• 한국생산제조학회지
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• 제19권6호
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• pp.776-781
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• 2010

Optimum design of movable hydraulic crane's booms for weight reduction was performed in this study. Since the boom weight of the present used booms is very heavy, it is needed to make them lighter structure as possible as we can. Optimum design was performed for the booms by changing from the hexagonal cross section to triangular truss structure under the conditions, which are the allowable stress for the present cross section must be maintained, and the optimized weight must be minimized. CATIAV5 was used for stress analysis and design variables were established as the height and width of the triangular truss structure. As the results, it is found that the height of the truss structure is increased in proportion to the height of the booms and the maximum stress for optimal truss structure was obtained as 412MPa, which is lower than the allowable stress for the present hexagonal cross section. The optimized weight of the booms is reduced to about 19.88% comparing to the original weight.

• 한국생산제조학회지
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• 제22권6호
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• pp.901-907
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• 2013

The development of high-rise firefighting vehicles warrants thorough structural analysis for ensuring vehicle stability. A few structural analyses were carried out using CAD data, material properties, load conditions, and boundary conditions for evaluating the structural stability of an overloaded multi-aerial platform for firefighting and rescue. Structural analysis was performed with an analytical model consisting of a turntable, six booms, two jib booms, and a basket structure. This model was operated in eight modes. All simulation was performed using NASTRAN, a commercial code. As a result, we confirm that the position of local stress exceeds that of the yield strength. Therefore, stress concentration relaxation is possible by introducing reinforcing boom structures, changing the shape, or imparting a larger moment of inertia to the booms' cross sections.

• 한국전산유체공학회지
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• 제21권3호
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• pp.31-38
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• 2016

The FDS-HCIB method is expanded to simulate water-oil-air flows around oil booms under relative motion, which is intended to increase the thickness of contained oil. The FDS scheme captures discontinuity in the density field and abrupt change of the tangential velocity across an interface without smearing. The HCIB method handles relative motions of thin oil booms with ease. To validate the developed FDS-HCIB code for water-oil-air flow around a moving body, the computed results are compared with the reported experimental results on the shape, length, and thickness of the oil slicks under towing. It is observed that the increase in pressure field between two barriers lifts the oil slick and the interfacial wave propagates and reflects as one barrier gets closer to the other barrier.

• 한국생산제조학회지
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• 제21권6호
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• pp.885-891
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• 2012

In this study, some structural analysis using 3D CAD data, material properties, load conditions and boundary conditions are carried out to evaluate structural stability of the multi-aerial platform for high-rise fire fighting and rescue. We conduct structural analysis for the upper structures such as turn table, booms and basket, by using a universal structural analysis program NASTRAN. As the results, there is local stress exceeding the yield strength, but it is able to relax stress concentration in a way such as changing thickness of the structure or making larger inertia moment in cross section of booms.

• Journal of Biosystems Engineering
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• 제31권3호
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• pp.146-152
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• 2006

Most upland in Korea have irregular field shapes. Boom sprayers working alone winding row will show considerable differences of spraying amount per unit area between left and right booms. If flow rates of both booms are equal. This phenomenon becomes significant as steering radius of sprayer decreases. This study was performed to seek a method which reduce the difference of the spray amount between left, right and center booms while spraying along curvy rows. A flow rate control method for keeping application rate of each boom section constant was proposed and experimentally proved using a boom sprayer attached to a cultivating tractor. The flow rate control device was composed of 3 ball valves and a rotary angle sensor. The rotary angle sensor showed a symmetric voltage output with respect to steering radius. The spray overlapping was happened in a boom nearby the steering center when steering radius of the sprayer was less than 5.2 m. Flow rates for left, right and center booms were regulated using ball valves based on the steering radius and spraying areas ration of right/left boom. The Maximum spraying area ratio ($S_{LR}$) of left to right boom section was 1:3.6 at the steering radius of 5.2 m. However, The Maximum achieved right and left spraying flow ratio was 1:2.7.

• 한국태양에너지학회 논문집
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• 제31권3호
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• pp.1-7
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• 2011

In the performance test for wind turbines of medium and large, The reference met-mast should be installed for measurement reference wind speed as IEC 61400-12-1 standards and design of booms for mounted an anemometer must be considered exactly. Boom-mounted cup anemometer are influenced by flow distortion of the mast and the boom. Therefore design of booms must be important so that flow distortion due to booms should be kept below 0.5%. But, in some cases at size of met-mast structure, the distance of boom from mast is longer then measurement of wind speed is impossible because of oscillation of boom-mounted anemometer. In this paper, We measured a wind speed at several point from mast and boom and we analyzed the error of wind speed at each point of measurement. Also, we will suggest a correction method using the data curve fitting about errors of wind speed between each point of mounted anemometer.

• 대한조선학회 특별논문집
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• 대한조선학회 2011년도 특별논문집
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• pp.5-11
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• 2011

In this paper, the dynamic response analysis of a floating crane with elastic booms and a cargo is performed. The objective is to consider the effects of the elastic boom in the lifting design stage. Governing equations of the motion for the system which consists of interconnected rigid and flexible bodies are derived based on the formulation of flexible multibody system dynamics. To model the boom as a flexible body, floating reference frame and nodal coordinates are used. Coupled surge, pitch, and heave motion of the floating crane with the cargo which has 3 degree of freedom is simulated by solving the equation numerically. Finally, the effects of the elastic boom for the lifting design that the floating crane is required to lift a heavy cargo are discussed by comparing the simulation result between with the elastic boom and with the rigid one.

• 벤처창업연구
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• 제19권1호
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• pp.1-21
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• 2024

최근 고금리, 경기둔화로 인한 벤처투자 위축이 전 세계적으로 진행 중이며, 우리나라도 예외가 아니다. M&A와 상장시장의 침체, 경기불확실성 증가, 기업 파산의 여파로 인한 투자심리 위축으로 벤처기업의 자금조달에 많은 어려움을 겪고 있다. 이렇게 바뀐 경제 환경에서 벤처캐피탈의 투자의사결정 요인도 많은 변화를 나타내고 있다. 하지만, 벤처캐피탈의 투자의사결정에 대한 연구는 일반적인 경제 환경에 초점을 맞추고 있다. 본 연구는 경제 후퇴와 호황에 따라 벤처캐피탈의 투자의사결정 요인이 어떻게 변화하는지를 살펴보았다. 이를 위해 경제 불황과 호황을 모두 겪은 적극적인 벤처 투자자들을 인터뷰하여 벤처캐피탈의 투자의사결정 요인: 1)창업자의 개인적 특성, 2)창업자의 경험, 3) 제품/서비스, 4) 시장, 5) 재무상황, 6) 투자조건, 7) 벤처캐피탈 공동투자가 어떻게 변화하는지를 비교하여 연구하였다. 연구결과, 투자의사결정 요인인 창업자의 개인적 특성, 경험, 제품/서비스는 경제 불황기에 더 높은 중요도를 가졌다. 시장 요인은 경제 호황기에 약간 높은 수준의 중요도를 나타냈다. 재무적 상황과 투자조건 요인은 경제 불황기에 경제 호황기 대비 중요도가 급격히 상승하였다. 마지막으로 벤처캐피탈 공동 투자는 경제 불황과 호황기에 많은 차이를 보이지 않았다. 본 연구는 최근 어려워진 벤처투자 환경에서 벤처캐피탈의 투자의사결정 요인을 보다 심도 있게 이해함으로써, 스타트업의 자금 조달을 돕고, 어려운 시장에서 생존하는 방안 마련에 도움을 준다.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.377-378
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• 2002

In many dynamic systems, unwanted vibrations which may arise during operation of machines are costly in terms of reduction of performance and service life. Sometimes these risky oscillations endanger equipment and personnel. When hydraulic telescopic booms taken large mass are driven at slow speeds between the two pads, unstable oscillations occur through the stick-slip at the sliding parts and become more severe and saw-toothed. This paper supposes few models for the telescopic boom in the multi-degree of freedom system, and attempts a theoretical approach for the numerical analysis in its stick-slip condition, It was verified that this theoretical approach has an effect on estimate of stick-slip in the one-degree as well as multi-degree of freedom system.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2008년도 정기 학술대회
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• pp.178-183
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• 2008

A robot crane truck is being developed by the Bridge Inspection Robot Development Interface(BRIDI) for an automated and/or teleoperated bridge inspection. At the end of the telescoping boom allows the operator to scan the bridge structure under the deck trough the camera. Boom vibration induced by wind and deck movement can cause serious problems in this scanning system. This paper presents a control system to mitigate such vibration of the robot boom In the proposed control system an actuator is installed at the end of the working boom. This control system is studied using a mathematical model analysis with LQ control algorithm and a scaled model test in the laboratory. The study indicates that the proposed system is efficient for the vibration control of the robot booms, thereby demonstrating its immediate applicability in the field.