• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.31-33
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• 2000

This paper discusses the operational characteristic analysis of distance relay depending on the power system parameters in transmission line including FACTS devices. Distance relay requires protective coordination because the FACTS devices change power system parameters to increase power transmission capacity. In this paper, the dynamic operational characteristics of distance relay are analyed for the effect of fault resistance and operation mode of FACTS devices according to the installed points of these devices.

• Journal of Digital Convergence
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• v.19 no.1
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• pp.11-22
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• 2021

The COVID-19 pandemic has led to distance learning in primary and secondary school. Little has been known whether home ICTs environment is appropriate for the distance learning. This paper aims to assess the current state of ICTs environment at home for the distance learning of children. Using 2012 and 2019 Korean Media Panel Survey, we investigated the number of smart devices owned by households and found differences in ownership by household characteristics. The results showed that the majority of household owned more than one smart devices per child. However, the difference in the proportion of households with less than one device per child varied depending on whether smartphone was included in smart devices. These results imply that public intervention is needed to prevent educational inequality caused by the home ICTs environment for the distance learning.

• Journal of the Korean Society of Safety
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• v.25 no.6
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• pp.40-46
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• 2010

To protect press operator from the after-reach hazard, current Ministry of Labor Notification(MOLN) requires the use of a formula for calculating the safe distance away from the point of operation for locating press protective devices, Two Hand Control Devices(THCD) and Active Opto-Electronic Protective Devices(AOPD), on a power press. This formula is based on a same hand speed constant of 160cm/s. While EN standards use different hand speed constant for THCD and AOPD respectively. The objective of this study is to compare two guidelines on the hand speed constant published by MOLN and EN 692, also to propose a proper hand speed constant and validate it experimentally. As a experimental result, it could be known that hand speed constant of Ministry of Labor Notification should be improved as that of EN standards.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.1006-1008
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• 2003

Position controls are very important in semiconductor manufacturing devices, machine tools precision measuring instruments, etc. to measure the distance of movement of moving objects in minute units and the accuracy of measurement for the moving distance in these devices affect the performance of the whole devices. Therefore, in those precision instruments, a sensing device that can measure the distance of movement with high-precision resolution is required. In this paper, a novel encoder of digital and analog hybrid type is proposed. It is shown that from this experiment a high-resolution angle measurement device can be designed by a low cost incremental encoder.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.18 no.2
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• pp.95-102
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• 2012

Background: The purpose of this study was to find out influence of using portable mobile devices in human body. Method: The subjects were consisted of the normal persons (19 males and 20 females). These subjects were consisted of three groups according to test time. The A group (12 persons - 6 males, 6 females) tests 5 minutes, the B group (14 persons - 7 males, 7 females) tests 10 minutes, and the C group (13 persons - 6 males, 7 females) tests 15 minutes. Before test, sight, quickness and balance were measured, after test revision, quickness, balance were measured and checked pain scale. Results: The results were as follows. 1. Sight, quickness and balance were decreased and pains were increased after using portable mobile devices than before using these. 2. According to duration of using the portable mobile devices, sight, quickness and balance was not a statistically significant difference, the entire upper body pain was a statistically significant difference. When viewed as part of the pain, shoulder, lower back, and wrist pain were a statistically significant difference, but the neck and elbow were not a statistically significant difference. 3. The influence of vision according to distance of using Portable mobile devices was no statistically significant difference. In addition, less than 20cm distance using equipment group ("Ga") and the group ("Na") which exceeded 20cm in between the sight were not statistically significant difference, Influence of pain according to distance of using Portable mobile devices we-re no statistically significant differences. Conclusion: Using portable mobile devices affect human body on the elements of the biomechanics.

• Journal of the Korean Society of Safety
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• v.18 no.2
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• pp.22-27
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• 2003

The roller machines installed in the industrial field are operated under hazardous conditions due to no safety devices available, human error during operation, defective safety devices, and inadequate regulation even in case that safety devices are provided. Up to now, most roller machines installed in domestic field are provides with band breaking system as a safety device. In this study, the emergency stop distance is measured within the limit of domestic regulation but violates a foreign regulation(EN1417). Consequently, it is concluded that the roller machines with a band breaking system have high possibility of death or serious injury of the operator and the system should be improved with the introduction of additional safety devices. This thesis suggests the safety measures suitable for the roller machines with different drive systems based on the experiment results. The use of the newly developed safety system has been tested on many cases.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.2
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• pp.79-83
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• 2016

This research was analyzed thermal characteristics that was appointed disadvantage when smart LED driver ICs was packaged and we applied extracted thermal characteristics for optimal layout design. We confirmed reliability of smart LED driver ICs package without additional heat sink. If the package is not heat sink, we are possible to minimize package. For extracting thermal loss due to overshoot current, we increased driver current by two and three times. As a result of experiment, we obtained 22 mW and 49.5 mW thermal loss. And we obtained optimal data of 350 mA driver current. It is important to distance between power MOSFET and driver ICs. If thhe distance was increased, the temperature of package was decreased. And so we obtained optimal data of 3.7 mm distance between power MOSFET and driver ICs. Finally, we fabricated real package and we analyzed the electrical characteristics. We obtained constant 35 V output voltage and 80% efficiency.

• IE interfaces
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• v.20 no.4
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• pp.539-546
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• 2007

This study has been conducted on touch screen interface design for mobile devices. It was intended to measure user’s satisfaction on one-handed thumb input mobile devices. Recent studies proposed the optimal touch button size, but it is inappropriate for mobile devices. Therefore, this study was focused on four touch key factors-width, height, the horizontal and vertical distance between touch keys-as independent variables. The ANOVA results showed that the user satisfaction of four touch key factors was significantly affected by the thumb input. It also apparent that the interactions between four factors were significant. As a result, the horizontal and vertical distance as well as the width and height affected the satisfaction of users. In addition, this study suggested satisfaction models which represent the top 30%, 50%, 70% of user satisfaction measurement. The results of this study could be used to design touch keys that are able to enhance the usability on touch screen based mobile devices.

• Journal of the Korea Convergence Society
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• v.8 no.8
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• pp.27-32
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• 2017

The several wearable devices are not able to communicate through cable due to its portability. The wireless communication method is used because of its good communication quality and group action features when the several wearable devices communicate with each other. In this paper, we proposed the group decision algorithm for grouping display of the several wearable devices. It means that recognize as a group member after measuring distance in the wireless communication environment. The result of experience showed that the group-type display of several wearable devices method overcome the limit of the display of single wearable device.

• The Transactions of the Korean Institute of Power Electronics
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• v.8 no.6
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• pp.512-518
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• 2003

Position controls are very important in semiconductor manufacturing devices, machine tools Precision measuring instruments, etc. To measure the distance of movement of moving objects in minute units and the accuracy of measurement for the moving distance in these devices affect the performance of the whole devices. Therefore, in those Precision instruments, a sensing device that can measure the distance of movement with high-precision resolution is required. In this paper, a novel encoder of digital and analog hybrid type is proposed. It is shown that from this experiment a high-resolution angle measurement device can be designed by a low cost incremental encoder.