• Proceedings of the Korean Geotechical Society Conference
• /
• 2002.10a
• /
• pp.629-634
• /
• 2002

Demands for the automatic measurement on angle and depth of equipment were arisen for the better construction in deep mixing method and grouting method. Civil, geotechnical, electronic, and communication experts worked together for the development of automatic measuring devices using wire and wireless transmitting-receiving set. The results on the development of automatic devices in an industrial installation will be presented.

• International Journal of Contents
• /
• v.15 no.3
• /
• pp.39-46
• /
• 2019

This study aimed to develop a peer-assisted learning (PAL) program for use in a core nursing skills education course and to investigate the effects of the education program on three key outcomes. A comparative study was conducted through the division of students of a core nursing skills education program into a treatment group and control group. After the programs, self-efficacy, confidence and satisfaction were compared between the groups. The comparison of these three factors indicated that the related scores were significantly higher in the treatment group receiving the education program with the PAL method than those of the control group receiving traditional education. We concluded that self-efficacy gave the nursing students the confidence that they could successfully perform their tasks and motivation to learn. Education programs using the PAL method are suggested as an effective method for the acquisition of skills among nursing students.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.34 no.3
• /
• pp.211-219
• /
• 2014

Closed cracks are difficult to detect using conventional ultrasonic testing because most incident ultrasound passes completely through these cracks. Nonlinear ultrasound inspection using sub-harmonic frequencies a promising method for detecting closed cracks. To implement this method, a sub-harmonic phased array (PA) is proposed to visualize the length of closed cracks in solids. A sub-harmonic PA generally consists of a single transmitter and an array receiver, which detects sub-harmonic waves generated from closed cracks. The PA images are obtained using the total focusing method (TFM), which (with a transmitter and receiving array) employs a full matrix in the observation region to achieve fine image resolution. In particular, the receiving signals are measured using a laser Doppler vibrometer (LDV) to collect PA images for both fundamental and sub-harmonic frequencies. Oblique incidence, which is used to boost sub-harmonic generation, inevitably produces various surface waves that contaminate the signals measured in the receiving transducer. Surface wave interference often degrades PA images severely, and it becomes difficult to read the closed crack's position from the images. Various methods to prevent or eliminate this interference are possible. In particular, enhancing images with signal processing could be a highly cost-effective method. Because periodic patterns distributed in a PA image are the most frequent interference induced by surface waves, spatial frequency filtering is applicable for removing these waves. Experiments clearly demonstrate that the spatial frequency filter improves PA images.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.29 no.8
• /
• pp.599-607
• /
• 2018

This paper presents a ground-to-air bistatic radar system and its implementation algorithm, which resembles an SAR(synthetic aperture radar) reconstruction algorithm. Via cooperative working between a standoff transmitting radar and an array of ground based receiving radars, it detects and images moving targets under clutter in the air. In the proposed system, the whole receiving antenna aperture is synthesized by physical ground based radars, and thus, unlike conventional SAR, it does not require long illumination time of the target area. The reconstruction algorithm uses planewave approximation based polar format processing, which alleviates the requirement of positioning the receiving radars, which can cause grating lobes if not chosen properly. We derive a reconstruction algorithm including clutter suppression and discuss implementation issues, such as the resolution of a reconstructed image and the method of compensation for the irregularity of the receiving radars' positions. A simulation that validates the proposed algorithm is also shown.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.23 no.3
• /
• pp.274-281
• /
• 2013

Field measurement method of heavy/soft impact sound pressure level which is regulated in JIS and ISO has been using in Korea, Japan and Canada. It is reported that heavy/soft impact sound pressure level was varied by the sound field condition of receiving room such as sound absorption power and room volume. In this study, it is checked that heavy/soft impact sound pressure level was affected by the receiving sound field condition. Rubber ball and bang machine sound pressure level was measured in the vertically connected reverberation chamber. In oder to check the effect of receiving sound field on heavy/soft impact sound pressure, sound absorption power was changed with polyester sound absorption blankets with air space and glass wool. The reverberation time at 1 kHz band was changed from 10 s to 0.2 s by sound absorption material. Rubber ball sound pressure level measured without sound absorption material was 58 dB in $L_{i,Fmax,AW}$, but the level was 46 dB with sound absorption treatment. From this result, it is confirmed that sound field correction method is needed in the heavy/soft impact sound pressure level measurement method using bang machine and rubber ball.

• Journal of Advanced Navigation Technology
• /
• v.16 no.6
• /
• pp.935-943
• /
• 2012

In this paper a three step procedure was derived to select the GNSS network receiving site candidates for GNSS based infrastructure technology development and according to the proposed procedure the 4 site candidates was selected for final network configuration. In the first step, the site requirement was produced for GNSS based infrastructure technology development referring regulation of the international organizations related to permanent GNSS data receiving and the first candidates were selected using the proposed requirement. In the second step, the second candidates were selected among the first candidates by analyzing the visual measurement, environment test and so on. In the third step the final candidates were selected among the second candidates by analyzing sky clearance, radio frequency interference. Through above the three step procedure 16,7,4 candidates of site were selected sequentially and receiving station site could be effectively selected.

• Journal of architectural history
• /
• v.22 no.4
• /
• pp.35-44
• /
• 2013

This paper looked into the structure of and changes in the building process of Gijang mountain fortress and its receiving reservoir by analyzing data from an excavation investigation. The structure of the receiving reservoir may be classified into a flat form, stone sheath, floor facility, wall facility, and entry and exit facility. The flat form of the Gijang mountain fortress and receiving reservoir is round. Concerning the sectional form, the wall was obliquely excavated in the trapezoid. As a stone sheath building method, it was built by undertaking a range work of oblong stone materials in a clockwise direction on a stamped soil floor. Then, it was treated with stamping using double layers of gray clay and yellowish brown clay on the floor and the wall. Also, in a space between the stamped layers on the floor, herbal plants and a straw mat were laid for waterproofing as well as to prevent sinking. As an entry and exit facility, two facilities were confirmed symmetrically in the southeast and in the northwest. It is believed that they were built additionally during rebuilding after the initial construction. The building process was revealed to have been carried out in 8 stages. Given the structure and excavated remains, the building period is estimated to be the early to mid 7th century for the initial building, the later 9th to 11th centuries for the primary rebuilding, and the later 16th to early 17th centuries for the secondary rebuilding.

• Korean Journal of Hospice Care
• /
• v.3 no.2
• /
• pp.1-11
• /
• 2003

Purpose: The purpose of this study was to find out the effect of hospice home care on the pain relief and quality of life of terminal cancer patients. Method: Experimental pre and post tests were provided to a single group to see the changes of quality of life of patients who were referred to a hospice home care department after having cancer treatment. They were visited at least 8 times for the duration of 4~6 weeks and were provided a 24 hour phone call service. 41 subjects were transferred to a hospice home care department after being discharged from hospital were selected. Result: 1)The first hypothesis that "the pain score of the subjects after receiving hospice home care would be different from before receiving hospice home care would be different from before receiving hospice home care" which scored 4.06 point at the first test and 3.41 at the second did not statistically show a significant difference(t=1.421 p=1.66), even though the pain score is decreased. 2)The 2nd hypotheses that "the quality of life score of the subjects after receiving hospice home care would be different from before receiving hospice home care" which scored 2.88 point at the first test and 3.39 at the second showed a significant difference(t=-6.759, p=.000) and was supported. Regarding the changes of quality of life score, social aspect(t=-5.745, p=.000), emotional aspect(t=-5.684, p=.000), and spiritual aspect(t=-6.889, p=.000) has significantly been increased, while physical aspect has been more decreased significantly than before the hospice home care is provided(t=4.282, p=.000). Conclusion: It was effective to provide hospice home care in relieving the terminal cancer patients' pain and in improving their quality of life, even though a short term hospice home care for 4-6 weeks was provided.

• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.43 no.3 s.309
• /
• pp.41-50
• /
• 2006

This paper presents a novel ultrasonic sensor system to overcome limited distance detection range that can be measured only more than 30cm by single ultrasonic transducer. This is accomplished by separation of receiving capacitive ultrasonic transducer from transmitting capacitive ultrasonic transducer. And hardwares and software of the system are described in detail. The system makes very close range as well as long range detect by wireless precisely. Frequency of trigger pulse is 10Hz, but it is very low frequency for transmitting data in wireless module. Therefore, for triggering between receiver and transmitter, an algorithm for mixing and distinguishing trigger pulse from carrier pulse by software is proposed. The system is designed by common microprocessor 8051. The performance of the proposed method has been assessed through two types. The first, transmitting and receiving transducer are put on both sides. And then, distance of two point is measured as far as 0mm. Secondly, transmitting transducer send out ultrasonic pulse and measure the time of flight(TOF) until a first echo from an object detected by the detached receiving transducer. The distance between the detached transducers and a reflecting object is measured as far as 7cm. Images of measured ultrasonic waves and TOF for two methods presented to prove effectiveness of results.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.51 no.9
• /
• pp.46-53
• /
• 2014

In this paper, ku-band RF transceiver system is designed for the unmanned aerial vehicle(UAV) line-of-sight(LOS) datalink. The RF transceiver system is consisted of the transmitting and receiving unit, RF front-end unit, and high power amplification unit. The transmitting and receiving unit has the functions of frequency up/down converting and channel changing. The RF front-end unit has the functions of transmitting and receiving signal duplexing, antenna selection, small signal amplification, and frequency filtering excluding the receiving signal. The high power amplification unit has the functions of ku-band power amplification and transmitting power variation(High/Middle/Low/Mute). The frequency up/down converting of transmitting and receiving unit is designed by using the superheterodyne method. The RF transceiver system is designed to obtain the broadband and high linearity properties for the reliable transmission and reception of high data-rate and high speed data. Also, the channel changing function is designed to use selectively the frequency as the operation environment of UAV.