• The Journal of Korean Academy of Prosthodontics
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• v.53 no.1
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• pp.66-73
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• 2015

Alveolar bone loss and deformation can be a risk factor in removable prosthetic restoration treatment for partially or fully edentulous patients. The use of implants to solve this problem could improve the support, retention and stability of removable restoration. Attachments used in implant overdenture are versatile. The attachment should be selected according to the patients' conditions. Milled bar has been chosen when readymade bar could not be used because of the narrow distance between implants or firm stability and support of supra-structure were needed. Milled bar design is able to provide cross arch stabilization and comfortability to patients. However, it needs skilled laboratory procedures. Recently, the fabrication of milled bar has become simple and its suitability has been improved through the development of CAD/CAM system. In a 67-year-old female Alzheimer's disease patient with 8 implant fixtures on the fully edentulous site of mandible, implant overdenture with using milled bar and magnet attachment was planned. As rapid treatment was required, CAD/CAM system was used to make a simple laboratory procedure instead of a traditional fabrication process. With this system, implant overdenture with milled bar can be fabricated esthetically and functionally.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.8
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• pp.13-19
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• 2001

We report on the fabrication and characterization of $Al_{0.3}Ga_{0.7}N$ HFETs with different barrier layer thickness which were grown using plasma-assisted molecular beam epitaxy (PAMBE). The barrier thickness of $Al_{0.3}Ga_{0.7}N$/GaN HFETs could be optimized in order to maximize 2 dimensional electron gas induced by piezoelectric effect without the relaxation of $Al_{0.3}Ga_{0.7}N$ layer. $Al_{0.3}Ga_{0.7}N$/GaN (20 nm/2 mm) HFET with 0.6 ${\mu}m$-long and 34 ${\mu}m$-wide gate shows saturated current density ($V_{gs}=1\;V$) of 1.155 A/mm and transconductance of 250 ms/mm, respectively. From high frequency measurement, the fabricated $Al_{0.3}Ga_{0.7}N$/GaN HFETs showed $F_t=13$ GHz and $F_{max}=48$ GHz, respectively. The uniformity of less than 5% could be obtained over the 2 inch wafer. In addition to the optimization of epi-layer structure, the relation between breakdown voltage and high frequency characteristics has been examined.

• The Journal of Korean Academy of Prosthodontics
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• v.56 no.4
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• pp.317-322
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• 2018

The tongue, especially its lateral part, is the most common site of oral tumors. Patients who undergo glossectomy for the treatment of tongue cancer may experience difficulty in proper functioning for pronunciation, chewing, swallowing, and oral hygiene maintenance; therefore, a palatal augmentation prosthesis can be used to restore function of the tongue. In this case, an implant overdenture was used in a patient who had residual ridge resorption and obliteration of alveololingual sulcus after undergoing glossectomy for tongue cancer treatment. In addition, a palatal augmentation prosthesis with a metal framework, support, and retention part was fabricated. The palatal vault was reduced, so that even with limited tongue movement, adequate tongue-palate contact could be achieved. After placement of the definitive prostheses, the patient showed improvement in the functions of chewing, swallowing, and pronunciation.

• Journal of Dental Rehabilitation and Applied Science
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• v.33 no.4
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• pp.291-298
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• 2017

It is challenging to produce esthetic implant restoration in the narrow anterior maxilla region where insufficient volume of alveolar bone could limit the angle and position of implant fixture, if preceding bone augmentation is not considered. Ideal angle and position of implant fixture placement should be established to reproduce harmonious emergence profile with marginal gingiva of implant prosthesis, bone augmentation considered to be preceded before implant placement occasionally. In this case, preceding bone augmentation has been operated before esthetic implant prosthesis in narrow anterior maxilla region. Preceded excessive bone augmentation in buccal area allowed proper angulation of implantation, which compensates unfavorable implant position. Provisional restorations were corrected during sufficient period to make harmonious level of marginal gingiva and interdental papilla. The definite restoration was fabricated using zirconia core based glass ceramic. Functionally and esthetically satisfactory results were obtained.

• The Journal of Korean Academy of Prosthodontics
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• v.55 no.4
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• pp.427-435
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• 2017

The most important factor in the treatment of fully edentulous patients using implants is the shape of the definitive prosthesis. After the shape of the definitive prosthesis is determined, residual bone analysis and selection of the implant type, number and position should be followed. In this case, for restoration of an edentulous patient fully implanted (except the maxillary right lateral incisor) without considering definitive prosthesis, facial esthetics and possibility of fixed type prosthesis were evaluated using complete denture. It was determined that the fixed type prosthesis was possible. Implants that could not be used for the definitive prosthesis were excluded from the treatment plan and fixed type provisional restorations were fabricated. After four months of provisional restorations, the patient showed stable occlusion and esthetic satisfaction. Definitive prosthesis was made of zirconia using CAD/CAM (computer aided design and computer aided manufacturing). The results were satisfactory during the 3 months of follow-up period after termination of treatment.

• Journal of the Korea Convergence Society
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• v.8 no.5
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• pp.161-167
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• 2017

We have fabricated and characterized $32{\times}32$ photonic quantum ring (PQR) laser arrays uniformly operable with $0.98{\mu}A$ per ring at room temperature. The typical threshold current, threshold current density, and threshold voltage are 20 mA, $0.068A/cm^2$, and 1.38 V. The top surface emitting PQR array contains GaAs multiquantum well active regions and exhibits uniform characteristics for a chip of $1.65{\times}1.65mm^2$. The peak power wavelength is $858.8{\pm}0.35nm$, the relative intensity is $0.3{\pm}0.2$, and the linewidth is $0.2{\pm}0.07nm$. We also report the wavelength division multiplexing system experiment using angle-dependent blue shift characteristics of this laser array. This photonic quantum ring laser has angle-dependent multiple-wavelength radial emission characteristics over about 10 nm tuning range generated from array devices. The array exhibits a free space detection as far as 6 m with a function of the distance.

• Journal of the Korean Magnetics Society
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• v.13 no.3
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• pp.97-102
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• 2003

Synthetic ferrimagnetic layer (SyFL) with structure NiFe/Ru/NiFe which can be applied high density TMR device in free layer were prepared by an inductively coupled plasma (ICP) helicon-sputter. We proposed a model of predicting coercivity (H$\_$c/), spin-flopping field (H$\_$sf/), and saturation field (H$\_$s/) as a function of Ru thicknesses, from the equilibrium state of energies of Zeeman, exchange, and uniaxial anisotropy. We fabricated the samples of Ta(50 ${\AA}$)/NiFe(50${\AA}$)nu(4∼20${\AA}$)NiFe(30 ${\AA}$)/Ta(50${\AA}$), and measured the M-H loops with a superconduction quantum interference device (SQUID) applying the external field up to ${\pm}$ 15 kOe. The result was well agreed with the proposed model, and reveal K$\_$u = 1000 erg/㎤, J$\_$ex/ =0.7 erg/$\textrm{cm}^2$. We report that H$\_$c/ below 10 Oe is available, and R$\_$u/ thickness range should be in 4-10 ${\AA}$ for MRAM application. Our result implies that permalloy layers may lead to considerable magnetostriction effect in SyFL and intermixing in NiFe/Ru interfaces.

• The Journal of Korean Academy of Prosthodontics
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• v.51 no.1
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• pp.39-46
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• 2013

The loss of posterior support may cause attrition of anterior teeth, and loss of occlusal vertical dimension (OVD). The collapse of the posterior support will eventually cause the pathologic change of the TMJ and masticatory muscles, unesthetic facial appearance and decreased masticatory function. Patients with destroyed dentition need extensive prosthetic treatments. Proper diagnosis and treatment planning are necessary for the stability of the neuromuscular system and the TMJ, and esthetic and functional definitive restorations. In this case, 63 year-old male presented with decreased masticatory force and esthetic problems due to pathologic destruction of teeth structure on entire dentition. Based on assessment of OVD including intraoral findings, radiographic examination and diagnostic cast, full-mouth rehabilitation with increase of OVD was planned using fixed partial denture and removable partial denture. Diagnostic wax-up was done after 4 mm increase of OVD determined by assessment of OVD. The OVD was maintained with the overlay type removable interim prostheses for 12 weeks to ascertain his comfort and adaptation to the new OVD. After the adaptation period, second interim prostheses with tooth preparation maintaining the established OVD was delivered. After 4 weeks, final prostheses were fabricated and delivered. After 7 month follow-up period, occlusal stability is maintained. Through this procedure, satisfactory outcomes were achieved both in functional and esthetic aspects.

• Journal of Radiation Protection and Research
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• v.38 no.3
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• pp.132-137
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• 2013

Cryogenic particle detectors have recently been adopted in radiation detection and measurement because of their high energy resolution. Many of these detectors have demonstrated energy resolutions better than the theoretical limit of semiconductor detectors. We report the development of alpha spectrometer using a micro-fabricated magnetic calorimeter coupled to a large-area particle absorber. A piece of gold foil of $2{\times}2{\times}0.05mm^3$ was glued to the paramagnetic temperature sensor made of sputtered Au:Er film to serve as an absorber for incident alpha particles. We performed experiments with 241Am source at cryogen free adiabatic demagnetization refrigerator (CF-ADR). A high energy resolution of 6.8 keV in FWHM was obtained for 5.5 MeV alpha particles.

• Journal of the Korean Applied Science and Technology
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• v.31 no.2
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• pp.231-237
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• 2014

The supercritical fluids (SCFs) have been widely used for material synthesis and processing due to their remarkable properties including low viscosity, high diffusivity and low surface tension. Carbon dioxide is one of the suitable solvents in SCFs processes in terms of its advantages such as easy processibility (with low critical temperature and pressure), inexpensive, nonflammable, nontoxic, and readily available. However, it has generally low solubility for high molecular weight polymers with the exception of fluoropolymers and siloxane polymers. Therefore, hydrocarbon solvents and hydrochlorofluorocarbons have been used for various SCFs process by its high solubility for high molecular weight polymers. In this report, a PMMA/clay nanocomposites were fabricated by using supercritical fluid process. The $Na^+$-MMT(montmorillonites)was modified by a fluorinated surfactant which is able to enhance compatibility with the chlorodifluoromethane(HCFC-22) and thus, improve dispersability of the clay in the polymer matrix. The PMMA/fluorinated surfactant modified clay nanocomposite shows enhanced mechanical and thermal properties which characterized by X-raydiffraction(XRD), Thermo gravimetric analysis(TGA), Dynamic mechanical analysis (DMA) and Transmission electron microscopy (TEM).