• Journal of the Korean Geotechnical Society
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• v.18 no.1
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• pp.113-125
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• 2002

Ground improvement technique of cement stabilization via Deep Soil Mixing with dry cement is gaining popularity, particularly in Japan and other parts of Southeast Asia and in Scandinavia. Cement can be mixed with deep soft clay deposits, typical of marine environments, to improve the bearing capacity and/or reduce the compressibility of the material so that an otherwise poor site can be developed. However, the strength/deformation behaviour and resulting soil structure of the clay-cement mixture is presently not well understood with respect to both dry and wet mix methods. An extensive laboratory test was carried out to determine the mechanical characteristics of kaolin-cement, with some brief examination of the effects of curing environment. Laboratory tests include triaxial tests, unconfined compression tests, isotropic consolidation testis and oedometer tests. Cement contents up to 10 percent were considered and water curing was employed. Samples were cured for 7 to 112 days while submerged in distilled water. Conventional laboratory tests were also performed. In this paper, the laboratory testing program is described and various sample preparation techniques are discussed. Preliminary triaxial compression test results and trends at varying moisture contents, cement contents, confining pressures and curing times will be presented.

• Journal of Korean Foot and Ankle Society
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• v.3 no.1
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• pp.26-32
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• 1999

Fractures of the tibial pilon are the severe injuries to the ankle joint resulted from axial compression, shear and/or rotational forces. The pilon fractures have been difficult in management due to the severe comminution of articular surface and frequent soft tissue problem. Among many treatment options, limited internal fixation of the tibia with long screws and multiple pins augmented with external fixation or casting provide adequate stabilization without soft tissue compromise. Among the patients of pilon fracture admitted to our hospital from March 1993 to March 1997 who treated by limited internal fixation and external fixation or casting, 25cases are included who could be follow up for more than 10months. According to Ruedi and Allgower, typeI 3cases, typeII 14cases, typeIII 8cases. The authors analyzed the clinical and radiological results of the tibial pilon fractures according to Magnusson. The results were as follow. 1. 10cases at Ruedi-Allgower typeII were obtained above fair and 5cases at Ruedi-Allgower typeIII were obtained above fair. 2. The postoperative complications were skin problem(3cases) and infection(2cases), which were treated by antibiotics and flap surgery.

• Applied Chemistry for Engineering
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• v.5 no.3
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• pp.537-546
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• 1994

The physical characteristics of polymer modified asphalt depend on many parameters, such as, the polymer nature, polymer content and the asphalt properties. The objective of this study is to investigate the temperature susceptibility of polymer modified asphalt. The asphalts employed in this study were two different grades : a soft(200/300) grade and a hard(85/100) grade. And chlorinated polyethylene of two different characteristics were used : plastomer(Tyrin 2552) and elastomer(Tyrin CM0730). Temperature susceptibility of asphalt is a fundamental feature for characterizing asphalt and modified asphalt. It can be quantified by the penetration index(PI) and pen-vis number(PVN). These indices were obtained from the measurements of penetration and viscosity of the asphalt samples. For both of asphalts, the addition of the polymers increases the value of PI and PVN. Plastomer modified asphalt shows higher value of PI and PVN than elastomer modified asphalt. Soft grade shows more temperature susceptibility than hard grade at elevated temperatures.

• Magazine of the Korean Society of Agricultural Engineers
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• v.30 no.4
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• pp.94-108
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• 1988

The use of geotextile as reinforcing materials in soil structures has become widespread throughout the world. Geotextile reinforcement has been used in retaining walls, roadbed, embankment stabilization and especially reinforcement of soft foundation, and so on, In the past, however, its design and construction have been performed empirically. In this study, laboratory model tests were carried out in order to investigate the effects of geotextile rein- forcement on vertical and horizontal displacement and other characteristics in soft founda- tions. The experiments were executed in eight treatments ;no geotextile between embank - ment and subsoils, and seven geotextiles with different tensile strength. And such factors as the loading conditions, the tensile strength of geotextiles, the ingredient of geotextiles and the elapsed time were investigate in this study. And the analytical method were executed in order to study the stress and behavior of geotextile - reinforced soil structure by the nonlinear elasto - plastic finite element model. The following conclusions were drawn from this study. 1. Geotextile reinforcement reduced the effects of banking loads on subsoils more effectively with the increase of their tensile strength. 2. As the tensile strength of geotextiles was increase, the rate of the initial vertical disp - lacements of loading plate was reduced inverse proportional to loads, Rowever, the effect of loading was reduced when the loads exceed a certain limits, 3. The effect of reinforcement of nonwoven geotextile was 1.5-4.5 times larger than that of the woven geotextile with equivalent tensile strength. 4. The increased bearing capacity and the reduced settlement are proportioned as the tensile strength of geotextile. 5. The settlement at the long time loading were developed almost all, were completed after 10 days and the additional settlement were not developed since then. 6. The nonlinear elasto - plastic finite element method are accurate to predict the stresses and behayior of geotextile - reinforced soil structures.

• Journal of Korean Foot and Ankle Society
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• v.28 no.1
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• pp.8-14
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• 2024

Purpose: Ankle fracture fixation is the gold standard of treatment but it does have its own complications. There is inadequate data regarding the comparative effectiveness of early vs. delayed fixation for open ankle fracture outcomes. This study compares the clinical and functional outcomes of open ankle fractures treated by early or delayed definitive fixation and identifies the limitations of both methods. Materials and Methods: All 73 patients enrolled in the study underwent surgical intervention within 24 hours of injury. The early fixation group (group A) consisting of 39 patients underwent definitive fixation as an index procedure, while the delayed fixation group (group B) consisted of 34 patients who underwent debridement and external fixator application as an index procedure and definitive fixation when soft tissue condition was conducive. All patients were evaluated at 2, 6, and 12 weeks postoperatively and then three monthly for a year. Results: Enneking and American Orthopaedic Foot and Ankle Society scores were markedly higher in the early fixation group at 6 months postoperatively (p-values <0.001 and 0.011, respectively). However, no discernible intergroup difference was evident at 12 months postoperatively. Between 6 and 12 months, group functional outcome scores were significantly different. At 6 months, there was a substantial difference in dorsiflexion between the two groups (p-values 0.001 and <0.001, respectively), but no difference was observed at 12 months postoperatively. At 6 and 12 months, group average plantar flexions were non-significantly different. Conclusion: Early definitive fixation of complex ankle fractures using a targeted approach produced promising results for lower grade open fractures (grades 1 and 2), and delayed definitive fixation, after initial external fixation to allow for soft tissue stabilization, produced promising results for higher grade open fractures (grades 3A and 3B). At 12-month follow-ups, clinical and functional outcomes achieved using these strategies were equivalent.

• Korean Journal of Cleft Lip And Palate
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• v.15 no.1
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• pp.1-10
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• 2012

Parry-Romberg syndrome(PRS) is a degenerative disease characterized by progressive hemifacial atrophy. A 10-year-old girl who had been treated for linear scleroderma at the dermatologic department visited the orthodontic department. The frontal facial photograph showed mild facial asymmetry. On the left side, mild atrophy of soft tissue, enophthalmos, cheek depression, and dry skin with dark pigmentation were observed. The radiograph showed the hypoplasia of both the maxilla and mandible on the left side. This case report describes the treatment of a patient with PRS for 7 years. To minimize the effect of progressive atrophy on the facial growth, a hybrid appliance was used. The facial photos and radiographic records were periodically taken to analyze the progression of PRS. Although it is impossible to prevent the progression of facial asymmetry, it appears to be possible to limit the atrophic effect. After the stabilization of PRS, the orthodontic treatment by the fixed appliance was performed. Additionally, autologous fat graft was performed three times at 6 month intervals. After the treatment, the patient had a confident smile and facial asymmetry was improved.

• Journal of the Korean Geotechnical Society
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• v.18 no.4
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• pp.159-165
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• 2002

Soil cement which is a mixture of soil, cement, and water has a broad range of applications since it is economical, ecological, and easy to use, repair, and reinforce. Its applications include pavements, stabilization of slopes, retaining walls, and improvements of soft ground to name a few. Other types of chemicals are often added to increase its strength. This study investigated unconfined compressive strength of cured soil cement mixed with New Soil Chemical(NSC). The investigation involved laboratory experiments under various conditions including soil type, cement content, and ratios of water to NSC. Results of the study show that NSC enhanced the unconfined compressive strength significantly, and the degree of enhancement was varied with test conditions.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.9
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• pp.576-583
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• 2004

This paper presents a buck circuit topology of high-frequency with a single switching device. It solved the problem which arised from hard-switching in high-frequency using a resonant snubber and operating under the principle of ZCS turn-on and ZVS turn-off commutation schemes. In the existing circuit, it has the voltage stress that is almost twice of input voltage in a free-wheeling diode. In the proposed circuit, it has the voltage stress that is lower than input voltage with modifing a location of free -wheeling diode. In this paper, it expained the circuit operation of each mode and analyzed feedback-loop stabilization. Also it confirmed the waveform of each mode with simulation result. The experiment result verified the simulation waveform and compared the voltage stress of a free -wheeling diode in the exsiting circuit with the voltage stress of that in the proposed circuit. Moreover, it compares and analyzes the proposed circuit's efficiency with the hard-switching circuit's efficiency according to the change of load current.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.684-691
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• 2004

Various researches have been undertaken to develope a method of enhancing consolidation. This study investigated the effect of ultrasound on consolidation through a series of laboratory experiments. The tests were conducted using a specially designed and fabricated equipments which can apply ultrasonic energy on a soil sample at consolidation test. Specimens were prepared using a centrifuge facility, and test conditions included ultrasonic power and treatment time. The results of the study show that the effect of ultrasonic energy on consolidation is significant. The degree of significance varies with the test conditions. It could be concluded that the study showed potential application of ultrasound to enhance consolidation.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.11
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• pp.501-506
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• 1997

This is to investigate the physical properties of the commercially available Soft, Thomas, Minerva, and Philadelphia cervical braces which are widely used in orthopedics, neurosurgery, and rehabilitation medicine clinics as assisting devices or physical stabilization of cervical vertebrates, to use as a basic data or designing new type brace. Tensile strengths were observed by universal mechanical measuring device and Thomas brace required the highest stress to break by tensile stress. Durabilities against continuous frictional forces were also determined, and Minerva brace demonstrated the longest frictional time until being perforated. and Thomas/minerva braces are superior to the other braces in the effect of the material property on the skin tissue, as the animal test. According to these results, polyethylene is recommendable as a frame and preparation of pores in the material is favorable to provide ventilation to skin.