• Title/Summary/Keyword: sample heterogeneity

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A Study on the Seamline Estimation for Mosaicking of KOMPSAT-3 Images (KOMPSAT-3 영상 모자이킹을 위한 경계선 추정 방법에 대한 연구)

  • Kim, Hyun-ho;Jung, Jaehun;Lee, Donghan;Seo, Doochun
    • Korean Journal of Remote Sensing
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    • v.36 no.6_2
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    • pp.1537-1549
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    • 2020
  • The ground sample distance of KOMPSAT-3 is 0.7 m for panchromatic band, 2.8 m for multi-spectral band, and the swath width of KOMPSAT-3 is 16 km. Therefore, an image of an area wider than the swath width (16 km) cannot be acquired with a single scanning. Thus, after scanning multiple areas in units of swath width, the acquired images should be made into one image. At this time, the necessary algorithm is called image mosaicking or image stitching, and is used for cartography. Mosaic algorithm generally consists of the following 4 steps: (1) Feature extraction and matching, (2) Radiometric balancing, (3) Seamline estimation, and (4) Image blending. In this paper, we have studied an effective seamline estimation method for satellite images. As a result, we can estimate the seamline more accurately than the existing method, and the heterogeneity of the mosaiced images was minimized.

The Influence of Trade and Foreign Direct Investment on Green Total Factor Productivity: Evidence from China and Korea

  • Li, Kan-Yong;Gong, Wen-Chao;Choi, Beak-Ryul
    • Journal of Korea Trade
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    • v.25 no.2
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    • pp.95-110
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    • 2021
  • Purpose - This paper intends to conduct theoretical analysis and empirical test on the action mechanism of South Korea-China trade and South Korea's FDI to China on green total factor productivity, so as to provide a new perspective and ideas for the improvement of China's green total factor productivity and promote the high-quality development of China's economy Design/methodology - This paper uses the data of 30 provinces, autonomous regions and municipalities in China from 2004 to 2017 as the research sample, adopts the GML index method of SBM Directional Distance Function to measure GTFP, and analyzes the influence of South Korea-China trade and FDI from South Korea on China's GTFP. Findings - Trade is conducive to promoting technological progress, which has a significant promotion effect on China's green total factor productivity. While FDI has a significant inhibitory effect on China's green total factor productivity, which verifies the "pollution haven" hypothesis. In addition, such influence has certain regional overall heterogeneity. Trade has a more significant promoting effect on GTFP in eastern coastal areas, while FDI has a more significant inhibitory effect on GTFP in central and western inland areas. The interaction between trade and FDI is conducive to the improvement of green total factor productivity, indicating that the benign mechanism of trade and FDI has been formed. Urbanization, industrial structure, human resource level and investment in science and technology are all conducive to the improvement of GTFP. Originality/value - Through theoretical analysis and empirical test on the action mechanism of South Korea-China trade and South Korea's FDI on green total factor productivity, this paper provides a solid theoretical foundation for the further development of China-South Korea economic and trade cooperation in the future.

The Impact of Chinese SMEs' Financial Structure on Innovation Efficiency (중국 중소기업 재무구조가 혁신 효율성에 미치는 영향)

  • Wang, Yiqi;Sim, Jae-Yeon
    • Industry Promotion Research
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    • v.7 no.4
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    • pp.97-108
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    • 2022
  • This paper examined the impact of financing structure on the innovation efficiency of SMEs by constructing an econometric model using panel data of SMEs listed on the SME board from 2010 to 2020 as the research sample. The innovation efficiency of SMEs was measured by the Stochastic Frontier Analysis (SFA), the relationship between financing structure and innovation efficiency of SMEs was examined with the help of the Tobit model, and the corresponding heterogeneity analysis was conducted. Finally, the robustness of the model was tested. It was concluded that the effects of debt and equity financing on the quantitative efficiency of innovation were non-linear and mainly showed an inverted "U" shaped relationship. For innovation quality efficiency, bond financing could positively contribute, while equity financing negatively inhibits. Finally, the corresponding advice was given.

Effects of Electrical Stimulation on Patients with Non-Specific Low Back Pain : A Meta-Analysis of Domestic Database (비특이적 만성 허리통증 환자에 대한 전기자극의 효과 : 국내 데이터베이스의 메타분석)

  • Lee, Jeong-Woo;Cho, Sung-Hyoun
    • Journal of The Korean Society of Integrative Medicine
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    • v.10 no.3
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    • pp.37-52
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    • 2022
  • Purpose : The purpose of this meta-analysis was to evaluate the effects of electrical stimulation on patients with non-specific low back pain. Methods : Domestic databases were gathered from studies that conducted clinical trials associated with electrical stimulation and its impact on pain of non-specific low back patients. A total of 681 studies were identified, with 12 studies satisfying the inclusion data. The studies consisted of patient, intervention, comparison, outcome, and study design (PICO-SD). The search outcomes were items associated with low back pain. Cochrane risk of bias 2 (RoB 2) was used to evaluate the quality of 12 randomized controlled trials. Effect sizes (Hedges's g) in this study were computed as the corrected standard mean difference (SMD). A random-effect model was used to analyze the effect size because of the high heterogeneity among the studies. Egger's regression and 'trim-and-fill' tests were carried out to analyze the publication bias. Cumulative meta-analysis and sensitivity analysis were conducted to analyze the effect according to the sample size and the consistency of the effect size. Results : The following factors had a large overall effect size (Hedges's g=1.28, 95 % CI=.20~2.36) involving electrical stimulation on non-specific low back pain. The subgroup analysis all showed a statistical difference in the types of study design, electrical stimulation, and assessment tool. No statistically significant difference was found in the meta-regression analysis. Publican bias was found in the data. Conclusion : The findings in this study indicate that electrical stimulation interventions have a positive effect on patients with non-specific low back pain. However, due to the low quality of studies and publication bias, the results of our study should be interpreted cautiously.

Effectiveness of Acupuncture and Acupotomy for Trigger Finger: A Systematic Review and Meta-Analysis

  • Hae-Won Hong;Myung-In Jeong;Hyun-Il Jo;Sun-Ho Lee;Ka-Hyun Kim;Sung-Won Choi;Jae-Won Park;Ji-Su Ha
    • Journal of Acupuncture Research
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    • v.40 no.2
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    • pp.111-128
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    • 2023
  • Trigger finger is a common cause of hand disability that results in finger catching, clicking, or locking. Conventional treatment options such as medication, injection, and surgery have limitations. Studies have indicated that acupuncture and acupotomy can be effective in treating trigger finger. However, no review regarding these treatment modalities has been published yet. This review included randomized controlled trials published until January 2023, investigating acupuncture-related interventions. The primary outcomes of interest included the effectiveness rate (ER) and pain intensity, measured using a visual analog scale (VAS) and Numerical Rating Scale (NRS), and secondary outcomes were the Quinnell grade (QG) and recurrence rate (RR). Adverse events (AEs) have also been reported wherever available. Overall, 19 studies were included, and results demonstrated that arcedge acupuncture improved the ER and QG and reduced NRS, and acupuncture was effective in reducing VAS. Compared with conventional surgery, acupotomy alone improved the ER and QG and lowered VAS and RR, with relatively fewer AEs. Acupotomy add-on treatment was more effective than conventional treatment; however, careful interpretation is needed for VAS. Acupotomy add-on treatment was more effective than acupotomy alone. However, the overall results must be interpreted with caution because of study quality, small sample size, and heterogeneity of the results.

Grain Growth Behavior of Heat Treated Mg-0.6wt.%Zn-0.6wt.%Ca Alloy Sheet Manufactured via Twin Roll Casting and Hot Rolling (트윈롤 주조 후 열간압연된 Mg-0.6wt.%Zn-0.6wt.%Ca 합금 판재의 열처리에 따른 결정립 성장 거동)

  • Lee, Hee Jae;Park, No Jin
    • Journal of the Korean Society for Heat Treatment
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    • v.35 no.2
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    • pp.74-81
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    • 2022
  • This study aims to mitigate the microstructural heterogeneity arising from the manufacture of magnesium alloy plates using the twin roll casting (TRC) process. Homogenization was introduced through hot rolling and heat treatment, followed by confirmation of observed changes in the microstructure. Following the TRC process, the hot rolled 2mm plate exhibited a dendritic cast structure tilted in the roll rotation direction, while central segregation were developed. This nonuniform structure and central segregation disappeared upon heat treatment, followed by recrystallization to form uniform and fine grains. Abnormal grain growth (AGG) was observed over the course of heat treatment; grains exhibiting AGG occupied up to 75% of the total area after having held the sample at 400℃ for 64 h. The formation of coarse grains was also observed during heat treatment at 340℃ over a relatively long duration, though the maximum grain size was significantly smaller than that corresponding to the heat treatment at 400℃. AGG in the 400℃ heat treatment occurred because of movement of the grain boundary, which had been fixed prior as a result of the grain boundary fixing effect of the precipitation phase. The re-dissolution of the Ca2Mg5Zn5 precipitated phase over the long duration of the high-temperature annealing process caused the surrounding grains to disappear and regrow.

Reference values for pulp oxygen saturation as a diagnostic tool in endodontics: a systematic review and meta-analysis

  • Paula Lambert;Sergio Augusto Quevedo Miguens Jr;Caroline Solda;Juliana Tomaz Sganzerla;Leandro Azambuja Reichert;Carlos Estrela;Fernando Branco Barletta
    • Restorative Dentistry and Endodontics
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    • v.45 no.4
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    • pp.48.1-48.11
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    • 2020
  • Objectives: This systematic review aimed to identify mean oxygen saturation values (SpO2) using pulse oximetry in permanent maxillary anterior teeth. Materials and Methods: The MEDLINE, Scientific Electronic Library Online, Cochrane Central Register of Controlled Trials, EMBASE, and Literatura Latino Americana em Ciências da Saúde electronic databases were searched. Combinations and variations of "oximetry" AND "dental pulp test" were used as search terms. Studies reporting means and standard deviations of SpO2 values were included. Two reviewers independently extracted data following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses checklist. Heterogeneity was assessed using the I2 statistic, and all analyses were performed using R software. Study quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies-2 tool and the Newcastle-Ottawa scale. Results: Of the 251 studies identified, 19 met the eligibility criteria and were included (total sample, 4,541 teeth). In the meta-analysis, the mean SpO2 values were 84.94% (95% confidence interval [CI], 84.85%-85.04%) for the central incisors, 89.29% (95% CI, 89.22%-89.35%) for the lateral incisors, and 89.20% (95% CI, 89.05%-89.34%) for the canines. The studies were predominantly low-quality due to the high risk of bias associated with the index test, unclear risk regarding patient selection, and concerns about outcome assessment. Conclusions: Although most studies were low-quality, the oxygen saturation levels in normal pulp could be established (minimum saturation, 77.52%). Despite the risk of bias of the included studies, the reference values reported herein are clinically relevant for assessments of changes in pulp status.

Wage Differentials between Standard and Non-standard Workers (정규-비정규근로자 임금격차)

  • Kim, Yong-Min;Park, Ki Seong
    • Journal of Labour Economics
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    • v.29 no.3
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    • pp.25-48
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    • 2006
  • In this study, the wage differentials between standard and non-standard workers are estimated using the data from the Establishment Employment Survey of 2003. The estimated wage differentials between standard and non-standard workers become greater controlling for the fixed effects of establishments. The within-establishment wage differential is estimated to be 20.7% between male standard and male non-standard workers in unorganized establishments controlling for establishment heterogeneity. However, the estimated overall wage differential is reduced to 6.8% due to the high wages of non-standard workers in large size establishments and the low wages of standard workers in small size establishments. This difference between 20.7% and 6.8% reflects the between-establishment wage differential. In organized establishments, the wage differential becomes larger, 21.8%, between male standard and male non-standard workers. For the male workers, the greatest wage differential between standard and non-standard workers is found in unorganized large size establishments: it is 35.9%. In organized establishments, it contracts to 25.8%. The additional estimations on the probability of becoming non-standard workers are done. For the male sample, the probability of standard workers to become non-standard workers in unorganized establishments is 6.0 percentage points higher than that in small size organized establishments. The probability is 20.7 percentage points higher for the female sample. However, the signs of the interaction terms of union and large size establishments are all negative. While the effect of large size establishments reduces the effect of union on the probability to 7.3 percentage points for the males, it reduces the probability to 16.0 percentage points for the females.

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Analysis of Relationship between Housing Tenure and Birth in Newlywed Couples by Using Panel Data (패널자료를 이용한 신혼가구의 주택점유형태와 출산 관계 연구)

  • Shin, Hyungsub
    • Land and Housing Review
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    • v.13 no.3
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    • pp.39-55
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    • 2022
  • In this study, we investigate the interrelationship between housing tenure and childbirth by exploiting the correlation probability effect method that accounts for household heterogeneity. Using the newlywed household panel from 2011 to 2022, we find that home ownership has a positive impact on childbirth in newlyweds. Specifically, newlywed households with housing tenure show a 6.2%p higher birth rate and a 5.7%p higher second childbirth than newlywed households living in rented houses. For the case of first childbirth, we employ the probability effect probit model since the endogeneity was not detected between housing tenure and birth rate. We document the differential effects of housing tenure on childbirth in that the first childbirth rate is higher for households without housing tenures. The negative effects on first childbirth could be attributed to the economic burden due to initial housing ownership, while housing tenure could eventually provide housing stability, leading to positive effects on more than one childbirth. Finally, we identify that households with childbirth over the last year show a 4.2%p and 3.9%p lower probabilities of housing tenure in the total sample and second childbirth sample, respectively. This suggests that the increased living cost due to childbirth could delay home ownership.

Women's Knowledge, Attitudes, and Practices about Breast Cancer in a Rural District of Central India

  • Gangane, Nitin;Ng, Nawi;Sebastian, Miguel San
    • Asian Pacific Journal of Cancer Prevention
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    • v.16 no.16
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    • pp.6863-6870
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    • 2015
  • Background: Breast cancer accounted for almost 25% of all cancers in women globally in 2012. Although breast cancer is the most prevalent cancer in India, there is no organised national breast cancer screening programme. Local studies on the burden of breast cancer are essential to develop effective context-specific strategies for an early detection breast cancer programme, considering the cultural and ethnic heterogeneity in India. This study examined the knowledge, attitudes, and practices about breast cancer in rural women in Central India. Materials and Methods: This community-based cross sectional study was conducted in Wardha district, located in Maharashtra state in Central India in 2013. The sample included 1000 women (609 rural, 391 urban) aged 13-50 years, selected as representative from each of the eight development blocks in the district, using stratified cluster sampling. Trained social workers interviewed women and collected demographic and socio-economic data. The instrument also assessed respondents' knowledge about breast cancer and its symptoms, risks, methods of screening, diagnosis and treatment, as well as their attitudes towards breast cancer and selfreported practices of breast cancer screening. Chi-square and t-test were applied to assess differences in the levels of knowledge, attitude, and practice (the outcome variables) between urban and rural respondents. Multivariable linear regression was conducted to analyse the relationship between socio-demographic factors and the outcome variables. Results: While about two-thirds of rural and urban women were aware of breast cancer, less than 7% in rural and urban areas had heard about breast self-examination. Knowledge about breast cancer, its symptoms, risk factors, diagnostic modalities, and treatment was similarly poor in both rural and urban women. Urban women demonstrated more positive attitudes towards breast cancer screening practices than their rural counterparts. Better knowledge of breast cancer symptoms, risk factors, diagnosis, and treatment correlated significantly with older age, higher levels of education, and being office workers or in business. Conclusions: Women in rural Central India have poor knowledge about breast cancer, its symptoms and risk factors. Breast self-examination is hardly practiced, though the willingness to learn is high. Positive attitudes towards screening provide an opportunity to promote breast self-examination.