• Journal of the Korean Society for Precision Engineering
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• v.26 no.6
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• pp.131-135
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• 2009

In this study, we performed the compressive strength test of trabecular bone in knee joint for measuring the elastic modulus and ultimate strength. The main knee joint is femorotibial articulation between the lateral and medial femorotibial condyle. In the case of osteoarthritis, some patients have only medial condylar osteoarthritis. We performed the mechanical test for comparison the difference of the each condylar strength. We used diamond core-drill and linear precision saw for making the specimens. Specimens were cored from both condyle in distal femur and proximal tibia in fresh cadaver (male 10, female 12), and tested by universal test machine with temperature control saline circulation system. Results of the test in distal femoral parts, averaged elastic modulus was $360.61{\pm}159.40MPa$ for male, $150.89{\pm}70.65MPa$ for female. Averaged ultimate strength was $6.79{\pm}2.91MPa$ for male, $2.89{\pm}1.31MPa$ for female. Male was 2.4 times stronger than female. In the proximal tibial parts, averaged elastic modulus was $108.80{\pm}52.88MPa$ for male, $73.45{\pm}55.06MPa$ for female. Averaged ultimate strength was $2.59{\pm}1.39MPa$ for male, $1.75{\pm}1.16MPa$ for female. Male was 1.5 times stronger than female. In the distal femoral condyle, medial condyle had more strength than lateral condyle at middle region. But lateral condyle had more strength than medial condyle at anterior & posterior regions (p<0.02). In the proximal tibial condyle, medial condyle had more strength than lateral condyle. (p<0.01).

• Journal of Korean Tunnelling and Underground Space Association
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• v.6 no.2
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• pp.101-111
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• 2004

In order to guarantee the stability of a tunnel and its optimum design, it is very important to obtain enough ground investigation data. In realty, however, it is not the case due to the limitation of measuring spatially distributed data and economical reasons. Especially, there are regions where drilling is impossible due to civil appeal and mountainous topology, and it is also difficult to estimate rock mass classes quantitatively with only geophysical exploration data. In this study, therefore, 3 dimensional multiple indicator kriging (3D-MI kriging), which can incorporate geophysical exploration data and drill core data off a tunnel center line, is proposed to cope with such problems. To this end, two dimensional mutiple indicator kriging, which is one of the geostatistical techniques, is extended for three dimensional analysis. Also, the proposed 3D-MI kriging was applied to determine the rock mass classes by RMR system for the design of a Kyungbu express rail way tunnel.

• The Journal of Engineering Geology
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• v.17 no.4
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• pp.517-523
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• 2007

Geophysical surveys(seismic refraction, electrical resistivity, and ground penetrating radar) were performed to delineate the weathering zone associated with vadose water in Chojeong area and investigate the fault related fracture zones. On the basis of seismic velocity structures, weathering layer for the southwestern part is interpreted to be deeper than for the northeastern part. The depth to bedrock(i.e., thickness of weathered zone) from seismic refraction data attempted to be correlated with drill-core data and groundwater level. As for the investigation of geological discontinuities such as fault related fracture zone, seismic refraction, electrical resistivity, and ground penetrating data are compositely employed in terms of velocity and resistivity structures for mapping of surface boundary of the discontinuities up to shallow depth. Surface boundaries of fracture zone are well indicated in seismic velocity and electrical resistivity structures. Accurate estimation of weathered zone and fracture zone can be successfully available for mapping of attitude of vadose water layer.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.518-521
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• 2005

We performed the mechanical test for obtaining properties of femoral head. Tested sample was male and 35 years old. We measured bone mineral density by dual X-ray absorption method(DEXA). Results of DEXA, he has normal condition of bone density. His BMD $1.159g/cm^2$ and T-Score is 1.6. Tested femurs were harvested by surgical method from donated cadaver. We made 9 specimens in femoral head, 8 specimens in neck used by diamond core drill. Then we performed compressive test in saline solution at $38^{\circ}C$. We obtained results that elastic modulus of femoral head was 0.439GPa, neck was 0.459GPa. Compressive strength of femoral head was 7.441 MPa, neck was 7.095MPa. There was no significant difference of mechanical properties between left and right femoral head & neck. Invested local properties of femoral head have more strength superior and anterior side, femoral neck has more strength in superior and inferior side but other side except for superior has more weakness along the lateral side.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.6 no.2
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• pp.81-92
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• 2001

According to analyses of high-resolution seismic profiles (air gun, sparker, and SBP) and a deep-drill core(YSDP 105) in the mid-eastern Yellow Sea, stratigraphic and geoacoustic models have been established and seismo-acoustic modeling has been fulfilled using ray tracing of finite element method. Stratigraphic model reflects seismo-, litho-, and chrono-stratigraphic sequences formed under a significant influence of Quaternary glacio-eustatic sea-level fluctuations. Each sequence consists of terrestrial to very-shallow-marine coarse-grained lowstand systems tract and tidal fine-grained transgressive to highstand systems tract. Based on mean grain-size data (121 samples) of the drill core, bulk density and P-wave velocity of depositional units have been inferred and extrapolated down to a depth of the recovery using the Hamilton's regression equations. As goo-acoustic parameters, the 121 pairs of bulk density and P-wave velocity have been averaged on each unit of the stratigraphic model. As a result of computer ray-tracing simulation of the subsurface strata, we have found that there are complex ray paths and many acoustic-shadow zones owing to the presence of irregular layer boundaries and low-velocity layers.

• The Journal of Engineering Geology
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• v.24 no.4
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• pp.525-534
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• 2014

Environmental problems typically occurring in abandoned mine lands (AML) include: contaminated and acidic surface water and groundwater; stockpiled waste rock and mill tailings; and ground subsidences due to mining operations. This study examines the effectiveness of various geophysical techniques for mapping potential hazard and contaminated zones. Four AML sites with sedimentation contamination problems, acid mine drainage (AMD) channels, ground subsidence, manmade liner leakage, and buried mine tailings, were selected to examine the applicability of various geophysical methods to the identification of the different types of mine hazards. Geophysical results were correlated to borehole data (core samples, well logs, tomographic profiles, etc.) and water sample data (pH, electrical conductivity (EC), and heavy metal contents). Zones of low electrical resistivity (ER) corresponded to areas contaminated by heavy metals, especially contamination by Cu, Pb, and Zn. The main pathways of AMD leachate were successfully mapped using ER methods (low anomaly peaks), self-potential (SP) curves (negative peaks), and ground penetrating radar (GPR) at shallow penetration depths. Mine cavities were well located based on composite interpretations of ER, seismic tomography, and well-log records; mine cavity locations were also observed in drill core data and using borehole image processing systems (BIPS). Damaged zones in buried manmade liners (used to block descending leachate) were precisely detected by ER mapping, and buried rock waste and tailings piles were characterized by low-velocity zones in seismic refraction data and high-resistivity zones in the ER data.

• Tunnel and Underground Space
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• v.22 no.2
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• pp.144-156
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• 2012

This paper discusses the methods of estimating the punch penetration indices and data analysis punch penetration test to estimate the TBM normal force and penetration rate. In punch penetration test is known as a useful test to estimate penetration rates and normal force of TBMs directly with several slope indices indicated drill-ability and brittleness of rocks. However, the standard methods and indices for punch penetration test are not suggested yet. The main purpose of punch penetration test which is prediction of normal force of TBM disc cutter when cutters excavate rock mass. In this study, the punch penetration tests were performed for 6 representative Korean rock types and variety length and diameter of rock core specimens. Among slope indices were obtained from punch penetration test, PLI and MLI which is suggested in this study show high correlation with cutter force measured by full-scale cutting test. The results show that the predicted normal force of a single disc cutter and the experimental error was 10%. Based on these results, it is concluded that punch penetration test is reliable laboratory test for estimating thrust and penetration rates of TBM.

• Journal of the Society of Disaster Information
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• v.16 no.2
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• pp.267-275
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• 2020

Purpose: In this study, GPR exploration equipment, spray vehicles and flow meters, core drill, borehole image processing system(BIPS), 3D cavity imagery equipment, and cavity formatting equipment were used to identify this cavity growth process. Method: A certain amount of water was injected in proportion to the mass of the cavity, and the cavity was observed to expand as the injected water was drained out. The cavity rating change was evaluated by quantitatively evaluating the expansion factors and the speed of growth. Results: According to the results of examining the volume change through injection time - injection flow rate - volume increase for the four experimenters, the volume increase decreased as the injection time increased, and there was no further increase in volume if injected for one hour or so. Conclusion: In addition, the injection test analyzed the volumetric variation to determine whether the cause of the cavity occurrence was the effect of the underground burial in the vicinity of the cavity. Therefore, it was found that the cavity expansion is caused by the repetition of the relaxation soil collapse due to the groundwater flow and the loss of the collapsed soil below the cavity.

• The Journal of Engineering Geology
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• v.11 no.1
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• pp.63-79
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• 2001

This study is aimed for estimating hydraulic parameters using the Cooper-Bredehoeft-Papadopulos, the Hvorslev, and the Bouwer & Rice methods at nineteen test holes in Me. Geumjeong area composed of Bulguksa granites, and for characterizing hydraulic properties at the test holes with relatioll to drill core data. The relation among hydraulic Dammeters obtained by the three methods is also considered. The study area is divided into four sub-areas to consider the hydraulic characteristics. The difference of hydraulic conductivity estimates between the injection and the withdrawal slug test may be due to penncable fracture distlibutions around the test hole and/or the disturbance of fine mateIials in the fractures induced by the pressure variation due to different mechanisms of test initiation. The hydraulic conductivity estimates detennined by the Cooper-Bredehoeft-Papadopulos, the Hvorslev and the Bouwer & Rice methods ranges from 10$^{-8}$ to lO$^{-5}$m/sec, and the ranges of average values are from 10$^{-7}$ to 10$^{-6}$m/sec. Also, the transmissivity ranges from 10$^{-7}$ to 10$^{-5}$$m^2$/sec. Comparing average hydraulic conductivity by the Cooper-Bredehoeft-Papadopulos, the Hvorslev and the Bouwer & Rice methods, by the Hvorslev method has the highest values, then the Bouwer & Rice method, and the Cooper-Bredehoeft-Papadopulos method has the lowest.

• The Journal of Engineering Geology
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• v.15 no.1
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• pp.41-55
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• 2005

This research is aimed at investigating the ground characterization of the Cheongju granite area using the geophysical methods. Test site was chosen from the building site in Chungbuk University, Chongju, Chungbuk province. Furthermore, geophysical methods are employed on the outcrops in the east to map the distribution of fault and intrusion and reveal the degree of weathering. The subsurface structure mapped from seismic re-fraction survey mainly consists of two units of weathered soil and rock. Threshold of the units were determined on the basis of seismic velocity of 800 m/s, supported from the standard classification table. From the results of standard penetrating test(SPT), these units are found to show medium-high and high density, respectively. Weathering soil is subdivided in unsaturated layer and saturated layer with thresholds of seismic velocity (500 m/s) and resistivity (200 ohm-m). In particular, unsaturated layer is again classified into dry and wet portions using the GPR section. The boundary between unsaturated and saturated weathering soils corresponds to the groundwater table at depth of approximately 5～6.2 m, which is well correlated with the one from drill-core data. However, bedrock is not delineated by geophysical methods. In the GPR section, fault and intrusion observed on the outcrop are revealed not to extend to the building site. With respect to weathering degree, the outcrop characterized by low resistivity and velocity corresponds to the grade of 'completely weathered' from the geotechnical investigations.