• Journal of the Korea Safety Management & Science
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• v.8 no.3
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• pp.143-157
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• 2006

The purpose of this thesis is to develop a heuristic algorithm evaluating the layout to maximize number of boxes when a single-box-type is packed into a container. Actually because three-dimensional problems are involved in NP-complete, much study has been focused on heuristic algorithms. The basic concept of this study is as follows. The problem is solved as palletizing problems with each side of the container respectively. By using the height of boxes, the problem is extended to a three-dimensional problem. Consequently, through this thesis, we can get good solution and the result is displayed by three-dimensional computer graphic.

• Steel and Composite Structures
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• v.2 no.1
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• pp.51-66
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• 2002

Perforated shear connectors currently used in composite steel and concrete structures are described and evaluated. Modifications of the perforated connector suitable for common use injavascript:confirm_mark('abe', '1'); civil and bridge engineering are proposed. The connectors were tested in laboratories of CTU Prague for shear load capacity. Push tests of connectors with 32 mm openings and with 60 mm openings, both in normal and lightweight concrete of different strength characteristics and with different transverse reinforcement, were carried out. The experimental study also dealt with the connector height and parallel arrangement of two connectors and their influence on shear resistance. While extensive tests with static loading were carried out, fatigue tests under repeated loading are still in progress. After statistical evaluation of the experimental results and comparisons with other available data the authors developed reasonable shear resistance formulas for all proposed arrangements.

• Journal of Technologic Dentistry
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• v.35 no.4
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• pp.281-286
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• 2013

Purpose: Surface modification is important techniques in modern dental and orthopedic implants. This study was performed to try embedding of bioactive materials in porous Ti implants. Methods: Porous Ti implant samples were fabricated by sintering of spherical Ti powders in a high vacuum furnace. It's diameter and height were 4mm and 20mm. Embedding process was used to suction and vacuum chamber. Loading properties of porous Ti implants were evaluated by scanning electron microscope(SEM), confocal laser scanning microscope(CLSM), and UV-Vis-NIR spectrophotometer. Results: Internal pore structure was formed fully open pore. Average pore size and porosity were $10.253{\mu}m$ and 17.506%. Conclusion: Porous Ti implant was fabricated successfully by sintering method. Particles are necking strongly each other and others portions were vacancy. This porous structure can be embedded to bioactive materials. Therefore bioactive materials will be able to embedding to porous Ti implants. Bioactive materials embedding in the porous Ti implant will induced new bone faster.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.586-591
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• 2004

A load/unload mechanism is applied to most small form factor hard disk drives. Loading velocity is ones of the most important factors to ensure the reliability of the load/unload operations. Especially, the lower the flying height of the head becomes, the more important the accuracy of the loading velocity control becomes. Because there is no sensor during the load/unload operations, BEMF voltage is used to sense the head velocity. To measure BEMF voltage, a simple circuit is added to the load/unload HDD control system. Overall acceptable results are obtained by using the simple PI controller but the errors from the target velocity occur when the head moves along the ramp and then reaches the disk. Feedforward profile and disturbance observer are used to remove those errors effectively.

• Steel and Composite Structures
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• v.23 no.4
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• pp.445-452
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• 2017

This study intends to improve the structural details of the anchors in the conventional CFT column-to-foundation connection. To that goal, finite element analysis is conducted with various design variables (number and embedded length of deformed bars, number, aspect ratio, height ratio and thickness ratio of ribs) selected based upon the results of loading test and strength evaluation. The finite element analysis is performed using ABAQUS and the analytical results are validated by comparison with the load-displacement curves obtained through loading test applying axial and transverse loads. The behavioral characteristics of the numerical model according to the selected design variables are verified and the corresponding results are evaluated.

• Journal of the Korean Institute of Landscape Architecture
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• v.26 no.2
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• pp.166-180
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• 1998

In a city where the greenery always lacks landscaping roofs of existing buildings offers a way to solve the problem. But the most serious problem that poses is the matter of load limit. At present most existing buildings have the loading capacity of 200 kg/$m^2$ or less on their roofs. If the natural soil is used the loading capacity is easily surpassed because it simply is too heavy. To alleviate this problem it is realized to introduce the light weight artificial soil. The specific gravity of light soil is 0.65 whereas the natural soil is 1.8 when wet. It is three times lighter than the natural soil, thus eases the burden to the roof. The next problem to be confronted is the plant species to plant. It is possible to plant trees but they soon outgrow the loading capacity by weighing 8 times heavier in 10 years. Therefore shrubs and perennials are suggested to be planted because they don't weigh much even when they reach the mature height. The last problem is the stress put on roofs by the weight of the users. By some unexpected event the crowd gathered on a weak roof can cause the structural damage or even the collapse of the roof. The avoid the possibility of collapse a plaza or big pocket should not be designed in a roof garden because they hold crowd. By following the suggested means the old roofs of existing buildings can turn into the urban oases in the sky.

• Korean Journal of Applied Biomechanics
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• v.31 no.2
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• pp.113-118
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• 2021

Objective: The purpose of this study was to investigate differences of landing strategy between people with or without chronic ankle instability (CAI) during double-leg drop landing. Method: 34 male adults participated in this study (CAI = 16, Normal = 18). Participants performed double-leg drop landing task on a 30 cm height and 20 cm horizontal distance away from the force plate. Lower Extremities Kinetic and Kinematic data were obtained using 8 motion capture cameras and 2 force plates and loading rate was calculated. Independent samples t-test were used to identify differences between groups. Results: Compared with normal group, CAI group exhibits significantly less hip internal rotation angle (CAI = 1.52±8.12, Normal = 10.63±8.44, p = 0.003), greater knee valgus angle (CAI = -6.78±5.03, Normal = -12.38 ±6.78, p = 0.011), greater ankle eversion moment (CAI = 0.0001±0.02, Normal = -0.03±0.05, p = 0.043), greater loading Rate (CAI = 32.65±15.52, Normal = 18.43±10.87, p = 0.003) on their affected limb during maximum vertical Ground Reaction Force moment. Conclusion: Our results demonstrated that CAI group exhibits compensatory movement to avoid ankle inversion during double-leg drop landing compared with normal group. Further study about how changed kinetic and kinematic affect shock absorption ability and injury risk in participants with CAI is needed.

• Earthquakes and Structures
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• v.23 no.1
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• pp.13-21
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• 2022

Masonry constructions exhibit uncertain behaviors under dynamic effects such as seismic action. Complex issues arise in the idealization of structural systems of buildings having different material types and mechanical properties. In this study, the structural behavior of a vaulted masonry building constructed using full clay brick and lime-based mortar and sitting on consecutive arches was investigated by experimental and numerical approaches. The dimensions of the structure built in the laboratory were 391 × 196 cm, and its height was 234 cm. An incremental repetitive loading was applied to the prototype construction model. Along the gradually increasing loading pattern, the load-displacement curves of the masonry structure were obtained with the assistance of eight linear displacement transducers. In addition, crack formation areas, and relevant causes of its formation were determined. The experimental model was idealized using the finite element method, and numerical analyses were performed for the area considered as linear being under similar loading effect. From the linear analyses, the displacement values and stress distribution of the numerical model were obtained. In addition, the effects of tie members, frequently being used in the supports of curved load-bearing elements, on the structural behavior were examined. Consequently, the experimental and numerical analysis results were comparatively evaluated.

• Journal of Periodontal and Implant Science
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• v.45 no.5
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• pp.169-177
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• 2015

Purpose: Despite the high success rates of endosseous dental implants, their placement is restricted according to the height and volume of bone available. The use of short or mini dental implants could be one way to overcome this limitation. Thus, this study aimed to compare standard, short, and mini dental implants with regard to associated clinical parameters and peri-implant crevicular fluid (PICF) levels of cathepsin-K (CTSK), RANK ligand (RANKL), and osteoprotegerin (OPG), after prosthodontic loading. Methods: A total of 78 non-submerged implants (Euroteknika, $Aesthetica^{+2}$, Sallanches, France) were installed in 30 subjects (13 male, 17 female; range, 26-62 years) who visited the clinic of the Periodontology Department, Faculty of Dentistry, Selcuk University. Sampling and measurements were performed on the loading date (baseline) and 2, 14, and 90 days after loading. Assessment of the peri-implant status for the implant sites was performed using the pocket probing depth (PPD), modified plaque index, modified gingival index, modified sulcular bleeding index, and radiographic signs of bone loss. PICF samples collected from each implant were evaluated for CTSK, RANKL, and OPG levels using the ELISA method. Keratinized tissue and marginal bone loss (MBL) were also noted. Results: Clinical parameters statistically significantly increased in each group but did not show statistical differences between groups without PPD. Although implant groups showed a higher MBL in the upper jaw, only the standard dental group demonstrated a statistically significant difference. At 90 days, the OPG:sRANKL ratio and total amounts of CTSK for each group did not differ from baseline. Conclusions: Within the limitations of this study, both short and mini dental implants were achieving the same outcomes as the standard dental implants in the early period after loading.

• Journal of Korean Society of Steel Construction
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• v.26 no.4
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• pp.277-288
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• 2014

In this study, the local displacement and moment characteristics of a plate stiffened with closed ribs are analyzed according to the dimensions of stiffened plates. The analyzed results of various stiffened plates under square distributed load show that the effect of the loading panel width to the local behavior is dominant but that of the next panel width is very small. And the local behavior of reference stiffened plates can be expressed by the angle between the plate and the rib, and that of other stiffened plates can be obtained by multiplying ratio functions of the loading panel width, plate thickness, rib thickness, rib height and next panel width and they give good results. Applying ratio functions to other loading sizes shows that the applicability of ratio functions except for the loading panel width is proved and the modified ratio functions of the loading panel width improve error ratios. Therefore, the local displacement and moments of a plate stiffened with closed ribs can easily achieve proper results regardless of the dimensions using ratio functions proposed in this study.