• International Journal of Naval Architecture and Ocean Engineering
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• 제12권1호
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• pp.928-942
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• 2020

The pressure responsiveness property of a skirt-cushion system, which is closely related to the overall performance of Air Cushion Vehicles (ACVs), has always been the difficulty and challenging problem involving cushion aerodynamics and flexible skirt dynamics. Based on a widely used bag and finger skirt-cushion system, the pressure responsiveness properties are investigated numerically. The physical process and mechanism are analyzed and a numerical method for evaluating the pressure responsiveness property is proposed. A cushion-skirt information communication platform is also presented for interchanging the force and the skirt configuration between cushion aerodynamics and flexible skirt dynamics. The pressure responsiveness of a typical skirt-cushion system is calculated and the results demonstrate that the pressure responsiveness property helps alleviate the influence of the cushion height changing on the overall performance of ACVs. Finally, the influences of skirt geometrical and cushion aerodynamic parameters on the pressure responsiveness properties are discussed systematically, giving insight into the design of skirt-cushion systems.

• The Korean Journal of Physiology
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• 제23권1호
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• pp.151-167
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• 1989

The present study was undertaken to investigate modification in electrophysiological characteristics of cat dorsal horn cells resulting from carrageenin-induced inflammation. The followings were studied; 1) the time-course of changes in responses of the WDR (wide dynamic range) cell 1-3h after subcutaneous injection of carrageenin in its receptive field; 2) the responses of the same dorsal hern cells before and after induction of inflammation; 3) the effect of inflammation on the responsiveness of dorsal horn neurons to algogens (bradykinin & potassium); and 4) the effect of inflammation on the activity of WDR cell following administration of indomethacin and clonidine. Though responses of WDR neuron were increased dramatically during first 1h, the maximal enhancement was observed 3h after induction of inflammation especially by repetitive light tactile stimulus. Following carrageenin injection the majority of WDR neurons (10/15 units) showed enhanced responses to all the mechanical stimuli while in 3 cases responsiveness were intensified during activation by one tactile stimulus (brush or pressure). One cell was unaffected by inflammation and in another case the response was enhanced only to noxious stimulus. Five of 9 cells that could initially be driven by noxious stimulus were activated more strongly by same stimulus and even by tactile stimulus (pressure) following inflammation. In 2 cases neurons were sensitized only to noxious stimulus whereas in another 2 cells that did not show enhanced responses to noxious stimulus responses to light tactile stimulus (pressure) appeared after inflammation. Of 16 LT cells tested 6 responded to squeeze while 4 showed the characteristics of WDR cell following inflammation. No modification in responsiveness was recognized in 3 cells whereas response to only brush was enhanced in another 3 neurons. Following carrageenin injection responses of LT cell to bradykinin or $K^{+}$ were not altered whereas those of WOR neurons to bradykinin or $K^{+}$ were suppressed in 22.2% and 33.3% of cases, respectively. In two of 8 activity of HT cells were inhibited by bradykinin while in five of 8 responsiveness to $K^{+}$ were rather enhanced by inflammation. In the rest inflammation was ineffective. In inflammation-induced animal the receptive field of LT cell was not changed whereas those of WDR cell and HT cell were tremendously expanded. The enhanced responses of WDR neurons to mechanical stimuli resulted from inflammation were suppressed by intravenously injected indomethacin and clonidine suggesting that postaglandin is involved in inflammation-induced sensitization of these cells. The involvement of peripheral and central mechanisms in the modification in responsiveness of dorsal horn cells in the carrageenin-induced inflammation was discussed.

• The Korean Journal of Physiology and Pharmacology
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• 제5권6호
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• pp.457-466
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• 2001

Glutamate is the most common excitatory amino acid in the brain. Responsiveness of dendrites to the glutamate greatly varies depending on the application sites. Especially, a point of the maximal response to the glutamate of the dendrite is called as 'hot spot'. In our experiment, the responsiveness of the hot spot to the glutamate was investigated in the CA1 pyramidal neuron of the rat hippocampal slice. CNQX, the antagonist of AMPA receptor, blocked 95% of membrane current to the glutamate focal application $(I_{gl}).$ Train ejection of glutamate on one point of the dendrite increased or decreased the amplitude of $I_{gl}$ with the pattern of train, and the changes were maintained at least for 30 min. In some cases, glutamate train ejection also induced calcium dependent action potentials. To evoke long-term change of synaptic plasticity, we adopted ${\theta}-burst$ in the glutamate train ejection. The ${\theta}-burst$ decreased the amplitude of glutamate response by 60%. However, after ${\theta}-burst$ glutamate train ejection, the calcium dependent action potential appeared. These results indicated that the focal application of glutamate on the neuronal dendrite induced response similar to the synaptic transmission and the trains of glutamate ejection modulated the change of AMPA receptor.

• The Korean Journal of Physiology
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• 제21권2호
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• pp.291-296
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• 1987

There have been reports on the aberration of the control mechanisms of the blood pressure, hormone secretion, and renal functions in spontaneously hypertensive rats (SHR). However, the contribution of the renin-angiotensin system in the maintenance of high blood pressure in SHR is still controversial. Recently, it has been reported that the negative feedback short loop control mechanism of the renin-angiotensin system may be changed in SHR. In the present experiment, it was attempted to explore the possible alterations in the effect of arginine vasopressin (AVP) on the renal function in SHR. Experiments have been done in anesthetized SHR as well as in normotensive Wistar and Sprague-Dawley rats as control groups. Pharmacologic doses of AVP (10-13 mU/rat/10 min) decreased urine volume, excreted amount of creatinine and para-amino-hippuric acid. No differences in these parameters was observed between normotensive and hypertensive rats. AVP increased sodium and potassium excretion, but the responses in SHR were suppressed as compared with normotensive rats. Intravenous infusion of AVP also increased blood pressure in normotensive and hypertensive rats and a vasopressor effect of AVP was attenuated in SHR. There was a positive correlation between the changes in blood pressure and excreted amount of sodium during AVP infusion. These data suggest that the attenuated natriuretic effect of intravenous infusion of AVP may be due to a difference in renal tubular responsiveness to AVP but not due to a difference in vasopressor responsiveness.

• 한국건설순환자원학회논문집
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• 제7권3호
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• pp.243-254
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• 2019

본 연구에서는 지금까지 공동주택 지하주차장 상부 슬래브에 적용하여 누수하자가 발생된 방수공법들의 문제점과 상부 슬래브의 특성을 고려한 요구조건을 검토하고, 이에 적합한 성능(안)을 선정하여 복합형 폴리우레아 공법을 대상으로 그 적합성 여부를 판단하고자 하였다. 검토결과, 공동주택 지하주차장 상부슬래브에는 (1) 균열 및 거동 대응성, (2) 바탕면 일체성, (3) 수직부 수밀 안정성, (4) 누름층 시공 용이성, (5) 충격 및 누름 대응성, (6) 차량 이동하중에 대한 대응성 등의 성능검토가 필요하겠다. 연질, 경질의 복합형 폴리우레아를 대상으로 요구조건에 해당하는 5가지 항목에 대한 평가를 진행한 결과 모두 조건에 부합하는 것으로 확인되었으며, 단일 공법으로 적용함에 있어 문제점이 있던 재료들을 복합화 함으로서 각 재료의 장단점을 보완하여 효과적으로 적용할 수 있음을 확인하였다. 단, 실제 현장에 적용하기 위해서는 향후 Mock-up 평가 등 현장 적용성에 대한 추가적인 평가가 이루어져야 할 것이며, 복합화에 따른 경제성 및 유지관리성 측면에서의 검토를 통해 실제 시장 적용성 여부에 대한 후속적인 연구가 필요하겠다.

• 동아시아식생활학회지
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• 제9권3호
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• pp.378-385
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• 1999

A reduced NaCl intake for the general population of the world has been recommended to reduce the overall blood pressure level and hence to reduce the overall incidence of cardiovascular disease. A high NaCl diet convincingly contributes to elevated arterial pressure in humans and animal models of hypertension. Among individuals there is considerable variability of blood pressure responsiveness to NaCl intake. In normotensive as well as hypertensive subjects, blood pressure can be judged to be salt sensitivity (SS) when observed to vary directly and substantially with the net intake of NaCl. The prevalence of SS in normotensive adults in the U.S. ranges from 15% to 42% and in hypertensive adults from 28% to 74%. SS is a risk factor for hypertension and may be an important marker in the identification of children for hypertension prevention programs. High NaCl intakes produce expansion of the extracellular fluid volume and thus increase blood pressure. Nonchloride salts of sodium does not expand the extracellular fluid volume and does not alter blood pressure. Blood pressure response to NaCl may be modified by other components of the diet. Low dietary intakes of potassium or calcium augment NaCl-induced increases of blood pressure. Conversely, high dietary intakes of potassium or calcium attenuate NaCl-induced hypertension. A greater intakes of potassium or calcium may prevent or delay the occurrence of hypertension. SS occurs when dietary potassium is even marginally deficient but is dose-dependently suppressed when dietary potassium is increased within its normal range. Orally administered KHCO$_3$, abundant in fruits and vegetates, but not KCl has a calcium-retaining effect which may contributed to its reversal of pressor effect of dietary NaCl. Since nutrients other than NaCl also affect blood pressure levels, a reduced NaCl intake should be only one component of a nutritional strategy to lower blood pressure.

• Tuberculosis and Respiratory Diseases
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• 제42권5호
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• pp.752-759
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• 1995

연구배경: 심부전 환자에서 기관지 과민성의 여부를 확인하고 이러한 기관지 과민성과 혈역학적 지표사이의 상관관계를 알기위해 메타콜린을 이용하여 기관지 유발검사를 실시하였다. 방법: 1994년 3월부터 8월까지 본원에 내원하여 흉부 X선 촬영, 심에코도 검사, 심도자술로 승모판 심장질환이 진단되고 호흡곤란의 정도가 NYHA 기능적 분류 2인 11명의 환자를 대상으로 PARI nebulizer I을 이용하여 메타콜린 용액의 농도를 올리면서 기관지 유발검사를 시행하여 최대호기 유속이 20%이상 감소를 보이면 양성반응으로 간주하였다. 또한 각각의 환자는 심도자술을 통해서 혈역학적인 지표와 기관지 과민반응과의 상관 관계를 알아보고저 하였다. 결과: 1) 11명의 환자중 남자 2명 여자 9명이였으며 평균연령은 38.0세이였고 흡연력은 1명이외에는 없었다. 2) 각 환자의 호흡곤란 정도는 NYHA 기능적 분류 2였고 승모판 협착증만 있는 환자는 5명이였고 이외는 승모판 질환과 대동맥 판막질환이 동반되어있었다. 3) 환자들의 평균폐동맥압과 평균폐모세혈관 쐐기압은 각각 21.72mmHg(${\pm}8.55$), 15.45mmHg(${\pm}8.69$)로 정상보다 높았고 심장지수와 좌심실분획률은 각각 2.64L/min/m2(${\pm}0.41$), 61.81%(${\pm}7.21$)로 정상범위이였다. 4) 11명의 환자중 1명만 메타콜린 기관지 유발검사에 양성이었다. 결론: NYHA 기능적 분류 2인 승모판 심장질환이 있는 심부전환자 11명중 1명만 기관지 과민반응이 관찰되었으며 그 이유로 지속적인 심부전의 치료에 의한 간질성 폐부종의 소설로 인해 기관지의 반응성이 증가되지 않았다고 사료되며 NYHA 기능적 분류 3 또는 4인 승모판 심장질환 환자를 대상으로 기관지 과민 반응에 대한 추후의 검사가 필요할 것으로 생각된다.

• Archives of Pharmacal Research
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• 제18권3호
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• pp.169-172
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• 1995

The changes in blood pressure may relate to the alterations of the responsiveness to vasoconstrictors and vasodilators, and these alterations can arise the modifications in the properties of angiotensin II (AII) receptor. In order to examine the changes of AII receptor in the hypertensive mechanism of renin-dependent hypertensive rats (RHRs; two-kidney, one-ligated type), we compared the equilibrium binding characteristics of $[^3H]$All in adrenal cortex and medulla from RHRs and normotensive rats. The dissociation constants of AII binding in both tissues of RHRs were very similar to those in the respective tissue of normotensive rats. However, the maximum binding was increased from 805 to 1050 fmole/mg protein in the adrenal cortex of RHRs, and decreased from 172 to 126 fmole/mg protein in the adrenal medulla of RHRs. These results imply that the up- and down-regulation of the All receptor population on the cell surface of adrenal glands from RHRs are consorted with the elevation of blood pressure and the activation of renin-angiotensin system.

• 대한약리학회지
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• 제3권1호
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• pp.5-13
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• 1967

It has been reported by some investigators that pressor response of rabbits to sympathetic ganglionic stimulants was weak. In this paper it was attempted to investigate this problem more thorouglhy in urethane anesthetized rabbits. 1) In rabbits the approximate doses to elicit increase of about 20 mmHg of blood pressure were $100\;{\mu}g/kg$ with DMPP, $50\;{\mu}g/kg$ with Wy-615, $500\;{\mu}g/kg$ with TMA and with nicotine. The pressor activity of these substances was markedly augmented by treating animals with syrosingopine. 2) In adrenal-ligated rabbits pressor activity of the substances was markedly reduced. Treating the adrenal-ligated animals with syrosingopine augmented significantly the pressor activity of these substances except DMPP. Direct injection of DMPP and TMA into the adrenal produced mole pressor response than intravenous injection did. These date suggest that DMPP has greater effect on the adrenal medulla than the other substances. 3) In vagotomized and atropinized rabbits the pressor activity of these compounds was more marked than in normal rabbits. 4) The above facts indicate that the pressor activity of the ganglionic stimulants in rabbits was definitely low than in cats and dogs. The low responsiveness of the rabbits to these agents was discussed in the light of catecholamine releasing mechanisms, and extraganglionic actions of these substances.

• 대한약리학회지
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• 제21권1호
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• pp.27-33
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• 1985

전기자극에 의한 적출 정관의 수축 또는 뇌척수제거 흰쥐의 심박동수 증가가 카드뮴 장기투여 (매격일 $10{\mu}$ mols, 1회씩 2주간 복강내 주사)로 인하여 대조군에 비하여 현저히 항진되었다. 이러한 전기자극에 의한 반응은 ${\alpha}_2$-효현제인 clonidine에 의하여 억제 되었고, 이 억제는 ${\alpha}_2$-길항제인 yohimbine 투여로 봉쇄되었다. 나아가 methoxamine에 의한 확장 혈압의 증가는 카드뮴 투여에 의하여 영향을 받지 아니하였으나 clonidine에 의한 증가는 카드뮴 투여에 의하여 억제되었다. 이러한 결과로 보아 카드뮴 장기 노출에 의하여 시납스 전 및 후 ${\alpha}2-adrenoceptors$가 우선적으로 억제되었다고 시사되는 바이다.