• Journal of the Korean Society of Marine Environment & Safety
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• v.21 no.1
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• pp.97-102
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• 2015

The long line fishing machine is combined with motor and two disc rollers has used on the small size fishing-boat under 1 ton located in near Jeollanam-do seaside. The long line fishing motor is controlled only one direction because the fishing line is loaded heavily at pulling up. On this paper we made the long line fishing 400W power motor controller which it was usually applied under 1 ton fishing boat, and designed the controller using PWM chip, Half bridge driver and MOSFET for one direction motor control. Furthermore some user convenience devices were added like battery indicator and safety protection circuit for battery overdischarge and battery source wire mismatch connection. So we protected the battery from overdicharging when the battery voltage was below 11.5V and fishermen didn't need to worry about source lines misconnection anymore. We confirmed the test version of controller was the good working condition at land and sea.

• Physical Therapy Korea
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• v.18 no.1
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• pp.83-92
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• 2011

Osteoarthritis is a degenerative joint disease and is led to physical disability. Yet the development of effective disease-modifying treatments has lagged. In this study, I examined the effect of physical therapeutic intervention through microcurrent stimulation and attempt to find which degree of intensity, either 25 ${\mu}A$ or 500 ${\mu}A$ with a regular 5 pps pulse, is more effective in the osteoarthritis. Osteoarthritis was induced with a mixture of 2% carrageenan and 2% kaolin in 26 male Sprague-Dawley rats. The mixture (0.1 $m{\ell}$) was injected into the intra-articular capsule of knee joint once a week for three weeks. Five animals did not show degenerative changes by radiological findings and excluded in the following experiment. Osteoarthritic animals were randomly divided into 3 groups ($n_1$, $n_2$, $n_3$=7/each): untreated, treated with 25 ${\mu}A$, treated with 500 ${\mu}A$. All experimental groups received microcurrent stimulation for four weeks (15 min/day, 5 days/week). The ethological inspection of foot print analysis on the walking corridor was accomplished every week. Histological preparations and immunohistochemical staining with insulin-like growth factor-1 were also done in the articular cartilages. All of these parameters were compared with those of osteoarthritic control group (n=7). The ethological inspection of foot print analysis revealed that changes of walking track (paw width) and stride length was significantly increased in both experimental groups. The better results were observed in experimental group treated with 25 ${\mu}A$ intensity without significance than group treated with 500 ${\mu}A$. Histological preparations disclosed that routine hyaline cartilage of articular surface were altered to fibrous cartilage in untreated group and experimental group treated with 500 ${\mu}A$ intensity. But a little changes were seen in experimental group treated with 25 ${\mu}A$ intensity. Immunolocalization of insulin-like growth factor-1 was simultaneously decreased according to the duration of osteoarthritis, and did not show significant difference among the groups. In this study discovered that the microcurrent stimulation, especially 25 ${\mu}A$ intensity, had a positive effect by the ethological inspection, histological and immunohistochemical stainings. These results suggest that microcurrent stimulation with low-intensity might be effective in the promotion of healing process for the osteoarthritis.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.9
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• pp.883-891
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• 2013

In wireless smart phone charging scenario, the transmitter pad is larger than the size of the receiver pad. Thus, it is important to supply a constant power to the receiver regardless of its location. In this paper, we propose a new method to regulate the receiver's power by adjusting a drain bias of class E power amplifier. The proposed LF-band wireless power transfer system is as follows: a buck converter power supply which is controlled by a pulse width modulation(PWM) IC TL494, a class E amplifier using a low cost IRF510 power MOSFET, a transmitter coil whose dimension is $16cm{\times}18cm$, a receiver coil whose dimension is $6cm{\times}8cm$, and a full bridge rectifier using Schottky diodes. A measured performance show a maximum output power of 4 W and system efficiency of 67 % if we fix the bias voltage. If we adjust the bias voltage, the received power can be maintained at a constant power of 2 W regardless of receiver pad location.

• Geophysics and Geophysical Exploration
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• v.8 no.3
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• pp.224-231
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• 2005

In geophysical field surveys, commercial equipments often fail to resolve the subsurface target or even sometimes fail to be applied because they do not fit to the various field situations or the physical properties of the medium or target. We developed a geophysical measurement system, which can be easily adapted for the various field situations and targets. The system based on PXI with A/D converter and some stand alone equipment such as Network Analyzer was applied to borehole radar survey, borehole sonic measurement and electromagnetic noise measurement. The system for borehole radar survey consists of PXI, Network Analyzer, dipole antennas, GPIB interface is used for PXI to control Network Analyzer. The system for borehole sonic measurement consists of PXI, 24 Bit A/D converter, high voltage pulse generator, transmitting and receiving piezoelectric sensors. The electromagnetic noise measurement system consists of PXI, 24 Bit A/D converter, 2 horizontal component electric field sensors and 2 horizontal and 1 vertical component magnetic filed sensors. The borehole radar system has been successfully applied to detect the width of the artificial tunnel through which the borehole pass and to image buried steel pipe, while the commercial borehole radar equipment failed. The borehole sonic system was tested to detect the width of artificial tunnel and showed a reasonable result. The characteristic of electromagnetic noise was grasped at an urban area with the data from the electromagnetic noise measurement system. The system is also applied to characterize the signal distortion by induction between the electric cables in resistivity survey. The system can be applied various geophysical problems with a simple modification of the system and sensors.

• Journal of Practical Agriculture & Fisheries Research
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• v.17 no.1
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• pp.57-71
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• 2015

This study was conducted to develop the fertigation system with a peristaltic hose pump and brushless DC motor. The fertigation system was consisted of sensor, main controller, motor control unit, peristaltic pump, water supply pump, control panel, and filter. The peristaltic pump discharges liquid by squeezing the tube with rollers. Rollers attached to the external circumference of the rotor compresses the flexible tube. The fluid is contained within a flexible tube fitted inside a circular pump casing. The developed fertigation system has no mixing tank but instead injects directly a concentrated nutrient solution into a water supply pipe. The revolution speed of the peristaltic pump is controlled by PWM (Pulse width modulation) method. When the revolution speed of the peristaltic pump was 300rpm, the flow rate of the 3.2, 4.8, 6.3mm diameter tube was 202, 530, 857mL/min, respectively. As increasing revolution speed, the flow rate of the peristaltic pump linearly increased. As the inner diameter of a tube larger, a slope of graph is more steep. Flow rate of three roller was more than that of four roller. Flow rate of a norprene tube with good restoring force was more than that of a pharmed tube. As EC sensor probe was installed in direct piping in comparison with bypass piping showed good performance. After starting the system, it took 16~17 seconds to stabilize EC. The maximum value of EC was 1.44~1.7dS/m at a setting value of 1.4dS/m. The developed fertigation system showed ±0.06dS/m deviation from the setting value of EC. In field test, Cucumber plants generally showed good growth. From these findings, this fertigation system can be appropriately suitable for fertigation culture for crops.