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Critical Current Equalization via Neutral Lines in a Transformer-Type SFCL
Hyo-Sang Choi,Yong-Sun Cho IEEE 2008 IEEE transactions on applied superconductivity Vol.18 No.2
<P>In order to increase the capacity of the superconducting fault current limiter (SFCL), serial and parallel connections of the superconducting units are necessary. The resistive-type SFCL with serial and parallel connections has the unbalance of power burden because of the difference of critical current between the superconducting units. The transformer-type SFCL using a neutral line consists of a primary coil and several secondary coils with the superconducting units. Because the neutral line is connected with the secondary coils in the SFCL, it induces the simultaneous quench from compulsive current distribution in the superconducting units. The simultaneous quench enables the power burden between the superconducting units to be distributed equally. The neutral line also induces the equal voltage distribution between the superconducting units due to the equal turn's ratio of the secondary coil. In conclusion, the increase of the capacity in the transformer-type SFCL could be achieved easily through the application of the neutral line between the secondary coils and the superconducting units.</P>
Effects of the isoflavone puerarin and its glycosides on melanogenesis in B16 melanocytes
Choi, Young-Mi,Jun, Hee-jin,Dawson, Kevin,Rodriguez, Raymond L.,Roh, Mi Ran,Jun, Jungae,Choi, Chung-Hyo,Shim, Jae-Hoon,Lee, ChoongHwan,Lee, Sang Jun,Park, Kwan-Hwa,Lee, Sung-Joon Springer-Verlag 2010 European food research and technology Vol.231 No.1
Endosulfan Plant Uptake Suppression Effect on Char Amendment in Oriental Radish
Choi, Geun-Hyoung,Lee, Deuk-Yeong,Seo, Dong-Cheol,Kim, Leesun,Lim, Sung-Jin,Ryu, Song-Hee,Park, Byung-Jun,Kim, Jeong-Han,Kim, Jin Hyo Springer Netherlands 2018 Water, Air and Soil Pollution Vol.229 No.1
<P>Persistent organic pollutants (POPs) immobilization in farm land is an important issue to solve the residue in crop, and char has been considered for the remediation. In here, three commercially available chars like powdered oak char (POC), granulated oak char (GOC), and rice husk char (RHC) including powdered activated carbon (PAC) were investigated for their potential to adsorb and immobilize endosulfan in the soil. The maximum adsorption capacities (mg g(-1)) of the applied chars as POC, GOC, and RHC were 714.8, 322.6, and 181.8, respectively, and the capacity of POC was similar with PAC (713.8). In addition, the pore volume (0.138 cm(3) g(-1)) and the surface area (270.3 m(2) g(-1)) of POC were over 3-fold higher than GOC and RHC. The bioconcentration factor (BCF) reducing effect of alpha-, beta-endosulfan, and endosulfan sulfate in oriental radish (Raphanus sativus var. sativus) was investigated by amendment of three commercially available chars to the contaminated soils. The BCF of total endosulfan was 0.025 in the radish root. POC treatments effectively suppressed the endosulfan uptake (BCF 0.002). However, GOC and RHC showed little BCF reducing effect of endosulfan in radish.</P>
High Incidence of Bell’s Palsy After Mastoidectomy: A Longitudinal Follow-up Study
Choi, Hyo Geun,Sim, Songyong,Hong, Sung Kwang,Park, Su-kyoung,Lee, Hyo-Jeong,Chang, Jiwon Lippincott Williams Wilkins 2017 Otology & Neurotology Vol.38 No.10
OBJECTIVE:: The objective of this study was to compare the prevalence of Bell’s palsy in participants who underwent mastoidectomy (to treat chronic otitis media) and nonmastoidectomy participants (control). METHODS:: Using the national cohort study from the Korean Health Insurance Review and Assessment Service, mastoidectomy patients (2,045) and control participants (8,180) were matched 1:4 for age, sex, income, and region of residence. The prevalence of Bell’s palsy in both the groups was measured from 0 to 10 years postoperation. RESULTS:: In a sample of 1,025,340 Korean individuals, 7,070 were diagnosed or treated with Bell’s palsy between 2002 and 2013; the annual incidence of Bell’s palsy was 0.057%. The overall prevalence of Bell’s palsy was three times higher in the mastoidectomy group (1.27%) than control group (0.49%) (p < 0.001). The prevalence of Bell’s palsy was different between the two groups in postoperative 0 year: 0.78% for the mastoidectomy group versus 0.01% for the control group (p < 0.001). CONCLUSION:: Although we could not verify the laterality, the prevalence of Bell’s palsy was increased in chronic otitis media patients treated with mastoidectomy patients compared with controls, especially within a year after surgery.
Choi Hyo-Sang,Sang-Yong Park 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.2
The direct current (DC) grid range is rapidly expanding according to the increase of power generation capacity for the DC demands. In order to stably operate the DC grid system, we need a suitable DC circuit breaker for DC characteristics. We propose the superconducting arc-induction type DC circuit breaker. Lorentz’s force is occurred by the strong magnetic fi eld is occurring by the superconducting magnet and the arc is occurring by the between Anode and Cathode. If we exactly control that, the effi ciency of the arc-induction can be higher. In this paper, the electric fi eld and according to the cut-off operation of the superconducting arc-induction type DC circuit breaker were analyzed. It is very important because the electric fi eld and Lorentz force are an indicator for confi rming the movement of the arc caused by the opening contacts. As a result, we confi rmed that the Lorentz force calculated from the FEM showed a maximum increase ratio of 1101 times.
Choi, Jin Woo,Lee, Sang Yub,Kim, Jong Hyo,Jin, Hyeongmin,Lee, Jaewon,Choi, Young Hun,Lee, Hyeon-Kyeong,Park, Jae Hyung Raven Press 2018 Journal of computer assisted tomography Vol.42 No.2
OBJECTIVE: The purpose of this study was to evaluate a gonadal shield (GS) and iterative metallic artifact reduction (IMAR) during computed tomography scans, regarding the image quality and radiation dose. METHODS: A phantom was imaged with and without a GS. Prospectively enrolled, young male patients underwent lower extremity computed tomography venography (precontrast imaging without the GS and postcontrast imaging with the GS). Radiation dose was measured each time, and the GS-applied images were reconstructed by weighted filtered back projection and IMAR. RESULTS: In the phantom study, image artifacts were significantly reduced by using IMAR (P = 0.031), whereas the GS reduced the radiation dose by 61.3%. In the clinical study (n = 29), IMAR mitigated artifacts from the GS, thus 96.6% of the IMAR image sets were clinically usable. Gonadal shielding reduced the radiation dose to the testes by 69.0%. CONCLUSIONS: The GS in conjunction with IMAR significantly reduced the radiation dose to the testes while maintaining the image quality.