• Journal of the Korean Geosynthetics Society
• /
• v.17 no.1
• /
• pp.21-31
• /
• 2018

This paper analyzes the displacements of CFRD which was completed by field measurement. It is to understand the deformation behavior of the dam body according to the water level change from the impounding time. And it was compared with numerical analysis results. As a result of measuring the behavior of the dam crest and downstream slope according to impounding, horizontal displacements in axis direction of the dam, upstream and downstream displacements and settlements occurred mostly when the water level reaches about half of the dam height. The displacements continued until the water level reached its maximum. After that, it showed a constant convergence regardless of the water level. Horizontal displacements of the face slab which is the most important in CFRD were similar at all locations. The Horizontal displacements of the face slab showed the trends of increasing in winter and decreasing in summer due to the effect of the outside temperature before impounding. Also, the displacements increased until the water level reached about half of the dam height. After that, they decreased with rising in water level. As a result, the face slab behaviors according to seasonal change after impounding as well as water level condition. It is judged because of the material characteristics of the concrete slab. Numerical analysis showed slightly different maximum settlement and depth of occurrence from the measuring data after construction of the dam. It is considered that this is due to various design and construction differences such as the estimation of input parameters in analysis, construction period, and the layer thickness of construction. For the overall period of the dam, the settlements were mostly completed during the construction period and some settlements occurred in the early days of impounding and then converged.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.36 no.2
• /
• pp.112-120
• /
• 2020

Purpose: The purpose of this study was to compare the biomechanical outcome in the mandibular posterior region between two different loading conditions by finite element analysis. Materials and Methods: The mandibular posterior teeth model and the implant model were generated for the study. And 2 different types of loading conditions were provided: Arbitrary occlusion and natural occlusion obtained from the digital occlusal analyzer, Accura (Accura, Dmetec Co. Ltd., Seoul, Korea). Total load of 100 N was evenly distributed over arbitrary occlusion points, and 100 N load was differentially distributed over natural occlusion points according to Accura data. The biomechanical outcome was evaluated by the finite element analysis software. Results: The result of finite element analysis showed considerable difference in both von Mises stress pattern and displacement under different loading conditions. Conclusion: In finite element analysis, it is recommended to simulate a realistic occlusal loading pattern that is based on accurate measurement.

• Journal of Sensor Science and Technology
• /
• v.9 no.3
• /
• pp.163-170
• /
• 2000

Optical frequency modulated fiber optic interferometric sensor was developed to sense the mechanical quantities, such as displacement, strain, force etc. It has been difficult to distinguish whether the increase of the mechanical quantities or the decrease of the quantities measured by the conventional fiber optic interferometric sensors because their signals only have a sinusoidal wave pattern related to the change of mechanical quantities. In this study, in order to measure the mechanical quantifies with the distinction of the changing direction of the quantities, the fiber of optic Michelson interferometric sensor was simply constructed by the laser light modulated with saw tooth wave pattern. The output signal of the sensor was controlled as the sinusoidal wave. The signal processing was based on the counting of the wave number of the output signal during constant time duration. The strain was determined by the cumulative value of the wave number producted by the gage factor. In order to verify the strain measurement capability of this sensor, the strain increase-decrease test was performed by universal testing machine installed with the aluminum specimen bonded with the fiber optic sensor and electrical strain gage. In the result of the test, the strain from the fiber optic sensor had a good agreement with the values from the electrical strain gage.

• Korean Journal of Remote Sensing
• /
• v.34 no.3
• /
• pp.495-506
• /
• 2018

Global interest in climate change and sea level rise has led to active research on the velocities of glaciers. In studies about the velocity of glaciers, in-situ measurements can obtain the most accurate data but have limitations to acquire periodical or long-term data. Offset tracking using SAR is actively being used as an alternative of in-situ measurements. Offset tracking has a limitation in that the accuracy of observation is lower than that of other observational techniques, but it has been improved by recent studies. Recent studies in the $Uv{\hat{e}}rsbreen$ glacier area have shown that glacier altitudes decrease at a rate of 1.5 m/year. The glacier displacement velocities in this region are heavily influenced by climate change and can be important in monitoring and forecasting long-term climate change. However, there are few concrete examples of research in this area. In this study, we applied the improved offset tracking method to observe the two-dimensional velocity in the $Uv{\hat{e}}rsbreen$ glacier. As a result, it was confirmed that the glacier moved at a maximum rate of 133.7 m/year. The measruement precisions for azimuth and line-of-sight directions were 5.4 and 3.3 m/year respectively. These results will be utilized to study long-term changes in elevation of glaciers and to study environmental impacts due to climate change.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.9 no.2
• /
• pp.43-54
• /
• 1989

In this paper, measured and calculated responses are compared in order to give how the static and dynamic responses occurred in steel railway bridges due to train loads could be calculated appropriately. From this, it is investigated how the impact factors are varied by changing the train speed above 100km/h Field measurement is carried out by the steel strain gages and displacement transducers at the main design points, and then the static and dynamic response, fundamental frequencies, damping ratios and impact factors of the bridges are obtained. Static analysis is done using the computer program developed according to three dimensional matrix structural analysis in which the trains and bridges are modelled as 1,2 and 3 dimensions. Dynamic analysis is done according to 2 approaches, the moving force and mass problem. In moving force problem, the solutions are obtained by the modesuperposition-method and in moving mass problem by the direct integration method. From this study, it is known that in order to obtain the static response in the railway bridges, the bridge could be modelled by 1 or 2 dimension as in the highway bridge, however the response ratio(measured/calculaled) is high comparing to the highway bridges. By the way, the dynamic response should be obtained by the moving mass problem. And by comparing the measured and code specified impact factors, it is known that the factors specified in the present railway bridge code are very safe under the present service speed below 100km/h. However, because the factors become very high under the speed above 100km/h, especially in the simple plate girder bridge, it is thought that the code specification on impact factor should be discussed enough under the rapid transit system.

• Journal of Korean Neurosurgical Society
• /
• v.29 no.1
• /
• pp.78-86
• /
• 2000

Objective : Lumbar spinal instability occurs when normal biomechanics support in lumbar vertebrae interrupted. Despite the recent enthusiastic studies, the precise radiological assessment has not been fully established, yet. Therefore, we carefully studied our cases to analyze the radiologic findings in lumbar spinal instability. Patients and Methods : We have put together radiological analysis and assessment based on 38 patients who have been diagnosed and treated for lumbar spinal instabilities from June 1994 to December 1998, Patients who have been diagnosed and treated for trauma were excluded from study. Results : The outcomes are as follows : 1) Lumbar lordotic curve was statistically significant in unstable group by 23.7, compared to the control group ($17.0^{\circ}$). 2) According to the resting x-ray, sagittal plane angulation measured on unstable group was $21.1^{\circ}$, control group $18.0^{\circ}$. Therefore unstable group was noticeably higher(p<0.01). 3) According to the resting x-ray sagittal plane displacement, unstable group had 4.3mm, the comparison had 1.2mm. Therefore measurement from the unstable group were significantly higher(p<0.01). 4) According to stress view, sagittal plane translation was 4.1mm for the unstables and 2.7mm for the comparisons. Therefore unstables were noticeably higher(p<0.01). 5) According to stress view, sagittal plane rotation was $15.1^{\circ}$ at L3-4, $22.0^{\circ}$ at L4-5, $27.9^{\circ}$ at L5S1 for the unstable group and $11.3^{\circ}$, $18.1^{\circ}$, $21.0^{\circ}$ each for the comparison. 6) Facet angle for unstable group, left $29.3^{\circ}-61.5^{\circ}$, right $24.4^{\circ}-63.2^{\circ}$ and the mean for each are $43.1^{\circ}$, $47.2^{\circ}$. The difference between left and right facet angle was $3.5^{\circ}-20.7^{\circ}$ and the mean value $15.3^{\circ}$. Facet angle for the comparisons for the left was $29.3^{\circ}-59.5^{\circ}$, right was in between $25.7^{\circ}-64.5^{\circ}$ range and the each mean are $44.9^{\circ}$ and $47.6^{\circ}$. Also, the difference between left and right facet angle was $4.1^{\circ}-9.3^{\circ}$ and the average was $17.1^{\circ}$. The average and the difference between the left and right angle are found not to have statistic necessity for both unstable and stable measurements(p>0.01). 7) 19 patients were found to have vacuum facet phenomenon among unstable group etc. results were collected. Conclusion : According to above results, we attempted to prepare the application to the patient of radiological analysis and assessment for lumbar spinal instability early checkup.

• Restorative Dentistry and Endodontics
• /
• v.33 no.2
• /
• pp.115-124
• /
• 2008

The purpose of this study was to measure the polymerization shrinkage and hygroscopic expansion of resin-based temporary filling materials and to evaluate microleakage at the interface between the materials and cavity wall. Five resin-based temporary filing materials were investigated: Fermit (Vivadent), Quicks (Dentkist), Provifil (Promedica), Spacer (Vericom), Clip (Voco). Caviton (GC) was also included for comparison. Polymerization shrinkage of five resin-based temporary filling materials was measured using the bonded disc method. For the measurement of hygroscopic expansion, the discs of six cured temporary filling materials were immersed in saline and a LVDT displacement sensor was used to measure the expansion for 7 days. For estimating of microleakage, Class I cavities were prepared on 120 extracted human molars and randomly assigned to 6 groups of 20 each. The cavities in each group were filled with six temporary filling materials. All specimens were submitted to 1000 thermocycles, with temperature varying from $5^{\circ}C/55^{\circ}C$. Microleakage was determined using a dye penetration test. The results were as follows: 1. Fermit had significantly less polymerization shrinkage than the other resin-based temporary fill ing materials. Fermit (0.22%) < Spacer (0.38%) < Quicks (0.64%), Provifil (0.67%), Clip (0.67%) 2. Resin-based temporary filling materials showed 0.43-1.1% expansion in 7 days. 3. Fermit showed the greatest leakage, while Quicks exhibited the least leakage. 4. There are no correlation between polymerization shrinkage or hygroscopic expansion and microleakage of resin-based temporary filling materials.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.22 no.3
• /
• pp.211-221
• /
• 2009

With recent trends of super-tallness, atypical plan shapes and zoning constructions in high-rise buildings, a structural stability of the building under construction is arising as a key issue for design and construction plan. To ensure the structural stability under construction, the differential column shortening of vertical members, the lateral displacement of tower frames, and differential settlement of raft foundation by unbalanced distributions of a tower self-weight before the completion of a lateral load resisting system should be checked by construction sequence analysis, which should be performed by systematic combinations with structural health monitoring, construction compensation program, and construction panning. This paper presents the scheme of zone-based construction sequence analysis by using the existing commercial analysis program, to check the stability of high-rise building under construction. This scheme is applied to 3-dimensional structural analysis for a real high-rise building under construction. The analysis includes real construction zoning plans and schedules as well as creep and shrinkage effects and time-dependent properties of concrete. The simplified construction sequence and assumed material properties were continuously updated with the change on construction schedule and correlations with in-situ measurement data.

• Journal of the Korean Geophysical Society
• /
• v.9 no.4
• /
• pp.377-386
• /
• 2006

There is an inseparable relation between human race and engineering work. As world developed into highly industrialized society, a diversity of large structures is being built up correspondently to limited topographical circumstance. Though large structures are national establishments which provide us with convenience of life, there are some disastrous possibilities which were never predicted such as ground subsidence and degradation. It is very difficult to analyze the volume of total metamorphosis with the relative displacement measurement system which is now used and it is impossible to know whether there is structural metamorphosis within a permissible range of design or not. In this research with an object of 13-year-old earthen dam, through generating point-cloud which has 3D spatial coordinates(x, y, z) of this dam by means of 3D Laser Scanning, we can get real configuration data of slanting surface of this dam with this method of getting a number of 3D spatial coordinates(x, y, z). It gives 3D spatial model to us and we can get various information of this dam such as the distance of slanting surface of dam, dimensions and cubic volume. It can be made full use of as important source material of reinforcement and maintenance works to detect previously the bulging of the dam through this research.

• Clinics in Shoulder and Elbow
• /
• v.6 no.1
• /
• pp.55-66
• /
• 2003

Background: The purpose of this study was to evaluated results of arthroscopic treatment of the traumatic recurrent unidirectional posterior subluxation. Materials and Methods: We treated twenty-seven patients who had traumatic recurrent unidirectional posterior subluxation of the shoulder by arthroscopic labral repair and posterior capsular shift and prospectively evaluated for a mean of thirty-nine months (range,24 to 85 months). Patients who had posteroinferior instability, multidirectional instability, atraumatic onset, or revision cases were excluded. There were twenty-five male and two female patients with the mean age of twenty-one years (range, 14 to 33 years). All patients were involved in sports activity. All had a significant traumatic event prior to the onset of the instability. Stability, motion, three objective measurement (UCLA, ASES, and Rowe scores) and two subjective measurements (pain and function visual analogue scale) were evaluated. Results: The most common finding in magnetic resonance image-arthrogram was separation of the posteroinferior labrum without displacement in 9 patients, In arthroscopic examination, all patients had one or more lesions in the posterior inferior labrum and capsule. The most common finding was incomplete stripping of the posterior inferior labrum (18 patients). The posteroinferior capsule subjectively appeared to be stretched in twenty-two patients. At follow-up, all patients had improved shoulder function and scores(p < 0.01). All patients had stable shoulder by subjectivel and objectivel measurements, except one patient who had recurrent subluxation. All but one patient with postoperative recurrence were able to return to their prior sports activity with little or no limitation. Twenty-four patients were graded as having more than 90％ of shoulder function. Their were twenty-one excellent, five good, and one fair UCLA. scores. Pain sore improved from 4.5 to 0.2 point(p : 0.0001). Mean loss internal rotation was one vertebral level. None had operative complications. Conclusion: In conclusion, treatment outcomes of the traumatic unidirectional recurrent posterior subluxation are consistently reliable with respect to the stability, pain relief, and functional restoration by the arthroscopic posterior capsular shift procedure.