• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2012.10a
• /
• pp.312-315
• /
• 2012

Generally, SAW device, which uses Time Domain Sampling, requires high speed AD converter because SAW device (TDS) needs high sampling speed as much as its high data speed. However, the high price of AD converter discourages makers from using it. On the other hand, SAW device, which uses Frequency Domain Sampling, does not required high speed AD converter because SAW device (FDS) does not need high sampling speed. It is very efficient in price comparison to its performance because high processing speed of SAW device (FDS) can be implemented using low price Embedded Systems. The purpose of the thesis is to solve the issues above by designing and realizing SAW device (FDS) using SAW sensor for TDS.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2009.06a
• /
• pp.152-152
• /
• 2009

We investigate micro-tip properties as Ni-Co plating and CMP processes for MEMS probe card and units. The micro-tip are fabricated by using Ni-Co plating machine, lapping machine, and chemo-mechanical polisher. In order to get high conductive and reliable micro-tip, we control Co contents and thickness by CMP speed. We have found that about 20-25% of Co contents are required and have to lapping speed of 30 rpm. Also, we investigate photolithography and Ni-Co plating processes conditions for the one-step and the three-step micro-tips.

• Human Ecology Research
• /
• v.55 no.1
• /
• pp.1-12
• /
• 2017

This study examines the relationship among children's smart device immersion tendency, children's self-regulation, and pro-social behavior as well as investigates the mediating effect of self-regulation between children's smart device immersion tendency and pro-social behavior. Participants were composed of 263 4-year-old children attending kindergarten in Incheon and Gyeonggi province. Data were analyzed by means of Pearson's correlation coefficients in SPSS, the structural equation model and bootstrapping in AMOS. The results are as follows. First, there is a statistically meaningful relationship among children's smart device immersion tendency, self-regulation, and pro-social behavior. There is a negative correlation between children's smart device immersion tendency and children's self-regulation as well as pro-social behavior; however, there is positive relationship between children's self-regulation and pro-social behavior. Second, children's smart device immersion tendency had a direct effect on children's self-regulation. In addition, children's self-regulation indicated a direct effect on children's pro-social behavior. Third, children's self-regulation was found sufficient to mediate the relationship between children's smart device immersion tendency and pro-social behavior. The results indicate that the effort to increase children's self-regulation may decrease the negative effect toward children's pro-social behavior caused by smart device immersion tendencies.

• Proceedings of the Korean Society for Agricultural Machinery Conference
• /
• 1997.12a
• /
• pp.255-262
• /
• 1997

A low-cost and precise metering device, which is suitable to automatic mixing of nutrient-solution for hydroponic culture, was developed for small-scale growers. The metering device was composed of three parts those were supply pumps, metering cylinders and venturi tube. Those parts were controlled by personal computer with time-based odoff control method. To verify the performance of the developed metering device, the relationship between operating time and discharge was examined and the accuracy of the developed metering device was compared with commercial metering pumps. The results of this study are as follows. 1. The correlation coefficient between the flow rate and operating time was 0.9999, and the linear regression equation computed was y=21.759x, where y is the discharge(g) and x is the operating time(s). 2. The developed device has greater accuracy than commercial metering pumps in terms of the full-scale error. Calculated errors for the developed metering device and two commercial pump were $\pm$0.3 %, $\pm$2.45 % and $\pm$1.38 % respectively. 3. Above results show developed metering device is a useful tool for nutrient-solution control system.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2003.06a
• /
• pp.1154-1157
• /
• 2003

The spent fuel slitting device is an equipment developed for the separation of the pellet and hull from the cutting fuel rod with length of 250 mm, and in order to feed UO$_2$ pellet. We have analyzed on the existing technologies for designing and producing of the slitting device in the first year(2001), based on these results, designed and produced the rod slitting device. It has effectively separated the pellet from the hull, but demanded the supplement separation work because of the mixing with pellet and hull in the vessel, and required the condition for the reducing time of the process. In the second year(2002), we have reduced the work time, performed the test and capacity evaluation with the improving device, based these results, and ensured the data demanded for designing of the spent fuel rod slitting device. We have compared with the DUPIC(Direct use of spent PWR fuel in CAND reactors) process, and developed the device for the purpose of reducing over 40 % in comparition with the DUPIC operation time(5 minutes). Based on these results, it will is effectively applied to available data for designing and producing of the hot test facility.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.65 no.6
• /
• pp.1103-1107
• /
• 2016

The automatic tensioning device of the catenary system constantly maintains the tension of the trolley wire by absorbing the variations due to the elasticity of the line caused by temperature variation. The tension plays an important role in affecting the electric motorcar operation directly. This paper suggests the methodology of the life cycle extension and the maintenance of the automatic tensioning device by means of performance diagnosis of the pulley type automatic tensioning device which has been commonly used for the electric railway system. Through conducting performance diagnosis and comparative test for the wornout pulley type automatic tensioning device by replacing the components such as the bearing and the bearing shaft without replacing all the assembly, the tensioning device is analyzed whether it is properly functioned. Provided that the maintenance regulation is reinforced so as to implement the bearing replacement through periodical precise inspection along with random check-up inspection which is now carried out by the operating organizations, it is ensured that the life cycle extension and the reduction of maintenance cost of the tensioning device could be achieved.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2012.02a
• /
• pp.386-386
• /
• 2012

We studied a bilateral switching device for spin transfer torque (STT-MRAM) based on 3D device simulation. Metal/P/N+or Metal/N/P+ junction device with $30{\times}30nm2$ area which is composed of one side schottky junction at Metal/P/N+ and Metal/N/P+ provides sufficient bidirectional current flow to write data by a drain induced barrier lowering (DIBL). In this work, Junction device confirmed that write current is more than 30 uA at 2 V, It is also has high on-off ratio over 105 under read operation. Junction device has good process feasibility because metal material of junction device could have been replaced by bottom layer of MTJ. Therefore, additional process to fabricate two outer terminals is not need. so, it provides simple fabrication procedures. it is expected that Metal/P/N+ or Metal/N/P+ structure with one side schottky junction will be a promising switch device for beyond 30 nm STT-MRAM.

• Journal of rehabilitation welfare engineering & assistive technology
• /
• v.11 no.4
• /
• pp.299-306
• /
• 2017

The Korean medical device industry has increased dramatically due to various investments in the domestic medical device industry and the introduction of new technologies, but the domestic medical device usage rate in great hospital is still low. In this paper, improvement point for domestic medical device was suggested by domestic medical device usage rate and user and manager's perception survey in great hospitals in Korea. To do this, a survey on the types of medical devices and domestic medical device usage rates were conducted at four national university hospitals in Korea. From this results, the priority survey medical devices were selected. Improvements of Korean medical devices were suggested by failure mode analysis and user awareness surveys for the priority survey medical devices.

• Human Ecology Research
• /
• v.59 no.2
• /
• pp.157-168
• /
• 2021

The purpose of this study was to examine the pathways between mothers' inappropriate smart device usage habits, preschoolers' immersion tendency and self-regulation, and children's cognitive ability. The subjects of the study were 308 preschoolers aged 4 and 5 years and their mothers in Seoul, Gyeonggi-do, Incheon, Gangwon-do, Daejeon, Busan, and Mokpo. Data were analyzed with descriptive statistics, t-test, one-way ANOVA, and Pearson correlation using the SPSS 25 program. A sequential mediation model was analyzed using the AMOS 22 program. Mothers' inappropriate smart device usage habits were found to have a negative effect on the preschoolers' self-regulation, and this association was mediated by the preschoolers' smart device immersion tendency. These findings show the mechanisms through which mothers' inappropriate smart device usage habits negatively affect preschoolers' smart device immersion and self-regulation which, in turn, has a negative impact on cognitive ability

• Journal of Biosystems Engineering
• /
• v.41 no.1
• /
• pp.21-33
• /
• 2016

Purpose: In order to ensure that vegetable seedlings (with a soil block around their roots) are planted in an upright orientation after metering in a vegetable transplanter, they need to be dropped freely from a certain height. The walk-behind hand-tractor-powered machines do not have sufficient space to drop the seedlings from that height. In the present work, a hopper-type planting device was developed for the walk-behind hand-tractor-powered vegetable transplanter to ensure that the soil block seedlings are planted in an upright orientation. Methods: Various dimensionless terms were developed based on the dimensional analysis approach, and their effect on the planting of soil block seedlings in an upright orientation (planting efficiency) was studied. The optimum design dimensions of the hopper-type planting device were identified by the Taguchi method of optimization. Results: The ratio of the height of free fall to the sliding distance of the seedling on the surface of the hopper had the highest influence on planting efficiency. The planting efficiency was highest for plants with a height $15{\pm}2cm$. The plant handling Froude number, in interaction with the design of the hopper-type planting device, also significantly affected the planting efficiency. Of the hopper design factors, the length of the slide of the seedlings on the surface of the hopper was most important, and induced sufficient velocity and rotation to cause the seedling to fall in an upright orientation. An evaluation of the performance of the planting device under actual field conditions revealed that the planting efficiency of the developed planting device was more than 97.5%. Conclusions: As the seedlings were fed to the metering device manually, an increase in planting rate increased missed plantings. The planting device can be adopted for any vegetable transplanter in which the seedlings are allowed to drop freely from the metering device.