• 한국전기전자재료학회논문지
• /
• 제23권3호
• /
• pp.194-198
• /
• 2010

Recently as the electronic devices are getting to be more and more smaller, transformers are needed to be micro fabricated using MEMS technology. In this paper transformers have been fabricated and measured by depositing insulation layer to reduce the loss of eddy current and in the middle core a high permeability permalloy was designed based on the turns ratio between primary coil and secondary coil which are 1:1 transformers. (the number of turns of primary coil and secondary coil: 3/3, 5/5, 7/7). The size of the transformers including ground shield are $1mm{\times}1.5mm$, $1mm{\times}1.95mm$, $1mm{\times}2.35mm$ respectively. The line width, pitch and the height of post are 50um. Based on the measured data from the micro fabricated transformers, the 3/3 turns in the primary coil and secondary coil showed the lowest insertion loss with 1.5 dB at 480 MHz and the 7/7 turns in the primary coil and secondary coil showed the highest insertion loss with 2.5 dB at 280 MHz. Also confirmed that the bandwidth goes up as the number of turns goes down. There was some difference between the actual measured data and the HFSS simulation result. It looks as if it is an error of the difference between oxidation of copper or the permeability of SU-8.

• 한국환경과학회지
• /
• 제4권5호
• /
• pp.103-103
• /
• 1995

In the Chinhae Bay, Korea, sedimentation rates and sedimentary record of anthropogenic metal loads were determined by $^{210}Pb$ dating and heavy metal analysis of four sediment cores . The sedimentation rates varied from 0.16g/$cm^2$/yr(3.1mm/yr) at Sta. Ct, located within narrow waterway to 0.24g/$cm^2$/yr(4.8mm/yr) at Sta. Cl, located in Haengam Bay. Maximum contents of Mn, Zn, Cu and Cr were observed at Sta. C2 located near the mouth of Masan Bay, while minimum contents were observed at Sta. CB. Mn/Fe ratios at Sta. C2 and Sta. C4 showed gradually increasing and decreasing downward, respectively, in the upper layer of sediment cores. This suggests that Mn may be diagenetically redistributed in highly reduced environment. At Sta. C2, the concentrations of Zn and Cu began to increase from 1920s by anthropogenic input and have been remarkablely increasing since mid 1960s. At Sta. C3, located near Sungpo, anthropogenic input of these two elements has also slightly increased after 1970s. However, pollution of these two elements was not significant in Haengam Bay(Sta. Cl) and Chiljun watenway(Sta. C4). The pollution of Co, Ni and Cr was not remarkable in all core samples except surface sediment of Sta. C2. The total input of anthropogenic Zn and Cu since 1920s was estimated to be 28∼792 ㎍/cm2 and 0∼168㎍/cm2, respectively. Sta. C2 showed remarkablely higher values relative to other stations: anthropogenic loads of Zn and Cu constituted 27% and 29% of the total sedimentary inventories at the present day, respectively. Fe, Ni, Cr and Co contents showed good correlation(r>0.8) with each other. Anthropogenic Zn and Cu also showed a very good positive correlation(>0.9). However, correlation between these two group of element was quite scattered, indicating different sources and geochemical behaviors.

• 한국환경과학회지
• /
• 제4권5호
• /
• pp.489-500
• /
• 1995

In the Chinhae Bay, Korea, sedimentation rates and sedimentary record of anthropogenic metal loads were determined by $^{210}Pb$ dating and heavy metal analysis of four sediment cores . The sedimentation rates varied from 0.16g/$cm^2$/yr(3.1mm/yr) at Sta. Ct, located within narrow waterway to 0.24g/$cm^2$/yr(4.8mm/yr) at Sta. Cl, located in Haengam Bay. Maximum contents of Mn, Zn, Cu and Cr were observed at Sta. C2 located near the mouth of Masan Bay, while minimum contents were observed at Sta. CB. Mn/Fe ratios at Sta. C2 and Sta. C4 showed gradually increasing and decreasing downward, respectively, in the upper layer of sediment cores. This suggests that Mn may be diagenetically redistributed in highly reduced environment. At Sta. C2, the concentrations of Zn and Cu began to increase from 1920s by anthropogenic input and have been remarkablely increasing since mid 1960s. At Sta. C3, located near Sungpo, anthropogenic input of these two elements has also slightly increased after 1970s. However, pollution of these two elements was not significant in Haengam Bay(Sta. Cl) and Chiljun watenway(Sta. C4). The pollution of Co, Ni and Cr was not remarkable in all core samples except surface sediment of Sta. C2. The total input of anthropogenic Zn and Cu since 1920s was estimated to be 28~792 $\mu\textrm{g}$/cm2 and 0~168$\mu\textrm{g}$/cm2, respectively. Sta. C2 showed remarkablely higher values relative to other stations: anthropogenic loads of Zn and Cu constituted 27% and 29% of the total sedimentary inventories at the present day, respectively. Fe, Ni, Cr and Co contents showed good correlation(r>0.8) with each other. Anthropogenic Zn and Cu also showed a very good positive correlation(>0.9). However, correlation between these two group of element was quite scattered, indicating different sources and geochemical behaviors.

• Corrosion Science and Technology
• /
• 제20권3호
• /
• pp.158-168
• /
• 2021

Austenitic 316 stainless steel was irradiated with protons accelerated by an energy of 2 MeV at 360 ℃, the various defects induced by this proton irradiation were characterized with microscopic equipment. In our observations irradiation defects such as dislocations and micro-voids were clearly revealed. The typical irradiation defects observed differed according to depth, indicating the evolution of irradiation defects follows the characteristics of radiation damage profiles that depend on depth. Surface oxidation tests were conducted under the simulated primary water conditions of a pressurized water reactor (PWR) to understand the role irradiation defects play in surface oxidation behavior and also to investigate the resultant irradiation assisted stress corrosion cracking (IASCC) susceptibility that occurs after exposure to PWR primary water. We found that Cr and Fe became depleted while Ni was enriched at the grain boundary beneath the surface oxidation layer both in the non-irradiated and proton-irradiated specimens. However, the degree of Cr/Fe depletion and Ni enrichment was much higher in the proton-irradiated sample than in the non-irradiated one owing to radiation-induced segregation and the irradiation defects. The microstructural and microchemical changes induced by proton irradiation all appear to significantly increase the susceptibility of austenitic 316 stainless steel to IASCC.

• 한국광물학회지
• /
• 제13권2호
• /
• pp.53-64
• /
• 2000

Chlorite from the talc deposits in the Chungnam area, Korea, has been studied using electron microprobe analysis and high resolution transmission electron microscopy (HRTEM), Talc orea are hydrothermal alteration products of serpentinite which was originated from ultramafic rocks. Chlorite occurs in close association with talc ores of with the black alteration zone between talc ore bodies and granitic gneiss. It is the most abundant impurity mineral of talc ores. Chlorite in association with talc is characterized by very high but narrow variation in Mg/(Mg+Fe) ratios (0.784~0.951), significant octahedral substitution (-0.200~0.692), wide variation in Al contents (1.085~3.160 / 14 oxygens), and high Cr and Ni contents. It was formed under a very limited but high Mg/(Mg+Fe) condition in close connection with serpentinite. Chlorite in the black alteration zone is characterized by a high Fe content, wide variation in Mg/(Mg+Fe) ratios (0.378~0.852), narrow octahedral substitution (-0.035~0.525), high narrow Al contents (1.468~2.959), and low Cr and Ni contents. It was formed under a low Mg/(Mg+Fe) and relatively Al-rich condition in close connection with county rocks. Two different chemical modes for chlorite suggest two different origins for two different chlorites. Although most of chlorites show typical 14-$\AA$ lattice fringe images under HRTEM, some chlorites show fringe images of 21-$\AA$ (14$\AA$+7$\AA$) spacings within (001) lattice-fringe images of chlorite (14$\AA$). But brown chlorite from the black zone has high Ti and K contents suggesting that mica was the precursor of brown chlorite. Such possibility is also supported by the fact that lattice-fringe images of brown chlorite show 14-$\AA$ chlorite layers in which 10-$\AA$ mica single layer or packets are interlayered. Partial terminations from 3 mica layers to 2 chlorite layers are often observed. It, therefore, is suggested that the chlorite associated with talc ores is a hydrothermal alteration products of serpentinite, whereas the chlorites in the black alteration zone is a hydrothermal alteration product of granitic gnesis under a partial influence of serpentinite.

• 한국미생물·생명공학회지
• /
• 제27권3호
• /
• pp.203-207
• /
• 1999

V. alginolyticus 138-2, a marine halophilic bacterium, produced an extracellular amylase with a molecular weight of ca. 56,000. The analysis of the digestion products of soluble starch by thin layer chromatography(TLC) revealed that the extracellular amylase of V. alginolyticus 138-2 is a saccharifying-type alpha-amylase. The alpha-amylase activity of the culture supernatant of soluble starch was optimal at pH 6.0 and 45$^{\circ}C$. Ca2+ slightly increased the alpha-amylase activity, whereas Hg2+, An2+, Cu2+, Ni2+, Fe2+, and Mn2+inhibited the enzymatic activity. Alkylating thiol group agent, iodoacetic acid did not affect the alpha-amylase activity, but reduced thiol reagents such as dithiothreitol, cysteine, and beta-mercaptoethanol stimulated theenzymatic activity. On the other hand, even if V. alginolyticus 138-2 is a marine halophilic bacterium, its alpha-amylase activity was significantly inhibited by NaCl.

• 한국주조공학회지
• /
• 제13권3호
• /
• pp.276-284
• /
• 1993

The interfacial phenomena between intermetallic compounds and Al matrix have been studied at $680^{\circ}C$ for various holding time under argon atmosphere. Model experiments were performed using Fe, Ni and Ti wire to observe the interfacial phenomena. The interfacial phenomena between intermetallic compounds and Al matrix were analysed by optical microscope, SEM and EDX. The results of EDX and XRD showed that the interfacial zones of intermetallic compounds/Al matrix were composed of several intermetallic layers. The reaction layer was varied with holding time and heating temperature. The investigation of interfacial zones in the specimen as a function of heat treatment time at $680^{\circ}C$ indicated that the best heat treatment condition for squeeze casting was $680^{\circ}C$ for 5min.

• 한국자기학회:학술대회 개요집
• /
• 한국자기학회 2002년도 동계연구발표회 논문개요집
• /
• pp.30-31
• /
• 2002

100 Gbit/in$^2$ 이상의 자기기록밀도를 달성하기 위해서는 재생헤드로 사용되고 있는 스핀밸브의 자기저항비가 10% 이상을 가지면서 열적 특성이 우수해야 한다. 현재까지 연구되어진 스핀밸브 구조 중 NiO([,2,3], $\alpha$-Fe$_2$O$_3$[4]등의 산화물 반강자성 층을 사용한 스핀밸브의 경우 기본 스핀밸브 구조를 사용하고도 이미 20% 이상의 자기저항비를 달성하였다. 이러한 높은 자기저항비는 절연층인 산화물 반강자성층과 금속 자성층 계면에서 일어나는 전자의 스펙큘라 반사(specular reflection)로부터 기인한다고 보고하고 있다.[2] (중략)

• 한국표면공학회지
• /
• 제26권2호
• /
• pp.45-54
• /
• 1993

In this study, magnetic properties of anodized Al film deposited with ferro-magnetic metals in the capacity of perpendicular magnetic recording media were measured and evaluated to find out the role of structure and morphology of the oxide films on magnetic characteristics. The object of this work was to present the conditions of magnetic thin film formation with more superior magnetic property. Anodizing was carried out under various conditions, and then the anodized film were electro-deposited with Co, Ni, Fe and their alloys. Coercive force and residual magnetization in perpendicular direction increased as the pore length of anodized film increased. It was attributed to the increase of the amount of depoisted metals and the ratio of length/diameter of pores. Morphology of anodized films in phosperic acid was not similar to that of sulfuric acid, and thin films in the former solution had perpendcular magnetic anisostropy because of large diameter, irregular length and distribution of the pores. It was found that magnetic properties of the thin films, which had doubled layer of two metals, were dominated by the metal electrodeposited on the surface of the anodized oxide films.

• Transactions on Electrical and Electronic Materials
• /
• 제15권4호
• /
• pp.189-192
• /
• 2014

Yttria-stablized zirconia (YSZ) is the most commonly used electrolyte material, but the reduction in working temperature leads to insufficient ionic conductivity. Ceria based electrolytes (GDC) are more attractive in terms of conductivity at low temperature, but these materials are well known to be reducible at very low oxygen partial pressure. The reduction of electrolyte resistivity is necessary to overcome cell performance losses. So, thin YSZ/GDC bilayer technology seems suitable for decreasing the electrolyte resistance at lower operating temperatures. Bilayer electrolytes composed of a galdolinium-doped $CeO_2$ ($Ce_{0.9}Gd_{0.1}O_{1.95}$, GDC) layer and yttria-stabilized $ZrO_2$ (YSZ) layer with various thicknesses were deposited by RF sputtering and E-beam evaporation. The bilayer electrolytes were deposited between porous Ni-GDC anode and LSM cathode for anode-supported single cells. Thin film structure and surface morphology were investigated by X-ray diffraction (XRD), using $CuK{\alpha}$-radiation in the range of 2ce morphol$^{\circ}C$. The XRD patterns exhibit a well-formed cubic fluorite structure, and sharp lines of XRD peaks can be observed, which indicate a single solid solution. The morphology and size of the prepared particles were investigated by field-emission scanning electron microscopy (FE-SEM). The performance of the cells was evaluated over $500{\sim}800^{\circ}C$, using humidified hydrogen as fuel, and air as oxidant.