• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
• /
• pp.24-27
• /
• 2009

Solid-state dye-sensitized solar cells (DSSCs) have been constructed employing supramolecular electrolytes with multiple hydrogen bonding. A supramolecule was facilely synthesized by one-pot reaction between the amines of methyl isocytosine (MIC) and the epoxy groups of poly(ethylene glycol diglycidyl ether) (PEGDGE) to produce quadruple hydrogen bonding units. Hydrogen bonding interactions and dissolution behavior of salt in supramolecular electrolytes are investigated. The ionic conductivity of the supramolecular electrolytes with ionic liquid, i.e. 1-methyl-3-propylimidazolium iodide (MPII) reaches $8.5{\times}10^{-5}$ S/cm at room temperature, which is higher than that with metal salt (KI). A worm-like morphology is observed in the FE-SEM micrographs of $TiO_2$ nanoporous layer, due to the connection of $TiO_2$ nanoparticles resulting from adequate coating by electrolytes. DSSCs employing the supramolecular electrolytes with MPII and KI exhibit an energy conversion efficiency of 2.5 % and 0.5 %, respectively, at 100 $mW/cm^2$, indicating the importance of the cation of salt. Solar cell performances were further improved up to 3.7 % upon introduction of poly(ethylene glycol dimethyl ether) (PEGDME) with 500 g/mol.

• 보존과학연구
• /
• 통권21호
• /
• pp.77-99
• /
• 2000

Tumuli located in Chodang-dong in Kangreung City are sitesexcavated by the Museum of Kangreung University in 1993.Ofthese sites, a gilt bronze crown and gilt bronze sword with ring pommel with a tri-leaf ornament were excavated from the B-16tumulus. Underneath the gilt bronze crown was the gilt bronzes word with ring pommel with tri-leaf ornament, and these artifacts were treated with Polyurethane foams on the spot followed by special measures for conservation. This manuscript describes measures for conservation andanalysis with regard to the gilt bronze crown, gilt bronze sword with ring pommel with tri-leaf ornament and gilt bronze beltornaments. Bronze on the gilt bronze crown was completely corroded, therefore it was consolidated together with soil in the back of the artifact with Paraloid B72 after cleaning. Polyurethanefoams bottom was finished by applying the mixture of Epoxy resinAW106 and HV935K with soil. On the sword with ring pommel, the wooden part of the hilt was coated with Paraloid B72 (in Xylene) and the blade was consolidated with Paraloid NAD-10 30% after desalting with Sodium sesquicarbonate method. The gilt bronzebelt ornaments were treated with 3% Benzotriazole, coated with Paraloid B72 and then joined by using Cyanlacrylate. Specimens for the gilt bronze crown and gilt bronze belt ornaments were produced and gilding layers were examined under a metallographic microscope. The gilt bronze crown and the gilt bronze belt ornament maintained relatively good gilding quality with uniform gilding layers. Analysis of wood for the sheath of the sword with ring pommel revealed it to be Juglans mandshurica. Further more, analysis of constituents for a blue colored grassbead from dissolution of Polyurethane foams found it to be from the $Na_2O$-CaO-$AI_2O_3$-$SiO_2$ family.

• 한국결정성장학회지
• /
• 제7권2호
• /
• pp.284-291
• /
• 1997

V-Ti(V-rich) 수소저장합금을 기초(base)로 하여 2가지 타입(type)의 전극을 제조하였다. 첫째로 V-Ti 합금에 Ni 분말을 혼합하여 성형한 후 급속가열방법으로 소결하여 전극을 제조하였다. 둘째로 Ni을 V-Ti 합금과 합금화한 V-Ti-Ni 3원계 수소저장합금에 Ni, PTFE 분말을 혼합하여 냉간압축으로 성형하여 전극을 제조하였다. 이와같이 제조된 전극으로 싸이클에따른 충/방전 실험을 한 결과, 모든 전극에 있어 10싸이클 이내에 퇴화(degradation)가 일어났다. 충방전 실험후 전해질내의 조성분석결과 Ti에 비해 V이 많이 전해질 내에 용해되었으며 합금원소의 용해에 의한 표면 형상의 변화가 관찰되었고, 전극표면에 매우 passive 한 Ti-oxide($TiO_2$)가 형성되었다. Ti-oxide($TiO_2$)는 전기전도도가 매우 낮고, 수소에대한 확산계수(diffusivity)도 낮기때문에 전극표면에 형성된 $TiO_2$층은 충/방전 싸이클동안 방전용량을 크게 감소시키는 것으로 나타났다.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 1992년도 추계학술대회 논문집
• /
• pp.77-81
• /
• 1992

The purpose of this research was th evaluate conductivity of electricity of Ge-Se-Bi system Chalcogenide glass as a amorphous semiconductor by observing its dissolution and crystallization. In this experiment. Ge-Se-Bi metal powder in the rage of $Ge_{12-25}$, $Se_{65-85}$, $Bi_{2.5-15}$ was used as the sample ore. The ore was. put into a vaccous quartz tube and then melted. The condition of heat treatment was to dispose it to $1000^{\circ}C$ heat for 10 hours and then rapidly quenched it at $3834^{\circ}C$/see. The crystallization of the fused sample ripened as the change of temperature and time, after the crystal core was formell. At that time it was possible to observe the state that $Bi_2Se_3$ and $GeSe_2$ were crystallized. In the experiment of making memberance, the memberance was produced by using the previously experimented bulk sample. And decrystalization was well progressed when Ge was over 15 at %, Se was over 70 at %, and Bi was under 10 at%. As for bulk. when Ge was fixed to 20 at %, the conducting of electricity was increased as Bi gained at %. In the case of memberance, the conductivity was much more increased than that of bulk sample as the increase of at the increase of at % of Bi. In the experiment on $Ge_{20}$, $Se_{77.5}$ and $Bi_{2.5}$, the crystallization sswas most vigorous when they were kept at $330^{\circ}C$ for 4 hours.

• 한국표면공학회지
• /
• 제41권2호
• /
• pp.69-75
• /
• 2008

Electrochemical behaviors of surface modified and MC3T3-E1 cell cultured Ti-30Ta alloys have been investigated using various electrochemical methods. The Ti alloys containing Ta were melted by using a vacuum furnace and then homogenized for 6 hrs at $1000^{\circ}C$. MC3T3-E1 cell culture was performed with MC3T3-E1 mouse osteoblasts for 2 days. The microstructures and corrosion resistance were measured using FE-SEM, XRD, EIS and potentiodynamic test in artificial saliva solution at $36.5{\pm}1^{\circ}C$. Ti-Ta alloy showed the martensite structure of ${\alpha}+{\beta}$ phase and micro-structure was changed from lamellar structure to needle-like structure as Ta content increased. Corrosion resistance increased as Ta content increased. Corrosion resistance of cell cultured Ti-Ta alloy increased predominantly in compared with non cell cultured Ti- Ta alloy due to inhibition of the dissolution of metal ion by covered cell. $R_p$ value of MC3T3-E1 cell cultured Ti-40 Ta alloy showed $1.60{\times}10^6{\Omega}cm^2$ which was higher than those of other Ti alloy. Polarization resistance of cell-cultured Ti-Ta alloy increased in compared with non-cell cultured Ti alloy.

• Korean Chemical Engineering Research
• /
• 제50권1호
• /
• pp.118-127
• /
• 2012

고분자전해질 연료전지용 분리판 소재로 스텐레스 강의 내식성과 전기전도성을 향상시키기 위해 표면을 TiN(titanium nitride) 또는 Ti/TiN(titanium/titanium nitride)으로 코팅하여 연료전지 운전환경에서 표면 코팅층의 물성 변화를 조사하였다. 200시간의 연료전지 운전에서 표면 코팅층의 부식, 균열(crack), 박리, 표면 화학조성 변화 등을 분석하여 코팅된 TiN 또는 Ti/TiN 박막의 역할을 규명하고자 하였다. 스텐레스 강 분리판의 전기전도도와 부식저항성은 소재 표면에 질화층 박막을 코팅함으로써 증가하였으나 연료전지 환경하에서 운전시 코팅된 박막의 부식과 박리현상이 SUS316L-Ti/TiN을 제외하고 현저히 발생하였다. TiN 코팅층과 하부 기재 사이에 Ti 중간층을 도입함으로써 TiN 박막의 밀착성이 향상되고 또한 코팅층의 두께 증가로 부식 위험성이 감소하는 것을 관찰하였다.

• Corrosion Science and Technology
• /
• 제16권1호
• /
• pp.1-7
• /
• 2017

When aiming for an increased and more sustainable use of metals a thorough knowledge of the corrosion phenomenon as function of the local metal microstructure is of crucial importance. In this work, we summarize the information presented in our previous publications[1-3] and present an overview of the different local (electrochemical) techniques that have been proven to be effective in studying the relation between different microstructural variables and their different electrochemical behavior. Atomic force microscopy (AFM)[1], scanning electrochemical microscopy (SECM)[2], and electrochemical scanning tunneling microscopy (EC-STM)[3] were used in combination with electron backscatter diffraction (EBSD). Consequently, correlations could be identified between the grain orientation and grain boundary characteristics, on the one hand, and the electrochemical behavior on the other hand. The grain orientation itself has an influence on the corrosion, and the orientation of the neighboring grains also seems to play a decisive role in the dissolution rate. With respect to intergranular corrosion, only coherent twin boundaries seem to be resistant.

• 대한화학회지
• /
• 제44권6호
• /
• pp.547-555
• /
• 2000

대구${\cdot}$경북지역의 상수원 및 공업용수로서 사용되고 있는 낙동강 중${\cdot}$상류지역 하천 표류수의 수질을 분석하고, 하상 퇴적층에 함유된 중금속과 유기물의 종류 및 함유량을 분석하였다. 시료 채취는 갈수기 중 6월 22, 23 양일간 안동댐 상류 청량산 도립공원 양삼교 밑을 제 1지점으로 하여, 경북 지방을 통과하는 낙동강의 최하단인 고령군 고령교까지, 주로 공단의 전후 및 하천의 합류 지점을 대상으로 총 10개 지점에서 실시하였다. 표류수의 분석은 표류수의 시험항목 중 암모니아성 질소, 아질산성 질소, COD 등 총 22개 항목에 대하여 수행하였으며, 퇴적층은 trichloroethylene 등의 유기물과 중금속 등 11개 항목에 대하여 분석하였다. 퇴적물 시료는 용출시험법 및 산분해법으로 각각 분석하여 결과를 비교하였으며, 시료 중 중금속 성분은 유도결합 플라스마 방출분광법으로 분석하였고, 기타 성분은 환경부기준 공정시험방법에 의하여 분석하였다.

• 자원리싸이클링
• /
• 제22권6호
• /
• pp.55-63
• /
• 2013

본 연구에서는 전기화학법으로 생성된 염소를 산화제로 이용하여 루테늄의 침출에 대한 연구를 수행하였다. 휘발성 루테늄산화물의 손실을 막기 위해 전 시스템이 밀폐형으로 제작된다. 루테늄의 침출의 최적조건을 조사하기 위해 pH, 온도, 전해 염소 생성시 인가전류 등의 영향을 조사하였다. 염소전해생성 시스템에 산화전류를 인가하여 염소가스를 발생시키고 침출조에 공급하여 루테늄 용해에 필요한 염소화합물을 생성시켰다. 산화제인 염소화합물의 농도가 포화상태에 도달하였을 때 루테늄 분말시료를 장입하고 침출반응을 진행하였다. 일정시간 간격으로 침출액을 채취하면서 루테늄 침출농도를 분석하였다. 본 실험결과 최적조건은 pH 10, 2 A, $40^{\circ}C$로 이 때 침출률은 88% 이다.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
• /
• pp.237.2-237.2
• /
• 2013

ReRAM cell, also known as conductive bridging RAM (CBRAM), is a resistive switching memory based on non-volatile formation and dissolution of conductive filament in a solid electrolyte [1,2]. Especially, Chalcogenide-based ReRAM have become a promising candidate due to the simple structure, high density and low power operation than other types of ReRAM but the uniformity of switching parameter is undesirable. It is because diffusion of ions from anode to cathode in solid electrolyte layer is random [3]. That is to say, the formation of conductive filament is not go through the same paths in each switching cycle which is one of the major obstacles for performance improvement of ReRAM devices. Therefore, to control of nonuniform conductive filament formation is a key point to achieve a high performance ReRAM. In this paper, we demonstrated the enhanced repeatable bipolar resistive switching memory characteristics by spreading the Ag nanocrystals (Ag NCs) on amorphous GeSe layer compared to the conventional Ag/GeSe/Pt structure without Ag NCs. The Ag NCs and Ag top electrode act as a metal supply source of our devices. Excellent resistive switching memory characteristics were obtained and improvement of voltage distribution was achieved from the Al/Ag NCs/GeSe/Pt structure. At the same time, a stable DC endurance (>100 cycles) and an excellent data retention (>104 sec) properties was found from the Al/Ag NCs/GeSe/ Pt structured ReRAMs.