• Journal of Korean Foot and Ankle Society
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• v.8 no.1
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• pp.71-75
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• 2004

Purpose: The purpose of this study was to evaluate retrospectively the clinical results of closed reduction and percutaneous screw fixation for unstable injuries on stress radiographs in subtle injuries of Lisfranc joint. Materials and Methods: From June 1997 to March 2003, 6 cases of unstable injuries on stress radiograph in subtle injuries of Lisfranc joint were treated by percutaneous cannulated screw fixation after closed reduction. All cases were injuried by indirect force (twisting injury). The average diastasis between the 1st and 2nd metatarsal base was 3 mm (2-4 mm) on initial nonweight bearing AP radiograph. The average follow-up period was 20 months. Clinical evaluation was assessed according to the American Orthopedic Foot and Ankle Society (AOFAS) midfoot score. Results: The AOFAS midfoot score was average 86 (80-90) points. The average diastasis between 1st and 2nd metatarsal base was 2 mm (1-3 mm) on weight bearing AP radiograph in final follow up. The final diastasis was increased slightly than diastasis in initial postoperative radiographs. But the clinical results were good. There was no correlation between the degree of diastasis and the clinical results. On weight bearing lateral radiograph, the average difference with normal foot in the distance between plantar aspect of 5th metatarsus and medial cuneiform was 2 mm (0-3 mm). One case had mild arthritic change on the radiographs. Conclusion: When the Lisfranc injuries, especially in the subtle injuries were suspicious, the stress views are helpful to assess stability of the Lisfranc injuries and planning of treatment. For unstable injuries on stress radiographs in subtle injuries of Lisfranc joint, closed reduction and percutaneous screw fixation is useful method to expect good clinical results.

• Geomechanics and Engineering
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• v.8 no.6
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• pp.801-810
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• 2015

The ultimate pullout capacity under inclined dynamic loading is an important measure of the destruction degree of vertical screw piles (anchors) under dynamic actions. Based on the static and dynamic tests on two kinds of model screw piles, the ultimate bearing capacity was researched considering different distance-width ratio of blade (D/W) and preloading ratio. The results compared well with other experimental data available in the literature. This research reveals that D/W might determine the failure model of the piles (anchors), for example D/W = 3.14 or 5; a critical dynamic-static loading ratio (DSLR) existed in the experiments. The critical DSLR was reached under the conditions of 40%~60% preloading (D/W = 3.14) or 20%~40% preloading (D/W = 5), respectively.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.333-338
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• 2000

This paper presents an experimental study and numerical thermal deformation analysis in the home appliance, Video Cassette Recorder. Analyzing the change axial force of a set screw according to the change of temperature in the drum assembly, we can determine the initial torque in tightening set screw. The torque will have the preload boss not be separated from the bearing. Also we conduct the fundamental experiment to constitute a boundary condition of the numerical analysis. With the result of this study, we can change the material of preload boss, copper, for aluminum.

• Journal of Trauma and Injury
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• v.36 no.3
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• pp.265-268
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• 2023

Ankle fractures with syndesmotic injuries often require fixation, where metal screw fixation is a popular method. However, as the patient begins weight-bearing, most syndesmotic screws tend to loosen or break, and removal of such screws has been challenging for the surgeons, as the available techniques require predrilling or trephination and are associated with risks of bone damage. This study presents a case with technical tip for the removal of broken tricortical-fixed non-cannulated syndesmotic screws. It implements the generation of a small cortical window in the medial distal tibia and the use of pliers to engage the screw tip and remove through the medial side. The technique presented in the current study overcomes these limitations and facilitates minimal bone damage and reduced exposure to radiation.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.820-825
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• 2007

A ballscrew-linear motion(LM) guide is well-described by its name: it is a LM guide that runs by ballscrew. It consists of LM rail, LM block, end plate, screw, nut and bearing balls. The ballscrew-LM guide has many advantages compared with conventional LM guide. The high efficiency achieved with rolling contact devices permits the employment of antibacklash methods. The balls provide the only physical contact between nut rail and block and ball screw and nut replacing the sliding friction with a rolling motion. The life of the ballscrew-LM is determinated by the balls. The objective of this paper is to introduce the design of the ballscrew-LM with the safety working load.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.10a
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• pp.342-349
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• 2002

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.360-368
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• 2010

Noise and vibration triggered by pile driving in a construction site not only give hard time to the surrounding areas but could also cause residents nearby to file civil complaints to the extent of bringing construction to a halt. To deal with this issue, construction engineers have worked strenuously to develop low noise & low vibration pile methods. A noise & vibration-free screw concrete pile method proposed in this study is one of the successful outputs. It penetrates pile underground by rotating and pressing in body of the pile to avert noise and vibration while maximizing bearing capacity. A prototype of noise and vibration-free precast screw pile method was manufactured, which is not seen anywhere in Korea and elsewhere, and have undergone pilot tests twice to determine construction method.

• The KSFM Journal of Fluid Machinery
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• v.10 no.3 s.42
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• pp.47-54
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• 2007

A rotordynamic analysis was performed with a dry vacuum pump, which is a major equipment in modem semiconductor and LCD manufacturing processes. The system is composed of screw rotors, lobes picking air, helical gears, driving motor, and support rolling element bearings of rotors and motor. The driving motor-screw rotor system has a rated speed of 6,300rpm, and was modeled utilizing a rotordynamic FE method for analysis, which was verified through the results of its 3-D finite element model. As loadings on the bearings due to the gear action were significant in the system considered, each resultant bearing load was calculated determinately and indeterminately by considering the generalized forces of the gear action as well as the rotor itself. Each resultant bearing loading was used in calculating each stiffness of rolling element bearings. Design goals are to achieve wide separation margins of critical speeds and favorable unbalance responses of the rotor in the operating range. Then, a complex rotordynamic analysis of the system was carried out to evaluate its forward synchronous critical speeds, whirl natural frequencies and mode shapes, and unbalance responses under various unbalance locations. Results show that the entire system is well designed in the operating range. In addition, the procedure of rotordynamic analysis for dry vacuum pump rotor-bearing system was proposed and established.

• Journal of Korean Foot and Ankle Society
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• v.1 no.2
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• pp.112-118
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• 1997

Tarsometatarsal fracture-dislocation is uncommon but severe lesion. Since this lesion is sometimes difficult to recognize by roentgenography, it is easily overlooked. Three patients were treated with open reduction and internal fixation with 3.5 mm cannulated screw and K-wire, two had treatment with open reduction and internal fixation with 3.5 mm cannulated screw only and two had treatment with dosed reduction and short leg cast only between January 1994 and May 1996. The duration of follow-up ranged from twelve to twenty-nine months after the diagnosis. Results were assessed by a subjective questiormaire, physical examination, and radiographic analysis. Multiple fixation techniques for maintaining the reduction of tarsometatarsl joint have been introduced. We recent]y used the 3.5 mm cannulated screw for internal fixation of the tarso-first and second metatarsal fracture-dislocation. We think cannulated screw fixation has several advantages; 1. The cannulated screw fixation is more rigid than the K-wire fixation. 2. There is an decreased risk of screw breakage with early weight bearing. 3. It is possible to compress the involved joints, if necessary. There were no disability in all patients. One patient who was treated with delayed open reduction and internal fixation with 3.5 mm cannulated screw and K-wire had a radiographic mild degenerative arthritis. And one patient who was treated with dosed reduction and short leg cast had a mild metatarsus adductus. But. these two patients were symptom free. There was no correlation between the severity of the diastasis and the patient s functional result.

• Journal of the Korean GEO-environmental Society
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• v.11 no.7
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• pp.15-24
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• 2010

Noise and vibration due to pile driving cause residents nearby construction sites to file civil complaints and to the extent of bringing construction to a halt. To deal with this issue, construction engineers have worked strenuously to develop several types of low noise & low vibration pile methods. In this study, a new noise and vibration-free precast screw pile method proposed as a low noise & low vibration pile. It penetrates into the ground by rotating and pressing to avert noise and vibration while maximizing bearing capacity. A prototype of noise and vibration-free precast screw pile method was manufactured, which is not seen anywhere in Korea and elsewhere, and have undergone pilot tests twice to determine construction method. Based on this study, features of the noise & vibration-free screw pile method, production of screw concrete pile prototype, two pilot tests and subsequent construction method were determined.