• Journal of Korean Society of Water and Wastewater
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• v.19 no.3
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• pp.288-294
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• 2005

This study was conducted to evaluate the grit removal efficiency of tornado block-type vortex grit separator. Vortex grit separator was manufactured for this study, and it was characterized by the impeller and tornado block installed in separator. Impeller was installed to increase water velocity in the separator and tornado block was installed to increase the grit lifting efficiency. Pilot study was also conducted in A sewage treatment plant (STP) in Gyeonggi province from November 2003 to May 2004 (64 days). Major findings are as follows. 1. Impeller was proven to increase water velocity in the grit separator, especially in low flow rate. This influence will increase separation ratio of organics from grits, preventing those organics from sedimentation. 2. Sand (with 0.2~0.3mm size) removal efficiency was over 98 % and 96 %, at the flow rate of $500m^3/day$ and $750m^3/day$ under the condition that impeller rotation velocity kept at 15 rpm. Originally that grit separator was designed to have the capacity of $500m^3/day$. $750m^3/day$ was tried to investigate the performance of this type of grit separator under overload condition. Stable grit removal was still available to the extent of 150% of designed capacity. 3. It took less than 3 minutes for the grit separator to completely lift out 3 kgs of 0.2-0.3 mm sized, settled sand at the bottom to 2,060 mm high above water surface. But it showed the tendency to spend a little more time on lifting the grit as the grit size and the vertical height of the lift increased. 4. During experimental duration in A STP, it was found that the average amount of inlet grit was about 981 g/day (160~1,685 g/day) under $500m^3/day$ of operation condition, but it varied so severely during the experimental duration. After classification of discharged grit according to its size, grit with 0.3-0.42 mm size was found as largest part of output.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2008.04a
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• pp.307-312
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• 2008

Local damage may cause sequential collapse of structure, which is called progressive collapse. Current progressive collapse analysis is based on the mean value of design variables. This deterministic approach has a low reliability as it doesn't consider uncertainty of variables. In this study the sensitivity of design variables for progressive collapse of structure is evaluated by Monte Calro simulation and Tornado diagram. The analysis results show that the behaviour of model structures is highly sensitive to variation of the yield force of beams and the structural damping ratio.

• Wind and Structures
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• v.15 no.2
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• pp.163-176
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• 2012

Damaging winds, associated with a variety of weather phenomena, are frequently experienced in New Zealand. Observations and modelling of two recent extreme wind events; the Taranaki tornado outbreak of July 2007, and the Greymouth down-slope easterly wind storm of July 2008 are described in detail here. Post-event engineering damage surveys, rare for New Zealand, were done for these storms and the results are summarized here. Finally, the issue of sampling extreme wind events is raised and the need to include detailed numerical modelling analysis to understand wind gust climatologies at observing sites and extending these to wider regions is discussed.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.10
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• pp.631-638
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• 2017

An experimental study was conducted to investigate the effect of a rotor design on the performance characteristics of a slurry pump using the tornado principle. The slurry pump differs considerably in terms of construction as well as operating principle when compared to the conventional centrifugal pump. The design parameters of the cross-shaped rotor included the diameter, thickness and height. The total head, shaft and water powers, and pump efficiency as a function of flow rate were compared with the design parameter. It was found that as the rotor diameter and height increase, the efficiency increases, whereas, an increase in the rotor thickness decreases the efficiency. In the rotor design condition of this study, the specific area and efficiency of the maximum height rotor were, respectively, smaller and higher than those of maximum diameter rotor.

• Defense and Technology
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• no.12 s.130
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• pp.62-69
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• 1989

현재 개발되고 있는 유럽의 헬기들은 거의 전부가 공동개발 형태이며, 이 프로그램들을 관리하는 기술은 이전의 영.불콩고드, 유럽의 에어버스, 불.독의 유로미사일 그리고 NATO의 Tornado 전투기프로그램에서 얻은 경험들을 토대로 하고 있다. 이 관리기술이 가장 최근에 실현된 프로그램이 EH-101이라 할수 있다. 엄청난 리스크와 비용을 유럽이 그간 축적한 경험으로 극복한 점은 유럽공동개발 프로그램으로서 EH-101이 갖는 각별한 의미이다

• Magazine of RCR
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• v.15 no.2
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• pp.39-44
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• 2020

• Defense and Technology
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• no.11 s.237
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• pp.58-65
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• 1998

새로운 전술 정찰장비의 개발은 미 공군 이외에도 미 해군과 해병대에서도 F-14와 F-18 전투기에 장착 가능한 전술 정찰용 장비의 개발이 추진되고 있으며, 영국에서는 Tornado를, 프랑스에서는 Mirage와 Rafale을, 이스라엘, 덴마크, 네덜란드 등은 F-16을 유인 전술 정찰기로 사용하기 위해 새로운 전술정찰 체계를 자체 개발하거나 합작 생산을 추진하고 있다.

• Wind and Structures
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• v.19 no.3
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• pp.321-337
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• 2014

This study has developed an Enhanced Remote-Sensing (ERS) scale to improve the accuracy and efficiency of using remote-sensing images of residential building to predict their damage conditions. The new scale, by incorporating multiple damage states observable on remote-sensing imagery, substantially reduces measurement errors and increases the amount of information retained. A ground damage survey was conducted six days after the Joplin EF 5 tornado in 2011. A total of 1,400 one- and two-family residences (FR12) were selected and their damage states were evaluated based on Degree of Damage (DOD) in the Enhanced Fujita (EF) scale. A subsequent remote-sensing survey was performed to rate damages with the ERS scale using high-resolution aerial imagery. Results from Ordinary Least Square regression indicate that ERS-derived damage states could reliably predict the ground level damage with 94% of variance in DOD explained by ERS. The superior performance is mainly because ERS extracts more information. The regression model developed can be used for future rapid assessment of tornado damages. In addition, this study provides strong empirical evidence for the effectiveness of the ERS scale and remote-sensing technology for assessment of damages from tornadoes and other wind events.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.1
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• pp.71-77
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• 2001

A flow visualization study using the oil film method and the smoke-laser light sheet arrangement is carried out to investigate the three-dimensional flow pattern around the free end surface region of a finite circular cylinder (aspect ratios of 1.25 and 4.25) mounted on a flat plate. The experiment is performed for the cases of two Reynolds numbers: 5.92${\times}$10$^3$and 1.48${\times}$10(sup)5. Various kinds of singular points on the free-end surface are disclosed from the oil surface flow visualization. The smoke-laser light sheet visualization, to aid in understanding the oil streak-line patterns, clearly demonstrates that a pair of tornado-like vortices marched along the downstream together with a pair of side tip vortices. A topological sketch to characterize the surface flow and the four vortices emanating from the top surface is included.

• Defense and Technology
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• no.2 s.144
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• pp.24-35
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• 1991

MBB사의 연간 매출은 약 3조원(41억불)이며, 이 가운데 75%가 각종 국제협력사업에서 이루어지고 있다. 민수분야가 54%를 차지하고 있고, 특히 주목할만한 것은 매출액중 각종 개발관련사업이 24%의 높은 비율을 차지하고 있는 점이다. 앞으로 MBB는 현재 진행하고 있는 Airbus 여객기, Tornado 전투기, 각종 헬기 생산에 주력하면서 여객기 개발, 전투기 개발, 각종 헬기개발, 전투기 성능개량, 수송기 개발, TiltRotor기 개발, 각종 미사일 개발 그리고 위성시스템 개발에 전력을 경주할 것이다