• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.10a
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• pp.570-573
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• 2022

This paper presents the identification of void diameters for a cast-resin transformer using an artificial neural network (ANN) model. A PD signal was measured by the Rogowski coil sensor which has the planar and thin structures fabricated on a printed circuit board (PCB), and the PD electrode system was fabricated to simulate a PD defect by a void. In addition, void samples with different diameters were fabricated by injecting air in a cylindrical aluminum frame using a syringe during the epoxy curing process. To identify the diameter of void defects, PD characteristics such as the discharge magnitude, pulse count, and phase angle were extracted and back propagation algorithm (BPA) was designed using virtual instrument (VI) based on the Labview program. From the experimental results, the BPA algorithm proposed in this paper has over 90% accurate rate to identify the diameter of void defects and is expected to use reference data of maintenance and replacement of insulation for cast-resin transformers in the on-site PD measurement.

• Tuberculosis and Respiratory Diseases
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• v.44 no.1
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• pp.154-161
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• 1997

Background : Although the long term adverse effects of cigarette smoking on health are well known, the acute possible detrimental effects of smoking on pulmonary or cardiovascular function, especially when these systems are stressed by the metabolic demands of exercise, have not been well studied The purpose of this study is to determine the acute action of cigarette smoking on cardiopulmonary function under stress. Method : Twenty -one healthy smoking subjects were studied. Before exrecise testing, history taking, physical examination and baseline studies, including CBC, chest PA, PFT and EKG, were done. The subjects performed an incremental bicycle exercise test to exhaustion on two occasions, one without smoking and the other after smoking 5 cigarettes/h for 2 hours. All indices of P.F.T. and bicycle ergometry were compared between before and after smoking. Results : 1. $VO_2$max and $O_2$ pulse showed significant decrease in smoking day. 2. Although there were no significant differences, anaerobic threshold showed a tendency of decrease and HRmax showed that of increase in smoking day. 3. P.F.T. and respiratory indices showed no significant change io smoking day. Conclusion : Cigarette smoking has immediate adverse effect, especially on the cardiovascular system rather than the respiratory system. These results would be due to the effect of elevated HbCO and/or impaired blood flow in response to the exercise stimulus.

• Journal of the Korean Chemical Society
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• v.33 no.5
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• pp.558-567
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• 1989

The synthesis of methanol from carbon dioxide and hydrogen was studied for various compositions of Cu/ZnO catalyst system. Effect of the composition ratio of CuO and ZnO on the catalytic activity in the above reaction and the relationship between the activity and the characteristics of the catalysts were explained from the result of surface area measurements, SEM, XRD, and XPS. The major products of the reaction were methanol and carbon monoxide. The selectivity to methanol increased with increase of the copper oxide content in the catalyst up to CuO: ZnO = 30:70 weight ratio, and decreased rapidly when the content is above 70%. SEM and BET measurements, indicate that this point corresponds to the increasing point of the catalyst crystallite size and the decreasing point of the surface area. As to the Cu/Cu + Zn atomic ratio, the surface concentration of copper measured by XPS decreased remarkably when the copper oxide content in catalyst was higher than 50%. All the unreduced catalysts had almost same binding energy of Cu(2P3) level, but the binding energy for $Cu(2P^3)$ level of reduced catalysts was lowered than that of calcined catalysts. The surface copper species which was in the maximum amount when the CuO:ZnO composition in the catalyst was 30:70, existed as zero valent copper. This result agreed with the experimental result that the highest rate of methanol formation was observed when the CuO content in the catalyst was 30%. It was postulated that these reduced catalysts performed with a relatively strong basicity because the formation rate of acetone was higher than that of propylene in isopropanol decomposition as measured in a pulse type reactor.

• Korean Journal of Animal Reproduction
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• v.26 no.2
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• pp.125-132
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• 2002

This study was conducted to examine the effects of electric stimulation conditions on in vitro developmental ability of procine embryos after somatic cell nuclear transfer, The porcine ear cell was cultured in vifro for confluency in serum-starvation condition (TCM-199＋0.5% FBS) for cell confluency. The zona pellucida of IVM oocytes were partially drilled using laser system. Single somatic cell was individually transferred into the enucleated oocyte. The reconstructed embryos were electrically fused with 0.3M mannitol. After electric fusion, the embryos were activated and cultured in NCSU-23 medium containing 10% FBS at 39$^{\circ}C$, 5% $CO_2$ in air for 6 to 8 days. Nuclear transferred(NT) oocytes which fused at a field strength of 1.90kv/cm showed a higher (P<0.05) fusion rate(49.5%, 50/101) compared to 2.10 kv/cm(25.8%, 24/93) or 2.50kv/cm(30.3%, 27/89). After electric activation, the cleavage rate of NT embryos was 48.0(24/50), 66.6(16/24) and 70.3% (19/27), respectively and these were not different. There was no significant difference in fusion rate by duration and pulse of electric stimulation. In cleavage rate, however, more NT embryos(76.3%, 45/59) cleaved at 60 $\mu$sec twice than other embryos(49.1 to 56.5%) with different conditions of electric stimulation(P<0.05). NT embryos activated at a field strength of 1.50kv/cm showed a higher developmental rate(9.8%, 5/51) than those embryos activated at 1.25kv/cm(0%) or parthenotes(6.4%, 7/109). These results suggest that some factors such as field strength, duration and pulse of electric stimulation could be affected to in vitro developmental ability of nuclear transplanted porcine embryos.

• KSBB Journal
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• v.15 no.5
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• pp.489-496
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• 2000

Several culture systems including batch, two-stage CSTR, semi-fed batch, and two-stage cyclic fed-batch were investigated for the efficient production of the Fab fraction of PDC-E2 specific human monoclonal antibody using high cell density recombinant E. coli. A two-phase batch system and a two-stage continuous system were examined to overcome plasmid instability problems, by separating the growth and the production stages. The cell density and productivity of the two-stage continuous culture was better than that of the two-phase batch fermentation. In the two-stage continuous culture system with DO-stat, the cell growth and the productivity were superior to those of the system without the DO control. Also, almost total plasmid stability was maintained in the two-stage continuous culture system. Modified M9 medium was selected as an optimum feeding medium for the fed-batch process, and the optimum C/N ratio determined to be 2:3. The optimum feeding rate was $0.6g/\ell/hr$ for a constant feeding strategy in semi-fed batch system. When the feeding medium was fed by pulsing, it was observed that more frequent pulsing resulted in improved cell growth. The linear feeding method was the most efficient of the various feeding methods tested. Finally, high cell density culture using a two-stage cyclic fed batch system with pH-stat was tried because the linear feeding method showed limitations in terms of obtaining high cell densities, and a cell density of $54 g/\ell$ was achieved. It was concluded that the two-stage cyclic fed batch system was the most efficient system for high cell density culture of the systems tested. However, productivity improvements were lower than expected due to the extremely high accumulations of acetate, although the low levels of residual glucose were maintained.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.4
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• pp.21-28
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• 2006

In this paper, the proposed full-bridge high frequency isolated zoo voltage and zero current switching phase shifted pulse width modulation(ZVZCS PS-PWM)DC-DC converter among fuel cell generation system consist of 1.2[kW] fuel cell of Nexa Power Module, full-bridge DC-DC converter to boost the fuel cell low voltage($28{\sim}43[%]$) to 380[VDC] and a single phase full-bridge inverter is implemented to produce AC output(220[VAC], 60[Hz]). A tapped inductor filter with freewheeling diode is newly implemented in the output filter of the proposed full-bridge high frequency isolated ZVZCS PS-PWM DC-DC converter to suppress circulating current under the wide output voltage regulation range, thus to eliminate the switching and transformer turn-on/off over-short voltage or transient phenomena. Besides the efficiency of $93{\sim}97[%]$ is obtained over the wide output voltage regulation ranges and load variations.

• The Korean Journal of Emergency Medical Services
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• v.11 no.3
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• pp.163-174
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• 2007

Purpose : This study analyzes prehospital care report of emergency service at prehospital stage, examines characteristics of activities of 119 paramedics and its users and aims to provide help for improving emergency system in future. Methods : Data collected were 119 prehospital care report and hospital records with 7,160 patients to emergency room by 119 ambulance from Jan. 1 to Dec. 31, 2006 and percentage and frequency of the data were obtained. Results : 1) Use of emergency room by 119 ambulance was increased in summer and autumn such as August(9.1%), September(11.2%) and October(13.5%) and it was more frequently used on Monday(17.3%), Saturday(17.2%) and Friday(16.1%) by telephone(98.6%). 2) Using emergency room was most in over sixties(51.8%), men(64.2%), community residents (78.3%), by report of family(50.3%) and at '09:01~12:00'(16.5%). 3) Symptoms of emergency room users included headache, chest pain, stomachache, lumbago and others as 40.6% and places where patients were found were at home(60.1%) due to chronic internal diseases at 49.2%. 4) Most of non-emergency patients(80.2%) arriving at hospital had normal pupil condition (88.4%) and clear consciousness(71.2%) and most of them left hospital after having first-aid treatment. 5) Physiological symptom tests evaluated by paramedics at prehospital stage included blood pressure(56.6%), pulse(22.9%), breathing(13.0%) and temperature(9.2%), and there was no SPo2 case. 6) Classification of severity by paramedics showed difference as emergency patients(18.0%) by paramedics and those(24.9%) by hospital. 7) First-aid treatments by paramedics at prehospital stage were promoting comfort(28.9%), hemostasis(7.7%), fixing cervical vertebrae(4.0%) and ensuring vein route(3.1%). 8) Selectors of medical agency were patients or guardians(86.2%) and emergency medical technicians(73.6%). Conclusion : To sum up the above research, it was found that percentage of using 119 ambulance by non-emergency patients was higher and paramedics performed basic first-aid treatment rather than professional first-aid treatment due to several conditions such as legal problems, range of allowance, etc. Therefore, it is considered that method to reduce frequency of ambulance by non-emergency patients and approaches to alleviate limitations of allowance of paramdeics to make them perform effective first-aid treatment at prehospital stage should be sought in the dimension of individual, organization and government.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.11
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• pp.1-10
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• 2007

In this paper, we proposed channel estimation scheme for LR-UWB system which has low data rate for WPAN in IEEE 802.15.4a. At the transmitter, we proposed dynamic power level allocation depends on channel condition in specific period when we modulate signal. We use two orthogonal code to estimate channel at once. It can estimate channel more accurately by using two code which shows good correlation characteristic then it can estimate more accurately by spreading gain. Using estimated channel condition, we synchronize symbol timing of transmitted signal. Then determined power allocation scheme and channel information is transmitted to transmiter side. Finally, using these information, transmiter side change the power level of repeated pulse to adopt to channel condition. Simulation is performed under S-V channel for LR-WPAN in IEEE 802.15.4a and we compare the performance with a different type of receiver type. We use coherent and non-coherent method at the receiver. Simulation result shows us at the NLOS channal performance evaluation is greater than that of LOS channel and the result is independent of receiver type. In the NLOS channel, as the signal delay spreading is big, performance evaluation is also increased.

• 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.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.11
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• pp.746-754
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• 2016

Smart healthcare systems, a convergent industry based on information and communications technologies (ICT), has emerged from personal health management to remote medical treatment as a distinguished industry. The smart healthcare environment provides technology to deliver vital information, such as pulse rate, body temperature, health status, and so on, from wearable devices to the hospital network where the physician is located. However, since it deals with the patient's personal medical information, there is a security issue for personal information management, and the system may be vulnerable to cyber-attacks in wireless networks. Therefore, this study focuses on a key-development and device-management system to generate keys in the smart environment to safely manage devices. The protocol is designed to provide safe communications with the generated key and to manage the devices, as well as the generated key. The security level is analyzed against attack methods that may occur in a healthcare environment, and it was compared with existing key methods and coding capabilities. In the performance evaluation, we analyze the security against attacks occurring in a smart healthcare environment, and the security and efficiency of the existing key encryption method, and we confirmed an improvement of about 15%, compared to the existing cipher systems.