• Journal of Korean Neurosurgical Society
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• v.45 no.3
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• pp.176-178
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• 2009

Traumatic brainstem hemorrhage after blunt head injury is an uncommon event. The most frequent site of hemorrhage is the midline rostral brainstem. The prognosis of these patients is poor because of its critical location. We experienced a case of traumatic brainstem hemorrhage. A 41-year-old male was presented with drowsy mentality and right hemiparesis after blunt head injury. Plain skull radiographs and brain computerized tomography scans revealed a depressed skull fracture, epidural hematoma, and hemorrhagic contusion in the right parieto-occipital region. But, these findings did not explain the right hemiparesis. T2-weighted magnetic resonance (MR) image of the cervical spine demonstrated a focal hyperintense lesion in the left pontomedullary junction. Brain diffusion-weighted and FLAIR MR images showed a focal hyperintensity in the ventral pontomedullary lesion and it was more prominent in the left side. His mentality and weakness were progressively improved with conservative treatment. We should keep in mind the possibility of brainstem hemorrhage if supratentorial lesions or spinal cord lesions that caused neurological deficits in the head injured patients are unexplainable.

• Journal of IKEEE
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• v.22 no.2
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• pp.339-343
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• 2018

Power semiconductors are semiconductors capable of controlling power over 1W and are mainly used as switches. This power semiconductor device has been developed with the goal of reducing power consumption and high breakdown voltage. This research was analyzed electrical characteristics of IGBT(Insulated Gate Biopolar Transistor) according to diffusion length of JFET region. The Diffusion length of JFET region was controlled by temperature and time using T-CAD simulator. As a result of experiments, we could obtain 1.14V low on state voltage drop by fixing 1440V breakdown voltage.

• Journal of Magnetics
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• v.9 no.2
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• pp.60-64
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• 2004

In this paper calculations of magnetisation and magnetoresistance characteristics of the Spin Valve (SV) and Pseudo Spin Valve (PSV) spintronics structures are reported and compared with the experimental data. The magnetisation reversal process was analysed with respect to the Stoner- Wohlfahrt model of total surface energy in terms of uniaxial anisotropy, exchange coupling between ferromagnetic layers, unidirectional exchange anisotropy of pinned layer (modelled by exchange coupling between magnetisation of pinned layer and net magnetisation of antiferromagnetic layer with high anisotropy). The numerical simulation of the model to the experimental magnetisation data yielded the above parameters for SV and PSV structures. These parameters were used to more sophistically micromagnetic modelling tool originating from the project called Object Oriented Micromagnetic Framework. Influence of the shape anisotropy of the Magnetic Tunnelling Junction cell used in MRAM was simulated by means of micromagnetic simulations. Results were compared to those obtained from the spot Kerr measurements.

• Journal of the Korean Society of Visualization
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• v.12 no.2
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• pp.13-17
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• 2014

In the present study, the optofluidic droplet manipulation in a microfluidic platform was demonstrated via theoretical and experimental approaches. Optical scattering force and gradient force were used to separate and trap droplets. Two types of droplets were generated by a T-junction method in the microfluidic channel. While they approach a test region where the optical beam illuminates the droplets, they were pushed by the optical scattering beam. The displacement by the laser beam is dependent on the refractive index of the droplets. By using the optical gradient force, the droplets can be trapped and coalesced. In order to bring the droplets in a direct contact, the optical gradient force was used to trap the droplets. A theoretical modeling of the coalescence was derived by combining the optical force and drag force on the droplet.

• Progress in Superconductivity and Cryogenics
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• v.17 no.4
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• pp.38-42
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• 2015

In terms of food safety,mixture of contaminants in food is a serious problem for not only consumers but also manufacturers. In general, the target size of the metallic contaminant to be removed is 0.5 mm. However, it is a difficult task for manufacturers to achieve this target, because of lower system sensitivity. Therefore, we developed a food contaminant detection system based on high-Tc RF superconducting quantum interference devices (SQUIDs), which are highly sensitive magnetic sensors. This study aims to improve the signal to noise ratio (SNR) of the system and detect a 0.5 mm diameter steel ball. Using a real time digital signal processing technique along with analog band-pass filters, we improved the SNR of the system. Owing to the improved SNR, a steel ball with a diameter as small as 0.3 mm, with stand-off distance of 117 mm was successfully detected. These results suggest that the proposed system is a promising candidate for the detection of metallic contaminants in food products.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.481.2-481.2
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• 2014

Bulk hetero junction (BHJ) polymer solar cell (PSCs) is one of the most promising fields as alternative energy source. Especially, the development of new p-type conjugated polymer is one of the main issues to get core technology. In this study, we investigated the chemical doping effects of incorporating 3,6-carbazole units into conjugated polymers based on 2,7-carbazole. We assessed the structural effects of this chemical doping by measuring the photovoltaic device performance of the copolymers with and without annealing. Note that the use of nanostructures in the bulk heterojunction layer could be a major obstacle to commercialization because nano-morphologies are frequently unstable at high temperatures. Therefore, the development of thermally stable polymer:fullerene blends with optimized PCEs is an important goal in this area of research. We studied the morphologies of the copolymers incorporating 3,6-carbazole units resulting from thermal annealing to investigate the effects of the difference between the T g values of the 2,7-carbazole unit and the 3,6-carbazole unit.

• Progress in Superconductivity
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• v.1 no.2
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• pp.110-114
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• 2000

We have investigated the Josephson vortex dynamics in $Bi_2Sr_2CaCu_2O{8+\delta}$ intrinsic Josephson junctions subjected to a magnetic field parallel to $CuO_2$ planes. We investigated mesas with $40\times40{\mu}m^2$ in size and containing 6 and 20. intrinsic junctions. The zero field I-V characteristics exhibited a typical hysteretic, multi-branched nature of the intrinsic Josephson effect. At high magnetic fields (H>1.5 T), I-V characteristics showed flux flow steps. The Swihart velocity obtained from this observation was about $4.2\times10^5$ m/s, which was the lowest mode electromagnetic wave velocity of N coupled stack. The experimental I-V curves fitted well into the simple model of Cherenkov radiation including Ohmic and non-linear dissipation terms. This suggests that the dissipation mechanism of Josephson vortex be due to both Cherenkov radiation and quasiparticle tunneling current.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.7 no.4
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• pp.44-50
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• 2011

Turbulent mixing of hot and cold coolants is one of the possible causes of high cycle thermal fatigue in piping systems of nuclear power plants. A typical situation for such mixing appears in turbulent flow through a T-junction. Since the high cycle thermal fatigue caused by thermal striping was not considered in the piping fatigue design in several nuclear power plants, it is very important to evaluate the effect of thermal striping on the integrity of mixing tees. In the present work, before conducting detailed evaluation, three thermal striping evaluation methodology suggested by EPRI, JSME and NESC are analyzed. Then, a by-pass pipe connected to the shutdown cooling system heat exchanger is investigated by using these evaluation methodology. Consequently, the resulting thermal stresses and the fatigue life of the mixing tee are reviewed and compared to each other. Futhermore, the limitation of each methodology are also presented in this paper.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.2
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• pp.66-72
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• 1995

Using the Si/SiGe layer grown by solid source molecular beam epitaxy(SSMBE) on the LOCOS-patterned wafers, an emitter-base self-aligned hterojunction biplar transistor(HBT) with the polysilicon-emitter and the silicon germanium(SiGe) base has been fabricated. Trech isolation process, planarization process using a chemical-mechanical poliching, and the selectively implanted collector(SIC) process were performed. A titanium disilicide (TiSi$_{2}$), as a base electrode, was used to reduce an extrinsic base resistance. To prevent the strain relaxation of the SiGe epitaxial layer, low temperature (820${^\circ}C$) annealing process was applied for the emitter-base junction formation and the dopant activation in the arsenic-implanted polysilicon. For the self-aligned Si/SiGe HBT of 0.9${\times}3.8{\mu}m^{2}$ emitter size, a cut-off requency (f$_{T}$) of 17GHz, a maximum oscillation frequency (f$_{max}$) of 10GHz, a current gian (h$_{FE}$) of 140, and an emitter-collector breakdown voltage (BV$_{CEO}$) of 3.2V have been typically achieved.

• Korean Journal of Veterinary Research
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• v.49 no.1
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• pp.73-78
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• 2009

Discoid lupus erythematosus (DLE) is an immune-mediated skin disease which requires histopathology and immunohistopathology in both dogs and humans. A 10-month-old, intact female Alaskan Malamute presented for depigmentation, swelling, alopecia, erythema, and crusting on the bridge of the nose and the nasal planum. Cytological examination of nasal lesions revealed numerous cocci and neutrophils. Histopathological features included of infiltration of mononuclear cells at the dermoepidermal junction. Direct immunofluorescence tests and immunohistochemistry exhibited positive IgG, IgM, IgA, CD3, CD18, and CD79a on the epidermal basement membranes and around adnexal glands. This case indicates both T cells and B cells are related to mechanism of canine DLE. This case report describes advanced diagnostic tests and clinical outcome with immune suppressive therapy in a rare juvenile canine DLE case.