• Toxicological Research
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• 제30권3호
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• pp.141-148
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• 2014

Endothelium-derived relaxing factors (EDRFs), including nitric oxide (NO), prostacyclin ($PGI_2$), and endothelium-derived hyperpolarizing factor (EDHF), play pivotal roles in regulating vascular tone. Reduced EDRFs cause impaired endothelium-dependent vasorelaxation, or endothelial dysfunction. Impaired endothelium-dependent vasorelaxation in response to acetylcholine (ACh) is consistently observed in conduit vessels in human patients and experimental animal models of hypertension. Because small resistance arteries are known to produce more than one type of EDRF, the mechanism(s) mediating endothelium-dependent vasorelaxation in small resistance arteries may be different from that observed in conduit vessels under hypertensive conditions, where vasorelaxation is mainly dependent on NO. EDHF has been described as one of the principal mediators of endothelium-dependent vasorelaxation in small resistance arteries in normotensive animals. Furthermore, EDHF appears to become the predominant endothelium-dependent vasorelaxation pathway when the endothelial NO synthase (NOS3)/NO pathway is absent, as in NOS3-knockout mice, whereas some studies have shown that the EDHF pathway is dysfunctional in experimental models of hypertension. This article reviews our current knowledge regarding EDRFs in small arteries under normotensive and hypertensive conditions.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2000년도 특별강연 및 추계학술발표대회 개요집
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• pp.219-221
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• 2000

• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 2001년도 추계학술대회 논문집
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• pp.271-279
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• 2001

• 한국물환경학회지
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• 제26권5호
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• pp.871-879
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• 2010

To figure out the removal efficiency of indicator and pathogenic bacteria by unit processes of a sewage treatment plant using activated sludge process, analyses were done for incoming sewage, influent and effluent of primary clarifier, aeration tank, secondary clarifier and final discharge conduit of the plant. A matrix of bacterial items (average of bacterial reduction [log/ml], p value of paired t-test, number of decreased cases of twenty analyses, removal percentage only for decreased cases) between incoming sewage and final effluent of the plant were heterotrophic plate counts (1.54, 0.000, 20, 95.01), total coliforms (1.38, 0.000, 19, 83.94), fecal coliforms (0.90, 0.000, 20, 94.84), fecal streptococci (0.90, 0.000, 20, 98.08), presumptive Salmonella (0.23, 0.561, 7, 99.09), and presumptive Shigella (1.02, 0.002, 15, 92.98). Total coliforms, fecal coliforms, heterotrophic plate counts, and fecal streptococci showed highest decrease through secondary clarifier about 1-log (p<0.001) between 88% and 96%, and primary clarifier represented the significant (p<0.05) decrease. However, final effluent through discharge conduit showed higher total coliforms and fecal streptococci than effluent of secondary clarifier (p<0.05). In addition, final effluent once violated the water quality standard while effluent of secondary clarifier satisfied the standard. Hence some control measures including elimination of deposits in discharge conduit or disinfection of final effluent are necessary.

• 한국정보통신학회논문지
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• 제20권3호
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• pp.607-614
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• 2016

발전소 설비에서 케이블 포설을 위한 설계는 발전소 설비에 사용되어지는 케이블 유형의 다양한 형태로 인해 매우 많은 시간이 요구되고 매우 중요한 과제이다. 케이블 포설 설계 시 레이스웨이(Raceway)는 출발지(Source) 장비로부터 목적지(Destination) 장비까지의 케이블 트레이(Tray) 및 콘디트(Conduit)의 포설 구간을 의미한다. 기존의 케이블 포설 설계 과정은 모두 수기에 의해 작성되어 인적/시간적 투자손실이 크고, 케이블의 누락 및 케이블 오버필(Over Fill)과 같은 비효율적인 손실이 빈번히 발생한다. 따라서 본 논문에서는 효과적인 발전소 케이블 포설 설계를 위한 레이스웨이의 유연한 케이블 오버 필(Fill) 체크 기반의 자동화된 케이블 라우팅 경로 계산 알고리즘을 구현하였고, 제안한 자동화 케이블 라우팅 설계기법은 케이블 위치의 변화에도 유연한 레이스웨이 계산이 가능하다. 구현 결과, 케이블 라우팅 설계 프로그램은 발전소 케이블 포설 설계 사양을 준수하면서 케이블 라우팅 경로를 효과적으로 설정하고, 케이블 포설 설계 시간을 기존 대비 크게 단축하는 성능을 얻을 수 있었다.

• Journal of Computational Design and Engineering
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• 제3권1호
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• pp.37-52
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• 2016

To injection mould polymers, designing mould is a key task involving several critical decisions with direct implications to yield quality, productivity and frugality. One prominent decision among them is specifying sprue-bush conduit expansion as it significantly influences overall injection moulding; abstruseness anguish in its design criteria deceives direct determination. Intuitively designers decide it wisely and then exasperate by optimising or manipulating processing parameters. To overwhelm that anomaly this research aims at proposing an ideal design criteria holistically for all polymeric materials also tend as a functional assessment metric towards perfection i.e., criteria to specify sprue conduit size before mould development. Accordingly, a priori analytical criterion was deduced quantitatively as expansion ratio from ubiquitous empirical relationships specifically a.k.a an exclusive expansion angle imperatively configured for injectant properties. Its computational intelligence advantage was leveraged to augment functionality of perfectly injecting into an impression gap, while synchronising both injector capacity and desired moulding features. For comprehensiveness, it was continuously sensitised over infinite scale as an explicit factor dependent on in-situ spatio-temporal injectant state perplexity with discrete slope and altitude for each polymeric character. In which congregant ranges of apparent viscosity and shear thinning index were conceived to characteristically assort most thermoplastics. Thereon results accorded aggressive conduit expansion widening for viscous incrust, while a very aggressive narrowing for shear thinning encrust; among them apparent viscosity had relative dominance. This important rationale would certainly form a priori design basis as well diagnose filling issues causing several defects. Like this the proposed generic design criteria, being simple would immensely benefit mould designers besides serve as an inexpensive preventive cliché to moulders. Its adaption ease to practice manifests a hope of injection moulding extremely alluring polymers. Therefore, we concluded that appreciating injectant's polymeric character to design exclusive sprue bush offers a definite a priori advantage.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집B
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• pp.371-376
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• 2000

In this study, the computational method is presented to simulate the hemodynamics of the patients after the Fontan procedure. The short-term feedback control models are implemented to assess the hemodynamic responses of the patients exposed to the stresses such as gravitational effect or hemorrhage. To construct the base line of the Fontan model, we assume an increase in venous tone, in heart rates, and in systemic resistance that are based on the clinical observations. For the verification of the present method we simulate the LBNP (lower body negative pressure) test for the normal and the Fontan model and we compare these with experimental data. Computational results show that the diastolic ABP(arterial blood pressure) increases but the systolic ABP decreases during LBNP. The increase in heart rate is due to the control system activated by the decreased mean ABP and CVP(central venous pressure). In case of the Fontan model, the increased venous tone is the reason of the diminished CVP change during LBNP. We also simulate 20% hemorrhage stress to the patient after the Fontan procedure and these results are compared with the experimental and the existing computational one. Computational results on the hemodynamics of patients after the Fontan procedure show that the mean ABP and cardiac output decrease. Heart rate and systemic resistance increase to compensate for the decrease in ABP. The sensitivity analysis according to the conduit resistance is also presented to delineate the effects of the local blood flow resistance. The cardiac output decreases according to the increase of the conduit resistance. The 50% increase in the conduit resistance causes about 3% decrease of cardiac output.

• Journal of Mechanical Science and Technology
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• 제19권5호
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• pp.1158-1168
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• 2005

A shunt from the left ventricle to the left anterior descending artery is being developed for coronary artery occlusive disease, in which the shunt or conduit connects the the left ventricle (LV) with the diseased artery directly at a point distal to the obstruction. To aid in assessing and optimizing its benefit, a computational model of the cardiovascular system was developed and used to explore various design conditions. Computational fluid dynamic analysis for the shunt hemodynamics was also done using a commercial finite element package. Simulation results indicate that in complete left anterior descending artery (LAD) occlusion, flow can be returned to approximately 65% of normal, if the conduit resistance is equal for forward and reverse flow. The net coronary flow can increase to 80% when the backflow resistance is infinite. The increases in flow rate produced by asymmetric flow resistance are enhanced considerably for a partial LAD obstruction, since the primary effect of resistance asymmetry is to prevent leakage back into the ventricle during diastole. Increased arterial compliance has little effect on net flow with a symmetric shunt, but considerably augments it when the resistance is asymmetric. The computational results suggest that an LV-LAD conduit will be beneficial when the resistance due to artery stenosis exceeds 27 PRU, if the resistance is symmetric. Fluid dynamic simulations for the shunt flow show that a recirculating region generated near the junction of the coronary artery with the bypass shunt. The secondary flow is induced at the cutting plane perpendicular to the axis direction and it is in the attenuated of coronary artery.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2003년도 추계학술대회 논문집
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• pp.301-303
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• 2003

The KSTAR(Korea Superconducting Tokamak Advanced Research) superconducting magnet system consist of 16 TF(Toroidal Field) and 14 PF(Poloidal Field) coils. Internally-cooled cabled superconductors will be used for the magnet system. The magnet system adopt a superconducting CICC (Cable-In-Conduit Conductor) type. The KSTAR PF 6, 7 CICCs use NbTi Superconducting cable with stainless steel 316LN conduit while the other PF CICC use Incoloy 908 conduit. For the fabrication of PF CICC, superconducting cables have been fabricated and the cable has the diameter of 22.3mm. A continuous CICC jacketing system is developed for the CICC jacketing and the jacketing system uses the tube-mill process, which consists of forming, welding, sizing and squaring procedures. The cabling and the jacketing process is described. The welding condition and design specification of CICCs are also discussed. The fabrication results including the geometrical specification and the void fraction will be discussed.

• 대한기계학회논문집B
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• 제35권11호
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• pp.1191-1198
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• 2011

심실보조장치는 말기 심부전환자에게 심장이식수술 없이 1 년 생존율을 25%에서 52%까지 증가 시킬 수 있는 유일한 장치이다. 하지만 심실보조장치 이식 후 1 년이 이내에 사망하는 원인 중 기기의 고장으로 인한 사망률이 6%를 차지하기 때문에 심실보조장치의 고장이 환자의 심장 움직임과 혈류 역학적인 상태에 영향을 주지 않는 새로운 방법이 필요하다. 기존의 심실보조장치는 원심형, 축심형으로 혈액을 박출해 주는 방식이어서 동맥압 보다 박출하는 압력이 낮을 때 혈액의 역류가 일어나는 문제점이 있다. 본 논문에서는 박출 압력이 약할 때, 2 개의 밸브에 의하여 혈액의 역류를 방지하고 관형태의 구조에 의해 혈액의 정체량을 줄일 수 있는 새로운 박동형 관형 심실보조장치를 개발하였으며, 체외실험과 동물실험으로 박출량과 펌프의 압력을 측정하여 그 특성을 평가하였다.