• Title/Summary/Keyword: Difference-In-Difference

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Construction Considering the Difference of Setting Time of Super Retarding Agent for Reduction of Hydration Heat of Footing Mass Concrete (기초 매스콘크리트의 수화열 저감을 위한 초지연제 응결시간차 공법의 현장 적용)

  • 황인성;배정렬;윤석명;김기철;오선교;한천구
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2003.05a
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    • pp.95-98
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    • 2003
  • This paper presents the results of field experiment to apply the difference of setting tine method using super retarding agent for reducing hydration heat of mass concrete of foundation. According to the results, as the properties of fresh concrete, base concrete satisfies aimed slump and air content, and there is no difference of slump and air content with mixture of super retarding agent. The mixing ratio of super retarding agent is determined for setting time to be retarded by 12 hours in comparison with base concrete, but because the temperature of the air and concrete is low, the difference of setting time is retarded to 24 hours. In man concrete of foundation to which the difference of setting time method is applied, crack by hydration heat is not seen because the lower concrete of super retarding agent generates heat after generation of hydration heat of the upper concrete.

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An Error Analysis of Precise Point Positioning using Ionosphere Free Combination Measurements (IF 조합 측정치를 사용하는 단독 정밀 측위 오차해석)

  • Park, Sul-Gee;Cho, Deuk-Jae;Shin, Young-Cheol;Park, Chan-Sik
    • Journal of Institute of Control, Robotics and Systems
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    • v.18 no.9
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    • pp.871-877
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    • 2012
  • An error analysis of PPP (Precise Point Positioning) using IF (Ionosphere Free) combination is given in this paper. It is shown that the performance of the ordinary model with positions, clock bias, integer ambiguities and ionosphere delay as unknowns is equivalent to that of an ionosphere difference combination where ionosphere delay is cancelled out. Furthermore, it is shown that IF combination is an ionosphere difference combination but not unique. It is also proved that all difference models show same performances. The error analysis evaluated with a hardware simulator and real measurements show that the ionosphere delay is effectively eliminated by IF combination or equivalently by the ionosphere difference combination. However, if bias errors such as troposphere, clock bias or multipath are included in the measurements, the performance of the IF combination is degraded because the bias errors are amplified by the ionosphere difference operation.

A Study on the Optimum Synthesis of Line Source Difference Patterns by Sidelobe Level Control (Sidelobe 레벨 제어를 통한 선전원 차패턴 최적 합성에 관한 연구)

  • Park, Eui-Joon
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.44 no.6 s.360
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    • pp.57-63
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    • 2007
  • In this paper, a new approach to the optimum synthesis of line source difference patterns is proposed for the monopulse tracking way antennas. In the Proposed scheme, which is different from the well-known Bayliss difference pattern synthesis, the difference patterns with the desired individual sidelobe levels are optimally synthesized by appropriately modifying the Taylor line source sum pattern formula. That is, the relationship between the difference pattern and the corresponding source distribution function is analytically established, and then the desired pattern and the distribution are simultaneously extracted by the optimum perturbation of pattern null positions. Furthermore this method provides more rapid sidelobe decay rates than conventional methods. Some numerical results show the validity and usefulness of the proposed procedures.

- A Comparative Study on the Actual Somatotype and the Cognitive Somatotype of Female College Students and High School Students - (개인적 인식에 의한 인지체형과 실제체형과의 비교연구)

  • 정옥임
    • Journal of the Korean Home Economics Association
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    • v.31 no.1
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    • pp.153-162
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    • 1993
  • The purpose of this study is to demonstrate the physical consciousness of two groups, the high school girl(335) and the female college students(246), about their actual somatotype and cognitive comatotype, and to investigate it in comparison with the R hrer Index, the BMI Index, and the Broca-Katsura Index to find if there is any difference between the two groups. The results are as follows; A. In the light of cognitive somatotype by self-evaluation:(1) both high school girls and female college students recognized their weight and somatotype as normal and balanced with no significant difference between them. (2) bout groups indicated that their answers were the results of their own self-evaluation, and it was shown that there was a significant difference between the two groups. B. According to the actual somatotype based on Index. (1) it was shown there was a significant difference between the cognitive somatotype and the actual one of the tow respective groups when based on the Broca Katsura Index. (3) there was a significant difference between the cognitive somatotype and the actual one of the two respective groups when based on the Rohrer Index. Finally, it was shown that there was a significant difference between the two groups.

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Biomechanics analysis by golf drive swing pattern (골프 드라이브 스윙시 구질 변화에 따른 운동학적 분석)

  • Choi, Sung-Jin;Park, Jong-Jin;Yang, Dong-Ho
    • Korean Journal of Applied Biomechanics
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    • v.12 no.2
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    • pp.259-278
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    • 2002
  • This study divided straight success, pade success and failure with 7male golfers who have experiences more than 3 years, analyzed kinematic factors of golf swing to suggest scientifically. The conclusions were follows. 1) The wrist angle has significant difference in straight success, pade success and failure when swing of every pattern. There is no significant difference in pade success and failure. 2) The body twist angle has no significant difference in straight success, pade success and failure when swing of every pattern. There is no significant difference in pade success and failure. 3) The shoulder joint rotation angle has no significant difference in success, pade success and failure when swing of every pattern. There is no significant difference in pade success and failure. 4) The left hip joint vertical angle has no significant difference in straight success, pade success and failure when swing of every pattern. There is no significant difference in pade success and failure. 5) The hip joint rotation angle has no significant difference in straight success, pade success and failure when swing of every pattern. There is no significant difference in pade success and failure. 6) The trunk angle has no significant difference in straight success, pade success and failure when swing of every pattern. There is no significant difference in pade success and failure. 7 )The left knee joint angle has no significant difference in straight success, pade success and failure when swing of every pattern. There is no significant difference in pade success and failure. This study divided golf swing motion of pattern change in straight success, pade success and failure and analyzed the kinematic factors by 3-dimension cinematography to improve performance. In the future, many researchers have to study kinematic analysis to improve performance in every events.

An Exploratory Study on the Main Factors Affecting Health Perception of the Patients Following Cardiac Valve Replacement Surgery (판막치환수술후 환자들의 건강인지도에 영향을 미치는 제요인에 관한 연구)

  • 김금순;전동희
    • Journal of Korean Academy of Nursing
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    • v.15 no.1
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    • pp.52-58
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    • 1985
  • This study was attempted to investigate the main factors affecting health perception of the patients following cardiac valve replacement surgery. Data were collected from Sept. 1 to Oct. 31, 1984 through administration of questionnaire developed for this study by the researcher. The subject was 95 patients who received follow up care following cardiac valve replacemert surgery at S.N.U.H. The data were analyzed by T-test, oneway ANOVA, pearson correlation and multiple regression according to dependent variables. The results were as follows. \circled1 Average self-health perception of those patients. were 4.62, (maximum; 7 minimum; 1) and they showed on affirmative response for their health condition, \circled2 There was significant difference in health perception according to sex difference. Men had higher health perception than women. (t=2,83, p=0.006) \circled3 There was significant difference in health perception according to occupation. Those who had occupation showed higher health perception those who had no occupation. (t=3.25, p=0.002) \circled4 The longer post-operative period elapsed, the higher health perception was, and there was significant difference in health perception (f=0.2958, p=0.002). \circled5 The higher age was, the lower health perception was, and there was a significant difference in health perception. (${\gamma}$= -0.2485, p=0.008) \circled6 The fewer subjective psychosomatic symptoms were, the higher health perception was, and there was a significant difference in health perception. (f = -0.4988, p=0.0000) \circled7 The more active daily activities were, the higher health perception was, and there was a significant difference in health perception. (${\gamma}$=0.6359 p=0.0000) \circled8 The main factors predicting health perception .are like these. \circled1 Daily activities (42.7%), highest variable. \circled2 Psychosomatic symptoms (7.29%) \circled3 Elapsed period after cardiac valve replacement surgery (1.89%) \circled4 Existence of occupation (1.87%) \circled5 Sex (1.78%) \circled6 Age (0.8%).

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Perceived competence of Children and Perception of responsibilities of Parents Based on Age, Sex, Sociometric Status (연령, 성별, 사회측정적지위에 따른 아동의 자기능력지각과 부모의 책임지각)

  • 이진화
    • Journal of the Korean Home Economics Association
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    • v.33 no.6
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    • pp.225-244
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    • 1995
  • The purpose of this study is to see difference based on age, sex, sociometric ststus for perceived competence of children and difference about perception of responsibilities degree of parents of these children. the content of study as follows. 1. How is the difference about perceived competence of children based on age, sex, sociometric status. 2. How is the difference about perception of responsibilities of children based on age, sex, sociometric status. 3. How is the relationship between father and mother. The subject of this study is children and their parents of 126 persons of the third grade, sixth grade of S elementary school, the second grade of S middle school, the second grade of S girls' middle school which are located in Pusan city. This study used a peer nomination among sociometric assesment method as sociolity assessment means, self-perception profile for children of Harter(1985) as perceived competence assessment means of children and used self-perception profile for children which amends fits for parents. the collected data are managed by SPSS/PC+ program. We analyze three-way ANOVA to verify study question No, one, two, analyze t-verification and Pearson's product moment correlations to verify study question No. three. The result of this study as follows. First, in investigating difference about perceived compretence of children based on age, sex, sociometric status, we can see that children perceive high, self-ability for low ages. Also, boys than girls, popular children than rejected children, neglected children perceive high self-ability. Second, in investigating difference about perception of responsibilities of children based on age, sex, sociometric status, we can see that mother perceive responsibilities in learning sphere, exercise sphere, the whole self-value sphere and father perceive responsibility only in social sphere. Third, in investigating relation between perception of responsibilities of father and mother, this shows that difference between perception of responsibilities of father and mother is not showed ane have (+) interrelation of r=.46(P<.001) between perception of responsibilities of father and perception of responsibilities of mother.

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An Analysis of the Gender Difference in National Assessment of Educational Achievement of Mathematics (수학과 국가수준 학업성취도 평가에서의 성별 차이 분석)

  • Ko, Jung-Hwa;Do, Jong-Hoon;Song, Mi-Young
    • Journal of Educational Research in Mathematics
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    • v.18 no.2
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    • pp.179-200
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    • 2008
  • In this paper, we analyzed the characteristics of the gender difference with the results of National Assessment of Educational Achievement(NAEA) from 2004 to 2006, which subjects are 3rd, 9th and 10th graders. First, we analyzed the characteristics of the achievement by the scale scores, according to years, achievement standards, grades. Second, we surveyed the number of items and ratio which male/female prevails and its characteristics according to grades, difference levels, content areas(i.e., numbers and operations, figures, measurement, probability and statistics, letters and formulas, patterns and function). Furthermore, we perform in-depth analysis of the items which gender difference in correct response proportion is more than 7% and analyze the cause of gender difference of achievement. This paper provides large valid data about gender difference by the results of NAEA. It can give suggestions with regard to policy making.

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The effect of using a Nursing Standards on the Quality of Nursing care in Musculo-skeletal Disorder Patients (간호표준 적용이 근${\cdot}$골격장애 환자의 간호질에 미치는 효과)

  • Choe, Sun-Ok
    • Journal of Korean Academy of Nursing Administration
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    • v.9 no.1
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    • pp.89-101
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    • 2003
  • Purpose : this study was to examine the effect of using a nursing standards for the quality of nursing care in musculo-skeletal patients. Method : The approach to nursing quality assurance evaluation was selected process-outcome framework. The subjects ware 100 case of musculo-skeletal patients in orthopedic surgery nursing care unit of E. university hospital in seoul. The data of a control group were collected from 23 December 2001 to 20 March 2002 and an experimental group were collected from 1 June to 25 August 2002. The instruments used for this study were a nursing care standards in musculo-skeletal disorder patients developed by the investigator and an evaluation tool for the quality of nursing care in orthopedic surgery patients developed by soon-ook Choi in 1995. It's reliability is Cronbach alpha=.8628. The data were analyzed by means of $x^1$-test, t-test, ANOVA with SPSS program. Results : This study are as fellows : 1. Scores of the quality of nursing care in standard 1 in the experimental group were higher than those of the control group with no significant difference(t=-8.793, p=.000), scores of the quality of nursing care in standard 2 in the experimental group were higher than those of the control group with significant difference(t=-8.793, p=.000) and standard 3 in the experimental group were higher than those of the control group with significant difference(t=-10.550, p=.000). scores of the quality of nursing care in standard 4 in the experimental group were higher than those of the control group with significant difference(t=-8.793, p=.000). scores of the quality of nursing care in standard 4 in the experimental group were higher than those of the control group with no significant difference(t=-1.833, p=.070). 2. Scores of the quality of nursing care in criteria 28 of 33 criteria in the experimental group were higher than those of the control group with significant difference in 12 criteria(p<.05 ). 3. Scores of the quality of nursing care in standard 1 to standard 4(process evaluation); the experimental group were higher than those of the control group with significant difference(t=-10.704, p=.000). scores of the quality of nursing care in standard 5(outcome evaluation); the experimental group were higher than those of the control group. but no significant difference(t=-1.833, p=.070). 4. Scores of the quality of nursing care in experimental group were higher than those of the control group with significant difference(t=-10.794, p=.000). Conclusion : Through this study, I'm sure that using a nursing care standards in musculo-skeletal disorder patients improve quality of nursing care and nursing care standards are effective nursing care.

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A Study on the Vertical Temperature Difference of Steel Box Girder Bridge by Field Measurement (실측에 의한 강박스거더교의 상하 온도차에 대한 연구)

  • Lee, Seong-Haeng;Park, Young-Chun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.8
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    • pp.545-551
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    • 2018
  • For domestic application of the temperature gradient model proposed by foreign design standards, a specimen of steel box girder bridge was fabricated with the following dimensions: 2.0 m width, 2.0 m height and 3.0 m length. Temperature was measured using 24 temperature gauges during the summer of 2016. The reliability of the measured data was verified by comparing the measured air temperature with the ambient air temperature of the Korea Meteorological Administration. Of the measured gauges, four temperature gauges that can be compared with the temperature difference of the Euro code were selected and used to analyze the distribution of the measured temperatures at each point. The reference atmospheric temperature for the selection of the maximum temperature difference was determined by considering the standard error. Maximum and minimum temperatures were calculated from the four selected points and the resulting temperature difference was calculated. The model for the temperature difference in the steel box girder bridge was shown by graphing the temperature difference. Compared to the temperature distribution of the Euro code, the presented temperature difference model showed a temperature difference of $0.9^{\circ}C$ at the top and of $0.3^{\circ}$ to $0.4^{\circ}C$ at the intermediate part. These results suggested that the presented model could be considered relatively similar to the Euro code The calculated standard error coefficient was 2.71 to 2.84 times the standard error and represents a range of values. The proposed temperature difference model may be used to generate basic data for calculating the temperature difference in temperature load design.