• Proceedings of the KWS Conference
• /
• 1995.10a
• /
• pp.3-20
• /
• 1995

Development of Real-Time Quality Evaluation of Friction Welding by Acousitc Emission : Report 1 ABSTRACT : According as the friction welding has been increasingly applied in manufacturing various machine components because of its significant economic and technical advantages, one of the important concerns is the reliable quality monitoring method for a good weld quality with both joint strength and toughness in the process of its production. However no reliable nondestructive test method is available at present to determine the weld quality particularly in process of production. So this paper presents an experimental examination and quantitative analysis for the real-time evaluation of friction weld quality by acoustic emission, as a new approach which attempts finally to develop an on-line quality monitoring system design for friction welds using AE techniques. As one of the important results, it was confirmed, through this study, that AE techniques can be reliably applied to evaluating the friction weld qualify with 100% joint strength, as the cumulative AE counts occurring during welding period were quantitatively correlated with reliability at 95% confidence level to the joint strength of welds. Real-Time Evaluation of Automatic Production Quality Control for Friction Welding Machine : Report 2 Abstract : Both in-process quality control and high reliability of the weld is one of the major concerns in applying friction welding to the economical and qualified mass-production. No reliable nondestructive monitoring method is available at present to determine the real-time evaluation of automatic production quality control for friction welding machine. This paper, so that, presents the experimental examinations and statistical quantitative analysis of the correlation between the initial cumulative counts of acoustic emission(AE) occurring during plastic deformation period of the welding and the tensile strength of the welded joints as well as the various welding variables, as a new approach which attempts finally to develop an on-line (or real-time) quality monitoring system and a program for the process of real-time friction welding quality evaluation by initial AE cumulative counts. As one of the important results, it was well confirmed that the initial AE cumulative counts were quantitatively and cubically correlated with reliability of 95% confidence level to the joint strength of the welds, bar-to-bar (SCM4 to SUM31, SCM4 to SUM24L) and that an AE technique using initial AE counts can be reliably applied to real-time strength evaluation of the welded joints, and that such a program of the system was well developed resulting in practical possibility of real-time quality control more than 100% joint efficiency showing good weld with no micro-structural defects.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 1994.04a
• /
• pp.653-659
• /
• 1994

Human experts have the various own knowledges to be applied in specialized domains. The fact that knowledge itself becomes more critical in the context of textile knowledge with rapid development of new fibers, automated equipments, processes and applications. Diversity of worsted spun yarns, lack of human expertise, and inconsistency among manually generated process plans in consequency of adjustment machine parameters owing to change up raw materials frequently increase the necessity of developing computer aided process planning(CAPP) systems for spinning process. Expert systems offer one of techniques to develop CAPP systems which would behave in a knowledgeable manner. Expert systems are the problem-solving computer program that can reach a level of performance comparable to that of a human expert in some specialized problem domain. This paper is described as job justification module. The job justification module performs to consult with users on which worsted spun yarn manufacturing process planning under the various factors, e.g., raw materials, machine parameters and required yarn counts. Also, the developed module informs the various knowledges relevant process planning. The job justification module offers the control parameters at each process and includes the various standard process plans as database. These knowledges are generated by facts and rules within rule bases.

• Journal of Institute of Control, Robotics and Systems
• /
• v.3 no.2
• /
• pp.187-196
• /
• 1997

This paper presents a semi-automatic methodology to synthesize executable digital controller saftware in a multi-loop control system. A digital controller is described by a task graph and end-to-end timing requirements. A task graph denotes the software structure of the controller, and the end-to-end requirements establish timing relationships between external inputs and outputs. Our approach translates the end-to-end requirements into a set of task attributes such as task periods and deadlines using nonlinear optimization techniques. Such attributes are essential for control engineers to implement control programs and schedule them in a control system with limited resources. In current engineering practice, human programmers manually derive those attributes in an ad hoc manner: they often resort to radical over-sampling to safely guarantee the given timing requirements, and thus render the resultant system poorly utilized. After task-specific attributes are derived, the tasks are scheduled on a single CPU and the compiled kernel is synthesized. We illustrate this process with a non-trivial servo motor control system.

• 제어로봇시스템학회:학술대회논문집
• /
• 1993.10a
• /
• pp.582-588
• /
• 1993

A scheme of dynamic optimization for batch reactor his been developed and applied to a semi-batch esterification reactor. To obtain optimal operating conditions for the given semi-batch reactor system with complex reaction kinetic and process constraints, a general nonlinear programming solver and finite element techniques have been introduced. The optimization results for the complex reactor system have been compared with those of Kumar et al. [1984] to show better optimization performance. The proposed optimizing scheme has been applied to the free end time problem to obtain the realistic operating condition. The results can supply valuable information for economic operation of the given batch esterification reactor.

• 제어로봇시스템학회:학술대회논문집
• /
• 1994.10a
• /
• pp.224-228
• /
• 1994

This paper deals with a Batch processor application to determine orbit trajectories from satellite tracking data. The purpose of this paper is to find the initial state vectors. In order to determine the better estimation process, several different cases are compared. Here we adapt a minimum variance concept to develop estimation and prediction techniques. These results are compared with by SEP, Spherical Error Probable, values.

• Proceedings of the IEEK Conference
• /
• 1999.11a
• /
• pp.739-742
• /
• 1999

This study is to increase capability of the DC/DC converter (for PCS) in miniaturizing, stabilizing by locating an inductor with the structure of multi layer on to the glass/ceramic circuit board. When the DC/DC converter is stimulated. the characteristic operation of PWM switching circuit, losses. output power to input power, stability, efficiency and interfaces inside of control circuit and convener circuit are to be distinguished. The process would make it able to develop the techniques of designing and manufacturing of the converter of next generation.

• Journal of electromagnetic engineering and science
• /
• v.6 no.4
• /
• pp.229-234
• /
• 2006

This paper presents an advanced method of simulation for EM(electromagnetic) environment that affects on mobile receivers. A new calibration algorithm in the process of simulation is introduced. With a proposed calibration method, the time required for simulation is reduced and this makes it possible to simulate a near-real time EM environment in a shielded anechoic chamber. EM environment data acquisition and logging techniques with GPS for simulation were developed.

• Journal of Korean Society for Quality Management
• /
• v.10 no.2
• /
• pp.10-17
• /
• 1982

Three different manual assembly techniques are evaluated by relating the effects of component quality to the total cost of the product. The results show that the choice of the scrapping or repairing the defective products or alternatively, salvaging the acceptable parts, may effect the total product cost by as much as 400 per cent. This paper emphasizes the need for accurate control quality of parts in assembly if low-cost manufacture is to be achieved.

• Proceedings of the KWS Conference
• /
• 2002.10a
• /
• pp.336-341
• /
• 2002

Recent developments in sensor hardware and in advanced software have made it feasible to consider automating some of the most difficult welding operations. This paper describes some techniques used to automate successfully multipass submerged arc welding operations typically used in pressure vessel manufacture, shipbuilding, production of offshore structures and in pipe mills.

• Plant Journal
• /
• v.5 no.3
• /
• pp.59-65
• /
• 2009

In the plant EPC project, the procurement work can be considered as the most important part that affects the success or failure of project as it has the closest mutual influence in every execution process of the project. Procurement takes up generally 60% ~ 70% of the entire project budget and the current trend of plant EPC project becoming larger in scale and a variety of process technology being applied. So, it is needed to identify the risks that are expected to occur according to the stages of procurement work, namely, proposal stage, manufacturer selection and purchasing agreement stage, expediting the process management of manufacturer stage, inspection stage and logistics & transportation stage. The management of observation and control of the risks should be performed with the response techniques which are 'avoid',' transfer'and' mitigate'.