• 비파괴검사학회지
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• 제18권4호
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• pp.304-312
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• 1998

비파괴검사중의 하나인 초음파 탐상검사는 교량, 발전설비 및 석유화학플랜트 등의 각종 다양한 구조물들의 안전성 확보를 위한 내부결함 및 손상평가를 위하여 일반적으로 폭넓게 사용되고 있다. 초음파를 이용한 데 파괴 평가 기술은 각종 구조물에 존재하는 내부결함에 의한 산란신호를 통해 건전성을 평가하는 기법이므로 결함의 신뢰성 녹은 정량적 평가를 위해서는 결함으로부터의 초음파 산란산호특성에 대한 기본적 이해가 필수적이며 따라서 이를 위한 모델링 수치해석 연구가 요구된다. 본 연구에서는 동탄성 경계요소법을 이용하여 무한체내에 존재하는 다중기공 결함에 의한 초음파 수평횡파의 근거리 산란특성에 대하여 결함의 형상과 결함사이의 상호작용을 고려하여 해석하였다. 본 연구에서 얻어진 결과들은 결함검출 민감도의 개선 및 역변환 해석에 의한 정량적 비파괴 평가에 큰 도움을 줄 수 있다.

• 전자공학회논문지A
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• 제32A권10호
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• pp.43-50
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• 1995

A laser diode(LD) structure consisting of a single 150$\AA$ $Al_{0.07}$Ga$_{0.93}$As quantum well active region operating at ${\lambda}$=809nm, cladded with an AlGaAs graded-index separate confinement heterostructure, has bes been grown by MOCVD. Temperature coefficient of wavelength is approximately 0.2nm $^{\circ}C$ for the diode. The active aperture consists of five emitters separated from each other by means of SiO$_{2}$ deposition and stripe formation, which creates insulating regions that channel the current to 100-$\mu$m-wide stripes placed on 450-$\mu$m centers. From a typical uncoated LD, the output power of 0.8W has been obtained at a 1$\mu$s, 1kHz pulsed current level of 2.0$\AA$, which results in about 64% external quantum efficiency. The threshold current density is 736A/cm$^{2}$ for the case of 500$\mu$m cavity length LD's. The measure of an internal quantum efficiency was 75.8% and the internal loss 4.83$cm^{-1}$ . Finally, 3.1W output power has been obtained at a 1$\mu$s, 1kHz pulsed current level of 9A from the 500$\mu$m-aperture LD array with 460-$\mu$m- cavity length.

• Journal of Dental Anesthesia and Pain Medicine
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• 제16권2호
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• pp.103-109
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• 2016

Background: One nostril must be selected for nasotracheal intubation. In some cases, structural anomalies within the nasal cavity hinder the insertion of the tube or complications, such as epistaxis, develop. This study examined the possibility of using radiography to select the nostril that would induce fewer complications. Methods: Four hundred and five patients who underwent nasotracheal intubation under general anesthesia were studied. A 7.0-mm internal diameter nasal right angle endotracheal (RAE) tube and 6.5-mm internal diameter nasal RAE tube were inserted into men and women, respectively. Complications were considered to have developed in cases in which insertion of the tube into the nasal cavity failed or epistaxis occurred. The tube was inserted into the other nostril for insertion failures and hemostasis was performed in cases of epistaxis. The degree of nasal septal deviation was determined from posteroanterior skull radiographs or panoramic radiographs; the incidence of complications was compared depending on the direction of the septal deviation and the intubated nostril. Results: The radiographs of 390 patients were readable; 94 had nasal septum deviation. The incidence of complications for cases without nasal septum deviation was 16.9%, that for cases in which the tube was inserted into the nostril on the opposite side of the deviation was 18.5%, and that for cases in which the tube was inserted into the nostril with the deviation was 35.0%, showing a high incidence of complications when intubation is performed through the nostril with septum deviation (chi-square test, P < 0.05 ). Conclusions: Although there were no differences in the incidence rates of complications between intubation through the left nostril and that through the right nostril, radiological findings indicated that incidence of complications significantly increased when the tube was inserted into the nostril with the septum deviation.

• Wind and Structures
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• 제16권1호
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• pp.1-23
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• 2013

The wind-induced transient response of internal pressure following the creation of a sudden dominant opening during the occurrence of high external pressure, in low-rise residential and industrial buildings was numerically investigated. The values of the ill-defined parameters namely the flow contraction coefficient, loss coefficient and the effective slug length were calibrated by matching the analytical response with the computational fluid dynamics predictions. The effect of a sudden i.e., "instantaneously created" windward opening in the Texas Technical University (TTU) test building envelope was studied for two different envelope flexibility-leakage combinations namely: (1) a quasi-statically flexible and non-porous envelope and (2) a quasi-statically flexible and porous envelope. The responses forced by creating the openings at different time leads/lags with respect to the occurrence of the peak external pressure showed that for cases where the openings are created in close temporal proximity to the peak pressure, the transient overshoot values of internal pressure could be higher than the peak values of internal pressure in the pre-sequent or subsequent resonant response. In addition, the influence of time taken for opening creation on the level of overshoot was also investigated for the TTU building for the two different envelope characteristics. Non-dimensional overshoot factors are presented for a variety of cavity volume-opening area combinations for (1) buildings with rigid/quasi-statically flexible non-porous envelope, and (2) buildings with rigid/quasi-statically flexible and porous envelope (representing most low rise residential and industrial buildings). While the factors appear slightly on the high side due to conservative assumptions made in the analysis, a careful consideration regarding the implication of the timing and magnitude of such overshoots during strong gusts, in relation to the steady state internal pressure response in cyclonic regions, is warranted.

• Tuberculosis and Respiratory Diseases
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• 제57권4호
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• pp.381-385
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• 2004

저자들은 클렙시엘라균종에 의한 폐렴에 동반된 폐 괴저를 수술적 치료없이 약물로만 호전시킨 1예를 경험하였기에 문헌고찰과 함께 보고하는 바이다.

• Tuberculosis and Respiratory Diseases
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• 제57권5호
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• pp.465-469
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• 2004

저자들은 패혈증이나 혈액응고장애가 이상이 없는 소방이 형성된 흉막삼출 환자에서 비교적 안전한 것으로 알려진 urokinase의 주입 후에 발생한 혈흉과 이로 인한 hypovolemic shock을 경험하였기에 문헌 고찰과 함께 보고하는 바이다.

• Tuberculosis and Respiratory Diseases
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• 제38권3호
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• pp.309-316
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• 1991

Malignant fibrous histiocytoma (MFH) is the most common soft tissue sarcoma of late adult life. This tumor occurs principally as a mass on an extremity or in the abdominal cavity or retroperitoneum of adult but primary pulmonary MFH is rare. MFH may be subclassified into storiform-pleomorphic, myxoid, giant cell, inflammatory, and angiomatoid type and the prognosis is no different among the histologic subtypes. We experienced one patient who was consistent with primary MFH of the lung. The patient complained dyspnea and intermittent hemoptysis and showed bilateral suprahilar mass on simple chest film and chest CT. Histological findings by open lung biopsy was storiform-pleomorphic type and individual cells showed histiocyte-like and fibroblast-like appearance.

• Restorative Dentistry and Endodontics
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• 제41권1호
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• pp.37-43
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• 2016

Objectives: The purpose of this study was to compare the marginal and internal fit of nano-composite CAD-CAM restorations. Materials and Methods: A full veneer crown and an mesio-occluso-distal (MOD) inlay cavity, which were prepared on extracted human molars, were used as templates of epoxy resin replicas. The prepared teeth were scanned and CAD-CAM restorations were milled using Lava Ultimate (LU) and experimental nano-composite CAD/CAM blocks (EB) under the same milling parameters. To assess the marginal and internal fit, the restorations were cemented to replicas and were embedded in an acrylic mold for sectioning at 0.5 mm intervals. The measured gap data were pooled according to the block types and measuring points for statistical analysis. Results: Both the block type and measuring point significantly affected gap values, and their interaction was significant (p = 0.000). In crowns and inlays made from the two blocks, gap values were significantly larger in the occlusal area than in the axial area, while gap values in the marginal area were smallest (p < 0.001). Among the blocks, the restorations milled from EB had a significantly larger gap at all measuring points than those milled from LU (p = 0.000). Conclusions: The marginal and internal gaps of the two nano-composite CAD/CAM blocks differed according to the measuring points. Among the internal area of the two nano-composite CAD/CAM restorations, occlusal gap data were significantly larger than axial gap data. The EB crowns and inlays had significantly larger gaps than LU restorations.

• Restorative Dentistry and Endodontics
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• 제37권1호
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• pp.41-49
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• 2012

Objectives: The internal adaptation of composite restorations with or without resin modified glass ionomer cement (RMGIC) was analyzed non-destructively using Microcomputed tomography (micro-CT). Materials and Methods: Thirty intact human teeth were used. The specimens were divided into 3 groups. In the control group, the cavities were etched with 10% phosphoric acid for 15 sec. Composite resin was filled into the cavity without adhesive. In group 1, light cured glass ionomer cement (GIC, Fuji II LC, GC) was applied as a base. The cavities were then etched, bonded, light cured and filled with composites. In group 2, the cavities were then etched, bonded, light cured and filled with composites without base application. They were immersed in a 25% silver nitrate solution. Micro-CT was performed before and after mechanical loading. One-way ANOVA with Duncan analysis was used to compare the internal adaptation between the groups before or after loading. A paired t-test was used to compare internal adaptation before and after mechanical loading. All statistical inferences were made within the 95% confidence interval. Results: The silver nitrate solution successfully penetrated into the dentinal tubules from the pulp spaces, and infiltrated into the gap between restoration and pulpal floor. Group 2 showed a lower adaptation than the control group and group 1 (p < 0.05). There was no significant difference between the control group and group 1. For all groups, there was a significant difference between before and after mechanical loading (p < 0.05). Conclusions: The internal adaptation before and after loading was better when composites were bonded to tooth using adhesive than composites based with RMGIC.

• Tuberculosis and Respiratory Diseases
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• 제48권1호
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• pp.84-90
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• 2000

저자들은 안정시 호흡곤란을 주소로 내원하였고 흉벽에 종괴가 있었던 68세 남자환자에서 조직학적 검사상 전형적인 투명세포형의 원발성 신장암으로 진단된 1 예를 경험하였기에 문헌고찰과 함께 보고하는 바이다.