• Journal of Chest Surgery
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• v.27 no.5
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• pp.418-421
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• 1994

The usage of autosuture instruments and techniques in resection of bronchovascular structures gained increasing acceptance amongst surgeons in the recent years. The manipulation of these devices are simple, safe, and shortens operating time by avoiding numerous ties and sutures. We have been using autosuture instruments in most of pulmonary resections in Yongdong Severance hospital, and had a satisfactory results. However, we recently have experienced post-pneumonectomy rupture of left pulmonary vein on postoperative one day where the rupture site was in the border of left atrium and left pulmonary vein where the stapler was fired. The patient underwent emergency operation to control massive bleeding and successfully managed by left atrial suture.

• Journal of Chest Surgery
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• v.28 no.11
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• pp.1001-1006
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• 1995

From January, 1990 to December, 1994, we have operated 10 patients with cardiac rupture. The patients are divided into two groups according to their clinical manifestation ; five patients in each hemorrhage and tamponade group. The patients in both groups could maintain their vital signs with closed thoracostomy and fluid resuscitation. The effect of pericardiocentesis was especially dramatic in three patients of tamponade group. The average time from injury to admission was 101 minutes and that of the patients who came our hospital via one or two other hospitals was 170 minutes comparing 31 minutes of those who came directly. The average time from admission to operation was 211 minutes. Considering 98 minutes for the diagnosis and preoperative management and another 30 minutes for the preparation for operation, operations were delayed by 83 minutes to get permission. We conclude that this delaying time for transport and operation of heart-ruptured patients should be shortened in order to manage them more effectively.

• Design & Manufacturing
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• v.2 no.6
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• pp.43-48
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• 2008

Magnesium alloys have given high attention to the industry of light-weigh as automobile and electronics with aluminium, titanium and composite alloys due to their high strength, low specific density and good damping characteristics. But the magnesium contained structures under high temperature have the problems related to creep deformation and rupture life, which is a reason of developing the new material against creep deformation to use them safely. The purpose of this study is to predict the creep deformation mechanism and rupture time of AZ31 magnesium alloy. For this, creep tests of AZ31 magnesium alloy were done under constant creep load and temperature with the equipment including automatic temperature controller with acquisition computer. The apparent activation energy Qc, the applied stress exponent n and rupture life have been determined over the temperature range below 0.5Tm and stress range of 109~187MPa, respectively, in order to investigate the creep behavior. AZ31 Magnesium alloy identify the activation energy for creep deformation and the stress dependence to creep rate at below 0.5Tm, and then investigate the mechanism for creep deformation and creep rupture life of AZ31 Magnesium alloy.

• Journal of Veterinary Clinics
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• v.20 no.2
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• pp.229-232
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• 2003

Ultrasonographic examination of the stifle joint four clinically and radiographically normal adult dogs was performed before and after inducing the cranial cruciate ligament (CrCL) rupture of the bilateral stifle surgically. At Pre- or post-surgery, the hyperechoic patella ligament and the echogenic infrapatella fat interfered the visualization of the CrCL by the plain scanning method. However when the stifle joint was imaged by the scanning method injecting normal saline within the joint capsule, the hyperechogenic ligament was visualized by the separation of the infrapatella fat and the CrCL and the contrast effect of anechoic saline. When the stifle joint was imaged by the real time scanning method after the induction of the surgical rupture, fluttering of the ligament and anechoic area between the bone and the CrCL was identified due to the lack of tonicity and continuity of the ligament. Enlargement of the ligament because of its increased diameter as well as fluttering of the CrCL and the increased joint space's thickness was visualized. Consequently, confirming fluttering of the CrCL, increased ligament diameter and anechoic region between the CrCL and the bone, ultrasonographic examination is a valuable diagnostic tool as well as cranial drawer test and radiographic examination.

• Journal of the Korean Geotechnical Society
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• v.20 no.7
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• pp.79-89
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• 2004

An elastic-plastic-viscous constitutive model was proposed based on a simple formulation scheme. The anisotropic modified Cam-Clay model was extended for the general stress space for the plastic simulation. The generalized viscous theory was simplified and used for the viscous constitutive part. A damage law was incoporated into the proposed constitutive model. The mathematical formulation and development of the model were performed from the point of view that fewer parameters be better employed. The creep behaviors with or without creep rupture were predicted using the developed model for cohesive soils. The model predictions were favorably compared with the experimental results including the undrained creep rupture, which is an important observed phenomenon for cohesive soils. Despite the simplicity of the constitutive model, it performs well as long as the time to failure ratio of the creep rupture tests is within the same order of magnitude.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.3
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• pp.84-91
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• 2012

This paper aims to investigate the effects of cable rupture on the dynamic responses of concrete cable-stayed bridges in comparison with those of steel composite ones. It examines an adequate analysis method for simulating cable rupture using a time history function and evaluates the design guidelines for dynamic amplification factor (DAF). The computed DAFs from a concrete cable-stayed bridge are compared with those from a steel composite one based on the design guideline. As a conclusion, the current design guidelines for DAF may be reliable in overall but show some unstable cases despite satisfying the design guidelines, especially for concrete cable-stayed bridges.

• Korean Journal of Materials Research
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• v.31 no.5
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• pp.255-263
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• 2021

P91 steel has been a highly researched material because of its applicability for high-temperature applications. Considerable efforts have been made to produce experimental creep data and develop models for creep life prediction. As creep tests are expensive and difficult to conduct, it is vital to develop authenticated empirical methods from experimental results that can be utilized for better understanding of creep behavior and can be incorporated into computational models for reliable prediction of creep life. In this research, a series of creep rupture tests are performed on the P91 specimens within a stress range of 155 MPa to 200 MPa and temperature range of 640 ℃ (913 K) to 675 ℃ (948 K). The microstructure, hardness, and fracture surfaces of the specimens are investigated. To analyze the results of the creep rupture tests at a macro level, a parameter called creep work density is derived. Then, the relationships between various creep parameters such as strain, strain rate, time to rupture, creep damage tolerance factor, and creep work density are investigated, and various empirical equations are obtained.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.2
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• pp.157-162
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• 2011

High temperature and stress are encounted in power plants and vehicle engines. Therefore, determination of the creep-fatigue life of a material is necessary prior to fabricating equipments. In this study, life design was determined on the basis of the lethargy coefficient for different temperatures, stress and rupture times. SP-Creep test data was compared with computed data. The SP-Creep test was performed to obtain the rupture time for X20CrMoV121 steel. The integration life equation was considered for three cases with various load, temperature and load-temperature. First, the lethargy coefficient was calculated by using the obtained rupture stress and the rupture time that were determined by carrying out the SP-Creep test. Next, life was predicted on the basis of the temperature condition. Finally, it was observed that life decreases considerably due to the coupling effect that results when fatigue and creep occur simultaneously.

• Journal of Power System Engineering
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• v.6 no.1
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• pp.55-60
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• 2002

There has been no report on the life prediction for gas turbine materials at high temperatures based on the creep properties and their relationship with the AE(acoustic emission) properties as a means of real-time non-destructive testing. One of the important issues is thus to develop a reliable method of evaluating creep properties by the AE technique. In this paper, the real-time evaluation of high temperature creep time and AE cumulative counts for nickel-based superalloy Udimet 720 was performed on round-bar type specimens under pure load at the temperatures of 811, 922 and 977K. The total AE cumulative counts until the starting point of secondary creep($N_1$) and that of tertiary creep($N_2$) have quantitative relationship with the tertiary creep time and the rupture time. It is thus possible to construct the life prediction system based on creep and the prevention system of tertiary creep by using AE technique.

• Journal of the Korean Institute of Gas
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• v.16 no.5
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• pp.28-34
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• 2012

Material degradation of Cr steels in using for boiler tubes was studied in the relation of microstructural changes like carbide behavior and mechanical properties of hardness and creep-rupture life. The carbide dissolution was occurred in 2Cr steel of T22 during high temperature operation. And the grain refinement within martensite lath of 12Cr steel of X20 was derived by the high temperature-long time exposure. But the specific phenomena of material degradation which might be represented by hardness or creep-rupture time of the used tubes were not shown in all the tubes of T22 and X20 even in the fire-side using.