• Journal of Wetlands Research
• /
• v.25 no.4
• /
• pp.306-314
• /
• 2023

Stream sediments are an important component of water quality management because they are receptors of various pollutants such as heavy metals and organic matters emitted from upland sources and can be secondary pollution sources, adversely affecting water environment. To effectively manage the stream sediments, identification of primary sources of sediment contamination and source-associated control strategies will be required. We evaluated the performance of machine learning models in identifying primary sources of sediment contamination based on the physico-chemical properties of stream sediments. A total of 356 stream sediment data sets of 18 quality parameters including 10 heavy metal species(Cd, Cu, Pb, Ni, As, Zn, Cr, Hg, Li, and Al), 3 soil parameters(clay, silt, and sand fractions), and 5 water quality parameters(water content, loss on ignition, total organic carbon, total nitrogen, and total phosphorous) were collected near abandoned metal mines and industrial complexes across the four major river basins in Korea. Two machine learning algorithms, linear discriminant analysis (LDA) and support vector machine (SVM) classifiers were used to classify the sediments into four cases of different combinations of the sampling period and locations (i.e., mine in dry season, mine in wet season, industrial complex in dry season, and　industrial complex in wet season). Both models showed good performance in the classification, with SVM outperformed LDA; the accuracy values of LDA and SVM were 79.5% and 88.1%, respectively. An SVM ensemble model was used for multi-label classification of the multiple contamination sources inlcuding landuses in the upland areas within 1 km radius from the sampling sites. The results showed that the multi-label classifier was comparable performance with sinlgle-label SVM in classifying mines and industrial complexes, but was less accurate in classifying dominant land uses (50~60%). The poor performance of the multi-label SVM is likely due to the overfitting caused by small data sets compared to the complexity of the model. A larger data set might increase the performance of the machine learning models in identifying contamination sources.

• The korean journal of orthodontics
• /
• v.26 no.4
• /
• pp.414-420
• /
• 1996

Cephalometric measureements have disadvantage of representing cranio-facial structures in two dimension only and therefore they pose limitations in describing three-dimentional structures of cranio-facial region. More interests have been put on the correlation between the two planes. This study evaluated correlations between facial type score, which allows effects on malocclusion, growth change prediction and establishment of treatment method and prognosis, and measurements from submentovertex view. Cephalometric view and submentovertex view were taken of skeletal Class I adults with optimal profile and correlations between them have been observed. Following results were obtained: 1. To learn about factors that influence average condylar angulation, FACE, INT-CO-ANG, MN-CORPUS, CON-RATIO, GON-RATIO, MN-RATIO were used as variables and underwent multiple regression analysis. As a result, the following equation was obtained : CON-AVE=.l73(FACE)-.322(INT-CO-ANG)+36.34(GON-RATIO) +.420(MN-CORPUS) (($R^2=.85451$) 2. The following equation was obtained concerning facial type score. FACE= .050(CON-ANG)+.023(INT-CO-ANG)-.075(MN-CORPUS)($R^2=.31547$) 3. Among the submentovertex measurements, MN-CORPUS, CON-RATIO, GON-RATIO, MN-RATIO showed close correlations. (P<0.05) 4. Average condylar angualtions were $23.37^{\circ}$ on the right and $20.71^{\circ}$ on left. There was a difference between the two. FACE : facial type soore. CON-ANG: mean value of condylar angulation. CON-AVE: mean value of Rt. Lt condylar angulation. INT-CO-ANG : angle between Rt. Lt condylar axis. MN-CORPUS : angle formed between RT. Lt gonion & pogonion. CON-RATIO: lntercondylar distance/mandibular body length. GON-RATIO : intergonion distanoe/mandibular body length. MN-RATIO: lntermylohyoid distance/mandibular body length. MX-RATIO: intermaxillary tuberosity distance/ANS-PNS distance.

• Investigative Magnetic Resonance Imaging
• /
• v.1 no.1
• /
• pp.119-124
• /
• 1997

Purpose: To assess the utility of magnetic resonance(MR) cerebral blood volume (CBV) map in the evaluation of brain tumors. Materials and Methods: We performed perfusion MR imaing preoperatively in the consecutive IS patients with intracranial masses(3 meningiomas, 2 glioblastoma multiformes, 3 low grade gliomas, 1 lymphoma, 1 germinoma, 1 neurocytoma, 1 metastasis, 2 abscesses, 1 radionecrosis). The average age of the patients was 42 years (22yr -68yr), composed of 10 males and S females. All MR images were obtained at l.ST imager(Signa, CE Medical Systems, Milwaukee, Wisconsin). The regional CBV map was obtained on the theoretical basis of susceptibility difference induced by first pass circulation of contrast media. (contrast media: IScc of gadopentate dimeglumine, about 2ml/sec by hand, starting at 10 second after first baseline scan). For each patient, a total of 480 images (6 slices, 80 images/slice in 160 sec) were obtained by using gradient echo(CE) single shot echo-planar image(EPI) sequence (TR 2000ms, TE SOms, flip angle $90^{\circ}$, FOV $240{\times}240mm,{\;}matrix{\;}128{\times}128$, slice-thick/gap S/2.S). After data collection, the raw data were transferred to CE workstation and rCBV maps were generated from the numerical integration of ${\Delta}R2^{*} on a voxel by voxel basis, with home made software (${\Delta}R2^{*}=-ln (S/SO)/TE). For easy visual interpretation, relative RCB color coding with reference to the normal white matter was applied and color rCBV maps were obtained. The findings of perfusion MR image were retrospectively correlated with Cd-enhanced images with focus on the degree and extent of perfusion and contrast enhancement. Results: Two cases of glioblastoma multiforme with rim enhancement on Cd-enhanced Tl weighted image showed increased perfusion in the peripheral rim and decreased perfusion in the central necrosis portion. The low grade gliomas appeared as a low perfusion area with poorly defined margin. In 2 cases of brain abscess, the degree of perfusion was similar to that of the normal white matter in the peripheral enhancing rim and was low in the central portion. All meningiomas showed diffuse homogeneous increased perfusion of moderate or high degree. One each of lymphoma and germinoma showed homogenously decreased perfusion with well defined margin. The central neurocytoma showed multifocal increased perfusion areas of moderate or high degree. A few nodules of the multiple metastasis showed increased perfusion of moderate degree. One radionecrosis revealed multiple foci of increased perfusion within the area of decreased perfusion. Conclusion: The rCBV map appears to correlate well with the perfusion state of brain tumor, and may be helpful in discrimination between low grade and high grade gliomas. The further study is needed to clarify the role of perfusion MR image in the evaluation of brain tumor.

• Tuberculosis and Respiratory Diseases
• /
• v.60 no.2
• /
• pp.151-159
• /
• 2006

Background : Excision repair cross complementing gene 1 (ERCC1) not only has a protective role against carcinogens, but plays an important role in cisplatin-resistance via the repair of cisplatin-DNA adducts. This study investigated the association between the ERCC1 expression levels in sputum and survival after cisplatin-based chemotherapy in patients with inoperable non-small cell lung cancer (NSCLC). Methods : Using the sputum collected from 67 inoperable (stage IIIa-IV) NSCLC patients treated with either taxanes (33 cases) or gemcitabine (34 cases) plus cisplatin, the relative expression levels of ERCC1 and the expression of the tumor specific antigen, MAGE, were examined by the quantitative RT-PCR and RT-PCR, respectively. The response and survival were compared with the relative level of ERCC1 or MAGE expression and the treatment modality. Results : In the sputum, ERCC1 and MAGE was detected in 74.6% and 40.2% of patients, respectively. Using the median ERCC1 level, the patients were classified as having high or low ERCC1 expression. The median overall survival (MST) was significantly longer in patients with a high ERCC1 expression level than those with a low expression level (84 weeks vs. 44 weeks respectively, P=0.017). In the taxene-based treatment group, the MST was longer than the gemcitabine group (79 weeks vs. 47 weeks, respectively, P=0.03). The levels of ERCC1 were significantly higher in patients who were MAGE-positive (P=0.003). In the MAGE-negative patients, the MST was longer in the high ERCC1 group (103 weeks vs. 43 weeks, P=0.008), but not in the MAGE-positive patients (62 weeks vs. 44 weeks, P=0.348). Conclusion : ERCC1 expression in the sputum can be a prognostic factor for survival after chemotherapy in patients with inoperable NSCLC.

• Economic and Environmental Geology
• /
• v.48 no.1
• /
• pp.25-39
• /
• 2015

$CO_2$ geological storage plays an important role in reduction of greenhouse gas emissions, but there is a lack of research for CCS demonstration. To achieve the goal of CCS, storing $CO_2$ safely and permanently in underground geological formations, it is essential to understand the characteristics of them, such as total storage capacity, stability, etc. and establish an injection strategy. We perform the impedance inversion for the seismic data acquired from the Ulleung Basin in 2012. To review the possibility of $CO_2$ storage, we also construct porosity models and extract attributes of the prospects from the seismic data. To improve the quality of seismic data, amplitude preserved processing methods, SWD(Shallow Water Demultiple), SRME(Surface Related Multiple Elimination) and Radon Demultiple, are applied. Three well log data are also analysed, and the log correlations of each well are 0.648, 0.574 and 0.342, respectively. All wells are used in building the low-frequency model to generate more robust initial model. Simultaneous pre-stack inversion is performed on all of the 2D profiles and inverted P-impedance, S-impedance and Vp/Vs ratio are generated from the inversion process. With the porosity profiles generated from the seismic inversion process, the porous and non-porous zones can be identified for the purpose of the $CO_2$ sequestration initiative. More detailed characterization of the geological storage and the simulation of $CO_2$ migration might be an essential for the CCS demonstration.

• The Korean Journal of Nuclear Medicine Technology
• /
• v.16 no.2
• /
• pp.49-56
• /
• 2012

Purpose : Gated myocardial perfusion SPECT provides not only myocardial perfusion status, but various functional parameters of left ventricle (LV). The purpose of this study was to analyze ejection fraction (EF) for correlation and difference between $^{201}Tl$ gated myocardial perfusion SPECT and echocardiography depending on extent of perfusion defect, gender and LV volumes. Materials and Methods : From April 2011 to May 2012, we analyzed 291 patients (male:female =165:126; mean: $64.6{\pm}10.8$ years) who were examined both $^{201}Tl$ gated myocardial perfusion SPECT and echocardiography at less than 7 days apart in our hospital. 101 patients showed perfusion defect and the rest of the people without any defect. We applied automatic analysis (Quantitative gated SPECT, QGS), and calculated EF, End-diastolic volume (EDV) and End-systolic volume (ESV) from Stress (G-Stress) and Rest (G-Rest) studies. And we analyzed the correlation and difference for EF between $^{201}Tl$ gated SPECT and echocardiography. Results : The correlation of LVEF among G-Stress, G-Rest and echocardiography was quite a good (G-Stress vs. G-Rest: r=0.909, G-Stress vs. echocardiography: r=0.833, G-Rest vs. echocardiography: r=0.825). And there were significant differences in EDV, ESV and EF in total patients (p<0.01). The normal group showed significant difference in EF (p<0.01) and the group with perfusion defect also demonstrated significant difference (a group with reversible defect: p<0.01, fixed defect: p<0.01) depending on extent of perfusion defect. We analyzed difference in normal group by gender. In normal group, there was no significant difference (p>0.05) in EF from men. However, there was a significant difference (p<0.01) from women. When we classified two groups by average size of EDV in Korean women, there was no significant difference in a group of above average size of EDV (p>0.05). Conclusion : When compared among Stress and Rest of $^{201}Tl$ gated SPECT and echocardiography, we confirmed that there was a good correlation for LVEF. But there were significant differences among three studies. And extent of perfusion defect, gender and LV volumes are independent determinants of the accuracy of LVEF. So, it is hard to compare and interchange quantitative indices among modalities. We should take additional researches to prove results of our study.

• Investigative Magnetic Resonance Imaging
• /
• v.17 no.4
• /
• pp.267-274
• /
• 2013

Purpose : To re-evaluate additional clinical significance of the apparent diffusion coefficient (ADC) map in the inference of infarction stage, authors studied the evolution patterns of the DWI and the ADC map of the brain infarction. Materials and Methods: In 127 patients with cerebral infarctions, including follow-up checks, 199 studies were performed. They were classified as hourly (117 studies)-, daily (108 studies)-, weekly (62 studies)-based groups. The signal intensity (SI) was measured at the core of the infarction and contralateral area with ROI of 0.3 $cm^2$ or more on the images of the DWI and the ADC map, and calculated the ratios of SI and ADC value of the infarction area / contralateral normal area, and compared the patterns of the change according to the evolution. Results: Infarction was detected as early as 1 hour after the attack, and the ratio of SI in the DWI became over than 2 after 12 hours, which showed a plateau until the 6th day. Thereafter, it decreased slowly to 1 on the 30th day, and changed to lower SI than the surrounding brain. The ratio in the ADC map became 0.46 in 24 hours after the attack, and increased slowly to 1 in the 15th day. Thereafter, it became a higher value than the surrounding brain. Overall, the ratio in the ADC map changed earlier than in the DWI, and the ratio curves showed inverse pattern each other according to the evolution of the infarction. Conclusion: The evolution patterns of infarction on the ADC map showed an inverse curve of DWI curve, which means that the ADC value is accurately predictable from DWI, and the ADC map joined with the DWI seems helpful in the determination of subacute infarction between 15 to 30 days.

• Clinical and Experimental Pediatrics
• /
• v.50 no.3
• /
• pp.241-247
• /
• 2007

Purpose : Congenital muscular torticollis (CMT) is a common and benign congenital disorder of the musculoskeletal system in neonates and infants. The pathophysiology is that the sternocleidomastoid muscle (SCM) is shortened on the involved side by fibrosis, leading to ipsilateral tilt and contralateral rotation of the face and chin. In this study, we investigated the clinical features of CMT, the role of ultrasonography (USG) in prediction of prognoses and the clinical significance of early detection and treatment. Methods : Forty seven patients (M:F=31:16) were diagnosed as a CMT between March 2003 and May 2006. We reviewed age at diagnosis, physical findings, USG findings, treatment and therapeutic outcome from their medical records. Results : The median age at diagnosis was 90 days (18 days-9 years, 7 months) and the right side of neck was affected in more patients (right : left=26:21). Of 24 patients with a palpable neck mass, 21 had USG; 19 cases showed sternocleidomastoid tumor (SMT). In cases with no neck mass, USG was performed in 11 patients; seven had postural torticollis (POST), three had SMT and one had muscular torticollis (MT). Among 40 patients with follow-up, 36 had total resolution. There was negative correlation between the age at diagnosis and the recovery time, whereas the final outcome was not correlated with USG findings. However, the patients without positive findings in USG had earlier resolution (1 month vs 2.6 months, P=0.0008). The patients with SMT had earlier diagnosis and excellent outcomes. The patients with MT were delayed to diagnosis and had the longest time to resolve. Lastly, the patients with POST had delayed diagnoses, but they had excellent outcomes. Conclusion : Since the patients with delayed diagnoses, in despite of benign courses, may take a long time to resolve and rarely need surgical treatment, it is important to diagnose and treat early. This study showed that USG findings of the SCM may be used as predictive factors.

• Tuberculosis and Respiratory Diseases
• /
• v.39 no.4
• /
• pp.310-317
• /
• 1992

Background: Angiotensin converting enzyme is a glycoprotein peptidyldipeptide hydrolase which cleaves the c-terminal dipeptides of several oligopeptides. It is a menbrane-bound protein mainly synthesized by the endothelial cells. Since the lung has the largest capillary bed of any organ in the body, it is here that ACE acts on circulating substrates like angiotensin I and bradykinin. It is well known that ACE correlates with disease activity in sarcoidosis and also there are reports that changes in serum ACE activity are found in many acute and chronic lung diseases. So we planned this study to see if serum ACE activity can act as a prognostic factor in lung cancer. Methods: Forty-one newly diagnosed lung cancer patients were included in the study group. There were 19 patients with squamous cell lung cancer, 13 with adenocarcinoma, and 9 with small cell carcinoma. Patients were excluded from the study if they had high blood pressure, heart disease, liver disease, renal disease, or other lung disease. Serum ACE activity was analyzed according to cell type, staging, mode of treatment, and clinical response to treatment. Results: 1) There was no difference in serum ACE activity between lung cancer patients and the control group. Also no difference in serum ACE activity was found according to cancer cell type or staging. 2) In patients who underwent curative resection of lung cancer, serum ACE activity was decreased significantly after the operation. 3) In patients who were diagnosed as non-small cell lung cancer and were treated with 4 cycles of anti-cancer chemotherapy without clinical improvement, changes in serum ACE activity were not seen after the treatment. 4) In patients diagnosed as small cell lung cancer treated with 4 cycles of anti-cancer chemotherapy with clinical improvement, changes in serum ACE activity were also not observed. Conclusion: Serum ACE activity was decreased after lung resection but had no relation to cell type, staging, or clinical response to treatment in lung cancer patients. Therefore, serum ACE activity is not suitable in predicting clinical outcome of lung cancer patients.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.34 no.4
• /
• pp.297-305
• /
• 2018

Purpose: This study aimed to analyze stress distribution and maximum von Mises stress generated in intracoronal restorations and in tooth structures of mandibular molars with various types of cavity designs and materials. Materials and Methods: Three-dimensional solid models of mandible molar such as O inlay cavity with composite and gold (OR-C, OG-C), MO inlay cavity with composite and gold (MR-C, MG-C), and minimal invasive cavity on occlusal and proximal surfaces (OR-M, MR-M) were designed. To simulate masticatory force, static axial load with total force of 200 N was applied on the tooth at 10 occlusal contact points. A finite element analysis was performed to predict stress distribution generated by occlusal loading. Results: Restorations with minimal cavity design generated significantly lower values of von Mises stress (OR-M model: 26.8 MPa; MR-M model: 72.7 MPa) compared to those with conventional cavity design (341.9 MPa to 397.2 MPa). In tooth structure, magnitudes of maximum von Mises stresses were similar among models with conventional design (372.8 - 412.9 MPa) and models with minimal cavity design (361.1 - 384.4 MPa). Conclusion: Minimal invasive models generated smaller maximum von Mises stresses within restorations. Within the enamel, similar maximum von Mises stresses were observed for models with minimal cavity design and those with conventional design.