• Proceedings of the Korean Nuclear Society Conference
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• 2005.05a
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• pp.821-822
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• 2005

• KIEAE Journal
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• v.15 no.1
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• pp.139-146
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• 2015

This is an experimental study on the engineering characteristics of perforated reinforced concrete beams with shells. In the material matter of this study, the water cement ratio put 60%, the ratio of substitution of oyster shells to fine aggregate 30%. And in the structural matter, the form of opening put circle and square, the size of opening as the radius and the length of it changed from one to three times of the beam depth with a change presence and absence of reinforced steel around opening. All thirteen reinforced concrete beam tests composed one standard beam and twelve six beams with the circle and square opening were tested in shear strength under two points loading and compared and analyzed the characteristics of test beams under the same conditions one another. The results of the study showed as followed. 1) The initial crack load value of the opening test beams is similar the standard beam but the maximum load value decreased with increase in proportion of the opening size, in the square opening than the circle opening and in the absence than the presence of reinforced steel. 2) As the difference between the circle opening and the square opening beams is represented 2.17~9.8% in the maximum load value and the load capacity of the square opening suddenly decrease than it of the circle opening, it is judged because of the shortage of concrete section, the concentration of the stress in the corner of the square opening and material influence of shell substitution. 3) The failure figure such as the pattern of the crack and so on is represented brittle failure as the opening size is the bigger and the ratio of substitution is higher because of the lack material properties.

• Journal of Hydrogen and New Energy
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• v.35 no.4
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• pp.363-369
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• 2024

Needle valves are instrumentation devices with quick-opening inherent flow characteristics, used in pipelines requiring rapid flow supply immediately upon opening the flow path. For needle valves applied in liquefied hydrogen plants operating in cryogenic environments, it is necessary from the initial design stage to have various inherent flow characteristics in addition to quick-opening, depending on the intended usage. In this study, the inherent flow characteristics of a 1/2'' liquid hydrogen needle valve were evaluated through computational fluid dynamics analysis. Disk shapes exhibiting various inherent flow characteristics were proposed by deriving the flow coefficient (Cv) according to changes in disk shapes. Among the disk shapes that directly affect the Cv, the disk length and slope angle were selected, and case studies were conducted with nine parameter combinations. From the results of the normalized Cv regarding to opening rates, disk lengths and slope angles exhibiting quick-opening, equal-percentage, and linear inherent flow characteristics were determined.

• Proceedings of the KSME Conference
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• 2000.11a
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• pp.688-692
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• 2000

This study proposed design parameters of opening spring of circuit breaker that cut off the over-current in order to protect the electric device about opening speed using the energy method. We simulated the opening kinetic energy, the potential energy of opening spring and the design parameters of opening spring with respect to opening speed of VCB (Vacuum Circuit Breaker)'s moving contactor which has 24kV 25kA break capacity. From the result of simulation the initial tensional force and the final tensional force of the opening spring chose 107kgf and 282kgf respectively. Through the dynamic analysis using ADAMS, We verified that the opening speed of moving contactor satisfied break capacity of VCB and analyzed opening dynamic characteristics of VCB such as the opening displacement, the opening velocity and the opening acceleration of moving contactor in time domain.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.10
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• pp.801-807
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• 2020

Opening characteristics of a main oxidizer shut-off valve at different valve inlet pressures have been experimentally investigated. The pilot pressure at the moment of the valve opening increases linearly with increasing the valve inlet pressure and the increased pilot pressure reduces the valve travel time. As the pilot pressure increases at the moment of valve opening, the time to start opening the valve is delayed resulting in increasing the valve opening time. With the increment of the valve inlet pressure, the valve opening time is mainly determined by the time required for the pilot pressure to start opening the valve. Therefore the design of a pilot gas supply system can readily control the valve inlet pressure at the valve opening as well as the amount of oxidizer supplied to a combustion chamber during the engine startup.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.2
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• pp.121-127
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• 2008

This paper investigates the effects of outdoor pressure fluctuations on natural ventilation through an opening on a building envelope. The ventilation airflow rate depends on the magnitude and the period of the pressure fluctuations, the size of the opening relative to the space volume, and the resistance characteristics of the opening. Non-dimensional parameters have been derived, which determine indoor pressure responses due to outdoor pressure fluctuations. The flow regions are categorized into (1) synchronized region, (2) opening resistance region, and (3) transition region depending on the non-dimensional parameter derived. Pressure fluctuations and flow characteristics are investigated numerically using the 4th order Runge-Kutta method.

• Journal of the Korea Fashion and Costume Design Association
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• v.17 no.1
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• pp.93-104
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• 2015

As interest grows in nursing-wear in accordance with dissemination of breast-feeding, a study on opening of nursing-wear is needed to enhance convenience of breast-feeding regardless of location. In this study, the items on nursing-wear were classified and each characteristic was analyzed. The types and characteristics of opening on nursing-wear were identified and the characteristics of nursing brassier closely related to the nursing-wear were also identified. Top 5 companies for the nursing-wear and nursing-brassier were selected by ranking top 5 in NAVER with the search word 'nursing-wear' and 'nursing-brassier'. 732 one-piece and top (t-shirt and blouse) which have the highest portion in the nursing-wear were selected as the subject. Based on the photo, product explanation on the internet and in-depth interview of designer, the types and characteristics of openings for each item were identified. 732 nursing-brassier were selected to study the types and openings in breast-feeding. The result is as follows. Firstly, the item of nursing-wear can be classified into top, one-piece, package of top and the bottom, and sleeveless. Top and one-piece have the highest production rate. Secondly, the types of the openings are either covering or opening types. There are vertical-slit and horizontal-slit in covering type, and vertical-zipper, horizontal-zipper, and button types in opening type, and overlap and pocket type for the rest. Thirdly, the commercially available nursing-brassier according to the opening manner can be classified into upper-opening, middle-opening, and overlap types. Most largely produced product is upper-opening type as it minimizes the exposure of the breast in breast-feeding. When producing the nursing-brassier, the measurement of the lower breast and cup size are considered.

• Nuclear Engineering and Technology
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• v.54 no.5
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• pp.1674-1685
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• 2022

The ball valve is an important device in the pipeline transportation system of nuclear power plants. Its operational stability and safety directly affect the normal working of nuclear power plants. In this study, the transient numerical simulation of the opening and closing process of a ball valve was conducted on the basis of the flow interruption capability experiment of the ball valve by using the moving mesh method and inlet and outlet variable boundary conditions. The flow rate and pressure difference with time of the opening and closing process of the ball valve were studied. The internal flow characteristics of the ball valve under different relative openings were analyzed in conjunction with the typical back-step flow structure. Results show that the transient numerical results agree well with the experimental results. The internal flow characteristics of the ball valve are similar at the same opening during opening and closing process. At small opening, the spool and outlet channels easily form a back-step flow structure. The disappearance and generation of backflow vortices during opening and closing occur at 85% opening and 75% opening, respectively. With the decrease in opening degree, the difference in vortex core area in the flow channel of the ball valve spool in the opening and closing process gradually appears. The research results provide some reference value for the design and optimization of ball valves.

• Phonetics and Speech Sciences
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• v.3 no.3
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• pp.141-148
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• 2011

There are many factors that affect speech intelligibility and speech acceptability. Structural anomalies and neuromotor pathologies are known for the reasons of abnormal speech sounds. And there are minor variations related to oral mechanism. Speaking with restricted mouth opening related to therapeutic procedure or habitual speech pattern might affect the quality of speech sounds. So this study compared speech intelligibility and speech acceptability of recorded 24 words in two conditions (restricted mouth opening condition and normal mouth opening condition) by 30 normal hearing adults. The results showed that speech intelligibility and speech acceptability were significantly lower in restricted mouth opening condition. And speech acceptability was significantly lower than speech intelligibility in restricted mouth opening condition. Speech acceptability in restricted mouth opening condition was significantly lower especially in open vowel. These findings indicated that the mouth opening condition could affect vowel shape and could be an adverse effect on speech intelligibility and speech acceptability.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.859-864
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• 2001

In a vacuum circuit breaker mechanism, a spring-actuated linkage system is used to satisfy the desired opening and closing characteristics of electric contacts. Because the opening and the closing dynamics of electric contacts is determined by such a linkage system, the stiffness, free length and attachment points of a spring become the important design parameters. In this paper, based on the dynamic model of the circuit breaker using a multibody dynamic program ADAMS, a optimal design procedure of determining the spring design parameters is presented. The proposed procedure is applied to the design of an opening spring for satisfying the specified opening characteristics.