• 대한약리학회지
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• 제24권1호
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• pp.63-70
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• 1988

문맥 고혈압 동물에서 내장장기의 혈류역동학적 변동으로서 문맥압의 증가와 동반하여 장간의 혈류량 증가와 혈관저항의 감소뿐만 아니라 전신 혈관저항의 감소가 특징적으로 야기된다. 문맥고혈압에 있어서 propranolol이 beta 1과 beta 2 수용체의 봉쇄작용으로 문맥고혈압을 저하시킨다는 점에서 사용되기도 한다. 본 실험에서는 흰쥐에서 문맥을 부분적으로 결찰하여 문맥고혈압을 야기하고 10일 후에 내장장기의 혈류역동학적 변동과 혈관 수축성 약물에 대한 반응성의 변동을 관찰하였다. 동시에 이에 대한 propranolol의 효과도 검토하였다. 문맥 결찰 후에는 비 펄프압의 증가와 동반하여 내장장기의 혈류량과 모세혈관압 증가가 야기되었고 동시에 모세혈관 전 저항(Ra)과 모세혈관 후 저항(Rv)은 저하되었다. Noradrenaline에 대한 Rv의 증가반응, adrenaline에 대한 Ra와 Rv의 증가반응, 및 phenylephrine에 대한 상장간막 동맥압, Ra및 Rv의 증가반응이 특징적으로 문맥결찰군에서 대조군에 비하여 현저히 약화되었다. Propranolol 처치군(PPL-3)에서 장간막 혈류량의 감소가 초래되었고, 문맥결찰군에서 저하된 Ra와 Rv가 propranolol투여로 대조군 수치로 회복되 었다. 이러한 성적의 결과로 문맥 결찰에 의하여 장간막 혈류량 증가와 동반된 Ra와 Rv의 저하는 비 펄프압 증가로 야기된 것으로 추측되며 내장장기 혈류역동학적 및 혈관 반응도의 변동은 장기적인 propranolol 처치로 효과있게 교정되는 점으로 미루어 내장장기의 과혈류역동은 내장장기 혈관의 아드레나린성 수용체의 기능변동과 밀접한 관련이 있다고 사료되었다.

• 접착 및 계면
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• 제15권3호
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• pp.116-122
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• 2014

자외선 경화법을 이용한 강판의 표면 코팅 시 사용되는 올리고머, 단량체, 광개시제 및 강판의 특성 등 주요 인자가 코팅 표면의 $20^{\circ}$ 및 $60^{\circ}$ 광택도(ASTM D523)에 미치는 영향에 대해서 연구하였다. 공정 변수에 대한 광택도의 변화는 $60^{\circ}$ 광택도에 비해 $20^{\circ}$ 광택도가 민감하게 변화하였다. 단독으로 올리고머를 사용할 경우의 경우, 광택도의 변화는 거의 없었으나, 올리고머의 혼합 비율이, 단량체의 종류와 혼합 비율, 올리고머와 단량체의 혼합 비율, 개시제의 종류와 함량 비, 강판의 종류는 광택도에 큰 영향을 주었다. 올리고머 혼합의 경우 폴리우레탄 아크릴레이트(UA)와 에폭시 아크릴레이트(EA)의 혼합 비율이 70 : 30, 단량체의 경우 트리메틸올프로판트리아크릴레이트(TMPTA)와 테트라히드로퍼퍼릴아크릴레이트(THFA)가 5 : 5의 비율로 혼합된 경우가, 혼합 올리고머(UA : EA = 70 : 30)의 함량이 90 wt%인 경우 최대의 광택도를 나타내었다. 광개시제 중 액체 타입인 Darocur MBF가 고체 타입인 Irgacure 184에 비해 우수한 광택도를 나타내었으며, 최소 투입량인 1 wt%의 농도에서 높은 광택도를 나타내었다. 기질의 경우, EG강판이나 primer가 처리된 강판에 비해 GI강판이 더 좋은 광택도를 보여주었다. 상기 공정 변수에 대한 연구를 통해 광택도 향상을 위해 사용되는 첨가제 없이도 $20^{\circ}$ 광택도 95 GU의 최대값을 $60^{\circ}$ 광택도는 120 GU의 광택도를 얻을 수 있었다.

• Korean Journal of Radiology
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• 제24권11호
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• pp.1081-1092
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• 2023

Objective: To investigate the incidence of microvascular myocardial ischemia in diabetic patients without obstructive coronary artery disease (CAD) and its relationship with angina. Materials and Methods: Diabetic patients and an intermediate-to-high pretest probability of CAD were prospectively enrolled. Non-diabetic patients but with an intermediate-to-high pretest probability of CAD were retrospectively included as controls. The patients underwent dynamic computed tomography-myocardial perfusion imaging (CT-MPI) and coronary computed tomography angiography (CCTA) to quantify coronary stenosis, myocardial blood flow (MBF), and extracellular volume (ECV). The proportion of patients with microvascular myocardial ischemia, defined as any myocardial segment with a mean MBF ≤ of 100 mL/min/100 mL, in patients without obstructive CAD (Coronary Artery Disease-Reporting and Data System [CAD-RADS] grade 0-2 on CCTA) was determined. Various quantitative parameters of the patients with and without diabetes without obstructive CAD were compared. Multivariable analysis was used to determine the association between microvascular myocardial ischemia and angina symptoms in diabetic patients without obstructive CAD. Results: One hundred and fifty-two diabetic patients (mean age: 59.7 ± 10.7; 77 males) and 266 non-diabetic patients (62.0 ± 12.3; 167 males) were enrolled; CCTA revealed 113 and 155 patients without obstructive CAD, respectively. For patients without obstructive CAD, the mean global MBF was significantly lower for those with diabetes than for those without (152.8 mL/min/100 mL vs. 170.4 mL/min/100 mL, P < 0.001). The mean ECV was significantly higher for diabetic patients (27.2% vs. 25.8%, P = 0.009). Among the patients without obstructive CAD, the incidence of microvascular myocardial ischemia (36.3% [41/113] vs. 10.3% [16/155], P < 0.001) and interstitial fibrosis (69.9% [79/113] vs. 33.3% [8/24], P = 0.001) were significantly higher in diabetic patients than in the controls. The presence of microvascular myocardial ischemia was independently associated with angina symptoms (adjusted odds ratio = 3.439, P = 0.037) in diabetic patients but without obstructive CAD. Conclusion: Dynamic CT-MPI + CCTA revealed a high incidence of microvascular myocardial ischemia in diabetic patients without obstructive CAD. Microvascular myocardial ischemia is strongly associated with angina.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2004년도 춘계 학술발표대회 개요집
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• pp.87-89
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• 2004

Brazing is an indispensable manufacturing technology for liquid rocket engine. In this study, for LRE injector, stainless steel 316L was used of base metal and Ni based MBF-20 of insert metal. The brazing and diffusion was carried out under various conditions. There are solid phase and. residual liquid phase in the brazed joint. With increment of holding time, the amount of solid phase increased and the elements of base metal and insert metal compositionally graded. Boron diffused from insert metal came into base metal and made boride with Cr and Mo at the brazed joint of base metal and insert metal.

• 한국항공우주학회지
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• 제30권8호
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• pp.65-70
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• 2002

본 연구에서는 로켓엔진에 사용되고 있는 2상 스테인리스강의 브레이징 접합성에 관하여 접합 현상과 기계적 강도의 두가지 측면의 고찰을 통하여 검증하였다. UNS32550을 모재로, MBF-50을 인서트금속으로 사용하여 브레이징 접합온도를 1473K, 1498K로 변화시키고, 접합 시간은 0~1.8ks로 변화시키면서 각 조건에서의 접합현상을 고찰한 결과, 접합부에서는 모재와 인서트금속간의 반응으로 인해 다양한 상이 생성되었다. 접합 초기에는 접합계면 및 접합부 근방의 모재에서 BN가 생성되고, 접합계면에서는 Cr질화물이 생성되어 접합 시간이 증가함에 따라 BN과 Cr질화물의 양이 감소하였다. 전단시험 결과 500MPa의 우수한 전단강도를 얻었다.

• Journal of Oral Medicine and Pain
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• 제47권4호
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• pp.206-211
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• 2022

Purpose: The purpose of this study is to develop a reproducible and reliable method for evaluating the masseter's functional state by measuring the masseter muscle with ultrasonography (US). Methods: Nineteen healthy adults (9 males, 10 females) were the subjects of this study. During US scanning, the image was taken from the thickest part of the masseter muscle in the image. To evaluate changes in thickness during masseter function, US images were taken of the participant's masseter muscle at rest and during clenching. In this study, US scanning was conducted using two approaches to compare the difference in masseter muscle thickness determined when inducing maximum bite force (MBF). Results: All 19 subjects completed US scanning of the masseter muscle at rest and during clenching under the conventional method and the articulation paper method. There was no difference in masseter muscle thickness measured at rest. However, the thickness of the masseter muscles determined by the articulation paper during jaw clenching was greater than that measured by the conventional method. Conclusions: In conclusion, using the US for masseter muscle evaluation can offer objective and functional information on the masseter muscle. A standardized US scanning method needs to be developed to obtain reproducible and reliable information on the masseter muscle at rest and during clenching. In particular, generating MBF using an articulation paper can be a reproducible and reliable method of measuring the functional state of the masseter muscle.

• 대한핵의학회:학술대회논문집
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• 대한핵의학회 2004년도 추계학술대회 및 총회
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• pp.403.1-403.1
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• 2004

• 대한핵의학회:학술대회논문집
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• 대한핵의학회 2000년도 2nd Korea-China Congress of Nuclear Medicine and 39th Annual Spring Meeting if the Korea SOciety Nuclear Medicine
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• pp.81.2-81.2
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• 2000

• Journal of Welding and Joining
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• 제21권2호
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• pp.64-69
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• 2003

The bonding phenomena and mechanical property of duplex stainless steel during brazing have been investigated. The UNS32550 was used for base metal, and the MBF50 was used for insert metal. Brazing was carried out under the various conditions (brazing temperature : 1473K, 1498K, holding time : 0∼1.8ks). There were various microconstituents in the bonded interlayer because of reaction between liquid insert metal and base metal. In the early stage of brazing, BN is formed in the bonded interlayer and base metal near the bonded layer. Cr made is formed in the bonded interlayer. The amount of BN and Cr nitrides decrease with the increase of bonding temperature and holding time. Superior shear strength of 550MPa is obtained by restraining the formation of nitrides. (Received January 17, 2003)

• Journal of Welding and Joining
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• 제18권4호
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• pp.96-103
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• 2000

This study investigated the effects of bonding temperature and bonding atmosphere on high temperature mechanical properties of transient liquid phase(TLP) bonded joints of heat resistant alloy using MBF-50 insert metal. Specimens were bonded at 1,423~1,468K for 600s. Microconstituents of {TEX}$Cr_{7}(C,B)_{3}${/TEX}were formed in the bonded region when the bonding temperature was low. The amount of microcostituents in the bonded layer decreased with increasing the bonding temperature, and the microconstituents in the bonded layer disappeared at the bonding temperature above 1,468K. The tensile strength of the joints at elevated temperatures increased with the increase the bonding temperature and was the same level as one of the base metal in the bonding temperature over 1,453K. Microstructure and alloying element distributions of the bonded region bonded in Ar and $N_2$atmosphere were similar to those of the bonded in vacuum. The creep rupture strength and rupture lives of joints were almost identical to those of base metal.