• Journal of Veterinary Clinics
• /
• v.33 no.1
• /
• pp.10-15
• /
• 2016

The purpose of this study was to establish reproducible ischemic infarction model using allogenic blood clot in beagle dogs and identify induced ischemic lesion after middle cerebral artery occlusion using magnetic resonance imaging (MRI) and histopathologic findings. Twenty eight male beagle dogs with no evidence of neurologic disease were experimented. Allogenic embolus was made using a healthy beagle dog. After internal carotid artery (ICA) was exposure, 16G catheter was introduced through the ICA. The dog was administered 0.3 ml blood clot for 15 seconds followed by 3 ml of saline for 15 seconds. MRI scans were performed with 1.5T to evaluate ischemic lesion at 7 days after middle cerebral artery occlusion procedure. Evaluation parameters of MRI include location, distribution, infarction type, margin, shape, mass effect and intensity of T1-weighted imaging (T1WI), T2-weighted imaging (T2WI), fluid attenuated inversion recovery (FLAIR) sequence, diffusion weighted imaging (DWI) and apparent diffusion coefficient (ADC). On MRI, all dogs (28/28) showed focal or multifocal lesion including telencephalon and thalamus lesions, especially caudate nucleus (24/28). These lesions had well-defined margin from adjacent brain parenchyma, none or mild mass effect and various shape. Most of dogs appeared hyperintensity on T1WI, T2WI, FLAIR, and DWI/ADC, corresponding to chronic infarction. These lesions were histopathologically confirmed atrophic changes and unstained lesion. In conclusion, MRI is the useful method to provide information about ischemic infarction in dogs and the best reproducible ischemic infarction model was developed by using allogenic blood clot.

• Korean Journal of Food Science and Technology
• /
• v.18 no.1
• /
• pp.61-65
• /
• 1986

This study was performed to examine the drying characteristics of apples at various drying conditions. Air velocity has no effect on the drying rate except the constant rate period. In this experiment the diffusion coefficients of moisture in the apple tissue were in the range of $1.1470-2.2148{\times}10cm^2/sec$. As a result of balance of heat and mass transfer during the falling rate period. an empirical equation based on Fick's law was obtained as follows; $log{\Delta}t\;=\;log\;t_o\;-\;D{\frac{{\pi}^2{\theta}}{4d.}}$ This equation can be used to calculate the temperature of apples during the falling rate period, provided the diffusion coefficients of apple are known. The experimental values of the internal moisture distribution during apple dehydration were nearly in accord with the theoretical values.

• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2006.09b
• /
• pp.1018-1021
• /
• 2006

Powdered metal parts and components may be carburized successfully in a vacuum furnace by combining carburizing technology $VacCarb^{TM}$ with a hi-tech control system. This approach is different from traditional carburizing methods, because vacuum carburizing is a non-equilibrium process. It is not possible to set the carbon potential as in a traditional carburizing atmosphere and control its composition in order to obtain a desired carburized case. This paper presents test results that demonstrate that vacuum carburizing system $VacCarb^{TM}$ carburized P.M. materials faster than traditional steel with acceptable results. In the experiments conducted, PM samples with the lowest density and open porosity showed a dramatic increase in the surface carbon content up to 2.5%C and a 3 times deeper case. Currently the boost-diffusion technique is applied to control the surface carbon content and distribution in the case. In the first boost step, the flow of the carburizing gas has to be sufficient to saturate the austenite, while avoiding soot deposition and formation of massive carbides. To accomplish this goal, the proper gas flow rate has to be calculated. In the case of P.M. parts, more carbon can be absorbed by the part's surface because of the additional internal surface area created by pores present in the carburized case. This amount will depend on the density of the part, the densification grade of the surface layer and the stage of the surface. "as machined" or "as sintered". It is believed that enhanced gas diffusion after initial evacuation of the P.M. parts leads to faster carburization from within the pores, especially when pores are open . surface "as sintered" and interconnected . low density. A serious problem with vacuum carburizing is delivery of the carbon in a uniform manner to the work pieces. This led to the development of the different methods of carburizing gas circulation such as the pulse/pump method or the pulse/pause technique applied in SECO/WARWICK's $VacCarb^{TM}$ Technology. In both cases, each pressure change may deliver fresh carburizing atmosphere into the pores and leads to faster carburization from within the pores. Since today's control of vacuum carburizing is based largely on empirical results, presented experiments may lead to better understanding and improved control of the process.

• Restorative Dentistry and Endodontics
• /
• v.29 no.6
• /
• pp.498-503
• /
• 2004

The properties of ideal root canal sealers include the ability of sealing the total root canal system and no toxic effects to periradicular tissues. Cytotoxicity test using cell culture is a common screening method for evaluation of the biocompatibility of root canal sealers. The purpose of this study was to investigate the cytotoxic effect of newly developed resin-based sealer (Adseal 1, 2, and 3) comparing with those commercial resin-based sealers (AH26 and AH Plus), ZOE-based sealers (Tubliseal EWT, Pulp Canal Sealer EWT) and calcium hydroxide based sealer (Sealapex), An indirect contact test of cytotoxicity by agar diffusion was performed according to the international standard ISO 10993-5. L929 fibroblast cells were incubated at $37^{\circ}C$ in humidified 5% $CO_2-containing$ air atmosphere. The freshly mixed test materials were inserted into glass rings of internal diameter 5 mm and height 5 mm placed on the agar. After the 24 hrs incubation period, the decolorization zones around the test materials were assessed using an inverted microscope with a calibrated screen. A Decolorization Index was determined for each specimen. Adseal 1. 2, and 3 did not exert any cytotoxic effects, whereas AH26, AH Plus, Tubliseal EWT, Pulp Canal Sealer EWT, and Sealapex produced mild cytotoxicity.

• Journal of Hydrogen and New Energy
• /
• v.32 no.4
• /
• pp.245-255
• /
• 2021

Various studies about metallic bipolar plates have been conducted to improve fuel cell performance through flow field design optimization. These research works have been mainly focused on fuel cells for vehicle, but not fuel cells for building. In order to reduce the price and volume of fuel cell stacks for building, it is necessary to apply a metallic flow field, In this study, for a metallic flow field applied to a fuel cell for building, the effect of a change in the flow field shape on the performance of a polymer electrolyte membrane fuel cell was confirmed using a model and experiments with a down-sizing single cell. As a result, the flow field using a metal foam outperforms the channel type flow field because it has higher internal differential pressure and higher reactants velocity in gas diffusion layer, resulting in higher water removal and higher oxygen concentration in the catalyst layer than the channel type flow field. This study is expected to contribute to providing basic data for selecting the optimal flow field for the full stack of polymer electrolyte membrane fuel cells for buildings.

• 한국사회정책
• /
• v.20 no.3
• /
• pp.117-140
• /
• 2013

This research focuses on the effects of international and national factors on the legislation of data privacy law in 117 countries from 1960 to 2011. Previous research on data privacy law usually put its emphasis on the contents of data privacy law, legal interpretation of data privacy law or legal cases; yet it lacks academic approaches from human rights perspectives. This paper points out the diffusion of data privacy law in nation states and analyzes the effects of national international factors affecting the legislation of data privacy law using an event history analysis. It turns out that the increasing number of internet users and international human rights regime are positively associated with the likelihood of having data privacy law. Contrary to our hypotheses, FDI, internal human rights practices, and the level of high technology do not show any effects on the likelihood of having a data privacy law.

• Journal of the Korean Electrochemical Society
• /
• v.27 no.1
• /
• pp.32-39
• /
• 2024

The key components of a Phosphoric acid fuel cell (PAFC) are an electrode catalyst, an electrolyte matrix and a gas diffusion layer (GDL). In this study, we introduced a microporous layer on the GDL of PAFC to enhance liquid electrolyte management and overall electrochemical performance of PAFC. MPL is primarily used in polymer electrolyte membrane fuel cells to serve as an intermediate buffer layer, effectively managing water within the electrode and reducing contact resistance. In this study, electrodes were fabricated using GDLs with and without MPL to examine the influence of MPL on the performance of PAFC. Internal resistance and polarization curves of the unit cell were measured and compared to each other to assess the impact of MPL on PAFC electrode performance. As the results, the application of MPL improved power density from 170.2 to 192.1 mW/cm². MPL effectively managed electrolyte and water within the matrix and electrode, enhancing stability. Furthermore, the application of MPL reduced internal resistance in the electrode, resulting in sustained and stable performance even during long-term operation.

• Journal of the Korean Society of Radiology
• /
• v.12 no.6
• /
• pp.755-762
• /
• 2018

The purpose of this study was to compare the FA(faractional anisotropy) and ADC(apparent diffusion coefficient) values, which were derived from diffusion tensor imaging in breast cancer patients. The diffusion gradient used in this study was derived from quantitative diffusion indices using 20 directions(b-value, 0 and $1,000s/mm^2$). Quantitative analysis was analyzed using Pearson's correction and qualitative analysis using for correction coefficients. As a result, $FA_{min}$, $FA_{mean}$ and $FA_{max}$ were $0.098{\pm}0.065$, $0.302{\pm}0.142$ and $0.634{\pm}0.236$, respectively(p > 0.05). The $ADC_{min}$, $ADC_{mean}$ and $ADC_{max}$ were $0.741{\pm}0.403$, $1.095{\pm}0.394$ and $1.530{\pm}0.447$, respectively(p > 0.05). The $FA_{min}$, $FA_{mean}$, and $FA_{max}$ mean values were $0.132{\pm}0.050$, $0.418{\pm}0.094$, and $0.770{\pm}0.164$ for Category 6 and Kinetic Curve Pattern III, respectively. $ADC_{min}$, $ADC_{mean}$, and $ADC_{max}$ were $0.753{\pm}0.189$, $1.120{\pm}0.236$, and $1.615{\pm}0.372$, respectively. Quantitative analysis showed negative correlation between $ADC_{mean}-FA_{mean}$ and $ADC_{max}-FA_{max}$(p = 0.001, 0.003). The qalitative analysis showed ADC 0.628(p = 0.001), FA 0.620(p = 0.001) in the internal evaluations, ADC 0.677(p = 0.001), FA 0.695(p = 0.001) in external evaluations. In conclusion, based on the morphological examination, time to signal intensity graph is the form of wash-out(pattern III) in the dynamic contrast enhance examination, As a result, the $ADC_{mean}$ $1.120{\pm}0.236$ and $FA_{mean}$ values were $0.032{\pm}0.142$ with a negative correlation (Y=1.44-1.12X). Therefore, If we understand the shape of time to signal intensity graph and the relationship between ADC and FA, It will be a criterion for distinguishing malignant diseases in breast cancer.

• Tuberculosis and Respiratory Diseases
• /
• v.81 no.1
• /
• pp.42-48
• /
• 2018

Background: The diffusing capacity of the lung is influenced by multiple factors such as age, sex, height, weight, ethnicity and smoking status. Although a prediction equation for the diffusing capacity of Korea was proposed in the mid-1980s, this equation is not used currently. The aim of this study was to develop a new prediction equation for the diffusing capacity for Koreans. Methods: Using the data of the Korean National Health and Nutrition Examination Survey, a total of 140 nonsmokers with normal chest X-rays were enrolled in this study. Results: Using linear regression analysis, a new predicting equation for diffusing capacity was developed. For men, the following new equations were developed: carbon monoxide diffusing capacity (DLco)=-10.4433-0.1434${\times}$age (year)+0.2482${\times}$heights (cm); DLco/alveolar volume (VA)=6.01507-0.02374${\times}$age (year)-0.00233${\times}$heights (cm). For women the prediction equations were described as followed: DLco=-12.8895-0.0532${\times}$age (year)+0.2145${\times}$heights (cm) and DLco/VA=7.69516-0.02219${\times}$age (year)-0.01377${\times}$heights (cm). All equations were internally validated by k-fold cross validation method. Conclusion: In this study, we developed new prediction equations for the diffusing capacity of the lungs of Koreans. A further study is needed to validate the new predicting equation for diffusing capacity.

• Journal of Korea Soil Environment Society
• /
• v.4 no.2
• /
• pp.137-147
• /
• 1999

Fluidized-bed thermal desorber coupled with a heat pipe was investigated for the remediation of soil contaminated with diesel oils. Thermal gravimetric analysis by Cahn-balance indicated that the desorption of diesel oils from the soil particles was mainly governed by the internal diffusion at low concentration of less than 0.5 wt. % of oils in the soil particles. In fluidized-bed experiments. increase of fluidizing gas velocity reduced the residual oils of the contaminated soils, the increase of soil feed rate decreased efficiency of fluidized-bed desorber. A mathematical model was developed by incorporating Fickian diffusion kinetics into the Kunii-Levenspiel model Simulation results showed reasonable agreement for the performance of fluidized-bed thermal desorber.