• Title/Summary/Keyword: Difference-in-differences analysis

Search Result 4,333, Processing Time 0.034 seconds

Biological Hazard Analysis of Leaf Vegetables and Fruits According to Types of Cultivation and Distribution Systems (엽채류 및 과채류의 재배유형 및 유통경로별 생물학적 위해요소 조사)

  • Yu, Yong-Man;Youn, Young-Nam;Choi, In-Uk;Yuan, Xianglong;Lee, Young-Ha
    • Food Science and Preservation
    • /
    • v.14 no.1
    • /
    • pp.35-41
    • /
    • 2007
  • As the consumption of environmentally friendly agricultural products increases, food safety is at the forefront of public health concerns. We analyzed the biological hazards of 26 species of leaf vegetables and 4 species of fruit according to types of cultivation (conventional or organic filming) and distribution system (giant retailers or organic food stores) using various culture media, automatic bacterial identification systems, and microscopy, Total bacterial count of unwashed agricultural product ranged from $5.2{\times}10^{3}\;to\;1.5{\times}10^{5}\;CFU/mL$ (from 0.1 g of agricultural products), and the average count dropped 25-fold (range, 8-60-fold) after water washing. Microbial levels of washed organic agricultural products were $6.0{\times}10^{2}-1.9{\times}10^{4}\;CFU/mL$, and were not significantly different f개m the microbial loads on conventionally farmed produce. There was no significant difference in bacterial count from agricultural produce purchased from giant retailers or organic food stores. Total microbial count of Chinese cabbage, welsh onion, red chicory and kale were comparatively high, and Enterobacter cloacae was isolated most frequently. Parasites were detected in agricultural products purchased from conventional farm products in the stores of giant retailers, and in organic food stores, and parasite prevalence was especially high in Chinese cabbages and welsh onion. The study indicated that cultivation methods and distribution systems did not cause significant differences in biological contamination levels of agricultural produce. Some vegetables and fruits were highly contaminated effective sanitizing methods to reduce these biological hazards are needed.

An Analysis of the Psychiatric Characteristics of the Alopecia Areata in Female (여성 탈모증의 정신의학적 특성 분석)

  • Lee, Kil-Hong;Na, Chul;Lee, Young-Sik;Lee, Chang-Hoon;No, Byung-In;Hong, Chang-Kwon
    • Korean Journal of Psychosomatic Medicine
    • /
    • v.8 no.1
    • /
    • pp.31-45
    • /
    • 2000
  • Objectives : The present study was performed to reveal differences between female and male cases of alopecia in their alopecia related variables such as patterns of hair loss, psychiatric characteristics, associate illnesses, and methods of treatment, and to use them as basic materials for proper management and early prevention of the alopecia prone cases. Methods : In order to analysis the gender difference in hair losses, the subjects were divided into two subgroups as the 51 cases of female alopecia and the 42 cases of male alopecia, who had visited to the department of psychiatry consulted from the department of dermatology, Yongsan hopital, ChungAng University, Seoul, Korea, from January 1998 to December 1998. In data analysis, the subjects were statistically assesed by chi-squre test and analysis of varaiance, through SPSS-$PC^+$ 9.0V. Results : 1) Female subjects were more likely showed lower socio-economical level including lower eonomical level, lower educational level, or lower occupational level in their parent's job, were more likely to have larger number of siblings and to have many sisters comparison to the male cases. 2) Female subjects were more likely visited to the department of dermatology, more history of alopecia in their female family members, lesser history of alopecia in their male family members, more loss of hairs in vertex or frontal region of scalp, lesser loss of hairs in occipital region, and lesser nail changes in comparison to the male cases. 3) Female subjects were more suffered from intra-familial conflicts and economical changes, or their introverted personality makeup, lesser likely suffered from changes of business and health changes, and showed lesser conflicts related with poorer adaptaion in their job life. 4) Female subjects were more likely diagnosed as depression or conversion disorders, more frequently complaint anxiety symptoms or depressive symptoms, higher level of anxiety index, lesser complaint somatization or obsessive compulsive symptoms, and lesser diagnosed as anxiety disorder in comparison to the male cases. 5) Female subjects were more likely tended to show personality makeup such as the introverted, the lie, the repressed, or the feminine trends than the male cases. 6) Female subjects were more significantly treated by antianxiety drug such as etizolam and dermatological therapies include tretinoin, and lesser treated by clotiazepam and prednicarbonate in comparison to the male cases. Conclusion : From the facts that The most important factors in developing hair loss in the female subjects in comparison to the male cases seems to be closely correlated with the serious psychopathology such as the presence of mental disorders including depression, the presence of complaining anxiety or depressive symptomatology, the presence of stressful life events such as intrafamilial life changes, and the presence of personality makeup such as the introverted, the lie, the repressed, or the feminine trends, the authors confirmed that dermatologists act as the primary care physician are in a unique position to recognize psychiatric comorbidity and execute meaningful intervention for female patients with the alopecia with psychiatrists.

  • PDF

Effect of Vegetation Types on the Distribution of Soil Invertebrates (식생유형이 토양무척추동물 분포에 미치는 영향)

  • Kim, Myung-Hyun;Bang, Hea-Son;Han, Min-Su;Hong, Hey-Kyoung;Na, Young-Eun;Kang, Kee-Kyung;Lee, Jeong-Taek;Lee, Deog-Bae
    • Korean Journal of Environmental Agriculture
    • /
    • v.28 no.2
    • /
    • pp.125-130
    • /
    • 2009
  • The aim of this study was to investigate whether differences in the distribution of soil invertebrates among different vegetation types (forest, reservoir, and crop land types) in rural area. A total of 18 orders and 137 species were collected by pitfall traps. Species numbers were the lowest (33 species) at the Chamaecyparis obtusa plantation (St. 6). On the forest sites, the individual number of Hymenoptera was the most abundant, and Acari and Coleoptera was the relatively more abundant than the other sites. On the reservoir sites (Salix chaenomeloides community), the individual number of Collembola was the most abundant, and Diptera was the relatively more abundant than the other sites. On the crop land sites, the individual numbers of Collembola, Hymenoptera, and Araneae were the relatively more abundant than the other orders. The density of Araneae was higher in the reservoir and crop land sites than in the forest sites. From a point of view of biodiversity, although the diversity index(H') was the highest in the mixed broad-leaved forest type (St. 2) with Quercus serrata and Q. acutissima, and the lowest in the upland levee of crop land(St. 11), there was no significant difference among the habitat or vegetation types. According to the community analysis, the soil invertebrates could be divided into 4 groups, the mixed broad-leaved forest type (A group), the plantation or pure forest type (B group), the reservoir type (C group), and the crop land type (D group).

Quality Characteristics of Jocheong Containing Various Level of Letinus edodes Extracts (표고버섯 추출액을 이용한 조청의 품질특성)

  • Park, Jung-Suk;Na, Hwan-Sik
    • Journal of the Korean Society of Food Science and Nutrition
    • /
    • v.34 no.7
    • /
    • pp.1082-1090
    • /
    • 2005
  • Jocheong was prepared by adding Lentinus edodes extract to improve its quality and to give some functional properties. Contents of crude protein, ash and crude lipid were similar to those of control, while carbohydrate content was decreased. Total mineral content were $1,916.03\~2,674.24mg/kg$ that was no difference between test samples. From HPLC determination of free sugars, Jocheong was found to contain maltose as the highest sugar, followed by glucose and fructose. In amino acid analysis, seventeen amino acid were identified and quantified. Glutamic acid in Jocheong was major amino acid. The major fatty acids in Jocheong $(0\%,\;control)$ were linoleic acid, palmitic acid, oleic acid, myristic acid and caproic acid. There was no significant differences in fatty acid composition, pH and reducing sugar content among the Jocheong samples. The viscosity and solid contents tended to decrease with the addition of Lentinus edodes extract. Increasing the ratio of mushroom extract in Jocheong tended to decrease the lightness, yellowness and redness in Hunter's color value. Although sensory value decreased with increasing Lentinus edodes extracts, use of mushroom extracts (7: 3; saccharification liquids: Lentinus edodes extracts) is recommended for making Jocheong.

Expansive Application of the POCoM (Practical On-site Cooperation Model) for Practical Improvement of Science Teaching (과학수업의 실제적 개선을 위한 POCoM (Practical On-site Cooperation Model)의 확장 적용)

  • Park, Jongwon;Kim, Youngmin;Jeong, Jin-Su;Park, Young-Shin;Park, Jongseok
    • Journal of Science Education
    • /
    • v.41 no.3
    • /
    • pp.365-381
    • /
    • 2017
  • Based on the previous study (Park et al., 2015) which indicated positive results in the improvement of science teaching through the POCoM (Practical On-site Cooperation Model) application, this work concentrates on expanding the POCoM to more various teaching settings. To do this, 18 cyclic applications (72 teaching classes in total) of the POCoM were divided into (1) the first cycles and the second cycles conducted after the first cycles, (2) classroom teaching and laboratory teaching, and (3) cycles by our research team and cycles by other experts team. The comparison between the two parts were conducted using the improvement rates, the number of KTOP (Korean Teaching Observation Protocol) items which improvement was needed, and the change of these numbers according to teaching sequence. As results, no difference regarding the improvement was observed between classroom and laboratory teachings, and also between the first and the second cycles. When other experts team applied the POCoM, the number of KTOP items which improvement was needed was larger and the improvement rate was lower than those in the cycle by our research team. Nevertheless, these differences were not statistically significant, and also, it was expected that, if other experts team tries to improve science teaching through 6 teachings, the improvement by the other experts would be nearly the same with the improvement by our research team through 4 teachings. In conclusion, it is confirmed that the POCoM can be used in various teaching settings with the almost the same potency. Lastly, the necessity and possibility of the more detailed and qualitative analysis about the POCoM application are discussed.

Assessment of Clinical Applicability of a New Plaque Scoring System Using Quantitative Light-Induced Fluorescence-Digital (Quantitative Light-Induced Fluorescence-Digital을 이용한 치면세균막 검사법의 임상적 활용 가능성 평가)

  • Hwang, Hye-Rim;Cho, Young-Sik;Kim, Baek-Il
    • Journal of dental hygiene science
    • /
    • v.14 no.2
    • /
    • pp.150-157
    • /
    • 2014
  • The aim of this study was to suggest a convenient method of monitoring the gingival state through plaque detection. Quantitative Light-Induced Fluorescence-Digital (QLF-D), which can assess mature plaque, can be used to assess the oral hygiene status of individuals and to establish an adequate intervention plans for them. The subjects of the study participated in the clinical training at Department of Dental Hygiene, N University. The subjects completed questionnaires on general characteristics and oral hygiene methods. Then, photographs of maxillary and mandibular anterior teeth of the subjects were taken using the QLF-D. After the oral examinations, gingival state was recorded according to the $L{\ddot{o}}e$ & Silness's Gingival Index (GI). In addition, a plaque control record was calculated in percentage using disclosing agent. The analysis of the relation between the plaque control record and the QLF-D scores showed positive correlation (r=0.638, p<0.001), and the analysis of the relation between the QLF-D scores and the gingival bleeding index scores also showed positive correlation (r=0.562, p<0.001). Besides, the study classified the participants into healthy gingiva group and the gingivitis group according to the classification criteria of GI, and when the difference of QLF-D scores between the groups was analyzed, the QLF-D scores were statistically significantly higher (t=-2.785, p=0.007) in the gingivitis group ($1.71{\pm}1.545$) than the healthy gingiva group ($0.74{\pm}1.290$). When the differences in mean values of the QLF-D scores were analyzed against and the gingival bleeding index scores, the QLF-D scores of 0 and 1 belonged to the category of normal gingival state while the QLF-D scores of 2, 3 and 4 belonged to the category of gingivitis state. Therefore, it is deemed that the red fluorescence detected by the QLF-D from the mature supragingival plaque can be used for monitoring the state of gingivitis.

Biomass, Net Production and Biomass Estimation Equations in Some Natural Quercus Forests (주요 참나무류 천연림(天然林)의 물질생산(物質生産) 및 현존량추정식(現存量推定式)에 관(關)한 연구(硏究))

  • Park, In Hyeop;Moon, Gwang Sun
    • Journal of Korean Society of Forest Science
    • /
    • v.83 no.2
    • /
    • pp.246-253
    • /
    • 1994
  • Four Quercus forests in Mt. Mohu were studied to investigate biomass, net production and effective biomass estimation method. Five $10m{\times}10m$ quadrats were set up, ten sample trees were cut and roots of three sample trees were excavated for dimension analysis in each forest. There was little difference in accuracy among three allometric biomass regression models of logWt=A+BlogD, $logWt=A+BlogD^2H$ and logWt=A+BlogD+ClogH, where Wt, D and H were dry weight, DBH and height, respectively. Analysis of covariance showed that there were no significant differences among slopes and intercepts of allometric biomass regressions, logWt=A+BlogD, of four Quercus species. Biomass of Q. acutissima, Q. nariabilis, Q. serrata and Q. mongolica forests were 164.0, 158.9, 115.3 and 118.9t/ha, respectively. Net production of Q. acutissima, Q. variabilis. Q. serrata and Q. mongolica forests were 25.0, 23.2, 14.5 and 12.6t/ha/yr., respectively. The proportion of roots to total biomass and total net production of Q. mongolica forest was higher than that of three other species forests. Net assimilation ratio of Q. acutissima, Q. variabilis, Q. serrata and Q. mongolica forests were 2.87, 2.80, 3.20 and 2.95, respectively. Relatively less leaf biomass of Q. serrata and Q. mongolica forests were the reason why total biomass and total net production of Q. serrata and Q. mongolica forests were less than those of Q. acutissima and Q. variabilis.

  • PDF

A Study on Applicable Level of Entrepreneurship: Focus on Entrepreneurial Orientation (기업가정신의 적용수준과 기업성과에 관한 연구 -기업가지향성을 중심으로-)

  • Han, Eun-Soo;Jeong, Beom-Goo;Lee, Sang-Bin;Sung, Eul-Hyun
    • Management & Information Systems Review
    • /
    • v.36 no.2
    • /
    • pp.157-185
    • /
    • 2017
  • This study was carried out with the attention that the concept of entrepreneurial orientation has been applied at various levels of CEO, employee, management, and organization as a whole. The differences between these concepts were examined by discriminant validity and convergence validity, and the causal relationship between these concepts and performance was analyzed. A total of 96 questionnaires were collected and analyzed. The results show that CEO's entrepreneurial orientation, employee's entrepreneurial orientation, manager's entrepreneurial orientation and organizational entrepreneurial orientation have convergent validity and discriminant validity, and that these variables have different effects on the firm 's innovation performance and financial performance. In the analysis of the mediating effect, when the variables of all levels were put into a single variable, the innovation performance mediates between the entrepreneurial orientation and the financial performance in all variables. However, when all variables are applied simultaneously, innovation performance has mediating effect only on the relationship between organizational entrepreneurship orientation and financial performance. This shows that there is a conceptual difference according to applied level. As a result of the analysis of the causal relationship by the application level of entrepreneurial orientation, it is found that causality is formed among the entrepreneurial orientation variables. In particular, CEO's entrepreneurial orientation influences employee's entrepreneurial orientation, manager's entrepreneurial orientation, and organization's entrepreneurial orientation, and again, employee's entrepreneurial orientation and managerial entrepreneurial orientation form a causal relationship that influences organization's entrepreneurial orientation. In the relationship between innovation performance and financial performance, CEO's entrepreneurial orientation, organization's entrepreneurial orientation, and manager's entrepreneurial orientation are influencing innovation performance, and the only variables influencing financial performance are organization's entrepreneurial orientation. In conclusion, the limitations of the study and its future direction are presented.

  • PDF

Comparison of Image Quality among Different Computed Tomography Algorithms for Metal Artifact Reduction (금속 인공물 감소를 위한 CT 알고리즘 적용에 따른 영상 화질 비교)

  • Gui-Chul Lee;Young-Joon Park;Joo-Wan Hong
    • Journal of the Korean Society of Radiology
    • /
    • v.17 no.4
    • /
    • pp.541-549
    • /
    • 2023
  • The aim of this study wasto conduct a quantitative analysis of CT image quality according to an algorithm designed to reduce metal artifacts induced by metal components. Ten baseline images were obtained with the standard filtered back-projection algorithm using spectral detector-based CT and CT ACR 464 phantom, and ten images were also obtained on the identical phantom with the standard filtered back-projection algorithm after inducing metal artifacts. After applying the to raw data from images with metal artifacts, ten additional images for each were obtained by applying the virtual monoenergetic algorithm. Regions of interest were set for polyethylene, bone, acrylic, air, and water located in the CT ACR 464 phantom module 1 to conduct compare the Hounsfield units for each algorithm. The algorithms were individually analyzed using root mean square error, mean absolute error, signal-to-noise ratio, peak signal-to-noise ratio, and structural similarity index to assess the overall image quality. When the Hounsfield units of each algorithm were compared, a significant difference was found between the images with different algorithms (p < .05), and large changes were observed in images using the virtual monoenergetic algorithm in all regions of interest except acrylic. Image quality analysis indices revealed that images with the metal artifact reduction algorithm had the highest resolution, but the structural similarity index was highest for images with the metal artifact reduction algorithm followed by an additional virtual monoenergetic algorithm. In terms of CT images, the metal artifact reduction algorithm was shown to be more effective than the monoenergetic algorithm at reducing metal artifacts, but to obtain quality CT images, it will be important to ascertain the advantages and differences in image qualities of the algorithms, and to apply them effectively.

Utility of the 16-cm Axial Volume Scan Technique for Coronary Artery Calcium Scoring on Non-Enhanced Chest CT: A Prospective Pilot Study (비 조영증강 흉부 CT에서 관상동맥 칼슘스코어 측정을 위한 16 cm 축상 촬영 기법의 유용성: 전향적 탐색적 연구)

  • So Jung Ki;Chul Hwan Park;Kyunghwa Han;Jae Min Shin;Ji Young Kim;Tae Hoon Kim
    • Journal of the Korean Society of Radiology
    • /
    • v.82 no.6
    • /
    • pp.1493-1504
    • /
    • 2021
  • Purpose This study aimed to evaluate the utility of the 16-cm axial volume scan technique for calculating the coronary artery calcium score (CACS) using non-enhanced chest CT. Materials and Methods This study prospectively enrolled 20 participants who underwent both, non-enhanced chest CT (16-cm-coverage axial volume scan technique) and calcium-score CT, with the same parameters, differing only in slice thickness (in non-enhanced chest CT = 0.625, 1.25, 2.5 mm; in calcium score CT = 2.5 mm). The CACS was calculated using the conventional Agatston method. The difference between the CACS obtained from the two CT scans was compared, and the degree of agreement for the clinical significance of the CACS was confirmed through sectional analysis. Each calcified lesion was classified by location and size, and a one-to-one comparison of non-contrast-enhanced chest CT and calcium score CT was performed. Results The correlation coefficients of the CACS obtained from the two CT scans for slice thickness of 2.5, 1.25, and 0.625 mm were 0.9850, 0.9688, and 0.9834, respectively. The mean differences between the CACS were -21.4% at 0.625 mm, -39.4% at 1.25 mm, and -76.2% at 2.5 mm slice thicknesses. Sectional analysis revealed that 16 (80%), 16 (80%), and 13 (65%) patients showed agreement for the degree of coronary artery disease at each slice interval, respectively. Inter-reader agreement was high for each slice interval. The 0.625 mm CT showed the highest sensitivity for detecting calcified lesions. Conclusion The values in the non-contrast-enhanced chest CT, using the 16-cm axial volume scan technique, were similar to those obtained using the CACS in the calcium score CT, at 0.625 mm slice thickness without electrocardiogram gating. This can ultimately help predict cardiovascular risk without additional radiation exposure.