• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.79-80
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• 2007

To obtain the single crystal thin films, $AgGaSe_2$ mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the hot wall epitaxy (HWE) system. The source and substrate temperatures were $630^{\circ}C\;and\;420^{\circ}C$, respectively. The temperature dependence of the energy band gap of the $AgGaSe_2$ obtained from the absorption spectra was well described by the Varshni's relation, $E_g$(T) = 1.9501 eV - ($8.79{\times}10^{-4}$ eV/K)$T^2$/(T + 250 K). After the as-grown $AgGaSe_2$ single crystal thin films was annealed in Ag-, Se-, and Ga-atmospheres, the origin of point defects of $AgGaSe_2$ single crystal thin films has been investigated by the photoluminescence(PL) at 10 K. The native defects of $V_{Ag},\;V_{Se},\;Ag_{int},\;and\;Se_{int}$ obtained by PL measurements were classified as a donors or acceptors type. And we concluded that the heat-treatment in the Ag-atmosphere converted $AgGaSe_2$ single crystal thin films to an optical p-type. Also, we confirmed that Ga in $AgGaSe_2$/GaAs did not form the native defects because Ga in $AgGaSe_2$ single crystal thin films existed in the form of stable bonds.

• Journal of the Architectural Institute of Korea Planning & Design
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• v.36 no.4
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• pp.71-81
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• 2020

The purpose of this study is to propose the planning methods for pollution prevention in the initial design stage by identifying the pollution phenomena on the exterior of the building. It is important to catch the problem early on because exterior troubles begin with an initial design defect and causes rapid aging. The scope of this study is seoul public borough offices that should be sustainable for long as landmark located at the center of the district. Field survey was conducted three times in six months. Twenty-six borough offices were diagnosed with three levels of contamination through visual inspection and the contaminated locations, types, materials, and characteristics were checked. Fourteen common contaminated locations were identified in the first and intensively rechecked in the second. Five locations vulnerable to contamination were designated and the contamination and cleanliness situations were checked by location in the third. As a result, main polluted types and locations are sloping wall, upper wall, protruded wall, canopy, and wall under window. The key to avoiding these pollution problems is to minimize the horizontal plane on which dust can be deposited. In other words, it can be considered variously by shape and location, such as the slope of the horizontal plane, the floating of the surface, the installation of the roof surface, and the vertical louvers. And throating plans and material plans suitable for each location are presented. Various methods of the shape and location, material are expected to use as useful basic data for preventing pollutions during the initial design stage.

• Corrosion Science and Technology
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• v.3 no.1
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• pp.30-33
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• 2004

It has been reported that some events of a rupture of seam generator tube have occurred in nuclear power plants around the world. Main causes of the leakage are from various types of corrosion in the steam generator(SG) tubings. Primary water stress corrosion cracking(PWSCC) of steam generator tubings have occurred in many tubes in Korean plant, and they were repaired using sleeves or plugs, In order to develop proper repair criteria, it is necessary to ascertain the leak behavior of the tubings. A high pressure leak and burst testing system was manufactured. Various types of Electro Discharged Machined (EDM) notches were developed on the SG tubes. Leak rate and burst pressure were measured on the tubes at room temperature. Burst pressure of the part through wall defected tubes depends on the defect depth, Water flow rates after the burst were independent of the t1aw types; tubes having 20 to 60 mm long EDM notches showed similar flow rates regardless of the defect depth. A fast pressurization rate gave the tube a lower burst pressure than the case of a slow pressurization.

• Transactions on Electrical and Electronic Materials
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• v.6 no.4
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• pp.177-185
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• 2005

Fatigue characteristics of lead zirconate titanate (PZT) films deposited by electron cyclotron resonance plasma enhanced chemical vapor deposition (ECR-PECVD) were investigated. The fatigue characteristics were investigated with respect to PZT film thickness, domain structure, fatigue pulse height, temperature, electrode materials and electrode configurations. The used top and bottom electrode materials were Pt and $RuO_2$. In the fatigue characteristics with fatigue pulse height and PZT film thickness, the fatigue rates are independent of the applied fatigue pulse height at the electric field regions to saturate the P-E hysteresis and polarization $(P^*,\;P^A)$ characteristics. The unipolar and bipolar fatigue characteristics of PZT capacitors with four different electrode configurations $(Pt//Pt,\;Pt//RuO_2,\;RuO_2//Pt,\;and\;RuO_2//RuO_2)$ were also investigated. The polarization-shifts during the unipolar fatigue and the temperature dependence of fatigue rate suggest that the migration of charged defects should not be expected in our CVD-PZT films. It seems that the polarization degradations are attributed to the formation of charged defects only at the Pt/PZT interface during the domain switching. The charged defects pin the domain wall at the vicinity of Pt/PZT interface. When the top and bottom electrode configurations are of asymmetric $(Pt//RuO_2,\;RuO_2//Pt)$, the internal fields can be generated by the difference of charged defect densities between top and bottom interfaces.

• Journal of International Society for Simulation Surgery
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• v.3 no.2
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• pp.80-83
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• 2016

A 37-year-old male was assaulted and complained of severe periorbital swelling. Physical examination revealed that there were limitation of eyeball movement on upper gaze, diplopia, and hypoesthesia on the infraorbital nerve innervating region. Three-dimensional (3D) computed tomography (CT) of facial bone exhibited the fracture of orbital floor accompanying the significant amount of orbital contents' herniation extending to the far posterior part. To recover the orbital volume and restore orbital floor without threatening the optic nerve, preoperative simplified simulation was applied. The posterior margin of the fractured orbit was delineated with simulation technique using cross-linkage between the coronal and sagittal sections based on the referential axial view of the CT scans. Dissection, reduction of orbital contents, and insertion of the absorbable mesh plate molded after the prefabricated template by the simulation technique was performed. Extensive orbital floor defect was successfully reconstructed and there were no serious complications. The purpose of this report is to emphasize the necessity of preoperative simulation in case of restoring the extensive orbital floor defect.

• Journal of Korean Neurosurgical Society
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• v.54 no.4
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• pp.355-358
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• 2013

Spinal extradural arachnoid cyst (SEAC) is a rare disease and uncommon cause of compressive myelopathy. The etiology remains still unclear. We experienced 2 cases of SEACs and reviewed the cases and previous literatures. A 59-year-old man complained of both leg radiating pain and paresthesia for 4 years. His MRI showed an extradural cyst from T12 to L3 and we performed cyst fenestration and repaired the dural defect with tailored laminectomy. Another 51-year-old female patient visited our clinical with left buttock pain and paresthesia for 3 years. A large extradural cyst was found at T1-L2 level on MRI and a communication between the cyst and subarachnoid space was illustrated by CT-myelography. We performed cyst fenestration with primary repair of dural defect. Both patients' symptoms gradually subsided and follow up images taken 1-2 months postoperatively showed nearly disappeared cysts. There has been no documented recurrence in these two cases so far. Tailored laminotomy with cyst fenestration can be a safe and effective alternative choice in treating SEACs compared to traditional complete resection of cyst wall with multi-level laminectomy.

• Archives of Plastic Surgery
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• v.36 no.6
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• pp.795-798
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• 2009

Purpose: The repair of complex chest wall defects presents a challenging problem for the reconstructive surgeon. In particular, a free flap is often required when the defect is large, in which case suitable recipient vessels must be found to insure revascularization. The authors report a case of persistent bronchopleural - cutaneous fistula developed after undergoing lobectomy for lung cancer. Methods: The defect area was repaired using a free vertical rectus abdominis muscle flap revascularized by microvascular anastomosis to the 6th intercostal pedicle. The flap obliterated the right chest cavity, closed the site of empyema drainage, and aided healing of a bronchopleural - cutaneous fistula. Results: The patient has remained healed for 14 months without any postoperative complications and recurrent infection or fistula. Conclusion: We suggest that a rectus abdominis musculocutaneus free flap and intercostal pedicle as a recipient could be a useful method for repair of chest defects.

• Journal of Chest Surgery
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• v.37 no.5
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• pp.448-451
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• 2004

Report of right atrial thrombus complicating pulmonary embolism after cardiac surgery is rare. A 54-year-old woman operated on the atrial septal defect 10 months ago was admitted for left pleuritic pain and dyspnea. Multiple segmental perfusion defects were detected in lung perfusion scan. Transesophageal echocardiography showed a large mobile right atrial mass attached to the free wall of the right atrium with a stalk. Despite the intravenous heparinization for 13 days, follow-up echocardiography revealed the right atrial mass had not diminished in size. The mass which was confirmed as an organizing thrombus was excised under cardiopulmonary bypass. The patient recovered uneventfully and was discharged on warfarin therapy.

• Clinical and Experimental Pediatrics
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• v.48 no.10
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• pp.1143-1143
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• 2005

The traumatic ventricular septal defect (VSD) is a rare but potentially life threatening complication of chest wall injury. The traumatic VSD occurs in up to 4.5% of penetrating cardiac trauma. Most of the patients are usually operated on because of heart failure and/or significant left-to-right shunt. The feasibility of surgical repair under cardiopulmonary bypass may be affected by coexisting pulmonary, cerebral or other vascular injuries. Transcatheter closure of VSD is being considered as an alternative therapeutic modality to surgery in order to avoid the potential risk of cardiopulmonary bypass. We report a patient who underwent a successful transcatheter closure of VSD with an $Amplatzer^{(R)}$ VSD occluder. The patient had a residual VSD with significant left-to-right shunt after surgical repair of post-traumatic VSD using cardiopulmonary bypass.

• Nuclear Engineering and Technology
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• v.38 no.3
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• pp.293-300
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• 2006

A liquid metal reactor (LMR) operated at high temperatures is subjected to both cyclic mechanical loading and thermal loading; thus, creep-fatigue is a major concern to be addressed with regard to maintaining structural integrity. The Korea Advanced Liquid Metal Reactor (KALIMER), which has a normal operating temperature of $545^{\circ}C$ and a total service life time of 60 years, is composed of various cylindrical structures, such as the reactor vessel and the reactor baffle. This study focuses on the creepfatigue crack initiation for a cylindrical Y-junction structure made of 316 stainless steel (SS), which is subjected to cyclic axial tensile loading and thermal loading at a high-temperature hold time of $545^{\circ}C$. The evaluation of the considered creep-fatigue crack initiation was carried out utilizing the ${\sigma}_d$ approach of the RCC-MR A16 guide, which is the high-temperature defect assessment procedure. This procedure is based on the total accumulated strain during the service time. To confirm the evaluated result, a high-temperature creep-fatigue structural test was performed. The test model had a circumferential through wall defect at the center of the model. The defect front of the test model was investigated after the $100^{th}$ cycle of the testing by utilizing a metallurgical inspection technique with an optical microscope, after which the test result was compared with the evaluation result. This study shows how creep-fatigue crack initiation for a high-temperature structure can be predicted with conservatism per the RCC-MR A16 guide.