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폐굴껍질을 산성토양 적용시 토양의 화학적 특성변화에 관한 기초 연구
임진희,문종익,김성우,성낙창,이영형,윤태경 동아대학교 환경문제연구소 1999 硏究報告 Vol.22 No.2
Oyster shell has caused environmental problems in the coast. But it is possible to be used as an acidic soil amendment because it is the alkalic material of pH 9.0. In order to evaluate the utility of the crushed oyster shell as a soil amendment, acidic sandy loam soil was amended with it and then Chinese cabbages were cultivated in pots. The amount of the oyster shell was ⅰ)none, ⅱ)0.5kg/㎥, ⅲ)1.0kg/㎥, ⅳ)1.5kg/㎥, ⅴ)2.0kg/㎥ and ⅵ)2.3kg/㎥. The particle size of oyster shell consists of 34.88% of 40∼100mesh and 14.98% of larger than 100 mesh. It increased pH and the contents of available P₂O_(5) and SiO₂ and exchangeable Ca in used soil The application of oyster shell also increased the height and diameter of Chinese cabbages.
황순호,임형업,우성주,김신규 慶熙大學校 1994 論文集 Vol.23 No.-
We have synthesized protoberberine derivatives from tetra- hydroberberinium perchlorate. On quaternization of a several protoberberine derivativese with methyl iodide, the formation of the cis methiodides the corresponding trans methiodides increased according to the order of the bulkiness of the 14-substituent as H>CH₃>CN. The N-methyl signal of the cis 14-substituted quinolisidine methiodides was conformed to appear at higher field than those of the corresponding trans methiodides except for the 14-cyano methiodides in their NMR specta.
Woo-Seok Kim,Ok-Bae Hyun,Chung-Ryul Park,Seong-Woo Yim,Seung-Duck Yu,Seong-Eun Yang,Hee-Sun Kim,Hye-Rim Kim IEEE 2012 IEEE transactions on applied superconductivity Vol.22 No.3
<P>This paper presents the results of short-circuit tests with a 22.9 kV hybrid superconducting fault current limiter (SFCL) on the KEPCO test grid. The hybrid SFCL we used for the test had suffered from lots of field tests including a long term operation and it is still in working order. We have already proved that the SFCL showed high reliability as well as feasibility through a long term operation and short-circuit tests performed before. In this paper, we tried to study a dynamic characteristics of the same SFCL on the distribution power grid through short-circuit tests with a circuit breaker and a reclosing relay. An artificial fault generator (AFG) was used to generate fault currents in the KEPCO power test center. The two objectives of the tests are (1) verifying a precise reaction of the SFCL to reclosing operation and (2) a study for protection coordination with SFCL. The test results showed that the SFCL worked precisely with a fast recovery of the superconducting elements when we applied a one-time reclosing operation with the interval of 0.6 second. We also suggested a proper manipulation of the coordination of the protection system in distribution networks with the SFCL in the paper.</P>
Analysis on Current Distribution in Bi-2223/Ag Tapes with Applied Alternating Over-critical Current
Yim, Seong-Woo,Kim, Hye-Rim,Hwang, Si-Dole The Korean Institute of Electrical and Electronic 2004 전기전자재료학회논문지 Vol.17 No.6
Generally Bi-2223/Ag tapes have a broad S/N transition region and their sheath is a good electric conductor. In this study, the current distribution between superconductor and metal sheath in HTS tapes were investigated. AC with its peak value above 10 times $I_{c}$ was applied to HTS tapes for around 6 cycles and V-I characteristics were measured. Using the resistance of the sheath and V-I curves, the current distribution between superconductor and metal sheath was calculated. When 150 $A_{p}$ was applied, more than 2/3 of the current flows through superconductor. However, in the case of 304 $A_{p}$, most of the applied current came to flow through the metal sheath at the 6th cycle.e.e.e.
Quench Development Due to External Magnetic Field in HTS Cable Conductor Transporting AC Current
Seong-Woo Yim,Sung-Hun Lim,Song-Ho Sohn,Si-Dole Hwang,Sung-Chae Yang Institute of Electrical and Electronics Engineers 2006 IEEE transactions on applied superconductivity Vol.16 No.2
<P>In this study, a prototype HTS cable conductor with 1 layer of 10 Bi-2223/Ag tapes was fabricated and the quench development due to the influence of external magnetic fields was investigated. Firstly, AC current whose peak value amounts around two times critical current was applied to the HTS cable conductor. From the experiments, the influence of self field was considered to be small enough not to affect the transporting characteristics. Secondly, external magnetic fields of 50 and 100 mT were applied to the HTS cable conductor transporting AC current. In this case, due to the directional dependence of Bi-2223/Ag tapes on magnetic field, various magnitudes of voltages were detected in each strand. Finally, the quench development with the magnitude of the applied external magnetic field was analyzed</P>
Application of Resistive Type SFCL to Protect Bi-2223/Ag Tape Against AC Over-Currents
Seong-Woo Yim,Song-Ho Sohn,Si-Dole Hwang,Ok-Bae Hyun,Sung-Hun Lim,Kishio, K. IEEE 2006 IEEE transactions on applied superconductivity Vol.16 No.2
<P>Based on the electrical behavior of Bi-2223/Ag tape in transient state, the possibility of SFCL application was investigated as a fundamental study for the protection of HTS power apparatus. For the experiments, the Bi-2223/Ag tape having the critical current of 56 A and the resistive type SFCL fabricated using three elements of YBCO thin films were examined. When the applied current exceeds the rated current of the SFCL, the current was limited to sufficiently low level, however, higher than 40 Vrms was not allowed considering power density of SFCL. On the other hand, as a method to increase the power density, a shunt resister across the SFCL was adopted to increase the allowed power density. In this case, the results showed that the over current was limited below the safe range for HTS tape and the SFCL was safe, although 100 V<SUB>rms</SUB> was applied to the circuit. In conclusion, the switching power capacity of a SFCL could be increased by using a shunt resistor, and HTS tape could be protected safely within the quench margin</P>