• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.26 no.8
• /
• pp.1506-1511
• /
• 2002

A computer aided expert system fur spur, helical, bevel and worm gears was newly developed by using AutoiCAD system and its AutoLISP computer language in the present study. Two methods are available for a designer to draw a gear. The first method needs the gear design parameters such as pressure, module, number of tooth, shaft angle, velocity, materials, etc. When the gear design parameters are inputted, a gear is drawn in AutoCAD system and maximum allowable power and shaft diameter are calculated additionally. The second method calculates all dimensions and gear design parameters to draw a gear when the information such as transmission, reduction ratio, nm, materials and pressure are inputted. The system includes four programs. Each program is composed of a data input module, a database module, a strength calculation module, a drawing module, a text module and a drawing edit module. In conclusion, the CAD system would be widely used in companies to find the geometric data and manufacturing course.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.15 no.7
• /
• pp.1439-1446
• /
• 2011

This paper describes the algorithm that lowers the dimension, maintains the object recognition and significantly reduces the eigenspace configuration time by combining the higher correlation feature information and Principle Component Analysis. Since the suggested method doesn't require a lot of computation than the method using existing geometric information or stereo image, the fact that it is very suitable for building the real-time system has been proved through the experiment. In addition, since the existing point to point method which is a simple distance calculation has many errors, in this paper to improve recognition rate the recognition error could be reduced by using several successive input images as a unit of recognition with K-Nearest Neighbor which is the improved Class to Class method.

• Journal of the Korean Operations Research and Management Science Society
• /
• v.42 no.2
• /
• pp.49-61
• /
• 2017

The study on the efficiency analysis of Korean automobile parts companies is mostly based on the calculation of the size of output such as sales. However, the performance indicators such as sales, operating profit, and net profit are directly related to the cost structure, and this cost structure is affected by changes in the company's asset structure and capital structure. As a result, it is necessary that efficient capital procurement should be done at the same time to create efficient management performance through proper investment. In this study, we aim to measure the efficiency of asset and capital procurement compared to the sales figures, such as sales, generated by 33 primary suppliers who supply parts to Hyundai Kia Motors. For this purpose, this study proposed a DEA cross analysis model that can simultaneously measure efficiency in terms of input assets and capital procurement based on the same management performance when analyzing the efficiency of domestic auto parts companies.

• Journal of the Korean Society for Precision Engineering
• /
• v.20 no.8
• /
• pp.21-29
• /
• 2003

This paper describes a research work on the development of computer-aided design system for deep drawing & ironing of a high pressure vessel. An approach to the system is based on the knowledge-based rules. Knowledge for the system is formulated from plasticity theories, handbook, experimental results and empirical knowledge of field experts. An attempt is made to link programs incorporating a number of expert design rules with the process variables obtained by commercial FEM software, DEFORM and ANSYS, to form a useful package. It is composed of five main modules, which are calculation of product thickness, input, production feasibility check, process planning, and autofrettage process modules and two submodules, which are folding check and process variable verification submodules. Programs for the system have been written in AutoLISP on the AutoCAD 2000 using personal computer. The developed system makes it possible to design and manufacture large high pressure vessel requiring D.D.I. process more efficiently.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.27 no.9
• /
• pp.1273-1281
• /
• 2003

The present study is mainly motivated to investigate the vaporization, auto-ignition, and combustion of liquid fuel spray injected into high pressure environment. The unsteady, multi-dimensional models were used for realistic simulation of spray as well as prediction of accurate ignition delay time. The Separated Flow (SF) model which considers the finite rate of transport between liquid and gas phases was employed to represent the interactions between spray and gas field. Among the SF models, the Discrete Droplet Model (DDM) which simulates the spray using finite number of representative samples of discrete droplets was adopted. The Eulerian-Lagrangian formulation was used to analyze the two-phase interactions. In order to predict an evaporation rate of droplet in high pressure environment, the high pressure vaporization model was applied using thermodynamic equilibrium and phase equilibrium at droplet surface. The high pressure effect as well as high temperature effect was considered in the calculation of liquid and gas properties. In case of vaporization, an interaction between droplets was studied through the simulation of spray. The interaction is shown up differently whether the ambient gas field is at normal pressure or high pressure. Also, the characteristics of spray behavior in high pressure environment were investigated through the comparison with normal ambient pressure case. In both cases, the spray behaviors are simulated through the distributions of temperature and reaction rate in gas field.

• Journal of Biosystems Engineering
• /
• v.41 no.3
• /
• pp.170-176
• /
• 2016

Purpose: This study aimed to improve the method for determining the position of the center of gravity for agricultural tractors. Methods: The proposed method uses trigonometric functions and coordinate transformation. Data were measured according to the ISO 789-6 test procedures for the center of gravity of agricultural tractors. The height calculated using the proposed method was compared with that determined from an AutoCAD drawing. To find the center of gravity of the tractor, the algorithm for finding the intersection of the two lines was used. Results: The vertical height from the ground to the center of gravity is 682.06 mm. The vertical coordinates obtained from the calculation and the drawing were the same. Conclusions: The developed method uses trigonometric and polar coordinate transformation. The method was compared and verified with the AutoCAD drawing results. The results indicate that users can apply this developed method instead of the plotting method which is an inconvenient and time-consuming. Further, users can program Microsoft Excel to easily determine the vertical coordinate. In addition, researchers will propose this method to the ISO as a standard method for determining the center of gravity in accordance with ISO 789-6.

• Proceedings of the KOSOMBE Conference
• /
• v.1997 no.11
• /
• pp.399-402
• /
• 1997

It is important to find a accurate root canal length or successful endodontic therapy. By X-ray method takes a long time and difficult in a curved canal. After developed electronic apex locator has allowed to measure the root canal length with easy, in a short time also in a curved canal. But most electronic apex locators have the disadvantage which is too short reading or sometimes the measurement itself becomes impossible if there are electrolytes in the canal. To overcome this drawback, impedance ratio method has been developed. In this study, we have developed frequency dependent electronic apex locator to minimize the interference of electrolytes. And based on that also some error in clinic use, we added the other method. Difference of two signals which are used in calculation of impedance ratio was can be represent the status of root canal fluid. As a result, using impedance ratio method and auto-calibration by voltage difference method can reduce the measurement error.

• Geomechanics and Engineering
• /
• v.17 no.6
• /
• pp.565-572
• /
• 2019

Spatial variability is an inherent characteristic of soil, and auto-correlation length (ACL) is a very important parameter in the reliability or probabilistic analyses of geotechnical engineering that consider the spatial variability of soils. Current methods for estimating the ACL need a large amount of laboratory or in-situ experiments, which is a great obstacle to the application of random field theory to geotechnical reliability analysis and design. To estimate the ACL reasonably and efficiently, we propose a micro-structure based numerical simulation method. The quartet structure generation set algorithm is used to generate stochastic numerical micro-structure of soils, and scanning electron microscope test of soil samples combined with digital image processing technique is adopted to obtain parameters needed in the QSGS algorithm. Then, 2-point correlation function is adopted to calculate the ACL based on the generated numerical micro-structure of soils. Results of a case study shows that the ACL can be estimated efficiently using the proposed method. Sensitivity analysis demonstrates that the ACL will become stable with the increase of mesh density and model size. A model size of $300{\times}300$ with a grid size of $1{\times}1$ is suitable for the calculation of the ACL of clayey soils.

• Journal of Auto-vehicle Safety Association
• /
• v.13 no.1
• /
• pp.51-56
• /
• 2021

As hydrogen is classified as an eco-friendly fuel, vehicles using hydrogen fuel are being developed worldwide. Vehicle fuel hydrogen is stored in cylinders at 70 MPa, so there is a high risk of explosion. Therefore, it is important to inspect hydrogen cylinders in used-vehicles. This study was conducted to improve the inspection method of the cylinders currently mounted on used-hydrogen buses. The inspection method is an image analysis method using a camera. Calcaulation algorithm was developed to quantitatively chech the amount of hydrogen leakage by the image method. As a result of adding a contact angle element to the calculation algorithm suggested by the GTR regulation and comparing it with the experimental data of the GTR regulation, the algorithm reliability was 94%, which secured similarity.

• Journal of Welding and Joining
• /
• v.33 no.2
• /
• pp.18-22
• /
• 2015

The importance of emotional quality of car is getting higher in these days. Noise takes great portion in emotional quality because it is detectable problem with just a few rides. The sources of car noise during operation are various and the related technical issues are vast. Sometimes weldments of auto body are referred as the source of noise and the suspicious weldment shows unsatisfactory welding quality in most cases. In this research, cases of noise making weldments are investigated to figure out the solution for welding quality improvement. They are categorized into several groups in according to the inferred types of the error source then appropriate solutions are suggested. Auto body has weldments of resistance spot welding and gas metal arc welding in general. Therefore the solutions are suggested as adjustment of welding process variables and related machineries. Inevitable error source is also referred which is originated from thermal expansion rate difference between ultra high strength steel and mild steel. This new approach is validated through simple calculation then more concrete investigation with numerical analysis is remained as further works to be done.