• Title/Summary/Keyword: two phases model

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Study on Spatial Model Generation for BIM-based Apartment Maintenance History Management (BIM 기반 공동주택 유지보수 이력 관리를 위한 공간 모델 생성 연구)

  • Lee, Kwang-eon;Lee, Yun-Gu;Ham, Nam-Hyuk;Kim, Jae-Jun
    • Journal of KIBIM
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    • v.14 no.3
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    • pp.31-45
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    • 2024
  • This study proposes a BIM-based space model generation framework for managing maintenance history in apartments. While BIM adoption in design and construction phases is increasing, its use in operation and maintenance remains limited, particularly in the continuous utilization of as-built BIM models. To address this, the study introduces a methodology for automated space model generation using DYNAMO, analyzing 1,875 maintenance records and long-term repair plans from two apartment projects over two years. The framework was applied to case projects, achieving a 100% space model creation rate for dedicated spaces and 108.91% for public spaces, proving its applicability. This suggests that the automated space model generation process proposed in this study is applicable. The significance of this study is that it presents a model transition framework for the operation and maintenance phase of the as-built BIM model. In addition, it is of research value that a simplified BIM space model is proposed to overcome the limitation of not being able to manage the history of each part in the current maintenance phase. This study can be utilized as a basis for future BIM guidelines applicable to operation and maintenance phases and delivery guidelines for as-built BIM models.

Computations of Compressible Two-phase Flow using Accurate and Efficient Numerical Schemes

  • Kim, Chong-Am
    • 한국전산유체공학회:학술대회논문집
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    • 2006.10a
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    • pp.13-17
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    • 2006
  • RoeM and AUSMPW+ schemes are two of the most accurate and efficient schemes which are recently developed for the analysis of single phase gas dynamics. In this paper, we developed two-phase versions of these schemes for the analysis of gas-liquid large density ratio two-phase flow. We adopt homogeneous equilibrium model (HEM) using mass fraction to describe different two phases. In the Eulerian-Eulerian framework, HEM assumes dynamic and thermal equilibrium of the two phases in the same computational mesh. From the mixture equation of state (EOS), we derived new shock-discontinuity sensing term (SDST), which is commonly used in RoeM and AUSMPW+ for the stable numerical flux calculation. The proposed two-phase versions of RoeM and AUSMPW+ schemes are applied on several air-water two-phase test problems. In spite of the large discrepancy of material properties such as density, enthalpy, and speed of sound, the numerical results show that both schemes provide very satisfactory solutions.

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A Convective Heat Transfer Correlation for Turbulent Gas-Liquid Two-Phase Flow in Vertical Pipes

  • Kim, Dong-Woo
    • International Journal of Air-Conditioning and Refrigeration
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    • v.9 no.4
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    • pp.27-36
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    • 2001
  • A new two-phase non-boiling convective heat transfer correlation for turbulent flow $(Re_{SL}>4000)$ in vertical tubes with different fluid flow patterns and fluid combinations was developed using experimental data available from the literature. The correlation presented herein originates from a careful analysis of the major non-dimensional parameters affecting two-phase heat transfer. This model takes into account the appropriate contributions of both the liquid and gas phases using the respective cross-sectional areas occupied by the two phases. A total of 255 data points from three available studies (which included the four sets of data) were used to determine the curve-fitted constants in the improved correlation. The performance of the new correlation was compared with two-phase correlations from the literature, which were developed for specific fluid combinations.

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Kinetic Characterization of Swelling of Liquid Crystalline Phases of Glyceryl Monooleate

  • Lee, Jae-Hwi;Choi, Sung-Up;Yoon, Mi-Kyeong;Choi, Young-Wook
    • Archives of Pharmacal Research
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    • v.26 no.10
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    • pp.880-885
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    • 2003
  • Research in this paper focuses on the kinetic evaluation of swelling of the liquid crystalline phases of glyceryl monooleate (GMO). Swelling of the lamellar and cubic liquid crystalline phases of GMO was studied using two in vitro methods, a total immersion method and a Franz cell method. The swelling of the lamellar phase and GMO having 0 %w/w initial water content was temperature dependent. The swelling ratio was greater at $20^{\circ}^C than 37^{\circ}^C$ . The water uptake increased dramatically with decreasing initial water content of the liquid crystalline phases. The swelling rates obtained using the Franz cell method with a moist nylon membrane to mimic buccal drug delivery situation were slower than the total immersion method. The swelling was studied by employing first-order and second-order swelling kinetics. The swelling of the liquid crystalline phases of GMO could be described by second-order swelling kinetics. The initial stage of the swelling (t < 4 h) followed the square root of time relationship, indicating that this model is also suitable for describing the water uptake by the liquid crystalline matrices. These results obtained from the current study demonstrate that the swelling strongly depends on temperature, the initial water content of the liquid crystalline phases and the methodology employed for measuring the swelling of GMO.

Landing Motion Analysis of Human-Body Model Considering Impact and ZMP Condition (충격과 ZMP 조건을 고려한 인체 모델의 착지 동작 해석)

  • So Byung Rok;Kim Wheekuk;Yi Byung-Ju
    • Journal of Institute of Control, Robotics and Systems
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    • v.11 no.6
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    • pp.543-549
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    • 2005
  • This paper deals with modeling and analysis fer the landing motion of a human-body model. First, the dynamic model of a floating human body is derived. The external impulse exerted on the ground as well as the internal impulse experienced at the joints of the human body model is analyzed. Second, a motion planning algorithm exploiting the kinematic redundancy is suggested to ensure stability in terms of ZMP stability condition during a series of landing phases. Four phases of landing motion are investigated. In simulation, the external and internal impulses experienced at the human joints and the ZMP history resulting from the motion planning are analyzed for two different configurations. h desired landing posture is suggested by comparison of the simulation results.

Comparison of Foot Pressure Distribution During Single-leg Squat in Individuals With and Without Pronated Foot

  • Il-kyu Ahn;Gyeong-tae Gwak;Ui-jae Hwang;Hwa-ik Yoo;Oh-yun Kwon
    • Physical Therapy Korea
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    • v.31 no.1
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    • pp.40-47
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    • 2024
  • Background: Single-leg squat (SLS)s are commonly used as assessment tool and closed kinetic exercises are useful for assessing performance of the lower extremities. Pronated feet are associated with foot pressure distribution (FPD) during daily activities. Objects: To compare the FPD during SLSs between groups with pronated and normal feet. Methods: This cross-sectional study included 30 participants (15 each in the pronated foot and control groups) are recruited in this study. The foot posture index was used to distinguish between the pronated foot and control groups. The Zebris FDM (Zebris Medical GmbH) stance analysis system was used to measure the FPD on the dominant side during a SLS, which was divided into three phases. A two-way mixed-model ANOVA was used to identify significant differences in FPD between and within the two groups. Results: In the hallux, the results of the two-way mixed-model ANOVAs revealed a significant difference between the group and across different phases (p < 0.05). The hallux, and central forefoot were significantly different between the group (p < 0.05). Moreover, significant differences across different phases were observed in the hallux, medial forefoot, central forefoot, lateral forefoot, and rearfoot (p < 0.05). The post hoc t-tests were conducted for the hallux and forefoot central regions. In participants with pronated foot, the mean pressure was significantly greater in hallux and significantly lower, in the central forefoot during the descent and holding phases. Conclusion: SLSs are widely used as screening tests and exercises. These findings suggest that individuals with pronated feet should be cautious to avoid excessive pressure on the hallux during the descent-to-hold phase of a SLS.

Chiral Recognition Models of Enantiomeric Separation on Cyclodextrin Chiral Staionary Phases

  • 이선행;김병학;이영철
    • Bulletin of the Korean Chemical Society
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    • v.16 no.4
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    • pp.305-309
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    • 1995
  • The enantiomeric separation of several amino acid derivatives by reversed-phase liquid chromatography using two (R)-and (S)-naphthylethylcarbamate-β-cyclodextrin(NEC-β-CD) bonded stationary phases was studied to illustrate the chiral recognition model of the enantiomeric separation. The retention and enantioselectivity of the chiral separations with (R)-and (S)-NEC-β-CD bonded phases were compared with similar separations with the native β-CD stationary phases. Especially, the enantioselectivity and elution orders between the derivatized amino acid enantiomers are carefully examined. These results can be illustrated by the chiral recognition models involving inclusion complexation, π-π interaction, and/or hydrophobic interaction. Inclusion complexation and hydrophobic interaction of the naphthyl group of the NEC moiety seem to be major chiral recognition components in the enantiomeric separation of 2,4-dinitrophenyl amino acids and dabsyl amino acids on (R)-and (S)-NEC-β-CD columns. For dansyl amino acids, only the inclusion complexation is the dominant factor. Three different chiral recognition models containing π-π interaction, inclusion complexation and hydrogen bonding were proposed for the separation of the 3,5-dinitrobenzoyl amino acid enantiomers, depending on the size and shape of amino acids.

A Concept Analysis on Learning Transfer in Nursing Using the Hybrid Model (혼종 모형을 이용한 간호 학습전이의 개념 분석)

  • Son, Hae Kyoung;Kim, Hyo Jin;Kim, Dong Hee
    • Korean Journal of Occupational Health Nursing
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    • v.29 no.4
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    • pp.354-362
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    • 2020
  • Purpose: This study aimed to define and clarify learning transfer in nursing. Methods: This study used a hybrid model to analyze the concept of learning transfer in nursing through three phases. For the theoretical phase, learning transfer attributes were identified through a scoping literature review. In the fieldwork phase, in-depth focus group interviews were conducted to develop attributes. Purposive sampling was performed with ten participants(five nursing students, two nurses, three nursing faculty members). In the analysis phase, the attributes and final analysis of learning transfer in nursing were extracted and integrated from the previous two phases. Results: According to the analysis, learning transfer was represented in two dimensions with eight attributes. The development of competency dimension had three attributes: 1) theory acquisition, nursing skills, professional attitude, 2) integration, and 3) analysis competency. The competency change dimension had five attributes: 1) appropriateness in patient care, 2) proficiency in patient care, 3) satisfaction, 4) achievement, and 5) confidence. Conclusion: The concept analysis might provide a basic understanding of learning transfer, a development framework toward a measurement of nursing learning transfer and effective educational nursing strategies.

A SIMPLE DISK-HALO MODEL FOR THE CHEMICAL EVOLUTION OF OUR GALAXY

  • Lee, S.W.;Ann, H.B.
    • Journal of The Korean Astronomical Society
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    • v.14 no.2
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    • pp.55-71
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    • 1981
  • On the basis of observational constraints, particularly the relationship between metal abundance and cumulative stellar mass, a simple two-zone disk-halo model for the chemical evolution of our Galaxy was investigated, assuming different chemical processes in the disk and halo and the infall rates of the halo gas defined by the halo evolution. The main results of the present model calculations are: (i) The halo formation requires more than 80% of the initial galactic mass and it takes a period of $2{\sim}3{\times}10^9$ yrs. (ii) The halo evolution is divided into two phases, a fast collapse phase ($t=2{\sim}3{\times}10^8$ yrs) during which period most of the halo stars $({\sim}95%)$ are formed and a later slow collapse phase which is characterized by the chemical enrichment due to the inflow of external matter to the halo. (iii) The disk evolution is also divided into two phases, an active disk formation phase with a time-dependent initial mass function (IMF) up to $t{\approx}6{\times}10^9$ yrs and a later steady slow formation phase with a constant IMF. It is found that at the very early time $t{\approx}5{\times}10^8$ yrs, the metal abundance in the disk is rapidly increased to ${\sim}1/3$ of the present value but the total stellar mass only to ${\sim}10%$ of the present value, finally reaching about 80% of the present values toward the end of the active formation phase.

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