• Title/Summary/Keyword: cross-section area

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A Study on Gas-Liquid Interfacial Areas with the Stirrer Spends for A$CO_2$bsorption in Agitated Vessel (평면 교반조에서의 $CO_2$ 기체흡수에서 교반속도에 따른 기-액 계면 면적에 관한 연구)

  • 박문기;문영수
    • Journal of Environmental Science International
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    • v.3 no.4
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    • pp.403-408
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    • 1994
  • Catalytic slurry reactors, in which a solid maintained in the rom of fine particles suspended in a liquid, are frequently used in chemical and biochemical and industries. In these processes the particle loading is normally low so that the effects of particles on the liquid-film mass transfer coefacent and the gas-liquid interface area are assumed to be negligible. But it is known from the works, amongst others, that the finely powdered activated carbon can increase the gas-liquid mass transfer significantly in surface-aerated reactors. The stirred cell (13.2cm inside diameter) contained four baffles and at the stirring speeds range of 80 ∼ 300ppm, the gas-liquid interfacial area could be considered as that of the cross section of the vessel (that is, 130.1cm2). When the stirrer speeds were increased, the effective interfacial area was slightly higher than the geometric area and was obtained experimentally from the Danckwerts plots. Key Words : gas-liquid interfacial area, Duckwert's Plot stirred dell. mass transfer coefficient.

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A Study on Speed-up of a Transition Section Between Overhead Catenary and Rigid Conductor System (강체 전차선로이행구간 고속화 방안 연구)

  • Lee, Kiwon;Choi, Tae-Su;Cho, Yong Hyeon;Park, Young;Jun, Hyo Chan;Choi, Kyu-Hyoung
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.67 no.3
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    • pp.467-473
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    • 2018
  • R-Bar(Overhead Rigid Conductor system) is being developed for the high-speed in Europe because it has an advantage of cross section area reduction of tunnel compared with OCS (Overhead Catenary Line). Because there are lots of underground sections and mountains in korea, it is necessary to develop the R-Bar for a high-speed line. In this study, a method on speed-up of transition section between OCS and R-Bar is proposed. The commercial program, DAFUL, is used to predict a dynamic characteristics between Overhead Line and pantograph. The program is evaluated according to EN 50318 which is the European Norm for evaluation of the program. Using the evaluated modeling and method, a method for the max. speed of 250 km/h of transition section is proposed.

Modified Equation for Ductility Demand Based Confining Reinforcement Amount of RC Bridge Columns (철근콘크리트 교각의 소요연성도에 따른 심부구속철근량 산정식 수정)

  • Lee, Jae-Hoon;Son, Hyeok-Soo
    • Journal of the Korea Concrete Institute
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    • v.21 no.2
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    • pp.169-178
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    • 2009
  • An equation for calculating confining reinforcement amount of RC bridge columns, specified in the current bridge design codes, has been made to provide additional load-carrying strength for concentrically loaded columns. The additional load-carrying strength will be equal to or slightly greater than the resistant strength of a column against axial load, which is lost because the cover concrete spalls off. The equation considers concrete compressive strength, yield strength of transverse reinforcement, and the section area ratio as major variables. Among those variables, the section area ratio between the gross section and the core section, varying by cover thickness, is a variable which considers the strength in the compression-controlled region. Therefore, the cross section ratio does not have a large effect in the aspect of ductile behavior of the tension-controlled region, which is governed by bending moment rather than axial force. However, the equation of the design codes for calculating confining reinforcement amount does not directly consider ductile behavior, which is an important factor for the seismic behavior of bridge columns. Consequently, if the size of section is relatively small or if the section area ratio becomes excessively large due to the cover thickness increased for durability, too large an amount of confining reinforcement will be required possibly deteriorating the constructability and economy. Against this backdrop, in this study, comparison and analysis were performed to understand how the cover thickness influences the equation for calculating the amount of confining reinforcement. An equation for calculating the amount of confining reinforcement was also modified for reasonable seismic design and the safety. In addition, appropriateness of the modified equation was examined based on the results of various test results performed at home and abroad.

Optimized Cross-section Suggestion of a New Concept Lining Board through Parametric Study (매개변수해석을 통한 신개념 복공판의 최적단면 제안)

  • Kim, Chun-Ho;Yi, Seong-Tae;Kim, In-Sic;Sim, Tae-Mu
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.19 no.2
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    • pp.84-91
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    • 2015
  • In this paper, to overcome disadvantages of existing lining boards, the parametric studies to evaluate safety and verify performance of newly suggested lining boards was performed. Since the calculated stresses of steel plates are lower than the allowable stress for considered all analytical variables, end reinforcement locations, and crane rail loads, it can be concluded that the suggested lining board is structurally safe. Where, "$3,000{\times}2,000{\times}6t$" was select to be optimized cross-section and the reinforcement from the end to 200mm to the internal direction looks like the best case. In addition, the suggested lining board is economical since the steel amount per unit area compared to existing lining board is reduced by 36% and it can apply to the lining structural system of subway and underpass since construction speed is past due to the less installation number of lining boards.

General Theory for Enhancing the Transmission Efficiency through Small Apertures (소형 개구의 투과효율 향상을 위한 일반 이론)

  • Cho, Young-Ki
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.25 no.11
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    • pp.1113-1120
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    • 2014
  • In this paper, general methods for enhancing the transmission efficiency through the small subwavelength aperture in an infinite conducting plane are considered first by use of the transmission-resonant aperture like the ridged circular aperture structure, second by employing the transmission-resonant cavity structure. In particular, the maximum transmission cross section is found to be $\frac{2G{\lambda}^2}{4{\pi}}[m^2]$ for the two structures, where G is the gain of the aperture in the output half space. As experimental works, the impedance matching characteristics are investigated for the cases that above two structures are incorporated as a potential near field microscopic probe in the waveguide end. As a complementary problem to the above transmission-resonant aperture problem, some discussions are also given on the scattering resonance by the scattering object much smaller than the wavelength. This discussion may provide a good understanding of the physics for the phenomena that the maximum scattering cross section is much larger than the physical size of the atom in atomic physics area.

An Experimental Study about Fire Resistance effect on Boundary Condition of CFT Column under Loading in Fire (CFT기둥 재하가열 실험에서의 경계조건에 따른 내화성능 영향에 관한 실험적 연구)

  • Kim, Hyung-Jun;Kim, Heung-Youl;Park, Kyung-Hun;Cho, Kyung-Suk;Kwon, In-Kyu
    • Proceedings of the Korea Institute of Fire Science and Engineering Conference
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    • 2010.04a
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    • pp.389-394
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    • 2010
  • A concrete filled square steel tube (CFT) is composed of the external steel material, which its strength is reduced in fire due to sudden temperature increase, and the internal concrete with high thermal capacity that can ensure the fire resistance performance of the structure. Therefore, research about the influence factors of the structural performance of CFT column is required in order to apply CFT column to a fire resisting structure, and additional research about influence for each condition is also necessary. Among the influence factors, the boundary condition between column and beam is important structurally, and it is one of the major factors that determine overall fire resisting performance. This study performed a fire experiment under loading in order to analyse the influences of CFT column to the boundary condition. As the results of the experiment, fire resistance time of 106 minutes was ensured for the clamped-end condition but 89 minutes for the hinge-end condition in case of the 360 cross section. And, fire resistance time of 113 minutes was ensured for the clamped-end condition but 78 minutes for the hinge-end condition in case of the 280 cross section. The difference in the fire resistance performance according to changes in the boundary conditions showed a tendency that larger change effect on the fire resistance performance was derived from smaller cross section area.

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Model on the Elastic Behavior of Spectacle Frame (안경테 및 의료용구에 관한 연구 - 안경테의 탄성해석에 관한 모델 -)

  • Kim, DaeSoo
    • Journal of Korean Ophthalmic Optics Society
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    • v.5 no.2
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    • pp.127-138
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    • 2000
  • Differential equations and their solutions were formulated to describe the deflection of both temples and front frames and the pressure exerted by them varying parameters such as elastic modulus, thickness, length, width and shape of crosssection. The effect of such parameters on the deflections of both temples and front frames was illustrated by plotting the solutions of the derived equations. Deflection of temples was found to be maximum where the cross section was diamond-shaped and to be minimum with the rectangular cross section while thickness and cross section area of temples remain constant. The effect of parameters consisting of front frame on the deflection of front frames are very similar to those on temples. The central deflection and pressure of front frame initiated by the temple decreases as the length of temple increases. Detailed analysis of stresses at various parts of the temple will help design custom made spectacle frame as well as most comfortable frames.

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Development of a Fast Neutron Detector (속중성자 탐지용 반도체 소자 개발)

  • 이남호;김승호;김양모
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.52 no.12
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    • pp.545-552
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    • 2003
  • When a Si PIN diode is exposed to fast neutrons, it results in displacement damage to the Si lattice structure of the diode. Defects induced from structural dislocation become effective recombination centers for carriers which pass through the base of a PIN diode. Hence, increasing the resistivity of the diode decreases the current for the applied forward voltage. This paper involves the development of a neutron sensor based on the phenomena of the displacement effect damaged by neutron exposure. The neutron effect on the semiconductor was analyzed. Several PIN diode arrays with various thickness and cross-section area of the intrinsic layer(I layer) were fabricated. Under irradiation tests with a neutron beam, the manufactured diodes have a good linearity to neutron dose and show that the increase of thickness of I layer and the decrease of cross-section of PIN diodes improve the sensitivity. Newly developed PIN diodes with thicker I layer and various cross section, were retested and then showed the best neutron sensitivity at the condition that the I layer thickness was similar to a side length. On the basis of two test results, final discrete PIN diodes with a rectangular shape were manufactured and the characteristics as neutron detectors were analyzed through the neutron beam test using on-line electronic dosimetry system. Developed PIN diode shows a good linearity as dosimetry in the range of 0 to 1,000cGy(Tissue) and its neutron sensitivity is 13mV/cGy at constant current of 5mA, that is three times higher than that of commercially available neutron detectors. And the device shows little dependency on the orientation of the neutron beam and a considerable stability in annealing test for a long period.

The Characteristics of Heavy Rainfall in Summer over the Korean Peninsula from Precipitation Radar of TRMM Satellite : Case Study (TRMM/PR 관측에 의한 한반도에서의 여름철 호우의 특성 : 사례연구)

  • 박혜숙;정효상;노유정
    • Korean Journal of Remote Sensing
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    • v.16 no.1
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    • pp.55-64
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    • 2000
  • The Tropical Rainfall Measuring Mission(TRMM) Satellite was launched in November 1997, carving into orbit the first space-borne Precipitation Radar(PR). The main objective of the TRMM is to obtain and study multi-year science data sets of tropical and subtropical rainfall measurements. In the present investigation, the characteristics of heavy rainfall cases over Korea in 1998 and 1999 are analyzed using the TRMM/PR dat3. We compare the rainrate measured from TRMM/PR with the accumulated rainfall data for 10 minutes tv Automatic Weather System(AWS). Especially, horizontal cross-section of rainrate with height and longitude in the precipitating clouds are investigated. As a result of the comparison with GMS-5 IR1, the TRMM/PR data delineate well the rain type( i.e. convective, stratiform cloud and others), height of storm top and instantaneous rainrate in the precipitating clouds. The vertical structure with height and horizontal cross-section of rainrate along the longitude show the orographic effect on the rainfall. TRMM/PR instrument measures the rainrate below 6 ㎜/hr more than AWS rainguages and inclined to underestimate the rainrate than rainguages for the whole area.

Multi-objective shape optimization of tall buildings considering profitability and multidirectional wind-induced accelerations using CFD, surrogates, and the reduced basis approach

  • Montoya, Miguel Cid;Nieto, Felix;Hernandez, Santiago
    • Wind and Structures
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    • v.32 no.4
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    • pp.355-369
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    • 2021
  • Shape optimization of tall buildings is an efficient approach to mitigate wind-induced effects. Several studies have demonstrated the potential of shape modifications to improve the building's aerodynamic properties. On the other hand, it is well-known that the cross-section geometry has a direct impact in the floor area availability and subsequently in the building's profitability. Hence, it is of interest for the designers to find the balance between these two design criteria that may require contradictory design strategies. This study proposes a surrogate-based multi-objective optimization framework to tackle this design problem. Closed-form equations provided by the Eurocode are used to obtain the wind-induced responses for several wind directions, seeking to develop an industry-oriented approach. CFD-based surrogates emulate the aerodynamic response of the building cross-section, using as input parameters the cross-section geometry and the wind angle of attack. The definition of the building's modified plan shapes is done adopting the reduced basis approach, advancing the current strategies currently adopted in aerodynamic optimization of civil engineering structures. The multi-objective optimization problem is solved with both the classical weighted Sum Method and the Weighted Min-Max approach, which enables obtaining the complete Pareto front in both convex and non-convex regions. Two application examples are presented in this study to demonstrate the feasibility of the proposed strategy, which permits the identification of Pareto optima from which the designer can choose the most adequate design balancing profitability and occupant comfort.