• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.06a
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• pp.299-303
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• 2005

A lighting control switch, extended to incorporate a power line communication technology, is developed. The system uses not an exclusive microprocessor but a general one, and developed PPM protocol. The coupling circuit is a type of an isolation LC filter, and the impedance of the circuit was designed as low as possible to extend signal transmission distance. The frequency of the carrier, considering the data length and signal attenuation as the length of power lines, was set at 250 kHz. Tests on a prototype in an indoor power lines have shown that the switch has a stable operation with the distance of power lines

• Journal of Korean Society for Atmospheric Environment
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• v.6 no.1
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• pp.97-102
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• 1990

A pilot field study was conducted to measure indoor and personal exposure to carbon monoxide (CO) levels using personal monitors from January to February in 1989. The principal objectives of the study was to design and evaluate the research protocol and the instrumentation performance for application to the conduct of a large-scale personal monitoring program. The mean CO concentrations in kitchen and in bedroom were 23.4 and 11.9 ppm, respectively, while mean concentration of personal CO exposure was 18.9 ppm. It was found that the mean CO concentrations in kitchen exceeded 20 ppm of the Korea ambient CO standard(8-hr average) not to be exceeded more than three times per year. The results suggest that indoor CO levels in Korean houses appear to be affected by use of coal briquette for heating any cooking.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.29 no.3
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• pp.336-342
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• 2019

Introduction: An unexpected death was reported in a beginner immediately after starting the work at a plating factory. After the incident, air sampling was performed using a simulation of the situation as it had been at the time. Methods: To evaluate the airborne concentration of hydrogen cyanide, a total of six samples were collected: one personal sample, three area samples, and two background samples (office and outdoors). Hydrogen cyanide measurement was performed according to the standard sampling protocol recommended by the U.S. NIOSH (National Institute of Occupational Safety and Health). Results: The highest concentration of hydrogen cyanide was 0.938 ppm measured in a sample collected from the plating bath area with local exhaust ventilation. This value was approximately 20% of the ceiling occupational exposure limit. The personal sample showed a concentration of 0.135 ppm. Samples collected near the bath in which the incident occurred and a dehydrator showed hydrogen cyanide concentrations of 0.236 ppm and 0.101 ppm, respectively. Hydrogen cyanide was not detected in the background samples (office and outdoors). Conclusions: It is necessary to use proper ventilation systems and respirators in plating factories to prevent acute poisoning. Furthermore, it is important to educate and train new workers dealing with toxic substances.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.281-284
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• 2005

A lighting control switch, extended to incorporate a power line communication technology, is developed. The system uses not an exclusive microprocessor but a general one, and developed PPM protocol. The coupling circuit is a type of an isolation LC filter, and the impedance of the circuit was designed as low as possible to extend signal transmission distance. The frequency of the carrier, considering the data length and signal attenuation as the length of power lines, was set at 250 kHz. Tests on a prototype in an indoor power lines have shown that the switch has a stable operation with the distance of power lines

• Food Science and Preservation
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• v.15 no.2
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• pp.236-242
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• 2008

We investigated the optimum concentration of a $NaClO_2$ solution and the amount of gaseous $Cl_2$ for production of high yield and purity of aqueous $ClO_2$ by use of a gaseous chlorine-chlorite $ClO_2$ generator. This system produced lower concentrations of chlorine dioxide and is applicable for direct-use in food processing as a cleaner and sanitizer. The concentration of $NaClO_2$ solution and the amount of gaseous $Cl_2$ was varied from 0.01-0.1% and 100-1,000 g/hr, respectively. The concentrations of chlorite, chlorate, FAC (free available chlorine), and chlorine dioxide that were produced increased with increasing concentration of $NaClO_2$ solution and with the amount of gaseous $Cl_2$. The optimum concentration of $NaClO_2$ solution and amount of gaseous $Cl_2$ were 0.1% and 900 g/hr respectively. $ClO_2$ and FAC produced at these concentrations were 882.0 ppm and 8.0 ppm, with no detection of chlorite and chlorate. The yield and purity of $ClO_2$ were 97.0% and 96.0% respectively. Immersion-cleaning experiments showed that this protocol decreased the level of CFU/g by $10^3$- to $10^4$-fold, with a similar effect on fruit.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.38 no.6
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• pp.372-378
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• 2005

An analysis method of tetracyclines far fish and shellfish products containing large amount of low molecular materials and pigments was established. The recovery of the established analysis method for four tetracycline samples was $72-100\%$ and higher than other methods reported. Especially, proposed sample treatment protocol was shown to be effective for the removal of low molecular materials and pigments that tend to interfere with accurate analysis. The detection limit of oxytetracycline (OTC) and tetracycline (TC) from the sample was 0.02 ppm, and the detection limit of chlortetracycline (CTC) and doxycycline (DC) from the sample was 0.1ppm, To examine the efficiency of the established method and identify tetracycline usage in fish farms, tetracycline group antibiotics in the flounder being cultured was monitored. The improved method can be used for fish and shellfish products effectively and all surveyed fish farms have used tetracycline all the year round. The proposed method was adopted as official method for fishery products by Korean Food and Drug Administration in 2003 and it is being used by regulatory authority as National Fishery Products Quality Inspection Service.

• 한국생물공학회:학술대회논문집
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• 2005.10a
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• pp.456-462
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• 2005

The objective of this study was to develop a removal process by which $H_2S$ could be biologically removed from the odoriferous gases generated in the waste food recycling process. In order to develop this process we were first required to select a proper biofilter support protocol. When the selected biofilter equipment was then tested suing a synthetic odoriferous gas containing 600 ppm of $H_2S$, we noted a maximal removal rate of 658 $g-H_2S/m^3{\cdot}hr$, using polypropylene fibrils as supporting materials. Under identical experimental conditions, we obtained a value of 411.2 $g-H_2S/m^3{\cdot}hr$, using polyurethane as a support material. We also conducted a trial in which volcanic stone was utilized as a support material, and in this trial, we logged a maximal 105.1 $g-H_2S/m^3{\cdot}hr$ removal rate. As the result of our experiments, we concluded that polypropylene fibrils constituted the ideal material for the removal of $H_2S$ gas via biological treatment.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.4
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• pp.792-797
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• 2005

Lighting control switches based on the power line communication technology are developed and extended to incorporate dimming control to provide energy saving and appropriate illumination. The developed switch uses a general purpose microprocessor and associated electronics. Both the power line communication and the dimming function are implemented in one microprocessor, and it enables the low price commercialization. The frequency of the carrier was set at 250kHz considering the transmission data length and signal attenuation in power lines. Tests on prototypes in an low-voltage power lines have shown that the switches have a robust operation characteristics with the length of power lines and the variation of load capacities.

• Journal of Korean Society for Atmospheric Environment
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• v.18 no.E4
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• pp.181-190
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• 2002

A novel portable device for the direct measurement of alveolar breath carbon monoxide (CO) was developed. The major components of the device include a mouthpiece, non-rebreathing two-way valve, Teflon tube, and CO dosimeter. An alveolar CO measurement can be completed within 1.5 min when using the proposed device and measurement protocol. Measurements could be read to the nearest 0.1 ppm. Humidity did not influence the CO measurements taken by the CO dosimeter, plus there were no problems associated with the recovery and carryover of CO through the device. The criterion for significance in statistical analyses was p< 0.05. The average recovery was 103 and 99% for recovery and carryover experiments, respectively. Test results using the proposed alveolar CO measurement system reflected a good reproducibility. This reproducibility was also supported by the finding that the relative standard deviations (RSDs) of the data sets were less than 7％ for the loss experiment and less than 8% for the carryover experiment. Consequently, it would appear that the proposed device can be effectively applied to measure CO levels found in breath, thereby overcoming several disadvantages associated with the conventional bag and adsorbent tube sampling methods.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.1
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• pp.179-185
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• 2017

Communication technologies hold a significant place in the swarm flight of drones for surveillance, inspection of disasters and calamities, entertainment performances, and drone collaborations. A GCS(ground control station) for the control of drone swarms needs its devoted communication method to control a large number of drones at the same time. General drone controllers control drones by connecting transmitters and drones in 1:1. When such an old communication method is employed to control many drones simultaneously, problems can emerge with the control of many transmitter modules connected to a GCS and frequency interference among them. This study implemented a transmitter controller to control many drones simultaneously with a communication chip of 2.4GHz ISM band and a Cortex M4-based board. It also designed a GCS to control many transmitter controllers via a network. The hierarchical method made it possible to control many more drones. In addition, the problem with frequency interference was resolved by implementing a time- and frequency-sharing method, controlling many drones simultaneously, and adding the frequency hopping feature. If PPM and S.BUS protocol features are added to it, it will be compatible with more diverse transmitters and drones.