• Applied Chemistry for Engineering
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• v.34 no.2
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• pp.137-143
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• 2023

In this study, natural surfactants were extracted from Medicago sativa L. The O/W emulsification processes with the extracted natural surfactants were optimized using central composite design model-response surface methodology (CCD-RSM) and a 95% confidence interval was used to confirm the reasonableness of the optimization. Herein, independent parameters were the ratio of saponins to total surfactant (P), amount of surfactant (W), and emulsification speed (R), whereas the reaction parameters were the emulsion stability index (ESI), mean droplet size (MDS), and viscosity (V). Using the multiple reaction, the optimal conditions for the ratio of saponins to total surfactant, amount of surfactant, and emulsification speed for O/W emulsification were 49.5%, 9.1 wt%, and 6559.5 rpm, respectively. Under these optimal conditions, the expected values of ESI, MDS, and V as the reaction parameters were 89.9%, 1058.4 nm, and 1522.5 cP, respectively. The values of ESI, MDS, and V from these expected values were 88.7%, 1026.4 nm, and 1486.5 cP, respectively, and the average experimental error for validating the accuracy was about 2.3 (± 0.4)%. Therefore, it was possible to design an optimization process for evaluating the O/W emulsion process with Medicago sativa L. using CCD-RSM.

• Journal of Pharmaceutical Investigation
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• v.25 no.3
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• pp.249-264
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• 1995

Although liposome has many advantages as a pharmaceutical dosage form, its application in the industrial field has been limited because of some problems such as preparation method, reproducibility, scale-up, stability and sterilization etc. Liposomes prepared by microemulsification method had defined size, narrow size distribution, reproducibility and high entrapment efficiency. For enhancing the stability, the dry form of liposome was recommended. These types of liposome are proliposome and freeze-dried liposome. The liposome must have some properties for preparing of freeze-dried liposome; small size $(50{\sim}200\;nm)$, narrow size distribution and cryoprotectant. In this experiment, the liposomes containing 5-Fluorouracil(5-FU) and its prodrug(pentyl-5-FU-1-acetate; PFA, hexyl-5-FU-1-acetate; HFA) were made with soybean phosphatidylcholine, cholesterol, stearylamine(SA) and dicetyl phosphate(DCP) employing hydration method or microemulsification method using $Microfluidizer^{TM}$. Both or liposome types were MLV and MEL. After preparation, freeze drying and rehydration were performed. In the process of freezing, trehalose(Tr) was added as a cryoprotectant. Their evaluation methods were as follows; entrapment efficiency, mean particle size and size distribution, dissolution test, retain of entrapment efficiency and turbidity after freeze-drying. The results are summarized as belows. The entrapment efficiency of 5-FU was dependent on total lipid concentration and cholesterol content but that of PFA and HFA was decreased when cholesterol was added. When DCP and SA were added, entrapment efficiency was decreased. As the partition coefficient of drug was increased, entrapment efficiency was increased. Under the same condition, entrapment efficiency of MEL is similar to that of MLV. The mean particle size and size distribution of MEL were smaller than those of MLV. Dissolution rates of drug from both liposome types were comparatively similar. Dissolution rates of drugs with serum and liver homogenate were faster than without these material. After preparation of liposome, free drug was removed efficiency by Dowex 50W-X4. When liposome was freeze-dried and then rehydrated in the presence of Tr, characteristics of liposome were maintained well in MEL than MLV. Tr Was used successfully as a cryoprotectant in the process of freeze drying and the optimal ratio of Tr:Lipid was 4:1(g/g).

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.5
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• pp.115-123
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• 2010

Cool-down performance after soaking is important because it affects passenger's thermal comfort. The cooling capacity of HVAC system determines initial cool down performance in most cases, the performance is also affected by location, and shape of panel vent, indoor seat arrangement. Therefore, optimal indoor designs are required in developing a new car. In this paper, initial cool down performance is predicted by CFD(computational fluid dynamics) analysis. Experimental time-averaging temperature data are used as inlet boundary condition. For more reliable analysis, real vehicle model and human FE model are used in grid generation procedure. Thermal and aerodynamic characteristics on re-circulation cool vent mode are investigated using CFX 12.0. Thermal comfort represented by PMV(predicted mean vote) is evaluated using acquired numerical data. Temperature and velocity fields show that flow in passenger's compartment after soaking is considerably unstable at the view point of thermodynamics. Volume-averaged temperature is decreased exponentially during overall cool down process. However, temperature monitored at different 16 spots in CFX-Solver shows local variation in head, chest, knee, foot. The cooling speed at the head and chest nearby panel vent are relatively faster than at the knee and foot. Horizontal temperature contour shows asymmetric distribution because of the location of exhaust vent. By evaluating the passenger's thermal comfort, slowest cooling region is found at the driver's seat.

• Journal of the Korean Society of Physical Medicine
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• v.11 no.3
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• pp.55-58
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• 2016

PURPOSE: This study was measured the differences in the flexor and extensor muscle activities of the elbow joints based on the tire pressure of wheelchairs during propulsion, investigating the optimal tire pressure for improving occupants' propulsion and avoiding related injury. METHODS: Ten healthy volunteers (10 men aged $23.1{\pm}1.9years$, weight: $67.9{\pm}3.4kg$, height: $175.1{\pm}2.7cm$) took part in the study. The mean values used in the statistical process were obtained from values measured while a subject sitting on a wheelchair propelled himself forward for 10 meters on a flat floor at maximum speed. The tire pressure of the wheelchairs was set at 100 psi, 50 psi, and 25 psi. All of the subjects performed wheelchair propulsion for each pressure. This study was measured the activation of the biceps brachii and triceps brachii muscles on the dominant side during wheelchair propulsion. The measured data was analyzed using one-way analysis of variance (ANOVA) via the statistical package for the social sciences (SPSS) version 12.0 for Windows to compare the muscle activity. RESULTS: The muscle activities of the biceps brachii and triceps brachii were significant differences between each pressure group. The post hoc test found statistically significant differences between 100 psi and 50 psi and 100 psi and 25 psi for the biceps brachii and triceps brachii muscles, respectively. CONCLUSION: The maintaining proper tire pressure in a wheelchair may help to prevent overuse syndrome in the occupant's elbow joints.

• Journal of Biosystems Engineering
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• v.33 no.5
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• pp.317-325
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• 2008

The electrocardiogram (ECG) measurement system consists of I/O interface to input the ECG signals from two electrodes, FPGA (Field programmable gate arrays) module to process the signal conditioning, and real time module to control the system. The algorithms based on wavelet transform were developed to remove the noise of the ECG signals and to determine the QRS-waves. Triangular wave tests were conducted to determine the optimal factors of the wavelet filter by analyzing the SNRs (signal to noise ratios) and RMSEs (root mean square errors). The hybrid rule, soft method, and symlets of order 5 were selected as thresholding rule, thresholding method, and mother wavelet, respectively. The developed wavelet filter showed good performance to remove the noise of the triangular waves with 10.98 dB of SNR and 0.140 mV of RMSE. The ECG signals from a total of 6 subjects were measured at different measuring postures such as lying, sitting, and standing. The durations of QRS-waves, the amplitudes of R-waves, the intervals of RR-waves were analyzed by using the finite impulse response (FIR) filter and the developed wavelet filter. The wavelet filter showed good performance to determine the features of QRS-waves, but the FIR filter had some problems to detect the peaks of Q and S waves. The measuring postures affected accuracy and precision of the ECG signals. The noises of the ECG signals were increased due to the movement of the subject during measurement. The results showed that the wavelet filter was a useful tool to remove the noise of the ECG signals and to determine the features of the QRS-waves.

• Journal of Korean Neurosurgical Society
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• v.58 no.2
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• pp.93-100
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• 2015

Objective : Optimal treatment decision and estimation of the prognosis in traumatic brain injury (TBI) is currently based on demographic and clinical predictors. But sometimes, there are limitations in these factors. In this study, we analyzed three central nervous system biomarkers in TBI patients, will discuss the roles and clinical applications of biomarkers in TBI. Methods : From July on 2013 to August on 2014, a total of 45 patients were included. The serum was obtained at the time of hospital admission, and biomarkers were extracted with centrifugal process. It was analyzed for the level of S-100 beta (S100B), glial fibrillary acidic protein (GFAP), and ubiquitin carboxy-terminal hydrolase-L1 (UCH-L1). Results : This study included 33 males and 12 females with a mean age of 58.5 (19-84) years. TBI patients were classified into two groups. Group A was severe TBI with Glasgow Coma Scale (GCS) score 3-5 and Group B was mild TBI with GCS score 13-15. The median serum concentration of S100B, GFAP, and UCH-L1 in severe TBI were raised 5.1 fold, 5.5 fold, and 439.1 fold compared to mild injury, respectively. The serum levels of these markers correlated significantly with the injury severity and clinical outcome (p<0.001). Increased level of markers was strongly predicted poor outcomes. Conclusion : S100B, GFAP, and UCH-L1 serum level of were significantly increased in TBI according to severity and associated clinical outcomes. Biomarkers have potential utility as diagnostic, prognostic, and therapeutic adjuncts in the setting of TBI.

• Korean Journal of Remote Sensing
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• v.30 no.2
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• pp.219-226
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• 2014

Fractional values resulted from the spectral mixture analysis could be used to classify not only urban area with various materials but also forest area in more detailed spatial scale. Especially South Korea is largely consist of mixed forest, so the spectral mixture analysis is suitable as a classification method. For the successful classification using spectral mixture analysis, extraction of optimal endmembers is prerequisite process. Though geometric endmember selection has been widely used, it is barely suitable for forest area. Therefore, in this study, we modified Iterative Error Analysis (IEA), one of the most famous algorithms of image endmember selection which extracts pure pixel directly from the image. The endmembers which represent deciduous and coniferous trees are automatically extracted. The experiments were implemented on two sites of Compact Airborne Spectrographic Imager (CASI) and classified forest area into two types. Accuracies of each classification results were 86% and 90%, which mean proposed algorithm effectively extracted proper endmembers. For the more accurate classification, another substances like forest gap should be considered.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.7
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• pp.216-224
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• 2013

The within-class variance of Otsu's method is moderate but improper in expressing class statistical distributions. Otsu's method uses a variance to represent the distribution of each class. The variance utilizes a distance square from the mean to a data. This process is not proper in denoting a real class statistical distribution because of the distance square. In this paper, to express more exact class statistical distributions, the within-class standard deviation as a criterion for threshold selection is proposed and then the optimal threshold is determined by minimizing it. In order to have validity, it is shown through the experimental results that the proposed method was more superior to the counterparts.

• Journal of the Korean Ceramic Society
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• v.52 no.1
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• pp.33-40
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• 2015

Onggi, described as a 'breathing' type of pottery' has significantly influenced the traditional food culture of Korea. It is known that Onggi is an optimal type of storage for fermented foods such as soy sauce, salted seafood, and Kimchi, as air or liquid can penetrate through the body of this material. These foods gain flavor due to the breeding of aerobic bacteria at the beginning of the fermentation process. In this study, Onggi materials from five regions, Gangjin, Yeoju, Ulsan, Yesan, and Jeju, were collected and analyzed to determine their chemical and physical properties before and after sintering. The differences in the raw materials of other mining regions are examined in terms of their chemical and mineralogical compositions, specific surface area, particle size, and particle distribution. Among them, the Gangjin raw material has the greatest mean particle size of $92.29{\mu}m$, as well as the widest particle size distribution. Differences in the levels of $SiO_2$ and $Fe_2O_3$ are shown among Onggi raw materials. However, the crystalline phases formed after sintering are identical, except for the Jeju samples. At all sintering temperatures tested here, Gangjin Onggi showed the greatest porosity, leading to complete air permeation through the body within 90 minutes. These results taken together indicate that air permeation is strongly related to the pore structures in the Onggi body. This is assumed to affect the fermentation behavior.

• Korean Journal of Oriental Medicine
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• v.14 no.2
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• pp.113-119
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• 2008

In pulse diagnosis, floating pulse and sinking pulse are frequently used for diagnosis about where disease is located and how much severe they are. However, in what mechanism floating pulse and sinking pulse arise is not known well. There are two point of views on substantial of floating pulse and sinking pulse. The first one is the floating and sinking degrees is the expression on the depth of pulsation. And, the second one is floating and sinking pulse is based on the response of pulsation to the indent pressure on radial artery. In this paper, we discussed these two opinions in the view point of tonometric measurement. The process for diagnosis on floating pulse and sinking pulse is similar to the tonometric measurement for non invasive blood pressure or intraocular pressure. We modelled the degrees of depth of pulsation with different indent pressures for initial pulsation feeling and different slopes of indent pressure lines. From this modelling, we can confirm the effect of pulsation depth on P-H curve, that is, in the model where lower pulsation is assumed, the shift of optimal indent pressure to the right was observed. The response of pulse pressure to the indent pressure was tried to be modelled with the degrees of mean blood pressure. Consequently, we tried to model the phenomenon of floating and sinking pulse for the first. And, from this modelling, we can get abundant understanding on how floating and sinking pulse can be caused. In the further study, we want to prove the suitability of this tonometric measurement based modelling with various studies including ultrasound measurement for the depth of pulsation in different EMI subjects.