• Communications for Statistical Applications and Methods
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• 제25권1호
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• pp.29-42
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• 2018

We combine the integer-valued GARCH(1, 1) model with a generalized regime-switching model to propose a dynamic count time series model. Our model adopts Markov-chains with time-varying dependent transition probabilities to model dynamic count time series called the generalized regime-switching integer-valued GARCH(1, 1) (GRS-INGARCH(1, 1)) models. We derive a recursive formula of the conditional probability of the regime in the Markov-chain given the past information, in terms of transition probabilities of the Markov-chain and the Poisson parameters of the INGARCH(1, 1) process. In addition, we also study the forecasting of the Poisson parameter as well as the cumulative impulse response function of the model, which is a measure for the persistence of volatility. A Monte-Carlo simulation is conducted to see the performances of volatility forecasting and behaviors of cumulative impulse response coefficients as well as conditional maximum likelihood estimation; consequently, a real data application is given.

• 한국전산구조공학회논문집
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• 제17권3호
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• pp.225-239
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• 2004

이 논문에서는 철근콘크리트 골조 구조물의 시공 시 작용하는 사하중, 활하중, 시공하중 등의 하중에 대한 지지 및 안전한 시공을 위해 설치되는 지지시스템에 대하여 보다 체계적인 분석이 이루어졌다. 지지시스템의 종류, 비계의 강성과 간격 등의 변화에 따른 구조물의 거동특성을 비교, 분석하였고, 기존의 설계규준 및 해석방법과의 비교를 위해 크리프 등의 시간의존적 거동을 고려한 경우와 괴려하지 않은 경우에 대하여 해석이 수행되었으며, 나무 비계를 사용한 경우와 강재 비계를 사용한 경우에 대한 비교 검토가 이루어졌다. 또한, 대표적인 3-경간 구조물에 대한 해석을 수행하여 내측 기둥과 외측 기둥의 부등축소에 따른 영향을 반영한 검토가 이루어졌다. 나아가 다양한 설계인자의 변화에 따른 거동분석을 통해 2SlR 지지시스템이 가장 효율적임을 제시하였다.

• The Korean Journal of Ceramics
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• 제2권2호
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• pp.95-101
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• 1996

Variations of the leakage current behaviors and interface potential barrier $({\Phi}_B)$ of rf-sputter deposited (Ba, Sr)$TiO_3$ (BST) thin films with thicknesses ranging from 20 nm to 150nm are investigated as a function of the thickness and bias voltages. The top and bottom electrodes are dc-sputter-deposited Pt films. ${\Phi}_B$ critically depends on the BST film deposition temperature, postannealing atmosphere and time after the annealing. The postannealing under $N_2$ atmosphere results in a high interface potential barrier height and low leakage current. Maintaining the BST capacitor in air for a long time reduces the ${\Phi}_B$ from about 2.4 eV to 1.6 eV due to the oxidation. ${\Phi}_B$ is not so dependent on the film thickness in this experimental range. The leakage conduction mechanism is very dependent on the BST film thickness; the 20 nm thick film shows tunneling current, 30 and 40 nm thick films show Shottky emission current.

• 터널과지하공간
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• 제20권5호
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• pp.390-398
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• 2010

암석의 시간의존성 거동은 지하 광산 설계나 지하 암반구조물의 장기 안정성 평가를 위한 기본 입력자료로써 사용되는 매우 중요한 특성이다. 본 연구에서는 가곡광산에서 채취한 화강암 시험편에 대해 일축압축 크리프시험을 실시하였다. 측정된 크리프 변형률을 모사하기 위하여 Burgers 모형, Griggs 크리프법칙, Singh 크리프법칙을 사용하였으며 이중에서 Griggs 크리프법칙이 가곡광산 화강암의 실제 크리프 변형 거동을 가장 우수하게 모사하는 것으로 나타났다.

• 여성건강간호학회지
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• 제4권3호
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• pp.322-331
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• 1998

The postpartum is a period of transition to motherhood where a childless woman transforms into a woman with children. Parents, especially mothers must perform an essential role of implementing instrumental and emotional care behaviors on part of the helpless, dependent, and immature infant. First-time mothers, however, suddenly face the responsibility of round the clock duty without neither parenting training during pregnancy, nor a time to gradually adapt to growing responsibilities after birth, with confusion and frustration as a result. Thus, after providing first-time mothers with childcare education as maternal role preparation, this study will try to examine its effects on childcare behaviors and confidence in maternal role during the early postpartum period. This quasi-experimental study using a nonequivalent control group non-synchronized design, was carried out from March 1995 to May 1996 to verify the effects of a childcare education program with first-time mothers who had vaginal delivery in Ewha University Hospital, Seoul, Korea, and collected data from 60 subjects who consented to the study. The education was given in the early postpartum period(48-72 hours after delivery) and to measure its effects, a posttest was done 4 weeks later with the results analyzed by SPSS shown in the following : 1. The childcare behavior score of the experimental group that had received the newborn care education was higher than the control group(t=3.5, P=.001). 2. The control group and the experimental group which had received the education showed no difference in degree of confidence in maternal role. 3. The higher the childcare behavior score, the higher the degree of confidence in maternal role was among the subjects(r=.56, P=.001). The preceding results are significant in that childcare practices can be promoted by providing child-care education to first-time mothers in the early postpartum period. Thus, this education can be used as a nursing intervention strategy in the early postpartum period.

• 대한토목학회논문집
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• 제42권2호
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• pp.151-162
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• 2022

스마트 건설 기술의 도입으로 공장에서 일괄 대량생산이 가능한 프리팹 부재에 대한 관심이 높아졌다. 프리팹 프리스트레스 콘크리트 거더는 가설시 프리팹 바닥판과의 정합성을 위해 제작부터 가설 전 단계까지 거더의 형상관리가 중요하다. 이 연구에서는 프리팹 거더의 상연 및 하연에 병치된 변형률 측정치를 이용한 캠버 재구성 기법을 제시한다. 특히, 긴장력 도입 이후 가설 전까지 콘크리트의 시간 의존적 거동이 고려된 변형률 데이터에 대해 캠버 재구성 기법을 적용한다. 몬테카를로 수치 모사를 통해 제한된 센서의 개수, 계측 오차 그리고 비선형적 시간 의존적 거동들에 대해 재구성된 캠버의 통계적 정확도를 분석하고 타당성을 검증한다.

• Structural Engineering and Mechanics
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• 제57권3호
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• pp.425-439
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• 2016

This paper deals with the behavior of fresh concrete that is under vibration using mass-spring model (MSM). To this end, behaviors of two different full scale precast concrete molds were investigated experimentally and theoretically. Experiments were performed under vibration with the use of a computer-based data acquisition system. Transducers were used to measure time-dependent lateral displacements at some points on mold while mold is empty and full of fresh concrete. Analytical modeling of molds used in experiments were prepared by three dimensional finite element method (3D FEM) using software. Modeling of full mold, using MSM, was made to solve the problem of dynamic interaction between fresh concrete and mold. Numerical displacement histories obtained from time history analysis were compared with experimental results. The comparisons show that the measured and computed results are compatible.

• 설비공학논문집
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• 제12권10호
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• pp.908-916
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• 2000

In this paper, the characteristics of moisture ventilation in the lithium ion battery manufacturing dry room are studied numerically using standard $k-\varepsilon$ turbulence model. Both the steady-state and the unsteady behaviors of moisture ventilation are analyzed by considering local and uniform moisture generation. In order to evaluate the characteristics of moisture ventilation, three scales of ventilation efficiency and characteristic ventilation time are presented from the numerical results. It was shown that moisture distribution was dependent strongly on the flow field. The characteristics of moisture ventilation were improved by 20% and 40% in terms of the 1st scale of ventilation efficiency (SVE1) and the 2nd scale of ventilation efficiency (SVE2), respectively, through the modifications of design variables such as the addition of inlets, outlets and partition. A significant improvement in the characteristic ventilation time and the moisture exhaust efficiency was also made by these modifications.

• Steel and Composite Structures
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• 제25권2호
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• pp.187-196
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• 2017

In this work, transient thermo-piezo-elastic responses of an infinite functionally graded piezoelectric (FGPE) plate whose upper surface suffers time-dependent thermal shock are investigated in the context of different thermo-piezo-elastic theories. The thermal and mechanical properties of functionally graded piezoelectric plate under consideration are expressed as power functions of plate thickness variable. The solution of problem is obtained by solving the corresponding finite element governing equations in time domain directly. Transient thermo-piezo-elastic responses of the FGPE plate, including temperature, stress, displacement, electric intensity and electric potential are presented graphically and analyzed carefully to show multi-field coupling behaviors between them. In addition, the effects of functionally graded parameters on transient thermo-piezo-elastic responses are also investigated to provide a theoretical basis for the application of the FGPE materials.

• 한국심리학회지 : 코칭
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• 제5권1호
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• pp.1-32
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• 2021

본 연구의 목적은 습관행동 변화과정 모형(탁진국, 권혜란, 김혜영 등, 2019)을 기반으로 하여, 식습관 개선 성공 요인(최경화, 김혜영, 한석빈, 탁진국, 2020)과 선행 연구에서 습관 개선에 효과를 나타낸 방법들을 토대로 식습관 개선을 위한 온라인 코칭 프로그램을 개발하여 실시하고, 그 효과를 검증하는 데 있다. 식습관 개선을 희망하며 수도권에 거주 중인 19세 이상 성인 중 전화인터뷰를 통해 선정된 20명을 실험 및 통제집단으로 나누어 일대일 코칭을 진행하였다. 최종분석에는 17명의 자료가 사용되었으며, 프로그램 사전과 사후에 체중, 식습관, 식이행동, 식이효능감, 자기조절, 삶의 만족을 측정하여 분석하였다. 온라인 코칭프로그램의 효과성을 검증하기 위하여 프로그램 실시 사전, 사후의 시점과 집단 간의 상호작용효과를 분석한 결과, 자기조절과 삶의 만족을 제외한 체중, 식습관, 식이행동, 식이효능감에서 시점과 집단 간에 유의미한 결과가 나타나 프로그램 효과가 검증되었다. 즉, 통제집단에 비하여 실험집단에서 체중, 식습관, 식이행동, 식이효능감에서 유의미한 변화가 있었다. 이상의 연구 결과를 중심으로 본 연구의 의의 및 실무적 시사점, 제한점, 그리고 후속 연구를 위한 제언 등에 관해 논의하였다.