• Journal of the Computational Structural Engineering Institute of Korea
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• v.35 no.3
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• pp.167-174
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• 2022

This study investigates the behavior of a jointless bridge that integrates superstructure and abutment without an expansion joint. Based on the sensitivity analyses conducted in previous studies, a shell-based model was determined to be the most suitable numerical analysis model for jointless bridges due to the similarity of the model's results compared with the obtained displacement shape, which was influenced by relative errors, precision, and practical aspects. Accordingly, the behavior of a jointless bridge was analyzed at various wall depths using shell element-based and solid element models. In addition, the results of MIDAS Civil and ABAQUS analysis programs were compared. In the case of semi-integrated bridges (A and B), the displacement decreased as the wall depth increased due to the ground reaction force in Case 1 under a linear spring condition and +30℃. In the case where temperature was -30℃, the change in displacement was small because the ground reaction did not occur. As for bridge C (a fully integrated alternating bridge) and bridge D (an integrated chest wall alternating bridge), the displacement decreased as the wall depth increased at both +30 and -30℃ due to pile resistance. As for the comparison between the analysis programs used, the relative error in Case 1 was small, whereas a significant difference in Case 2 was observed. The foregoing variation is possibly due to the difference in the application of the nonlinear spring in the programs.

• Journal of Soil and Groundwater Environment
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• v.13 no.1
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• pp.77-91
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• 2008

In this study, we developed a technique of applying DRASTIC, which is the most widely used tool for estimation of groundwater vulnerability to the aqueous phase contaminant infiltrated from the surface, and a groundwater flow model jointly to assess groundwater contamination potential. The developed technique is then applied to Buyeo-eup area in Buyeo-gun, Chungcheongnam-do, Korea. The input thematic data of a depth to water required in DRASTIC model is known to be the most sensitive to the output while only a few observations at a few time schedules are generally available. To overcome this practical shortcoming, both steady-state and transient groundwater level distributions are simulated using a finite difference numerical model, MODFLOW. In the application for the assessment of groundwater vulnerability, it is found that the vulnerability results from the numerical simulation of a groundwater level is much more practical compared to cokriging methods. Those advantages are, first, the results from the simulation enable a practitioner to see the temporally comprehensive vulnerabilities. The second merit of the technique is that the method considers wide variety of engaging data such as field-observed hydrogeologic parameters as well as geographic relief. The depth to water generated through geostatistical methods in the conventional method is unable to incorporate temporally variable data, that is, the seasonal variation of a recharge rate. As a result, we found that the vulnerability out of both the geostatistical method and the steady-state groundwater flow simulation are in similar patterns. By applying the transient simulation results to DRASTIC model, we also found that the vulnerability shows sharp seasonal variation due to the change of groundwater recharge. The change of the vulnerability is found to be most peculiar during summer with the highest recharge rate and winter with the lowest. Our research indicates that numerical modeling can be a useful tool for temporal as well as spatial interpolation of the depth to water when the number of the observed data is inadequate for the vulnerability assessments through the conventional techniques.

• The Journal of the Korean bone and joint tumor society
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• v.9 no.2
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• pp.190-199
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• 2003

Purpose: The aim of this study was to find out a clinically appliable method to insert a biodegradable solid material containing holmium-166-chitosan complex into the surgical field, and to evaluate the histological changes in the normal tissues after ${\beta}$ -ray irradiation from holmium-166 according to the dose, period and type of tissues. Materials and Methods: 3.0 mCi, 50 ${\mu}l$ of the liquid state $^{166}$Ho-chitosan complex was attached to the absorbable gelatin sponge. The radiation activity measured by dose caliberator was 1.5 mCi. These $^{166}$Ho-chitosan complex containing absorbable gelatin sponges were inserted into the thigh muscles and over the femur bones of the Wistar rats. The cases were evaluated at 2 weeks after insertion, and 4, 6 weeks with respect to the histological changes of the soft tissues and bone, the depth of the tissue necrosis, and the changes of the $^{166}$Ho-chitosan complex containing absorbable gelatin sponges. Results: At 2 weeks, the muscles showed coagulation necrosis, degenerating myocytes, regenerating myocytes, intermuscular edema, and inflammatory cells. The necrosis depth was 3.3 mm. In the bones, there was no osteocyte in the lacuna of cortex (empty lacuna), marrow fibrosis, inflammation. The necrosis depth was 2.9 mm. At 4 weeks, in the muscle, calcification and increased fibrosis with necrosis depth by 3.3 mm were the additional findings. In the bone, marrow fibrosis with necrosis depth by 3.3 mm were detected. At 6 weeks, soft tissue shrinkage, increased fibrosis and granulation tissue formation, and nearly resolving inflammatory reaction were the findings. Conclusion: The local application of the $^{166}$Ho-chitosan complex attached to biodegradable gelatin material with surgery in the laboratory animals resulted in no mortality and morbidity, and satisfactory tissue necrosis. Holmium-166 can be applied to the treatment of the malignant tumor patients.

• Journal of the Korean Wood Science and Technology
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• v.39 no.4
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• pp.318-325
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• 2011

Pitch pine (Pinus rigida Miller) retaining walls using Steel bar, of which the constructability and strength performance are good at the construction site, were manufactured and their strength properties were evaluated. The wooden retaining wall using Steel bar was piled into four stories stretcher and three stories header, which is 770 mm high, 2,890 mm length and 782 mm width. Retaining wall was made by inserting stretchers into Steel bar after making 18 mm diameter of holes at top and bottom stretcher, and then stacking other stretchers and headers which have a slit of 66 mm depth and 18 mm width. The strength properties of retaining walls were investigated by horizontal loading test, and the deformation of structure by image processing (AlCON 3D OPA-PRO system). Joint (Type-A) made with a single long stretcher and two headers, and joint (Type-B) made with two short stretchers connected with half lap joint and two headers were in the retaining wall using Steel bar. The compressive shear strength of joint was tested. Three replicates were used in each test. In horizontal loading test the strength was 1.6 times stronger in wooden retaining wall using Steel bar than in wooden retaining wall using square timber. The timber and joints were not fractured in the test. When testing compressive shear strength, the maximum load of type-A and Type-B was 130.13 kN and 130.6 kN, respectively. Constructability and strength were better in the wooden retaining wall using Steel bar than in wooden retaining wall using square timber.

• The Journal of Korean Academy of Prosthodontics
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• v.47 no.1
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• pp.29-38
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• 2009

Statement of problem: A casting connection technique is widely used for repair, correction and addition to base metal framework. However, a casting connection technique may increase the risk of failure in clinical situations when high stresses exist. Purpose: The purpose of this study was to investigate the mechanical retentive groove design comparatively to increase the joint strength by using the three-dimensional finite element analysis model of a 3-unit fixed partial denture. Material and methods: Ten finite element models were constructed. (Model A: One retentive groove, Model B: Two retentive grooves, Model C: Three retentive grooves, Model D: Four retentive grooves, Model E: One horizontal groove and two vertical grooves, Model F: Two horizontal grooves and one vertical groove, Model G: One groove with the enlarged dimension, Model H: Two grooves with the enlarged dimension, Model I: One groove with the increased height, Model J: One groove with the increased width of base). The vertical force was applied to the mesial and the distal fossa to the casting connection of mandibular first molar. Results: The main factors, affecting joint strength of casting connection were both the retention between the primary cast and the secondary cast and the thickness of the primary cast remaining after preparing retentive groove. The increase of retentive force, according to the numbers and the dimension of retentive groove had an effect on distributing stress. However, in some cases, the increase of retentive force resulted in the increase of stress by reducing thickness of the primary cast in the connection area. Conclusion: The design of retentive groove that limits number of retentive groove for metal thickness and increases the depth of retentive groove for retention is highly recommended.

• The Journal of Engineering Geology
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• v.12 no.1
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• pp.23-34
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• 2002

Borehole image analysis has been carried out to obtain the detailed geological data by approach of direct observation. Direct application of borehole image analysis inevitably gives rise to a few of restriction of data acquisition due to the limited information within narrow borehole space. Considering the apparent dip of discontinuity surface depending upon the direction, the visualized program of two-dimensional subsurface discontinuities is coded. Borehole image analysis can compensate the distribution of subsurface discontinuity extending into the expected area of investigation. In order to draw subsurface profile in the proposed area of subsurface construction, visualized program is coded as a window GUI (Graphic User Interface) using Fortran and Visual Basic Programming languages. It is to open publicly for the usage of whoever is in want. Discontinuity distribution map is visualized along the Proposed line of tunnel in the Janggye-ri area, Jangsu-gun. Using the visualized program, the limited information from borehole spatially applies into analysis of overall subsurface structures, and the distributional characteristics of discontinuity anticipate at the proposed area. In addition, spacing and extension of joint and depth of discontinuity effecting tunnel safety can be visualized along the direction of the proposed tunnel. These lines of visualization apply design and construction of fundanmental structures.

• The Journal of Engineering Geology
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• v.11 no.1
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• pp.81-99
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• 2001

In order to clarify an effect of the cutoff grouting, a series of field experiments were performed during construction of the waterway tunnel from the River Gilancheon(Andong) to the Youngcheon dam. The experiments were conducted in three different ways based on the grouting time in the construction sequence, i.e., the pre-grouting, after-grouting and consolidation grouting tests. And those were also planned to compare the efficiency of grouting in relation to the material types of grout, base rock types and other geologic factors such as discontinuities, depth and direction of grouting holes, and number of grouting stages. Among the materials of grout employed in the experiments, such as a common Portland cement, a micro-cement, a micro-cement with sodium silicate, and a urethane, the urethane was the most effective as the cutoff grouting. And for the same grout material, the pre-grouting was more effective to cutoff the water inflow comparing to the after-grouting and the consolidation grouting. For the rock types, the grouting efficiency in the sedimentary rocks as a base rock was less than the other rocks such as granite and volcanic rocks, which is believed due to the smaller separation of joints and the abundance of infilling materials in the joints developed in the sedimentary rocks. There was no direct relationship between the total RMR value of the rock mass and the grouting efficiency, however, the joint separation which is one of the RMR criteria is believed to have positive relation to the grouting efficiency. And the direction of the grouting holes might not so much affect on the grouting efficiency while increasing the number of grouting stage showed the better results.

• Journal of Korea Technology Innovation Society
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• v.18 no.1
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• pp.28-48
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• 2015

This study is public R & D institutions report to verify what the impact factors on the course of progress of industrialization based on technology companies who previously received prior to the developed technology, what policies and plans for the next requirements based on this by offering the implications for business rate was to contribute to the improvement of the public research institution technology transfer. In this study, the influence factors on technology commercialization derived through the analysis of existing and previous studies, the characteristics of the previously received corporate environmental characteristics and previous technologies through a survey of the company received a technology transfer from public research institutions commercialization decisions and contributions, including sales and commercialization of the results were analyzed by logistic regression analysis demonstrated how to have relevance. Analysis, and linkage with high production company has an existing case of IT technology transfer, commercialization of higher technical success rate was higher compatibility. On the other hand, were observed and expected success rate were higher when a rather commercialized technologies independently be earlier than if participating in joint research in the development of the technology, unlike previously, completeness of the prior art did not significantly affect. This study has the following policy implications. Public research institutions have developed technologies are commercialized to figure out what the requirements of the technical aspects of consumer technologies in order to create economic wealth. And for technology commercialization for enough technical competencies to absorb the technology, and that the technology and considering the link between business and technology commercialization success to be applied. This study has some limitations. First, the sample size was not sufficient. In relation to the presence and participation of corporate success and commercialization of the R & D process, with many previous studies are needed more in-depth analysis by leading research in the sense that different results are obtained. Also did not reflect the will or the corporate culture, management and organizational skills and belongs to the external environment and internal corporate enterprises industry characteristics affecting the success of corporate management of the business. And lacked sufficient consideration of the various technical characteristics present in the form of joint research and industry. Finally, there is a limit of generalizations about other industries.

• The Journal of Engineering Geology
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• v.21 no.1
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• pp.15-24
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• 2011

To clarify the distribution of joints and fracture zones in the Cheongju granitic mass, we analyzed drill-core and geophysical well-logging data obtained at two boreholes located 30 m from each other. Lithological properties were investigated from the drill-core data and the samples were classified based on the rock mass rating (RMR) and on rock quality designation (RQD). Subsurface discontinuities within soft and hard rocks were examined by geophysical well-logging and cross-hole seismic tomography. The velocity structures constructed from seismic tomography are well correlated with the profile of bedrock depth, previously mapped from a seismic refraction survey. Dynamic elastic moduli, obtained from full waveform sonic and ${\gamma}-{\gamma}$ logging, were interrelated with P-wave velocities to investigate the dynamic properties of the rock mass. Compared with the correlation graph between elastic moduli and velocities for hard rock at borehole BH-1, the correlation points for BH-2 data showed a wide scatter. These scattered points reflect the greater abundance of joints and fractures near borehole BH-2. This interpretation is supported by observations by acoustic televiewer (ATV) and optical televiewer (OTV) image loggings.

• Proceedings of the KWS Conference
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• 2010.05a
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• pp.51-51
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• 2010

Recently just as in the automobile industry, shipbuilders also try to reduce material consumption and weight in order to keep operating costs as low as possible and improve the speed of production. Naturally industry is ever searching for welding techniques offering higher power, higher productivity and a better quality. Therefore it is important to have a details research based on the various welding process applied to steel and other materials, and to have the ability both to counsel interested companies and to evaluate the feasibility of implementation of this process. Submerged-arc welding (SAW) process is usually used about 20% of shipbuilding. Similar to gas metal arc welding(GMAW), SAW involves formation of an arc between a continuously-fed bare wire electrode and the work-piece. The process uses a flux to generate protective gases and slag, and to add alloying elements to the weld pool and a shielding gas is not required. Prior to welding, a thin layer of flux powder is placed on the work-piece surface. The arc moves along the joint line and as it does so, excess flux is recycled via a hopper. Remaining fused slag layers can be easily removed after welding. As the arc is completely covered by the flux layer, heat loss is extremely low. This produces a thermal efficiency as high as 60% (compared with 25% for manual metal arc). SAW process offers many advantages compared to conventional CO2 welding process. The main advantages of SAW are higher welding speed, facility of workers, less deformation and better than bead shape & strength of welded joint because there is no visible arc light, welding is spatter-free, fully-mechanized or automatic process, high travel speed, and depth of penetration and chemical composition of the deposited weld metal. However it is difficult to application of thin plate according to high heat input. So this paper has been focused on application of the field according to SAW process for thin plate in ship-structures. For this purpose, It has been decided to optimized welding condition by experiments, relationship between welding parameters and bead shapes, mechanical test such as tensile and bending. Also finite element(FE) based numerical comparison of thermal history and welding residual stress in A-grade 3.2 thickness steel of SAW been made in this study. From the result of this study, It makes substantial saving of time and manufacturing cost and raises the quality of product.