• Advances in materials Research
• /
• 제5권4호
• /
• pp.279-298
• /
• 2016

Present disquisition proposes an analytical solution method for exploring the buckling characteristics of porous magneto-electro-elastic functionally graded (MEE-FG) plates with various boundary conditions for the first time. Magneto electro mechanical properties of FGM plate are supposed to change through the thickness direction of plate. The rule of power-law is modified to consider influence of porosity according to two types of distribution namely even and uneven. Pores possibly occur inside FGMs due the result of technical problems that lead to creation of micro-voids in these materials. The variation of pores along the thickness direction influences the mechanical and physical properties. Four-variable tangential-exponential refined theory is employed to derive the governing equations and boundary conditions of porous FGM plate under magneto-electrical field via Hamilton's principle. An analytical solution procedure is exploited to achieve the non-dimensional buckling load of porous FG plate exposed to magneto-electrical field with various boundary condition. A parametric study is led to assess the efficacy of material graduation exponent, coefficient of porosity, porosity distribution, magnetic potential, electric voltage, boundary conditions, aspect ratio and side-to-thickness ratio on the non-dimensional buckling load of the plate made of magneto electro elastic FG materials with porosities. It is concluded that these parameters play remarkable roles on the dynamic behavior of porous MEE-FG plates. The results for simpler states are confirmed with known data in the literature. Presented numerical results can serve as benchmarks for future analyses of MEE-FG plates with porosity phases.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.2
• /
• pp.938-941
• /
• 2003

It is well known that the state of existence of molecules on the surface of water changes during compression of the molecules. Electric methods, such as measurement of the surface potential or displacement current are also useful for investigating dynamic changes of molecular state on the water surface during compression and Transformation of molecular film occurs only usually in air-water interface, 2 dimensions domain's growth and crash are achieved. Organic thin film that consist of growth of domain can understand correct special quality of accumulation film supplying information about fine structure and properties of matter of device observing information and so on that is surface forward player and optic enemy using AFM one of SPM application by nano electronics. In this paper Langmuir (L) that is one of basis technology to manufacture of organic matter device using biology material PBDG that is kind of polypeptide that have biology adaptedness. The Experiment method used ${\pi}-A$ isotherm and BAM(Brewster Angle Microscopy), using the BAM, we can to the molecular orientation of monolayer on the water surface and directly see the morphology of the films on water subphase as well as that of the films.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
• /
• pp.435-436
• /
• 2008

Dye-sensitized Solar Cells(DSSCs) which convert incident sun light into electricity were expected to overcome global warming and depletion of fossil fuels. And it is one of study that is lately getting into the spotlight because manufacturing method is more simple and inexpensive than existing silicon solar cells. In this respect, DSSCs are in the limelight as the next generation solar cells. DSSCs are generally composed of a dye-modified $TiO_2$ photoelectrode, a Pt counter electrode, and an electrolytes containing a redox couple$(I^-/I_3^-)$. Among these elements, pt electrode were prepared by applying electric potential to FTO substrate in the $H_2PtCl_6$ solution. In this study, we report the solar cell efficiency depending on $PtCl_4$ concentration change. $PtCl_4$ concentration was 1mM, 5mM, 10mM, and 20mM, and adhered on FTO glass substrate by sintering process. When applied each $PtCl_4$ counter electrode on DSSC, the best efficiency was found at 10mM of $PtCl_4$ concentration. The catalyst promotes the movement of electron from the counter electrode to the electrolyte the higher the molarity, the better the efficiency. However, in case of 20mM, it is estimated that over-deposited $PtCl_4$ tends to restrict the movement of electron due to its bundle formation.

• 대한전자공학회논문지SD
• /
• 제39권7호
• /
• pp.16-25
• /
• 2002

본 논문에서는 반도체 집적 회로의 다층 배선 인터커넥트 사이의 기생 인덕턴스를 수치 해석적으로 계산하여 추출하는 방법과 그 적용 예를 보고한다. 기생 인덕턴스를 추출하기 위하여, 3차원 다층배선 구조물에 대해 유한요소법을 이용하여 다층 배선내에서의 전위 분포 및 전류 밀도를 계산하고, 계산된 전류 밀도로부터 자계 에너지를 계산하여 상호 인덕턴스 및 셀프 인덕턴스를 계산하였다. 시뮬레이션 결과의 정확도를 검증하기 위하여 해석적 방법으로 해석이 가능한 간단한 구조에 대하여 시뮬레이션을 수행하여 결과를 비교하였으며, 또다른 응용으로, $13{\times}10.25{\times}8.25\;{\mu}m^3$ 크기의 4비트 룸 구조에 대하여 시뮬레이션을 수행하였다. 3차원 4비트 룸 구조물의 기생 인덕턴스 추출을 위해서, 유한요소법 적용을 위한 6,358개의 노드와 31,941개의 사면체 메쉬를 생성하였으며, ULTRA 10 워크스테이션에 대해서 소요된 CPU 시간은 약 2분 30초이었으며, 20 메가바이트의 메모리를 사용하였다.

• 전자공학회논문지D
• /
• 제36D권5호
• /
• pp.44-53
• /
• 1999

본 논문에서는 반도체 집적 회로의 다층 배선 인터커넥트 사이의 기생 캐패시턴스를 수치 해석적으로 계산하여 추출하는 새로운 방법과 그 적용 예를 보고한다. 기생 캐패시턴스를 시뮬레이션을 통해 추출하기 위하여, 복잡한 형태의 3차원 대층배선 구조물을 유한요소법을 이용하여 해석하였다. 캐패시턴스를 추출하기 위한 3차원 다층배선 구조물은 3차원 변환 정보를 가진 2차원 평면 마스크 레이아웃 데이터로부터 생성하였다. 시뮬레이션 결과의 정확도를 검증을 위하여 8.0×8.0×5.0㎛\sup 3\ 크기의 영역에 평행한 두 도전층이 상하로 교차한 구조에 대하여 실험치와 비교하였다. 3차원 다층배선 구조물의 기생 캐패시턴스 추출을 위해서, 유한 요소법 적용을 위한 1,960개의 노드와 8,892개의 사면체 메쉬를 생성하였으며, ULTRA SPARC 1 워크스테이션에 대해서 소요된 CPU 시간은 28초이었으며, 4.4 메가바이트의 메모리를 사용하였다.

• 한국태양에너지학회:학술대회논문집
• /
• 한국태양에너지학회 2012년도 춘계학술발표대회 논문집
• /
• pp.400-403
• /
• 2012

$Cu_2ZnSnSe_4$(CZTSe) is emerged as a promising material for thin-film solar cells because of non-toxic, inexpensive and earth abundant more than $Cu(In,Ga)Se_2$ materials. For fabricating compound semiconductor thin-film solar cells, CdS is widely used for a buffer layer which fabricated by a chemical bath deposition method (CBD). Through the experiment, we controlled deposition temperature and mol ratio of solution conditions to find the proper grain 크기 and exact composition. The optimum CdS layers were characterized in terms of surface morphology by using a scanning electron microscope (SEM) and atomic force microscope (AFM). The optimized CdS layer process was applied on CZTSe thin-films. The thickness of buffer layer related with device performance of solar cells which controlled by deposition time. Local surface potential of CdS/CZTSe thin-films was investigated by Kelvin probe force microscopy (KPFM). From these results, we can deduce local electric properties with different thickness of buffer layer on CZTSe thin-films. Therefore, we investigated the effect of CdS buffer layer thickness on the CZTSe thin-films for decreasing device losses. From this study, we can suggest buffer layer thickness which contributes to efficiencies and device performance of CZTSe thin-film solar cells.

• 대한전기학회논문지:시스템및제어부문D
• /
• 제54권11호
• /
• pp.680-688
• /
• 2005

The electrical current generated by heart creates not only electric potential but also a magnetic field. We have observed electrophysiological phenomena of the heart by measuring components of magnetocardiogram(MCG) using 61 channel superconducting quantum interference device(SQUD) system. We have analyzed the possibility and characteristics of MCG parameters for diagnosis of ischemic heart disease. A technique for automatic analysis of MCG signals in time domain was developed. The methods for detecting the position, the interval, the amplitude ratio, and the direction of single current dipole were examined in the MCG wave. The position and interval parameters were obtained by calculating the gradients of a envelope curve which could be formed by the difference between the maximum and minimum envelope of multi-channel MCG signals. We show some differences of the frequency contour map between the normal MCG and the abnormal (ischemic heart disease) MCG. The direction of single current dipole can be defined by rotating the magnetic field according to Biot-Savart's law at each point of MCG signals. In this study, we have examined the direction of single current dipole from searching for the centroids of positive and negative magnetic fields. The amplitude ratio parameters for measuring 57 deviation consisted of A$_{T}$/A$_{R}$ and other ratios. and We developed a new analysis method, which is based on the frequency contour map of electromagnetic field. Using theses parameters, we founded significant differences between normal subjects and ischemic patients in some parameters.

• 한국응용과학기술학회지
• /
• 제17권4호
• /
• pp.248-256
• /
• 2000

We investigated the property of formation of mono-vesicle(designated nano-some) with using of the combined co-emulsifiers and phospholipid. Nano-some was prepared with hydrogenated lecithin(HL) and diethanolamine cetyl phosphate(DEA-CP) by swelling reaction. Kojic acid and kojic dipalmitate could be made stabilization by nano-some system using microfluidizer(MF). Nano-some has a good affinity to skin by means of this system. The composition was compounded by 2% of hydrogenated lecithin (phosphatidyl choline contained with 75%, 0.5% of DEA-CP and 0.5% of diglyceryl dioleate (DGDO). To make nano-some, several conditions of MF have to be considered as follows. The optimum pH was 6.0. The pressure was 10,000psi and passage temperature was at $306^{\circ}C$. The nano-some base was passed to homogenize continually 3 times through MF. The Particle size distributions of the vesicles were with in $57{\sim}75.7nm$(mean 66nm) by measuring the Zetasizer-3000. Zeta potential of vesicles with 3 times passage through MF was -24.8mV. Formations for nano-some vesicle certificated photograph by scanning electric magnification (SEM). Stability of nano-some was very good for 6months. The turbidity was very good transparency compared nano-some with liposome. It was formed the mono vesicle in the opposite direction to be formed the multi-lamellar vesicle of liposome.

• 콘크리트학회논문집
• /
• 제22권1호
• /
• pp.69-76
• /
• 2010

콘크리트의 수축으로 인한 균열가능성 평가에 있어서 대부분의 경우 콘크리트를 균질한 물질로 가정하는 방식으로 접근하고 있다. 그러나 이러한 방식으로 접근할 경우 불구속조건 하의 콘크리트에서 자기수축으로 인한 미세균열(micro-cracking) 현상을 평가하는 것이 불가능함과 동시에 콘크리트 내부의 균열 발생 현상을 이해하는데 한계가 있다. 이에 이 연구에서는 시멘트 모르타르 시험체를 가지고 실험적으로는 음향방출(acoustic emission) 장비를 사용하여 내부 균열 발생량을 측정 및 평가하였으며, 이론적인 접근방식의 일환으로 실제 모르타르 시험체로부터 구하여진 이차원 이미지를 사용하여 NIST에서 개발한 OOF code로 유한요소해석을 수행하였다. 실험 및 해석 결과, 모르타르의 내부에서 시멘트 페이스트상의 수축 및 골재의 내부구속으로 인하여 발생하는 미세균열 발생 현상을 보다 현실적으로 이해할 수 있었다.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2000년도 추계학술대회 논문집
• /
• pp.271-274
• /
• 2000

Gas sensor materials capable of detecting hydrogen gases (H$_2$) or nitrogen oxides (NO$\_$x/, primarily NO and NO$_2$) with high sensitivity have attracted much interest in conjunction with the growing concern to the protection of global environments. Beside conventional sensor materials, such as semiconductors., conducting polymers and solid electrolytes, the potential of sensor materials with a new method for detecting hydrogen gases or nitrogen oxides gas has also been tested. The breakdown voltage of porous varistors shifted to a low electric field upon exposure to H$_2$ gas, whereas it shifted to a reverse direction in an atmosphere containing oxidizing gases such as O$_3$ and NO$_2$ in the temperature range of 300 to 600$^{\circ}C$. Furthermore, it was found that the magnitude of the breakdown voltage shift, i. e. the magnitude of sensitivity, was well correlated with gas concentration, and that the H$_2$ sensitivity was improved by controlling the composition of the Bi$_2$O$_3$ rich grain boundary phase. However, NO$\_$x/ sensing properties of porous varistors have not been studies in detail. The objective of the present study is to investigate the effect of the composition of the Bi$_2$O$_3$ rich grain boundary phase and other additive such as A1$_2$O$_3$ on the hydrogen gases (H$_2$) sensing properties of porous ZnO based varistors.