• 환경위생공학
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• 제16권1호
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• pp.91-101
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• 2001

In order to propose a optimum method increasing accuracy and reproducibility in analysis of urine lead levels, we compared matrix modifier addition method and microwave digestion method. The results were as follows ; 1. Where the concentration of $Pd(NO_3)_2$(matrix modifier) was $50mg/{\ell}$, and ashing temperature was $900^{\circ}C$, the results were optimum. In case of matrix modifier addition method, the average coefficient of variation (CV) of normal man was 24.1%, and lead worker was 7.9%. The average urine lead levels of standard were $10.42\mu{g}/{\ell}$ and $19.89\mu{g}/{\ell}$ , the accuracies compared to reference values were 97.0% and 92.6%, respectively. 2. Microwave digestion temperature($160~180^{\circ}C$), time(15~25min) and the ratio of urine/ashing acid(1:1~4:1) did not significantly affect lead absorbance and background absorbance. Therefore we set up a optimum analytical conditions as follows: temperature, $160^{\circ}C$; time, 15min; the ratio of urine/ashing acid, 4:1. after samples were digested by the above analytical conditions, lead absorbance and background absorbance was measured at $450^{\circ}C$ as ashing temperature. The average coefficient of variation (CV) of normal man was 12.4%, and lead worker was 6.2%. The average urine lead levels of standard urine were $10.66\mu{g}/{\ell}$ and $23.31\mu{g}/{\ell}$, the accuracies compared to reference values were 99.3% and 103.9%, respectively. From the results, we suggest that microwave digestion method is a more favorable method than matrix modifier addition method because of easiness to reduce organic matter, possibility to analysis at low temperature and accuracy.

• Biomolecules & Therapeutics
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• 제14권1호
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• pp.50-55
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• 2006

The objective of the study was to evaluate the bioequivalency between the $Rozid^{TM}$ Tablet (Ilhwa Pharm. Co., Ltd.) as a test formulation and the $Rulid^{TM}$ Tablet (Handok Pharm. Co., Ltd) as a reference formulation. Twenty-four healthy male volunteers were administered the formulations by the randomized Latin square crossover design, and the plasma samples were determined by a high performance liquid chromatography (HPLC) with fluorescence detector. $AUC_t,\;C_{max}\;and\;T_{max}$ were obtained from the time-plasma concentration curves, and log-transformed $AUC_t\;and\;C_{max}$ and log-untransformed $T_{max}$ values for two formulations were compared by statistical tests and analysis of variation. $AUC_t$ was determined to be $63.30{\pm}25.57{\mu}g.hr/ml$ for the test formulation and $64.02{\pm}29.27mg.hr/ml$ for the reference formulation. The mean values of $C_{max}$ for the test and reference formulations were $5.07{\pm}2.14\;and\;5.53{\pm}2.60{\mu}g/ml$, respectively. The $AUC_t,\;and\;C_{max}$ ratios of the test $Rozid^{TM}$ Tablet to the reference $Rulid^{TM}$ Tablet were -1.12% and -8.32%, respectively, showing that the mean differences were satisfied the acceptance criteria within 20%. The results from analysis of variance for log-transformed $AUC_t,\;and\;C_{max}$ indicated that sequence effects between groups were not exerted and 90% confidence limits of the mean differences for $AUC_t,\;and\;C_{max}$ were located in ranges from log 0.80 and log 1.25, satisfying the acceptance criteria of the KFDA bioequivalence. The RozidTM Tablet as the test formulation was considered to be bioequivalent to the RulidTM Tablet used as its reference formulation, based on $AUC_t,\;and\;C_{max}$ values.

• 한국군사과학기술학회지
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• 제7권2호
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• pp.81-87
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• 2004

Semiconductor thick film gas sensors based on tin oxide are fabricated and their gas response characteristics are examined for four simulant gases of chemical warfare agent (CWA)s. The sensing materials are prepared in three different sets. 1) The Pt or Pd $(1,\;2,\;3\;wt.\%)$ as catalyst is impregnated in the base material of $SnO_2$ by impregnation method.2) $Al_2O_3\;(0,\;4,\;12,\;20\;wt.\%),\;In_2O_3\;(1,\;2,\;3\;wt.\%),\;WO_3\;(1,\;2,\;3\;wt.\%),\;TiO_2\;(3,\;5,\;10\;wt.\%)$ or $SiO_2\;(3,\;5,\;10\;wt.\%)$ is added to $SnO_2$ by physical ball milling process. 3) ZnO $(1,\;2,\;3,\;4,\;5\;wt.\%)$ or $ZrO_2\;(1,\;3,\;5\;wt.\%)$ is added to $SnO_2$ by co-precipitation method. Surface morphology, particle size, and specific surface area of fabricated sensing films are performed by the SEM, XRD and BET respectively. Response characteristics are examined for simulant gases with temperature in the range 200 to $400^{\circ}C$, with different gas concentrations. These sensors have high sensitivities more than $50\%$ at 500ppb concentration for test gases and also have shown good repetition tests. Four sensing materials are selected with good sensitivity and stability and are fabricated as a sensor array A sensor array Identities among the four simulant gases through the principal component analysis (PCA). High sensitivity is acquired by using the semiconductor thick film gas sensors and four CWA gases are classified by using a sensor array through PCA.

• BMB Reports
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• 제37권4호
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• pp.480-486
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• 2004

Brain ischemia brings about hypoxic insults. Hypoxia is one of the major pathological factors inducing neuronal injury and central nervous system infection. We studied the involvement of mitogen-activated protein (MAP) kinase in hypoxia-induced apoptosis using cobalt chloride in C6 glioma cells. In vitro cytotoxicity of cobalt chloride was tested by MTT assay. Its $IC_{50}$ value was $400\;{\mu}M$. The DNA fragment became evident after incubation of the cells with $300\;{\mu}M$ cobalt chloride for 24 h. We also evidenced nuclear cleavage with morphological changes of the cells undergoing apoptosis with electron microscopy. Next, we examined the signal pathway of cobalt chloride-induced apoptosis in C6 cells. The activation of extracellular signal-regulated protein kinase 1/2 (ERK 1/2) started to increase at 1 h and was activated further at 6 h after treatment of 400 M cobalt chloride. In addition, pretreatment of PD98059 inhibited cobalt chloride-induced apoptotic cell morphology in Electron Microscopy. These results suggest that cobalt chloride is able to induce the apoptotic activity in C6 glioma cells, and its apoptotic mechanism may be associated with signal transduction via MAP kinase (ERK 1/2).

• Archives of Pharmacal Research
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• 제28권8호
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• pp.942-947
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• 2005

Peroxynitrite is a potent neurotoxic molecule produced from a reaction between NO and super-oxide and induces NO-mediated inflammation under neuropathological conditions. Previously, we reported that glucose deprivation induced ATP depletion and cell death in immunostimulated astrocytes, which was mainly due to peroxynitrite. In this study, the role of MAPKs (ERK1/2, p38MAPK, and JNK/SAPK) signal pathway in the SIN-1/glucose deprivation-induced death of astrocytes was examined. A combined treatment with glucose deprivation and $50 {\mu}M$ SIN-1, an endogenous peroxynitrite generator, rapidly and markedly increased the death in rat primary astrocytes. Also, SIN-1/glucose deprivation resulted in the activation of MAPKs, which was significantly blocked by the treatment with $20{\mu}M$ MAPKs inhibitors (ERK1/2, PD98059; p38MAPK, SB203580; JNK/SAPK, SP600125). Interestingly, SIN-1/glucose deprivation caused the loss of intracellular ATP level, which was significantly reversed by MAPKs inhibitors. These results suggest that the activation of MAPKs plays an important role in SIN-1/glucose deprivation-induced cell death by regulating the intracellular ATP level.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 C
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• pp.1867-1869
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• 2003

In this paper, chamber(Circuit breaker compartment of C-GIS) made of stainless steel with 4 mm width is used. Artificial defect was made on enclosure or HV conductor of chamber and $SF_6$ gas was injected into it according to pressure. In this experiment, Acoustic emission sensors of different types was used to compare sensitivity to detect acoustic signal occurred by Partial discharge(PD) of according to types and resonance frequency in $SF_6$ gas atmosphere. Sensors used in tests was R6I, R15I and 2/4/6 Pre-Amplifier connected with R6IU without pre. amp. In case of R6IU, gain was adjusted with 40 dB like other sensors and operated by differential mode. Post amplifier(post. amp) and band pass filter(BPF) were developed Gain of post. amp. is 60 dB and BPF has band width of $50{\sim}300$ kHz. Also, envelope circuit developed reduces frequency of AE sensor. As a result, in $SF_6$ atmosphere, R6IU and R6I had resonance frequency of 60 Hz was better than R15I. Also, R6IU was better than R6I because of type property of pre.amp. had differential mode.

• 한국약용작물학회지
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• 제20권1호
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• pp.27-35
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• 2012

This study was conducted to investigate changes in composition of ginsenosides and color of processed ginsengs prepared by different steaming-drying times. Processed ginsengs were prepared from white ginseng with skin by 9-time repeated steaming at $96^{\circ}C$ for 3 hours and followed by hot air-drying at $50^{\circ}C$ for 24 hours. As the times of steaming processes increased, lightness (L value) decreased and redness (a value) increased in color of ginseng powders. Crude saponin contents and ginsenosides compositions in processed ginsengs prepared by different steaming-drying times were investigated using the HPLC method, respecively. Crude saponin contents according to increasing steaming-drying times decreased in some degree. In the case of major ginsenosides, the contents of $Rb_1$, $Rb_2$, Rc, Rd, Rf, Re, $RG_1$, Re were decreased with increase in steamimg times, but those of $Rh_1$, $Rg_3$, $Rk_1$ were increased after especially 3 times of steaming processes. Interestingly, in black ginseng were prepared by 9 times steaming processes, the content of ginsenoside $Rg_3$ was 8.20 mg/g, approximately 18 times higher than that (0.46 mg/g) in red ginseng. In addition, the ratio of the protopanaxadiol group and protopanaxatiol group (PD/PT) were increased from 1.9 to 8.4 due to increasing times of steamming process.

• 한국전기전자재료학회논문지
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• 제32권5호
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• pp.418-425
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• 2019

A piezoelectric ceramic fiber composite (PCFC) was successfully fabricated using $0.69Pb(Zr_{0.47}Ti_{0.53})O_3-0.31[Pb(Zn_{0.4}Ni_{0.6})_{1/3}Nb_{2/3}]O_3$ (PZT-PZNN) for use in small-scale wind energy harvesters. The PCFC was formed using an epoxy matrix material and an array of Ag/Pd-coated PZT-PZNN piezo-ceramic fibers sandwiched by Cu interdigitated electrode patterned polyethylene terephthalate film. The energy harvesting performance was evaluated in a custom-made wind tunnel while varying the wind speed and resistive load with two types of flutter wind energy harvesters. One had a five-PCFC array vertically clamped with a supporting acrylic rod while the other used the same structure but with a five-PCFC cantilever array. Stainless steel (thickness: $50{\mu}m$) was attached onto one side of the PCFC to form the PZT-PZNN cantilever. The output power, in general, increased with an increase in the wind speed from 2 m/s to 10 m/s for both energy harvesters. The highest output power of $15.1{\mu}W$ at $14k{\Omega}$ was obtained at a wind speed of 10 m/s for the flutter wind energy harvester with the PZT-PZNN cantilever array. The results presented here reveal the strong potential for wind energy harvester applications to supply sustainable power to various IoT micro-devices.

• 대한건축학회논문집:계획계
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• 제34권2호
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• pp.3-11
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• 2018

Korea has achieved a rapid economic development and with the increase in population and national income and the expansion of social and economic activities, energy consumption has rapidly increased too. Energy consumption per head has constantly increased and currently, power consumption per head is 7.5 times bigger than in 1985. Buildings occupy 25% of total energy consumption and especially, 50% of total energy is consumed for heating and cooling. In this situation, multi-family housing, which has constantly been increased, has an energy saving rate of 1.9%, which is the lowest level and this makes the government's energy policy for sustainable energy system development useless. Besides, energy consumption leads to secondary problems, such as air, water and marine pollution and heat pollution and wastewater/drainage and the increased use of fossil fuel is a fundamental reason for ozone layer destruction and global warming. Therefore, efficient energy consumption plans are required. This study aims to analyze energy performance in each block type of high-rise and diversified multi-family housing that accounts for 60% of all the housing forms, depending on the variations in stories through BIM-based energy simulation. For this study, four representative block types were selected, based on the multi-family floor plan, which is certified for energy performance evaluation and they were applied to the floor plan of a multi-family house that is scheduled to be built. Then BIM modeling was conducted from the fifth story to the 40th story at an intervals of 5 stories and based on the finding, energy characteristics of each block type and energy performance depending on the variations in stories were analyzed. It is considered that this would serve as objective data for block type and block story decision of energy performance-based multi-family housing.

• 대한건축학회논문집:계획계
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• 제34권6호
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• pp.23-30
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• 2018

Gordon Cullen, who tried to understand urban landscapes in terms of visual attention, introduced a concept called 'Space and Infinity' in his book 'Townscape'. According to him, urban images like infinity spreading across the sky are more effectively created when we happen to see an open space while walking along a ground-level street than when we look at the sky. This study aims to quantitatively examine if urban observers pay more attention to spaces like pilotis on the bottom of a building. Thus, this study collected observers on actual urban landscape images and partially-edited images and conducted an experiment by adopting Eye-movement Tracking to find out if they actually pay more visual attention to a space like pilotis. This study selected a total of 50 people as research subjects and divided them into two groups. Image 1 was shown to one group, and Image 2 with the pilotis space edited was shown to the other group. As an experiment to find objective evidences on Gordon Cullen's 'Space and Infinity', this study analyzed difference between Image 1 and Image 2, and it was found that the domain of pilotis showed a value five times higher than the average visual attention since it attracted much visual attention although it was very small in area. That is, it has objectively clarified that people get most fascinated with a place with infinite images in the background like a pilotis space out of all the urban landscapes as Gordon Cullen's theory. In addition, the differences in visual concentration of pilotis space by sex, by subject was examined, and there was no significant difference in visual concentration of pilotis space by gender. As a result of examining the difference of visual concentration by classifying the subjects into architectural related major, the major group showed higher frequency of viewing than the non - major group.