• Geomechanics and Engineering
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• v.39 no.2
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• pp.157-170
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• 2024

In the present study, the acoustic emission characteristics of hard sedimentary sandstone with varying bedding dip angles were examined through uniaxial compression tests using a rock mechanics creep apparatus combined with an acoustic emission system. The deformation and failure behavior of the sandstone was analyzed by correlating acoustic emission parameters with stress over time. A damage constitutive model was developed, incorporating cumulative acoustic emission ringing counts as a key parameter, with time acting as the intermediary. The findings indicate that, despite the differences in bedding dip angles, the stress-strain curves of the samples follow a similar pattern throughout the loading process, passing through four distinct phases: compaction, elastic deformation, yielding, and post-peak failure. The fracture patterns of the sandstone are influenced by the dip angle of the bedding. Acoustic emission parameters, including the ringing count, cumulative ringing count, and energy, align with these four stages of the stress-strain curve. During the compaction and elastic deformation phases, acoustic emissions remain in a quite state, with only brief spikes at points of rapid stress change. In the unstable fracture stage, acoustic emissions become highly active, while they return to a quite state in the post-fracture stage. The RA value of the acoustic emission displays a banded pattern as time progresses, with areas of dense clustering. When the stress curve declines, RA values enter an active period, mainly associated with the generation of shear cracks. Conversely, during periods of smooth stress progression, RA values remain in a quiet state, primarily linked to the formation of tensile cracks. The time-based damage constitutive model for layered sandstone effectively captures the entire process of rock fracture development.

• Korean Journal of Clinical Laboratory Science
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• v.37 no.2
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• pp.61-64
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• 2005

We compared the serum protein electrophoresis patterns in sera of diabetes patients (n=166) which showed more than 150 mg/dL of glucose. The concentrations of total protein, albumin, ${\alpha}1$-globulin, ${\alpha}2$-globulin, ${\beta}$-globulin and ${\gamma}$-globulin in sera of patients were $6.3{\pm}1.2g/dL$, $40.3{\pm}6.4%$, $4.9{\pm}2.3%$, $13.5{\pm}3.8%$, $15.5{\pm}3.9%$, and $25.9{\pm}5.8%$, respectively. The frequency of patients showed lower levels of total protein, albumin, ${\alpha}1$-globulin were 48.5%, 96.4%, and 33.7%. The frequency of patients showed higher levels of ${\alpha}2$-globulin, ${\beta}$-globulin, and ${\gamma}$-globulin were 56.6%, 47.0%, and 90.4%, respectively. This data suggests that the high concentration of glucose in blood may damage the kidney and liver. Also, the decrease of albumin and ${\alpha}1$-globulin and increase of ${\alpha}2$-globulin, ${\beta}$-globulin and ${\gamma}$-globulin shows that the concentration of glucose in blood will have an effect on the variation of serum protein electrophoretic patterns.

• Journal of the Korea Concrete Institute
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• v.24 no.6
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• pp.737-744
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• 2012

Hysteretic steel damper has been applied mainly to steel buildings. However, the usage in RC buildings is rapidly increasing recently. In order to apply the steel hysteretic damper in RC buildings, supporting elements of the damper should have sufficient strength and stiffness suitable for transferring damper forces to beams and walls. But due to the inevitable damage in reinforced concrete elements due to cracking, identification of the load transfer mechanism from damper to supporting element and hysteretic characteristics of the supporting element are extremely important in evaluating the damper behavior. Experiments were carried out on connection details between RC walls and supporting elements of the steel plate typed damper such as EaSy damper. The test results showed that fracture patterns of all specimens were almost identical except in the crack number and pattern associated with shear loading condition. Among the specimens, HD-3 shoed a well distributed cracks patterns along with good performance with respect to energy dissipation capacity, stiffness deterioration, and strength degradation.

• Journal of Haehwa Medicine
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• v.21 no.1
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• pp.11-21
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• 2012

New onset diabetes is a major complication after kidney transplantation. However, the natural course of posttransplantation diabetes mellitus (PTDM) remains unclear. The aim of this study was to demonstrate the detailed natural courses of PTDM according to the onset and persistency of hyperglycemia, and to investigate risk factors for development of different courses of PTDM in renal allograft recipients. The purpose of this study is to develop novel immune suppressants for PTDM using of action mechanism of them. The use of immunosuppressive drugs in transplanted patients is associated with the development of diabetes, possibly due to ${\beta}$-cell toxicity. To better understand the mechanisms leading to post-transplant diabetes, we investigated the actions of prolonged exposure of ${\beta}$-cells to therapeutical levels of tacrolimus (FK506) or cyclosporin A(CsA). The immunosuppressive drug cyclosporine(CsA) is a potent agent widely used after organ transplantations and various autoimmune disorders. After using CsA, some patients suffer severe complications including renal and vascular toxicity. The renal or vascular toxicity is influenced by the degree of the endothelial damage. FK506(tacrolimus) is a widely used immunosuppressive agent in the treatment of various medical conditions, including autoimmune disease, bone marrow and organ transplantations. We found some interesting clusters and confirmed the feasibility of cDNA microarray in the study of Immunosuppressant. In this study, we investigated gene expression patterns induced by Immunosuppressant in RIN-m5F of rat insulinoma cell line. Gene expressions evaluated using cDNA microarry in two clusters were increased or decreased. this study provides comprehensive comparison of the patterns of gene expression changes induced by CsA and FK506 in ${\beta}$-cells. This study could establish that the mode of action mechanism by which currently used insulin inhibitors inducing PTDM could be elucidated at least in part, which raises the possibility that novel immune suppressive PTDM can be developed. The molecular biological study on PTDM will also contribute the progress in diabetes research field as well as in that of PTDM.

• Atmosphere
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• v.22 no.1
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• pp.47-55
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• 2012

The characteristics of flow and pollutant dispersion for fire scenarios in an urban area are numerically investigated. A computational fluid dynamics (CFD) model coupled to a mesoscale weather research and forecasting (WRF) model is used in this study. In order to more accurately represent the effect of topography and buildings, the geographic information system (GIS) data is used as an input data of the CFD model. Considering prevailing wind, firing time, and firing points, four fire scenarios are setup in April 2008 when fire events occurred most frequently in recent five years. It is shown that the building configuration mainly determines wind speed and direction in the urban area. The pollutant dispersion patterns are different for each fire scenario, because of the influence of the detailed flow. The pollutant concentration is high in the horse-shoe vortex and recirculation zones (caused by buildings) close to the fire point. It thus means that the potential damage areas are different for each fire scenario due to the different flow and dispersion patterns. These results suggest that the accurate understanding of the urban flow is important to assess the effect of the pollutant dispersion caused by fire in an urban area. The present study also demonstrates that CFD model can be useful for the assessment of urban environment.

• Convergence Security Journal
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• v.14 no.2
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• pp.17-24
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• 2014

Form of backdoor penetration attacks "trapdoor" penetration points to bypass the security features and allow direct access to the data. Backdoor without modifying the source code is available, and even code generation can also be modified after compilation. This approach by rewriting the compiler when you compile the source code to insert a specific area in the back door can be due to the use of the method. Defense operations and the basic structure of the backdoor or off depending on the nature of the damage area can be a little different way. This study is based on the diagnosis of a back door operating mechanism acting backdoor analysis methods derived. Research purposes in advance of the attack patterns of malicious code can respond in a way that is intended to be developed. If we identify the structures of backdoor and the infections patterns through the analysis, in the future we can secure the useful information about malicious behaviors corresponding to hacking attacks.

• Journal of the Korean Geographical Society
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• v.49 no.1
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• pp.18-31
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• 2014

In this study, the spatio-temporal patterns of salty wind by typhoon in Jeju Island and their damages to windbreak forests are examined. To investigate these patterns, field trips as well as analyses of meteorological data were conducted after the attack of typhoon BOLAVEN in late August, 2012. Collected data show that salty wind damage in windbreak trees by the typhoon was distinct in the southern and eastern coastal areas due to the southeasterly gusts with less precipitation. Most of trees including Japanese cedar (Cryptomeria japonica) within 8km from the coast as well as pine trees (Pinus thunbergii) along the coasts were damaged by salty water driven by the typhoon, but the magnitude of its damages and recovery rates of damaged vegetation varied by species. These results indicate that prediction and proactive activities for salty wind are needed to reduce its damages to local vegetation particularly before the arrival of a dry typhoon accompanying gusty wind.

• Journal of the Korea Concrete Institute
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• v.25 no.1
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• pp.107-114
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• 2013

In this study we experimentally evaluated an impact resistant performance of fiber reinforced concrete in the moment of explosion by high-velocity projectile with emulsion explosive. To assess the impact resistance, we conducted the impact test of high-velocity projectile which reaches an impact speed of 350 m/s and the experiment of contact exploding emulsion explosive. As a result, bending and tensile performance depending on type of PVA, PE fiber (polyvinyl alcohol fiber, polyethylene fiber) and steel fiber affects destruction of rear side in the form of spalling. Destroying the backside of the concrete compressive strength compared to suppress the bending and tensile performance is affected. In addition, the experiment shows that the destruction patterns of concrete specimen producted by high velocity impact and contact explosion are significantly similar. Therefore, it is possible to predict the destruction patterns of specimens in the situation of contact explosion by high-velocity projectile.

• Earthquakes and Structures
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• v.18 no.5
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• pp.649-665
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• 2020

One of the most important issues in structural systems is evaluation of the margin of safety in low and mid-rise buildings against the progressive collapse mechanism due to the earthquake loads. In this paper, modeling of collapse propagation in structural elements of RC frame buildings is evaluated by tracing down the collapse points in beam and column structural elements, one after another, under earthquake loads and the influence of column removal is investigated on how the collapse expansion in beam and column structural members. For this reason, progressive collapse phenomenon is studied in 3-story and 5-story intermediate moment resisting frame buildings due to the corner and edge column removal in presence of the earthquake loads. In this way, distribution and propagation of the collapse in progressive collapse mechanism is studied, from the first element of the structure to the collapse of a large part of the building with investigating and comparing the results of nonlinear time history analyses (NLTHA) in presence of two-component accelograms proposed by FEMA_P695. Evaluation of the results, including the statistical survey of the number and sequence of the collapsed points in process of the collapse distribution in structural system, show that the progressive collapse distribution are special and similar in low-rise and mid-rise RC buildings due to the simultaneous effects of the column removal and the earthquake loads and various patterns of the progressive collapse distribution are proposed and presented to predict the collapse propagation in structural elements of similar buildings. So, the results of collapse distribution patterns and comparing the values of collapse can be utilized to provide practical methods in codes and guidelines to enhance the structural resistance against the progressive collapse mechanism and eventually, the value of damage can be controlled and minimized in similar buildings.

• Journal of Trauma and Injury
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• v.30 no.1
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• pp.6-11
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• 2017

Purpose: The establishment of the trauma system has changed the quality of trauma care in many countries. As one of the first designated level I trauma centers in Korea, we hypothesized that there were changes in laparotomy patterns and subsequent survival rates after the center was established. Methods: This was a 5-year retrospective study of all severe hemoperitoneum patients who were transfused with more than 10 units of packed red blood cells (RBCs) within 24 h of hospitalization. Variables related to trauma were collected throughout the study period, and the patients admitted before (period 1) and after (period 2) the establishment of a trauma center were compared. Results: Forty-five patients were managed from January 2009 to March 2015. The baseline patient characteristics of the two groups, including age, Injury Severity Score, blood pressure, and hemoglobin levels, were similar. The time to the operating room (OR) was $144.3{\pm}51.5$ min (period 1) and $79.9{\pm}44.1$ min (period 2) (p<0.0001). Damage control surgery (DCS) was performed in 17% of patients during period 1 and in 73% during period 2. The number of actual survivors (n=10) was higher than expected (n=8) in period 2. Conclusion: This is the first study analyzing the impact of a trauma center on the management of specific injuries, such as severe hemoperitoneum, in patients in Korea. During the study, the time to OR was shortened and DCS was used to a greater extent as a surgical procedure.