• Imaging Science in Dentistry
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• v.32 no.1
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• pp.11-18
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• 2002

Purpose: To evaluate cultured human artificial skin as an experimental model for studying radiation effects in vitro. Materials and Methods: The skin was constructed by culturing keratinocytes over collagen lattice which made by culturing fibroblasts. Two groups were irradiated to gamma rays at single dose of 25 Gy with or without 3.5% of DMSO. Ultrastructures were investigated by electron microscopy after irradiation. The number of epidermal layers and expression of cytokeratin (CK) 14 & 10 were also seem by light microscopy. Results: At 2 days after irradiation in experimental group without DMSO, necrotic cells were rarely found in the spinosal layer and undercornified cells were visible in the homey layer. Similar findings were also found in experimental group with DMSO but in mild form. The number of epidermal layers in experimental group without DMSO were significantly fewer than other group. CK 14 expressed in all the layer excluding homey layer but CK 10 expressed over 3∼4 basal layers. Such patterns of CK expression were similar to all groups. It is suggested that structures of the keratinocytes and epidermal formation could be disturbed by irradiation in artificial skin and that DMSO can protect these damages. Conclusion : Therefore this work could be used as an organotypic experimental model in vitro using human cells for studying radiation effect in skin. Furthermore structural findings provided in this study could be used as useful basic data in further study using this model.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.5 s.236
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• pp.663-670
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• 2005

DIN CK35 (JIS S35CK) steels have been used as a material in fuel pump blocks for marine engines. Failures in the inner surface of a drilling hole, due to the initiation of fatigue cracks have been frequently reported. However, the mechanism initiating these cracks and growths has not been clearly diagnosed yet. This study was conducted using a scraped fuel pump block, containing an initiated fatigue crack in the inner surface of a drilling hole. Initially, the cracks and fractured surfaces inside the block were investigated using an optical microscope and a SEM (Scanning Electron Microscope). In addition, microstructure observation, fatigue life test and fatigue crack growth test were performed using a specimen, which was taken from the same block. Results from these tests are summarized as follows; (1) The early crack in the block was supposed to occur inside the inner surface of the drilling hole. (2) The fatigue endurance of this material was about 330 Mpa. (3) The early crack was generated in the cavitations created by the breakdown of a big inclusion, or separation between the big inclusion and the base metal, in which the fundamental ingredients of the inclusion were C, 5, and Mn. (4) In order to prevent these types of failures, the suppression of inclusions inflow by improving the casting process, formation of fine inclusions by applying a heat treatment process, and coating of the surface of the drilling hole were required.

• Journal of Chest Surgery
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• v.24 no.5
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• pp.429-437
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• 1991

Beta hydroxytrimethylammonium butyrate[L-carnitine] is highly concentrated in myocardium and it is essential substance for transfer of fatty acids into the mitochondria. We respect that L-carnitine has protective action to myocardium during ischemia. I studied coronary flow and CK - MB isoenzyme of coronary effluent of Langendorff`s isolated rat heart model. As a control group 5 Sprague-Dowley species rat hearts were connected to Langendorff`s isolated rat heart model and perfused for 30 minutes with Kreb-Henseleit buffer solution. After cessation of perfusion for 30 minutes they were reperfused for 30 minutes. In experimental group 10 Sprague-Dowley species rat hearts were perfused with 10mmole /L of L-carnitine contained in Kleb-Henseleit buffer solution. In equilibrium state, coronary flow was 1.7 times greater in experimental group. During reperfusion, both group showed equally decreased flow amount of about 60% of that of equilibrium state. CK-MB isoenzyme level of perfused coronary fluid showed no significant difference in equilibrium state. In reperfusion. CK-MB isoenzyme levels of control group were 17.61$\pm$8. 68U/L at 25 minutes, 23.32$\pm$4.15U /L at 30 minutes; and in experimental group, 13.63$\pm$6. 08U/L at 15 minutes and 13.6$\pm$8.41U /L at 30 minutes respectively. Those values in both states showed significantly lower CK-MB level in experimental group. In conclusion, L-carnitine prevent ischemic myocardial damage during ischemic and reperfusion state of Langendorff`s isolated rat hearts and also I suggest the L-carnitine act potent coronary vasodilator during preischemic and postischemic states of rat hearts.

• IMMUNE NETWORK
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• v.7 no.3
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• pp.117-123
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• 2007

Background: This study was designed to investigate the role of the hepatocyte growth factor (HGF) with regards to differentiation of somatic stem cells originating from the human umbilical cord blood (UCB) into hepatic lineage cells in vitro culture system. Methods: Mononuclear cells from UCB were cultured with and without HGF based on the fibroblast growth factor (FGF)-1, FGF-2, and stem cell factor. The cultured cells were confirmed by immunofluorescent staining analysis with albumin (ALB), cytokeratin-19 (CK-19), and proliferating cell nuclear antigen (PCNA) MoAb. ALB and CK-18 mRNA were also evaluated by reverse transcription-polymerase chain reaction. In order to observe changes in proliferating capacity with respect to the cultured period, CFSE with affinity to proliferating cells were tagged and later underwent flow cytometry. Results: In the HGF-treated group, cultured cells had a large oval shaped appearance with adherent, but easily detachable characteristics. In the HGF-non treated group, these cells were spindle-shaped with strong adherent characteristics. Expressions of ALB and CK-19 were evident in HGF-treated group compared to non-expression of those in to HGF-non treated group. Dual immunostaining analysis of the ALB producing cells showed presence of PCNA in their nuclei, and ALB and CK-18 mRNA were detected on the 21st day of cultured cells in the HGF-treated group. Conclusion: Our findings suggest that HGF has a pivotal role in differentiating somatic stem cells of human UCB into hepatic lineage cells in vitro.

• Reproductive and Developmental Biology
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• v.37 no.4
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• pp.169-174
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• 2013

Sperm capacitation refers to polymerization of filamentous (F)-actin from globular (G)-actin. While the role of actin-related protein 2/3 (Arp2/3) complex in actin polymerization is well appreciated, the underlying mechanism(s) and its relationship with capacitation are poorly understood. Therefore, to evaluate the potential role of Arp2/3 complex on capacitation, bovine spermatozoa were incubated with multiple doses (1, 10 and $100{\mu}M$) of CK-636, an inhibitor of Arp2/3 complex with heparin. The cellular localization of the Arp2/3 complex in spermatozoa was identified by immunohistochemistry, whereas western blot was also applied to detect the protein tyrosine phosphorylation of sperm proteins. Additionally, sperm motility and kinematic parameters were evaluated using a computer-assisted sperm analysis system. CK-636 resulted in significant changes in the ratio of Arp2/3 complex localization between acrosome and equatorial region of the spermatozoa. Short-term exposure of spermatozoa to $100{\mu}M$ of CK-636 significantly decreased sperm motility, however a non-detectable effect on protein tyrosine phosphorylation was observed during capacitation. On the basis of these results, we propose that Arp2/3 complex is associated with morphological changes during capacitation and compromised sperm motility.

• Carbon letters
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• v.19
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• pp.99-103
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• 2016

Porous carbons have attracted much attention for their novel application in gas storage. In this study, porous graphite nano-fiber (PGNFs)-based graphite nano fibers (GNFs) were prepared by KOH activation to act as adsorbents. The GNFs were activated with KOH by changing the GNF/KOH weight ratio from 0 through 5 at 900℃. The effects of the GNF/KOH weight ratios on the pore structures were also addressed with scanning electron microscope and N₂ adsorption/desorption measurements. We found that the activated GNFs exhibited a gradual increase of CO₂ adsorption capacity at CK-3 and then decreased to CK-5, as determined by CO₂ adsorption isotherms. CK-3 had the narrowest micropore size distribution (0.6–0.78 nm) among the treated GNFs. Therefore, KOH activation was not only a significant method for developing a suitable pore-size distribution for gas adsorption, but also increased CO₂ adsorption capacity as well. The study indicated that the sample prepared with a weight ratio of ‘3’ showed the best CO₂ adsorption capacity (70.8 mg/g) as determined by CO₂ adsorption isotherms at 298 K and 1 bar.

• Journal of The Korean Society of Clinical Toxicology
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• v.2 no.2
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• pp.151-153
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• 2004

Causes of rhabdomyolysis can be divided into traumatic and nontraumatic, Among the nontraumatic rhabdomyolysis, it is known that ingestion of drugs is one of the common causes. However, there have been few reports that benzodiazepine overdose causes rhabdomyolysis, moreover there was no report about rhabdomyolysis after alprazolam overdose. We experienced a case of rhabdomyolysis after alprazolam overdose. A 51-year-old woman was brought to the emergency room 11 hours after ingestion of 30 tablets (15 mg) of alprazolam in a suicidal attempt. On admission she was comatose and her CK level was 8,290 lUlL. The CK level increased up to 25,598 IU/L 10 hours after admission, but she became alert on the third day. Subsequently the CK level decreased gradually with supportive care without renal impairment and she discharged from the hospital on the $10^{th}$ day. Although a pressure effect on the dependent portion of the body due to mental alteration before admission might have caused the rhabdomyolysis, the alprazolam, per se, cannat be ruled out for the cause.

• Journal of Microbiology and Biotechnology
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• v.16 no.7
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• pp.1047-1052
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• 2006

A bile salt hydrolase (BSH) was purified from Lactobacillus plantarum CK 102 and its enzymatic properties were characterized. This enzyme was successfully purified using ion-exchange chromatography with Q-Excellose and hydrophobic interaction chromatography with Butyl-Excellose. The purified enzyme showed a single protein band of 37 kDa by SDS-polyacrylamide gel electrophoresis, which was similar to the molecular weight of known BSHs. The amino acid sequence of GLGLPGDLSSMSR, determined by MALDI-TOF, was identical to that of BSH of L. plantarum WCFS1. Although this BSH hydrolyzed all of the six major human bile salts, glycine-conjugated bile acid was the best substrate, based on its specificity and $K_{m}$ value. Among the various substrates, the purified enzyme maximally hydrolyzed glycocholate with apparent $K_{m}$ and $V_{max}$ values of 0.5 mM and 94 nmol/min/mg, respectively. The optimal pH of the enzyme ranged from 5.8 to 6.3. This enzyme was strongly inhibited by thiol enzyme inhibitors such as iodoacetate and periodic acid.

• Journal of Internet Computing and Services
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• v.23 no.6
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• pp.1-13
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• 2022

As the information and communication environment develops, the environment of military facilities is also development remarkably. In proportion to this, cyber threats are also increasing, and in particular, APT attacks, which are difficult to prevent with existing signature-based cyber defense systems, are frequently targeting military and national infrastructure. It is important to identify attack groups for appropriate response, but it is very difficult to identify them due to the nature of cyber attacks conducted in secret using methods such as anti-forensics. In the past, after an attack was detected, a security expert had to perform high-level analysis for a long time based on the large amount of evidence collected to get a clue about the attack group. To solve this problem, in this paper, we proposed an automation technique that can classify an attack group within a short time after detection. In case of APT attacks, compared to general cyber attacks, the number of attacks is small, there is not much known data, and it is designed to bypass signature-based cyber defense techniques. As an attack model, we used MITRE ATT&CK® which modeled many parts of cyber attacks. We design an impact score considering the versatility of the attack techniques and proposed a group similarity score based on this. Experimental results show that the proposed method classified the attack group with a 72.62% probability based on Top-5 accuracy.

• Journal of Chest Surgery
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• v.36 no.11
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• pp.799-811
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• 2003

Background: The aim of this study is to define the cardioprotective effects (hemodynamic, cytochemical and ultrastructural of the newly developed Histidine-Tryptophan-Ketoglutarate (HTK) cardioplegia compared to DelNido cardioplegia. Material and Method: Seventy-nine isolated rat hearts were divided into three groups on the basis of techniques of cardioplegia infusion. Twenty-eight hearts (Group 1) were flushed with cold DelNido cardioplegia with every 40 minutes for 2 hours. Twenty-seven hearts (Group 2) were flushed with cold HTK cardioplegia for once during the 2 hours. Twenty-four hearts (Group 3) were flushed with cold HTK cardioplegia with every 40 minutes for 2 hours. Heart rate, left ventricular developed pressure (LVDP), changes of + dp/dt max, coronary flow, and rate-pressure product value were measured at pre-ischemic, post-reperfusion 15 minutes, 30 minutes, and 45 minutes for hemodynamic study. Aspartate aminotransferase (AST), lactate dehydrogenase (LD), creatine kinase (CK), CK-MB, troponin-I, myoglobin, and lactate were measured at pre-ischemic and post-reperfusion 45 minutes for cytochemical parameters. Mitochondrial scores were counted in 3 cases from each group for ultrastructural assessment. Result: In hemodynamic study, there were no significant differences among group 1, group 2, and group 3. However, the decrease values of heart rate in group 2 and 3 exhibited significantly lower values than in group 1. In cytochemical study, there were no significant differences among group 1, group 2, and group 3. However, the increase values of lactate in group 2 and 3 exhibited significantly lower values than in group 1. In ultrastructural assessment, the mean myocardial mitochondria scores in group 1, group 2, and group 3 were 2.14$\pm$0.10, 1.52$\pm$0.57, and 2.10$\pm$0.16. Conclusion: HTK solution provides adequate myocardial protection with some advantages over DelNido solution in isolated rat hearts.