• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.244.2-244.2
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• 2014

금속, 플라스틱, 유리 등의 재료 표면에 다양한 색상을 표현하기 위해 일반적으로 습식 도금을 많이 적용하고 있다. 하지만 습식 도금은 공정 수가 많을 뿐만 아니라 위험물질 및 오염물질을 많이 사용하기 때문에 산업사고, 환경오염 등을 야기 시킨다. 따라서 본 연구에서는 친환경적 방법인 물리적기상증착(PVD ; Physical Vapor Deposition) 방식의 한 종류인 스퍼터링(Sputtering)으로 색상을 구현하였다. PVD 방식의 증착은 습식 도금 방식에 비해 친환경적이며, 전처리에서 후처리까지 한 공정으로 가능하다는 점이다. 스퍼터링은 PVD의 다른 방식인 E-beam 방식에 비해 대량생산을 할 수 있다는 장점이 있다. 양산형 스퍼터링 장비(${\Phi}1200mm{\times}H1400mm$)로 실험을 진행하였으며, 증착 물질은 Ti, Al, Cr 을 사용하였고, 반응성 가스(Reactive Gas) 로는 N2, C2H2 가스를 사용하였다. 전처리는 LIS (Linear Ion Source)로 식각(Etching) 하였고, 펄스직류전원공급장치(Pulsed DC Power Supply)를 사용하여 증착 하였으며, 증착시 기판에 bias (-100 V)를 인가 하였다. 그 결과 회색계열, 갈색계열 등 여러가지 색을 구현할 수 있었으며, 증착된 박막의 특성을 알아보기 위하여 색차계, 내마모 시험기, 연필경도 시험기를 사용하였다. 향후 후처리 공정으로 내지문(AF ; anti fingerprint coating) 박막 등과 같은 실용적인 박막을 증착할 계획이다.

• Transactions on Electrical and Electronic Materials
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• 제1권1호
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• pp.40-44
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• 2000

Metal-ferroelectric-insulator-semoiconductor field effect transistor (MFISFETs) were fabricated using CMOS processes. The Pt/SBT/NO combined layers were etched for forming a conformal gate by using Ti/Cr metal masks and a two step etching method, By the method, we were able to fabricate a small-sized gate with the dimension of $16/4{\mu}textrm{m}$ in the width/length of gate. It has been chosen the non-self aligned source and drain implantation process, We have deposited inter-layer dielectrics(ILD) by low pressure chemical vapor deposition(LPCVD) at $380^{circ}C$ after etching the gate structure and the threshold voltage of p-channel MFISFETs were about 1.0 and -2.1V, respectively. It was also observed that the current difference between the $I_{ON}$(on current) and $I_{OFF}$(off current) that is very important in sensing margin, is more that 100 times in $I_{D}-V_{G}$ hysteresis curve.

• 한국전기전자재료학회논문지
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• 제25권12호
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• pp.943-948
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• 2012

A new water energy harvester module, which is composed of piezoelectric bimorph cantilevers, harvesting circuit and a shaft with 16 impellers at a center axis, was fabricated for energy harvesting application. High energy density $Pb(Zr_{0.54}Ti_{0.46})O_3$ + 0.2 wt% $Cr_2O_3$ + 1.0 wt% $Nb_2O_5$ (PZT-CN) thick film obtained by tape casting method was used for the bimorph cantilever. The PZT-CN bimorph cantilever with a proof mass of 49 g exhibited extremely high output power of 22.5 mW (24 $mW//cm^3$) at resonance frequency of 11 Hz. In addition, the fabricated water energy harvester has a cylindrical structure with 48 bimorph cantilevers clamped at inner surface. A significantly high output power of 433 mW was obtained at a rotation speed of 120 rpm with a resistive load of $500{\Omega}$ for the water energy harvester.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.327-328
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• 2006

본 연구에서는 0-3 타입의 압전 세라믹 - 고분자 복합소재를 제조하기 위해서 $Pb(Zr_{0.54}Ti_{0.48})O_3$ + 0.2 wt% $Cr_2O_3$ + 1 wt% $Nb_2O_5$ 조성을 기본 조성으로 하여, 세라믹-고분자 첨가량에 따른 복합소재의 전기적 특성과 여러 분극조건, 즉 분극온도, 분극시간, 분극전압 변화에 의한 압전 특성을 고찰하였다. 세라믹 첨가비율이 증가함에 따라 유전상수와 압전상수($d_{33}$)는 증가하였으며, 전압상수($g_{33}$)는 급격히 감소하는 경향을 보였으며, 분극시간과 분극전압도 전기적 특성에 영향을 주는 것을 확인하였다. 분극전압 5KV 인가한 고분자 15% 첨가한 복합 소재에서 유전상수 13, 압전상수 $d_{33}$ 23(${\ast}10^{-12}C/N$), 전압상수 $g_{33}$ 170($10^{-3}v.m/N$)의 우수한 특성을 나타내었다.

• 자원환경지질
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• 제30권1호
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• pp.35-49
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• 1997

The coal formation of the Deokpyeong area are interbedded along metapelites of the Ogcheon Supergroup, which are composed mainly of graphite, quartz, muscovite and associated with small amounts of biotite, chlorite, pyrite and barite. The ratios of $SiO_2/Al_2O_3$, $Al_2O_3/Na_2O$ and $K_2O/Na_2O$ of the coaly metapelite are variable and wide range from 1.80 to 10.21, from 27.8 to 388.8 and from 7.6 to 61.8, respectively. These coal formation were deposited in basin of marine environments, and the REE of these rocks are not influenced with metamorphism and hydrothermal alterations on the basis of $Al_2O_3$ versus La, La against Ce, the ratios of La/Ce (0.19 to 0.99) and Th/U (0.02 to 4.75). These rocks also show much variation in $La_N/Yb_N$ (1.19 to 22.89), Th/Yb (0.14 to 21.43) and La/Th (0.44 to 13.67), and their origin is explained by derivation from a mixture of sedimentary and igneous rocks. The wide range in trace and REE element characteristics as Co/Th (0.12 to 2.78), La/Sc (0.33 to 10.18), Sc/Th (0.57 to 5.73), V/Ni (8 to 2347), Cr/V (0.02 to 0.67) and Ni/Co (1.56 to 32.95) of these coaly metapelites argues for inefficient mixing of the various source lithologies during sedimentation. Deep to pale green barium-vanadium muscovites (vanadium-oellacherite) have been found in this coal formations. Modes of occurrence and grain size of muscovite are heterogeneous, but most of the barium and vanadium-bearing muscovites occur along the boundaries between graphite and quartz grains, ranging from 200 to $350{\mu}m$ in length and from 40 to $60{\mu}m$ in width. Results of X-ray diffraction data of the minerals characterized to be monoclinic system with $a=5.249{\AA}$, $b=8.939{\AA}$, $c=20.924{\AA}$ and ${\beta}=95.894^{\circ}$. Representative chemical formula of the muscovite was $(Na_{0.09}K_{1.44}Ba_{0.46})(Al_{2.75}Ti_{0.07}V_{0.56}Fe_{0.08}Mg_{0.50})(Si_{6.12}Al_{1.88})O_{22}$. The V possibly substitute octahedral Al, and the Ba is coupled substitution of $K^+Si^{4+}=Ba^{2+}Na^+Ca^{2+}$, which compositional ranges of V and Ba are from 0.42 to 0.69 and from 0.34 to 0.56 based on $O_{22}$, respectively. Formation mechanism of the barium-vanadium muscovites in the coaly metapelite is shown that the formed by high pressure and temperature from regional metamorphism origanated during diagenesis at the interface between a basinal brine and organic matter.

• 광물과 암석
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• 제34권1호
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• pp.1-14
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• 2021

운산 금 광상은 한반도의 3대(대유동 광상, 광양 광상) 금 광상중의 하나였다. 이 광상의 지질은 선캠브리아기의 변성퇴적암류와 중생대의 반상화강암으로 구성된다. 이 광상은 선캠브리아기의 변성퇴적암류와 중생대의 반상화강암내에 발달된 단층대를 따라 충진한 함 금 석영맥 광상으로 조산형 금 광상에 해당된다. 이 광상의 석영맥은 광물조합에 따라 1) 방연석-석영맥형, 2) 자류철석-석영맥형, 3) 황철석-석영맥형, 4) 페크마틱 석영맥형, 5) 백운모-석영맥형 및 6) 단순석영맥형으로 분류된다. 연구된 석영맥은 황철석-석영맥형이며 견운모화작용, 녹니석화작용 및 규화작용이 관찰된다. 백색운모는 유색대에서 백색석영, 황철석, 녹니석, 금홍석, 모나자이트, 저어콘, 인회석, 칼리장석 및 방해석 등과 함께 세립질 내지 중립질 입단으로 산출된다. 이 백색운모의 화학조성은 (K0.98-0.86Na0.02-0.00Ca0.01-0.00Ba0.01-0.00 Sr0.00)1.00-0.88(Al1.70-1.57Mg0.22-0.09Fe0.23-0.10Mn0.00Ti0.04-0.02Cr0.01-0.00V0.00Ni0.00)2.06-1.95 (Si3.38-3.17Al0.83-0.62)4.00O10(OH2.00-1.91F0.09-0.00)2.00로써 이론적인 이중팔면체형 운모류 값보다 Si가 높고 K, Na, Ca는 낮다. 이 광상의 엽리상 석영맥에서 산출되는 백색운모의 화학조성 변화는 팬자이틱(phengitic) 또는 Tschermark 치환[(Al3+)VI+(Al3+)IV <-> (Fe2+ 또는 Mg2+)VI+(Si4+)IV] 및 직접적인 (Fe3+)VI <-> (Al3+)VI 치환에 의해 일어났음을 알 수 있다. 엽리상 석영맥에서 산출되는 녹니석의 화학조성은 (Mg1.11-0.80Fe3.69-3.14Mn0.01-0.00Zn0.01-0.00K0.07-0.01Na0.01-0.00Ca0.04-0.01Al1.66-1.09)5.75-5.69 (Si3.49-2.96Al1.04-0.51)4.00O10 (OH)8로써 이론적인 녹니석보다 Si 함량이 높다. 이 녹니석의 화학조성 변화는 팬자이틱(phengitic) 또는 Tschermark 치환(Al3+,VI+Al3+,IV <-> (Fe2+ 또는 Mg2+)VI+(Si4+)IV) 및 팔면체적 Fe2+ <-> Mg2+ (Mn2+) 치환에 의해 일어났음을 알 수 있다. 따라서 운산 광상의 엽리상 석영맥 및 변질광물은 조산운동 시 연성전단(ductile shear) 시기에 형성되었음을 알 수 있다.

• Transactions on Electrical and Electronic Materials
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• 제13권5호
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• pp.215-220
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• 2012

Miniature ultrasonic and tactile sensors on Si substrate have been proposed, fabricated and characterized to detect objects for a dexterous robot. The ultrasonic sensor consists of piezoelectric PZT thin film on a Pt/Ti/$SiO_2$ and/or Si diaphragm fabricated using a micromachining technique; the ultrasonic sensor detects the piezoelectric voltage as an ultrasonic wave. The sensitivity has been enhanced by improving the device structure, and the resonant frequency in the array sensor has been equalized. Position detection has been carried out by using a sensor array with high sensitivity and uniform resonant frequency. The tactile sensor consists of four or three warped cantilevers which have NiCr or $Si:B^+$ piezoresistive layer for stress detection. Normal and shear stresses can be estimated by calculation using resistance changes of the piezoresitive layers on the cantilevers. Gripping state has been identified by using the tactile sensor which is installed on finger of a robot hand, and friction of objects has been measured by slipping the sensor.

• Nuclear Engineering and Technology
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• 제46권6호
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• pp.857-862
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• 2014

Mechanical alloying under various gas atmospheres such as Ar, an Ar-$H_2$ mixture, and He gases were carried out, and its effects on the powder properties, microstructure and mechanical properties of ODS ferritic steels were investigated. Hot isostatic pressing and hot rolling processes were employed to consolidate the ODS steel plates. While the mechanical alloyed powder in He had a high oxygen concentration, a milling in Ar showed fine particle diameters with comparably low oxygen concentration. The microstructural observation revealed that low oxygen concentration contributed to the formation of fine grains and homogeneous oxide particle distribution by the Y-Ti-O complex oxides. A milling in Ar was sufficient to lower the oxygen concentration, and this led a high tensile strength and fracture elongation at a high temperature. It is concluded that the mechanical alloying atmosphere affects oxygen concentration as well as powder particle properties. This leads to a homogeneous grain and oxide particle distribution with excellent creep strength at high temperature.

• Nuclear Engineering and Technology
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• 제51권4호
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• pp.1069-1074
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• 2019

A novel fabrication method of oxide dispersion strengthened (ODS) steel cladding tubes for advanced fast reactors has been investigated using the cold spray powder-based materials deposition process. Cold spraying has the potential advantage for rapidly fabricating ODS cladding tubes in comparison with the conventional multi-step extrusion process. A gas atomized spherical 14YWT (Fe-14%Cr, 3%W, 0.4%Ti, 0.2% Y, 0.01%O) powder was sprayed on a rotating cylindrical 6061-T6 aluminum mandrel using nitrogen as the propellant gas. The powder lacked the oxygen content needed to precipitate the nanoclusters in ODS steel, therefore this work was intended to serve as a proof-of-concept study to demonstrate that free-standing steel cladding tubes with prototypical ODS composition could be manufactured using the cold spray process. The spray process produced an approximately 1-mm thick, dense 14YWT deposit on the aluminum-alloy tube. After surface polishing of the 14YWT deposit to obtain desired cladding thickness and surface roughness, the aluminum-alloy mandrel was dissolved in an alkaline medium to leave behind a free-standing ODS tube. The as-fabricated cladding tube was annealed at $1000^{\circ}C$ for 1 h in an argon atmosphere to improve the overall mechanical properties of the cladding.

• Nuclear Engineering and Technology
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• 제53권8호
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• pp.2582-2590
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• 2021

The high-energy milling is one of the most extended techniques to produce Oxide dispersion strengthened (ODS) powder steels for nuclear applications. The consequences of the high energy mill process on the final powders can be measured by means of deformation level, size, morphology and alloying degree. In this work, an ODS ferritic steel, Fe-14Cr-5Al-3W-0.4Ti-0.25Y₂O₃-0.6Zr, was fabricated using two different mechanical alloying (MA) conditions (M_std and M_act) and subsequently consolidated by Spark Plasma Sintering (SPS). Milling conditions were set to evidence the effectivity of milling by changing the revolutions per minute (rpm) and dwell milling time. Differences on the particle size distribution as well as on the stored plastic deformation were observed, determining the consolidation ability of the material and the achieved microstructure. Since recrystallization depends on the plastic deformation degree, the composition of each particle and the promoted oxide dispersion, a dual grain size distribution was attained after SPS consolidation. M_act showed the highest areas of ultrafine regions when the material is consolidated at 1100 ℃. Microhardness and small punch tests were used to evaluate the material under room temperature and up to 500 ℃. The produced materials have attained remarkable mechanical properties under high temperature conditions.