• Proceedings of the Korean Vacuum Society Conference
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.450.2-450.2
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• 2014

열전재료는 열-전기가 상호 가역적으로 변하는 재료로서, 최근 에너지 변환소재 분야에서 각광받고 있다. 열전재료의 특성 효율은 무차원 열전 성능지수(dimensionless figure of merit, $ZT={\alpha}2{\sigma}T/{\kappa}$)로 나타낼 수 있다. 여기서 ${\alpha}$는 제벡계수(Seebeck coefficient), ${\sigma}$는 전기전도도(electrical conductivity), ${\kappa}$는 열전도도(thermal conductivity), T는 Kelvin 온도를 나타낸다. 500 K에서 800 K까지의 중온 영역에서 우수한 열전특성을 보이는 $Mg_2X$ (X=Si, Ge, Sn)와 이들의 고용체는 성분원소가 독성이 없고, 매장량이 많아 친환경 열전 재료로 각광받고 있다. $Mg_2X$ 고용체 중 $Mg_2Si_{1-x}Ge_x$는 기존 $Mn_2Si$, $Mg_2Ge$, $Mg_2Sn$계 보다 더 우수한 열전 성능지수를 보인다. 다양한 제조 방법들이 시도되고 있으나, 조성설계 및 구조, 성능 조절의 어려움이 있고, Mg의 산화와 휘발 및 Mg, Si, Ge의 융점 차이가 크고 중력 편석과 반응하지 않은 원소들로 인해 제조가 상당히 어렵다. Sb가 도핑된 $Mg_2Si_{0.5}Ge_{0.5}Sb_y$ (y=0, 0.005, 0.01, 0.02, 0.03) 고용체를 고상반응으로 합성하고 진공열간 압축성형을 통해 성공적으로 제조하였다. 고용 상을 확인하기 위하여 X선 회절분석을 실시하였고, 고용체 형성과 도핑에 따른 전기적 특성변화를 평가하기 위해 Hall 효과를 측정하여 전자 이동특성을 분석하였고, 323~823 K까지 전기전도도, 제벡계수, 열전도도의 측정을 통해 열전 성능지수를 평가하였다.

• Journal of Korea Water Resources Association
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• 제30권1호
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• pp.3-13
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• 1997

Modifications of Prandtl's mixing length theory were used to obtain a power velocity distribution in which the coefficient and exponent are variable over a range from 1/4 to 1/7. A simple suspended-sediment concentration distribution was developed which can be associated with this modified velocity distribution. Using nominal values of ${\beta}$=1.0, $\kappa$=0.4 and visual accumulation tube values of fall velocity, the comparison between theory and field measurements by the USGS on the Rio Grande is fair. Doubling the value of the exponent results in a good comparison. Further research is needed to be able to better choose ${\beta}$, $\kappa$, and fall velocity values, but such research will not be able to account for the effects of large-scale turbulence and secondary flows. In a pragmatic sense, a special set of fairly detailed measurements can establish coefficients and exponents for any gaging site.

• Journal of Wetlands Research
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• 제16권3호
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• pp.393-401
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• 2014

The purpose of this study was to investigate the objective impact in accuracy and reliability with tendency depend on training samples by using the high-resolution images. Supervised classification was performed based on multi-spectral images which made by each satellite and aerial images for considering all of bands' characteristics. The highest accuracy was 84.7% with satellite image(3*3) and 83% with aerial image(5*5) at the accuracy verification phase. Also, the overall accuracy with the consideration of Kappa coefficient were 0.84 for satellite images and 0.82 for aerial images. In all of the images, the smaller training sample was, the higher accuracy showed. Therefore, tree species classification accuracy was tended to rely on training sample size.

• Journal of Korean Society for Geospatial Information Science
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• 제11권2호
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• pp.47-52
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• 2003

Change detection and analysis is a powerful application of remote sensing, in that the spectral resolution of multi-band sensors can be used to advantage in monitoring both significant and subtle land cover changes over time. In this study, the LANDSAT TM data was used to detect the change areas affected by flood from a heavy rainfall. The study area is the Nakdong River located in the Korea peninsular. Among the several change detection techniques, change vector analysis(CVA), principle component analysis(PCA) and image difference approach are utilized in this paper. CVA uses any number of spectral bands from multi-date satellite data to produce change image that yield information of the magnitude and direction of differences pixel values. And accuracy assessment was carried out with a change image produced from three techniques. In result, CVA was found to be the most accurate for detecting areas affected by flood. CVA with the overall accuracy and Kappa coefficient of 97.27 percent and 94.45 percent, respectively.

• Imaging Science in Dentistry
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• 제52권2호
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• pp.181-186
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• 2022

Purpose: This study aimed to investigate inter-observer reliability among observers with different levels of proficiency and the diagnostic imaging reliability of cone-beam computed tomography (CBCT) images of the retromolar canal. Materials and Methods: CBCT images of 307 patients were assessed for the presence of retromolar canals(RMCs) by 3 observers independently. Diagnoses were made twice by each observer at intervals of more than 3 weeks. Interobserver reliability was assessed using the kappa coefficient. One observer had no experience in diagnosis using CBCT images. Therefore, a specialist in diagnostic imaging explained the CBCT images for interpretation and practiced diagnostic imaging together with this observer, while the other observer interpreted the images independently. Thereafter, the observers re-evaluated the images. Results: The interobserver kappa coefficients (including bilateral RMCs) calculated at the first reading were low, ranging from 0.21 to 0.61. Their values ranged from 0.95 (right side) to 1.00 (left side) after one-on-one practice with a diagnostic imaging specialist, while the values ranged from 0.65 (right side) to 0.66 (left side) without one-on-one practice. Conclusion: Diagnostic accuracy was improved through diagnostic imaging practice. To improve the anatomical interpretation of images, it is important to practice diagnostic imaging with a specialist in diagnostic imaging. One-on-one instruction about diagnostic imaging was an effective method of training.

• Journal of the Korean Society of Earth Science Education
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• 제16권1호
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• pp.87-102
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• 2023

The purpose of this study is to propose an analytical framework for the essential contents that must be included in a climate change education program for elementary school students based on community issues, which can be used by citizen instructors in the community. To develop the analytical framework, 24 climate environmental education specialists were consulted seven times. The content validity of the final analysis framework was statistically verified using I-CVI and S-CVI coefficients, and the reliability of the expert panel was verified using Fleiss' Kappa coefficient. The final analysis framework consists of three analytical areas (program objectives, program content, program evaluation), seven analysis items, seven analysis indicators, and detailed explanations of the analysis indicators. In particular, by adding detailed explanations for the analysis indicators, the content validity and reliability were increased, and the objective nature of the analysis framework was firmly established. It is expected that the proposed analytical framework for a community-based climate change education program for elementary school students in this study will contribute to the systematic development of the program by citizen instructors.

• Journal of Preventive Medicine and Public Health
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• 제55권3호
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• pp.234-242
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• 2022

Objectives: This study assessed the validity and reliability of the Health-related Quality of Life Instrument with 8 Items (HINT-8) in patients with diabetes. HINT-8 is a newly-developed, generic health-related quality of life (HRQoL) instrument. Methods: Three HRQoL instruments-HINT-8, EuroQoL 5-Dimension 5-Level (EQ-5D-5L), and Short Form Health Survey version 2.0 (SF-36v2)-were provided to 300 patients with diabetes visiting a tertiary hospital for follow-up visits in Korea. The HRQoL scores obtained using the HINT-8 were evaluated for subgroups with known differences based on demographics and diabetes-related characteristics (known-group validity). The mean scores of the instruments were compared between groups segmented by their responses to the HINT-8 (discriminatory ability). Correlation coefficients of the HINT-8 with other instruments were calculated (convergent and divergent validity). The Cohen kappa and intra-class correlation coefficient (ICC) were also evaluated (test-retest reliability). Results: The average HINT-8 indexes were lower among women, older, and less-educated subjects. Subjects who did not list any problems on the HINT-8 had significantly higher HRQoL scores than those who did. The correlation coefficients of the HINT-8 with the EQ-5D-5L index and EuroQoL visual analogue scale were 0.715 (p<0.001) and 0.517 (p<0.001), respectively. The correlation coefficients between the HINT-8 index and the scores of 8 domains of the SF-36v2 ranged from 0.478 (p<0.001) to 0.669 (p<0.001). The Cohen kappa values for the HINT-8 ranged from 0.268 to 0.601, and the ICC of the HINT-8 index was 0.800 (95% confidence interval [CI], 0.720 to 0.860). Conclusions: This study showed that the HINT-8 is a valid and reliable HRQoL instrument for patients with diabetes.

• Journal of Sasang Constitutional Medicine
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• 제36권2호
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• pp.1-11
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• 2024

Objectives The purpose of this study was to compare between baseline and follow up data after 5 years about the change of Sasang constitutional value. Methods Cohort data of educational personnel in D University was used. Korean Sasang Constitutional Diagnostic Questionnaire was used to compare Sasang value including body shape, temperament, and pathological symptoms in baseline with those of follow up. Paired t test, chi-square test, correlation analysis and cohen's kappa coefficient was used. Results Total 150 subjects participated in this analysis. Taeeumin, Soeumin and Soyangin was 71, 46 and 33 respectively. Height decreased in follow-up, and weight increased, accordingly body mass index increased(p<.05). The score of nocturia was significantly increased, and the temperature of drinking water was significantly decreased. The consistency rate of the Sasang constitutional values in KS-15 between baseline and follow up was 76%, and the kappa value was 0.607. Compared to the expert's diagnosis, the agreement rate was 66.7% in baseline and 69.3% in follow up. Conclusion As times goes by, Sasang Constitutional phenotype, such as body mass index, nocturia, and temperature of drinking water, and accordingly, the predicted value of Sasang constitution may be changed. Those who use Sasang constitutional type and therapy in clinics should consider these factors.

• Journal of Gastric Cancer
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• 제5권4호
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• pp.228-237
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• 2005

Purpose: We investigated the impacts of the methylation states of the P16 and the hMLH1 genes on pathogenesis and genetic expression of stomach cancer and their relationships with Helicobater pylori infection, and with other clinico-pathologic factors. Material and Methods: In our study, to detect protein expression and methylation status of the P16 and the hMLH1 genes in 100 advanced gastric adenocarcinomas, used immunohistochemical staining and methylation-specific PCR (MSP) and direct automatic genetic sequencing analysis. Results: Methylation of the P16 gene was observed in 19 out of 100 cases (19%) and in the 18 of those cases (94.7%) loss of protein expression was seen. We were sble to show that loss of P16 gene expression was related to methylation of the P16 gene (kappa coefficient=0.317, p=0.0011). Methylation of the hMLH1 gene was observed in 27 cases (27%), and in 24 cases of those 27 cases (88.8%), loss of protein expression was seen, which suggested that loss of protein expression in the hMLH1 gene is related to methylation of hMLH1 gene (kappa coefficient=0.675, P<0.0001). Also methylation of the hMLH1 gene was related to age, size of the mass, and lauren's classification. Conclusion: We found that methylation of DNA plays an important role in inactivation of the P16 and the hMLH1 genes. The methylation of the hMLH1 genes is significantly related to age, size of the mass, and lauren's classification.

• Journal of health informatics and statistics
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• 제41권1호
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• pp.49-56
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• 2016

Objectives: Carotid intima-media thickness (CIMT) and the presence of carotid artery plaque are widely used as preclinical markers of atherosclerosis. Due to operator dependency in measuring CIMT, it is important to evaluate the reliability of measuring CIMT and plaque between centers in a multicenter study. The purpose of this study is to evaluate the inter-rater reliability of CIMT and plaque presence among three clinical centers of the Cardiovascular and Metabolic Disease Etiology Research Center (CMERC). Methods: Twenty people without known cardiovascular disease (age 37-64) were enrolled during 2014-2015, and their left and right carotid arteries were examined repeatedly with ultrasonography for CIMT measurements at three clinical centers according to a predetermined protocol. Maximum and mean values of CIMT at distal common carotid artery were recorded. Plaque presence at a carotid artery was checked by an operator. The reliability of CIMT and carotid plaque presence was assessed using an intraclass correlation coefficient (ICC) and kappa statistics, respectively. Results: Calculated ICC was 0.647 (95% CI: 0.487-0.779) for maximum CIMT, and 0.758 (95% CI: 0.632- 0.854) for mean CIMT. In Bland Altman plot, most observed values were distributed within mean difference ${\pm}1.96$ SD ranges. Kappa statistics of plaque presence between two centers were 0.304 (center 1 and 2), 0.507 (center 1 and 3), and 0.606 (center 2 and 3), respectively, while Fleiss kappa for overall agreement was 0.445. Conclusions: The inter-rater reliability of CIMT measurements among three clinical centers turned out to be high, and the agreement of measuring carotid plaque presence was fair.