• Journal of Environmental Health Sciences
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• v.49 no.1
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• pp.48-56
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• 2023

Background: Few studies have assessed exposure to chemicals in the context of environmental vulnerability with a focus on exposure among populations living in certain geographical areas. Objectives: This study aimed to investigate cadmium exposure levels and kidney damage indices in environmentally and socioeconomically vulnerable populations, with further subgrouping according to economic status. Methods: Four areas were selected to represent geographical vulnerability (two environmentally vulnerable populations and two socioeconomically vulnerable populations). Among them, population groups with lower socioeconomic status (SES) were separately classified. Urinary cadmium (UCd), beta2-microglobulin (β2-MG), and N-acetyl-β-D-glucosaminidase (NAG) levels were analyzed in samples from 245 residents of these four areas. Results: Geometric means of concentrations of UCd (0.97~2.02 ㎍/g creatinine) in all selected populations (N, 245; mean age, 67.8~70.9 years old) were higher than the national reference values (0.39 for adults and 0.78 ㎍/g creatinine for people in their 60s). Participants with a lower SES had higher UCd and NAG concentrations than did non-low SES participants. In the lower SES group, there was a significant association between UCd and NAG concentrations; however, there was no such correlation in the non-low SES group. Conclusions: Consistent with the findings of previous studies evaluating chemical exposure and associated health effects in specific populations, the findings of this study suggest that individuals with a low SES may be more vulnerable to exposure and related health effects.

• Journal of the Korean Geotechnical Society
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• v.25 no.12
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• pp.57-67
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• 2009

Along with the advanced construction technologies, the maximum size of coarse aggregate used for dam construction ranges from several cm to 1m. Testing the original gradation samples is not only expensive but also causes many technical difficulties. Generally, indoor tests are performed on the samples with the parallel grading method after which the results are applied to the design and interpretation of the actual geotechnical structure. In order to anticipate the exact behavior characteristics for the geotechnical structure, it is necessary to understand the changes in the shear behavior. In this study, the Large Triaxial Test was performed on the parallel grading method samples that were restructured with river bed sand-gravel, with a different maximum size, which is the material that was used to construct Dam B in Korea. And the Stress - Strain characteristics of the parallel grading method samples and the characteristics of the shear strength were compared and analyzed. In the test results, the coarse-grained showed strain softening and expansion behavior of the volume, which became more obvious as the maximum size increased. The internal angle of friction and the shear strength appeared to increase as the maximum size of the parallel grading method sample increased.

• Journal of the Korean Geotechnical Society
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• v.39 no.7
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• pp.57-67
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• 2023

Slope failures during rainfall have been observed in mountainous areas of South Korea as a result of the presence of solar power facilities. The seepage behavior and pore pressure distribution differ from typical slopes due to the presence of impermeable solar panels, and the load imposed by the solar power structures also affects the slope behavior. This study aims to develop a method for evaluating the stability of slopes with solar power facilities and to analyze vulnerable points by considering the maximum slope displacement. To assess the slope stability and predict behavior while considering rainfall seepage, a combined seepage analysis and finite difference method numerical analysis were employed. For the selected site, various variables were assumed, including parameters related to the Soil Water Characteristic Curve, strength parameters that satisfy the Mohr-Coulomb failure criterion, soil properties, and topographic factors such as slope angle and bedrock depth. The factors with the most significant influence on the factor of safety (FOS) were identified. The presence of solar power facilities was found to affect the seepage distribution and FOS, resulting in a decreasing trend due to rainfall seepage. The maximum displacement points were concentrated near the upper (crest) and lower (toe) sections of the slope.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2020.08a
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• pp.64-64
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• 2020

우리나라의 고사리 재배면적은 2018년 기준 5,406ha 수준을 보이고 있으며 전체 산채류 재배면적에서 가장 높은 비중을 차지하고 있다. 고사리(Ferns)는 고사리 속(Pteridium spp.)에 속하는 양치식물의 총칭으로서 우리나라에는 22과 70속 272종이 분포되어 있는 것으로 보고되었다. 고사리의 어린 순에는 가식부 100g 당 칼슘 15.0mg, 칼륨 185.0mg 등이 함유되어 있으며 골다공증, 심혈관 질환 등에 효과가 있고 식이섬유로 인해 변비 예방에도 유용한 것으로 알려져 있다. 고사리 뿌리에서 추출한 전분은 중국 및 일본 등지에서 면류나 제과용으로 이용되고 있어 고사리 재배의 부가가치를 향상시킬 수 있는 방안으로 기대되고 있다. 본 연구에서는 고사리의 재배년차간에 뿌리 전분의 생산성과 이화학적 특성을 조사하기 위해 2020년 3월 26일 각 재배년차별로 굴취한 뿌리를 세척 후 고무망치로 파쇄하고 수침 방법을 사용해 추출한 전분의 이화학적 특성을 조사하였다. 재배년차간 고사리 뿌리의 생산성은 5년생과 7년생에서 3,000 kg/10a 이상으로 유의하게 높은 수량을 보였다. 세척한 고사리 뿌리를 24시간 sodiun metasulfite 4% V/W 용액에 수침하여 전분을 추출한 후 24시간 간격으로 3회에 걸쳐 진탕, 침전과 세척의 과정을 거친 후 조사한 전분 추출 수율은 뿌리 생체중 대비 6.8~7.6% 수준이었으며 재배년차간 차이는 없었다. 추출한 전분의 색도분석에서 L 값은 재배년차가 높아질수록 낮아지는 경향을 보였으나 a 값은 3.7~4.8, b 값은 13.5~15.9로서 뚜렷한 차이를 보이지 않았다. 고사리 뿌리전분의 호화특성에서 최고점도는 3년생 고사리 뿌리에서 추출한 전분이 557.4 RVU로 높은 값을 보였으나 재배년차간 통계적 유의성을 인정할 수는 없었으며, 최저검도에서는 5년생에서 추출한 전분이 269.9RVUfh 낮은 경향을 보였다. 또한 최대 점도 시간은 5.0~5.2hr로 재배년차간 차이는 없었으며 호화 저지온도는 67.0~68.9℃ 범위로 유의한 차이를 보이지 않았다. 고사리 뿌리에서 채취한 전분의 무기물 함량을 조사한 결과 황의 함량은 1년생에서 0.081%로 유의하게 높았으며, 인산 함량은 3년생에서 72mg/kg으로 가장 높았고 1년생에서 31mg/kg으로 가장 낮은 값을 나타냈다. 칼륨의 함량은 7년생에서 추출한 전분에서 376.3mg/kg으로 높았으나 재배년차 간 뚜렷한 경향을 보이지 않았으며 칼슘, 마그네슙 및 철분 함량에서는 5년생 전분에서 유의하게 높은 경향을 보였다.

• Korean Circulation Journal
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• v.53 no.12
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• pp.843-854
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• 2023

Background and Objectives: We evaluated the effect of diabetes on the relationship between body mass index (BMI) and clinical outcomes in patients following percutaneous coronary intervention (PCI) with drug-eluting stent implantation. Methods: A total of 6,688 patients who underwent PCI were selected from five different registries led by Korean Multicenter Angioplasty Team. They were categorized according to their BMI into the following groups: underweight (<18.5 kg/m²), normal weight (18.5-24.9 kg/m²), overweight to obese (≥25.0 kg/m²). Major adverse cardiac and cerebrovascular events (MACCE), defined as a composite of death, nonfatal myocardial infarction, stroke, and target-vessel revascularization, were compared according to the BMI categories (underweight, normal and overweight to obese group) and diabetic status. All subjects completed 1-year follow-up. Results: Among the 6,688 patients, 2,561 (38%) had diabetes. The underweight group compared to normal weight group had higher 1-year MACCE rate in both non-diabetic (adjusted hazard ratio [HR], 2.24; 95% confidence interval [CI], 1.04-4.84; p=0.039) and diabetic patients (adjusted HR, 2.86; 95% CI, 1.61-5.07; p<0.001). The overweight to obese group had a lower MACCE rate than the normal weight group in diabetic patients (adjusted HR, 0.67 [0.49-0.93]) but not in non-diabetic patients (adjusted HR, 1.06 [0.77-1.46]), with a significant interaction (p-interaction=0.025). Conclusions: Between the underweight and normal weight groups, the association between the BMI and clinical outcomes was consistent regardless of the presence of diabetes. However, better outcomes in overweight to obese over normal weight were observed only in diabetic patients. These results suggest that the association between BMI and clinical outcomes may differ according to the diabetic status.

• Korean Journal of Radiology
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• v.20 no.5
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• pp.759-772
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• 2019

Objective: To investigate the value of ultrasound (US) microflow assessment in distinguishing malignant from benign solid breast masses as well as the association between US parameters and histologic microvessel density (MVD). Materials and Methods: Ninety-eight breast masses (57 benign and 41 malignant) were examined using Superb Microvascular Imaging (SMI) and contrast-enhanced US (CEUS) before biopsy. Two radiologists evaluated the quantitative and qualitative vascular parameters on SMI (vascular index, morphology, distribution, and penetration) and CEUS (time-intensity curve analysis and enhancement characteristics). US parameters were compared between benign and malignant masses and the diagnostic performance was compared between SMI and CEUS. Subgroup analysis was performed according to lesion size. The effect of vascular parameters on downgrading Breast Imaging Reporting and Data System (BI-RADS) category 4A masses was evaluated. The association between histologic MVD and US parameters was analyzed. Results: Malignant masses were associated with a higher vascular index (15.1 ± 7.3 vs. 5.9 ± 5.6), complex vessel morphology (82.9% vs. 42.1%), central vascularity (95.1% vs. 59.6%), penetrating vessels (80.5% vs. 31.6%) on SMI (all, p < 0.001), as well as higher peak intensity (37.1 ± 25.7 vs. 17.0 ± 15.8, p < 0.001), slope (10.6 ± 11.2 vs. 3.9 ± 4.2, p = 0.001), area (1035.7 ± 726.9 vs. 458.2 ± 410.2, p < 0.001), hyperenhancement (95.1% vs. 70.2%, p = 0.005), centripetal enhancement (70.7% vs. 45.6%, p = 0.023), penetrating vessels (65.9% vs. 22.8%, p < 0.001), and perfusion defects (31.7% vs. 3.5%, p < 0.001) on CEUS (p ≤ 0.023). The areas under the receiver operating characteristic curve (AUCs) of SMI and CEUS were 0.853 and 0.841, respectively (p = 0.803). In 19 masses measuring < 10 mm, central vascularity on SMI was associated with malignancy (100% vs. 38.5%, p = 0.018). Considering all benign SMI parameters on the BI-RADS assessment, unnecessary biopsies could be avoided in 12 category 4A masses with improved AUCs (0.500 vs. 0.605, p < 0.001). US vascular parameters associated with malignancy showed higher MVD (p ≤ 0.016). MVD was higher in malignant masses than in benign masses, and malignant masses negative for estrogen receptor or positive for Ki67 had higher MVD (p < 0.05). Conclusion: US microflow assessment using SMI and CEUS is valuable in distinguishing malignant from benign solid breast masses, and US vascular parameters are associated with histologic MVD.

• Journal of Korean Neurosurgical Society
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• v.67 no.1
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• pp.60-72
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• 2024

Objective : Recently, robotic-assisted spine surgery (RASS) has been considered a minimally invasive and relatively accurate method. In total, 495 robotic-assisted pedicle screw fixation (RAPSF) procedures were attempted on 100 patients during a 14-month period. The current study aimed to analyze the accuracy, potential risk factors, and learning curve of RAPSF. Methods : This retrospective study evaluated the position of RAPSF using the Gertzbein and Robbins scale (GRS). The accuracy was analyzed using the ratio of the clinically acceptable group (GRS grades A and B), the dissatisfying group (GRS grades C, D, and E), and the Surgical Evaluation Assistant program. The RAPSF was divided into the no-breached group (GRS grade A) and breached group (GRS grades B, C, D, and E), and the potential risk factors of RAPSF were evaluated. The learning curve was analyzed by changes in robot-used time per screw and the occurrence tendency of breached and failed screws according to case accumulation. Results : The clinically acceptable group in RAPSF was 98.12%. In the analysis using the Surgical Evaluation Assistant program, the tip offset was 2.37±1.89 mm, the tail offset was 3.09±1.90 mm, and the angular offset was 3.72°±2.72°. In the analysis of potential risk factors, the difference in screw fixation level (p=0.009) and segmental distance between the tracker and the instrumented level (p=0.001) between the no-breached and breached group were statistically significant, but not for the other factors. The mean difference between the no-breach and breach groups was statistically significant in terms of pedicle width (p<0.001) and tail offset (p=0.042). In the learning curve analysis, the occurrence of breached and failed screws and the robot-used time per screw screws showed a significant decreasing trend. Conclusion : In the current study, RAPSF was highly accurate and the specific potential risk factors were not identified. However, pedicle width was presumed to be related to breached screw. Meanwhile, the robot-used time per screw and the incidence of breached and failed screws decreased with the learning curve.

• Journal of Chest Surgery
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• v.57 no.3
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• pp.242-251
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• 2024

Background: This study compared the outcomes of surgical aortic valve replacement (AVR) in patients aged 50 to 70 years based on the type of prosthetic valve used. Methods: We compared patients who underwent mechanical AVR to those who underwent bioprosthetic AVR at our institution between January 2000 and March 2019. Competing risk analysis and the inverse probability of treatment weighting (IPTW) method based on propensity score were employed for comparisons. Results: A total of 1,580 patients (984 patients with mechanical AVR; 596 patients with bioprosthetic AVR) were enrolled. There was no significant difference in early mortality between the mechanical AVR and bioprosthetic AVR groups (0.9% vs. 1.7%, p=0.177). After IPTW adjustment, the risk of all-cause mortality was significantly higher in the bioprosthetic AVR group than in the mechanical AVR group (hazard ratio [HR], 1.39; 95% confidence interval [CI], 1.07-1.80; p=0.014). Competing risk analysis revealed lower risks of stroke (sub-distributional hazard ratio [sHR], 0.44; 95% CI, 0.28-0.67; p<0.001) and anticoagulation-related bleeding (sHR, 0.35; 95% CI, 0.23-0.53; p<0.001) in the bioprosthetic AVR group. Conversely, the risk of aortic valve (AV) reintervention was higher in the bioprosthetic AVR group (sHR, 6.14; 95% CI, 3.17-11.93; p<0.001). Conclusion: Among patients aged 50 to 70 years who underwent surgical AVR, those receiving mechanical valves showed better survival than those with bioprosthetic valves. The mechanical AVR group exhibited a higher risk of stroke and anticoagulation-related bleeding, while the bioprosthetic AVR group showed a higher risk of AV reintervention.

• The Korean journal of internal medicine
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• v.39 no.2
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• pp.347-359
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• 2024

Background/Aims: Renal relapse has known to be a poor prognostic factor in patients with lupus nephritis (LN), but there were few studies that identified the risk factors of renal relapse in real world. We conducted this study based on 35-years of experience at a single center to find out predictors of renal relapse in Korean patients with LN after achieving complete response (CR). Methods: We retrospectively analyzed the clinical, laboratory, pathologic and therapeutic parameters in 296 patients of LN who reached CR. The cumulative risk and the independent risk factors for renal relapse were examined by Kaplan-Meier methods and Cox proportional hazards regression analyses, respectively. Results: The median follow-up period from CR was 123 months. Renal relapse had occurred in 157 patients. Renal relapse occurred in 38.2%, 57.6% and 67.9% of patients within 5-, 10-, and 20-year, respectively. The age at diagnosis of SLE and LN were significantly younger, and the proportions of severe proteinuria and serum hypoalbuminemia were higher in patients with renal relapse. Interestingly, the proportion of receiving cytotoxic maintenance treatment was higher in patients with renal relapse. In Cox proportional hazards regression analyses, only young-age onset of LN (by 10 years, HR = 0.779, p = 0.007) was identified to independent predictor of renal relapse. Conclusions: Young-age onset of LN was only independent predictor and the patients with severe proteinuria and serum hypoalbuminemia also tended to relapse more, despite of sufficient maintenance treatment. Studies on more effective maintenance treatment regimens and duration are needed to reduce renal relapse.

• Tuberculosis and Respiratory Diseases
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• v.65 no.1
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• pp.23-28
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• 2008

Background: Thymic epithelial tumors are the most common tumors affecting the anterior mediastinum. The aim of this study is to investigate clinical features of the patients who were diagnosed with thymic epithelial tumors at Pusan National University Hospital. Methods: We retrospectively reviewed the records of thirty-seven patients who were diagnosed with thymic epithelial tumors from Jan. 1997 to Jan. 2007. The pathological classification and clinical stage of the thymic epithelial tumors were based on the WHO classification and Masaoka's staging system. A total 37 patients were enrolled: 23 were males and 14 were females, and their mean age was 51.3 years. Results: Thirty patients presented symptoms at the time of diagnosis and their symptoms were as follows: chest pain (53%), dyspnea (23%), and cough (17%). Myasthenia gravis was diagnosed in five patients. With respect to the tumor staging, three cases (8%) were stage I, 10 cases (28%) were stage II, 12 cases (32%) were stage III, 6 cases (16%) were stage IVA and 6 cases (16%) were stage IVB. Twenty-four cases (67%) displayed stage III or IV disease. The pathological types according to the WHO classification were as follows: B1 (32%), C (23%), B3 (20%), B2 (16%), AB (6%) and A (3%). Twenty-four patients underwent thymothymectomy and four of these patients relapsed. Stage III or type B3 was common in the relapsed patients. Five patientsexpired. Stage IV or type B3 and C were common in the expired patients. Conclusion: In this study, stage III or IV disease and type B3 or C were common at the time of diagnosis and these findings might contribute to postoperative recurrence and a poor outcome.