• Journal of Institute of Control, Robotics and Systems
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• v.18 no.2
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• pp.141-148
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• 2012

This paper proposes fault tolerant gaits of a quadruped robot with feet of flat shape. Fault tolerant gaits make it possible for a legged robot to continue static walking against a leg failure. In the previous researches, it was assumed that a legged robot had feet that have point contact with the surface. When the robot is endowed with feet having flat shape, fault tolerant gaits can show better performance compared with the former gaits, especially in terms of the stride length and gait stability. In this paper, fault tolerant gaits of a quadruped robot against a locked joint failure are addressed in straight-line motion and crab walking, respectively.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.557-560
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• 2004

This paper is to investigate the fire endurance of high performance concrete with the contents of cellulose fiber. According to test results, the use of CL lead to decrease in fluidity. For compressive strength, the use of CL had no influence on compressive strength. For spalling properties, plain concrete showed a severe spalling failure. The use of CL protected from spalling of concrete, but most specimens had scale failure and partial destruction of specimens. This is due to the insufficient fiber length and diameter of CL fiber, which was unable to discharging the internal vapour pressure. For this reason, CL fiber can not be used to protect from spalling oh high performance concrete. Residual strength was observed to $5\~7\%$ of original strength.

• Journal of Korean Institute of Industrial Engineers
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• v.22 no.4
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• pp.619-631
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• 1996

This paper describes an approach for the incorporation of maintenance times into a hierarchical scheduling for a failure prone flexible manufacturing system. The maintenance should not be performed too often because of the resulting reduction of capacity. Most manufacturing systems are large and complex. It is natural to divide the control into a hierarchy consisting of a number of different levels. Each level is characterized by the length of the planning horizon and the kind of data required for the decision making process. The goal of the analysis reported here is to calculate the production requirements while the machines fail and are repaired at random times. The machine failure and preventive maintenance are considered simultaneously.

• Clinical Endoscopy
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• v.57 no.2
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• pp.263-267
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• 2024

Technical failure of endoscopic ultrasound-guided gallbladder drainage (EUS-GBD) is often attributed to device failure. To rectify this problem, we developed a single-pigtail plastic stent (SPPS) for EUS-GBD. We retrospectively reviewed the cases of four patients who underwent EUS-GBD for acute cholecystitis. To prepare the SPPS, a 7.5-Fr endoscopic nasobiliary drainage tube was cut to an appropriate length. The use of SPPS during EUS-GBD was successful from both technical and clinical standpoints. The SPPS spontaneously detached 57 days after the procedure in patient 4 and 412 days after the procedure in patient 1. Patient 1 developed cholecystitis after 426 days and was managed with antibiotics. The other three patients did not develop any complications after surgery. In conclusion, we designed a new SPPS dedicated to EUS-GBD and established its technical feasibility and clinical effectiveness.

• Journal of Chest Surgery
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• v.25 no.1
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• pp.86-95
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• 1992

We have performed surgical operations for 184 primary lung carcinomas over a 10 year period from December, 1979 to December, 1990 at the department of Thoracic and Cardiovascular Surgery, Yonsei University College of Medicine, Seoul, Korea. We have reviewed 77 cases confirmed to be dead in the post-operative follow-up period among 184 cases. There were 68 males and 9 females [M: F=7.56: 1], with 76.62% ranging between 50 to 70 years old There were 50 cases[64.94%] of squamous cell carcinoma, 15[19.48%] of adenocarcinoma, 4[5.19%] of large cell carcinoma, 4[5.19%] of mixed cell carcinoma 3 [3.90%] of small cell carcinoma % 1 case of bronchoalveolar cell carcinoma. There were 25 cases[32.47%] in stage I, 12 [15.58%] in stage II 32 [41.56%] in stage IIIa and 8 [10.39%] in stage IIIb according to the new international staging system for lung cancer. The operative methods were left pneumonectomy in 38 cases, right pneumonectomy in 21, bilobectomy in 5, lobectomy in 12, and wedge resection in one case.ase. There were 9 operative mortalities; one case by bleeding, 5 cases by respiratory failure, one case by bleeding & renal failure, one case by empyema thoracis with BPF and one case by brain metastases. The actuarial mean survival length was 14.636$\pm$18.188months overall and 16.441$\pm$18. 627months in 68 cases excluding 9 operative deaths. The actuarial mean survival length was 18.568$\pm$11.057 months in 43 squamous cell carcinomas, 14.385$\pm$11.057 months in 14 adenocarcinomas, 10.250$\pm$8.884months in 4 large cell carcinomas and 12.250$\pm$17.193months in 4 mixed cell carcinomas. The actuarial mean survival length was 14.051$\pm$16.963months in 59 pneumonectomy cases, 15.200$\pm$12.478 months in 5 bilobectomy cases, 18.417$\pm$26.026months in 12 lobectomy cases. The actuarial mean survival length was 28.952$\pm$25.738months in 22 stage I cases, 19. 455$\pm$16.723months in ll stage II cases, 8.633$\pm$6.584months in 29 stage IIIa cases and 6. 167$\pm$4.355months in 6 stage IIIb cases. The differences of actuarial mean survival length according to the stages were statistically significant [a=0.003]

• Journal of Dental Rehabilitation and Applied Science
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• v.28 no.1
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• pp.1-13
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• 2012

Short implants are used in parts which have anatomical structures like maxillary sinus, inferior alveolar nerve and limited alveolar height due to severe alveolar bone resorption. In these case, there are no need of additional bone augmentation so there are advantages like reduced entire treatment time, reduced patient's discomfort and protection of important anatomical structures. The aim of this study is, in implants whose length is less than 10mm, to analyze the impact of implant length, diameter, location of implant placement, presence of bone graft, presence of prosthesis splinting on survival rates and marginal bone resorption. The samples used in this study were 227 implants, less than 10mm, placed in 137 patients in Wonkwang university dental hospital implant center. From dental charts the information about implant length, diameter, location of implant placement, presence of bone graft, presence of prosthesis splinting were obtained. Emago advanced v5.6(Oral diagnostic systems, Amsterdam, The Netherlands)program was used to measure the amount of marginal bone resorption. Out of total 227 implants, resulting in 96.5 % of survival rate. There was a tendency toward higher failure rates for the maxilla and bone graft site. No significant difference in marginal bone resorption was found associated with length of implants(p>0.05) and neither with the diameter of implants. Among the risk factors examined, more failure rates of short implants can be attributed to poor bone quality in the maxilla and presence of bone graft. At implants under 10mm, length, diameter, location of implant placement, bone graft and splinting of prosthesis didn't affect marginal bone loss.

• Journal of the Korea Concrete Institute
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• v.16 no.1 s.79
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• pp.94-101
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• 2004

This study shows the test results of seven RC beams retrofitted with modified polymer system and parametric study about the effects of tensile strength of retrofitting materials by analytical method on the flexural behavior. The main parameters are the retrofitted depth and length. The beams are loaded to the failure by four-point loading. Test results show that the effect of the retrofitted length on the structural behavior is more significant than that of depth. As the retrofitted depth is increased, the beams represents the brittle failure mode The non-linear analysis is carried out to grasp the effect of the tensile strength of retrofitting material on the structural behavior. As the retrofitted depth and length are increased, the tensile strength becomes more effective so these parameters should be considered to determine the retrofitted area. The analytical results show that failure strength is less than that of experimental results, but the stiffness is vice versa.

• Journal of the Korean GEO-environmental Society
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• v.8 no.1
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• pp.33-40
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• 2007

Engineering behaviour of uplift-resisting ground anchors constructed in weathered rocks has been investigated by carrying out a series of full scale pull-out tests. The anchor was to resist uplift forces (buoyancy) associated with high groundwater table acting on the basement of a rail way station. The study has included the ultimate pull-out capacity of the anchors and shear stress transfer mechanism at the anchor-ground interface. The pull-out tests were conducted by changing bonded lengths of the anchor (2~7 m) and diameter of drilled borehole (108~165 mm) to investigate their effects on the behaviour of the anchor. The measured results showed that the ultimate capacity of the anchors was increased with an increase in the bonded length, diameter of drilled borehole as expected. The ultimate capacity of the anchors deduced from the pull-out tests ranged from 392 to 1,569 kN, depending on the above-mentioned factors. This corresponds to the interface shear strength of about 227~505 kPa. Interface shear stresses deduced from the pull-out test showed that the larger the pull-out force, the larger the mobilisation of the interface shear strength. The failure mode of the anchors heavily depended on the bonded lengths of the anchors. When the bonded length was short (2~3 m), a cone-type failure was observed, whereas when the bonded length increased (5~7 m), failure developed at the grout-ground interface.

• Journal of the Korea Institute of Building Construction
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• v.9 no.6
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• pp.141-149
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• 2009

The objective of this study was to propose a development length equation for bottom and top GFRP bars. Including the bottom and top GRPP bars, a total of 104 modified pullout tests were completed. The test variables were embedment length (15, 30, 45db), net cover thickness (0.5~2.0db), different GFRP bar types, and bar diameters (10, 13, 16mm). The average bond stresses were determined based on the modified pullout test results. Two variable linear regression analyses were performed on the results of the average bond stresses. Utilizing the 5% fractile concept, a conservative development length design equation was derived. The design equation of the development length for bottom and top GFRP bars was proposed and the design equation derived in this study was compared to the ACI 440.1R-06 committee equation.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.5
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• pp.59-67
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• 2014

In tension lap splices of straight deformed bars, KCI Code (KCI2012) and ACI Code (ACI318-11) requires that the lap lengths for class B splice are 1.3 times as development length. KCI2012 contains development length provisions for the use of headed deformed bars in tension and does not allow their tension lap splices. The purpose of this experimental study is to evaluate that KCI2012 equation for the development length, $l_{dt}$, of headed bars can be used to calculate the lap length, $l_s$, of headed deformed bars in grade SD400 and SD500, having specified yield strength of 400 and 500 MPa. Test results showed that specimens with $l_s$ equal to $1.3l_{dt}$ had maximum flexural strengths as 1.16~1.31 times as the nominal flexural strengths, flexural failure mode, and ductility. These observations indicate that $1.3l_{dt}$ is suitable to the tensile lap length of headed deformed bars in grade SD400 and SD500.