• Journal of the Korea Society for Simulation
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• v.19 no.2
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• pp.73-80
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• 2010

A wireless sensor network which is deployed in hostile environment can be easily compromised by attackers. The selective forwarding attack can jam the packet or drop a sensitive packet such as the movement of the enemy on data flow path through the compromised node. Xiao, Yu and Gao proposed the checkpoint-based multi-hop acknowledgement scheme(CHEMAS). In CHEMAS, each path node enable to be the checkpoint node according to the pre-defined probability and then can detect the area where the selective forwarding attacks is generated through the checkpoint nodes. In this scheme, the number of hops is very important because this parameter may trade off between energy conservation and detection capacity. In this paper, we used the fuzzy rule system to determine adaptive threshold value which is the number of hops for the ACK packets. In every period, the base station determines threshold value while using fuzzy logic. The energy level, the number of compromised node, and the distance to each node from base station are used to determine threshold value in fuzzy logic.

• Analytical Science and Technology
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• v.22 no.6
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• pp.514-518
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• 2009

Coenzyme $Q_{10}$($CoQ_{10}$), a vitamin E-like substance, represents a components of the complex antioxidant system of the human organism. $CoQ_{10}$ levels in human plasma were determined by high performance liquid chromatography (HPLC) with UV detection. It was dissociated from lipoproteins by methanol and extracted into n-hexane with liquid-liquid extraction procedure, after centrifugation, the supernatant was dried under nitrogen gas stream. The residue was dissolved in the absolute ethanol. Determination of $CoQ_{10}$ was performed on a $C_{18}$ reversed-phase analytical column with ultraviolet detection at 275 nm and the mobile phase containing 15% (v/v) ethanol in methanol at a flow rate of 1.7 mL/min. The low limit of quantitation was 0.02 mg/L (S/N=10), the linearity between the concentration and peak height is from 0.1 to 2.0 mg/L. Twenty-four randomly selected plasma samples from apparently healthy, 27 to 44 year old individuals (males and females) were analyzed for total $CoQ_{10}$. The average level in these subjects was $0.62{\pm}0.13mg/L$ with the range of 0.41-0.98 mg/L. This method has a specific and a sufficient limit of quantitation (LOQ) for analysis of $CoQ_{10}$ in human plasma in both a clinical study and research at laboratories.

• Analytical Science and Technology
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• v.20 no.4
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• pp.323-330
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• 2007

A simple and rapid HPLC method with fluorescence detection(FLD) for quantitation of penciclovir in human plasma using a monolithic column was developed and validated. Penciclovir and ganciclovir(internal standard, I.S.) were separated on a Chromolith column RP-18e ($4.6{\times}100mm$) with a mobile phase consisting of a mixture of (A) methanol/50 mM sodium phosphate buffer containing 200 mg/L sodium dodecyl sulfate (3/97, pH 2.5) and (B) methanol/50 mM sodium phosphate buffer containing 200 mg/L sodium dodecyl sulfate (50/50, pH 2.5) at a flow gradient of $1.6{\sim}4.0mL/min$. The retention times of penciclovir and internal standard were less than 4.0 min. Calibration curve was linear ($R^2=0.9994$) over a concentration range of $0.1{\sim}5{\mu}g/mL$. Intra-day precision, accuracy and inter-day precision were 1.36~8.55 %, 92.8~100.0 % and 0.93~5.62 %, respectively with a limit of quantitation at $0.1{\mu}g/mL$. The present HPLC-FLD method is sensitive, precise and accurate. The method described herein has been successfully used for the bioequivalence study of a famciclovir formulation product after oral administration to healthy Korean volunteers.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.49 no.4
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• pp.291-298
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• 2023

In this study, a quantitative analysis method was developed using high-performance liquid chromatography (HPLC) to analyze the content of ceramide NP in lotion, cream, and cleanser formulations in cosmetics. The analysis was performed using a C18 column, and the mobile phase was set at a ratio of 70 : 30 for acetonitrile and methanol, the flow rate was set to 0.8 mL/min, and the column temperature was set to 20 ℃. The method was verified by analyzing specificity, linearity, limit of detection, limit of quantitation, accuracy, and precision in accordance with the ICH guidelines. As a result of validating the method, the linearity of the calibration curve was excellent (R² = 0.99984). The accuracy of the lotion, cream, and cleanser formulations was confirmed with a recovery rate ranging from 95.11% to 100.48%. The precision analysis showed a low relative standard deviation (RSD) of less than 0.26%. The limit of detection was 0.902 ㎍/mL, and the limit of quantitation was 2.733 ㎍/mL. Through this quantitative analysis method of ceramide NP applied in cosmetics, it is expected to assist in the quality control of products by enabling measurement even when it is difficult to separate the main peak due to the influence of interfering substances.

• The Journal of the Convergence on Culture Technology
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• v.9 no.6
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• pp.867-873
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• 2023

In this study, for the purpose of standardized quality control of a cold medicine, we simultaneous analyzed four main chemical components of a cold medicine: acetaminophen, caffeine, methyl paraben, and propyl paraben. The sample was subjected to quantitative analysis using high performance liquid chromatography (HPLC), after pretreatment of four components. The experiment was carried out by using Isocratic elution at wavelength of 270nm. Acetonitrile and water (H₂O) were used as a mobile phase at a flow rate of 1.0mL/min in a commercial C18 reversed-phase column. A volume of 10uL cold medicine were injected into the column with column oven temperature at 35℃. As a result of the experiment, the values of Resolution were 4.983, 1.596, 5.519, and 1.678 respectively-well over Rs >1.5, which indicates that the separation of four components were efficient. In addition, value of symmetry factor of the components was 1.056, 1.069, 1.032, and 1.133 respectively, to show its symmetrical stability. The calibration curve of all four components exhibits good linearity with R² >0.9995 to 0.9999. Furthermore, the limit of detection(LOD) were between 0.0118 to 1.5973 mg/mL, while the limit of quantification (LOQ) were between 0.0353 to 4.7919 ㎍/mL with the recovery rate of 79.6% ~ 120.5%. The results of this study showed an efficient quality evaluation of a simultaneous analysis method for cold medicine components.

• Journal of Korean Neurosurgical Society
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• v.67 no.4
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• pp.442-450
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• 2024

Objective : Cerebral hyperperfusion syndrome (CHS) manifests as a collection of symptoms brought on by heightened focal cerebral blood flow (CBF), afflicting nearly 30% of patients who have undergone superficial temporal artery (STA)-middle cerebral artery (MCA) anastomosis. The aim of this study was to investigate whether the amalgamation of magnetic resonance imaging (MRI) fluid-attenuated inversion recovery (FLAIR) and apparent diffusion coefficient (ADC) imaging via MRI can discern cerebral hyperemia after STA-MCA anastomosis surgery. Methods : A retrospective study was performed of patients who underwent STA-MCA anastomosis due to Moyamoya disease or atherosclerotic steno-occlusive disease. A protocol aimed at preventing CHS was instituted, leveraging the use of MRI FLAIR. Patients underwent MRI diffusion with FLAIR imaging 24 hours after STA-MCA anastomosis. A high signal on FLAIR images signified the presence of hyperemia at the bypass site, triggering a protocol of hyperemia care. All patients underwent hemodynamic evaluations, including perfusion MRI, single-photon emission computed tomography (SPECT), and digital subtraction angiography, both before and after the surgery. If a high signal intensity is observed on MRI FLAIR within 24 hours of the surgery, a repeat MRI is performed to confirm the presence of hyperemia. Patients with confirmed hyperemia are managed according to a protocol aimed at preventing further progression. Results : Out of a total of 162 patients, 24 individuals (comprising 16 women and 8 men) exhibited hyperemia on their MRI FLAIR scans following the procedure. SPECT was conducted on 23 patients, and 11 of them yielded positive results. All 24 patients underwent perfusion MRI, but nine of them showed no significant findings. Among the patients, 10 displayed elevations in both CBF and cerebral blood volume (CBV), three only showed elevation in CBF, and two only showed elevation in CBV. Follow-up MRI FLAIR scans conducted 6 months later on these patients revealed complete normalization of the previously observed high signal intensity, with no evidence of ischemic injury. Conclusion : The study determined that the use of MRI FLAIR and ADC mapping is a competent means of early detection of hyperemia after STA-MCA anastomosis surgery. The protocol established can be adopted by other neurosurgical institutions to enhance patient outcomes and mitigate the hazard of permanent cerebral injury caused by cerebral hyperemia.

• Particle and aerosol research
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• v.7 no.3
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• pp.71-77
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• 2011

Pork belly meat and mackerel are popular meals in Korea. Although a lot of people enjoy cooking these food, there have been some reports that generated organic particles during cooking could be thereas on of lung cancer of nonsmoking housewives. In addition, some experiments show that carcinogens may be included in meat and fishes which we eat usually. For this reason, particle size and concentration in formation during cooking are necessary to figure out the relationship between particles and the diseases. Thus, we identify number concentrations and size distributions of generated nano aerosol in cooking with respect to time, hood operation, and distance between cooking and measurement locations. The maximum concentrations of nano aerosol(diameter sizes are between 10 to 700nm)are decreased after the cooking from $8{\times}10^6{\sharp}/cm^3$ to zeroth order in pork belly meat cooking, and from $3.5{\times}{\times}10^6{\sharp}/cm^3$ to zeroth order in mackerel cooking respectively. When it comes to hood operation during cooking, the detected concentrations of generated aerosols are decreased as in taking flow rate of the hood increases. In cooking pork belly meat, the reduced amount of concentration is about $3{\times}10^6{\sharp}/cm^3$ compared to no hood operation, when hood in taking flow rate is $610m^3/hr$ In mackerel cooking, reduced concentration is $6{\times}10^5{\sharp}/cm^3$ in the same condition. Also, Naphthalene and Fluorene, which are known as polycyclic aromatic hydrocarbons (PAHs), are detected in the generated aerosols during cooking.

• Tuberculosis and Respiratory Diseases
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• v.71 no.2
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• pp.88-96
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• 2011

Background: It is known that cigarette smoke (CS) causes cell death. Apoptotic cell death is involved in the pathogenesis of CS-related lung diseases. Some members of the protein kinase C (PKC) family have roles in cigarette smoke extract (CSE)-induced apoptosis. This study was conducted to investigate the role of PKC epsilon in CSE-induced apoptosis in human lung fibroblast cell line, MRC-5. Methods: Lactate dehydrogenase release was measured using a cytotoxicity detection kit. The MTT assay was used to measure cell viability. Western immunoblot, Hoechst 33342 staining and flow cytometry were used to demonstrate the effect of $PKC{\varepsilon}$. Caspase-3 and caspase-8 activities were determined using a colorimetric assay. To examine $PKC{\varepsilon}$ activation, Western blotting was performed using both fractions of membrane and cytosol. Results: We showed that CSE activated $PKC{\varepsilon}$ by demonstrating increased expression of $PKC{\varepsilon}$ in the plasma membrane fraction. Pre-treatment of $PKC{\varepsilon}$ peptide inhibitor attenuated CSE-induced apoptotic cell death, as demonstrated by the MTT assay (13.03% of control, 85.66% of CSE-treatment, and 53.73% of $PKC{\varepsilon}$ peptide inhibitor-pre-treatment, respectively), Hoechst 33342 staining, and flow cytometry (85.64% of CSE-treatment, 53.73% of $PKC{\varepsilon}$ peptide inhibitor-pre-treatment). Pre-treatment of $PKC{\varepsilon}$ peptide inhibitor reduced caspase-3 expression and attenuated caspase-3, caspase-8 activity compared with CSE treatment alone. Conclusion: $PKC{\varepsilon}$ seem to have pro-apoptotic function and exerts its function through the extrinsic apoptotic pathway in CSE-exposed MRC-5 cells. This study suggests that $PKC{\varepsilon}$ inhibition may be a therapeutic strategy in CS-related lung disease such as chronic obstructive pulmonary disease.

• Korean Chemical Engineering Research
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• v.44 no.5
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• pp.513-519
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• 2006

We developed two kinds of the microchip for application to electrophoresis based on both glass and quartz employing the MEMS fabrications. The poly-Si layer deposited onto the bonding interface apart from channel regions can play a role as the optical slit cutting off the stray light in order to concentrate the UV ray, from which it is possible to improve the signal-to-noise (S/N) ratio of the detection on a chip. In the glass chip, the deposited poly-Si layer had an important function of the etch mask and provided the bonding surface properly enabling the anodic bonding. The glass wafer including more impurities than quartz one results in the higher surface roughness of the channel wall, which affects subsequently on the microflow behavior of the sample solutions. In order to solve this problem, we prepared here the mixed etchant consisting HF and $NH_4F$ solutions, by which the surface roughness was reduced. Both the shape and the dimension of each channel were observed, and the electroosmotic flow velocities were measured as 0.5 mm/s for quartz and 0.36 mm/s for glass channel by implementing the microchip electrophoresis. Applying the optical slit with poly-Si layer provides that the S/N ratio of the peak is increased as ca. 2 times for quartz chip and ca. 3 times for glass chip. The maximum UV absorbance is also enhanced with ca. 1.6 and 1.7 times, respectively.

• Journal of the Microelectronics and Packaging Society
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• v.14 no.2 s.43
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• pp.59-63
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• 2007

This paper presented a low-cost thick film gas sensor module, which was based on simple PCB (Printed Circuit Board) process. The proposed sensor module included a $NO_2/H_2$ gas sensor, a relative humidity sensor, and a heating element. The $NO_2/H_2$ gas and relative humidity sensors were realized by screen-printing $SnO_2,\;BaTiO_3$ nano-powders on IDTS (Interdigital Transducer) of a PCB substrate, respectively. At first 1% $H_2$ gas flowed into the sensor chamber. After 4 min, air filled the chamber while $H_2$ gas flow stopped. This experiment was performed repeatedly. The Identical procedure was used for the $NO_2$ detection. The result for sensing $H_2$ gas showed the increase of voltage from 0.8V to 3.5V due to the conductance increase and its reaction response time by hydrogen flow was 65 sec. $NO_2$ sensing results showed 2.7 V voltage drop due to the conductance decrease and its response time was 3 sec through a voltage monitoring.