• Tribology and Lubricants
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• v.26 no.1
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• pp.61-67
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• 2010

The purpose of this paper is to study and analyze the failure examples on tribological characteristics of an automotive steering system. In this failure study, the grease leakage may stick leaked grease, dust, and wear particles between pinion and rack gears in mechanical steering system. In the case of seal failures such as a rod seal, o-ring and oil seals, the gear box and oil pump do not operate properly due to lack of oils. This means that oil pump does not supply a working fluid and produce a normal oil pressure of the steering system. This leads to leak a working fluid from the seals and produce a wear between pinion and rack gears. Especially, the leaked oil is usually mixed with internal wear particles and foreign dust/fine sands. Thus no leakage of working oils is very important design concepts, which is strongly related to the sealing components and smoothly operating of the mechanical friction parts of power steering system.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.862-869
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• 2005

This study examined 233 cut slopes in Gyeongnam region; evaluated hazards and slope conditions involved in the slope; and determined the priority order for reinforcement. The conclusions are summarized in the following. (1) The slopes that need reinforcement or maintenance are 153, accounting for 65.6% of the entire slopes. Slopes with a length of $0{\sim}200m$ account for 70.9%; slopes with a height of $10{\sim}20m$ account for over 50%. (2) Slopes with slope of more than 1:0.5 account for 70.9% of the entire slopes. The steepness of the slope is owing to more rock slopes than soil slopes. (3) The percentages of rock slopes, soil slopes, complex slopes mixed with rocks and soil, and slopes comprised of igneous rocks are 54.4%, 24.9%, 20.7%, and 54.1%, respectively. (4) In the rock area occurred cave-in, plain failure, wedge failure, and overturning failure, in order. Slopes with volcanic rocks are the most unstable, while sedimentary rocks and metamorphic rocks are relatively stable. (5) When the slope height is over 20m, low grade slopes are more than 80%; leading to the conclusion that the higher the slope height is, the more unstable the slope is.

• The Journal of Engineering Geology
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• v.10 no.2
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• pp.1-17
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• 2000

In this study, 270 cut-slopes are investigated and statistical analyses are performed. More than 84% of unstable slopes are rock slopes or rock-soil mixed slopes, and 72% of the slopes have 10 to 30 meter in height. And in order to clarify the cause of failure, 3 slopes which have been failed are back-analysed by using the computer programs such as DIPS, UDEC and PCSTABL5M. A heavy rainfall during rainy season is a main cause of slope failure, and a blasting vibration during construction could also give a significant influence on the slope instability.

• Tribology and Lubricants
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• v.18 no.5
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• pp.351-356
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• 2002

The surfaces of machine components in sliding contact such as bearing, gears and pistons etc. frequently operate under the condition of mixed lubrication due to high load, high speed and slip. These machine components often undergo the inception of scuffing in practical application. The scuffing failure is a critical problem in modern machine components, especially for the requirement of high efficiency and small size. However, it is difficult to find a universal mechanism to explain all scuffing phenomena because there are so many factors affecting the onset of scuffing. In this study, scuffing experiments are conducted using Acoustic Emission(AE) measurement by an indirect sensing approach to detect scuffing failure. Acoustic Emission(AE) signal has been widely utilized to monitor the interaction at the friction interface. Using AE signals we can get an indication about the state of the friction processes, about the quality of solid and liquid layers on the contacting surfaces in real time. The FFT(Fast Fourier Transform) analyses of the AE signal are sued to understand the interfacial interaction and the relationship between the AE signal and the state of contact is presented.

• Journal of Chest Surgery
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• v.25 no.1
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• pp.96-104
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• 1992

The 242 patients were operated due to chronic empyema in Hanyang University Hospital From Jan, 1983 to Aug, 1991, we operated 17 patients by modified.Schede`s thoracoplasty with myoplasty and we concluded to next scentences. 1. The age of patients were varied from 28 to 65[Average 39.1] and male preponderance was seen[more than 3 times]. 2. The preoperative cause of disease were tuberculosis in 14 patients[3 patients were associated with aspergillosis, and 1 patient was associated vrith actinomycosis], lung abscess in 2 patients, and haemophilia in 1 patient. 3. The Preoperative duration of empyema were varied from 1 month to 30 years[Average 49.8 month], and the duration from pulmonary resection to thoracoplasty were 1 month to 13.5 years[Average 55 month] except 3 patients, who were operated pneunectomy with thoracoplasty at the same time. 4. The total number of thoracoplasty were 19, because in 2 patients, we operated 2 steps, and we failed in 6 cases, so the success rate was 68.5%. 5. In failure analysis of 6 cases, the cause were obliteration failure in 3 cases, inadequete drainage in 1 case, and in the other 1 case was mixed type. 6. From 1990 to 1991, there were no death associated with operation and there were 1 failure, so the success rate was greatly improved. 7. The bronchopleural fistula or spontaneous rupture of trachea were seen in 12 cases, and the success rate was high in absent cases.

• Structural Engineering and Mechanics
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• v.47 no.1
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• pp.45-58
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• 2013

In structural reliability analysis, the response surface method is a powerful method to evaluate the probability of failure. However, the location of experimental points used to form a response surface function must be selected in a judicious way. It is necessary for the highly nonlinear limit state functions to consider the design point and the nonlinear trend of the limit state, because both of them influence the probability of failure. In this paper, in order to approximate the actual limit state more accurately, experimental points are selected close to the design point and the actual limit state, and consider the nonlinear trend of the limit state. Linear, quadratic and cubic polynomials without mixed terms are utilized to approximate the actual limit state. The direct Monte Carlo simulation on the approximated limit state is carried out to determine the probability of failure. Four examples are given to demonstrate the efficiency and the accuracy of the proposed method for both numerical and implicit limit states.

• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.6
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• pp.201-212
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• 2007

This study presents experimental results of Steel-PSC mixed structural system having front-rear plate connection between Steel and Prestressed Concrete. Two kinds of Steel-PSC mixed structural system of 5.4m length were tested to evaluate flexural behaviors under four point loading, and 4 kinds of specimens with and without prestressing force at R & L type connection were tested to observe the shear behavior. Based on the test results of load-deflection curves and failure modes of specimens, it is found that the proposed L shape connection with front-rear plate connection between Steel and Prestressed Concrete has higher strength and stiffness. From the study, Steel-PSC mixed structural system with L shaped connection has a better structural performance in connection part.

• The Journal of Korean Obstetrics and Gynecology
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• v.32 no.3
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• pp.1-19
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• 2019

Objectives: To select the optimal ranges showing obvious synergic anti-osteoporotic potential after adjust mixed formula consisted of Morindae Radix (MR) and Cistanchis Herba (CH) as compared with those of each single formula or risedronate sodium (RES) using bilateral ovariectomized (OVX) female mice. Methods: Fourteen groups, total eight sham or 104 OVX mice were selected based on the body weights at 34 days after OVX surgery. After that, 9 types mixed compositions, single formula of MR and CH, and RES were orally administered for 35 days. And we measured changes in body weight and gain, femur weight, bone mineral density (BMD), bone strength (failure load) and mineral content - calcium (Ca) and inorganic phosphorus (IP), osteocalcin contents and bone specific alkaline phosphatase (bALP) activities of all mice. Results: The OVX-induced estrogen-deficient osteoporotic signs were significantly inhibited by 35 days of continuous oral treatment of all treated mice as compared with OVX control mice. Especially, MR:CH 1:3 and 1:1 mixed formula treated mice showed significantly more favorable inhibitory activities against estrogen-deficient osteoporosis symptoms as compared to those of each single formula of MR and CH. Although RES also ameliorated the decreases of the femur BMD, strength and trabecular bone architectures through the inhibited the increases of bone turnover, but they did not critically influenced on the bone formations. Conclusions: The results suggest that MR:CH 1:3 mixed formula showed somewhat lower anti-resorptive effects as compared to those of RES, but they also showed bone formation effects. therefore, it is expected that MR:CH 1:3 mixture will be promising as a potent protective agents for relieving the osteoporosis in menopausal women.

• Restorative Dentistry and Endodontics
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• v.29 no.3
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• pp.281-287
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• 2004

The purposes of this study were to evaluate the effect of adhesive property on microtensile bond strength and to determine the failure mode. Flat occlusal dentin surfaces were prepared using low-speed diamond saw. The dentin was etched with 37％ phosphoric acid. The following adhesives were applied to the etched dentin to manufacturer's directions： Scotchbond Multi-Purpose in group SM, Prime＆Bond NT in group NT, Scotchbond Multi-Purpose followed by Tetric-flow in group TR. After adhesive application, a cylinder of resin-based composite was built up on the occlusal surface. Each tooth was sectioned vertically to obtain the $1{\;}{\times}{\;}1\textrm{mm}^2$ "sticks". Microtensile bond strength were determined. Each specimen was observed under stereomicroscope and scanning electron microscope (SEM) to examine the failure mode. Data were analyzed using one way ANOVA. The results of this study were as follows：1. The microtensile bond strength value were：group SM ($18.98{\pm}3.01MPa$). group NT ($16.01{\pm}4.82MPa$) and group TR ($17.56{\pm}3.22MPa$). No significant statistical differences were observed among the groups (P>0.05). 2. Most of specimens showed mixed failure. In group TR, there was a higher number of specimens showing areas of cohesive failure in resin.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.129-133
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• 2000

The purpose of this paper is to develope concrete which presents self-damage as soon as the crack by external force occur. In experiment, when concrete specimens inserted glass filled with mixed liquid into were loaded, glass tube was break and crack around became red color. Failure properties were investigated according to type, location of sensor and existence of reinforced bar.