• Environmental Analysis Health and Toxicology
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• v.21 no.2 s.53
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• pp.127-138
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• 2006

In urban areas, diesel exhaust particles (DEP) are probably a major component of particulate matters, especially in Korea where drive many diesel vehicles. The aim of this study was to investigate genotoxic effects of DEP using single ceil gel electrophoresis. In order to evaluate the mechanisms of DEP genotoxicity, the rat microsome mediated and DNA repair enzyme treated comet assays together with conventional comet assay were performed. Total diesel particles (DEPT) was collected without site fractionation from diesel engine bus and dichloromethane extract was obtained. The organic extract of DEPT revealed DNA damage itself in NIH/3T3 cells. The level of DNA breaks plus oxidative DNA lesions and microsome mediated DNA damage was assessed by modified single cell gel eletrophoresis. DEPT was able to induce oxidative DNA damage as well as microsome mediated DNA damage. Vitamin C as an model antioxidant reduced DNA damage in endonuclase III treated comet assay. One of flavonoid, galangin as a CYP1A1 inhibitor. reduced DNA damage in the presence of S-9 mixture. $DEP_T$ is the sources of oxidative stress, but antioxidants can significantly reduce oxidative DNA dmage. And $DEP_T$ may contain indirect mutagens which can be inhibited by CYP1A1 inhibitors. The ethanol extracts of the mixed vegetables (BV) or the mixed fruits (BF) were evaluated for their in vitro antigenotoxic effects. BV and BF showed potent Inhibitory effects against DEPT induced DNA damage with oxidative DNA lesions and in the prescence of S-9 mixture. These results indicate that BV and BF could prevent cellular DNA damage by inhibiting oxidative stress and suppressing cytochrome P4501A1 in cell culture.

• Journal of Energy Engineering
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• v.12 no.2
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• pp.154-163
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• 2003

Grid connection essentially requires a wind energy conversion system (WECS) to not only supply adequate power responding to constantly varying wind speed but also provide a specified level of voltage magnitude and frequency that is acceptable in the electric power network. To satisfy such requirements, appropriate control schemes of a wind turbine to be connected to the power grid should be employed. This paper presents an output control strategy of a grid-connected wind power generation, which consists of a fixed-pitch wind turbine, a synchronous generator and a AC-DC-AC component with a voltage source inverter built in, and performs modelling and analysis of the strategy using PSCAD/EMTDC, an electromagnetic transient analysis software. Real power output control of the voltage source inverter is implemented to extract the maximum energy from wind speed inputted through wind blades and reactive power control, to keep the terminal voltage of WECS at a specific level. SPWM switching method is used to reduce the harmonics and maintain 60 ㎐ of the output frequency. The wind turbine performance and output corresponding to wind variation and the terminal load change is simulated and analysed.

• Journal of the Korean Ceramic Society
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• v.51 no.3
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• pp.162-169
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• 2014

This paper introduces a microwave-assisted synthesis method to prepare hybrid $Bi_2Se_3-GR/TiO_2$ nanocomposites, which exhibit superior properties over single component materials. The as-prepared composites were characterized by XRD, UV-vis absorbance spectra, SEM,TEM, EDX, and BET analyses, revealing uniform covering of the graphene nanosheet with $Bi_2Se_3$ and $TiO_2$ nanocrystals. For visible light photocatalysis of Rh.B, a significant enhancement in the reaction rate was consequently observed with $Bi_2Se_3-GR/TiO_2$ composites. The degradation rate($k_{app}$) obtained for sonophotocatalysis was $6.8{\times}10^{-3}min^{-1}$, roughly 2.2 times better than that of VL photocatalysis under higher concentrations of Rh.B. The sonophotocatalysis was faster due to greater formation of reactive radicals as well as an increase of the active surface area of the $Bi_2Se_3-GR/TiO_2$ composites. The high activity is attributed to the synergetic effects of high charge mobility and red shift of the absorption edge of $Bi_2Se_3-GR/TiO_2$.

• Toxicological Research
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• v.34 no.3
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• pp.267-279
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• 2018

Neurolathyrism is a neurodegenerative disorder characterized by spastic paraplegia resulting from the excessive consumption of Lathyrus sativus (Grass pea). ${\beta}$-N-Oxalyl-L-${\alpha},{\beta}$-diaminopropionic acid (L-ODAP) is the primary neurotoxic component in this pea. The present study attempted to evaluate the proteome-wide alterations in chick brain 2 hr and 4 hr post L-ODAP treatment. Proteomic analysis of chick brain homogenates revealed several proteins involved in cytoskeletal structure, signaling, cellular metabolism, free radical scavenging, oxidative stress and neurodegenerative disorders were initially up-regulated at 2 hr and later recovered to normal levels by 4 hr. Since L-ODAP mediated neurotoxicity is mainly by excitotoxicity and oxidative stress related dysfunctions, this study further evaluated the role of L-ODAP in apoptosis in vitro using human neuroblastoma cell line, IMR-32. The in vitro studies carried out at $200{\mu}M$ L-ODAP for 4 hr indicate minimal intracellular ROS generation and alteration of mitochondrial membrane potential though not leading to apoptotic cell death. L-ODAP at low concentrations can be explored as a stimulator of various reactive oxygen species (ROS) mediated cell signaling pathways not detrimental to cells. Insights from our study may provide a platform to explore the beneficial side of L-ODAP at lower concentrations. This study is of significance especially in view of the Government of India lifting the ban on cultivation of low toxin Lathyrus varieties and consumption of this lentil.

• Korean Journal of Pharmacognosy
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• v.36 no.4 s.143
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• pp.324-331
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• 2005

The roots of Rosa rugosa have been used to treat diabetes mellitus in the folkloric society of Korea. To demonstrate the active component for the rat obesity induced by high fat diet for 6 weeks, the phytochemical fractionation and the pharmacological activity test were performed on this crude drug. It was shown that the methanolic extract and its EtOAc fraction inhibited the weight increase of the rat body, abdominal fat pad and hyperlipidemia at 200 mg/kg dose. Further, the triterpenoids, euscaphic acid and tormentic acid, isolated from R. rugosa roots were active at 30 mg/kg in the same assay. The two components shifted serum total-, HDL, and LDL-cholesterol levels toward the values of the unteated group, suggesting that the active compounds has hypolipidemic effects. The rats fad euscaphic acid and tormentic acid also reduced thiobarbituric acid-reactive substance (TBARS) and hydroxyl radical in the rat blood and increased superoxide dismutase activity compared to the control. TBARS values and carbonyl contest of the hepatic protein were reduced by treatment with the two triterpenoids. Antioxidative enzyme (SOD, glutathione peroxidase, and catalase) activities in hepatic were increased by treatment of rats with the triterpenoids, which suggests that triterpenoids inhibited the reduction of hepatic antioxidative activity caused by high fat diet. Taken together, these results support that euscaphic acid and tormentic acid improve a high fat diet-induced hyperlipidemia via the activation of antioxidative mechanism.

• Natural Product Sciences
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• v.19 no.1
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• pp.54-60
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• 2013

Rhus verniciflua Stokes (Anacadiaceae) is a plant that is native to East Asian countries, such as Korea, China, and Japan, and it has been found to exert various biological activities including antioxidative, anti-aggregatory, anti-inflammatory, anti-mutagenic, and apoptotic effects. Sulfuretin is one of the major flavonoid component isolated from the heartwood of R. verniciflua. Reactive oxygen species (ROS), produced via dental adhesive bleaching agents and pulpal disease, can cause oxidative stress. In the present study, we isolated sulfuretin from R. verniciflua and demonstrated that sulfuretin possesses cytoprotective effects against hydrogen peroxide ($H_2O_2$)-induced dental cell death. $H_2O_2$ is a representative ROS and causes cell death through necrosis in human dental pulp (HDP) cells. $H_2O_2$-induced cytotoxicity and production of ROS were blocked in the presence of sulfuretin, and these effects were dose dependent. Sulfuretin also increased heme oxygenase-1 (HO-1) protein expression. In addition, to determine whether sulfuretin-induced HO-1 expression mediated this cytoprotective effect, HDP cells were cotreated with sulfuretin in the absence or presence of SnPP, an inhibitor of HO activity. Sulfuretin-dependent HO-1 expression was required for suppression of $H_2O_2$-induced HDP cell death and ROS generation. These results indicate that sulfuretin-dependent HO-1 expression was required for the inhibition of $H_2O_2$-induced cell death and ROS generation. In addition, sulfuretin may be used to prevent functional dental cell death and thus may be useful as a pulpal disease agent.

• Journal of Korean Society on Water Environment
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• v.22 no.5
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• pp.943-951
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• 2006

Spatial distribution of water pollution in the Gap Stream was investigated from October to November, 2005. Sampling was conducted three times including effluents discharged from a wastewater treatment plant (WWTP) and a dam reservoir during the low-flow period. As a typical urban stream, total nitrogen and inorganic nitrogen concentrations increased toward downstream. Ammonia concentration was the highest in the treated water of the wastewater treatment plant and the lowest nitrate concentration was found in the effluent of the dam reservoir. A part of soluble reactive phosphorous (SRP) in total phosphorous was 22~54% in the upstream reach of WWTP in the Gap Stream whereas 68~73% in the downstream reach. Mean chlorophyll-a concentration ranged from 1.6 to $11.0{\mu}g/L$ and it tends to increase toward downstream except for WWTP effluent. As expected, untreated wastewater and WWTP effluent were suggested as the major sources of water pollution in the Gap Stream. In this study, the water pollution of the Gap Stream is a significant undergoing typical eutrophication, caused by excessive phosphorus and nitrogen nutrients from WWTP located in the watershed. As a result, the critical factor for the water pollution was evaluated to dissolved inorganic nitrogen and phosphorus nutrients. Particularly, SRP is a most important for the eutrophication. It suggest that may occur in the most urban streams of Korean peninsula. Therefore, because the necessity of water pollution management in the urban stream, inorganic N and P nutrients should be included as an essential component of water quality criteria in the advanced water quality project of Korean Government by enforcing of water quality assessment and total maximum daily loads (TMDLs).

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.4 no.1
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• pp.113-119
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• 2001

Mesenchymal hamartoma is an uncommon benign tumor usually found in childhood, especially during the first two years of life. The tumor consists of a solid component and multiple cyst. Without treatment, these lesions can grow to an enormous size. We experienced a case of mesenchymal hamartoma which was found incidentally, in a 8 month old girl who had ascending cholangitis after Kasai operation due to biliary atresia. On abdominal ultrasonography and CT, there was a well-defined homogeneous small echogenic mass in the right lobe of the liver with cirrhosis. Five months later, she underwent liver transplantation. Gross picture of the resected liver showed a dark greenish pigmented solid mass in the right lobe of the cirrhotic liver. Microscopic findings showed reactive mesenchyma and epithelial overgrowth.

• Korean Journal of Materials Research
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• v.5 no.8
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• pp.960-965
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• 1995

Hard Ti(C, N) layers of various compositions were coated on ASP30 tool steel employing a reactive HCD ion plating technique. The effect of film composition on the wear characteristics were investigated in lights of hardness, adhesion and wear mechanism. With an increase in the amount of nonmetallic component(N, C), the hardness of films increased, but the increase in carbon content resulted in poor adhesion. Within the concentration range of ([C+N]/Ti<1), these trends became mute clear than in the concentration below stoichiometry. Therefore, the wear resistance could be maximized when the film is deposited with the concentration of ([C+N]/Ti<1) for high microhardness and, at the same time, with the low carbon contents not to wear out in adhesive mode.

• Journal of The Korean Society of Integrative Medicine
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• v.8 no.3
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• pp.133-142
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• 2020

Purpose : The purpose of this study was to investigate the differences in social quotient and sensory processing function between completed-toileting and incomplete-toileting children with autism spectrum disorder (ASD). We aims to provide a basis for the training of children with autism spectrum disorders. Methods : The subjects of this research were children with ASD, aged from 4 to 7, receiving sensory integration therapy at the H-Child Development Research Center in Busan, South Korea. After recruiting 30 parents who had children with ASD, we interviewed them and we divided their children into completed-toileting group and incomplete-toileting group based on the past researches. We assessed them using the Social Maturity Scale and Sensory Profile. Spearman correlation was used to analyze between the sensory processing score and social quotient. Mann-Whitney U test was used to compare the Sensory Profile scores of the two groups. Results : The social quotient was correlated with the sensory processing score in the most of component as for auditory processing, vestibular processing, touch processing, multisensory processing, orosensory processing, except for visual processing. The groups of completed-toileting and incomplete-toileting group showed statistically significant intergroup difference in sensory seeking, emotional reactive, oral-sensory sensitivity, and inattention/distractibility in the sensory factor region. No statistically significant difference from intergroup was observed in any modulation areas, nor in behavioral & emotional response domains. Conclusion : A significant intergroup difference was observed in the most of sensory processing areas, except for modulation areas and behavioral & emotional response domains. The result revealed that toileting is significantly correlated with sensory processing. Therefore, this study suggests that the sensory processing function should be considered in the toilet training of children with ASD.