• 설비공학논문집
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• 제14권4호
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• pp.269-277
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• 2002

Dynamic characteristics of water hammer arresters installed in a building water supply system have been investigated numerically by utilizing a commercial rode that employs the method of characteristics. Some preliminary results with those arresters produced in this study agree well with the previously reported. Then, the arresters have been incorporated into a water supply pipe system of a $59m^2$ apartment unit constructed by a leading construction company, and their dynamic characteristics, especially on the reduction in the water hammer pressure, are investigated. It is found that the setting of the arresters in the pipe system, which is recommended by the company, may not be proper for reducing the pressure to less than 1082.0 kPa when buick-closure valves in the pipe system are closed within 30 ms at the static pressure of 542.6 kPa. More arresters in the system may be required to meet a pressure criteria.

• Journal of Korean Vacuum Science & Technology
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• 제6권3호
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• pp.109-115
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• 2002

This paper describes a CCM key comparison of low absolute-pressure standards at seven National Measurement Institutes that was carried out during the period March 1998 to September 1999 in order to determine their degrees of equivalence at pressures in the range 1 Pa to 1000 Pa. The Korea Research Institutes of Standards and Science(KRISS) participated from 10 Pa to 1000 Pa pressure range in 1999. The primary standards, which represent two principal measurement methods, included five liquid-column manometers and four static expansion systems. The transfer standard package consisted of four high-precision pressure transducers, two capacitance diaphragm gauges to provide high resolution at low pressures, and two resonant silicon gauges to provide the required calibration stability.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2001년도 유체기계 연구개발 발표회 논문집
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• pp.149-155
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• 2001

Recently, it is required to design higher stage pressure ratio compressor while maintaining equal adiabatic efficiency. To increase the stage pressure ratio, blade rotational speed or diffusion factor should be increased. In the case of increasing rotational speed, relative speed of flow at blade leading edge is well supersonic. In supersonic blade, total pressure loss is mainly due to shock wave and blade leading edge thickness should be very thin to minimize the shock wave loss. As a result, the blade is like to be week in terms of mechanical strength and the manufacturing cost is very high because NC machining is necessary. It is also one of big hurdle to overcome to make small compressor. In this paper, the effects of blade leading edge to the performance of supersonic blade In terms of total pressure loss. The efficiency of already known method to make thin blade leading edge from the casted blade with rather thick leading edge thickness is also assessed.

• Journal of Advanced Marine Engineering and Technology
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• 제27권2호
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• pp.299-304
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• 2003

Static mixer consists of a straight pipe of circular cross section into which individual elements are inserted to cut, fold, twist and re-combine the mixing fluid. The number of elements and their shape required in any application depend on the complexity of the mixing process. The objectives of this study are to develop a new static mixer and to perform the experimental investigation of pressure drop in order to evaluate the performance of the new one. The mixing fluid used is Glycerin. The pressure drop is measured using a hydraulic manometer and the correlation of Z-factor is suggested as a function of Re. The Z-factors of SSC and YNU mixer are about 40% lower than and 4% higher than that of the Sulzer one.

• 한국생산제조학회지
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• 제22권2호
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• pp.241-247
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• 2013

The doctor blade is equipped in a toner cartridge and is a device to maintain the uniform thickness of a toner by controlling the pressure on the developing roller. The contact pressure between the developing roller and the doctor blade is one of the significant factors for image quality and durability of toner cartridge. The purpose of this study is to develop approximation model in order to minimize the time and cost which are needed much required in making optimal design of the doctor blade. Central composite design was used for the design of experiment and response surface design was used for approximation. The data for contact pressure were acquired through finite element analysis and data of image density and toner weight were acquired through experiment. The approximation model developed in this study has presented very high fitness.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.617-620
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• 1997

In this paper, the thermal stress analysis of spent nuclear fuel disposal canister in a deep repository at 500m underground is done for the underground pressure variation. Since the nuclear fuel disposal usually emits much heat and radiation, its careful treatment is required. And so a long term safe repository at a deep bedrock is used. Under this situation, the canister experiences some mechanical external loads such as hydrostatic pressure of underground water, swelling pressure of bentonite buffer, and the thermal load due to the heat generation of spent nuclear fuel in the basket etc.. Hence, the canister should be designed to designed to withstand these loads. In this paper, the thermal stress analysis is done using the finite element analysis code, NISA.

• 설비공학논문집
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• 제4권2호
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• pp.116-122
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• 1992

The purpose of this paper is to determine the cut off flowrate regions of the overflow valve in using L.P gas vassels. The experimental methods were employed to measure the cut off flowrate in the state of constant pressure by using the $N_2$ gas. 1) To determine the optimum cut off flowrate regions, Hose length are required 0.5 meters. 2) Cut off fowrate regions about the each pressure can be suggested as follows. A) Cut off flowrate rigions are $2.0-4.0m^3/hr$ at the pressure of the $1Kg_f/cm^2$. B) Cut off flowrate rigions are$7.0-10.0m^3/hr$ at the pressure of the $10Kg_f/cm^2$.

• 한국의류학회지
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• 제39권4호
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• pp.586-600
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• 2015

This study investigates clothing pressure and subjective sensations in brassieres depending on breast type or bra type. The results of this study show that clothing pressure and subjective sensations were significantly influenced by breast type. The flat type breast and drooping type breast have a lower subjective satisfaction. Satisfaction for 3/4WL is the largest; however, 1/2W having low preventing breast shake and no-wire bra having low bust-up or low arrange-breast are required enhancements in bra function. The results are useful to provide basic data and produce high-quality brassieres depending on breast type.

• Tribology and Lubricants
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• 제29권4호
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• pp.228-234
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• 2013

This paper presents analysis of elastohydrodynamic lubrication (EHL) of ball bearings, in which surface roughness is considered. A lot of time is required to obtain a solution in the case of EHL analysis where surface roughness is considered, because the analysis requires a variety of analytic nodes. To save time, we use the full approximation scheme (FAS) among multilevel methods. We analyze the results of EHL and contact analyses in terms of pressure. We also compare the results for smooth and rough surfaces with respect to film thickness. We confirm that the film pressure decreases as compared to contact pressure because of the presence of lubricants between the ball and the raceway. Furthermore, in the case when surface roughness is considered, the film pressure increases because of contact asperities. Therefore, surface roughness should be considered when designing ball bearings.

• 대한기계학회논문집B
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• 제27권7호
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• pp.877-882
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• 2003

The main objective of the present study is to analyze the heat transfer characteristics in the vacuum carburizing furnace. Local temperatures are measured at different locations in the self-fabricated furnace for various operating conditions using K-type thermocouples. In addition, the present study simulates the fluid flows and heat transfer in the vacuum carburizing furnace using a commercial package (Fluent V. 6.0), and compares the predictions of local temperatures with experimental data. The temperature and flow fields are predicted. It is found that the time taken for reaching the steady-state temperature under the vacuum pressure is shorter than that under the normal pressure condition. It means that the carburizing furnace under vacuum pressure condition is capable of saving the required energy more efficiently than the furnace under the normal pressure condition. Furthermore, the temperature variations predicted by the numerical simulations are in good agreement with experimental data.