• 한국멀티미디어학회논문지
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• 제16권1호
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• pp.108-118
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• 2013

최근 컴퓨터 비전, 컴퓨터 그래픽스 분야의 급속한 발전과 하드웨어의 우수한 성능으로 인해 3차원 모델링 기술 또한 급속히 발전 되었다. 그리고 다양한 3D 컨텐츠들의 등장으로 3차원 모델링 기술의 수요가 더욱 많아지고 그 질 또한 높아지고 있다. 3D 얼굴 모델은 이러한 컨텐츠들에 폭 넓게 적용될 수 있어 활용성이 높다. 본 논문에서는 주어진 한 장의 2D 정면 얼굴 영상으로부터 3D 얼굴을 모델링하는 방법을 제안한다. 이를 위해 다수의 정점으로 구성된 3D 일반 얼굴 모델을 입력 얼굴 영상과의 대응관계를 통해 변형하여 3D 얼굴을 모델링한다. 우선 AAM을 이용하여 입력된 얼굴 영상에서 특징점을 추출한다. 그리고 추출된 특징점만으로 직관적인 모델을 변형하기 위해 메쉬 워핑을 적용한다. 여기에 얼굴의 깊이 정보를 유도하기 위하여 한 장의 정면 얼굴 영상을 활용한 명도 변화 기반의 깊이 값의 추출을 시도한다. 이러한 과정을 통해 경제적으로 부담되지 않으며 사용 환경에 대한 제한이 적어 보편적으로 활용될 수 있는 3D 얼굴 모델링 방법을 구현하고 그 타당성을 실험으로 보인다.

• 대한금속재료학회지
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• 제46권5호
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• pp.321-327
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• 2008

Cu based amorphous ($Cu_{54}Zr_{22}Ti_{18}Ni_6$) coating was produced by cold spraying as a new fabrication process. The microstructure and macroscopic properties of amorphous coating layer was investigated and compared with those of cold sprayed pure Cu coating. Amorphous powders were prepared by gas atomization and Al 6061 was used as the substrate plate. X-ray diffraction results showed that Cu based amorphous powder could be successfully deposited by cold spraying without any crystallization. The Cu based amorphous coating layer ($300{\sim}400{\mu}m$ thickness) contained 4.87% porosity. The hardness of Cu based amorphous coating represented $412.8H_v$, which was correspond to 68% of the hardness of injection casted bulk amorphous material. The wear resistance of Cu based amorphous coating was found to be three times higher than that of pure Cu coating. The 3-point bending test results showed that the adhesion strength of Cu based amorphous coating layer was higher than that pure Cu coating. It was also observed that hard Cu base amorphous particle could easily deform soft substrate by particle collisions and thus generated strong adhesion between coating and substrate. However, the amorphous coating layer unexpectedly represented lower corrosion resistance than pure Cu coating, which might be resulted from the higher content of porosity in the cold sprayed amorphous coating.

• 한국콘텐츠학회논문지
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• 제22권6호
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• pp.541-556
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• 2022

뇌졸중 장애인을 대상으로 실시한 운동 프로그램은 주로 병원에서 실시한 물리치료 형태로 치료적 효과에만 집중되어 단조로운 경향이 있다. 그러나 본 연구에서 실시한 뉴스포츠 프로그램은 대상자별 운동능력을 고려하여 운동 강도, 난이도의 변형이 가능하고 특수재질로 만든 장비를 사용하여 안전하고 재미있게 참여할 수 있을 것으로 생각된다. 이에 본 연구는 뇌졸중 장애인의 뉴스포츠 프로그램 참여에 대한 의미와 인식, 프로그램 참여에 대한 경험을 심층적으로 이해하고 분석하는데 목적이 있다. 연구대상은 뉴스포츠 프로그램에 참여한 뇌졸중 장애인 11명을 연구참여자로 선정하였으며, 질적 연구 방법인 심층면담을 통하여 자료를 수집하였다. 연구결과, 4개의 하위범주(프로그램에 대한 기대, 프로그램 참여 경험, 프로그램 개선 방안)와 10개의 핵심 개념을 도출하였다. 본 연구 결과를 바탕으로 퇴원 이후 지역사회에 거주하고 있는 뇌졸중 장애인들을 대상으로 실시한 뉴스포츠 프로그램은 추후 뇌졸중 장애인의 특성을 고려한 지역사회 기반 운동 프로그램이 개발되는데 기초가 될 것으로 사료된다.

• 방송공학회논문지
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• 제27권5호
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• pp.638-653
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• 2022

본 논문은 고화질 2차원 전신 영상을 입력으로 받아 영상 속 인물이 입고 있는 의상 패턴과 체형 정보를 추정한 후, 이를 반영한 3차원 가상 휴먼의 생성 기법을 제안한다. 의상의 패턴을 얻기 위해서 Cascade Mask R-CNN을 이용하여 의상 분할을 진행한다. 이후 Pix2Pix로 경계를 블러 및 배경색을 추정하고, UV-Map 기반으로 변환하여 3차원 의상 메쉬의 UV-Map을 얻을 수 있다. 또한, SMPL-X를 이용하여 체형 정보를 얻고 이를 기반으로 의상과 신체의 기본 메쉬를 변형한다. 앞서 얻은 의상 UV-Map, 체형이 반영된 의상과 신체의 메쉬를 이용해 최근 각광받고 있는 게임 엔진인 언리얼 엔진에서 렌더링하여 최종적으로 사용자가 그의 외형이 반영된 3차원 가상 휴먼의 애니메이션을 볼 수 있도록 한다.

• 대한두경부종양학회지
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• 제38권2호
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• pp.29-32
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• 2022

Lipoma is one of the most common benign soft tissue tumors. However, giant lipomas compressing and deforming the neurovascular structure rarely occur in the lateral neck. A 70-year-old man visited our outpatient clinic for treatment of a visible painless neck mass that had been identified 2 years prior. Neck magnetic resonance imaging revealed that a 10 × 9 × 4 cm fatty mass located between the sternocleidomastoid and sternohyoid muscles invaded the carotid sheath. Under general anesthesia, the mass was excised without damage to the adjacent neurovascular structures. Upon histopathological examination, the mass was identified as a lipoma. During the surgery, enlargement of the internal jugular vein was observed under the resected mass. However, on ultrasound examination, the function of the internal jugular vein was evaluated as good. No recurrence or neurological and vascular complications were reported during a 6-month follow-up after the surgery. As a giant lipoma located in the deep layer of the lateral neck can deform important cervical structures, its impact on the surrounding structures should be carefully assessed preoperatively to minimize the rate of possible complications.

• 반도체디스플레이기술학회지
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• 제21권1호
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• pp.27-32
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• 2022

There has always been a demand for orthodontic treatment. Orthodontic treatment allows tooth to be arranged by flexible arch wire fixed with tooth-attached brackets. Arch wire generate constant pressure to tooth brackets which moves the teeth to proper place. When the bracket transmits force, the braced wing of the bracket may deform. Deformed tie wing will lead to lost tension of elastic ligature. Then, lacking grip between tie wing and ligature might delay the tooth movement. Furthermore, tooth brackets used for orthodontic treatment make contact with in direct oral surface and this cause feeling of irritation that comes from height of tooth braces. This study suggests an optimal teethe bracket design to make up for inconvenience by shorten the height of bracket and complement the shape of bracket to reduce strain rate using finite element analysis. As a result, new optimal design of teethe bracket indicates lower strain rate of the bracket wing and takes good effects of shorten body height in terms of convenience.

• Design & Manufacturing
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• 제16권4호
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• pp.34-39
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• 2022

Sustained economic development around the world is accelerating resource depletion. Research and development of secondary batteries that can replace them is also being actively conducted. Secondary batteries are emerging as a key technology for carbon neutrality. The core of an electric vehicle is the battery (secondary battery). Therefore, in this study, the temperature change by the heat source of the hammer and the rotational speed (rpm) of the abrasive disc of the Classifier Separator Mill (CSM) was repeatedly calculated and analyzed using the heat flow simulation STAR-CCM+. As the rotational speed (rpm) of the abrasive disk increases, the convergence condition of the iteration increases. Under the condition that the inlet speed of the Classifier Separator Mill (CSM) and the heat source value of the disc hammer are the same, the disc rotation speed (rpm) and the hammer temperature are inversely proportional. As the rotational speed (rpm) of the disc increases, the hammer temperature decreases. However, since the wear rate of the secondary battery material increases due to the strong impact of the crushing rotational force, it is determined that an appropriate rpm setting is necessary. In CSM (Classifier Separator Mill), it is judged that the flow rate difference is not significantly different in the direction of the pressure outlet (Outlet 1) right above the classifier wheel with the fastest flow rate. Because the disc and hammer attachment technology is adhesive, the attachment point may deform when the temperature of the hammer rises. Therefore, it is considered necessary to develop high-performance adhesives and other adhesive technologies.

• Nuclear Engineering and Technology
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• 제54권12호
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• pp.4514-4521
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• 2022

In this study, the effects of heat and radiation on the degradation behaviour of fluoroelastomer under simulated normal operation and a severe accident environment were investigated using sequential testing of gamma irradiation and thermal degradation. Tensile properties and Shore A hardness were measured, and thermogravimetric analysis was used to evaluate the degradation behaviour of fluoroelastomer. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy were used to characterize the structural changes of the fluoroelastomer. Heat and radiation generated in nuclear power plant break and deform the chemical bonds, and fluoroelastomer exposed to these environments have decreased C-H and functional groups that contain oxygen and double bonds such as C-O, C=O and C=C were generated. These functional groups were formed by auto oxidation by reacting free radicals generated from the cleaved bond with oxygen in the atmosphere. In this auto oxidation reaction, crosslinks were generated where bonded to each other, and the mobility of molecules was decreased, and as a result, the fluoroelastomer was hardened. This hardening behaviour occurred more significantly in the severe accident environment than in the normal operation condition, and it was found that thermal stability decreased with the generation of unstable structures by crosslinking.

• Computers and Concrete
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• 제31권5호
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• pp.419-432
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• 2023

Beam-column joints are a critical component of reinforced concrete frame structures. They are responsible for transferring forces between adjoining beams and columns while limiting story drifts and maintaining structural integrity. During severe loading, beam-column joints deform significantly, affecting, and sometimes governing, the overall response of frame structures. While most failure modes for beam and column elements are commonly considered in plastic-hinge-based global frame analyses, the beam-column joint failure modes, such as concrete shear and reinforcement bond slip, are frequently omitted. One reason for this is the dearth of published guidance on what type of hinges to use, how to derive the joint hinge properties, and where to place these hinges. Many beam-column joint models are available in literature but their adoption by practicing structural engineers has been limited due to their complex nature and lack of practical application tools. The objective of this study is to provide a comparative review of the available beam-column joint models and present a practical joint modeling approach for integration into commonly used global frame analysis software. The presented modeling approach uses rotational spring models and is capable of modeling both interior and exterior joints with or without transverse reinforcement. A spreadsheet tool is also developed to execute the mathematical calculations and derive the shear stress-strain and moment-rotation curves ready for inputting into the global frame analysis. The application of the approach is presented by modeling a beam column joint specimen which was tested experimentally. Important modeling considerations are also presented to assist practitioners in properly modeling beam-column joints in frame analyses.

• 문화기술의 융합
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• 제9권5호
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• pp.529-534
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• 2023

고속 및 대면적 인쇄를 위한 라인 프린팅 기술은 늘어난 헤드 길이만큼 헤드 내부로 잉크를 공급하는 유로를 확보해야 하는 구조적 취약점과 제조 과정에서 발생하는 잔류응력에 의한 피드홀 변형으로 인해 노즐층이 파손되거나 잉크가 누출되는 결함이 있다. 따라서 본 논문에서는 견고하고 신뢰할 수 있으며 라인 프린팅 방식에 보다 적합한 열전사 방식의 잉크젯 프린트 헤드 형상을 제안하고자 한다. 먼저 실험을 통해 초기 라인 프린팅 헤드의 변형량을 측정한 후 이를 등가의 하중량으로 변환하였으며 FEA 해석을 통해 하중 추정 방법의 타당성을 검증하였다. 또한 헤드 크기를 증가시키지 않으면서 변형을 최소화할 수 있도록 기둥이나 지지벽으로 단위 노즐을 보강하거나 지지빔이나 건/습식각된 브릿지를 추가하여 내부 강성을 증가시킨 헤드 구조를 설계하였으며, 피드홀 변형이 최대 90% 감소하는 것을 확인하였다. 제안된 형상 중 공정 편의성과 제작비용을 고려하여 건식각된 피드홀 브릿지 형태의 헤드를 선정하였으며 실제 제작을 통해 노즐층 변형이나 잉크 누출 없이 정상 작동하는 것을 확인하였다.