• Journal of Korea Foundry Society
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• v.23 no.3
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• pp.137-146
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• 2003

The main purpose of this study is to investigate the effects of process parameter on alpha-case formation of Ti and TiAl castings. The previous studies showed that the molten titanium is excessively reactive to the refractory oxide mold, resulting in alpha-caes of the titanium castings regardless of composition of titanium alloys. However, the behavior of the alpha-case formation of TiAl alloy is not consistent with conventional titanium alloy. In order to investigate the alpha-case formation of Ti and TiAl castings with process parameter, especially the associated factors of investment mold such as mold material, binder and mold preheating temperature. An attempt has been made to characterize the alpha-case of titanium casting by using optical microscope, EDS, XRD, EMPA and hardness profiles. The formation of the alpha-case on the surface of pure titanium during investment casting was rather by that of solid solution with metallic element from mold material. The required mold strength was obtained with $CaZrO_3$ because of the possibility of using water soluble binder. However, the separation phenomenon between facing and back-up mold materials should be considered. The interfacial reaction of TiAl alloy showed different behavior from that of pure titanium and $Al_2O_3$ was best mold materials. The effect of binder as well as mold material on the formation of alpha-case was significant.

• Korean Journal of Clinical Laboratory Science
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• v.46 no.3
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• pp.91-98
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• 2014

Primary gastric lymphoma (PGL) is derived from mucosa-associated lymphoid tissue (MALT) and it differs from nodal lymphoma in histologic features and biologic behavior. Recent studies have showed that Helicobacter pylori (H.pylori ) infection is closely related to the development of low grade gastric lymphoma, and eradication of the infection induces regression of the tumor. H. pylori infection is known to be important to the development of gastric MALT lymphoma. The aim of this study was to elucidate the histopathological behavior of PGL according to the concept of MALT and to compare the predictive value of tests frequently used for diagnosis of H. pylori. The histological features of gastric lymphoma arising from MALT are the replacement of glands by uniform dense infiltration of centrocyte-like cells in the lamina propria and lymphoidepithelial lesion. H. pylori-associated histologic changes of neutrophilic infiltration, lymphoid follicle or aggregates formation and intestinal metaplasia, and H. pylori immunoreactivity were analyzed. Detection of H. pylori in chronic active gastritis and peptic ulcer suggests a possible role of H. pylori in the pathogenesis. Giemsa, Toluidine blue and Long H&E stains were used in H. pylori detection. Histopathological examination of gastric biopsy specimens revealed lymphoepithelial lesions pathognomonic of MALT lymphoma, and immunohistochemical staining for CD20 was diffusely positive. CD3 was positive in reactive T cells. PAX-5 was negative except the follicle. Bcl-2, cytokeratin, Ki-67, and c-myc were positive. The findings may indicate a predictable transition of low grade to high grade, and c-myc may be used as a valuable marker before molecular pathology diagnosis.

• Journal of the Korean institute of surface engineering
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• v.54 no.5
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• pp.230-237
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• 2021

In this study, the influence of silicon contents on the microstructure, mechanical and tribological properties of Ti-Al-Si-N coatings were systematically investigated for application of cutting tools. The composition of the Ti-Al-Si-N coatings were controlled by different combinations of TiAl₂ and Ti₄Si composite target powers using an arc ion plating technique in a reactive gas mixture of high purity Ar and N₂ during depositions. Ti-Al-Si-N films were nanocomposite consisting of nanosized (Ti,Al,Si)N crystallites embedded in an amorphous Si₃N₄/SiO₂ matrix. The instrumental analyses revealed that the synthesized Ti-Al-Si-N film with Si content of 5.63 at.% was a nanocomposites consisting of nano-sized crystallites (5-7 nm in dia.) and a three dimensional thin layer of amorphous Si₃N₄ phase. The hardness of the Ti-Al-Si-N coatings also exhibited the maximum hardness value of about 47 GPa at a silicon content of ~5.63 at.% due to the microstructural change to a nanocomposite as well as the solid-solution hardening. The coating has a low friction coefficient of 0.55 at room temperature against an Inconel alloy ball. These excellent mechanical and tribological properties of the Ti-Al-Si-N coatings could help to improve the performance of machining and cutting tool applications.

• BMB Reports
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• v.55 no.4
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• pp.181-186
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• 2022

Ventriculomegaly induced by the abnormal accumulation of cerebrospinal fluid (CSF) leads to hydrocephalus, which is accompanied by neuroinflammation and mitochondrial oxidative stress. The mitochondrial stress activates mitochondrial unfolded protein response (UPRmt), which is essential for mitochondrial protein homeostasis. However, the association of inflammatory response and UPRmt in the pathogenesis of hydrocephalus is still unclear. To assess their relevance in the pathogenesis of hydrocephalus, we established a kaolin-induced hydrocephalus model in 8-week-old male C57BL/6J mice and evaluated it over time. We found that kaolin-injected mice showed prominent ventricular dilation, motor behavior defects at the 3-day, followed by the activation of microglia and UPRmt in the motor cortex at the 5-day. In addition, PARP-1/NF-κB signaling and apoptotic cell death appeared at the 5-day. Taken together, our findings demonstrate that activation of microglia and UPRmt occurs after hydrocephalic ventricular expansion and behavioral abnormalities which could be lead to apoptotic neuronal cell death, providing a new perspective on the pathogenic mechanism of hydrocephalus.

• Journal of The Korean Society of Integrative Medicine
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• v.9 no.3
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• pp.47-58
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• 2021

Purpose : This study aimed to investigate the association between asthma and oral health and factors influencing asthma in adults. We also investigated whether asthma is related to mental health and physiological factors of blood. Methods : Data from 12,639 adults was taken from the 7th period (2016~2018) Korea National Health and Nutrition Examination Survey and analyzed using with SPSS 22.0 statistical program. Statistical analysis of data included frequency analysis, cross-analysis, and logistic regression analysis. For continuous data, an independent sample t-test was performed. The statistical significance level was defined as 0.05. Results : The probability of asthma occurrence was statistically different within general characteristics (gender, age, school grade, income, and drinking). By independent variables in a logistic regression analysis, the asthma diagnosis group had more people with speech discomfort (OR=1.37), chewing discomfort (OR=1.29), and oral pain (OR=.73). We found that people with asthma had a more unfavorable perception of their health (OR=1.73), suffered more depression (OR=.45), stress (OR=.66), and limited activity (OR=2.38). Moreover, the white blood cell count (OR=1.10) and high sensitivity C-reactive protein test (OR=1.06) also showed higher values than the control group. Conclusion : Our study showed that oral health and mental health were associated with the asthma, and influencing factors were oral health and behavior and mental health-related characteristics. Therefore, it is necessary to understand asthma-related risk factors for oral health and recognize the importance of systematic oral care education and regular dental visits for patients receiving asthma treatment. Thus, this study provides valuable insights on appropriate oral health management and prevention of asthma in patients.

• Journal of Distribution Science
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• v.12 no.9
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• pp.101-112
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• 2014

Purpose - Recently, although corporate social responsibility activities have been increasing in size, they do not have to achieve qualitative improvements and can be passive and cost consuming. Therefore, companies should make quantitative as well as qualitative improvements in their efforts in corporate social responsibility activities. In this study, the classification of social responsibility activities in a variety of studies was analyzed through a more specific path than in previous studies. Corporate behavior image, social behavior image, and corporate contributions image were analyzed through a more detailed analysis of performance. This study suggests that more detailed and concentrated social responsibility activities be pursued by forming companies. Research design, data, and methodology - The purpose of study is to gauge the corporate need for a more intensive, specific area of CSR activities. For this purpose, the sample of consumers that were targeted for CSR activities, recognized as 261 persons, have been investigated. Through a theoretical discussion on previous research, nine hypotheses were established on corporate image, the influence of corporate performance on CSR, and the CSV regulation effect. In order to test the hypothesis, a survey was conducted on 261 male and female consumers who were targeted for CSR, being persons in their 20s to 40s. PASW Statistics 18.0 and AMOS 18.0 were used for statistical analysis. Results - Corporate behavior image was formed through legal responsibility activities and economic responsibility activities. In addition to economic responsibilities, ethical responsibilities and environmental responsibilities were confirmed to have influence on social behavior image. Corporate social responsibility and philanthropic responsibility were confirmed to have influence on economic contribution image. Corporate image has positive effects on brand attitude, corporate reputation, and corporate competition. In addition, when CSV awareness is high, consumers perceive corporate image only through economic responsibility. However, when CSV awareness is low, economic responsibility as well as legal responsibility through charitable activities form the corporate image that influences the brand attitude and corporate reputation, as well as corporate competitiveness. It would appear that the area of corporate social responsibility needs more intensive management for corporate image and corporate competitive advantage. Conclusion - First, the findings of this study show that each CSR activity has a different effect on corporate image and thus, the corporate image influences corporate performance in distinct ways, depending on the CSR activity. This implies that reactive strategies should be tailored to the required image. Second, there is a difference in CSV awareness between groups. When the CSV awareness is low, we can confirm that legal responsibility activities have an especially significant effect on corporate image, implying that corporations should pursue their economic objectives within legal regulations and need to invest significant time and effort for this. This study has limited generalization potential because the result of the model fit has insufficient reference value. In future research, we need to approach various dimensions of corporate performance.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1781-1785
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• 2004

In existing factory, robot has less necessity that consider person. However, person should be considered at design and use of service robot. To service robot can be used in everyday life along with this, more functions are required. Specially, medical service robot needs function that is intelligence function. Especially, to help patient brain disease patient (cerebral hemorrhage, cerebral infarction, imbecility), gait assistance Mobile robot consider ergonomic element necessarily. In order to develop the medical support service robot, the ergonomic design should be considered. This robot ergonomic design parameters are treated in ("evelopment of Medical Support Service Robot Using Ergonomic Design" 2003, ICASS) Fig2 show this Robot. In this study, navigation algorithm of walk assistance robot is analyzed in ergonomic view. Navigation algorithm of Mobile robot can divide by two patterns. Traditional derivative method has shortcoming in dynamic environment. Reactive method is result that react excellently in dynamic environment. However, number of behavior function is limited. So hybrid navigation algorithm was proposed by the alternative way. We consider enough user specificity at navigation algorithm application of gait assistance robot.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2033-2038
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• 2003

This paper describes an integrated navigation strategy for the autonomous service robot PSR. The PSR is under development at the KIST for service tasks in indoor public environments. The PSR is a multi-functional mobile-manipulator typed agent, which works in daily life. Major advantages of proposed navigation are as follows: 1) Structured control architecture for a systematic integration of various software modules. A Petri net based configuration design enables stable control flow of a robot. 2) A range sensor based generalized scheme of navigation. Any range sensor can be selectively applied using the proposed navigation scheme. 3) No need for modification of environments. (No use of artificial landmarks.) 4) Hybrid approaches combining reactive behavior as well as deliberative planner, and local grid maps as well as global topological maps. A presented experimental result shows that the proposed navigation scheme is useful for mobile service robot in practical applications.

• Bulletin of the Korean Chemical Society
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• v.34 no.9
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• pp.2741-2746
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• 2013

The immobilization of enzyme is one of the key issues both in the field of enzymatic research and industrialization. In this work, we reported a facile method to immobilize Candida Antarctica lipase B (CALB) in alginate carrier. In the presence of calcium cation, the enzyme-alginate suspension could be cross-linked to form beads with porous structure at room temperature, and the enzyme CALB was dispersed in the beads. Activity of the enzyme-alginate composite was verified by enzymatic hydrolysis reaction of p-nitrophenol butyrate in aqueous phase. The effects of reaction parameters such as temperature, pH, embedding and lyophilized time on the reactive behavior were discussed. Reuse cycle experiments for the hydrolysis of p-nitrophenol butyrate demonstrated that activity of the enzyme-alginate composite was maintained without marked deactivation up to 6 repeated cycles.

• Journal of the Korean institute of surface engineering
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• v.35 no.3
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• pp.133-140
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• 2002

The Ti-Si-N coating layers were synthesized on SKD 11 steel substrate by a DC reactive magnetron co-sputtering technique with separate Ti and Si targets. The high resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS) analyses for the coating layers revealed that microstructure of Ti-Si-N layer was nanocomposite, consisting of nano-sized TiN crystallites surrounded by amorphous $Si_3$$N_4$ phase. The highest hardness value of about 39 GPa was obtained at the Si content of ~11at.%, where the microstructure had fine TiN crystallites (about 5nm in size) dispersed uniformly in amorphous matrix. As the Si content in Ti-Si-N films increased, the TiN crystallites became from aligned to randomly oriented microstructure, finer, and fully penetrated by amorphous phase. Free Si appeared in the layers due to the deficit of nitrogen source at higher Si content. Friction coefficient and wear rate of the Ti-Si-N coating layer significantly decreased with increase of relative humidity. The self-lubricating tribe-layers such as $SiO_2$ or (OH)$Si_2$ seemed to play an important role in the wear behavior of Ti-Si-N film against steel.