In this study, we tried to evaluate the mechanical properties of Polycarbonate(PC) and acrylonitrile-butadiene-styrene(ABS) plastic materials, which are frequently used as parts of home appliances and machinery, when repeated impacts were applied. A repeating impact tester for this research was designed and manufactured to apply repetitive impacts. Two types of plastic were repeatedly impacted under a constant load, and a tensile test was performed on the plastic material that was impacted. The tensile strength of PC plastic materials that received impact more than 2000 times was reduced by about 45 % and elongation was reduced by about 10 % when compared to impact free specimens. On the other hand, in ABS plastic, a reduction of tensile strength of about 20 % was observed at about 2,000 impacted specimen, but at about 20,000 repetitive impacted specimen, a tensile strength decrease of about 65 % was observed. And the elongation was reduced by 10 % due to the cyclic harding behavior of the material.
The necessity and the importance of the remanufacturing are increasing day by day along with environmental problems. Many studies are being conducted on remanufacturing, but the research for cleaning is much lacking. This study aims to evaluate the effective cleaning method for remanufacturing of start motors, one of the automobile parts. The cleaning process consists of oil stain removal, drying and rust removal processes. In this study, the two processes were conducted except for the drying process which has little influence on cleaning. The methodology for cleaning agent selection, degreasing and rust removal process was presented. For each methodology, five analysis factors were calculated by two-way comparison according to the process, and the values were evaluated quantitatively by substituting them into the evaluation table. In the selection of cleaning agent, neutral system, ultrasonic cleaning in degreasing, and grinding in rust removal were selected as the best cleaning methods.
According to the research and investigations performed on Port Facilities for cargo-works of hazardous materials around the Port of Busan, a conclusion was drawn that the manually operating foam tower monitors are ineffective as they are hard to access due to the radiant heat under contingency circumstances such as a fire. Moreover, in some cases, the effective range of Foam Tower Monitors are insufficient to reach docked ships and manifolds where hazardous materials are being unloaded. In addition, Dangerous Goods freights are inadequately and inefficiently stored regardless properties of hazardous substances due to complicated local regulations, and some are equipped with inapplicable facilities for docked ships. Therefore, in order to effectively counteract the contingencies and obtain safety, it would be recommended to install adequate facilities.
Continuous industrial development has led to a better quality of life for everyone, even further accelerating industrial growth. Industrial development, however, has also caused environmental degradation, which is posing a serious threat to humanity. It has also encouraged the indiscriminate use of limited resources, causing resource depletion. Efficient resource management based on resource circulation is critical to saving resources. Resource circulation methods are as follows: reducing the use of resources in the manufacturing process, recycling used or reprocessed products and reusing used resources without being reprocessed, remanufacturing with end-of-life products with disassembled parts. Furthermore, remanufacturing process including cleaning, inspection, repairing, and reassembling facilitate performance level as well as new typical products. It is noteworthy that the remanufacturing of machine tools can significantly save resources because their structural parts are substantially large in size. Machine tools have served as a foundation for the manufacturing industry, which has driven Korea's industrial development. Nevertheless, a few research has been reported for remanufacturing technology with used machine tools. Relevant research of developing a remanufacturing process chart and method is prerequisite for saving the resource and environments.
Therefore, it was agreed that an earthquake monitoring station should be set up within the site of Handong University by analyzing drilling data and Disaster such as earthquakes is urgently needed to prepare for earthquakes in that people's lives and national development depend on the nation's ability to manage disasters. Many experts say that the Korean Peninsula is also under the influence of earthquakes and is not a safe zone for earthquakes. A seismological observatory will be established in Pohang to monitor ground sensors and study seismic characteristics through the task of "Development of Smart Sensor-based Intelligent Information Platform in Earthquake Region." Therefore, it was agreed to set up a seismological observatory within the site of Handong University by analyzing drilling data and conducting on-site surveys in northern Pohang, which were heavily damaged by liquefaction and earthquakes. In this study, it was decided to make a comprehensive judgment by considering the geological characteristics of the site, whether it can perform functions, and the convenience of construction and maintenance for the final site of the seismological observatory discussed with Handong University. After completing a feasibility review on selecting a site for Handong University, we will establish a seismological observatory and actively utilize it for seismic research using data from alarm issuance and seismic data in the event of a future earthquake.
There are many accident risks in logging operation of forestry such as struck by felled trees and caught in, under, or between felled trees. These accidents are primarily occurred by not keeping a safe distance between workers. According to the forestry safety instruction, workers are not supposed to go into the safety zone which is a circle with a radius of more 2 times the height of felling tree. However, this rule does not keep because of poor safety consciousness, poor sight and extreme noise of logging operation machines. This problem causes many major accidents every year. To solve this problem, we made forestry safety helmets based on IoT technology. These helmets have functions to make a visual and an acoustic alarm signal when reach the distance between workers within 20 meters. We developed the algorithm to operate the helmet's functions and conducted tests to check the functions. As a result of tests, we assured the normal system operating conditions.
In this Study, as the structure of IT module for smart phone display becomes thin to catch up with slim product trend, the reliability of display module is on the rise as a issue for product design. Especially, almost part of cellular phone should undergo thermal dissipation test. thus many manufacturers have considered design guide line using CAE and simulation for more effective usage of limited resources on the market. This test simulates the case when cellular phone slips through user's fingers while he is talking on the phone. This paper studies a thermal simulation of display module in smart phone. This design for reliability improvements are suggested on the basis of the results of FVM Analysis and display of IT module and smart phone design.
This study proposes a method to improve the sleep stage and efficiency estimation of sleep apnea patients using a UWB (Ultra-Wideband) radar. Motion and respiration extracted from the radar signal were used. Respiratory signal disturbances by motion artifacts and irregular respiration patterns of sleep apnea patients are compensated for in the preprocessing stage. Preprocessing calculates the standard deviation of the respiration signal for a shift window of 15 seconds to estimate thresholds for compensation and applies it to the breathing signal. The method for estimating the sleep stage is based on the difference in amplitude of two kinds of smoothed respirations signals. In smoothing, the window size is set to 10 seconds and 34 seconds, respectively. The estimated feature was processed by the k-nearest neighbor classifier and the feature filtering model to discriminate between the sleep periods of the rapid eye movement (REM) and non-rapid eye movement (NREM). The feature filtering model reflects the characteristics of the REM sleep that occur continuously and the characteristics that mainly occur in the latter part of this stage. The sleep efficiency is estimated by using the sleep onset time and motion events. Sleep onset time uses estimated features from the gradient changes of the breathing signal. A motion event was applied based on the estimated energy change in the UWB signal. Sleep efficiency and sleep stage accuracy were assessed with polysomnography. The average sleep efficiency and sleep stage accuracy were estimated respectively to be about 96.3% and 88.8% in 18 sleep apnea subjects.
The air cleaning unit of K00 IFV(or Infantry Fighting Vehicle) has important roles to make sure the engine of the vehicle works precisely as filtering foreign substances in the air such as dust and sands. The entire components including scavenge fan which is one of the important inner part of the air cleaning unit are developed so that we can produce it domestically and don't need to import it from P⁎⁎ Co., the original maker in United Kingdom. This paper introduces a few verification processes including cleaning efficiency and reliability. As this core unit has developed successfully the improvement of military strength and logistics support can be expected. And design capability, manufacturing skills, maintenance ability of tracked weapon system will be increased thanks to the accumulated technical knowledge obtained from this developing project. Foreign currency savings and reducing operational cost can be expected as well in military industry.
In this study, we conducted technology monitoring to search for the current technology level and new technologies targeting the core technologies selected as "convergence technologies based on advanced ICT". This technology group, selected by the National Research Foundation(NRF) as one of the future-emerging technologies in 2018, consists of 'next-generation millimeter wave wireless communication technology', 'data-centric computing technology', and 'immersive media interface' that can be seen as important technologies in the fourth industrial revolution. It is possible to provide strategic research direction to the R&D-related stakeholders of countries or enterprises by providing information on newly emerged technologies through quantitative analysis based on patent data on these technologies. Therefore, in this study, we proposed a new technology for the convergence technologies based on advaned ICT group through patent data based on the newly emerged IPC code, and also suggested that it can suggest a strategic direction in planning R&D on related technologies.
Recently, various tries to apply ROV (Remotely Operated Vehicle) into underwater are being developed. However, due to underwater environment uniqueness, the additional problem must be taken into account when designing an ROV for the inspection of the underwater structure. This is because a GPS-based information method cannot be applied, and the obtainable image is also dependent on the turbidity. Also, it is necessary to be able to satisfy waterproof and operating speeds in consideration of most practical application environments. This paper describes the design results of the ROV system for underwater structure inspection considering the above problems. The designed system applied INS / DVL for location recognition and was configured to support 3D mapping and stereo camera-based image information using sonar depending on visibility. To satisfy the waterproof, a pressure vessel using a composite material was applied. And over-actuated system using eight thrusters to maintain a stable posture and operating speed was applied also. The designed system was verified by structural analysis and flow analysis also.
In this study, I analyzed problems of safety management system of hazardous substances and proposed improvement measures. By statistics of Korea National Fire Agency it shows that hazardous substances of not less than a designated quantity were 2,180 factorys, 24,732 handling places and 85,218 storing places in 2018. also It has been conformed that Fire accidents break out year after year in factory, etc. so In this study, I analyzed the safety controllers of hazardous substances of the present law and fire statistics. therefore I has been found out the problems that the first, safety controllers' status. the second, There is no laws related design, installation, installation supervision. the third, fire safety inspection. This study will be used a basic data for preventing of extensive hazazardous substances-related accident that is very difficult handling.
Safety and security during the handling of hazardous materials is a great concern for anyone in the field. One driving point in the security field is the ability to detect the source of the danger and take action against it as quickly as possible. Via the usage of a fully convolutional network, it is possible to create the label map of an input image, indicating what object is occupying the specific area of the image. This research employs the usage of U-net, which was constructed in biomedical field segmentation to segment cells, instead of the original FCN. One of the challenges that this research faces is the availability of ground truth with precise labeling for the dataset. Testing the network after training resulted in some images where the network pronounces even better detail than the expected label map. With better detailed label map, the network might be able to produce better segmentation is something to be studied in further research.
Recently, In the production line of batteries, charge and discharge tests are essential to verify battery characteristics. In this case, the battery charging uses a unidirectional AC/DC converter capable of output voltage and current control, and the discharge uses a resistive load. Since this method consumes energy during discharge, it must be replaced with a bi-directional AC/DC converter system capable of charging and discharging. Although it is difficult to replace the connected inverter part of the bi-directional AC/DC converter system due to the high cost, the spread of the solar-connected inverter rapidly increases as the current solar supply business is activated, and thereby the solar-connected type Inverter prices are plunging. If it can be used as a power converter for battery discharge without program modification of the solar-powered inverter, it will have competition. In this paper, propose a new battery discharge system using a combination of a photovoltaic DC/DC simulator and photovoltaic PCS using a battery to be used as a power converter for battery discharge without program modification of a low-cost photovoltaic inverter. In addition, propose an optimal solar characteristic curve for the stable operation of PCS. The validity of the proposed system was verified using a 500[W] class solar DC/DC simulator and a solar PCS prototype.
Capacitor-run single-phase induction motor is cheaper than motors that use permanent magnets and is widely used in home appliances and industries based on relatively high durability and productivity. It can also be operated by line. However speed cannot be controlled because the line frequency is free. In this paper we dealt pole change method one of the method controlling speed of capacitor-run single-phase induction motor. The conventional pole change method is difficult to improve the power and efficiency of the motor because the composition of the pole change device is complex and do not have enough area of the windings because of windings not used according to the driving conditions. In this paper, we proposed the pole change method that is used main windings and auxiliary windings at 4 poles operation and used auxiliary windings as compensation windings at 2 poles operation. The proposed method was verified through finite element analysis.
Liquid filling machines are frequently used in packaging fields; however, there exists a problem in precisely measuring the quantity of the liquid. In the case where the liquid filling machine is not properly metered, there may be issues, such as the fluid exceeding the capacity or chemicals being exposed outside. In this paper, we propose a smart injection nozzle device that can solve the issues stated above. The proposed smart injection nozzle can raise the nozzle according to the water level to remove bubbles and inject the accurate amount of fluid. In addition, the efficiency of the logistics process is enhanced by the smart QR code. Through experiments using the developed smart injection nozzle device, we have noticed that the accuracy of injection capacity, nozzle position, reaction time and building data exceeded the target value. Therefore, it expected that this machine will give more production and save a lot of manpower for packaging industry.
Deep learning methods have been effectively used to provide great improvement in various research fields such as machine learning, image processing and computer vision. One of the most frequently used deep learning methods in image processing is the convolutional neural networks. Compared to the traditional artificial neural networks, convolutional neural networks do not use the predefined kernels, but instead they learn data specific kernels. This property makes them to be used as feature extractors as well. In this study, we compared the quality of CNN features for traditional texture feature extraction methods. Experimental results demonstrate the superiority of the CNN features. Additionally, the recognition process and result of a pioneering CNN on MNIST database are presented.
Foot drop is a common symptom in stroke patients due to central nervous system (CNS) damage, which causes walking disturbances. Functional electrical stimulation (FES) is an effective rehabilitation method for stroke patients with CNS damage. Aim of this study was to determine the effectiveness of 6 weeks FES walking training based lower limb muscle synergy of stroke patients. Lower limb muscle synergies were extracted from electromyography (EMG) using a non-negative matrix factorization algorithm (NMF) method. Cosine similarity and cross correlation were calculated for similarity comparison with healthy subjects. In both stroke patients, the similarity of leg muscle synergy during walking changed to similar to that of healthy subjects due to a decrease in foot drop during. FES walking intervention influenced the similarity of muscle synergies during walking of stroke patients. This intervention has an effective method on foot drop and improving the gait performance of stroke patients.
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