AN IN-SITU YOUNG'S MODULUS MEASUREMENT TECHNIQUE FOR NUCLEAR POWER PLANTS USING TIME-FREQUENCY ANALYSIS

Choi, Young-Chul,Yoon, Doo-Byung,Park, Jin-Ho,Kwon, Hyun-Sang Korean Nuclear Society 2009 Nuclear Engineering and Technology Vol.41 No.3

Elastic wave is one of the most useful tools for non-destructive tests in nuclear power plants. Since the elastic properties are indispensable for analyzing the behaviors of elastic waves, they should be predetermined within an acceptable accuracy. Nuclear power plants are exposed to harsh environmental conditions and hence the structures are degraded. It means that the Young's modulus becomes unreliable and in-situ measurement of Young's modulus is required from an engineering point of view. Young's modulus is estimated from the group velocity of propagating waves. Because the flexural wave of a plate is inherently dispersive, the group velocity is not clearly evaluated in temporal signal analysis. In order to overcome such ambiguity in estimation of group velocity, Wigner-Ville distribution as the time-frequency analysis technique was proposed and utilized. To verify the proposed method, experiments for steel and acryl plates were performed with accelerometers. The results show good estimation of the Young's modulus of two plates.

AN IN-SITU YOUNG’S MODULUS MEASUREMENT TECHNIQUE FOR NUCLEAR POWER PLANTS USING TIME-FREQUENCY ANALYSIS

YOUNG-CHUL CHOI,DOO-BYUNG YOON,JIN-HO PARK,권휴상 한국원자력학회 2009 Nuclear Engineering and Technology Vol.41 No.3

Elastic wave is one of the most useful tools for non-destructive tests in nuclear power plants. Since the elastic properties are indispensable for analyzing the behaviors of elastic waves, they should be predetermined within an acceptable accuracy. Nuclear power plants are exposed to harsh environmental conditions and hence the structures are degraded. It means that the Young’s modulus becomes unreliable and in-situ measurement of Young’s modulus is required from an engineering point of view. Young’s modulus is estimated from the group velocity of propagating waves. Because the flexural wave of a plate is inherently dispersive, the group velocity is not clearly evaluated in temporal signal analysis. In order to overcome such ambiguity in estimation of group velocity, Wigner-Ville distribution as the time-frequency analysis technique was proposed and utilized. To verify the proposed method, experiments for steel and acryl plates were performed with accelerometers. The results show good estimation of the Young’s modulus of two plates.

QR코드를 이용한 청소년 체험학습 쿠폰 시스템 개발

박순호 ( Soon Ho Park ),김유두 ( Yu Doo Kim ),문일영 ( Il Young Moon ) 한국실천공학교육학회 2013 실천공학교육논문지 Vol.5 No.1

PC의 빠른 보급으로 많은 사용자가 PC로 다양한 콘텐츠를 즐기고 있다. 특히 최근 들어 청소년들의 PC이용 률이 급격히 증가했다. 청소년들은 이러한 PC를 이용하여 보다 쉽게 정보를 얻을 수 있고, 특히 온라인 게임을 통하여 스트레스를 해소하고, 가상현실에서의 또 다른 재미를 느낄 수 있다. 이렇게 일찍부터 빠르게 발전하고 있는 IT문화를 접하는 것은 좋은 일인 것은 분명하다. 하지만 그로 인해 청소년들은 자연스럽게 실내 활동이 많아지게 되면서 야외활동이 줄어들게 됨에 따라 세상을 보는 시야 또한 많이 좁아지게 되었다. 따라서 청소년 들의 야외활동을 유도하기 위해 최근 많이 사용하는 스마트 폰 어플리케이션을 이용하여 현장체험 쿠폰 시스템을 구축하게 되었다. 그리고 HTML5를 기반으로 하는 하이브리드 앱을 개발함으로써 디바이스의 구분없이 사용할 수 있도록 하였다. 따라서 이 어플리케이션을 통해서 청소년들의 현장체험에 대한 관심과 동기를 유발시킴으로써 많은 볼거리를 체험하고, 다양한 시각에서 세상을 바라볼 수 있다. Because of rapid spread of the PC, many users have been enjoying a variety of content as PC. Especially in recent years, young people has increased dramatically PC usage. Young people get more easily information using a PC. Especially they relieve their stress through online games and feel another fun of virtual reality. It is obviously a good effect that they contact IT culture with rapidly developed. But young people`s perspective with world is narrow because of doing more indoor activities than outdoor. Therefore we built Spot experience voucher system using smart phone application. We hope that many young people act outdoor activities. And Our product offer hybrid device by developing HTML5-based app. Thus this app will give interest of spot-experience to young-people. So If young people use this app, they can have many experience and see diverse aspects.

가속도계를 이용한 재료의 영계수 측정방법

손창호(Sohn, Chang-Ho),박진호(Park, Jin-Ho),윤두병(Yoon, Doo-Byung),정의필(Chong, Ui-Pil),최영철(Choi, Young-Chul) 한국소음진동공학회 2006 한국소음진동공학회 논문집 Vol.16 No.11

For the description of the elastic properties of linear objects a convenient parameter is the ratio of the stress to the strain, a parameter called the Young's modulus of the material. Young's modulus can be used to predict the elongation or compression of an object as long as the stress is less than the yield strength of the material. Conventional method for estimating Young's modulus measured the ratio of stress to corresponding strain below the proportional limit of a material using a tensile testing machine. But the method needs precision specimens and expensive equipment. In this paper, we proposed method for estimating Young's modulus using accelerometer. The basic idea comes from that the wave velocity is different as the Young's modulus. To obtain Young's modulus, a group velocity is obtained. It is difficult to measure group velocity. This is because plate medium has a dispersive characteristics which has different wave speed as frequency. In this paper, we used Wigner-Ville distribution to measure group velocity. To verify the proposed method, steel and acryl plate experiments have been performed. Experimental results show that the proposed method is powerful for estimating Young's modulus.

GASKET LIFE CRITERIA AT LOW TEMPERATURES ADOPTING PROPORTIONAL COMPENSATION FOR LOSS OF FLEXIBILITY AND CONFORMABILITY

Young-Doo Kwon,Seong-Hwa Jun,Jin-Sik Han,Dong-Jin Lee 한국자동차공학회 2018 International journal of automotive technology Vol.19 No.1

In the automobile industry, the service life of gaskets is defined as the time until which a released gasket recovers 60 % of the original compression. It was observed that the recovery curves of gaskets were highly nonlinear at high temperatures, and relatively nonlinear at temperatures above the room temperature. However, it was also noted that the recovery curves of the gaskets at temperatures below room temperature exhibited linearity with respect to the ln(time). Automotive manufacturers demand gasket life criteria that exceed a specific time or the entire life of a car. In the case of gaskets used at lower temperatures, since materials encounter losses in its flexibility and conformability, the definition of service life specifying a 60 % recovery may not be sufficiently safe to eliminate possible leakages. In this study, new gasket life criteria that could be used at low temperatures were proposed. The new criteria were proposed based on the change in Young’s modulus of the gasket material in order to conserve the sealing capability.

흰쥐 視床下部 神經細胞의 [met]^(G4635)-enkephalin과 Oxytocin 同所存在性에 關한 免疫組織化學的 硏究

李永植,李永基,張家鏞,趙斗英 서울醫大 1990 精神醫學 Vol.15 No.2

孫昌涉 初期作品의 精神分析的 考察 : [死緣記], [비오는 날], [生滑的]을 對象으로 하여 Sa-yun-kee(a Death Record), Bi-o-neun-nal(a Rainy Day), and Saeng-hwal-chuk(Being Realistic)

趙斗英 大韓神經精神醫學會 1996 신경정신의학 Vol.35 No.2

The author has previously explored the psychodynamics of a Korean writer, Chang-Sup Sohn, based on his autobiographic novel, and the creative process of his maiden work in psychoanalytic point of view. In this article, the focus is placed on the psychodynamics of the creative processes on first three short-stories after the maiden work, namely "a Death Record", "a Rainy Day" and "Being 'Realistic". "A Death Record" is a story about a young man, whose personality is described as similar to that of the writer, supporting his friend and the family. This friend had married to the hero's fiancee while the hero was imprisoned as a political prisoner in North Korea. The friend is in terminal state of pulmonary tuberculosis, and becomes paranoid. After witnessing a physical violence of the friend against the friend's wife, the hero had a dream in that he fought against and wrestled with his friend to protect the woman. Using other materials in the story the author interpreted this dream as the fulfillment of the unconscious erotic wishes of the hero directed to the wife of his friend. Expanding this interpretation further to the creative process of the writer the author concluded that the fulfillment of the unconscious incestuous wishes toward his widowed mother who had seduced and deserted him during his latency period was the nuclear creative motivation of this fiction. "A Rainy Day" is a story about a young unmarried crippled woman, who was deserted without any mean in an half-ruined cottage totally exposed to the heavy rains in summer monsoon season during the Korean War by her elder brother. It was found that the creative motivation originated from the writer's suffering from persistent enuresis in childhood ; the cottage represented the enuretic body, and the young woman the writer as a child. "Being Realistic" is a story in that a passive poor young man loses his lover to an aggressive, able and greedy middle-aged man, and an orphan girl in anaclitic depression whose widowed mother stays in North Korea across th front dies of pulmonary tuberculosis. The author concluded that the writer's previous affective state and longing for the mother in childhood after his widowed-mother deserted him by elopement seemed to be the base of the creative impulse of this story.

관동맥질환에서 저밀도 지단백 입자 크기의 분포

임효영,김인숙,승기배,강동헌,전두수,장기육,박준철,이수영,홍순조,최규보 대한순환기학회 1998 Korean Circulation Journal Vol.28 No.8

열형광 CaSO₄:Dy 소자의 최적 제조조건에 관한 연구

김장렬,남영미,장시영,김두영,양정선,박재우 제주대학교 산업기술연구소 2000 尖端技術硏究所論文集 Vol.11 No.1

An experimental investigation has been performed to determine optimal conditions for preparing the thermoluminescent CaSO4:Dy pellets which have been widely used as personal radiation dosimeter material. Our investigation has shown that an optimal weight concentration of the dopant Dy in the bulk CaSO4:Dy is 0.1 mol%, and an optimal temperature of adding Dy in the preparing process is 320 ℃. An optimal time and temperature for sintering the CaSO4:Dy crystal produced from the chemical process are found to be 2 hours and 800 ℃, respectively. The maximum thermoluminescent sensitivity was observed when the CaSO4:Dy crystal was pulverized to grain sizes of 63 - 200 ㎛ in diameter before being fabricated into pellets. The commercial Teflon was selected as an adhesive for the fabrication of the CaSO4:Dy pellets with an optimal mixing ratio of the Teflon and CaSO4:Dy being 70 to 30 in weight.

점액성췌장 낭종 1예

황석주,김영운,오성광,김대영,임선재,박승욱,이두용,이헌영 충남대학교 의과대학 지역사회의학연구소 1995 충남의대잡지 Vol.22 No.2

Pancreatic cystadenoma is very rare, slow growing tumor and generally preoperative differential diagnosis may be difficult. A 43-year-old female was admitted to our hospital with the complaint of abdominal discomfort in the epigastrium for about preceeding 5 years. Ultrasonography and Computed tomography were performed. When endoscopic retrograde cholangio-pancreatogram was performed, displacement of distal pancreatic duct by huge mass was noted and injected dye was drained irregulary into the cavity of mass. Distal pancreatectomy was performed with splenectomy. The mass size of distal pancreas was 7X4cm, and the cyst contained with yellowish thick mucoid fluid. Diagnosis was confirmed the mutinous cystadenoma of the pancreas on histologic examination.