• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.774-777
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• 2002

There are various methods to join mechanical structures together. They typically include welding, mechanical joints by bolts and other processes depending on specific needs. Analyses of joints in the mechanical structures are essential in understanding the dynamic characteristics of the structures. In this research an impulse technique is applies to investigate the dynamic behavior of joints produced by bolts. The length overlap in the joints was varied as the number of the bolts in the joins was changed. Also, the torque applied to the bolts were adjusted. Resonance frequencies were determined for the joints to evaluate the relationship between the increase in the applied torque and the increase in the number of bolts used in the joints. The results have demonstrated that the resonance frequencies of the joints increase with the increasing torque.

• Journal of Advanced Navigation Technology
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• v.18 no.3
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• pp.248-252
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• 2014

In this paper, press and nut runner used in press-fit or tightening the bolts and nuts at assembling process of automobile parts companies continually demand accuracy and improved productivity. Simultaneous control of production systems through synchronization configuring of the combination multi press-fit system developed multi servo press system using the low-speed serial communication. As a result, the accuracy and the productivity is improved and product quality improvement could be achieved.

• Journal of the Korea Institute of Military Science and Technology
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• v.1 no.1
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• pp.189-200
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• 1998

본 연구에서는 얇은 마레이징강으로 제작된 천마 연소관에 브라켓이 용접되어 비행 날개를 볼트로 체결한 경우, 압력과 공력하중에 의해 브라켓 부위에 집중되는 응력의 해석기법을 정립하기 위하여 선형해석과 기하학적 비선형 해석을 수행하였다. 높은 압력에 의해 발생한 얇은 연소관의 면내 응력이 구조물의 강성을 증가시키는 응력의 강성보강효과(stress stiffening effect)를 고려한 기하학적 비선형 해석을 수행하여 선형해석 결과와 비교하였으며, 압력과 공력하중을 동시에 적용할 수 있는 복합하중시험기로 변형률을 측정하여 해석치의 정확성을 검토하였다. 얇은 연소관에 압력과 공력하중이 동시에 작용하는 경우는 응력의 강성보강효과를 고려한 기하학적 비선형 해석을 수행함으로써 보다 정확한 응력을 구할 수 있다는 결론을 얻었다.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.26 no.3
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• pp.292-298
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• 2017

Numerical analysis for various design parameters should be preceded by optimal design of composite materials. Numerous studies have been conducted on the bolting of interconnecting beams. In this study, the response surface method was applied to optimize the design of bolted joints connected by laminated wood composite beams. The response surface was created by combining the FEA code for composite analysis and the algorithm for forming the response surface. Optimization on this response surface was performed with a genetic algorithm to derive the results. The determination of the optimum bolt-hole position for the connection of composite beams is an optimization problem. Tsai-Wu composite failure index, maximum deflection, and simple von Mises stress are set as the objective functions. It has been proved that the design results of the optimized bolt-hole are superior to the design performance of the existing conventional bolt-hole position.

• Journal of ILASS-Korea
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• v.9 no.3
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• pp.1-7
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• 2004

This experiment was undertaken to investigate the atomization characteristics of the low viscosity biodiesel blended fuel and ultrasonic energy added one. Test fuels were conventional diesel fuel and biodiesel fuel. We compared to the characteristics of viscosity and surface tension, SMD between low viscosity biodiesel blended fuel and ultrasonic energy added one. Sauter mean diameter was measured under the variation of the spray distance. Viscosity and surface tension was measured under the variation of the time trace. To measure the droplet size, we used the Malvern system 2600C. Droplet size distribution was analyzed from the result data of Malvern system. Through this experiment, we found that the condition of the ultrasonic energy added situation had smaller Sauter mean diameter of droplet, viscosity and surface tension than that of the conventional situation.

• Tribology and Lubricants
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• v.23 no.2
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• pp.61-65
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• 2007

It is very important to connect machinery and maintain it. This is usually done by bolt joint. There are two ways in connecting the bolt joint : the angle method and the torque method. The torque method is a method that let the clamping force maintain. The underhead of the bolt's head and the thread friction are the main influences. This study focuses on how the clamping farce and friction coefficient change under the condition in vibrating the underhead of the bolt's head part. As a result, under vibration condition, we found out that the clamping farce increases, while the friction coefficient decreases.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.4
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• pp.577-586
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• 2004

Structural failures, such as crack initiation, often arise near the bolted parts of the side member and trunnion bracket in some commercial vehicles. The purpose of this paper is: 1) establishment of a simple and practical bolted joint modelling technique and 2) determination of the key design variables for design improvement based on numerical experiments. Once the bolted joint modelling technique is established through experimental verification, the key design variables must be identified in order to alleviate the level of the stress concentration near the problem region. Numerical results indicate that the torsional rigidity of the frame cross-section should be increased to reduce the level of the maximum stress at the actual crack initiation location.

• Journal of the Korean Vacuum Society
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• v.11 no.2
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• pp.81-86
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• 2002

With a specific model for the Helicoflex type metal gasket expected to be used in large ports of the KSTAR vacuum vessel, a sealing curve was obtained by measuring the flange tightening properties such as the correlations of the tightening torque(or linear load), displacement to the leak rate. From the experiment results it was found that the leak rate of the Helicoflex seal in the room temperature was bellow $2\times10^{-1}\textrm{mbar\cdot L/s}$ with a tightening torque of 2500kgf . cm using Ml8 bolts.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.5
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• pp.31-39
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• 1999

A good atomization in uniform size brings the elevation of thermal efficiency in spray combustion, the beautiful painting on surfaces, and the economical sprinkling of chemicals. Ultrasonic atomization has been expected as a good uniform atomization mechanism due to its uniform size distribution. Influx, load, and physical properties of liquids are the effecting factors to atomize liquids. In this study, distilled water and city water are selected as reference liquids and gasoline, kerosene, and petroleum as fuel liquids. Characteristics and affinity to get the maximum effect for the ultrasonic atomization are observed by using the two ultrasonic transducers with 28kHz and 2MHz. Results show that the size distributions of liquid spray dorplet by the direct vibration method prevail over those by the aerosol method in uniform droplet size and as a whole, sizes of spray liquid droplets are increased slightly according to increasing influx in the direct vibration method and quantities of spray droplets in the aerosol method decreasing according to increasing liquid load h.

• Journal of the korean Society of Automotive Engineers
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• v.15 no.3
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• pp.47-54
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• 1993

This paper describes briefly the effect of ultrasonic fuel supply device on the performance of four stroke cycle gasoline engine. Experiments were carried out to clarify the effect of ultrasonic fuel supply device on the engine output, traveling fuel consumption ratio, exhaust emissions. The results were obtained as follows: 1.Engine output was increased 9-14% in comparison with that of the conventional injector. 2.Travelling fuel consumption ratio was improved 17-29% in comparison with that of the conventional injector. 3. CO, HC exhaust emissions was decreased compared to the value of the conventional injector. 4.Fuel consumption ratio in highway driving test was improved about 10% in comparison with that of the conventional injector.