• Journal of Welding and Joining
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• 제16권5호
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• pp.86-92
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• 1998

High speed wire seam weldability of tin coated thin gage sheet steels was investigated. Thickness and coating weight ranges of the test materials were 0.21~0.35mm and 1.1/1.1~2.8/11.2g/$m^2$, respectively. Test results indicated that the surface roughness value, Rz decreased as increasing the coating weight. The Rz was thought to be one of the important factors to influence the optimum welding condition range, $\triangle$Q. The $\triangle$Q showed close relationship with welding conditions such as welding pressure and travel speed. Higher welding pressure widened the $\triangle$Q while higher travel speed reduced the $\triangle$Q value. Results also demonstrated that tin coating weight should be optimized based on the weldability or the serviceability after welding. At th HAZ of sheet materials with thinner coating layer, tin depleted zone was produced since molten film of the coating material on the base metal agglomerated by the surface tension, which could result in reducing the corrosion resistance of the HAZ in the service environment.

• Journal of Welding and Joining
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• 제3권1호
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• pp.40-45
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• 1985

Wire meling characteristics were examined with variation of gas formers such as $MgCO_3, CaCO_3 and Li_ 2CO_ 3$ by self-shielded flux cored arc welding. The flux cored wire of overlap type was welded by DCRP. The results obtainedareas follows. 1) Drop type was observed with no gas former, repelled type with MgCO_3$ added and short circuit type with $Li_2CO_3$ added. The variation of transfer mode was related to the blowing force of $CO_2$ gas and the surface tension of the slag. 2) Droplet size increased with adding gas formers due to the effect of $CO_2$ gas cushion. 3) Core spikes were observed more frequently with increasing the amount of gas formers.

• 산업기술연구
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• 제25권A호
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• pp.87-93
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• 2005

Three-dimensional ultrasonic probes being applied to the medical imaging can be grouped into three depending on the scanning methods, which are a mechanical type system, a free-hand system, and 2D phased arrays system. A mechanical type scanner uses a mechanically driven transducer to acquire series of 2D plane images. By integrating these images, a 3-D medical image can be constructed. A motor driving mechanism is a conventional choice for mechanically driving a transducer assembly which picks the raw ultrasonic images up. In this paper we attempt to design a 3D ultrasonic probe which has a operating mechanism of s tilting 3-D scanning. The motion of a transducer assembly of the ultrasonic probe is analytically modelled. We propose a selection procedure for the diameter of a wire rope driving the transducer assembly and the size of torsional spring which gives an initial tension to wire ropes.

• 한국CDE학회논문집
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• 제15권1호
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• pp.70-83
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• 2010

Recently, floating cranes are mainly used to erect heavy blocks or cargos for constructing ships in many shipyards. It is important to estimate the dynamic motion of the heavy cargo suspended by a floating crane and the tension of the wire ropes between the floating crane and the heavy cargo. In this paper, the coupled dynamic equations of motion are set up for considering the 6 degree-of-freedom floating crane and the 6-degrees-of-freedom heavy cargo based on multibody system dynamics. Depending on the cargo weight, the motion of the floating crane would be changed to nonlinear state. The nonlinear terms in the equation of motion are considered. In addition, the nonlinear hydrostatic force, the linear hydrodynamic force, wire rope force, mooring force and gravity force are considered as the external forces. As the result of this paper, we analyze the engineering effect for erecting the heavy cargo by using the floating crane.

• Nuclear Engineering and Technology
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• 제38권8호
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• pp.753-762
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• 2006

In this paper, works related to enhancement of the CHF are reviewed in terms of fundamental mechanisms and practical applications. Studies on CHF enhancement in forced convection are divided into two categories, CHF enhancement of internal flow in tubes and enhancement of CHF in the nuclear fuel bundle. Methods of enhancing the CHF of internal flows in tubes include enhancement of the swirl flow using twisted tapes, a helical coil, and a grooved surface; promotion of flow mixing using a hypervapotron; altering the characteristics of the heated surface using porous coatings and nano-fluids; and changing the surface tension of the fluid using additives such as surfactants. In the fuel bundle, mixing vanes or wire wrapped rods can be employed to enhance the CHF by changing the flow distributions. These methods can be applied to practical heat exchange systems such as nuclear reactors, fossil boilers, fusion reactors, etc.

• 한국지반환경공학회 논문집
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• 제16권3호
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• pp.41-48
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• 2015

비탈면 계측시스템이 예전에 비해 많이 개선되긴 했지만, 주로 하드웨어적인 측면의 개선에 치우쳤다. 실제 비탈면의 거동은 3차원 거동이며, 3차원 거동해석은 많은 변수를 함유하고 있어 비탈면 안정해석을 위한 비탈면 거동분석프로그램은 상대적으로 개발이 부족하였다. 일차원 해석은 방향의 고려 없이 길이의 증감만을 나타내나, 실제 비탈면 현장의 경우 3차원 공간상 변화를 나타낸다. 3차원상의 공간좌표를 확정하기 위하여 결정되어야 하는 값들은 길이, 수평각 및 수직각이다. 그러므로 두 방향 및 길이 변화를 고려한 좌표 시스템을 이용하여 새로운 좌표들을 구할 경우, 3차원의 공간을 분할하여 수평변화 및 수직변화를 구분하여 비탈면의 거동을 해석할 수 있다. 본 해석 모델을 충청북도 DY비탈면의 계측 data에 적용하였다. 현장 계측자료를 3-D 해석한 결과 비탈면은 전반적으로 오른쪽으로 이동하고 있으며, 변위가 도로방향으로 일어남과 동시에 수직변위가 발생하고 있음을 알 수 있다. 현재 비탈면은 계측지점 간 누적변위가 4.3cm 이내인 미소거동을 하며, 계측지점 모두 거동양상이 유사한 변위 방향 및 크기를 보이고 있음을 알 수 있다.

• 설비공학논문집
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• 제5권2호
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• pp.85-93
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• 1993

The rise of a large gas bubble or slug in a Micro Two-Phase Closed Thermosyphon with a thin wire insert has been analiged by the potential flow theory. The effect of the interfacial surface tension is explicitly accounted by application of the Kelvin-Laplace equation and solved for the bubble shape. The solution is expressed in terms of the Stokes stream function which consists of an infinite series of Bessel functions. The conditions of the bubble movement in a Micro Two-Phase Closed Thermosyphon were theoretically ascertained.

• 대한치과교정학회지
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• 제14권2호
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• pp.241-248
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• 1984

The mechanical properties of Cr-Ni alloy of austenitic stainless steel and Co-Cr alloy orthodontic wires were studied in tension. The wires (0.018 inch) were tested in the as-manufactured and heat-treated conditions. Instron type tension testing machine was used for this study. Mean values and standard deviations were computed. The results were as follows; 1. The Cr-Ni orthodontic wires of austenitic stainless steel are generally superior than the Co-Cr orthodontic wires in ultimate tensile strength, In the elongation, however, Co-Cr orthodontic wire are superior than Cr-Ni orthodontic wires. 2. Increase in the degree of strength by heat treatment are more clearly shown in Co-Cr orthodontic wires than Cr-Ni orthodontic wires. And the elongation is decreased by heat treatment in both case. 3. The changes of the degree of strength by cooling method we not clearly shown, but in Cr-Ni orthodontic wires, air cooling are more effective, in Co-Cr orthodontic wires, cooling effect are scarcely shown.

• 전기학회논문지
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• 제65권1호
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• pp.214-218
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• 2016

Catenary maintains the tension of the catenary using automatic tensioning devices to meet performance require m ents exhibited by the house is generated in accordance with the new external temperature changes. Double spring type autom a tic tensioning device is permanent and does not require the usual maintenance, and a deterioration due to no recognizable ab normalities characteristic of the nature of the internal state has the disadvantage that can not be confirmed. The disassembled for automatic spring-tension capabilities ensure efficient operation and life expectancy of the adjustment device via a check by analyzing the changes in old age determine the remaining lifetime is expected to be available as a basis for maintenance in the future.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.256-259
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• 2008

An micro-probe tip must be manufactured using thin film to evaluate integrity of the semiconductor with narrow distance between pads. In this study, fatigue tests were performed for BeCu thin film which is used in micro-probe tip of semiconductor test machine. The thin film was manufactured by electro plating process, and the specimens were fabricated by wire-cut electric discharge method to make hour glass type specimen of $5000{\mu}m$ width, $29200{\mu}m$ length and $30{\mu}m$ thickness. The fatigue test of load control with 10Hz frequency was performed, in ambient environment. The fatigue cycles were tension-tension with mean stress, at stress ratio, R=0.1.