• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.5
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• pp.111-116
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• 2022

The causes of motor burnout include overload, phase loss, restraint, interlayer short circuit, winding ground fault, instantaneous overvoltage, and the rotor contacting the stator, leading to insulation breakdown, leading to breakdown or electrical accidents. Therefore, equipment failure causes not only loss due to cost required for equipment maintenance/repair, but also huge economic loss due to productivity decrease due to process stop because the process itself including the motor is stopped. The current level of technology for diagnosing motor failures uses vibration, heat, and power analysis methods, but there is a limit to analyzing the problems only after a considerable amount of time has passed according to the failure. Therefore, in this paper, a device and algorithm for measuring insulation resistance using DC AMP signal was applied to an industrial motor to solve this problem. And by following the insulation resistance state value, we propose a diagnosis of deterioration and failure of the motor that cannot be solved by the existing method.

• The Journal of Korean Academic Society of Nursing Education
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• v.27 no.2
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• pp.197-209
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• 2021

Purpose: The purpose of this study is to evaluate the validity and reliability of the Korean Bereavement Care Confidence Scale (K-BCCS). Methods: The Perinatal Bereavement Care Confidence Scale (PBCCS) was translated into Korean according to an algorithm of cultural adaptation process and excluded six items which were specific to perinatal bereavement. A total of 229 clinical nurses participated in the study. Construct validity, convergent validity, discriminant validity, and group comparison validity were evaluated, and Cronbach's α was calculated to estimate the reliability of the K-BCCS. Results: The K-BCCS consisted of 31 items in 7 factors, including knowledge and skills for bereavement care (12 items), organizational support (6 items), awareness of the needs (3 items), interpersonal skills (3 items), workload influence (2 items), continuous education (2 items), and understanding the grief process (3 items). The factor loading of 31 items within the 7 factors ranged from .60 to .86. For the convergent validity, the construct reliability (CR) ranged from .74 to .94, and the average variance extracted (AVE) ranged from .49 to .73, which is considered acceptable. The discriminant validity showed that the AVEs of the subscales were greater than the square of the correlation coefficient r. The nurses who had experience providing bereavement care (t=4.94, p<.001) or had received bereavement education (t=6.64, p<.001) showed higher K-BCCS values those without experience. The Cronbach's α of 31 items was .93 and ranged from .60 to .94 per subscale. Conclusion: The K-BCCS is a valid and reliable tool for evaluating nurses' confidence in bereavement care.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.1
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• pp.123-129
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• 2023

In this paper, the frequency synthesis(FS) MMIC and the receive MMICs were developed for a Ka-band compact radar. Also a compact Ka-band frequency synthesizer and a receiver were developed based on those MMICs. The FS MMIC and the wireless-receiver(WR) MMIC to receive the baseband frequency were manufactured by a 65 nm CMOS process and the front-end(FE) MMIC to receive the Ka-band frequency was manufactured by a 150 nm GaN process. Linear frequency modulation waveform and pulse waveform for the transmit signal were measured by output signal of frequency synthesizer. The measured performance of developed receiver including the FE MMICs and the WR MMIC were ≧ 80 dB gain, ≦ 6 dB noise figure and ≧ 10 dBm at OP1dB. The measurement results of the developed frequency synthesizer and the receiver including the manufactured MMICs showed that they could be applied to Ka-band compact radar.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.11
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• pp.36-42
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• 2021

This study was conducted to analyze the effect of the gear specification and gear quality corresponding to the macro geometry on the gear transmission error. The two pairs of gears with large and small transmission errors were selected for calculation, and two pairs of gears were manufactured with different gear quality. The test gears were manufactured by two different gear specifications with ISO 5 and 8 gear quality, respectively. The transmission error measurement system consists of an input motor, reducer, encoders, gearbox, torque meter, and powder brake. To confirm the repeatability of the test results, repeatability was confirmed by performing three repetitions under all conditions, and the average value was used to compare the transmission error results. The transmission errors of the gears were analyzed and compared with the test results. When the gear quality was high, the transmission error was generally low depending on the load, and the load at which the decreasing transmission error phenomenon was completed was also lower. Even when the design transmission error according to the gear specification was different, the difference of the minimum transmission error was not large. The transmission error at the load larger than the minimum transmission error load increased to a slope similar to the slope of the analysis result.

• Fashion & Textile Research Journal
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• v.24 no.1
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• pp.146-155
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• 2022

We proposed a simple process of creating electroconductive textiles by using PEDOT:PSS(Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate))/non-oxidized graphene to coat polyamide or polyurethane knitted fabric for smart healthcare purposes. Electroconductive textiles were obtained through a coating process that used different amounts of PEDOT:PSS/non-oxidized graphene solutions on polyamide/polyurethane knitted fabric. Subsequently, the surface, electrical, chemical, weight change, and elongation properties were evaluated according to the ratio of PEDOT:PSS/non-oxidized graphene composite(1.3 wt%:1.0 wt%; 1.3 wt%:0.6 wt%; 1.3 wt%:0.3 wt%) and the number of applications(once, twice, or thrice). The specimens' surface morphology was observed by FE-SEM. Further, their chemical structures were characterized using FTIR and Raman spectroscopy. The electrical properties measurement (sheet resistance) of the specimens, which was conducted by four-point contacts, shows the increase in conductivity with non-oxidized graphene and the number of applications in the composite system. Moreover, a test of the fabrics' mechanical properties shows that PEDOT:PSS/non-oxidized graphene-treated fabrics exhibited less elongation and better ability to recover their original length than untreated samples. Furthermore, the PEDOT:PSS/non-oxidized graphene polyamide/polyurethane knitted fabric was tested by performing tensile operations 1,000 times with a tensile strength of 20%; Consequently, sensors maintained a constant resistance without noticeable damage. This indicates that PEDOT:PSS/non-oxidized graphene strain sensors have sufficient durability and conductivity to be used as smart wearable devices.

• Tribology and Lubricants
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• v.38 no.4
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• pp.170-178
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• 2022

Mechanical surface treatment is an excellent approach widely used to modulate and improve the performance and service life of bearings, gears, and frictional joints. The main purpose of this study is to investigate and compare the effect of ultrasonic nanocrystal surface modification (UNSM) and wonder process craft (WPC) on the surface and tribological properties of SUJ2 bearing steel. The surface roughness and hardness of the untreated and treated (UNSM- and WPC-treated) specimens were measured and compared. Their tribological properties were evaluated using a micro-tribometer under grease-lubricated and dry conditions against itself. Surface hardness measurement results revealed that both the UNSM- and WPC-treated specimens had a higher hardness than that of the untreated specimen. The surface roughness of the untreated specimen was reduced after UNSM and WPC treatments. Abrasive wear mode was observed on the surface of the specimens worn under grease-lubricated conditions, while adhesive wear mode was found on the surface of the specimens worn in dry conditions. According to the tribological test results, the friction coefficient and wear rate of the untreated specimens were reduced by the application of both the UNSM and WPC treatments under grease-lubricated and dry conditions.

• Korean Journal of Materials Research
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• v.32 no.9
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• pp.391-395
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• 2022

Research is being actively conducted on the continuous thin plate casting method, which is used to manufacture magnesium alloy plate for plastic processing. This study applied a heat transfer solidification analysis method to the melt drag process. The heat transfer coefficient between the molten magnesium alloy metal and the roll in the thin plate manufacturing process using the melt drag method has not been clearly established until now, and the results were used to determine the temperature change. The estimated heat transfer coefficient for a roll speed of 30 m/min was 1.33 × 10⁵ W/m²·K, which was very large compared to the heat transfer coefficient used in the solidification analysis of general aluminum castings. The heat transfer coefficient between the molten metal and the roll estimated in the range of the roll speed of 5 to 90 m/min was 1.42 × 10⁵ to 8.95 × 10⁴ W/m²·K. The cooling rate was calculated using a method based on the results of deriving the temperature change of the molten metal and the roll, using the estimated heat transfer coefficient. The DAS was estimated from the relationship between the cooling rate and DAS, and compared with the experimental value. When the magnesium alloy is manufactured by the melt drag method, the cooling rate of the thin plate is in the range of about 1.4 × 10³ to 1.0 × 10⁴ K/s.

• Journal of the Korean Society of Clothing and Textiles
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• v.45 no.6
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• pp.1052-1062
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• 2021

This study aims to confirm the possibility of Ultra-Violet (UV)-printed 3D printing materials using thermal polyurethane (TPU) with CMYK colors by applying an eco-friendly UV digital printing process. A UV-printed 3D printing TPU material was prepared with cycles of UV printing and CMYK colors. Dyeability of the 3D TPU samples with cycles of UV printing and CMYK were analyzed for thickness, weight, surface roughness, reflectance, colorimetry, and K/S values. The thickness and weight of 3D-printed TPU samples with cycles of UV printing are increased with overprints from 1 to 5. The surface roughness of 3D-printed TPU samples with increasing UV prints were decreased, meaning that the surface of TPU samples becomes gradually smoother. The reflectance spectra of CMYK UV-printed TPU samples showed the surface reflectance within each characteristic wavelength of CMYK. The 3D-printed TPU samples, subjected to UV printing twice or more, showed low surface reflectance. After examining the L^*a^*b^* of the 3D-printed TPU samples by the cycles of UV printing, the study found that the more UV got printed more than 2 times, the closer the color to each CMYK.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.4
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• pp.1-13
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• 2022

Household refrigerator cabinets must undergo cyclic testing at -20 ℃ and 65 ℃ for quality control (QC) after their production is complete. These cabinets were assembled from different materials, including acrylonitrile butadiene styrene (ABS), polyurethane (PU) foam, and steel plates. However, different thermal expansion values could be observed owing to differences in the mechanical properties of the materials. In this study, a technique to predict delamination on a refrigerator wall caused by thermal deformation was developed. The mechanical properties of ABS and PU foams were tested, theload factors causing delamination were analyzed, delamination was observed using a high-speed camera, and comparison and verification in terms of stress and strain were performed using a finite element model (FEM). The results indicated that the delamination phenomenon of a refrigerator wall can be defined in two cases. A method for predicting and evaluating delamination was established and applied in an actual refrigerator. To determine the effect of temperature changes on the refrigerator, strain measurements were performed at the weak point and the stress was calculated. The results showed that the proposed FEM prediction technique can be used as a basis for virtual testing to replace future QC testing, thus saving time and cost.

• Journal of Wellness
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• v.7 no.2
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• pp.113-121
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• 2012

This study chose the academic journals related with e-sports for analysis among the top tier journals of National Research Foundation of Korea from 2006 to 2011 to check the academic trend Beginning in 2006, the first study of e-sports was published in the journal related with e-sports. So, the studies from 2006 to 2011 were chosen for analysis. Using Research Information Sharing Service(RISS), the keyword 'e-sports' was searched. By virtue of this process, total 27 studies were selected as final analysis. So, the academic trends are as follows. In Korea, the studies related with e-sports have started from the beginning of 2000s with internet and then it spread out via cable TV. And then from the middle of 2000s, e-sports was discussed seriously. The early subject of the studies usually focused on the measurement of e-sports based on the strategic elements as a product. After that, game addiction and violent tendency which were one of the biggest issues were raised as a constant problem and it became the academic studies of user behavior. E-sports became a recreation culture of teenagers so it has been in charge of the role of exit and the problems related with it have continuously appeared. So, the academic studies tend to have departmentalization like immersion, addiction, sociality, self-regulation and etc. But, there was a tendency that the similar contents were repeated in the view point of subject and method while the subjects were departmentalized. So, for the systematic study of e-sports, development of the unique subject, study method and verification process should be conducted continuously.