• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.11 no.4
• /
• pp.82-89
• /
• 2012

In order to clarify the effect of overload on crack growth behaviors, fatigue tests for overload were carried out for round plain specimens of SM45C steel. In the experiment, typical semi-elliptical crack shape was found and further crack growth behaviors were tested. Using three types of single overload fatigue tests, Crack growth retardation phenomenon were examined. The growth rate of surface crack(da/dN) during retardation period was analyzed in terms of ${\Delta}K$ and ${\Delta}K_{eff}$. On the growth rate of surface crack analyzed by ${\Delta}K$, the dependence of overload stress levels appears. However, on the growth rate by ${\Delta}K_{eff}$ obtained by Willenborg analysis, there is a liner relationship between da/dN and ${\Delta}K_{eff}$ with narrow scatter band.

• Proceedings of the KIPE Conference
• /
• 2002.07a
• /
• pp.73-76
• /
• 2002

In electrical machinery and apparatus, the most important problem is protect of machinery and apparatus in due to transient phenomena and overload on operation. Particularly by advanced technology of late, there Is demand for low cost of equipments and high percentage of use of equipments. Therefore, protection of machinery and apparatus In condition of overload is more valued considering that all efficiency increase is passed by operating all machinery and apparatus in condition of heavyload. In this paper, the suggested system is added overload interrupt system using CT in condition of overload.

• Proceedings of the KIEE Conference
• /
• 2002.04a
• /
• pp.28-30
• /
• 2002

In electrical machinery and apparatus, the most important problem is protect of machinery and apparatus in duo to transient phenomena and overload on operation. Particularly by advanced technology of late, there is demand for low cost of equipments and high percentage of use of equipments. Therefore, protection of machinery and apparatus in condition of overload is more valued considering that all efficiency increase is passed by operating all machinery and apparatus in condition of heavyload. In this paper, the suggested system is add overload protect system using CT in condition of overload.

• Journal of Korea Society of Digital Industry and Information Management
• /
• v.8 no.2
• /
• pp.11-19
• /
• 2012

Crane systems have been widely used for transportation in building sites, ports, nuclear wastehandling operation and so on. As a typical underactuated system, an overhead crane has such merits as high flexibility and less energy consumption. And it's getting more types of cranes, universally applicable algorithms should be developed. That is the design and development of scalable algorithms are required. Developed algorithms can be used for the controller and crane overload protection that meets the requirements of the algorithm are presented. These algorithms force the state to warn the operator and stops the operation of equipment. In this paper, crane overload conditions that can cause damage to alert the operator, and to limit the operation of equipment overload protection algorithm is presented.

• Journal of Ocean Engineering and Technology
• /
• v.18 no.1
• /
• pp.28-34
• /
• 2004

It is well known that tensile peak overloads may significantly delay suubsequent constant amplitude fatigue crack growth in many materials. Since real structures are usually subjected to complex load histories, the ability to predict accurate crack growth under realistic service conditions is of major engineering interest. This paper describes experiments on fatigue track growth in the integrally stiffened panel of 7075-T6 aluminum alloy. The effect of shape parameters and overload position on the fatigue crack growth behavior of integrally stiffened panels are discussed. Based on the experimental results, the following conclusions have been drawn: the overall fatigue crack growth retardation resulting from single overload in the stiffened panels was generally larger in the larger thickness ratio, although the retardation trends, according to the change in overload positions, were similar to those exhibited in the non-stiffened panels.

• Journal of the Korean Institute of Telematics and Electronics C
• /
• v.34C no.6
• /
• pp.79-88
• /
• 1997

New technologies, systems, and services in telecommunication have increased the need for an efficient and robust control mechanism to protect switching systems from overload. To achieve proper control, it is necessary to find a set of parameters that can describe the system. However, it is difficult to find types of data that can form a suitable basis for control. In this paper, we categorize the load status of a switching system into three classes (i.e., normal state, pre-overload state, and overload state) and formulate the overload detection as a classification problem. We find the relationships between the load classes and a set of monitored switching system parameters by applying a fuzzy rule-generation method. The rules are automatically generated from training data. Simulation results involving a switching system is given.

• Proceedings of the KIPE Conference
• /
• 2002.11a
• /
• pp.209-212
• /
• 2002

In electrical machinery and apparatus, the most important problem is protect of machinery and apparatus in duo to transient phenomena and overload on operation. Particularly by advanced technology of late, there is demand for low cost of equipments and high percentage of use of equipments. Therefore, protection of machinery and apparatus in condition of overload is more valued considering that all efficiency increase is passed by operating all machinery and apparatus in condition of heavyload. In this paper, the suggested system is add overload protect system using CT in condition of overload.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.9 no.2
• /
• pp.181-186
• /
• 2014

In this paper, we propose an overload control scheme to resolve an overload problem in a random access channel of cellular machine-to-machine (M2M) communication networks. The M2M applications are characterized by small-sized data intermittently transmitted by a massive number of machines. Due to this characteristics, an overload situation in random access channel (RACH) can happen when a large number of devices try to send a signal via the RACH. To address this overload problem, we propose a scheme in which a base station estimates the total load in the network and controls the load by using a p-persistent method based on the estimated load.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.19 no.2
• /
• pp.451-462
• /
• 1995

Single overload tests performed to examine the crack retardation behavior for the specimen thickness and overload ratios. Delayed crack length was tend to increase in small thickness and big overload ratio but was difference between delayed crack length and plastic zone size that expected in specimen thickness. So retardation behavior that estimated in plastic zone size, was not sufficient. Crack tip branching and striation distribution, secondary mechanisms that effected in retardation behavior, was examined by experiment and finite element analysis. Crack tip branching was affected by micro structure, and appeared the more complicatedly according to increasing damage by overload and decreasing crack driving force in base line stress level. And crack tip branching the branching angle decreased crack driving force in the crack tip. And a characteristic of the fractography on retardation zone was that striation distribution did not appear due to decreased crack driving force.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1997.04a
• /
• pp.481-485
• /
• 1997

6063-T5 alloys are tested in laboratory air, water and 3% NaCl solution to investigate the effects of corrosive environment on the retardation behavior through single overload fatigue test. Also, the fatigue crack propagation and the crack closure behavior are studied. The results obtained in this experimental study are summarized as follows: 1) Behaviors of fatigue crack growth retardation are observed in water and 3% NaCl solution as they do in air. The number of delay cycles and the size of affected region by single overload decrease greatly in water and 3% NaCl compared with those in air. 2) In fractographic results, the overload marking by single overload appear remarkably in air, but indistinctly in water and 3% NaCl solution. 3) The effect of crack closure on crack propagation is most remarkable in the beginning of crack propagation. With crack propagation, the crack closure level and its effect decrease greatly.