• 한국막학회:학술대회논문집
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• 한국막학회 2004년도 Proceedings of the second conference of aseanian membrane society
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• pp.19-24
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• 2004

ED method is employed to effectively remove the organic acid salts in actual PDO fermentation broth. The lower electrical potential is selected to avoid the serious membrane fouling so as to ensure a stable and durative desalination process. Under the selected operation conditions, about 90% of organic acids salts are removed from PDO fermentation broth successfully by ED process. To reduce the loss of PDO product due to the diffusion, the operation time should be considered carefully. And based on mass balance equation and irreversible thermodynamics approach, a mathematical model is developed to describe the desalination process of an aqueous solution containing neutral solute by ED method. While the influence of concentration polarization is reflected by decreasing the conductivity of membrane, the model is verified well to describe the ED processes under varied operation conditions. Through the model, ED process of actual PDO fermentation broth is simulated to get a suitable scope of initial concentration in concentrated compartment.

• 대한의용생체공학회:의공학회지
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• 제24권4호
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• pp.329-337
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• 2003

선천적 혹은 후천적인 이유로 인하여 인체 특정 부위의 정맥과 동맥이 서로 관통하여 동맥계의 혈류가 말초 혈관계를 우회하여 정맥계로 흐르게 되는 동정맥루는 인체 심혈관계의 혈류 역학적 거동에 큰 영향을 미치게 된다. 본 연구에서는 lumped parameter 모델을 기반으로 하는 수치 해석 방법을 사용하여 우측 하지에 위치한 급성 동정맥루가 전체 심혈관계에 미치는 영향을 해석적으로 고찰하였다. 이를 위하여 동정맥루가 포함된 인체 심혈관계를 전기 회로 상사계로 구성하였으며. 부위별 혈압과 관련된 상미분 연립 방정식을 4차의 Runge-Kutta방법으로 풀어서 시간에 따른 혈류 역학적 변수들을 구하였다 이때 급성 동정맥루의 생성에 따른 혈류 역학적 보상작용을 분석하기 위하여 arterial baroreflex 제어계를 모델에 포함하였다.

• 대한방사성의약품학회지
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• 제2권2호
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• pp.108-112
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• 2016

Molecular imaging with the radiolabeled RGD peptides for ${\alpha}_v{\beta}_3$ integrin has been an increasing interest for tumor diagnosis and the treatment monitoring. Recently, $^{64}Cu$-NODAGA-gluco-E[c(RGDfK)]$_2$ was developed for quantification of ${\alpha}_v{\beta}_3$ integrin and its biological properties was elucidated. To better understand the molecular process in vivo, we performed the kinetic analysis for the $^{64}Cu$-NODAGA-gluco-E[c(RGDfK)]$_2$. After preparation of a radiotracer, dynamic PET images were obtained in the U87MG xenograft mice for 60 min (n = 6). Binding potential values were estimated from the 3-tissue compartment model, reference Logan and simplified reference tissue model. In the early time frame (0-20 min), the liver, kidney, intestine, urinary bladder and tumor were visualized but these uptakes were diminished as time went by. The tumors showed a good contrast at 40 min after administration. $^{64}Cu$-NODAGA-gluco-E[c(RGDfK)]$_2$ showed the 2-fold uptake in the tumor compared with that in the muscle. The parametric maps for binding values also provide the higher tumor-to-background contrast than the static images. A binding value obtained from the 3-tissue compartment model was comparable to other modeling methods. From these results, we conclude that $^{64}Cu$-NODAGA-gluco-E[c(RGDfK)]$_2$ may be a promising PET radiotracer for the evaluation of angiogenesis.

• 한국임상약학회지
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• 제27권4호
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• pp.258-266
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• 2017

Objective: To develop a population pharmacokinetics (PK)/pharmacodynamics (PD) model for alcohol in healthy volunteers and to elucidate individual characteristics to affects alcohol's PK or PD including dissolved oxygen. Methods: Following multiple intakes of total 540 mL alcohol (19.42 v/v%) to healthy volunteer, blood alcohol concentration was measured using a Breathe alcohol analyser (Lion SD-400 $Alcolmeter^{(R)}$). A sequential population PK/PD modeling was performed using NONMEM (ver 7.3). Results: Eighteen healthy volunteer were included in the study. PK model of alcohol was well explained by one-compartment model with first-order absorption and Michaelis-Menten elimination kinetics. $K_a$, V/F, $V_{max}$, $K_m$ is $8.1hr^{-1}$, 73.7 L, 9.65 g/hr, 0.041 g/L, respectively. Covariate analysis revealed that gender significantly influenced $V_{max}$ (Male vs Female, 9.65 g/hr vs 7.38 g/hr). PD model of temporary systolic blood pressure decreasing effect of alcohol was explained by biophase model with inhibitory $E_{max}$ model. $K_{e0}$, $I_{max}$, $E_0$, $IC_{50}$ were $0.23hr^{-1}$, 44.9 mmHg, 138 mmHg, 0.693 g/L, respectively. Conclusion: Model evaluation results suggested that this PK/PD model was robust and has good precision.

• 한국임상약학회지
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• 제26권4호
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• pp.312-317
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• 2016

Objective: Midazolam is mainly metabolized by cytochrome P450 (CYP) 3A. Inhibition or induction of CYP3A can affect the pharmacological activity of midazolam. The aims of this study were to develop a population pharmacokinetic (PK) model and evaluate the effect of CYP3A-mediated interactions among ketoconazole, rifampicin, and midazolam. Methods: Three-treatment, three-period, crossover study was conducted in 24 healthy male subjects. Each subject received 1 mg midazolam (control), 1 mg midazolam after pretreatment with 400 mg ketoconazole once daily for 4 days (CYP3A inhibition phase), and 2.5 mg midazolam after pretreatment with 600 mg rifampicin once daily for 10 days (CYP3A induction phase). The population PK analysis was performed using a nonlinear mixed effect model ($NONMEM^{(R)}$ 7.2) based on plasma midazolam concentrations. The PK model was developed, and the first-order conditional estimation with interaction was applied for the model run. A three-compartment model with first-order elimination described the PK. The influence of ketoconazole and rifampicin, CYP3A5 genotype, and demographic characteristics on PK parameters was examined. Goodness-of-fit (GOF) diagnostics and visual predictive checks, as well as bootstrap were used to evaluate the adequacy of the model fit and predictions. Results: Twenty-four subjects contributed to 900 midazolam concentrations. The final parameter estimates (% relative standard error, RSE) were as follows; clearance (CL), 31.8 L/h (6.0%); inter-compartmental clearance (Q) 2, 36.4 L/h (9.7%); Q3, 7.37 L/h (12.0%), volume of distribution (V) 1, 70.7 L (3.6%), V2, 32.9 L (8.8%); and V3, 44.4 L (6.7%). The midazolam CL decreased and increased to 32.5 and 199.9% in the inhibition and induction phases, respectively, compared to that in control phase. Conclusion: A PK model for midazolam co-treatment with ketoconazole and rifampicin was developed using data of healthy volunteers, and the subject's CYP3A status influenced the midazolam PK parameters. Therefore, a population PK model with enzyme-mediated drug interactions may be useful for quantitatively predicting PK alterations.

• 한국화재소방학회논문지
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• 제23권4호
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• pp.130-136
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• 2009

본 연구는 생성율 개념에 기초하여 화재유동장의 연소가스를 해석하는 필드모델의 신뢰성을 평가하기 위해 수행되었다. 환기조건에 따른 화재실 내부의 일산화탄소와 연기밀도를 해석하기 위하여 총괄당량비(GER) 개념이 도입되었으며 FDS 모델에 의해 예측된 일산화탄소와 연기밀도는 ISO-9705 표준화재실의 축소실험결과와 직접 비교하였다. 환기부족화재에 대해 수치해석결과는 일산화탄소와 연기밀도를 하향 예측하는 경향을 보였으며 총괄당량비가 증가함에 따라 수치해석결과와 실험결과의 오차는 증가하였다. 생성율 모델을 이용하여 화재발생으로 인한 연소생성물의 농도장을 해석하고자 하는 경우 공간내부의 환기 조건에 따라 해석결과의 신뢰성 검증에 주의를 기울여야 하며 지속적인 연구를 통해 타당한 물리적 모델개발과 함께 다양한 화재조건에 대한 모델의 검증이 요구된다.

• Journal of Theoretical and Applied Mechanics
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• 제3권1호
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• pp.34-44
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• 2002

Theoretical analysis Is carried out to identify the modal coupling effect between some particular acoustic modes of a vehicle compartment cavity and vibration modes of body panels like side doors, roof or floor. A simplified panel-cavity coupled model is investigated on the coupled resonance frequencies, modes and frequency response characteristics. Through parametric study, It Is possible to explain how the acoustic response of a coupled system will be determined by the vibration and acoustic property of the individual panel and cavity system. Full coupled system shows some interesting features different from those of the semi-coupled system In frequency, mode and acoustic response.

• IMMUNE NETWORK
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• 제1권3호
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• pp.196-202
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• 2001

Backgorund: WEHI-231 B cell line is a representative model for $IgM^+$ mature B cells. To understand the signaling differences between mature and immature B cells, we compared the responsiveness of WEHI-231 and Bal 17 B cell lines to BCR cross-linking. Methods: The extents of tyrosine phosphorylation, ligand-induced internalization, and activation-induced cell death upon BCR cross-linking were compared in two cell lines. Results: Despite a higher expression of BCR, cross-linking of BCR on WEHI-231 cell evoked a weaker level of tyrosine phosphorylation and BCR endocytosis than Bal 17 cells. Furthermore, the endocytosed BCR could not enter the lysosomal compartment and stayed as peripheral spots in WEHI-231 cells. Conclusion: WEHI-231 cell showed preferred BCR-mediated signaling pathways leading to a reduced capability of antigen presentation as well as the enhanced apoptosis in comparision with Bal 17 cells. These results might reflect the signaling differences between mature and immature B cells.

• International Journal of Automotive Technology
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• 제7권7호
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• pp.769-776
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• 2006

A mathematical model is developed in this paper to define the interaction between the occupant and vehicle passenger compartment and to predict the occupant dynamic response during a sudden impulse load. Two different types of occupants are considered in this study, child and adult occupants. The occupants are considered as lumped masses connected to the child seat and vehicle's body masses by means of restraint systems. In addition, the occupant restraint characteristics of seat belt and airbag are represented by stiffness and damping elements. To obtain the dynamic response of the occupant, the equations of motion of the occupants during vehicle collisions are developed and analytically solved. The occupant's acceleration and relative displacement are used as injury criteria to interpret the results. It is demonstrated from the numerical simulations that the dynamic response and injury criteria are easily captured and analyzed. It is also shown that the mathematical models are flexible, useful in optimization studies and it can be used at initial design stage.

• 한국가시화정보학회지
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• 제8권2호
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• pp.40-44
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• 2010

Thermal comfort inside a passenger car has been receiving large attention in automobile industries. Especially, the performance of windshield defroster is important in the design of a car to ensure passenger comport and safety. Thereby, better understanding on the ventilation flow along the vehicle windshield is essential to evaluate the performance of windshield defroster. However, most previous studies dealt with the defrost flow using CFD (computational fluid dynamics) calculations or scale-down model experiments. In this study, a real commercial automobile was used to investigate the flow discharged from the vehicle defroster and the ventilation flow along the windshield using a PIV velocity field measurement technique. The experimental data would be useful to understand the flow characteristics in detail and also can be used to validate numerical predictions.