• Title/Summary/Keyword: Difference-in-Differences(DID)

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Analysis of Image Distortion on Magnetic Resonance Diffusion Weighted Imaging

  • Cho, Ah Rang;Lee, Hae Kag;Yoo, Heung Joon;Park, Cheol-Soo
    • Journal of Magnetics
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    • v.20 no.4
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    • pp.381-386
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    • 2015
  • The purpose of this study is to improve diagnostic efficiency of clinical study by setting up guidelines for more precise examination with a comparative analysis of signal intensity and image distortion depending on the location of X axial of object when performing magnetic resonance diffusion weighted imaging (MR DWI) examination. We arranged the self-produced phantom with a 45 mm of interval from the core of 44 regent bottles that have a 16 mm of external diameter and 55 mm of height, and were placed in 4 rows and 11 columns in an acrylic box. We also filled up water and margarine to portrait the fat. We used 3T Skyra and 18 Channel Body array coil. We also obtained the coronal image with the direction of RL (right to left) by using scan slice thinkness 3 mm, slice gap: 0mm, field of view (FOV): $450{\times}450mm^2$, repetition time (TR): 5000 ms, echo time (TE): 73/118 ms, Matrix: $126{\times}126$, slice number: 15, scan time: 9 min 45sec, number of excitations (NEX): 3, phase encoding as a diffusion-weighted imaging parameter. In order to scan, we set b-value to $0s/mm^2$, $400s/mm^2$, and $1,400s/mm^2$, and obtained T2 fat saturation image. Then we did a comparative analysis on the differences between image distortion and signal intensity depending on the location of X axial based on iso-center of patient's table. We used "Image J" as a comparative analysis programme, and used SPSS v18.0 as a statistic programme. There was not much difference between image distortion and signal intensity on fat and water from T2 fat saturation image. But, the average value depends on the location of X axial was statistically significant (p < 0.05). From DWI image, when b-value was 0 and 400, there was no significant difference up to $2^{nd}$ columns right to left from the core of patient's table, however, there was a decline in signal intensity and image distortion from the $3^{rd}$ columns and they started to decrease rapidly at the $4^{th}$ columns. When b-value was 1,400, there was not much difference between the $1^{st}$ row right to left from the core of patient's table, however, image distortion started to appear from the $2^{nd}$ columns with no change in signal intensity, the signal was getting decreased from the $3^{rd}$ columns, and both signal intensity and image distortion started to get decreased rapidly. At this moment, the reagent bottles from outside out of 11 reagent bottles were not verified from the image, and only 9 reagent bottles were verified. However, it was not possible to verify anything from the $5^{th}$ columns. But, the average value depends on the location of X axial was statistically significant. On T2 FS image, there was a significant decline in image distortion and signal intensity over 180mm from the core of patient's table. On diffusion-weighted image, there was a significant decline in image distortion and signal intensity over 90 mm, and they became unverifiable over 180 mm. Therefore, we should make an image that has a diagnostic value from examinations that are hard to locate patient's position.

IN VITRO MARGINAL FIT OF THE COMPUTERAIDED MILLED CERCON CROWNS

  • Chang, Jae-Yoon;Yang, Jae-Ho;Han, Jung-Suk;Lee, Jai-Bong
    • The Journal of Korean Academy of Prosthodontics
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    • v.43 no.3
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    • pp.306-313
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    • 2005
  • Statement of problem. There have been many studies about marginal discrepancy of single restorations made by various systems and materials. But most of statistical inferences are not definite because of sample size, measurement number, measuring , instruments, etc. And there have been few studies about the marginal fit of Computer-aided Cercon crowns. Purpose. The purpose of this study was to compare the marginal fit of the anterior single restorations made using computer-aided milled Cercon crowns with metal-ceramic restorations and to obtain more accurate information by using a large enough sample size and by making sufficient measurements per specimen. Material and methods. The in vitro marginal discrepancies of computer-aided milled Cercon crowns and control groups (metal ceramic crowns) were evaluated and compared. The crowns were made from one extracted maxillary central incisor prepared by milling machine. 30 crowns per each system were fabricated. Measurements of a crown were recorded at 50 points that were randomly selected for marginal gap evaluation. Parametric statistical analysis was performed for the results. Results. The means and standard deviations of the marginal fit were 85$\pm$22$\mu$m for the control group and 91$\pm$15$\mu$m for the Cercon crowns. The t-test of the marginal discrepancies between Cercon crowns and metal-ceramic crowns were performed. Significant differences were not found between groups (P=0.230>.05). Based on the criterion of 120$\mu$m as the limit of clinical acceptability, the mean marginal fits of Cercon crowns and metal-ceramic crowns were acceptable. Conclusion. Within the limitations of this in vitro study, the following conclusions were drawn: 1. Mean gap dimensions and standard deviations at the marginal opening for maxillary incisal crowns were 85$\pm$22$\mu$m for the control (metal-ceramic crowns), 91$\pm$15$\mu$m for Cercon crowns. 2. The Cercon crowns showed slightly larger marginal gap discrepancy than the control but marginal gap between Computer-aided milled Cercon crowns and metal ceramic crowns did not showed significant difference (P>.05). 3. The Cercon crowns and metal ceramic crowns showed clinically acceptable marginal discrepancy.

Influence of Abnormally Low Temperatures on Growth, Yield, and Biologically Active Compounds of Strawberry (이상 저온조건이 딸기의 생육, 수량 및 생리활성 성분에 미치는 영향)

  • Lee, Gyu-Bin;Choe, Yun-Ui;Park, Eun-Ji;Wang, Ziyu;Li, Mei;Li, Ke;Park, Young-Hoon;Choi, Young-Whan;Kang, Nam-Jun;Kang, Jum-Soon
    • Journal of Environmental Science International
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    • v.26 no.3
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    • pp.381-392
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    • 2017
  • The present study aimed to investigate the effects of low temperature on the growth, yield, quality, and biologically active compounds of strawberry and obtain basic information for developing a technology for stable growth of strawberry in greenhouses. Growth of strawberry, including leaf number, area, and length, plant height, and dry weight was better at the optimum growth temperature of $20^{\circ}C$ than at a lower temperature of $15^{\circ}C$. At the low temperature of $15^{\circ}C$, the cultivar 'Maehyang' was more tolerant and displayed better growth rate than 'Seolhyang'. At $15^{\circ}C$, the fruit production per week and fruit weight was lower than that at $20^{\circ}C$. In contrast, fruit length and diameter were not significantly different between the two growth temperatures. Growth temperature also did not affect the fruit color index, Hunter L, a, b value, or fruit firmness. However, the sugar content of strawberries grown at $15^{\circ}C$ was higher by 0.8 and 1.5 Brix for 'Seolhyang' and 'Maehyang', respectively, than of those grown at $20^{\circ}C$. There was no difference in the content of fisetin, a biologically active compound, for 'Seolhyang' at both growth temperatures, however, the fisetin content of 'Maehyang' was higher at $20^{\circ}C$ than at $15^{\circ}C$. Cinchonine and ellagic acid content of 'Seolhyang' was higher at $20^{\circ}C$ than at $15^{\circ}C$, whereas that of 'Maehyang' was higher at $15^{\circ}C$ than at $20^{\circ}C$. Quercetin content showed no significant differences with respect to growth temperature, however, it tended to increase at $20^{\circ}C$. The cinnamic acid content of 'Seolhyang' was higher at $15^{\circ}C$ than at $20^{\circ}C$, whereas that of 'Maehyang' increased at $20^{\circ}C$. Collectively, the biologically active compounds of strawberry were affected by growth temperature. Moreover, the content of these compounds tended to increase at $20^{\circ}C$, the optimum growth temperature, rather than at the sub-optimal growth temperature of $15^{\circ}C$.

Comparison and Validation Study on Computational Fluid Dynamics and Wind Tunnel Test Results of Standard Dynamics Model (표준 동안정 모델의 전산유체해석 및 풍동시험 결과 비교검증)

  • Cho, Donghyurn;Kim, Seung Pil;An, Eunhye;Choi, Younseok;Roh, Jisoo;Chung, Hyoung Seog
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.45 no.3
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    • pp.217-225
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    • 2017
  • This research represents comparison and validation of static aerodynamic results in different wind tunnel organizations and EFD-CFD results. KAFA conducted wind tunnel tests with Standard Dynamics Model(SDM) which is based on the NRC model, the same configuration of KARI; and then compared and analyzed similarities and differences of the data from KARI and NRC results for verifying the accuracy of wind tunnel tests. Also, We compared the result of CFD with that of wind tunnel tests and examined strakes effect in static characteristics which are attached on the forward fuselage of SDM for investigating the cause of some discrepancies. From this analysis, there are some discrepancies in Cm tendency between EFD-CFD and it did not show the big difference of aerodynamic characteristics by strake effects. Thus, we need to research additionally for analyzing the different cause of some discrepancies such as vortex structures by the rear strut or intake of SDM and regenerating grid resolution of CFD.

Clinical characteristics and outcomes among pediatric patients hospitalized with pandemic influenza A/H1N1 2009 infection

  • Lee, Eun;Seo, Ju-Hee;Kim, Hyung-Young;Na, Shin;Kim, Sung-Han;Kwon, Ji-Won;Kim, Byoung-Ju;Hong, Soo-Jong
    • Clinical and Experimental Pediatrics
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    • v.54 no.8
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    • pp.329-334
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    • 2011
  • Purpose: The purpose of this article is to describe the clinical and epidemiologic features and outcomes among children hospitalized with pandemic influenza A/H1N1 2009 infection. Methods: We retrospectively reviewed the charts of hospitalized pediatric patients (<18 years) diagnosed with pandemic influenza A/H1N1 2009 infection by reverse-transcriptase polymerase chain reaction at a tertiary hospital in Seoul, Korea, between September 2009 and February 2010. Results: A total of 72 children were hospitalized with pandemic influenza A/H1N1 2009 infection (median age, 6.0 years; range, 2 months to 18 years). A total of 40% had at least 1 underlying medical condition, including asthma (17%), malignancies (19%), and heart diseases (17%). Of the 72 patients, 54 (76%) children admitted with H1N1 infection showed radiographic alterations compatible with pneumonia. There was no significant difference in pre-existing conditions between pandemic influenza A/H1N1 infected patients with or without pneumonia. Children with pandemic influenza A/H1N1 pneumonia were more likely to have a lower lymphocyte ratio (P=0.02), higher platelet count (P=0.02), and higher level of serum glucose (P=0.003), and more commonly presented with dyspnea than did those without pneumonia (P=0.04). Conclusions: No significant differences in age, sex, or presence of preexisting conditions were found between children hospitalized with pandemic influenza A/H1N1 H1N1 influenza infection with pneumonia and those without pneumonia. Higher leukocyte count, higher glucose level, and a lower lymphocyte ratio were associated with the development of pandemic A/H1N1 2009 influenza pneumonia.

Alterations of Human Autonomic Nervous System Activity on Capsaicin Ingestion, and Variants of UCP1 and β3- -adrenergic Receptor Polymorphism (캡사이신 섭취와 UCP1 과 β3- adrenergic Receptor Polymorphism의 다양성에 대한 자율신경활동의 변화)

  • Ko, Ki-Jun;Shin, Ki-Ok
    • Journal of Life Science
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    • v.17 no.8 s.88
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    • pp.1075-1081
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    • 2007
  • We investigated whether 1) capsaicin ingestion (100 mg) enhances autonomic nervous system (ANS) activities associated with thermogenic sympathetic activity as energy metabolic modulator, 2) UCP1 and ${\beta}_{3}$-AR variants of each subjects influence with ANS activity. Eight healthy males (24.7 ${\pm}$ 1.8 yr) volunteered for this study. The cardiac autonomic nervous activities evaluated by means of heart rate variability of power spectral analysis and energy metabolism were continuously measured during 5-min rest for total 90-min resting condition with placebo or capsaicin oral administration chosen at random. The results indicated that there were no significant differences in heart rate during rest between both trials. Autonomic nervous activity increased in capsaicin tablet trial, but the difference did not reach the statistical significance. Capsaicin, however, induced significantly lower respiratory gas exchange ratio at Test3 (CAP: 0.80 ${\pm}$ 0.02 vs. 0.85 ${\pm}$ 0.02), means ${\pm}$ SE, p<0.05). In conclusion, it may be suggested the capsaicin consumption as a valuable supplement for the treatment of individual with hyperlipidemia and/or obesity by improving lipolysis. Further studies will also be considered genetic variants such as UCP1 and/or ${\beta}_{3}$-AR associated with obesity.

The Effect of Newly Synthesized Compounds on the Photosynthetic Electron Transport of Cyanobacteria (Anacystis nidulans $R_2$) (신규(新規) 합성화합물들이 cyanobacteria의 광합성전자전달계에 미치는 영향)

  • Hwang, I.T.;Kim, J.S.;Cho, K.Y.;Yoneyama, K.;Yoshida, S.
    • Korean Journal of Weed Science
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    • v.13 no.2
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    • pp.89-95
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    • 1993
  • The Inhibiting activity of newly synthesized phenol (E-series) and triazine (T-series) derivatives was evaluated by using thylakoid membranes extracted from cyanobacteria (Anacystis nidulans $R_2$). There were no significant differences between phenol derivatives and dinoseb to the thylakoid membrane extracted from wild type in the Hill reaction. However, a phenol derivative, E-24 which has no -Cl at phenyl ring, did not show any activity. The longer the length of R substituents was in phenol derivatives, the lower inhibiting activity was in the Hill reaction. Triazine derivatives, T-27, T-28, T-40, T-41, T-47 and T-48 were also compared with diuron and atrazine. Among triazine compounds, T-27 and T-28 showed 10 and 30 times activity as high as atrazine to wild type, respectively. Other triazine derivatives, T-40, T-41, T-47 and T-48 showed low inhibiting activity to wild and mutant type. A structural difference of T-27 and T-28 from T-40, T-41, T-47 and T-48 was the presented of -C-NH-. Both T-27 and T-28 were very closely associated with serine, an amino acid located at the 264th position of D1 protein because of the resistant ratio(R/S) to mutant G-264 were higher than that of atrazine.

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Development of Mathematical CAI program Model And Its Application (수학과 CAI프로그램 모형 개발과 적용)

  • 강희태;권연근
    • Education of Primary School Mathematics
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    • v.2 no.1
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    • pp.53-64
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    • 1998
  • Two different CAI programs have been developed to study the affect of CAI element for the types of learners'performance; (i) one is the 'CAI program 1' including the open questions for the fourth grade (the fourth period of the 'Time and Angle' in chapter 3 of the first term) of the mathematics class in the elementary school, and (il) the other is 'CAI program 2' for the existing methods. The fourth grade of Andong Songhyun elementary school has been chosen as the study subjects (243 learners), and the t-test and learners'interview have also been used to analysis the results of CAI programs. The CAI programs have only been used as the control variable. The developed CAI programs have been applied two different learners'groups to investigate the degree of performance among the superior, average, and inferior learners. For the superior group (p<.0023) at the t<3.2268 level and for the average group (p<.0706) at the t<1.8211 level the learner' group using CAI program 1 shows the higher performance compared with the learners' group using the CAI program 2, whereas fur the inferior group (p<.8073) at the t<.2458 level two programs did not show any difference. The learners interviews show that the superior and average groups have an interest for the open problems, whereas the inferior group do not shows an interest for the open problems. Thus, the CAI programs including the open questions (open fields, open evaluation) will be helped to the learners' group with the individual differences. Furthermore, it is expected that the CAI programs including the open questions as the mathematics and the program model of CAI can be used to develope the CAI program in future.

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Body fat distribution and hypertension (신체의 지방분포양상과 고혈압)

  • Lee, Choong-Won;Yoon, Nung-Ki
    • Journal of Preventive Medicine and Public Health
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    • v.24 no.1 s.33
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    • pp.57-69
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    • 1991
  • This study examined the cross-sectional association of central body fat distribution with hypertension as well as the superiority of medial calf skinfold measured as peripheral fat distribution over the conventional triceps skinfold using 450 Korean Navy divers selected by authors' convenience in 1990. Their mean age was 27.9 and range of it was 19-51. The centrally located body fat was approximated by subscapular skinfold and peripherally located fat by triceps and medial calf skinfolds. Four indices were constructed from these skinfold measures to reflect central versus peripheral fat distribution pattern : 2 ratios and 2 differences. After controlling age and overall obesity (body mass index), prevalance odds ratios of the 2/4, 3/4, 4/4 quartiles of subscapular skinfold comparing with lowest 1/4 quartile were 2.05(95% confidence interval, CI 1.18-3.59), 2.02(95% CI 1.06-3.86), 4.00 (95% CI 1.99-8.06) respectively. The difference of subscapular and medial calf skinfolds was associated with hypertension (odds ratio 2.45, 95% CI 1.28-4.68 comparing highest with lowest quartiles). Triceps and medial calf skinfolds alone did not show any odds ratio not including unity. The adjusted odds ratios were generally reduced in small magnitude compared with crude odds ratios not adjusted for age and overall obesity. The medial calf skinfold appeared to be more representative of peripheral body fat distribution than triceps skinfold. These findings suggest that central fat distribution rather than peripheral distribution is associated with hypertension independent of age and overall level of obesity and medial calf skinfold may replace conventional triceps skinfold in predicting peripheral distribution of body fat.

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Effect of interproximal undercut on the dimensional accuracy of impression (치간 유두 소실로 인한 언더컷이 인상체의 체적 정확도에 미치는 영향)

  • Lee, Ju-Ri;Kim, Seok-Gyu
    • The Journal of Korean Academy of Prosthodontics
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    • v.53 no.4
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    • pp.330-336
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    • 2015
  • Purpose: This study evaluated the effect of loss of interproximal papilla, creating an undercut, on the accuracy of impression materials. Materials and methods: Two addition type silicone impression materials ($Extrude^{(R)}$ Speed Wash, $Imprint^{TM}$ II Quick Step Light Body) and one alginate impression material (Cavex Impressional) were used to make impressions of a maxillary master model simulating clinical conditions with or without interproximal papilla. Stone was poured in the impressions and working casts were fabricated. A total of 6 groups with 6 working casts in each group were scanned using 3-dimensional optical scanner. The accuracy of the impressions was assessed by measuring the dimensional changes (${\Delta}I$ (%)) of 6 distances on working casts compared to a master model with a 3-dimensional digitizing and inspection software. The data were analyzed by two-way ANOVA (P<.05). Results: Three of 6 distances showed statistically significant differences among the impression materials. Only 1 of 6 distances in alginate impression showed a statistically significant difference between casts with and without interproximal papilla (P=.047). Conclusion: The presence of undercut due to loss of interproximal papilla did not significantly influence the dimensional accuracy of addition type silicone and alginate impression materials.