• The Journal of Engineering Geology
• /
• v.20 no.1
• /
• pp.47-60
• /
• 2010

This study is focused on the analysis of tunnel behavior to estimate the stability on tunnel design. An estimation method was proposed as a hybrid consideration, which contains the displacement analysis by 3D numerical simulation, the maximum displacement obtained after field measurement, and an assessment of tunnel stability using a deformation analysis proposed by Sakurai(1988, 1997). The points of case study by Sakurai(1988, 1997) were replotted considering his analysis. From the new analysis of the tunnel case study, the trend line for analyzed points is analogized, which curve is divided into stable, unstable and failure zone. To evaluate the estimation method, a special shape of railway tunnel was selected, which are the Inchon international airport rail way connected to subway line 9 in Gimpo, Korea. The point s of upper and below track on the Inchon international airport rail way were satisfied to the stability of tunnel after reinforcing. Also the points shows the higher apparent Young's modulus, which resulted from improvement on shear strength by the micro silica grouting and the supporting of umbrella method. Therefore, if new analysis used, proper tunnel reinforcing method could be selected according to tunnel strain and geological property.

• Fire Science and Engineering
• /
• v.27 no.3
• /
• pp.85-93
• /
• 2013

Modern fire fighting jobs have been expanded to include areas of rescue, emergency medical service as well as conventional fire suppression, so that load for fire fighting jobs has been increased. Specifically, musculoskeletal disorders (MSDs) such as low back injury have been considered as one of major industrial hazards in heavy manual material handling during fire fighting jobs. This study tried to evaluate risk levels and to prepare background for reducing risk levels associated with heavy manual material handling during fire fighting jobs. This study applied two major tools in evaluating heavy manual material handling jobs which were NLE (NIOSH Lifting Equation) and 3DSSPP (3D Static Strength Prediction Program). A risk index in terms of heavy manual material handling during fire fighting jobs was identified. This index consisted of seven risk levels ranged from nine points (the first level) to three points (the seventh level). There was no job associated with the first level (the highest risk level) of index. There was only one job (life saving job) belonging to the second level (the second highest risk level) of index. The third level had jobs such as usage of destruction equipment and lifting patient. A total of basic eighteen jobs was categorized into six different levels (2nd-7th levels) of index. The outcome of the study could provide a good basis for conducting job intervention, preparing good equipment and developing good education program in order to prevent and reduce MSDs including low back injury of fire fighting jobs.

• Journal of Chest Surgery
• /
• v.36 no.5
• /
• pp.329-334
• /
• 2003

Backgound: Cryoablation and radiofrequency ablation have been used to treat the atrial fibrillation. Some reports insisted that the microwave ablation Is a better method for a deep and extensive lesion. Material and Method: From December 2001 to July 2002, we peformed 8 microwave ablations in patients who needed mitral valve surgery (7 MVR, 1 MVR+AVR). There were 3 men and 5 women, and their mean age was 43.4$\pm$8.3 years and mean follow up period was 5.6$\pm$2.4 months respectively. The microwave was applied on endocardium or epicardium by Lynx (Afx, inc.) using a power of 45 watts for 25 seconds. We studied the left atrial dimension, the left atrial function and the sinus conversion with echocardiography and electro-cardiography at three times; 1) before the operation, 2) immediately after the operation, and 3) 6 months after the operation. Result: There was no complication and no mortality. The mean aortic clamping time was 104.6$\pm$25.0 minutes, and the mean total bypass time was 130.5$\pm$28.7 minutes. The rate of sinus conversion was 75%, A wave across the mitral valve was a mean of 77.0$\pm$24.8 cm/sec, and the AVE was a mean of 0.46$\pm$0.17 at 5.6 months postoperatively Conclusion: There was no difference in the early result of microwave ablation compared to other methods. The microwave ablation was an acceptable method due to its convenient application especially in beating heart.

• Proceedings of the Korean Radioactive Waste Society Conference
• /
• 2005.06a
• /
• pp.335-343
• /
• 2005

The Methodology of burnup calculation with EPMA test set up in this study. The spent fuel from PWR nuclear power plant was used as specimen. This $UO_2$ fuel with $3.2\%$ of enrichment had been irradiated up to 35,000 MWd/MTU(reference data). The burnup is very important factor for nuclear fuel to estimate all fuel behaviors in reactor. To measure amounts of fission products and actinides for the burnup calcualation, chemical analysis (destructive method) has been used but it mattes long experimental time and second radio-wastes. In this study, EPMA test was available to measure amount of fission products. Neodymium is able to be detected and quantified. It can be compared with the results from chemical analysis and ORIGEN-2 code calculation. Concentration of Nd from EPMA test showed good agreement with result of ORIGEN-2 code in the same burnup.

• The Journal of Engineering Geology
• /
• v.21 no.4
• /
• pp.281-293
• /
• 2011

We investigated the causes and characteristics of a landslide at Hwangryeong Mountain, Busan, based on aerial photos, annual precipitation data, rock fracture patterns, and geomorphic features using GIS Software, and a statistical analysis of tilted trees. The analyzed slope shows evidence of a previous slope failure event and the possibility of future failures. Although the NW-SE trending slope was relatively stable until 1975, a large-scale slope failure occurred between 1975 and 1985 due to complex factors, including favorably oriented geologic structures, human activity, and heavy rain. This indicates that a detailed study of geologic structures, slope stability, and rainfall characteristics is important for slope cuttings that could be a major factor and cause of urban landsliding events. The statistic analysis of tilted trees shows a slow progressive creeping type of mass wasting with rock falls oblique to the dip of the slope, with the slope having moved towards the west since 1985. A concentration of tree tilting has developed on the northwestern part of the slope, which could reach critical levels in the future. The analysis of deformed trees is a useful tool for understanding landslides and for predicting and preventing future landslide events.

• Applied Microscopy
• /
• v.35 no.3
• /
• pp.113-119
• /
• 2005

The Methodology of burnup calculation with EPMA test set up in this study. The spent fuel from PWR nuclear power plant was used as specimen. This $UO_2$ fuel with 3.2% of enrichment had been irradiated up to 35,000 MWd/MTU. The burnup is very important factor for nuclear fuel to estimate all fuel behaviors in reactor. To measure amounts of fission products and actinides for the burnup calcualation, destructive method analysis has been used but it makes long experimental time and second radio-wastes. In this study, EPMA test was available to measure amount of fission products. Neodymium is able to be detected and quantified. It can be compared with the results from chemical analysis and ORIGEN-2 code calculation. Concentration of Nd from EPMA test showed good agreement with result of ORIGEN-2 code in the same burnup.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.16 no.5
• /
• pp.112-120
• /
• 2012

A numerical model considering the internal vaporization and the creep effect, in the form of a analytical program, for tracing the behavior of high strength concrete(HSC) members exposed to fire is presented. The two stages, i.e., spalling procedure and fire resistance time, associated with the thermal, moisture flow, creep and structural analysis, for the prediction of fire resistance behavior are explained. The use of the analytical program for tracing the response of HSC member from the initial pre-loading stage to collapse, due to fire, is demonstrated. Moisture evaporates, when concrete is exposed to fire, not only at concrete surface but also at inside the concrete to adjust the equilibrium and transfer properties of moisture. Finite element method is employed to facilitate the moisture diffusion analysis for any position of member, so that the prediction method of the moisture distribution inside the concrete members at fire is developed. The validity of the numerical model used in this program is established by comparing the predictions from this program with results from others fire resistance tests. The analytical program can be used to predict the fire resistance of HSC members for any value of the significant parameters, such as load, sectional dimensions, member length, and concrete strength.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.20 no.5
• /
• pp.35-43
• /
• 2016

In order to understand rotation behavior of high strength steel endplate connections under fire, this study is compared with existing studies conducted using FEA program. Eurocode 3 presents the three failure modes according to the prediction of bending resistance moment. The parameters of analysis model are temperature, thickness and steel materials of endplate. The rotation stiffness, and bending resistance moment are analyzed according to the parameters. The change of rotation stiffness and bending resistance moment are analyzed about the parameters, regression equations are suggested the change of high strength steel endplate connections. Consequently, the regression equations were proposed as the linear and quadratic equation. The moment ratio of high strength steel under fire was more reduced than the carbon steel, and was small effect about the thickness. When the high strength steel under fire was compared with at ambient temperature, the slope of initial rotation stiffness reduced, the increment ratio of moment was slow, and the change of plastic rotation stiffness wasn't effect by the thickness increase.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.1 no.2
• /
• pp.160-164
• /
• 1999

Subsurface environments, including the intermediate vadose zone and aquifers, may be contributing to increased atmospheric concentrations of $N_2$O. Denitrification appears to be the major source of $N_2$O in the subsurface environment. In the intermediate vadose zone, the level of denitrifying activity is dependent on the soil morphology, particularly stratified layers within the soil profile, which impede water and solute movement and create conditions favorable for denitrification. Movement of organic C from the soil surface appears to support denitrifying activity by providing an energy source and increasing the consumption of $O_2$. Denitrirication and $N_2$O production have been observed in aquifers but appear to be of greatest significance in shallow unconfined aquifers. The lack of organic C, N $O_2$, or anaerobiosis is often a limiting factor for activity but seems to be site specific. The presence of denitrifying bacteria does not appear to be a major limitation, based on published results, but the ubiquity of denitrifiers in subsurface environments needs to be confirmed. The fate of the $N_2$O produced in subsurface environments is unknown. Transport of $N_2$O by up ward diffusion, by outgassing at contacts with surface waters, and by ground water use need to be quantified to determine the contribution to atmospheric $N_2$O. Contamination of subsurface environment with N $O_3$$^{ }$ and organics has the potential for increasing the contribution to atmospheric $N_2$O by enhancing denitrification .

• Journal of the Korean Geosynthetics Society
• /
• v.11 no.2
• /
• pp.1-9
• /
• 2012

In order to review the utility of Lade's single hardening constitutive model, a series of isotropic compression-expansion tests and consolidated drained triaxial tests including as CTC, TC, RTC, and OSP were performed by Baekma river sand with various of stress path. Parameters required in model were determined using these tests. The accuracy of analysis was reviewed by back analysis of test results used to determine the 11 parameters of soil property through the test of each stress path. Also. for verifying the accuracy of prediction for the stress-strain behavior using failure criterion related 9 parameters with correlational equation and constant and yield criterion related parameters h, ${\alpha}$ and ${\eta}_1$, when stress path is different with each other, it has been obtained in the review result of stress path dependent characteristics of the constitutional model through the analyzing results of CTC, TC, RTC, OSP, and fine silica sand tests.