• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.215-218
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• 2001

This paper is proposed a sinusoidal input current multi-level ac-dc converter using transformer. The multi-level converter which controls input current by combining Buck converter to Improve input current characteristics. This method, which is multiplying and duplicating output of converter of equal capacity, is able to control unit power factor of input current, reduce the problem caused by high frequency switching, and apply to high power converter because filter is not necessary The feasibility of the circuit is verified by computer simulation using PSIM

• Korean Journal of Animal Reproduction
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• v.17 no.4
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• pp.311-323
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• 1994

This study was conducted to observe seasonal and individual changes in semen characteristics and sperm freezability, and sperm penetration into zona-free hamster eggs in Korean native goats. Buck response and change in semen characteristics to electrical stimulations was evaluated for four seasons throughout 2 years and percentage of motile sperm and normal apical ridge acrosome was investigated after equilibration and thawing for 4 seasons with 5 bucks. Sperm penetration rate was evaluated for 4 bucks. 1. Probe insertion at depth of 7cm and repeated stimulation for 3 sec was more effective(P<0.05) in buck response and semen collection than those of other conditions. 2. Semen characteristics from electrojaculation was signficantly(P<0.005) higher in spring and fall for semen volume, in spring and summer for sperm concentration and in fall for sperm motility than those in other seasons, respectively. However, there were no differences in total sperm among seasons. 3. Buck response to electrical stimulation showed significant difference(P<0.05) among individuals in all 3 seasons except winter. Significant individual difference in semen volume was only in spring and summer, but there was no indivudual difference in sperm concentration and total sperm in all season. 4. Washing of semen before freezing treatment was greatly(P<0.05) beneficial to sperm motility after thawing, no matter whether ejaculates exhibit egg yolk coagulation or not. 5. Sperm motility after glycerol equilibration was significantly(P<0.05) low in summer semen and motility after thawing was greatly(P<0.05) higher in winter semen than in other seasons. Freezability of unwashed sperm was significantly difference among bucks, but a yearly freezability of washed sperm after chilling and thawing were no differences among bucks and percentage of normal apical ridge acrosome were not different among seasons and bucks. 6. There was no significant difference in sperm motility after thawing between egg yolk levels in summer, although 20% level gave more higher motility than 5% level. 7. In summer, 3.2% glycerol and 3-h equilibration gave greatest percentage(P<0.05) of sperm motility and normal apical ridge acrosome after thawing. 8. Sperm penetration rate into zona-free hamster eggs was not different between bucks and seasons. Overall, it is concluded that to obtain maximum sperm output and successive semen freezing by electrojaculation method, buck selection with good response in all season could be basically considered and that seasonal effect on sperm freezability was more greater than that of individual bucks.

• Journal of Power Electronics
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• v.19 no.4
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• pp.858-868
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• 2019

With the widespread use of modern clean energy, lithium-ion batteries have become essential as a more reliable energy storage component in the energy Internet. However, due to the difference in monomers, some of the battery over-charge or over-discharge in battery packs restrict their use. Therefore, a novel multiphase interleaved converter for reducing the inconsistencies of the individual cells in a battery pack is proposed in this paper. Based on the multiphase converter branches connected to each lithium battery, this circuit realizes energy transferred from any cell(s) to any other cell(s) complementarily. This flexible interlaced converter is composed of an improved bi-directional Buck-Boost circuit that is presented with its own available control method. A simulation model based on the PNGV model of fundamental equalization is built with four cells in PSIM. Simulation and experimental results demonstrate that converter and its control achieve simple and fast equalization. Furthermore, a comparison of traditional methods and the HNFABC equalization is provided to show the performance of the converter and the control of lithium-based battery stacks.

• Journal of IKEEE
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• v.12 no.3
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• pp.176-183
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• 2008

The high efficiency power management IC(PMIC) with DTMOS(Dynamic Threshold voltage MOSFET) switching device is proposed in this paper. PMIC is controlled with PWM control method in order to have high power efficiency at high current level. DTMOS with low on-resistance is designed to decrease conduction loss. The control parts in Buck converter, that is, PWM control circuits consist of a saw-tooth generator, a band-gap reference circuit, an error amplifier and a comparator circuit as a block. The Saw-tooth generator is made to have 1.2 MHz oscillation frequency and full range of output swing from ground to supply voltage(VDD:3.3V). The comparator is designed with two stage OP amplifier. And the error amplifier has 70dB DC gain and $64^{\circ}$ phase margin. DC-DC converter, based on Voltage-mode PWM control circuits and low on-resistance switching device, achieved the high efficiency near 95% at 100mA output current. And DC-DC converter is designed with LDO in stand-by mode which fewer than 1mA for high efficiency.

• Korean journal of applied entomology
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• v.40 no.3
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• pp.211-217
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• 2001

Field survey for Orius spp., predacious natural enemies of thrips pests, on several plants by beating or sweeping method revealed that O. sauteri, O. strigicollis, O. minutus, and O. nagaii habituated in open fields or in greenhouses of Korea. Among them, O. sauteri was the most dominant species at all areas (83.0~92.5%), followed by O. strigicollis and O. minutus. Especially, O. sauteri exclusively dominated on the economically important crops such as soybean, red pepper, and watermelon. On the other hand, O. strigicallis and O. nagaii occurred mainly on ornamental plants including chrysanthemum and rose and on rice, respectively, during summer-autumn season. The seasonal occurrence varied depending on the plant. Initial population of Orius spp. was first observed on white clover in late May, followed by on soybean, red pepper, an buck wheat in early June, indcating that movement of Orius spp. relates to the flowering time of the plant. Peak of Orius spp. abundance was found first in July and secondly in August or September. On white clover and buck wheat the first peak of abundance was one week earlier than on soybean and red pepper. Therefore, we suppose that wild plants such as white clover can serve as a reservoir for Orius spp. after overwintering.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.5
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• pp.477-483
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• 2011

Existing switching system that is one of the ways which are used for DC/DC power converter is classified to hard-switching system and resonant-soft-switching system, generally. Hard-switching system is inefficient because the power loss of the switching element is large when it is been to trun on or turn off. And resonant-soft-switching system have the defect that need to add the another reactor and capacitor that make it expensive and huge. This paper suggest the ZVS Full-Bridge power converter contrcution of novel switching system for the overcoming these shortcomings. In Suggested soft-switching system, the front of buck converter at diode current, switch is changing on and off at the part of full-bridge converter's zero voltage part. as the result that is possible to be ZVS excepting the reactor and capacitor. also to verify the reasonability of the isolated ZVS full-bridge DC/DC converter as previously suggested, we produced the 500[W] level DC/DC converter and enforced the simulation for Psim, and then it able to conform the superiority of the DC/DC converter's efficient.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.1
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• pp.45-53
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• 2013

Fuel cell power system is one of the most promising energy source for the alternative energy because it has unique advantages such as high energy density, no power drop during operation, and feasible to make compact size. However, due to very low response time, fuel cell is difficult to correspond to drastic load changes and start-up operation. For solving these problem, fuel cell power system must include energy storage device such as Li-Poly battery or super capacitor. Therefore, bi-directional DC-DC converter must be required for this storage device and fuel cell-PCS control. This paper presents a design and modeling of the bi-directional DC/DC converter. Firstly, we present modeling the boost and buck mode of the bi-directional converter through both PWM switch model and state space averaging technique. Secondly, in order to minimize output ripple and transient response overshoot, we have two identical DC-DC converters interleaved and adopt two-loop voltage-current controller. The proposed bi-directional DC-DC converter's modeling method and control design have been verified with computer simulation and experimentation.

• Journal of Distribution Science
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• v.9 no.2
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• pp.97-109
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• 2011

As a marketing vehicle to survive in intensified retailing competition, retailer brand development has been adopted by retailers in Korea. As evidence, the retailer brand share of a major retailer, Tesco Korea, has grown from 20% in 2007 to 22.8% in the first half of 2008. It means that retailers have provided more and more retailer brand foods for customers. With the growing accessibility to retailer brand foods, it would be expected that the number of retailer brand food claims will increase. Customers have increasingly exposed to a variety of marketing activities conducted by retailers. When buying the retailer brand foods, customers tend to be affected by marketing activities of retailers. Despite the fact that customers trust retailers and then, buy their brand foods, in case of food accidents caused by production process, customers have to seek compensation from a retailer brand supplier. Of course, a retailer tends to shift its responsibility to its suppliers. Accordingly, it is not easy for customers to solve food claims. The research, therefore, aims at exploring the relationship between the buying-decision processes of retailer brand customers and which side takes legal responsibility for food claims. To effectively achieve the research aim, the author adopted a quantitative and a qualitative research technique, in order to supplement the disadvantages of each method. Before field research, based on the developed research model, the author pre-tested questionnaire with 10 samples, amended, and handed out to 400 samples. Amongst them, 316 questionnaires are available. For a focus group interview, 9 participants were recruited, who are students, housewives, and full-time workers, aged from 20s to 40s. Through the focus group interview as well as the questionnaire results, it was found that most customers were influenced by a retailer or store image in a customer's mind, retailer reputation and promotional activities. Surprisingly, customers think that the name of a retailer is a more important factor than who produces retailer brand foods, even though many customers check a retailer brand supplier, when making a buying-decision. Rather than retailer brand suppliers, customers trust retailers. That is why they purchase retailer brands. Nevertheless, production-related food claims is not involved with retailers. In fact, it would be difficult for customers to distinguish whether a food claim is related to selling or manufacturing processes. Based on research results, from a customer perspective, the research suggests that the government should require retailers to take the whole responsibility for retailer brand food claims, preventing retailers from passing the buck to retailer brand suppliers. In case of food claims, in order for customers to easily get the compensation, it is necessary to reconsider the current system. If so, retailers have to fully get involved in retailer brand production stage, and further, the customer awareness of retailer brands will be improved than ever before. Retailers cannot help taking care of the whole processes of retailer brand development, because of responsibility. As a result, the process to seek compensation for food claims might become easier, and further, the protection of customer right might be improved.

• The Journal of Natural Sciences
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• v.8 no.2
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• pp.137-146
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• 1996

To increase the oxidation-resistance of graphite substrate, we have tried to form SiC film on its surface by Sol-Gel method. TEOS(Tetraethyl orthosilicate) and phenol resin have been used as silicon(Si) and carbon(C) sources, respectively. In order to know the effect of the TEOS Sol concentration on the forming of SiC film, we have taken 5 different $H_2O$/TEOS mol ratios of 2, 4, 6, 8 and 10. And the coating states of SiC on the graphite substrate have been analyzed with X-ray diffractometer and scanning electron microscope (SEM), and we have obtained about 5${\mu}m$, 12${\mu}m$, 7${\mu}m$, 7${\mu}m$ and 2 ${\mu}m$ as the thickness of SiC coating layers, respectively. For also knowing the oxidation resistance the SiC coated graphites at $1600^{\circ}C$ were heated again at $1000^{\circ}C$ under air atmosphere for 1 hr, and as a result we have received the weight losses of 26.17%, 20.97%, 17.28%, 21.73% and 28.13%, respectively.

• Research in Community and Public Health Nursing
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• v.15 no.4
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• pp.587-599
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• 2004

Purpose: The purpose of this study is to compare abdomen-fat rate, life style and social-support between normal weight women and obese women. Method: 304 women objectives from their 30 to 59 years of age were selected living in Je-chon city, Chung-Buck province and their height and weight were measured from April 1st to June 30th, 2003. Data were classified into low-weight group ($18.5kg/m^2$), normal-weight group ($18.5{\sim}22.9kg/m^2$), over weight group ($23{\sim}24.9kg/m^2$), and obese group ($25kg/m^2$) following the Korean Conference of Obesity, 2001. in which 119 people in the normal weight group and 91 people in the obese group, i.e. total 210 people were analyzed in sequence. Using SPSS Win 10.1 Program, frequency and percentile, and by ANOVA, $X^2-test$ and t-test were treated. Results: The average age of obese women was 46.68 distributing 40.7% of forties and 39.6% of fifties while normal-weight women were average 41.73-year old distributing 53.8% of forties and 34.5% of thirties, which revealed aged in obese women. The body fat rate of obese women averaged $37.52{\pm}4.17%$, in which 98.9% of obese women and 21.0% of normal weight women with a more than 30% of body-fat rate resulted in a higher body-fat rate in obese women. The waists of obese women averaged $88.37{\pm}8.22cm$, in which more than 85cm showed in obese women of 68.2% and normal weight women of 7.6% indicating a higher waist-fat rate in obese women. The abdomen-fat rate of more than 0.85 of waist vs hip-fat showed 74.7% in obese women and 58.4% in normal weight women, indicating a higher abdomen-fat rate in obese women. Obese women and normal weight women showed significant differences in education level, number of children, religion, menstrual status, and mother's weight. Especially, obese women ate hotter or saltier food than normal weight women preferring meat. However, no significant differences appeared in marital status, social economic status. occupation. eating habits. smoking. drinking and physical exercise. Social support levels showed a lower rate in obese women than in normal weight women, indicating a statistically significant difference (p<.05). Observing areas of social support, obese women showed lower rates in attachment/intimacy, social integrity, opportunity of foster and confidence in value except help and instruction, which indicated a statistically significant difference (p<.05). Social support for obese women showed significant differences in age, education level, social hierarchy, religion and menstrual status. Obese women were more negative than normal weight women in health recognition, indicating a statistically significant difference (p<.01). Normal weight women showed higher health recognition when provided high social support and significantly low (p<.01) health recognition when provided low social support. However, there was no significant difference in health recognition in obese women whether high or low social support was given. The health recognition of obese women showed significant differences in age, education level, social hierarchy, number of children, menstrual status, physical exercise, eating habits, eating taste and preference of food. Conclusion: Obese women showed elder than normal-weight women, higher body-fat rate and abdomen-fat rate, lower social support, and a tendency to more negative health recognition. Therefore, providing weight-control programs for the treatment of obesity and prevention of recurrence for obese women to prevent progressing to adult disease and promote a healthy life, we suggest that better eating habits and the encouragement of regular physical exercise should be included, as well as total approachment on change of health recognition and social support would be needed.