• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.1
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• pp.99-118
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• 2018

Recently, the limit state design method in the design of the structure is in global trend, but it is limited to a few structures in Korea. Since the introduction of the limit state design method has recently been attempted for tunnels, which are the main underground structures, it is surely necessary to understand the latest limit state design method. Therefore, based on the recently published AASHTO LRFD Road Tunnel Design and Construction Guide Specification (2017), structural load factors and load combinations were reviewed, and various factors which should be applied for the review of structures have been analyzed. In this study, utility tunnel section and subway tunnel sections used in Korea were analyzed by the limit state design method, and we have analyzed the direction of application of limit state design method through studying the tendency of member force by various influential factors such as ground conditions, load modifier and joint stiffness.

• Tunnel and Underground Space
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• v.33 no.4
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• pp.255-264
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• 2023

As the demand for urban underground space increases recently, urban tunnel planning is actively progressing. In the urban area, a underground station is planned in consideration of the living environment of residents, and 2-arch tunnel is applied for the stability of existing structures and reduction of environmental damage. However, since the depth of weak rock mass is deeply distributed in the urban area due to severe weathering, careful planning is required to secure tunnel stability. In addition, if TBM mechanical excavation is applied as the main tunnel excavation method considering the composite ground in urban area, the construction connectivity with the 2-arch tunnel of the NATM concept may be deteriorated. In this study, the design case of applying TBM pre-excavation type 2-arch tunnel for the first time in Korea was mainly described. The main considerations for the segment design of TBM pre-excavation type 2-arch tunnel were explained for side tunnels. Also, a stability analysis was conducted to verify the effectiveness and adequacy of the TBM pre-excavation type 2-arch tunnel.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.2
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• pp.513-525
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• 2018

A 3 dimensional numerical analysis for shield TBM tunnel should take into account various characteristics of the shield TBM excavation, such as gap, tail void, segment installation, and backfill injection. However, analysis method considering excavation characteristics are generally mixed with various method, resulting in concern of consistency and reliability degradation of the analytical results. In this paper, a parametric study is carried out by using actually measured ground settlement data on various methods that can be used for 3 dimensional numerical analysis of shield TBM tunneling. As a result, we have analyzed and arranged an analytical method to predict similarly the behavior of ground settlement and tunnel face pressure at the design stage. Skin plate pressure, backfill pressure and soil model have been identified as the most significant influences on the ground settlement. The grout pressure model is considered to be applicable when there is no volume loss information on the excavated ground, such as seabed tunnels, or when it is important to identify the behavior around a tunnel, such as surface settlement as well as face pressure. And it is considered that designers can use these guidelines as a base material to perform a reasonable 3 dimensional numerical analysis that reflects the ground conditions and the features of the shield TBM tunneling.

• Journal of the Korean Applied Science and Technology
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• v.37 no.2
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• pp.232-240
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• 2020

The purpose of this study was to analyze the effect of using standing step condition on biomechanical variables during jab in boxing. For this purpose, eight orthodox type college boxers(age = 20.38±0.52 yrs, height = 172.38±5.80 cm, body mass = 63.45±8.56 kg, career = 6.00±1.07 yrs) who without injury to the musculoskeletal system participated in the experiment over the last year. In order to verify the effect of biomechanical variables using standing step during jab in boxing, the paired t-test (α = .05) statistical method was used. First, W.S(with-step) showed a greater impact force than N.S(non-step), and muscle activity was analyzed to be low. Second, it was analyzed that the pelvis and foot segments move faster because W.S affects the velocity of the anterior segment of the human body. Third, the rotational movement of the pelvis was faster in W.S. Fourth, W.S was analyzed to have greater ground reaction force in the anterior caused by the right and left foot than N.S. Through this, it was found that the use of the standing step during jab increases the ground reaction force the velocity and rotational movement of the human segment. Therefore, it was confirmed that it allowed a faster and more agile movement, and thus produces a greater impact force with relatively less muscle activity. Therefore, in order to effectively deliver a greater impact force to the opponent during the jab, it was effectively analyzed to accompany the standing step.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.185-185
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• 2011

Mapping of artificial levee lines, one of major tasks in river zone mapping, is critical to prevention of river flood, protection of environments and eco systems in river zones. Thus, mapping of artificial levee lines is essential for management and development of river zones. Coastal mapping including river zone mapping has been historically carried out using surveying technologies. Photogrammetry, one of the surveying technologies, is recently used technology for national river zone mapping in Korea. Airborne laser scanning has been used in most advanced countries for coastal mapping due to its ability to penetrate shallow water and its high vertical accuracy. Due to these advantages, use of LiDAR data in coastal mapping is efficient for monitoring and predicting significant topographic change in river zones. This paper introduces a method for construction of a 3D artificial levee line using a set of LiDAR points that uses normal vectors. Multiple steps are involved in this method. First, a 2.5-dimensional Delaunay triangle mesh is generated based on three nearest-neighbor points in the LiDAR data. Second, a median filtering is applied to minimize noise. Third, edge selection algorithms are applied to extract break edges from a Delaunay triangle mesh using two normal vectors. In this research, two methods for edge selection algorithms using hypothesis testing are used to extract break edges. Fourth, intersection edges which are extracted using both methods at the same range are selected as the intersection edge group. Fifth, among intersection edge group, some linear feature edges which are not suitable to compose a levee line are removed as much as possible considering vertical distance, slope and connectivity of an edge. Sixth, with all line segments which are suitable to constitute a levee line, one river levee line segment is connected to another river levee line segment with the end points of both river levee line segments located nearest horizontally and vertically to each other. After linkage of all the river levee line segments, the initial river levee line is generated. Since the initial river levee line consists of the LiDAR points, the pattern of the initial river levee line is being zigzag along the river levee. Thus, for the last step, a algorithm for smoothing the initial river levee line is applied to fit the initial river levee line into the reference line, and the final 3D river levee line is constructed. After the algorithm is completed, the proposed algorithm is applied to construct the 3D river levee line in Zng-San levee nearby Ham-Ahn Bo in Nak-Dong river. Statistical results show that the constructed river levee line generated using a proposed method has high accuracy in comparison to the ground truth. This paper shows that use of LiDAR data for construction of the 3D river levee line for river zone mapping is useful and efficient; and, as a result, it can be replaced with ground surveying method for construction of the 3D river levee line.

• Korean Journal of Remote Sensing
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• v.26 no.5
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• pp.477-487
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• 2010

In North Korea, forests were intensively degraded by forest land reclamation for food production and firewood collection since the mid-1970s. These degraded forests have to be certainly recovered for economic support, environmental protection and disaster prevention. In order to provide detailed land cover information of forest recovery project (A/R CDM), this study was focused to develop an improved classification method for degraded forest using 2.5m SPOT-5 pan-sharpened image. The degraded forest of North Korea shows various different types of texture. This study used GLCM texture bands of segmented image with spectral bands during forest cover classification. When scale factor 40/shape factor 0.3 was used as a parameter set to generate segment image, segment image was generated on suitable segment scale that could classify types of degraded forest. Forest land cover types were classified with an optimum band combination of Band1, Band2, band3, GLCM dissimilarity (band2), GLCM homogeneity (band2) and GLCM standard deviation (band3). Segment-based classification method using spectral bands and texture bands reached an 80.4% overall accuracy, but the method using only spectral bands yielded an 70.3% overall accuracy. As using spectral and texture bands, a classification accuracy of stocked forest and unstocked forest showed an increase of 23~25%. In this research, SPOT-5 pan-sharpened high-resolution satellite image could provide a very useful information for classifying the forest cover of North Korea in which field data collection was not available for ground truth data and verification directly. And segment-based classification method using texture information improved classification accuracy of degraded forest.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.25 no.2
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• pp.39-46
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• 2019

Background: Ground repulsion or impact on the ground during daily activities, sports, or occupational activities may cause injury to the knee when walking. Non-elastic taping is effective in treating these problems in previous studies. Non-elastic taping strengthens the structure of the soft tissues of the injured knee joint to maintain constant tension, improves muscle rearrangement and function, and improves proprioception. Based on previous studies, we intended to see the therapeutic changes of non-elastic taping in patients with patellofemoral joint pain syndrome. Methods: The non-elastic taping application method was applied to the patient three times for five hours for one week. Non-elastic taping was applied to the patellar tendon with little space above the skin segment of the patellar femur, with both sides fixed by taping. Muscle strength and gait change were evaluated with non-elastc taping. Results: The knee flexion, extension strength and gait evaluation of the knee joint with inelastic taping showed significant differences after treatment. There was a significant difference in the comparison between the two groups after the treatment method was applied (p<.05). Conclusion: As a result, this study confirms that the non-elastic taping method applied for the treatment of patellar femoral joint pain syndrome is effective in the treatment.

• The Journal of Engineering Geology
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• v.24 no.4
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• pp.511-523
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• 2014

Limit equilibrium analysis and finite difference analysis were used to evaluate slope stability in the in Gohan, Korea, which is affected by large-scale tensile cracks and uplift. There is a thick colluvial layer in the study area and predicting ground behavior is problematic because the presence of clay makes it difficult to determine the strength parameters of the soil. Consequently, a numerical model able to reflect the collapse properties of the site was required that applied the modified boundary layer model and calculated the strength parameters using back analysis. The numerical simulation results that consider the strength parameter one does with the present situation the establishment of the pile is completed, and the simulation is able to asses ground stability in complex terrain in a reliable manner. Also the somewhat it judges with the fact that it will be able to provide the fundamental data which secures the stability of the segment where it is unstable.

• Korean Journal of Applied Biomechanics
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• v.19 no.4
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• pp.749-759
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• 2009

The purpose of this study was to provide basic information for improving a soft tennis forehand middle volley technique based on kinematic and kinetic analyses of volleys performed by four male national tennis players($33.3{\pm}2.16$ years). The results are as follows. The first phase of the stroke was the longest, covering 64.7% of the stroke time. The displacement of the center of gravity was 48.1% to the right and 54% to the front in the first phase. When impacted, the elbow joint showed the highest average velocity, 3.67m/s, and the upper arm segment displayed the highest angular velocity, $201^{\circ}/s$. The average of the elbow angle and the ball velocity were $149^{\circ}$ and 18.9m/s, respectively. In the ground reaction force, the left and right foot forces in both the x and y directions showed a statistically significant difference. This result seems to indicate that when the left foot is pushed to the right, the force of the right foot is proportional and symmetrical to the left, serving as a supporter.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.36 no.6
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• pp.535-544
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• 2018

Autonomous driving can be limited by only using sensors if the sensor is blocked by sudden changes in surrounding environments or large features such as heavy vehicles. In order to overcome the limitations, the precise road-map has been used additionally. This study was conducted to segment and classify road objects using 3D point cloud data acquired by terrestrial mobile mapping system provided by National Geographic Information Institute. For this study, the original 3D point cloud data were pre-processed and a filtering technique was selected to separate the ground and non-ground points. In addition, the road objects corresponding to the lanes, the street lights, the safety fences were initially segmented, and then the objects were classified using the support vector machine which is a kind of machine learning. For the training data for supervised classification, only the geometric elements and the height information using the eigenvalues extracted from the road objects were used. The overall accuracy of the classification results was 87% and the kappa coefficient was 0.795. It is expected that classification accuracy will be increased if various classification items are added not only geometric elements for classifying road objects in the future.