• Clinical and Experimental Pediatrics
• /
• 제49권5호
• /
• pp.482-488
• /
• 2006

목 적 : 신생아의 첫 태변 및 초뇨 배출 시간은 건강 상태의 양호한 정도를 나타내는 표지이다. 첫 태변 배출 시간과 초뇨 배출 시간에 영향을 미칠 수 있는 여러 인자들에 대해 조사하고 이를 비교 평가 분석함으로써 그 임상적 의의를 비교 관찰하였다. 방 법 : 2004년 11월부터 2005년 4월까지 본원에서 분만된 재태 연령 34주 이상의 신생아 1,221명을 대상으로 하였다. 모체의 인구학적 변수(모체 연령, 분만력, 분만 방법, 양수의 태변 착색 여부, 그리고 모체 당뇨 여부)와 영아의 변수(성별, Apgar 점수, 재태 연령, 출생 체중, 첫 24시간 동안의 수유 유형, 첫 수유 시 연령, 출생 후 12시간까지 수유 횟수, 퇴원 시 연령, 첫 번째 배뇨 시 연령, 첫 번째 태변 배출 시 연령)에 따른 태변 배출 및 초뇨 배출 시간을 비교 분석하였다. 결 과 : 본 연구에서, 58.8%가 12시간 이전에, 95.3%가 24시간 이전에, 99.8%가 36시간 이전에 초뇨가 배출되었다. 그리고 68.3%가 12시간 이전에, 95.8%가 24시간 이전에, 98.3%가 36시간 이전에 태변이 배출되었다. 미숙아와 만삭아를 비교하였을 때 초뇨 배출시 연령은 각각 $6.5{\pm}5.8$시간, $12.1{\pm}6.6$시간이었고(P=0.000), 첫 태변 배출시 연령은 각각 $20.7{\pm}13.5$시간, $10.0{\pm}6.3$시간(P=0.000)으로 미숙아의 경우에 초뇨가 더 빨리 배출되고 태변이 더 늦게 배출되는 경향을 나타냈다. 수유를 빨리 시작한 경우에 초뇨나 첫 태변 배출 시간이 통계학적으로 유의하게 더 빨랐다. 출생 후 첫 12시간 동안의 수유 횟수는 초뇨 배출 시간과는 큰 상관이 없었다(P=0.778). 수유 횟수가 많을수록 24시간 이내에 첫 태변을 배출한 영아가 더 많았으며 이는 통계학적으로 유의하였다(P=0.000). 분만 방법(질식 분만, 수술 분만), Apgar 점수, 출산력, 성별, 수유 유형, 모체 당뇨 여부 등은 초뇨 배출 및 첫 태변 배출시 연령과는 통계학적으로 유의성은 없었다. 결 론 : 재태 연령, 출생 체중, 초기 수유 시작 시간이 초뇨 및 첫 태변 배출 시간과 연관성이 있는 것으로 보여지며, 초뇨 및 태변 배출의 지연을 보일 경우 동반되는 이상 증상의 유무에 대한 면밀한 관찰 외에도 상기 요소들에 대한 사항을 고려하여 성급하고 불필요한 임상 검사 및 치료는 피해야 할 것으로 사료된다.

• 대한수학회보
• /
• 제50권5호
• /
• pp.1659-1671
• /
• 2013

In this paper, we are concerned with the analysis of the waiting time distribution in the M/M/m retrial queue. We give expressions for the Laplace-Stieltjes transform (LST) of the waiting time distribution and then provide a numerical algorithm for calculating the LST of the waiting time distribution. Numerical inversion of the LSTs is used to calculate the waiting time distribution. Numerical results are presented to illustrate our results.

• Bulletin of the Korean Chemical Society
• /
• 제19권10호
• /
• pp.1068-1072
• /
• 1998

We present results of molecular dynamic (MD) simulations for the segmental motion of liquid n-butane as the base case for a consistent study for conformational transition from one rotational isomeric state to another in long chains of liquid n-alkanes. The behavior of the hazard plots for n-butane obtained from our MD simulations are compared with that for n-butane of Brownian dynamics study. The MD results for the conformational transition of n-butane by a Poisson process form the total first passage times are different from those from the separate t-g and g-t first passage times. This poor agreement is probably due to the failure of the detailed balance between the fractions of trans and gauche. The enhancement of the transitions t-g and g-t at short time regions are also discussed.

• Smart Structures and Systems
• /
• 제2권4호
• /
• pp.313-320
• /
• 2006

The reliability analysis of structures subjected to stochastic loading involves evaluation of time and probability of the system's residence in a reference domain. In this paper, we derive an asymptotic estimate of exit time for multi-degrees-of-freedom structural systems. The system's dynamics is governed by the Lagrangian equations with linear dissipation and fast additive noise. The logarithmic asymptotic of exit time is found explicitly as a sum of two terms dependent on kinetic and potential energy of the system, respectively. As an example, we estimate exit time and an associated structural performance for a rocking structure.

• 한국경영과학회지
• /
• 제19권3호
• /
• pp.93-109
• /
• 1994

Even though sojourn time distributions are essential information in analyzing queueing networks, there are few methods to compute them accurately in non-product form queueing networks. In this study, we model the location process of a typical customer as a GMPH semi-Markov chain and develop computationally useful formula for the transition function and the first-passage time distribution in the GMPH semi-Markov chain. We use the formula to develop an effcient method for approximating sojourn time distributions in the non-product form queueing networks under quite general situation. We demonstrate its validity through numerical examples.

• 대한기계학회논문집B
• /
• 제20권9호
• /
• pp.3015-3029
• /
• 1996

The notion of effective transport property of a heterogeneous medium implies that the medium is large enough that the ergodic theorem holds and local fluctuation of the property can be neglected. In case that the medium is not large enough compared to its characteristic microstructure length scale, the effective property fluctuates and differs from the value of the medium being large enough. As a representative transport phenomenon, diffusion was considered and the fluctuation of varying effective diffusion property, diffusion coarseness $C_k$, was defined as a quantifying parameter. Scaled effective diffusion property, $^*$>/k$_1$ and $C_k$ were computed for the two phase random media consisting of matrix of diffusion coefficient k$_1$ and spheres of diffusion coefficient k$_2$. Numerical simulations were performed by use of the so-called first passage time technique and data were collected for existing microstructure models of hard spheres(HS), overlapping spheres(OS) and penetrable concentric shells(PCS).

• 국토계획
• /
• 제53권7호
• /
• pp.5-22
• /
• 2018

While the competitiveness of small and medium sized cities has become important for balanced development at the national scale, they have experienced continuous decline in population and employment, particularly those in non-capital regions. In addition, some of small and medium sized cities have been classified into shrinking cities that have declined due to their long-term structural reasons. To address these issues, a regional approach, by which a hub city and its surrounding small and medium sized cities can collaborate has been suggested. Given this background, the purpose of this study is to identify and delineate hub cities and their impact areas by using travel data as a functional network index. This study uses a centrality index to identify the hub cities of small and medium sized cities and Markov-chain model and cluster analysis to delineate regional boundaries. The mean first passage time (MFPT) generated from the Markov-chain model can be interpreted as functional distance of each region. The study suggests a methodological approach delineating the boundaries of regions incorporating functional relationships of hub cities and their impact areas, and provides 59 hub cities and their impact areas. The results also provide policy implications for regional spatial planning that addresses appropriate planning boundaries of regions for enhancing the economic competitiveness of small and medium sized cities and ensuring services for shrinking cities.

• International Journal of Human Ecology
• /
• 제14권1호
• /
• pp.29-39
• /
• 2013

The study examined how changes in time invested in private tutoring and academic achievement influenced each other through a multivariate latent growth model by using the data from the first to the third year presented in the KYPS. This study identifies not only how changes in the private tutoring experience exerted a direct influence on changes in academic achievement, but also measures what kind of changes in private tutoring and academic achievement had emerged over time. The detailed study results are as follows. First, the analysis of time invested in private tutoring showed that the higher the grades, the greater were the amount of time invested in private tutoring in the case of Korean language study. On the other hand, the results showed that in the case of English and mathematics, the higher the grades, the lesser was the amount of time invested in private tutoring. Second, private tutoring and academic achievement were all in a linear relationship. Third, it was shown that the time invested in private tutoring and academic achievement exerted a negative influence on each other according to the passage of time.

• 한국주거학회논문집
• /
• 제20권4호
• /
• pp.113-120
• /
• 2009

The demands of residents can be predicted by analyzing the housing viewpoint of residents. And also, the housing viewpoint can change according to various environmental changes, so it's important for us to understand the trend of change. Therefore, the housing viewpoints of university students who will be subjective residents of houses in future were analyzed by observing change due to trend of time. Target for this study is female university students in 20s. A portion of previously presented material (Korean Home Economics Association 37,1, 67-78) was used as data for 1998 and a questionnaire with 171 female university students was conducted on December 2008 for data for 2008. The following result was drawn from examination of change in the housing viewpoint due to trend of time by comparing the housing viewpoint of university students between 1998 and 2008. First, importance of was decreased and importance of was increased in functions of residence. Second, regardless of the time passage, the most students thought and as their opinions on housing. And also, the most students considered a living room as the most important space inside of a house regardless of the time passage and the level of considering a living room as the most important space was more increased. Third, the level of consideration got higher with time in the selection of houses. , , , , , and had higher level of consideration regardless of time passage. Items of which level of consideration increased with time are , , , , , and , and items of which level of consideration decreased are and . Fourth, it can be understood that the level of satisfaction in housing got higher with time. And it can be said that , , , and were not increased in the level of satisfaction in housing compared with 10 years ago. Fifth, regardless of time passage, the level of satisfaction in housing was lower than the level of consideration in the event of selection of houses. As , , and had lower levels of satisfaction in the event of selection of houses compared with the levels of consideration, they have higher possibility of dissatisfaction in housing.

• International Journal of Reliability and Applications
• /
• 제9권2호
• /
• pp.167-182
• /
• 2008

The objective of this paper is to discuss the stochastic analysis and the statistical inference of a three-states semi-Markov reliability model. Using the maximum likelihood procedure, the parameters included in this model are estimated. Based on the assumption that the lifetime and repair time of the system are gener-alized Weibull random variables, the reliability function of this system is obtained. Then, the distribution of the first passage time of this system is derived. Many important special cases are discussed. Finally, the obtained results are compared with those available in the literature.