http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
상황인지 커뮤니티 컴퓨팅을 위한 u-Zone 네트워크 기술
김용혁,김영한 에스케이텔레콤 (주) 2009 Telecommunications Review Vol.19 No.6
상황인지 커뮤니티 컴퓨팅은 사용자가 요구하는 특정 목적을 달성하기 위해 컴퓨팅 객체들이 협업 조직인 커뮤니 티를 구성하여 상호 상황정보를 공유하는 동시에 상황정보에 따른 협업 역할을 맡아 수행함으로 목적을 달성한다. 이 와 같은 상황인지 커뮤니티 컴퓨팅을 위한 네트워크는 상황정보의 실시간적 전송, 커뮤니티 멤버간 자가 네트워크 구 성 및 목적 기반 네트워킹 등의 요구를 만족해야 한다. 이와 같은 요구들 각각에 만족하는 기존 네트워크 기술로서 에 드혹 기술 및 서비스 인지형 네트워킹 기술, Qo S 전송 기술 등이 존재한다. 그러나 이러한 요소 기술이 융합되어 상황 인지 커뮤니티 컴퓨팅의 전반적 목적에 부합하는 네트워크 기술은 부재한 상황이다. 이에 본 논문에서는 상황인지 커 뮤니티 네트워크 구성을 위한 u-Zone(Ubiquitous-Zone) 네트워크를 제안한다. u-Zone 네트워크 기술은 에드혹 네 트워크 기술을 기반으로 한 객체간 자가 네트워크 구성 기능을 기본으로 하고 커뮤니티별 차등화 전송, 컨텍스트 인지 형 라우팅 기술, 커뮤니티 오버레이 네트워크 구성 기능 등이 종합적으로 융합되어 있는 기술로서 상황인지 커뮤니티 컴퓨팅의 요구에 만족하는 네트워크 인프라 구성방법을 제공한다.
김용혁,Kim, Yong-Hyuk 한국전기전자재료학회 2010 전기전자재료학회논문지 Vol.23 No.12
In this study, magnesium (Mg), zinc (Zn) and aluminium (Al) as anode electrode and the solution of NaCl dissolved with 2~20 wt% as electrolytes were used for the metal-air cell. The open circuit voltage, short circuit current and I-V characteristics upon different kinds of anode electrode and electrolyte concentration were investigated. The open circuit voltage, initially about 1.45 V, rises to 1.6 V during the first 10 minutes indicating the necessity of an induction time to activate the catalyst on the air cathode. The short circuit current increases with an increased concentration of NaCl, causes an increase in the conductivity of the electrolyte solution, but the open circuit voltage did not under undergo influence of electrolyte. From NaCl 20 wt% electrolyte, the maximum output power of the magnesium electrode materials was measured with 177mW. It is found that the power characteristics of metal-air cell could be improved by using magnesium electrode materials in the NaCl electrolyte.
PZT/Epoxy (1-3형) 복합재료의 두께변화에 따른 압전특성
김용혁,김호기,김진수,이덕출 한국세라믹학회 1988 한국세라믹학회지 Vol.25 No.1
In this paper, piezoelectric composite materials of 1-3 connectivity were prepared by using "dicing-filling" technique with PZT ceramics and epoxy polymers, and the dependence of piezoelectric properties on the thickness of specimens was investigated. In case that the PZT volume percent is 18.1%, according to an increment of thickness, the dielectric constant of composites( 33) is unchangeable, which is about 200, the piezoelectric coefficient (d33) is somewhat increased, which is about 240-280 (PC/N) and the electromechanical coupling factor of thickness mode(kt) is proportioned, but radial mode(kp) is constant.
김용혁,Kim, Yong-Hyuk 한국전기전자재료학회 2010 전기전자재료학회논문지 Vol.23 No.6
A new method for the poling of piezoelectric ceramics with an air insulation medium in stead of silicon oil is described. A similar variation of electromechanical coupling coefficient $K_t$, for an air medium is observed in comparison to that of the material poled by the conventional poling method using a silicon oil medium. Different poling parameters such as dielectric constant $\varepsilon^T$ and frequency deviation ${\Delta}f$ are studied as well as the influence on the aging effect. The required poling factors to achieve the optimal piezoelectric characteristics are electric field, 2 kV/mm, temperature $100^{\circ}C$, and poling time 30 Min. From this result electric field 3 kV/mm atmosphere airs there being will be able to use with the polarization insulation medium about the piezoelectric material, confirmed.
동시 진공증착한 Cu-Co 미세입상 합금박막의 자기 및 자기저항 특성
김용혁,이성래,오용주 대한금속재료학회(대한금속학회) 1995 대한금속·재료학회지 Vol.33 No.4
Magnetic and magnetoresistance properties as functions of Co composition and annealing temperatures were investigated in the Cu_(1-x)Co_x (x=0.2∼0.4) alloy films deposited by thermal co-evaporation. The MR ratio of 12.5% at room temperature which was the largest among the reported values was obtained in the 25 at.%Co-Cu granular alloy film aged at 500℃ for 140 minutes. At higher measuring temperature and limited external field, the maximum MR ratio occurs for larger Co size. In the low Co concentration($lt;25at.%) alloy films, they behaved mainly as paramagnetic in the as-deposited state at room temperature and above that composition, it showed the ferromagnetic character. The enhanced MR ratio up to annealing temperature of 500℃ was due mainly to the reduction of the Cu matrix resistivity, which resulted from the Co precipitation and Cu matrix grain growth. The MR ratio and the magnetization decreased by raising the annealing temperature from 500℃ to higher temperature. These were thought to be due to re-solution of precipitated Co back into the Cu matrix at higher temperature. The Co content of the diffused interface layer decreased and a result of that, the interface spin-dependent scattering power decreased.
김용혁,이덕출 한국전기전자재료학회 1995 電氣電子材料學會誌 Vol.8 No.1
Electrical properties of ZnO ceramics based on Bi oxide was investigated in relation to sintering temperature. In the temperature range >$1150^{\circ}C$ to >$1350^{\circ}C$ the grain size increased from 9.mu.m to 20.mu.m when the sintering temperature was raised. The leakage current in the low voltage range increased as the potential barrier decreases, which is caused by increasing the grain size at high temperature. The dielectric characteristics of the ZnO ceramics was also affected by sintering temperature. Large dielectric constant was attributed, to the grainboundary layer of polycrystalline ZnO ceramics and decreasing grainboundary width. The variation of breakdown voltage with sintering temperature was attributed to the change of the donor concentration in the ZnO grain and grain size. The results showed that breakdown voltage increased decreasing grain size and donor concentration. Nonohmic coefficient was associated with the lower breakdown voltage per grainboundary layer due to the grain growth and higher donor concentration.