• 한국압력기기공학회 논문집
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• 제20권1호
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• pp.25-31
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• 2024

The core shroud of rector vessel internals (RVI) of OPR1000 and ARP1400 is made of Type 304 stainless steel (SS) by bending and welding process that may induce high deformation and residual stress in manufacturing. This work aims to evaluate the susceptibility of stress corrosion crack (SCC) initiation of bent parts of RVI in high temperature primary water environment. For SCC initiation test, tensile specimens were fabricated from the 90 degree bent plate of Type 304 SS (DT specimen), that is an archived part of a Korean APR1400. After the SCC initiation test, the specimen surface was thoroughly examined by optical and scanning electron microscopy, and compared to the specimen fabricated from the as-received plate of Type 304 SS (AR specimen). The surface observation revealed that SCC initiated on the AR specimen surface in typical intergranular (IG) mode, while SCC on the DT specimen occurred in transgrannular mode as well as IG mode. It was also found that the size and number of SCC on the DT specimen were larger than that on the AR specimen. This was attributable to a strain-hardening during the bending process. To compare the susceptibility of SCC initiation, total crack density (TCD) was calculated from the total crack length divided by the measured area of AR and DT specimens. TCD of DT specimen was 4.6 times higher than AR specimen in average, indicating that higher possibility of degradation of bent parts of RVI for a long-term operation.

• 공업화학
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• 제18권3호
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• pp.205-212
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• 2007

본 연구는 polyacrylonitrile (PAN)를 dimethyl formamide (DMF)에 용해시켜 전압조건을 8~20 kV, PAN 농도조건을 5~15 wt%, 그리고 tip-to-collector distance (TCD)를 15 cm로 다양한 조건에서 전기방사를 실시하였다. 나노섬유는 $250^{\circ}C$에서 1 h 동안 안정화시켰으며, $800{\sim}1000^{\circ}C$에서 1 h 동안 탄화시켰다. 안정화와 탄화 전후의 나노섬유의 구조 특성은 FT-IR 장비를 이용하여 연구하였으며 나노섬유의 직경분포와 모폴로지 특성을 알기 위해서 SEM 분석장비를 이용하였다. 나노섬유웹의 전기화학적 특성은 순환전류 전압곡선 특성 실험을 통해 고찰하였다. 실험 결과로부터 전기방사한 나노섬유의 직경의 크기는 일반적으로 방사용액의 농도와 인가전압에 영향을 받는다는 것을 확인할 수 있었으며 섬유의 평균 직경은 고분자의 농도 10 wt% 이상 증가함에 따라 감소하며 15 kV의 전압과 15 cm의 TCD 조건에서 섬유의 직경분포가 균일하고 평균직경이 작은 것으로 나타났다.

• 대한한방내과학회지
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• 제29권4호
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• pp.950-961
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• 2008

Objectives : The purpose of this study was to compare cerebral biood flow between hypertensives and normotensives using transcranial doppler ultrasonography (TCD). Methods : I investigated cerebral blood flow of 72 hypertensives and 127 normotensives. To evaluate the cerebral blood flow, I measured the systolic peak velocity(Vs) and mean How velocity (Vm) of the middle cerebral artery(MCA), anterior cerebral artery(ACA), posterior cerebral artery(PCA), basilar artery(BA), and internal carotid artery(ICA) in the two groups using TCD. Result : 1. There was a decrease in the Vs and Vm of all examined vessels of hypertensives in comparison with normotensives. There was a significant difference in the Vs of ACA and Vm of ACA, PCA, ICA. 2. In males, there was a decrease in the Vs of ACA, PCA, ICA and Vm of MCA, ACA, PCA, ICA of hypertensives in comparison with normotensives. However, there was no significant difference in the Vs or Vm of all examined vessels. 3. In females, there was a decrease in the Vs and Vm of all examined vessels of hypertensives in comparison with normotensives. There was a significant difference in the Vs of MCA, ACA and BA and Vm of ACA, PCA and BA. 4. In 30-49 year-olds, there was a decrease in the Vs and Vm of all examined vessels of hypertensives in comparison with normotensives. There was a significant difference in the Vs of ACA and Vm of ACA. 5. In 50-69 year-olds, there was a decrease in the Vs of ACA, PCA, BA, ICA and Vm of all examined vessels of hypertensives in comparison with normotensives. However, there was no significant difference in the Vs or Vm of all examined vessels. 6. In 70-89 vests old. there was a decrease in the Vs. Vm of PCA, BA, ICA of hypertensives in comparison with normotensives. But, there was no significant difference in the Vs, Vm of all examined vessels. Conclusions : There was a significant difference in the cerebral blood now velocity between hypertensives and normotcnsives. These results suggest that blood pressure has influence on cerebral blood flow.

• Radiation Oncology Journal
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• 제9권1호
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• pp.7-15
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• 1991

Pentoxifylline (PENTO)는 적혈구의 유동성을 증가시켜 모세혈관의 적혈구 흐름을 증가시킨다. 또한 적혈구내 2,3-DPG를 증가시켜서 산소 친화력을 감소시켜 산소의 해리를 촉진시킨다. Nicotinamide (NA)는 종양내 혈류를 일시적으로 증가시켜서 종양내 급성 저산소 세포의 수를 감소시킨다. PENTO와 NA의 병용이 저산소 세포의 산소화에 의해서 방사선 감수성을 증가시킬 수 있는지를 확인하기 위하여 FSaII생쥐의 섬유육종을 이용하여 실험을 시행하였다. 방사선에 의한 성장 장애가 유의하게 증가하였으며, 증가율은 2.5~2.8이었다. $TCD_{50}$가 대조 종양군에서는 57Gy였으나 PENTO+NA투여 종양군에서는 32Gy로 1.8배의 $TCD_{50}$의 감소를 보였다. 정상피부의 방사선 감수성에는 영향이 없었다. PENTO+NA의 방사선 감수성의 증가를 규명하기 위하여 종양내 혈류의 변화, 종양내 산소농도를 laser Doppler flowmetry와 산소 미소전극 방법으로 측정하였다. PENTO+NA투여후 10분 경과하여 혈류가 유의하게 증가하였으며 종양내 산소 분압도 8 mmHg에서 19 mmHg로 유의하게 증가함을 관찰하였다. 따라서 PEHTO또는 NA단독보다 PENTO+NA병통이 더욱 효과적이라 사료되며 생체내 종양의 방사선 감수성의 증가는 종양내 산소의 증가로 생각되며 더욱 방사선 감수성을 증가시키기 위하여 여러 농도의 PENTO의 단독 또는 NA와의 병용등에 대한 지속적인 연구가 필요하다.

• 생명과학회지
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• 제30권6호
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• pp.550-554
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• 2020

이 연구의 목적은 시험관내 TCD (테스토스테론 화합물 검출) 시스템으로 8개 한약재의 테스토스테론 유사 활성을 검색하는 것이었다. 녹각상, 백수오, 야관문, 홍삼, 토령, 민들레, 남가세, 호로파의 열수 추출물과 80% 에탄올 추출물을 5, 50, 500 ㎍/ml의 농도로 in vitro TCD 시스템에 적용하였다. 80% 에탄올 추출물의 테스토스테론 유사 활성은 일반적으로 농도에 비례하였고, 음성대조군보다 0.9 내지 5.0 배 더 높았다. 호로파와 야관문은 동일한 농도에서 우수한 테스토스테론 유사 활성을 보였으며 민들레와 홍삼이 그 뒤를 이었다. 토령과 남가세는 낮은 테스토스테론 유사 활성을 보였으며 녹각상과 백수오는 매우 낮은 활성을 나타냈다. 양성대조군 5α-DHT의 활성과 비교하면, 호로파 및 야관문의 80% 에탄올 추출물은 500 ㎍/ml에서 10^-8 M 5α-DHT보다 높은 테스토스테론 유사 활성을 나타냈다. 열수 추출물은 80% 에탄올 추출물보다 낮은 테스토스테론 유사 활성을 보였고, 농도에 따른 활성의 증가도 에탄올 추출물보다 낮았다. 호로파, 야관문 및 민들레 등의 80% 에탄올 추출물이 테스토스테론 관련 유전자의 전사 효율을 향상시킬 수 있음이 확인되었다. 따라서, 본 연구는 남성 갱년기 증상의 개선에 필요한 건강 기능성 식품 재료 또는 의약 재료를 개발하는 데 참고가 될 수 있을 것이다.

• Journal of Chest Surgery
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• 제37권1호
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• pp.50-55
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• 2004

배경: 경두개 초음파 검사는 색전의 위험이 있는 환자에서 미세색전 신호를 진단할 수 있다. 미세색전 신호의 임상적 중요성은 인공 기계 심장 판막 환자에서는 아직 증명되지 않았다. 우리는 인공 기계 심장 판막 수술 후의 뇌 혈전색전증과 산소 흡입 중 측정되는 미세색전 신호의 관련성을 연구하였다. 대상 및 방법: 인공 기계 심장 판막 수술 후 뇌 혈전색전증의 병력이 있는 20명의 환자군과 성별, 연령별로 일치시킨 30명의 대조군을 대상으로 연구하였다. 경두개 초음파 검사로 일측 중대뇌동맥을 감시하였다. 20분간의 기초 검사 후 40분 동안 100% 산소를 흡입하면서 검사하였다. 결과: 인공 기계 심장 판막의 수술 부위와 수술 후 기간은 환자군과 대조군의 차이가 없었다. 기초 검사 동안 측정된 미세색전 신호의 양성률과 빈도는 양 군 간의 차이가 없었다. 산소 흡입 중 환자군은 대조군에 비하여 미세색전 신호의 양성률이 높았고(55%, 27.6%, p=0.045), 미세색전 신호수도 흔하였다(p=0.027). 결론: 산소 흡입을 이용한 경두개 초음파 검사는 인공 기계 심장 판막 이식 환자에서 임상적으로 의미가 있는 미세색전의 감별에 도움이 된다.

• Journal of Biosystems Engineering
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• 제43권3호
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• pp.161-172
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• 2018

Purpose: During tillage operations, the selection of a working machine (tool) depends on the soil conditions as well as the type of tillage operation to be performed. The goal of this research was to ascertain the effects of varying working machine parameters of a compact disc harrow on tillage operations under various soil moisture content (SMC) conditions. Methods: The working machine parameters were the disc spacing and machine speed. The tillage parameters under investigation were the soil inversion ratio (SIR), tillage cutting depth (TCD), and soil clod breakage ratio (SCB). To determine the SIR, the areas of the white regions before and after tillage were obtained. The ratio of the difference of the areas of the white regions before and after tillage to the area of the white regions before tillage was considered as the SIR. The SCB was obtained as the ratio of the weight of soil clods after sieving with a mesh size of <0.02 m to the total weight of the soil clods before sieving. The soil TCD was measured using a tape measure at random points after the tillage operation. The resulting data were statistically analyzed in a one-way analysis of variance. Results: The highest soil inversion was achieved when the machine speed was 0.2 m/s with the disc spaced at 0.2 m in the 16.5% SMC. At a 0.4-m/s machine speed and 0.3-m disc spacing the highest soil breakage was achieved in the 26.5% SMC. The highest TCD was achieved at a 0.2-m/s machine speed and 0.2-m disc spacing in the 16.5% SMC. Conclusions: It was concluded that varying the working machine parameters, such as the disc spacing and machine speed, could significantly affect the soil inversion and soil clod breakage; however, it had no significant impact on the TCD.

• 동의생리병리학회지
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• 제23권6호
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• pp.1513-1520
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• 2009

The purpose of this study was to compare cerebral blood flow between hyperlipidemic patient group and normal healthy aldult group using transcranial doppler ultrasonography(TCD). I investigated cerebral blood flow of 63 hyperlipidemic patients and 42 healthy adults. To evaluate the cerebral blood flow, I measured the systolic peak velocity(Vs) and mean flow velocity(Vm) of the milddle cerebral artery(MCA), anterior cerebral artery(ACA), posterior cerebral artery(PCA), basilar artery(BA), internal carotid artery(ICA) in the two groups using TCD. In normal healthy adults, subjects showed a decerease in Vs and Vm with advancing in age. There was a significant difference in the Vm of ICA. There was no significant differences in the Vm of ACA and ICA. In normal healthy adults, females showed high velocities of all examined vessel. There was a significant difference in the Vs of ICA. There was a significant differences in the Vm of MCA and ICA. Normal healthy adults higher than hyperlipidemic patients in the Vs of MCA, ACA, PCA. There was no significant difference in the Vs of all exmined vessels. Hyperlipidemic patientsincrease higher than normal healthy adults in the Vm of ACA. There was a significant difference in the Vs of BA. In the patients aged under 50's, normal healthy adults higher than hyperlipidemic patients in the Vs and Vm except BA. But there was no significant difference in all exmined vessels. In the patients aged over 50's, hyperlipidemic patients higher than normal healthy adults in all examined vessel expect PCA. There was a significant difference in the Vs of BA and ICA. And hyperlipidemic patients higher than that normal healthy adults in all exmined vessels. There was a significant difference in BA and ICA. In this study, visible differences in blood flow between hyperlipidemic patient group and normal healthy aldult group were shown. However, these results do not come up to the previous values that were reported and known worldwide.

• 감성과학
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• 제19권2호
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• pp.35-42
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• 2016

전기방사는 높은 비표면적을 가지는 마이크로~나노 단위 직경의 나노섬유를 생산하는 간단하고 효율적인 공정이다. 따라서 식물 추출물과 폴리머를 혼합한 방사용액으로 손쉽게 의료용 나노섬유의 제조가 가능하다. 향나무는 라디칼 생성, 화상, 세포손상과 같은 자외선과 SLS에 의한 피부손상을 방지하는데 효과적이라고 알려져 있다. 또한 방미효과와 함께 집먼지 진드기 방지 효과가 보고된 바 있다. 전기방사로 향나무 추출물을 함유하여 제조한 PVA 나노섬유를 연구하였다. 향나무 추출물의 서로 다른 농도(0.25, 0.5, 1.5 wt. %)를 함유하는 PVA/향나무 추출물 나노 복합섬유를 제조하였으며 방사용액의 농도, 인가전압, TCD 등의 전기방사 조건을 최적화 하였다. 연구결과 균일한 PVA/향나무 추출물 나노 복합섬유을 얻을 수 있는 최적 조건으로 PVA 농도는 12wt%, 인가전압은 10 Kv, TCD는 10~20 cm로 나타나났다. 제조된 전기방사 나노 복합섬유의 형태 및 미세구조를 SEM을 통해 관찰하였다. 향나무 추출물의 첨가에 의해 나노섬유의 직경이 증가하는 것으로 나타났다. 결과적으로 310~360 nm의 직경범위를 가지는 PVA/향나무 추출물 복합 나노섬유가 전기방사를 통해 성공적으로 얻어졌다.

• 대한한의진단학회지
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• 제14권2호
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• pp.85-100
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• 2010

Objectives: The purpose of this study was to evaluate diagnostic value of Transcranial Doppler Ultrasound about risk factor of stroke by comparing blood flow between patients with metabolic syndrome(MS group) and Normal group. Methods: 62 metabolic syndrome patients and 106 healthy adults were selected who had no cerebrovascular diseases, cardiovascular diseases and other systemic diseases. We measured the mean velocity(Vm), peak systolic velocity(Vs) and pulsatility index(PI) of MCA, ACA, PCA, VA, ICA in two groups using TCD. All subjects were divided by gender and age. Results: In comparing Ms group with normal group, Vm in the MCA, ACA, PCA, ICA and Vs in the MCA, ICA were lower in MS group. In all vessels, PI of MS group were higher than that of Normal group. In all vessels, Vm and Vs revealed negative correlation with age and PI revealed positive correlation with age. In 20-39 year olds, there was decrease in the Vs and Vm and increase of PI of MS group in comparison with normal group. There was significant difference in the Vm of PCA, ICA, Vs of MCA, PCA, ICA and PI of MCA, ACA. In 40-59 year olds, Vm in the MCA, ACA, ICA and Vs in the MCA, ACA were lower in MS group. PI in the MCA, ACA, PCA, ICA were higher in MS group. In 60-79 year olds, Vm of MCA, PCA, ICA was decreased in MS group than Normal group with no statistical signification. Vs in the MCA was lower and PI in the PCA was higher in MS group. In male, Vm of PCA and Vs of MCA were lower and PI of MCA, ACA, PCA, ICA were higher in MS group. In female, Vm of MCA, PCA, ICA and Vs of MCA, ICA were lower and PI of ACA, PCA, VA, ICA were higher in MS group. Conclusions: The significant difference in Vm, Vs, PI between MS group and normal group suggests hemodynamic disorder. Screening and prognosing high risk group can be done through TCD and this can be used to prevent stroke. More detailed study will be needed.