• Title/Summary/Keyword: Flow efficiency

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Engineering Characteristics of CLSM Using Bottom Ash and Eco-friendly Soil Binder (친환경 고결제와 저회를 활용한 유동성 복토재의 공학적특성)

  • Park, Giho;Kim, Taeyeon;Lee, Yongsoo;Lee, Bongjik
    • Journal of the Korean GEO-environmental Society
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    • v.20 no.5
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    • pp.23-29
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    • 2019
  • In general, pipe laying works are performed by constructing underground facilities such as pipes and then refilling the rest of the area with sand or soil. However, there are many problems in the compaction process such as difficulties in tampering around the underground facility and low compaction efficiency. Such problems cause deformation and damage to the underground pipes during refilling work and ultimately cause road sinks. Construction methods using CLSM are one of the typical methods to solve these issues, and recently, studies on CLSM using coal ash, which has similar engineering properties as sand, have been actively performed to protect environment and recycle resources. While many studies have been conducted to recycle fly ash in many ways, the demand for recycling bottom ash is increasing as most of the bottom ash is not recycled and reclaimed at ash disposal sites. Therefore, in order to find bottom ash applications using eco-friendly soil binders that are environmentally beneficial and conform with CLSM standards, this study investigated flow characteristics and strength change characteristics of eco-friendly soil binders, weathered granite soil, a typical site-generated soil, bottom ash, and fly ash mixed soil and evaluated the soil pollution to present CLSM application methods using bottom ash.

A Study on Real Time Signal Metering Operation at Roundabouts by Considering Queue Clearance Time (대기행렬 소거시간을 고려한 회전교차로 실시간 신호미터링 운영 연구)

  • Lee, Sol;Ahn, Woo-Young;Lee, Seonha;Cho, Han-Seon
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.17 no.6
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    • pp.133-143
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    • 2018
  • Roundabouts are generally installed at which traffic and pedestrian volume is relatively small intersections, and hence traffic can flow one direction around a circular island without traffic lights. A number of researches for roundabout signal metering have been processing ways to deal with operation efficiency drops in conditions of unusual traffic and pedestrian volume increases. However, there is still a shortcoming exists in previous operation algorithm does not consider the hidden vehicles between yield lines and detectors and queueing vehicles in circular lanes. These queueing vehicles between them can be cleared by introducing the queue clearance time. The purpose of this research is developing a real time signal metering operation algorithm by considering the vehicle queue clearance time. The results of varying queue clearance time application show that there is a substantial average vehicle delay reduction in VISSIM Com-Interface simulation. When the total number of entering vehicle is 3,200~4,800 vehicle/hour with varying queue clearance time application 21~50 seconds gives average delay reduction per vehicle by 16.1~71.7%.

Analysis of Genetic Diversity and Structural Changes in Hanwoo Proven Bulls Population (한우 보증씨수소 집단의 유전적 다양성 및 구조 변화 분석)

  • Shin, Dong-Hyun;Kim, Do-Hyun;Oh, Jae-Don
    • ANNALS OF ANIMAL RESOURCE SCIENCES
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    • v.29 no.4
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    • pp.142-149
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    • 2018
  • In this study, 844 Hanwoo proven bulls in South Korea (called KPN) were classified into 8 groups based on their birth year. Microsatellite (MS) marker information for paternity identification of each individual is provided at the homepage of the National Agricultural Cooperation Federation, Korea (NACF) and is mainly for the analysis of genetic diversity and structural changes. The polymorphism analysis of KPN whole groups revealed the average number of alleles in each marker (number of alleles), the expected heterozygosity (Hex), the observed heterozygosity (Hob), the polymorphism information content (PIC) and the Fis mean as 10.54, 0.764, 0.773, 0.727 and -0.014, respectively. For group D, with the birth year 2004-2005, the Hex and Hob were 0.777 and 0.792 respectively and the PIC was 0.740. The Hex of group C and D, with birth years 2003-2004 and 2007-2008, respectively, were greater than Hob. In all the other groups, Hob was greater than Hex. Genetic composition and structure were analyzed using STRUCTURE software. According to the analyzed results, the generation of Hanwoo groups showed changes in specific genetic components according to the flow. It was confirmed that the continuous improvement in the Hanwoo affects the genetic structure of the proven bulls group. The results of this study are expected to be used for enhancing the efficiency of Hanwoo improvement project.

Threshold Condition for Exclusion of Riprap into Bypass Pipe (저층수 배출관에 유입된 사석의 배제 한계조건)

  • Jeong, Seokil;Lee, Seung Oh
    • Journal of Korean Society of Disaster and Security
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    • v.12 no.1
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    • pp.57-66
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    • 2019
  • One of the most serious problems with concrete small dams or barriers installed in small/median rivers is the deposit of sediments, especially, in Korea. An effective way to discharge such sediments to downstream is to construct a bypass pipe under the river bed. However, efficiency may become lowered if ripraps are entered into the bypass pipe. Therefore, in this study, we derived the threshold condition for the exclusion of ripraps from the bypass pipe using 3D numerical analysis. Upstream flow of the small dam was assumed to be stationary, and the energy concept was applied to the control volume containing the bypass pipe and its periphery. As a result, when the ratio of the water level difference between upstream and downstream to the diameter of the riprap was approximately equal to 1.2, the threshold condition for exclusion of the stones or riprap from the bypass pipe was affirmatively determined. If the characteristics of the adsorptive sediment adversely affecting the river environment in the future would be taken into account, results from this study are expected to put to practical use in the management of concrete small dam with bypass pipe system.

Variation of Liquid to Gas Ratio and Sulfur Oxide Emission Concentrations in Desulfurization Absorber with Coal-fired Thermal Power Plant Outputs (석탄화력 발전설비의 출력에 따른 탈황 흡수탑 액기비와 황산화물 배출농도 변화에 대한 연구)

  • Kim, Kee-Yeong;Moon, Seung-Jae
    • Plant Journal
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    • v.14 no.4
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    • pp.39-47
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    • 2018
  • In this research, when the output of the standard coal-fired thermal power plant operating continuously at the rated output of 500 MW is changed to operate at 300 to 500 MW, the amount of sulfur oxide produced and the amount of sulfur oxide in the absorption tower of desulfurization equipment and proposed an extra liquid to gas ratio improvement inversely proportional to the output. In order to calibrate the combustion efficiency at low power, the ratio of sulfur oxides relative to the amount of combustion gas is increased as the excess air ratio is increased. When the concentration of sulfur oxide at the inlet of the desulfurization absorber was changed from 300 to 500 ppm along with the output fluctuation. The liquid to gas ratio of limestone slurry and combustion gas was changed from 10.99 to 16.27. Therefore, if the concentration of sulfur oxides with output of 300 MW is x, The following correlation equation is recommended for the minimum required flow rate of slurry for the reduction of surplus energy due to the increase of the liquid weight at low load. $y1[m^3/sec]=0.11x+3.74$

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Development of Noise and AI-based Pavement Condition Rating Evaluation System (소음도·인공지능 기반 포장상태등급 평가시스템 개발)

  • Han, Dae-Seok;Kim, Young-Rok
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.22 no.1
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    • pp.1-8
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    • 2021
  • This study developed low-cost and high-efficiency pavement condition monitoring technology to produce the key information required for pavement management. A noise and artificial intelligence-based monitoring system was devised to compensate for the shortcomings of existing high-end equipment that relies on visual information and high-end sensors. From idea establishment to system development, functional definition, information flow, architecture design, and finally, on-site field evaluations were carried out. As a result, confidence in the high level of artificial intelligence evaluation was secured. In addition, hardware and software elements and well-organized guidelines on system utilization were developed. The on-site evaluation process confirmed that non-experts could easily and quickly investigate and visualized the data. The evaluation results could support the management works of road managers. Furthermore, it could improve the completeness of the technologies, such as prior discriminating techniques for external conditions that are not considered in AI learning, system simplification, and variable speed response techniques. This paper presents a new paradigm for pavement monitoring technology that has lasted since the 1960s.

Application of Remote Sensing Technology for Developing REDD+ Monitoring Systems (REDD+ 모니터링 시스템 구축을 위한 원격탐사기술의 활용방안)

  • Park, Taejin;Lee, Woo-Kyun;Jung, Raesun;Kim, Moon-Il;Kwon, Tae-Hyub
    • Journal of Korean Society of Forest Science
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    • v.100 no.3
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    • pp.315-326
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    • 2011
  • In recent years, domestic and international interests focus on climate change, and importance of forest as carbon sink have been also increased. Particularly REDD+ mechanism expanded from REDD (Reduced Emissions from Deforestation and Degradation) is expected to perform a new mechanism for reducing greenhouse gas in post 2012. To conduct this mechanism, countries which try to get a carbon credit have to certify effectiveness of their activities by MRV (Measuring, Reporting and Verification) system. This study analyzed the approaches for detecting land cover change and estimating carbon stock by remote sensing technology which is considered as the effective method to develop MRV system. The most appropriate remote sensing for detection of land cover change is optical medium resolution sensors and satellite SAR (Synthetic Aperture Radar) according to cost efficiency and uncertainty assessment. In case of estimating carbon stock, integration of low uncertainty techniques, airborne LiDAR (Light Detection and Ranging), SAR, and cost efficient techniques, optical medium resolution sensors and satellite SAR, could be more appropriate. However, due to absence of certificate authority, guideline, and standard of uncertainty, we should pay continuously our attention on international information flow and establish appropriate methods. Moreover, to apply monitoring system to developing countries, close collaboration and monitoring method reflected characteristics of each countries should be considered.

An analysis of hydraulic characteristics of stepped boulder fishway installed in mountain stream (산지하천에 설치된 계단식 전석 어도의 수리 특성 분석)

  • Kim, Ki Heung
    • Journal of Korea Water Resources Association
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    • v.55 no.1
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    • pp.99-109
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    • 2022
  • This study was intended to suggest the applicability of stepped boulder fishway using the concept of traditional boulder weir, focusing on the problems of existing concrete pool-and-weir fishways installed in mountain streams. To achieve this purpose, a stepped boulder fishway was designed and constructed as a pilot project in consideration of ascending capacity of the selected target fishes. Under the given discharge conditions, the hydraulic characteristics of the fishway were investigated in the field, and the characteristics and ascending capacity of the fishes were compared and analyzed. The fishway had a short length and steep slope, but the mean drops between each baffle were the range of 0.15 to 0.29 m, and this range satisfied the limit condition of about 0.40 m, which was in the limit of the drop that target fishes can ascend. The mean velocities of each baffle and pool were 0.82 to 0.87 m/sec and 0.13 to 0.24 m/sec. This result satisfied the conditions of burst speed (10 to 30 times of body length) and mean velocity of the resting pool (7 to 25% of burst speed) for target fishes. Since the bottom surface of the pool formed of boulders had a gentle reverse slope and rotational flow did not occur, the efficiency of fishway can be increased, and it will also be possible to solve the maintenance problem by flushing bed materials.

Recovery of Silver from Nitrate Leaching Solution of Silicon Solar Cells (실리콘 태양전지 질산침출액에서 LIX63를 이용한 은(Ag) 회수)

  • Cho, Sung-Yong;Kim, Tae-Young;Sun, Pan-Pan
    • Resources Recycling
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    • v.30 no.2
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    • pp.39-45
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    • 2021
  • Spent photovoltaic module is one of the important resource of silver, while related research concerning silver recovery remains limited. In our previous research, HNO3 was utilized to dissolve Ag(I) and Al(III) from the spent silicon solar cells. In order to recover Ag(I) from the leachate of a silicon solar cell, the present study made use of a nitrate solution containing Ag(I) and Al(III), which was subjected to a solvent extraction process with 5,8-diethyl-7-hydroxydodecan-6-oxime (LIX63). Ag(I) was selectively extracted with LIX63 over Al(III) from the nitrate leach solution. Subsequently, quantitative stripping of Ag(I) from the loaded LIX63 was performed by using 20% ammonia water. The McCabe-Thiele plots for the extraction and stripping isotherms of Ag(I) were also constructed. Extraction and stripping simulation tests confirmed an Ag(I) extraction and stripping efficiency of >99.99% and 98.9%, respectively with high purity Ag (99.998%) and Al (99.99%) solution. A process flow sheet for Ag(I) recovery from the nitrate leach solution was proposed.

Analysis of the Sports Welfare Service Delivery System for the Sports Vouchers (스포츠강좌이용권의 스포츠복지서비스 전달체계 분석)

  • Choi, Hee-Dong
    • Journal of Korea Entertainment Industry Association
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    • v.14 no.5
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    • pp.131-146
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    • 2020
  • This research is based on social flow that is in need of sports welfare that diagnoses the delivery system of sports program pass that is typical business of national sports welfare services and operation structure, and analyze the supplier, operator, beneficiary and all that is related to business from multilateral aspects, therefore seek for operation systems for provision systems of sports welfare services. To clearly grasp the operating mechanisms of service provision system that is happening in real field, there were in-depth interview done by the 18 people of suppliers, operators, and beneficiaries that are the main participants of business, and through which drew an ideal agreed point for sports welfare services to get in the right direction. The result of this study is as following: First, based on the limited government budget for the compilation of budget for the business of sports welfare services it is found that there is need of constructing a pragmatic service provision system that can bring maximum of efficiency. Second, voucher that was introduced for market logic application and greater transparency of the business of sports welfare services has a complex structure that it is in need of simplification of structure which that is well fit with its characteristics. Third, for convenience enlargement in administration and management, make management policy of provision system be reflected and therefore enlarge the independence of management and secure the power of negotiation regarding fee savings through centralized budget management.