• Geomechanics and Engineering
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• v.11 no.6
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• pp.739-756
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• 2016

The shear strength reduction finite element method (SSRFEM) is a powerful tool for slope stability analysis. The factor of safety (FOS) of the slope can be easily calculated only through reducing effective cohesion (c′) and tangent of effective friction angle ($tan{\varphi}^{\prime}$) in equal proportion. However, this method may not be applicable to soil slope under wetting-drying cycles (WDCs), because the influence of WDCs on c′ and $tan{\varphi}^{\prime}$ may be different. To research the method of estimating FOS of soil slopes under WDCs, this paper presents an experimental study firstly to investigate the effects of WDCs on the parameters of shear strength and stiffness. Twelve silty clay samples were subjected to different number of WDCs and then tested with triaxial test equipment. The test results show that WDCs have a degradation effect on shear strength (${\sigma}_1-{\sigma}_3)_f$, secant modulus of elasticity ($E_s$) and c′ while little influence on ${\varphi}^{\prime}$. Hence, conventional SSRFEM which reduces c′ and $tan{\varphi}^{\prime}$ in equal proportion cannot be adopted to compute the FOS of slope under conditions of WDCs. The SSRFEM should be modified. In detail, c′ is merely reduced among shear strength parameters, and elasticity modulus is reduced correspondingly. Besides, a new approach based on sudden substantial changes in the displacement of marked nodes is proposed to identify the slope failure in SSRFEM. Finally, the modified SSRFEM is applied to compute the FOS of a slope example.

• Korean Journal of Applied Biomechanics
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• v.14 no.3
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• pp.235-257
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• 2004

The purpose of this study was to analyze the kinematical traits variables when performing Uchimata(inner thigh reaping throw) by Voluntary Resistance Levels(VRL) and two postures of Uke in Judo. The subjects, who were one male judoka(YH) for 1992 Barcelona Olympic Games, and one male trainee Y. I. University representative member(SDK) and were filmed on two S-VHS 16 mm video cameras(60fields/sec.), that posture of Uke were Shizenhontai(straight defensive posture) and Jigohontai(straight natural posture), VRL of Uke were 0% and 100%. The kinematical variables were temporal(total time-required: TR), potures and COG variables etc., The data of this study collection were digitized by SIMI Motion Program computed the mean values and the standard deviation calculated for each variables. When performing according to each posture and VRL, from the data analysis and discussion, the conclusions were as follows : 1. Temporal variables total time-required(TR) when performing Uchimata was shown the shortest time YH than SDK by each posture and VRL. TR of each posture were shown the shorten trends or equal in DP by lower than NP, In existence and / or nonexistence of VRL was shown the shorten trends in VRL 0% than 100% of Uke. 2. Posture variables : In attacking right knee angle, YH was performing flexion($147{\rightarrow}103degree$) from Tsukuri(set-up) to Kake(execution) in regardless of postures and VRLs, SDK was performing not exchange extension and flexion in VRL 100%, and extension($120{\rightarrow}142degree$) in VRL 0%, respectively. In supporting left hee angle, YH was performing extension($119{\rightarrow}163degree$) from Tsukuri(set-up) to Kake(at(execution) in regardless of postures and VRLs, SDK extension($93{\rightarrow}139degree$), respectively. In attacking right hip angle, from Tsukuri to Kake, YH was performing extension($133{\rightarrow}169degree$), except in VRL 0%($156{\rightarrow}137degree$) NP, SDK was performing flexion($159{\rightarrow}126degree$) accept in VRL 100%($149{\rightarrow}152degree$) NP, In left hip angle, from Tsukuri to Kake, YH was performing flexion NP(70, 50degree) more than DP(27, 57degree), SDK was performing flexion DP(73, 52degree) more than NP(34, 20degree). 3. COG variables : When performing Uchimata, vertical COG variables was shown YH(:$2{\sim}8cm$), SDK(:$15{\sim}24cm$) lower than Uke's COG level position, in existence and / or nonexistence of postures and VRL, during Kake as maximum force point of throwing techniques in Judo.

• Wind and Structures
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• v.10 no.4
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• pp.367-382
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• 2007

A nonlinear numerical method was developed to assess the stability of suspension bridge catwalks under a wind load. A section model wind tunnel test was used to obtain a catwalk's aerostatic coefficients, from which the displacement-dependent wind loads were subsequently derived. The stability of a suspension bridge catwalk was analyzed on the basis of the geometric nonlinear behavior of the structure. In addition, a full model test was conducted on the catwalk, which spanned 960 m. A comparison of the displacement values between the test and the numerical simulation shows that a numerical method based on a section model test can be used to effectively and accurately evaluate the stability of a catwalk. A case study features the stability of the catwalk of the Runyang Yangtze suspension bridge, the main span of which is 1490 m. Wind can generally attack the structure from any direction. Whenever the wind comes at a yaw angle, there are six wind load components that act on the catwalk. If the yaw angle is equal to zero, the wind is normal to the catwalk (called normal wind) and the six load components are reduced to three components. Three aerostatic coefficients of the catwalk can be obtained through a section model test with traditional test equipment. However, six aerostatic coefficients of the catwalk must be acquired with the aid of special section model test equipment. A nonlinear numerical method was used study the stability of a catwalk under a yaw wind, while taking into account the six components of the displacement-dependent wind load and the geometric nonlinearity of the catwalk. The results show that when wind attacks with a slight yaw angle, the critical velocity that induces static instability of the catwalk may be lower than the critical velocity of normal wind. However, as the yaw angle of the wind becomes larger, the critical velocity increases. In the atmospheric boundary layer, the wind is turbulent and the velocity history is a random time history. The effects of turbulent wind on the stability of a catwalk are also assessed. The wind velocity fields are regarded as stationary Gaussian stochastic processes, which can be simulated by a spectral representation method. A nonlinear finite-element model set forepart and the Newmark integration method was used to calculate the wind-induced buffeting responses. The results confirm that the turbulent character of wind has little influence on the stability of the catwalk.

• Journal of the Korean GEO-environmental Society
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• v.10 no.3
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• pp.37-45
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• 2009

The experimental study was carried out to evaluate the characteristics of the point load index and the uniaxial compressive strength of inherently anisotropic shale in the laboratory. In the testing program the effects of size and the shape on the point load index were investigated both in the axial and diametral direction. In general, the point load index of the shale was constant when the length/diameter (L/D) ratio of the specimen is greater than 1.0 in the diametral direction. The point load index in axial direction shows slight decrease as the L/D ratio is increased and the corner breakage was observed when L/D ratio is greater than unity. The minimum point load index was observed in the bedding angle of $\beta=15^{\circ}{\sim}30^{\circ}$ in the axial point load tests and of $\beta=30^{\circ}$ in the uniaxial compression tests. The relationship between the point load index and the uniaxial compressive strength was linear to ${\sigma}_c=25.0 I_{s(50)}$ for the specimen with the bedding plane angle, $\beta$ at the range of $0^{\circ}{\sim}90^{\circ}$. On the other hand, this relationship was appeared linear to ${\sigma}_c=14.4 I_{s(50)}$ when the bedding angle, $\beta$ is fixed to 90${^{\circ}}$ and this correlation is much different from ${\sigma}c=22 I_{s(50)}, which is generally applied to the rock specimen with no bedding plane in ISRM (1985). The anisotropic strength with different $\beta$ angle shows the shoulder type and this can be suitably modelled by the corrected Ramamurthy'(1993)s equation with the index value of 'n' equal to 3.0.

• Journal of Oral Medicine and Pain
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• v.38 no.2
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• pp.149-159
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• 2013

The purpose of this study was to investigate the relationship between horizontal morphology of lateral pterygoid muscle and onset of temporomandibular joint disorders. Randomly selected 150 subjects, assigned with equal number in terms of gender and age group, were included. The axial and sagittal images in their magnetic resonance images of the temporomandibular joints were used to measure the morphologic characteristics of lateral pterygoid muscles and temporomandibular joints. The measurement variables were maximal horizontal width and insertion angle to the condyle, position of the articular disc, condylar deformity, and joint effusion. In addition, presence or absence of the temporomandibular joint pain was examined through history and palpation of the joints. The relationships among measurement variables were analyzed and the results were as follow. The insertion angle of the lateral pterygoid muscle to the condyle was higher in the joint of anterior disc displacement without reduction than that in the joint of normal disc position. In addition, the maximal horizontal width of the lateral pterygoid muscle was significantly increased in joints with pain than those without pain. Also, the insertion angle was significantly higher in younger age group and the maximal width was significantly greater in male than in female. These results suggest that high insertion angle of lateral pterygoid muscle might be an important anatomic predisposing factor for anterior disc displacement in temporomandibular joint and muscular activity of lateral pterygoid muscle might be affected by preauricular pain. In conclusion, there might be a bi-directional interaction between lateral pterygoid muscle and joint in the progression of anterior disc displacement in temporomandibular joint.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.42 no.3
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• pp.144-150
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• 2016

Objectives: We compared the transbuccal and transoral approaches in the management of mandibular angle fractures. Materials and Methods: Sixty patients with mandibular angle fractures were randomly divided into two equal groups (A, transoral approach; group B, transbuccal approach) who received fracture reduction using a single 2.5 mm 4 holed miniplate with a bar using either of the two approaches. Intraoperatively, the surgical time and the ease of surgical assess for fixation were noted. Patients were followed at 1 week, 3 months, and 6 months postoperatively and evaluated clinically for post-surgical complications like scarring, infection, postoperative occlusal discrepancy, malunion, and non-union. Radiographically, the interpretation of fracture reduction was also performed by studying the fracture gap following reduction using orthopantomogram tracing. The data was tabulated and subjected to statistical analysis. A P -value less than 0.05 was considered significant. Results: No significant difference was seen between the two groups for variables like surgical time and ease of fixation. Radiographic interpretation of fracture reduction revealed statistical significance for group B from points B to D as compared to group A. No cases of malunion/non-union were noted. A single case of hypertrophic scar formation was noted in group B at 6 months postsurgery. Infection was noted in 2 patients in group B compared to 6 patients in group A. There was significantly more occlusal discrepancy in group A compared to group B at 1 week postoperatively, but no long standing discrepancy was noted in either group at the 6 months follow-up. Conclusion: The transbuccal approach was superior to the transoral approach with regard to radiographic reduction of the fracture gap, inconspicuous external scarring, and fewer postoperative complications. We preferred the transbuccal approach due to ease of use, minimal requirement for plate bending, and facilitation of plate placement in the neutral mid-point area of the mandible.

• Journal of the Korean Society of Clothing and Textiles
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• v.37 no.4
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• pp.482-490
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• 2013

This study suggests a suitable logo design application of a three colors LED light source and flexible plastic optical fiber (POF). In this study, characteristic relevant brightness of (according to the embodiment conditions of the flexible POF for logo design) for smart clothing were analyzed through two experiments. The suitable conditions of the logo design for three colors of light source were observed in 'Experiment 1'. The angle of $80^{\circ}$ to $100^{\circ}$ and the length of 8cm to 16cm appeared a more suitable condition for green-colored and red-colored light sources. The angle of $80^{\circ}$ to $100^{\circ}$ at a length of 8cm to 12cm appeared a more suitable condition for a blue-colored light source. In 'Experiment 2', a 'Klavika' in small letter was selected as suitable logo design for the application POF. The alphabet was separated by a morpheme, which is the minimal linguistic unit. All alphabets were classified into sixteen morphemes. The luminance of fourteen morphemes (realized by the embroidery method) were measured and analyzed. Subsequently, eight morphemes appeared to show a relatively equal luminance of $3-4cd/m^2$ in a green-colored light source, $2-3cd/m^2$ in red-colored light source, and $2cd/m^2$ in a blue-colored light source. Four of the fourteen morphemes, showed a 20% brighter level of luminance compared to the eight morphemes above, the cast of combination of green or red light source. This result indicates that a flexible POF with 20% less luminance are believed more suitable for four morphemes combined with a green or red light source. The results of this study provide fundamental data for further approaches to clothing logo design for the application of a flexible POF.

• Journal of Ocean Engineering and Technology
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• v.6 no.2
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• pp.21-34
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• 1992

The behavior of fatigue crack growth in the single spot welded joint of zinc galvanized steel sheets was studied experimentally and analytically based on fracture mechanics. Axial tension fatigue tests were carried out with the BSxGAB specimen that the bare plane(GAB) of monogalvanized steel sheet was spot welded to the double thickness bare steel sheet(BS), and with the GAxGAB specimen that the galvanized plane (GA) was spot welded to the equal thickness bare plane (GAB) 1. The relation between maximum stress intensity factor, K sub(max) and the number of cycles to failure, N sub(f) has shown a linear relation on log-log plot in the spot weld of the zinc galvanized steel sheet. 2. The fatigue strength of BSxGAB specimens is about 23% higher than that of GAxGAB specimens at the fatigue strength of $1\times10^6$ cycles. And the fatigue life of BSxGAB specimens at the same load range increases 6~9 times higher than that of GAxGAB specimens. 3. The general tendency at the angle of bending($\theta$) in an applied load has changed rapidly at the initial 20% of its life. After then, it has changed slowly. The change at the angle of bending has increased linearly as the load range increases. 4. It has shown a linear relation between the location ratio of initiation ${\gamma}$ and fatigue life $N_f$ on the semi-log graph paper. Here $\gamma$ means that the crack distance between main crack and sub-crack, 2L is divided by the nugget diameter, 2r. $\gamma=a{\cdot}log N_f+n$ (where a and n are material constant.)

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.12
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• pp.3277-3285
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• 1996

In this paper, w designed an opical power distribution device for application to an optical switching and an optical subscriber loop. We fabricated PSG thin film by LPCVD. Based on the measured index of fabricted thin film, rib-type waveguide was transformed to two-dimension by the effective index method and we simulated dispersion property to find asingle-mode condition. We found that the optimum design parameters of rib-type waveguide are:cladding layer of 3.mu.m, core layer of 3.mu.m, buffer layer of 10.mu.m, and core width of 4.mu.m. Each side of the guiding region was etched down to 4.mu.m to shape the core. We used these optimum parameters of the rib-type waveguide with branching angle of 0.5.deg. and simulted the Y-branch waveguide by the BPM simulation. Numerical loss in branching area was claculated to be 0.1581dB and equal to the total loss of the Y-branch. The loss of the fabricated Y-branch waveguide on PSG film ws 1.6dB at .lambda.=1.3.mu.m before annealing but was 1.2dB after annealing at 1000.deg. C for 10 minutes. Consequently, the loss of branching area from 3000.mu.m to 6000.mu.m in the z-direction was 0.8dB, and single-mode propagation was confirmed by measuring the near field pattern. For coupling the fabricated Y-branch waveguide with an optical fiber, we fabricated V-groove which was used as the upholder of optical fiber. An etching angle was 54.deg. and the width and depth of guiding groove was 150.mu.m, 70.mu.m, respectively. The optical fiber is inserted onto V-groove. Both the Y-branch and V-groove were connected through the index matching oil. Coupling loss after connecting Y-branch and the optical fiber on V-groove was 0.34dB and that after injecting index mateching oil was 0.14dB.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.47 no.1
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• pp.1-9
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• 2011

In order to investigate the cause and magnitude of scale effect occurring in the model experiments of fishing nets, five pairs of Nylon pyramid nets and one pair of PE ones in which all the two nets paired were equal each other in the factors determining their flow resistance, i. e., the ratio d/l of diameter d to length l of bars, the angle f between two adjacent bars, the attack angle q of nettings to the water flow, and the wall area S of nets, and different in the values of d and l were prepared. Then, the nets were attached to the circular steel frame alternately and their flow resistances with shapes in water were measured on the sea ascribing no turbulent flows by using the tension meter made of a block bearing for the experiment. All the Nylon nets were spreads out easily in water to form a circular cone at relatively low velocity of water and showed the resistance smaller a little in the nets with larger d and l than them with smaller d and l, because the filtration of water through meshes become easier in nets especially with larger l. But PE nettings were not spread out sufficiently on account of their small flexibility and showed higher resistance especially in them with thicker twines. Therefore, the difference in bar length or mesh size and flexibility of nettings between prototype and model nets are regarded to become factors ascribing scale effect. Especially the influence of the difference in mesh size may become large significantly in actual model experiments because the mesh size of model nets is decided at much larger value than that given by scale ratio and so the difference of mesh size between the two nets become much larger than that between nets used in this experiment.