• Title/Summary/Keyword: transport ability

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Coastal Protection with the Submerged Artificial Bio-reefs (인공 Bio-reef에 의한 해변침식방지)

  • Lee Hun;Lee Joong-Woo;Lee Hak-Sung;Kim Kang-Min
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • 2004.11a
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    • pp.159-166
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    • 2004
  • The beach, a margin between the sea and the land, is an extremely dynamic zone, for it is here that the motion of the sea interacts with the sediment, rock of the land or the artificial barriers. In order to prohibit or retard erosions due to the extreme Typhoon or storm induced waves, man has constructed these of temporary or more permanent nature, but they caused problems of other erosions from the secondary effect of them and a bad influence on the seascape. In considering the energy available to accelerate sediment transport and erosion in the surf zone, where the waves are broken, and offshore beyond the breaker line, the wave height and the wave period should be taken account. Hence, we tried to present an applicability of the submerged artificial Bio-reefs analyzing waves by a numerical model such that they could reduce the wave power without the secondary effect and restoration of marine ecologies. A new technique of beach preservation is by artificial reefs with artificial and/or natural kelps or sea plants. By engineering the geometry of the nearshore reef, the wave attenuation ability of the feature can be optimized Higher, wider and longer reefs provide the greatest barrier against wave energy but material volumes, navigation hazards, placement methods and other factors require engineering considerations for the overall design of the nearshore reefs.

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Interaction between Raindrops Splash and Sheet Flow in Interrill Erosion of Steep Hillslopes (급경사면의 세류간 침식에서 빗물튀김과 면상흐름의 상호작용)

  • Nam, Myeong Jun;Park, Sang Deog;Lee, Seung Kyu;Shin, Seung Sook
    • Journal of Korea Water Resources Association
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    • v.48 no.7
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    • pp.595-604
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    • 2015
  • Interrill erosion by the rainfall is divided into a detachment of soil particles by raindrop splash when raindrops having kinetic energy strike on the surface soil and a sediment transport by sheet flow of surface runoff. Rainfall kinetic energy is widely used as an indicator expressing the potential ability to separate the soil particles from soil mass. In this study, the soil erosion experiments of rainfall simulation were operated to evaluate the effects of rainfall kinetic energy on interrill erosion as using the strip cover to control raindrop impact. The kinetic energy from rainfall simulator was 0.58 times to that of natural rainfall. Surface runoff and subsurface runoff increased and decreased respectively with increase of rainfall intensity. Surface runoff discharge from plots of non-cover was 1.82 times more than that from plots with cover. The rainfall kinetic energy influenced on the starting time of surface and subsurface runoff. Soil erosion quantity greatly varied according to existence of the surface cover that can intercept rainfall energy. Sediment yields by the interaction between raindrop splash and sheet flow increased 3.6~5.9 times and the increase rates of those decreased with rainfall intensity. As a results from analysis of relationship between stream power and sediment yields, rainfall kinetic energy increased the transport capacity according to increase of surface runoff as well as the detachment of soil particles by raindrop splash.

Nitrate Reduction of Tobacco Leaves along the Stalk Position (담배식물(植物)의 엽서별(葉序別) 질산환원능력(窒酸還元能力) 비교(比較))

  • Lee, Yun-Hwan;Lim, Sun-Uk
    • Korean Journal of Soil Science and Fertilizer
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    • v.20 no.1
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    • pp.35-41
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    • 1987
  • Nitrate nitrogen was absorbed dominantly among the inorganic nitrogen nutrients by tobacco plant. Transport and reduction of $NO_3-N$ in plant tissue were the important metabolism for supplying synthetic N compounds to developing tissues during growth period. Under field and environment-controlled condition tobacco plants were grown and seperated to leaf tissues at stalk positions for investigation of nitrogen transport and assimilation ability during period of rapid vegative growth. The results of studies were summarized as follows: 1. $NO_3-N$ absorbed from roots was transported as inorganic nitrogen through the vascular tissue of leaf veins as resulting from the high $NO_3-N$ ratio of the nitrogen content in leaf veins, but these ratios in mesophyll tissue of the same leaf laminae decreased remarkably in disregard of higher accumulation of nitrogen being compared to midvien. 2. Mesophyll tissue of mature leaves appeared higher value of nitrate reductase activity (NRA) comparing with other tissues, stem, leaf vien, and meristmatic tissue at emergence point with young leaves. 3. Matured leaves at lower position being reducing nitrate nitrogen vigorously observed thick laminae and kept high amount of water in them. 4. Mature leaves of young plant reduced $NO_3-N$ vigorously for supply synthetic N compounds to meristmatic tissues at growing point by the reason of narrow and few leaves at young stage, but in advancing growth period NRA of mature leaves along upper position reached to lower value. This appearence attributed to distribution of organic-N compound demanding for growth to increasing numbers of wide leaves.

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Size Distributions of Trace Elements in Airborn Particulates Collected using Drum impactor at Gosan, Jeju Island : Measurements in Springtime 2002 (DRUM impactor를 이용한 대기 입자상 물질 중 원소성분의 입경분포 특성 : 제주도 고산지역의 2002년 봄철 (3.29-5.30) 측정 연구)

  • 한진석;문광주;류성윤;안준영;공부주;홍유덕;김영준
    • Journal of Korean Society for Atmospheric Environment
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    • v.20 no.4
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    • pp.555-569
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    • 2004
  • Size -segregated measurements of aerosol composition using 8-stage DRUM impactor are used to determine the transport of natural and anthropogenic aerosols at Gosan site from 29 March to 30 May in 2002. Separation of ambient aerosols by DRUM impactor offers many Advantages over other standard filtration techniques. Some of the most important advantages are the ability to segregate into details by particle tire, to better preserve chemical integrity since the air stream doesn't pars through the deposit, to collect samples as a function of time, and to have a wide variety of impaction surfaces available to match analytical needs. Although the transport of Yellow sand is a well-known phenomenon in springtime, the result of measurement shows that not only soil dust but also anthropogenic aerosols, including sulfur, enriched trace metals such as Pb, Ni, Zn. Cu, Cr, As, Se, Br, are transported to Gosan in springtime. This study combines the size- and time-resolved aerosol composition measurements with isentropic, backward air-mass trajectories in order to identify some potential source regions of anthropogenic aerosols. As a result, during the NYS period, the average concentration of PM$_{10}$ was 46$\mu\textrm{g}$/㎥, Si, Al. S, Fe, Cl, K, Ca were higher than 1,000 ng/㎥ and Ti was about 100 ng/㎥. The concentrations of Zn, Mn, Cu. Pb, Br, Rb, V, Cr, Ni. At, Se ranged between 1 and 70 ng/㎥. More than 50% typical soil elements, tuck as Al, Si, Fe, Cd. Ti, Cr, Cu, Br. were distributed in a coarse particle range(5.0-12${\mu}{\textrm}{m}$). In other hand, anthropogenic pollutants, luck as S, N, Vi, were mainly distributed in a fine particle range (0.09-0.56${\mu}{\textrm}{m}$). During the YS period, PM$_{10}$ increased about 8 times than NYS period, and main soil elements, such as Al, Si, S, K, V, Mn, Fe also doubled in coarse particle range (1.15-12${\mu}{\textrm}{m}$). But Zn, As, Pb, Cu and Se, which distributed in the time aerosols (0.09-0.56${\mu}{\textrm}{m}$), were on the same level with or decreased than NYS period. Finally. except the YS Period, coarse particles (2.5-12${\mu}{\textrm}{m}$) are inferred to be influenced by soil, coal combustion, waste incineration, ferrous and nonferrous sources through similar pathways with Yellow Sand. But fine particles have different sources, such as coal combustion, gasoline vehicle, biomass burning, oil or coal combustion, nonferrous and ferrous metal sources, which are transported from China, Korea peninsula and local sources.ces.

Integration of Space Syntax Theory and Logit Model for Walkability Evaluation in Urban Pedestrian Networks (도시 보행네트워크의 보행성 평가를 위한 공간구문론과 Logit 모형의 통합방안)

  • Kim, Jong Hyung;Lee, Mee Young
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.15 no.5
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    • pp.62-70
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    • 2016
  • Ensuring walkability in a city where pedestrians and vehicles coexist is an issue of critical importance. The relative relationship between vehicle transit and walkability improvements complicates the evaluation of walkability, which thus necessitates the formation of a quantitative standard by which a methodological measurement of walkability can be achieved inside the pedestrian network. Therefore, a model is determined whereby quantitative indices such as, but not limited to, experiences of accessibility, mobility, and convenience within the network are estimated. This research proposes the integration of space syntax theory and the logit path choice model in the evaluation of walkability. Space syntax theory assesses adequacy of the constructed pedestrian network through calculation of the link integration value, while the logit model estimates its safety, mobility, and accessibility using probability. The advantage of the integrated model hence lies in its ability to sufficiently reflect such evaluation measures as the integration value, mobility convenience, accessibility potential, and safety experienced by the demand in a quantitative manner through probability computation. In this research, the Dial Algorithm is used to arrive at a solution to the logit model. This process requires that the physical distance of the pedestrian network and the perceptive distance of space syntax theory be made equivalent. In this, the research makes use of network expansion to reflect wait times. The evaluation index calculated through the integrated model is reviewed and using the results of this sample network, the applicability of the model is assessed.

Research Suggestion for Disaster Prediction using Safety Report of Korea Government (안전신문고를 이용한 재난 예측 방법론 제안)

  • Lee, Jun;Shin, Jindong;Cho, Sangmyeong;Lee, Sanghwa
    • Journal of Korean Society of Disaster and Security
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    • v.12 no.4
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    • pp.15-26
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    • 2019
  • Anjunshinmungo (The safety e-report) has been in operation since 2014, and there are about 1 million cumulative reports by June 2019. This study analyzes the contents of more than 1 million safety newspapers reported at the present time of information age to determine how powerful and meaningful the people's voice and interest are. In particular, we are interested in forecasting ability. We wanted to check whether the report of the safety newspaper was related to possible disasters. To this end, the researchers received data reported in the safety newspaper as text and analyzed it by natural language analysis methodology. Based on this, the newspaper articles during the analysis of the safety newspaper were analyzed, and the correlation between the contents of the newspaper and the newspaper was analyzed. As a result, accidents occurred within a few months as the number of reports related to response and confirmation increased, and analyzing the contents of safety reports previously reported on social instability can be used to predict future disasters.

Developing a Structural Equation Model of Drivers' Preference on Route Diagrams of Variable Message Sign (구조방정식 모형을 이용한 도형식 가변안내표지판의 운전자 선호도 평가 모형 개발)

  • Kwon, Hye Ri;Kim, Byung Jong;Kim, Won Kyu;Yu, Su In
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.13 no.3
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    • pp.47-65
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    • 2014
  • VMS(Variable Message Sign) helps drivers to choose their path to destinations on roadways. Some types of VMS often provide traffic information with clearly visible and comprehensible graphical route diagrams. Currently many diagramed types of VMS are installed on urban arterial and highways. This type of VMS surely enhances drivers' ability to comprehend traffic route information while they are driving on the roadway. Nevertheless, some of them are presented with so much information and design elements and they sometimes lead to decline of drivers' comprehensible level for traffic information. Drivers would fail to decide their preferable route in this state of information overflow. The purpose of this paper is to develop a drivers preference model for effective design principle including size and height of displaying font, and the amount of information in the route diagram considering driving speed, sex and age of the driver. This model is developed using structural equation modeling techniques. This model considers driver's emotional factor and, human factor and design component of route diagram. To collect data, we built driving simulator which is able to replicate real driving condition. 72 people who participated in the simulation were selected considering gender and age. The developed model showed that the amount of information, and visibility are more influential factors to the drivers' preference of the route diagram on VMS than design elements such as the shape and the font of the diagram.

Evaluation of Absorption and Release, Survival Efficiency and Recovery Rate of Transport Medium according to the CLSI M40-A2 Standard (CLSI M40-A2 기준에 따른 수송배지의 흡수 및 배출, 생존 효율, 회수율 평가)

  • Ha, Sung-Il;Suk, Hyun-Soo;Shin, Jeong-Seob;Heo, Woong;Park, Kang-Gyun;Park, Yeon-Joon
    • Korean Journal of Clinical Laboratory Science
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    • v.51 no.2
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    • pp.164-170
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    • 2019
  • The absorption and release capacities, survival efficiency, and recovery rates of five kinds of transport media were evaluated based on the swab elution method (Quantitative) of CLSI (Clinical and Laboratory Standards Institute) M40-A2. Liquid media showed mostly better results than semi-solid media in the three evaluations. The flocked swabs had better ability to absorption and discharge bacteria than the standard swabs. The liquid medium (S4) had the best survival efficiency. Pneumococcal strains with poor growth had a higher survival efficiency and recovery rate in liquid media (S4, S5). The results of microbial recovery showed that S. pyogenes met all the CLSI standards in all media. S. pneumoniae was inadequate in the semi- solid media (S2, S3) and all the remaining media met the criteria. H. influenzae was unsuitable in semi-solid media (S1, S3) and met the criteria in semi-solid medium (S2) and liquid medium (S4, S5). The viability of the H. influenzae, pneumococcal strain causing respiratory disease, was poor in most media. Overgrowth of P. aeruginosa was observed at room temperature. The combination of liquid medium and flocked swab confirmed the best results in the three evaluation methods.

Suggestion of Evaluation Elements Based on ODD for Automated Vehicles Safety Verification : Case of K-City (자율주행자동차 안전성 검증을 위한 ODD 기반 평가요소 제시 : K-City를 중심으로)

  • Kim, Inyoung;Ko, Hangeom;Yun, Jae-Woong;Lee, Yoseph;Yun, Ilsoo
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.21 no.5
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    • pp.197-217
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    • 2022
  • As automated vehicle(AV) accidents continue to occur, the importance of safety verification to ensure the safety and reliability of automated driving system(ADS) is being emphasized. In order to encure safety and reliability, it is necessary to define an operational design domain(ODD) of the ADS and verify the safety of the ADS while evaluating its ability to respond in situations outside of the ODD. To this, international associations such as SAE, BSI, NHTSA, ISO, etc. stipulate ODD standards. However, in Korea, there is no standard for the ODD, so automated vehicles's ODD expression method and safety verification and evaluation are not properly conducted. Therefore, this study analyzed overseas ODD standards and selected suitable ODD for safety verification and evaluation, and presented evaluation elements for ADS safety verification and evaluation. In particular, evaluation elements were selected by analyzing the evaluation environment of the automated driving experimental city (K-City) that supports the development of ADS technology.

An Analysis of Road User Acceptance Factors for Fully Autonomous Vehicles : For Drivers and Pedestrians (완전 자율주행자동차에 대한 도로이용자 수용성 요인 분석 : 운전자 및 보행자를 대상으로)

  • Jeong, Mi-Kyeong;Choi, Mee-Sun
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.21 no.5
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    • pp.117-132
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    • 2022
  • The purpose of this study is to analyze factors that affect road users' acceptance of fully autonomous vehicles (level 4 or higher). A survey was done with drivers of general cars and pedestrians who share roads with fully autonomous vehicles. Five acceptability factors were selected: trust towards technology, compatibility, policy, perceived safety, and perceived usefulness. The effect on behavioral intention was analyzed using structural equation modeling (SEM). The perceived safety and trust towards technology were found to be very important in the acceptance of fully autonomous vehicles, regardless of the respondent, and policy was not influential. Compatibility and perceived usefulness were particularly influential factors for drivers. In order to improve the acceptance by road users, securing technical completeness of fully autonomous vehicles is important. Certification and evaluation of the safe driving ability of fully autonomous vehicles should be thoroughly performed, and based on the results, it is necessary to improve the perception by road users. It is necessary to positively recognize fully autonomous vehicles through education and publicity for road users and to support their smooth interaction.