• Maxillofacial Plastic and Reconstructive Surgery
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• v.12 no.1
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• pp.62-71
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• 1990

This study was to evaluate the nature of traumatic injuries on anterior teeth of 530 patients and the prognosis of stabilized cases of 102 patients, including possible 18-follow up cases among them, treated at Dental Hospital, Yonsei Medical Center from Mar. 1983 to Feb. 1988. The obtained results were as follows. 1. The peak of monthly distribution of trauma to the anteriors was June and was the lowest in November. The ratio of male to female was 2.6 : 1. The most common incidence of the trauma to the anteriors was seen in the 3rd decades. The most chiefly involved teeth were central incisors in both upper and lower jaws. The causes of trauma were as followed in descending order by first blows, traffic accidents, falls, slip downs, and sports. The types of traumatic injuries of anterior teeth consisted of periodontal tissue injuries(55.9%), the injuries to the hard dental tissues and pulp(31.3%), and alveolar bone injuries(12.8%). 2. 35.1% stabilized anteriors were treated with root canal therapy. The success rate of stabilization was 95.3%, and 92.3% in replantation of avulsed teeth. 3. External root resorption, internal root resorption with calcification of pulp chamber or root canal, ankylosis of root, and other periapical pathosis were seen in follow-up radiographic findings. 4. Success rate of stabilization of the traumatized anteriors after 3 years showed 71.4% average.

• The Journal of the Petrological Society of Korea
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• v.24 no.4
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• pp.307-321
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• 2015

The study area, Bophi Vum, Myanmar, is composed of the harzburgite, serpentinite and dunite, those are covered by Quaternary alluvium. The chromite ore bodies are developed within dunite and harzburgite bodies, mainly within dunite bodies. To identify the extension of the chromite ore bodies, we carried out trench surveys in the 5 different sites. The chromite ore bodies have 0.3-1.5 m wide, and several meters of extension, and deformed strongly as a sigmoid and a boudin shapes with dunite and harzburgite bodies by ductile deformation. The ductile deformation have a top-to-the-west shear sense, indicating the existence of a westward thrusting. The NW-SE trending distribution of ore bodies is related to the dextral ductile shearing and/or to the block rotation as a book-shelf structure by dextral strike-slip movement.

• Journal of the Korean Society of Safety
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• v.28 no.6
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• pp.49-56
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• 2013

The statistics of recent accidents in warehouses show that a heavy toll of lives were produced by various accidents, e.g. collision, overturn, fall, slip, exposure to harmful substances or environments, etc. Of significant concern amongst them is the collision, especially the collision between forklift and storage rack structure. Accordingly, this study focuses on behavioral characteristics of rack structure subjected to dynamic impact loading of a forklift. For this purpose, time-domain response analysis has been performed on a standard 2-bay six-story rack structure consisting of columns, beams and bracing members with perforated open section. In order to investigate the most critical scenario, the impact loads are applied in both down-aisle and cross-aisle directions, and the impact locations are also varied along the shelves of the palettes. In order to deal with storage distributions, three types of rack structures are further taken into account: original empty rack structure with no storage, half-loaded rack structure and fully-loaded rack structure. The numerical simulation results demonstrate that the dynamic characteristics of the rack structure are significantly dependent on the distribution of the storage goods and its natural period varies from 0.24sec to 1.06sec, approximately 4.4 times. Further, the parametric studies show that the forklift impact is most critical to the safety of the rack structure when it collides either at the base or at the top of the rack structure.

• The Journal of Engineering Geology
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• v.19 no.3
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• pp.287-294
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• 2009

To be design the slope, the area distributed the mica schist which was metamorphosed by shale or mudstone must carefully consider the stability. Mica schist is another unstable rock for slope by schistosity, cleavage, axial plane of a fold etc. In general mica schist contains the swelling clay minerals such as smectite, vermiculite and montmorillonite. These minerals make the slope unstable. At OO tunnel construction area for the rail way of the Kyungbu high speed train, the slope of mica schist is very unstable by the distribution phenomena of the discontinuous plane such as joints which are 1-5 cm spacing and thrust and strike-slip fault. By the drilling core of this area, most RQD have 0-20%.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.6
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• pp.1886-1896
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• 1991

This paper presents a method to predict the flying height of the head slider in a hard disk drive. Quantitative predicts of the flying height according to the variations of the external load and the disk velocity have been done by numerical computation. In addition, the magnitude of the external load to keep flying height constant were also suggested. The Modified Reynolds' equation driven from hydrodynamic lubrication theory under slip flow condition was used to describe air-bearing system under the slider. To solve the equation, a Finite Volume Method (FVM) has been applied. To determine the final minimum flying height and pitch angle of the head slider, the Secant iteration method is used which update initial guess of the minimum flying height and pitch angle of the slider. In this study, the model head slider has been selected from a real hard disk drive which is equipped in many commercial personal computers. As a result, as the disk velocity increases at constant external load, the minimum flying height and the pitch angle increase due to the in crease of the air-bearing force at the bottom of slider.

• Journal of Korean Society of Steel Construction
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• v.14 no.6
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• pp.803-811
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• 2002

Current composite steel and concrete bridges are designed using full-interaction theory assuming there is no relative slip, between the steel and concrete components along their interface, because of the complexities of partial-interaction analysis techniques. However, in the assessment of existing composite bridges this simplification may not be warranted as it is often necesary to extract the correct capacity and endurance from the structure. This may only be achieved using partial-interaction theory which tuly reflects the behaviour of the structure. In this paper, Parametric analyses have been carried out in order to confirm the partial-interaction curvatures with deflection effect using the finite element method. Therefore, the model is considered for simply supported steel and concrete composite bridges with a uniform distribution of connectors subjected to a single concentrated load. For the case studies, this study applicate a parameters such as the number and space of stud shear connector and elastic modulus of concrete slabs. From this study, it is known that partial-interaction effect was in the increase to the increasing the deflection of composite bridges, and stiffness and strength of slab concrete considering the occurrence of crack effect seriously to the partial-interaction behavior.

• Journal of the Earthquake Engineering Society of Korea
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• v.16 no.1
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• pp.27-35
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• 2012

In this study, the ground motion was synthesized using the finite fault model by the stochastic green function method, and the difference in the ground motions was evaluated by using various values of the source parameters. An earthquake with a moment magnitude of 6.5 was assumed for the example fault model. The distribution of the slip in the fault plane was calculated using the statistical data of the asperity area. The source parameters considered in this study were the location of the hypocenter in the fault plane and the ratio of the rupture to the shear wave velocity, the rise time, the corner frequency of the source spectrum, and a high frequency filter. The values of the parameters related to the stochastic element source model were adjusted for different tectonic regions, and the others were selected for several possible cases. The response spectra were constructed from the synthesized ground motion time history and compared with the different parameter values. The frequency range affected by each parameter and the differences of the spectral accelerations were evaluated.

• Geotechnical Engineering
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• v.7 no.2
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• pp.51-66
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• 1991

In the stability analysis of hillside slopes, the roots of vegetation have been considered to act as a soil reinforcement. In order to predict the amount of increase in soil shear resistance, produced by tensile strength of roots that intersect a potential slip surface in hillside slopes, new soil -root interaction models are proposed in this paper. For this purpose, firstly, laboratary teats and in-situ tests wert performed on soil-root systems, and experimental results were compared with a couple of soil-root interaction models which had been proposed by Gray, Waldron, and Wu etc. Based on this comparison, a new soil-root interaction model is proposed. Secondly, a probabilistic soil-root model is proposed based on statistical analysis considering random nature of root distribution, root characteristics, and soil-root interactions. Finally, to examine the effect of this root reinforcement system on stability of hillside slopes, a simple three-dimensional stability analysis was performed, and it was shown that root reinforcement had a significant stabilizing influence on shallow slips rather than deep slips in hillside slopes.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.17 no.4
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• pp.379-388
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• 1995

This study was based on a series of 369 patients with Oral and Maxillofacial injuries treated at Kumi Hospital, College of Medicine, Soon-Chun-Hyang University from Jan. 1992 to Dec. 1994. The results obtained were as follows : 1. The number of male patient was 310 and that of female was 59, leading to 5.3 : 1 of male-female ratio, and the 3rd decade was the highest age group in incidence. 2. Weekly incidence was the highest in Sun. & Sat. and monthly incidence was the highest in Nov.& Oct. 3. Causes as follows : traffic accident 41.9%, slip& fall down 25.4%, human trouble 16.5%, industrial accident 7.5%, sports 6.7%, etc. 4. Site distribution as follows : mandible fracture 32.3%, maxilla fracture 4.8%, zygoma fracture 21.4%, nasal bone fracture 34.1%, orbital& ethmoidal fracture 4.6%. 5. The most common site of mandible was symphysis & angle, and the ratio of OR & CR was 1.3 : 1. 6. The most common site of maxilla was Le Fort 1, 2, and the ratio of OR & CR was 3 : 1. 7. The most common site of zygoma was body, the ratio of OR & CR was 3.3 : 1. 8 . The mean period of intermaxillary fixation was 4.33weeks. 9. Combined injury in facial fracture was 35.8% : The facial fracture were most frequently combind with head & neck(47.0%), upper extremities and abdomen(9.8%). 10. The mean elapsed time from injury to hospital was 1.9days, and that to operation was 5.1days. 11. The mean number of combined teeth injury was 0.6, and percent of combined soft tissue injury of face was 51.3%. 12. Post-operative complication occurred in 4 out of 323 cases. all of that was infection.

• Earthquakes and Structures
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• v.15 no.2
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• pp.113-122
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• 2018

This study presents a new beam-column model comprising material nonlinearity and joint flexibility to predict the nonlinear response of reinforced concrete structures. The nonlinear behavior of connections has an outstanding role on the nonlinear response of reinforced concrete structures. In presented research, the joint flexibility is considered applying a rotational spring at each end of the member. To derive the moment-rotation behavior of beam-column connections, the relative rotations produced by the relative slip of flexural reinforcement in the joint and the flexural cracking of the beam end are taken into consideration. Furthermore, the considered spread plasticity model, unlike the previous models that have been developed based on the linear moment distribution subjected to lateral loads includes both lateral and gravity load effects, simultaneously. To confirm the accuracy of the proposed methodology, a simply-supported test beam and three reinforced concrete frames are considered. Pushover and nonlinear dynamic analysis of three numerical examples are performed. In these examples the nonlinear behavior of connections and the material nonlinearity using the proposed methodology and also linear flexibility model with different number of elements for each member and fiber based distributed plasticity model with different number of integration points are simulated. Comparing the results of the proposed methodology with those of the aforementioned models describes that suggested model that only uses one element for each member can appropriately estimate the nonlinear behavior of reinforced concrete structures.