• International Journal of Highway Engineering
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• v.8 no.2 s.28
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• pp.63-74
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• 2006

During the construction of circular underground pipe, the non-proper compaction along the pipe and the decrease of compaction efficiency have been the main problems to induce the failure of underground pipe or facility. The use of CLSM (controlled low strength materials) should be one of the possible applications to overcome those problems. In this research, the full-scaled field test and the numeric analysis using PENTAGON-3D FEM program were carried out for three different cases on the change of backfill materials, including the common sand, the soil from construction site, and the CLSM. From the full-scaled test in field, the use of in-situ CLSM as backfill materials reduced the vertical and lateral deformation of the pipe, as well as the deformation of the ground surface. The main reason for reducing the deformation would be the characteristics of the CLSM, especially self-leveling and self-hardening properties. The measured earth pressure at the surround of the corrugated pipe using the CLSM backfills was the smaller than the other cases, and the absolute value was almost zero. Judging from the full-scaled field test and FEM analysis, the use of CLSM as backfill materials should be one of the best choices reducing the failure of the underground pipes.

• Journal of the Mineralogical Society of Korea
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• v.17 no.4
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• pp.309-325
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• 2004

The Cannington Ag-Pb-Zn deposit, northwest Queensland, Australia developed around the host rocks composing banded and migmatitic gneisses, sillimanite-garnet schist and amphibolite. Three crystal habits of sillimanite, gahnite (Zn-spinel) and garnet porphyroblasts occurred on the host rocks of the Cannington deposit could be used to delineate metamorphism that closely associated with Zn-mineralization in the deposit. Linkages the metamorphism to Zinc-mineralization is determined in four chemical systems, KFMASH (K$_2$O-FeO-MgO-Al$_2$O$_3$-SiO$_2$-$H_2O$), KFMASHTO (K$_2$O-FeO-MgO-Al$_2$O$_3$-SiO$_2$-$H_2O$-TiO$_2$-Fe$_2$O$_3$), NCKFMASH (Na$_2$O-CaO-K$_2$O-FeO-MgO-AlO$_3$-SiO$_2$-$H_2O$) and MnNCK-FMASH (MnO-Na$_2$O-CaO-K$_2$O-FeO-MgO-AlO$_3$-SiO$_2$-$H_2O$), using THERMOCALC program (version 3.1; Powell and Holland 1988). Partial melting in MnNCKFMASH and NCKFMASH systems occurs at lower temperature than in the KFMASH and KFMASHTO systems. The partial melting temperature decreases with increasing of Na/(Na+Ca+K) of the bulk rock compositions in the MnNCKFMASH system. The host rocks have melted ca 15 vol.% in the MnNCKFMASH system at peak metamorphic conditions (634$\pm$62$^{\circ}C$ and 4.8$\pm$1.3 kbar), but partial melting have not occurred in KFMASHTO system. Based on calculations of sillimanite isograd in different systems and sillimanite modal pro-portion, prismatic and rhombic sillimanite and gahnite porphyroblasts including prismatic sillimanite inclusion probably have resulted from pressure and temperature increasing through partial melting (from 550～$600^{\circ}C$, 2.0～3.0 kbar to 700～75$0^{\circ}C$, 5.0～7.0 kbar), furthermore have experienced N-S then W-E crustal shortening during D$_1$ and D$_2$ deformation. Consequently, Zinc mineralization related to gahnite growth occurred during D$_2$ and was redistributed and upgraded by partial melting and retrograde metamorphism into structural and rheological sites during shearing in D$_3$.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.34 no.2
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• pp.166-179
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• 2008

Excessive concentration of stress which is occurred in occlusion around the implant in case of the implant supported fixed partial denture has been known to be the main cause of the crestal bone destruction. Therefore, it is essential to evaluate the stress analysis on supporting tissue to get higher success rates of implant. The purpose of this study was to evaluate the effects of stress distribution and deformation in 3 different types of three-unit fixed partial denture sup-ported by two implants, using a three dimensional finite element analysis in a three dimensional model of a whole mandible. A mechanical model of an edentulous mandible was generated from 3D scan, assuming two implants were placed in the left premolars area. According to the position of pontic, the experiments groups were divided into three types. Type I had a pontic in the middle position between two implants, type II in the anterior posi-tion, and type III in the posterior position. A 100-N axial load was applied to sites such as the central fossa of anterior and posterior implant abutment, central fossa of pontic, the connector of pontic or the connector between two implants, the mandibular boundary conditions were modeled considering the real geometry of its four-masticatory muscular supporting system. The results obtained from this study were as follows; 1. The mandible deformed in a way that the condyles converged medially in all types under muscular actions. In comparison with types, the deformations in the type II and type III were greater by 2-2.5 times than in the type I regardless of the loading location. 2. The values of von Mises stresses in cortical and cancellous bone were relatively stable in all types, but slightly increased as the loading position was changed more posteriorly. 3. In comparison with type I, the values of von Mises stress in the implant increased by 73% in Type II and by 77% in Type III when the load was applied anterior and posterior respectively, but when the load was applied to the middle, the values were similar in all types. 4. When the load was applied to the centric fossa of pontic, the values of von Mises stress were nearly $30{\sim}35%$ higher in the type III than type I or II in the cortical and cancellous bone. Also, in the implant, the values of von Mises stress of the type II or III were $160{\sim}170%$ higher than in the type I. 5. When the load was applied to the centric fossa of implant abutment, the values of von Mises stress in the cortical and cancellous bone were relatively $20{\sim}25%$ higher in the type III than in the other types, but in the implant they were 40-45% higher in the type I or II than in the type III. According to the results of this study, musculature modeling is important to the finite element analysis for stress distribution and deformation as the muscular action causes stress concentration. And the type I model is the most stable from a view of biomechanics. Type II is also a clinically accept-able design when the implant is stiff sufficiently and mandibular deformation is considered. Considering the high values of von Mises stress in the cortical bone, type III is not thought as an useful design.

• Korean Journal of Remote Sensing
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• v.34 no.6_4
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• pp.1479-1488
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• 2018

On September 3rd 2017, strong artificial seismic signals from North Korea were detected in KMA (Korea Meteorological Administration) seismic network. The location of the epicenter was estimated to be Punggye-ri nuclear test site and it was the most powerful to date. The event was not studied well due to accessibility and geodetic measurements. Therefore, we used remote sensing data to analyze surface changes around Mt. Mantap area. First of all, we tried to detect surface deformation using InSAR method with Advanced Land Observation Satellite-2 (ALOS-2). Even though ALOS-2 data used L-band long wavelength, it was not working well for this particular case because of decorrelation on interferogram. The main reason would be large deformation near the Mt. Mantap area. To overcome this limitation of decorrelation, we applied offset tracking method to measure deformation. However, this method is affected by window kernel size. So we applied various window sizes from 32 to 224 in 16 steps. We could retrieve 2D surface deformation of about 3 m in maximum in the west side of Mt. Mantap. Second, we used Pleiadas-A/B high resolution satellite optical images which were acquired before and after the 6th nuclear test. We detected widespread surface damage around the top of Mt. Mantap such as landslide and suspected collapse area. This phenomenon may be caused by a very strong underground nuclear explosion test. High-resolution satellite images could be used to analyze non-accessible area.

• Journal of the Korean earth science society
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• v.21 no.3
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• pp.302-314
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• 2000

Keumseong area in the southern part of the Jecheon city, the Ogcheon Belt, consists of Precambrian Dangdusan Metamorphic Complex, Dori Formation of the Choseon Supergroup, and Jurassic Jecheon Granite. The Dangdusan Metamorphic Complex consists of quartz schist, mica schist. quartzite and pegmatite. The Dori Formation is composed of mainly laminated limestone. The rocks in the study area have been undergone at least three phases of deformations since Paleozoic period. The Dangdusan Metamorphic Complex is outcrop at three areas in the study area, which are exposed along the faults and occurred as inlier within the Dori Formation. Previous authors interpreted the uplift of the Dangdusan Metamorphic Complex by the Dangdusan Fault, but we could not find any evidences related to the Dangdusan Fault. Thus, we interpret the uplift of the Dangdusan Metamorphic Complex due to the D$_2$ Weolgulri and Dangdusan thrusts and post-D$_2$ Jungbodeul, Kokyo and Jungjeonri faults. The uplift of the Busan Metamorphic Complex to the west of the study area was interpreted by ductile deformation. However, the Dangdusan Metamorphic Complex is formed by brittle thrusts and faults in this study. According to deformation sequence, the characters of deformations in the Choseon and Ogcheon suprergroups had been changed from ductile to brittle deformations through the time. Therefore, we interpret the Dangdusan Metamorphic Complex is exposed later than the Busan Metamorphic Complex.

• Korean Journal of Materials Research
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• v.9 no.3
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• pp.322-326
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• 1999

In this study, cold-rolling and appropriate annealing was adopted for the grain refining of Cu-26.65Zn-4. 05Al-0.31Ti(wt%) shape memory alloy. For the cold deformation of this alloy the ducti1e $\alpha$-phase must be contained. After heat treatment at $550^{\circ}C$ the $(\alpha+$\beta)$-dual phase with 40vol.% $\alpha$-phase was obtained which could be rolled at room temperature. This alloy was cold rolled into a final thickness of 1.0mm with total reduction degrees of 70% and 90%. The rolled sheets were betanized at $800^{\circ}C$ for various times, then quenched into ice water. The grain size of co]d rolled samples were $60~80\mu\textrm{m}$ which is much smaller comparing with the hot-rolled samples. And the 90% rolled sample showed smaller grain size than the case of the 70% rolled one. The small grain size had influence on the phase transformation temperatures and stabilization of the austenitic phases.

• Journal of Korean Tunnelling and Underground Space Association
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• v.14 no.5
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• pp.529-545
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• 2012

Three-dimensional (3D) finite element analyses have been performed to study the behaviour of a single pile to open face tunnelling in stiff clay. Several key factors such as tunnelling-induced ground and pile settlement, and shear transfer mechanism have been studied in detail. Tunnelling resulted in the development of pile settlement larger than the Greenfield soil surface settlement. In addition, due to changes in the shear transfer between the pile and the soil next to the pile with tunnel advancement, axial force distributions along the pile change drastically. The apparent allowable pile capacity was reduced up to about 30% due to the development of tunnelling-induced pile head settlement. The skin friction on the pile was increased with tunnel advancement associated with the changes of soil stresses and ground deformation and hence axial pile force distribution was reduced. Maximum tunnelling-induced tensile force on the pile was about 21% of the designed pile capacity. The zone of influence on the pile behaviour in the longitudinal direction may be identified as ${\pm}1$-2D (D: tunnel diameter) from the pile centre (behind and ahead of the pile axis in the longitudinal direction) based on the analysis conditions assumed in the current study. Negative excess pore pressure was mobilised near the pile tip, while positive excess pore pressure was computed at the upper part of the pile. It has been found that the serviceability of a pile experiencing adjacent tunnelling is more affected by pile settlement than axial pile force changes.

• Journal of the Korean Wood Science and Technology
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• v.38 no.6
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• pp.532-540
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• 2010

The strength properties of wooden model retaining wall made of pitch pine (Pinus rigida Miller) was evaluated. Three different types of wooden model retaining wall were made of the 11cm square timber treated with CUAZ-2 (Copper Azole). The retaining wall was made into the 4 layers of crossbar and the 3 layers of vertical-bar, of which the size was 86 cm high, 200 cm long and 96 cm wide. Type I was control and in Type II 20 cm vertical-bars and 93 cm vertical-bars were arranged alternately to decrease wood usage. TypeIII was similar to TypeII except that the connection between crossbars was reinforced with the wooden armature. In each type, the strength properties of retaining wall were investigated by horizontal loading test and the deformation of structure by image processing (AICON 3D DPA-PRO system). In horizontal loading test of Type I, Type II and Type III was 63.17, 57.80, and 60.97 kN/m, respectively. The deformation of the top layer in Type II was 1.5 times larger than in Type I and Type III. Consequently, the economic efficiency and strength performance were better in Type III than in Type I and Type II.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.3
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• pp.130-137
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• 2017

The purpose of this study is to provide a reasonable analytical method for the reinforced concrete beams which shows failure mode of shear and flexure-shear by proposing a modified formulation to consider the effect of shear deformation on the beam-column fiber element based on the flexibility method and a new constitutive law of inelastic shear response history for the section. A total of 6 specimens of reinforced concrete beams which is designed to cause shear failure before yielding longitudinal reinforcement to investigate the influence of the main experimental variables on the shear behavior characteristics and the analysis was performed by using a non-linear finite element analysis program (RCAHEST) applying the newly modified constitutive equation by the authors. The failure mode and the overall behavior characteristics until fracture are predicted appropriately for all specimens and the results are expected to be useful enough for the 3 - D analysis to carry out reliable results of large-scale and complicated structures in the future.

• Geotechnical Engineering
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• v.14 no.4
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• pp.177-204
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• 1998

In the present study, a method of quasi-three dimensional stability analysis is proposed for a systematic design of the GRS-RW(Geosynthetic-Reinforced Soil Retaining Wall) system based on the postulated three dimensional failure wedge. The proposed method could be applied to the analysis of the stability of both the straight-line and cove-shaped are. As with skew reinforcements. Maximum earth thrust expected to act on the rigid face wall is assumed to distribute along the depth, and wall displacements are predicted based on both the assumed compaction-induced earth pressures and one dimensional finite element method of analysis. For a verification of the procedure proposed in the present study, the predicted wall displacements are compared with chose obtained from the RMC tests in Canada and the FHWA tests in U.S.A. In these comparisons the wall displacements estimated by the methods of Christopher et at. and Chew & Mitchell are also included for further verification. Also, the predicted wall displacements for the convex-shaped zone reinforced with skew reinforcements are compared with those by $FLAC_{3D}$ program analyses. The assumed compaction-induced earth pressures evaluated on the basic of the proposed method of analysis are further compared with the measurements by the FHWA best wall. A parametric stduy is finally performed to investigate the effects of various design parameters for the stability of the GRS-RW system