• 암석학회지
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• 제4권1호
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• pp.61-87
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• 1995

홍제사 화강암질 편마엄체의 암상은 국부적으로 중앙부에거 주변부로 감에 따라 차례로 입상변정질 화강임질 편마암, 반상변정질 화강암질 편마암, 그리고 미그마타이트질 편마암으로 점이적인 변화를 보인다. 암상변화에 따른 광물군의 변화는 뚜렷하게 구분되지 않지만, 미그마타이트질 편마암 인접부에서는 부분적으로, 광물군이 변화를 보여, 이를 Zone I과 II로 구분하였다. Zone I의 특징은 K-장석+백운모+규선석의 공생이고, Zone II의 특징은 (1)백운모의 소멸, (2) 석류석+군청석의 공생, (3) 석류석+근청석+각섬석의 공생이다. 분천 화강암질 편마암체는 주로 안구상편마암으로 구성되어있으며, 홍제사 화강암질 편마암체과 인접부에서는 흑운모+K-장석+규선석+(남장석) 광물군집을 보인다. 두 암체에서 산출되는 남정석은 타형 내지 반자형의 결정으로잔류형태의 광물로 나타나며, 규석석과 공존하며 나타나기도 한다. 미그마이트질 편마암의 ZoneII에서 석류석은 중심부와 주변부에서 높은 F/FM(=Fe/Fe+Mg)값과 $X_{Fe}$ 함량을 보인다. 반면에, $X_{Mg}$와 $X_{Ca}$ 함량은 상대적으로 약간 감소하는 경향을 보인다. 반상변정질 화강암질 편마암의 ZoneI에서 산출되는 석류석은 중심부에서는 성분변화를 보이지 않지만, 주변부에서는 누대구조를 보인다. 흑운모 ZoneI에서 ZoneII로 이동됨에 따라 색은 녹갈색에서 갈색, 적갈색으로 변화하는 양상을 보이며, 그에따라 Ti, Mg 함량이 증가하는 경향을 보인다. ZoneI에서 장정석은 올리고크레스에 해당하는 $Ab_{84}An_{16}$내지 $Ab_{70}An_{30}$ 의 화학조성을 보이며, ZoneII의 사장석은 안데신에 해당하는 $Ab_{70}An_{30}$ 내지 $Ab_{50}An_{50}$ 의화학조성을 나타낸다. 이와같은 변화양상을 연구지역이 규선석+K-장석대 또는 상부 앰피볼라이트상에서 해당되는 규선석+K-장정석대에 해당하는 고온-저혈압형 변성작용 이전에 고온-중압형의 변성작용을 경험했을 가능성을 제기해 주고 있다. 석류석- 흑운모, 근청석-석류석, 사장석-K-장석 지온계, GASP 지압계 및 ZoneI과 II의 광물군으로 측정된 연구지역의 암석에 대한 변성 작용의 온도.압력 조건은 분천 화강암질 편마암의 경우, 698~$729^{\circ}C$/6.3~11.3kbar (Zone I의 중압대)이고, 미그마타이트질 편마암의 경우, 621~$667^{\circ}C$/1.0~5.4kbar (Zone II)이며, 반상변정질 화강암질 편마암이 경우는 602~$624^{\circ}C$/1.9~3.4kbar (Zone I의 저압대) 이다. 이상의 증거로부터 추정된 연구 지역의 전체적인 온도.압력 경로는 "등온성 압력감소 (isothermal-decompression: ITD"를 보이며 시계방향(clockwise path)으로 이동된 것으로 생각된다. 압력감소 비율(dP/dT)은 약 60bar/$^{\circ}C$를 보인다.TEX>를 보인다.

• 한국진공학회지
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• 제9권2호
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• pp.136-143
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• 2000

RF magnetron sputtering법으로 $SrBi_2Ta_2O_9$ (SBT)박막을 상온에서 p-type Si(100) 기판위에 증착하여 DRO 강유전체 메모리(destructive read out ferroelectric random access memory)에 사용되는 강유전체막으로 Pt/SBT/Pt/Ti/$SiO_2$/Si (MFM)구조의 응용가능성을 확인하였다. 구조적인 특징들이 열처리 시간의 변화와 Ar/$O_2$의 가스 유량비의 변화에 따라서 XRD(x-ray diffractometer)에 의해 관찰되었으며 표면 특성은 FE-SEM(field emission scanning electron microscopy)에 의해서 관찰하고 박막의 전기적 특성들은 P-V(polarization-voltage measurement)와 I-V(current-voltage measurement)를 사용하여 관찰하였다. 스퍼터링 증착시 Ar/$O_2$의 가스 유량비는 1:4에서 4:1까지 변화 시켰고 SBT박막은 상온에서 증착시켰다. XRD 측정시 박막들은 SBT의 (105), (110) peak들을 나타내었다. 상온에서 증착시킨 박막은 1시간, 2시간 동안 산소 분위기에서 $800^{\circ}C$ 열처리를 하여 결정화 시켰다. SBT 박막의 P-V곡선은 이력 곡선의 모양을 갖추었으며 비대칭적인 강유전체 특성을 나타내었다. Ar/$O_2$ 가스유량비가 1 : 1, 2 : 1인 경우에 박막의 누설 전류밀도 값이 제일 좋았으며, 그 값은 3V 5V 7V에서 각각 $3.11\times10^{-8} \textrm{A/cm}^2$, $5\times10^{-8}\textrm{A/cm}^2$, $7\times10^{-8}\textrm{A/cm}^2$ 이었다. 열처리 시간을 2시간으로 증가시킨 후, 그들의 전기적 특성과 결정화특성이 개선됨을 확인하였다. AES 분석 및 EPMA분석으로 SBT박막의 깊이 분포 및 조성을 확인하였다.

• 한국수소및신에너지학회논문집
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• 제25권3호
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• pp.247-254
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• 2014

The synthesis of Fischer-Tropsch oil is the catalytic hydrogenation of CO to give a range of products, which can be used for the production of high-quality diesel fuel, gasoline and linear chemicals. Our cobalt based catalyst was prepared Co/alumina, silica and titania by the incipient wet impregnation of the nitrates of cobalt and promoter with supports. Cobalt catalysts was calcined at $350^{\circ}C$ before being loaded into the FT reactors. After the reduction of catalyst has been carried out under $450^{\circ}C$ for 24hrs, FT reaction of the catalyst has been carried out at GHSV of 4,000/hr under $200^{\circ}C$ and 20atm. From these test results, we have obtained the results as following ; in case of 12wt% Co-supported $Al_2O_3$, $SiO_2$ and $TiO_2$ catalysts, maximum activities of the catalysts were appeared at the promoters of Mn, Mo and Ce respectively. The activity of 12wt% $Co/Al_2O_3$ added a Mn promoter was about 3 times as high as that of 12wt% $Co/Al_2O_3$ catalyst without promoters. When it has been the experiment at the range of reaction temperature of $200{\sim}220^{\circ}C$ and GHSV of 1,546~5,000/hr, the results have shown generally increasing the activities with the increase of reaction temperature and GHSV.

• Computers and Concrete
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• 제19권2호
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• pp.153-159
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• 2017

In this study, the strength properties of alkali-activated silica fume (SF) mortars were investigated. The crushed limestone sand with maximum size of 0-5 mm and the sodium meta silicate ($Na_2SiO_3$) used to activate the binders were kept constant in the mortar mixtures. The mortar specimens using the replacement ratios of 0, 25, 50, 75 and 100% SF by weight of cement together with $Na_2SiO_3$ at a constant rate were produced in addition to the control mortar produced by only cement. Moreover, the mortar specimens using the replacement ratio of 4% titanium dioxide ($TiO_2$) by weight of cement in the same mixture proportions were produced. The prismatic specimens produced from eleven different mixtures were de-moulded after a day, and the wet or dry cure was applied on the produced specimens at laboratory condition until the specimens were used for flexural strength ($f_{fs}$) and compressive strength ($f_c$) measurement at the ages of 7, 28 and 56 days. The $f_{fs}$ and $f_c$ values of mortars applied the wet or dry cure were compared with the results of control mortar. The findings revealed that the $f_c$ results of the alkali activated 50% SF mortars were higher than that of mortar produced with Portland cement only. It was found that the $f_{fs}$ and $f_c$ of alkali-activated SF mortars cured in dry condition was averagely 4% lower than that of alkali-activated SF mortars cured in wet condition.

• 한국가금학회지
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• 제51권1호
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• pp.21-26
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• 2024

This study was conducted to investigate the composition of the fatty acids in the breast meat of Red-brown Korean native chickens (KNC-R). This study used a total sample of three hundred eighty-two KNC-R (males: 190, females: 192). We used the fatty acid methyl ester (FAME) method to extract the fatty acids. A 2-way ANOVA of the R program was used to assess the effects of batch and sex on each fatty acid trait. Analysis of the fatty acid in the sampled population showed that the predominant fatty acid was oleic acid (C18:1; 28.252%) which is monounsaturated fatty acid (MUFA), followed by palmitic acid (C16:0; 20.895%), saturated fatty acid (SFA), and two omega-6 polyunsaturated fatty acid (PUFAs): linoleic (C18:2; 15.975%), and arachidonic (C20:4; 10.541%). Indices used to evaluate the nutritional quality of fat in the diet: ratio between PUFAs and SFAs (P/S), thrombogenicity index (TI), and atherogenicity index (AI) were calculated and were 0.959, 0.814, and 0.355, respectively. Currently, meat consumers need healthier fatty acids. Therefore, information on the content of fatty acid in chicken meat is very important for meat consumers in choosing the type of the meat to be consumed.

• Corrosion Science and Technology
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• 제6권2호
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• pp.37-43
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• 2007

Iodine sulfur (IS) process is one of the promising processes for a hydrogen production by using a high temperature heat generated by a very high temperature gas cooled reactor(VHTR) in the nuclear power industries. Even though the IS process is very efficient for a hydrogen production and it is not accompanied by a carbon dioxide evolution, the highly corrosive environment of the process limits its application in the industry. Corrosion tests of selected materials were performed in sulfuric acid to select appropriate materials compatible with the IS process. The materials used in this work were Fe-Cr alloys, Fe-Ni-Cr alloys, Fe-Si alloys, Ni base alloys, Ta, Ti, Zr, SiC, Fe-Si, etc. The test environments were 50 wt% sulfuric acid at $120^{\circ}C$ and 98 wt% at $320^{\circ}C$. Corrosion rates were measured by using a weight change after an immersion. The surface morphologies and cross sectional areas of the corroded materials were examined by using SEM equipped with EDS. Corrosion behaviors of the materials were discussed in terms of the chemical composition of the materials, a weight loss, the corrosion morphology, the precipitates in the microstructure and the surface layer composition.

• Nuclear Engineering and Technology
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• 제55권3호
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• pp.1061-1070
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• 2023

Over the last few years, lead-free inorganic metal perovskites have gained impressive ground in empowering satellites in space exploration owing to their material stability and performance evolution under extreme space environments. The present work has examined the versatility of eight such perovskites as space radiation shielding materials by computing their photon, charged particles and neutron interaction parameters. Photon interaction parameters were calculated for a wide energy range using PAGEX software. The ranges of heavy charged particles (H, He, C, N, O, Ne, Mg, Si and Fe ions) in these perovskites were estimated using SRIM software in the energy range 1 keV-10 GeV, and that of electrons was computed using ESTAR NIST software in the energy range 0.01 MeV-1 GeV. Further, the macroscopic fast neutron removal cross-sections were also calculated to estimate the neutron shielding efficiencies. The examined shielding parameters of the perovskites varied depending on the radiation type and energy. Among the selected perovskites, Cs₂TiI₆ and Ba₂AgIO₆ displayed superior photon attenuation properties. A 3.5 cm thick Ba₂AgIO₆-based shield could reduce the incident radiation intensity to half its initial value, a thickness even lesser than that of Pb-glass. Besides, CsSnBr₃ and La_0.8Ca_0.2Ni_0.5Ti_0.5O₃ displayed the highest and lowest range values, respectively, for all heavy charged particles. Ba₂AgIO₆ showed electron stopping power (on par with Kovar) better than that of other examined materials. Interestingly, La_0.8Ca_0.2Ni_0.5Ti_0.5O₃ demonstrated neutron removal cross-section values greater than that of standard neutron shielding materials - aluminium and polyethylene. On the whole, the present study not only demonstrates the employment prospects of eco-friendly perovskites for shielding space radiations but also suggests future prospects for research in this direction.

• 전자공학회논문지D
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• 제36D권12호
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• pp.37-42
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• 1999

본 논문에서는 차세대 집적회로의 핵심공정으로 부각되고 있는 CMP를 이용한 Cu Damascene 공정을 연구하였다. E-beam lithography, $SiO_2$ CVD 및 RIE, Ti/Cu CVD등의 제반 단위 공정을 연구하였으며, 연구된 단위공정으로 2창의 Cu금속 배선을 제작하였다. CMP 단위공정 연구결과, hend 압력 4 PSI, table 및 head 속도 25rpm, 진동폭 10mm, 슬러리 공급량 40ml/min에서 연마율 4,635 ${\AA}$/min, Cu:$SiO_2$의 선택율 150:1, 평탄도 4.0%를 얻었다. E-beam 및 $SiO_2$ vialine 공정연구결과, 100 ${\mu}C/cm^2$ 도즈와 6분 30초의 현상 및 1분 10초의 에칭시간으로 약 0.18 ${\mu}m\;SiO_2$ via-line을 형성하였다. 연구된 단위공정으로 sub-0.2 ${\mu}$의 Cu 금속라인을 제작하였으며, Cu void 및 Cu의 peeling으로 인한 다층공정시의 문제점과 재현성 향상 방법에 대해 논의하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.375-375
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• 2009

For many large-scale applications of high-temperature superconducting materials, large critical current density($J_c$) in high applied magnetic fields are required. A number of methods have been reported to introduce artificial pinning centers(APCs) in $YBa_2Cu_3O_{7-\delta}$(YBCO) films for enhancement of their $J_c$. We report measurements of critical current in $YBa_2Cu_3O_{7-\delta}$ films deposited by PLD on $SrTiO_3$ substrates decorated with Au nanoparticles. Au nanoparticles were synthesized on STO substrates with self assembled monolayer. Microstructural analysis of the obtained YBCO films was performed by using cross-section transmission electron microscopy(TEM). Phase and textural analysis was done using X-ray diffraction. The surface morphology and surface roughness(Ra) of the layers was measured by atomic force microscopy(AFM).

• 한국전기전자재료학회논문지
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• 제22권11호
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• pp.935-940
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• 2009

In this research, the composites (100-x)LCP-xBNT (x = 0, 10, 20, 30, 40 vol.%) were fabricated with thermoplastic LCP(Liquid Crystal Polymer) and BNT($BaNd_2Ti_4O_{12}$) which is a high frequency dielectric material. Their dielectric properties, mechanical strength and microstructure were investigated by Impedance analyser, Instron and SEM. In order to fabricate LCP-BNT composites, LCP resin was put into the twin screw type mixer($310^{\circ}C$), melted by keeping for 10 min. After that, BNT filler was dispersed with melted LCP resin for 15 min. in the mixer. For measuring the dielectric properties and mechanical strength, Composite specimens were made by pressing composite granule (LCP-BNT) with 7 ton in the mold at $310^{\circ}C$. With increasing the BNT content (0~40 vol.%) of the composite, Its dielectric constant increased, dielectric loss and flexural strength decreased. The dielectric constant and flexural strength of composites with 20~30 vol.% of BNT filler are 4.1~6.0 and 35~55 MPa respectively. BNT/LCP composite is the potential substrate material for the high frequency application.