• Journal of Korean Society of Transportation
• /
• v.14 no.4
• /
• pp.91-106
• /
• 1996

This paper deals with on the efficiency questions of the left-turn prohibit at an isolated intersection and a corridor with 5-phase signal system. Its objectives are three-fold ; (1) to analyze the efficiency of the left-turn prohibit with the use of an imaginary network, (2) to evaluate various factors under consideration in decision making on the left-turn prohibit, (3) to provide a framework for estimating and evaluating overall impacts of the left-turn prohibit in traffic network. the major findings using an imaginary network and computer packages such as MINUTP, TRANSYT-7F and STATGRAPH are followings. First, left-turn prohibit reduces cycle length by 33 seconds and delay time per vehicle by 36 seconds at an isolated intersection, and cycle length by 31 seconds and delay time per veicle by 43 seconds along a corridor. Second, total vehicle mile of travel and total travel time at an isolated intersection seem up to increase 38.85 miles(57.36km), 14.4 hour on the average, Regarding to a corridor, total vehicle mile of travel is increased by 50.14 miles(80.22km), but total travel time is decreased by129.9 hours. Third, the efficiency of left-turn prohibit are affected the following eight factors including left-turn volume(veh/hr) and ratio(%), average delay time per vehicle(sec/veh) and others. Finally, several simple and multiple regression models to evaluate the impacts on the left-turn prohibit are formulated from the above eight factors. It can be expected that these models will take an important role in decision-making of left-turn prohibit.

• The Korea Journal of Herbology
• /
• v.35 no.5
• /
• pp.23-31
• /
• 2020

Objectives : This study was conducted to evaluate the anti-hyperlipidemia effect of Scutellariae Radix, Aucklandiae Radix and Bupleuri Radix(SAB). Methods : FL83B cells were mouse liver hepatocytes, and we used this cell line. FL83B cells were treated with 0.5 mM oleic acid(OA) for 24 h, SAB extract was treated. After OA treatment, intracellular triglyceride (TG) and free fatty acid contents were measured with AdiopoRed™ assay and Free Fatty Acid Quantitation assay kit, respectively. Further, we evaluated several lipogenesis and metabolic markers such as sterol regulatory element-binding transcription factor-1c (SREBP-1c), acetyl-CoA carboxylase (ACC), fatty acid synthase (FAS), 3-hydroxy3-methyl-glutaryl CoA reductase (HMGCR), hormone-sensitive lipase (HSL), carnitine palmitoyltransferase (CPT-1), peroxisome proliferator activated receptor alpha (PPARα), and cluster of differentiation (CD36) using RT-PCR and Western-blot analysis. Results : OA markedly increased intracellular TG and free fatty acid, which plays a key role in reducing hepatic lipid accumulation, in FL83B cells. These increases were alleviated by SAB extract. The mRNA and protein expression of Fatty acid(FA) oxidation factors (CPT-1, PPARα), lipolysis factor(HSL), FA transporter(CD36), cholesterol synthesis factors (HMGCoA) and Lipodenesis (SREBP-1c, FAS, and ACC-1) were significantly increased by treatment of SAB extract in the OA-induced fatty liver cell model. Conclusions : In summary, the treat of SAB extract showed a significant reduction of the influx of fatty acids into hepatocytes, promoted the oxidation of fatty acids, and regulated fat synthesis-related factors, thereby regulating the accumulation of TG and free fatty acids.

• Journal of Korean Society of Transportation
• /
• v.28 no.5
• /
• pp.77-87
• /
• 2010

In the last five years, Korea has supplied many more bicycle facilities than in the last several decades combined. However, have bicyclists increased in proportion to investment? If bicyclists are avoiding existing bicycle related facilities, including off-road bicycle facilities, it could be because suppliers did not consider bicyclists' preferences in their planning process. In this paper, the authors tried to understand the bicyclists' behavioral and route choice characteristics using stated preference surveys and a logit model, using commuting time in Daejeon Metropolitan City, Korea. The results show that nine factors affect the route choice behavior of bicyclists. In particular, bicyclists preferred sub-arterial roads to off-road, dedicated bicycle facilities in residential area. It means that bicyclists like a seamless bicycle route and that a buffer zone between car lanes and bicycle lanes or 50 km/h speed limits for cars are necessary for bicycle lanes that are not physical separated.

• Smart Media Journal
• /
• v.7 no.4
• /
• pp.44-51
• /
• 2018

The purpose of this research is to collect atmospheric environmental information at specific altitudes in a range of 0 to 1 km above the surface and to monitor it using drones. The corresponding temperature and humidity were measured with the meteorological factors, and the amounts of fine dust and $CO_2$ were observed by the environmental factors so that they could receive the normal values. Monitoring the status of atmospheric gas emission in specific enterprises, industrial complexes and regions through the measurement is meant to help establish policies to reduce pollution factors. In conventional means previously practiced, exhaust gas detection accompanies a great deal of risks in terms of safety because the surveyor is directly exposed to the source of contamination such as the holes installed in the chimney. However, in our proposed method, the drone can collect information in a wide range under safe circumstances, which can be utilized through wide industrial areas.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.29 no.6D
• /
• pp.685-691
• /
• 2009

The purpose of this paper is to classify the traffic condition in freeway by the impacts of road weather. The factor analysis showed that weather factors, which are considered as influential, are identified as weather condition (rain or clear), temperature and sight distance with RWIS and VDS data in Seohae bridge used. The result of ANOVA shows that weather is dividedinto clear and rainy; temperature into below and equal or above $5^{\circ}C$ and sight distance into below or equal or above 10km. Based on those factors, the freeway traffic condition has been classified as five different types. The flow-speed model for each traffic conditions was proposed, which was not significant due to the lack of smaple data. Although not sufficient, the methodology to categorize traffic situation model presented in this paper may shed light on the idea for the future and can be used for proper traffic management for each weather condition.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.32 no.6D
• /
• pp.549-556
• /
• 2012

Longitudinal tunnels are defined as tunnels with length of over 1km. Because of Korea's topographical conditions and as safety measures for linear design, many tunnels are inevitably being constructed in Korea. The number of longitudinal tunnels constructed on expressways amounted to 104 as of the end of 2010 with a total length of 192km. Given the increasing demand for tunnels and the increasing length of tunnels, a safety evaluation of longitudinal tunnels needs to be conducted. As such, this study selected design elements, transportation environment and delineation system as elements to check and tried to determine factors influencing road crashes. For this, tunnels have been classified based on history of crashes; ones with crashes and ones without crashes and statistically meaningful explanatory variables were selected. By using these variables, a logit model was development in order to better grasp the factors that directly and strongly influence crashes. The result, related to crashes as well as the analysis were utility tunnel interior materials of driving lane and passing lane, which are related to driver's visibility, lateral width widening to consolidate space in a tunnel, and annual average daily traffic (AADT) per lane. These results may be used in the future as analysis indicators when drawing up plans to prevent crashes in longitudinal tunnels.

• Journal of Korean Society of Transportation
• /
• v.19 no.6
• /
• pp.89-102
• /
• 2001

Using a multiproduct translog cost function model, this paper examines the existence or absence of scale and scope economies in Seoul's urban bus industry. The Paper then conceptualizes that the bus firm produces three outputs (city, seat and local bus-kilometers) using low input factors(labor, capital, fuel and maintenance). Using 1996 annual observations for 81 Seoul's bus firms, the equation system consisting of a cost function and three input share equations is estimated with the nonlinear iterative Zellner method. The findings show that the cost function corresponding to a non-homothetic production technology with separability between local bus outputs and inputs adequately represents the structure of cost for Seoul's bus firms, and that the demand lot all input factors is quite inelastic with respect to their own price. On the other hand, nearly all firms experience mild overall economies or scale, but rather marked product-specific economies of scale with respect to all the three outputs. In addition, there appear to be substantial economies or scope associated with the joint production of city and seat bus services, while considerable diseconomies of scope associated with that of city and local bus services. These results indicate that the merger of smaller firms into larger firms with a fleet of approximately 200 buses would result in more cost-efficient bus services.

• Korean Journal of Environment and Ecology
• /
• v.34 no.3
• /
• pp.191-197
• /
• 2020

The purpose of this was to examine the differences of large whopper swan (Cygnus cygnus) in wintering habitat preference among bridge sections of the lower Nakdong River of the Nakdong River Estuary, the largest whopper swan's wintering habitat in Korea. This species is designated and protected as Natural Monument in Korea. The survey was conducted in six time-series during the 2018~2019 wintering season, and it found up to 500 whopper swans were wintering in the lower Nakdong River. For the survey, a seven sections were set up based on the bridges across the river. Whopper swans were rarely observed in five narrow sections where the distance between bridges was less than 2 km. The stable population of the whopper swan was observed only in two broader sections where the distance between bridges was is over 4 km. As these sections were relatively little affected by artificial interference, the distance from the mouth of the Nakdong River was not a factor. Securing a stable space is considered as one of the most important factors for wintering of whopper swans, which are an endangered species. The survey results indicate that the distance between bridges should be at least 4 km to secure the whopper swan's stable habitat. These results are expected to be a reference to the development or restoration of the river ecosystems, especially bridge construction.

• The Journal of the Korea Contents Association
• /
• v.11 no.6
• /
• pp.486-494
• /
• 2011

River bed change due to various factors in watershed and/or river environment would one of the most important issues in river management. To judge whether the river bed was aggrading or degrading, normally we use the change in thalweg or average bed, calculated using the design flood of the river. The present study is to figure out the problems of the existing methods and to propose a new concept of average river bed using annual maximum flood. To evaluate the new method, it was applied to the Nakdong River. We use the river bed data surveyed in 1983, 1993, and 2005. The results showed that there were no significant river bed change during 1983 and 1993, while the river bed was degraded significantly during 1993 and 2005. In the latter period, the river had severe degradations, 2~3 m in average sense and 5 m for the maximum in the middle reach(120~200 km from river mouth), and 1~2 m in average in the upper reach(200~240 km from river mouth). For the upstream reach of the confluence of the Naesung River(about 240 km from river mouth), most of the river bed change seemed to be only local phenomena. The main cause of the river bed change in the Nakdong River seems to be massive gravel mining in the middle reach of the river.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.31 no.3A
• /
• pp.163-172
• /
• 2011

The CFTA girder developed is a concrete filled steel tubular system with arched shape and external post-tensioning (PT) tendons which control the initial camber and the bending stress of the girder. In the present study the effects of the PT tendons on the dynamic behavior of the girder subjected to a moving vehicle load are numerically investigated. Various levels for the tendon quantity and the tendon forces are considered, using the existing FE model of the girder. The vehicle considered is a DB-24 truck and is modeled with two tracks-three axles. Equivalent-load pulse time histories are applied to each node to simulate the moving vehicle, depending on the time of arrival and the discretization. The vehicle speeds are varied from 40 km/hr to 100 km/hr with increment of 20 km/hr. The analysis results show that the tendon forces do not produce any influences on the dynamic responses of the girder. However the dymamic deflection of the girder increases when a smaller amount of tendons is used. The Dynamic Amplification Factors (DAF) are evaluated based on the static and dynamic responses. Much lower values of the DAF are obtained, even no tendons applied, than those provided by the design criteria of the AASHTO LRFD and the Korea Highway Standard Specification.