• Title/Summary/Keyword: Driving Cycle

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Overfishing and recent risk for collapse of fishery in coastal Mediterranean lagoon ecosystem (Karavasta lagoon, southeastern Adriatic sea)

  • Spase Shumka;Yukio Nagahama;Sarjmir Hoxha;Koji Asano
    • Fisheries and Aquatic Sciences
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    • v.26 no.4
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    • pp.294-303
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    • 2023
  • Beside that the fish species and their sub-populations are highly important as a keystone species in the coastal and marine ecosystem, there are very few studies on their presence, distribution and temporal variations within and around the lagoon ecosystems in Albania. This paper provides an updated review on the life cycle, fishery, exploitation state and management of the main species that are subject of commercial fishing in the Karavasta lagoon, southeastern Adriatic coast of Albania. Due to the fact that lagoons represent a continuum between continental and marine aquatic ecosystems they play a crucial role in species life cycles. Further on in the circumstances of rapid utilizations and environmental changes, anomalies in salinity and temperatures, accelerated anthropogenic influences their rate of vulnerability is highly increased. Following the requirements of the Water Framework Directive, transitional water, coastal lagoons and estuaries there is a need for urgent monitoring and management approaches. The commercial species include: European eel (Anguilla anguilla), species of Family Mugilidae (Mugil cephalus, Liza ramada, Liza salienes and Chelon labrosus), Seabream (Sparus aurata), Seabass (Dincentrarchus labrax), etc. Fish productivity is oscillating from maximum value of 61.95 kg/ha is recorded in period of 1975-80 and lower value of 31 kg/ha in year 2020. Our study highlights importance of fish and fishery long-term monitoring, and contributes to understand the driving factors in productivity, migration patterns and species ecology in the vital coastal ecosystems.

External mechanisms driving ecosystem changes in a coastal wetland, the Mississippi Delta, USA

  • Ryu, Junghyung;Liu, Kam-biu;McCloskey, Terrence A.;Yun, Sang-Leen
    • Proceedings of the Korea Water Resources Association Conference
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    • 2022.05a
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    • pp.85-85
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    • 2022
  • The world's most extensive and active deltas, Louisiana's wetlands, are deteriorating rapidly due to multiple stressors such as the discharge of the Mississippi River, sea-level rise, and coastal retreat, the substantial but spatially and temporally variable impacts. However, the ecological and anthropogenic histories, the mode of environmental changes on a multi-millennial timescale have not been thoroughly documented. This study, a palynology-based multiproxy analysis, investigates hydrological, geological, geochemical, and anthropogenic impacts on southern Louisiana wetlands and a variety of external forcing agents influencing ecological succession. Sediment cores extracted from a small pond on a mangrove-dominate island near Port Fourchon, Louisiana, USA yielded a 4,000-year record. The site has been transformed from freshwater to saline water environments, to a mangrove dominant island over the late Holocene. The multivariate principal component analysis identified the relative strength of external drivers responsible for each ecological shift. The Mississippi River delta cycle (lobe switching) was the dominant driver of ecosystem changes during the late Holocene, while relative sea-level rise, tropical cyclones, climate, and anthropogenic effects have been the main drivers late in the site's history.

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Evaluation of along-channel sediment flux gradients in an anthropocene estuary with an estuarine dam

  • Figueroa, Steven M.;Lee, Guan-hong;Chang, Jongwi;Schieder, Nathalie W.;Kim, Kyeongman;Kim, Seok-Yun;Son, Minwoo
    • Proceedings of the Korea Water Resources Association Conference
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    • 2022.05a
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    • pp.86-86
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    • 2022
  • While estuarine dams can develop freshwater resources and block the salt intrusion, they can result in increased sediment deposition in the estuary. The mechanism of increased sediment deposition in an estuary with an estuary dam is not well understood. To fill this knowledge gap, 7 ADCP measurements of flow and suspended sediment concentration (SSC) were collected along-channel in an estuary with an estuarine dam over a neap-spring cycle. Flow and SSC were used to calculate the sediment flux and sediment flux gradients. The results indicated that the cumulative sediment fluxes at all stations were directed landward. The along-channel sediment flux gradient was negative, which indicated deposition along the channel. The landward mean-flow fluxes were dominant in the deep portion of the channel near the estuary mouth, whereas landward correlation fluxes were dominant in the shallow portion of the channel near the estuarine dam. The tides were the dominant forcing driving the sediment fluxes throughout the estuary.

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Edge to Edge Model and Delay Performance Evaluation for Autonomous Driving (자율 주행을 위한 Edge to Edge 모델 및 지연 성능 평가)

  • Cho, Moon Ki;Bae, Kyoung Yul
    • Journal of Intelligence and Information Systems
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    • v.27 no.1
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    • pp.191-207
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    • 2021
  • Up to this day, mobile communications have evolved rapidly over the decades, mainly focusing on speed-up to meet the growing data demands of 2G to 5G. And with the start of the 5G era, efforts are being made to provide such various services to customers, as IoT, V2X, robots, artificial intelligence, augmented virtual reality, and smart cities, which are expected to change the environment of our lives and industries as a whole. In a bid to provide those services, on top of high speed data, reduced latency and reliability are critical for real-time services. Thus, 5G has paved the way for service delivery through maximum speed of 20Gbps, a delay of 1ms, and a connecting device of 106/㎢ In particular, in intelligent traffic control systems and services using various vehicle-based Vehicle to X (V2X), such as traffic control, in addition to high-speed data speed, reduction of delay and reliability for real-time services are very important. 5G communication uses high frequencies of 3.5Ghz and 28Ghz. These high-frequency waves can go with high-speed thanks to their straightness while their short wavelength and small diffraction angle limit their reach to distance and prevent them from penetrating walls, causing restrictions on their use indoors. Therefore, under existing networks it's difficult to overcome these constraints. The underlying centralized SDN also has a limited capability in offering delay-sensitive services because communication with many nodes creates overload in its processing. Basically, SDN, which means a structure that separates signals from the control plane from packets in the data plane, requires control of the delay-related tree structure available in the event of an emergency during autonomous driving. In these scenarios, the network architecture that handles in-vehicle information is a major variable of delay. Since SDNs in general centralized structures are difficult to meet the desired delay level, studies on the optimal size of SDNs for information processing should be conducted. Thus, SDNs need to be separated on a certain scale and construct a new type of network, which can efficiently respond to dynamically changing traffic and provide high-quality, flexible services. Moreover, the structure of these networks is closely related to ultra-low latency, high confidence, and hyper-connectivity and should be based on a new form of split SDN rather than an existing centralized SDN structure, even in the case of the worst condition. And in these SDN structural networks, where automobiles pass through small 5G cells very quickly, the information change cycle, round trip delay (RTD), and the data processing time of SDN are highly correlated with the delay. Of these, RDT is not a significant factor because it has sufficient speed and less than 1 ms of delay, but the information change cycle and data processing time of SDN are factors that greatly affect the delay. Especially, in an emergency of self-driving environment linked to an ITS(Intelligent Traffic System) that requires low latency and high reliability, information should be transmitted and processed very quickly. That is a case in point where delay plays a very sensitive role. In this paper, we study the SDN architecture in emergencies during autonomous driving and conduct analysis through simulation of the correlation with the cell layer in which the vehicle should request relevant information according to the information flow. For simulation: As the Data Rate of 5G is high enough, we can assume the information for neighbor vehicle support to the car without errors. Furthermore, we assumed 5G small cells within 50 ~ 250 m in cell radius, and the maximum speed of the vehicle was considered as a 30km ~ 200 km/hour in order to examine the network architecture to minimize the delay.

From Hobby to Profession: A Phenomenological Study of the Emergence of Hobby-preneurs and its Impact on Arts and Cultural Ecology (취미에서 직업으로 - 하비프러너(hobby-preneur)의 출현과 문화예술 생태계 구조 변화에 관한 현상학적 연구 -)

  • Song, Nam Eun;Lyu, YuHee;Chang, WoongJo
    • Korean Association of Arts Management
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    • no.55
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    • pp.5-38
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    • 2020
  • This study focuses on the emergence of "hobby-preneurs" and the ways in which they are transforming the virtuous cycle of arts and cultural ecology. The hobby-preneur pursues and expands his or her favorite hobby into a professional job and/or arts business. Hobby-preneurs are the new driving force in the arts and cultural industry. Their activities enhance the arts as a public good even as they build valuable social capital for arts organizations and have a profound impact on supply and demand in the arts and cultural marketplace. Thus we found that by injecting and potentiating certain values that professional artists cannot directly deliver to arts consumers, hobby-preneurs function as major intermediaries in the virtuous cycle of arts and cultural ecology. To understand more about these emergent actors we examine their personal, social, and economic values and how these values guide their arts-related activities and thereby impact the ecology of the arts and cultural sector. In this study we use a phenomenological approach to investigate five hobby-preneurs and the particular ways their acquisition of professionalism is transforming the arts education node of the virtuous cycle in the creative sector.

Exhaust Gas Emission and Particulate Matter (PM) from Gasoline, LPG and Diesel Vehicle Using Different Engine Oil (가솔린, LPG, 디젤 차량에서 윤활유에 따른 배출가스 및 입자상물질)

  • Jang, Jinyoung;Lee, Youngjae;Kwon, Ohseok;Woo, Youngmin;Cho, Chongpyo;Kim, Gangchul;Pyo, Youngdug;Lee, Minseob
    • Transactions of the Korean Society of Automotive Engineers
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    • v.24 no.2
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    • pp.144-151
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    • 2016
  • This study effect of engine oils on regulated fuel economy and emissions including particulate matter (PM) to provide basic data for management of engine oil in vehicles. Three engine oils (Group III base oil, Group III genuine oil with additive package and synthetic oil with poly alpha olefins (PAOs)) were used in one gasoline, one LPG(liquefied petroleum gas) and two diesel vehicles. In the case of diesel vehicles, one is a diesel vehicle without DPF (diesel particulate filter) other is a diesel vehicle with DPF. In this study, the US EPA emission test cycle FTP-75, representing city driving, was used. HORIBA, PIERBURG, and AVL gas analyzers were used to measure the fuel economy and regulated emissions such as CO, NOx, and THC. The number of PM was measured using a PPS (pegasor particle sensor). And, the shape of PMs was analyzed by SEM (scanning electron microscope). The effects of oil type on fuel economy, exhaust gas, and PM were not significant because engine oil consumption by evaporation and combustion in the cylinder is very tiny. Fuel and vehicle type were dominant factors in fuel economy and emissions. HC emission from gasoline vehicles was higher than that from other vehicles and NOx emission from diesel vehicles was higher than that from other vehicles. The number of PM was not affected by the engine oil, but by the driving pattern and fuel. The shapes of the PM, sampled from each vehicle using any test engine oil, were similar.

Internal Flow Analysis of Urea-SCR System for Passenger Cars Considering Actual Driving Conditions (운전 조건을 고려한 승용차용 요소첨가 선택적 촉매환원장치의 내부 유동 해석에 관한 연구)

  • Moon, Seong Joon;Jo, Nak Won;Oh, Se Doo;Lee, Ho Kil;Park, Kyoung Woo
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.40 no.3
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    • pp.127-138
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    • 2016
  • Diesel vehicles should be equipped with urea-selective catalytic reduction(SCR) system as a high-performance catalyst, in order to reduce harmful nitrogen oxide emissions. In this study, a three-dimensional Eulerian-Lagrangian CFD analysis was used to numerically predict the multiphase flow characteristics of the urea-SCR system, coupled with the chemical reactions of the system's transport phenomena. Then, the numerical spray structure was modified by comparing the results with the measured values from spray visualization, such as the injection velocity, penentration length, spray radius, and sauter mean diameter. In addition, the analysis results were verified by comparison with the removal efficiency of the nitrogen oxide emissions during engine and chassis tests, resulting in accuracy of the relative error of less than 5%. Finally, a verified CFD analysis was used to calculate the interanl flow of the urea-SCR system, thereby analyzing the characteristics of pressure drop and velocity increase, and predicting the uniformity index and overdistribution positions of ammonia.

Experiment and Simulation of 2-bed PSA for Hydrogen Separation from H2/CH4 Gas Mixture (수소/메탄 혼합 기체로부터 수소 분리를 위한 두 탑 PSA 실험과 전산 모사)

  • Nam, Gi-Moon;Jeong, Byung-Man;Kang, Seok-Hyun;Lee, Chang-Ha;Lee, Byung-Kwon;Choi, Dae-Ki
    • Korean Chemical Engineering Research
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    • v.43 no.2
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    • pp.249-258
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    • 2005
  • A two-column six-step pressure swing adsorption(PSA) process was to study separation of hydrogen from hydrogen and methane($60_{vol}%/40_{vol}%$) binary system onto activated carbon adsorbent. The effects of the feed gas pressure, the feed flowrate and the P/F(purge to feed) ratio on the process performance were evaluated. The cyclic steady-states of PSA process were reached to after 15 cycles. $H_2$ purity increases according as the P/F ratio and pressure increase and the feed flow rate decreases; however, $H_2$ recovery shows an opposite phenomena to the purity. PSA process simulation studied to find optimum operation condition. In the results, 22 LPM feed flowrate, 11 atm adsorption pressure and 0.10 P/F ratio might be optimal values to obtain more than 75% recovery and 99% purity hydrogen. In this study was non-isothermal and non-adiabatic model considering linear driving force(LDF) model and Langmuir-Freundlich adsorption isotherm considered to compare between prediction and experimental data.

The Need for Weight Optimization by Design of Rolling Stock Vehicles

  • Ainoussa, Amar
    • International Journal of Railway
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    • v.2 no.3
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    • pp.124-126
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    • 2009
  • Energy savings can be achieved with optimum energy consumptions, brake energy regeneration, efficient energy storage (onboard, line side), and primarily with light weight vehicles. Over the last few years, the rolling stock industry has experienced a marked increase in eco-awareness and needs for lower life cycle energy consumption costs. For rolling stock vehicle designers and engineers, weight has always been a critical design parameter. It is often specified directly or indirectly as contractual requirements. These requirements are usually expressed in terms of specified axle load limits, braking deceleration levels and/or demands for optimum energy consumptions. The contractual requirements for lower weights are becoming increasingly more stringent. Light weight vehicles with optimized strength to weight ratios are achievable through proven design processes. The primary driving processes consist of: $\bullet$ material selection to best contribute to the intended functionality and performance $\bullet$ design and design optimization to secure the intended functionality and performance $\bullet$ weight control processes to deliver the intended functionality and performance Aluminium has become the material of choice for modern light weight bodyshells. Steel sub-structures and in particular high strength steels are also used where high strength - high elongation characteristics out way the use of aluminium. With the improved characteristics and responses of composites against tire and smoke, small and large composite materials made components are also found in greater quantities in today's railway vehicles. Full scale hybrid composite rolling stock vehicles are being developed and tested. While an "overdesigned" bodyshell may be deemed as acceptable from a structural point of view, it can, in reality, be a weight saving missed opportunity. The conventional pass/fail structural criteria and existing passenger payload definitions promote conservative designs but they do not necessarily imply optimum lightweight designs. The weight to strength design optimization should be a fundamental design driving factor rather than a feeble post design activity. It should be more than a belated attempt to mitigate against contractual weight penalties. The weight control process must be rigorous, responsible, with achievable goals and above all must be integral to the design process. It should not be a mere tabulation of weights for the sole-purpose of predicting the axle loads and wheel balances compliance. The present paper explores and discusses the topics quoted above with a view to strengthen the recommendations and needs for the weight optimization by design approach as a pro-active design activity for the rolling stock industry at large.

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Development of the Calorimeter to Measure Heat Rate Generated from Battery for EV & HEV (전기자동차용 축전지의 발열량 측정을 위한 열용량계 개발)

  • Yang Cheol-Nam;Park Seong-Yong
    • Journal of the Korean Electrochemical Society
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    • v.2 no.4
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    • pp.218-220
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    • 1999
  • The performance of the Electric Vehicle and Hybrid Electric Vehicle depends on that of the battery pack composed of series connected batteries. And thermal property is one of the main factors which decide the performance of the battery pack. So heat generation rate from the battery under the various driving mode must be measured as precise as possible because thermal characteristics of the battery affect the driving performance and battery pack's life cycle. Besides, to design and develop the battery thermal management system for the EV and HEV, the measurements of the thermal properties of the batteries are needed. However, the established calorimeter is not adequate to test an EV's battery because its cavity is too small to accommodate the EV's battery. Therefore we developed the calorimeter to test the thermal property of the EV's battery. Its cavity size is 120mm long, 75mm wide and 200mm high. The calorimeter is calibrated by the dummy cell which generates the heat rate from zero to 200W. The measuring accuracy of the calorimeter is within $2\%$ and its voltage stability is 2.5mV in the constant temperature bath.