• 제목/요약/키워드: Difference-in-Differences(DID)

검색결과 1,346건 처리시간 0.037초

협동학습을 활용한 고등학교 영어 쓰기 지도 효과 (The effectiveness of English writing instruction using the cooperative learning approach in high schools)

  • 민찬규;김보경
    • 영어어문교육
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    • 제12권4호
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    • pp.185-210
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    • 2006
  • This study has two purposes. First, it aims to suggest an appropriate approach to English writing education for Korean high school students in a cooperative learning situation. It also aims to suggest what type of learner grouping, either homogeneous or heterogeneous, is appropriate by comparing the learners' writing abilities and the changes of their affective factors after being exposed to cooperative EFL writing instruction. Two homogeneous classes were selected and instructed to write in English for 11 weeks. One was composed of homogeneous small groups based on the students' writing scores, and the other was composed of heterogeneous small groups, again based on the students' writing scores. The results showed that the improvement between the two class types was quite different across different proficiency levels. For example, although there is little difference between the homogeneous and the heterogeneous classes of low and intermediate-level learners in writing ability improvement, high-level students showed a significant difference between the classes. In addition, it was found that class participation correlated significantly to writing ability improvement. Cooperative learning was proved to be an effective writing instructional approach to encourage learners' interest and increase their self-confidence; however, the results did not show any significant differences in learners' affective domain between the homogeneous and the heterogeneous classes. Similarly, the learners' grouping preference was not affected by the grouping method.

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Prognostic role of preoperative carcinoembryonic antigen levels in colorectal cancer: propensity score matching

  • Kim, Cho Shin;Kim, Sohyun
    • Journal of Yeungnam Medical Science
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    • 제34권2호
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    • pp.216-221
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    • 2017
  • Background: This study was conducted to investigate preoperative carcinoembryonic antigen (CEA) as a prognostic factor in colorectal cancer. Methods: Between January 2000 and July 2011, 1298 patients with primary adenocarcinoma colorectal cancer without metastasis, who underwent curative resection were retrospectively identified. The patients were divided into two groups according to serum CEA level at primary diagnosis: a high CEA (HCEA) group (serum CEA ${\geq}6ng/mL$) and a normal CEA (NCEA) group (serum CEA <6 ng/mL). A 1:1 propensity score matching analysis was applied to reduce bias. Finally, 364 patients were enrolled in this study. Matched variables were age, gender, preoperative chemoradiotherapy, tumor site, cell differentiation and pathologic stage. Results: The clinicopathological characteristics of the two groups did not differ significantly difference. The systemic metastasis rate was 16.5% (30/182) and 25.3% (46/182) in the NCEA and HCEA groups, respectively (p=0.039). There were no significant differences in local recurrence or metastatic sites between groups. The 5-year disease-free survival (DFS) rate of the HCEA group was worse than that of the NCEA group; however, there was no significant difference in overall survival between the two groups. Conclusion: Elevated preoperative CEA was related to frequent systemic recurrence and low DFS. Therefore, elevated preoperative CEA could be considered a prognostic factor for worse clinical outcomes in patients with colorectal cancer.

비대면 수업에서 온라인 실습활동의 사례- '기초전기회로 및 실습' 교과목을 중심으로 (A Case Study of Online Practice Activities in Non-face-to-face Class - 'Introduction to Electric Circuits and Lab' Course)

  • 한안나;이호철
    • 공학교육연구
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    • 제25권1호
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    • pp.22-32
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    • 2022
  • The purpose of this study is to design and operate non-face-to-face online practice class in engineering education, and to explore students' perceptions and effectiveness of them. To this end, after developing and implementing a strategy for non-face-to-face online practice activities in the 'Introduction to Electric Circuits and Lab' course, the questionnaire responses of 47 learners were analyzed, and the group differences were investigated using Kruskal-Wallis test. As a result, it was found that students' perceptions of non-face-to-face online practice class were positive in terms of learning effect, learning convenience, interaction, and satisfaction. The group difference according to the face-to-face/non-face-to-face preference method was found to be higher in the group that preferred non-face-to-face class in terms of learning convenience, interaction and satisfaction. As for the group difference according to the number of questions and answers of the learners, the group who answered the question showed a higher awareness of the learning convenience and interaction than the group that did not. In addition, implications for designing a learning environment for non-face-to-face online practice classes were presented.

성견에서 수산화인산염 피개 IMZ임플란트와 티타늄 피개 IMZ임플란트주위의 골형성 및 골성숙 정도에 대한 비교연구 (EFFECTS OF HYDROXYAPATITE AND TITANIUM-COATED DENTAL IMPLANTS ON BONE FORMATION AND MATURATION IN DOG)

  • 윤홍철;한동후
    • 대한치과보철학회지
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    • 제33권2호
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    • pp.317-334
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    • 1995
  • The purpose of this study was to compare the bone formation, maturation around HA-and titaniumcoated dental implants in dog. 5 hydroxyapatite coated IMZ implants and 5 titanium coated IMZ implants were placed into the previously extracted site in the mandible of 5 adults dogs. All dogs were injected intravenously Tetracycline, Alizalin red S, and Calcein for bone fluorescent labelling, After the experimental period of 16weeks, the dogs were sacrificed and tissue samples around the implants were obtained. Microscopic observations(ligth, polariged and fluorescence microscope), morphometric analysis, line profile with EPMA, and quantitative analysis for Ca,P, and Ti were performed. The results were as follows ; 1. Bone maturations around the implants were relatively lower than those of natural teeth. No significant differences in bone maturation and remodeling patterns were observed between the two implants groups. 2. Calcification of bone surrounding the implants was initiated in 8-11 weeks for HA-coated implants, while it took 11 weeks or more for Ti-coated implants. 3. Bone-to-implants contact ratio of 82.63% was recorded for HA-coated group and 72.25% for titanium coated group, with no significant difference between the two groups. 4. Bone around the implants exhibited reduced quantity of Ca and P in the $100{\mu}m$ region relative to natural teeth, while the rest of the regions showed no statistical differences. No significant differences were found between the two implant groups. 5. There was a separation of HA layer from the implant core and subsequent infiltration of inflammatory cells into the resulting space in the HA-coated implants, and evidences of phagocytosis of HA particles by macrophages. Bone calcification was more rapid around HA-coated implants compared to titanium-coated implants, but HA coated implants did not show any significant differences either in the degree of calcification or the bone-to-implant contact ratio over Ti coated implants. HA coated implants may have complications associated with HA absorption and separation of HA layer from the implant core.

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인지진단모형을 적용한 TIMSS 8학년 수학 기하 영역의 성차 분석 (Gender Differences in Geometry of the TIMSS 8th Grade Mathematics Based on a Cognitive Diagnostic Modeling Approach)

  • 이현숙;고호경
    • 대한수학교육학회지:학교수학
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    • 제16권2호
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    • pp.387-407
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    • 2014
  • 수학에서의 성차는 교수 학습 환경에서 학습자에 대한 공평성을 추구하는 맥락에서 연구자들의 지속적인 관심을 받아 왔다. 수학의 여러 영역 중 특히 기하 영역은 전통적으로 남학생이 여학생에 비해 높은 성취를 보이는 영역으로 인식되어 왔으나, 최근에는 성차가 완화되거나 점차 사라지고 있다는 경험적 증거들이 종종 보고되고 있다. 본 연구에서는 2003년부터 2011년까지 3개 주기 동안 실시된 TIMSS 8학년 수학과 데이터를 활용하여 우리나라 중학생들이 기하 영역의 각 하위 인지요소에서 나타내는 성차를 인지진단모형을 활용하여 고찰하였다. 본 연구에서는 여러 가지 인지진단모형 중 교육 전문가에게 유용하고 해석 가능한 정보를 제공할 수 있는 Fusion 모형을 적용하였다. 연구결과, 기하 영역의 세부 인지요소 중 '입체도형의 모양'에 있어서는 2003년과 2007년 각각 남학생이 여학생에 비해 높은 숙달 확률을 나타내었으나, 2011년에는 전체 인지요소에서 남녀 간에 차이가 없는 것으로 나타나, 성차가 완화되고 있다는 최근 연구들을 지지하는 하나의 경험적 증거를 제공하였다. 이밖에 인지진단모형을 적용하여 성차를 분석한 결과에 따라, 학생들의 인지요소 숙달 프로파일이 남녀 간에 어떠한 차이를 보이는지, 그리고 특정 문항을 푸는데 있어서 반드시 필요하다고 정의된 인지요소들이 성별에 따라 상대적으로 더 혹은 덜 중요하게 기능하는지 등에 대해 고찰하고 이에 근거하여 기하 영역의 교수 학습에 시사점을 제공하였다.

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만성 뇌졸중 환자에서 피질 척수로와 운동 능력의 상관관계 연구 (The Functional Role of the Corticospinal Track in Relation to Motor Functions in Chronic Stroke Patients)

  • 여상석
    • PNF and Movement
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    • 제12권3호
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    • pp.143-150
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    • 2014
  • Purpose: The corticospinal tract (CST) is known to be an important pyramidal tract for walking and motor function. However, very little is known about the functional role of the CST in the recovery of motor function. In the current study, we investigated the relation between the CST and motor function in chronic hemiparetic stroke patients. Methods: Fifty-four patients and 20 normal subjects were recruited. The Functional Ambulation Category (FAC) was used in measurement of the walking ability. We classified patients into three groups according to the ability to walk independently: group A, patients who could not walk independently (FAC: 0-2); group B, patients who could walk independently (FAC: 3); and group C, patd walk functionally (stairs and uneven surfaces, FAC 4-5). The Motricity Index (MI) was used to measure the motor function of the affected upper and lower extremities (maximum score: 100). The fractional anisotropy (FA) value, apparent diffusion coefficient (ADC) value, and fiber volume of the CST were used for the diffusion tensor imaging (DTI) parameters. Results: In terms of the CST of the unaffected hemisphere, the FA value of group A was significantly lower than that of normal controls (p <0.05). The fiber volume of group C was significantly higher than that of normal controls (p <0.05). In contrast, the ADC values of all patient groups and the control group did not show any difference (p >0.05). In terms of lower MI and total MI, significant differences were observed between all patient groups (p <0.05). In addition, significant differences in terms of the upper MI scores were observed between groups A and C and between groups B and C (p <0.05); however, no significant difference was observed between groups A and B (p>0.05). Conclusion: The increased fiber volume of the CST in the unaffected hemisphere appears to be related to functional walking ability in chronic stroke patients. This result would be useful for elucidation of the neural recovery mechanism of walking and the investigation of new modalities for the recovery of walking following a stroke with CST injury.

장애물 높이에 따른 성인과 노인의 족저압 분포 비교 (The Comparison of Plantar Foot Pressure Distribution in Adult and Elderly according Obstacle Heights)

  • 장종성;이명희
    • The Journal of Korean Physical Therapy
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    • 제26권4호
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    • pp.257-261
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    • 2014
  • Purpose: The purpose of this study was to compare plantar foot pressure distribution in adults and elderly according to obstacle height. Methods: Nine healthy adults and nine older adults were recruited and the subjects provided written informed consent consent prior to participation. Both groups walked and crossed obstacles with heights of 0%, 10%, 20%, and 30% of their height. Foot pressure was measured by peak pressure using the Pedar System (Novel Gmbh, Germany) during obstacle walking with barefeet in shoes. Three trails were calculated on eight areas and then averaged for data analysis. Results: A significant difference in great toe, little toes, and lateral metatarsal area was observed between adults and elderly groups, but other areas did not show significant differences. Foot pressure was increased in groups according to obstacle height. Conclusion: These findings showed that change in foot pressure distribution is more lateral in elderly in order to maintain postural control during obstacle crossing.

바람장 및 Fingerprint를 이용한 악취추적기법 활용가능성 평가 (Applicability Investigation for the Odor Source Tracking Approach using the Wind Field and the Fingerprinting)

  • 나경호;박용출;장영기
    • 한국대기환경학회지
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    • 제23권1호
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    • pp.1-13
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    • 2007
  • This study was carried out to evaluate the applicability of the odor source tracking using wind field and fingerprint as a solution tool. First of all, CALMET and HYSPLIT modeling system, and database of odor discharge companies were utilized to track odor from industrial complexes. Secondly, industrial odor fingerprint was made by listing on the 19 domestic industries, and compared with foreign data to assess the representative, and thus the similarity was 86.7%. On the modeling experiment, Sihwa industrial complex did not show any difference because the matching rates of day and night were 49.5% and 50.0%, respectively. However, the Banwol and Sihwa industrial complexes did show some differences due to odor facility density. Separately, in this study, odor samples were obtained from 10 odor discharging companies, located in the Sihwa and Banwol industrial complexes, They were compared with the results of odor tracking modeling. The matched companies were 4 of 10 by three cases of tracking, while the fingerprint and industry of odor monitoring networks and companies matched each other. Therefore, this study confirmed the approach applicability of source tracking system using the fingerprint.

한우종모우의 번식능력에 관한 연구 II. 2재종모우의 정액채취빈도가 정액성장 및 성적활동에 미치는 영향 (Studies on Reproductive Capacity of Korean Native Bulls II. Effect of collection Frequency on Semen Characteristics and Sexual Activity in 2-Year-Old Bulls)

  • 김창근;정영채;김종대;김선환
    • 한국가축번식학회지
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    • 제9권1호
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    • pp.40-45
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    • 1985
  • Eight 2-yr old bulls from Artificial Breeding Center, NLCF were used to determine the effectof collection frequency on semen characteristics and sexual activity. Two successive ejaculates per day were collected by artificial vagina for 4 weeks on weekly or twice a week. Total ejaculate volume included 2nd ejaculates for one time and two time bulls was 6.8ml and 6.0ml, but there was no significant difference between collection intervals. Sperm concentration of one time and two time bulls averaged 0.79$\times$109/ml and 0.89$\times$109/ml, respectively. Total sperm per ejaculate was 5.14$\times$109 for one time bulls and 5.45$\times$10 for two time bulls. Two time bulls had slight more sperm per ml and ejaculate than one time bulls, but there were no significant differences between two group bulls. Sperm motility and semen pH of two time bulls was slightly better than that of one time bulls. In changes of bulk minerals in semen, solium concentration of two time bulls was similar to that of one time bulls. Potassium and calcium was more concentrated in one time bulls than in two time bulls, but these concentrations did not differ significantly. Libido score for two time bulls was higher than that for one time bulls. However, there was no difference between two groups and these scores did not change for 4 weeks in two goups. Total time to 2nd ejaculation was 16.3 sec for one time bulls and 20.5 sec for two time bulls.

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공동주거단지 개발에 따른 주변지역 거주자의 근린의식 특성에 관한 연구 - 광주광역시 사례를 중심으로 - (Study on the Characteristics of the Residents' Sense of Neighborhood in the Surrounding Area after the Housing Complex Development - Focused on the Cases in Gwang-Ju -)

  • 이수용;오세규;문출성
    • 한국주거학회논문집
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    • 제22권2호
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    • pp.53-61
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    • 2011
  • This study aims to examine the characteristics of the changes in residents' perception of neighborhood and sense of neighborhood according to the residential structural changes caused by city renewal projects such as old urban large redevelopment. Research findings benefits of the residential environment changes after the development are environment improvement, convenient traffic, leisure activity increase, and green area increase, whereas their drawbacks are encroachment of sunshine and view, However, with the regard to the relationship with neighbors, paired-sample t-test results showed there were no statistically significant differences between before and after the development. It appeared to be that the community residential complex development did not influence the relationship with neighbors. ANOVA was used to examine the differences in the neighborhood perception among age categories. The results showed that there were no differences between age groups but when there were changes in their life cycle, residents showed differences in their neighborhood perception among age groups. The neighborhood perception was measured on 5-point Likert Scale in four factors of intimacy, participation, reliability, and group identity. The perception decreased somewhat after the development and the group identity, especially, showed a significant difference (p<.001). This was considered to be caused by a sense of incongruity due to the influx of different social-economic groups.