• Safety and Health at Work
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• 제2권2호
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• pp.169-175
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• 2011

Objectives: The questionnaire of occupational stress index (OSI) has been popular in the workplace, and it has been tailored for bus drivers in Taiwan. Nevertheless, its outcomes for participants are based on self-evaluations, thus validation by their physiological stress biomarker is warranted and this is the main goal of this study. Methods: A cross-sectional study of sixty-three city bus drivers and fifty-four supporting staffs for comparison was conducted. Questionnaire surveys, 24-hour urine cortisol testing, and blood draws for dehydroepiandrosterone-sulfate (DHEA-S) testing were performed. The measured concentrations of these biological measures were logarithmically transformed before the statistical analysis where various scores of stressor factors, moderators, and stress effects of each OSI domain were analyzed by applying multiple linear regression models. Results: For drivers, the elevated 24-hour urine cortisol level was associated with a worker's relationship with their supervisor and any life change events in the most recent 3 months. The DHEA-S level was higher in drivers of younger age as well as drivers with more concerns relating to their salary and bonuses. Non-drivers showed no association between any stressor or satisfaction and urine cortisol and blood DHEA-S levels. Conclusion: Measurements of biomarkers may offer additional stress evaluations with OSI questionnaires for bus drivers. Increased DHEA-S and cortisol levels may result from stressors like income security. Prevention efforts towards occupational stress and life events and health promotional efforts for aged driver were important anti-stress remedies.

• 대한원격탐사학회지
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• 제15권2호
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• pp.107-117
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• 1999

본 연구에서는 원격탐사를 이용하여 수질 파라미터들을 평가하는데 기존의 다중 회귀나 밴드비 회귀 분석을 이용한 통계적인 방법과 신경망을 이용한 방법을 비교하였다. 사용된 영상은 1996년 3월 18일 대청호 유역의 Landsat TM 영상이며, 30개의 현장 실측치가 위성이 통과하는 시간대에 샘플링되었다. 적용된 신경망은 3개의 층으로 구성된 전향 신경망이며 훈련방법으로는 역전파를 사용하였다. 본 연구에서는 가용한 훈련 데이터 셀이 작으므로 cross-validation 방법이 적용되었다. 비록 기존의 회귀분석에 의한 결과도 어느 정도 유의하게 나왔지만, 신경망에 의한 결과가 훨씬 성공적인 수행을 보여주었다. 신경망을 이용한 수질평가는 신경망이 자료의 비선형적 속성을 잘 반영해주기 때문에 기존의 통계적 기법보다 훨씬 나은 결과를 제공한다고 판단된다.

• Journal of Preventive Medicine and Public Health
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• 제52권6호
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• pp.366-376
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• 2019

Objectives: The relationships among discrimination, social support, and mental health have mostly been studied in minorities, and relevant studies in the general population are lacking. We aimed to investigate associations between discrimination and depressive symptoms in Korean non-minority young adults, considering the role of social support. Methods: In total, 372 participants who completed the psychological examinations conducted in the third wave of the Jangseong High School Cohort study were included. We used the Everyday Discrimination Scale to evaluate perceived discrimination and the Beck Depression Inventory-II to measure depressive symptoms. Social support was measured by the Multidimensional Scale of Perceived Social Support. Multivariate linear regression was conducted to investigate associations between discrimination and depression, along with the effect modification of social support. We stratified the population by gender to investigate gender differences. Results: Perceived discrimination was significantly associated with depressive symptoms (${\beta}=0.736$, p<0.001), and social support was negatively associated with depression (${\beta}=-0.245$, p<0.001). In men, support from friends was the most influential factor (${\beta}=-0.631$, p=0.011), but no significant effect modification was found. In women, support from family was the most influential factor (${\beta}=-0.440$, p=0.010), and women with higher familial support showed a significantly diminished association between discrimination and depression, unlike those with lower family support. Conclusions: Discrimination perceived by individuals can lead to depressive symptoms in Korean young adults, and this relationship can may differ by gender and social support status.

• Tuberculosis and Respiratory Diseases
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• 제84권3호
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• pp.182-187
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• 2021

Background: Fractional exhaled nitric oxide (FeNO) is a non-invasive marker for eosinophilic airway inflammation and a good predictor of response to corticosteroids. There is a need for a reliable and accurate measurement method, as FeNO measurements have been widely used in clinical practice. Our study aimed to compare two FeNO analyzers and derive a conversion equation for FeNO measurements in adults. Methods: We included 99 participants who had chief complaints of chronic cough and difficulty in breathing. The participants underwent concurrent FeNO measurement using NIOX VERO (Circassia AB) and NObreath (Bedfont). We compared the values of the two devices and analyzed their correlation and agreement. We then formulated an equation to convert FeNO values measured by NObreath into those obtained by NIOX VERO. Results: The mean age of the participants was 51.2±17.1 years, with a female predominance (58.6%). Approximately 60% of the participants had asthma. The FeNO level measured by NIOX VERO (median, 27; interquartile range [IQR], 15-45) was significantly lower than that measured by NObreath (median, 38; IQR, 22-58; p<0.001). There was a strong positive correlation between the two devices (r=0.779, p<0.001). Additionally, Bland-Altman plots and intraclass correlation coefficient demonstrated a good agreement. Using linear regression, we derived the following conversion equation: natural log (Ln) (NObreath)=0.728×Ln (NIOX VERO)+1.244. Conclusion: The FeNO values of NIOX VERO and NObreath were in good agreement and had positive correlations. Our proposed conversion equation could help assess the accuracy of the two analyzers.

• 한국산학기술학회논문지
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• 제20권6호
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• pp.548-556
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• 2019

본 연구의 목적은 식생활라이프스타일과 인구통계적 특성이 외식영양표시 외식업체의 브랜드이미지에 미치는 영향을 분석하여 외식업체의 차별화된 브랜드 이미지 전략을 수립을 위한 마케팅의 기초자료를 제공하는데 있다. 연구분석을 위해 SPSS 21.0 (ver.) 프로그램, 빈도분석 및 기술통계, 요인분석 및 신뢰도분석, 상관관계 분석, 다중선형회귀분석 등을 실시하여 가설을 검증하였다. 그 결과 거주지에서 수도권은 안전추구, 비수도권은 맛추구, 안전추구, 성별에서 남성은 건강추구, 맛추구, 안전추구, 여성은 안전추구일수록 외식영양표시 외식업체에 대한 브랜드이미지가 상승하였다. 연령에서 20대는 맛추구, 30대와 40대는 안전추구, 결혼여부에서 기혼과 미혼 모두 안전추구일수록 외식영양표시 외식업체에 대한 브랜드이미지가 상승하는 것으로 분석되었다. 즉, 식생활라이프스타일이 안전추구, 건강추구일 경우 주거지, 연령, 성별, 결혼여부, 자녀유무와 관계없이 외식영양표시 외식업체에 긍정적인 브랜드이미지를 갖고 있다는 것을 알 수 있었다.

• 상하수도학회지
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• 제35권3호
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• pp.237-246
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• 2021

The ILI, developed by the IWA (International Water Association), has been used in many countries as an indicator of water leakage. In Korea, the revenue water has been used as a performance indicator for waterworks although there is an opinion to replace it with the ILI. Hence, it has been necessary to investigate whether the ILI can replace the revenue water in Korea. The four main operating indicators (i.e., water service population, profit-loss ratio, fiscal self-reliance, and aged pipe rate) of 162 Korean waterworks were compared with the ILI with the linear regression method. Local water authorities with more than 1 million water service population, with more than 60% profit-loss ratio, more than 40% and less than 60% fiscal self-reliance, and more than 20% aged pipe rate showed meaningful correlation between the four parameters and the ILI. In the remaining cases, their correlations were little or weak. This means that using the ILI may not be an efficient method to represent the performance of the water supply system in Korea because of the lack of UARL (Unavoidable Annual Real Losses) data accuracy. To use the ILI in Korea, it will be required to carry out an additional research to accumulate reliable CARL (Current Annual Real Losses) and UARL data in the future.

• Geomechanics and Engineering
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• 제24권6호
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• pp.519-529
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• 2021

In coal mining activities, the abutment stress of the coal has to undergo cyclic loading and unloading, affecting the strength and seepage characteristics of coal; additionally, it can cause dynamic disasters, posing a major challenge for the safety of coal mine production. To improve the understanding of the dynamic disaster mechanism of gas outburst and rock burst coupling, triaxial devices are applied to axial pressure cyclic loading-unloading tests under different axial stress peaks and different pore pressures. The existing empirical formula is use to perform a non-linear regression fitting on the relationship between stress and permeability, and the damage rate of permeability is introduced to analyze the change in permeability. The results show that the permeability curve obtained had "memory", and the peak stress was lower than the conventional loading path. The permeability curve and the volume strain curve show a clear symmetrical relationship, being the former in the form of a negative power function. Owing to the influence of irreversible deformation, the permeability difference and the damage of permeability mainly occur in the initial stage of loading-unloading, and both decrease as the number of cycles of loading-unloading increase. At the end of the first cycle and the second cycle, the permeability decreased in the range of 5.777 - 8.421 % and 4.311-8.713 %, respectively. The permeability decreases with an increase in the axial stress peak, and the damage rate shows the opposite trend. Under the same conditions, the permeability of methane is always lower than that of helium, and it shows a V-shape change trend with increasing methane pressures, and the permeability of the specimen was 3 MPa > 1 MPa > 2 MPa.

• 한국경제지리학회지
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• 제25권1호
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• pp.183-201
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• 2022

주택가격을 정확히 추정하기 위한 많은 연구가 진행되어 왔다. 선행연구들은 주택의 고유 특성과 인근 지역 특성을 통제하는 계량경제모형을 활용한 분석이 많았다. 본 연구에서는 인공신경망 모형(ANN)을 활용하여 주택가격을 추정하였다. 딥러닝 기술의 장점은 변수 간의 복잡하고 비선형적인 특성을 모델링하고 데이터의 패턴을 인식할 수 있다는 것이다. 본 연구에서는 부동산 시장에서 공간적 분포도 패턴으로 인식할 수 있다는 가정하에 지리좌표를 설명변수로 ANN에 투입하였다. 선형회귀분석과 ANN 모형 간 비교 결과, 선형 모형 대비 ANN 모형의 설명력이 높았으며, 특히 ANN 모형은 지리좌표를 투입하였을 때 더 높은 정확도를 보여주었다. 또한 ANN 모형의 경우 지리좌표를 통해 모형 잔차의 공간적 자기 상관성이 크게 감소하였다는 점을 확인하였다. 이를 통해 ANN 모형의 패턴인식 능력을 활용하면 공간적 패턴을 학습시킴으로써 주택가격을 정확히 추정할 수 있음을 밝혔다.

• 인간식물환경학회지
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• 제24권6호
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• pp.629-638
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• 2021

Background and objective: This study was conducted to develop diameter growth models for thinned Quercus glauca Thunb. (QGT) stands to inform production goals for treatment and provide the information necessary for the systematic management of this stands. Methods: This study was conducted on QGT stands, of which initial thinning was completed in 2013 to develop a treatment system. To analyze the tree growth and trait response for each thinning treatment, forestry surveys were conducted in 2014 and 2021, and a one-way analysis of variance (ANOVA) was executed. In addition, non-linear least squares regression of the PROC NLIN procedure was used to develop an optimal diameter growth model. Results: Based on growth and trait analyses, the height and height-to-diameter (H/D) ratio were not different according to treatment plot (p > .05). For the diameter of basal height (DBH), the heavy thinning (HT) treatment plot was significantly larger than the control plot (p < .05). As a result of the development of diameter growth models by treatment plot, the mean squared error (MSE) of the Gompertz polymorphic equation (control: 2.2381, light thinning: 0.8478, and heavy thinning: 0.8679) was the lowest in all treatment plots, and the Shapiro-Wilk statistic was found to follow a normal distribution (p > .95), so it was selected as an equation fit for the diameter growth model. Conclusion: The findings of this study provide basic data for the systematic management of Quercus glauca Thunb. stands. It is necessary to construct permanent sample plots (PSP) that consider stand status, location conditions, and climatic environments.

• Archives of Pharmacal Research
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• 제18권6호
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• pp.415-422
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• 1995

Twenty-four flavones were synthesized with various hydroxyl and/or methoxyl groups on A and B rings. Their antimutagenic properties were evaluated against ben:w(a)pyrene (BaP) and a pool of mutagenic urine concentrate (U) using a modified liquid incubation method of Ames test. The tester strain was Salmonella typhimurium TA98+S9 Mix. The antimutagenic activities were calculated by non linear regression analysis and the doses of flavones (in nmoles) required for a 50% reduction of induced revertants with BaP and U were defined as the inhibition doses (TEX>$ID_{508}{\;}and{\;}ID_{508}$ respectively). Seventeen flavones possessed significant antimutagenic activity against BaP. $ID_{508}$ ranged from 15.1 nmoles (F22) to 1000.6 nmoles (F13). Eighteen f1avones showed significant antimutagenic activity against U. $ID_{50U}$ ranged from 23.5 nmoles (F22) to 354.6 nmoles (F3). The 2',3',4'-trihydroxyflavone (F22, $ID_{508}=15.1$ nmoles, $ID_{50U}=23.5$ nmoles) and the 2',3',4',7-tetrahydroxyflavone (F20, $ID_{508}=37.8$ nmoles; $ID_{50U}=62.3$ nmoles) had antimutagenic activities similar to those of chlorophyllin ($ID_{508}=19.6$ nmoles and $ID_{50U}=44.2$ nmoles) and were evaluated against B(alP 7,8-dihydrodiol-9,10-epoxide. Against this last mutagen, the flavones which included three OH in B ring showed the highest activity and this property seemed independent of the substituent groups on A ring.