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STS316L 용접부의 피로거동 및 초음파시럼에 의한 열화특성 평가
남기우,박소순,안석환,도재윤,박인덕 한국비파괴검사학회 2003 한국비파괴검사학회지 Vol.23 No.2
STS316L은 인성, 연성, 부식저항성 등 우수한 기계적 성질 때문에 에너지환경설비 등 구조물에 널리 이용되고 있다. 그러나, 용접구조물은 가혹한 환경하에서 경년열화가 심각하다. 지금까지의 연구들은 주로 용접부의 피로균열진전거동에 관하여 수행되었고, 피로균열진전속도식의 재료상수와 비파괴적 평가의 상관성에 관한 연구는 거의 없었다. 본 연구는 STS316L 용접부의 피로균열진전 거동을 조사하고, 초음파 파라미터로 열화특성을 평가하고 시간-주파수 분석으로 해석을 하였다. 본 연구 결과는 용접구조물의 사용기간 중 피로수명 등을 예측하기 위한 기초 데이터로서 사용될 수 있다. STS316L had been used as the structural material for energy environmental facilities, because austenite stainless steels like 316L have superior mechanical properties of which toughness, ductility, corrosion resistant and etc. However, those welded structures are receiving severe damage due to increasing of the aged degradation. Most studies until now have been carried out against fatigue bahaviors of weldments, and were not well studied on nondestructive evaluation methods. In this study, the fatigue crack propagation behavior of STS316L weldment usually used for vessels of the nuclear power plant was investigated. Also, the degradation characterstics of 316L stainless steel weldments were evaluated by the ultrasonic parameter such as ultrasonic velocity, attenuation factor and time-frequency analysis. The results of this study can be used as a basic data for the prediction of the fatigue crack life of weldments structures without disjointing or stopping service of structures in service.
대학생 축구선수의 등속성 체간근력과 대퇴근력 및 거퇴근력과의 관련성
박기용,홍석민,최경훈,추근도 한국스포츠리서치 2003 한국 스포츠 리서치 Vol.14 No.6
The purpose of this study was to investigate the relationships among trunk muscle, knee, and ankle strengths using Cybex770, the isokinetic muscle functioning measurement device. 41 K and Y University soccer players who did not have any experience about back pain or spine surgery were recruited as subjects. The results of the study were as follows. 1. Trunk extension was significantly higher than trunk flexion and muscle strength was diminished with increasing load speed. 2. Trunk flexion/extension ratio was well balanced at 30。/sec but this balance was broken with increasing load speed. 3. At 60。/sec of load speed, the knee extension and flexion of the left side were higher than those of the right side. 4. At 60。/sec of load speed, the ipsilateral muscle strengths of the left knee were well balanced but those of the right side were imbalanced. 5. At 60。/sec of load spped, the ratio of bilateral muscle strength of knee was -18.5±32.3% and this implies the possibility of knee injury. 6. Plantalflexion and dorsiflexion of the right ankle were higher than those of the left side, and dorsiflexion/plantalflexion ratio of the left side was higher than that of the right side. 7. The ratio of bilateral muscle strength of ankle at 60。/sec of load speed represented a balanced muscle development but this balance was broken with increasing load speed.8. There were partially significant relationships between trunk muscle and knee strengths. and between knee and ankle strengths. In conclusion, the trunk muscle strength of soccer player might be a very important factor to improve performance. In addition. a training technique which considering strength and speed is needed to develop not static but dynamic strength. This training not only develops well balanced muscle strength but also protects sport injury. Thus, the isokinetic training of trunk could improve the trunk muscle strength. and increase the ability of flexion/extension of knee and ankle.
윤기도,권동진,홍석산,김수일,정건섭 한국미생물생명공학회 ( 구 한국산업미생물학회 ) 1996 한국미생물·생명공학회지 Vol.24 No.4
To investigate the inhibitory effect of soybean and Korean traditional fermented soybean products on the chemically induced mutagenesis, we extracted soybean, Kanjang, Doenjang, Kochujang, and Chonkukjang with water, methanol and hexane. Inhibitory effect of extracts was assayed by the SOS chromotest using Escherichia coli PQ37 as a test strain. 4-nitroquinoline-1-oxide(4NQO), N-methyl-N'-nitro-N-nitrosoguanidine(MNNG), and aflatoxin B_1(AFB_1) were used as mutagens. Methanol extracts showed relatively higher inhibitory effect than water and hexane extracts. Methanol extracts of soybea, Doenjang, Kochujang, and Chongkukjang showed inhibitory effect of 68.4, 96.3, 17.5, and 100.9%, against MNNG, and 28.6, 109.1, 41.3, and 101.8% against AFB_1., respectively. Doenjang methanol extract showed inhibitory effect of 51.0, 96.3, and 109.1% against 4NQO, MNNG, and AFB_1. Inhibitory effect of heat-treated Doenjang and Chongkukjang methanol extracts on the mutagenicity of MNNG and AFB_1 was remained over 95% of the inhibitory effect of heat-untreated extracts, demonstrating the heat stability of the potent antimutagenic activity.
권경주,정성애,심기남,정정화,강석형,송도경,전승정,김혜인 이화여자대학교 의과학연구소 2012 EMJ (Ewha medical journal) Vol.35 No.1
Until recently, colorectal polyps were classified predominantly as hyperplastic or adenomatous. While adenomatous polyps are well-characterized precursor lesions of adenocarcinomas, hyperplastic polyps have been considered as benign lesion. However, some hyperplastic polyps with serrated morphology of the crypts have been recognized to have distinctive features and these polyps were termed ‘serrated adenomas’. Recent data show that sessile serrated adenomas (SSA) might be the precursors of serrated colonic cancers, underlining the necessity of identifying them. SSA is approximately 3% of all polyps, commonly appears as flat or sessile and yellowish due to mucus production. In the pathogenesis of SSA, progression to high grade dysplasia or early invasive carcinoma may be associated with serrated neoplasia pathway different from adenoma-carcinoma sequence. We report a case with a colon polyp diagnosed as sessile serrated adenoma with high grade dysplasia after endoscopic submucosal dissection.
A Forecast Model for the First Occurrence of Phytophthora Blight on Chili Pepper after Overwintering
Do, Ki-Seok,Kang, Wee-Soo,Park, Eun-Woo The Korean Society of Plant Pathology 2012 Plant Pathology Journal Vol.28 No.2
An infection risk model for Phytophthora blight on chili pepper was developed to estimate the first date of disease occurrence in the field. The model consisted of three parts including estimation of zoosporangium formation, soil water content, and amount of active inoculum in soil. Daily weather data on air temperature, relative humidity and rainfall, and the soil texture data of local areas were used to estimate infection risk level that was quantified as the accumulated amount of active inoculum during the prior three days. Based on the analysis on 190 sets of weather and disease data, it was found that the threshold infection risk of 224 could be an appropriate criterion for determining the primary infection date. The 95% confidence interval for the difference between the estimated date of primary infection and the observed date of first disease occurrence was $8{\pm}3$ days. In the model validation tests, the observed dates of first disease occurrence were within the 95% confidence intervals of the estimated dates in the five out of six cases. The sensitivity analyses suggested that the model was more responsive to temperature and soil texture than relative humidity, rainfall, and transplanting date. The infection risk model could be implemented in practice to control Phytophthora blight in chili pepper fields.
Do, Ki Seok,Chung, Bong Nam,Joa, Jae Ho The Korean Society of Plant Pathology 2016 Plant Pathology Journal Vol.32 No.6
We developed a model, termed D-PSA-K, to estimate the accumulated potential damage on kiwifruit canes caused by bacterial canker during the growing and overwintering seasons. The model consisted of three parts including estimation of the amount of necrotic lesion in a non-frozen environment, the rate of necrosis increase in a freezing environment during the overwintering season, and the amount of necrotic lesion on kiwifruit canes caused by bacterial canker during the overwintering and growing seasons. We evaluated the model's accuracy by comparing the observed maximum disease incidence on kiwifruit canes against the damage estimated using weather and disease data collected at Wando during 1994-1997 and at Seogwipo during 2014-2015. For the Hayward cultivar, D-PSA-K estimated the accumulated damage as approximately nine times the observed maximum disease incidence. For the Hort16A cultivar, the accumulated damage estimated by D-PSA-K was high when the observed disease incidence was high. D-PSA-K could assist kiwifruit growers in selecting optimal sites for kiwifruit cultivation and establishing improved production plans by predicting the loss in kiwifruit production due to bacterial canker, using past weather or future climate change data.