• Journal of Biosystems Engineering
• /
• 제38권2호
• /
• pp.129-137
• /
• 2013

Purpose: Modeling has been used for elucidating the mechanism of complex biosystems. In spite of importance and uniqueness of adolescent calcium (Ca) metabolism characterized by a threshold Ca intake, its regulatory mechanism has not been covered and even not proposed. Hence, this study aims at model-based proposing potential mechanisms regulating adolescent Ca metabolism. Methods: Two different hypothetic mechanisms were proposed. The main mechanism is conceived based on Ca-protein binding which induces renal Ca filtration, while additional mechanism assumed that active renal Ca re-absorption regulated Ca metabolism in adolescents. Mathematical models were developed to represent the proposed mechanism and simulated them whether they could produce adolescent Ca profiles in serum and urine. Results: Simulation showed that both mechanisms resulted in the unique behavior of Ca metabolism in adolescents. Based on the simulation insulin-like growth factor-1 (IGF-1) is suggested as a potential regulator because it is related to both growth, a remarkable characteristic of adolescence, and Ca metabolism including absorption and bone accretion. Then, descriptive modeling is employed to conceptualize the hypothesized mechanisms governing adolescent Ca metabolism. Conclusions: This study demonstrated that modeling is a powerful tool for elucidating an unknown mechanism by simulating potential regulatory mechanisms in adolescent Ca metabolism. It is expected that various analytic applications would be plausible in the study of biosystems, particularly with combination of experimental and modeling approaches.

• Water Engineering Research
• /
• 제6권3호
• /
• pp.113-122
• /
• 2005

Periphyton is known to be one of major primary producers for river ecosystem. While the growth of periphyton usually observed on the stone surface in gravel river, the large growth of periphyton is sometimes seen even in sand river with relatively small river discharge. In the present study, field observations and numerical simulations were performed to investigate the growth of periphyton in sand river. In the field observation, the growth of periphyton on fixed sand bed was measured weekly. The results of the field observations show that the large growth of periphyton occurs in sand river until the bed material sands have not moved. An integrated numerical simulation model is presented to describe the growth of periphyton at observed river reach, and a series of numerical simulations were performed to study the effect of river discharge on growth of periphyton in the sand river. The results of the numerical simulations show that the net primary production of periphyton decreases with the river discharge. These results suggest that the reduction of river discharge at ordinary water stage strongly affects the primary productivity of periphyton even in sand river.

• The Korean Journal of Ecology
• /
• 제6권4호
• /
• pp.1-9
• /
• 1983

The observation of branching pattern on Magnolia denudata Desr. was performed from July 1982 to September 1983 and then computer simulation was carried out. Tree crown pattern depends on not genetic factors but also environmental factors and the determination of branchin pattern which characterized it appears to properly explain the relationships such as branching pattern and allocation of materials through the analysis of influence branches under several assumptions. Now that computer simulated simulated pattern was considered as the accumulation of two factors which controled the growth, it was represented as the stimulated tree which differs in branching rate that described allocation of material necessary for the growth of each branch. There was a tendency of allocation ratio of nutrients, i.e. subbranch to main branch to decrease by the passage of year. Under assumption that branch was branched when accumulated material reached 1, it was possible to represent the allocation of nutrients are residual $nutrient{\times}\frac{1}{1+F};in main; branch, ; residual; nutrient{\times}\frac{F}{1+F}$ in subbranch, A(iA, iC)+$F^(iA-1)$ in current twig. Like this, the basic minute difference of the allocation of nutrients according to the branch resulted in complicated patterns in the tree crown.

• Journal of Biosystems Engineering
• /
• 제36권5호
• /
• pp.348-354
• /
• 2011

Various crop spacing methods have been implemented so far for the greenhouse and plant factory applications. However, there is no generally accepted parameter for evaluation of plant spacing efficiency in plant production system. In this study, 'Planted Area Index' (PAI) of a spacing method is defined as the ratio of the planted area in the field to required planted area using the spacing method when no transplanting operation is assumed. Three common types of spacing methods for plane placement of the plants were modeled mathematically. For calculating the planted area, an optimal growth radius function (R(t)) is needed. Function of the days after transplanting stage gives a radius of an optimal circle area for the living plants. A computer simulation was developed to calculate the PAI, based on three crop spacing methods and four optimal growth radius functions. In general, the 1-D zigzag spacing showed the best PAI. Moreover, it gives an example on how to apply the PAI for the design.

• 한국환경복원기술학회지
• /
• 제3권3호
• /
• pp.37-44
• /
• 2000

The objective of this study is on suggesting the simulation model of 10 selected plants for the traffic noise barrier through field experiment by computer. The field experiment was carried out at the traffic noise barrier of Honam highway. The results are as follows. 1. It was identified that Paederia scandens, Celastrus Orbiculatus, Lonicera japonica, Wisteria floribunda, Parthenocissus tricuspidata and Parthenocissus quinquefolia grows well vertically and takes 3 years in covering completely. 2. It was identified that Trachelospermum asiaticum and Hedera rhombea, evergreen Climber(vine), grows slowly in comparative with other deciduous Climbers(vine), but give drivers good landscapes in winter. So those have considerable value in the south region of Taejeon. 3. It was identified that Wisteria jl.oribunda, Lonicera japonica, Paederia scandens, Clematis mandschurica and Campsis grandijlora showed good view in flowering period. 4. It was identified that auxiliary materials for inducing growth were needed in other plants except Parthenocissus tricuspidata, Parthenocissus quinquefolia. 5. It was identified that subsequent research about the auxiliary materials for inducing growth and adequate planting distance of each plants is needed for actual application.

• 한국결정성장학회지
• /
• 제15권4호
• /
• pp.162-167
• /
• 2005

건조공정 중인 다공성 물질의 물성은 재료의 비균질성 즉 전위, 입자, 입계, 균열, 기공과 같은 미시적인 결함인자들의 영향을 받는다. 따라서 다공성 물질의 건조공정을 전산 시뮬레이션하기 위해서는 원자 스케일 해석을 통한 미시적 물성을 알아야 한다. 본 연구에서는 분자동역학 시뮬레이션을 이용하여 원자 모델을 구성하고 원자 상호간 거동을 예측하여 재료의 미시적 물성을 계산하였다. 이렇게 구한 탄성계수, 열팽창계수, 체적 열용량은 실험 및 이론에 기초한 결과들과 비교하여 검증하였다.

• 반도체디스플레이기술학회지
• /
• 제16권3호
• /
• pp.1-7
• /
• 2017

Multi-wafer planetary type chemical vapor deposition reactors are widely used in thin film growth and suitable for large scale production because of the high degree of growth rate uniformity and process reproducibility. In this study, a two-dimensional model for estimating the effect of the gap between satellite and wafer on the wafer surface temperature distribution is developed and analyzed using computational fluid dynamics technique. The simulation results are compared with the results obtained from an analytical method. The simulation results show that a drop in the temperature is noticed in the center of the wafer, the temperature difference between the center and wafer edges is about $5{\sim}7^{\circ}C$ for all different ranges of the gap, and the temperature of the wafer surface decreases when the size of the gap increases. The simulation results show a good agreement with the analytical ones which is based on one-dimensional heat conduction model.

• 한국가시화정보학회지
• /
• 제19권2호
• /
• pp.26-31
• /
• 2021

The spanwise growth of turbulence structures in turbulent pipe flow was investigated using the direct numerical simulation data of Re_𝜏 = 544, 934 and 3008. Two-point correlations and pre-multiplied energy spectra of streamwise velocity fluctuations were examined along the spanwise direction. The arclength direction is defined as r𝛳, which is useful for an analogy with the spanwise direction for channels or boundary layers; here, r and 𝛳 are the radial distance from the core and the azimuthal angles, respectively. Both analyses showed that the arclength scales increased with increasing the wall-normal distance. It showed that the coherent structures were confined in the core region due to the crowding effect of a circular pipe geometry. The pipe flow simulation could describe a realistic geometrical flow along the azimuthal direction, unlike the simulations of turbulent channel or boundary layer flow using periodic boundary conditions along the spanwise direction. The present results provided the spanwise organization of energy-containing motions over a broad range of scales in turbulent pipe flow.

• 한국전자통신학회논문지
• /
• 제5권1호
• /
• pp.102-108
• /
• 2010

컴퓨터 그래픽스 기술을 접목한 디지털 영상 콘텐츠 산업이 점차 증가하면서, 사용자들은 현실세계와 흡사할 정도의 고품질 애니메이션을 요구하고 있으며, 사이버수족관 및 어류백과사전 등을 통해서 어류의 형태나 유영방식을 관찰하고자 한다. 본 연구에서는 해저 환경을 표현함에 있어서 가장 핵심이 되는 어류의 자연스럽고도 역동적인 움직임을 표현하기 위해 어류 성장 과정 시스템을 설계하고 개발하였다. 본 시스템에서는 기존 어류 유영 방식을 새롭게 보완한 알고리즘을 사용한 시뮬레이션과 기존 모핑 연구에서 제시되지 않은 새로운 모핑 기법을 제안한다. 또한 어류의 성장 과정 중 환경 요인에 따라 발생하는 질병 감염 상태를 현실적으로 표현한다. 기존 어류 연구와 다르게 포괄적인 어류 연구를 진행하여 어류에 관련된 전반적인 특징을 현실적으로 시뮬레이션 하여 살펴보게 된다.

• 한국시뮬레이션학회논문지
• /
• 제21권1호
• /
• pp.19-26
• /
• 2012

본 논문은 카자흐스탄의 해외직접투자와 경제성장에 관한 연관관계를 연구한다. 이 연구를 위하여 저자들은 먼서 카자흐스탄의 독립이후로 해외직접투자에 영향을 미친 요인들을 조사하고 그들의 영향정도를 파악한다. 다음으로 일인당 GDP대한 일인당 해외직접투자의 영향을 연구한다. 이러한 연구목적을 달성하기 위하여 1992년부터 2009년 사이의 자료를 World Bank Database에서 수집하여 분석하였다. 자료분석은 중회귀분석, 시계열분석 및 Granger Causality Test를 주로 사용하였다. 연구 결과에 의하면 해외직접투자에 영향을 미치는 요소는 GDP 와 economic freedom index로 나타났으며, 경제성장 또한 해외직접 투자에 영향을 받는 것으로 나타났다. 특별히, 해외직접투자는 GDP 및 economic freedom index와 양의 상관관계가 있었다. 일인당 GDP에 대한 일인당 해외직접투자의 영향은 일인당 해외직접투자 1달러 증가시 일인당 GDP 30.4달러가 증가하는 것으로 나타났다. 본 연구의 결과는 정책결정자들로 하여금 해외투자를 유치하고 경제성장을 촉진하는 정책결정에 유용한 정보를 제공할 것이다.