• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.20 no.6
• /
• pp.44-50
• /
• 2021

This study analyzed the stability of antenna equipped on vehicles by the link of modal analysis and random vibration analysis with the vibration data of MIL-STD-810H, METHOD 514.8. As a result of the random vibration analysis of antenna, the maximum equivalent stress 41.9MPa and minimum margin of safety 8.37 was generated in the bracket of antenna by the vertical direction vibration. Thus, it was found that antenna has enough stability during the operation.

• Design & Manufacturing
• /
• v.12 no.3
• /
• pp.42-47
• /
• 2018

Recently, in the surge of global environmental issues, there has been a great attention to lightweight materials in purpose of saving energy. Magnesium alloys not only have low specific gravity, and superb specific stiffness, but are also excellent in blocking vibrations and electromagnetic waves. So demand for this material is getting bigger rapidly throughout the industry. In this study, we examined the improvement of formability of magnesium alloy AZ31 material in warm working. Drawing, bending and shearing process were carried out by varying the forming temperature and the forming speed, and the influence of the variables on each process was studied. In the experiments, the high forming temperature and low forming speed results in high formability in the drawing process and the bending process. In the shearing process, as the forming temperature increases, the length of the fracture decreases.

• Transactions of the Korean hydrogen and new energy society
• /
• v.30 no.2
• /
• pp.147-154
• /
• 2019

In this study, effects of flow types and size of molten carbonate fuel cells (MCFCs) were investigated using CFD simulation. In the simulation, the current collector of MCFCs were assumed to be an porous media. With the area of $0.09m^2$, the effect of flow types such as Co-flow, Counter-flow, Cross-flow were studied. After that the effect of the size and flow direction was studied. Among three-flow types, MCFCs with co-flow type shows more uniform distribution and current density distribution.

• Design & Manufacturing
• /
• v.16 no.4
• /
• pp.7-16
• /
• 2022

A helmet is essential for safety when operating personal mobility. However, user's actual helmet wear rate is low due to the inconvenience of wearing and poor ventilation. In this study, a new helmet structure with improved ventilation for personal mobility devices was designed. To design a new structure with improved breathability compared to the existing helmet while satisfying the safety regulations for the helmet, a generative design method was applied to the shock-absorbing liner of the helmet. In addition, other materials were applied to create a structure with improved ventilation while maintaining safety. The generated design result was verified for shock absorption through simulation. As a result of the study, EPS, the current material was replaced with CFRP and Kevlar, and the structure was changed. This design was judged to satisfy safety regulations against impact. The new helmet structure is expected to improve the helmet usability for personal mobility and increase the helmet wear rate of users.

• Transactions of the Korean hydrogen and new energy society
• /
• v.34 no.1
• /
• pp.69-76
• /
• 2023

An experimental study was conducted on a 4-stroke direct injection diesel engine to examine the combustion and emission characteristics of 1-octanol/diesel fuel blends. The concentration of 1-octanol in the fuel blends was 10%, 30%, and 50% by volume. Experiments were conducted by varying the engine torque from 6 Nm to 12 Nm at the same engine speed of 2,700 rpm. Results showed that the fuel conversion efficiency increased as the 1-octanol proportion increased under most experimental conditions. However, the brake specific fuel consumption increased due to the relatively low lower heating value of 1-octanol. The smoke opacity and the concentrations of NO_x and CO emissions generally decreased with brake mean effective pressure as the 1-octanol proportion increased. On the other hand, the unburned hydrocarbon concentration increased with an ascending ratio of 1-octanol.

• Journal of the KSME
• /
• v.22 no.6
• /
• pp.434-446
• /
• 1982

현재 기계가공의 자동화 시스템으로 주목되고 있는 FMS(Flexible Manufacturing System)에 관해 기술해보기로 한다. FMS는 다중품종중소량생산에 맞춘 시스템으로써, 더욱이 24시간 연속 자동화운전을 만족시키는 시스템으로써 개발을 침전시키고 있는 것이다.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.21 no.6
• /
• pp.1-7
• /
• 2022

This work investigated the performance improvement of a medium-pressure fixed-displacement-type SPUR gear pump, which is mainly used in the machine tool industry. The 3D CFX analysis and IS technique were applied using ANSYS (commercial FEM code) and compared with experimental results to ensure the reliability of the analysis. In addition, the performance improvement of the pump was obtained using the theoretical volumetric displacement equation, and the gear tooth width was changed. The pressure flow performance curves were compared, and the results were analyzed according to the width of the gear teeth. This is a factor that can cause irregular flow, vibration, and noise inside the gear pump owing to friction between the housing and gear pump.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.18 no.9
• /
• pp.94-99
• /
• 2019

To evaluate the stability of a pneumatic conveyor system, a flow analysis and structural analysis were performed using the FSI technique. Prototypes were fabricated and verified. As a result of the flow analysis, the maximum pressure applied to the device was calculated to be 0.55 MPa. The structural analysis determined that the maximum stress was 131 MPa and the yield strength of the structure was less than 205 MPa. The safety of the system was confirmed by the fact that no deformation occurred during the manufacturing and operation of the prototype.

• Journal of the Microelectronics and Packaging Society
• /
• v.28 no.4
• /
• pp.109-114
• /
• 2021

We investigated the effects of atmospheric hydrogen plasma treatment on Cu-Cu direct bonding. Hydrogen plasma was effective in reducing the surface oxide layer of Cu thin film, which was confirmed by GIXRD analysis. It was observed that larger plasma input power and longer treatment time were effective in terms of reduction and surface roughness. The interfacial adhesion energy was measured by DCB test and it was observed to decrease as the bonding temperature decreased, resulting in bonding failure at bonding temperature of 200℃. In case of wet treatment, strong Cu-Cu bonding was observed above bonding temperature of 250℃.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.33 no.11
• /
• pp.1294-1299
• /
• 2009

The Korean tilting train called Hanvit 200 was launched recently in Korea to improve train speed up to 200 km/h at conventional lines. In this paper, we propose a HILS system for simulations of mechanical braking of the Hanvit 200 train using actual ASCU, actual dump valves, Simulink, dSPACE board, and ControlDesk software. In the proposed HILS system, dynamics of wheelsets, bogies and car body, brake force generation, creep force generations are realized via mathematical models, and anti-skid logic is realized using actual components. The validity of the proposed HILS system is demonstrated via comparing results of real-time and off-line simulations.