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.

유아의 자연물에 대한 연상, 유사성, 생명 개념에 관한 연구

최진승,김지영 동아대학교 교육대학원 1998 동아교육논총 Vol.24 No.-

본 연구는 유아가 자연물에 대한 지식을 연상하고 생명 유무와 유사성을 판단하는 기준을 공통적인 준거로써 찾고 그 준거별 반응정도가 연령 및 성별, 자연물의 범주에 따라서 어떠한 양상을 보이면서 발달하는지 밝히는데 그 목적을 두었다. 본 연구의 대상은 부산 시내 유치원에 재원하는 3, 4, 5세 유아 90명이며 유아에게 제시된 자연물은 예비 조사와 친숙도 검사를 통해 선정하였으며, 범주에 따라서 동물, 식물, 천체, 기타 무생물 범주로 나뉘며 각 범주별로 3개씩 총 12개이다. 자료는 인터뷰식으로 진행하여 수집되었으며 유아의 반응은 모두 녹음하여 준거에 따라 수량화하였고, 통계처리는 일원변량분석, 다변량분석, t-검증, Duncan(.05)사후 검증 등을 활용하였다. 본 연구의 결과 및 논의를 통해 얻어진 결론은 다음과 같다. 첫째, 자연물의 소유, 형태, 주제에 관한 개념은 3세에 이미 발달되어 있으며, 색깔과 기능에 관한 개념은 4세와 5세 사이에 크게 발달하는 것으로 보인다. 둘째, 여아는 남아보다 자연물의 기능 및 행위에 관한 개념을 더 먼저 획득한다. 셋째, 동물 및 기타 무생물 범주에 관한 자연물의 개념은 식물 범주 및 천체 범주에 대한 개념보다 더 먼저 발달한다. 넷째, 유아의 자연물의 유사성 판단은 주제-지각-기능-개념 이행으로 변화하며 발달한다. 여섯째, 유아들이 자연물과 유사한 대상으 판단할 때 근거하는 기준은 자연물의 범주에 따라 다른데, 생물 범주는 기능적인 법칙에 근거하고 무생물 범주는 지각적인 특징에 근거하여 판단한다. 일곱째, 자연 법칙에 근거하여 자연물의 생명성을 판단할 수 있는 능력은 5세에 갖추어어지며, 자연물의 범주에 따라 생명성의 판단의 기준이 다르다. 동물 범주는 자연법칙에 근거하며 식물 범주는 사람들의 활동과 개입 유무에 근거하고, 무생물 범주는 의인적인 준거에 근거하여 판단하는 경향이 높다. The purpose of this study is that how the young childrens' association, simialrity, life concept on natural kinds changes with age, sex, and the categories of natural kinds. The subjects in this study were 90 young children who were 3, 4, and 5 years old, and sampled from 3 kindergartens in Pusna. Natural kinds were selected through the pilot test and the categories of natural kinds were divided into animal, plant, planet, and dnonbiological category. Following conclusions were derived from discussion on the results to this study: 1.Young children's association about natural kinds' having, shape, thematic knowledge don't change with age, and their association for the color, functional knowledge of natual kinds were increaed with age. 2.Female childrens' association is higer than male in the natural kinds' functional knowledge. 3.Young childrengs association about plant, planet is increasing with age. Therefore, young childrens' concept about animal, nonbiological kinds is formed nearly at 3 age olds, and young childrens' concept about plant, planet develops highly between the age of 4 and 5 years old. 4.Young children's association about natural kinds' shape is high in the all categories of natural kinds, their assocaition about natural kinds' thematic knowledge is high in nonbiological category. In addition, their association about natural kinds' function is high in animal category at most. 5.Young childrens' reponses about natural kinds' thematic simiarity are decreasing with age. On the other hand, their responses about natural kinds' perceptual, functional simiarity are increasing with age. The result suggests that young childrens' concept on natural kinds is developing thematic-perceptural-founctional-conceptual shift. 6.Young childrens' assocaition about the simiarity is based on objects' founctional character in biological category. On the other hand, their assocaition about inanimates' similarity is based on the perceptual character in nonbiological category. 7.Young childrens' ability to discriminate the animates-nonanimates is increasing at 5 years old. Therefore, young childrens' life concept is formed nearly at 5 years old. 8.Young childrens discriminate between animate and inanimate things in animal category at the based of animals' functional character and in plant category at the based of persons' activity. However they justify the objects' lives at the based of perceptual character in nonbiological category.

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.

Localization of Antigenic Sites at the Amino-terminus of Rinderpest Virus N Protein Using Deleted N Mutants and Monoclonal Antibody

Kang-seuk Choi,Jin-ju Nah,Young-joon Ko,Shien-young Kang,Yi-seol Joo 대한수의학회 2003 Journal of Veterinary Science Vol.4 No.2

of Antigenic Sites at the Amino-terminus of Rinderpest Virus N Protein Using Deleted N Mutants and Monoclonal AntibodyKang-seuk Choi*, Jin-ju Nah, Young-joon Ko, Shien-young Kang1 and Yi-seok JooNational Veterinary Research and Quarantine service, Ministry of Agriculture and Forestry, 480 Anyang, Gyounggi 430-824, Korea1Research Institute of Veterinary Medicine, College of Veterinary Medicine, Chungbuk National University, 48 Gaeshin-dong, Heungduk-gu, Cheongju, Chungbuk 361-763, KoreaReceived April 2, 2003 / Accept July 10, 2003J. Vet. Sci. (2003), 4(2), 167-173JOURNAL OFVeterinaryScience*Corresponding author: Kang-seuk Choi National Veterinary Research and Quarantine service, Ministry of Agriculture and Forestry, 480 Anyang, Gyounggi 430-824, Korea Tel: +82-31-467-1860, Fax: +82-31-449-5882 E-mail: choiks@nvrqs.go.kr

Factors associated with the risk of colorectal neoplasia in young adults under age 40

Ilsoo Kim,Han Hee Lee,Young Jae Ko,Ho Eun Chang,Dae Young Cheung,Bo-In Lee,Young-Seok Cho,Jin Il Kim,Myung-Gyu Choi 대한내과학회 2022 The Korean Journal of Internal Medicine Vol.37 No.5

Background/Aims: Recent epidemiologic studies have shown a continued increase in colorectal cancer incidence among younger adults. Little is known about the factors that contribute to the development of young-onset colorectal neoplasia (CRN). Methods: A cross-sectional analysis was performed for individuals younger than 40 years who underwent colonoscopy in Seoul St. Mary’s Hospital and its affiliated health screening center. High-risk CRN was defined as adenoma or sessile serrated lesion ≥ 10 mm, with three or more adenomas, villous histology, high grade dysplasia, or carcinoma. Results: Of these 13,621 included participants, 2,023 (14.9%) had one and more CRN. Young patients with CRN tended to be elderly, male, obese, smoker, having a habit of drinking, and having comorbidities such as hypertension, dyslipidemia, diabetes, and chronic kidney disease. In a multivariate analysis adjusted for age, sex, obesity, smoking status, and alcohol intake, old age (odds ratio [OR], 1.086; 95% confidence interval [CI], 1.054 to 1.119), male sex (OR, 1.748; 95% CI, 1.247 to 2.451), obesity (OR, 1.439; 95% CI, 1.133 to 1.828), and smoking (OR, 1.654; 95% CI, 1.287 to 2.127) were independent risk factors for overall CRN. Obesity and smoking as two modifiable factors increased the risk for high-risk CRN even more than for overall CRN (OR, 1.734; 95% CI, 1.168 to 2.575 and OR, 1.797; 95% CI, 1.172 to 2.753, respectively). Conclusions: Obesity and smoking were modifiable risk factors for CRN in young adults. They increased the risk for highrisk CRN even more than for overall CRN. A colonoscopy might be beneficial for young individuals with these factors.

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.

Polyphosphate가 Porphyromonas endodontalis의 성장에 미치는 영향에 관한 연구

최성백,최호영,민병순,박상진,이진용,최기운 大韓齒科保存學會 1998 Restorative Dentistry & Endodontics Vol.23 No.1

Polyphosphate has been used to prevent decomposition of foods and has been shown to have inhibitory effect on the growth of gram positive bacteria. The purpose of this study was to evaluate the effect of polyphosphate on the growth of Porphyromonas endodontalis, a gram negative endodontopathic bacterium. Porphyromonas endodontalis ATCC 35406 was grown in the presence of polyphosphates with different chain lengths. Inhibitory effect of each polyphosphate which was added at the beginnig or during the culture, was determined by measuring the optical density of the bacterial cell at 540nm and by viable cell count. The results from this study were as follows : 1. Polyphosphates were shown the growth inhibition of the Porphyromonas endodontalis. 2. The minimal inhibitory concentration(MIC) of polyphosphate was observed to be 0.04%. 3. Polyphosphates with chain lengths of 25 and 75 demonstrated the greatest inhibitory effect on the growth of Porphyromonas endodontalis. 4. Polyphosphates are bactericidal to Porphyromonas endodontalis, demonstrating the growth inhibition of the bacterium. The overall results suggest that use of polyphosphate may affect the growth of Porphyromonas endodontalis. Further studies will be needed to confirm the effect of Polyphosphate.

영구형 항서맥 심박조율기 환자의 장기추적관찰

최현석,이무용,최영진,최성준,김효수,손대원,오병희,이명묵,박영배,최윤식,이영우,이명용 대한순환기학회 1998 Korean Circulation Journal Vol.28 No.5

[Book Review:] Yi Jin-sang’s “the Theory of Sim jeuk ri (Mind is the Principle),” in Complete Works of Hanju.

( Choi Young-jin ) 성균관대학교 유교문화연구소 2014 儒敎文化硏究(中文版) Vol.0 No.21

리니어 모터로 이송되는 탄성체의 진동 최소화를 위한 이송속도 최적화 연구

최영휴,홍대선,최응영,최국진 국립7개대학공동논문집간행위원회 2005 공업기술연구 Vol.5 No.-

Linear motor feed drive systems have been broadly used in machine tools or precision automatic systems. Recently, modern machine tools require high speed and high precision feed drive system to achieve high productivity. Unfortunately, a feed drive system, even though it was designed optimally, may experience severe transient vibrations during high-speed operation if its feed rate control is unsuitable. A rough feed rate curve having discontinuity in its acceleration profile causes serious vibrations in the feed slides system. This paper presents a feed rate optimization of a machine tool feed slide system, which is driven by a linear motor, for its minimum vibrations. Firstly, a 4-degree-of-freedom lumped parameter model is proposed for the vibration analysis of a linear motor driven machine tool feed drive system. Next, a feed rate optimization of the feed slide is carried out for minimum vibrations. The feed rate curve optimization strategy is to find out the most appropriate acceleration profile with jerk continuity. Of course, the optimized feed rate should approximate to the desired one as possible. A genetic algorithm with variable penalty function was used in this feed rate optimization.