• 제목/요약/키워드: Printing Volume

검색결과 114건 처리시간 0.025초

3D Topology Optimization of Fixed Offshore Structure and Experimental Validation

  • Kim, Hyun-Seok;Kim, Hyun-Sung;Park, Byoungjae;Lee, Kangsu
    • 한국해양공학회지
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    • 제34권4호
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    • pp.263-271
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    • 2020
  • In this study, we performed a three-dimensional (3D) topology optimization of a fixed offshore structure to enhance its structural stiffness. The proposed topology optimization is based on the solid isotropic material with penalization (SIMP) method, where a volume constraint is applied to utilize an equivalent amount of material as that used for the rule-based scantling design. To investigate the effects of the main legs of the fixed offshore structure on its structural stiffness, the leg region is selectively considered in the design domain of the topology optimization problem. The obtained optimal designs and the rule-based scantling design of the structure are manufactured by 3D metal printing technology to experimentally validate the topology optimization. The behaviors under compressive loading of the obtained optimal designs are compared with those of the rule-based scantling design using a universal testing machine (UTM). Based on the structural experiments, we concluded that by employing the topology optimization method, the structural stiffness of the structure was enhanced compared to that of the rule-based scantling design for an equal amount of the fabrication material. Furthermore, by effectively combining the topology optimization and rule-based scantling methods, we succeeded in enhancing the structural stiffness and improving the breaking load of the fixed offshore structure.

도공층의 공극과 인쇄적성에 관한 연구(제4보) -안료 배합 비율이 미치는 영향- (Studies on the Pore of Coating Layer and Printability (IV) -Effects of Blending Ratio of Pigments-)

  • 김창근;이용규
    • 펄프종이기술
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    • 제33권3호
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    • pp.29-36
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    • 2001
  • This paper was made to evaluate the effect of the blending ration of GCC and No. 1 clay on the printability by investigating the structure of pore such as the pore rate, the number of pores, pore size and distribution of coated paper. The coated structure is mainly depended on the results of correlation between pigment and binder. It means that the structure of the pore occurred is chiefly affected by the blending ratio of GCC and No. 1 clay. This physical properties of the pore have a close relation with ink set-off associated with the drying rate and the penetration in ink into base paper and with printing gloss. Therefore it was needed to find out how the pore structure and the printability will be changed by modifying the blending ratio of GCC and No. 1 clay to vary the pore structure of coated paper. Below are the results of measurement: As the blending ratio of clay going up, water retention, sedimentation volume. smoothness, and paper gloss were increased, but relatively brightness and opacity were decreased. Pore rate was the highest at the blending ratio of No. 1 clay to GCC, 70:30. In this case, average pore radius was also increased. Ink receptivity and K&N ink receptivity were improved with the increase of the blending ratio of GCC, where was, ink setting was vice versa. No difference was observed in the weight of ink, but ink repellance decrease with the decrease of blending ratio of GCC.

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조선초기 공기록물(公記錄物) 관리제(管理制)의 개편 (The Reformation of the Public Record Management System in Early Chosǒn Dynasty)

  • 윤훈표
    • 기록학연구
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    • 제2호
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    • pp.129-168
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    • 2000
  • $Chos{\check{o}}n$ Dynasty was governed by the words of king, however, if they were not announced by the form of public document, they were useless. Therefore, the form of public document was the symbol of governing activity, and it was very important to manage the public record in operating the nation affairs. However, the point we should consider is that $Chos{\check{o}}n$ Dynasty, in the case of managing the public record, edited 'the original' instead of preserving them. And so, the preservation of the public record was deeply related to the editing of history. In Late Korea dynasty, the management of the public record got into utter confusion and so many troubles were occurred. In order to resolve these problems, the movements which innovated the public record managements system was gradually extended. This movements were continued in $Chos{\check{o}}n$ Dynasty. Finally, through the several modification procedures, the rules of public record management were legislated by 'Kyong Kuk Dae Jeon'(經國大典). Especially, by laws of 'Kyong Kuk Dae Jeon', not only the daily records of Secretary Department(承政院) but also the important documents which was related to the government branch should be booked in the last decade of the year and the number of the books had to be reported to the king. This rule made certification of the fact that the king was the last confirmer of the public record management. In addition, through the procedure of printing the record of the national affairs, and the diplomatic once in three years, and then preserving that public record in the National Department(議政府), other departments responsible and the archives, the National Department practically took part in the public record management. The management system was also changed in order that the public record was virtually used and consulted before taking the procedure of immortal preservation. All public documents were classified by the definite rule and filed in a same volume. After classifying and filing, certainly, for making convenience of reference and application of public record, records were indicated by the paper card. It may be that, after the step of reference, application and indicating, the public documents were gradually transferred to the next step. In these procedures, Early $Chos{\check{o}}n$ public documents system was confirmed.

Comparing volumetric and biological aspects of 3D-printed interim restorations under various post-curing modes

  • Song, Gun;Son, Ji-Won;Jang, Ji-Hyun;Choi, Sung-Hyeon;Jang, Woo-Hyung;Lee, Bin-Na;Park, Chan
    • The Journal of Advanced Prosthodontics
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    • 제13권2호
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    • pp.71-78
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    • 2021
  • Purpose. This study aims to compare the volumetric change, degree of conversion (DOC), and cytotoxicity of 3D-printed restorations post-cured under three different conditions. Materials and Methods. 3D-printed interim restorations were post-cured under three different conditions and systems: 5 min, 30 min, and 24 h. Three-unit and six-unit fixed dental prostheses (n = 30 for each case) were printed; ten specimens from each group were post-cured and then scanned to compare their volumetric changes. Root-mean-squared (RMS) values of the data were acquired by superimposing the scanned files with original files. Thirty disk-shaped specimens were printed to evaluate the DOC ratio. Fourier transform infrared spectroscopy was used to compare the DOCs of 10 specimens from each group. Human gingival fibroblasts were used to measure the cell viability of every specimen (n = 7). The data from this experiment were employed for one-way analysis of variance and Tukey's post-hoc comparisons. Results. Differences between the three-unit restorations were statistically insignificant, regardless of the post-curing conditions. However, for the six-unit restorations, a high RMS value was acquired when the post-curing duration was 30 min. The average DOC was approximately 56 - 62%; the difference between each group was statistically insignificant. All the groups exhibited cell viability greater than 70%, rendering them clinically acceptable. Conclusion. The post-curing conditions influenced the volume when the length of the restoration was increased. However, this deviation was found to be clinically acceptable. Additionally, post-curing did not significantly influence the DOC and cytotoxicity of the restorations.

휘발성 유기화합물용 수동식 시료채취기 개발 (Development of Passive Samplers for Volatile Organic Compounds)

  • 장미연;이광용;전현진
    • 한국산업보건학회지
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    • 제32권4호
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    • pp.359-370
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    • 2022
  • Objective: This study is intended to design a commercially available passive sampler and conduct performance test on its use as a media for evaluating a working environment. Methods: This study was conducted to select adsorbents, design models, and evaluate storage stability and sampling rates for the development of new types of passive samplers. Results: The impurity detection, adsorbent capacity and breakthrough volume of five types of activated carbon were tested for selection of an adsorbent. One product was selected in consideration of the efficiency of purchase. A number of passive samplers were designed in a radial style and a badge style using plastic as a material. The final two prototypes were made using molds or 3D printing. For the storage stability evaluation, samples were stored at different temperature for 1~21 days and then analyzed. Most of the chemicals had excellent storage stability when refrigerated. However, some chemicals such as dichloromethane and methyl ethyl ketone need to be analyzed as soon as possible after sampling. Conclusion: In this study, new types of passive samplers for 66 chemical compounds were developed. The evaluation of storage stability and sampling rates showed different results depending on the properties of the chemical substance. For some chemicals such as methyl ethyl ketone and dimethylformamide, activated carbon is inappropriate as an absorbent. In future studies, additional experiments are required on chemicals that are difficult to collect with activated carbon.

미국 국립공원 주니어레인저 워크북 특성 및 국내 지형교육에의 시사점 (Characteristics of Junior Ranger Activity Books of U.S. National Parks and Their Implications for Geomorphological Education in Korea)

  • 김태호
    • 한국지형학회지
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    • 제28권1호
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    • pp.101-114
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    • 2021
  • Junior Ranger is a self-directed interpretation program for young visitors at national parks in the United States. The success of this program can be largely attributed to the role of an activity book which is given an applicant free of charge at a visitor center. This study aims to analyze the main characteristics of activity books for 14 national parks' Junior Ranger and to draw some implications for Korean geomorphological education. Although the activity books are varied in size, volume and printing, all of them offer diverse activities which are composed of different contents related to park resources in four fields and are performed in different ways such as Q&A, picture and word game, and creative activity. The time-consuming activities including attendance at a ranger-led program prevent the participant from making a superficial visit to be a junior ranger. The implications of the study are as follows: Firstly, the geomorphological education for children is needed to be strongly based on field experience learning and to be more carried out using a way of game rather than conventional Q&A, suggesting that it encourages students not to lose their interest for learning. Secondly, it is also necessary for the learning contents to be focused on various resources related to landform as well as landform itself. In addition, a creative activity such as writing verse or drawing feeling should be more applied to the geomorphological education in order to enhance their effects on affective domain beyond cognitive one. It is likely to be an alternative approach to understand landform by internalizing a sense of landform.

3D 프린팅 기술을 활용한 치매노인 전용 영양(수분)보충 식품섭취용기 개발 (Development of 3D Printed Snack-dish for the Elderly with Dementia)

  • 이지연;김철호;김국원;이경애;고광오;김희선
    • 대한지역사회영양학회지
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    • 제26권5호
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    • pp.327-336
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    • 2021
  • 본 연구는 전반적 신체기능 소실, 음식 섭취량의 만성적 저하의 특징을 갖는 치매노인에서 만성적 영양불량 해소에 도움을 줄 수 있도록 수분이나 영양소의 보충을 위한 스낵 개념의 식품을 제공하는 맞춤형 용기를 개발하고자 하였다. 아이디어 창출 협의체 구성 후 선행연구 탐색 및 브레인스토밍을 통하여 포도 모양의 디자인이 적합하다고 판단하였다. 드로잉 스케치와 점토모형 제작 후 시제품 제작을 위해 개인니즈를 충족시키며 소규모 제작에 적합하다고 알려진 3D 프린팅 기술을 적용하였다. 3차원 설계는 3D CAD 소프트웨어 SolidWorks을 이용하였고 한국인의 영양소섭취기준과 관련 선행연구 및 기존 연구결과를 종합하여 용기 당 최대 수분제공량 및 수치를 결정하였다. 필라멘트를 녹인 뒤 층층이 쌓아올리는 출력 방식(FDM) 3D 프린터(DP200)를 사용하였고 식품용기 위생과 안전을 고려하여 사전유해물질 인준이 확인된 옥수수 전분 유래 PLA 필라멘트를 이용해 출력하였다. 용기 당 수분을 기준으로 수분 섭취기준대비 30%를 충족하는 285 mL를 설정하였다. 제작 크기를 고려하여 포도 알맹이는 총 6개로 결정되었다. 알맹이 1개당 47.5 mL의 수분제공이 가능하였는데, 이를 통해 반지름 2.25 cm의 반 구로 설계하였다. 이때 사이 간격을 4 mm로 설정하였다. 사용 시 안전사고 예방을 위해 조작이 쉽고 모나거나 뾰족하지 않은 외형을 갖추며 위생을 위한 뚜껑도 설계하였다. 인지기능이 저하된 치매노인이 해당 용기를 사용할 때 흥미를 느끼고 식사섭취 중 교육 교구로 응용될 수 있도록 뚜껑과 포도 알맹이 바닥면에 숫자를 각인하여 최종 출력 및 조립하였다. 조립 시 수동 작업이 요구된 점은 3D 프린팅 기술의 대표적 장점인 편리성에 반하는 점으로 향후 보완논의가 필요하다고 사료된다. 신체기능이 퇴화되어 만성적으로 섭취량이 제한된 치매 노인에게 단순 섭취 증량을 권고하기에는 무리가 있으므로 맞춤형 영양중재 실시는 상당히 중요하다. 따라서 추후 연구를 통해 개발된 치매노인 전용 식품섭취용기의 만족도 분석을 실시하고 영양밀도를 높인 전용 음식 개발 과정이 논의되어야 하겠다. 4차 산업 핵심기술인 3D 프린팅을 연구에 적용하여 아이디어 구현에 정확도와 편의성이 확인되었으나 관련 기술수준에 따라 발생하는 비용 지출과 외부 전문가 의존에 대한 한계점은 향후 해결이 필요한 부분이라 사료된다. 추후 영양중재 도구개발 시 연구 다양성을 위해 식품영양 전공자에게 해당기술의 융합교육을 통한 자급 활용 빈도를 높이고 진입장벽을 낮추기 위한 다방면의 시도가 필요하겠다.

Impact of lattice versus solid structure of 3D-printed multiroot dental implants using Ti-6Al-4V: a preclinical pilot study

  • Lee, Jungwon;Li, Ling;Song, Hyun-Young;Son, Min-Jung;Lee, Yong-Moo;Koo, Ki-Tae
    • Journal of Periodontal and Implant Science
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    • 제52권4호
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    • pp.338-350
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    • 2022
  • Purpose: Various studies have investigated 3-dimensional (3D)-printed implants using Ti6Al-4V powder; however, multi-root 3D-printed implants have not been fully investigated. The purpose of this study was to explore the stability of multirooted 3D-printed implants with lattice and solid structures. The secondary outcomes were comparisons between the 2 types of 3D-printed implants in micro-computed tomographic and histological analyses. Methods: Lattice- and solid-type 3D-printed implants for the left and right mandibular third premolars in beagle dogs were fabricated. Four implants in each group were placed immediately following tooth extraction. Implant stability measurement and periapical X-rays were performed every 2 weeks for 12 weeks. Peri-implant bone volume/tissue volume (BV/TV) and bone mineral density (BMD) were measured by micro-computed tomography. Bone-to-implant contact (BIC) and bone area fraction occupancy (BAFO) were measured in histomorphometric analyses. Results: All 4 lattice-type 3D-printed implants survived. Three solid-type 3D-printed implants were removed before the planned sacrifice date due to implant mobility. A slight, gradual increase in implant stability values from implant surgery to 4 weeks after surgery was observed in the lattice-type 3D-printed implants. The marginal bone change of the surviving solid-type 3D-printed implant was approximately 5 mm, whereas the value was approximately 2 mm in the lattice-type 3D-printed implants. BV/TV and BMD in the lattice type 3D-printed implants were similar to those in the surviving solid-type implant. However, BIC and BAFO were lower in the surviving solid-type 3D-printed implant than in the lattice-type 3D-printed implants. Conclusions: Within the limits of this preclinical study, 3D-printed implants of double-rooted teeth showed high primary stability. However, 3D-printed implants with interlocking structures such as lattices might provide high secondary stability and successful osseointegration.

펄프·제지 산업에서의 프랙탈 기하 원리 및 그 응용 (The Principles of Fractal Geometry and Its Applications for Pulp & Paper Industry)

  • 고영찬;박종문;신수정
    • 펄프종이기술
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    • 제47권4호
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    • pp.177-186
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    • 2015
  • Until Mandelbrot introduced the concept of fractal geometry and fractal dimension in early 1970s, it has been generally considered that the geometry of nature should be too complex and irregular to describe analytically or mathematically. Here fractal dimension indicates a non-integer number such as 0.5, 1.5, or 2.5 instead of only integers used in the traditional Euclidean geometry, i.e., 0 for point, 1 for line, 2 for area, and 3 for volume. Since his pioneering work on fractal geometry, the geometry of nature has been found fractal. Mandelbrot introduced the concept of fractal geometry. For example, fractal geometry has been found in mountains, coastlines, clouds, lightning, earthquakes, turbulence, trees and plants. Even human organs are found to be fractal. This suggests that the fractal geometry should be the law for Nature rather than the exception. Fractal geometry has a hierarchical structure consisting of the elements having the same shape, but the different sizes from the largest to the smallest. Thus, fractal geometry can be characterized by the similarity and hierarchical structure. A process requires driving energy to proceed. Otherwise, the process would stop. A hierarchical structure is considered ideal to generate such driving force. This explains why natural process or phenomena such as lightning, thunderstorm, earth quakes, and turbulence has fractal geometry. It would not be surprising to find that even the human organs such as the brain, the lung, and the circulatory system have fractal geometry. Until now, a normal frequency distribution (or Gaussian frequency distribution) has been commonly used to describe frequencies of an object. However, a log-normal frequency distribution has been most frequently found in natural phenomena and chemical processes such as corrosion and coagulation. It can be mathematically shown that if an object has a log-normal frequency distribution, it has fractal geometry. In other words, these two go hand in hand. Lastly, applying fractal principles is discussed, focusing on pulp and paper industry. The principles should be applicable to characterizing surface roughness, particle size distributions, and formation. They should be also applicable to wet-end chemistry for ideal mixing, felt and fabric design for papermaking process, dewatering, drying, creping, and post-converting such as laminating, embossing, and printing.

Vateria acuminata Hyne으로 만든 오일의 항세균 및 항진균 효과 (Anti-bacterial and Anti-fungal Effects of Herbal Oil Made from Vateria acuminata Hyne)

  • 김수지;;홍진영;조창욱;김영희;최정은
    • 보존과학연구
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    • 통권33호
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    • pp.5-17
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    • 2012
  • Ola 잎에 글씨를 새긴 다음 그 홈을 Vateria acuminata Hyne의 뿌리로 만든 식물성 오일과 탄소 가루를 섞어 채운 올라 잎 기록물은 스리랑카에서 사용되는 기록 방법 중의 하나이다. 문헌상에 따르면 올라 잎 기록물은 1세기부터 18세기까지 사용되었다. Ola 잎 기록물이 400여 년 동안 보관되어 왔다는 최근의 발견과 좋은 보존 상태로 보아 이 식물성 오일이 올라 잎을 곰팡이와 곤충 같은 생물학적 요인과 환경 요인으로부터 보호해 주는 것으로 보인다. 이 식물성 오일의 항균 활성을 측정하기 위하여 해인사 장경판전에서 분리한 곰팡이와 올라 잎에서 분리한 균을 배양한 후 억제 효과를 확인하였다. 균 현탁액을 평판배지에 도말한 다음 식물성 오일을 흡수시킨 페이퍼 디스크를 평판배지에 올린다. 이 실험에서 식물성 오일은 육안 상 분명한 투명환을 형성하였으며 곰팡이나 세균과 같은 미생물의 성장을 저해하는 것을 확인하였다. 이 결과로 보아 Vateria acuminata Hyne의 식물성 오일은 항세균 및 항진균 활성을 가지고 있다는 것을 나타낸다.

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