• Title, Summary, Keyword: S/B ratio

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Signal to Noise Ratio of the Announcement from Reinforced Sound System and Background Noise in Transportation Facility (교통시설에서의 스피커 안내음과 배경소음의 신호대잡음비)

  • Song, Han-Sol;Ryu, Jong-Kwan;Jin, Min-Gyu;Sung, Chang-Ju
    • 한국건축친환경설비학회 논문집
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    • v.11 no.5
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    • pp.355-363
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    • 2017
  • This study investigated signal to noise ratio (S/N) of the signal sound and announcement in transportation facilities such as subway and railway station, bus-terminal and airport. The result of survey in subway station showed that 82% of participants were dissatisfied with the signal sound and announcement. Acoustical characteristic and S/N of the signal sound and announcement were also analysed after measuring the signal sound, announcement, train arriving noise and background noise in transportation facilities. In the subway station, the S/N ratios ranged from - 14.4~13.8 dB and mostly were lower than 10 dB, which is suitable value for word recognition of elderly person. The S/N ratio in the railway station ranged from 0.7 to 5.7 dB, and the ratio in the bus terminal and airport was 8.4 dB and 9.2 dB, respectively. For the subway station, the S/N ratio in separated platform was 2 dB higher than that of island platform, and the ratio in platform with screen door was about 7 dB higher than that in platform without screen door.

Effects of deck's width-to-depth ratios and turbulent flows on the aerodynamic behaviors of long-span bridges

  • Lin, Yuh-Yi;Cheng, Chii-Ming;Lan, Chao-Yuan
    • Wind and Structures
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    • v.6 no.4
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    • pp.263-278
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    • 2003
  • This study investigates the effects of a bridge deck's width-to-depth (B/H) ratio and turbulence on buffeting response and flutter critical wind speed of long-span bridges by conducting section model tests. A streamlined box section and a plate girder section, each with four B/H ratios, were tested in smooth and turbulent flows. The results show that for the box girders, the response increases with the B/H ratio, especially in the vertical direction. For the plate girders, the vertical response also increases with the B/H ratio. However, the torsional response decreases as the B/H ratio increases. Increasing the B/H ratio and intensity of turbulence tends to improve the bridge's aerodynamic stability. Experimental results obtained from the section model tests agree reasonably with the calculated results obtained from a numerical analysis.

The Fundamental Properties of Alkali-Activated Slag Cement (AASC) Mortar with Different Water-Binder Ratios and Fine Aggregate-Binder Ratios (물-결합재 비와 잔골재-결합재 비에 따른 알칼리 활성화 슬래그 모르타르의 기초특성)

  • Kim, Tae-Wan;Hahm, Hyung-Gil;Lee, Seong-Haeng;Eom, Jang-Sub
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.17 no.5
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    • pp.77-86
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    • 2013
  • This study investigates the fundamental properties of the water-binder (W/B) ratio and fine aggregate-binder (F/B) ratio in the alkali-activated slag cement (AASC) mortar. The W/B ratios are 0.35, 0.40, 0.45, and 0.50, respectively. And then the F/B ratios varied between 1.00 and 3.00 at a constant increment of 0.25. The alkali activator was an 2M and 4M NaOH. The measured mechanical properties were compared, flow, compressive strength, absorption, ultra sonic velocity, and dry shrinkage. The flow, compressive strength, absorption, ultra sonic velocity and dry shrinkage decreased with increases W/B ratio. The compressive strength decreases with increase F/B ratio at same W/B ratio. Also, at certain value of F/B ratio significant increase in strength is observed. And S2 (river sand 2) had lower physical properties than S1 (river sand 1) due to the fineness modulus. The results of experiments indicated that the mechanical properties of AASC depended on the W/B ratio and F/B ratio. The optimum range for W/B ratios and F/B ratios of AASC is suggested that the F/B ratios by 1.75~2.50 at each W/B ratios. Moreover, the W/(B+F) ratios between 0.13 and 0.14 had a beneficial effect on the design of AASC mortar.

Effects of n-6/n-3 and P/S Ratio of Dietary Lipid on Thromboxane B2 and 6-Keto prostaglandin F1$\alpha$ Production in Rat (P/S 비율과 n-6/n-3 비율을 달리한 식이지방이 흰쥐의 Thromboxane B2 와 6-Keto prostaglandin F1$\alpha$ 합성에 미치는 영향 연구)

  • 김우경
    • Journal of Nutrition and Health
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    • v.27 no.6
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    • pp.574-582
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    • 1994
  • The effects of age and dietary fatty acid composition on prostagladin production was investigated in Sprague-Dawley strain male rats. Animals weighing 88.6$\pm$2.2g were fed 10% dietary fat(W/W, 20% of total energy). The P/S ratios of dietary lipid were three levels(0.5, 1, 2) and there were three different levels of n-6/n-3 fatty acid ratio(2, 4, 8) in each P/S ratio. The experimental period were 1 month and 12 months, respectively. The results of this study were as follows. As the age of rats increased, the plasma thromboxane B2 production increased, but aorta 6-keto prostaglandin F1$\alpha$ decreased. When a higher amount of n-3 fatty acid was fed in each P/S ratio, the relative percentage of linolenic acid and EPA in platelet increased.

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Unconfined Compressive Strength Characteristics of E.S.B. Mixed Soil Based on Soil Compactness and Curing Period (토양의 다짐도와 재령기간에 따른 E.S.B. 혼합토의 일축압축강도특성)

  • Oh, Sewook;Kim, Hongseok;Bang, Seongtaek
    • Journal of the Korean Geoenvironmental Society
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    • v.20 no.5
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    • pp.47-55
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    • 2019
  • This study aims to provide basic data for soil packaging differing in accordance with the strength characteristics of mixed soil, using E.S.B. (Eco Soil Binder), an eco-friendly hardening agent, based on the type of soil. The soil used in this study is weathered granite soil readily collected in and around Korea, and is classified into SW, SP and SC according to soil classification systems. The test piece for the unconfined compressive strength test has dimensions of 50 mm in diameter and 100 mm in height, with the mix ratio of E.S.B. proportional to the weight of mixed soil changed from 5% to 10%, 15%, 20%, 25%, and 30%, where compactness of 90% and 100% were applied according to each condition to analyze the unconfined compressive strength characteristics at material ages of 3, 7, and 28 days. Also, the ratio of soil packaging standard strength and unconfined compressive strength was calculated to determine the optimal E.S.B. mix ratio, whereby the field applicability of the unconfined compressive strength using the estimation equation of ACI209R was evaluated.

PS-b-PDMS와 Amorphous Carbon Layer를 이용하여 Aspect-ratio와 Line-edge 개선에 대한 연구

  • O, Ji-Su;Seong, Da-In;O, Jong-Sik;Yeom, Won-Gyun;Yeom, Geun-Yeong
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • pp.142-142
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    • 2017
  • High Flory-Huggins interaction parameter (${\chi}$)를 가지는 polystyrene-block-dimethylsiloxane (PS-b-PDMS)는 초미세 패턴 제작과 우수한 defect density, 우수한 edge roughness 특성으로 향상된 패턴을 제공한다는 점에서 반도체 분야에서 많은 연구가 되고 있다. 하지만, PS와 PDMS 사이에 존재하는 큰 surface tension의 차이로 인해 PDMS는 PS와 air 사이에서 segregate되기 때문에 수직배향에 불리하여 high aspect ratio (HAR)을 가지는 cylinder, lamellar 패턴 제작에 있어 큰 어려움을 가진다. 본 연구에서는 이러한 문제를 해결하기 위해, PS-b-PDMS BCP 패턴과 하부 실리콘 기판 사이에 amorphous carbon layer (ACL)를 삽입하여 효과적으로 pattern transfer하는 공정을 연구하였다. 플라즈마를 이용하여 무한대에 가까운 etch selectivity를 가지는 식각 공정을 개발함으로써 낮은 aspect ratio를 가지는 PS-b-PDMS BCP 패턴의 한계점을 극복하였다. Large-x value를 가지는 BCPs를 이용하여도 매우 높은 aspect ratio를 가지면서 동시에 pattern quality를 향상시킬 수 있는 plasma process를 제시하였다.

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Flow and Compressive Strength Properties of Low-Cement Soil Concrete (저시멘트 소일콘크리트의 유동성 및 압축강도 특성)

  • Park, Jong-Beom;Yang, Keun-Hyeok;Hwang, Chul-Sung
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.6 no.1
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    • pp.1-7
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    • 2018
  • This study examined the effect of binder-to-soil ratio(B/S) and water-to-binder ratio(W/B) on the flow and compressive strength development of soil concrete using high-volume supplementary cementitious materials. As a partial replacement of ordinary portland cement, 10% by-pass dust, 40% ground granulated blast-furnace slag, and 25% circulating fluidized bed combustion fly ash were determined in the preliminary tests. Using the low-cement binder incorporated with clay soil or sandy soil, a total of 18 soil concrete mixtures was prepared. The flow of the soil concrete tended to increase with the increase in W/B and B/S, regardless of the type of soils. The compressive strength was commonly higher in sandy soil concrete than in clay soil concrete with the same mixture condition. Considering the high-workability and compressive strength development, it could be recommended for low-cement soil concrete to be mixed under the following condition: B/S of 0.35 and W/B of 175%.

A Study on the Changes in Spatial Composition Ratio of National Rental Houses - Focused on the Jangseong-gun Jeollanam-do Province - (국민임대주택의 평면구성비 변화에 관한 연구 -전라남도 장성군을 중심으로 -)

  • Kim, Hong-Bae
    • Journal of the Korean Institute of Rural Architecture
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    • v.20 no.1
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    • pp.61-68
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    • 2018
  • This study aims to investigate the changes in area ratios by space through floor plans of national leasing houses constructed by the LH in Jangseong-gun, particularly focusing on the floor plans of public leasing housing complexes built during the 1970s-80s and those during the 2010s. The results are as follows: First, according to the composition ratio of floor plans by period, the type of Bedroom> Livingroom> Common Area> Kitchen+Dining> Multi-purpose room> Bathroom> or the type of Bedroom> Livingroom> Kitchen/Dining> Common Area> Bathroom> Multi-purpose room were found to be high during the 1970s. Whereas, the type of Common Area>Living room(Kitchen/Dining included)>Bedroom>Bathroom>Front Entrance was found to be high during the 2010. It can be concluded that the ratio of Bedroom and Living room was found to be high during the 1970s, but after 2010s, the spacial composition ratio of Common Space, Living room, and Bedroom is getting higher in the order. Second, in terms of the composition ratio of floor plans by the area of unit household, among the floor plan of C-1, B-2, B-3, C-2 which were used since 2010s, the spatial ratio of Bedroom was maintained in the range of 20%; while during the 1970s, the Bedroom space of A-1(46%), A-2(46%), and A-3(41%) was found to be higher than 40%. It can be concluded that the size of bedroom space has doubled over time. In terms of the changes in the spatial ratio of Living room, A-1(15%), A-2(22%), and A-3(23%) were found during the 1970s. Compared to the recent floor plans of C-1(28%), B-2(25%), B-3(33%), and C-2(34%) which are applied in Jangseong-gun, Jeollanam-do province, no big changes have been found, particularly in the small floor plans (20% range).

A Study on the Protection Ratio of GPS (GPS 보호비 연구)

  • Yu, Byeong-Jae;Shim, Yong-Sup;Cho, Hyun-Mook;Lee, Il-Kyoo;Hong, Heon-Jin
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.36 no.3A
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    • pp.296-301
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    • 2011
  • GPS(Global Positioning System) service is more important than other wireless services. The GPS is necessary protected from any other interference signals. Therefore, GPS protection ratio was calculated on the basis of bit error rate(BER) in this paper. Simulation results show that the allowable maximum interference power is -190 dBm/Hz and the ratio of interference to noise(I/N) is -16 dB. The achieved protection ratio is available to be applied as the protection criteria of GPS in considering the implementation margin of 4 dB. As a result, the proposed protection ratio of GPS is expected to give standard for a stable GPS service.

Development of the Delamination Evaluation Parameters (I) -The Delamination Aspect Ratio and the Delamination Shape Factors-

  • Song, Sam-Hong;Oh, Dong-Joon
    • Journal of Mechanical Science and Technology
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    • v.18 no.11
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    • pp.1932-1940
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    • 2004
  • Although the previous researches evaluated the fatigue behavior of Al/GFRP laminates using the traditional fracture mechanism, their researches were not sufficient to do it : the damage zone of Al/GFRP laminates was occurred at the delamination zone instead of the crack-metallic damages. Thus, previous researches were not applicable to the fatigue behavior of Al/GFRP laminates. The major purpose of this study was to evaluate delamination behavior using the relationship between crack length (a) and delamination width (b) in Al/GFRP laminate. The details of investigation were as follows: 1) Relationship between the crack length (a) and the delamination width (b), 2) Relationship between the delamination aspect ratio (b/a) and the delamination area rate ((A$\_$D/)/subN// (A$\_$D/)$\_$All/), 3) The effect of delamination aspect ratio (b/a) on the delamination shape factor (f$\_$s/) and the delamination growth rate (dA$\_$D// da). As results, it was known that the delamination aspect ratio (b/a) was decreased and the delamination area rate ((A$\_$D/)$\_$N// (A$\_$D/)$\_$All/) was increased as the normalized crack size (a/W) was increased. And, the delamination shape factors (f$\_$s/) of the ellipse-II(f$\_$s3/) was greater than of the ellipse-I(f$\_$s2/) but that of the triangle (f$\_$s1/) was less than of the ellipse-I(f$\_$s2/).