• The Journal of Engineering Geology
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• v.11 no.2
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• pp.163-174
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• 2001

For quantitative evaluation of geotechnical engineering properties such as rippability and diggability, clear interpretation on the subsUJiace velocity structures should be preceded by figuring out top soil, weathered and soft rock layers, shape of basement, fracture zones, geologic boundary and etC. from the seismic refraction data. It is very important to set up suitable field parameters, which are the configuration of profile and its length, spacings of geophones and sources and topographic conditions, for increasing field data Quality. Geophone spacing of 3 to 5m is reconunended in the land slope area of house land development site. In refraction tomography technique, the number of source points should be more than a Cluarter of available channel number of instrument and the subsurface structure interpretation can be decreased the artifact of inversion by topographic effect. Compared with core logging data, it is shown that the velocity range of the soil is less than 700m/s, weathered rock 700~1,200m/s, soft rock 1,200~1,800m/s on the velocity tomogram section. And the upper limit of P-wave velocity for rippability is estimated 1,200 to 1,800m/s in land slope area of gneiss.

• The Journal of Engineering Geology
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• v.16 no.2 s.48
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• pp.125-134
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• 2006

In order to establish the in-situ application of the artificial storage and recovery (ASR) technology which is used the property of the aquifer storage of groundwater. We carried out to the in-situ experiments such as borehole TV logging, pumping test and artificial hydraulic fracturing in volcanic island, Ulleungdo. In-situ experiments were conducted to divide the before- and after-hydraulic fracturing. Pumping test was achieved to confirm the two fracture zones, GL-13m and GL-21m, which are determined by the borehole TV logging. From the results of the before- and after-pumping tests, the hydraulic connectivity was confirmed to locate at GL-13m in the residual deposit zone of pumice media as alluvium. However, in the bedrock tone at GL-21m the hydraulic connectivity could be considered to faulty. Consequently, in this study area the artificial recharge has a little unsatisfied to geo-structural condition and desired to more detail investigation works.

• Clinics in Shoulder and Elbow
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• v.12 no.1
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• pp.33-37
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• 2009

Purpose: To evaluate the results of the compression plate fixation and autogenous bone graft in the management of humerus shaft nonunion. Materials and Methods: Eighteen cases were treated for humerus shaft nonunion using compression plate fixation and an autogenous iliac bone graft. The mean follow-up period was 28 months. Bony union was confirmed from the serial radiographs and the clinical outcomes were assessed according to ASES scoring system. Results: In 12 cases of initial plate fixation, the causes of nonunion were 6 cases of inadequate plate length, 2 with a broken plate, 2 with screw loosening, 1 infection and 1 noncompliance of a psychiatric patient. In 3 cases of initial intramedullary fixation, the cause of nonunion was a distraction of the fracture site. In 3 cases of external fixation, the cause of nonunion was inadequate fixation. All cases showed bony union after an average of 24 weeks. The clinical outcomes were 11 excellent, 6 good and 1 fair. Conclusion: In the treatment for nonunion, compression plate fixation with autogeneous bone graft after complete removal of the fibrous and necrotic tissue is believed to give satisfactory results.

• Tunnel and Underground Space
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• v.15 no.2 s.55
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• pp.119-128
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• 2005

Although the evaluation of the mechanical properties and behavior of jointed rock masses is very important for the design of tunnel and underground openings, it has always been considered the most difficult problem. One of the difficulties in describing the rock mass behavior is the selection of the appropriate constitutive model. This limitation may be overcome with the progress in discrete element software such as PFC, which does not need the user to prescribe a constitutive model for rock mass. In this paper, a 30\;m\;\times\;30\;m\;\times\;30\;m m jointed rock mass of road tunnel site was analyzed. h discrete fracture network was developed from the joint geometry obtained from core logging and surface survey. Using the discontinuities geometry from the DFN model, PFC simulations were carried out, starting with the intact rock and systematically adding the joints and the stress-strain response was recorded for each case. With the stress-strain response curves, the mechanical properties of jointed rock masses were determined. As expected, the presence of joints had a pronounced effect on mechanical properties of the rock mass. More importantly, getting the mechanical response of the PFC model doesn't require a user specified constitutive model.

• Journal of the Korean Geosynthetics Society
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• v.21 no.4
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• pp.69-78
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• 2022

Geotextile tubes are widely used to prevent erosion in coastal areas and to replace the backfill for shore slopes in the reclamation of land using dredged soil. In this study, The triaxial confining pressures were chosen as 10kPa, 50kPa, or 100kPa for the specimens reinforced with geotextile considering the condition in the site. The strain behavior under various compressive stresses was then identified. At strains 0% to 7%, the stress-strain behavior was the same due to the effect of initial strain hardening, in which the force was exerted according to the relaxation of the geotextile regardless of the confining pressure (≤100kPa). At strains of 7% or more, the specimen with the small confining pressure had smaller deformation under load, which increases the tensile resistance provided by the reinforcing geotextile. Brittle fracture was then observed due to strain softening and the deviator stress abruptly decreased. This is different from the phenomenon in which the shear strength increases as the confining pressure increases in general triaxial compression tests. In the geoxtile-confined tests, geotextiles are primarily subjected to tensile displacement. Thereafter, the modulus of elasticity increases rapidly, which exhibits the elastic behavior of the geotextile.

• Journal of the Korean Orthopaedic Association
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• v.54 no.6
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• pp.574-578
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• 2019

For the treatment of a bony Bankart lesion accompanied by an acute traumatic shoulder dislocation, anatomical reduction and stable fixation of the bone fragment and glenohumeral ligament are essential to avoid chronic instability or degenerative changes. If the Bankart lesion has large bony pieces or comminuted fragments, it can be difficult to perform precise and secure fixation of the big intraarticular fragment to the fracture site because of the limited visualization of the arthroscopic procedure. In addition, in the case of the open procedure, it requires an extensive surgical dissection to access the fractured fragment, which may cause surgical approach-related morbidity, such as neurovascular complications, delayed subscapularis healing, and increased risk of stiffness. This paper describes an alternative open suture anchor technique for a large bony Bankart lesion, which was secured anatomically with squared knots after a shuttle relay through bony tunnels and adjacent soft tissue and labrum. This technique can achieve anatomical and firm fixation under direct vision, and reduce the number of surgery related morbidities.

• The Journal of the Acoustical Society of Korea
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• v.42 no.6
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• pp.559-564
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• 2023

It is known that change in the bone strength of cortical bone constituting the outer shell of long bones such as the tibia or radius due to aging and osteoporosis is a risk factor for fracture. In this study, the group velocity of time-reversed Lamb waves generated in tibial cortical bone in vivo was measured using a time reversal method, and the correlations of the group velocity with the cortical bone thickness (cTh) and cortical bone mineral density (cBMD) closely related to the bone strength were investigated. It was found that the group velocity of time-reversed Lamb waves measured in the right tibia of 7 subjects showed a very high correlation, r = 0.90 (p < 0.0001), with the cTh and a relatively low correlation, r = 0.69 (p < 0.0001), with the cBMD. A limitation of this in vivo study is that the group velocity of time-reversed Lamb waves was measured for a normal group consisting of only 7 healthy adults. In the future, if the clinical usefulness of the time-reversed Lamb wave is demonstrated by follow-up studies on normal and osteoporotic groups consisting of a large number of healthy adults and osteoporotic patients, respectively, it is expected to improve the reliability of quantitative ultrasound technology for osteoporosis diagnosis. In addition, it is necessary to expand the skeletal site for measuring the group velocity of time-reversed Lamb waves not only to the tibia but also to the femur or radius.

• Economic and Environmental Geology
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• v.38 no.6 s.175
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• pp.675-687
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• 2005

The rocks of the five storied stone pagoda in the Jeongrimsaji temple site are 149 materials in total with porphyritic biotite granodiorite. They include pegmatite veinlet, basic xenolith and evenly developed plagioclase porphyry. This stone pagoda has comparably small fracture and cracks which are farmed in the times of rock properties, but surface exfoliation and granular decomposition are in process actively since the rocks are generally weakened from the influence of air contaminants and acid rain. Structural instability of constituting rocks in the 4th roof materials are observed to occur from distortion and tilt. Such instability is judged to threat stability of the upper part of the stone pagoda. Also, chemical weathering is operating even more as the contaminants, ferro-manganese hydroxides eluted from water-rock interaction on the rock surface. Most of the rock surface is covered with yellowish brown, dark black and light gray contaminants, and especially occur in the lower part of the roof rocks on each floor. The roof underpinning rocks are severe in surface pigmentation from manganese hydroxides and light gray contaminants. The surface of rocks lives bacteria. algae, lichen, or moss and diverse productions in colors of light gray, dark Bray and dark green. Grayish white crustose lichen grows thick on the surface with darkly discolored by fungi and algae in the first stage on basement rocks, and weeds grows wild on the upper part of each roof rocks. This stone pagoda must closely observe the movements of the upper part rock materials through minute safety diagnosis and long term monitoring for structural stability. Especially since the surface discoloration of rocks and pigmentation of secondary contaminants are severe, establishment of general restoration and scientific conservation treatment are necessary through more detailed study for this stone pagoda.

• Economic and Environmental Geology
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• v.37 no.5
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• pp.569-583
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• 2004

The rock properties of the West pagoda in the Gameunsaji temple site are composed mainly of dark grey porphyritic granodiorite with medium grained equigranular texture and developed with small numerous dioritic xenoliths. These xenoliths occurred with small holes due to different weathering processes. As a weathering results, the rock properties of this pagoda occur wholly softened to physical hardness because of a complex result of petrological, meteorological and biological causes. Southeastern part of the pagoda deteriorated seriously that the surface of rock blocks showed partially exfoliations, fractures, open cavities in course of granular decomposition of minerals, sea water spray and crystallization of salt from the eastern coast. The Joint between blocks has small or large fracture cross each other, contaminated and corrupted for inserting with concrete, cement mortar, rock fragments and iron plates, and partially accelerated coloration and fractures. There are serious contamination materials of algae, fungus, lichen and bryophytes on the margin and the surface on the roof stone of the pagoda, so it'll require conservation treatment biochemically for releasing vegetation inhabiting on the surface and the discontinuous plane of the blocks because of adding the weathering activity of stones and growing weeds naturally by soil processing on the fissure zone. Consisting rock for the conservation and restoration of the pagoda would be careful choice of new rock properties and epoxy to reinforce for the deterioration surfaces. For the attenuation of secondary contamination and surface humidity, the possible conservation treatments are needed.

• Restorative Dentistry and Endodontics
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• v.25 no.1
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• pp.46-55
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• 2000

During bonding procedure of composite resin, the prepared cavity can be contaminated by saliva. In this study, marginal microleakage and shear bond strength of a composite resin to primed enamel and dentin treated with artificial saliva(Taliva$^{(R)}$) were evaluated. For the marginal microleakage test, Class V cavities were prepared in the buccal surfaces of fifty molars. The samples were randomly assigned into 5 groups with 10 samples in each group. Control group was applied with a bonding system (Scotchbond$^{TM}$ Multi-Purpose plus) according to manufacture's directions without saliva contamination. Experimental groups were divided into 4 groups and contaminated with artificial saliva for 30 seconds after priming: Experimental 1 group ; artificial saliva was dried with compressed air only, Experimental 2 group ; artificial saliva was rinsed and dried. Experimental 3 group ; cavities were etched with 35% phosphoric acid for 15 seconds after rinsing and drying artificial saliva. Experimental 4 group ; cavities were etched with 35% phosphoric acid for 15 seconds and primer was reapplied after rinsing and drying artificial saliva. All the cavities were applied a bonding agent and filled with a composite resin (Z-100$^{TM}$). Specimens were immersed in 0.5% basic fuschin dye for 24 hours and embedded in transparent acrylic resin and sectioned buccolingually with diamond wheel saw. Four sections were obtained from one specimen. Degree of marginal leakage was scored under stereomicroscope and their scores were averaged from four sections. The data were analyzed by Kruscal-Wallis test and Fisher's LSD. For the shear bond strength test, the buccal or occlusal surfaces of one hundred molar teeth were ground to expose enamel(n=50) or dentin(n=50) using diamond wheel saw and its surface was smoothed with Lapping and Polishing Machine(South Bay Technology Co., U.S.A.). Samples were divided into 5 groups. Treatment of saliva-contaminated enamel and dentin surfaces was same as the marginal microleakage test and composite resin was bonded via a gelatin capsule. All specimens were stored in distilled water for 48 hours. The shear bond strengths were measured by universal testing machine (AGS-1000 4D, Shimaduzu Co., Japan) with a crosshead speed of 5 mm/minute. Failure mode of fracture sites was examined under stereomicroscope. The data were analyzed by ANOVA and Tukey's studentized range test. The results of this study were as follows : 1. Enamel marginal microleakage showed no significant difference among groups. 2. Dentinal marginal microleakages of control, experimental 2 and 4 groups were lower than those of experimental 1 and 3 groups (p<0.05). 3. The shear bond strength to enamel was the highest value in control group (20.03${\pm}$4.47MPa) and the lowest value in experimental 1 group (13.28${\pm}$6.52MPa). There were significant differences between experimental 1 group and other groups (p<0.05). 4. The shear bond strength to dentin was higher in control group (17.87${\pm}$4.02MPa) and experimental 4 group (16.38${\pm}$3.23MPa) than in other groups, its value was low in experimental 1 group (3.95${\pm}$2.51 MPa) and experimental 2 group (6.72${\pm}$2.26MPa)(p<0.05). 5. Failure mode of fractured site on the enamel showed mostly adhesive failures in experimental 1 and 3 groups. 6. Failure mode of fractured site on the dentin did not show adhesive failures in control group, but showed mostly adhesive failure in experimental groups. As a summary of above results, if the primed tooth surface was contaminated with artificial saliva, primer should be reapplied after re-etching it.