• Korean Journal of Acupuncture
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• 제38권2호
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• pp.75-99
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• 2021

Objectives : The purpose of this study is to analyze animal behavioral changes and related neurobiological mechanisms in recent studies using animal models with pain and depression. Methods : We conducted database search in Pubmed, NDSL, and EMBASE up to January 2021. Included studies were classified as depression-like behavior observed in pain model, pain-like behavior observed in depression model, and pain and depression comorbidity model. The results of pain- and depression-like behaviors, the changes of neurobiological mechanisms, and the treatment methods such as drugs, natural substance-derived chemicals, or acupuncture were analyzed. Results : We included 124 studies (81 studies in depression-like behavior observed in pain model, 19 studies in pain-like behavior observed in depression model, and 24 studies in pain and depression comorbidity model). Pain and depression comorbidity animal models were induced using various methods by drugs or surgery. Von frey test, a method for evaluating mechanical allodynia was the most commonly used for measuring pain-like behavior and the forced swimming test was the most commonly used for measuring depression-likes behavior. The changes of neurobiological factors, such as decrease of 5-hydroxytryptamine and increase of oxidative stress and pro-inflammation cytokines were generally changed in the frontal cortex, hippocampus, thalamus, and spinal cord in all types of models. For treating pain and depression-like behaviors, various types of drugs such as antidepressant, tranquilizer, analgesic, and natural substance-derived chemicals were used. Acupuncture treatment was used in 4 studies. Conclusions : In the future, more diverse studies on the combined model of pain and depression need to be conducted. In addition, it is necessary to establish a mechanistic basis for the development of various treatments by identifying the common mechanisms of pain and depression.

• Nuclear Engineering and Technology
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• 제54권7호
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• pp.2367-2375
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• 2022

In this work, we propose a new mechanistic model for the treatment of helium behaviour at the grain boundaries in oxide nuclear fuel. The model provides a rate-theory description of helium inter-granular behaviour, considering diffusion towards grain edges, trapping in lenticular bubbles, and thermal resolution. It is paired with a rate-theory description of helium intra-granular behaviour that includes diffusion towards grain boundaries, trapping in spherical bubbles, and thermal re-solution. The proposed model has been implemented in the meso-scale software designed for coupling with fuel performance codes SCIANTIX. It is validated against thermal desorption experiments performed on doped UO₂ samples annealed at different temperatures. The overall agreement of the new model with the experimental data is improved, both in terms of integral helium release and of the helium release rate. By considering the contribution of helium at the grain boundaries in the new model, it is possible to represent the kinetics of helium release rate at high temperature. Given the uncertainties involved in the initial conditions for the inter-granular part of the model and the uncertainties associated to some model parameters for which limited lower-length scale information is available, such as the helium diffusivity at the grain boundaries, the results are complemented by a dedicated uncertainty analysis. This assessment demonstrates that the initial conditions, chosen in a reasonable range, have limited impact on the results, and confirms that it is possible to achieve satisfying results using sound values for the uncertain physical parameters.

• 대한화학회지
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• 제55권3호
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• pp.341-345
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• 2011

Schiff base 코발트(II) 착물, bis[4-chloro-2-((E)-(isopropylimino) methyl) phenol]cobalt(II), 을 합성하고 단결정 X-ray 회절 분석을 하였다. 코발트 (ii) 합성물의 현상학적, 속도론적 및 기계적 특성은 TG/DTG법으로 연구하였다. 실험 데이터에 기초하여, 활성화 에너지, 지수 앞자리인자, 활성화 엔트로피와 같은 속도론적 파라미터를 계산하였으며, 가장 가능성 있는 메카니즘 함수로는 $g({\alpha})={\alpha}^2$이 추정되었다. 따라서, 모든 분해 단계에서 속도 조절 단계는 1차원 확산 과정(Parabolic model) 이다.

• 한국정밀공학회지
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• 제18권7호
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• pp.143-148
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• 2001

In this study, a mechanistic model of cutting force components in up and down end milling process is presented. Using this cutting force model of 4-tooth endmills with various helix angles, cutting force variation of inconel 718 has been predicted. Predicted values of cutting force components are coincide well with the measured ones. As helix angle increases, overlapping effects of the active cutting edges increase. In up endmilling the magnitudes of radial and feed cutting force componts FX and FY are lowest when the helix angle is $40\{\circ}$, but in down endmilling the magnitudes of these values increase slightly as helix angle becomes large.

• Environmental Engineering Research
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• 제25권2호
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• pp.205-211
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• 2020

Chlorhexidine digluconate (CHD) in the aquatic environment causes irreversible change to microbes, making them resistant to biodegradation, which needs remediation other than biological process. Adsorption study was performed for the removal of CHD on fly ash (FA) as a function of pH and ionic strength. Experimental result has been validated by characterization using Scanning electron microscopy, Fourier Transform-Infrared Spectroscopy and Brunauer-Emmett-Teller. CHD adsorption with FA showed an increasing trend with an increase in pH. Variation in pH proved to be an influential parameter for the surface charge of adsorbent and the degree of ionization of the CHD molecules. The adsorption capacity of CHD decreased from 23.60 mg g-1 to 1.13 mg g-1, when ionic strength increased from to M. The adsorption isotherms were simulated well by the Freundlich isotherm model having R2 = 0.98. The Lagergren's model was incorporated to predict the system kinetics, while the mechanistic study was better explained by pseudo-second order for FA. On the basis of operational conditions and cost-effectiveness FA was found to be more economical as an adsorbent for the adsorption of CHD.

• The Korean Journal of Physiology and Pharmacology
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• 제18권3호
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• pp.217-223
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• 2014

Plasma ionized calcium ($Ca^{2+}$) concentrations are tightly regulated in the body and maintained within a narrow range; thus it is challenging to quantify calcium absorption under normal physiologic conditions. This study aimed to develop a mechanistic model for the parathyroid hormone (PTH) response after calcium intake and indirectly compare the difference in oral calcium absorption from PTH responses. PTH and $Ca^{2+}$ concentrations were collected from 24 subjects from a clinical trial performed to evaluate the safety and calcium absorption of Geumjin Thermal Water in comparison with calcium carbonate tablets in healthy subjects. Indirect response models (NONMEM Ver. 7.2.0) were fitted to observed $Ca^{2+}$ and PTH data, respectively, in a manner that absorbed but unobserved $Ca^{2+}$ inhibits the secretion of PTH. Without notable changes in $Ca^{2+}$ levels, PTH responses were modeled and used as a marker for the extent of calcium absorption.

• International Journal of Precision Engineering and Manufacturing
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• 제6권3호
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• pp.24-28
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• 2005

Stress state of chip formation zone is one of the main problems in metal cutting mechanics. In two-dimensional case this process is usually considered as consistent shears of work material along one of several shear surfaces, separating chip from workpiece. These shear planes are assumed to be trajectories of maximum shear stress forming corresponding slip-line field. This paper suggests a new approach to the constriction of slip-line field, which implies uniform compression in chip formation zone. Based on the given model it has been found that imaginary shear line in orthogonal cutting is close to the trajectory of maximum normal stress and the problem about its determination has been considered as well. It has been shown that there is a second central slip-line field inside chip, which corresponds well to experimental data about stress distribution on tool rake face and tool-chip contact length. The suggested model would be useful in understanding mechanistic problems in machining.

• Nuclear Engineering and Technology
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• 제32권4호
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• pp.410-423
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• 2000

A two-dimensional numerical model is developed and applied to the LAVA-EXV tests performed at the Korea Atomic Energy Research Institute (KAERI) to investigate the external cooling effect on the thermal margin to failure of a reactor pressure vessel (RPV) during a severe accident. The computational program was written to predict the temperature profile of a two-dimensional spherical vessel segment accounting for the conjugate heat transfer mechanisms of conduction through the debris and the vessel, natural convection within the molten debris pool, and the possible ablation of the vessel wall in contact with the high temperature melt. Results of the sensitivity analysis and comparison with the LAVA-EXV test data indicated that the developed computational tool carries a high potential for simulating the thermal behavior of the RPV during a core melt relocation accident. It is concluded that the main factors affecting the RPV failure are the natural convection within the debris pool and the ablation of the metal vessel, The simplistic natural convection model adopted in the computational program partly made up for the absence of the mechanistic momentum consideration in this study. Uncertainties in the prediction will be reduced when the natural convection and ablation phenomena are more rigorously dealt with in the code, and if more accurate initial and time-dependent conditions are supplied from the test in terms of material composition and its associated thermophysical properties.

• Membrane and Water Treatment
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• 제8권1호
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• pp.73-88
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• 2017

Adsorption kinetics of aqueous ferric ion ($Fe^{3+}$) onto bio-natural rice grains (BRG) have been studied in a batch system. The influence of contact time (0-180 minutes), the dosage of BRG adsorbent (10, 20, 40, and $60gL^{-1}$), and ambient temperature (27, 37, 47, and $57^{\circ}C$) for the adsorption system have been reported. The equilibrium time achieved after 20 minutes of adsorption contact time. The maximum removal of ferric ion is 99% by using $60gL^{-1}$ of BRG, $T=37^{\circ}C$, and $50mgL^{-1}$ ferric ion solution. Adsorption kinetic and diffusion models, such as pseudo-first order, pseudo-second order, and Weber-Morris intra-particle diffusion model, have been used to describe the adsorption rate and mechanism of the ferric ion onto BRG surface. The sorption data results are fitted by Lagergren pseudo-second order model ($R^2=1.0$). The kinetic parameters, rate constant, and sorption capacities have been calculated. The new information in this study suggests that BRG could adsorb ferric ion from water physiosorption during the first 5 minutes. Afterward, the electrostatic interaction between ferric ion and BGR-surface could take place as a very weak chemisorptions process. Thus, there is no significant change could be noticed in the FTIR spectra after adsorption. I recommend producing BGR as a bio-natural filtering material for removing the ferric ion from water.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1997년도 추계학술발표회논문집(1)
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• pp.599-604
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• 1997

One of important inconsistencies in the six-equation model predictions has been found to be the force experienced by a single bubble placed in a convergent stream of liquid. Various sets of governing equations yield different amount of forces to hold the bubble stationary in a convergent nozzle. By using the first order potential flow theory, it is found that the six-equation model can not be used to estimate the force experienced by a deformed bubble. The theoretical value of the particle stress of a bubble in a convergent nozzle flow has been found to be a function of the Weber number when bubble distortion is allowed. This force has been calculated by using different sets of governing equations and compared with the theoretical value. It is suggested in this study that the bubble size distribution function can be used to remove the presented inconsistency by relating the interfacial variables with different moments of the bubble size distribution function. This study also shows that the inconsistencies in the thermal-hydraulic governing equation can be removed by mechanistic modeling of the phasic interface.