• Journal of Korean Society of Transportation
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• v.34 no.6
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• pp.560-569
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• 2016

Previous studies show that driver mental workload plays a significant role in the occurrence of traffic accidents. This study also analyzes driving workload under different road conditions especially with the brain wave data collected by a driving simulator. We use a logistic regression model to explain the relationship between driving workload and gamma brain waves. The results show that beta band of brain waves becomes broader with more curved sections while alpha band and gamma band become narrower. Since driving workload is negatively correlated with gamma band, it can be concluded that driving condition with less curved section is beneficial for reducing driving stress and increasing driving comfort.

• Proceedings of the KSME Conference
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• 2000.11b
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• pp.397-403
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• 2000

In the present study, flow characteristics of turbulent pulsating flow in a square-sectional $180^{\circ}$ curved duct were experimentally investigated. Experimental studies for air flows were conducted to measure axial velocity and wall shear stress distributions and entrance length in a square-sectional $180^{\circ}$ curved duct by using the LDV with the data acquisition and the processing system. The experiment was conducted in seven sections from the inlet (${\phi}=0^{\circ}$) to the outlet (${\phi}=180^{\circ}$) at $30^{\circ}$ intervals of the duct. The results obtained from the experimentation were summarized as follows ; (1) When the ratio of velocity amplitude ($A_1$) was less than one, there was hardly any velocity change in the section except near the wall and any change in axial velocity distributions along the phase. When the ratio of velocity amplitude ($A_1$) was 0.6, the change rate of velocity was slow. (2) Wall shear stress distributions of turbulent pulsating flow were similar to those of turbulent steady flow. The value of the wall shear stress became minimum in the inner wall aid gradually increased toward the outer wall where it became maximum. (3) The entrance length of turbulent pulsating flow reached near the region of bend angle of $90^{\circ}$, like that of turbulent steady flow. The entrance length was changed by the dimensionless angular frequency (${\omega}^+$).

• Journal of Environmental Science International
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• v.22 no.5
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• pp.571-580
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• 2013

In this study, compared with the result of water surface elevation and water velocity on the establishment of river maintenance basic plan and result of HEC-GeoRAS based GIS, and after use the result of water surface elevation and velocity were observed in the Han stream on Jeju island, analysis 2 dimensional stream flow. the lateral hydraulic characteristics and curved channel of the stream were analyzed by applying SMS-RMA2 a 2 dimensional model. The results of the analysis using HEC-RAS model and HEC-GeoRAS model indicated that the distribution ranges of water surface elevation and water velocity were similar, but the water surface elevation by section showed a difference of 0.7~2.18 EL.m and 0.63~1.16 EL.m respectively, and water velocity also showed differences of maximum 1.58m/sec and 2.67m/sec. SMS-RMA2 analysis was done with the sphere of Muifa the typhoon as a boundary condition, and as a result, water velocity distribution was found to be 1.19 through 3.91 m/sec, and the difference of lateral water velocity in No. 97 through 99 the curved channel of the stream was analyzed to be 1.59 through 2.36 m/sec. In conclusion it is anticipated that the flow analysis of 2 dimension model of stream can reflect the hydraulic characteristics of the stream curved channel or width and shape, and can be applied effectively in the establishment of river maintenance basic plan or management and designing of stream.

• The Journal of the Convergence on Culture Technology
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• v.7 no.3
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• pp.517-522
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• 2021

In this study, the causes of damage to the concrete sleepers in a ballast track with under sleeper pads attached to the base of the sleepers installed in the sharp curved track(R=180m) of the urban railway bridge were analyzed. The damage types of concrete sleepers were investigated, and the correlation with track irregularity was reviewed. Also, stress generated in the concrete sleeper was reviewed through structural analysis. As a result, most of the cracks of the sleepers occurred in the section with severe track irregularity. In addition, as a result of the analysis, the stress generated in the track components and the sleepers was found to be reduce in the fastening system using the 4-anchor.

• Journal of Korean Society of Forest Science
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• v.110 no.4
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• pp.622-629
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• 2021

This study analyzed the running speed of logging trucks (25 tons), depending on the structural state of forest roads, on four main forest roads in the national forest management offices in Chuncheon and Hongcheon for trafficability. The speeds for the curved and straight sections were 7.6 km/h and 8.7 km/h, respectively, which were less than the designed speed (20 km/h). Thus, it would be necessary to improve the forest road's structure to fulfill minimum running speed. No significant difference was observed in the running speed by the longitudinal gradient up to 13%, while it was increased at more than 100 m by the distance in the straight section. By the facility's location in the curved section, the running speed was 6.2%-9.3% lower in a ridge than a valley. The running speed was lowest at the internal angles of <90° and at the curved radius of <15 m, respectively. When this radius was less than 15 m, the substandard sections for widening amounts were more than 50%; thus, sufficient widening was not achieved.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.5
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• pp.577-584
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• 2019

Recently, CSB(Cable-Stayed Bridge) have been attempted to be atypical forms for landscape elements in Korea. CSB with new geometry need to analyze their characteristics clearly to ensure structural safety. This study's bridge is the S-shaped curved pedestrian CSB that has a girder with S-shape plane curve and reverse triangular truss cross section, inclined independent pylon, modified Fan type main cable and vertical backstay cable. Curved CSB can have excessive lateral displacement and moment when the tension is adjusted, focusing only on longitudinal behavior, such as a straight CSB. In order to analyze the effect of the cable on the lateral behavior of bridges, the cable is divided into two groups according to the lateral displacement direction of the pylon due to tension. The influence of the combination ratio of GR1 and GR2 on the girder, bearing, pylon, and vertical anchor cable was analyzed. When the tension applied to the bridge is 1.0GR1 plus 1.0GR2, In the combination of 1.2GR1 plus 0.8GR2, the stress on the left and right upper member of the truss girder and the deviation of the both were minimized. In addition, the horizontal force of the bearing, the lateral displacement and moment of the pylon, and the tension of the vertical backstay cable also decreased. This study is expected to be used as basic data for determination of tension of CSB with similar geometry.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.2D
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• pp.127-134
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• 2010

Tunnel sections on the highway are different from rest of sections on the highway in terms of velocity, the number of passing cars, and vehicle density which, in particular, affect drivers' behavior before and after drivers pass through the tunnel. However, literature review reveals that former studies are too focused on quantitative indicator to consider qualitative aspects. Therefore, this paper conducts survey questionnaire and IPA (Importance Performance Analysis) to find out qualitative improvements on velocity drop on the tunnel sections. The results show as follows: First, drivers require improvements of tunnel form (length and curved form inside tunnel) which is derived from long distance tunnel. Second, experts primarily ask for amendment of geometric characteristics. With comparison of requirements of both drivers and experts, there are many differences in length of tunnel and form of curved tunnel. This also presents that drivers don't satisfy with both length of tunnel and form of curved tunnel that are provided as a part of highway design factors.

• The Journal of Engineering Geology
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• v.19 no.3
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• pp.277-285
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• 2009

In order to assess the fault behavior by the geometric analysis of fault slip, the study area between Yangsan city and Shinkwang-myon, Pohang city along the strike of the Yangsan fault is divided into 5 domains($A{\sim}E$ domains) based on the strike change of main fault, the type of fault termination, the cyclic variation of fault zone width, deformation pattern of fault rocks and angular deviation of secondary shears. And, we would apply the relationship between the mode of fault sliding and the resultant deformation texture obtained from previous several experimental studies of simulated fault gouge to the study of the Yangsan fault. To understand sliding behavior of the fault we measured the data of fault attitude and fault slip, and analyzed relationships between the main fault and secondary Riedel shear along the Yangsan fault. The sliding behavioral patterns in each section were analyzed as followings; the straight sections of A, D and E domains were analyzed as the creeping section of stably sliding. In contrast, the curved section of B domain was analyzed as the locked section of stick-slip movement.

• Korean Institute of Interior Design Journal
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• v.25 no.6
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• pp.52-60
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• 2016

Observation about space is looked steady in an instant, but in continuous movement, one's observation unconsciously stays at different points. In department store, customer actually observes around the store for buying, not focusing on certain point. By studying customer's movement and observation feature, buying desire and interest can be found. For analysis of the different searching-features according to the continuous-observation depending on sex, the study is set up to record movements of customers at women in Department store. The following are the findings. First, Men observed 0.2-0.4 units more in I-II section which are assumed as predominant. The result shows that men can focus on more section (around +0.4%) and longer (around +5.7%) than women do. Second, the same feature of observation depending on sex is that both men and women observe left and right section while keep focusing on middle section. Third, according to the fact that right-focused observation magnificently occurred in the image curved to right, the Space-composition has influenced on the observation of both men and women on the space. Forth, excessive number of display can cause avoidance of observation. Moreover, observation does not stay on the coverage due to wall or post, but is attracted to the brand name. As brand name causes right-focused observation in the image [(8)], brand name can be one of the reasons to attract observation in women apparel store. To sum up, this study is noticeable as it researches about continuous-observation. Furthermore, verifying the result that the composition of space and the placement of products can cause big differences in the observation feature is meaningful outcome.

• International Journal of Highway Engineering
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• v.17 no.5
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• pp.115-122
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• 2015

PURPOSES: Recently, many local governments have applied chicanes for traffic calming to ensure environment-friendly comfortable and safe roads. However, the geometry of a chicane is designed for speed reduction using a curved portion. This study aims to improve the road geometry conditions of chicanes for reducing carbon emissions and maintaining appropriate driving speeds by considering the relationship between road geometry and carbon emissions. METHODS: This study was conducted as follows. First, carbon emissions corresponding to changing acceleration of vehicles were studied. Second, vehicle acceleration caused by the relationship between the curve radius and the straight length was studied. Accordingly, desirable conditions of curve radius and length of the straight section for reducing carbon emissions were proposed. RESULTS: The existing literature on chicanes present the minimum value of stagger length and path angle in the primary variable condition. This study suggests the maximum values of the curve radius and length of straight section in the primary variable condition. Therefore, if a vehicle's speed at a chicane is 30 km/h, this study suggests a curve radius of up to 24 m. In addition, if the vehicle's speed is 24 km/h, this study suggests a length of straight section of up to 6.6 m. These are the geometric conditions for considering the control of acceleration to the vehicle's maximum speed. CONCLUSIONS: This paper proposes an application of geometric conditions to reduce carbon emissions and maintain appropriate speeds of vehicles through a combination of curve radius and length of straight section.