• Journal of the Korean Data and Information Science Society
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• 제8권2호
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• pp.119-125
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• 1997

We handle the stochastic processes of independent and identically distributed random variables. But random variables are usually dependent among themselves in actual life. So in this paper, we find out a new process not satisfying Markov property. We investigate the probability mass functions and study on the probability of the first-passage time. Also we find out the average frequency of continuous successes in from 0 to n time.

• 한국보육지원학회지
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• 제3권1호
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• pp.1-15
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• 2007

본 연구는 취업모의 직장환경과 양육시간을 알아보고, 그에 따른 일-어머니 역할갈등의 차이를 알아보는데 그 목적이 있다. 연구 대상은 서울 경기 지역에 소재한 어린이집을 통해 만 3-5세 영유아의 취업모 230명을 대상으로 설문하였다. 설문지는 아동을 통해 각 가정에 의뢰하여 어린이집에서 수거한 뒤 본 연구자가 취합하였다. 배부된 설문지 중에서 202부가 회수되었다. 연구의 목적을 달성하기 위해 t, F검증, 상관관계, 회귀분석을 실시하였으며 연구의 결과는 다음과 같다. 첫째, 취업모의 직장환경은 근무시간 융통성이 낮고, 비정규 근무가 높을수록 일-어머니 역할갈등이 높게 나타났으며 가족과 관련된 정책의 시행여부에 따라서는 일-어머니 역할갈등에 차이가 나타나지 않았다. 둘째, 취업모가 자녀와 함께하는 양육시간이 짧을수록 일-어머니 역할갈등이 높게 나타났다. 셋째, 취업모의 일-어머니 역할갈등과 직장환경, 양육시간은 서로 유의한 상관이 나타났다. 마지막으로, 취업모의 직장환경과 양육시간은 일-어머니 역할갈등에 영향을 미치는 것으로 나타났다.

• 한국조사연구학회지:조사연구
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• 제12권2호
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• pp.145-157
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• 2011

인터넷 조사에 가중치를 적용하여 그 일반성을 높이고자 하는 시도가 다양하게 이루어졌지만, 안정적으로 적용될 수 있는 방법이 아직까지 개발되지는 않았고 이것이 인터넷 조사의 활용을 제약하고 있다. 인터넷 조사를 위한 가중치 개발에는 준거조사 결과가 필요하지만, 센서스나 정부기관에서 제공되는 통계 중 일부 인구학적 속성을 제외하면 이러한 준거 조사 자료를 구하기 어렵다는 것이 중요 요인이다. 본 연구는 생활시간 조사를 이용해서 가중치를 개발하여 적용할 때, 인터넷 조사의 일반성을 높일 수 있는지를 검토해 보았다. 생활시간 조사는 정부기관에 의해 정기적으로 조사될 뿐만 아니라 센서스와는 달리 라이프스타일에 관련된 다양한 내용을 조사하기 때문이다. 2009년에 실시된 통계청 사회조사의 온라인 버전을 2004년 생활시간 조사결과를 이용해 가중치를 적용한 결과, 2009년에 동일한 설문지를 이용해 실시된 면접원방문 사회조사결과에 보다 일치하는 방향으로 작용하는 것으로 나타났다. 즉 생활시간 조사에서 나타난 취침 시간, 귀가시간, 인터넷 이용시간 등을 이용해서 가중치를 적용했을 때 단지 인구학적 속성만을 이용해서 가중치를 적용하는 경우보다, 온라인 조사결과와 오프라인 조사결과가 보다 근접해지는 경향이 있다는 것이다. 이러한 본 연구의 결과는 생활시간 조사자료가 인터넷 조사의 가중치 개발에 활용될 수 있다는 점을 보여준다.

• 수산경영론집
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• 제29권2호
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• pp.97-110
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• 1998

This paper tries to estimate Korea's import demand function for fisheries using cointegration analysis. The estimation function consists of one dependent variable-import quantity of fisheries(FTIW) and two independent variables-relative price(RP) between importable and domestic products and real income(GDP). As it has been empirically found out that almost all of time series of macro-variables such as GDP, price index are nonstationary, existing studies which ignore this fact need to be reexamined. Conventional econometric method can not analyze nonstationary time series in level. To perform the analysis, time series should be differenciated until stationarity is guaranteed. Unfortunately, the difference method removes the long run element of data, and so leads to difficulties of interpretation. But according to new developed econometric theory, cointegration approach could solve these problems. Therefore this paper proceeds the estimation on the basis of cointegration analysis, because the quartly variables from 1988 to 1997 used in the model is found out to be nonstationary. The estimation results show that all of the variables are statistically significant. Therefore Korea's import demand for fisheries has been strongly affected by the variation of real income and the relative price.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 하계학술대회 논문집
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• pp.555-558
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• 1991

The IESF(Integral Error and State Feedback) controller, which incorporates state feedback as a modern control scheme and integral action as a classical control scheme, has better performance than that of the conventional PID controller in linear time-invariant systems. The IESF controller requires the measurement of all the state variables. But, unfortunately, it may be difficult or impossible to measure all state variables in many applications. And the IESF controller is applicable only to pole-assignable linear time-invariant system without time delay. In this paper, new IESF controller structure was proposed which performs feedback with only measurable state variables. In order to estimate the unmeasurable state variables. It was adopted the filter mode by full-order obserber. The good performance and effectiveness of the proposed controller was confirmed by computer simulation.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 2004년도 춘계공동학술대회 논문집
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• pp.487-493
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• 2004

This paper consider a six sigma project for improving the TIP life time in a spot welding process. The project follows a disciplined process of five phases: define, measure, analyze, improve, and control. A process map is used to identify process input and output variables. Nine key process input variables are selected by using C&E matrix and FMEA, and finally four vital few input variables are selected from analyze phase. The optimum process conditions of the four vital few input variables are jointly obtained by maximizing TIP life time using DOE.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.36-39
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• 1996

In chemical processes, measurement errors reduce the credibility of information and cause inconsistency in material and energy balances. Because multicomposition flows and temperature measurements make material and energy balances nonlinear equations, data reconciliation becomes a nonlinear constrained optimization problem. In multicomposition processes, if we follow general optimization procedure, the number of measurement variables is so large that data reconciliation requires much computation time. We propose the decomposition procedure to reduce the computation time without the decrease of accuracy of data reconciliation. Decomposition procedure finds global variables, that can reduce the nonlinearity of constraints, and divides two sub-optimization problems. Once we optimize the global variables at upper level, we can easily optimize the remain variables at tower level, We can obtain the short computational time and the same accuracy as SQP optimization method.

• 천문학회보
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• 제37권1호
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• pp.58.1-58.1
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• 2012

We present a comprehensive re-analysis of stellar photometric variability in the field of open cluster M37, using our new high-precision light curves. This dataset provides a rare opportunity to explore different types of variability between short (-minutes) and long (-one month) time-scales. To investigate the variability properties of -30,000 objects, we developed new algorithms for detecting periodic, aperiodic, and sporadic variability in their light curves. About 7.5% (2,284) of the total sample exhibits convincing variations that are induced by flares, pulsations, eclipses, starspots and, in some cases, unknown causes. The benefits of our new photometry and analysis package are evident. The discovery rate of new variables is increased by 63% in comparison with the existing catalog of variables, and 51 previously identified variables were found to be false positives resulting from time-dependent systematic effects. Based on extended and improved catalog of variables, we will review the basic properties (e.g., periodicity, amplitude, type) of the variability and how different they are for different spectral types and for cluster memberships.

• 천문학회지
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• 제27권2호
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• pp.133-146
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• 1994

We have detected a SiO maser line (v=1, J=2- 1) for 15 stars out of about 80 long period variables in the wide range of period. No new sources are detected; all detected sources are variables with period longer than 300 days; no evidence is found that the dust grains in the outer envelope have influenced on this line. The time variation of this maser line for 7 stars, T Cep, ${\mu} Cep$, U Her, R Leo, R Lmi, U Ori, and R Ser is observed and compared with optical light curve at the same epoch of maser observation. No universial relation between the time variation and the optical light curve is found. It implies that the radiation from a central star does not much play an important role for the direct pumping of the SiO maser line.

• 가족자원경영과 정책
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• 제19권3호
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• pp.81-99
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• 2015

This study investigates the balance between work and family, and the happiness of married working women who have preschool-aged children. Data were collected from 321 questionnaires that consisted of three parts: 1) basic demographic variables, 2) family-life variables, and 3) working-life variables. SPSS 21.0 was used for the statistical analysis. The variables that were identified to have a statistically significant impact on the balance between work and family were income, age of first child, time spent on housework and childcare on weekdays, time spent on housework on weekends, family-friendly service in the workplace and flexibility of work schedule. 2) The variables that were identified to have a statistically significant impact on happiness were age, income, time spent on housework on weekends, satisfaction with spouse's participation in housework and childcare, average working time, family-fiendly service in the workplace, flexibility of work schedule, and balance between work and family. The majority of the variables that influence balance between work and family, and happiness related to aspects of work, such as family-fiendly service, flexibility of work schedules, and average working time. The results also found that the load of housework and childcare on weekends is a heavy burden for working women. Further research needs to focus on developing the extending index of happiness including the measure of balance between work and life. In addition, further studies with more varied groups need to be conducted.