• Geomechanics and Engineering
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• v.34 no.6
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• pp.623-636
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• 2023

This study utilized small-scale physical model tests to investigate the impact of different types of geosynthetics, including geocell, planar geotextile, and wraparound geotextile, on the behaviour of strip footings placed on 0.8 m thick soil fills and backfills with a slope angle of 70°. Bearing capacity and settlement of the footing and failure mechanisms are discussed and evaluated. The results revealed that the bearing capacity of footings situated on both unreinforced and reinforced slopes increased with a greater embedment depth of the footing. For settlement ratios below 4%, the geocell reinforcement exhibited significantly higher stiffness, carrying greater loads and experiencing less settlement compared to the planar and wraparound geotextile reinforcements. However, the performance of geocell reinforcement was influenced by the number and length of the geocell layers. Increasing the geocell back length ratio from 0.44 to 0.84 significantly improved the bearing capacity of the footing located at the crest of the reinforced slope. Adequate reinforcement length, particularly for geocell, enhanced the bearing pressure of the footing and increased the stiffness of the slope, resulting in reduced deflections. Increasing the length of reinforcement also led to improved performance of the footing located on wraparound geotextile reinforced slopes. In all reinforcement cases, reducing the vertical spacing between reinforcement layers from 100 mm to 75 mm allowed the slope to withstand much greater loads.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.22 no.4
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• pp.303-329
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• 2019

Intestinal failure (IF) is the critical reduction of the gut mass or its function below the minimum needed to absorb nutrients and fluids required for adequate growth in children. Severe IF requires parenteral nutrition (PN). Pediatric IF is most commonly due to congenital or neonatal intestinal diseases or malformations divided into 3 groups: 1) reduced intestinal length and consequently reduced absorptive surface, such as in short bowel syndrome (SBS) or extensive aganglionosis; 2) abnormal development of the intestinal mucosa such as congenital diseases of enterocyte development; 3) extensive motility dysfunction such as chronic intestinal pseudo-obstruction syndromes. The leading cause of IF in childhood is the SBS. In clinical practice the degree of IF may be indirectly measured by the level of PN required for normal or catch up growth. Other indicators such as serum citrulline have not proven to be highly reliable prognostic factors in children. The last decades have allowed the development of highly sophisticated nutrient solutions consisting of optimal combinations of macronutrients and micronutrients as well as guidelines, promoting PN as a safe and efficient feeding technique. However, IF that requires long-term PN may be associated with various complications including infections, growth failure, metabolic disorders, and bone disease. IF Associated Liver Disease may be a limiting factor. However, changes in the global management of IF pediatric patients, especially since the setup of intestinal rehabilitation centres did change the prognosis thus limiting "nutritional failure" which is considered as a major indication for intestinal transplantation (ITx) or combined liver-ITx.

• Nuclear Engineering and Technology
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• v.50 no.7
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• pp.1138-1147
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• 2018

Delayed hydride cracking (DHC) is an important failure mechanism for Zircaloy tubes in the demanding environment of nuclear reactors. The threshold stress intensity factor, $K_{IH}$, and critical hydride length, $l_C$, are important parameters to evaluate DHC. Theoretical models of them are developed for Zircaloy tubes undergoing non-homogenous temperature loading, with new stress distributions ahead of the crack tip and thermal stresses involved. A new stress distribution in the plastic zone ahead of the crack tip is proposed according to the fracture mechanics theory of second-order estimate of plastic zone size. The developed models with fewer fitting parameters are validated with the experimental results for $K_{IH}$ and $l_C$. The research results for radial cracking cases indicate that a better agreement for $K_{IH}$ can be achieved; the negative axial thermal stresses can lessen $K_{IH}$ and enlarge the critical hydride length, so its effect should be considered in the safety evaluation and constraint design for fuel rods; the critical hydride length $l_C$ changes slightly in a certain range of stress intensity factors, which interprets the phenomenon that the DHC velocity varies slowly in the steady crack growth stage. Besides, the sensitivity analysis of model parameters demonstrates that an increase in yield strength of zircaloy will result in a decrease in the critical hydride length $l_C$, and $K_{IH}$ will firstly decrease and then have a trend to increase with the yield strength of Zircaloy; higher fracture strength of hydrided zircaloy will lead to very high values of threshold stress intensity factor and critical hydride length at higher temperatures, which might be the main mechanism of crack arrest for some Zircaloy materials.

• Steel and Composite Structures
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• v.21 no.5
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• pp.1017-1029
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• 2016

When a welded circular hollow section (CHS) tubular joint is subjected to brace axial loading, failure position is located usually at the weld toe on the chord surface due to the weak flexural stiffness of the thin-walled chord. The failure mode is local yielding or buckling in most cases for a tubular joint subjected to axial load at the brace end. Especially when a cyclic axial load is applied, fracture failure at the weld toe may occur because both high stress concentration and welding residual stress along the brace/chord intersection cause the material in this region to become brittle. To improve the ductility as well as to increase the static strength, a tubular joint can be reinforced by increasing the chord thickness locally near the brace/chord intersection. Both experimental investigation and finite element analysis have been carried out to study the hysteretic behaviour of the reinforced tubular joint. In the experimental study, the hysteretic performance of two full-scale circular tubular T-joints subjected to cyclic load in the axial direction of the brace was investigated. The two specimens include a reinforced specimen by increasing the wall thickness of the chord locally at the brace/chord intersection and a corresponding un-reinforced specimen. The hysteretic loops are obtained from the measured load-displacement curves. Based on the hysteretic curves, it is found that the reinforced specimen is more ductile than the un-reinforced one because no fracture failure is observed after experiencing similar loading cycles. The area enclosed by the hysteretic curves of the reinforced specimen is much bigger, which shows that more energy can be dissipated by the reinforced specimen to indicate the advantage of the reinforcing method in resisting seismic action. Additionally, finite element analysis is carried out to study the effect of the thickness and the length of the reinforced chord segment on the hysteretic behaviour of CHS tubular T-joints. The optimized reinforcing method is recommended for design purposes.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.27 no.2
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• pp.178-183
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• 2001

Since the introduction of the concept of osseointegration, the success rate of dental implant has increased dramatically. So, the uses of dental implant in the treatment of partially or fully edentulous patients have played an important role in dental rehabilitation. Regardless of high success rate of dental implant, some amounts of fixtures cannot help failing. We can classify dental implant failure according to timing, causative factor, etc. This study is focused on dental implant fixture failure, occurring during preprosthetic stage. There are various reasons that cause implant failure on this periods, such as improper patient selection, poor bone quality, and periimplantitis, etc. We investigate the survival rate of 1058 fixtures, which installed in 306 patients in our clinic from January 1997 to December 1999, according to type, sex, location, fixture length and width, using Kaplan-Meier product-limit method and to compare each other with log-rank test. Overall survival rate was 96.80%, and 33 implants failed over the preprosthetic stage. Our survey data identified posterior location of mandible as being associated with implant failure(P<0.05).

• Journal of Korean Academy of Nursing
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• v.36 no.5
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• pp.853-862
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• 2006

Purpose: The purpose of this study was to identify the factors that influence the functional status of patients with heart failure. Method: A descriptive, correlational study design was used. The participants in this study were 260 patients with heart failure who were admitted at Y University and U University in Seoul, Korea. Between September 2005 and December 2005 data was collected by an interview using a questionnaire and from medical records. The Functional status was measured with KASI. Physical factors (dyspnea, ankle edema, chest pain, fatigue, and sleep dysfunction), psychological factors (anxiety and depression), and situational factors (self-management compliance and family support) were examined. Result: In general, the functional status, anxiety, depression, self-management compliance, and family support was relatively not good. The level of fatigue was highest and the level of ankle edema was lowest for physical symptom experiences. In regression analysis, functional status was significantly influenced by dyspnea(23%), age(13%), monthly income(7%), fatigue(3%), ankle edema(2%), depression(1%), and length of stay in the hospital(1%). These factors explained 50% of the variables in the functional status. Conclusion: These results suggest that psycho-physiological symptoms management should be a focus to improve the functional status in patients with heart failure.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.10
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• pp.3199-3210
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• 1996

The buckling and postbuckling behaviors were sutdied analytically and experimentally for stiffened laminated composite panels under compression loading. The panels with I-, blade, -and hat-shapeed stiffeners were investigated. In the analysis, the stiffened panels were anlyzed using the nonlinear finite element method combined with an improved arc-length method. The progressive failure analysis was done by adopting the maximum stress criterion and complete unloading failure model. The effects of the fiber angles were investigated on the buckling and postbuckling behaviors. In the experiment, the web and the lower cap of each stiffener were formed by the continuous lay-up of the skin for cocuring the stiffened panels. Therefore, the separation between stiffener and skin was not found in the junction part even after postbuckling ultimate load and the stiffened panels had excellent postbuckling load carrying capacity. A shadow moire thchnique was used to monitor the out-of-plane deformations of the panels. The piezoelectric films were attached to the panels to get the failure characteristics of the panel. The analytical results on the buckling load, postbuckling ultimate load, and failure pattern showed good agreement with the experimental results.

• Journal of the Korean Wood Science and Technology
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• v.39 no.5
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• pp.429-436
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• 2011

The selected physical and mechanical properties of non-certificated LVL circulated in domestic lumber market were investigated and compared to relevant standards. The tested LVL passed the moisture content and the soaking delamination rate limit as per domestic (KS) and Japanese standard (JAS). The evaluated mechanical properties were flatwise/edgewise bending strength, modulus of elasticity (MOE), horizontal shear and compressive strength. The 30 mm-thick LVL showed significantly higher bending strength than that of the 25 mm-thick LVL. The modulus of elasticity (MOE) showed same tendency in the results of bending strength. The edgewise bending strength and MOE were higher than that of flatwise bending strength and MOE. The horizontal shear strength values were also showed similar results to bending strength values. The tested results were compared each other and each products were graded according to JAS 701 grade specification. The failure mode of LVL in bending test showed the similar failure mode of solidwood that failed in a simple tension manner (splintery tension). The glue line failure was severe in 25 mm-thick specimens due to concentration of shear stress in layer discontinuity containing small voids and starved glue lines. In horizontal shear strength test, failure mode of LVL showed the typical horizontal shear failure. Compressive specimens failed with fiber crushing in company with apparent delamination that splitted along the length of the specimens. From the results, the complete bonding between lamination and consistency in thin veneer layer were considered as a critical factor in the mechanical properties of LVL. Moreover, the standard test procedure and specification for non-certificated LVL should be required to check the performance of uncertificated materials.

• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.5
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• pp.144-152
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• 2007

This study investigated the failure mechanism of RC beams strengthened with AFRP sheets. Total 5 half-scale RC beams were constructed and tested to estimate the effectiveness of various methods to prevent the debonding failure of AFRP sheets. From the experimental results, it was found that increasing bonded length or end U-wrappings does not prevent debonding failure. On the other hand, the beams with center U-wrappings and shear-keys reached the ultimate state with their sufficient performance. The center U-wrappings tended to control debonding of the longitudinal AFRP sheets because the growth of the longitudinal cracks along the edges of the composites was delayed. In case of shear-keys, it was sufficient to eliminate debonding and the beams failed by AFRP sheets rupture due to the sufficient bond mechanism.

• Structural Engineering and Mechanics
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• v.66 no.6
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• pp.783-792
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• 2018

This paper presents a detailed theoretical study of the sleeved compression members based on a mechanical model. In the mechanical model, the core protrusion above sleeve and the contact force between the core and sleeve are specially taken into account. Via the theoretical analyses, load-displacement relationships of the sleeved compression members are obtained and verified by the experimental results. On the basis of the core moment distribution changing with the increase of the applied axial load, failure mechanism of the sleeved compression members is assumed and proved to be consistent with the experimental results in terms of the failure modes and the ultimate bearing capacities. A parametric study is conducted to quantify how essential factors including the core protrusion length above sleeve, stiffness ratio of the core to sleeve, core slenderness ratio and gap between the core and sleeve affect the mechanical behaviors of the sleeved compression members, and it is concluded that the constrained effect of the sleeve is overestimated neglecting the core protrusion; the improvement of ultimate bearing capacity for the sleeved compression member is considered to be decreasing with the decrease of the core slenderness ratio and for the sleeved compression member with core of small slenderness ratio, small gap and small stiffness ratio are preferred to obtain larger ultimate bearing capacity and stiffness.