• Polymer(Korea)
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• v.26 no.3
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• pp.316-325
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• 2002

The deformation and coalescence behaviors of immiscible LDPE/PS blends (86.5/13.5 vol%) prepared by internal mixer were studied using rheometer and scanning electron microscope. The fine droplets coagulated at initial stage of mixing, and deformed fiber at large strain. The critical capillary number was calculated according to the empirical equation of De Bruijn and it was 0.95, the local capillary number was 3.867. The polymer blends were annealed at $200^{\circ}C$ for various time to investigate morphological change of polymer blends. The maximum size of droplet after annealing at $200^{\circ}C$ was found at ${\gamma}$=1798, and there was destruction of the morphology at 15 minutes of annealing time. The viscosity of matrix was critical to determine a coalescence of droplet.

• The Journal of the Korea Contents Association
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• v.20 no.7
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• pp.636-652
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• 2020

Purpose: This study aimed to have an in-depth understanding of the structure and essence of the living experiences of unmarried mothers institutionalized after childbirth through phenomenological research. Methods: The data were collected through in-depth interview with 9 unmarried mothers from October 1, 2016 to February 2017 and this is qualitative research using Colazzi's phenomenological research method. Results: The living experiences of unmarried mothers institutionalized after childbirth had 15 themes in 4 theme clusters: 'childbirth and parenting,' 'living in women's refuge,' 'becoming independent as proud mother,' and 'disentangled thread.' Conclusion: After childbirth, unmarried mothers experienced psychological pressure from the need to cope with lonely and wearing reality by themselves but struggled to overcome the reality together with their child. Unmarried mothers hoped to live the life they chose proudly and happily together with their child. It is therefore necessary to give residential and environmental support to unmarried mothers in pursuit of their stable living and to change the awareness in the whole society with the aim of removing negative social attitude and discrimination, accepting differences, and living together.

• Journal of Korean Neurosurgical Society
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• v.50 no.3
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• pp.173-178
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• 2011

Objective : The rat middle cerebral artery thread-occlusion model has been widely used to investigate the pathophysiological mechanisms of stroke and to develop therapeutic treatment. This study was conducted to analyze energy metabolism, apoptotic signal pathways, and genetic changes in the hippocampus of the ischemic rat brain. Methods : Focal transient cerebral ischemia was induced by obstructing the middle cerebral artery for two hours. After 24 hours, the induction of ischemia was confirmed by the measurement of infarct size using 2,3,5-triphenyltetrazolium chloride staining. A cDNA microarray assay was performed after isolating the hippocampus, and was used to examine changes in genetic expression patterns. Results : According to the cDNA microarray analysis, a total of 1,882 and 2,237 genes showed more than a 2-fold increase and more than a 2-fold decrease, respectively. When the genes were classified according to signal pathways, genes related with oxidative phosphorylation were found most frequently. There are several apoptotic genes that are known to be expressed during ischemic brain damage, including Akt2 and Tnfrsf1a. In this study, the expression of these genes was observed to increase by more than 2-fold. As energy metabolism related genes grew, ischemic brain damage was affected, and the expression of important genes related to apoptosis was increased/decreased.Conclusion : Our analysis revealed a significant change in the expression of energy metabolism related genes (Atp6v0d1, Atp5g2, etc.) in the hippocampus of the ischemic rat brain. Based on this data, we feel these genes have the potential to be target genes used for the development of therapeutic agents for ischemic stroke.

• The Journal of Korean Academy of Prosthodontics
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• v.39 no.4
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• pp.366-375
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• 2001

The objective of this study was to investigate the surface contact and screw joint stability between screw and implant interface by use of sealer. The implants evaluated in this study were Steri-Oss futures(Hexlock $3.8D{\times}10mm$: Steri-Oss, Yorba Linda, CA), and Steri-Oss staight abutment. Titanium alloy screws were used to secure abutments to implants. The other titanium alloy screws applicating sealer(Impla-Seal, Implant Support Systems, Inc. Irvine, CA) were used to secure abutments to implants. In one another sample, 6kg of force was applied during simulated intraoral movements after abutment screws were secured to the implants with sealer. All samples were cross sectioned with sandpaper and polished with $0.1{\mu}m\;Al_2O_3$. Then samples were recorded with an scanning electron microscope. The results were as follows : 1. In the case of titanium alloy screw, irregular contacts and relatively large gap were present at thread mating surface. Also abutment screw/implant interface demonstrate incomplete seating and only one surface contact of threads between implant and screw. 2. In the case of titanium alloy screw applecating sealer, sealer was present between implant and screw. Therefore implant and screw had relatively close and tight contact without the presence of large gap. 3. On the other hand, in the case of titanium alloy screw applicating sealer and dynamic loading of suprastructures, sealer was partially present between implant and screw. Conclusively, sealer fills voids, creating a barrier to moisture and bacteria. In addition, loading of suprastructures may change the situation and limit the indications for gap sealing.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.5
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• pp.131-136
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• 2016

Currently, an EDM tapping procedure has comprised some parts of the engraving discharge process for the press die. Usually, tapping has been used in cases where we are unable to mechanically machine using steelwork processes due to an increase in the hardness of a material after heat treatment in relation to a design change or missing process. Here, we analyze the influence of discharge tap shape on discharge time, discharge current, and the number of repetition conditions when a cold-work tool steel (STD11) has been treated with a discharge tapped by a screw-shaped cu electrode. The most important influence on processing condition has been determined to be the number of discharge repetitions. As this number increases, the angle reduction of a thread closes to an angle of the electrode via a power generation reduction. The optimal combination of conditions has been determined to be three discharge repetitions, $180{\mu}s$ of discharge time (same as existing regulations), and 25.4A of peak current. A 0.2749db advantage has emerged after comparing between this combination of optimal conditions and the SN rate of existing regulations.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.28 no.2
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• pp.171-183
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• 1992

In this paper, the behaviour of cavitation erosion, influence of corrosion and corrosion control on slide bearing metals for internal combustion engine were investigated, and this experiment was done by the vibratory cavitation erosion tester. The main results obtained are as follows: 1. With decreasing the space between horn and specimen, the weight loss and its rate increased step by step. But the weight loss and its rate of 0.2mm space decreased conversely more than that of 0.4mm space at early stage. 2. The weight loss and its rate with change of pH were appeared to the order of pH2>pH12>pH7>pH4. And the weight loss and its rate at pH 4 decreased at best. 3. The weight loss and its rate by cavitation erosion for bearing metals were shown to the order of W.M7>W.M1>K.M4. 4. There appeared mainly small pit hole at pH2, and appeared the pit of netting thread type at pH12 by the results of the damaged surfaces at pH2 and pH12 environments that were sensitive to cavitation erosion. 5. With increasing the viscosity of lubricating oil, the weight loss rate by cavitation erosion became dull at the space below 0.5mm. 6. The protective efficiency of cavitation erosion-corrosion is superior inhibitor of chormate(25 ppm) to cathodic protection.

• The KIPS Transactions:PartC
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• v.16C no.1
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• pp.101-108
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• 2009

The data broadcasting service, which is growing remarkably today, provides viewers with useful information as well as high quality video and audio. Service information is a kind of additional data that contains a wide range of information such as channel list and/or program title. Each service information is transmitted in the form of a table. And most standard committees have specified their own table list used for carrying the service information. Consequently, It causes incompatibility among services that each broadcast operators produce because the tables that they use differ from each other. In this paper, we propose a general-purpose service information processing system for an integrated data broadcasting middleware that is compatible with heterogenous broadcasting environments. The system is able to change its target table list dynamically without any code modification. Futhermore, we also adopted a thread pool model for efficient parsing and event dispatching.

• Tribology and Lubricants
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• v.35 no.1
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• pp.65-70
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• 2019

Self-loosening of bolts owing to external forces occurs in several machines that are clamped by bolts and nuts. This study focuses on the self-loosening of the aiming bolt of the head lamp in a vehicle. It is important to prevent the aiming bolt from self-loosening as it has a decisive effect on the angle of the head lamp. A nut clamped with a bolt, known as a retainer, is made of plastic and has a partial screw thread. In addition, a transverse load has a considerable impact on the self-loosening of a bolt. We concentrate on the self-loosening of a bolt by a transverse load. The aim of this study is to define the limits of the external force that loosen the bolt. Based on the above conditions, we derive a theoretical equation and develop a numerical analysis program that can calculate the limiting forces for self-loosening. To verify the developed program, we design a test device that can measure the self-loosening by applying sliding forces to the aiming bolt. Using this method, we can draw the following conclusions. First, the developed testing device is suitable to prove the theory for calculating the self-loosening force. Second, the equation confirms the relationship of bolt self-loosening between resistance torque and shear force. Finally, the equation obtains the minimum value of the resistance torque required to decrease the change in the angle of the head lamp, thereby improving the possibility of increasing the stability of the head lamp.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.589-592
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• 2016

The period of the previous multi-core could be helped to improve program performance, based on the development of the hardware. However, one of the core performance enhancements for this encounter limitations and become the common way of multi-core with multiple cores. Modern programming concurrency that improves the conventional method for using threads of the kernel level in order to use the multi-core come to the fore. Using modern lightweight thread concurrency programming is to optimize the benefits of multi-core. Also sharing the absence of available data that can change is a major consideration when writing concurrent code. This paper describes the key considerations when creating a discussion concurrent code, and these issues are being supported in any way in the language of one 'go' of technologies that support the modern concurrency, and even how to write better code concurrency.

• KIPS Transactions on Computer and Communication Systems
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• v.12 no.4
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• pp.127-134
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• 2023

This paper describes how to port the eCos operating system and PROFINET communication stack developed based on gcc to the IAR compiler. The eCos operating system provides basic functions such as multi-thread, TCP/IP, and device driver for PROFINET operation, so there is no need to change it when developing PROFINET applications. Therefore, in this study, we reuse an eCos library built with gcc and it link with PROFINET communication stack that are ported to IAR complier. Due to the different of the gcc and IAR linker, symbol definitions and address of the constructors should be changed using the external tool that generates symbol definitions and address of the constructors from MAP file. In order to verify the proposed method, it was confirmed that the actual I/O was operating normally through PROFINET IRT communication by connecting to the Siemens PLC. IAR compiler has better performance in both the compile time and the size of the generated binary. The proposed method in this study is expected to help port various open sources as well as eCos and PROFINET communication stacks to other compilers.