• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.29 no.3
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• pp.289-297
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• 2019

Objectives: To identify the positive rate of and the risk factors associated with latent tuberculosis infection(LTBI) in mine workers, the objectives of the present study evaluated those among former mine workers. Methods: Between January 2015 and May 2017, former male mine workers who had been subjects for epidemiology research for work-related chronic obstructive pulmonary disease(COPD) and had received QuantiFERON-$TB^{(R)}$ Gold In-Tube(QFT-GIT) from the Institute of Occupation and Environment(IOE) under Korea Workers' Compensation and Welfare Service(KCOMWEL) were selected as the study subjects. To identify significant variables for increased risk of LTBI, logistic regression analysis was performed. Results: A total of 736 male former mine workers were selected as study subjects. The positive rate of LTBI among subjects was 69.2%(509/736). The current smoking[odds ratio(OR), 2.3; 95% confidence interval(CI), 1.1-4.9], COPD(OR, 1.4; 95% CI, 0.9-2.3), department loading(OR, 1.8; 95% CI, 0.9-3.4) and mining(OR, 1.5; 95% CI, 0.9-2.5), and working duration of over 20(OR, 1.6; 95% CI, 0.9-3.1) and over 30 years(OR, 2.2; 95% CI, 0.9-4.9) were associated with increased risk of LTBI. The interferon-gamma(IFN-${\gamma}$) level after stimulation with Mycobacterium tuberculosis(MTB)-specific antigens showed a significantly negative correlation with age(r=-0.126). Conclusions: The present study determined that the high positive rate of LTBI among mine workers was associated with not only the host factors but also the occupational exposure to mine dust.

• PNF and Movement
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• v.21 no.1
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• pp.27-35
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• 2023

Purpose: Hallux valgus (HV) is one of the most common chronic foot disorders, occurring when the first toe deviates laterally toward the other toe. HV impairs muscle strength and affects gait function (postural sway and gait speed). Thus, this study aims to investigate using the FDM system the effect of wearing braces on gait while wearing a virtual reality (VR) device. Methods: This study was conducted on 28 healthy adults with HV of 15 degrees or more. To compare differences in walking, depending on whether a toe brace can be worn, the subject walked without wearing anything, walked after wearing the VR device, and walked after wearing the VR device and the toe brace, and the FDM system was used for the gait ability measurement analysis. Results: As a result of a one-way repeated analysis of variance, the walking speed-related variables (cadence, velocity, etc.) in the HV group were higher during comfortable walking. In addition, walking while wearing a VR device and walking while wearing a VR device and a toe brace demonstrated more significant values in terms of six gait parameters (double stance phase, loading response, stage, stage, stage, and stage). The maximum pressure of the forefoot was significantly reduced when walking while wearing a VR device and a toe brace compared to comfortable walking, but in all variables, there was no statistically significant difference between walking while wearing a VR device and walking while wearing a VR device and a toe brace. Conclusion: Orthosis with a VR device during gait (OVG) and gait with a VR device (GVR) affect gait in HV patients. However, there was no significant difference between GVR and OVG. Thus, it is necessary to conduct experiments on various HV angles and increase the duration of wearing the toe brace.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.4D
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• pp.323-330
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• 2010

The time in port for vessels is one of the important factors for analyzing the operation status and the capacity of ports. In addition, the time in port for vessels can be directly used for estimating the greenhouse gas emissions resulted from vessels in port. However, it is unclear which variables can affect the time in port for vessels and what the marginal effect of each variable is. With these challenges in mind, the study analyzes the time in port for vessels arriving and departing port of Busan by using a parametric survival model. The results show that the log-logistic accelerated failure time model is appropriate to explain the time in port for 19,167 vessels arriving and departing port of Busan in 2008, in which the time in port is significantly affected by gross tonnage of vessels, service capacity of terminal, and vessel type. This study also shows that the greenhouse gas emission resulted from full-container vessels, which accounted for about 61% of all vessels with loading/unloading purpose arriving and departing port of Busan in 2008, is about "17 ton/vessel" in the boundary of port of Busan. However, the hotelling greenhouse gas emissions resulted from non-container vessels (3,774 vessels; 20%) are greater than those from the full-container vessels. Hence, it is necessary to take into account more efficient port management polices and technologies to reduce the service time of non-container vessels in port of Busan.

• Journal of the Korean Recycled Construction Resources Institute
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• v.11 no.3
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• pp.184-191
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• 2023

With increasing corrosion in RC (Reinforced Concrete) structures, cracks occurred due to corrosion products and bearing load resistance decreased. In this study, corrosion was induced through an accelerated corrosion test (ICM: Impressed Current Method) with 140 hours of duration, and changes in USV (Ultra-Sonic Velocity), flexural failure load, and corrosion weight were evaluated before and after corrosion test. Three levels of cover depth (20 mm, 30 mm, and 40 mm) were considered, and the initial cracking period increased and the rust around steel decreased with increasing cover depth. In addition, the USV linearly decreased with decreasing cover depth and increasing amount of corrosion. In the flexural loading test, the bending capacity decreased by more than 10% due to corrosion, but a clear correlation could not be obtained since the corrosion ratio was small, so that the effect of slip was greater than that of reduced cross-sectional area of steel due to corrosion. As cover depth increased, the produced corrosion amount and USV changed with a clear linear relationship, and the cracking period due to corrosion could be estimated by the gradient of the measured corrosion current.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.28 no.4
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• pp.121-132
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• 2023

Marine heatwaves (MHWs), referring to anomalously high sea surface temperatures, have drawn significant attention from marine scientists due to their broad impacts on the surface marine ecosystem, fisheries, weather patterns, and various human activities. In this study, we examined the impact of the distribution of Changjiang diluted water (CDW), a significant factor causing oceanic property changes in the East China Sea (ECS) during the summer, on MHWs. The surface salinity distribution in the ECS indicates that from June to August, the eastern extension of the CDW influences areas as far as Jeju Island and the Korea Strait. In September, however, the CDW tends to reside in the Changjiang estuary. Through the Empirical Orthogonal Function analysis of the cumulative intensity of MHWs during the summer, we extracted the loading vector of the first mode and its principal component time series to conduct a correlation analysis with the distribution of the CDW. The results revealed a strong negative spatial correlation between areas of the CDW and regions with high cumulative intensity of MHWs, indicating that the reinforcement of stratification due to low-salinity water can increase the intensity and duration of MHWs. This study suggests that the CDW may still influence the spatial distribution of MHWs in the region, highlighting the importance of oceanic environmental factors in the occurrence of MHWs in the waters surrounding the Korean Peninsula.

• Membrane Journal
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• v.34 no.1
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• pp.38-49
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• 2024

Wastewater treatment using membrane bioreactors has been extensively used to alleviate water shortage and pollution by improving the quality of the treated water discharged into the environment. However, membrane biofouling persistently holds back an MBR process by reducing the process efficiency. Herein, we synthesized carbon nanospheres (CNSs) with many hydrophilic oxygen groups and utilized them as an additive to prepare high-performance ultrafiltration (UF) membranes with hydrophilicity and porous pore structure. CNSs were found to form crescent-shaped pores on the membrane surface, increasing the mean surface pore size by about 40% without causing significant defects larger than bubble points, as the CNS content increased by 4.6 wt%. In addition, the porous pore structure of CNS composite membranes was also attributable to the CNS's isotropic morphologies and relatively low particle number density because the aforementioned properties contributed to preventing the polymer solution viscosity from soaring with the loading of CNS. However, too porous structure compromised the mechanical properties, such that CNS2.3 was the best from a comprehensive consideration including the pore structure and mechanical properties. As a result, CNS2.3 showed not only 2 times higher water permeability than CNS0 but also 5 times longer operation duration until membrane cleaning was required.

• Journal of the Korean Geotechnical Society
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• v.20 no.5
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• pp.145-159
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• 2004

The conventional method for assessment of liquefaction potential proposed by Seed and Idriss has been widely used in most countries because of simplicity of tests. Even though various data such as stress, strain, stress path, and excess pore water pressure can be obtained from the dynamic test, especially, two simple experimental data such as the maximum deviatoric stress and the number of cycles at liquefaction have been used in the conventional assessment. In this study, a new detailed assessment for liquefaction potential to reflect both characteristics of real earthquake motion and dynamic soil resistance is proposed and verified. In the assessment, the safety factor of the liquefaction potential at a given depth of a site can be obtained by the ratio of a resistible cumulative plastic shear strain determined through the performance of the conventional cyclic test and a driving cumulative plastic shear strain calculated from the shear strain time history through the ground response analysis. The last point to cumulate the driving plastic shear strain to initiate soil liquefaction is important for this assessment. From the result of cyclic triaxial test using real earthquake motions, it was concluded that liquefaction under the impact-type earthquake loads would initiate as soon as a peak loading signal was reached. The driving cumulative plastic shear strain, therefore, can be determined by adding all plastic shear strains obtained from the ground response analysis up to the peak point. Through the verification of the proposed assessment, it can be concluded that the proposed assessment for liquefaction potential can be a progressive method to reflect both characteristics of the unique soil resistance and earthquake parameters such as peak earthquake signal, significant duration time, earthquake loading type, and magnitude.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.5A
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• pp.557-564
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• 2009

In recent years, there have been numerous explosion-related accidents due to military and terrorist activities. Such incidents caused not only damages to structures but also human casualties, especially in urban areas. To protect structures and save human lives against explosion accidents, better understanding of the explosion effect on structures is needed. In an explosion, the blast overpressure is applied to concrete structures as an impulsive load of extremely short duration with very high pressure and heat. Generally, concrete is known to have a relatively high blast resistance compared to other construction materials. However, information and test results related to the blast experiment of internal and external have been limited due to military and national security reasons. Therefore, in this paper, to evaluate blast effect on reinforced have concrete structure and its protective performance, blast tests are carried out with $1.0m{\times}1.0m{\times}150mm$ reinforce concrete slab structure at the Agency for Defence Development. The standoff blast distance is 1.5 m and the preliminary tests consists with TNT 9 lbs and TNT 35 lbs and the main tests used ANFO 35 lbs. It is the first ever blast experiment for nonmilitary purposes domestically. In this paper, based on the basic experiment procedure and measurement details for acquiring structural behavior data, the blast experimental measurement system and procedure are established details. The procedure of blast experiments are based on the established measurement system which consists of sensor, signal conditioner, DAQ system, software. It can be used as basic research references for related research areas, which include protective design and effective behavior measurements of structure under blast loading.

• Pediatric Infection and Vaccine
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• v.21 no.1
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• pp.9-21
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• 2014

Purpose: To determine the clinical significance of voriconazole therapeutic drug monitoring (TDM) in the pediatric population. Methods: Twenty-eight patients with invasive fungal infections administered with voriconazole from July 2010 to June 2012 were investigated retrospectively. Fourteen received TDM, and 143 trough concentrations were analyzed. All 28 patients were assessed for adverse events and treatment response six weeks into treatment, and at the end. Results: Out of 143 samples, 53.1% were within therapeutic range (1.0-5.5 mg/L). Patients administered with the same loading (6 mg/kg/dose) and maintenance (4 mg/kg/dose) dosages prior to initial TDM showed highly variable drug levels. Adverse events occurred in 9 of 14 patients (64.3%) in both the TDM and non-TDM group. In the TDM group, voriconazole-related encephalopathy (n=2, 14.3%) and aspartate aminotransferase (AST) or alanine aminotransferase (ALT) elevation (n=8, 57.1 %) occurred with serum levels in the toxic range (>5.5 mg/L), whereas blurred-vision (n=2, 14.3%) occurred within the therapeutic range (1.18 mg/L and 3.9 mg/L). The frequency of voriconazole discontinuation due to adverse events was lower in the TDM group (0.0% vs. 18.2%, P =0.481). Overall, 57.2% of the patients in the TDM group versus 14.3% in the non-TDM group showed clinical response after 6 weeks (P =0.055), whereas 21.4% in the TDM group versus 14.3% in the non-TDM group showed response at final outcome (P =0.664). In the TDM group, >67.0% of the serum levels were within therapeutic range for the first 6 weeks; however 45.5% were within therapeutic range for the entire duration. Conclusion: Routine TDM is recommended for optimizing the therapeutic effects of voriconazole.

• The Journal of the Korean dental association
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• v.50 no.12
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• pp.743-754
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• 2012

urpose : The purpose of this study was to evaluate the US II plus/GS II Osstem$^{(R)}$ implants through the study for the clinical success rate during the installation of the Osstem¢Á implants after bone graft. Materials and Methods : This study was researched in the 4 medical institutions: Chonnam National University, Chosun University, Bundang Seoul National University Hospital, and FM dental clinic from May, 2002 to September, 2009. Based on the total number of 60 patients whose treatment was the installation of the US II plus/GS II Osstem¢Á implants after bone graft, we evaluated success rate of implants. We analysis the distribution of patient's age and gender, edentulous area, bone type, fixture length and diameter, installation and loading time, donor site, bone graft material and method, antagonistic teeth, and survival and success rate. From these analyses we got the following results. Results : 1. In this study, the total number of patients who have been installed with US II plus implant was 27, and total of 52 implants were installed. The average age was 38.9, with 16 male, and 11 female patients. 2. The total number of patients who have been installed with GS II implant was 33, and total of 54 implants were installed. The average age was 49.7, with 24 male, and 9 female patients. 3. As for bone graft method, either autogenous bone or a mix of autogenous and heterogenous bone was used(88.4%) for US II plus. Chin, iliac, and Maxillary tuberosity were the donor sites for autogenous bone graft, and onlay method of bone graft was performed. 4. Allogenic bone or a mix of autogenous and heterogenous bone was used(77.8%) for GS II. Chin, ramus, and tibia were the donor sites for autogenous bone graft, and GBR method of bone graft was performed. 5. The duration from the installation of implants to setting of final prosthesis was average of 16 months and 10 months for US II plus and GS II respectively. Also, the final follow up period was average of 31 months and 28 months respectively. During this period, one GS II implant was removed from 1 patient due to failure of early osteointegration. 6. The survival rates were 100% and 98.1%, and success rates were 94.2% and 94.4% for US II plus and GS II implant respectively. Conclusion : On the evaluation of our clinical study, both US II plus and GS II Osstem¢Á implants showed the excellent clinical results after bone graft.