• Ocean Systems Engineering
• /
• 제6권1호
• /
• pp.99-115
• /
• 2016

In meeting the technical needs for deepwater conditions and overcoming the shortfalls of single-layer pipes for deepwater applications, pipe-in-pipe (PIP) systems have been developed. While, for PIP pipelines directly laid on the seabed or with partial embedment, one of the primary service risks is lateral buckling. The critical axial force is a key factor governing the global lateral buckling response that has been paid much more attention. It is influenced by global imperfections, submerged weight, stiffness, pipe-soil interaction characteristics, et al. In this study, Finite Element Models for imperfect PIP systems are established on the basis of 3D beam element and tube-to-tube element in Abaqus. A parameter study was conducted to investigate the effects of these parameters on the critical axial force and post-buckling forms. These parameters include structural parameters such as imperfections, clearance, and bulkhead spacing, pipe/soil interaction parameter, for instance, axial and lateral friction properties between pipeline and seabed, and load parameter submerged weight. Python as a programming language is been used to realize parametric modeling in Abaqus. Some conclusions are obtained which can provide a guide for the design of PIP pipelines.

• Child Health Nursing Research
• /
• 제22권3호
• /
• pp.182-189
• /
• 2016

Purpose: The purpose of this study was to identify effects of parenting stress in North Korean refugee fathers on their parenting behavior. Methods: A descriptive study design was used. Data were collected during 2014 and 2015 in a settlement support center for North Korean refugees and 99 North Korean refugee fathers participated. Data were analyzed using SPSS 21.0. Results: Warmth encouragement parenting behavior received the highest score. The score for parenting stress was 81.98 out of 180, and 32.3% of participants were found to need professional help (${\geq}PSI\;90$). There were significant negative correlations between warmth encouragement parenting behavior and parenting stress. There were also significant positive correlations between rejection neglect parenting behavior and parenting stress. Predictors of warmth encouragement behavior were parent-child dysfunctional interaction which explained 10.1% of the variance. Predictors of rejection neglect behavior were parent-child dysfunctional interaction, number of children and wife's education level which explained 33.4% of the variance. Conclusion: Findings show that North Korean refugee fathers' parenting stress significantly influenced warmth encouragement and rejection neglect parenting behavior indicating a need to identify ways to decrease parenting stress. Parenting education can guide North Korean refugee fathers to strengthen parent-child positive interactions and therefore promote their children's growth and development.

• Steel and Composite Structures
• /
• 제46권4호
• /
• pp.577-589
• /
• 2023

In this study, on-site testing was carried out to investigate the vibration performance of a cold-formed thin-walled steel floor system. Ambient vibration, walking excitation (single and double persons), and impulsive excitation (heel-drop and jumping) were considered to capture the primary vibration parameters (natural frequencies, damping ratios, and mode shapes) and vertical acceleration response. Meanwhile, to discuss the influence of cement fiberboard on structural vibration, the primary vibration parameters were compared between the systems with and without the installation of cement fiberboard. Based on the experimental analysis, the cold-formed thin-walled steel floor possesses high frequency (> 10 Hz) and damping (> 2%); the installed cement fiberboard mainly increases the mass of floor system without effectively increasing the floor stiffness and may reduce the effects of primary vibration parameters on acceleration response; and the human-structure interaction should be considered when analyzing the vibration serviceability. The comparison of the experimental results with those in the AISC Design Guide indicates that the cold-formed thin-walled steel floor exhibits acceptable vibration serviceability. A crest factor 𝛽_rp (ratio of peak to root-mean-square accelerations) is proposed to determine the root-mean-square acceleration for convenience.

• 대한기계학회논문집 C: 기술과 교육
• /
• 제5권2호
• /
• pp.127-134
• /
• 2017

원자로내부구조물은 다양한 진동하중조건에서 안전성과 건전성을 유지해야한다. 그러므로 미국원자력규제 위원회는 펌프 압력 맥동에 의한 진동을 포함하여 음향으로 유발되는 진동을 평가하기 위한 규제지침서 1.20을 제시하고 있다. 본 논문은 음향-구조 연성해석 기법을 사용하여 펌프 맥동 가진으로 인한 해석을 위해 노심지지배럴 주변의 유체와 구조의 연성을 고려하여 해석하는 방법론을 제안하였다. 해석결과는 미국 Palo Verde 1호기 종합진동평가 프로그램 발전소 시험결과와 잘 일치한다. 따라서 제안된 해석 방법론은 펌프 압력맥동에 대한 노심지지배럴의 구조응답을 평가하기 위한 효과적 방법으로 판단된다.

• 한국가정과교육학회지
• /
• 제31권1호
• /
• pp.39-58
• /
• 2019

본 연구는 교육실습 동안 가정과 예비교사의 수업 상황에서 언어 상호작용을 분석하는 데 목적을 두었다. 4명의 가정과 예비교사를 대상으로 수업참여 관찰을 한 이후 녹화된 자료를 AF 분석을 활용하여 분석하였으며, 연구결과는 다음과 같다. 첫째, 가정과 예비교사의 언어 상호작용을 항목별로 살펴보면 교사의 '강의', '비언어적 상황', 교사의 '질문' 순으로 높게 나타났다. 학습자의 '긍정적인 학습 분위기 조성', '칭찬이나 격려' 항목에서는 빈도가 낮게 나타났으며 학습자에게 '지시' 혹은 '학생 비판이나 교사의 권위를 정당화'는 거의 이루어지지 않았다. 둘째, 수업 상호작용의 형태는 '교사의 질문-학생의 반응적인 발언' 혹은 '강의-질문'의 형태로 나타났으며 마지막 수업에서는 '교사의 질문-학생의 주도적인 발언', '강의-교사의 질문-칭찬이나 격려, 학생의 아이디어 수용 및 활용' 순으로 나타났다. 셋째, 수업에서 지수 경향은 전체적으로 비지시적인 경향을 띠며, 학습자의 발언에 허용적으로 나타났다. 교사의 질문비가 높고 첫 수업에서 학생의 발언비와 넓은 답변비는 낮게 나타났으나 마지막 수업에서는 높게 나타났다. 넷째, 전문가 분석에서 수업 운영에 대한 질문과 확산형 질문이 증가하였으며 교사는 학생들의 학습활동을 안내하고 학생들은 교사의 질문에 대하여 확산적인 사고를 하는 것으로 나타났다. 본 연구를 통해 예비교사들이 교과 지식의 전달을 촉진하고 학생과 적극적인 언어 상호작용이 이루어지도록 자기수업 분석과 함께 현장에서의 적극적인 지원이 요구된다.

• 한국측량학회:학술대회논문집
• /
• 한국측량학회 2004년도 춘계학술발표회논문집
• /
• pp.401-406
• /
• 2004

Recently various types of digital maps are widely available through the internet. Such e-maps have an advantage that user can easily get the information of destination by using only the search function. But these e-naps are based on 2D coordinate system so that they have limits that the virtual shapes of ground are very different from the real ones. Therefore, for more actual services of location information, we made a 3D model of Yonsei University with JAVA 3D and VRML technology and built the 3D e-map of Yonsei University, which is applied through the interaction between the web server and clients.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2005년도 춘계 학술발표회 논문집
• /
• pp.3-11
• /
• 2005

The structural analysis considering the soil-structure interaction is very important in the design process of underground structures located on the site with various soil conditions. In practice, simplified modelling techniques to obtain the approximate solution are used in accordance with the specifications. However, their details are insufficient for practical engineers to obtain the stable solutions and the analysis results of each engineer occasionally my be different in spite of the same problem. In this study, the sensitivity of structural behaviour on the underground structures is analyzed according to the structural modelling techniques of existing specifications. It is performed to obtain the fundamental informations to establish the guide to obtain the stable solutions in practical analysis of the underground structures such as subway structures.

• 대한기계학회논문집B
• /
• 제27권2호
• /
• pp.236-242
• /
• 2003

Thermal bubbles find their diverse application areas in the MEMS (MicroElectroMechanial Systems) technology, including bubble jet printers, microactuators, micropumps, etc.. Especially, microactuators and micropumps, which use a microbubble growing by a controlled heat input, frequently involve mechanical and thermal interaction of the bubble with a solid structure, such as a cantilever beam and a membrane. Although the concept is experimentally verified that an internal pressure of the bubble can build up high enough to deflect a thin solid plate or a beam, the physics of the entire process have not yet been thoroughly explored. This work reports the experimental study of the growth of a thermal bubble while deflecting a thin cantilever beam. A physical model is presented to predict the elastic response of the cantilever beam based on the experimental measurements. The scaling law constructed through this work can provide a design guide for micro- and nano-systems that employ a thermal bubble for their actuation/pumping mechanism.

• 대한디지털의료영상학회논문지
• /
• 제12권1호
• /
• pp.65-69
• /
• 2010

High energy electron beams were to concentrically dose inside a tumor and more energy is a shape decreased of dose. Therefore, it is useful to radiation therapy of a tumor. Also high energy electron beams ionized into collision with a atom in structure material of tissue and it has big changes to dose distribution by multiple scattering. The study had to establish characteristic of electron beams from interaction of electron beams and materials. Experiment method was to measure dependence of electron beam central axis for depth dose curve, field flatness and symmetry and field size dependence. The results were able to evaluate data for a datum pint of electron beam. Also radiotherapy has to be considered for not only energy pencil of lines but characteristic, electron guide and isodose curves distribution.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2002년도 제18회 학술발표대회 논문초록집
• /
• pp.10-13
• /
• 2002

Pogo is the instability resulting from the interaction between rocket structure and propulsion system of liquid propellant rocket. The coupling of structure and propulsion system can lead to severe problem in rocket. For the analysis of pogo, a time-invariant linearized mathematical model is developed for a selected flight time. Propulsion system is modeled using element representations for each components. The constitutive equation of propulsion system is a homogeneous second-order equation form in the Laplace domain. Rocket structure is modeled using FEM. From the results of modal analysis of structure, the behavior of structure can be represented. System equations for coupling structure and propulsion system are composed of all propulsion system equations and vehicle motion equations reacting on the vehicle by each component of propulsion system. The stability is obtained by the eigen solution of system matrix. The optimization of the design variables such as size, place of accumulator for suppressing pogo instability is carried out. This article of study can be used to determine the degree of stability, and guide the design of pogo suppression system.