• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.472-473
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• 2006

Maghemite and hematite nanospheres were synthesized by using the Sol-gel technique. The structural properties of these nanosphere powders were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), and pore size distribution. Hematite phase shows crystalline structures. The mean particle size that resulted from BET and XRD analyses were 4.9 nm and 2 nm. It can be seen from transmission electron microscopy that the size of the particles are very small which is in good agreement with the FESEM and the X-ray diffraction. The BET and pore size method were employed for specific surface area determination.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.04a
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• pp.47-48
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• 2006

Electrowetting phenomenon is applied in the various field of technology. One of that is electrowetting display as a paper like electronic paper. Fast response and easy to express a color is goodness. In spite of that, the oil movement of the electrowetting display is irregular. So it doesn't look like uniform. Because of the above reason, electrowetting display using patterned electrode is made and the characteristic of oil movement is observed. Electrode and polymer wall is patterned by photo-lithography. We analyze the oil movement according to the variation of size and the position of etched electrode area.

• Journal of The Korean Society of Agricultural Engineers
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• v.58 no.6
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• pp.31-38
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• 2016

The purpose of this study was to assess nonpoint sources (NPS) pollution affected by liquid manure and regulating gate in a small agricultural watershed. The study area, which is a wide plain farmland, was operating by the Buyong regulating gate in order to maintain irrigation water level during irrigation period. Consequentially, runoff only occurs through the gate at each event in rainy season for avoiding farmland inundation. In addition, the usage ratio of liquid manure in the study area has been increased greatly since 2014. Discharge loads at the Hwaingsan bridge subwatershed were 1.2 times for T-N, 4-10 times for T-P, and 3-8 times for TOC compared with the Soyang watershed (control) during study period. The reason was that NPS pollutants from upper Gpeun and Sangri bridge subwatersheds, which are widely spraying with livestock liquid manure, were stack at this subwaterehd because of regulating gate in non-rainy seasons. A number of agricultural watersheds in Saemangeum watershed are affected by regulating gate and vigorous livestock activities so that substantial management schemes under controling regulating gate are needed for minimizing livestock related NPS.

• Animal cells and systems
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• v.8 no.2
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• pp.111-115
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• 2004

The epidermis of the mudskipper, Periophthalmus modestus, consists of three layers- the outermost layer, middle layer and stratum germinativum. Extensive fine blood capillaries are present near the superficial layer of epidermis and outermost layer in five fins and a sucking disc. The diffusion distance between the vascular capillaries and the surface of epidermis ranged from 3.6 to 10.9${\mu}$m: 3.6 ${\mu}$m in the sucking disc, 10.9 ${\mu}$m in the anal fin and 4.6 to 5.0 ${\mu}$m in the two dorsal fins. Rate of the surface area of respiratory epithelium, the surface area of the fine blood capillaries occupied per surface area of epidermis in 0.1mm, is 3.7 to 4.4% in two dorsal fins and 1.1% in the anal fin. The middle layer is simpler in structure consisting of small or voluminous cells swollen by epidermal cells, and this layer appeared web-like. Well-developed lymphatic spaces containing lymphocytes existed in the stratum germinativum. The five fins and sucking disc had no epidermal glands.

• Imaging Science in Dentistry
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• v.31 no.2
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• pp.121-127
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• 2001

Inflammatory pseudotumor was originally described in the lung, but recently has been recognized to occur in various sites. A 56-year-old female was referred to our department with a painless swelling of the right midfacial area since 3 months ago. Clinical examination showed non-specific intraoral findings, but asymmetric facial appearance and numbness of the right midfacial area. Plain radiographs and CT images showed aggressive destruction and irregular thickening of the right maxillary sinus wall, increased antral opacification, and destruction of the zygomatic arch. A relatively well-defined soft tissue mass occupied the right maxillary sinus, nasal cavity, zygoma, and infraorbital region. The soft tissue mass showed mild enhancement on CT. Radiographically, this lesion presented a rapidly enlarging mass demonstrating aggressive behavior, mimicking a malignant tumor. Histopathologic examinations showed plasma cells and inflammatory cells in variable fibrotic tissues and demonstrated positive reactivity for vimentin. No malignent changes could be found.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.68 no.1
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• pp.90-97
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• 2019

The charge redistribution digital-to-analog converter(CR-DAC) is often used for successive approximation register analog-to-digital converter(SAR ADC) that requiring low power consumption and small circuit area. However, CR-DAC is required 2 to the power of N unit capacitors to generate reference voltage for successive approximation of the N-bit SAR ADC, and many unit capacitors occupy large circuit area and consume more power. In order to improve this problem, this paper proposes SAR ADC using series capacitor DAC. The series capacitor DAC is required 2(1+N) unit capacitors to generate reference voltage for successive approximation and charges only two capacitors of the reference generation block. Because of these structural characteristics, the SAR ADC using series capacitor DAC can reduce the power consumption and circuit area. Proposed SAR ADC was designed in CMOS 180nm process, and at 1.8V supply voltage and 500kS/s sampling rate, proposed 6-bit SAR ADC have signal-to-noise and distortion ratio(SNDR) of 36.49dB, effective number of bits(ENOB) of 5.77-bit, power consumption of 294uW.

• Archives of Reconstructive Microsurgery
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• v.23 no.2
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• pp.70-75
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• 2014

Purpose: Soft-tissue reconstruction in the knee area requires thin, pliable, and tough skin. The range of motion of the knee also acts as a limitation in using only local flaps for coverage. The author has successfully used various perforator flaps for soft tissue reconstruction around the knee while preserving its functional and cosmetic characteristics. Materials and Methods: Out of the twenty patients assessed from April 2009 to March 2011, seven received anterolateral thigh perforator flaps, four received medial sural perforator island flaps, four received lateral supragenicular perforaor perforator flaps, and five received medial genicular artery flaps. The age of the patients ranged from 44 to 79 and the size of the defects ranged from $4{\times}5cm$ to $17{\times}11cm$. Fifteen of the twenty patients had histories of total knee replacement (TKR) surgery. Results: There were no flap losses in any of the twenty patients assessed. Two patients showed partial losses in the distal area of the flap, but were treated through careful wound care. One patient presented with pedicle adhesion at the drainage site from a past TKR, but it did not hinder the flap survival. Primary closure at the donor site was possible in nine patients, while split skin graft was necessary for the other 13. Conclusion: In soft tissue reconstruction of the knee, various perforator flaps can be used depending on the condition of the preoperation scar, wound site, and size. It also proved to provide better functional and cosmetic results than in primary wound closure or skin grafts.

• Journal of Veterinary Clinics
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• v.25 no.5
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• pp.370-378
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• 2008

The aim of this study was to investigate bioactivities of 50% Chitin - hydroxyapatite (Chitin-H) compound and 50% Chitosan - hydroxyapatite (Chitosan-H) compound in canine bone. Ten healthy mongrel dogs (1-5 years old, 1.7 - 6.9 kg) were used in this study. These compounds had been transplanted into bilateral femur separately, and then the changes of femur were observed through the examinations of hemato-biochemical profiles, radiology, and histological profiles for 42 days. After 3 weeks, expanded radiolucent changes were observed in both areas transplanted the compounds. After 6 weeks, the area transplanted the Chitin-H compound did not observe any changes of bony tissue, while the area inserted the Chitosan-H compound was observed changes of increasing bone formation. In histological examination, infiltrations of inflammatory cells and bone absorptions were observed at both transplanted sites. However an increasing of active osteogenesis was observed at the transplanted site with Chitosan-H compound. In conclusion, Chitosan-H compound had an function of active osteogenesis as compared with Chitin-H compound. From this study, it is indicated that Chitosan-H compound would be used in dogs with severe bone defect.

• The Journal of the Korean dental association
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• v.54 no.1
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• pp.49-56
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• 2016

An oro-antral fistula(OAF) is one of the most common complications after procedures at the maxillary posterior area. The purpose of this study was to introduce the closure of OAF with repair of the Schneiderian membrane. This case report includes three patients with OAF arising after dental surgery on molar region of maxilla. Under general anesthesia, fistulectomy was achieved in all three patients and the full thickness flap around OAF was raised. After removal of inflammatory tissue, the Schneiderian membrane was repaired with suture or application of fibrin sealant. Additional closures were then performed with a buccal fat pad flap and a buccal mucoperiosteal flap. All OAF in three patients enrolled in this study were closed successively without recurrence of fistula. Treatment of oroantral fistula using repair of the Schneiderian membrane is a good alternative option for patients with OAF accompanied by chronic maxillary sinusitis.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.153-153
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• 2010

Recently, to develop GaN-based light-emitting diodes (LEDs) with better performances, various approaches have been suggested by many research groups. In particular, using the patterned sapphire substrate technique has shown the improvement in both internal quantum efficiency and light extraction properties of GaN-based LEDs. In this paper, we discuss the influences of the direction of the hexagonal-structure arrays of lens-shaped patterns (HSAPs) formed on sapphire substrates on the crystal, optical, and electrical properties of InGaN/GaN multi-quantum-well (MQW) LEDs. The basic direction of the HSAPs is normal (HSAPN) with respect to the primary flat zone of a c-plane sapphire substrate. Another HSAP tilted by 30o (HSAP30) from the HSAPN structure was used to investigate the effects of the pattern direction. The full width at half maximums (FWHMs) of the double-crystal x-ray diffraction (DCXRD) spectrum for the (0002) and (1-102) planes of the HSAPN are 320.4 and 381.6 arcsecs., respectively, which are relatively narrower compared to those of the HSP30. The photoluminescence intensity for the HSAPN structure was ~1.2 times stronger than that for the HSAP30. From the electroluminescence (EL) measurements, the intensity for both structures are almost similar. In addition, the effects of the area of the individual lens pattern consisting of the hexagonal-structure arrays are discussed using the concept of the planar area fraction (PAF) defined as the following equation; PAF = [1-(patterns area/total unit areas)] For the relatively small PAF region up to 0.494, the influences of the HSAP direction on the LED characteristics were significant. However, the direction effects of the HSAP became small with increasing the PAF.