• Title/Summary/Keyword: Difference in difference(DID)

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Studies on Factors affecting on Reproductive traits of the Pig Farms managed by EDP System (전산관리 양돈농가의 번식성적에 미치는 요인에 관한 연구)

  • Kim, H.S.;Kim, B.W.;Kim, H.C.;Lee, K.W.;Ha, J.K.;Jeon, J.T.;Lee, J.G.
    • Journal of Animal Science and Technology
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    • v.45 no.6
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    • pp.917-922
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    • 2003
  • This study was conducted to investigate effects of farm, type of sow Landrace${\times}$Yorkshire, LY; Yorkshire${\times}$ Landrace, YL; Yorkshire${\times}$Yorkshire, YY and multi-cross bred sow, MBS), parity, farrowing year, farrowing season and mating method on reproductive traits such as total number born per litter, number of born alive per litter, number of weaned per litter, number of mummified per litter, number of stillbirth. The Reproductive Records of 3,387 litters from January, 1999 to September, 2002 were obtained from four pig farms managed by Electronic Data Processing(EDP) system. Reproductive performances for two types of F1 Sows(YL and LY) were estimated as 11.34${\pm}$0.266 and 11.57${\pm}$0.263 heads for total number of born per litter, 10.56${\pm}$0.216 and 11.81${\pm}$0.251 heads for number of born alive per litter, and 10.05${\pm}$0.131 and 9.96${\pm}$0.153 heads for number of weaned per litter, respectively. These records are significantly higher(P〈0.05) than those of YY and MBS. However, number of mummified per litter, number of stillborn per litter, number of dead by diarrhea per litter, number of dead by other reasons during lactating period per litter and estrus interval did not show significant difference between types of sows. There were more total number of born per litter and number of weaned per litter in year 2001 than other year. As year passed, number of dead by crush per litter, number of dead by diarrhea per litter and number of dead by other reasons during lactating period per litter reduced from 0.18${\pm}$0.023 to 0.07${\pm}$0.022 head, 0.12${\pm}$0.21 to 0.02${\pm}$0.020 head and 0.43${\pm}$0.041 to 0.22${\pm}$0.040 head, respectively and weaning rate increased from 0.94${\pm}$0.005% to 0.97${\pm}$0.005%. The total number of born per litter and number of born alive per litter were higher(P〈0.05) in the case of mating twice than mating once. The number of weaned per litter, number of mummified per litter and number of stillborn per litter were not significant(P〈0.05) between mating methods. Estrus interval was shorter on the occasion of twice artificial insemination(5.24${\pm}$0.153days) than twice natural mating(6.51${\pm}$0.466days).

Analysis of First Flushing Effects and EMCs of Non-point Pollutants from Impervious Area during Rainfall (강우시 불투수성 지역의 비점오염물질 EMCs 산정 및 초기세척효과 분석)

  • Ahn, Tae-Woong;Kim, Tae-Hoon;Oh, Jong-Min
    • Korean Journal of Ecology and Environment
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    • v.45 no.4
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    • pp.459-473
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    • 2012
  • This study evaluated the rainfall-runoff characteristics of Non-point Pollution Source (NPS) of the impervious area through on-site monitoring. In this study, trend analysis was performed by various runoff analysis method of non-point pollution source. The characteristics of rainfall at impervious area appeared to be influenced by rainfall strength. It is judged that the measure is required to be prepared against that now that concentration difference of non-point pollution source appeared to be big by precedent number of days of no rainfall. However, it appeared that Rainfall Sustaining Time (RST) has nothing to do with effluent concentration of non-point pollution source, however, the rising tendency that effluent concentration did not appear because the tendency that concentration of non-point pollution source reduces more than 50% within initial 60 min due to first flushing effects and rainfall sustaining time is long. If looking into the outflow tendency of non-point pollution source at the impervious area, it showed the tendency that the concentration lowers gradually as time goes by after initial concentration appeared very high. However, it could be recognized that the concentration of non-point pollution source appeared to be high as the pollutants integrated on the surface of the road during dry season. The Event Mean Concentrations (EMCs) in impervious area were ranged $9.2{\sim}199.3mg{\cdot}L^{-1}$ for TSS, $8.1{\sim}24.2mg{\cdot}L^{-1}$ for $COD_{Mn}$, $0.070{\sim}1.860mg{\cdot}L^{-1}$ for T-N. Based on such runoff characteristics of non-point pollution source, it is judged that it would be desirable to process initial rain efficiently as the measure against initial rain phenomenon at the impervious area.

Diameters of the Thoracic Aorta Measured with Multidetector Computed Tomography (다중검출 전산화 단층촬영을 이용하여 측정한 흉부대동맥의 직경)

  • Lee, Gun;Lim, Chang-Young;Lee, Hyeon-Jae
    • Journal of Chest Surgery
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    • v.42 no.1
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    • pp.79-86
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    • 2009
  • Background: Background: Computed tomography (CT) is the main tool for detecting abnormalities of the thoracic aorta, but conventional CT only shows the cross-sectional images. These CT images have some limitations fo accuratly measuring the thoracic aortic diameters at various levels. Multidetector computed tomography (MDCT) overcomes these limitations. We measured the thoracic aortic diameter perpendicular to the loop-shaped thoracic aortic course and this was studied in relation to age, gender, height, weight, the body surface area, the body mass index and the presence of hypertension. Material and Method: Thirty hundred thirty one patients (males: 141 patients and females: 190 patients) who had no abnormalities of the thoracic aorta were investigated using MDCT aortography. They were divided into three age categories: 20~39 years old, 40~59 years old and over age 60. The image was reformed with multiplanar reconstruction and the diameter of the aorta was measured perpendicular to the aortic course at 5 anatomic segments. Level A was the mid-ascending aorta, level B was the distal ascending aorta, level C was the aortic arch, level D was the aortic isthmus and level E was the mid-descending aorta. Result: The mean age was 49.5 years old for males and 54.9 years old for females (p<0.05). The mean diameter of the thoracic aorta at level A was 31.1 mm, that at level B was 30.2 mm, that at level C was 26.5 mm, that at level D was 24.0 mm and that at level E was 22.6 mm. The diameters at all the levels were gradually increased with age. Hypertensive patients had larger diameters than did the non-hypertensive population. There was a positive correlation between the ascending aortic diameter (levels A&B) and height and the body surface area, but there were no statistical differences at the aortic arch (level C) and the descending aorta (levels D&E). There were no statistical differences of the weight and body mass index at all levels. Conclusion: The diameters of the thoracic aortas were directly correlated with gender, age and hypertension. Height and the body surface area were only correlated with the ascending aorta. Weight and the body mass index have no statistical difference at all levels. We measured the age related thoracic aortic diameters and the upper normal limits and we provide this data as reference values for the thoracic aortic diameter in the Korean population.

Characteristics of Edible Films Based with Various Cultivars of Sweet Potato Starch (고구마 전분을 이용한 가식성 필름의 제조와 특성)

  • Lee, Jung-Ju;Rhim, Jong-Whan
    • Korean Journal of Food Science and Technology
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    • v.32 no.4
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    • pp.834-842
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    • 2000
  • In order to investigate the characteristics of various sweet potato starches, gelatinization temperatures, solution viscosity of starch separated from two cultivars of the dry type sweet potatoes(Yulmi and Gunmi), one cultivar of moist type sweet potato(Jinmi), and one cultivar of purple colored variety(Jami) were compared, and properties of the edible films prepared with the starches were determined. Under a differential scanning colorimetry(DSC), initial temperatures for starch gelatinization of the dry type sweet potatoes (Yulmi and Gunmi) were higher than that of the moist type sweet potato (Jinmi), and that of Jami was close to those of the dry type ones. The sweet potato starch solutions tested by a cone and plate viscometer, showed peudoplastic characteristics. The moist type sweet potato was the most viscous followed by Jami, Yulmi, and Gunmi among the tested starch solutions. Total color difference of the edible films prepared with different cultivars of sweet potatoes showed appreciable differences between cultivars, caused by differences in Hunterb values. Water Vapor Permeability (WVP) of sweet potato starch films also showed significant differences between cultivars. Films prepared with the dry type sweet potato, Gunmi, showed the lowest WVP value of $0.83{\times}10^{-9}\;g\;{\cdot}\;m/m^{2}\;{\cdot}\;s\;{\cdot}\;Pa$, followed by Jami, Yulmi, and Jinmi. Water solubility of the films did not show any significant differences between cultivars. Tensile strength of the dry type sweet potato and Jami, which ranged 14.18-18.75 MPa, were higher than that of the moist type sweet potato, which was 4.66 MPa. Elongation values of the films, which were 5-6%, indicated that sweet potato starch films were not so elastic.

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Effects of Sublethal Doses of Imidacloprid on the Brown Planthopper, Nilaparvata lugens $St{\aa}l$ (Homoptera: Delphacidae) (Imidacloprid의 아치사량이 벼멸구(Nilaparvata lugens $St{\aa}l$)의 생물적 특성에 미치는 영향)

  • Choi, Byung-Ryul;Lee, Si-Woo;Song, Yoo-Han;Han, Man-Jong;Yoo, Jai-Ki
    • The Korean Journal of Pesticide Science
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    • v.4 no.2
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    • pp.56-62
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    • 2000
  • Effects of sublethal dose of imidacloprid on biological characteristics, such as longevity, fecundity and excretions from brown planthopper (BPH) and its repellency to imidacloprid were examined. Topical application of imidacloprid to BPH at the dose of $LD_{10}$ and $LD_{30}$ (These values were determined at 48 hours after topical application of imidacloprid) was remarkably increased the mortality from 3 days after application and showed over 90% mortality on 4 days after application. Topical application of imidacloprid at dose of $LD_{10}$ (16 days) showed no difference compared to the control (16.9 days) in the longevity, while application of $LD_{30}$ was reduced the longevity of BPH to 13.5 days. Application of sublethal dose of imidacloprid to BPH adults reduced the number of eggs laid per day and for adult stage, and the hatchability of their eggs. By root zone application at the dose of $LC_{30}$, 50% longevity and 40% fecundity was reduced respectively, but showed no effect on number of eggs laid per day. The day on which BPH laid 50 % of eggs in number were 7.6 days at the $LC_{10}$ and 5.9 days the of $LC_{30}$ respectively. Hatchabilities of the groups treated with imidacloprid were lower than that of the control. Topical application to BPH at the dose of $LD_{10}$ did not reduce the amount of excretes, but application at the dose of $LD_{30}$ was reduced 26.5% of excretion compared to the control. Leaf dipping into the solution of concentration of $LC_{10}$ and $LC_{30}$ was reduced 96.4% and 98.0% of excretion, respectively. And root zone treatment at the concentration of $LC_{10}$ and $LC_{30}$ reduced 79.5% and 96.6% of excretion, respectively. Repellency rates of BPH to imidacloprid were 20% regardless of the dose of application.

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Characterization of New Bacillus thuringiensis Isolated with Bioactivities to Tobacco Cutworm, Spodoptera litura (Lepidoptera: Noctuidae) (담배거세미나방에 살충효과를 나타내는 새로운 Bacillus thuringiensis 균주의 특성)

  • Kim, Da-A;Kim, Jin-Su;Kil, Mi-Ra;Paek, Seung-Kyoung;Choi, Su-Yeon;Jin, Da-Yong;Youn, Young-Nam;Hwang, In-Cheon;Yu, Yong-Man
    • Korean journal of applied entomology
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    • v.47 no.1
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    • pp.87-93
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    • 2008
  • Bacillus thuringiensis with selected high toxicities against tobacco cutworm, Spodoptera litura were isolated from domestic soils. When being observed under a phase-contrast microscope, the insecticidal crystal proteins were showed a bipyramidal crystal types. New CAB 109 isolate was identified to B. thuringiensis subsp. aizawai in the H serotype. As a results of insecticidal activities between CAB 109 isolate and 3 existing ready-made products against 3rd larva of S. litura, CAB 109 isolate showed 100% mortality with spore concentration $(1.3{\times}10^7cfu/ml)$. It was a very high insecticidal activity compared with a existing ready-made B. t. products. $LD_{50}$ values of CAB 109 isolate was $9.78{\times}10^5,\;6.87{\times}10^6\;and\;1.83{\times}10^7cfu/ml$ spore concentration against 2nd, 3rd and 4th larva of S. litura, respectively. Unlike Plutella xylostella, S. litura was slowly died after application up to 7 days. The weight of S. litura larva applied with CAB 109 isolate were 6-7 times less than controlled group. Even though it didn't die, it did not grow into next larva. The result observed with scanning electron microscope was that CAB 109 isolate of B. t. aizawai formed a typical bipyramidal crystal protein type. Otherwise, when CAB 109 isolate was examined with SDS-PAGE and with trypsin, there was no difference between CAB 109 strain and ready-made products of B. thuringiensis.

Evaluation for Soil Moisture Stabilization and Plant Growth Response in Horizontal Biofiltration System Depending on Wind Speed and Initial Soil Moisture (풍속과 초기 토양수분에 따른 평면형 바이오필터 내 토양수분 안정화 및 식물 생육반응 평가)

  • Choi, Bom;Chun, Man Young;Lee, Chang Hee
    • Korean Journal of Plant Resources
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    • v.27 no.5
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    • pp.546-555
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    • 2014
  • The final aim of this study is to develop a biofiltration system integrated with plant vegetation for improving indoor air quality effectively depending on indoor space and characteristics. However, to approach this final goal, several requirements such as constant pressure drops (PDs) and soil moisture contents (SMCs), which influence the capacity design for a proper ventilation rate of biofiltration system, should be satisfied. Thus, this fundamental experiment was carried out to adjust a proper wind speed and to ensure a stabilization of initial SMCs within biofilter for uniform distribution of SMCs and PDs, and for normal plant growth, especially avoiding root stress by wind. Therefore, we designed horizontal biofliter models and manufactured them, and then calculated the ventilation rate, air residence time, and air-liquid ration based on the biofilter depending on three levels of wind speed (1, 2, and $3cm{\cdot}s^{-1}$). The relative humidity (RH) and PD of the humidified air coming out through the soil within the biofilter, and SMC of the soil and plant growth parameters of lettuce and duffy fern grown within biofilter were measured depending on the three levels of wind speed. As a result of wind speed test, $3{\cdot}sec^{-1}$ was suitable to keep up a proper RH, SMC, and plant growth. Thus, the next experiment was set up to be two levels of initial SMCs (low and high initial SMC, 18.5 and 28.7%) within each biofilter operated and a non-biofiltered control (initial SMC, 29.7%) on the same wind speed ($3cm{\cdot}sec^{-1}$), and measured on the RH and PD of the air coming out through the soil within the biofilter, and SMC of the soil and plant growth parameters of Humata tyermani grown within biofilter. This result was similar to the first results on RHs, SMCs, and PDs keeping up with constant levels, and three SMCs did not show any significant difference on plant growth parameters. However, two biofiltered SMCs enhanced dry weights of the plants slightly than non-biofiltered SMC. Thus, the stability of this biofiler system keeping up major physical factors (SMC and PD) deserved to be adopted for designing an advanced integrated biofilter model in the near future.

Effect of 15% Carbamide Peroxide Agents with and without Potassium Nitrate and Fluoride(PF) on the Tooth Color and Surface Microhardness of Human Enamel (15% 치아미백제의 potassium nitrate와 fluoride(PF) 함유 여부에 따른 치아색조와 미세경도 변화)

  • Woo, Hee-Sun;Shim, Youn-Soo
    • The Journal of the Korea Contents Association
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    • v.12 no.1
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    • pp.353-360
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    • 2012
  • The purpose of this study was to evaluate tooth color and microhardness after 15% carbamide peroxide(CP) bleaching treatments with/without potassium nitrate and fluoride(PF), which were used home bleaching. Thirty tooth specimens were obtained from thirty premolar and were randomly divided into three groups: 1, untreated controls(Distilled water): 2, treatment with 15% CP bleaching agent; 3, treatment with 15% CP bleaching agent (contained 3% potassium nitrate and 0.11% fluoride). All groups were treated 6h per day for 14 days then immersed in distilled water. Changes in enamel color were evaluated on Baseline and Day 14. Microhardness were evaluated on Baseline, Days 7 and 14. All the bleached enamel specimens revealed increased whiteness without control group. Groups 2 and 3 showed significantly decreased enamel microhardness compared to control group. On Day 7, Groups 2-3 showed significantly decreased enamel microhardness compared to control group and respective baseline data. The percentage microhardness loss(PML) look at Day 7 and 14 for Group 1, respectively, there was little difference between 1.7 and 0.8. However, Group 2 was 21.9 and 3.5, Group 3 was 16.7 and 1.4 as a baseline and Day 7 were significantly different (p<0.05). The PML of group 2 was significantly highest than that of group 3 on Day 7. As a result, the data indicate that the addition of PF did not influence the whitening efficacy of the bleaching agent negatively. PF-containing bleaching agent reduce the percentage microhardness loss. PF-containing tooth bleaching your teeth with a whitening effect can be reduced by decreasing the hardness of enamel.

EVALUATION OF RADIOPACITY AND DISCRIMINABILITY OF VARIOUS FIBER REINFORCED COMPOSITE POSTS (수종의 섬유 강화 레진 포스트의 방사선 불투과도와 식별도 평가)

  • Lee, Eun-Hye;Choi, Hang-Moon;Park, Se-Hee;Kim, Jin-Woo;Cho, Kyung-Mo
    • Restorative Dentistry and Endodontics
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    • v.35 no.3
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    • pp.188-197
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    • 2010
  • The purpose of this study was to compare radiopacity and radiographic discriminability of various FRC-Posts. Six FRC-Posts were investigated ; 1) FRC Postec Plus (Ivoclar Vivadent AG, Schaan, Liechtenstein), 2) Snowlight (Carbotech, Lewis center, OH, USA), 3) Dentin Post (Komet Brasseler, Lamgo, Germany), 4) Rely-X Fiber Post (3M ESPE, St.paul, MN, USA), 5) D.T.-Light Post (BISCO, Schaumburg, IL,USA), 6) Luxapost (DMG, Hamburg, Germany) The radiographs of each post with a reference 1 mm / 2 mm aluminum step-wedge was taken using digital sensor. The optical density were calculated by gray value of $10{\times}10$ pixel and compared in mm Al equivalent at five points. Six maxillary incisors of similar radiopacity were used. Radiographs of posts in Mx. incisors of lingual side of dry mandible were taken. We showed radiographs and asked the questionnaire to 3 radiologists, 3 endodontists, 3 general practitioners. The questionnaire was comprised of choices of the highest, lowest radiopaque individual post and the choices of best discriminable post at apical, coronal area. The following results were obtained. 1. Each post system showed various radiopacity. 2. There was change of discriminability between each post and simulated specimens regardless of examiner. Although each post showed various radiopacity, the difference of radiopacity did not affect on discriminability.

Response to Fungicides of Colletotrichum Species Isolated from Infected Tissues of Several Crops (다양한 작물로부터 분리한 탄저병균(Colletotrichum spp.)의 살균제에 대한 반응)

  • Kim Joon-Tae;Min Ji-Young;Kim Heung-Tae
    • Research in Plant Disease
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    • v.12 no.1
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    • pp.32-39
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    • 2006
  • This study has been conducted to investigate the responses of various isolates of four Colletotrichum species such as C. gloeosporioides, C acutatum, C. coccodes, and C. dematium isolated from infected tissues of several crops to fungicides such as carbendazim, carbendazim+diethofencarb, four protective fungicides, and three ergosterol biosynthesis-inhibiting (EBI) fungicides. All the isolates of C. acutatum showed $EC_{50}$ values in a range of 0.001-3.040 ${\mu}g/ml$ against carbandazim, a benzimidazole fungicide. As for the response to carbendazim, the isolates of C. gloeosporioides obtained from pepper, apple, and strawberry were clearly divided into two groups, resistant or sensitive isolates. All the resistant isolates showed $EC_{50}$ values above 1000 ${\mu}g/ml$, whereas the sensitive isolates had lower $EC_{50}$ values than 0.550 ${\mu}g/ml$. The isolates of C. gloeosporioides exhibited a negative cross resistance between carbendazim and diethofencarb (a N-phenylcarbamate fungicide), but isolates of C. acutatum did not. Toward carbendazim, C. coccodes and C. dematium isolates showed a similar response to C. acutatum isolates and the sensitive isolates of C. gioeosporioides, respectively. As for response of Protective fungicides, all the isolates of C. acutatum showed a more resistant reaction than all the isolates of C. gloeosporioides. However, there was no difference among 4 species of Colletotrichum against EBI fungicides.