• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2007년도 추계 학술대회논문집
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• pp.162-166
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• 2007

In the present study, the pressure coefficient of a cubic building model is numerically simulated. Three turbulence models of standard ${\kappa}-{\varepsilon}$, RNG ${\kappa}-{\varepsilon}$ and LES are adopted and the results are compared with the available experimental data. From the results, it has been found that RNG ${\kappa}-{\varepsilon}$ turbulence model and LES turbulence model were shown to predict fairly well the experimental pressure coefficient. In contrast, the results of the standard ${\kappa}-{\varepsilon}$ turbulence model showed large discrepancies in pressure coefficient on the side and top surfaces of the cubic building, which limits the applicability of the standard ${\kappa}-{\varepsilon}$ turbulence model on wind engineering.

• 한국전산유체공학회지
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• 제13권3호
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• pp.1-7
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• 2008

A supersonic base flow is computed to investigate the effect of the eddy viscosity coefficient to the linear ${\kappa}-{\varepsilon}$ turbulence models. Slight modifications to the eddy viscosity coefficient, which are based on the realizability condition, are given to the Launder-Sharma turbulence model so that present models satisfy the realizability condition. Numerical results for supersonic base flow show that turbulence models with the weaky-nonlinear eddy viscosity coefficient can lead to reasonable enhancements in the prediction of the velocity and turbulent kinetic energy profiles.

• 대한한의진단학회지
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• 제17권1호
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• pp.29-44
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• 2013

Objectives This study is aimed at assessing the reliability of the Pattern identification questionnaire (PIQ) developed by Korea Institute of Oriental Medicine and examining the validity of the PIQ by comparing the pattern identification scores of different groups. Methods We conducted a survey of 258 participants (79 teachers and 179 graduate students at one School of Korean Medicine) using self-reported questionnaire and all the samples were retested. The test-retest reliability was assessed by Kappa coefficient(${\kappa}$) and Pearson correlation coefficient. Also we compared the differences in pattern identification scores according to sex, age and occupation. Results 1. One of 116 questions are impossible to calculate; 22 of them (18.97%) scored under 0.4 in ${\kappa}$; 90(77.59%) ranged from 0.4 to 0.8 in ${\kappa}$; and three questions (3.58%) scored 0.8 or over in ${\kappa}$. 2. Pearson correlation coefficients between test score and retest score of all pattern identification items are 0.4 or over. 3. The mean score for pattern identification in women was generally higher than that in men, particularly in patterns of blood-deficiency, blood-stasis, yang-deficiency and kidney disease. 4. The mean score for pattern identification in the graduate student group was generally higher than that in the teacher group. Conclusion In test-retest reliability, the PIQ showed relatively high reliability. The mean pattern identification score showed differences in regards to retaining knowledge about Korean medicine. Therefore, future research involving modification of questionnaire items and confirming the validity of this questionnaire is required.

• 한방안이비인후피부과학회지
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• 제26권2호
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• pp.10-18
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• 2013

Objectives : We performed a pilot study to investigate inter- and intra-rater reliability of pattern identification using nasal endoscopy for allergic rhinitis(AR). Methods : Eight experts of ophthalmology, otolaryngology and dermatology of Korean medicine evaluated 20 nasal endoscopy photograph cases of AR patients with pattern identification index using nasal endoscopy for AR including the nasal membrane color(pale / hyperemia), nasal membrane humidity(dryness / dampness), rhinorrhea(watery / yellow), and membrane edema (atrophic / edematous) on nasal endoscopy. Results : Intra-rater agreement(%) and Kappa coefficient was generally from 'moderate' to 'good'(% agreement: 73.13-90% / Kappa coefficient: 0.547-0.748). Inter-rater agreement(%) and Kappa coefficient was also from 'moderate' to 'good' (% agreement: 65-85% / Kappa: 0.475-0.778) except 'humidity(dryness / dampness)' item (% agreement: 55.98% / Kappa: 0.340). In findings of subgroup analysis according to affiliation of raters, Inter-rater agreement(%) and Kappa coefficient of raters in same affiliation was higher than inter-rater agreement(%) and Kappa coefficient of raters in different affiliation except 'dryness / dampness' item. Conclusions : It is necessary to improve objectivity and reproducibility of pattern identification using nasal endoscopy for allergic rhinitis(AR) through the development of detail-oriented criteria and enhanced training of clinicians with development of standard operating procedures(SOPs).

• Journal of Preventive Medicine and Public Health
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• 제40권4호
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• pp.297-304
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• 2007

Objectives : We investigated the validity of the dipstick method (Mossman Associates Inc. USA) and the expired CO method to distinguish between smokers and non-smokers. We also elucidated the related factors of the two methods. Methods : This study included 244 smokers and 50 ex-smokers, recruited from smoking cessation clinics at 4 local public health centers, who had quit for over 4 weeks. We calculated the sensitivity, specificity and Kappa coefficient of each method for validity. We obtained ROC curve, predictive value and agreement to determine the cutoff of expired air CO method. Finally, we elucidated the related factors and compared their effect powers using the standardized regression coefficient. Results : The dipstick method showed a sensitivity of 92.6%, specificity of 96.0% and Kappa coefficient of 0.79. The best cutoff value to distinguish smokers was 5-6ppm. At 5 ppm, the expired CO method showed a sensitivity of 94.3%, specificity of 82.0% and Kappa coefficient of 0.73. And at 6 ppm, sensitivity, specificity and Kappa coefficient were 88.5%, 86.0% and 0.64, respectively. Therefore, the dipstick method had higher sensitivity and specificity than the expired CO method. The dipstick and expired CO methods were significantly increased with increasing smoking amount. With longer time since the last smoking, expired CO showed a rapid decrease after 4 hours, whereas the dipstick method showed relatively stable levels for more than 4 hours. Conclusions : The dipstick and expired CO methods were both good indicators for assessing smoking status. However, the former showed higher sensitivity and specificity and stable levels over longer hours after smoking, compared to the expired CO method.

• 지적과 국토정보
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• 제50권1호
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• pp.201-214
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• 2020

본 연구는 UAV 영상의 식생지수를 활용한 소나무재선충병 피해목 조기 탐지를 그 목적으로 하며, NDVI를 비롯한 대표적인 식생지수들을 선정하고 각각의 분류 정확도 비교분석을 통해 최적의 식생지수를 분석해보았다. 현장답사를 통하여 193개체의 소나무재선충병 피해목 위치데이터를 구축하고 동시에 다중분광 UAV 영상을 이용하여 4가지 식생지수 분석을 수행하였다. 무감독분류(K-Means)를 통하여 피해목을 분류하였고, 오차행렬(Confusion Matrix)를 이용하여 식생지수별 분류정확도를 비교·분석하였다. 연구의 결과를 요약하면 다음과 같다. 첫째 분류의 전체정확도는 NDVI (88.04%, Kappa계수 0.76) > GNDVI (86.01%, Kappa계수 0.72) > NDRE (77.35%, Kappa계수 0.55) > SAVI (76.84%, Kappa계수 0.54)순으로 분석되어 NDVI가 가장 높은 정확도를 보였으며, GNDVI가 거의 비슷한 수준의 분류정확도를 보였다. 둘째, NDVI 및 GNDVI 식생지수를 이용한 K-Means 무감독 분류방법으로 피해목의 판별이 어느 정도 가능한 것으로 판단된다. 특히 위 기법은 연산이 집약적이고 사용자의 개입이 적고 분석과정이 상대적으로 간단하여 피해목의 조기 탐지에 도움을 줄 수 있을 것으로 판단된다. 향후 시계열영상의 활용 또는 딥러닝기법의 추가 응용으로 분류정확도를 높일 수 있을 것으로 기대한다.

• 대한원격탐사학회지
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• 제40권2호
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• pp.179-190
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• 2024

This study aims to compare supervised classification methods with phenology-based approaches, specifically pixel-based and segment-based methods, for accurate crop mapping in agricultural landscapes. We utilized Sentinel-2A imagery, which provides multispectral data for accurate crop mapping. 31 normalized difference vegetation index (NDVI) images were calculated from the Sentinel-2A data. Next, we employed phenology-based approaches to extract valuable information from the NDVI time series. A set of 10 phenology metrics was extracted from the NDVI data. For the supervised classification, we employed the maximum likelihood (MaxLike) algorithm. For the phenology-based approaches, we implemented both pixel-based and segment-based methods. The results indicate that phenology-based approaches outperformed the MaxLike algorithm in regions with frequent rainfall and cloudy conditions. The segment-based phenology approach demonstrated the highest kappa coefficient of 0.85, indicating a high level of agreement with the ground truth data. The pixel-based phenology approach also achieved a commendable kappa coefficient of 0.81, indicating its effectiveness in accurately classifying the crop types. On the other hand, the supervised classification method (MaxLike) yielded a lower kappa coefficient of 0.74. Our study suggests that segment-based phenology mapping is a suitable approach for regions like South Korea, where continuous cloud-free satellite images are scarce. However, establishing precise classification thresholds remains challenging due to the lack of adequately sampled NDVI data. Despite this limitation, the phenology-based approach demonstrates its potential in crop classification, particularly in regions with varying weather patterns.

• 한방안이비인후피부과학회지
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• 제30권4호
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• pp.97-103
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• 2017

Objectives : To identify whether pattern identification using nasal endoscopy for rhinitis can be applied as a tool for evaluating rhinitis in routine care setting, we performed a inter-rater reliability study on this pattern identification. Methods : Two Korean medicine doctors assessed 290 left/right nasal endoscopy photograph cases of rhinitis patients with pattern identification using nasal endoscopy. This pattern identification consist of four assessment items, nasal membrane color(pale/hyperemia), nasal membrane humidity(dryness/dampness), rhinorrhea(watery/yellow), and turbinate membrane edema(atrophic/edematous). Cohen's kappa statistic and Percentage agreement were used to evaluate the inter-rater reliability. Results : Inter-rater percentage agreement and Kappa coefficient for left nasal endoscopy photograph cases was from 'slight' to 'moderate'(% agreement: 40.00-67.59%/Kappa: 0.06-0.407). Only the agreement of 'rhinorrhea (watery/yellow)' item was moderate(% agreement: 67.59%/Kappa: 0.407). Inter-rater percentage agreement and Kappa coefficient for right nasal endoscopy photograph cases was also from 'slight' to 'moderate'(% agreement: 42.41-68.97%/Kappa: 0.109-0.465). Only the agreement of 'rhinorrhea(watery/yellow)' item was moderate(% agreement: 68.97%/Kappa: 0.465). Conclusions : It is necessary to resolve problems such as cut-off value setting, bipolar evaluation values(pale/hyperemia, dryness/dampness, watery/yellow, atrophic/edematous) and weighting items. Further rigorous studies that overcome the limitations of the current research are warranted.

• 사상체질의학회지
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• 제11권1호
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• pp.159-168
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• 1999

Purpose : Sasang Constitutional Medicine explains the pathology peculiar to constitution and suggests treatment for each constitution. In Sasang Constitutional Medicine hwnan beings are classified on four groups; Taeyangin, Taeumin, 5oyangin, Soeumin. These four constitution has their's own symptoms and treatments. In treatment, control of mind inclination, that is to say, moderation takes a very important role. But the study on heredity in Sasang Constitutional Medicine has not done not biological study but also statistical study. So we used several statistical methods and analyzed 163 samples. Methods : We implemented Fishers exact test for adjusting chi-squared test, kappa coefficient to estimate agreement of parent's and children's constitutions, and finally plotted bi-plot using correspondence analysis. Results : From Fisher's exact test result, we could know that parent's and children'S constitution's distribution had significant difference. In kappa coefficient, mother and daughter's estimated value produced highest result. In correspondence analysis we only plotted the case of mother and son for easy interpretation. Conclusion : In the study of heredity of SaSang constitution, we cannot know exactly the heredity of constitution in terms of biology or genetics. But this research can be helpful for further analysis, that is, a study of biological or genetical aspects. And we could conclude that in statistical aspects the heredity in SaSang constitution is meaningful.

• 한국측량학회지
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• 제40권2호
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• pp.135-144
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• 2022

식생은 인간에게 다양한 생태공간을 제공하고 수자원 및 기후환경 측면에서도 매우 중요하기 때문에 근적외선 센서 기반의 식생지수를 활용한 식생 모니터링 연구가 많이 수행되어 왔다. 따라서 근적외선 센서를 구비하지 못할 경우 식생 모니터링 연구가 현실적으로 어려운 문제가 있었다. 본 연구에서는 이러한 문제를 개선하고자 NDVI 식생지수를 기준자료로 하여 광학센서 기반의 식생지수 정확도를 평가하였다. 먼저 현장에서 조사한 식생조사 지점과 NDVI 식생지수와의 중첩을 통해 Kappa 계수를 계산하였으며, 그 결과 Kappa 계수가 0.930으로 가장 높게 나타난 0.6 이상의 임계값을 갖는 식생영역을 광학센서 기반의 식생지수 정확도 평가의 기준자료로 선정할 수 있었다. NDVI 식생지수를 기준자료로 선정하여 광학센서 기반의 식생지수와 비교한 결과, 0.04, 0.08, 0.30 이상의 임계값 구간에서 Kappa 계수가 각각 0.713, 0.713, 0.828로 가장 높게 분석되었다. 특히 RGBVI 식생지수의 경우 Kappa 계수가 0.828로 높게 나타났으며, 따라서 근적외선 센서를 활용하지 못하는 환경에서도 광학센서를 활용한 식생 모니터링 연구가 가능함을 알 수 있었다.