• Journal of Electrical Engineering and information Science
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• v.3 no.2
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• pp.245-250
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• 1998

Novel fabrication process of vertical spring for micro mirror array is proposed. The proposed fabrication process adopts a shadow evaporation process using shielding screen structure on top of the sacrificial layer. The 50${\times}$50 micro mirror arrays are fabricated using the proposed process and ceramic packaged. The static and dynamic characteristics of mirror are measured. The mirror plate touches substrate at 16V and the response time of about 16.8 ${\mu}\textrm{s}$. The resonant frequency of mirror is 16kHz. The spring thickness is calculated from static characteristic to be 1075${\AA}$.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.2260-2262
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• 2000

In this paper, micromirror which can rotate 45 degree is designed, analyzed and fabricated. The micromirror is parallel to the substrate initially. When external magnetic field is applied, a micromirror can rotate to align its easy axis to the field. The size of micromirror array is $10{\times}10$. The mirror plate and spring is made of aluminium, and nickel is used as soft magnetic material. To obtain 45 degree angular deflection, dimension ratio between stopper length and thickness of sacrificial layer is properly selected. By using electrostatic force, individual actuation is possible.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2383-2385
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• 2005

In this paper we discuss the design and fabrication of two millimeter wave filters, in bandpass and bandstop topologies for wireless communications applications. The filters are made using a high Q MMIC transmission line, which consists of a 100 micrometers tall, surface micromachined, air filled inverted microstrip structure on a quartz substrate, made by using a JSR THB-151N negative photoresist sacrificial layer mold and electroplating technology. The filter topologies include a new, very compact, four pole, cross-coupled filter, that presents a single transmission zero at the lower side of the passband, which provides a very sharp out of passband rejection at this region.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.8 s.185
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• pp.163-170
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• 2006

By removing sacrificial layer through ashing process, movable MEMS structure on substrate can be fabricated in surface micromachining. However, MEMS structure includes, during the ashing process, the warping or buckling effects due to stress gradient along the vertical direction of thin film. In this study, we presented method for counteracting the unwanted deflection of MEMS structure and designed using character of deposit process to overcome limited design conditions. Unit cell patterns were designed with character of deposit shape, and their final shapes were adopted using Finite Element Method. Finally, RF MEMS switch was fabricated by surface micro machining as test vehicles. We checked out that alleviation effect for deformation of switch improved by 35%.

• Journal of the Korea Convergence Society
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• v.8 no.11
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• pp.307-312
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• 2017

In the industry, galvanizing using the principle of sacrificial anode is used Zn-Ni alloy plating was developed as one of the measures to increase the corrosion resistance rather than pure zinc plating. The alloy plating layer has a corrosion resistance of 4-5 times that of the pure zinc plating layer, so that it is applied to automotive parts requiring high corrosion resistance even though the plating cost is high. The amount of Zn-Ni alloy plating solution is a sulfuric acid bath, a chlorinated bath, an alkali bath, and an ammonia bath. Here, the influence of the electrolytic conditions on the composition of the alloy plating in the chloride bath was investigated. The results are explained by the cathode overvoltage and the diffusion coefficient. In general, as the overvoltage of the cathode increases, the concentration polarization becomes more important than the activation polarization. The concentration polarization is determined by element diffusion in the diffusion layer. That is, as the overvoltage of the cathode increases, the Zn content having a large diffusion coefficient increases.

• Applied Science and Convergence Technology
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• v.26 no.5
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• pp.110-113
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• 2017

The two-dimensional layered $MoS_2$ has high mobility and excellent optical properties, and there has been much research on the methods for using this for next generation electronics. $MoS_2$ is similar to graphene in that there is comparatively weak bonding through Van der Waals covalent bonding in the substrate-$MoS_2$ and $MoS_2-MoS_2$ heteromaterial as well in the layer-by-layer structure. So, on the monatomic level, $MoS_2$ can easily be exfoliated physically or chemically. During the $MoS_2$ field-effect transistor fabrication process of photolithography, when using water, the water infiltrates into the substrate-$MoS_2$ gap, and leads to the problem of a rapid decline in the material's yield. To solve this problem, an epoxy-based, as opposed to a water-based photoresist, was used in the photolithography process. In this research, a hydrophobic $MoS_2$ field effect transistor (FET) was fabricated on a hydrophilic $SiO_2$ substrate via chemical vapor deposition CVD. To solve the problem of $MoS_2$ exfoliation that occurs in water-based photolithography, a PPMA sacrificial layer and SU-8 2002 were used, and a $MoS_2$ film FET was successfully created. To minimize Ohmic contact resistance, rapid thermal annealing was used, and then electronic properties were measured.

• Bulletin of the Korean Chemical Society
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• v.28 no.12
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• pp.2481-2485
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• 2007

Spatially resolved, quantitative, non-destructive analysis using synchrotron x-ray reflectivity (XR) with subnano-scale resolution was successfully performed on the nanoporous organosilicate thin films for low dielectric applications. The structural information of porous thin films, which were prepared with polymethylsilsesquioxane and thermally labile 4-armed, star-shaped poly(ε-caprolactone) (PCL) composites, were characterized in terms of the laterally averaged electron density profile along with a film thickness as well as a total thickness. The thermal process used in this work caused to efficiently undergo sacrificial thermal degradation, generating closed nanopores in the film. The resultant nanoporous films became homogeneous, well-defined structure with a thin skin layer and low surface roughness. The average electron density of the calcined film reduced with increase of the initial porogen loading, and finally leaded to corresponding porosity ranged from 0 to 22.8% over the porogen loading range of 0-30 wt%. In addition to XR analysis, the surface and the inner structures of films are investigated and discussed with atomic force and scanning electron microscopy images.

• Proceedings of the KIEE Conference
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• 1999.11d
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• pp.1137-1139
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• 1999

저가의 우수한 성능을 갖는 적외선 영상표시 소자 구현에 적합한 마이크로 볼로미터를 MEMS 기술을 사용하여 제작하였다. 작은 열질량을 갖는 마이크로미터 단위의 열적고립 구조(thermal isolation structure) 제작은 폴리이미드(PI2611)를 희생층으로 사용하여 최종적으로 ashing공정 단계에서 폴리이미드를 제거하여 마이크로 볼로미터 구조를 완성하였다. 이 때의 구조층으로는 PECVD 질화실리콘($SiN_x$) 박막, 감지층으로 산화바나듐($VO_x$) 박막을 사용하였다. 본 연구에서는 폴리이미드 패턴 형성시 건식식각 공정조건 변수에 따라서 패턴의 기울기를 조절하여 폴리이미드 측면에서 발생되는 불 균일한 박막 증착과 패터닝 문제를 개선하였다. 또한 저응력의 질화실리콘 박막을 사용하여 잔류응력에 의한 열적고립 구조의 뒤틀림 현상을 완화하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.558-561
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• 2001

Vanadium oxide ($VO_x$) thin films are very good candidate material for uncooled infrared (IR) detectors due to their high temperature coefficient of resistance (TCR) at room temperature. But, the deposition of $VO_x$ thin films showing good electrical properties is very difficult in micro bolometer fabrication process using sacrificial layer removal because of its low process temperature and thickness of thin films less than $1000{\AA}$. This paper presents a new fabrication process of $VO_x$ thin films having high TCR and low resistance. Through sandwich structure of $VO_{x}(100{\AA})/V(80{\AA})/VO_{x}(500{\AA})$ by sputter method and post-annealing at oxygen ambient, we have achieved high TCR more than $-2%/^{\circ}C$ and low resistance less than $10K\Omega$ at room temperature.

• Journal of Ocean Engineering and Technology
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• v.18 no.1
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• pp.69-74
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• 2004

In general, the protection method of Shell and Tube Type heat exchanger for a vessel has been applied as a sacrificial anode, which is attached at the inner side of the shell. However, this is an insufficient protection method for tube. Therefore, a more suitable method, such as the impressed current cathodic protection for tube protection, is required. Al-brass is the raw material of tubes for heat exchanger of a vessel where seawater is used for cooling the water. It has a high level of heat conductivity, excellent mechanical properties, and a high level of corrosion resistance, due to a cuprous oxide (Cu$_2$O) layer against th seawater. However, in actuality, it has been reported that Al-brass tubes for heat exchanger of a vessel can produce local corrosion, such as stress corrosion cracking (SCC). This paper studied the effect of impressed potential on the stress corrosion cracking of Al-brass for impressed current cathodic protection in 3.5% NaCl +0.1% NH$_4$OH solution, under flow by a constant displacement tester. Based on the test results, the latent time of SCC, stress corrosion crack propagation, and the dezincification phase of Al-brass are investigated.