• Title/Summary/Keyword: Experimental designs

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Experimental Study on Combustion Characteristics of Live Fire Load in a Bookstore (서점의 적재가연물의 연소특성에 관한 실험적 연구)

  • Nam, Dong-Gun
    • Fire Science and Engineering
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    • v.25 no.5
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    • pp.47-53
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    • 2011
  • Fire load in buildings greatly contribute to the time and scale of fire according to the type and quantity of the fire load. Because bookstores have a large quantity of fire load compared with other buildings which may lead to large scale fires, however, their heat release characteristics have been hardly investigated. In this study, to obtain the data applicable for the performance-based fire safety design of bookstores, the specimens representing stacked fire loads were heated in a furnace in compliance with the standard heating curve of ISO834-1:1999 to investigate their heat release characteristics. From the experiment result, the combustion velocity and heat release rate required for performancebased fire safety designs are obtained.

Mechanical properties of concrete containing recycled materials

  • Solanki, Pranshoo;Dash, Bharat
    • Advances in concrete construction
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    • v.4 no.3
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    • pp.207-220
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    • 2016
  • The objective of this study was to evaluate the influence of recycled materials, namely, shredded scrap tire (SST), reclaimed asphalt pavement (RAP) and class C fly ash (CFA) on compressive and tensile strength of concrete. Either SST or RAP was used as an aggregate replacement and class C fly ash (CFA) as Portland cement replacement for making concrete. A total of two types of SST and RAP, namely, chips and screenings were used for replacing coarse and fine aggregates, respectively. A total of 26 concrete mixes containing different replacement level of SST or RAP and CFA were designed. Using the mix designs, cylindrical specimens of concrete were prepared, cured in water tank, and tested for unconfined compressive strength (UCS) and indirect tensile strength (IDT) after 28 days. Experimental results showed aggregate substitution with SST decreased both UCS and IDT of concrete. On the contrary, replacement of aggregate with RAP improved UCS values. Specimens containing RAP chips resulted in concrete with higher IDT values as compared to corresponding specimens containing RAP screenings. Addition of 40% CFA was found to improve UCS values and degrade IDT values of SST containing specimens. Statistical analysis showed that IDT of SST and RAP can be estimated as approximately 13% and 12% of UCS, respectively.

Analysis of Research Trends about Spiritual Care in Korea (영적 간호에 관한 국내 연구동향 분석)

  • Yoo, Seung-Yeon
    • Korean Journal of Adult Nursing
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    • v.25 no.3
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    • pp.332-343
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    • 2013
  • Purpose: The purpose of this study was to analyze the research trends of spiritual care in Korea and to make suggestions for future studies. Methods: 209 researches from 1981 to 2012 were analyzed. Results: Among the 209 studies reviewed. 74 were thesis studies and 135 for reported research in academic journal. There were 169 quantitative studies, 11 qualitative studies and 29 other types studies. The most frequently used study design was correlational. The majority of study participants were patients, followed by nursing students, nurses or non-medical participants. In the correlation studies, the variable of spiritual well-being had a positive correlation with hope, self-esteem and spiritual nursing care and a negative correlation with depression, anxiety and loneliness. In the experimental studies, the independent variables were spiritual nursing intervention, spiritual care education program and spiritual promoting intervention. The main theme of qualitative studies were the experience of spiritual care, spiritual experience and the most frequent designs were grounded theory, phenomenology and interpretative phenomenology. Conclusion: The domestic research about spiritual care needs to utilize a variety of approaches including concept or tool development study suitable for Korean peoples, multi-disciplinary research, qualitative study and program development study.

Numerical study on Wells turbine with penetrating blade tip treatments for wave energy conversion

  • Cui, Ying;Hyun, Beom-Soo
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.8 no.5
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    • pp.456-465
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    • 2016
  • In order to optimize the performance of a Wells turbine with fixed guide vanes, the designs of an end plate and a ring on the tip of the turbine rotor are proposed as penetrating blade tip treatments. In this study, numerical investigations are made using computational fluid dynamics (CFD)-based ANSYS Fluent software, and validated by corresponding experimental data. The flow fields are analyzed and non-dimensional coefficients $C_A$, $C_T$ and ${\eta}$ are calculated under steady-state conditions. Numerical results show that the stalling phenomenon on a ring-type Wells turbine occurs at a flow coefficient of ${\phi}=0.36$, and its peak efficiency can reach 0.54, which is 16% higher than that of an unmodified turbine and 9% higher than in the case of an endplate-type turbine. In addition, quasi-steady analysis is used to calculate the mean efficiency and output work of a wave cycle under sinusoidal flow conditions. As a result, it has been found that the ring-type turbine is superior to other types of Wells turbines.

Prediction of Long Term Performance and Creep of Laminated Natural Rubber Bearings(NRB) (적층 천연고무 면진장치의 장기성능과 크리프에 대한 예측)

  • Hwang, Kee Tae;Seo, Dae Won;Cho, Sung Gook
    • Journal of the Earthquake Engineering Society of Korea
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    • v.17 no.3
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    • pp.117-125
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    • 2013
  • Seismic isolation has been considered and utilized in various industries as a way to prevent huge damage on to structures by large earthquakes in various industries. The laminated Laminated rubber bearings is are most frequently used in seismic isolation systems. The structural Structural safety could not be assured unless the performance of the rubber bearing is not guaranteed for the life time of the structure under the consideration that the bearing is a critical structural member to sustain vertical loads in the seismically isolated structure. However, there are few studies on the deterioration problems of rubber bearings during their service life. The long term performance of the rubber bearings was not considered in past designs of seismically isolated structures. This study evaluates the long term performance and creep characteristics of laminated natural rubber bearings that are used in seismically isolated buildings. For the this study, a set of accelerated thermal aging tests and creep tests are were performed on real specimens. The experimental results show that the natural rubber bearings would have a stable change rate of change for durability under severe environmental conditions for a long time.

Effects of Store Density and Perceived Price Benefit of Sale on Perceived Crowding (점포 밀도와 세일의 가격혜택이 혼잡성 지각에 미치는 영향)

  • Park, Kyungae;Heo, Soonim
    • Journal of the Korean Society of Clothing and Textiles
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    • v.39 no.4
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    • pp.613-624
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    • 2015
  • This study examined: 1) the effect of store density on perceived crowding 2) the difference of perceived price benefit of sale by store density 3) the effect of perceived price benefit and store density on perceived crowding and 4) the effect of perceived crowding and price benefit on shopping behaviors. Store density and perceived crowding were categorized into social and spatial dimensions. Data were collected with 6 (high, medium, and low social and spatial densities) * 2 (sale and no-sale) between-subjects experimental designs. A total of 395 responses were analyzed. The results revealed that social density affected social crowding, but spatial density had no effect on perceived crowding. Price benefit of sale was not different by store density. The sale itself did not affect perceived crowding. Under the social density situation, perceived price benefit reduced spatial crowding and social crowding showed a positive effect on purchase behavior while spatial crowding had a negative effect. However, the most important effect on purchase behavior was price benefit. The study implies that social density (not spatial density) is important for consumer behavior and retail strategies.

Accuracy Improvement in Transfer-Type Variable Lamination Manufacturing Process using Expandable Polystyrene Foam and Experimental Verification (단속형 가변 적층 쾌속 초형 공정(VLM-ST)을 위한 정밀도 향상에 관한 연구 및 실험적 검증)

  • Choe, Hong-Seok;An, Dong-Gyu;Lee, Sang-Ho;Yang, Dong-Yeol
    • Journal of the Korean Society for Precision Engineering
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    • v.19 no.7
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    • pp.97-105
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    • 2002
  • The use of rapid prototyping (RP) has reduced time to market, cut total costs and improved product quality by giving design and manufacturing teams the opportunity to verify and fine tune designs before committing them to expensive tooling and fabrication. In order to improve their unique characteristics according to the working principles, Variable Lamination Manufacturing process (VLM-ST) and corresponding CAD/CAM software (VLM-Slicer) is developed. The objective of this study is to improve the accuracy of VLM-ST process, and it can be done by offset fur cutting error correction, cutting path overrun fur sharp edge and reference shape generation for off-line stacking. It has been shown that, through the verification experiments for given practical shapes, the proposed algorithms are effective for diverse categories of three-dimensional shapes.

Study on Design Optimization of Degasser Baffles using CFD (전산유체역학을 이용한 Degasser Baffle최적설계 연구)

  • Sur, Jong-Mu;Im, Hyonam;Lee, In-Su;Lee, Heesung;Choi, Jaewoong
    • Journal of Ocean Engineering and Technology
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    • v.29 no.5
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    • pp.331-341
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    • 2015
  • A degasser is a separation unit used in drilling to separate gas from the drilling mud. The degasser used in offshore drilling was developed at an early stage of drilling. Since its development, the design of the degasser’s internal structure has been optimized, with many limitations due to the restrictions of experimental and computational performance measurement methods. Despite the recent development of CFD technology for multiphase flow analysis, CFD has only been used in a limited way for degasser internal flow analysis and design optimization. In this study, a design optimization procedure for a degasser’s internal structure design was proposed, and CFD analyses of three types of internal structural designs were performed to evaluate the separation performance. The CFD result for each design type was used for the design optimization and, as the result, an optimized design is proposed.

A Two-antenna GPS Receiver Integrated with Dead Reckoning Sensors (Two-antenna 자세 결정용 GPS 수신기와 DR 센서의 통합 시스템)

  • 이재호;서홍석;성태경;박찬식;이상정
    • 제어로봇시스템학회:학술대회논문집
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    • 2000.10a
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    • pp.186-186
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    • 2000
  • In the GPS/DR integrated system, the GPS position(or velocity) is used to compensate the DR output and to calibrate errors in the DR sensor. This synergistic relationship ensures that the calibrated DR accuracy can be maintained even when the GPS signal is blocked. Because of the observability problem, however, the DR sensors are not sufficiently calibrated when the vehicle speed is low. This problem can be solved if we use a multi-antenna GPS receiver for attitude determination instead of conventional one. This paper designs a two-antenna GPS receiver integrated with DR sensors. The proposed integration system has three remarkable features. First, the DR sensor can be calibrated regardless of the vehicle speed with the aid of two-antenna GPS receiver. Secondly, the search space of integer ambiguities in GPS carrier-phase measurements is reduced to a part of the surface of the sphere using DR heading. Thirdly, the detection resolution of cycle-slips in GPS carrier-phase measurements is improved with the aid of DR heading. From the experimental result, it is shown that the search grace is drastically reduced to about 3120 of the non-aided case and the cycle-slips of 1 or half cycle can be detected.

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Performance Evaluation of an Electrohydrodynamic Spray Nozzle for Regeneration of Particulate Matter on Diesel Particulate Filter (경유차 입자상물질 저감필터(DPF) 재생용 전기수력학적 연료 후분사 노즐의 미립화 특성 평가 및 수치해석을 이용한 액적 입경별 연소 특성 평가)

  • Jeong, Seonghun;Park, Sung-Eun;Kim, Min-Jung;Cho, Hyung-Jei;Hwang, Jungho
    • Particle and aerosol research
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    • v.8 no.2
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    • pp.55-68
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    • 2012
  • Particulate matters (PM) which are collected into a diesel particulate filter (DPF) system have to be periodically removed by thermal oxidation. In this report, we fabricated an electrohydrodynamic-assisted pressure-swirl nozzle to spray diesel droplets finer. Atomization performance of the nozzle was evaluated using both experimental and numerical methods. Two types of nozzle designs, the charge induction type and the charge injection type, were tested. While the former generated diesel droplets of $400\;{\mu}m$ at an applied electric potential over 10 kV, the latter presented the droplets smaller than $23\;{\mu}m$ at an applied electric potential of 8 kV. The numerical simulation results showed that the reduced size of droplets caused higher evaporation of droplets and therefore the increased temperature, which would eventually increase the regeneration performance of the DPF system.