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        • KCI등재

          생체용 Ti-18Nb-6Zr-XO (X = 0~1.5at%) 합금의 형상기억특성에 미치는 산소 농도의 영향

          박영철,옥지면,오정화,박수호,이준희,김재일,Park, Young-Chul,Ock, Ji-Myeon,Oh, Jeong-Hwa,Park, Su-Ho,Lee, Jun-Hee,Kim, Jae-Il 한국재료학회 2011 한국재료학회지 Vol.21 No.11

          The effect of oxygen on the shape memory characteristics in Ti-18Nb-6Zr-XO (X = 0-1.5 at%) biomedical alloys was investigated by tensile tests. The alloys were fabricated by an arc melting method at Ar atmosphere. The ingots were cold-rolled to 0.45 mm with a reduction up to 95% in thickness. After severe cold-rolling, the plate was solution-treated at 1173 K for 1.8 ks. The fracture stress of the solution-treated specimens increased from 450 Mpa to 880 MPa with an increasing oxygen content up to 1.5%. The fracture stress increased by 287MPa with 1 at% increase of oxygen content. The critical stress for slip increased from 430 MPa to 695 MPa with an increasing oxygen content up to 1.5 at%. The maximum recovery strain of 4.1% was obtained in the Ti-18Nb-6Zr-0.5O (at%) alloy. The martensitic transformation temperature decreased by 140 K with a 1.0 at% increase in O content, which is lower than that of Ti-22Nb-(0-2.0)O (at%) by 20 K. This may have been caused by the effect of the addition of Zr. This study confirmed that addition of oxygen to the Ti-Nb-Zr alloy increases the critical stress for slip due to solid solution hardening without being detrimental to the maximum recovery strain.

        • KCI등재후보

          웨이블릿을 이용한 QRS complex 검출 알고리즘의 고정 소수점 연산 최적화

          박영철,Park, Young-chul 한국정보전자통신기술학회 2014 한국정보전자통신기술학회논문지 Vol.7 No.3

          본 논문에서는 웨이블릿 변환을 통하며 QRS complex를 검출 하며, 32비트 고정 소수점 연산이 가능한 프로세서에도 동작하도록 알고리즘 최적화 기법을 제시한다. 먼저 입력 ECG 신호를 밴드 패스 필터를 통과 시키고, 3개의 서로 다른 웨이블릿 함수를 하나로 병합한 웨이블릿 함수를 이용하여 웨이블릿 변환을 하며, 다음으로 시간 평균 함수를 뒤에 마지막으로 QRS complex를 검출 한다. 제안 알고리즘은 MIT-BIH arrhythmia database에 적용하여 검증한다. 모든 과정은 32비트 고정 소수점 연산으로 구현되며, 삼각함수 같은 복잡한 연산은 테이블화 하였다. 검출 알고리즘은 컴퓨터 시뮬레이션을 통해 평가 한다. In this study, QRS complex is detected by Wavelet Transform and it can be worked in 32bit fixed point operation thought optimization. First, ECG signal is passed though band pass filter. Second, it is transformed using one-band combined wavelet function from 3-band wavelet function. Third, it is passed though moving window integral. Finally, QRS complex is detected by decision rule. The proposed algorithm is evaluated using MIT-BIH arrhythmia database. Its all of process make progress 32-bit fixed-point operation and it makes table that high complexity operations like trigonometrical function. The detection algorithm evaluate through computer simulation.

        • KCI등재후보

          숙지황(Rehmannia glutinosa)의 약리작용과 독성

          박영철,이기용,백낙민,손혜영,국윤범,이선동,Park, Yeong-Chul,Lee, Gi-Yong,Baek, Lag-Min,Son, Hye-Young,Kook, Yoon-Boom,Lee, Sun-Dong 대한한의학방제학회 2011 大韓韓醫學方劑學會誌 Vol.19 No.1

          Objectives : Rehmannia glutinosa has been used extensively in Korean traditional medicine. Although thorough clinical trials are lacking, Various pharmacological actions for Rehmannia glutinosa has been identified newly using animal models. In addition, it was reported that reactive intermediates, potentially causing toxic effects, was isolated from one of components in Rehmannia glutinosa. In this article, it is purposed for explanation and introduction of new studies for Rehmannia glutinosa in terms of pharmacological action and toxicology. Methods : New studies for Rehmannia glutinosa were reviewed and summarized in terms of pharmacological action and toxicity. Results and Conclusions : Rhmannia glutinosa and its components including iridoids, saccharides, as well as amino acid, showed a variety of pharmacological actions on the blood system, immune system, endocrine system, cardiovascular system and the nervous system. In addition, it was identified that aucubin, one of major components of Rhmannia glutinosa was biotransformed to reactive intermediates by ${\beta}$-glycosidase and acid-hydrolysis, resulting in forming aucubigenin- albumin adduct. Even if a lot of new pharmacological actions has been identified, it should be considered for Rhmannia glutinosa to contain the material producing reactive intermediates which may induce the side effects.

        • 틸트 로터형 무인항공기의 손상허용 설계

          박영철,임종빈,박정선,Park, Young Chul,Im, Jong Bin,Park, Jung Sun 항공우주시스템공학회 2007 항공우주시스템공학회지 Vol.1 No.2

          '스콜라' 이용 시 소속기관이 구독 중이 아닌 경우, 오후 4시부터 익일 오전 7시까지 원문보기가 가능합니다.

          The Damage Tolerant Design is developed to help alleviate structural failure and cracking problems in aerospace structures. Recently, the Damage Tolerant Design is required and recommended for most of aircraft design. In this paper, the damage tolerant design is applied to tilt rotor UAV. First of all, the fatigue load spectrum for the tilt rotor UAV is developed and fatigue analysis is performed for the flaperon joint which has FCL (fatigue critical location). Tilt rotor UAV has two modes: helicopter mode when UAV is taking off and landing; fixed wing mode when the tilt rotor UAV is cruising. To make fatigue load spectrum, FELIX is used for helicopter mode. TWIST is used for fixed wing mode. Fatigue analysis of flaperon joint is performed using fatigue load spectrum. E-N curve approach is used for picking crack initiation point. The LEFM(Linear Elastic Fracture Method) is considered for analyzing crack growth or propagation. Finally, including the crack initiation and propagation, the fatigue life is evaluated. Therefore the Damage Tolerant Design can be done.

        • KCI등재후보

          배양망막색소상피세포에서 젤라틴아제의 발현에 대한 산화스트레스의 영향

          박영철,최광주,Young-Chul Park,Gwang-Ju Choi 대한안과학회 2005 대한안과학회지 Vol.46 No.11

          '스콜라' 이용 시 소속기관이 구독 중이 아닌 경우, 오후 4시부터 익일 오전 7시까지 원문보기가 가능합니다.

          Purpose: To evaluate the expression pattern of gelatinases in the human retinal pigment epithelial cell line ARPE-19 in response to oxidative stress. Methods: ARPE-19 cells were exposed to paraquat for 72 hours. The cells were assayed for the mRNA expression of gelatinase A and gelatinase B by reverse transcriptase polymerase chain reaction (RT-PCR). The conditioned media were assayed for the production of gelatinases protein by Western blotting. Also, the inhibitory effect of the antioxidants against oxidative stress to the cells was evaluated. Results: The gelatinase levels in the RPE cells increased under oxidative stress compaired with the control (p〈 0.05). Also, the levels decreased when the cells were incubated with the antioxidant N-acetylcysteine (NAC). Conclusions: Oxidative stress upregulates gelatinase expression in ARPE-19 cells.

        • SCOPUSKCI등재

          세라믹/금속접합재의 고온 열사이클에 따른 잔류응력분포 및 굽힘강도 특성

          박영철,허선철,부명환,김현수,강재욱,Park, Young-Chul,Hue, Sun-Chul,Boo, Myoung-Hwan,Kim, Hyun-Su,Kang, Jae-Wook 대한기계학회 1997 大韓機械學會論文集A Vol.21 No.10

          Since the ceramic/metal joint material is made at a high temperature, the residual stress develops when it is cooled from bonding temperature to room temperature due to remarkable difference of thermal expansion coefficient between ceramic and metal. As residual stress at ceramic/metal joints influences the strength of joints, it is important to estimate residual stress quantitatively. In this study, it is attempted to estimate joint residual stress of Si$_3$N$_4$STS304 joints quantitatively and to compare the strength of joints. The difference of residual stress is measured when repeated thermal cycl is loaded, under the conditions of the practical use of the ceramic/metal joint. The residual stress increases at 1 cycle of thermal load but decreases in 3 cycles to 10 cycles of thermal load. And 4-point bending test is performed to examine the influence of residual stress on fracture strength. As a result, it is known that the stress of joint decreases as the number of thermal cycle increases.

        • KCI등재

          적외선 체열 촬영을 이용한 중풍(中風) 편마비(片痲痺) 환자(患者)의 합곡혈(合谷穴) 일반 자침시(刺針時)와 심자시(深刺時) 피부온도변화(皮膚溫度變化) 관찰(觀察)

          박영철,채진석,엄재용,송성세,최익선,Park, Young-chul,Chae, Jin-seok,Eom, Jae-yong,Son, Sung-se,Choe, Ick-seon 대한침구의학회 2003 대한침구의학회지 Vol.20 No.4

          Objective : This study designed to find out the effects of deep acupuncture in cerebrovascular hemiplegia. Methods : This study was performed on 30 patients with cerebrovascular hemiplegia to observe difference in temperature of skin surface between general acupuncture and deep acupuncture at Hapkok using digital infrared thermographic imaging(D.I.T.I.) Results : 1. Temperature of paralytic side is sigficantly higer $0.39{\pm}0.78^{\circ}C$ than that of contralateral side. 2. Thermal difference(${\Delta}T$) of paralytic side-contralateral side decreased $0.08{\pm}0.53^{\circ}C$ after general acupuncture, but there is no significant. $0.20{\pm}0.50^{\circ}C$ after deep acupuncture decreased significantly. So deep acupuncture is more effective than general acupuncture. 3. Thermal difference of paralytic side-paralytic side and contralateral side-contralateral side decreased significantly after acupuncture, and thermal difference of deep acupuncture on paralytic side-paralytic side decreased $0.42{\pm}1.07^{\circ}C$ more than that of general acupuncture. So deep acupuncture is more effective than general acupuncture. Conclusions: This study showed that deep acupuncture is more effective than general acupuncture In cerebrovascular hemiplegia, and further study is needed on clinical trials.

        • KCI등재

          Performance Analysis of Saturation Routing Algorithm in Non-Hierarchical Networks

          박영철,Park Young-Chul Digital Contents Society 2002 한국디지털콘텐츠학회논문지 Vol.3 No.1

          포화 경로 선정 알고리즘은 주로 전술적 응용 및 패킷 라디오 망에 유용한 경로 선정 알고리즘으로 알려져 있는데, 이유는 통화로 개설 시간이 짧고 경로 선정 테이블을 갖고 있지 않기 때문이다. 통신망 효율 면에서는 통제 메시지의 오버 해드로 인해 약점이 있기도 하다. 본 논문에서는 4개의 링크로 구성된 격자형 전술 회선 교환망에 두개의 우선 순위 음성 트래픽을 갖는 망을 고려하였다. 최소 1차 미분 길이를 갖는 경로를 이용하여 통화로 개설 시간 및 알고리즘 처리 부하를 증가 시키지 않으면서 회선망의 차단 확률을 향상 시켰다. Saturation routing algorithm is known to be an effective routing mechanism for tactical application and packet radio networks, since it minimizes the call set-up time and does not have to maintain routing tables. But, it is known that it has significant drawbacks with respect to the network efficiency, the overhead on the control messages [1]. We consider a tactical circuit-switched grid network with a maximum of tour links and two priority classes of voice traffic. Using the minimum first-derivative length (MFDL) path, we improve the blocking probability performance of a circuit-switched network without increasing the call set-up time and processor loading of the algorithm.

        • mBHT의 랫드를 이용한 단회경구투여 독성시험

          박영철,박용기,Park, Young-Chul,Park, Yong-Ki 동국대학교 한의학연구소 2008 東國韓醫學硏究所論文集 Vol.11 No.-

          Objectives: The study was designed to evaluate the single dose toxicity of modified Bo-yang-Hwan-o-Tang (mBHT) in Sprague-Dawley (SD) rats. Methods: The mBHT was once administrated orally to both sexes of rats at dose 2,000 mg/kg body weight which are the recommended maximum limit dose for acute toxicity. We recorded clinical signs of toxicity, body weight, gross and histological changes in target organs for all rats. Results: Neither significant changes of body weight not death was observed during the observation period in mBHT-administrated rats. Neither significant toxic signs not histopathological changes were shown during the observation period. There were not observed significant gross abnormality between the control and mBHT-administrated rats. Conclusions: These results indicated that the toxicity of mBHT is greater than 2,000 mg/kg body weight in SD rats.

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