• Korean Journal of Metals and Materials
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• v.48 no.11
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• pp.1035-1040
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• 2010

The research efforts on GaN-based light-emitting diodes (LEDs) keep increasing due to their significant impact on the illumination industry. Surface mount technology (SMT) is widely used to mount the LED packages for practical application. In surface mount soldering both the device body and leads are intentionally heated by a reflow process. We studied on the effects of multiple reflows on microstructural variation and joint strength of the solder joints between the LED package and the substrate. In this study, Pb-free Sn-3.0Ag-0.5Cu solder and a finished pad with organic solderability preservatives (OSP) were employed. A $Cu_6Sn_5$ intermetallic compound (IMC) layer was formed during the multiple reflows, and the thickness of the IMC layerincreased with an increasing number of reflows. The shear force decreased after three reflows. From the observation of the fracture surface after a shear test, partially brittle fractures were observed after five reflows.

• PNF and Movement
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• v.17 no.2
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• pp.215-222
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• 2019

Purpose: The objective of this study was to investigate whether augmented low-dye taping treatment, which consists of low-dye, reverse-six, and calcaneal-sling taping, is effective in alleviating the collapse of the medial longitudinal arch, which is used for physical balancing during one leg standing. Methods: The subjects comprised 27 students in their 20s whose navicular bone height was lowered by 10 mm or more when evaluated using the navicular drop test. Those with interference factors like deformities, fractures, or traumas were excluded. Frequency-division multiplexing was used to measure one leg standing, and the method to avoir the average each time after 3 times of measurement was applied. Results: Significant differences in the center of pressure (COP) path length, COP average velocity, and forefoot force were observed during left leg standing (p<0.05), but for right leg standing, only changes in forefoot force were noted. Conclusion: Based on the changes to the non-dominant leg in terms of COP path length, COP average velocity, and forefoot force, the immediate effect of augmented low-dye taping, which combines three types of anti-pronation taping, on one leg standing balance in people with flat feet was confirmed.

• Journal of Convergence for Information Technology
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• v.11 no.1
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• pp.128-135
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• 2021

The possibility and effectiveness of cryopreservation was determined to assess survival rates and improve stock management of thawed embryos of Manila clam, Ruditapes philippinarum. The ideal freezing rates were designed and tested to allow cryoprotectants to equilibrate across the membrane during freezing. Survival rates ranging from 0 to 64.3% were obtained using a stepwise freezing protocol compared with 82.3% control rates. Embryos of Ruditapes philippinarum were equilibrated in 2 CPAs plus sea water for 10 min at 25℃ and then cooled at -1℃/min from 20℃ to -12℃. Straws containing more than 100 embryos were held at 12℃ for 5 min allowing equilibration after seeding and slowly cooled at 2℃/min. to -35℃ for 30 min for equilibration before quenching in liquid nitrogen. Dimethyl sulfoxide (DMSO) is the best cryoprotectant indicated for embryos of R. philippinarum with a survival rate of 64.3±3.28% in the presence of 2.0 M DMSO.

• Journal of the Microelectronics and Packaging Society
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• v.28 no.2
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• pp.45-50
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• 2021

As the difficulty of flip chip products increases, there is a growing interest in the material of flux, which is safe from the solder wetting and reliability. In the case of no clean flux, there is merit in terms of process efficiency because there is no cleaning process. But Cu migration and delamination can be occurred if the residue remains after the reflow process. In this study, major element materials, solvent and activator, are changed and confirmed effect of non-wet and reliability in the package environment. Stability of materials were secured through storage stability evaluation, and we found out non-wet zero materials through the application of two types of solvent and activator with different boiling point and the increase of activator content. After reliability test, no delamination was found in the plane analysis, which secured the final composition of low residue flux.

• Tribology and Lubricants
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• v.38 no.3
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• pp.93-100
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• 2022

Micro-light emitting diode (micro-LED) displays offer numerous advantages such as high brightness, fast response, and low power consumption. Hence, they are spotlighted as the next-generation display. However, defective LEDs may be created due to non-uniform contact loads or LED alignment errors. Therefore, a repair process involving the replacement of defective LEDs with favorable ones is necessitated. The general repair process involves the removal of defective micro-LEDs, interconnection material transfer, as well as new micro-LED transfer and bonding. However, micro-LEDs are difficult to repair since their size decreases to a few tens of micron in width and less than 10 ㎛ in thickness. The conventional nozzle-type dispenser for fluxes and the conventional vacuum chuck for LEDs are not applicable to the micro-LED repair process. In this study, transfer conditions are determined using a micro stamp for repairing micro-LEDs. Results show that the aging time should be set to within 60 min, based on measuring the aging time of the flux. Additionally, the micro-LEDs are subjected to a compression test, and the result shows that they should be transferred under 18.4 MPa. Finally, the I-V curves of micro-LEDs processed by the laser and hot plate reflows are measured to compare the electrical properties of the micro-LEDs based on the reflow methods. It was confirmed that the micro-LEDs processed by the laser reflow show similar electrical performance with that processed by the hot plate reflow. The results can provide guidance for the repair of micro-LEDs using micro stamps.

• Journal of IKEEE
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• v.26 no.3
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• pp.396-400
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• 2022

In this study, an ICT-based underwater communication monitoring device for underwater structures is implemented based on lifting fixture that transport human bodies found on the seabed to sea level. The lifting fixture is packaged with a retback, sideback, and cartridge that injects air. Monitoring systems are developed in a mobile manner in a portable structure. The underwater ultrasonic sensor signal is supplied using a USB port, and the O/S consists of Linux. For the underwater communication dong test, a measurement test was conducted in real time from 6m to 40m in depth on the east coast. The ultrasonic sound sensor is converted to 2,400 bps to verify the transmission error according to the duality. The communication speed of sensor to monitoring is 115,200 bps, and the speed of communication from controller to receiver is 2,400 bps. In the commercialization stage of the lifting device, it is easy to develop a low-end type and the compatibility is wide.

• Journal of Korea Entertainment Industry Association
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• v.14 no.3
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• pp.229-236
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• 2020

In this paper, the tone of Daegeum, one of the most representative wind instruments of our country, was analyzed. Daegeum is widely used as Jeongak Daegeum and Sanjo Daegeum, which are played in royal and wind music, and Sanjo Daegeum is mainly played in Sanjo, Sinawi and folk music. The reason why the two pieces of music are being played in different music genres is due to the improvement of the length of the pipe and the location of the finger holes, allowing the Sanjo Daegeum to perform faster than Jeongak Daegeum, apply various techniques, and make the choice of musical instruments harmonized with music by making the difference in tone. For timber analysis of Jeongak Daegeum and Sanjo Daegeum, the composition of the overtones was visually verified through Spectrogram and Spectrum Analizer, in which the results of recordings were recorded by playing octave low, flat, and octave high positions with the same power. From this, Jeongak Daegeum, which is rich in low-pitched sound, harmonizes with solemn music such as royal music, and Sanjo Daegeum, which has a relatively clear high-pitched sound, is well suited to bright music such as solo music.

• (The) Research of the performance art and culture
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• no.42
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• pp.183-204
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• 2021

This study analyzed the placement and interactivity of the immersive performance . In the sense of place, it was analyzed that first, walked and followed the living spaces and streets of the victims of the Sewol ferry, and second, through this, the participants induce a transfer experience to become the main character of the performance. In terms of interactivity, participants were able to carry out various forms of participation, and as a result, they analyzed that they had relieved debt consciousness or exerted healing effects. In addition, it was confirmed that they pursued solidarity and sympathy by focusing more on the city 'Ansan' rather than the story of the Sewol ferry. Through these results, it can be seen that has many social functions, a variety of art forms, and is differentiated from other immersive performances. So, it is necessary to consider the continuous holding.

• Journal of the Korea Society of Computer and Information
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• v.29 no.6
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• pp.101-112
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• 2024

In this paper, we present EDF (Event Data Factory), an interactive tool designed to assist event log generation for process mining. EDF integrates various data connectors to improve its capability to assist users in connecting to diverse data sources. Our tool employs low-code/no-code technology, along with graph-based visualization, to help non-expert users understand process flow and enhance the user experience. By utilizing metadata information, EDF allows users to efficiently generate an event log containing case, activity, and timestamp attributes. Through log quality metrics, our tool enables users to assess the generated event log quality. We implement EDF under a cloud-based architecture and run a performance evaluation. Our case study and results demonstrate the usability and applicability of EDF. Finally, an observational study confirms that EDF is easy to use and beneficial, expanding small and medium-sized enterprises' (SMEs) access to process mining applications.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.24 no.2
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• pp.65-71
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• 2018

Paper packs, glass bottles, metal cans, and plastic materials are classified according to packaging material recycling groups that are Extended Producer Responsibility (EPR). In the case of waste paper pack, the compressed cartons are dissociated to separate polyethylene films and other foreign substance, and then these are washed, pulverized and dried to produce toilet paper. Glass bottle for recycling is provided to the bottle manufacturers after the process of collecting the waste glass bottle, removing the foreign substance, sorting by color, crushing, raw materializing process. Waste glass recycling technology of Korea is largely manual, except for removal of metal components and low specific gravity materials. Metal can is classified into iron and aluminum cans through an automatic sorting machine, compressed, and reproduced as iron and aluminum through a blast furnace. In the case of composite plastic material, the selected compressed product is crushed and then recycled through melt molding and refined products are produced through solid fuel manufacturing steps through emulsification and compression molding through pyrolysis. In the recycling process of paper packs, glass bottles, metal cans, and plastic materials, the influx of recycled materials and other substances interferes with the recycling process and increases the recycling cost and time. Therefore, the government needs to improve the legal system which is necessary to use materials and structure that are easy to recycle from the design stage of products or packaging materials.