• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.7
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• pp.357-363
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• 2002

The target reliability values are defined for the train, signaling, rail track and electric power supply system of the LRT under development. The allocation of the reliability value is based on the failure rate and the failure type in the Korean subways. The reliability allocation in the train system is the made ore detail than others. The purpose of the allocation is to verify the reliability value of the results from each of the development stage, which could be the designing, manufacturing and purchasing work. The reliability of braking system, traction system, door system and other control system could be verified by establishing reliability models of these system. It could also enable us to estimate and analyse the reliability value and redo the work if necessary to achieve the shooting reliability value. A guide to the LRT reliability criteria is to be prepared after running test on the test track.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.645-649
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• 1997

In case of swash plate type axial piston hydraulic motor, hydrostatic bearing used to achieve the lubrication effect on the mechanical sliding contact areas between the following parirs ; sliooer-pad and swash plate,piston and cylinder bore,valve plate and cylinder block, etc. This study discussed the basic charateristic for the hydrostatic slipper-pad bearings with the capillary or orifice restrictor under static load condition. And, we also development of hydrostatic bearing tester for hydrostatic balancing test of pistion & slipper-pad assembly, and some experimental data on supply pressure step responce are reported.

• Proceedings of the KIEE Conference
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• 2001.07d
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• pp.2446-2448
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• 2001

In addition to the stabilization of electricity supply and the quality management of electricity, load balance has been an important strategy for achieving high quality load management. Among many techniques for load management, direct load management has been actively studied and applied for increasing the efficiency of power facility and suppressing peak load. In Korea, the highest peak load is demanded in summer rather than in winter, and almost 50% of the peak load comes from cooling load. Currently, applicable systems are limited to air conditioners that have the cooling capacity less than 2kW. This paper describes the development of remote controlled air conditioners and the result of the field test of the new type air conditioner. The technical specification based on the test will be applied to the new model of the remote controlled air conditioner. The wide distribution of the air conditioners to the public will be helpful to control peak demand due to cooling load in summer time. Financial investment to generating, transmission, distribution facilities will be decreased from flatting the seasonal power load.

• Proceedings of the KIEE Conference
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• summer
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• pp.1391-1393
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• 2004

This paper described the development of technology for LRT (Light Rail Transit) power system, which are sponsored by MOCT and supervised by KRRI. Especially, manufacture, interface between components and composition for DC Switchgear are focused. Most main components for DC switchgear(Protective Relay, HSCB, DS) are made by own. Also the type test report of international testing laboratory about the DC Switchgear based on IEC regulations is introduced. Finally the product will be proved based on field test.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.2
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• pp.179-184
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• 2010

The digital substation automation system has contributed hugely to increasing the stability of power systems by providing not only protection and control of power systems but diagnostic features alongside them. Digital substation automation systems in the scale of substations consist of integrated operation systems and intelligent electronic devices. The main intelligent electronic devices currently in use are digital protection relays and the bay controllers in Gas insulated switchgears. Proficiently accomplishing the coordination of protection within the power system as a means of ensuring reliability and contriving for the stability of power supply through connection of function, the application of bay controllers is crucial, which collectively manage the protection relay at the bay level in order to achieve both. In this research, the bay controllers to be used in high-voltage Gas insulated switchgear has been localized, and in particular, the logic function and editor required in order to minimize the complicated hardware-like cable connections in the local panel have been developed. In addition, to ensure the strength and reliability of the bay controller hardware developed herein, the type tests from KERI have been successfully completed.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.422-425
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• 2009

A sea water source cascade heat pump was designed and tested in this study. The system was designed to perform a single stage operation in summer, as well as a cascade operation in winter to ensure the high temperature lift. A steady-state simulation model was developed to analyze and optimize its performance. The simulation results show that the R717 exhibits best performance among combinations considered in this study. A R410A also exhibits the highest performance among HFCs with the smallest compressor displacement. A 15-RT R410A-R134a pilot system was installed in the 5-story commercial building at Samcheok City by the East Sea. A scroll type R410A compressor, a reciprocating type R134a compressor, plate type condenser/evaporator/ cascade heat exchanger and two electronic expansion valves were used to build a pilot. A titanium plate type heat exchanger is also used for the heat exchanging with a sea water. The heat source/sink water is supplied from the well below the seashore in the depth of 5 m. In the initial test of the system, supply water temperature was rising up to $67^{\circ}C$ using a sea water heat source of $9^{\circ}C$, while an ambient temperature was $4.5^{\circ}C$.

• The Journal of Korean Physical Therapy
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• v.28 no.2
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• pp.155-163
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• 2016

Purpose: Infection management is important for physical therapists in order to protect patients and themselves since they often provide patient care and have physical contact with patients. This study examined the performance of infection control and associated factors among physical therapists. Methods: The study subjects were 174 physical therapists working in the G metropolitan city. The performance of infection control according to general characteristics, job-related characteristics, and infection-related characteristics were compared using t-test and ANOVA. Associations between awareness and performance of infection control were tested by correlation. Finally, multiple linear regression analyses were performed to examine the factors associated with performance of infection control. Results: Overall performance scores for personal and therapy room were $87.47{\pm}11.70$ and $70.08{\pm}13.68$, respectively. Both personal and therapy room infection control were lower for the degree of performance than the degree of awareness. In multiple linear regression analysis, the degree of performance at a personal level was related to current smoking status, type of charge therapy, supply of protection equipment, and awareness of personal infection control. The degree of performance of therapy room was related to injury experience in the workplace, supply of protection equipment, and awareness of therapy room infection control. Conclusion: Performance of therapy room infection control was lower than that of personal infection control. The performance was associated with the supply of protection equipment and awareness. Therefore, the degree of performance for infection control will be increased with proper supply of protection equipment in the hospital and increase the degree of awareness with adequate prevention education.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.12
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• pp.8306-8313
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• 2015

Open-type current sensors have been commonly used for DC motor controller, AC variable controller and Uninterruptible Power Supply. Recently they have begun to be used more widely, as the growth of renewable energy and smart-grid in power system. Considering most of the open-type current sensors are imported, developing the core technology needed to produce open-type current sensors is required. This paper describes the development and test results of open-type current sensors. Design of C type magnetic core, selection and test of a Hall sensor, design of current source circuit and signal conditioning circuit are described. 100A class DIP(Dual In-line Package) type and SMD(Surface Mount Devide) type open-type current sensors was made and tested. Test results show that the developed open-type current sensor satisfies the accuracy requirement of 2% and linearity requirement of 2% at 100 A of DC and AC current of 60Hz. Temperature compensation was carried out by using a temperature compensation circuit with NTC(Negative Temperature Coefficient) thermistor and the effect of the temperature compensation are described.

• Journal of the Korean Geosynthetics Society
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• v.12 no.2
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• pp.1-11
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• 2013

Water content of subgrade soil in water supply systems has a large effect on performance. Many researchers lately make use of time-domain reflectometry (TDR) probes to measure the soil water content of subgrade soil from monitoring. The laboratory calibration test of TDR probe should be performed with soil field, because TDR probe can cause an error by type, gradation, density, and temperature of soil. This study shows the laboratory calibration test using TDR CS616, TDR-P3, TDR-T3. The calibration equations of TDR were then proposed. It was confirmed from the study that the data of TDR probe monitored in field could be used to estimate the freezing, unfrozen water content, and matric suction of soil.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.4
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• pp.151-159
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• 2015

In this study, we developed an automated contact-type thickness measurement machine that continuously and precisely measures the thickness of a PCB module product using multi-LVDT sensors. The system contains a measurement part to automatically measure the thickness in real time according to the set conditions with an alignment supply unit and unloading unit to separate OK and NG products. The sensors were calibrated before assembly in the measuring machine, and precision and accuracy performance tests were also performed to reduce uncertainty errors in the measurement machine. In the calibration test, the precision errors of the LVDT sensor were determined to be $1-3{\mu}m$ as 0.1% at the measuring range. A measurement error of 0.8 mm and 1.0 mm thickness test standards were found to be $1{\mu}m$ and $4{\mu}m$, and the standard deviations of two 1.0 mm products were measured as $14{\mu}m$ and $8{\mu}m$, respectively. In the measurement system analysis, the accuracies of test PCB standards were found to be $2{\mu}m$ and $3{\mu}m$, respectively. From the results of gage repeatability and reproducibility (R & R) crossed, we found that the machine is suitable for the measurement and process control in the mass production line as 7.92% of total gage R & R and in seven distinct categories. The maximum operating speed was limited at 13 pcs/min, showing a value good enough to measure.