• Proceedings of the KIEE Conference
• /
• 2008.04a
• /
• pp.228-229
• /
• 2008

This paper presents stochastic methodology based fault diction and diagnosis algorithm for induction motor systems. First, we construct probability distribution model from healthy motors and then probability distribution for faulty motors is recursively calculated by means of the proposed probability estimation. We measure motor current with hall sensors as system state. The estimated probability is compared to the model to generate a residue signal which is utilized for fault detection and diagnosis, that is, where a fault is occurred. We carry out real-time induction motor experiment to evaluate efficiency and reliability of the proposed approach.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.15 no.2
• /
• pp.567-574
• /
• 1991

In this study thermal stress generated in three ingot moulds(GC25) during the solidification process of aluminum were analyzed by the two-dimensional thermo-elasto-plastic theory. In temperature analysis, all of the three models are shown steep temperature rising each case in initial stage of cooling. In thermal stress analysis, all of three models took compressible stress on inside wall of the mould, and tensible along with on out side. Model 2 take place less compressible, tensible stress then model 1. But model 3. have similar as thermal stress as model 2. The analysis will made one possible to calculate an optimum mould shape whose thermal stress gradient becomes minimum.

• Research in Mathematical Education
• /
• v.6 no.1
• /
• pp.97-106
• /
• 2002

Educators have found that the concept of randomness is often misunderstood by students. Chance recently pointed out that students should be introduced to the concept of randomness through the use of simulations. In this article, we studied various aspects of the probability distribution off linear random path in a circle and introduce some related simulations to guide student exploration and discovery. Consider a random line segment that crosses a circle with a certain radius. Perhaps it can be considered to be a path that an airplane shows up and flies into a random direction in a monitor. What is the expected amount of flying distance through the monitor, and the expected variation\ulcorner Are we monitoring what we see scientifically\ulcorner This article studies the probability distribution and some related aspects of a linear random path within a circular monitor. Some simulative activity is also introduced which can be used in a statistics or probability classes.

• Journal of Power System Engineering
• /
• v.20 no.4
• /
• pp.5-11
• /
• 2016

This study analyzed the damage to a slitting knife after cutting steel sheets. Damages to the structure were observed and wear tests were conducted. In addition, the degradation on the damaged and undamaged parts was compared with a micro Vickers hardness test. Weibull statistical analysis was carried out in order to evaluate the reliability of the micro Vickers hardness measured data. Spalling of the edge portion occurred by degradation during use over a long period. Rough parts in the specimens were caused by damage because the slitting knife was used for 1 year. The friction coefficient and wear loss at the damaged parts of the knife edge were slightly larger from shock due to repetitive cutting operation. The micro Vickers hardness followed a two-parameter Weibull probability distribution.

• Journal of Welding and Joining
• /
• v.21 no.4
• /
• pp.69-74
• /
• 2003

The mechanical properties of STD11 Joints by using TLP (Transient Liquid Phase Diffusion) bonding method employing MBF-30 and MBF-80 insert metals were investigated with concerning to the microstructural change. TLP bonding of STD 11 was carried out at 1323∼1423K for 0.6ks∼3.6ks in vacuum. The microstructure and the element distribution of the interlayer between tool steels and insert metals showed specific feature with bonding conditions. It was found that the width of the interlayer increased at initial bonding stage. However, the width of interlayer showed nearly constant value during the isothermal solidification. After isothermal solidification was completed, the joint showed homogeneous element distribution and similar microstructure with base metal because of the grain boundary migration to the bonded interlayer. The bonding strength measured by a tensile test has been varied with the bonding conditions. The maximum joint strength, 760MPa, was obtained with the condition of 1423K for 1.2ks using MBF30 insert metal in this experiment.

• Journal of Korean Society on Water Environment
• /
• v.28 no.4
• /
• pp.574-581
• /
• 2012

It is important to analyze the status of water quality with relation to the stream flow to attain water quality goal more effectively in the unit watersheds for the management of Total Maximum Daily Loads (TMDLs). This study developed a flow duration-water quality distribution graph to figure out water quality appearances on the flow variation and analyzed contributions of water quality observations to the impaired water bodies quantitatively by hydrologic conditions. Factors relating to water quality variation can be analyzed more precisely and assessed on the base of quantified contributions. It is considered that this approach could be utilized to establish a more effective plan for the water quality improvement including the prioritization of pollution reduction options.

• Proceedings of the KIEE Conference
• /
• 2008.04b
• /
• pp.171-173
• /
• 2008

This paper presents stochastic methodology based fault diction and diagnosis algorithm for induction motor systems. First, we construct probability distribution model from healthy motors and then probability distribution for faulty motors is recursively calculated by means of the proposed probability estimation. We measure motor current with hall sensors as system state. The estimated probability is compared to the model to generate a residue signal which is utilized for fault detection and diagnosis, that is, where a fault is occurred. We carry out real-time induction motor experiment to evaluate efficiency and reliability of the proposed approach.

• Journal of Distribution Science
• /
• v.11 no.3
• /
• pp.5-11
• /
• 2013

Purpose - Going concern is one of fundamental concepts in accounting and auditing and sometimes the assessment of a company's going concern status that is a tough process. Various going concern prediction models' based on statistical and data mining methods help auditors and stakeholders suggested in the previous literature. Research design - This paper employs a data mining approach to prediction of going concern status of Iranian firms listed in Tehran Stock Exchange using Particle Swarm Optimization. To reach this goal, at the first step, we used the stepwise discriminant analysis it is selected the final variables from among of 42 variables and in the second stage; we applied a grid-search technique using 10-fold cross-validation to find out the optimal model. Results - The empirical tests show that the particle swarm optimization (PSO) model reached 99.92% and 99.28% accuracy rates for training and holdout data. Conclusions - The authors conclude that PSO model is applicable for prediction going concern of Iranian listed companies.

• Journal of Distribution Science
• /
• v.3 no.1
• /
• pp.23-42
• /
• 2005

The service offer expectation and the desire of customers to a large-sized rate influence store also increase as a result of such environmental change. the counter where research of a book was upgraded from differentiation pursuit by competition between business condition in business condition in the case of the domestic rate influence store which has put the focus on service strengthening The work shrine which cannot reach here the competition predominance in the domestic market it will be hard coming to secure, when environmental change of inside large-sized rate influence store industry is taken into consideration The research which tried to receive customer service failure recovery carried out actual proof analysis in the influence to which fair nature lateness of a customer attains to the re-purchase intention to this store of customer satisfaction and future by service recovery process for an object in the customer who held service failure recovery experience in the domestic large-sized rate influence store.

• Journal of Distribution Science
• /
• v.3 no.1
• /
• pp.113-131
• /
• 2005

This study aims to look into how we Korean ports can improve NODE competitiveness among northern-east region of Asia, and to examine a conceptual as well as practical methodology approach to be applied in terms of cluster. Also many other researches have done to take out the conclusion, which is environmental aspects as economic and logistical one in terms of northern-east region of Asia, basic concept with NODE, and matters concerning seaport from the viewpoint of hub-spoke, etc. Then finally it is suggested that we Korea has to concentrate on seaport, which is equipped with logistics cluster provide into value added logistics, in order to keep and gain the NODE competitiveness in northern-east region of Asia.