• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.4
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• pp.609-614
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• 2009

A fuel-cell power system among various alternative power sources has many advantages such as comparatively independable circumstances, high-efficient, and heat-recyclable, thus it is now able to be up to hundreds MWh-scaled through improving feasibility and longevity of it. During the last few decades, numerous research results has been investigated to expand interest in fuel-cell technology. This study presents pressure distribution on the geometrical manifold structures, which are U-type and Z-type, of a planar-type fuel-cell stack by simulated with computational fluid dynamics(CFD). Then, electrical performance of a 200W fuel-cell stack, which is U-type, was diagnosed after pre-conditioning operation. The stack has electrical characteristics ; 22V, 10A, 220W, and current density $200mA/cm^2$.

• Journal of Biomedical Engineering Research
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• v.10 no.2
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• pp.195-202
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• 1989

Chinese Hamster Ovary( CHO) cells were cultured on the surface-modified polymers described in the previous study( "Polymer Surfaces for Cell Adhesion. 1. Surface Modification of Polymers and ESCA Analysis, " J. of KOSOMBE, Vol. 10, No. 1, 43-51, 1989). Among the physicochemical treatment methods. the chloric acid treatment was found to be the best method of rendering the polymer surfaces adhesive for CHO cells probably due to the high density of hydroxyl groups on the surface. Among the biological methods, the fibronectin treatment was best for CHO cell-compatibility probably due to specific active sites existed on the tell-binding domains of the fibronectin structure. When we compare the cell-compatibility of the chloric acid - and the fibronectin -treated PET surfaces, the number of cells attached on the surfaces were increased by 460.5 % and 559.0 % and, respectively, after 32 hr CHO cell culture, compared to that of untreated PET.eated PET.

• Journal of the Korean Institute of Telematics and Electronics
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• v.24 no.6
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• pp.1074-1079
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• 1987

We present a fast, constructive algorithm for the automatic placement of standard cells, which consists of two steps. The first step is responsible for cell-row assignment of each cell, and converts the circuit connectivity into a multi-stage graph under to constraint that sum of the cell-widths in each stage of the multi-state graph does not exceed maximum cell-row width. Generatin of feed-through cells in the final layout was shown to be drastically reduced by this step. In the second step, the position of each cell within the row is determined one by one from left to right so that the cost function such as the local channel density is minimized. Our experimental result shows that this algorithm yields near optimal results in terms of the number of feed-through cells and the horizontal tracks, while running about 100 times faster than other iterative procedures such as pairwise interchange and generalized force directed relaxation method.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.28 no.1
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• pp.150-165
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• 2002

The purpose of this study was to evaluate bacteriocin activity against human flora. Lactobiocin, a bacteriocin produced by Lactococcus sp. HY 449, inhibited the growth of Starphylococcus epidermidis, Starphylococcus aureus, Streptoccoccus pyogenes and Propionibacterium acnes. When crude bacteriocin was added to indicator cells during logarithmic growth, the optical density(O.D 650nm) of cells without bacteriocin increase after 5h of incubation. Whereas in the presence of bacteriocin, the O.D of cell suspensions decreased. The similar patterns were observed for absorbance readings at 280 nm and 260 nm. The release of cellular components when cell were treated with Lactobiocin suggests some degree of membrane damage or cell lysis. Scanning electron microscopy of cells following treatments with Lactobiocin in PBS buffer revealed disruptures of cell morphology. These results indicate that bacteriocin appears to cause cell lysis of tested strains. In cytotoxicity on human fibroblast, LD$\_$50/ of Lactobiocin was ca. 50 mg/ml and no change was observed cell proliferation at the same concentration. Any irritation and allergic reaction did not observed when evaluated by human patch test for Lactobiocin.

• Journal of Acupuncture Research
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• v.20 no.2
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• pp.135-144
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• 2003

Objective : The purpose of this study is To investigate the effects of acupuncture and moxibustion at Zusanli(ST36) and Weishu(BL21) Methods : serum gastrin level by radioimmunoassay was measured at 5 days after acupuncture and moxibustion of those acupoints. Gastric endocrine cell(G cell and Histamine immunoreactive density) by avidin-biotinylated complex(ABC) technique, histological examinations(Alcian Blue-PAS Stain; Alcian blue-Periodic Acid Schiff reagent) of the gastric mucosa were also performed. Acupuncture applied to the ST36 acupoint increased gastrin level of serum, but moxibustion did not produced significant effect. All of acupuncture and moxibustion at BL21 acupoint increased gastrin level of serum significantly. In moxibustion at ST36 and BL21, the number of gastrin secreting cells in gastric mucosa, the density of immunoreactive histamin secreting cells and the density of body mucosa stained by PAS were decreased compare to acupuncture at ST36 and BL21. In acupuncture and moxibustion at BL21, the density of pylorus mucosa stained by PAS were increased compare to the groups applied to ST36. In the density of body mucosa stained by AB, moxibustion at BL21 and ST36 were increased compare to the other groups. Results : These data suggest that acupuncture and moxibustion at BL21 increased gastrin level of serum and those effects were more potent than acupuncture at ST36.

• Journal of Environmental Science International
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• v.9 no.6
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• pp.463-468
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• 2000

Ther effect of UV on the mortality rate of toxic dinoflagellate Amphidinium Carterae causing a red tide in the coastal area of korea was investigated in the batch and continuous-scale reactor equipped with ultraviolet irradiation-apparatus. Degussa P(sub)25 titanium oxide, a photocatalyst proved to be effective of the mortality of Amphidinium Carterae supplied with photocatalyst and UV radiation were greater than 95% in 2 minutes of UV radiation and the rate were higher than that by UV-radiation without titanium dioxide in the batch and continuous-flow scale reactor, The mortality time of Amphidinium Carterae increased with the cell density under UV-illumination in the batch scale reactor. The mortality rate in the density of $5.0$\times$10^4$ cell/mL at the same experimental condition was more than 90% in 4 minutes in the continuous flow scale reactor. The percentage of 99.9$\pm$0.1% of Amphidinium Carterae in the density of $0.5$\times$10^4$ cells/mL was died in 20 minutes when the phytoplankton was illuminated with UV-radiation without photocatalyst.

• The Korean Journal of Physiology and Pharmacology
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• v.6 no.4
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• pp.183-186
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• 2002

Ischemic damage is one of the most serious problems. The openers of KATP channel have been suggested to have an effect to limit the ischemic damage. However, it is not yet clear how KATP channels of a cell correspond to hypoxic damage. To address the question, N2a cells were exposed to two different hypoxic conditions as follows: 6 hours hypoxia followed by 3 hours reperfusion and 12 hours hypoxia followed by 3 hours reperfusion. As the results, 6 hours hypoxic treatment increased glibenclamide- sensitive basal $K_{ATP}$ current activity (approximately 6.5-fold at 0 mV test potential) when compared with nomoxic condition. In contrast, 12 hours hypoxic treatment induced a relatively smaller change in the $K_{ATP}$ current density (2.5-fold at 0 mV test potential). Additionally, in experiments where $K_{ATP}$ channels were opened using diazoxide, the hypoxia for 6 hours significantly increased the current density in comparison to control condition (p＜0.001). Interestingly, the augmentation in the $K_{ATP}$ current density reduced after exposure to the 12 hours hypoxic condition (p＜0.001). Taken together, these results suggest that $K_{ATP}$ channels appear to be recruited more in cells exposed to the 6 hours hypoxic condition and they may play a protective role against hypoxia-reperfusion damage within the time range.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.526-526
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• 2012

DC magnetron discharges were studied using three-dimensional self-consistent particle-in-cell and Monte Carlo collisional (PIC-MCC) simulation codes. Two rectangular sputter sources (120 mm * 250 mm and 380 mm * 200 mm target sizes) were used in the simulation modeling. The number of incident ions to the Cu target as a function of position and simulation time was obtained. The target erosion profile was calculated by using the incident ions and the sputtering yields of the Cu target calculated with SRIM codes. The maximum ion density of the ion density distribution in the discharge was about $10^{10}cm^{-3}$ due to the calculation speed limit. The result may be less than one or two order of magnitude smaller than the real maximum ion density. However, the target erosion profiles of the two sputter sources were in good agreement with the measured target erosion profiles except for the erosion profile near the target surface, in which which the measured erosion width was broader than the simulation erosion width.

• Biomedical Science Letters
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• v.15 no.1
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• pp.25-29
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• 2009

The changes on the regional distributions and frequencies of somatostatin-immunoreactive (IR) cells in the fundus and pylorus of the stomach of osteoporotic Sprague-Dawley rats induced by ovariectomy were studied by immunohistochemical methods. The experimental animals were divided into two groups, one for non-ovariectomized group (Sham) and the other for ovariectomized group (OVX). Samples were collected from the fundus and pylorus regions at the 10 th week after ovariectomy or sham-operation. Somatostatin-IR cells were observed in both regions of the stomach regardless of ovariectomy. Most of these IR cells in the mucosa of the fundus or pylorus were generally spherical or spindle in shape (open type cell) while cells found in the gastric gland regions were round in shape (close type cell). Significantly lower number (P<0.01) of somatostatin-IR cells were detected in OVX as compared with Sham in the fundus and pylorus. In the present study, the density of somatostatin in the stomach was markedly decreased. Therefore, these changes in density of somatostatin-IR cells detected in this study may support the speculation that the development of gastrointestinal symptoms in osteoporosis such as impairments of calcium and some lipids, frequently encountered in patients with postmenopausal osteoporosis because the changes in gastrointestinal endocrine density would reflect the change in the capacity of producing these hormones and regulating gut motility and digestion.

• Transactions of the Korean hydrogen and new energy society
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• v.21 no.2
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• pp.111-116
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• 2010

In this study, the structural analysis was performed to optimize the membrane humidifier with hollow fiber membrane for polymer electrolyte membrane fuel cell system. The main design factors were considered by evaluating the humidifying performance according to various structural parameters such as packing density and length. The effects of operation conditions of membrane humidifier were also elucidated experimentally. Results imply that there are optimum points for the packing density and length of humidifier. It was also found that among operation conditions, relative humidity of wet exhaust gas and temperature of dry inlet gas have major effects on the humidifying performance.