• Journal of the Institute of Electronics Engineers of Korea SC
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• v.43 no.1 s.307
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• pp.45-52
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• 2006

In this paper, authors propose a step-up converter of pulse width modulation (PWM) and power factor correction (PFC) by using a novel loss-less snubber. The proposed converter for a discontinuous conduction mode (DCM) eliminates the complicated circuit control requirement and reduces the size of components. The input current waveform in the proposed converter is got to be a sinusoidal form of discontinuous pulse in proportion to magnitude of ac input voltage under the constant duty cycle switching. Thereupon, the input power factor is nearly unity and the control method is simple. In the general DCM converters, the switching devices are fumed-on with the zero current switching (ZCS), and the switching devices must be switched-off at a maximum reactor current. To achieve a soft switching (ZCS and ZVS) of the switching turn-off, the proposed converter is constructed by using a new loss-less snubber which is operated with a partial resonant circuit. The result is that the switching loss is very low and the efficiency of converter is high. Some simulative results on computer and experimental results are included to confirm the validity of the analytical results.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.3
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• pp.421-432
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• 2020

This paper proposes a 2-kW solid-state power amplifier (SSPA) developed by employing power amplifier pallets designed using gallium-nitride high electron mobility transistors, which is used in S-band military radars and to replace existing traveling-wave tube amplifier (TWTA). The SSPA consists of a high-power amplifier module, which combines eight power amplifier pallets, a drive amplifier module, a digital control module, and a power supply unit. First, the amplifier module and component were integrated into a small package to account for space limitations; next, an on-board harmonic filter was fabricated to reject spurious components; and finally, an auto gain control system was designed for various duty ratios because recent military radar systems are all active phase radars using the pulse operation mode. The developed SSPA exhibited a max gain of 48 dB and an output power ranging between 63-63.6 dBm at a frequency band of 3.1 to 3.5 GHz. The auto gain control function showed that the output power is regulated around 63 dBm despite the fluctuation of the input power from 15-20 dBm. Finally, reliability of the developed system was verified through a temperature environment test for nine hours at high (55 ℃) / low (-40℃) temperature profile in accordance with military standard 810. The developed SSPA show better performance such as light weight, high output, high gain, various safety function, low repair cost and short repair time than existing TWTA.

• Journal of Biomedical Engineering Research
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• v.19 no.5
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• pp.477-486
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• 1998

In this paper, we implemented the urine analysis system capable of measuring a qualitative and semi-quantitative and assay using strip. The analysis algorithm of urine analysis was adopted a fuzzy logic-based classifiers that was robust to external error factors such as temperature and electric power noises. The spectroscopic properties of 9 pads In a strip were studied to developing the urine analysis system was designed for robustnesss and stability. The urine analysis system was consisted of hardware and software. The hardware of the urine analysis system was based on one-chip microprocessor, and Its peripherals which composed of optic modulo, tray control, preamplifier, communication with PC, thermal printer and operating status indicator. The software of the urine analysis system was composed of system program and classification program. The system program did duty fort system control, data acquisition and data analysis. The classification program was composed of fuzzy inference engine and membership function generator. The membership function generator made triangular membership functions by statical method for quality control. Resulted data was transferred through serial cable to PC. The transferred data was arranged and saved be data acquisition program coded by C+ + language. The precision of urine analysis system and the stability of fuzzy classifier were evaluated by testing the standard urine samples. Experimental results showed a good stability states and a exact classification.

• Journal of the Korean Society of Marine Environment & Safety
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• v.21 no.4
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• pp.409-420
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• 2015

In this study, I researched, analysed and compared the examples of civilian maritime search and rescue auxiliaries of world leading countries' such as Japan and America, and the Korean volunteer fire fighting team. Through this, I suggest that the decentralized civilian maritime search and rescue forces of Maritime Rescue and Salvage Association and KCG Civilian Auxiliary should be united into unified search and rescue system and establish legal basis for stabilized support and development. It seem that we should organize laws and regulations for the government to have centralized control of rescue mission as in the cases of America and Canada and elivate rescue mission capability with systemized education and training entrusted to specialized external training organization. I proposed to establish financial support such as fund for the stabilized status of civilian auxiliary, domestic and overseas training session for the civilian auxiliary to inspire integrity and sense of duty as a part of maritime search and rescue forces.

• Journal of the Korean Society of Safety
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• v.30 no.1
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• pp.137-143
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• 2015

Fire fighter are exposed to the situations which are hard to predict due to continuous and accidental changes which hinder their fire fighting activity. As these threats of safety accident act as fear factors, they are doing insecure fire fighting activities. Therefore, as unclear and abnormal risks of working environment such as the riskiness of expansion of disaster, instability, obstacles of activities, abnormality, urgency, etc. increase, safety accidents are caused. This study analyzes the actual condition of safety and health and awareness of fire fighter who are exposed safety accidents during their fire fighting activities and utilize such result as the basis data to secure safety of fire fighter, keep efficient safety control and prevent accidents. The results of analysis are as follows. As rescue works among all fire-fighting works shows the highest emotional stabilization and the highest post-traumatic stress disorder is shown in fire sergeant level positions, and fire fighters whose working period is 10-15 years, reinforcing safety training to long-term workers is necessary. As the result of survey regarding safety awareness, the highest awareness level was shown in fire sergeant level positions, and fire fighters whose working period is over 20 years, and when it comes to operation of fire fighting equipments, fire-fighting workers and workers having 1-4 years of working period showed high safety awareness. The more serious injury in a fire fighter experienced as the first injury after working as a fire-fighter, the more cause-and-effect relationship was shown between personal physical condition and work, and it is shown as obstacles of fire fighting activities and affects to post-traumatic stress disorder. Moreover, as after-work off duty activities also affect to official disaster, systematic improvement of working environment is required. Occupational medical work compatibility evaluation considering the distinct characteristics of works to secure fire-fighter' health care together with fire-fighting capability is shown to be necessary.

• Journal of Preventive Medicine and Public Health
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• v.23 no.3 s.31
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• pp.275-284
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• 1990

To obtain the useful information for the status of working environment and health management of workers in manufacturing industries, comparision of results on the status of working environmental and health management of workers for 32 manufacturing industries in Chunan area from 1988 to 1989 was carried out. The results were as follows : 1. The rate of over-PEL (Permissible Exposure Limit) to for hazardous factors decreased significantly 23.5% in 1988, 18.3% in 1989 (p<0.05) and, the highest rate of over-PEL was the stone and sand handling industry, the highest rate of over-PEL was the dusty workplace as 38.5% in 1988, 35.2% in 1989. 2. The rate of workers exposed to hazardous factors in 1988 and in 1989 was 22.4% respectively, the rate of workers checked up special health examination was 40.1% in 1988, 75.3% in 1989. In stone and sand handling and medicochemical industries, none of workers exposed to hazardous factors was subjected to special health examination in 1988, but 75% of workers exposed to hazardous factors had checked up in 1989. 3. The 6 industries appointed as part-time factory physician among 17 industries which were supposed to have factory physician according to the Safety and Healthy Act of Korea, 6 out of 24 industries only appointed industrial hygienist, furthermore 4 out of 6 hygienists had another duty in addition to occupational hygiene itself.

• ETRI Journal
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• v.36 no.3
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• pp.352-360
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• 2014

This paper presents a 900 MHz zero-IF RF transceiver for IEEE 802.15.4g Smart Utility Networks OFDM systems. The proposed RF transceiver comprises an RF front end, a Tx baseband analog circuit, an Rx baseband analog circuit, and a ${\Delta}{\Sigma}$ fractional-N frequency synthesizer. In the RF front end, re-use of a matching network reduces the chip size of the RF transceiver. Since a T/Rx switch is implemented only at the input of the low noise amplifier, the driver amplifier can deliver its output power to an antenna without any signal loss; thus, leading to a low dc power consumption. The proposed current-driven passive mixer in Rx and voltage-mode passive mixer in Tx can mitigate the IQ crosstalk problem, while maintaining 50% duty-cycle in local oscillator clocks. The overall Rx-baseband circuits can provide a voltage gain of 70 dB with a 1 dB gain control step. The proposed RF transceiver is implemented in a $0.18{\mu}$ CMOS technology and consumes 37 mA in Tx mode and 38 mA in Rx mode from a 1.8 V supply voltage. The fabricated chip shows a Tx average power of -2 dBm, a sensitivity level of -103 dBm at 100 Kbps with PER < 1%, an Rx input $P_{1dB}$ of -11 dBm, and an Rx input IP3 of -2.3 dBm.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.3
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• pp.7-12
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• 2012

Cooled EGR system is widely used to reduce NOx emissions in diesel engine. But when EGR rate was increased, combustion stability was worsened and PM level was increased. So determining optimized control point of EGR rate is important. In order to determine this point, it is important to figure out the effect of EGR system on the exhaust emissions. In this research, NOx and PM emissions were analyzed with various coolant temperature supplied to the EGR cooler at several positions such as downstream of turbocharger, upstream and downstream of DPF. Effects of some variables such as EGR rate, hot / cooled EGR and change of injection timing were estimated. And $CO_2$ emissions were measured at exhaust and intake manifold to calculate EGR rate at each engine operating condition. Also combustion analysis was performed in each engine operating conditions. In the result of this study, there was trade-off between NOx emissions and PM emissions. When EGR rate was increased, combustion pressure was decreased and COV of IMEP was increased.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2016.05a
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• pp.103-105
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• 2016

Shin(2015) etc. published use of smart phones on the effect the use of smart phones released in the ship duty performed by survey of using smart phones Status and Usage in previous studies, soon as the survey provided this environment(36% on sailing) where you can use your smart phone from the ship, at the risk of officers using survey questionnaires were analyzed smart phones that use about twice the risk than before. In this study, maritime those who have experienced a period of sailors aboard a diagnostic test subjects Ship Handling Simulation analysis evaluation item of Maritime Traffic Admit, Proximity evaluation of a ship evaluation, by measuring the degree of danger that the subjective evaluation and control of the ship evaluation to evaluate the risk on navigation safety. Also indicated the risk of a smart phone quantitatively by measuring the time that the awareness of dangerous situation depending on using smart phone or not.

• Archives of Plastic Surgery
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• v.36 no.3
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• pp.262-268
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• 2009

Purpose: Recently medical dispute about plastic surgery is increasing rapidly as result of growing surgery itself due to high interest in appearance and advertisement of plastic surgery. So we want to find a way to prevent similar medical accident by making better solution of plastic surgery through case analysis of medical dispute. Method: 161 cases about plastic surgery asked for aid at Korea Consumer Agency and 41 cases judged at the court was surveyed and gender, location and kind of hospital, goal and kind of operation, making operation agreement or not, kind of damage, result of process, result of lawsuit was studied from 2004.1.1. to 2006.12.31. Result: Medical doctor have to explain about symptoms of disease, method of treatment, possibility of complication, prognosis to patients before therapy so they can make decision if they take operation by doctor or not. On this survey, among the patients who underwent re - operation or had complication, 88.1%(96 from 109 cases) of them didn't get enough explanation about possibility of complication before surgery They brought lawsuit insisting they would not undergo operation if they got enough explanation about possibility of complication and result of operation before surgery. Conclusion: It is advisable that doctor must observe the duty of explanation before surgery and respect the right to decide of patient, make operation agreement and put down concrete progress note and store the pre and post operative photo to avoid medical accident. It is also needed to have guideline of therapy, Code of ethics, organization which deals with medical dispute, reconsideration of law to control that.