• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.4
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• pp.353-360
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• 2015

Commercial drivers feel tired more than the general public, because their driving times are long and they experience more idle vibration. In this study, we developed a nonlinear model of a magnetic, linear spring seat suspension to determine the optimal design to improve ride comfort. The resonant frequency for the optimal design of the suspension was found to be 3.5 Hz, and the stiffness was analyzed through displacement-load experiments. Additionally, the vibration transmissibility was analyzed by the suspension stiffness, and the existing coil spring type vibration transmissibility was found to be 0.99. A parallelogram type magnetic spring was determined to result in a better performance than the existing spring with a vibration transmissibility of 0.823.

• Journal of the Korean Society of Industry Convergence
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• v.12 no.2
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• pp.107-112
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• 2009

The effective reinforcement methods of structure is required to improve the durability of existing structures. Recently, the continuous fiber sheets to the concrete structures are widely used in the earthquake-proof reinforcement method. This study examines suitability and effect to concrete structure of fiber by FEM analysis. The result of analysis is as follows; All specimens occurred bending tensile failure at the middle span. Ultimate strength of specimen in the RC and reinforced RC specimen were 53.9 kN, 56.3 kN respectively and it was some low by degree 0.89, 0.82 to compare with calculated result. The deflection of specimen at the middle span occurred in approximately 0.2 mm, and did linear behavior in load 20 kN by seat reinforcement. Stiffness did not decrease by occurrence in the finer crack and reinforcement beam's flexure stiffness was increased until reach in failure. To compare calculated value and analysis value, it almost equal behavior in the elastic reign and can confirm effectiveness of analysis. Crack was distributed uniformly by reinforcement of fiber seat at failure and it do not occurred stiffness decreases.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.3
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• pp.437-443
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• 1987

An optimal design to improve the ride quality was performed with the time and frequency domain analysis based on both of deterministic and random road profiles. The objective function is established to minimize the absorbed power while the constraints are taken so as to satisfy the condition for the stability of vehicle. The result of the optimal design shows that the rms for the acceleration of a driver and his seat is within the critical values for the ride quality from ISO. The optimal values obtained show that the maximum absolute acceleration of the driver and his seat has significantly been reduced and the reference limits on the relative displacement have satisfied their feasibility. As the optimal value according to a specific speed is the results from the optimization process, a global optimum value should be determined to be the one which gives th minimum values of total sum of absorbed power with respect to various speed.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.758-762
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• 2007

Revenue management is a new approach method to solve the problem of supply and demand, and one of fields which is diffused quickly at the service enterprise to use perishable-asset like the transportation business. It is based on multiple fare policy that discount charge reservation should be received if the benefit value of current discount fare is more than expected profit of the normal fare reservation it will be able to occur in future when suitable goods is sold to the customers at discount fare, at the time they want, and at assigned seat by controlling supply and demand from market. In this research, I will review on initial operation case for special class goods that the seat which is limited is assigned at some of train and portion of KTX for demand dispersion and new demand creation at peak time, put a limit in purchase conditions, and provides discounted fare. I will also try to find implication for strategic operation.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.1447-1457
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• 2008

The operation of the Seat-type Express Electric railway (SEE) has been watched for an alternative plan according to the increase of competition among the vehicle in metropolitan city. The purpose of this study was to examine a feasibility for the adoption of the SEE by analysis of various condition in the double tracked Souel-Chuncheon line. Fare estimate, station selection for SEE, managerial plan, demanding forecasting and analysis were performed to compute financial efficiency. The results showed financial validity on Revenue Cost Ratio (R/C), Financial Net Present Value (FNPV), Financial Internal Rate of Return (FIRR). This results indicate the evidence that SEE is a new means which is able to complement for finance, transportation capacity in metropolitan city.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.8
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• pp.200-207
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• 2016

The automotive seat is an important component that moves in sync with the driver and is actively being developed with various new functions. The aim of this work is to develop a lightweight seat cushion extension module using a lightweight material. To this end, a structural strength analysis, vertical strength test, and durability test were conducted. In the structural analysis, the maximum value of deformation under vertical load was 4.98 mm at the front of the upper panel. The maximum stress was approximately 105 MPa, which occurred at the point of contact between the upper and lower panels of the module. The vertical strength test showed a maximum vertical deformation of 5.31 mm under a vertical load, which differed from the analysis results by approximately 6.45%. The structural safety of the product was verified by the fact that it showed no harmful deformation or damage during operation after the vertical strength test and a durability test for 20,000 cycles. Furthermore, the use of engineering plastics made it possible to reduce the weight by approximately 30% compared to existing products. The lack of damage after tests verified the passenger safety, strength, and rigidity of the product. The results are expected to be applied for improving environmental and fuel efficiency regulations and preventing accidents due to driver fatigue. The applications of this module could be expanded various types of vehicles, as well as other industries in which eco-friendly and lightweight materials are used.

• Transactions of the KSME C: Technology and Education
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• v.3 no.2
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• pp.131-140
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• 2015

The mono-ski for the paraplegia designed to skiing is formed as seat bucket on the sled. The impact force transferred by snow surface during skiing is absorbed by the leg joints of normal human, but it is transferred to the human body on the seat when using mono-ski. Most of commercially available mono-ski have absorbing device and link mechanism between seat and ski mount in order to complement it. In this study we developed the comfort evaluation model that could provide skiing simulation of mono-ski with hydraulic damper and analyzed vibrational acceleration occurred during skiing uneven surface. The evaluation method used in this study is the international standard BS6841. We evaluated comfort performance of mono-ski in accordance with nozzle adjustment of hydraulic damper.

• Journal of IKEEE
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• v.26 no.4
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• pp.602-613
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• 2022

This paper proposes an algorithm for correcting indirect situations resulting from the wheelchair moving the stairs with wheel-type caterpillar and seat position variable. For analyzing the Yawing movement model, the change of Yaw value was estimated using Roll, Pitch, and Yaw in the driving environment, and it was used as a control variable and the information of the wheel drive controller. The verification confirmed the correction of about 10° of Yawing movement within about 7 seconds. It was confirmed that the angular velocity was reduced by 47.5% in seat position change.

• Journal of Environmental Health Sciences
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• v.20 no.1
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• pp.28-38
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• 1994

The objective of this study were to measure concentrations of indoor pollutants in public transportation systems to provide importance of indoor air quality in transportation systems to policy makers. Indoor air quality of the pollutants (CO, CO$_2$, PM-10) and environmental sources (temperature, humidity) were measured at subway, seat-type bus, and city-type bus in the Seoul area from April to September 1992. The same pollutants and environmental sources were also measured at selected bus stops and subway stations during October 1991-September 1992. The mean concentrations of indoor pollutants in the public transportation systems were showed 115.5 $\mu$g/m$^3$ in PM-10, 6.8 ppm in CO, and 2167.9 ppm in CO$_2$, respectively. The mean values of PM-10 and CO showed below the U.S. 24 hour standard value of PM-10 and the Korea ambient CO standard, while the mean concentrations of CO$_2$ exceeded the Korea CO$_2$ standard. The highest levels of indoor concentration at public transportation systems were PM-10 of 134.6 $\mu$g/m$^3$ in the subway, CO of 8.9 ppm in the city-type bus, CO$_2$ of 2,511.1ppm in seat-type bus, respectively. The results showed that indoor air quality in bus and subway seemed likely to be affected by number of passengers and outdoor air infiltrated from exhausted gases of automobiles.

• Safety and Health at Work
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• v.10 no.3
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• pp.314-320
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• 2019

Background: Sitting posture may be related to risk factors, including inadequate weight-bearing support, particularly when maintained for long periods. Considering that body weight is loaded in a closed support system composed of the seat, backrest, floor and working surface, the aims of the present study were to describe the development of an ergonomic sitting workstation to continuously record weight-bearing at the seat, chair, backrest, work surface, and floor and to test its measurement properties: reproducibility, criterion-related validity, and sensitivity. Methods: Rigid bodies (1 to 30 kg) and participant weights were recorded to evaluate the workstation measurement properties. Results: Rigid body tests showed variation values less than 0.050 kg on reproducibility test and errors below 5% of measured value on criterion validity tests. Participant tests showed no statistically significant differences between repeated measures ($p{\geq}0.40$), errors were less than 2% of participant weights an sensitivity presented statistically significant changes (p = 0.007). Conclusion: The sitting workstation proposed showed to be reliable, valid and sensitive for use in future ergonomic studies to evaluate the sitting posture.