• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 추계학술대회 논문집
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• pp.118-121
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• 2008

Flexible die is more efficacious than fixed die which is generally used in stretch forming process in view of production cost. Accordingly, in order to verily the validity of the flexible forming process, curved thin skin structure forming analyses using the fixed and flexible die were performed. As results, merit and demerit with regard to the fixed and flexible die were confirmed. The result of the stretch forming process analysis using the flexible die was better than that using the fixed die in view of the elastic recovery. However wrinkles were occurred on the sheet material due to die cavities between the punches in the flexible forming process, thus the solutions against these problems were presented.

• 산업경영시스템학회지
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• 제43권1호
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• pp.143-150
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• 2020

To enhance the effectiveness of the FMS (flexible manufacturing system), it is necessary for the manufacturing control system to be upgraded by integrating the cyber and the physical manufacturing systems. Using the CPPS (Cyber-Physical Production System) concept, this study proposes a 4-stage vertical integration and control framework for an aircraft parts manufacturing plant. In the proposed framework, the process controller prepares the operations schedule for processing work orders generated from the APS (advanced planning & scheduling) system. The scheduled operations and the related control commands are assigned to equipments by the dispatcher of the line controller. The line monitor is responsible for monitoring the overall status of the FMS including work orders and equipments. Finally the process monitor uses the simulation model to check the performance of the production plan using real time plant status data. The W-FMCS (Wing rib-Flexible Manufacturing Control & Simulation) are developed to implement the proposed 4-stage CPPS based FMS control architecture. The effectiveness of the proposed control architecture is examined by the real plant's operational data such as utilization and throughput. The performance improvement examined shows the usefulness of the framework in managing the smart factory's operation by providing a practical approach to integrate cyber and physical production systems.

• 산업경영시스템학회지
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• 제44권3호
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• pp.22-32
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• 2021

To meet rapidly changing market demands, manufacturers strive to increase both of productivity and diversity at the same time. As a part of those effort, they are applying flexible manufacturing systems that produce multiple types and/or options of products at a single production line. This paper studies such flexible manufacturing system with multiple types of products, multiple Bernoulli reliability machines and dedicated buffers between them for each of product types. As one of the prevalent control policies, priority based policy is applied at each machines to select the product to be processed. To analyze such system and its performance measures exactly, Markov chain models are applied. Because it is too complex to define all relative transient and its probabilities for each state, an algorithm to update transient state probability are introduced. Based on the steady state probability, some performance measures such as production rate, WIP-based measures, blocking probability and starvation probability are derived. Some system properties are also addressed. There is a property of non-conservation of flow, which means the product ratio at the input flow is not conserved at the succeeding flows. In addition, it is also found that increased buffer capacity does not guarantee improved production rate in this system.

• 산업경영시스템학회지
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• 제16권28호
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• pp.49-58
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• 1993

We have been recognize the adaptation of JIT(Just-in-Time) production system is necessary to improve the constitution of enterprises. But this system is not settled in our industrial environment owing to misunderstanding of JIT concepts and lack of participation all members of the oranization. This paper deals with systematic application of the JIT subsystems such as U-form layout, flexible workforces with multi- functional skilled workers and adjustment of standard operations procedures. And a successful productivity improvement case study of a small and medium sized industry was dealt.

• 산업경영시스템학회지
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• 제14권24호
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• pp.97-103
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• 1991

This paper deals with a scheduling problem with the objective of maximizing the throughput rate in flexible manufacturing system with shop type. Manufacturing system is consisted of multi-stage in series. All kinds of parts are processed in same in processing time. No buffer space is allowed between stages, and no part waiting is allowed in each stage. Part flow control method for determining the optimal production sequence of all parts and the production starting time of each part is proposed.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.750-753
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• 2002

At present, almost circuits are wired using copper in flexible circuits. But, these circuit have limit to flexibility so it occurs fracture about cyclic bending and, thermal load of bending stress occur a circuit trouble. a study of all-polymer flexible circuits get over that problem. Established fabrication method of all-polymer circuits is photolithograph. This method can not have mass production, so this method wastes time and human effort. In this study, all polymer flexible circuits are fabricated using the inkjet process.

• 산업경영시스템학회지
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• 제20권44호
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• pp.153-161
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• 1997

This paper has proposed the modelling by simulation in order to evaluate the performance of process through discrete event simulation using SIMAN language in flexible manufacturing systems. The production system is assumed to be a job shop type of system under the batch production of discrete products. In this paper, the input data is the workstation(process) time, the number of workstation(process), a probability distribution, the number of simulation runs. Also, transient period is considered. In the case study, this paper deals with three products in real flexible manufacturing systems. Finally, a number of simulation runs were executed under different experimental conditions to obtain preliminary statistics on the following performance measures: operating rate of facility and average system operating rate, transient period, central processing unit, average system throughput, and average waiting time in queues.

• 한국정밀공학회지
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• 제33권7호
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• pp.601-606
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• 2016

In this paper, an energy harvester is developed that has advantages regarding piezoelectric noise minimization, mass production, and an easily available environmental energy source, electromagnetic induction, as well as low-frequency bandwidth and high amplitude. A process for fabricating a three-dimensional multilayered planar coil using micro-electro-mechanical systems (MEMS) on a flexible printed circuit board FPCB is introduced. Optimal shape and size were calculated via internal resistance and inductance, and a prototype was fabricated through the MEMS procedure while considering the possibility of mass production. Although the internal resistance matched the designed value, the electromotive force generated did not reach the intended amount. The main reason for the decrease in efficiency was the low area of coil outskirt exposed to the magnetic field while there was relative motion between the magnet and the coil.

• Transactions on Control, Automation and Systems Engineering
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• 제1권1호
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• pp.32-43
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• 1999

Adaptive robust control scheme is introduced for flexible joint manipulator with nonlinearities and uncertainties. The system does not satisfy the matching condition due to insufficient actuators for each node. The control only relies on the assumption that the bound of uncertainty exists. Thus, the bounded value does not need to be known a prior. The control utilizes the update law by estimating the bound of the uncertainties. The control scheme uses the backstepping method and constructs a state transformation. Also, stability analysis is done for both transformed system and original system.

• International Journal of Naval Architecture and Ocean Engineering
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• 제3권3호
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• pp.181-192
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• 2011

Recently, the speed of change related with enterprise management is getting faster than ever owing to the competition among companies, technique diffusion, shortening of product lifecycle, excessive supply of market. For the example, the compliance condition (such as delivery date, product quality, etc.) from the ship owner is getting complicated and the needs for the new product such as FPSO, FSRU are coming to fore. This paradigm shift emphasize the rapid response rather than the competitive price, flexibility and agility rather than effective and optimal perspective for the domestic shipbuilding company. So, domestic shipbuilding companies have to secure agile and flexible ship production environment that could respond change of market and requirements of customers in order to continue a competitive edge in the world market. In this paper, I'm going to define a standard shipbuilding production management system by investigating the environment of domestic major shipbuilding companies. Also, I'm going to propose a unified ship production management and system for the operation of unified management through detail analysis of the activities and the data flow of ship production management. And, the system functions for the strategic approach of ship production management are investigated through the business administration tools such as performance pyramid, VDT and BSC. Lastly, the research of applying strategic KPI to the digital shipyard as virtual execution platform is conducted.