• Architectural research
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• 제11권1호
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• pp.7-14
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• 2009

In this paper, we take advantage of Wavelet Transform to identify damping ratios of membrane structures under wind action. Due to the lightweight and flexibility of membrane structures, they are very sensitive to the wind load, and show a type of fluid-structure interaction phenomenon simultaneously. In this study, we firstly obtain the responses of an air-supported membrane structure by ADINA with the consideration of this characteristic, and then conduct Wavelet Transform on these responses. Based on the Wavelet Transform, damping ratios could be obtained from the slope of Wavelet Transform in a semi-logarithmic scale at a certain dilation coefficient. According to this principle, damping ratios could eventually be obtained. There are two numerical examples in this study. The first one is a simulated signal, which is used to verify the accuracy of the Wavelet Transform method. The second one is an air-supported membrane structure under wind action, damping ratios obtained from this method is about 0.05~0.09. The Wavelet Transform method could be regarded as a very good method for the the damping analysis, especially for the large spatial structures whose natural frequencies are closely spaced.

• 한국응용과학기술학회지
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• 제6권2호
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• pp.59-65
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• 1989

The rate constants of the hydrolysis of cinnamanilide derivatives were determined UV spectrometry in $H_2SO_4\;(5{\sim}20N)$, NaOH($5{\sim}11N)\;at\;50{\sim}110^{\circ}C$ and rate equation could be applied over a strong acid and strong base were obtained. Final product of the hydrolysis was a cinnamic acid. The ${\rho}$ values obtained from the slope of linear plots of log $k_{abs}$ vs. Hammet $t{\sigma}$ constants were slightly negatives, Substituents on cinnamanilide showed a relatively small effect, with hydrolysis facilitated be electron donating group. Activation energy(Ea)was also calculated for the hydrolysis of the cinnamanilide. From this reaction rate equation, substituent effect and experimental of rate constants, that the hydrolysis of cinnamanillde was Initiated by the netural molecule of $H_2O$ which do not dissociate at strong acid, and proceeded by hydroxide ion at strong base.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.1602-1610
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• 2005

In this study was investigated and analyzed of damage characteristics for infrastructures by typhoon that have been many occur. The objective Structures were the road and hydraulic structure. The road structure was included the cut-slopes, retaining walls and bridges. The hydraulic structure is divided with the dike, small-scale dam, reservoir and floodgate. The analysis result of the bridge damage cause is river bottom height increase and passage ability decrease. The principal damage reasons of the cut-slope structure are weakening the ground due to the localized torrential downpour and drainage defective. Also, the principal damage reasons of the small-scale dam, reservoir, dike and the floodgate are continuous collapse of dike beside the floodgate.And we divided a typhoon damage occurrence cause with artificial and natural. As the result of analysis, the many damage occurrence cause will be removed by system improvement and technical development.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2004년도 추계학술발표대회 논문집
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• pp.69-72
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• 2004

A new three-node triangular shell element based on higher order zig-zag theory is developed for laminated composite shells with multiple delaminations. The present higher order zig-zag shell theory is described in a general curvilinear coordinate system and in general tensor notation. All the complicated curvatures of surface including twisting curvatures can be described in an exact manner in the present shell element because this element is based on geometrically exact surface representation. The displacement field of the proposed finite element includes slope of deflection, which requires continuity between element interfaces. Thus the nonconforming shape function of Specht's three-node triangular plate bending element is employed to interpolate out-of-plane displacement. The present element passes the bending and twisting patch tests in flat surface configurations. The developed element is evaluated through the eigenvalue problems of composite cylindrical shells with multiple delaminations. Through the numerical examples it is demonstrated that the proposed shell element is efficient because it has minimal degrees of freedom per node. The present shell element should serve as a powerful tool in the prediction of natural frequency and modes of multi-layered thick laminated shell structures with arbitrary-shaped multiple delaminations.

• Structural Engineering and Mechanics
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• 제57권6호
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• pp.989-1014
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• 2016

This paper deals with the analysis of the natural frequencies, mode shapes of an axially loaded beam system carrying ends consisting of non-concentrated tip masses and three spring-two mass sub-systems. The influence of system design and sub-system parameters on the combined system characteristics is the major part of this investigation. The effect of material properties, rotary inertia and shear deformation of the beam system is included. The end masses are elastically supported against rotation and translation at an offset point from the point of attachment. Sub-systems are attached to center of gravity eccentric points out of the beam span. The boundary conditions of the ordinary differential equation governing the lateral deflections and slope due to bending of the beam system including developed shear force frequency dependent terms, due to the sub.system suspension, have been formulated. Exact formulae for the modal frequencies and the modal shapes have been derived. Based on these formulae, detailed parametric studies are carried out. The geometrical and mechanical parameters of the system under study have been presented in non-dimensional analysis. The applied mathematical model is presented to cover wide range of mechanical, naval and structural engineering applications.

• 한국터널공학회:학술대회논문집
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• 한국터널공학회 2005년도 학술발표회 논문집
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• pp.87-104
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• 2005

Rock masses represent natural systems that are inherently complex and in which multiple mechanisms occur. Rock engineering systems such as tunnel and slope interact with surrounding systems through an exchange of both mass and energy. Accordingly the complex nature of rock masses calls for a system approach, and the open nature of rock engineering even requires the engineering to be controlled by a system approach for surrounding environments. However, traditional methods cannot take all variables and their interactions into account and are limited to the system with single mechanisms. Therefore, they are not proper for a complex and open system, and also cannot portray the whole system. Thus, a system approach is indispensable to rock engineering for dealing with the whole of a complex and open system. In this paper Mechanism Path Analysis Methodology (MPAM) Is Introduced for a system approach to rock engineering. The analysis by the methodology gives us all the information of systems behavior in the context of the whole system in order to accomplish the optimum design in accordance with the project objectives and analysis purposes. As an application a conventional model for the evaluation of TBM tunneling performance system is analyzed by MPAM and the result is compared with that by a traditional method.

• JSTS:Journal of Semiconductor Technology and Science
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• 제9권3호
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• pp.136-147
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• 2009

In this paper we analyze the influence of source/drain (S/D) extension region design for minimizing short channel effects (SCEs) in 25 nm gate length single and double gate Silicon-on-Insulator (SOI) and Germanium-on-Insulator (GOI) MOSFETs. A design methodology, by evaluatingm the ratio of the effective channel length to the natural length for the different devices (single or double gate FETs) and technology (SOI or GOI), is proposed to minimize short channel effects (SCEs). The optimization of non-overlapped gate-source/drain i.e. underlap channel architecture is extremely useful to limit the degradation in SCEs caused by the high permittivity channel materials like Germanium as compared to that exhibited in Silicon based devices. Subthreshold slope and Drain Induced Barrier Lowering results show that steeper S/D gradients along with wider spacer regions are needed to suppress SCEs in GOI single/double gate devices as compared to Silicon based MOSFETs. A design criterion is developed to evaluate the minimum spacer width associated with underlap channel design to limit SCEs in SOI/GOI MOSFETs.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 추계학술대회 논문집
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• pp.1209-1212
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• 2007

Urban flooding with surcharges in sewer system was investigated because of unexpected torrential storm events these days, causing significant amounts of human and economic damages. Although there are limitations in forecasting and preventing natural disasters, integrated urban flooding management system using the SWMM(Storm Water Management Model) engine and Web technology will be an effective tool in securing safety in operating rubber-tired transportation system. In this study, the study area, located in Chuncheon, Kangwon province, was selected to evaluate the applicability of the SWMM model in forecasting urban flooding due to surcharges in sewer system The catchment are 21.10 ha in size and the average slope is 2% in lower flat areas. Information of subcatchment, conjunctions, and conduits was used as the SWMM interface to model surface runoff generation, water distribution through the sewer system and amount of water overflow. Through this study, the applicability of the SWMM for urban flooding forecasting was investigated and probability distribution of storm events module was developed to facilitate urban flooding prediction with forecasted rainfall amounts. In addition, this result can be used to the establishment of disaster management system for rainfall safety of rubber-tired tram in the future.

• 한국운동역학회지
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• 제20권3호
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• pp.319-325
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• 2010

The purpose of this research was to investigate the differences in the ski carving turn motion according to level of expertise. The posture and movement of 6 skiers nearby the fall-line was evaluated with a biomechanical approach focusing the rotational mechanics. The slope was at an angle of $9^{\circ}$ and the following variables were measured and calculated: tangential velocity, change of COM height after passing fall-line, width between feet, angle between upper body and thigh, trunk angle, average radius of curvature and average centripetal force. The expert skiers minimized their center of mass height movement and maintained the width of between their feet after the passing the fall-line in comparison with the beginners and intermediate skiers. The experts restrained themselves from pushing their upper body downward after the turn to maximize the centripetal force. The experts in comparison with the beginners and intermediate skiers during the turn didn't have to reduce their radius of curvature to maintain a high centripetal force. It was concluded, that the most important factor affecting the centripetal force, was for the beginners and intermediate skiers, to minimize their movement while using the appropriate amount of edging.

• 산업기술연구
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• 제26권B호
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• pp.21-28
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• 2006

A diesel truck of 1 ton is re-powered by a gasoline engine and the fuelling system of gasoline engine modified to gasoline/CNG bi fuel system. The engine characteristics such as fuel economy and power are evaluated by driving rest, sloping test and dynamometer. The driving test prove the driving cost is saved by 55% and the maximum speed is raised by 13%, which is mainly due to the higher calorific value of CNG. The sloping test is done on the road of which slope is 15%. The truck shows the mean velocity of 88km/h, which means that a re-powered truck is working fine. The BHP are measured by dynamometer. The power and torque produced by a re-powered truck are reduced by 13% and 14% respectively from the power of gasoline engine. The BHP reduction is one of main problems which one has to solve in near future.