• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.05a
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• pp.12-13
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• 2021

Methods for the manufacture, erection, and assembly of heavy frame modules were proposed. Interferences among precast members were prevented by using bolted metal plates for dry precast beam-to-column joints during assembly with a clearance for tolerance implementing grouted concrete filler plates instead of metal filler plates. Clearances for tolerances were provided to avoid conflictions among components during erection phases. These gaps were, then, grouted by high-strength mortar. The constructability of new connections of a beam-to-column joint using bolted metal plates for precast structures was examined using a full-scale assembly test in which practical observations indicated that members could be aligned and placed accurately in both horizontal and vertical directions, leading to a fast and convenient assembling. Bolt holes of the endplate were properly aligned using couplers with 30 mm fastened length embedded in the columns. The assembly test demonstrated the erection safety and structural stability of the proposed joints that were without filler plates when they were subjected to heavy loads at the time of their erection. The facile and rapid assembly of precast beam-to-column connections with a 30 mm tolerance was observed. The proposed assembly method is rapid, sustainable, and resilient, replacing the conventional methods of concrete frame construction, offering a connection that can be used in constructing infrastructure, such as buildings and pipe-rack frames.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.3C
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• pp.209-218
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• 2006

In this study, stress and deformation of CFRD during its construction and impounding were analyzed and compared with its monitoring results. Moreover, deformation characteristics of CFRD after impounding were evaluated based on the settlement monitoring records of total 23 domestic and foreign CFRDs during construction and impounding. The investigation on the behavior of CFRD indicated that the influence of impounding on its stability was minimal although slight increases in vertical and horizontal stresses and strains were observed. Also, one method was proposed to predict a crest settlement from multi-layer settlements by applying the best fit method. It is expected that the results of this study would provide practical information for the design, construction, and management of CFRD.

• Steel and Composite Structures
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• v.49 no.2
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• pp.143-159
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• 2023

Recently, the design of scaffolding systems has garnered considerable attention due to the increasing number of scaffold collapses. These incidents arise from the underestimation of imposed loads and the site-specific conditions that restrict the application of lateral restraints in scaffold assemblies. The present study is committed to augmenting the buckling resistance of vertical support members, obviating the need for supplementary lateral restraints. To achieve this objective, experimental and computational analyses were performed to assess the axial load buckling capacity of steel props, composed of two hollow steel pipes that slide into each other for a certain length. Three full-scale steel props with various geometric properties were tested to construct and validate the analytical models. The total unsupported length of the steel props is 6 m, while three pins were installed to tighten the outer and inner pipes in the distance they overlapped. Finite Element (FE) modeling is carried out for the three steel props, and the developed models were verified using the experimental results. Also, theoretical analysis is utilized to verify the FE analysis. Using the FE-verified models, a parametric study is conducted to evaluate the effect of different inserted pipe lengths on the steel props' axial load capacity and lateral displacement. Based on the results, the typical failure mode for the studied steel props is global elastic buckling. Also, the prop's elastic buckling strength is sensitive to the inserted length of the smaller pipe. A threshold of minimum inserted length is one-third of the total length, after which the buckling strength increases. The present study offers a prop with enhanced buckling resistance and introduces an equation for calculating an equivalent effective length factor (k), which can be seamlessly incorporated into Euler's buckling equation, thereby facilitating the determination of the buckling capacity of the enhanced props and providing a pragmatic engineering solution.

• Journal of Dental Rehabilitation and Applied Science
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• v.39 no.3
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• pp.158-167
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• 2023

As digital technology has advanced in the field of dentistry, the use of computer-aided design/computer-aided manufacturing (CAD/CAM) has brought changes to the stages of dental treatment. The use of CAD/CAM technology in dental restoration offers clinical efficiency and convenience by reducing production time and appointment intervals, while also simplifying the fabrication process to reduce errors. In this case, digital replication and printing of temporary teeth were used to aid a patient with complex medical histories and physical disabilities. The final impression obtained with silicone impression material included information on the vertical dimension, centric relation, and the angle and length of the anterior teeth, which shortened the production time and appointment intervals and increased patient satisfaction. The final restoration was fabricated using milling and monolithic disc techniques, demonstrating appropriate stability, retention, and support, resulting in functional and aesthetic satisfaction.

• Journal of Aerospace System Engineering
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• v.18 no.1
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• pp.99-107
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• 2024

This paper introduces an emergency response system in urban air mobility scenarios. A biometric responsive smartwatch was designed to monitor passengers' real-time heart rates. When an anomaly was detected, the system would send an alert via Morse code vibration and voice notification. It was integrated with the assumed control system of the ROS environment and communicates to implement a system for generating the shortest path for emergency landing to a nearby vertical port during urban air mobility operations. System stability was verified through high-fidelity simulation environments and testing based on actual geographic locations. Our technology improved the reliability and convenience of urban air mobility, demonstrating its effectiveness through simulations and tests in real-world scenarios.

• Journal of Korean Dental Science
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• v.17 no.2
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• pp.64-74
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• 2024

This case report presents the long-term radiographic outcomes of a novel approach for simultaneous lateral augmentation and implant surgery. A 60-year-old male patient who required tooth extraction of the maxillary central and lateral incisors due to trauma visited the clinic. After tooth extraction, severe horizontal and vertical deficiencies occurred owing to atrophy of the alveolar ridge, and a simultaneous guided bone regeneration (GBR) procedure was planned along with the installation of two implants. In the present case, a modification of the conventional 'sandwich technique' was used by placing the mixture of autogenous bone chips and xenografts at the outermost layer to maximize the osteogenic potential at the coronal part of augmentation while applying solely xenografts at the inner layer. To enhance volumetric stability, an autogenous block of periosteum harvested from the maxillary tuberosity was incorporated between the two layers. Cone-beam computed tomography was performed at baseline and 3 years after the surgery to compare radiographic outcomes. Dehiscence after fixture installation was successfully observed at the re-entry of the surgery site. Three years after the surgery, average horizontal bone gains of 6.11 mm and 4.12 mm were observed in the maxillary central and lateral incisor areas, respectively. Healthy peri-implant mucosa and well maintained marginal bone levels were observed 8 years after the surgery, meeting the criteria for implant success. The findings of this case suggest that a substantial amount of horizontal bone gain can be obtained with a layered approach using autogenous bone materials and xenografts, highlighting the advantages of incorporating autogenous blocks into the simultaneous GBR procedure.

• The korean journal of orthodontics
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• v.29 no.2 s.73
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• pp.239-249
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• 1999

In orthognathic surgery to obtain proper functional and esthetic form after skeletal discrepancy treatment, precise diagnosis and treatment plan are essential. Especially in two jaw surgeries that have serious upper and lower jaw problems, maxilla and mandible are arranged in three dimensions. Based on the maxillary rearrangement, mandibular sagittal and transverse positions are determined, and thus new occlusal plane is established. The object of this study is to evaluate the stability of the indiviual ideal occlusal plane based on the architectural and structural craniofacial analysis of Delaires. The subjects of this study were 48 patients who underwent two jaw surgeries, and they were equally divided into two groups, A and B. A group was operated with ideal occlusal plane and B group was not. Two groups were compared at the preoperative, immediate postoperative (average 4.3days), and long-term postoperative (average 1.3years) lateral cephalometric radiographs. The following results were obtained: 1. ANS was lower than that of PNS for both A and B after the surgery. That is, maxilla and mandible are rotated in posterior and superior direction. 2. Significances were found between $T_2$ and $T_3$ for both A and B are HRP-Me at vortical measurements, articular angle(p<0.01), gonial angle(p<0.01), and Mn. plane angle(p<0.05) at angular measurement. Mn. plane angle is increased at HRP-Me is decreased for both A and B. 3. There is no significance in skeletal stability aster the surgery between group A and B. 4. Horizontal movements of B and Pog by surgery have statistically significant inverse correlations with horizontal relapse of B and Pog, and vertical relapse of PNS, as well as Mn. Plane angle, and gonial angle after the surgery.

• Journal of the Korean Arthroscopy Society
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• v.10 no.2
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• pp.209-213
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• 2006

Purpose: Conventional transtibial approach for the anterior cruciate ligament (ACL) reconstruction tended to place the femoral tunnel in too vertical position (11 or 1 o'clock), which could provide the postoperative anteroposterior (AP) stability but not provided the rotational stability. Therefore we present a surgical technique to make the transtibial femoral tunnel at 10 or 2 o'clock position. Surgical approach: To make a transtibial femoral tunnel at the 10 or 2 o'clock position, the direction and position of the tibial drill guide was important. We set the tibial drill guide at $40{\sim}45$ degrees and the intraarticular guide tip was 1 mm anterior and medial to the conventional site. The starting point for the guide pin on the proximal tibia was proximal to the pes anserinus and anterior to the medial collateral ligament. The tibial tunnel was initially drilled 1mm less than the diameter of the graft. Then femoral offset guide could be easily placed at 10 or 2 o'clock position through the tibial tunnel. The tibial tunnel and the femoral tunnel of 30 mm in length were made with the reamer that was same size with the graft. Conclusion: We report a surgical technique to create a transtibial femoral tunnel at 10 or 2 o'clock position in ACL reconstruction to provide the rotational stability as well as the AP stability.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.35 no.2
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• pp.82-87
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• 2013

Purpose: This study evaluated postoperative maxillary stabilities in patients with skeletal Class III malocclusion who were taken both maxillary advancement surgery and mandibular retrusive surgery, using Le Fort I osteotomy, through three-dimensional computed tomography. Methods: We selected 14 patients who were taken postoperative three-dimensional computerized tomography at the time before surgery, immediately after surgery, six months after surgery among the patients undergone both maxillary advancement surgery using Le Fort I osteotomy and mandibular retrusive surgery using bilateral sagittal split ramus osteotomy. We measured and compared the vertical distance of A-point and posterior nasal spine (PNS), the horizontal distance of A-point and PNS in transverse plane and coronal plane of the three-dimensional reconstructed images, respectively. Results: In transverse plane, the distance difference between immediately after surgery ($S_1$) and immediately before surgery ($S_0$) of A-point was $-0.04{\pm}1.80$ mm, $S_2$ and $S_0$ was $-0.15{\pm}1.69$ mm, and between $S_1$ and $S_2$ was $0.11{\pm}0.58$ mm. There were no significant differences between these data (P>0.05). In transverse plane, the distance between $S_1-S_0$ of PNS was $-3.87{\pm}2.37$ mm, $S_2-S_0$ of PNS was $-3.79{\pm}2.39$ mm, and $S_1-S_2$ of PNS was $-0.08{\pm}0.18$ mm. There were significant differences between these data (P<0.05). In coronal plane, the distance between $S_1-S_0$ of A-point was $3.99{\pm}0.86$ mm, $S_2-S_0$ was $3.57{\pm}1.09$ mm, and $S_1-S_2$ was $0.42{\pm}0.42$ mm. There were significant differences between these data (P<0.05). In coronal plane, the distance between $S_1-S_0$ of PNS was $3.82{\pm}0.96$ mm, $S_2-S_0$ was $3.43{\pm}0.91$ mm, and $S_1S_2$ was $0.39{\pm}0.49$ mm. There were significant differences between these data (P<0.05). In transverse plane, it was estimated that PNS has no statistical postoperative stability in the same direction. In coronal plane, it was estimated that both A-point and PNS had no statistical postoperative stability (P<0.05). Conclusion: Clinically, the operation plan needs to take into account of the maxillary relapse.

• Korean Chemical Engineering Research
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• v.60 no.1
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• pp.93-99
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• 2022

With the rapid development of ultra-small and wearable device technology, continuous electricity supply without spatiotemporal limitations for driving electronic devices is required. Accordingly, Triboelectric nanogenerator (TENG), which utilizes static electricity generated by the contact and separation of two different materials, is being used as a means of effectively harvesting various types of energy dispersed without complex processes and designs due to its simple principle. However, to apply the TENG to real life, it is necessary to increase the electrical output. In addition, stable generation of electrical output, as well as increase in electrical output, is a task to be solved for the commercialization of TENG. In this study, we proposed a method to not only improve the output of TENG but also to stably represent the improved output. This was solved by using the contact layer, which is one of the components of TENG, as an electret for improved output and stability. The utilized electret was manufactured by sequentially performing corona charging-thermal annealing-corona charging on the Fluorinated ethylene propylene (FEP) film. Electric charges artificially injected due to corona charging enter a deep trap through the thermal annealing, so an electret that minimizes charge escape was fabricated and used in TENG. The output performance of the manufactured electret was verified by measuring the voltage output of the TENG in vertical contact separation mode, and the electret treated to the corona charging showed an output voltage 12 times higher than that of the pristine FEP film. The time and humidity stability of the electret was confirmed by measuring the output voltage of the TENG after exposing the electret to a general external environment and extreme humidity environment. In addition, it was shown that it can be applied to real-life by operating the LED by applying an electret to the clap-TENG with the motif of clap.