• 한국안전학회지
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• 제5권3호
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• pp.8-26
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• 1990

It is important to have exact information about the contact pressure distribution in the design of connected parts of machines and structures. In previous works, stress analyses on a two body contact problem have been carried out in large numbers. Besides, the measurement of contact stress is important to confirm the adequateness of the theoretical analysis, to verify appropriateness of Hertzian contact theory and to know the practical pressure distribution, but an excellent measuring method con't be found at present. Therefore, a quantitative measurement of contact pressure by means of ultrasonic waves using a normal probe and an angle has been proposed to measure the contact pressure distribution between two rough flat surfaces. At first, in a new proposed calibration method, the relation between mean contact pressure and sound pressure of reflected waves is obtained by using calibration blocks with various surface roughnesses made of the same material as the rectangular section beams And then, this experimental results are compared with the analytical ones, and the utility of this method is discussed.

• Nutrition Research and Practice
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• 제1권4호
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• pp.335-340
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• 2007

The purpose of the present study was to examine the relation of total antioxidant status (TAS) to metabolic risk factors in Korean adults. Anthropometric measures, blood pressure, serum lipids and fasting glucose were determined in 406 men and women. TAS was measured by using commercially available Randox kit. Serum TAS was significantly positively correlated with body weight (p=0.004), body mass index (BMI) (p=0.033), waist circumference (p=0.017), total cholesterol (p=0.038) and triglyceride (TG) (p<0.001). The mean TAS of hypertriglyceridemic subjects (TG ${\geq}$150 mg/dl) was significantly higher than that of subjects whose TG was lower than 150 mg/dl (p=0.001). When central obesity, TG, high density lipoprotein cholesterol, fasting glucose and blood pressure were considered as metabolic risk factors, TAS was shown to be elevated with increased number of metabolic risk factors (p=0.004). The positive association between TAS and a number of metabolic risk factors suggests that increased TAS may not always indicate one's healthier condition. In order to help understand TAS as a marker of total antioxidant capacity in humans with various metabolic conditions, it is needed to clarify the factors affecting TAS in relation to changes in metabolic risk factors.

• 터널과지하공간
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• 제34권1호
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• pp.71-87
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• 2024

고준위방사성폐기물 심층처분 시, 처분공 주변의 근계암반은 높은 지중응력과 재포화된 벤토나이트 완충재의 팽윤압, 방사성 원소 붕괴열의 영향을 받아 국부적으로 투수계수가 변화될 수 있다. 본 연구에서는 국내 유력한 처분 대상 부지 암종 중의 하나인 결정질 경암으로서의 화강암을 대상으로, 실제 처분 환경에서 예상되는 다양한 구속압과 온도 조건을 적용하여 투수계수 변화 특성을 실험적인 방법을 통하여 고찰하고자 하였다. KURT 화강암 시험편 하나당 3개 이상의 정수압 조건에서 투수시험을 수행하여 구속압이 증가함에 따라 투수계수가 지수적으로 감소하는 관계를 도출하였다. 예상 최대 온도로 설정한 90℃ 이하 수준에서는 온도에 의한 투수계수 변화가 무시 가능할 정도로 작음을 확인하였다. 추가로 초기투수계수가 초기공극률의 거듭제곱에 비례하는 상관관계를 도출함으로써, 특정 공극률을 지닌 화강암이 일정 구속압 하에 있을 때 가지는 투수계수 값을 유추할 수 있었다.

• 한국생산제조학회지
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• 제22권5호
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• pp.767-773
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• 2013

A high-pressure, high-pressure drop control valve, which transforms the power transfer of a system by reducing the inlet pressure of 345bartothe outlet pressure of 112bar, is a fundamental component in an offshore plant process. With the increasingly growing market share of the maritime industry, this valve has been expected to be a high-value-added product. This study not only analyzes the relation between pressure drop and fluid velocity in a trim by using fluid analysis, but also examines the possibility of cavitation in a valve in addition to the plot for the extension of lifespan. Based on the analysis results, the design and production method of the valve are established, and accordingly, performance evaluation is carried out. It is demonstrated that the pressure drop from 345bar to 112bar is more feasible in the presence of the trim, which can induce a continuous and diminutive pressure drop in order to prevent cavitation in a high-pressure drop control valve. Furthermore, despite the fluid velocity near a seatring being found to be over 30m/s, the lifespan of the valve is determined to be adequate considering the operation condition of a prototype valve of 80%.

• 소성∙가공
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• 제4권1호
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• pp.17-27
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• 1995

The tact switch is widely used in electric and electronic products. The dome type tact spring is produced by stamping. Stamping of the tact spring and operation of the tact switch have been simulated by the elasto-plastic finite element method. The operating characteristics of the switch may be given by the relation between the operating force and stroke. For a given material, this is affected by two main factors. One is the geometry of dome spring which is determined by the geometry of stamping dies and the stamping pressure, and another one is the dimension of switch. From the calculation, it was possible to obtain the stamping conditions and switch dimension for a predetermined force-stroki relation And, the hoop stresses and effective strains distributions due to the stamping and during the operation of the switch indicate a possibility of cracking in the center and rim of dome spring.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 춘계학술대회 논문집 기술교육전문연구회
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• pp.96-102
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• 2003

Today, stage technology is developing highly by application of digital computer. Performance is composed of audio/video and acoustic technology takes very important position in field of stage technology. Generally speaking, four factors of sound are loudness, pitch, sound timbre and duration. Loudness depends on sound pressure level, yet partly related with spectrum and dulation. Pitch depends mainly on frequence and have a relation with sound pressure and duration. sound timbre depends strongly on spectrum and have a relation with frequence. In this paper, I designed a multi-microphone system which can used in broadcasting and performance stage with vicboss 200MHz-VHF wireless microphone and vicboss 900MHz-VHF wireless microphone. I also studied about multi-microphone which can use conveniently in the super play that needs many microphones. If this multi-microphone is prodused, we could expect better sound quality and a big progress in stereo recording technology.

• 대한예방한의학회지
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• 제17권3호
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• pp.91-102
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• 2013

Objective : This study aimed to evaluate the relation ship between depression and anxiety, self esteem, BMI, blood types, blood pressure, scoliosis of spine. Method : We analyzed the results Health examination of 5619 university students (included BDI, BAI, SES, BMI, Blood Types, Blood Pressure, X-ray of whole spine). All the data were analyzed statistically by descriptive statistics, t-test, ANOVA and regression analysis. Result : Female's BMI score and BAI score are higher than Male's. And Senior Group showed higher score than Freshman Group. There were positive correlation between BAI, and BDI. but negative correlation between SES, Blood Pressure and BDI. BMI, Blood types and Scoliosis of spine were not related to depression. Conclusion : There were correlation between BAI, SES, Blood Pressure and BDI. It is necessary to study about depression with many other effective factors of various psychological and physical subjects.

• 산업기술연구
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• 제25권B호
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• pp.89-97
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• 2005

Application of proper orthogonal decomposition (POD) and continuous wavelet transform (CWT) is introduced to study wind speed and building roof pressures of flow separation region. In this study, a detailed analysis of the approach wind flow, wind-induced building pressure and the relation between the two fields was carried out using the POD technique and CWT analysis. The results show potential of the application of POD and CWT in characterization of spatio-temporal and spectral properties of the approach wind and its induced dynamic pressure events. Some of findings resulting from the application of this analysis can be summarized as follows: (1) The POD first principal coordinate of the roof pressure in the separated shear layer is closely correlated with the longitudinal component of oncoming flow. (2) The CWT analysis suggests that the extreme peak pressure in the separated shear layer is due to condensed large-scale eddy motions.

• 한국자동차공학회논문집
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• 제11권5호
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• pp.77-82
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• 2003

A parametric study was conducted on pressure drop in a catalytic converter for automobile. In this work, we proposed a new pressure drop relation which contains the various parameters needed to calculate and got a few results. In a monolith of catalyst, the flow originally turbulent flow changes to laminar flow and thus the pressure drop through the monolith is linearly proportional to the velocity. The exhaust pressure is doubly affected by the increase of mean velocity and length when we decrease the diameter of monolith while the volume keeps constant. Theoretical parameters such as $\alpha$ and $\beta$ are suggested to use as a reference value when there is no a experimental data. Especially in the part load test, these values should be modified to consider the property change of exhaust gas.

• 가정과삶의질연구
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• 제8권1호
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• pp.129-142
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• 1990

The purpose of this study were to investigate : 1) Differences of perceived time pressure according to the employment status of housewife. 2) The differences of housework strategy according to the employment status of housewife. 3) The relation between perceived time pressure and housework performance strategy. The subject of this study were 375 women living in Seoul, the age of youngest child is at least school age. They were composed of non employed housewives, employed professional housewives and employed non professional housewives. Survery methods were questionare and interview. Data analysis strategy were percentile, frequency, one-way ANOVA, scheffe test and MCA. The major findings were : 1) Perceived time pressure and two sub areas, psychological time pressure and time pressure according to the part of housework were significantly different according to the employment status of housewife. The independent influence of employment status of housewives was most po erful in regression analysis. 2) Housework performance strategy was different according to the employment status of housewife. The strategies were divisions of housework amon family members, use of convenience goods, services, appliance, paid help, adjustment of housework performance standard, reduction of leisure and sleep time.