• Korean Journal of Optics and Photonics
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• v.14 no.3
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• pp.244-248
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• 2003

When confocal lenses are applied to a digital holography system, the interference pattern of a larger object size can be recorded on CCD. The angle of incoming light to the CCD can be reduced by the ratio of the two focal lengths of confocal lenses. The recordable spatial frequency is limited by the unit cell size of the CCD. Therefore the spatial frequency of interference on the CCD is lowered by reduction of the incoming light angle. By using confocal lenses , another merit can be achieved that the area of the zero order diffraction is reduced by the square of the ratio of two focal lengths at the numerical reconstruction.

• Current Optics and Photonics
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• v.6 no.6
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• pp.565-575
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• 2022

In this paper, we propose a non-fungible token (NFT) transaction method that can commercialize the real 3D property and make property sharing possible using the 3D reconstruction technique. In addition, our proposed method enhances the security of NFT copyright and metadata by using optical encryption. In general, a conventional NFT is used for 2D image proprietorial rights. To expand the scope of the use of tokens, many cryptocurrency industries are currently trying to apply tokens to real three-dimensional (3D) property. However, many token markets have an art copyright problem. Many tokens have been minted without considering copyrights. Therefore, tokenizing real property can cause significant social issues. In addition, there are not enough methods to mint 3D real property for NFT commercialization and sharing property tokens. Therefore, we propose a new token management technique to solve these problems using integral imaging and double random phase encryption. To show our system, we conduct a private NFT market using a test blockchain network that can demonstrate the whole NFT transaction process.

• Current Optics and Photonics
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• v.5 no.4
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• pp.409-420
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• 2021

We propose a method to synthesize a color non-hogel-based computer-generated-hologram (CGH) from light field data of a three-dimensional scene with a hologram pixel pitch shared for all color channels. The non-hogel-based CGH technique generates a continuous wavefront with arbitrary carrier wave from given light field data by interpreting the ray angle in the light field to the spatial frequency of the plane wavefront. The relation between ray angle and spatial frequency is, however, dependent on the wavelength, which leads to different spatial frequency sampling grid in the light field data, resulting in color aberrations in the hologram reconstruction. The proposed method sets a hologram pixel pitch common to all color channels such that the smallest blue diffraction angle covers the field of view of the light field. Then a spatial frequency sampling grid common to all color channels is established by interpolating the light field with the spatial frequency range of the blue wavelength and the sampling interval of the red wavelength. The common hologram pixel pitch and light field spatial frequency sampling grid ensure the synthesis of a color hologram without any color aberrations in the hologram reconstructions, or any loss of information contained in the light field. The proposed method is successfully verified using color light field data of various test or natural 3D scenes.

• Archives of Plastic Surgery
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• v.50 no.4
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• pp.389-392
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• 2023

A 14-year-old girl had a midfacial trauma event caused by hitting against an opening door and experienced discomfort and swelling of the columella and upper lip. Physical examination revealed mild tenderness on light palpation without any discomfort with upper lip movement. A computed tomography scan of the maxillofacial bones with three-dimensional reconstruction showed a fracture of the anterior nasal spine with obvious leftward displacement, mild-deviation of the caudal aspect of the nasal septum, and no sign of nasal bone fracture. Open reduction and internal fixation was performed with regard to aesthetic and functional concerns, including nasal septum deviation. The postoperative course was uneventful, and healing proceeded normally without complications. Herein, we emphasize the importance of differential diagnosis of isolated anterior nasal spine fractures in patients with midfacial trauma and clinicians' strategic decision-making in treatment modalities.

• Applied Microscopy
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• v.50
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• pp.25.1-25.11
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• 2020

Scanning acoustic microscopy (SAM) or Acoustic Micro Imaging (AMI) is a powerful, non-destructive technique that can detect hidden defects in elastic and biological samples as well as non-transparent hard materials. By monitoring the internal features of a sample in three-dimensional integration, this technique can efficiently find physical defects such as cracks, voids, and delamination with high sensitivity. In recent years, advanced techniques such as ultrasound impedance microscopy, ultrasound speed microscopy, and scanning acoustic gigahertz microscopy have been developed for applications in industries and in the medical field to provide additional information on the internal stress, viscoelastic, and anisotropic, or nonlinear properties. X-ray, magnetic resonance, and infrared techniques are the other competitive and widely used methods. However, they have their own advantages and limitations owing to their inherent properties such as different light sources and sensors. This paper provides an overview of the principle of SAM and presents a few results to demonstrate the applications of modern acoustic imaging technology. A variety of inspection modes, such as vertical, horizontal, and diagonal cross-sections have been presented by employing the focus pathway and image reconstruction algorithm. Images have been reconstructed from the reflected echoes resulting from the change in the acoustic impedance at the interface of the material layers or defects. The results described in this paper indicate that the novel acoustic technology can expand the scope of SAM as a versatile diagnostic tool requiring less time and having a high efficiency.

• Clinics in Shoulder and Elbow
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• v.27 no.1
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• pp.108-116
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• 2024

Reverse total shoulder arthroplasty (RTSA) is widely popular among shoulder surgeons and patients, and its prevalence has increased dramatically in recent years. With this increased use, the indicated pathologies associated with RTSA are more likely to be encountered, and challenging patient presentations are more likely to be seen. One prominent challenging presentation is RTSA patients with severe glenoid bone loss. Several techniques with varying degrees of invasiveness, including excessive reaming, alternate centerline, bone grafting, and patient-specific implants (PSIs), have been developed to treat patients with this presentation. PSI treatment uses a three-dimensional reconstruction of a computed tomography scan to design a prosthetic implant or component customized to the patient's glenoid morphology, allowing compensation for any significant bone loss. The novelty of this technology implies a paucity of available literature, and although many studies show that PSIs have good potential for solving challenging shoulder problems, some studies have reported questionable and equivocal outcomes. Additional research is needed to explore the indications, outcomes, techniques, and cost-efficiency of this technology to help establish its role in current treatment guidelines and strategies.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.34 no.5
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• pp.555-561
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• 2008

Purpose: The goal of this study was to develop a technique for creating a computerized composite maxillofacial-dental model, based on point-based surface best fit algorithm and to test its accuracy. The computerized composite maxillofacial-dental model was made by the three dimensional combination of a 3-dimensional (3D) computed tomography (CT) bone model with digital dental model. Materials and Methods: This integration procedure mainly consists of following steps : 1) a reconstruction of a virtual skull and digital dental model from CT and laser scanned dental model ; 2) an incorporation of dental model into virtual maxillofacial-dental model by point-based surface best fit algorithm; 3) an assessment of the accuracy of incorporation. To test this system, CTs and dental models from 3 volunteers with cranio-maxillofacial deformities were obtained. And the registration accuracy was determined by the root mean squared distance between the corresponding reference points in a set of 2 images. Results and Conclusions: Fusion error for the maxillofacial 3D CT model with the digital dental model ranged between 0.1 and 0.3 mm with mean of 0.2 mm. The range of errors were similar to those reported elsewhere with the fiducial markers. So this study confirmed the feasibility and accuracy of combining digital dental model and 3D CT maxillofacial model. And this technique seemed to be easier for us that its clinical applicability can good in the field of digital cranio-maxillofacial surgery.

• Archives of Reconstructive Microsurgery
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• v.18 no.1
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• pp.35-39
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• 2009

Purpose: Various techniques have been attempted for design of the flaps. However, there are some disadvantages. They have thin, pliable, and two dimensional methods. The aim of this study is to report usefulness of polyurethane foam dressing materials for three dimensional design of the digital island flap. Methods: From June of 2007 to september of 2008, 10 patients received digital island flap surgery for soft tissue defect of the finger. After minimal debridement of the wound, size and shape of the defect were measured using polyurethane foam. We used Medifoam-$5^{(R)}$ And then, designed this inset the wound. The flap was designed on the donor site with a arterial pedicle as the central axis according to size and shape. A full thickness skin graft from the groin is applied on the flap donor defect and secured with a tieover bolster dressing. Results: Reviewing sizes of the flaps, the length and width of flaps ranged from 1.5 to 3.3 cm and 1.0 to 2.5 cm. The PACS(Picture Archiving Communication System) program allows identification of the donor depth of finger. The distance for the soft tissue ranged from 4.3 mm to 6.7 mm. Mean depth of donor site was 5.3${\pm}$0.6 mm. Also, the thickness of Medifoam-$5^{(R)}$ ranged nearly 5 mm. On flap insetting, full-thickness skin graft was necessary. We did not experience any problems in the recipient site size either, regardless of the extended flaps. Conclusion: Polyurethane foam has many advantages over the more conventional templates. Refinements in flap design and surgical technique resulted in favorable functional and cosmetic results. Especially, for beginner, Polyurethane foam dressing material is a simple and safe tool and therefore is an excellent choice for design of the island flap.

• Archives of Plastic Surgery
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• v.35 no.1
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• pp.36-41
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• 2008

Purpose: For facial reconstruction, skin color match is crucial to achieve great aesthetic result. Forehead flap and full thickness skin graft have been used for many years to reconstruct facial defect. Their results are aesthetically valuable with remarkable resemblance and harmony of the skin color between donor and recipient sites. The purpose of this study is to evaluate and compare the aesthetic outcome of the two methods as the analysis of skin color match. Methods: From January 1995 to December 2005, ten forehead flaps and ten full thickness skin grafts were performed. The reconstructed areas of forehead flaps were five noses and five eyelids. Recipient sites of full thickness skin grafts were seven eyelids, two noses and one forehead. In order to obtain the objective validity, the skin color of flap(or graft) and the recipient sites were measured by chromameter. The skin colors were quantified according to a three-dimensional coordinate system used in chromameter, L*(brightness), a*(redness), and b*(yellowness).Results: There was no significant color difference between forehead flap site and adjacent skin in all color values. On the other hand, the L* and b* values of graft sites were significantly lower than those of the adjacent skins. The a* values of graft sites were higher than those of the adjacent skins. Conclusion: This study reveals that skin color match of forehead flap is greater than that of full thickness skin graft. As forehead flap has adequate volume and great color match, it can be useful to reconstruct deep facial defect such as nasal defect. On the other hand, full thickness skin graft can be used for superficial defect like partial eyelid defect.

• Korean Journal of Head & Neck Oncology
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• v.19 no.1
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• pp.41-46
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• 2003

Background and Objectives: Surgical ablation of tumors in the oral cavity and the oropharynx results in a three dimensional defect because of the needs to resect the adjacent area for the surgical margin. Although a variety of techniques are available, radial forearm free flap has been known as an effective method for this defect, which offers a thin, pliable, and relatively hairless skin and a long vascular pedicle. We report the clinical results of our 54 consecutive radial forearm free flaps used for oral cavity and oropharynx cancers. Materials and Methods: We reviewed the medical records of patients who were offered intraoral reconstruction with a radial forearm free flap after ablative surgery for oral cavity and oropharyngeal cancers from August 1994 to February 2003 and analyzed surgical methods, flap survival rate, complication, and functional results. Among these, 20 cases were examined with modified barium swallow to evaluate postoperative swallowing function and other 8 cases with articulation and resonance test for speech. We examined recovery of sensation with two-point discrimination test in 15 cases who were offered sensate flaps. Results: The primary sites were as follows : mobile tongue (18), tonsil (17), floor of mouth (4), base of tongue (2), soft palate (2), retromolar trigone (3), buccal mucosa (1), oro-hypopharynx (6), and lower lip (1). The paddles of flaps were tailored in multilobed designs from oval shape to tetralobed design and in variable size according to the defects after ablation. This procedures resulted in satisfactory flap success rate (96.3%) and showed good swallowing function and social speech. Eight of 15 cases (53.3%) who had offered sensate flap showed recovery of sensation between 1 and 6 postoperative months (average 2.6 month). Conclusion: The reconstruction with radial forearm free flap might be an excellent method for the maximal functional results after ablative surgery of oral cavity and oropharyngeal cancers that results in multidimensional defect.