• Journal of Chest Surgery
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• v.34 no.2
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• pp.111-117
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• 2001

배경: 심근 수축력과 더불어 전신저항은 개심술 후 적절한 심박출량을 유지하기 위한 매우 중요한 요인이다. 후부하의 변화를 비관혈적으로 평가할 수 있는지 알아 보고자 대동맥 혈류파형의 변화를 관찰하였다. 대상 및 방법: 개흉한 8마리의 잡견에서 연속파형 Doppler 심초음파를 이용하여 nitroprusside 단독 또는 epinephrine과의 병합투여 잔후로 상행 대동맥 혈류를 측정하였다. 결과: Nitroprusside의 투여로 동맥압과 전신저항은 약물의 투여량에 비례하여 감소함으로써(p<0.05 vs 기준치), 대동맥 혈류파형의 최고속도, 평균가속 및 분거리(속도시간적분$\times$심박동수)는 증가하였고, 가속시간은 짧아졌으며(p<0.05 vs 기준치), 가속시간/박출시간의 비는 변화가 없었다. Nitroprusside 투여로 인한 전신저항의 변화는 속도시간적분이나 Doppler 시간간격 지표보다는 최고속도(r=0.60, p=0.001)와 평균가속(r=0.52, p=0.003)과 상관관계가 있었다. Epinephrine과의 병합투여로 전신저항이 증가하지 않는 한 nitroprusside 단독투여에 비해서 최고속도, 평균가속 및 속도시간적분이 더 크게 증가했으나, 전신저항이 증가되면 이 Doppler 지표들은 감소하는 경향을 보였다. 결론: Doppler 심초음파를 이용하여 상행 대동맥 혈류파형의 최고속도와 평균가속을 연속적으로 측정함으로써 후부하의 변화를 비관혈적으로 평가할 수 있으리라 생각된다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.1
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• pp.64-72
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• 1998

In this work, we have investigated the change of surface roughness, grain size and crystallinity of Poly-$Si_{1-x}Ge_x$ films deposited with the variation of deposition parameters (temperature, pressure, Ge composition ) and the effect of these results on the electrical resistivity. The crystallinity and the grain size were increased with increasing deposition temperature and Ge composition. Also, the electrical resistivity was decreased by enhanced grain size, while the surface roughness was increased. With increasing deposition pressure, the crystallinity was increased, but the grain size and the cluster size were decreased, by which the surface roughness was decreased. And the electrical resistivity was increased. Based on the effect of the crystallinity and the grain size on the electrical resistivity, it was founded that the electrical resistivity was depend on the grain size rather than the crystallinity.

• The Korean Journal of Rheology
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• v.3 no.1
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• pp.76-85
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• 1991

적은양의 분자량이 큰선형 고부자를 수용액에 첨가함으로서 얻어지는 마찰저항가소 연구가 rotating disk 장치를 이용해 수행되었다. 마찰저항 감소제로 poly(ethylene oxide)와 poly(acrylamide)를 사용하였으며 고분자 분자량 고분자 농도, disk 의 회전속도 및 온도 등 여러 가지 인자에 대한 마찰정항감소의 의존성을 연구하였다. 또한 마찰저항 감소 효과와 고분자 용액의 점도평균 분자량을 동시에 측정함으로서 고분자 퇴화에 대한 연구도 수행하 였다. 마찰저항감소는 고분자 농도가 증가함에 따라 임계농도에 도달할때까지 증가하였고 낮은 농도에서는 분자량이 큰 고분자일수록 더욱 큰 마찰저항 감소효과를 나타내었다. 마찰 감소 진행 중의 높은 전단력에 기인하는 고분자의 분해는 고분자 농도가 낮은데에서 더욱두 드러지게 나타났으며 온도 효과의 연구로부터 poly(acrylamide)가 poly(ethylene oxide)보다 열적으로 안정함을 알수 있었다.

• Journal of the Microelectronics and Packaging Society
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• v.2 no.1
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• pp.19-28
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• 1995

RuO2 함량을 각각 달리한 pyrochlore 구조의 Pb2Ru2O6.5분말을 제조하여 이 분말과 유기 vehicle 유기용매를 혼합하여 저항 페이스트를 제조한후 인쇄, 소결과정을 거쳐 전반적 인 물성을 분석하였고 두 종류의 페이스트에 TCR보정용 첨가제로서 ZrO2를 첨가한 경우 처가량에 따라 저항값은 크게 변화하였으나 TCR 은 약간의 변화를 보였으며 Nb2O5의 경우 저항값이 크게 증가하였으며 TCR은 2wt%까지 첨가시 매우 안정적인 값을 나타내었다. 고 정항의 경우 CuO의 첨가시 저항값이 크게 감소 하였으며 TCR은 첨가량에 따라 증가하였 으나 3wt%이상 첨가시 저항체 표면이 심하게 거칠어지는 결과를 보였다.

• Journal of Korean Society of Forest Science
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• v.48 no.1
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• pp.59-63
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• 1980

The resistance to water transport were measured for the species which are easy for rooting and the species which are difficult for rooting from cutting to rooting. The experimental materials were selected as Euonymus japonica and Viburnum Awabuki for the species easy to root and Quercus glauca, Pasania edulis and Rhaphiolepsis umbellata var. integerreima for the species that are difficult to root. The results were summarized as follows; 1. As the time passed after cutting, the variation of total resistance (RT) showed a slow increase for the species easy to root, while the species that were difficult to root showed a rapid increase. 2. The stem resistance without leaves (RS) showed a rapid increase for the species easy to root but the species difficult to root had nearly constant values. 3. The stem resistance in the cross section (RC) increased noticably for the species difficult to root showed no increase. Furthermore the stem resistance in the cross section (RC) depended on the variation of the stem resistance without leaves (RS). 4. The total resistance (RT) consisted mainly of the resistance of the axil part (RL) for the species difficult to root.

• Applied Biological Chemistry
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• v.40 no.6
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• pp.508-513
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• 1997

Thermal characteristics and granular morphology on enzyme-resistant starches (RS) formed during heat-moisture treatment (HMT) and retrogradation were investigated in high amylose corn starches, Hylon V and Hylon VII. With each treatment, both starches showed a similar trend in the increase of RS, but RS yield of Hylon VII is higher than that of Hylon V. Specially, RS was increased remarkably by HMT. It was more than doubled from 11.4% to 26.6% for Hylon V and from 15.9% to 32.8% for Hylon VII. A small increase of RS resulted from retrogradation. HMT on starch increased gelatinization temperature, decreased enthalpy. Retrograded starch exhibited small three endothermic transitions at $94^{\circ}C$, $110^{\circ}C$ and $140^{\circ}C$ in differential scanning calorimetry (DSC) thermogram due to the remained ungelatinized starch granules, dissociation of amylose-lipid complex and melting of recrystallized amylose, respectively. Enzyme-resistant starches isolated from native and heat-moisture treated starches showed a broad endothermic transition at higher temperature than native starch, while retrograded starch exhibited a very sharp peak at ${\sim}150^{\circ}C$ due to the melting of amylose crystallites. Under microscopy, starch granules with HMT was not changed, but retrograded starches showed the aggregates of starch granules because amylose leached out during gelatinization. Iodine stained RS clearly showed the differences in enzyme hydrolysis on the native, heat-moisture treated and retrograded starches.

• Korean Journal of Food Science and Technology
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• v.29 no.2
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• pp.383-386
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• 1997

Maize starches with different amylose content were repeated autoclaving-cooling cycles up to 4 times, and the yield of resistant starch (RS) from autoclaved maize starches was investigated by enzymatic-gravimetric method and ${\alpha}-amylase$ treatment. With increasing amylose content in starch and the number of autoclaving-cooling cycles, RS yield was also increased, regardless of isolation method. Enzymatic-gravimetric method severely hydrolyzed amorphous region of autoclaved maize starches. Crystalline region was obtained more effectively by enzymatic-gravimetric method than by ${\alpha}-amylase$ treatment.

• Elastomers and Composites
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• v.33 no.4
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• pp.246-254
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• 1998

In order to investigate the characteristics of resistance and conduction of vulcanized styrene butadiene rubber (SBR)/ carbon black (CB) composites, surface/ volume resistivity, point to point resistance, decay time, and electrical conduction experiments with four different kinds of non-conductive carbon black were measured. When about 50phr of carbon black were loaded in SBR, all resistivites suddenly decreased and critical region (Rc) was shown. Current densities of SBR/CB composites showed critical point (Pc) and increased with the electric fields. Electrical conduction mechanisms of SBR/CB composites could be considered as the ohmic conduction at low electric fields and the space charge limited conduction (SCLC) at high electric fields, respectively.

• Journal of the Korean Geosynthetics Society
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• v.13 no.2
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• pp.49-57
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• 2014

In this study, in order to take advantage of samples collected in the Jangbogo station, and to grasp the liquefaction resistance characteristics of the dynamic load was performed cyclic triaxial test. Also, through the comparison with the existing literature. The test results, for the relationship between number of cycles for the same cyclic shear stress ratio and the cyclic shear stress ratio to produce an axial strain of 5%, in all samples, the cyclic shear stress ratio to liquefaction for the specimen, which has been liquefied, was increased, whereas number of cycles were reduced. The cyclic shear stress ratio of samples first decrease up to the fine content of about 10%. After this strength level, there is a little increase in cyclic shear stress ratio with increasing fine content. In addition, the cyclic shear stress ratio between cohesive strength, mean particle size, and friction angle decrease but some time later, there was a tendency that cyclic shear stress ratio is a little increased.

• Tuberculosis and Respiratory Diseases
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• v.52 no.3
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• pp.251-259
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• 2002

Background : Reduced lung compliance and increased lung resistance are the primary lung mechanical abnormalities in acute respiratory distress syndrome (ARDS). Although there is little information regarding the mechanisms responsible for the increases in the respiratory resistance of ARDS, bronchodilators have been frequently administered in mechanically ventilated ARDS patients. To determine the effect of a bronchodilator on the respiratory mechanics depending on the level of applied positive end-expiratory pressure (PEEP), the changes in the respiratory mechanics by salbutamol inhalation was measured under the variable PEEP level in patients with ARDS. Materials and Methods : Fifteen mechanically ventilated paralyzed ARDS patients (14 of male, mean age 57 years) were enrolled in this study. The respiratory system compliance, and the maximum and minimum inspiratory resistance were obtained by the end-inspiratory occlusion method during constant flow inflation using the CP-100 pulmonary monitor (Bicore, Irvine, CA, USA). The measurements were performed at randomly applied 8, 10 and 12 cm $H_2O$ PEEP before and 30 mins after administrating salbutamol using a meter-dose-inhaler (100ug${\times}$6). Results : 1) The maximum inspiratory resistance of the lung was higher than the reported normal values due to an increase in the minimal inspiratory resistance & additional resistance. 2) The maximum inspiratory resistance and peak airway pressure were significantly higher at 12cm $H_2O$ of PEEP compared with those at 10cm $H_2O$ of PEEP. 3) Salbutamol induced a significant decrease in the maximum and the minimum inspiratory resistance but no significant change in the additional resistance only was observed at 12cm $H_2O$ of PEEP(from $15.66{\pm}1.99$ to $13.54{\pm}2.41$, from $10.24{\pm}2.98$ to $8.04{\pm}2.34$, and from $5.42{\pm}3.41$ to $5.50{\pm}3.58cm$ $H_2O$/L/sec, respectively). 4)The lung compliance did not change at the applied PEEP and salbutamol inhalation levels. Conclusion : The bronchodilator response would be different depending on the level of applied PEEP despite the increased respiratory resistance in patients with ARDS.