• Journal of the Korean Institute of Telematics and Electronics
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• v.4 no.1
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• pp.13-21
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• 1967

A low pass filter is synthesized with R, C and negative impedance converters(NIC). The filter has a 4-th order elliptic function, which gives best magnitude approximation with equi-ripple characteristics both in pass and stop band. And experimental investigations have been made on the effect of the anticipated deviation of the NIC conversion factor and of possible loaded operation. Through the study, it has been cocluded that: 1. For minimum pole-zero sensitivity with respect to the NIC conversion factor, the network of a parallel RC-NIC configuration is preferable and the Horowitz polynomial decomposition method is applied in the synthesis procedure. 2. A few percentage variation of the NIC conversion factor changes the frequency and amplitude characteristics of the filter by nearly negligible amount. 3. With a load resistance below the critical value, the filter turns into an oscillator.

• Journal of the Korean Ceramic Society
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• v.55 no.4
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• pp.307-324
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• 2018

Rechargeable lithium-ion batteries (LIBs) have been rapidly expanding from IT based applications to uses in electric vehicles (EVs), smart grids, and energy storage systems (ESSs), all of which require low cost, high energy density and high power density. The increasing demand for LIBs has resulted in increasing price of the lithium source, which is a major obstacle to wider application. To date, the possible depletion of lithium resources has become relevant, giving rise to the interest in Na-ion batteries (NIBs) as promising alternatives to LIBs. A lot of transition metal compounds based on conversion-alloying reaction have been extensively investigated to meet the requirement for the anodes with high energy density and long life-time. In-depth understanding the electrochemical reaction mechanisms for the transition metal compounds makes it promising negative anode for NIBs and provides feasible strategy for low cost and large-scale energy storage system in the near future.

• Journal of Electrochemical Science and Technology
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• v.13 no.1
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• pp.32-53
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• 2022

Although lithium-ion batteries are currently the most reliable power supply system for various mobile applications, further improvement in energy density is still required as the need for batteries in large energy-consuming devices is rapidly growing. However, in the anode, the most widely commercialized graphite-based anode materials almost face theoretical limitations. In addition, sodium-ion batteries have been actively studied to replace expensive charge carriers with cheaper ones. Accordingly, conversion-based materials have been extensively studied as high-capacity anode materials in both lithiumion batteries and sodium-ion batteries because their theoretical capacity is twice or thrice higher than that of insertion-based materials. This review will provide a comprehensive understanding of conversion-based materials, including basic charge storage behaviors, critical drawbacks that should be overcome, and practical material design for high-performance.

• Journal of Environmental Science International
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• v.31 no.12
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• pp.1135-1138
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• 2022

This study was conducted to evaluate the effects of sipjeondaebo-tang by-product powder on the growth performance of broilers. A total of 120 broiler chicks (Arbor acres) at 0 days old were assigned to one of two treatments with three replications: control and 1% sipjeondaebo-tang by-product powder. Weight gain at 3 weeks and feed intake at 5 weeks were significantly (p<0.05) influenced by the sipjeondaebo-tang by-product powder treatments. However, there were no significant differences in the feed conversion ratio between treatments as a function of treatment time (p>0.05). Overall, weight gain and the feed conversion ratio were slightly greater for the sipjeondaebo-tang by-product powder treatment than the control treatment. It was concluded that sipjeondaebo-tang by-product powder may be an appropriate source of feed additive, without any negative effects on the growth performance of the broilers.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.276-280
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• 2001

In this paper, an approach to the design of negative impedance stabilizing controllers for PWM DC/DC converters that are used in DC switching. power supplies with constant power loads is presented. The control approach is based on the feedback linearization technique. Because of the negative impedance destabilizing characteristics of constant power loads, classical linear control methods have stability limitations around the operating points. However, the proposed stabilizing technique improves large-signal stability and dynamic responses. The proposed controllers are simulated and their responses under different operations are studied. Stability of the control technique is also verified using the second theorem of Lyapunov.

• The Journal of Information Systems
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• v.30 no.2
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• pp.79-103
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• 2021

Purpose Based on consumers' economic, psychological, self-development and conversion costs, this study discusses the relationship between consumers' negative attitude to their shadow work during the course of using self-service in unmanned supermarkets and their behavior. Design/methodology/approach Along with the Hirschman(1970)'s EVLN(Exit, Voice, Loyalty, and Neglect) reviewed, the proposed model of this study is based on the S-O-R model(Mehrabian and Russel, 1974) and mental accounting theory(Thaler, 1999), having empirical validation. Findings In the process of visits and consumption in unmanned supermarkets, increasing economic and psychological benefits can effectively reduce consumers' negative attitudes towards shadow work. In addition, the increase in switching costs will also effectively reduce consumers' negative attitudes towards shadow work. When shadow work holds a negative attitude, all the three kinds of actions will occur. Unmanned supermarket operators use consumers to create value while giving a certain return to them, which is conducive to the sustainable development of unmanned supermarket enterprises.

• Journal of Educational Research in Mathematics
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• v.17 no.1
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• pp.1-31
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• 2007

Negative numbers have been one of the most difficult mathematical concepts, and it was only 200 years ago that they were recognized as a real object of mathematics by mathematicians. It was because it took more than 1500 years for human beings to overcome the quantitative notion of numbers and recognize the formality in negative numbers. Understanding negative numbers as formal ones resulted from the Copernican conversion in mathematical way of thinking. we first investigated the historic and the genetic process of the concept of negative numbers. Second, we analyzed the conceptual fields of negative numbers in the aspect of the additive and multiplicative structure. Third, we inquired into the levels of thinking on the concept of negative numbers on the basis of the historical and the psychological analysis in order to understand the formal concept of negative numbers. Fourth, we analyzed Korean mathematics textbooks on the basis of the thinking levels of the concept of negative numbers. Fifth, we investigated and analysed the levels of students' understanding of the concept of negative numbers. Sixth, we analyzed the symbolizing process in the development of mathematical concept. Futhermore, we tried to show a concrete way to teach the formality of the negative numbers concepts on the basis of such theoretical analyses.

• The Korean Journal of Pharmacology
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• v.10 no.2
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• pp.25-29
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• 1974

The present clinical trial was performed to evaluate the anthelminthic effect and tolerance of Oxantel pamoate, a new antiwhipworm agent, in the treatment of T. trichiurus infection. Oxantel pamoate oral suspension was administered as a sing1e dose of 10 mg per kg. body weight to a total of 46 T. trichiurus infected cases selected out of 64 positives, by examining 89 fecal specimens collected from the soldiers and in-patients of xx Armed Forces General Hospital. For the evaluation, the negative conversion rate (cure rate) and the egg reduction rate were assessed 22 days after the treatment. The result obtained were as follows: 1. The prevalence rate of T. trichiurus infection in this study was 71.9%, while the mean E.P.G. of 46 treated cases was 126. 2. The egg negative conversion rate was 91.3%, and 98.4% of egg reduction rate was obtained. 3. From the observation of 107 worms expelled during 3 consecutive days after the treatment, it was known that sex ratio of male and female was about 1 : 2 and that average worm burden per capita was 2.3. 4. In all treated cases, the medication was readily accepted and well tolerated. On the hemograms, urinalysis and liver function tests, no significant differences were noted before and after the drug administration. There was also no detectable objective and subjective side effect.

• Restorative Dentistry and Endodontics
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• v.20 no.1
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• pp.33-54
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• 1995

The degree of conversion of composite resin was known to have influence on the mechanical properties of composite materials such as hardness, strength, wear resisitance, dimensional and color stability. Also unreacted monomer was reported to be harmful to the pulp. So the degree of conversion was a very important factor in the success of composite resin restorations. In recent, the dual cure resin cement was developed with the advocations that it could increase the curing rates in the sites where the curing ligt could not reach. Moreover many manufactors added some adhesive components in the resin cement. This study was undertaken to observe the effects of curing depth and light curing times on the degree of conversion of dual cure resin cements. CR INLAY CEMENT, DUAL CEMENT and OPTEC BOND, by the Fourier transform Infrared analysis, changing the curing depth 1mm, 2mm and 3mm, and varying the light curing time 20 seconds, 40 seconds and 80 seconds at each depth. The cytotoxicity of dual cure resin cements was tested by the in vitro MTT method using L929 cell. The results was evaluated and compared statistically. The results were obtained as follows : 1. The dual cure resin cements reavealed various degree of conversion, CR INLAY CEMENT and DUAL CEMENT had a tendency to be more reactive to the light cure and OPTEC BOND was a more chemical one. 2. CR INLAY CEMENT and DUAL CEMENT showed the lowest degree of conversion in 2 mm depth, and in 3mm depth the degree of conversion increased, which were due to the chemical cure of dual cures, but OPTEC BOND showed decreasing degree of conversion with increasing curing dept h and all experimental groups showed lower degree of conversion than CHEMICAL group which cured in dark room with no light, so the weak light-curing of dual cure resin cement prevented the chemical cure. (P<0.05) 3. CR INLAY CEMENT and DUAL CEMENT showed increasing degree of conversion in 1 mm and 3 mm, according to the increasing cure times, but in 2 mm depth the degree of conversion decreased with increasing light-curing times and OPTEC BOND showed contrary tendency, but there was no ststistical importance in the differences among the experimental group.(P>0.05) 4. The optical density by MTT assay of extractions of CR INLAY CEMENT, DUAL CEMENT and OPTEC BOND revealed no statitically important differences comparing with optical density of negative control.(P>0.05) 5. CR INLAY CEMENT showed a tendency of increaing cytotoxicity with days and DUAL CEMENT and OPTEC BOND showed higher cytotoxicity in 2 days than in 4 days, but there was no statistical importance in the differences.(P>0.05).

• Journal of Korea Society of Digital Industry and Information Management
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• v.4 no.4
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• pp.21-29
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• 2008

The DC characteristics of GaAS Gunn diode are investigated as a preliminary study on the planar grade gap injector GaAs Gunn diode which is the transferred electron device with high output power and dc-rf conversion efficiency. The Gunn devices we fabricated were confirmed to have the DC characteristics of negative differential resistance(NDR). We discussed the nature of the NDR effect, including the electron intervalley transfer; the NDR effect was examined for six different cathode radii.