• Journal of the Korean Vacuum Society
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• v.17 no.6
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• pp.523-527
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• 2008

GaAs/AlGaAs based quantum cascade lasers were fabricated with two different types of i) the shallow mesa type which was etched up to above active region and ii) the deep mesa type which was etched through active region. While the threshold current density of shallow mesa type was $26-32\;kA/cm^2$, the one of deep mesa type was reduced drastically up to $13\;kA/cm^2$. Such lowered threshold current density at deep mesa type attributed to the reduction of current loss to the lateral directions.

• Proceedings of the Korean Magnestics Society Conference
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• 2008.12a
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• pp.133.2-133.2
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• 2008

• Journal of the Korean Vacuum Society
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• v.17 no.6
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• pp.555-559
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• 2008

Junction temperature of quantum dot laser diodes is investigated by utilizing forward voltage-temperature method. In the case of ridge type laser diodes with deep mesa the increasing rate of junction temperature to current is about 0.05 K/mA, while in the case of shallow mesa the increasing rate is about 0.07 K/mA. It is explained that the relatively low increasing rate in the deep mesa results from the heat expansion to the lateral direction of mesa.

• Proceedings of the Korean Magnestics Society Conference
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• 2007.05a
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• pp.233.2-233.2
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• 2007

• Korean Journal of Optics and Photonics
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• v.10 no.6
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• pp.518-523
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• 1999

In thi, study, we made experiments to fonn a mesa shape by meltback method with various concentration of solutions and found that unsaturated (20%) InGaAsP (1.55 !-tm) solution at a growth temperature was the most suitable for the formation of a mesa ,hape on the wafer which has an InGaAsP active layer and an InP cap layer on an n-InP substrate. It was difficult to form a proper mesa shape for the fabrication of PBH-LDs only by the meltback method; therefore, we fabricated PBH-LDs by forming the mesa shape with the meltback method after wet etching and by growing a current-blocking layer successively. As the electrical and optical charaleri,tiecs of MQW-PBH-LDs fabricated by above methods, when the cavity length was $300{\mu}m$, the threshold current was about 10 mA, internal quantum efficiency 82%, internal loss $9.2cm^{-1}$, and characteristic temperature was 65 K at $25~45^{\circ}C$ and 42 K at $45~65^{\circ}C$. /TEX>.

• Proceedings of the Korean Magnestics Society Conference
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• 2007.05a
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• pp.236.2-236.2
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• 2007

• Transactions of the Society of Information Storage Systems
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• v.3 no.2
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• pp.86-93
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• 2007

In this paper we explain why future probe storage systems will use patterned media. As a model system, magnetic patterned media will be discussed, even though their data density is limited to about $7Tbit/in^2$. The first results on magnetic probe storage on patterned media are presented, and the problem of switching field distribution is discussed in detail. Finally we will present the first steps into two-dimensional coding for patterned media.

• The Journal of Korea Robotics Society
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• v.10 no.2
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• pp.90-95
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• 2015

The main goal of e-learning systems is just-in-time knowledge acquisition. Rule-based e-learning systems, however, suffer from the mesa effect and the cold start problem, which both result in low user acceptance. E-learning systems suffer a further drawback in rendering the implementation of a natural interface in humanoids difficult. To address these concerns, even exceptional questions of the learner must be answerable. This paper aims to propose a method that can understand the learner's verbal cues and then intelligently explore additional domains of knowledge based on crowd data sources such as Wikipedia and social media, ultimately allowing for better answers in real-time. A prototype system was implemented using the NAO platform.

• Journal of IKEEE
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• v.17 no.4
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• pp.428-433
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• 2013

In this study, an 4H-SiC Trench MOS Barrier Schottky (TMBS) rectifier which utilizes the trapezoid mesa structure and the upper half of the trench sidewall is proposed to improve the forward voltage drop and reverse blocking voltage concurrently. The proposed 4H-SiC TMBS rectifier reduces the forward voltage drop by 12% compared to the conventional 4H-SiC TMBS rectifier with the tilted sidewall and improves the reverse blocking voltage by 11% with adjusting the length of the upper sidewall. The Silvaco T-CAD was used to analyze the electrical characteristics.

• Clinical and Experimental Reproductive Medicine
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• v.22 no.2
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• pp.143-148
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• 1995

To present and assess the efficacy of combination of microsurgical epididymal sperm aspiration(MESA) and intracytoplasmic sperm injection(ICSI) for the treatment of infertility due to unreconstructable obstructive azoospermia or congenital bilateral agenesis of vas deferens (CBAVD), MESA was performed in the 45 husbands ( 16 CBAVD, 29 unreconstructable genital tract obstruction), followed by ICSI of oocytes recovered from the wives hyperstimulated by GnRH agonist in combination with hMG and FSH. Cleaving embryos were transfered to the uterine cavity or follopian tube(ZIFT) 18 or 24 hours after ICSI procedure. In 45 cycles of MESA, 492 oocyte complexes were recovered. ICSI was carried out on 355 metaphase II oocytes and 226 oocytes (63.7%) showed normal two pronucleus fertilization. After 198 embryos were transferred in 43 cycles, an average of 5 per cycle, 20 patients presented a positive HCG and intrauterine pregnancy was confirmed by US. So, the clinical ongoing pregnancy rate per transfer was 46.5%. Until now, 8 patients have given birth to 9 babies, 5 male and 4 female, including 1 twin. The babies were all healthy except 1 twin female baby. There was 1 miscarriage at 7 weeks and chromosomal study of abortus revealed as 45X, monosomy. These results suggested that it was possible to achieve high normal fertilization and pregnancy rate by ICSI using epididymal sperm.