• Korean Journal of Family Social Work
• /
• no.43
• /
• pp.61-85
• /
• 2014

The aim of this study is to examine how labour transition of female householders is proceeded, and to identify mechanisms that cause them to be excluded from labor market. For this, thirteen lone mothers who have had labor experience in the market, while raising children were interviewed. This qualitative case study was proceeded by way of participants' interviews and questionnaires. Finding shows, impoverished lone mothers were horizontally moving incessantly on second labor market. As poverty worsens by years, poor lone mothers tend to be more dependant on the government's support and to transit downward to work-poor labor market. The unprivileged women were excluded from multi-dimentions: market structure, social relations and gender norms. The sex-segmental and human capital-oriented market has excluded women who gave up their career for caring. Female breadwinners were frequently excluded from social relations and opportunities for labor due to their stigma. sometimes they were self-excluded from the market for they had to care for their children. In conclusion, suggestions are given to enhance qualities of lone mother's lives and help them exit from poverty. It is necessary to implement positive labor policy with labor flexibility and stability and to practice socialization of care as care support system is very important for maintaining their jobs. Above all, social awareness of gender role must be changed.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.39 no.5
• /
• pp.595-603
• /
• 2019

To alleviate the demand on private car that is constantly increasing, Busan Metropolitan City (BMC) has established Bus Rapid Transit (BRT) to revitalize public transportation. But there are no unified lane system between BRT and general bus stations, which makes off-lane turning general bus to contribute to congestion. And as the bottleneck phenomenon at entrance/exit accelerates the congestion, there has been huge dissatisfaction among commuting drivers. Therefore, this study identifies efficient methods to operate better through measuring civilian awareness. We evaluate both satisfaction and drawbacks on BRT service with Importance-Performance Analysis (IPA). We first distinguish the groups by the awareness on BRT and their main transit usage, and then clarify the difference between the groups. And as a result, the group who is positive to BRT and uses buses often demands improvement in bus indoor comfort and curbing jaywalking. On the other hand, group who is negative to BRT and uses private cars often demands improvement in lane changing and the moving speed of private cars. We next examines the groups with MDPREF, one method of Multidimensional Scaling (MDS). And we have clarified that the evaluating criteria and the individual attributes of the groups corresponds very well.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.4 no.4
• /
• pp.87-97
• /
• 2000

A steady state performance simulation and diagnostics program for the turboprop engine (PT6A-62), which is the power plant of the first developed military basic trainer KT-1 in Republic of Korea, was developed. The developed steady state performance analysis program was evaluated with the performance data provided by the engine manufacturer and with analysis results of GASTURB program, which is well known for the performance simulation of gas turbines. Performance parameters were discussed to evaluate validity of the developed program at various cases such as altitude, flight velocity and part load variation. GPA(Gas Pass Analysis) allows engine performance deterioration to be identified at the module level in terms of reduction in component efficiencies and changes in mass flow. In order to find optimal instrument set to detect the physical faults such as fouling, erosion and corrosion, a gas path analysis approach is utilized. This study was performed in two cases for selection of optimal measurement parameters. One case was considered with the effect of instrument number by changing independent parameter number. The other case was performed with selection of independent parameter set. According to the analysis results, the optimal measurement parameters selected were eight dependent variables such as shaft horsepower, fuel flow rate, compressor exit pressure and temperature, compressor turbine inlet pressure and temperature and power turbine inlet pressure and temperature.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2008.03a
• /
• pp.89-96
• /
• 2008

This paper investigates the effect of blade deformation, caused by manufacturing inaccuracies, on the performance of a 2-stage axial steam turbine. A high fidelity 3D coordinate Measurement Machine has been employed to obtain the exact geometrical model of the blades. A Streamline Curvature solver was used to predict the overall performance of the turbine. During the manufacturing process of the casts and of the blades themselves, several types of errors can occur which lead to a different geometry from that envisaged by the designer. The main objective of this study is to investigate the effect of those errors on the performance of a 2-stage experimental axial steam turbine. A high fidelity measurement of the actual geometry of both stator and rotor blades has been carried out, using a 3D Coordinate Measurement Machine. The cross sections of the blades obtained by the measurement were compared with those produced by the design process to evaluate the change in blade inlet/exit angles. In addition, the geometrical deviations from the initial design have been subjected to a statistical study in order to locate the nature of the error. The actual(measured) model has been used as input into a Streamline Curvature solver to evaluate its performance. Finally, a comparison with the performance plots of the original geometry has been carried out. A measurable change of efficiency as well as in the total power delivered by the turbine was found. This suggests that the accumulated error caused during the manufacturing procedure plays a significant role in the overall performance of the machine by making it less efficient by more than 1%. Reverse engineering techniques are proposed to predict and alleviate these errors leading thereby to a final design of each stage with improved performance.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2008.03a
• /
• pp.25-34
• /
• 2008

In this paper, three-dimensional multiblade row unsteady Navier-Stokes simulations at a hot streak temperature ratio of 2.0 have been performed to reveal the effects of rotor tip clearance on the inlet hot streak migration characteristics in low pressure stage of a Vaneless Counter-Rotating Turbine. The hot streak is circular in shape with a diameter equal to 25% of the high pressure turbine stator span. The hot streak center is located at 50% of the span and the leading edge of the high pressure turbine stator. The tip clearance size studied in this paper is 2.0mm(2.59% high pressure turbine rotor height, and 2.09% low pressure turbine rotor height). The numerical results show that the hot streak is not mixed out by the time it reaches the exit of high pressure turbine rotor. The separation of colder and hotter fluid is observed at the inlet of low pressure turbine rotor. Most of hotter fluid migrates towards the rotor pressure surface, and only little hotter fluid migrates to the rotor suction surface when it convects into the low pressure turbine rotor. And the hotter fluid migrated to the tip region of the high pressure turbine rotor impinges on the leading edge of the low pressure turbine rotor after it goes through the high pressure turbine rotor. The migration of the hotter fluid directly results in very high heat load at the leading edge of the low pressure turbine rotor. The migration characteristics of the hot streak in the low pressure turbine rotor are dominated by the combined effects of secondary flow and leakage flow at the tip clearance. The leakage flow trends to drive the hotter fluid towards the blade tip on the pressure surface and to the hub on the suction surface, even partial hotter fluid near the pressure surface is also driven to the rotor suction surface through the tip clearance. Compared with the case without rotor tip clearance, the heat load of the low pressure turbine rotor is intensified due to the effects of the leakage flow. And the numerical results also indicate that the leakage flow effect trends to increase the low pressure turbine rotor outlet temperature at the tip region.

• Nuclear Engineering and Technology
• /
• v.42 no.4
• /
• pp.382-393
• /
• 2010

Thermal mixing by steam jets in a pool is dominantly influenced by a turbulent water jet generated by the condensing steam jets, and the proper prediction of this turbulent jet behavior is critical for the pool mixing analysis. A turbulent jet flow induced by a steam jet discharged through a vertical upward single hole into a subcooled water pool was subjected to computational fluid dynamics (CFD) analysis. Based on the small-scale test data derived under a horizontal steam discharging condition, this analysis was performed to validate a CFD method of analysis previously developed for condensing jet-induced pool mixing phenomena. In previous validation work, the CFD results and the test data for a limited range of radial and axial directions were compared in terms of profiles of the turbulent jet velocity and temperature. Furthermore, the behavior of the turbulent jet induced by the steam jet through a horizontal single hole in a subcooled water pool failed to show the exact axisymmetric flow pattern with regards to an overall pool mixing, whereas the CFD analysis was done with an axisymmetric grid model. Therefore, another new small-scale test was conducted under a vertical upward steam discharging condition. The purpose of this test was to generate the velocity and temperature profiles of the turbulent jet by expanding the measurement ranges from the jet center to a location at about 5% of $U_m$ and 10 cm to 30 cm from the exit of the discharge nozzle. The results of the new CFD analysis show that the recommended CFD model of the high turbulent intensity of 40% for the turbulent jet and the fine mesh grid model can accurately predict the test results within an error rate of about 10%. In this work, the turbulent jet model, which is used to simply predict the temperature and velocity profiles along the axial and radial directions by means of the empirical correlations and Tollmien's theory was improved on the basis of the new test data. The results validate the CFD model of analysis. Furthermore, the turbulent jet model developed in this study can be used to analyze pool thermal mixing when an ellipsoidal steam jet is discharged under a high steam mass flux in a subcooled water pool.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.24 no.6
• /
• pp.745-756
• /
• 2022

The road tunnel is a semi-closed space that is blocked on all sides except the entrance and exit, and in the event of a fire, the smoke of the fire spreads longitudinally due to heat buoyancy caused by the fire and air currents that always exist in the tunnel. To solve this problem, smoke removal facilities are installed in road tunnels to secure a safe evacuation environment by controlling the direction of movement of smoke or directly smoking at fire points. In urban areas, the service level of urban roads decreases due to the increase in traffic due to the increase in population, and as a solution, the construction of underground roads in urban areas is increasing. When a fire occurs during hydrogen leakage through TPRD of a hydrogen fuel cell vehicle (FCEV), the fire intensity depends on the amount of leakage, and the maximum fire intensity depends on the orifice diameter of the TPRD. Considering the TPRD orifice diameter of 1.8 mm, this study analyzed the diffusion distance of fire smoke according to the wind speed of the roadway and the opening interval of the large exhaust port when the maximum fire intensity was 15 MW. As a result, it was analyzed that air flow in the tunnel could be controlled if the wind speed of the road in the tunnel was less than 1.25 m/s, and smoke could be controlled within 200 m from the fire if the damper interval was 50 m and 100 m.

• Korean journal of applied entomology
• /
• v.60 no.4
• /
• pp.479-487
• /
• 2021

This study investigated the life history of the plum sawfly Monocellicampa pruni Wei, 1998 through field observations and laboratory experiments. M. pruni is a univoltine, complete metamorphosis species with five instars at the larval stage. Adults emerge from the soil around mid-March when Japanese plum trees are in their flowering period. The adults deposit one (rarely two) egg(s) under the epidermis layer of the calyx. After hatching, the larva soon burrows into the fruitlet, consumes the endocarp and remains inside the fruit within its four-time moulting transitions before reaching full growth. At maturity (in May), the larva leaves the infested fruitlet through an exit hole and burrows into the soil at a depth of 2 - 11 cm for spinning its cocoon and hibernates until the next spring as the larval form. Under laboratory conditions (T = 20℃; RH = 40 - 60%), the male lived for a slightly shorter period than the female, 6.03 ± 0.40 and 7.55 ± 0.45 days, respectively. A female could produce 30.29 ± 4.50 eggs in her lifespan. In the field, the duration of the egg was approximately 10 - 11 days and that of the larva was approximately 31 - 34 days.

• Journal of the Korea Convergence Society
• /
• v.12 no.12
• /
• pp.315-322
• /
• 2021

This study analyzes the Required Safe Egress Time (RSET), in the event of a fire at a welfare center for the disabled, using the emergency passage according to the floor arrangement of users to evaluate the safety and the difference in RSET for each emergency passage using the Pathfinder simulation program to suggest an efficient evacuation method. As a result of RSET, it was found that there is no problem in evacuation safety for the current state of the facility's personnel allocation by satisfying the standard RSET in case of fire, and evacuation can be completed safely by evacuating through stairs rather than using elevators if possible. It is necessary for employees to be provided sufficient education and training in advance so that they can evacuate effectively with the disabled in case of fire. This study gives significance in saving many precious lives and safely evacuate in case of fire as evacuation routes were secured through the design, construction and operation of facilities for the disabled and the RSET was shortened through regular evacuation practices. It is necessary to discuss the further RSET studies based on the automatic fire shutters open or not when a fire occurs at a specific location following the installation of automatic fire shutter at the entrance of each floor of the facilities.

• Journal of Digital Convergence
• /
• v.19 no.9
• /
• pp.125-133
• /
• 2021

This study investigated to explore the broadened concept of the subscription service market and categorize of the subscription market and its consumer behavior. We examined the satisfaction of the service users and the reasons for terminating the subscription. Survey respondents were 443 people in their 20s and 30s, who actively use subscription services. As a result of the survey it was found that users in their 20s were more satisfied with the overall subscription service than those in their 30s, and that user's residential areas were evenly distributed regardless of metropolitan area or non-metropolitan area. As a reason for the cancellation of subscription service: the lower the novelty of subscription, the less personalization tailored to consumer, the lack of feeling self-growth while using the service, and the more termination is made. Our findings have magnified the understanding of consumers behaviors in the age of 20s and 30s of using and terminating subscription service and hopefully be used for future studies of subscription services.