• 동의생리병리학회지
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• 제25권3호
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• pp.540-545
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• 2011

Quercus salicina has been widely used as a traditional medicine for the treatment of various diseases. In macrophages, nitric oxide (NO) is released as an inflammatory mediator and has been proposed to be an important modulator of many pathophysiological conditions in inflammation. In the present study, the inhibitory effect of methanolic extracts of Q. salicina (QSM) on NO production in LPS-stimulated mouse (C57BL/6) peritoneal macrophages was investigated. QSM suppressed NO production without notable cytotoxiciy. QSM also exhibited down-regulation of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expression via attenuation of NF-${\kappa}B$ translocation to nucleus in rIFN-${\gamma}$ and LPS stimulated mouse peritoneal macrophages. The present study strongly suggest that Q. salicina may be beneficial in diseases which related to macrophage-mediated inflammatory disorders.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1997년도 춘계학술대회논문집; 경주코오롱호텔; 22-23 May 1997
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• pp.452-459
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• 1997

For computer aided design and construction of low noisy power plants, indoor and outdoor noise prediction program has been developed. The program utilizes the predefined data of noise sources and building materials and has the faculty to estimate the source level using the empirical formula in case of the measured data not being available. In the noise prediction, the mutual noise propagation between indoor and outdoor sites are considered. The outdoor noise source in the calculation of geometric divergence effects is modelled as the omni-directional finite line or planar source according to the source geometry and the receiving points. Outdoor noise prediction is carried out to consider the diffraction effect due to plant structures as well as the attenuation effect due to atmospheric absorption and soft ground. The results of indoor and outdoor noise prediction for a recently constructed diesel engine power plant show good agreement with the measured.

• 대한기계학회논문집A
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• 제20권4호
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• pp.1177-1185
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• 1996

The crack growth under creep condition is one of the major damage mechanisms which determines remaining life of the component operating at high temperatures. In this paper, the creep crack growth by grain boundary cavitation is studied, which is frequently observed failure mechanism for creep brittle materials. As a result of diffusive growth of creep cavities, it is shown that the crack-tip stress field is modified from the original stress distribution by the amount of singularity attenuation parameter which is function of crack growth rate and material properties. Also, the stress relaxation at crack-tip results in the extension of cavitating area by the load dump effect to meet the macroscopic force equilibrium conditdion.

• 한국식품위생안전성학회지
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• 제14권2호
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• pp.179-185
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• 1999

Previous studies have shown that methanol extract and its butanol fraction of Carthamus tinctorius L. Semen have the hepatoprotective effect on the CCl4-induced hepatotoxicity. The hepatoprotective effect of the subfractions of butanol fraction has been evaluated by analyzing oxygen free radical scavenging enzyme activities and histopathological examinations. In BS-5 subfraction treated group, the activity of superoxide dismutase has been significantly increased as compared with that of CCl4, treated rats. Antioxidant activity has been evaluated by the examination of the scavenging activity against 1,1-diphenyl-2-picrylhydrazyl radical. BS-5 subfraction has shown strong antioxidant activities. The histopathological examination showed that the treatment of BS-5 subfraction has relieved the ballooning degeneration of hepatocytes which had been generated by CCl4. It appears that the protective effect of BS-5 subfraction would be mediated of the attenuation of lipid peroxidation by acting as a free radical scavenger, which were based on the increase of superoxide dismutase activity.

• 대한핵의학회지
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• 제39권4호
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• pp.246-251
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• 2005

목적: 심근관류 스펙트 검사에서 감쇠의 영향을 보정하기 위해 여러 가지 방법들이 사용되어 왔다. 본 연구는 CT를 이용한 감쇠보정이 관상동맥조영술이 정상인 환자들을 대상으로 하였을 때 어떠한 영향을 주는지 알아보고 기존의 감쇠보정방법들과 차이가 있는지를 알아보고자 하였다. 대상 및 방법: 관상동맥질환이 의심되어 심근 SPECT/CT를 시행한 환자들 중 관상동맥조영술상 정상소견을 보인 25명에서, Pryor 등의 방법으로 관상동맥질환의 위험도가 5.0% 미만인 15명의 환자를 대상으로 하였다. (남 6, 여 9, 평균연령 $58{\pm}8$세). CT가 장착된 Millennium VG (GE) 카메라로 감쇠보정을 하였으며, 영상의 판독은 육안분석과 극성지도를 이용한 정량적 분석을 시행하였다. 정량적 분석의 경우 극성지도 상에서 각 심근벽의 섭취율(최대 섭취율에 대한 %)을 구하여 감쇠보정을 하지 않은 영상과 감쇠보정을 한 영상을 비교하였다. 결과: 육안분석에서 감쇠보정을 한 경우 하벽의 섭취는 증가한 반면, 전벽과 심첨부 및 격벽의 섭취는 감소하였다. 간에서의 섭취도 감쇠보정을 한 경우에 증가하였다. 정량분석에서는 심첨부의 경우 감쇠보정 후 섭취율이 감소하였고, 하벽의 경우 증가하였다. 하벽의 경우 감쇠보정을 하여 판독에 도움을 받을 수 있었고, 반면 전벽이나 심첨부의 경우 감쇠보정 후 판독에 어려움이 있었다. 결론: 하벽의 경우 CT를 이용한 감쇠보정을 한 경우 판독에 도움이 되었으며, 감쇠보정전 영상이 정상인 경우 심첨부나 전벽등의 판독시는 주의가 필요하다.

• 한국음향학회지
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• 제16권1호
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• pp.76-80
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• 1997

Hofler 타입의 열음향 냉장시스템에 있어서 음향학적 공진특성을 해석하고, 공진특성이 냉장성능에 미치는 영향을 시스템의 제작 및 냉장 실험을 통하여 확인하였다. 열음향 냉장시스템의 공진특성을 결정하는 주요 인자는 공명구(cavity)와 가는 관, 그리고 굵은 관으로 구성되는 공명기의 특성과, 구동 스피커의 특성, 그리고 스피커 후면부의 음향학적 특성이며, 다시 스피커의 전기적 특성과 결합되어 전기적 공진특성이 정해진다. 또한 공명기에서 발생하는 벽-효과(wall effect)를 통한 감쇠로 인하여 공진특성이 둔해진다. 제작된 열음향 냉장시스템에 대한 해석 및 실험결과 전체 공진특성은 공명기에 의하여 결정되지만 후면부의 강성과 감쇠로 인하여 공진특성이 상당히 둔화되고, 냉장실험 결과 정확한 공진특성의 유지가 냉장성능에 큰 영향을 마침을 확인하였다.

• The Korean Journal of Physiology and Pharmacology
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• 제5권1호
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• pp.87-92
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• 2001

Carbon monoxide (CO) binds to soluble guanylate cyclase to lead its activation and elicits smooth muscle relaxation. The vascular tissues have a high capacity to produce CO, since heme oxygenase-2 (HO-2) is constitutively expressed in endothelial and smooth muscle cells, and HO-1 can be greatly up-regulated by oxidative stress. Moreover, the substrate of HO, heme, is readily available for catalysis in vascular tissue. Although the activation of heme oxygenase pathway under various stress conditions may provide a defence mechanism in compromised tissues, the specific role of HO-1-derived CO in the control of aortic contractility still remains to be elucidated. The present study was done to determine the effect of HO-1 induction on the aortic contractility. Thus, the effects of incubation of aortic tissue with S-nitroso-N-acetylpenicillamine (SNAP) for 1 hr on the aortic contractile response to phenylephrine were studied. The preincubation with SNAP resulted in depression of the vasoconstrictor response to phenylephrine. This effect was restored by HO inhibitor or methylene blue but not by NOS inhibitor. The attenuation of vascular reactivity by preincubation with SNAP was also revealed in endothelium-free rings. $AlF4^--evoked$ contraction in control did not differ from that in SNP-treated group. These results suggest that increased production of CO was responsible for the reduction of the contractile response to phenylephrine in aortic ring preincubated with SNAP and this effect of SNAP was independent on endothelium.

• Advances in nano research
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• 제14권5호
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• pp.463-474
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• 2023

The purpose of this paper is to present the analysis of propagating and evanescent waves in functionally graded (FG) nanoplates with the consideration of nonlocal effect. The analytical integration nonlocal stress expansion Legendre polynomial method is proposed to obtain complete dispersion curves in the complex domain. Unlike the traditional Legendre polynomial method that expanded the displacement, the presented polynomial method avoids employing the relationship between local stress and nonlocal stress to construct boundary conditions. In addition, the analytical expressions of numerical integrations are presented to improve the computational efficiency. The nonlocal effect, inhomogeneity of medium and their interactions on wave propagation are studied. It is found that the nonlocal effect and inhomogeneity of medium reduce the frequency bandwidth of complex evanescent Lamb waves, and make complex evanescent Lamb waves have a higher phase velocity at low attenuation. The occurrence of intersections of propagating Lamb wave in the nonlocal homogeneous plate needs to satisfy a smaller Poisson's ratio condition than that in the classical elastic theory. In addition, the inhomogeneity of medium enhances the nonlocal effect. The conclusions obtained can be applied to the design and dynamic response evaluation of composite nanostructures.

• 한국산업보건학회지
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• 제20권1호
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• pp.19-28
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• 2010

This study was designed to investigate the effect of increased blood and tibia lead on the change of bone mineral density in retired male lead workers. One hundred nine retired male lead workers who worked in 4 different lead industries and 51 nonoccupationally lead exposed male subjects were recruited from March 2004 to October 2004. Bone mineral density(BMD) was measured by broadband ultrasound attenuation(BUA) at left calcaneous bone area with broadband ultrasound attenuation method of QUS-2(Metra Biosystems Inc, USA). Tibia bone lead was measured for skeletal bone lead with K-xray fluorescence(K-XRF) and blood lead was analyzed with flameless atomic spectrophotometer. Hemoglobin, hematocrit, serum calcium and iron were also analyzed. In addition, information for smoking and drinking status and basic personal data such as age and lead exposure were also collected using questionnaire inquiry. Blood lead was correlated with tibia lead (r=0.711) and these two variables were negatively correlated with BUA in bivariate analysis. BUA and tibia lead showed significant main effects on the change of blood lead after adjusting covariates. The effect modification by the level of BMD (low: lower than the median of BUA and high: higher than the median of BUA) was observed between the association of tibia lead and blood lead after adjustment of covariates. The subjects who had higher BMD seemed to have lower blood lead by the increase of tibia lead than those of lower BMD. In the multiple regression analysis of blood lead and tibia lead on BUA after adjustment of covariates, only blood lead showed statistically significant effect on BUA. This study confirmed that BMD and blood lead were significantly associated. To verify the causal association of BMD on blood lead and vice versa, further longitudinal studies are needed.

• 한국의학물리학회지:의학물리
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• 제12권1호
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• pp.19-29
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• 2001

방사선의 에너지가 비교적 낮은 선원은 알짜선원의 방사능크기와 캡슐을 통과한 선량으로 나타내는 겉보기방사능크기로 구분할 필요가 있다. 저자는 국내 도입된 Ralstron 강내조사장치에 사용할 고선량률 Ir-192 선원을 고안제작하여 선원-캡슐간 필터효과를 조사하였다. 선원은 직경 1.5mm 와 높이 1.5mm 이고, 선원캡슐의 외경과 길이는 각각 3.0 mm 와 12.0mm로 원형과 동일한 외형을 하고 있다. 선원의 필터에 의한 선량감쇠는 66.3%로 나타났으며, 단위 방사능 강도에 의한 기준 출력선량은 선원 측방 1cm 거리에 도달되는 조직선량을 기준선량으로 규격화하였으며, 기준선량은 0.0013511cGy/mCi -sec (cGy/37MBq-sec) 로 나타났다. 선원하부는 스텐필터 두께의 영향으로 동일 거리의 측방 위치의 조직선량에 비해 약 52%의 선량감쇠를 보이고 있다. 그러나 선원하부 에서 측방 영역으로 갈수록 스텐 필터에 의한 선량감쇠효과가 줄어드는 것을 확인할 수 있었다. 선원중심에서 상하 45도 대각선 방향의 선량을 비교한 바 상부 대각선 방향의 선량이 하부의 것에 비해 약 4% 크게 나타났으며, 이는 선원 상부의 캡슐용기의 모양을 경사지게 한 결과 필터효과가 상대적으로 적음을 알 수 있다. 선원과 케이블이 있는 선원축의 연결케이블과 근접한 20도이내의 영역에서는 필터효과의 변화가 커서 40%의 선량감쇠를 보였으나, 축에서 떨어질수록 균등한 동심원의 선량분포를 얻었다.