• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.707-710
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• 2010

The most important things in the KSLV-I Kick Motor nozzle is a development of flexible seal that is utilized to drive a movable nozzle. Especially, a manufacturing technology of flexible seal is one of the key element in the Kick Motor nozzle development. The method used to produce flexible seal in the Kick Motor is injection method. Mold design technology, rubber injection technic and molding process through flexible seal manufacture has been established. After manufacturing, X-Ray inspection have been carried out to confirm a adhesive and internal array of flexible seal.

• Journal of the Microelectronics and Packaging Society
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• v.28 no.4
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• pp.47-50
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• 2021

Nanoimprint lithography (NIL) has revolutionized the fabrications of electronics, photonics, optical and biological devices. Among all the NIL processes, roll-to-roll nanoimprinting is regarded best for having the attributes of low cost, continuous, simple, and energy-efficient process for nanoscale device fabrication. However, large-area printing is limited by the master mold deformation. In this study, a finite element model (FEM) has been constructed to assess the deformation of the roll mold adhesively wrapped on the carbon fiber reinforced material (CFRP) base roll. This study also optimizes the deformations in the metallic roll mold with respect to nip-forces applied in the printing process of nano-fabrication on large scale. The numerical simulations were also conducted to evaluate the deflection in roll mold assembly due to gravity. The results have shown decreasing trend of the deformation with decreasing nip-force. Also, pressure uniformity of about 40% has been optimized by using the current numerical model along with an acceptable deflection value in the vertical axis due to gravity.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.11a
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• pp.6-7
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• 2021

Although the development of free-form architectural technology continues, it consumes a lot of money and time due to the one-time formwork and the difficulty of maintaining quality due to manual work. To this end, in this study, a shape connection technique was proposed and verified to improve the limitations of implementing the curved surface of the existing lower multi-point press. In order to improve the accuracy of the shape, a curved surface was implemented using a silicon cap and a silicon plate. As a result of the error analysis of the shape, a small value of less than 3 mm was found. This study can implement more accurate curved surfaces than conventional technologies and produce high-quality free-form panels.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2004.05a
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• pp.620-623
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• 2004

Conventionally injection molds & dies are manufactured through an order-oriented manner. This brings unexpected orders into the shop floor such as hot order, re-work, and new types of mold & dies. Thus, there needs appropriate resource assignment plans considering the available times of machines and workers. Further, a scheduling system is required that can create work schedules periodically or by customers' requests. Yet, in small & medium sized mold & die makers, production schedules usually depend on the shop floor workers' experience and their manual preparation. Hence, developed in this study is a scheduling management system (SMS) based on order release and review (ORR) in small and medium sized mold & die companies. The proposed SMS considers delivery dates as well as flexible work schedules, so as to meet frequent changes of customers' order. The system can provide effective resource assigning and work scheduling plans, securing standard data associated with shop floors. Furthermore, the system pursues economical schedules for companies' needs, equipped with an available to promise (ATP) function that can effectively accommodate the changes of production plans.

• Journal of the Society of Naval Architects of Korea
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• v.50 no.5
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• pp.349-354
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• 2013

The blades of flexible propellers are formed by overlaying and adhering many layers of thin glass-fiber fabric sheets, are compressed and dried in the rigid mold. The current manufacturing process can not avoid the rather irregular deformation of the blades composed of non-isotropic non-uniform fabric structures, and inevitably introduces the different shape-forming errors between blades. In this paper, several flexible model propellers are precisely measured with three-dimensional optical instrument and compared with the original design geometry. The model propellers with the as-measured geometry are evaluated with the lifting-surface-theory-based propeller analysis code. The open-water performance are presented and discussed. The importance of the manufacturing accuracy is addressed to be able to apply the flexible propellers for propulsion of marine vehicles.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.6
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• pp.30-36
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• 2013

An FFD(flexible fine die) is an embossed mold that consists of a thin plate ranging from 0.6 to 3 mm in thickness. FFDs are primarily used for cutting LCD films and F-PCB sheets. In the high-speed micro-milling process of flexible fine dies, the lubrication and cooling of the cutting edges is very important from the aspect of eco machining and cutting performance. In this paper, a comparative study of tool wear and surface roughness between cutting fluid and hybrid lubrication for eco-machining of FFD was conducted for processes of high-speed machining of highly hardened material (STC5, HRC52). Especially, the incorporated fluid method for eco machining, in which the cutting performances can be simultaneously measured, was introduced. The machining results show that hybrid lubrication, instead of conventional cutting fluid, leads to excellent tool wear and surface roughness and represents the proper conditions for eco micro-machining of flexible fine dies.

• Design & Manufacturing
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• v.14 no.4
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• pp.65-70
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• 2020

Partial reinforcement of sheet metal parts with CFRP patch is a technology that can realize ultra-lightweight body parts while overcoming the high material cost of carbon fiber. Performing these patchworks with highly productive press equipment solves another issue of CFRP: high process costs. The A-pillar is the main body part and has an undercut shape for fastening with other parts such as roof panels and doors. Therefore, it is difficult to bond CFRP patches to the A-pillar with a general press forming tool. In this paper, a flexible system that applies uniform pressure to complex shapes using ceramic particles and silicone rubber is proposed. By benchmarking various A-pillars, a reference model with an undercut shape was designed, and the system was configured to realize a uniform pressure distribution in the model. The ceramic spherical particles failed to realize the uniform distribution of high pressure due to their high hardness and point contact characteristics, which caused damage to the CFRP patch. Compression equipment made of silicone rubber was able to achieve the required pressure level for curing the epoxy. Non-adhesion defects between the metal and the CFRP patch were confirmed in the area where the bending deformation occurred. This defect could be eliminated by optimizing the process conditions suitable for the newly developed flexible system.

• Journal of the Microelectronics and Packaging Society
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• v.30 no.2
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• pp.1-12
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• 2023

In the current era of the global mobile smart device revolution, electronic devices are required in all spaces that people interact with. The establishment of the internet of things (IoT) among smart devices has been recognized as a crucial objective to advance towards creating a comfortable and sustainable future society. In-mold electronic (IME) processes have gained significant industrial significance due to their ability to utilize conventional high-volume methods, which involve printing functional inks on 2D substrates, thermoforming them into 3D shapes, and injection-molded, manufacturing low-cost, lightweight, and functional components or devices. In this article, we provide an overview of IME and its latest advances in application. We review biomimetic nanomaterials for constructing self-supporting biosensor electronic materials on the body, energy storage devices, self-powered devices, and bio-monitoring technology from the perspective of in-mold electronic devices. We anticipate that IME device technology will play a critical role in establishing a human-machine interface (HMI) by converging with the rapidly growing flexible printed electronics technology, which is an integral component of the fourth industrial revolution.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.11
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• pp.975-979
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• 2014

Transparent conductive films (TCF) with excellent electrical properties and high mechanical flexibility have been widely studied because of their potential for application in optoelectronic devices such as light-emitting diodes, paper displays and organic solar cells. In this paper, we report on low-resistance and high-transparent TCF for flexible device applications. To fabricate a high-resolution roll imprinted TCF, the following steps were performed: the design and manufacture of an electroforming stamp mold, the fabrication of high-resolution roll imprinted on flexible film, the manufacture of Ag-nano paste which was filled into patterned film using a doctor blade process. Also, we was demonstrated with the successful application(ITO free organic photovoltaic) of the developed flexible TCF.

• Design & Manufacturing
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• v.16 no.3
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• pp.22-27
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• 2022

The demand for new processing technology that can improve productivity is increasing in industries that require large-scale and various products. In response to this demand, a robot machining system with flexibility is required. Because of the low rigidity of the robot, the robot machining system has a large error during machining and is vulnerable to vibration generated during machining. Vibration generated during machining deteriorates machining quality and reduces the durability of the machine. To solve this problem, a stage for fixing the spindle during machining is required. In order to compensate for the robot's low rigidity, a system combining a piezoelectric actuator for generating a large force and a guide mechanism to actuate with a desired direction is required. Since the rigidity of flexible hinges varies depending on the structure, it is important to optimal design the flexible hinge and high-rigidity system. The purpose of this research is to make analytic model and optimize a flexible hinge and to design a high rigidity stage. In this research, to design a flexible hinge stage, a concept design of system for high rigidity and flexure hinge modeling is carried out. Based on analytic modeling, the optimal design for the purpose of high rigidity is finished and the optimal design results is used to check the error between the modeling and actual simulation results.