• 제목/요약/키워드: difference-in-differences method

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Proposal of Research Methodology Using The Measurement of Perception Difference

  • YANG, Hoechang
    • 웰빙융합연구
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    • 제2권2호
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    • pp.39-45
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    • 2019
  • The purpose of this study is to solve the problem of revision or abbreviation of questionnaires based on the previous studies suggested by many existing empirical studies. In addition, this study aims to provide the theoretical basis of the research method which has been variously approached since it presents the methodology that can directly measure the research object. For this purpose, this study proposed a more elaborate analysis method using the differences in perception of individuals who are interested in cognitive research. Specifically, the perception gap(D) can be used as an independent variable, a dependent variable, and a moderating variable. And this study suggested an effective research approach using the measurement of perception difference. The difference of perception suggested that it can be used as a measure to overcome the limitations of existing researches used it as independent variables or mediating variables that measure only one factor of expectation and performance or importance and satisfaction. In addition, it is highly likely that various analyzes on the perception differences, which are the result of measuring target factors for the same person, will be quite effective in the situation where follow-up of respondents is difficult. This study is expected to overcome various limitations reported by empirical studies such as scale utilization problem and follow-up survey difficulty. In future research, it was expected that the limitation of the factor derivation process in the research approach could be complemented by web crawling and text mining of big data analysis.

상관행렬의 구조분석에서 집단평균차이의 효과: 요인분석기법을 중심으로 (The Effect of Group Mean Differences upon Factor Analysis)

  • 김청택;이소영
    • 한국조사연구학회:학술대회논문집
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    • 한국조사연구학회 2001년도 춘계학술대회
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    • pp.109.2-130
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    • 2001
  • 이 논문의 목적은 상관분석에서 집단차 변수를 무시하였을 때 자료에 대한 잘못된 해석을 유도할 수 있음을 보여주고, 집단차를 고려한 분석의 중요성과 그 방법을 제시하는 것이었다. 연구 1은 시뮬레이션 연구로 상관구조에 대한 분석인 요인분석에서 집단차를 무시하면 자료가 지니고 있던 요인구조를 파악하지 못함을 보여주었다. 이에 대한 대비책으로 표준점수에 의한 자료의 변환 방법과 공분산 구조모형의 집단분석을 이용하는 방법등이 제시되었다. 연구 2는 사례연구로 실제 자료에서 집단의 평균차에 의한 효과가 발생하는지를 지능검사 자료를 이용하여 예증하고 이러한 문제점을 해결할 수 있는지를 보여주었다.

상관행렬의 구조분석에서 집단평균차이의 효과: 요인분석기법을 중심으로 (The Effect of Group Mean Differences upon Factor Analysis)

  • 김청택;이소영
    • 한국조사연구학회지:조사연구
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    • 제2권2호
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    • pp.109-130
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    • 2001
  • 이 논문의 목적은 상관분석에서 집단차 변수를 무시하였을 때 자료에 대한 잘못된 해석을 유도 할 수 있음을 보여주고, 집단차를 고려한 분석의 중요성과 그 방법을 제시하는 것이었다. 연구 1은 시뮬레이션 연구로 상관구조에 대한 분석인 요인분석에서 집단차를 무시하면 자료가 지니고 있던 요인구조를 파악하지 못함을 보여주었다. 이에 대한 대비책으로 표준점수에 의한 자료의 변환방법과 공분산 구조모형의 집단분석을 이용하는 방법 등이 제시되었다. 연구 2는 사례연구로 실제 자료에서 집단의 평균차에 의한 효과가 발생하는지를 지능검사 자료를 이용하여 예증하고 이러한 문제점을 해결할 수 있는지를 보여주었다.

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제어 알고리즘 구현을 위한 새로운 미분값 유도 방법 (New approach method of finite difference formulas for control algorithm)

  • 김태엽
    • 전기전자학회논문지
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    • 제23권3호
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    • pp.817-825
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    • 2019
  • 마이크로프로세서를 이용한 제어알고리즘 구현에서 차분방정식이 매우 유용하게 사용된다. 샘플링 데이터로부터 미분 값을 추정하기 위해 전향, 후향 및 중심 차분 방식이 사용되어왔다. 차분 값을 계산하기 위해서는 차분계수가 매우 중요하다. 본 논문에서는 유한 차분 계수를 계산하기 위한 새로운 방식을 제시하고자 한다. 제안된 방식의 유효성을 입증하기 위해 RLS 알고리즘을 적용한 파라미터 추정에 대하여 적용하였다.

아래팔 내측분지신경의 자극하는 방법에 따른 신경전도검사의 비교 (The Medial Antebrachial Cutaneous Nerve : Orthodromic and Antidromic Conduction Studies)

  • 곽재혁;이동국
    • Annals of Clinical Neurophysiology
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    • 제7권2호
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    • pp.83-87
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    • 2005
  • Background: The study of the medial antebrachial cutaneous nerve (MABCN) is an underused electrodiagnostic tool. But its use is often crucial for assessing mild lower brachial plexus or MABCN lesions, and sometimes for differentiating an ulnar mononeuropathy from a lower brachial plexopathy. This study was designed to know the difference of amplitude and velocity in a stimulation method (orthodromic vs antidromic), side of an arm and sex according by age. Method: MABCN conduction studies were performed orthodromically and antidromically in 90 subjects (42 women and 48 men, ranging from 22 to 79 years of age). We divided subjects into three groups by age (group 1: 20-39 years, group 2: 40-59 years, group 3: 60-79 years). The mean sensory nerve action potential amplitudes and sensory nerve conduction velocities in each group was compared by stimulation method, side of an arm and sex. Result: The amplitudes and velocities made a significant difference between orthodromic and antidromic method in all age groups. At comparison in amplitude and velocity by side of an arm, only amplitude was significantly higher in right arm than left by any stimulation method. The amplitudes and velocities were of no statistically differences in sex except amplitude checked orthodromically in right arm. Conclusion: This study suggests that there is the differences in conduction study of MABCN by stimulation method and side of an arm.

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편마비 환자의 슬건근의 근력의 차이가 보행에 미치는 영향 (The Influenc on Ambulation of the Difference in Muscle Strength on Hamstring Muscle of Hemiplegic Patients)

  • 윤장순
    • 대한물리치료과학회지
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    • 제12권4호
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    • pp.69-77
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    • 2005
  • The purpose of this study is to estimate how much the motility of affected and unaffected lower limb respectively would have effects on their ambulation through comparing the difference between their affected and unaffected lower limb and studying the correlation between such difference and their ambulation. In addition, the study also intends to find out remedial measures suitable for improving their ambulation with relevant physical treatment. To do this, a quantitative electromyogram(QEMG) test was done to hamstring of affected and unaffected lower limb so as to yield IP values. Based on such IP values, RMS(root mean square) values as the total sum of IP values were found with QEMG analysis system (made by Medelec Co.) and then the ambulation depending on the difference in muscular strength were analyzed by ink-foot print method as well as the corresponding statistics were processed by T-test through SPSS. The differences in muscular strength of hamstring in unaffected limbs of hemiplegic patients only affect stride length. It was statistically significant. The effect of difference in muscular strength of the hamstring in affected limb of hemiplegic patients on their ambulation was very different between strong and weak group in terms of walking velocity, step per minute, stride and step length, showing statistically significant difference(p<.05). Although there was a difference in the step length of the affected limb, it was not statistically significant(p>.05). For the unaffected hamstring, there were significant differences of stride length between in unaffected limb and in affected limb. For the affected hamstring, there were also significant differences in walking velocity, step per minute, stride and step length. Besides, it was found that the difference of the muscular strength between strong and weak group was at the highest.

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성별 및 연령에 따른 비음치 비교 (Age and Sex Differences in Nasalance Scores)

  • 김민정;임성은;최홍식
    • 대한후두음성언어의학회지
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    • 제11권2호
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    • pp.141-145
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    • 2000
  • Background and Objectives : The nasalance score measured by Nasometer is a supplementary data for the perceptually rated nasality by a trained speech pathologist. The nasalance score varies with subjects. The objective of the present study was to examine whether there are differences in nasalance scores as a function of age and sex. Materials and Method : This study used 20 normal chidren aged from 3 to 8 and 40 normal adults aged from 21 to 37(male : female= 1 : 1) as subjects. The nasalance scores were analyzed in 3 different phonetic contests(nasal, /i/ vowel,/a/ vowel) and 4 different sentence lengths(1, 2, 4, 8 syllable). Results : The children had significantly higher nasalance scores in short sentences an the adults. The female subjects had significantly higher nasalance scores in nasal sentences and in short sentences than the male subjects. Conclusion : These results may indicate that sex and age differences should be considered in the interpretation of the nasalance score in nasal sentences or in short sentences.

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시간영역 변위근사 유한차분법의 자유면 경계조건 (Free-surface Boundary Condition in Time-domain Elastic Wave Modeling Using Displacement-based Finite-difference Method)

  • 민동주;유해수
    • 지구물리와물리탐사
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    • 제6권2호
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    • pp.77-86
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    • 2003
  • 자유면 경계조건을 정착하게 묘사할 수 있는 변위근사 유한차분법을 이용하는 시간영역 탄성파 모델링법을 고안하였다. 기존의 변위근사 유한차분법의 경우 변위와 매질의 물성을 격자점에 정의하는 격자군(격자점 기반의 격자군)을 이용하였으나, 이 연구에서 제시하는 새로운 유한차분법에서는 변위는 격자점에 정의하지만 매질의 물성을 격자점으로 둘러싸인 면에 정의하는 격자군(셀 기반의 격자군)을 이용한다. 매질의 물성을 셀에 정의할 경우 자유면에서 응력이 사라진다는 자유면 경계조건을 추가로 적용할 필요가 없으며 매질의 물성 변화만으로 자유면 경계조건을 표현할 수 있다. 수치예를 통한 정확도 분석 결과 셀 기반의 격자군을 이용할 경우 계산된 수치석인 해가 해석적인 해에 매우 근사함을 알 수 있었다.

Gender Differences in Work-related Musculoskeletal Disorders among Agricultural Workers

  • Kim, Yu-Chang;Shin, Yong-Seok
    • 대한인간공학회지
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    • 제30권4호
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    • pp.535-540
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    • 2011
  • Objective: The aim of this paper is to survey the gender differences Work-related musculoskeletal disorders among agriculture workers. Background: The number of occupational injuries has been decreasing trend in Korea, but it has been increasing in agriculture. The ratio of women worker shows steady increasing trend among the agricultural worker in Korea. Method: This study investigated through the questionnaire to 358 agricultural workers who are working for agriculture located in Gyeongnam, Gyeongbuk and Jeju. Results: The task types occurring frequently and the weight of a heavy object handled according to the sex were showed statistically significant difference. The estimation of WMSDs patients by sex appeared statistically very significant difference. Conclusion: The prevalence rate of WMSDs in female was about 21 percent higher than the prevalence rate of WMSDs in male. Application: The result of this study will help improvement of work environment and prevention of WMSDs in agricultural work.

의복의 적절성이 대인지각에 미치는 영향에 관한 연구 -이화여대 학생의 캠퍼스 웨어를 중심으로- (The Effect of Clothing Appropriateness on Person Perception)

  • 박성은;임숙자
    • 한국의류학회지
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    • 제19권2호
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    • pp.264-277
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    • 1995
  • is designed to study the college women's desirable clothing behavior in campus, and to find out the difference in person perception according to appropriate or inappropriate clothing. Detailed object is to find out the following differences according to appropriate and inappropriate clothing in campus: 1) formation of impression 2) inference of value. Addi\ulcorner tionally the difference in person perception according to major, grade and preference group are studied. For data collection, 460 college women who are attending Ewha Woman's University are included, and convenience sampling method is used. Frequency, percentage, mean, factor analysis, t-test, ANDV A. duncan test, correspondent analysis are used for data analysis. The result are as follows: 1) Wearer's impression is devided into four factors: appearence evaluation, personality evaluation, ability and activity. 2) There are significant differences in impression formation and value inference according to situational appropriateness. 3) There are significant differences in person perception according to major, grade and preference group.

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