• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.2 no.2
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• pp.57-62
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• 2009

In this paper, we proposed the metal tag antenna of PIFA structure with an isotropic radiation pattern when tag attached the metal material. The antenna consist of antenna body, horizontal patch and ground, and inserted a substrate with high dielectric constant between the antenna body and ground in order to miniaturize the antenna size. The antenna body with symmetric structure is designed to produce an oppositely directed currents. The simulation shows the impedance bandwidth has 20 MHz (900 ~ 920 MHz) and the maximum radiation gain satisfy the -10 dBi and -15 dBi when the tag is in air and attach the metal material. Also, the proposed antenna operates with an isotropic radiation pattern due to satisfy the gain deviation lower than 6 dB, respectively.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.97.2-97.2
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• 2011

Pt-Ru and Pt-Ni bimetallic catalysts were prepared and tested for heavy hydrocarbon reforming. Metals were supported on CGO($Ce_{0.8}Gd_{0.2}O_{2.0-x}$) by incipient wetness method. The prepared catalysts were characterized by Temperature programmed reduction(TPR). Oxidative steam reforming of n-dodecane was conducted to compare the activity of the catalysts. The reforming temperature was varied from $500^{\circ}C$ to $800^{\circ}C$ at fixed $O_2$/C of 0.3, $H_2O$/C of 3.0 and GHSV of 5,000/h.Reduction peaks of metal oxide, surface CGO and bulk CGO were detected. Reduction temperature of metal oxide decreased over the bi-metallic catalysts. It is considered that interaction between metals leads to decrease interaction between metal and oxygen. On the other hands, reduction temperatures of surface CGO were dectected in the order of Pt-Ru > Pt-Ni > Pt. low reduction temperatures of surface CGO indicates the low activation energy for oxygen ion conduction to metal. Oxygen ion conduction is known as de-coking mechanism of ionic conducting supports such as CGO. In activity test, fuel conversion was in the same order of Pt-Ru > Pt-Ni > Pt. Especially, 100% of fuel conversion was obtained over Pt-Ru catalysts at $500^{\circ}C$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.425-425
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• 2008

Bismuth-antimony-telluride based thermoelectric thin film materials were prepared by metal organic vapor phase deposition using trimethylbismuth, triethylantimony and diisopropyltelluride as metal organic sources. A planar type thermoelectric device has been fabricated using p-type $Bi_{0.4}Sb_{1.6}Te_3$ and n-type $Bi_2Te_3$ thin films. Firstly, the p-type thermoelectric element was patterned after growth of $4{\mu}m$ thickness of $Bi_{0.4}Sb_{1.6}Te_3$ layer. Again n-type $Bi_2Te_3$ film was grown onto the patterned p-type thermoelectric film and n-type strips are formed by using selective chemical etchant for $Bi_2Te_3$. The top electrical connector was formed by thermally deposited metal film. The generator consists of 20 pairs of p- and n-type legs. We demonstrate complex structures of different conduction types of thermoelectric element on same substrate by two separate runs of MOCVD with etch-stop layer and selective etchant for n-type thermoelectric material. Device performance was evaluated on a number of thermoelectric devices. To demonstrate power generation, one side of the device was heated by heating block and the voltage output was measured. The highest estimated power of 1.3mW is obtained at the temperature difference of 45K. We provide a promising approach for fabricating thin film thermoelectric generators by using MOCVD grown thermoelectric materials which can employ nanostructures for high thermoelectric properties.

• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.332-333
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• 2003

Optical Add／Drop Multiplexer (OADM)은 WDM, 즉 파장분할을 이용하여 보다 많은 정보를 보다 빠르게 전송할 수 있는 광통신 시스템에서 가장 중요한 소자 중의 하나이다. WDM (특히, DWDM) 시스템에서는 광신호의 전송 대역이 파장 영역에서 0.8 nm 정도의 매우 좁은 간격으로 배치되기 때문에, 파장 가감을 위한 광필터들은 높은 파장 정확성과 환경적 조건에 대한 안정성을 가져야만 한다. 그러나 광섬유 단주기 격자의 온도 의존성은 일반적으로 0.01 nm／$^{\circ}C$ 정도로 너무 크기 때문에 WDM 시스템에서 응용되기 위해서는 패키징을 통한 온도 보상이 필요하다. (중략)

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.483-484
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• 2006

In this paper, we fabricated the organic bi-stable devices under the different condition from the other groups and analyzed the electrical characteristics. Then we investigated the effects of the device structure such as organic layer thickness, middle metal layer thickness and middle metal layer deposition rate on the memory characteristics.

• Proceedings of the Korean Ceranic Society Conference
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• 2003.10a
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• pp.165.2-165
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• 2003

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.448-451
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• 2005

It was observed that after unloading or removal of the load from the specimen subjected to bending stress, partial or full elastic spring back occurred and considerable stresses have resulted while plastic deformation was considered. ABAQUS is a suite of powerful engineering simulation programs, based on the finite element method. In this paper, it was used as the main tool to analyze elastic and plastic deformations of hi-material metal joint. In the case of elastic deformations, the results were comparable to the theoretical data. Plastic deformations and residual stresses of hi-material metal joint under bending moment were obtained by ABAQUS; where the theory needs to be studied and improved further to verify the results.

• Progress in Superconductivity
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• v.3 no.1
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• pp.91-94
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• 2001

By varying fabricating process, precursor powders with different initial conditions were prepared. Subsequently, Bi-2223/Ag tapes were made through these powders. The effects of precursor powders on the phase evolution and Jr properties of Bi-2223/Ag tapes were studied along with several thermomechanical cycles. Our results showed that the initial conditions of precursor powders could strongly influence the phase formation rate and $J_{c}$ value in final tapes. The factors of precursor powders that influence the phase formation and $J_{c}$ of Bi-2223/Ag tapes must be studied and optimized in combination.ion.

• Corrosion Science and Technology
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• v.5 no.3
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• pp.94-98
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• 2006

The next generation nuclear power reactor will use Pb-Bi as the cooling material. The steel structure materials such as HT-9 used in the reactor suffer from corrosion when they are exposed to high temperature Pb-Bi. Therefore corrosion should be prevented to use Pb-Bi as the coolant material without any safety problem. One method is to control the oxygen content in Pb-Bi. An appropriate amount of oxygen in Pb-Bi can produce a thin oxide layer on steel, and this layer protects the steel from corrosion attack. Since the required oxygen content in Pb-Bi is in the range of $10^{-5}$ to $10^{-7}$ wt%, this small oxygen content can be controlled by flowing a mixture of hydrogen gas and water vapor. The stagnant corrosion test of HT-9 samples was performed by controlling the oxygen content up to 2,000 hours. The corrosion behavior of HT-9 was analyzed at the temperatures of $500^{\circ}C$ and $650^{\circ}C$ with a reduced condition and a oxygen content of $10^{-6}$ wt%.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.180-180
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• 2003

FRAM (Ferroelectric Random Access Memory)은 DRAM(Dynamic Random Access Memory)in 커패시터 재료을 상유전체 물질에서 강유전체 물질로 대체하여 전원 공급이 차단되어도 정보를 기억할 수 있고, 데이터의 고속처리가 가능하고 저소비전력과 집적화가 뛰어난 차세대 메모리 소자이다. 본 연구에서는 n-Well/P-Si(100) 기판위에 $Y_2$O$_3$ 박막을 중간층 (buffer layer)으로 사용하여 (Bi,La) Ti$_3$O$_{12}$ (BLT) 강유전체 박막을 졸-겔 방법으로 형성하여 MFM(I)S(Metal Ferroelectric Metal (Insulation) Silicon) 구조의 커패시터 및 전계효과형 트랜지스터(Field Effect Transistor) 소자를 제작하였다. 제작된 소자에 대해 형상학적, 전기적 특성을 조사, 분석하였다.