• Atmosphere
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• v.34 no.2
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• pp.139-151
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• 2024

The Yeongdong region has suffered from severe snowstorms and the relevant damage such as traffic accidents on slippery roads, and the collapse of greenhouses and temporary buildings. While a lot of research on snowfall has been conducted, the detailed study of snow crystals' phase and habit through intensive observations and the relevant microphysical analysis is still lacking. Therefore, a snowflake camera, PARSIVEL, and intensive radiosonde soundings were utilized to investigate phase and habit changes in solid precipitation. Two remarkable episodes of phase and habit changes were selected such as 19 March 2022 and 15 February 2023. Both events occurred in the synoptic condition of the High in the north and the Low passing by the south, which was accompanied by rapid temperature cooling below 2.5 km. During the events of a short period between 3 to 6 hours, the temperature at 850 hPa decreased by about 4 to 6℃. This cooling led to a change in the main habit of snow particles from riming to aggregate, identified with both MASC and PARSIVEL. Meanwhile, the LDAPS model analyses do not successively represent the rapid cooling and short-term variations of solid precipitation, probably by virtue of overestimating low-level equivalent potential temperature during these periods. The underlying causes of these the low-level temperature variations within 6 hours, still remain unclear. It might be associated with mesoscale orographic phenomenon due to the mountains and East Sea effects, which certainly needs an intensive and comprehensive observation campaign.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.2D
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• pp.167-173
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• 2009

In general, an influenced area of merging section is defined as 500 m including 100 m upstream and 400 m downstream. However, from an observation of the actual traffic flow, it is found that merging effect influences more on downstream than upstream. In this study, an influenced area of merging section on freeway is analyzed by using turbulence which is defined as conflicts between vehicles. In order to overcome the limits of existing traffic flow detection system established with intervals of about 500 m, this study uses raw data collected from the detectors which are established in entrance ramps with similar road conditions. To divide data of each point into similar road conditions, the data of total 72 hours is sorted by Level of Service. An influenced area analyzed by standard deviation of speed is 700 m section of highway, including 300 m upstream and 400 m downstream, for both right and left ramps. It is the result including upstream 200 m more than previous studies.

• Korean Journal of Construction Engineering and Management
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• v.17 no.5
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• pp.120-129
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• 2016

The user cost is an important analysis item which should be considered together with life-cycle of facility, administrator cost and discount rate in LCCA for efficient asset management of SOC facilities. Especially, a significant delay cost occurs often for users in the road field due to a work zone for cleaning and maintenance, and in such case, the administrator should consider the administrator cost as well as the user cost for more rational decision making. However, the user cost has not been considered in most decision making steps until recently and relevant studies also have not been carried out actively. In this study, the methodology to estimate the user cost and delay cost required in the decision making step using the traffic flow model and the direct benefit estimation model in the traffic facility investment evaluation guideline is suggested. And, the traffic flow model was estimated on 4 national highway sections where maintenance was actually carried out in 2014 using VISSIM and, the user cost and the delay cost were estimated based on the suggested methodology. The analysis result showed that the average user cost of $17,569,000KRW/km{\times}day$ occurred on Section A with approximately 30,000 AADT before a work zone occurred, and in case the first lane was blocked for maintenance, the delay cost of $10,193,000KRW/km{\times}day$ (158%) on average occurred additionally. The delay cost of $1,507,000KRW/km{\times}day$ (115%) and $1,985,000KRW/km{\times}day$ (119%) occurred on Sections B and D with approximately 20,000 AADT respectively and the delay cost of $262,000KRW/km{\times}day$ (105%) occurred on Section C with approximately 10,000 AADT. This result of this study was estimated based on the simulation of traffic flow model so that there is a limitation in its actual application. A study ot develop a highly appropriate model using actual observation data and improve the possibility to apply it through the verification using the simulation will be necessary in future.

• International Journal of Highway Engineering
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• v.14 no.4
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• pp.1-8
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• 2012

PURPOSES : Skid resistance on pavements plays an important role in reducing the risk of vehicle skidding on wet surface particularly. Almost 9.3 percent of traffic accidents were occurred under rainy condition and these are over-represented in terms of the severity of the crashes. Recently, unusual weather conditions referred widely as the intensified rainfalls justify the need of a systematic management of skid resistance. In this context, the study carried out the observational study on the skid resistance characteristics of different types of pavement with the time passage. METHODS : This study measured the skid resistance with Pavement Friction Tester at three times within five years. The skid resistance measurement has followed the method suggested by ASTM. RESULTS : As the main results under the scope of this study, skid resistance of asphalt concrete has not nearly reduced with time. On the contrary, skid resistance of cement concrete has been rapidly reduced with time though the highest resistance was gained at the early observation. Porous asphalt concrete shows a steady decrease of skid resistance with time, anyway, the reduction rate according to the increase of measurement speeds is relatively lower than the others. CONCLUSIONS : Based on our study, skid resistance of the pavement should be regarded as one of the pavement management system, so periodic measurement should be made to assure road safety as a whole.

• Journal of Korean Society of Transportation
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• v.26 no.2
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• pp.101-107
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• 2008

Traffic speed data may be missed due to detector malfunction or network problems. In this paper we have proposed effective methods to estimate the data which could not be collected through loop detectors. Our proposed algorithm has three steps. First step is to find the most similar neighbor data record by coefficient of correlation. Second step is to make some data records which is calculated by the 5 kinds of estimation methods. Third step is to compare the data records with history data record of observation link and thus the best method is selected. The proposed method is useful for estimating travel time.

• Structural Engineering and Mechanics
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• v.26 no.2
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• pp.111-126
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• 2007

Dynamic responses of the bridge for a straddle-type monorail subjected to the ground motion of high probability to occur are investigated by means of a three-dimensional traffic-induced vibration analysis to clarify the effect of a train's dynamic system on seismic responses of a monorail bridge. A 15DOFs model is assumed for a car in the monorail train. The validity of developed equations of motion for a monorail train-bridge interaction system is verified by comparison with the field-test data. The inertia effect due to a ground motion is combined with the monorail train-bridge interaction system to investigate the seismic response of the monorail bridge under a moving train. An interesting result is that the dynamic system of the train on monorail bridges can act as a damper during earthquakes. The observation of numerical results also points out that the damper effect due to the dynamic system of the monorail train tends to decrease with increasing speed of the train.

• Journal of Veterinary Clinics
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• v.26 no.1
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• pp.72-75
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• 2009

Pulmonary bullae are air-filled spaces within the lung parenchyma that result from the destruction, dilatation and confluence of adjacent alveoli. Pulmonary bullae are found most often in healthy, middle aged, large breed or deep-chested dogs that have no previous history of lung disease and bulla may occur as a result of emphysema, inflammation or trauma. Clinical signs include respiratory distress, anorexia, depression and tachypnea. In this study, a dog with respiratory distress by traffic accident was diagnosed as pulmonary bullae with pneumothorax using radiography at Veterinary Medical Teaching Hospital, GNU. In radiographs, various sized, smooth margin, well defined, oval shaped, gas or fluid filled multiple bullae are shown in the left cranial, left caudal and right accessory lobes. At the initial stage of observation, there were indications of four bullae, two of which were not found in the following radiograph. At the same time, there were serious indications of lung consolidation that caused respiratory distress of patient. Ultimately, the patient was expired after ten hours.

• Journal of Chest Surgery
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• v.7 no.1
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• pp.23-30
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• 1974

During the 35 month period from November 1966 to November 1967 and from June 1971 to March 1973 I had experienced 127 cases of non fatal wounds of chest in Viet-Nam. .Among these 127 cases, 62[45.4%] were gun shot wounds, 49[35.8%] were shrapnel wounds and the other were traffic accident. stab wounds and miscellanous. Approximately 21% of gun shot wound were perforating and 79% were penetrating but all cases of shrapnel wounds were penetrating. Of these 127 cases. 90% evacuated to hospital within 6 hours and average time 2.5 hours. The tranfusion requirement of these cases ranged from zero to 36 pints of whole blood with an average of 2.600cc. Initial intrathoracic findings were hemopneumothorax and hemothorax mostly. and the incidence of open thoracotomy was 9.5%[12cases] and closed thoracotomy was 82.8%[104cases], which were contrast to the reports from Korean conflict. I had experienced 24 cases with complication, such as large hematoma in lung parenchyme[8 cases], atelectasis[4 cases], pyothorax [3 cases], pneumonia [3 cases], fibrothorax [3 cases], pleural effusion [2 cases] and wound infection [2 cases]. Mortality rate for entire group was 4.7% but the cases associated with brain injury was 100%, with spinal cord injury was 50%, with large vessel 50%, and abdominal injury was 33.3%, and nobody died solely of thoracic injury.

• Journal of Environmental Science International
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• v.19 no.3
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• pp.313-321
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• 2010

This study was carried out to investigate the emissions of the air pollutants from the automobile in Suwon city. To estimate emissions due to by automobile the data of express highway and the national road used an observation traffic volume, and the other roads used a method by Vehicle kilometer traveled(VKT). In the emissions due to by automobile from Suwon city, CO was highest 36,290.4 ton/year, NOx at 19,392.1 tons, HC 5,095.4 tons and PM 2,788.7 tons was highly order. SOx emissions in the whole Suwon city by fuel types was investigated with 178ton/year from the Diesel motorcar, 26.9 ton/year and 6.2 ton/year from the gasolines and LPG automobiles, respectively. VOC emissions from the automobile was investigated with 366.4 ton/year (29.22%) from Gwonseon-gu, 329.2 ton/year (26.25%) Yeongtong-gu, 319.9 ton/year (25.51%) Jangan-gu, 238.6 ton/year (19.03%) Paldal-gu.

• Journal of Environmental Science International
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• v.17 no.8
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• pp.871-878
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• 2008

In this study, we measured volatile organic compounds in Gimhae city, South Korea. We selected twenty site and measured volatile organic compounds in ambient air by passive sampler when at sampling intervals of two month from April to December 2005. Passive sampler was exposed for fifteen day in ambient air. And samples were analyzed by GC/FID for volatile organic compounds. The results of each measured functional zone, mean concentration of each compound measured were generally higher the industrial complex area and traffic pollution area than residental area. Each area showed similar pattern for the observation period. concentration of measured each compound were the following order: winter > fall > spring > summer.