• Korean Journal of Acupuncture
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• v.24 no.1
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• pp.171-187
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• 2007

Objectives : This study was performed to determine if Orostachys japonicus A. Berger herbal acupuncture (OjB) provides the protective effect against the loss of cell viability and DNA damage induced by oxidant in renal proximal tubular cells. Methods : The cell viability was evaluated by a MTT reduction assay and DNA damage was estimated by measuring double stranded DNA breaks in opossum kidney (OK) cells, an established proximal tubular cell line. Lipid peroxidation was determined by measuring malondialdehyde (MDA), a product of lipid peroxidation. Results : H2O2 increased the loss of cell viability in a time-dependent manner, which were prevented by 0.1% OjB. The protective effect of OjB was dose-dependent over concentration range of 0.05-0.5%. H2O2 caused ATP depletion and DNA damage, which were prevented by OjB and the hydrogen peroxide scavenger catalase. The loss of cell viability by H2O2 was not affected by the antioxidant DPPD, but lipid peroxidation by the oxidant was completely inhibited by DPPD. Generation of superoxide and H2O2 in neutrophils activated by phorbol-12,13-dibutyrate was inhibited by OjB in a dose-dependent manner. OjB inhibited generation of H2O2 in OK cells treated with antimycin A and exerted a direct H2O2 scavenging effect. Exposure of OK cells to 1 mM tBHP caused a significant depletion of glutathione which was prevented by OjB. OjB accelerated the recovery in cells cultured for 20 hr in normal medium without oxidant following oxidative stress. Conclusions : These results suggest that OjB exerts the protective effect against oxidant-induced cell injury and its protective effect was resulted from radical scavenging and antioxidant activities.

• Journal of Microbiology
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• v.43 no.4
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• pp.375-380
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• 2005

Autonomous ultradian metabolic oscillation (T$\simeq$50 min) was detected in an aerobic chemostat culture of Saccharomyces cerevisiae. A pulse injection of GSH (a reduced form of glutathione) into the culture induced a perturbation in metabolic oscillation, with respiratory inhibition caused by $H_2S$ burst pro-duction. As the production of $H_2S$ in the culture was controlled by different amino acids, we attempted to characterize the effects of GSH on amino acid metabolism, particularly with regard to branched chain and sulfur-containing amino acids. During stable metabolic oscillation, concentrations of intra-cellular glutamate, aspartate, threonine, valine, leucine, isoleucine, and cysteine were observed to oscil-late with the same periods of dissolved $O_2$ oscillation, although the oscillation amplitudes and maximal phases were shown to differ. The methionine concentration was stably maintained at 0.05 mM. When GSH (100 $\mu$M) was injected into the culture, cellular levels of branched chain amino acids increased dramatically with continuous $H_2S$production, whereas the cysteine and methionine concentrations were noticeably reduced. These results indicate that GSH-dependent perturbation occurs as the result of the promotion of branched chain amino acid synthesis and an attenuation of cysteine and methionine synthesis, both of which activate the generation of $H_2S$. In a low sulfate medium containing 2.5 mM sulfate, the GSH injections did not result in perturbations of dissolved $O_2$ NAD(P)H redox oscillations without burst $H_2S$ production. This suggests that GSH-dependent perturbation is intimately linked with the metabolism of branched-chain amino acids and $H_2S$ generation, rather than with direct GSH-GSSG redox control.

• Parasites, Hosts and Diseases
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• v.57 no.2
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• pp.83-92
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• 2019

Based on the reactive oxygen species (ROS) regulatory properties of diphenyleneiodonium (DPI), we investigated the effects of DPI on host-infected T. gondii proliferation and determined specific concentration that inhibit the intracellular parasite growth but without severe toxic effect on human retinal pigment epithelial (ARPE-19) cells. As a result, it is observed that host superoxide, mitochondria superoxide and $H_2O_2$ levels can be increased by DPI, significantly, followed by suppression of T. gondii infection and proliferation. The involvement of ROS in anti-parasitic effect of DPI was confirmed by finding that DPI effect on T. gondii can be reversed by ROS scavengers, N-acetyl-L-cysteine and ascorbic acid. These results suggest that, in ARPE-19 cell, DPI can enhance host ROS generation to prevent T. gondii growth. Our study showed DPI is capable of suppressing T. gondii growth in host cells while minimizing the un-favorite side-effect to host cell. These results imply that DPI as a promising candidate material for novel drug development that can ameliorate toxoplasmosis based on ROS regulation.

• The KIPS Transactions:PartD
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• v.8D no.4
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• pp.367-376
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• 2001

For the electronic map service by wireless, the existing map database cannot be used directly. This is because, the data volume of a map is too big to transfer by wireless and although the map is transferred successfully, the devices to display the map usually don’t have enough resources as the ones for desktop computers. It is also not acceptable to construct map database for the exclusive use of wireless service because of the vast cost. We propose new technique to generate a map for wireless service dynamically, from the existing map database. This technique includes the generalization method to reduce the map data volume and filtering method to guarantee that the data volume don’t exceed the limit of bandwidth. The generalization is performed in 3 steps :ㅁ step of merging the layers, a step of reducing the size of spatial objects, and a step of processing user interface. The filtering is performed by 2 module, counter and selector module. The counter module checks whether the data blume of generated map by generalization, exceeds the bandwidth limit. The selector module eliminates the excess objects and selects the rest, on the basis of distance.

• Korean Institute of Interior Design Journal
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• v.17 no.3
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• pp.86-93
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• 2008

The purpose of this study is to find out how the otherness philosophy reveals itself in the principle of F.O.A construction space creation. The traditional philosophy of totality is self-centered and thoughts are based on the subject. It couldn't escape from the world associated with the self, and has subordinated the other to the main body. But the philosophy of otherness transcends the subject, to the open, creative way of thinking which acknowledges deconstruction, decentralization, and non-hierarchy. This is very similar to contemporary architecture, which pursuits change, and also to the current state of society. In construction by the construction group F.O.A, which is doing notable activity this generation, there is an attempt to transcend the fixed subject which is seen in the otherness discussion, and realize recategorization by overcoming the boundaries of subject and object. First, by the realization of landscape architecture using a topographical folding technique, boundaries of the subject and object are demolished in the relationship of the landscape construction, and recategorization. Second, by breaking up the meaning of the surface which is a visual and physical boundary for both the internal and external, recategorization is being done. Third, by making the boundary between the interior and exterior indistinct, cognitive threshold is dissolved, and the relationship between the subject and object is being recategorization. In conclusion, we can see that the many recategorization phenomenons that are happening in the F.O.A construction show the otherness that escapes from the conventional and stationary relationship, and recognizes each other at the same time, forming new relationships.

• Korean journal of applied entomology
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• v.41 no.3
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• pp.211-216
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• 2002

The present study was aimed to examine the effect of different host plants on the biological property of cotton caterpillar, outbreak pest of cucurbit vegetables. The feeding and oviposition preferences toward cucumber and pumpkin were greater than those toward watermelon, oriental melon, and melon. The periods of egg and larva fed on oriental melon, melon, and pumpkin were longer than those on watermelon and cucumber. The longest pupal period was 10.5 days from cucumber. The hatching rate, pupation rate, emergence rate, and survival rate were observed from different host plants. The hatching rate was the highest on cucumber (87.2%) and the lowest on melon (72.8%). The pupation rate on watermelon and oriental melon (90.0% and 89.1%, respectively) was higher than that on cucumber (62.0%). The emergence rate on cucumber and pumpkin (93.5% and 92.0%, respectively) was higher than that on oriental melon (78.7%). The survival rate from hatching to emergence on watermelon (76.0%) was the highest, and the lowest on cucumber (50.0%). The adult period on melon (21.0 days) was the longest, and the shortest on cucumber (15.5 days) among 5 host plants. Average number of eggs per female on cucumber (281.8 eggs) was the highest, and the least on oriental melon (96.6 eggs). The survivorship on cucumber was the longest (30 days), and the shortest on pumpkin (17 days). The preoviposition period on oriental melon and melon (3.4 days) was longer than that on watermelon (2.1 days) and mean generation time in day (T) on melon was the longest (47.2 days) though they were not significant. The net reproductive rate per generation (R$_{o}$) on cucumber, 191.3, was the highest and the highest intrinsic rate of natural increase (r$_{m}$) was observed from cucumber as 0.127. All these results suggest that the growth ana reproduction of cotton caterpillar varies depending upon the kind of host plants. The analysis of the life table revealed that cucumber and pumpkin were the favorable host plants of cotton caterpillar.

• Journal of Ocean Engineering and Technology
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• v.15 no.3
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• pp.1-8
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• 2001

With uniform heat generation within the wall of the cylinder placed in a cross flow, heat flows by conduction in the circumferential direction due to the asymmetric nature of the fluid flow around the perimeter of the cylinder. The circumferential heat flow affects the wall temperature distribution to such an extent that in some cases significantly different results may be obtained for geometrically similar surfaces. In the present investigation, the effects of circumferential wall heat conduction on local convective heat transfer is investigated for the case of forced convection around horizontal cylinder in cross flow of air. Two-dimensional temperature distribution $T_w$/(${\gamma}$,${\theta}$) is presented through the numerical analysis. The one-dimensional and two-dimensional solutions are in good agreement with experimental results of local heat transfer coefficients.

• Nuclear Engineering and Technology
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• v.52 no.7
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• pp.1367-1379
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• 2020

The small modular sodium-cooled fast reactor (SMSFR) is an important component of Generation-IV reactors. The objective of this work is to improve the reactivity control in SMSFR by using innovative systems, including burnable poisons and optimized control rods. SMSFR with MOX fuel usually exhibits high burnup reactivity loss that leads to high excess reactivity and potential fuel melting in control rod withdrawal (CRW) accidents, which becomes an important constraint on the safety and economic efficiency of SMSFR. This work applies two types of burnable poisons in a SMSFR to reduce the excess reactivity. The first one homogenously loads minor actinides in the fuel. The second one combines absorber and moderators in specific assemblies. The influence of burnable poisons on the core characteristics is discussed and integrated into the analysis of CRW accidents. The results show that burnable poisons improve the safety performance of the core in a significant way. Burnable poisons also lessen the demand for the number, absorption ability, and insertion depth of control rods. Two optimized control rod designs with rare earth oxides (Eu₂O₃ and Gd₂O₃) and moderators are compared to the conventional design with natural boron carbide (B₄C). The optimized designs show improved neutronic and safety performance.

• Corrosion Science and Technology
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• v.18 no.1
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• pp.8-15
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• 2019

A high-temperature gas-cooled reactor (HTGR) is recognized as the best candidate reactor for next generation nuclear reactors. Helium is used to be the coolant in the core of the HTGR with temperature expected to exceed $900^{\circ}C$ at the core outlet. Several iron- and nickel-based superalloys, including Alloy 800H, Hastelloy X, and Alloy 617, are potential structural materials for intermediate heat exchanger (IHX) in an HTGR. Oxidation behaviors of three selected alloys (Hastelloy X, Alloy 800H, and Alloy 617) were investigated at four different temperatures from $650^{\circ}C$ to $950^{\circ}C$ under helium environments with various concentrations of $O_2$ and $H_2O$. Preliminary results showed that chromium oxide as the primary protective layer was observed on surfaces of the three tested alloys. Based on results of mass gain and SEM analyses, Hastelloy X alloy exhibited the best corrosion resistance in all corrosion tests. Further details on the oxidation mechanism of these alloys are presented in this study.

• Journal of Environmental Science International
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• v.25 no.6
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• pp.829-837
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• 2016

The mechanism of micro-bubble generation with a pump is not clarified yet, so the design of water treatment systems with a micro-bubble generating pump is based on trial and error methods. This study tried to explain clearly quantitative relationships of experimental micro-bubble concentration ($C_{air}$) of continuous operation tests with a micro-bubble generating pump and theoretical air solubility. Operation parameters for the tests were discharge pressure ($P_g$), water ($Q_{w0}$) and air ($q_0$) flow rates, orifice diameter ($D_o$), and retention time (t). The experimental micro-bubble concentrations ($C_{air}$) at 4.8 atm of discharge pressure ($P_g$) were in the range of 21.04 to 25.29 mL/L. When the retention time (t) by changing the pipe line length ($L_p$) increased from 1.22 to 6.77s, the experimental micro-bubble concentrations ($C_{air}$) increased from 25.86 to 30.78 mL air/L water linearly. The dissolved and dispersed micro-bubble concentrations ($C_{air}$) are approximately 4 times more than the theoretical air solubility.