• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.7
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• pp.486-493
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• 2003

Schottky type A $l_{0.33}$G $a_{0.67}$N ultraviolet photodetectors were fabricated on the MOCVD grown AlGaN/ $n^{＋}$-GaN and AlGaN/AlGaN interlayer/ $n^{＋}$-GaN structures. The grown layers have the carrier concentrations of -$10^{18}$, and the mobilities were 236 and 269 $\textrm{cm}^2$/V.s, respectively. After mesa etching by ICP etching system, the Si3N4 layer was deposited for passivation between the contacts and Ti/AL/Ni/Au and Pt were deposited for ohmic and Schottky contact, respectively. The fabricated Pt/A $l_{0.33}$G $a_{0.67}$N Schottky diode revealed a leakage current of 1 nA for samples with interlayer and 0.1$\mu\textrm{A}$ for samples without interlayer at a reverse bias of -5 V. In optical measurement, the Pt/A $l_{0.33}$G $a_{0.67}$N diode with interlayer showed a cut-off wavelength of 300 nm, a prominent responsivity of 0.15 A/W at 280 nm and a UV-visible extinction ratio of 1.5x$10^4./TEX>.

• Journal of the Korean Vacuum Society
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• v.15 no.2
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• pp.201-208
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• 2006

Optical characteristics of InGaAs quantum dot (QD) laser structures with an Al native oxide (AlOx) layer as a current-blocking layer were studied by means of photoluminescence (PL), PL excitation, and spatially-resolved micro-PL techniques. The InGaAs QD samples were first grown by molecular-beam epitaxy (MBE), and then prepared by wet oxidation and thermal annealing techniques. For the InGaAs QD structures treated by the wet oxidation and thermal annealing processes, a broad PL emission due to the intermixing effect of the AlOx layer was observed at PL emission energy higher than that of the non-intermixed region. We observed a dominant InGaAs QD emission at about 1.1 eV in the non-oxide AlAs region, while InGaAs QD-related emissions at about 1.16 eV and $1.18{\sim}1.20eV$ were observed for the AlOx and the SiNx regions, respectively. We conclude that the intermixing effect of the InGaAs QD region under an AlOx layer is stronger than that of the InGaAs QD region under a non-oxided AlAs layer.

• Clinical and Experimental Pediatrics
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• v.50 no.11
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• pp.1085-1090
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• 2007

Purpose : Radiofrequency catheter ablation (RFCA) has become an effective therapeutic modality for treating pediatric tachyarrhythmias. Using conventional RFCA catheters, ablation of parahisian accessory pathways may be difficult and have high risk for heart block. We reviewed the efficacy and complications of the RFCA in children and adolescent with arrhythmias including parahisian accessory pathways. Methods : We studied 48 patients (aged 2 years to 20 years) who had undergone RFCA from August 2003 to March 2007. We reviewed clinical findings, electrophysiologic studies, RFCA data, complications, and follow-up results of the patients. Results : Mean age of the patients was 13.1 years. Numbers and types of arrhythmias (age, acute success rate) were as follows: 19 WPW syndrome including 5 parahisian accessory pathways ($13.7{\pm}4.6yr$, 18/19), 11 atrioventricular reentrant tachycardia with concealed bypass tract ($12.3{\pm}5.0yr$, 10/11), 13 atrioventricular nodal reentrant tachycardia ($12.6{\pm}4.4yr$, 13/13), 4 atrial flutter ($13.0{\pm}7.4yr$, 3/4), and 1 ventricular tachycardia (20 yr, 1/1). Associated cardiac structural lesion was not detected in 48 patients. The recurrence rate was 6.5%, and the final success rate was 93.8%. Conclusion : These results suggest that RFCA is a highly effective treatment method in children and adolescent with tachyarrhythmia.

• The Korean Journal of Physiology
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• v.2 no.1
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• pp.79-88
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• 1968

For the purpose of assessing the influence of the mamillary bodies on the general activity and stress response, mamillary body·damaged rats(mamillary body group), operated control rats, and normal control animals were prepared and 2 experiments were carried out. The mamillary bodies. were damaged electrolytically by passing 0.3 ma d.c. current through stereotaxically implanted electrodes. The operated control group received the same treatment except passage of current. In the 1st experiment, each subject belonging to the mamillary body group .(9 rats) or the operated control group (13 animals) was put individually into an activity cage across which an infrared beam traversed. The number of beam interruptions by the movement of the subject in the cage was. recorded hourly for 48 hours and was regarded as an index of general activity. In the 2nd experiment, each of the mamillary body group (52 animals), the operated control group (45 rats), and the normal control group (37 animals) was further divided into 4 subgroups and the adrenal ascorbic acid content of one of the 4 subgroups was measured before, another subgroup immediately after, a third subgroup 2 hours after, and the remaining subgroup 4 hours after termination of a cold stress ($-10^{\circ}C$ for 1 hour). Following results were obtained: 1. Though the total activities in 48 hours of the mamillary body group and the operated control group were not significantly different, the activities of the malnillary body group for a few hours. at the beginning of the measurement and also in the evenings of both the 1st and the 2nd experimental days were significantly greater than those of the operated control group. 2. Judged by the significant reduction in adrenal ascorbic acid content, the stress response of the mamillary body group was as marked as that of the operated control or the normal control group-immediately after termination of cold exposure. Recovery from the stress was accelerated significantly in the mamillary body group and insignificantly in the operated control group compared with that of the normal control group, the intergroup difference of the former two groups being insignificant. It was inferred from the above results that the mamillary bodies may exert an inconspicuous inhibitory influence upon the central mechanism of general activity, and that the mamillaryies bodies may not be the main seat of the stress mechanism, although more works are desirable to confirm the results.