Method for solving origami tessellation hole problem using triangle twist folding

Yamamoto Yohei,Nakazato Riku,Mitani Jun 한국CDE학회 2022 Journal of computational design and engineering Vol.9 No.1

Origami tessellations are geometric pieces folded from a single sheet of paper with flatly overlapped facets. Most existing origami tessellations are constructed by first marking a grid of crease lines on the paper and then arranging repeating patterns along the grid. However, this design method is limited because it cannot design origami tessellations with patterns that cannot be represented on a grid, such as a regular pentagon. This paper proposes a new construction method for origami tessellations that solves this problem and enriches these varieties. In the proposed method, a boundary of an origami tessellation is determined first, and then patterns called triangle twist fold patterns are placed inside the boundary. A similar approach is known as a hole problem, although in this paper, the problem is redefined and discussed in a form suitable for origami tessellations. As a result, a grid-independent construction method was proposed, and new origami tessellations were obtained by using software that implements the method.

Continuous deformation of flat-foldable crease patterns via interpretation as set of twist-patterns

Yamamoto Yohei,Mitani Jun 한국CDE학회 2023 Journal of computational design and engineering Vol.10 No.3

In the study of origami, various parametric methods have been proposed to design crease patterns under geometric conditions for flat-folding. Each design method contributes to finding a desirable crease pattern, e.g., one with superior engineering properties, by manipulating parameters. On the other hand, to continuously deform other crease patterns, it is necessary to recreate it once with such a parametric method; however, this inverse problem is less studied. This paper is basic research to solve this problem and to allow parametric deformation of flat-foldable crease patterns. Given crease patterns are interpreted as networks consisting of twist-folding patterns that can be generated by an existing parametric method named twist-based design method. Then, by manipulating the parameters, the crease pattern is deformed. Importantly, any flat-foldable crease pattern having no crease line connecting two points on the boundary can be targeted, and it is locally guaranteed that deformed crease patterns have non-intersecting crease lines and are flat-foldable. The proposed method contributes to increased origami variations by deformations of existing crease patterns.

Fetal development of the carotid canal with special reference to a contribution of the sphenoid bone and pharyngotympanic tube

Yohei Honkura,Masahito Yamamoto,José, Francisco Rodrí,guez-Vá,zquez,Gen Murakam,Hiroshi Abe,Shin-ichi Abe,Yukio Katori 대한해부학회 2021 Anatomy & Cell Biology Vol.54 No.2

The bony carotid canal is a tube-like bone with a rough surface in contrast to smooth surfaces of the other parts of the temporal bone petrosal portion (petrosa): it takes an impression of the additional, out-sourcing product. No study had been conducted to evaluate a contribution of the adjacent sphenoid and pharyngotympanic tube (PTT) to the carotid canal. We examined sagittal and horizontal histological sections of hemi-heads from 37 human fetuses at 10 to 37 weeks. At 10 to 18 weeks, the future carotid canal was identified as a wide loose space between the cartilaginous cochlea and the ossified or cartilaginous sphenoid elements (ala temporalis and pterygoid). A linear mesenchymal condensation extending between the cochlear wall and ala temporalis suggested the future antero-inferior margin of the carotid canal. This delineation was more clearly identified in later stages. After 25 weeks, 1) the growing pterygoid pushed the PTT upward and, in turn, the PTT pushed the internal carotid artery (ICA) upward toward the petrosa: 2) a membranous ossification occurs in the dense mesenchymal tissue, the latter of which took an appearance of an anterior process of the petrosa; 3) the bony process of the petrosa involved the ICA inside or posteriorly. The bony carotid canal was made with membranous ossification in the dense mesenchymal tissue between the petrosa and sphenoid. The mother tissue was detached from the sphenoid by the PTT. The ossification of the septum between the ICA and tympanic cavity seemed to continue after birth.

A simple technique for impression taking of teeth and functionally generated paths

Yamamoto, Takatsugu,Sato, Yohei,Watanabe, Hidehiko,Punj, Amit,Abe, Minoru,Momoi, Yasuko,Ohkubo, Chikahiro The Korean Academy of Conservative Dentistry 2018 Restorative Dentistry & Endodontics Vol.43 No.1

The objective of this case report is to introduce a simple technique for simultaneously taking a closed-mouth impression and functionally generated path (FGP) for a full coverage crown restoration. A monolithic zirconia crown was the restoration of choice. An alginate impression of the abutment tooth was taken to fabricate a custom-made closed-mouth impression tray covering the abutment tooth and the adjacent teeth. The tray had an FGP table and an abutment tray in cameo and intaglio surfaces, respectively. The impression was taken with silicone impression material after adjusting the abutment tray and inscribing the FGP using self-curing acrylic resins. Plaster casts were made from the impression, and a zirconia crown was fabricated. The crown was cemented to the abutment tooth with minimal adjustments. This simple technique resulted in a well-fitting crown that accounted for mandibular movements. Using the custom closed-mouth impression tray incorporating an FGP table simultaneously aids in fabricating an accurately fitting restoration that incorporates harmonious mandibular movements using a single impression capture.

A simple technique for impression taking of teeth and functionally generated paths

Takatsugu Yamamoto,Yohei Sato,Hidehiko Watanabe,Amit Punj,Minoru Abe,Yasuko Momoi,Chikahiro Ohkubo 대한치과보존학회 2018 Restorative Dentistry & Endodontics Vol.43 No.1

The objective of this case report is to introduce a simple technique for simultaneously taking a closed-mouth impression and functionally generated path (FGP) for a full coverage crown restoration. A monolithic zirconia crown was the restoration of choice. An alginate impression of the abutment tooth was taken to fabricate a custom-made closed-mouth impression tray covering the abutment tooth and the adjacent teeth. The tray had an FGP table and an abutment tray in cameo and intaglio surfaces, respectively. The impression was taken with silicone impression material after adjusting the abutment tray and inscribing the FGP using self-curing acrylic resins. Plaster casts were made from the impression, and a zirconia crown was fabricated. The crown was cemented to the abutment tooth with minimal adjustments. This simple technique resulted in a well-fitting crown that accounted for mandibular movements. Using the custom closed-mouth impression tray incorporating an FGP table simultaneously aids in fabricating an accurately fitting restoration that incorporates harmonious mandibular movements using a single impression capture.

Radiation-induced synthesis of Au/Fe oxide nanocomposite particles for magnetic separation of biomolecules

Satoshi Seino,Takuya Kinoshita,Yohei Otome,Takashi Nakagawa,Kenji Okitsu,Tadachika Nakayama,Tohru Sekino,KoichiNiihara,Takao A. Yamamoto 한양대학교 세라믹연구소 2004 Journal of Ceramic Processing Research Vol.5 No.2

Nanocomposite particles composed of gold and iron oxide were synthesized with various ratios of gold and iron oxide in an aqueous phase using γ-rays. Iron oxide nanoparticles of γ-Fe2O3 or Fe3O4 were used as a magnetic phase on which gold nanoparticles with average diameters of 5-10 nm were supported. The efficiency of magnetic separation of biomolecules by the present nanocomposite particles was investigated using glutathione as a model compound. The amount of glutathione magnetically separated was significantly enhanced by the supported gold nanoparticles.

Current Treatment Strategy for Superficial Nonampullary Duodenal Epithelial Tumors

Tetsuya Suwa,Kohei Takizawa,Noboru Kawata,Masao Yoshida,Yohei Yabuuchi,Yoichi Yamamoto,Hiroyuki Ono 대한소화기내시경학회 2022 Clinical Endoscopy Vol.55 No.1

Endoscopic submucosal dissection (ESD) is the standard treatment method for esophageal, gastric, and colorectal cancers. However,it has not been standardized for duodenal lesions because of its high complication rates. Recently, minimally invasive and simplemethods such as cold snare polypectomy and underwater endoscopic mucosal resection have been utilized more for superficialnonampullary duodenal epithelial tumors (SNADETs). Although the rate of complications associated with duodenal ESD has beengradually decreasing because of technical advancements, performing ESD for all SNADETs is unnecessary. As such, the appropriatetreatment plan for SNADETs should be chosen according to the lesion type, patient condition, and endoscopist’s skill.