• Advances in nano research
• /
• 제8권2호
• /
• pp.157-167
• /
• 2020

This paper studies forced vibrational behavior of porous nanocrystalline silicon nanoshells under radial dynamic loads using strain gradient theory (SGT). This type of material contains many pores inside it and also there are nano-size grains which define the material character. The formulation for nanocrystalline nanoshell is provided by first order shell theory and a numerical approach is used in order to solve nanoshell equations. SGT gives a scale factor related to stiffness hardening provided by nano-grains. For more accurate description of size effects due to nano-grains or nano-pore, their surface energy influences have been introduced. Surface energy of inclusion exhibit extraordinary influence on dynamic response of the nanoshell. Also, dynamic response of the nanoshell is affected by the scale of nano-grain and nano-pore.

• Corrosion Science and Technology
• /
• 제7권4호
• /
• pp.237-242
• /
• 2008

Physical properties of water, such as dielectric constant and ionic product, significantly vary with the density of water. In the supercritical conditions, since density of water widely varies with pressure, pressure has a strong influence on physical properties of water. Dielectric constant represents a character of water as a solvent, which determines solubility of an inorganic compound including metal oxides. Dissociation equilibrium of an acid is also strongly dependent on water density. Dissociation constant of acid rises with increased density of water, resulting in drop of pH. Density of water and the density-related physical properties of water, therefore, are the major governing factors of corrosion and environmentally assisted cracking of metals in supercritical aqueous solutions. This paper discusses importance of "physical properties of water" in understanding corrosion and cracking behavior of alloys in supercritical water environments, based on experimental data and estimated solubility of metal oxides. It has been pointed out that the water density can have significant effects on stress corrosion cracking (SCC) susceptibility of metals in supercritical water, when dissolution of metal plays the key role in the cracking phenomena.

• 한국주거학회:학술대회논문집
• /
• 한국주거학회 2005년도 추계학술대회 논문집
• /
• pp.63-66
• /
• 2005

The purpose of this study is to suggest the modeling of ubiquitous environments according to the analysis of user's behaviors focused on the living area within the house. Recently, with appearing 'Ubiquitous environments', the applications of ubiquitous technologies on the our environment adopt a new paradigm. This new paradigm leads to the possibility of creating more intellectual dwelling environment according to user's behaviors. This paper suggests to change our dwelling by considering both engineering technology and the character of dwelling, because the house should provide causes humans with comfortability. Therefore, we need to understand user's behaviors in the dwelling, towards user friendly environment. Also, it very important for us to configure proper sensors and technologies by the priority based on user's behaviors. To sum up, this study is aimed to analyze user's behaviors and then, to suggest the guideline for users offering optimal ubiquitous environments.

• 한국조경학회지
• /
• 제26권3호
• /
• pp.152-161
• /
• 1998

The purpose of this study was to identify remained real state of groves of enclosed village in human settlement circle. That was practiced in case of Chinan-Gun region which traditional elements had well been conservated. 48 village groves were found by site survey, reference and interview in Chinan-Gun region. 27 groves of 48 village groves were clarified as complementing village grove by classification of grove character. It was identified through survey that many were partially destructed by development and human use. The results of this study showed general, socio-behavioral characteristics, characteristics of forest state and vegetation structure of complementing village groves. Length, area, form, type, motive, location, relationship of those were analyzed to identify general characteristics. Facilities, human behavior and ownership of those were analyzed to identify socio-behavoral characteristics. Dominent species, appearing rate, height, width, density and biodiversity of upper trees were analyzed to identify forest state and vegetation structure. Interrelation of each factor were analiged and comparative review with previous studies was achieved.

• 한국표면공학회지
• /
• 제27권1호
• /
• pp.29-35
• /
• 1994

The effects of coating of 3$\mu\textrm{m}$ thickness on the mechanical property of alumina after heat treatment at 100$0^{\circ}C$ for 30minutes under $10^{-6}$torr vacuum was quantified in terms of modulus of rupture(MOR) using Weibull plot. While the copper coating did not change MOR of alumina due to the nonwetting behavior of Cu on $Al_2O_3$, the reactive titanium metal coating caused a noticeable 29% reduction in averaged MOr strength. This was related with the combined effects of microcracks in coating formed during heat treatment and good bonding character between Ti and $Al_2O_3$. The effect of cosputtering of Ti and Cu, bilayer coatings of Cu/Ti and Ti/Cu were also investigated. It was found that Ti, cosputtered, Cu/ti and Ti/Cu coatings reduced MOR strength of alumina in the order listed. This was correlated with the amount of Ti at coating/alumina inter-face associated with a coated layer or segregation of Ti during heat treatment.

• 한국실내디자인학회:학술대회논문집
• /
• 한국실내디자인학회 2005년도 추계학술발표대회 논문집
• /
• pp.111-114
• /
• 2005

The purpose of this study is to suggest configuration methods of sensor according to user's behaviors in the ubiquitous house. Recently, with appearing the concept of 'Ubiquitous', the applications of ubiquitous technologies on the our environment adopt a new paradigm. This new paradigm leads to the possibility of creating more intellectual dwelling environment according to user's behaviors. This paper suggests to change our dwelling by considering both engineering technology and considering the character of dwelling, because the house should provide causes humans with comfortability. Therefore, we need to understand user's behaviors in the dwelling, towards user friendly environment.

• 한국정보과학회:학술대회논문집
• /
• 한국정보과학회 2004년도 봄 학술발표논문집 Vol.31 No.1 (B)
• /
• pp.475-477
• /
• 2004

이동전화 가입자 수의 폭발적 증가와 전송속도 향상으로 고성능 이동전화인 스마트폰이 주목을 받고 있으며, 스마트폰상에서 작동하는 지능형 서비스의 필요성이 커지고 있다. 본 논문에서는 스마트폰에서 지능형 서비스를 구현하는 방법으로 지능형 캐릭터를 제안한다. 캐릭터는 사용자가 친숙하게 느낄 수 있어 지능형 서비스의 좋은 인터페이스가 될 수 있다. 제안하는 캐릭터는 베이지안 네트워크를 이용하여 추론된 사용자의 감정 상태, 바쁨의 정보 등의 정보와 스마트폰에서 수집된 디바이스 상태에 기반하여 행동 선택을 행동 선택을 하여 디바이스와 사용자의 상태를 반영한다. 실제 작동 예를 통해 제안하는 캐릭터의 유용성을 보인다.

• Bulletin of the Korean Chemical Society
• /
• 제16권10호
• /
• pp.929-933
• /
• 1995

The electronic band structure and electrical properties of KMo4O6 containing chains of condensed molybdenum octahedra are analyzed by means of the extended Hu&ckel tight-binding method. KMo4O6 has partially filled bands of 1D as well as 3D character. They also exhibit the anisotropic band dispersions with bandwidths much larger along the c* axis than along the directions perpendicular to it. Thus, conduction electrons are essentially delocalized along the c* direction (i.e., the chain of condensed molybdenum octahedra) in the solid. The 1D band of two partially filled d-block bands leads to Fermi surface nesting with the wave vector q=0.3c*. The CDW instability due to this nesting is expected to cause the phase transition associated with the resistivity anomaly at low temperature. The characteristics of metallic behavior in the crystallographic ab plane are explained on the basis of the unnested 2D Fermi surfaces.

• Bulletin of the Korean Chemical Society
• /
• 제20권10호
• /
• pp.1149-1152
• /
• 1999

1H NMR spectrum of a DMF-d7 solution containing 4-aminopyrimidine and [SiW11CoIIO39]6- (SiW11Co) shows separate peaks from two linkage isomers, a and b, in which N(1) and N(3) of the pyrimidine ring are coordinated to SiW11Co, respectively. The signal from the amine group in the isomer a exhibits temperature dependence that is characteristic of a two-site exchange problem. Rates of internal rotation of the amine group were determined by simulating the NMR spectra at 5-35℃. The amine group of free 4-aminopyrimidine also shows temperature-dependent spectra at lower temperatures; rates of internal rotation at (-25)-25℃ were determined. The internal rotation of the amine group in the complex is much slower than that for free 4-aminopyrimidine, indicating that π-character of the C-N bond increases on coordination to SiW11Co. The amine group in the isomer b does not show such behavior. It is probable that hydrogen bonding between N-H and a bridging oxygen atom of SiW11Co prevents it from rotating at low temperatures.

• Computers and Concrete
• /
• 제24권1호
• /
• pp.51-61
• /
• 2019

Compressive ability is one of the most important mechanical properties of concrete material. The compressive failure process of concrete is pretty complex with internal tension, shear damage and friction between cracks. To simulate the complex fracture process of concrete at meso level, methodology for meso-structural analysis of concrete specimens is developed; the zero thickness cohesive elements are pre-inserted to simulate the crack initiation and propagation; the constitutive applied in cohesive element is established to describe the mechanism of crack separation, closure and friction behavior between the fracture surfaces. A series of simulations were carried out based on the model proposed in this paper. The results reproduced the main fracture and mechanical feature of concrete under compression condition. The effect of key material parameters, structure size, and aggregate content on the concrete fracture pattern and loading carrying capacities was investigated. It is found that the inner friction coefficient has a significant influence on the compression character of concrete, the compression strength raises linearly with the increase of the inner friction coefficient, and the fracture pattern is sensitive to the mesostructure of concrete.