2010

In order to meet the requirements of faster speed and higher packing density for devices in the field of semiconductor manufacturing, the development of Cu/Low k device material is explored for use in multi-layer interconnection. SiOC(-H) thin films containing alkylgroup are considered the most promising among all the other low k candidate materials for Cu interconnection, which materials are intended to replace conventional Al wiring. Their promising character is due to their thermal and mechanical properties, which are superior to those of organic materials such as porous $SiO_2$, SiOF, polyimides, and poly (arylene ether). SiOC(-H) thin films containing alkylgroup are generally prepared by PECVD method using trimethoxysilane as precursor. Nano voids in the film originating from the sterichindrance of alkylgroup lower the dielectric constant of the film. In this study, methyltriphenylsilane containing bulky substitute was prepared and characterized by using NMR, single-crystal X-ray, GC-MS, GPC, FT-IR and TGA analyses. Solid-state NMR is utilized to investigate the insoluble samples and the chemical shift of $^{29}Si$. X-ray single crystal results confirm that methyltriphenylsilane is composed of one Si molecule, three phenyl rings and one methyl molecule. When methyltriphenylsilane decomposes, it produces radicals such as phenyl, diphenyl, phenylsilane, diphenylsilane, triphenylsilane, etc. From the analytical data, methyltriphenylsilane was found to be very efficient as a CVD or PECVD precursor.

• Nuclear Engineering and Technology
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• 제31권2호
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• pp.182-191
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• 1999

The sorption of UO$_{2}$$^{2+}$ onto goethite and kaolinite under various experimental conditions was successfully interpreted using surface complexation modeling (SCM). The SCM approach used in this work is the triple-layer model (TLM) in which weakly bonded ions are modeled as outer-sphere (ion-pair) complexes and strongly bonded ions as inner-sphere (surface coordination) complexes. The change of ionic strength did not affect the U(VI) sorption onto goethite, thus the formation of inner-sphere surface complexes, (FeO)$_2$UO$_2$ and (FeO)$_2$(UO$_2$)$_3$OH$_{5}$ was assumed to simulate the effects of ionic strength and goethite concentration. On the other hand, the U(VI) sorption onto kaolinite showed ionic strength dependence, thus the formation of AlO-UO$_{2}$$^{2+}$(outer-sphere complex) and SiO(UO$_2$)$_3$OH$_{5}$ (inner-sphere complex) was assumed to simulate the experimental data. In the presence of carbonates, the sorption of U(VI) onto kaolinite decreased in the weakly alkaline pH range. This was well simulated assuming the formation of a outer-sphere surface complex, A1OH$^{2+}$- (UO$_2$)$_2$CO$_3$OH$_3$. Since SCM approach uses thermodynamic data such as surface complexation constants, it is more predictive than empirical modeling approach in which conditional values such as partition coefficient are used. used.