• Wind and Structures
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• v.11 no.1
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• pp.1-18
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• 2008

Interference effects in five square tall buildings arranged in an L- or T-shaped pattern are investigated in the wind tunnel. Mean and fluctuating shear forces, overturning moments and torsional moment are measured on each building with a force balance mounted at its base. Results are obtained at two values of clear separation between adjacent buildings, at half and a quarter building breadth. It is found that strong interference effect exists on all member buildings, resulting in significant modifications of wind loads as compared with the isolated single building case. Sheltering effect is observed on wind loads acting along the direction of an arm of the "L" or "T" on the inner buildings. However, increase in these wind loads from the isolated single building case is found on the most upwind edge building in the arm when wind blows at a slight oblique angle to the arm. The corner formed by two arms of buildings results in some wind catchment effect leading to increased wind pressure on windward building faces. Interesting interference phenomena such as negative drag force are reported. Interference effects on wind load fluctuations, load spectra and dynamic building responses are also studied and discussed.

• The Journal of Advanced Prosthodontics
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• v.13 no.4
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• pp.216-225
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• 2021

PURPOSE. The aim of this study is to evaluate the effects of canine guidance occlusion and group function occlusion on the degree of stress to the bone, implants, abutments, and crowns using finite element analysis (FEA). MATERIALS AND METHODS. This study included the implant-prosthesis system of a three-unit bridge made of monolithic zirconia and hybrid abutments. Three-dimensional (3D) models of a bone-level implant system and a titanium base abutment were created using the original implant components. Two titanium implants, measuring 4 × 11 mm each, were selected. The loads were applied in two oblique directions of 15° and 30° under two occlusal movement conditions. In the canine guidance condition, loads (100 N) were applied to the canine crown only. In the group function condition, loads were applied to all three teeth. In this loading, a force of 100 N was applied to the canine, and 200-N forces were applied to each premolar. The stress distribution among all the components of the implant-bridge system was assessed using ANSYS SpaceClaim 2020 R2 software and finite element analysis. RESULTS. Maximum stress was found in the group function occlusion. The maximum stress increased with an increase in the angle of occlusal force. CONCLUSION. The canine guidance occlusion with monolithic zirconia crown materials is promising for implant-supported prostheses in the canine and premolar areas.

• International Journal of Naval Architecture and Ocean Engineering
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• v.12 no.1
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• pp.226-240
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• 2020

This paper presents an experimental investigation of asymmetric impact effects on hydroelastic responses. A 1:64 scaled segmented ship model with U-shape open cross-section backbone was newly designed to meet elastic similarity conditions of vertical, horizontal and torsional stiffness simultaneously. Different wave heading angles and wavelengths were adopted in regular wave test. In head wave condition, parametric rolling phenomena happened along with asymmetric slamming forces, the relationship between them was disclosed at first time. The impact forces on starboard and port sides showed alternating asymmetric periodic changes. In oblique wave condition, nonlinear springing and whipping responses were found. Since slamming phenomena occurred, high-frequency bending moments became an important part in total bending moments and whipping responses were found in small wavelength. The wavelength and head angle are varied to elucidate the relationship of springing/whipping loads and asymmetric impact. The distributions of peaks of horizontal and torsional loads show highly asymmetric property.

• Journal of Korean Foot and Ankle Society
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• v.7 no.1
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• pp.7-12
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• 2003

Purpose: To study the relationship of the 1st to 2nd intermetatarsal angle(1-2 IMA) between the intra-operative and weight bearing postoperative anterior-posterior(AP) radiography, and evaluate the intra-operative predictability for the postoperative 1-2 IMA after proximal metatarsal osteotomy(PMO) in the hallux valgus deformity. Materials and Methods: 20 cases of moderate to severe hallux valgus patients were included in this study. After the oblique PMO(Ludloff procedure) was performed and the osteotomy site was fixed temporarily, the AP view was taken intra-operatively. About 10 weeks after surgery, postoperative weight bearing AP view was taken. The pre -. intra -, and postoperative 1-2 IMAs were compared and ana lysed statistically. Results: The 1-2 IMAs of the weight bearing preoperative, non-weight bearing intra-operative and weight bearing postoperative AP view were $15.9^{\circ}{\pm}1.8^{\circ},\;4.7^{\circ}{\pm}2.1^{\circ}$, and $6.8^{\circ}{\pm}2.5^{\circ}$ (Mean${\pm}$SD) respectively. The postoperative 1-2 IMA was greater than intra-operative measurement by $2.1^{\circ}{\pm}1.8^{\circ}$ (range; $-1^{\circ}$ to $6^{\circ}$) which was stastistically significant(p<0.05). To get less than $9^{\circ}$ postoperatively as an average normal, intra-operative 1-2 IMA should be within $3.8^{\circ}$ to $5.2^{\circ}$ (95% confidence interval), and intra-operative 1-2 IMA should be within $3.4^{\circ}{\pm}$to $5.4^{\circ}$(95% confidence interval) to get more than $6^{\circ}$ difference between preoperative and postoperative 1-2 IMA, which is regarded as more than average correction by the distal metatarsal osteotomy. Conclusion: In hallux valgus surgery, it should be considered that intra-operative 1-2 IMA was less than the postoperative. To achieve postoperative 1-2 IMA less than $9^{\circ}$ and more than correction angle of $6^{\circ}$, it is suggested that the intra-operative 1-2 IMA should be measured less than about $5^{\circ}$.

• The Journal of Korean Academy of Prosthodontics
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• v.50 no.1
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• pp.1-9
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• 2012

Purpose: The purpose of this study was to investigate the effects of a mouthguard on stress distribution under mandibular impact. Materials and methods: The FEM model of head consisted of skull, maxilla, mandible, articular disc, teeth, and mouthguard. The impact locations on mandible were gnathion, the center of inferior border, and the anterior edge of gonial angle. And the impact directions were vertical, oblique ($45^{\circ}$), and horizontal. The impact load was 800 N for 0.1 sec. Results: When vertical impact was applied, the similar stress and the distribution pattern was occurred without the relation of the mouthguard use (P>.05). The model with mouthguard was dispersed the stress to the teeth, the facial bone and the skull when the oblique ($45^{\circ}$) impacts were happened. However, the stress was centralized on the teeth in the model without mouthguard(P<.05). The model with mouthguard was dispersed the stress to the teeth, the facial bone and the skull when the horizontal impacts was occurred. However, the stress was centralized on the teeth without mouthguard (P<.05). For all impact loads, stress concentrated on maxillary anterior teeth in model without mouthguard, on the contrary, the stress was low in the model with mouthguard and distributed broadly on maxillary anterior teeth, facial bone, and skull. Conclusion: The mouthguard was less effective at shock absorbing when vertical impact was added. However, it was approved that mouthguard absorbed the shock regarded to the oblique ($45^{\circ}$) and horizontal impact by dispersing the shock to the broader areas and decreasing the stress.

• The Journal of Korean Society for Radiation Therapy
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• v.33
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• pp.99-108
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• 2021

Purpose: The goal of this study is to evaluate usefulness of noninvasive method instead of previous inserting Fiducial Marker Method when performing Stereotactic Partial Breast Irradiation in CyberKnife. Material and methods: For consistency of Imaging Center, we evaluated both oblique images at angle 45 and 315 acquired from 2D Simulator and CyberKnife quantitatively through dice similarity coefficient. Also, location reproducibility of Surface Fiducial Marker was analyzed from 2D Simulator, treatment plans and CyberKinfe images by using 8 Fiducial Markers made of gold attached to ATOM Phantom based on our institution's protocols. Results: The results of the estimated consistency were 0.87 and 0.9 at the oblique angle 45 and 315, respectively. For location consistency of Surface Fiducial Markers, values of horizontal vertical direction of left breast were Superior/Inferior 0.3 mm, Left/Right -0.3 mm, Anterior/Posterior 0.4 mm, and the values of rotational direction were Roll 0.3 °, Pitch 0.2 °, Yaw 0.4 °. The values of horizontal vertical direction of right breast were Superior/Inferior -0.1 mm, Left/Right -0.1 mm, Anterior/Posterior -0.1 mm, and the values of rotational direction were Roll 0.2°, Pitch 0.1°, Yaw 0.1°. Conclusions: We expect that the protocols used by Surface Fiducial Markers when performing Stereotactic Partial Breast Irradiation in CyberKnife will provide protection from pain and cut expenses for treatment and reduce treatment errors and make treatment more accurate by suggesting treatment protocols based on high consistency of Imaging Center and reproducibility of Fiducial Markers.

• Physical Therapy Korea
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• v.15 no.2
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• pp.54-63
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• 2008

The purpose of this study was to examine the effect of the hip internal rotation on knee extensor and hip abductor electromyographic (EMG) activity during stair up and stair down mobility. Eighteen healthy subjects were recruited. All subjects performed stair up and down movements on a step of 30cm height while maintaining the hip in neutral (condition 1) and hip in internal rotation (condition 2). Surface EMG activity was recorded from five muscles (gluteus maximus, vastus lateralis (VL), vastus medialis oblique (VMO), posterior gluteus medius (Gmed), and tensor fascia latae (TFU)) and hip internal rotation angle was measured using a three dimensional motion analysis system The time period for stair up and down was normalized using the MatLab 6.5 program, and EMG activity was normalized to the value of maximal voluntary isometric contraction (%MVIC). The EMG activities according to the hip rotation (neutral or internal rotation) during the entire time period of stair up and down in each phase were compared using a paired t-test. During the entire period of stair up, the EMG activities of VL and TFL in condition 2 were significantly greater than in condition 1 (p<.05). During the entire period of stair down, the EMG activities of VL and TFL in condition 2 were significantly greater than in condition 1 (p<.05). However, the EMG activities of the other muscles were not significantly different between the conditions (p>.05). These results suggest that the stair up and down maintaining hip internal rotation was could be a contributing factor on patellar lateral tracking.

• The Korean Journal of Pain
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• v.22 no.1
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• pp.47-51
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• 2009

Background: The blind sacroiliac joint (SIJ) block cannot always be performed accurately; it is commonly performed in the office based setting because intraarticular and periarticular injections are effective for SIJ pain. However, knowledge on the surface anatomy of the SIJ is lacking. The purpose of this study was to analyze the surface anatomical location of the posterior-inferior margin of the SIJ. Methods: After informed consent was obtained, fifty patients undergoing SIJ block in the prone position were examined. The oblique angles where the anterior-inferior margin and the posterior-inferior margin of the SIJ overlap on X-ray were evaluated. In addition, the surface anatomical relationships between the posterior-inferior margin of the SIJ on X-ray and the posterior superior iliac spine (PSIS) and sacral hiatus by palpation were assessed. Results: The oblique angle was $5.4{\pm}2.9^{\circ}$. The vertical and transverse distance between the posterior-inferior margin of the SIJ and PSIS were $3.8{\pm}0.8cm$ and $0.9{\pm}0.6cm$, respectively. The vertical and transverse distance between the posterior-inferior margin of the SIJ and the midpoint of the sacral hiatus were $3.4{\pm}0.7cm$ and $3.9{\pm}0.6cm$, respectively. Only the vertical distance between the posterior-inferior margin of the SIJ and PSIS showed significant difference between the male and the female groups (P = 0.0016). Conclusions: The measurements in this study can be used as a reference standards for the blind SIJ block.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.8
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• pp.555-563
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• 2020

Foward-swept wings are known to possess superior aerodynamic performance compared to the conventional straight wings. However major concerns regarding forward-swept wings include divergence at lower airspeeds which require careful consideration at the design stage. As an endeavor to overcome such drawbacks, aeroelastic tailoring is attempted. In order to find an optimal ply sequence, recursive aeroelastic analyses is conducted and one-dimensional beam analysis coupled with simple aerodynamics is used for the improved computational efficiency and modelling convenience. The analysis used in this paper, DYMORE and analytic formula, both use one-dimensional beam model for the structure. Cross-sectional analysis for multi-cell NACA0015 airfoil section is conducted using VABS and oblique function is used for the sweep angle. Throughout the present aeroelastic tailoring, the maximum divergence speed of 290.2m/s is achieved which is increased by approximately 43% than that for the conventional ply configuration.

• Physical Therapy Rehabilitation Science
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• v.8 no.1
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• pp.45-51
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• 2019

Objective: The purpose of this study was to investigate the muscle activity ratio of the lower limb according to changes in straight leg raise (SLR) test angles on hamstring muscle shortening during squat exercises. Design: Randomized controlled trial. Methods: The subjects were 14 healthy adults who were informed of and agreed to the method and purpose of the study. The participants were classified into SLR groups according to two angles (over $80^{\circ}$ or under $80^{\circ}$) assessed using the SLR tests. After training and practicing the wall squat posture to be applied to the experiment, electromyography (EMG) was used to measure changes in muscle activity during the performance of a wall squat. After stretching, a sequence of pre-stretch tests were performed again, and the active and passive SLR tests were also reconducted; thereafter, a wall squat was performed again by attaching EMG electrodes. The EMG results before and after stretching were compared. Results: The muscle activity of the vastus lateralis oblique muscle increased in both groups. The muscle activity of the vastus medialis oblique muscle decreased in over both group. Rectus femorus activity increased in the under 80-degree groups but decreased in the over 80-degree group. The muscle activity of the biceps femoris muscle decreased after stretching in the over 80-degree group and increased in the under 80-degree group, and the semitendinosus muscle activity after stretching was decreased. The quadriceps-to-hamstring muscle (Q:H) ratio before and after stretching between groups showed that the hamstring muscle ratio decreased after stretching in both groups. Conclusions: The results of this study showed that the Q:H ratio before and after stretching between groups was not significantly different.