• Geomechanics and Engineering
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• v.7 no.1
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• pp.75-85
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• 2014

The application of the mechanized tunnelling has been extended in recent years. There are at present different approaches that are used in the design of segmental tunnel linings supported in mechanized tunnels. Even though segmental lining is utilized for mechanized tunnels, its behaviour is still quite unclear under in situ stress and there is a lack of data regarding the distribution of stresses inside segmental linings. So far no single effective calculation method exists for segmental lining design. The lack of clear solutions makes the use of segmental lining to be more expensive due to the adoption of greater safety factors. Therefore, a particular attention must be given in order to obtain data from monitored tunnels which permits to validate design methods. In this study, strain measurements, which were conducted during the construction of twin tunnels in the Bologna-Florence railway line, have been presented. The behaviour of segmental lining during the excavation and the influence of a new tunnel excavation on an existing tunnel have been shown through the measured data. The data are then compared with the results obtained with Einstein and Schwartz's method and Duddeck and Erdmann's method, which permits to highlight the fact that the two analytical methods underestimate structural forces induced in the segmental lining and then must be used with caution.

• 기술발표회
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• s.2006
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• pp.162-171
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• 2006

Segmental Grid Retaining Wall is one of the segmental grid retaining walls using headers and stretchers to establish the framework of the wall In this method, grids formed by the intersection of headers and stretchers are generally filled with the gravel to maintain the weight of the wall Therefore, the construction can be carried out with higher speed and much economically when compared with the concrete retaining wall Furthermore, it has high drain capacity, and environmentally friendly aspects also have been pointed out because the possibility of the planting at the front of the wall However, in the segmental grid retaining wall method, the relative movement between the individual headers and stretchers was generally recognized, and stress redistribution in the gravel filling was also observed when subjected to the external loading and self-weight of filling Therefore, it has been thought that the distribution of the earth pressure in the segmental grid retaining wall system differ from that of the concrete retaining wall In this study, the surcharge tests using the scaled model segmental grid retaining wall was carried out to observe the distribution of the earth pressure in the segmental grid retaining wall The earth pressure was measured in the six specified height of wall, and the distribution of the pressure was analyzed. Furthermore, the earth pressure by computation or by the test using the concrete retaining wall was also considered to make comparison

• Journal of KIISE:Software and Applications
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• v.29 no.3
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• pp.167-179
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• 2002

In this paper, we propose a new acoustic model for characterizing segmental features and an algorithm based upon a general framework of hidden Markov models (HMMs) in order to compensate the weakness of HMM assumptions. The segmental features are represented as a trajectory of observed vector sequences by a polynomial regression function because the single frame feature cannot represent the temporal dynamics of speech signals effectively. To apply the segmental features to pattern classification, we adopted segmental HMM(SHMM) which is known as the effective method to represent the trend of speech signals. SHMM separates observation probability of the given state into extra- and intra-segmental variations that show the long-term and short-term variabilities, respectively. To consider the segmental characteristics in acoustic model, we present segmental-feature HMM(SFHMM) by modifying the SHMM. The SFHMM therefore represents the external- and internal-variation as the observation probability of the trajectory in a given state and trajectory estimation error for the given segment, respectively. We conducted several experiments on the TIMIT database to establish the effectiveness of the proposed method and the characteristics of the segmental features. From the experimental results, we conclude that the proposed method is valuable, if its number of parameters is greater than that of conventional HMM, in the flexible and informative feature representation and the performance improvement.

• Geomechanics and Engineering
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• v.14 no.3
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• pp.293-299
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• 2018

This paper has the aim of estimating the applicability of a numerical approach to the Hyperstatic Reaction Method (HRM) for the analysis of segmental tunnel linings. For this purpose, a simplified three-dimensional (3D) numerical model, using the $FLAC^{3D}$ finite difference software, has been developed, which allows analysing in a rigorous way the effect of the lining segmentation on the overall behaviour of the lining. Comparisons between the results obtained with the HRM and those determined by means of the simplified 3D numerical model show that the proposed HRM method can be used to investigate the behaviour of a segmental tunnel lining.

• Journal of Electrical Engineering and Technology
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• v.13 no.3
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• pp.1138-1146
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• 2018

Performance comparisons of switched reluctance motor for cooling fan application are dealt in this paper. Conventional and novel segmental type motors with the same dimension are compared. The conventional 12/8 type is very popular and used widely. The structure of segmental rotor type motor is constructed from a series of discrete segments, and the stator is constructed from two types of stator poles: exciting and auxiliary poles. This type of motor has short flux path and no flux reversal in the stator. The auxiliary poles are not wound by the windings and only provide the flux return path. Compared with conventional SRM, the segmental structure increases electrical utilization of the machine and decreases core losses, which leads to higher efficiency. To verify the segmental structure, finite element method (FEM) is employed to get static and dynamic characteristics of both SRMs. Finally, the prototypes of conventional and segmental SRMs are tested for characteristics comparisons.

• Korean Journal of Community Nutrition
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• v.2 no.2
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• pp.179-186
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• 1997

A new bioelectrical impedance method has been developed and evaluated. The electrodes; were made of stainless steel and electrical interfaces were created by an upright subject gripping hand electrodes and stepping onto foot electrodes. Eight tactile electrodes were in contact with surfaces of both hands and feet; thumb, palm and fingers, front sole, and rear sole. Automatic on-off switches were used to change current pathways and to measure voltage differences for target segments. Segmental body resistances and whole body resistance(RWHOLE)were measured in 60 healthy subjects. Segmental resistances of right arm(RRA), left arm(RLA), trunk(RT), right leg(RRL) and left leg(RLL)were310.0$\pm$61.6$\Omega$, 316.9$\pm$64.6$\Omega$, 25.1$\pm$3.4$\Omega$, 236.8$\pm$31.2$\Omega$ and 237.6$\pm$30.4$\Omega$, respectively. Individual segmental impedance indexes(Ht2/RRA, Ht2/RT, and Ht2 /RLA) were closely related to lean body mass(LBM)as measured by densitometry ranged from r=0.925 to 0.960. Ht2/(RRA+RT+RLA) predicted LBM slightly better(r=0.969) than the traditional index, Ht2/RWHOLE(r=0.964), supporting the accuracy of the segmental measurement. A multiple regression equation utilizing Ht2/RRA, Ht2/RT and Ht2/RRL predicted LBM with r=0.971. Ht2/RRA term of the regression contributed to more than 40$\%$ of the LBM prediction, indicating that lean mass of arm represented whole body LBM more closely than other body segments. The new bioimpedance method was characterized by upright posture, eight tactile electrodes, segmental measurements and utilization of electronic switches in comparison with the traditional method. The measurement with this new method was extremely reproducible, quick and easy to use.

• Magazine of the Korea Concrete Institute
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• v.6 no.3
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• pp.84-95
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• 1994

• Proceedings of the Korean Geotechical Society Conference
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• 1999.11c
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• pp.69-83
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• 1999

Soil-reinforced segmental retaining walls(SRW) have been proven to be high earthquake-resistant structure during recent earthquakes in United States and Japan. The mechanicals behavior of the SRWs under seismic loading, however, has not been fully understood. Although the seismic design issues for the civil engineering structures have gained much attention in Korea due to the increase in frequency of earthquake occurrence, the seismic design for the SRWs has not been being implemented. This study has been undertaken with the aim of developing a more rational seismic design/analysis method for soil-reinforced segmental retaining walls. This paper present fundamentals of current seismic design/analysis method and the results of a comparative study between NCMA and FHWA design guidelines, Practical implications of the findings from this study are discussed in great detail.

• Proceedings of the Korea Concrete Institute Conference
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• 1989.10a
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• pp.73-76
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• 1989

A numerical procedure is developed to analyze the time-dependent behavior of prestressed concrete bridges constructed by the segmental cantilever method. The developed computer program accounts for the time-dependent properties of prestressed concrete materials due to the varing modulus of elasticity, creep and shrinkage of concrete and the stress relaxation of prestressing steel. It also accounts for the stiffness increase due to the presence of the steel reinforcements and the effects of the shear deformation of the prestressed concrete bridge girders. The program is applied to a multi-span continuous segmental prestressed concrete bridge to demonstrate its capabilities.

• Advances in concrete construction
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• v.16 no.2
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• pp.79-89
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• 2023

The occurrence of unexpected horizontal offset in the instrument or target will result in accumulated horizontal deviation in segment alignment with traditional short-line match method. A geometry control method, the four-point method, is developed for precast segmental bridges to avoid the influences of unexpected horizontal offset. The concept of the four-point method is elucidated. Furthermore, the detailed instruments and instructions are introduced. Finally, the four-point method is validated through a practical engineering application. According to the survey data, after short-line match precast construction, the vertical deviations on both sides vary between -5 mm and 5 mm in almost all segments, and the horizontal deviations vary between -4 mm and 4 mm in all segments. Without on-site adjustment, the maximum vertical and horizontal closure gaps are 12.3 and 26.1 mm, respectively. The four-point method is suggested to alleviate the issues associated with relatively poor soil conditions in casting yard.