• 한국신뢰성학회지:신뢰성응용연구
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• 제6권3호
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• pp.225-237
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• 2006

This paper proposes a method of modelling the informative dropouts with QoL(quality of life) in survival analysis. QoL is the index to measure the health related quality of life of a patient who got some treatments for a disease. Dropouts are prevalent occurrences on longitudinal study They are commonly dependent to the QoL of patients, that is, severe disease or death and called informative dropouts. Modelling the mechanism of dropouts could achieve the more accurate inference for survival analysis. A likelihood method is proposed to estimate the survival parameter and test the patterns of dropouts.

• Communications for Statistical Applications and Methods
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• 제9권3호
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• pp.703-713
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• 2002

In longitudinal studies, outcomes are repeatedly measured over time for each subject. It is common to have missing values or dropouts for longitudinal data. In this study time trend in longitudinal data with dropouts is of concern. The confounding of time trend with dropout process is investigated through simulation studies. Some simulation results are reported for binary responses as well as continuous responses with patterns of dropouts varying. It has been found that time trend is not confounded with random dropout process for binary responses when it is estimated using GEE.

• E2M - 전기 전자와 첨단 소재
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• 제8권5호
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• pp.633-639
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• 1995

Dropouts in magnetic media are a primary quality deficiency which is detrimental to magnetic signal quality and thus the major impediment to error-free recording, especially in high density digital recorders. The specific form of defects and causes found to be responsible for signal dropouts occurring in magnetic tape were studied. Dropout occurred when the RF signal falls to low level due to the various types of surface defects. However, the fall in the level of the RF signal in gravure roll coated tapes was most often caused by foreign particles adhering to the magnetic tape. It was also shown from the present study that scattered particles trapped under the tape surface or put on the top can lift it as it crosses the head, creating a spherical tent shaped defect and causing a temporary signal drop. Dropout producing substances were identified through optical and microchemical analyses. The results were correlated with measured electrical signal losses combined with analytical microscopy to clarify source identification of defects.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.1731_1732
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• 2009

This paper presents a stability analysis of networked control systems with packet dropouts. The packet dropouts are modeled as a linear function of the stochastic variable satisfying Bernoulli random binary distribution and weighted moving average (WMA). The observer based controller scheme is designed to exponentially mean square stabilize the NCS. Simulation results is provided to show the applicability of the proposed method.

• Communications for Statistical Applications and Methods
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• 제15권3호
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• pp.353-365
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• 2008

임상시험에서 피험자수는 검정가설, 변수값의 분산과 유효차이, 검정력과 유의수준 등에 의해 결정되어진다. 일반적으로 수학적으로 계산된 피험자수에 중도탈락 예상치를 고려한 피험자수를 추가하여 최종적인 실험참가자수를 결정하는데 본 논문에서는 이론적인 계산식에서부터 중도탈락을 고려하여 피험자수를 결정하는 방법을 제안한다. 임상시험에서 많은 자료는 경시적(longitudinal) 형태를 갖고, ITT(intention to treat) 실험의 경우 중도탈락이 생기면 결측값으로 처리하지 않고 탈락직전에 관측된 값을 최종값으로 대체하는 LOCF(last observation carried forward) 방법을 주로 사용한다. 이러한 LOCF 방법은 피험자수 계산에 사용했던 분산과 유효차이 값의 가정에 왜곡을 가져오기 때문에 우리가 원하는 검정력을 보장 받지 못할 수 있다. 본 연구에서는 중도탈락률에 관한 정보를 포함하는 피험자수의 결정식을 제안하고 평균의 동일성 검정 경우에 검정력을 비교하여 이러한 산출방식이 합리적임을 실증하였다.

• 한국정보컨버전스학회:학술대회논문집
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• 한국정보컨버전스학회 2008년도 International conference on information convergence
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• pp.89-92
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• 2008

This study analyzed the status and causes for the dropouts of college based on the survey conducted among 14,210 freshmen attending D College, other than the supernumerary special selection, from 2001 through 2005. A significant difference was shown in all items of general characteristics. The dropout rate of women, generally selected and general high school graduated were higher than for men, specially selected and special high school graduated, respectively. The most dropouts were due to Not Return(40.16%), followed by Unenrolled(32.98%), Voluntary Leave(26.05%) and Expelled(0.81%) in order. In the distribution of the central tendency values measured from the entire subjects. the high school records and the days of absence showed a positive skewness. while the college records showed a negative skewness with the data mostly around a higher grade. The standard deviation indicating that the dropouts got the scores higher than those of the continuing students demonstrated that there was relatively insignificant difference in scores between two groups.

• 패션비즈니스
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• 제14권1호
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• pp.184-197
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• 2010

This study was conducted by the questionnaires to 323 undergraduate students in fashion related departments. Questionnaires were designed to ask total 23 questions including possibility of halfway dropouts, establishment of goals, self-improvement, entrance motives, satisfaction ratings of academic subjects, job prospects and path planning, amelioration of ways to instruct, desires for the integrated lessons and intense academic courses, wishes of field project education carrying out tasks, desired lecturers, and others. Results in this research were summarized as follows. To begin with, it was appeared that respondents with possibility of halfway dropouts showed considerable percentage (25.4%) and the reasons left out were various including joining the army, the poor economic conditions in family, a major not corresponding with one's aptitude. Secondly, in the extent of establishing goals and improving oneself, there was the difference between people with possibility of halfway dropouts and people without that, and it was judged that the extent of establishing goals and improving oneself as good parameters could explain halfway omission. Thirdly, the ways to teach for getting classes interesting were to make instruction according to one's capabilities, to progress systematically, and to take lessons with specific goals. Fourth, many respondents answered to want the integrated lessons, intense academic courses, and field project education carrying out tasks. Fifth, an overwhelming majority of respondents hoped instructors with a outstanding ability in business. For improvement of the ways to instruct and the role of professors, it is suggested as follows. First, students are given intelligible lessons focused on fundamental subjects fitted to their levels and also need gradual intense academic courses classified by their way directions and interests. Second, creative and individualized teaching methods depending on the majors and levels are developed to help students have strong interest in schoolwork. Third, professors are constantly to learn practical techniques and skills related to industries in step with the education goals of college. Fourth, it is desirable to adopt instructors with practical business talents rather than theoretical capabilities.

• 한국정보컨버전스학회논문지
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• 제1권1호
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• pp.47-54
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• 2008

본 연구는 대학생의 중도탈락에 대한 현황과 요인을 분석한 연구로서 D대학의 2001년부터 2005년에 입학한 학생 중에서 정원 외 전형으로 입학한 학생을 제외한 14,210명을 대상으로 하였다. 일반적 특성의 모든 항목에서 유의한 차이가 있는 것으로 나타났으며, 남학생이 여학생보다, 특별전형으로 입학한 학생이 일반전형으로 입학한 학생보다, 기타계열의 고교 출신자가 일반계 고등학교 졸업자보다 중도탈락률이 높게 나타났다. 중도탈락 학생들에 대한 분석에서는 미복학(40.16%)으로 인한 중도탈락이 가장 많았으며 다음으로 미등록(32.98%), 자퇴(25.05%), 학사제적(0.81%)으로 인한 중도탈락 순이었다. 전체 대상자의 중심경향 값에 따른 분포를 보면 학생부 성적과 결석일수는 정적편포이며 대학 성적은 부적편포로 낮은 점수를 받은 학생은 일부이고 대부분 높은 점수가 집중된 경향임을 나타내었다. 표준편차를 보면 학업지속자 보다 중도탈락자의 성적이 크게 나타나 비교적 학업지속자의 성적이 비슷한 것으로 보여 학생부성적과 결석일수 모두가 중도탈락에 영향을 미치는 것으로 나타났으며, 학생부성적이 낮을수록, 결석일수가 많을수록 중도탈락에 더 많은 영향을 미침을 알 수 있다. 대학 1학년1학기 성적을 제외한 나머지 성적이 낮을수록 중도탈락에 더 많은 영향을 미침을 알 수 있었고, 1학년 전체 성적이 제일 많은 영향을 미치고 다음이 1-2학기학점, 1-1학기 성적, 1-2학기성적, 그리고 1-1학기 학점 순으로 영향을 미치는 것으로 나타났다. 일반적 특성 항목에서는 수업년한이 제일 큰 영향을 미치고 다음이 성별이 미치며 나머지 항목들은 영향의 수준이 미미한 것으로 나타났다.

• 아동학회지
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• 제30권6호
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• pp.391-403
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• 2009

This study examined the concept and status, research issues, and pragmatic and policy issues of school-dropout adolescents. As the number of school-dropout adolescents has been increasing in Korea since 2006, more attentions have been given to these adolescents academically, intervention and policy-wise. Some of the research topics on them include types of school-dropouts, their socio-environmental factors, and reasons for the increase of school-dropouts. In reality, the government is required to provide them with opportunities to cope with their dropping out of schools by preparing the career guidance for them and to resolve the issues of their returning to or continuing in school education and their welfare.

• Asian Pacific Journal of Cancer Prevention
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• 제13권12호
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• pp.5989-5994
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• 2012

Background: There is little information on longitudinal patterns of participation in faecal occult blood test (FOBT) based colorectal cancer (CRC) screening or on demographic or behavioural factors associated with participation in re-screening. The lack of an agreed system for describing participatory behaviour over multiple rounds also hampers our ability to report, understand and make use of observed associations. Our aims were to develop a system for describing patterns of participatory behaviour in FOBT-based CRC screening programs and to identify factors associated with particular behavioural patterns. Methods: A descriptive framework was developed and applied to a data extract of screening invitation outcomes over two rounds of the NBCSP. The proportion of invitees in each behaviour category was determined and associations between behaviour patterns and demographic and program factors were identified using multivariate analyses. Results: We considered Re-Participants, Dropouts, Late Entrants and Never Participants to be the most appropriate labels for the four possible observed participatory categories after two invitation rounds. The screening participation rate of the South Australian cohort of the NBCSP remained stable over two rounds at 51%, with second round Dropouts (10.3%) being balanced by Late Entrants (10.5%). Non-Participants comprised 38.7% of invitees. Relative to Re-Participants, Dropouts were older, more likely to be female, of lower SES, had changed their place of residence between offers had a positive test result in the first round. Late Entrants tended to be in the youngest age band. Conclusions: Specific demographic characteristics are associated with behavioural sub-groups defined by responses to 2 offers of CRC screening. Targeted group-specific strategies could reduce dropout behaviour or encourage those who declined the first invitation to participate in the second round. It will be important to keep first round participants engaged in order to maximise the benefit of a CRC screening program.