• Elastomers and Composites
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• v.53 no.2
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• pp.39-47
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• 2018

Styrene-butadiene rubber (SBR) is widely used in tire treads due to its excellent abrasion resistance, braking performance, and reasonable cost. Depending on the polymerization method, SBR is classified into solution-polymerized SBR (SSBR) and emulsion-polymerized SBR (ESBR). ESBR is less expensive and environmentally friendlier than SSBR because it uses water as a solvent. A higher molecular weight is also easier to obtain in ESBR, which has advantages in mechanical properties and tire performance. In ESBR polymerization, a surfactant is added to create an emulsion system with a hydrophobic monomer in the water phase. However, some amount of surfactant remains in the ESBR during coagulation, making the polymer chains in micelles clump together. As a result, it is well-known that residual surfactant adversely affects the physical properties of silica-filled ESBR compounds. However, researches about the effect of residual surfactant on the physical properties of ESBR are lacking. Therefore, in this study we compared the effects of remaining surfactant in ESBR on the mechanical properties of silica-filled and carbon black-filled compounds. The crosslinking density and filler-rubber interaction are also analyzed by using the Flory-Rehner theory and Kraus equation. In addition, the effects of surfactant on the mechanical properties and crosslinking density are compared with the effects of TDAE oil (a conventional processing aid).

• Smart Structures and Systems
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• v.12 no.3_4
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• pp.363-379
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• 2013

Dynamic displacement of structures is an important index for in-service structural condition and behavior assessment, but accurate measurement of structural displacement for large-scale civil structures such as long-span bridges still remains as a challenging task. In this paper, a vision-based dynamic displacement measurement system with the use of digital image processing technology is developed, which is featured by its distinctive characteristics in non-contact, long-distance, and high-precision structural displacement measurement. The hardware of this system is mainly composed of a high-resolution industrial CCD (charge-coupled-device) digital camera and an extended-range zoom lens. Through continuously tracing and identifying a target on the structure, the structural displacement is derived through cross-correlation analysis between the predefined pattern and the captured digital images with the aid of a pattern matching algorithm. To validate the developed system, MTS tests of sinusoidal motions under different vibration frequencies and amplitudes and shaking table tests with different excitations (the El-Centro earthquake wave and a sinusoidal motion) are carried out. Additionally, in-situ verification experiments are performed to measure the mid-span vertical displacement of the suspension Tsing Ma Bridge in the operational condition and the cable-stayed Stonecutters Bridge during loading tests. The obtained results show that the developed system exhibits an excellent capability in real-time measurement of structural displacement and can serve as a good complement to the traditional sensors.

• Safety and Health at Work
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• v.14 no.3
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• pp.303-308
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• 2023

Background: Occupational workers at altitudes are more prone to falls, leading to catastrophic outcomes. Acrophobia, height-related anxiety, and affected executive functions lead to postural instabilities, causing falls. This study investigated the effects of repeated virtual height exposure and training on cognitive processing and height-related anxiety. Methods: Twenty-eight healthy volunteers (age 20.48 ± 1.26 years; mass 69.52 ± 13.78 kg) were recruited and tested in seven virtual environments (VE) [ground (G), 2-story altitude (A1), 2-story edge (E1), 4-story altitude (A2), 4-story edge (E2), 6-story altitude (A3), and 6-story edge (E3)] over three days. At each VE, participants identified occupational hazards present in the VE and completed an Attitude Towards Heights Questionnaire (ATHQ) and a modified State-Trait Anxiety Inventory Questionnaire (mSTAIQ). The number of hazards identified and the ATHQ and mSTAIQ scores were analyzed using a 7 (VE; G, A1, A2, A3, E1, E2, E3) x 3 (DAY; DAY 1, DAY 2, DAY 3) factorial repeated measures analysis of variance. Results: The participants identified the lowest number of hazards at A3 and E3 VEs and on DAY 1 compared to other VEs and DAYs. ATHQ scores were lowest at G, A1, and E1 VEs. Conclusion: Cognitive processing is negatively affected by virtual altitudes, while it improves with short-term training. The features of virtual reality, such as higher involvement, engagement, and reliability, make it a better training tool to be considered in ergonomic settings. The findings of this study will provide insights into cognitive dual-tasking at altitude and its challenges, which will aid in minimizing occupational falls.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.34 no.2
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• pp.125-133
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• 2024

Objectives: The aim of this study is to develop a comprehensive Occupational Safety and Health (OSH) guide for maintenance tasks in semiconductor processing, specifically focusing on etching, deposition, and ion implantation processes. Methods: The development of the OSH guide involved a literature review, consultations with industry experts, and field investigations. It concentrates on Maintenance Work (MW) operations in these specialized areas. Results: The result is a detailed OSH guide tailored to MW in etching, deposition, and ion implantation facilities within semiconductor processing. This guide is structured to assist maintenance workers through pre-, during and post-MW phases, ensuring easy comprehension and adherence to safety protocols. It highlights the necessity of safety and health measures throughout the MW process to protect personnel. The guide is enriched with real-life scenarios and visual aids, including cartoons and photographs, to aid in the understanding and implementation of safety and health principles. Conclusions: This OSH guide is designed to enhance the protection of workers engaged in maintenance activities in the electronics sector, particularly in semiconductor manufacturing. It aims to improve compliance with safety and health standards in these high-risk environments.

• Journal of Positioning, Navigation, and Timing
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• v.4 no.3
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• pp.115-122
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• 2015

Global Positioning System (GPS) is used in various fields such as communications systems, transportation systems, e-commerce, power plant systems, and up to various military weapons systems recently. However, GPS receiver is vulnerable to jamming signals as the GPS signals come from the satellites located at approximately 20,000 km above the earth. For this reason, various anti-jamming techniques have been developed for military application systems especially and it is also required for commercial application systems nowadays. In this paper, we proposed a dual-channel Global Navigation Satellite System (GNSS) RF ASIC for digital pre-correlation anti-jam technique. It not only covers all GNSS frequency bands, but is integrated low-gain/attenuation mode in low-noise amplifier (LNA) without influencing in/out matching and 14-bit analogdigital converter (ADC) to have a high dynamic range. With the aid of digital processing, jamming to signal ratio is improved to 77 dB from 42 dB with proposed receiver. RF ASIC for anti-jam is fabricated on a 0.18-μm complementary metal-oxide semiconductor (CMOS) technology and consumes 1.16 W with 2.1 V (low-dropout; LDO) power supply. And the performance is evaluated by a kind of test hardware using the designed RF ASIC.

• Food Science of Animal Resources
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• v.40 no.1
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• pp.74-86
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• 2020

Horse meat is nutritionally adequate to the elderly, but it has a comparatively hard texture in contrast to most of the food. In practice, the meat intake in the elderly is generally bated because the relatively difficult texture of the meat can diminish mastication. Thus, strategies are being developed to produce meat products remanding detracted mastication exertion and possibly exalt ingestion and nutritional stand, in the elderly. Hence, the effects of enzymes on textural characteristics of horse meat were studied, because they have well-known favorable efficacy on the meat tenderness by causing important demotion of the myo-fibrillar protein and collagen. Four treatments namely, papain, bromelin, pepsin, and pancreatin, alongside one control were invoked to the horse meat. Their effects on the texture parameters were determined. All the above enzymatic treatments significantly reduced hardness and resilience (p<0.001). These results present opportunities to produce essential fatty acids fortified horse meat with soft texture and satisfied technological characteristics. The intake of the essential fatty acids intensified horse meat could aid the elderly to get their aimed essential fatty acid demands. Results also suggest that horse meat tenderized through enzymatic processing stand for auspicious options for the comprehension of texture-revised diets in the elderly population.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.4
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• pp.569-577
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• 2018

In this paper, with the aid of information which is included within data, preprocessing algorithm-based black plastic classifier is designed. The slope and area of spectrum obtained by using laser induced breakdown spectroscopy(LIBS) are analyzed for each material and its ensuing information is applied as the input data of the proposed classifier. The slope is represented by the rate of change of wavelength and intensity. Also, the area is calculated by the wavelength of the spectrum peak where the material property of chemical elements such as carbon and hydrogen appears. Using informations such as slope and area, input data of the proposed classifier is constructed. In the preprocessing part of the classifier, Principal Component Analysis(PCA) and fuzzy transform are used for dimensional reduction from high dimensional input variables to low dimensional input variables. Characteristic analysis of the materials as well as the processing speed of the classifier is improved. In the condition part, FCM clustering is applied and linear function is used as connection weight in the conclusion part. By means of Particle Swarm Optimization(PSO), parameters such as the number of clusters, fuzzification coefficient and the number of input variables are optimized. To demonstrate the superiority of classification performance, classification rate is compared by using WEKA 3.8 data mining software which contains various classifiers such as Naivebayes, SVM and Multilayer perceptron.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.5
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• pp.1074-1083
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• 1993

NC simulation has been used to replace the test cutting of NC machining. Although it can reduce the NC part programming effort, it still has a problem. If any error is found during the simulation, then the part has to be reprogrammed and it is time consumming. This paper presents a method for verifying and editing the NC code after the post-processing without going back to the part programming stage. A data structure and an algorithm to verify and edit the NC code interactively with the aid of graphics is introduced. Z-map method is used for the shaded image display and cross-sectional view display of the macined parts. The method was implemented in a IBM/PC-386 with MS-Windows software, and the multi-window function of the of the MS-Windows is used for the simultaneous editing and verification.

• 한국HCI학회:학술대회논문집
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• 2008.02a
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• pp.240-244
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• 2008

This paper presents an EMG-based wireless and wearable computer interface. The wearable device contains 4 channel EMG sensors and is able to acquire EMG signals using signal processing. Obtained signals are transmitted to a host computer through wireless communication. EMG signals induced by the volitional movements are acquired from four sites in the lower limb to extract a user's intention and six classes of wrist movements are discriminated by employing an artificial neural network (ANN). This interface could provide an aid to the limb disabled to directly access to computers and network environments without conventional computer interface such as a keyboard and a mouse.

• Transactions of Materials Processing
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• v.9 no.3
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• pp.233-241
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• 2000

It is well known that the quality and efficiency of the design of metal forming processes can be significantly improved with the aid of effective numerical simulations. In the present study, a two-and three-dimensional finite element simulation system, CAMP form, was developed for the analysis of metal forming processes in the PC environment. It is composed of a solver based on the thermo-rigid-viscoplastic approach and graphic user interface (GUI) based pre-and post-processors to be used for the effective description of forming conditions and graphic display of simulation results, respectively. In particular, in the case of CAMPform 2D (two-dimensional), as the solver contains an automatic remeshing module which determines the deformation step when remeshing is required and reconstructs the new mesh system, it is possible to carry out simulations automatically without any user intervention. Also, the forming analysis considers ductile fracture of the workpiece and wear of dies for better usage of the system. In the case of CAMPform 3D, general three-dimensional problems that involve complex die geometries and require remeshing can be analyzed, but full automation of simulations has yet to be achieved. In this paper, the overall structure and computational background of CAMPform will be briefly explained and analysis results of several forming processes will be shown. From the current results, it is construed that CAMPform can be used in providing useful information to assist the design of forming processes.