• Journal of the Korean Magnetics Society
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• v.8 no.5
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• pp.308-316
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• 1998

In this paper, the effects of lateral displacement on the thrust, lift force and (guide force) are investigated by 3-D Finite Element Analysis (FEA) in controlled-PM LSM which has some strong points that electrical power can be minimized and the thrust and lift force can be simultaneously obtained. The variations of airgap flux density and the forces concerning lateral displacement have been analyzed and the effect of lateral displacement and airgap length on the motor performance have been investigated in detail by analysis and experiment results. As the result of this study, the characteristics of PM-LSM concerning with the change of lateral placement and airgap have been made clear quantitatively.

• Journal of the Korean Society of Clothing and Textiles
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• v.42 no.6
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• pp.1002-1015
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• 2018

In this study, we analyzed the results of virtual clothing simulation according to the difference in the lateral neck point as well as the front and back shoulder inclination angles of the bodice foundation. Lim's (2016) (S) and Lee's (1999) method (L) were selected as the different setting for the lateral neck point. S1, S2, L1 and L2 were developed by changing the shoulder inclination angles. The SND and LND were developed by removing the darts in the S and L, respectively; in addition, the SND1, SND2, LND1, and LND2 were developed with different shoulder inclination angles. The results of S and L were similar with only slight differences observed in the armhole shape. However, the results of SND and LND were very different. The patterns of the S series were similar to each other, but the patterns of the L series were different. In addition, the patterns of the SND and LND series could not find a similar trend.

• Journal of Periodontal and Implant Science
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• v.29 no.1
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• pp.233-249
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• 1999

Primary fixation is one of the most important factor in establishing adequate osseointegration between implant and bone. To evaluate the initial healing response of bone around implants without primary bone contact, this study was designed to create considerable space between implant and bone in 5 mongrel dogs, about 1-year old. After 3 holes of 6.0mm in diameter were prepared at the femur neck of the dogs, commercially pure titanium thread type implants(STERI-$OSS^{(R)}$), 8mm in length and 3.8mm, 5.0mm and 6.0mm in diameter, were inserted. Implants were supported by only nonresorbable membrane($Teflon^{(R)}$), and the penetration of upper soft tissue into the gap was inhibited by it. The each implant was positioned in the center of the drilled hole. 9 implants with different diameters were inserted in 3 dogs for histologic observation, and 12 were inserted in 2 dogs for mobility test and removal torque test.Fluorescent dyes were injected in order of Doxycycline, Alizarin Red S, and Calcein at intervals of 2 weeks. At 4-, 8-, and 12-week after placement, 3 dogs were sacrificed for histologic observation, and at 8- and 12-week after placement, 2 dogs were sacrificed for mobility test using $Periotest^{(R)}$ (Simens AG, Bensheim, Germany) and torque test using Autograph AGS-1000D $series^{(R)}$(Japan). The result were as follows: 1. The wider the gap between bone and implant was, the less bone maturity was, and the later osseointegration was occurred. Trabecular direction of new bone around implant was changed from parallel to perpendicular to the implant, and the gap was filled with new bone, over time. 2. There was a decreasing tendency over time in the mobility of all implants, but the wider gap between bone and implant was, the smaller decrease of the mobility was. 3. There was a increasing tendency over time in the removal torque gauge of all implants, and the wider gap was, the smaller increase of the removal torque gauge was. The results suggest that osseointegration in case of implant without primary bone contact may be obtained by guided bone regeneration technique with prolonged healing period, but the time of second surgery should be considered carefully.

• Journal of Periodontal and Implant Science
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• v.41 no.2
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• pp.86-91
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• 2011

Purpose: The aim of this study was to analyze the short-term predictability and reliability of Astra Tech implants according to the demographical distribution of patients and condition of implant sites and location of implants. Methods: Among patients treated with Astra Tech implant (Astra Tech AB) in the Department of Periodontology at the Dental Hospital of Yonsei University of College of Dentisry and K Dental Clinic from May 2004 to March 2009, 195 implants in 98 patients which had been restored more than 6 months ago were reviewed in this study. Following data were reviewed from patient charts and implants success rate was examined: 1) patient type and implant location, 2) bone status at the implant site, 3) diameter and length of the placed implants, 4) presence or absence of bone augmentation and types of the augmentation. Results: The results from this study are as follows: 1) most implants were placed in the molar area, especially 1st molar area of maxilla, 2) most implants were placed at $D_2$ and $D_3$ bone type, 3) most implants were placed in areas of B and C bone quantity, 4) autogenous and alloplastic bone graft and artificial membrane were used for placement of 74 implants. Conclusions: Short-term survival rate of Astra Tech implants was 100%.

• Journal of Korean Neurosurgical Society
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• v.49 no.6
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• pp.351-354
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• 2011

Objective : This investigation was conducted to evaluate a new, safe entry point for the C2 pedicle screw, determined using the anatomical landmarks of the C2 lateral mass, the lamina, and the isthmus of the pars interarticularis. Methods : Fifteen patients underwent bilateral C1 lateral mass-C2 pedicle screw fixation, combined with posterior wiring. The C2 pedicle screw was inserted at the entry point determined using the following method : 4 mm lateral to and 4 mm inferior to the transitional point (from the superior end line of the lamina to the isthmus of the pars interarticularis). After a small hole was made with a high-speed drill, the taper was inserted with a 30 degree convergence in the cephalad direction. Other surgical procedures were performed according to Harm's description. Preoperatively, careful evaluation was performed with a cervical X-ray for C1-C2 alignment, magnetic resonance imaging for spinal cord and ligamentous structures, and a contrast-enhanced 3-dimensional computed tomogram (3-D CT) for bony anatomy and the course of the vertebral artery. A 3-D CT was checked postoperatively to evaluate screw placement Results : Bone fusion was achieved in all 15 patients (100%) without screw violation into the spinal canal, vertebral artery injury, or hardware failure. Occipital neuralgia developed in one patient, but this subsided after a C2 ganglion block. Conclusion : C2 transpedicular screw fixation can be easily and safely performed using the entry point of the present study. However, careful preoperative radiographic evaluation, regardless of methods, is mandatory.

• The Journal of Advanced Prosthodontics
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• v.9 no.6
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• pp.470-475
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• 2017

PURPOSE. The purpose of this study was to identify the complex course of the mandibular canal using 3D reconstruction of microCT images and to provide the diagram for clinicians to help them understand at the interforaminal region in Korean. MATERIALS AND METHODS. Twenty-six hemimandibles obtained from cadavers were examined using microCT, and the images were reconstructed. At both the midpoint of mental foramen and the tip of anterior loop, the bucco-lingual position, the height from the mandibular inferior border, the horizontal distance between two points, and position relative to tooth site on the mandibular canal were measured. The angle that the mental canal diverges from the mandibular canal was measured in posterior-superior and lateral-superior direction. RESULTS. The buccal distance from the mandibular canal was significantly much shorter than lingual distance at both the mental foramen and the tip of anterior loop. The mandibular canal at the tip of anterior loop was significantly located closer to buccal side and higher than at the mental foramen. And the mental canal most commonly diverged from the mandibular canal below the first premolar by approximately $50^{\circ}$ posterior-superior and $41^{\circ}$ lateral-superior direction, which had with a mean length of 5.19 mm in front of the mental foramen, and exited to the mental foramen below the second premolar. CONCLUSION. These results suggest that it could form a hazardous tetrahedron space at the interforaminal region, thus, the clinician need to pay attention to the width of a premolar tooth from the mental foramen during dental implant placement.

• Journal of Dental Rehabilitation and Applied Science
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• v.34 no.1
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• pp.46-55
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• 2018

Oral rehabilitation of a patient having severe periodontitis with alveolar bone resorption and periodontal inflammation presents a challenge to clinicians. However, if appropriate implant placement according to the bone shape is selected, unnecessary bone grafting or soft tissue surgery can be minimized. In recent years, using cone beam CT and software, it has become possible to operate the planned position with the surgical guide made with 3D printing technology. This case was a 70 years old female patient who required total extraction of teeth due to severe periodontitis and performed a full-mouth rehabilitation with an implant - supported fixed prosthesis. During the surgery, the implant was placed in a flapless manner through a surgical guide. Immediate loading of the temporary prosthesis made by CAD/CAM method before surgery was done. Since then, we have produced customized abutments and zirconia prostheses, and have reported satisfactory aesthetic and functional recovery.

• The Journal of Korean Academy of Prosthodontics
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• v.57 no.1
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• pp.57-65
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• 2019

Computer aided design and manufacturing and implant surgery using a guide template improve restoration-driven implant treatment procedures. This case utilized those digital technologies to make definitive prostheses for a patient. According to the work flow of digital dentistry, cone beam computed tomography established the treatment plan, which was followed to make the guide template for implant placement. The template guided the implants to be installed as planned. The customized abutments and surveyed fixed restorations were digitally designed and made. The metal framework of the removable partial denture was cast from resin pattern using an additive manufacturing technique, and the artificial resin teeth were replaced with the zirconia onlays for occlusal stability. These full mouth rehabilitation procedures provided functionally and aesthetically satisfactory results for the patient.

• Geomechanics and Engineering
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• v.29 no.4
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• pp.471-486
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• 2022

The effect of segmental joints is one of main importance for the segmental lining design when tunnels are excavated by a mechanized process. In this paper, segmental tunnel linings are analyzed by two numerical methods, namely the Beam-Spring Method (BSM) and the Solid-Interface Method (SIM). For this purpose, the Tehran Subway Line 6 Tunnel is considered to be the reference case. Comprehensive 2D numerical simulations are performed considering the soil's calibrated plastic hardening model (PH). Also, an advanced 3D numerical model was used to obtain the stress relaxation value. The SIM numerical model is conducted to calculate the average rotational stiffness of the longitudinal joints considering the joints bending moment distribution and joints openings. Then, based on the BSM, a sensitivity analysis was performed to investigate the influence of the ground rigidity, depth to diameter ratios, slippage between the segment and ground, segment thickness, number of segments and pattern of joints. The findings indicate that when the longitudinal joints are flexible, the soil-segment interaction effect is significant. The joint rotational stiffness effect becomes remarkable with increasing the segment thickness, segment number, and tunnel depth. The pattern of longitudinal joints, in addition to the joint stiffness ratio and number of segments, also depends on the placement of longitudinal joints of the key segment in the tunnel crown (similar to patterns B and B').

• Journal of Trauma and Injury
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• v.27 no.2
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• pp.33-37
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• 2014

Central venous catheterization through a subclavian approach is indicated for some special purposes but it may cause many complications such as infection, bleeding, pneumothorax, thrombosis, air embolization, arrhythmia, myocardial perforation, and nerve injury. A case involving a mistaken central venous catheterization into the right vertebral artery through the subclavian artery is presented. A 33-year-old man who had deteriorated mentality after head injury underwent an emergency craniotomy for acute epidural hematomas on the right frontal and temporal convexities. His mentality improved rapidly, but he complained of continuous severe pain in the right posterior neck even though he had no previous symptom or past medical history of such pain. Three-dimensional cervical spine computed tomography (3D-CT) was performed first to rule out unconfirmed cervical injuries and it revealed a linear radiopaque material intrathoracically from the level of the 1st rib up to the level of C6 in the right vertebral foramen. An additional neck CT was performed, and the subclavian catheter was indwelling in the right vertebral artery through right subclavian artery. For the purpose of proper fluid infusion and central venous pressure monitoring, the subclavian vein catheterization had been performed in the operation room after general anesthesia induction before the craniotomy. Sufficient anatomical consideration and prudence is essential because inadvertent arterial cannulation at a non-compressible site is a highly risky iatrogenic complication of central venous line placement.