• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.19 no.3
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• pp.38-51
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• 2020

A bottleneck and congestion occur when a freeway is closed due to maintenance and construction activities on the freeway. Although various traffic managements have been developed to improve the traffic efficiency at freeway work zones, such as merge control, there is a limit to those controls with human drivers. On the other hand, the wireless communication of connected and automated vehicles (CAVs) enables the operation of advanced traffic management. This study developed a traffic control strategy that integrates Dynamic Merge Control (DMC) and Lane Change Control (LCC) in a CAV environment. DMC operates as an either early or late merge based on the occupancy rate of upstream of the work zone. The LCC algorithm determines the number of vehicles that need to change their lane to balance the traffic volume on open lanes. The simulation results showed that integrated control improves the cumulative vehicle count, average speed upstream, and average network travel time.

• Journal of Korean Society of Transportation
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• v.31 no.5
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• pp.3-15
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• 2013

The purpose of this study is to propose a methodology for operating variable speed limit (VSL) strategies in freeway work zones. A notable feature in this study is to incorporate a multi-criteria decision making process into deriving better VSL strategies. Decision criteria in this study include operational efficiency, safety, and environmental impacts. Travel speed, acceleration noise, and CO2 were used as performance measures for evaluating VSL strategies. A multi-criteria value function was developed through an analytical hierarchical process (AHP) for representing expert's knowledge. Then, a variety of VSL operations scenarios were investigated utilizing a microscopic traffic simulation suite, VISSIM. The proposed methodology would be useful in supporting more efficient, safer, and more environment-friendly traffic operations and control in freeway work zones.

• Journal of the Korean Geotechnical Society
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• v.22 no.11
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• pp.13-23
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• 2006

The sinkhole and leakage in dam core were detected at one of earth fill dams in Korea. The damage areas in the core of the dam were repaired by compaction grouting method. This study is to evaluate compaction grouting activity by in-situ and laboratory experiments before, during and after the remedial work. The intensive site investigation and geophysical survey were conducted during and after the compaction grouting work. The compaction grouting work was carried out for the damaged dam core between June 16 and August 24, 2000. The leakage reduction generally occurred in the core of the dam after the remedial work. The use of compaction grouting was considered the proper countermeasures for repairing the damaged dam. It shows that the loose or voided zones have been properly filled and the leakage has been reduced by about 96% of that before the treatment of the remedial work performed at dam core by compaction grouting.

• Journal of Korean Society for Atmospheric Environment
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• v.18 no.5
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• pp.401-410
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• 2002

Concerns for energy conservation, environmental pollution, and the fact that organic wastes account for a major portion of our waste materials, have created the interest of biogas, which usually contains about 60 to 70 percent methane, 30 to 40 percent carbon dioxide, and other gases, including ammonia, hydrogen sulfide, mercaptans and other noxious gases. Cyclone combustors are used for homing a wide range of fuels such as low calorific value gas, waste water, sludge. coal, etc. The 3-dimensional swirling flow, combustion and emission in a tangential inlet cyclone incinerator under different inlet conditions are simulated using a standard k-s turbulence model and ESCRS (Extended Simple Chemically-Reacting System) model. The commercial code Phoenics Ver.3.4 was used for the present work. The main parameters considered in this work are inlet velocity and air to fuel ratio. The results showed that the change of operating conditions had an influence on the shape and size of recirculation zones, mixture fraction and axial velocity which are important factors for combustion efficiency and emission behavior. The application of this kind of computer program seams to be promising as a potential tool for the optimum design of a cyclone combustor with low emission.

• Journal of the Society of Naval Architects of Korea
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• v.50 no.2
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• pp.88-94
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• 2013

The primary objective of the current work is to obviously analyze regarding effects of trim conditions of a ship on resistance performance using model test and CFD. Model tests at a towing tank are conducted to investigate resistance for trim conditions at the given same displacement. Measured resistance shows small but distinct differences according to trim conditions. However, these differences are difficult to be clarified by measured physical quantities and wave pattern analysis from model tests. CFD is employed for the assessment of resistance performance according to trim conditions. The flow computation is conducted considering free surface and dynamic trim using a commercial CFD code (STAR-CCM+). The initiative of the present work is to systematically demonstrate pressure resistance acting on each region of divided finite zones of ship surface along the length and draught direction of surface when pressure distribution on the ship is interpreted. Also, a standard to assess the pressure resistance applied on the divided regions of a ship is established.

• Safety and Health at Work
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• v.9 no.3
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• pp.352-355
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• 2018

Hazardous work zones (i.e., hot, warm, and cold) are typically established by emergency response teams during hazardous materials (HAZMAT) calls but less consistently for fire responses to segment personnel and response activities in the immediate geographic area around the fire. Despite national guidelines, studies have documented the inconsistent use of respiratory protective equipment by firefighters at the fire scene. In this case-series report, we describe warm zone gas levels using multigas detectors across five independent fire incident responses all occurring in a large South Florida fire department. Multigas detector data collected at each fire response indicate the presence of sustained levels of volatile organic compounds in the "warm zone" of each fire event. These cases suggest that firefighters should not only implement strategies for multigas detector use within the warm zone but also include respiratory protection to provide adequate safety from toxic exposures in the warm zone.

• Journal of Korean Society of Transportation
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• v.31 no.4
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• pp.58-66
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• 2013

Due to the characteristics of urban freeways such as heavy traffic and high speed, work zone on urban freeways causes the increase of not only the likelihood of crash occurrence but also traffic congestion caused by lane drop, lane change, acceleration/deceleration, and etc. This paper aims to determine the proper length of transition area that satisfies two criteria, mobility and safety, to make the operation of work zone more efficient. For the analysis, three different scenarios were developed by the number of lanes and the proper length of transition area were determined by changing the length from 100m to 500m in 100m increments. The results showed that the proper length of transition area for 3- and 4-lane freeways is 300m, whereas the proper length of 2-lane freeways is 200m. The results indicated that the different length of transition area based on the number of lanes is more desirable and efficient.

• Korean Journal of Materials Research
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• v.3 no.1
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• pp.58-64
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• 1993

The degree of work hardening in the subsurface zones varied with the experimental conditions under the rolling contact fatigue wear test of high carbon Cr-Ti alloy steel was evaluated by the distribution of residual stresses. Surface residual stresses before the test did not affect the wear property. Surface residual stresses after the test decreased by the increase of contact stress and running. velocity. but the maximum compressive residual stress and its depth of saturation in the subsurface zone increased. The relationship between these experimental results and the distribution of the theoritical shear stress was also discussed.

• Journal of the Korean Society of Combustion
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• v.18 no.1
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• pp.7-12
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• 2013

A quasidimensional program is developed for a four stroke cycle homogeneous GDI (Gasoline Direct Injection) engine. It includes models for spray, burning rate and chemistry to predict knock and emissions. With early injection a homogeneous GDI engine goes through spark ignited, turbulent premixed combustion as in PFI (Port Fuel Injection) engines. The cylinder charge is divided into unburned and burned zone with the latter divided into multiple zones of equal mass to resolve temperature stratification. Validation is performed against measured pressure traces, NOx and CO emissions at different load and RPM conditions. Comparison is made between an empirical knock model and predictions by the chemistry model in this work.

• Korean Institute of Interior Design Journal
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• no.1
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• pp.52-55
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• 1992

The purpose of this study was to suggest the spatial structure among residential behaviors in relation to work space. To find the structure, Multi-Dimensional Scaling analysis was used. Respondents were 349 middle income housewives living in apartments in the area of Caopital region. Data were collected through the questinnaire survey. For the future residential interior design, following points were sugtested. A laundary space neess to be developed independently , being separated from both bathroom and kitchen/dining space. A new area which will give housewives some territoriality and also function as home office needs to be considered. A space configuration which satisfies the organic relationships among laundary behaviors such as washing dying, ironing and folding , needs to be systematically planned, with two adjoining separate zones of wet and dry utility . The present bathroom nees to be more incorporated to the private bedroom rather than to workspace.