• 한국군사과학기술학회지
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• 제17권1호
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• pp.33-40
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• 2014

Due to its unmanned feature and some of being matured underwater technologies, UUV(Unmanned Undersea Vehicle) is increasingly considered as a utility player in today's battle-field. The operational benefit of submarine-based UUV operation could be enormous yet the integration challenges are significant, particularly for most of small conventionally-powered submarines. In this paper, we consider UUV operational methodology via the conventional submarine's torpedo tube. Two previous attempts having been done to retrieve the UUV through torpedo tube are reviewed, and their pros and cons are also analyzed. Then, an alternative option is proposed for UUV operation via torpedo tube. In addition, some of practical challenges are also discussed in the paper.

• 대한기계학회논문집B
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• 제29권6호
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• pp.763-771
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• 2005

This paper is an experimental study on the performance according to a capillary tube diameter and length in a domestic small multi refrigerator[kimchi refrigerator]. Pressure drop in a capillary tube is predicted by theoretical analysis and experimental method as the reduction of capillary tube diameter from 0.74 to 0.6 mm. The differences between experimental results and analytical results are mainly caused by friction factor in a capillary tube. Because there are no adequate equations used to calculate pressure drop of capillary tube diameter under 1.0mm. The empirical equations necessary for interpretation of capillary tube were derived from capillary tube test results data using curve fitting method. This study shows that the optimized designs of system, which is capillary tube length and refrigerant charge amount, are 2000mm, 83g at the capillary tube diameter 0.6mm and 3000mm, 73g at the capillary tube diameter 0.74mm. And capillary design tools and system matching techniques necessary for development of the kimchi refrigerator were also developed through this study.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 춘계학술대회 논문집
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• pp.268-271
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• 2007

A sandwich tube is a structured material that has two inner and outer circular tubes and light material between them. In this paper, a sandwich tube with a pyramidal truss core is introduced. Fabrication method and example made by brazing are shown. The behavior of the sandwich tube under lateral loading is predicted by analytical and numerical method. Comparative study between the sandwich and the monocoque tube is performed at a point of view such as strength and weight saving. As a result, proposed tube is appropriate for application to lightweight structural material

• 한국자동차공학회논문집
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• 제3권3호
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• pp.29-36
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• 1995

The present paper deals with the crushing characteristics of double hatted-section tube used in body structure of passenger car. Being crushed, a double hatted-section tube shows symmetric or antisymmetric buckling mode according to section aspect ratio and flange size. Zone of buckling mode is shown by numerical methods. It is supposed that crippling behavior of double hatted-section tube corresponds with rectangular tube without flange. Crippling plate coefficient is also calculated when section aspect ratio of tube is higher than one.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 춘계학술대회논문집
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• pp.402-408
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• 2003

Currently tube hydroforming has many studies and applications in manufacturing industry, especially in automotive industry. But tube hydroforming was applied to the automotive component with simple shape. So the manufacturer and the researcher proposed additional processes to form the automotive component with complex shape. It is prebending and preforming. Prebending is to crush bend or rotary draw bend a tubular blank into a shape that facilitates placement into the next forming tool. Preforming is where the prebent tube is crushed into a shape that facilitates placement into the final forming tool. This paper analyzed and compared to the tube hydroforming process to using of general and preformed bending tube, also explained the importance of tube bending and preforming process. The explicit finite element program PAM-STAMP$\^$TM/ was used to simulate the tube hydroforming operations.

• 소음진동
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• 제11권2호
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• pp.241-248
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• 2001

The present paper describes experimental and computational work to augment the magnitude of the impulsive wave. An experiment was performed using a simple shock tube with an open end and numerical calculations were carried out to solve the unsteady, axisymmetric, inviscid, compressible governing equations. The control strategy applied was to alter the exit geometry of a straight tube to a sudden enlargement tube and a flare tube. The effects of the configurations of the tube exit on the magnitude of the impulsive wave were investigated over the range of the weak shock Mach number from 1.01 to 1.10. The results obtained were compared to those of the straight tube tests. The numerical result predicted the magnitude of the experimented impulsive waves with a good accuracy. The present passive control technique enabled the magnitude of the impulsive wave to augment by about 23 percent, compared to that of the straight tube of no control.

• 한국공작기계학회논문집
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• 제17권1호
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• pp.113-119
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• 2008

The purpose of the present paper is to investigate the optimal shape of the brake tube-end and flare nut for automobiles using the $DEFORM^{TM}-3D$, finite element code. A flare nut is a small and important part used to join a brake tube-end in automobiles. In this instance, we studied the optimal forging processes for the tube-end and flare nut. Finite element analysis has been carried out to predict an optimal shape of the tube-end and flare nut. Also the simulation results were reflected to the forging processes design for the tube-end and flare nut. The shape of the tube-end and flare nut is in agreement with the finite element simulation and the test results.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.642-647
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• 2008

The boiler structure is determined by combustion characteristics and construction costs in the combustion chamber of a large commercial boiler. The heat transfer in boiler is composed of the radiation and the convection. The convective heat transfer has happened to back-pass heating surface. The combustion gas sequentially passes through the reheater tube, 1st economizer tube, and 2nd economizer tube. In case of being lowered in boiler height, we have to install additional tube bundle in back-pass heating surface for increasing the heat transfer of boiler, which causes the noise and vibration from combustion gas. When the combustion gas passes through the back-pass tube bundle in specified load of commercial boiler, this paper analyzes the acoustic characteristics between vortex-shedding frequency and natural frequency in tube bundle cavity. The case study reduce the resonance by changing natural frequency characteristics of tube-bundle cavity using a way to install ant-noise baffle in the direction of combustion gas flow.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.2200-2206
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• 2008

This paper describes the results of experiments on the bending behavior of welded square tube structures for drive shaft sub frame of BIMODAL Tram. The used specimens to test were two different type made of ATOS60 and ST52-3. The square tube made of ST52-3 is the non-welded structure, while the square tube made of ATOS60 is the welded structure. The welded square tube made of ATOS60 will be applied for drive shaft sub frame of BIMODAL Tram. This welded square tube could reduce the manufacturing cost in comparison of non-welded square tube. The results showed that the bending performance of welded square tube made of ATOS60 was proven, and the bending behavior was in an good agreement with that of nonlinear finite element analysis.

• 한국안전학회지
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• 제30권4호
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• pp.168-173
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• 2015

A steam generator tubing is one of the main pressure boundary of the reactor coolant system in the nuclear power plants. Structural integrity refers to maintaining adequate margins against failure of the tubing. Burst pressure of a tube at tube support plate can be higher than that for a free-span tube because failure behaviors could be interfered from the tube support plate. Alternative repair criteria for out-diameter stress corrosion cracking indications in tubes to the drilled type tube support plate were developed, however, there are very limited information to the eggcrate type tube support plate. This paper discussed reinforcement effect of steam generator tube burst pressure with axial out-diameter stress corrosion cracking within an eggcrate type tube support plate. A series of tube burst tests were performed under the room temperature and it was found out that there is no significant but marginal effects.