• 한국응용과학기술학회지
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• 제37권5호
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• pp.1100-1105
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• 2020

본 연구는 기계화학적 활성화 된 스카치테이프가 금속 이온 수용액에서 유발하는 자발적 금속 나노입자 필름 형성의 구동력과 그 크기를 전기화학적 방법으로 분석했다. 은 필름이 형성된 테이프를 질산에 녹이고, 완충용액과 섞어 전기화학 측정용 샘플을 준비했다. 양극 벗김 전압전류법의 피크 신호를 통해, 은 입자의 자발적 환원에 소모된 전하량을 측정했다. 이를 검정 곡선에 대입하여, 환원된 은의 양을 구했다. 그 결과 은의 양이 선행 연구 대비 10⁶배 많은 점, 수용액에서 전하를 가진 이온들의 짧은 수명을 참고하여, 자발적 반응의 구동력을 라디칼로 결론 냈다.

• The Korean Journal of Pain
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• 제22권1호
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• pp.1-15
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• 2009

Neuropathic pain is often refractory to intervention because of the complex etiology and an incomplete understanding of the mechanisms behind this type of pain. Glial cells, specifically microglia and astrocytes, are powerful modulators of pain and new targets of drug development for neuropathic pain. Glial activation could be the driving force behind chronic pain, maintaining the noxious signal transmission even after the original injury has healed. Glia express chemokine, purinergic, toll-like, glutaminergic and other receptors that enable them to respond to neural signals, and they can modulate neuronal synaptic function and neuronal excitability. Nerve injury upregulates multiple receptors in spinal microglia and astrocytes. Microglia influence neuronal communication by producing inflammatory products at the synapse, as do astrocytes because they completely encapsulate synapses and are in close contact with neuronal somas through gap junctions. Glia are the main source of inflammatory mediators in the central nervous system. New therapeutic strategies for neuropathic pain are emerging such as targeting the glial cells, novel pharmacologic approaches and gene therapy. Drugs targeting microglia and astrocytes, cytokine production, and neural structures including dorsal root ganglion are now under study, as is gene therapy. Isoform-specific inhibition will minimize the side effects produced by blocking all glia with a general inhibitor. Enhancing the anti-inflammatory cytokines could prove more beneficial than administering proinflammatory cytokine antagonists that block glial activation systemically. Research on therapeutic gene transfer to the central nervous system is underway, although obstacles prevent immediate clinical application.

• 한국자동차공학회논문집
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• 제13권1호
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• pp.153-158
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• 2005

Titanium alloy has widely been used as material for automotive parts because it has high specific strength. It is also light and harmless to human body. But, we have little design data about the creep behaviors of the alloy. Therefore, in this study, creep tests under four constant stress conditions have been conducted with low different temperature conditions. A series of creep tests had been performed to get the basic design data and life prediction of titanium products and we have gotten the fallowing results. First, the stress exponents decrease as the test temperatures increased. Secondly, the creep activation energy gradually decrease as the stresses became bigger. Thirdly, the constant of Larson-Miller parameter on this alloy was estimated as about 7.5. And for the last, the fractographs at the creep rupture showed the ductile fracture due to the intergranullar rupture.

• Reproductive and Developmental Biology
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• 제28권4호
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• pp.257-260
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• 2004

Efficiency of somatic cell nuclear transfer was investigated in mice. First, oocyte activation was induced by SrCl₂, and the rate of development was compared with embryos from normal fertilization. Although more than one half of SrCl₂-treated oocytes developed to blastocysts (146/262, 55.7%), the rate of blastocyst formation was significantly lower than normal fertilization controls (59/79, 74.6%). Second, enucleation of oocytes was performed using Polscope that enables non-invasive visualization of metaphase spindles. Such approach could not only avoid damage of oocytes during an exposure to UV light often employed in conventional enucleation procedures, but could also assure the removal of nuclei from all oocytes operated because of monitoring the location of spindles during an entire process of enucleation. Morphologically normal blastocysts were obtained from the transfer of cumulus cell nuclei into enucleated oocytes. However, the rate of development into the blastocyst stage was still low (4/93, 4.3%). This reflects that the nuclear transfer procedure used in this study was not sufficiently optimized, and other factors may also impact greatly the efficiency of nuclear transfer. Including an induction of oocyte activation and method of enucleation tested in this study, a lot more elements are remained to be optimized to improve the efficiency of somatic cell nuclear transfer in mice.

• 한국세라믹학회지
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• 제45권11호
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• pp.750-754
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• 2008

The artificial aggregates with dense surface layer (shell) was fabricated and the dependence of water emission rate upon the shell structures was studied. The EAF dust containing many flux components and waste white clay with ignition loss of above 48% were used as for liquid phase and gas forming agents during a sintering process respectively. In addition, the shell structure was modified with various processes and the modification effect on water emission rate was analyzed. The pores under $10{\mu}m$ were found in the sintered artificial light aggregates and disappeared by incorporating to a bigger pore during re-sintering. The water emission rate in an initial step depended on a void content of aggregates filled in a bottle rather than a shell structure. But, after 7 days where the water emission of the aggregate with a shell is above 40%, the shell of aggregates suppressed the water emission. The core of aggregates was exposed and most shell was lost when crushed to smaller size so, the ability for suppressing water emission of the crushed aggregates decreased. The activation energy for the water emission was $3.46{\pm}0.25{\times}10^{-1}$J/mol for the most specimens showing that the activation energy is irrelevant to the pore size distribution and shell structure.

• 한국정보시스템학회지:정보시스템연구
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• 제8권1호
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• pp.45-63
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• 1999

Today, information society is affected by new technologies including Electronic Commerce(EC), Electronic Data Interchange(EDI), Commerce At Light Speed(CALS ), multimedia and teleconferencing. Electronic Commerce is believed to be a field that will bring about a huge revolution of human life in the 21st century and thus its industry will give greatly influential effect on other industries In this paper, we have surveyed and studied through the internet and related materials for the development of framework of Electronic Commerce. It is required that we need the leading role of our government for the earlier activation of Electronic Commerce usage and have to establish the solid background of EC technology creation of our nation's originality and to activate the venture industry oriented for idea and technology rather than the industries in the form of larger enterprises. In conclusion, we have to expand our own ability of research and development to keep the continuous growth of our Electronic Commerce market and industries through the development of new product and prior acquisition of market as well as to expand the path of various technology aquisition by the strategic M&A and capital investment with the leading foreign enterprises.

• Nuclear Engineering and Technology
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• 제40권1호
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• pp.93-98
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• 2008

Several adhesive tapes have been studied in terms of their suitability for securing gold wires into positions for neutron flux measurements in the reactor core and irradiation facilities surrounding the core of the Open Pool Australian Light water (OPAL) reactor. Gamma ray spectrometry has been performed on each irradiated tape in order to identify and quantify activated components. Numerous metallic impurities have been identified in all tapes. Calculations relating to both the effective neutron shielding properties of the tapes and the error in measurement of the $^{198}Au$ activity caused by superfluous activity due to residual tape have been made. The most important identified effects were the prolonged cooling times required before safe enough levels of radioactivity to allow handling were reached, and extra activity caused by residual tape when measured with an ionisation chamber. Knowledge of the most suitable tape can allow a minimal contribution due to these effects, and the use of gamma spectrometry in preference to ionisation chamber measurements of the flux wires is shown to make all systematic errors due to the tape completely negligible.

• The Korean Journal of Physiology and Pharmacology
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• 제27권5호
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• pp.449-456
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• 2023

N-methyl-D-aspartate (NMDA) receptors are ionic glutamine receptors involved in brain development and functions such as learning and memory formation. NMDA receptor inhibition is associated with autophagy activation. In this study, we investigated whether the NMDA receptor antagonists, memantine and ifenprodil, induce autophagy in human retinal pigment epithelial cells (ARPE-19) to remove N-retinylidene-N-retinylethanolamine (A2E), an intracellular lipofuscin component. Fluorometric analysis using labeled A2E (A2E-BDP) and confocal microscopic examination revealed that low concentrations of NMDA receptor antagonists, which did not induce cytotoxicity, significantly reduced A2E accumulation in ARPE-19 cells. In addition, memantine and ifenprodil activated autophagy in ARPE-19 cells as measured by microtubule-associated protein 1A/1B-light chain3-II formation and phosphorylated p62 protein levels. Further, to understand the correlation between memantine- and ifenprodil-mediated A2E degradation and autophagy, autophagy-related 5 (ATG5) was depleted using RNA interference. Memantine and ifenprodil failed to degrade A2E in ARPE-19 cells lacking ATG5. Taken together, our study indicates that the NMDA receptor antagonists, memantine and ifenprodil, can remove A2E accumulated in cells via autophagy activation in ARPE-19 cells.

• IMMUNE NETWORK
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• 제21권3호
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• pp.21.1-21.22
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• 2021

Myeloid-derived suppressor cells (MDSCs) have strong immunosuppressive activity and are morphologically similar to conventional monocytes and granulocytes. The development and classification of these cells have, however, been controversial. The activation network of MDSCs is relatively complex, and their mechanism of action is poorly understood, creating an avenue for further research. In recent years, MDSCs have been found to play an important role in immune regulation and in effectively inhibiting the activity of effector lymphocytes. Under certain conditions, particularly in the case of tissue damage or inflammation, MDSCs play a leading role in the immune response of the central nervous system. In cancer, however, this can lead to tumor immune evasion and the development of related diseases. Under cancerous conditions, tumors often alter bone marrow formation, thus affecting progenitor cell differentiation, and ultimately, MDSC accumulation. MDSCs are important contributors to tumor progression and play a key role in promoting tumor growth and metastasis, and even reduce the efficacy of immunotherapy. Currently, a number of studies have demonstrated that MDSCs play a key regulatory role in many clinical diseases. In light of these studies, this review discusses the origin of MDSCs, the mechanisms underlying their activation, their role in a variety of clinical diseases, and their function in immune response regulation.

• 감성과학
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• 제22권1호
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• pp.55-64
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• 2019

스트레스는 자율신경계 반응의 변화를 수반하며, 특히 심박변이도 지표는 스트레스에 의한 자율신경계의 활동을 반영하는 양적 지표로 사용된다. 본 연구에서는 스트레스 완화를 위한 산소와 색채 조명의 복합 자극이 제시되는 동안 자율신경계 반응의 변화를 확인하였다. 42명의 실험참가자는 지난 2주 동안 경험한 스트레스에 대한 증상들을 스트레스 반응 척도에 평가하였다. 스트레스 평가 후, 실험참가자는 복합 자극을 제시받았고, 자극 제시 전과 후, 그리고 자극이 제시되는 동안 심전도 신호가 기록되었다. 자극 조건은 30% 농도의 산소와 백색 조명, 산소와 주황색 조명과 산소와 파란색 조명의 조합의 세 가지로 구성되었다. 심박률(HR), R-R간격의 표준편차(SDNN), 연속한 R-R 간격 차이 값의 평균제곱근(RMSSD)과 심박변이도의 저주파 성분(LF), 고주파 성분(HF), 그리고 LF와 HF의 비율을 심박변이도 지표로 추출하였다. 이들 지표는 자극 제시 전과 후의 평균을 비교하는데 활용되었다. 결과는 자극 조건이 제시되고 난 후, HR과 LF/HF ratio의 유의한 감소를 보여주었다. 특히, 산소와 파란색 조명이 제시된 조건에서 다른 두 조건보다 유의하게 큰 RMSSD와 HF의 증가 및 LF/HF ratio의 감소가 나타났다. 이는 30% 농도의 산소와 파란색 조명의 조건이 부교감신경의 활성화에 의한 자율신경의 균형을 유발하여 스트레스 이완에 가장 효과적임을 보여주었다.