• 제목/요약/키워드: Added-mass

검색결과 938건 처리시간 0.028초

석고계 바인더를 활용한 습도도절 세라믹 보드의 특성 평가 (Evaluation of Humidity Control Ceramic Board Using Gypsum Binder)

  • 이종규;김태연
    • 한국재료학회지
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    • 제28권1호
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    • pp.62-67
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    • 2018
  • Active clay, bentonite and zeolite were used as porous materials for humidity controlling ceramic boards. The specific area and the pore volume of active clay were higher than bentonite and zeolite. The flexible strength of the gypsum board decreased with an increasing amount of porous material, and the flexible strength was lowest when active clay with a higher specific surface area than others porous materials was added. The specific surface area and total pore volume of ceramic boards containing porous material were highest at $102.25m^2/g$, $0.142cm^3/g$, respectively, when the active clay was added. In addition, as the amount of added porous materials increased, the specific surface area and total pore volume of the ceramic board increased, but the average pore diameter decreased. The addition of s porous materials with a high specific area and a large pore volume improved the moisture absorptive and desorptive performance of the ceramic board. Therefore, in this experiment, the moisture absorptive and desorptive properties were the best when active clay was added. Furthermore, as the amount of added porous materials increased, the moisture absorptive and desorptive properties improved. When 70 mass% of active clay was added to ${\alpha}$-type gypsum, the hygroscopicity was the highest, about $300g/m^2$, in this experiment.

직선늑골선형(直線肋骨船型)의 수평(水平) 및 비틂진동(振動)에 있어서의 2차원적(次元的) 부가관성계수(附加慣性係數) (Two Dimensional Added Inertia Coefficients for Straight Framed Hull Forms in Horizontal and Torsional Vibration.)

  • 김사수
    • 대한조선학회지
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    • 제12권2호
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    • pp.3-12
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    • 1975
  • As for two dimensional added mass coefficients for straight framed hull forms in a free surface of an ideal fluid, theoretical calculations by F.M. Lewis, vertical, K. Wendel, J.H. Hwang, and etc. are available; vertical modes of rectangular and triangle sections by Lewis, vertical, horizontal and torsional models of rectangular and triangle section by Wendel, and systematical calculations for vertical modes of single chine forms by Hwang. In this paper, employing the conformal transformation by which a unit circle and its exterior region can conformally mapped to a polygon and its exterior region, the author calculated two dimensional added inertia coefficients systematically for straight framed sections with single chine in horizontal and torsional modes of vibrations. As the results, it was found that sloping side angle is an important factor measuring the magnitude of two dimensional added inertia coefficient for a set of given values of the sectional area coefficient and the beam-draft ratio. To grasp it cleary in physical sense, pressure distributions are investigated for some typical section contours. The numerical results are presented graphically in the form of two dimensional added sectional area coefficients with beam-draft ratios and sloping side angles as parameters, so that the data may conveniently utilized for estimation of the added inertia coefficients based on a three parameter technique.

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자연광석을 이용한 염소계 지방족 탄화수소 혼합물 변환 특성 (Transformation Characteristics of Chlorinated Aliphatic Hydrocarbon (CAH) Mixtures by Natural Ores)

  • 손봉한;김남희;홍광표;윤준기;이채영;김영;권수열
    • 한국물환경학회지
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    • 제23권5호
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    • pp.712-722
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    • 2007
  • This study screened three natural ores (iron, mangenase, and zinc), two types of slags, and two elemental metals (elemental iron and zinc) to evaluate transformation characteristics of CAH mixtures [e.g. Carbontetrachloride (CT), 1,1,1-Trichloroethane (1,1,1-TCA), and Perchloroethene (PCE)]. To select an effective metal medium to treat the CAH mixtures, we measured transformation capacities (CAH mass ultimately transformed/mass of metal added) and the degree of dechlorination. We also considered economical efficiency of the metal media by comparing the value, CAH mass ultimately transformed divided by the price of metal medium added. A simplified mathematical model adapting CAH transformation capacity, first-order transformation kinetics, and available mass of metal transforming CAH was developed and used for estimating CAH transformation rate coefficient and longevity of the metal medium. CAH transformation capacity for elemental iron and elemental zinc were 4258~7129 and $4215{\sim}6330{\mu}g\;CAH\;transformed/g$ metal added, respectively, which are a factor of 80~200 higher than slags and natural ores. They also showed a factor of 1.1 to 2.2 greater degree of dechlorination than the others. Among natural ores and slags, Zinc ore showed the highest transformation capacity, $47{\sim}53{\mu}g\;CAH\;transformed/g$ metal added. Although zinc ore have smaller transformation capacity than elemental metals, economical efficiency of zinc ore is a factor of 10~20 greater than elemental metals tested. Consequently, zinc ore would be more economical medium than the others tested in this study. We estimated the pseudo first-order transformation rate of zinc ore was in the order of CT > 1,1,1-TCA > PCE.

Leipholz 기둥의 안정성에 미치는 자유단의 탄성구속과 말단질량의 영향 (Influence of Elastic Restraints and Tip Mass at Free End on stability of Leipholz Column)

  • 윤한익;박일주;진종태;김영수
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 1996년도 춘계학술대회논문집; 부산수산대학교, 10 May 1996
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    • pp.309-315
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    • 1996
  • An analysis is presented on the stability of elastic cantilever column subjected to uniformly distributed follower forces as to the influence of the elastic restraints and a tip mass at the free end. The elastic restraints are formed by both the translational and the rotatory springs. For this purpose, the governing equations and boundary conditions are derived by using Hamilton's principle, and the critical flutter loads and frequencies are obtained from the numerical evaluation of the eigenvalue functions of this elastic system. The added tip mass increases as a whole the critical flutter load in this system, but the presence of its moment of inertia of mass has a destabilizing effect. The existence of the translational and rotatory spring at the free end increases the critical flutter load of the elastic cantilever column. Nevertheless their effects on the critical flutter load are not uniform because of their coupling. The translational spring restraining the end of cantilever column decreases the critical flutter load by coupling with a large value of tip mass, while by coupling with the moment of inertia of tip mass its effect on the critical flutter load is contrary. The rotatory spring restraining the free end of cantilever column increases the critical flutter load by coupling with the tip mass, but decreases it by coupling with the moment of inertia of tip mass.

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HIP처리한 초미립 WC-(5~20) mass% Co 초경 합금의 미세조직과 기계적 성질 (Microstructures and Mechanical Properties of HIPed Submicron WC-(5~20) mass% Co Cemented Carbides)

  • 이승원;이완재
    • 한국분말재료학회지
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    • 제5권4호
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    • pp.279-285
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    • 1998
  • The microstructures and mechanical properties of submicron WC-Co cemented carbides were investigated in relation to cobalt content. To inhibit the WC grain growth during sintering, VC was added as a inhibitor in each alloy with 3 mass% to the cobalt content. The WC-(5, 8, 10, 15, 20) mass% Co compacts were sintered at $1400^{\circ}C$ for 30 min in vacuum. Some of WC-(5, 8, 10) mass% Co sintered compacts were HIPed with 120 atm at 130$0^{\circ}C$ for 1 hr. The shrinkages of all HIPed alloys were increased without depending on the cobalt contents and the sintered densities of them. The relative densities of the alloys were increased with the cobalt content and HIPing. The less the cobalt content, the larger the WC grain. Many contiguities of WC grains were found in WC-5 mass% Co alloy. The sizes and numbers of pores in the alloys were decreased by HIPing. And also the strength and the hardness of each alloy were increased. The maximum hardness was about 18.95 GPa in the WC-5 mass% Co alloy HIPed and the maximum transverse-rupture strength (T.R.S.) 3.2 GPa in the WC-20 mass% Co alloy sintered.

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가상질량과 저주파통과필터에 의한 햅틱 시스템의 안정성 영역에 관한 연구 (A Study for the Effect of a Virtual Mass with a Low-Pass Filter on a Stability of a Haptic System)

  • 이경노
    • 융복합기술연구소 논문집
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    • 제7권2호
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    • pp.25-30
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    • 2017
  • This paper presents the effects of a virtual mass with a low-pass filter on the stability boundary of a virtual spring in the haptic system. In general, a haptic system consists of a haptic device, a sampler, a virtual impedance model and zero-order-hold. The virtual impedance is modeled as a virtual spring and a virtual mass. However the high-frequency noise due to the sampling time and the quantization error of sampled data may be generated when an acceleration is measured to compute the inertia force of the virtual mass. So a low-pass filter is needed to prevent the unstable behavior due to the high-frequency noise. A finite impulse response (FIR) filter is added to the measurement process of the acceleration and the effects on the haptic stability are simulated. According to the virtual mass with the FIR filter and the sampling time, the stability boundary of the virtual spring is analyzed through the simulation. The maximum available stiffness to guarantee the stable behavior is reduced, but simulation results still show that the stability boundary of the haptic system with the virtual mass is larger than that of the haptic system without the virtual mass.

저속 횡 이동하는 선박의 선체에 작용하는 유체력에 관한 연구 (A Study of Hydrodynamic Forces Acting on a Ship Hull Under Lateral Low Speed Motion)

  • 이윤석;김순갑
    • 한국항해학회지
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    • 제23권2호
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    • pp.29-42
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    • 1999
  • An accurate method of estimating ship maneuverability needs to be developed to evaluate precisely and improve the maneuverability of ships according to the water depth. In order to estimate maneuverability by a mathematical model. The hydrodynamic forces acting on a ship hull and the flow field around the ship in maneuvering motion need to be estimated. The ship speed new the berth is very low and the fluid flow around a ship hull is unsteady. So, the transient fluid motion should be considered to estimate the drag force acting on the ship hull. In the low speed and short time lateral motion, the vorticity is created by the body and grow up in the acceleration stage and the velocity induced by the vorticity affect to the body in deceleration stage. For this kind of problem, CFD is considered as a goof tool to understand the phenomena. In this paper, the 2D CFD code is used for basic consideration of the phenomena to solve the flow in the cross section of the ship considering the ship is slender and the water depth is large enough. The flow fields Added and hydrodynamic forces for the some prescribed motions are computed and compared with the preliminary experiment results. The comparison of the force with measurement is shown a fairly good agreement in tendency. The 3D Potential Calculation based on the Hess & Smith Theory is employed to predict the surge, sway added mass and yaw added moment of inertia of hydrodynamic coefficients for M/V ESSO OSAKA according to the water depth. The results are also compared with experimental data. Finally, the sway added mass of hydrodynamic coefficients for T/S HANNARA is suggested in each water depth.

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수치적 방법에 의한 승용차 동적해석 (Dynamic analysis of vehicle system using numerical method)

  • 이종원;박윤식;조영호
    • 오토저널
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    • 제5권3호
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    • pp.45-55
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    • 1983
  • This paper discussed about Application Technique of Numerical Methods for large structure. The dynamic behaviours of a vehicle were investigated through finite element modelling. After dividing a vehicle body into three substructures, Basic Mass System was composed of 60 flexual modes which was obtained from the dynamic characteristics of each substructure using Modal Synthesis Method. Engine, transmission and rear axle, etc. were added to Basic Mass Model, consequently Full Mass System was constructed by 72 degree of freedoms. Full Mass System was analyzed over the frequency range 0.5-50.0 Hz under the loading conditions which were Stationary Gaussian Random Process. Results and discussions provided the guidelines to eliminate resonances among the parts and to improve the Ride Quality. The Absorbed Power was used as a standard to determine the Ride Quality. The RMS value of driver's vertical acceleration was obtained 0.423g from the basic model and 0.415g from the modified model.

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한국의 대중문화에 Animation Character가 미치는 부정적인 영향 (A Negative Effect of Animation Character in Mass Culture of Korea)

  • 김홍산;신정숙
    • 디자인학연구
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    • 제14권2호
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    • pp.147-154
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    • 2001
  • 애니메이션 캐릭터는 아이디어 지향의 고 부가가치 산업으로 다양한 시너지 효과를 창출하기 때문에 경제적인 측면만으로도 그 가치가 높다. 무엇보다도 애니메이션 캐릭터의 가치는 대중문화 커뮤니케이터로서의 역할에 있다. 애니메이션 캐릭터의 범람속에서 생활하는 대중들은 캐릭터에 의해 표현되는 다양한 성격과 행동에 영향받고 있다. 그러나 범람이라고 할만큼 대중의 생활을 둘러싸고 있는 애니메이션 캐릭터들의 성격과 행동들은 주로 극단적인 성향을 나타내고 있어, 대중사회의 유지와 존속에 필요한 역할모델의 제시에 부정적인 기능을 하고 있다.

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수중에 부분 몰수된 외팔보의 고유진동 특성 (Natural Vibration Characteristics of Cantilever Plate Partially Submerged into Water)

  • 곽문규;양동호;이재하
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2012년도 추계학술대회 논문집
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    • pp.229-230
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    • 2012
  • The free flexural vibration of a cantilever plate partially submerged in a fluid is investigated. The fluid is assumed to be inviscid and irrotational. The virtual mass matrix is derived by solving the boundary-value problem related to the fluid motion using elliptical coordinates. The introduction of the elliptical coordinates naturally leads to the use of the Mathieu function. Hence, the virtual mass matrix which reflects the effect of the fluid on the natural vibration characteristics is expressed in analytical form in terms of the Mathieu functions. The virtual mass matrix is then combined with the dynamic model of a thin rectangular plate obtained by using the Rayleigh-Ritz method. This combination is used to analyze the natural vibration characteristics of a partially submerged cantilever plate qualitatively. Also, the non-dimensionalized added virtual mass incremental factors for a partially submerged cantilever plate are presented to facilitate the easy estimation of natural frequencies of a partially submerged cantilever plate. The numerical results validate the proposed approach.

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