• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.13 no.2
• /
• pp.196-208
• /
• 2002

Since radio interference has occurred in the TRS frequency band in the south coastal area, Korea from 1994, similar interference has been observed in the mobile-cellular frequency band. Measurement showed that the sources of the radio interference are those from the base stations for digital cellular systems in Japan. This because the receiving frequency of the base stations in Korea is same as the transmitting frequency of the base stations in Japan. Since the distance between Korea and Japan is 240 ~ 300 km, we can conclude that the main reason of the interference is ducting. In this paper a ducting channel is modeled by split-step DMFT algorithm, and simulation results for measured index profile far east coast and west sea area are analyzed.

• Transactions on Electrical and Electronic Materials
• /
• v.12 no.4
• /
• pp.152-155
• /
• 2011

This paper presents a comparative analysis on step and the touch voltages generated by either a sine and a ring wave voltage generator; this analysis was done as a basic study in order to develop a small and lightweight ground meter. A ring wave generator using pulsed power technology was fabricated; an experimental grounding system specified in Institute of Electrical and Electronics Engineers standards 80 and 81 was installed. The step and the touch voltages, which were measured using comparable a sine and a ring waves in terms of magnitude and frequency, were equal. Using pulsed power technology, the weight of the fabricated ring wave generator could be reduced to one-fifth of that of a sine wave generator. Consequently, if a ground meter adopts the ring wave instead of a sine wave, it will be possible to reduce the weight of a ground meter and improve the efficiency of measurement.

• Physical Therapy Rehabilitation Science
• /
• v.9 no.4
• /
• pp.222-229
• /
• 2020

Objective: The purpose of this study was to investigate the effect of treadmill exercise on the posture and walking speed of chronic stroke survivors with an ankle-foot orthosis. Design: Randomized controlled trial. Methods: Twenty-four chronic persons with chronic stroke admitted to Bobath Memorial Hospital in Seongnam city were divided into two groups by random blind method. Treadmill exercise with an elastic ankle-foot orthosis was performed in the experimental group and treadmill exercise was performed in the control group. The experiment was carried out for 6 weeks, and the experiment was carried out three times a week for 20 minutes per session. To measure the effect, static balance was measured using the MTD system before and after training, and the Berg Balance Scale (BBS) was used to measure functional balance. Results: There was a statistically significant difference between the 2 groups in the BBS measurement results for confirming the functional balance (p<0.05). Also, there was a significant difference between the 2 groups in single limb support time, step time and step length (p<0.05). Conclusions: In this study, it was found that treadmill exercise with an elastic ankle-foot orthosis in persons with chronic stroke was effective in maintaining functional balance, walking ability, step length, and step time. Therefore, it is necessary to use a flexible ankle-foot orthosis with proper treadmill exercise as a method of improving balance and walking speed of chronic stroke survivors.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.14 no.6
• /
• pp.88-94
• /
• 2005

A swirl ratio of a charge in the cylinder could be calculated by measuring both the rotary speed of paddle and the intake air flow rate in the swirl measurement apparatus fur several positions of valve lift. The automation of the swirl ratio measurement for a cylinder head is achieved by controlling both the valve lift of cylinder head and a suction pressure of the surge tank, instead of controlling them manually. PID control of the surge tank pressure and positioning a valve lift of the cylinder head are also achieved by using two step motors, respectively. Rotating speed of a paddle are measured using an optical sensor and a counter. Flow rate are measured from ISA 1932 flow nozzle by reading a differential pressure gauge position using IEEE-1394 camera. Time to measure the swirl ratio for a port in the cylinder head is drastically reduced from an hour to 3 minutes by automation control of the apparatus.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.10 no.4
• /
• pp.872-876
• /
• 2009

The government has funded various types of projects to promote small and medium companies' computerization for several years. Most of these government-supported funds have been free and given small and medium firms good opportunities. The government has made various effects to manage results of these government-supported projects. We have not seen any noticeable research on the performance evaluation of government-supported projects for small and medium companies' computerization. This research proposes an approach that performance evaluations are made in different time based on evaluation area of government-supported information policy. The empirical study has been made by correlation analysis and has shown that the correlations among measurement factors are significant enough. The performance evaluation for government-supported information policy has been made differently in time depending on evaluation subjects such as organizational strategies, internal operations, supporting processes. Th experimental study shows that performance evaluations on organizational strategies, internal operations, supporting processes should be made respectively in long term(step3), mid term(step2), and short term(step1).

• Journal of the Korean housing association
• /
• v.23 no.6
• /
• pp.1-9
• /
• 2012

This study is to organize the frame of measuring inventory for housing quality related to mental health in foreign literature reviews. In the first step, many housing quality contents or items are extracted from empirical studies, including housing environment quality and mental health. In the next step, extracted contents and items are classified by space scope (house and neighborhood unit) and WHO housing properties (safety & security, health & sanitation, efficiency/convenience, comfort/amenity). Almost all housing properties follow the WHO standard, but some properties, sustainability and economic characteristics, do not follow the standard. These reflect on current Korean housing environment. They are energy saving and environment friendly effort, property value and economic burden, identity expression, and school district. So they need to be added to the Korean housing quality measurement related to mental health.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.33 no.4
• /
• pp.193-200
• /
• 2010

In this study, we took the census of the project satisfaction level of the employees who have participated in Six Sigma projects. We divided and measured the project satisfaction by the steps of performing the project (team building, execution, ownership and support step). We performed the analysis of variance to show the main factors of project satisfaction level, and the tests of homogeneity to know the relationship the business parts and among the job positions each. The results of analysis showed that the satisfactions of the team building and execution step were significant.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1996.04a
• /
• pp.264-270
• /
• 1996

In this paper, a computer automated system has been developed for measuring the focal length of camera lens using the MTF(Modurar Transfer Function) based on the signal processing around a line CCD and autocollimator. An optical Path for the focal length measurement system has been designed around thelight sourec, collimator, camera, mirror and the line CCD. The eyepiece of the collimator is replaced byline CCD, and the mirror is moved along the focal axis by a PC driven step motor. An efficient method has been designed for finding the optimum MTF value for the focal length based on the least squares approach. The developed system is fullycomputer automated: signal transmission to and from the camera, MTF evaluation based on the line CCD, step motor contorl, etc. The developed system has been applied to a practical camera manufacturing process and demonstrated its performance

• Journal of the Optical Society of Korea
• /
• v.18 no.1
• /
• pp.37-44
• /
• 2014

The use of a laser interferometer as a metrological tool in micro-optics measurement is demonstrated. A transmissive interferometer is effective in measuring an optical specimen having a high angle slope. A configuration that consists of an optical resolution of 0.62 micron is adapted to measure a specimen, which is a micro-Fresnel lens-shaped lenticular lens. The measurement result shows a good repeatability at each fraction of facets, however, a reconstruction of the lens shape profile is disturbed by a known problem of $2{\pi}$-ambiguity. To solve this $2{\pi}$-ambiguity problem, we propose a two-step phase unwrapping method. In the first step, an unwrapped phase map is obtained by using a conventional unwrapping method. Then, a proposed unwrapping method based on the shape modeling is applied to correct the wrongly unwrapped phase. A measured height of each facet is compared with a profile result measured by AFM.

• Korean Journal of Materials Research
• /
• v.10 no.7
• /
• pp.493-498
• /
• 2000

The effects of RRA treatment on the microstructures and mechanical properties of 7050 Al alloy were investigated by differential scanning calolimetry, transmission electron microscopy, microhardness measurement and electrical conductivity. The hardness of 2nd-step aged specimen at $175^{\circ}C$ was decreased to mimimum value and increased to a peak hardness, and then re-decreased with retrogression treatment. It was found that the hardness of 2nd-step aged specimen was further increased by 3rd step aging treatment($120^{\circ}C$x24h). The initial decrease in hardness during 2nd-step aging was due to the partial dissolution of pre-existing GP zone, the major precipitation hardening phase at T6 condition. It was confirmed that the major precipitation hardening phase at 3rd-step aging was GP zone and η' phase. The electrical conductivity increased continually through 2nd-step and 3rd-step aging treatment. It was conclude that the optium 2nd-step aging condition was at $175^{\circ}C$ for 50min by considering the hardness and electrical conductivity.