• Steel and Composite Structures
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• 제34권3호
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• pp.393-407
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• 2020

The braced tube frame system, a combination of perimeter frame and bracing frame, is one of the systems used in tall buildings. Due to the implementation of this system in tall buildings and the high rigidity resulting from the use of general bracing, providing proper ductility while maintaining the strength of the structure when exposing to lateral forces is essential. Also, the high stress at the connection of the beam to the column may cause a sudden failure in the region before reaching the required ductility. The use of Reduced Beam Section connection (RBS connection) by focusing stress in a region away from beam to column connection is a suitable solution to the problem. Because of the fact that RBS connections are usually used in moment frames and not tested in tall buildings with braced tube frames, they should be investigated. Therefore, in this research, three tall buildings in height ranges of 20, 25 and 30 floors were modeled and designed by SAP2000 software, and then a frame in each building was modeled in PERFORM-3D software under two RBS-free system and RBS-based system. Nonlinear time history dynamic analysis is used for each frame under Manjil, Tabas and Northridge excitations. The results of the Comparison between RBS-free and RBS-based systems show that the RBS connections increased the absorbed energy level by reducing the stiffness and increasing the ductility in the beams and structural system. Also, by increasing the involvement of the beams in absorbing energy, the columns and braces absorb less energy.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2017년도 춘계공동학술대회
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• pp.91-91
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• 2017

최근 국민 삶의 질 향상, 건강한 먹거리 인식 및 국내 여건 변화 등으로 벼농사에 비해 상대적으로 소득 수준이 높은 밭작물 생산에 대한 수요가 증가하고 있으나, 관련 농업기계 개발이 미흡하여 밭농업 기계화가 절실한 실정이다. 밭작물의 경우 기계화율이 2015년 56.3%이며, 특히 파종, 이식작업이 5%, 수확작업이 13.3% 수준으로 열악한 실정임. 경운정지 기계화율은 99%를 넘으며, 방제 작업도 기계화율이 85~99% 수준으로 다른 작업에 비해 높은 실정으로, 파종, 이식, 수확작업의 기계화는 밭농업 일관기계를 위하여 반드시 필요하다. 감자는 주요 밭작물 중 하나로, 최근 가공용 소비로 수입량이 증가하여 국내에서 자주식 굴취/선별/수집형 수확기(2011, 농촌진흥청)가 개발되었으나, 가격이 높고 표피손상 등 개선이 필요하여 트랙터 부착형 수집형 감자수확기가 개발 중에 있다. 따라서 본 연구에서는 수집형 감자 수확기 시작기 구조해석을 하려고 한다. 우선 시작기의 도면을 CATIA를 활용하여 3D로 작성한 뒤, MIDAS NFX 시뮬레이션 및 구조해석 프로그램으로 구조해석을 진행하였다. 수행한 해석으로는 선형정적해석으로서 외부하중에 대해 구조물의 변형을 검토하는 해석이다. 재질은 SM45C로 선정하였고, 접촉조건과 구속조건을 설정한 뒤 감자수확기 굴취부에 집중하중을 200 ~ 1000 N 까지 200N 간격으로 선형정적해석을 진행하여 Von-Mises 응력, 허용응력, 극한응력, 안전율을 해석하였다.

• 대한치과교정학회지
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• 제41권4호
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• pp.224-236
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• 2011

본 연구는 정상교합자의 치열궁과 기저골 형태를 파악하기 위해 시행하였다. 정상교합자 27명(남-15명: 25Y $10M{\pm}4Y$ 4M/여-12명: 26Y $1M{\pm}7Y$ 4M)을 대상으로 두개골의 전산화 단층촬영을 시행하고 입체영상을 제작한 뒤, 상악 중절치의 FA point의 중점을 원점으로 하는 3차원 좌표계를 형성하였다. 또한 상악 교합평면과 평행한 면으로 절단하여 상하악의 치열궁과 기저골의 형태에 대해 분석하였다. 상하악기저골은 A point, B point 부위와 양측 제1대구치 부위의 좌표에서 통계적으로 유의한 차이가 나타나지 않았다. 또한 상하악의 치열궁은 기저골악궁에 비해 전치부에서 순측으로 위치하였다. 또한 치열궁과 기저골악궁의 협설측 교차는 상악은 대구치 부위에서, 하악은 소구치 부위에서 이루어졌다.

• The Korean Journal of Ceramics
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• 제4권4호
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• pp.323-330
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• 1998

Mixed oxide compounds of potential usefulness for fibre coatings (hexagonal celsian, $BaAl_2Si_2O_8$ and lanthanum hexaluminate, $LaAl_{11}O_{18}$) or for matrix materials (yttrium aluminium garnet, $Y_3Al_5O_{12}$) were prepared by hybrid sol-gel synthesis and their thermal crystallisation was monitored by thermal analysis, X-ray diffraction and multinuclear solid state MAS NMR. All the gels convert to the crystalline phase below about $12200^{\circ}C$, via amorphous intermediates in which the Al shows and NMR resonance at 36-38 ppm sometimes ascribed to Al in 5-fold coordination. Additional information about the structural changes during thermal treatment was provided by $^{29}Si$, $^{137}Ba$ and $^{89}Y$ MAS NMR spectroscopy, showing that the feldspar framework of celsian begins to be established by about $500^{\circ}C$ but the Ba is still moving into its polyhedral lattice sites about $400^{\circ}C$ after the sluggish onset of crystallization. Lanthanum hexaluminate and YAG crystallise sharply at 1230 and $930^{\circ}C$ respectively, the former via $\gamma-Al_2O_3$, the latter via $YAlO_3$. Yttrium moves into the garnet lattice sites less than $100^{\circ}C$ after crystallisation.

• 전자공학회논문지
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• 제51권7호
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• pp.71-81
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• 2014

본 논문에서는 삼차원 소자 시뮬레이터(Sentaurus)를 이용하여 tri-gate FinFET의 fin과 소스/드레인 구조의 변화에 따른 소자의 성능을 분석하였다. Fin의 구조가 사각형 구조에서 삼각형 구조로 변함에 따라, fin 단면의 전위 분포의 차이로 문턱 전압이 늘어나고, off-current가 72.23% 감소하고 gate 커패시턴스는 16.01% 감소하였다. 소스/드레인 epitaxy(epi) 구조 변화에 따른 성능을 분석하기 위해, epi를 fin 위에 성장시킨 경우(grown-on-fin)와 fin을 etch 시키고 성장시킨 경우(etched-fin)의 소자 성능을 비교했다. Fin과 소스/드레인 구조의 변화가 회로에 미치는 영향을 살펴보기 위해 Sentaurus의 mixed-mode 시뮬레이션 기능을 사용하여 3단 ring oscillator를 구현하여 시뮬레이션 하였고, energy-delay product를 계산하여 비교하였다. 삼각형 fin에 etched 소스/드레인 epi 구조의 소자가 가장 작은 ring oscillator delay와 energy-delay product을 보였다.

• Steel and Composite Structures
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• 제33권3호
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• pp.445-461
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• 2019

The ultrasonic guided wave-based technique has become one of the most promising methods in non-destructive evaluation and structural health monitoring, because of its advantages of large area inspection, evaluating inaccessible areas on the structure and high sensitivity to small damage. To further advance the development of damage detection technologies using ultrasonic guided waves for the inspection of welded components in structures, the transmission characteristics of the ultrasonic guided waves propagating through welded joints with various types of defects or damage in steel plates are studied and presented in this paper. A three-dimensional (3D) finite element (FE) model considering the different material properties of the mild steel, high strength steel and austenitic stainless steel plates and their corresponding welded joints as well as the interaction condition of the steel plate and welded joint, is developed. The FE model is validated against analytical solutions and experimental results reported in the literature and is demonstrated to be capable of providing a reliable prediction on the features of ultrasonic guided wave propagating through steel plates with welded joints and interacting with defects. Mode conversion and scattering analysis of guided waves transmitted through the different types of weld defects in steel plates are performed by using the validated FE model. Parametric studies are undertaken to elucidate the effects of several basic parameters for various types of weld defects on the transmission performance of guided waves. The findings of this research can provide a better understanding of the transmission behaviour of ultrasonic guided waves propagating through welded joints with defects. The method could be used for improving the performance of guided wave damage detection methods.

• 한국유통학회지:유통연구
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• 제16권1호
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• pp.1-27
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• 2011

본 연구는 프랜차이즈 본사의 선택속성으로서 사전지원, 사후지원, 지각된 사업성과, 가맹본부와 가맹점의 커뮤니케이션, 가맹본부의 모럴해저드 등 외생변수가 매개변수인 가맹점의 만족과 위험지각에 미치는 영향을 분석하고, 이들 매개 변수가 다시 신뢰와 결과변수인 재계약의도에 미치는 영향관계를 분석하였다. 기존의 연구들과 차별점으로, 가맹본부의 가맹점에 대한 지원을 개점 전 지원인 사전지원으로, 개점 후 지원인 사후지원으로 구분하였고, 가맹점이 실제 사업운영 과정에서 느끼는 가장 중요한 지각된 사업성, 그리고 가맹본부와 가맹점의 쌍방향성의 커뮤니케이션 정도, 또 가맹본부의 모럴해저드를 연구모델에 설정하여 가맹점 만족, 위험지각, 신뢰, 재계약의도 등의 관계를 프랜차이즈 시스템의 실질적 관점에서 조사한 점이라고 할 수 있다. 연구결과 (1)가맹본부의 사전지원, 사후지원, 지각된 사업성, 커뮤니케이션, 모럴해저드는 가맹점 만족에 영향을 미쳤고, (2)지각된 사업성, 커뮤니케이션, 모럴해저드는 위험지각에도 유의한 영향을 미쳤으며, (3)만족과 위험지각, 신뢰 모두 재계약의도에 유의한 영향을 미친 것으로 나타났다. 또한 이러한 결과를 바탕으로 본 연구는 향후 프랜차이즈 산업발전에 발전적인 시사점을 제시하였다.

• 복식문화연구
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• 제20권5호
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• pp.655-663
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• 2012

Due to increased interest in character costumes, the field of animation character costume design is gradually developing into a specialized domain. The costume-making process for animation characters presents many differences from the costume-making process for regular apparel. However, there remains insufficient research on the actual process of making the character costumes used in stop motion videos both in Korea and abroad. The purpose of this study is to establish a costume design process for animation characters. Furthermore, this study presents a case study on the costume planning and making process for 3D stop motion animation characters. The character costume-making process was segmentalized into the following stages: character analysis stage, character modeling stage, and character costume making stage. In the character analysis stage, the investigator analyzed the character's movements, designed the character images, and analyzed the movements and motions of the animation characters. After completing character modeling, this study proposed a method for making the character costume. The style of the character costume was designed, and the structural design reflected the position and size of joints as well as the angle of movements. The patterns of the character costume were produced through dimensional tailoring after measuring the body size of the character. Afterward, the costume was completed after passing through the fitting and revision stages. The clothing material was selected to fit the colors and feelings shown in the illustration. To complete the costume after comparing it with the initial illustration, it was revised based on the assessment of its volume and overall atmosphere.

• Structural Engineering and Mechanics
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• 제68권4호
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• pp.409-421
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• 2018

In the present paper, functionally graded (FG) materials are presented to investigate the bending analysis of simply supported plates. It is assumed that the material properties of the plate vary through their length according to the power-law form. The displacement field of the present model is selected based on quasi-3D hyperbolic shear deformation theory. By splitting the deflection into bending, shear and stretching parts, the number of unknowns and equations of motion of the present formulation is reduced and hence makes them simple to use. Governing equations are derived from the principle of virtual displacements. Numerical results for deflections and stresses of powerly graded plates under simply supported boundary conditions are presented. The accuracy of the present formulation is demonstrated by comparing the computed results with those available in the literature. As conclusion, this theory is as accurate as other shear deformation theories and so it becomes more attractive due to smaller number of unknowns. Some numerical results are provided to examine the effects of the material gradation, shear deformation on the static behavior of FG plates with variation of material stiffness through their length.

• Journal of Mechanical Science and Technology
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• 제15권7호
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• pp.1041-1050
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• 2001

Control of bone cement volume (PMMA) may be critical for preventing complications in vertebroplasty, the percutaneous injection of PMMA into vertebra. The purpose of this study was to predict the optimal volume of PMMA injection based on CT images. For this, correlation between PMMA volume and textural features of CT images was examined before and after surgery to evaluate the appropriate PMMA amount. The gray level run length analysis was used to determine the textural features of the trabecular bone. Extimation of PMMA volume was done using 3D visualization with semi-automatic segmentation on postoperative CT images. Then, finite element (FE) models were constructed based on the CT image data of patients and PMMA volume. Appropriate material properties for the trabecular bone were assigned by converting BMD to elastic modulus. Structural reinforcement due to the changes in PMMA volume and BMD was assessed in terms of axial displacement of the superior endplate. A strong correlation was found between the injected PMMA volume and the area of the intertrabecular space and that of trabecular bone calculated from the CT images (r=0.90 and -0.90, respectively). FE results suggested that vertebroplasty could effectively reinforce the osteoporotic vertebra regardless of BMD or PMMA volume. Effectiveness of additional PMMA injection tended to decrease. For patients with BMD well lower than 50mg/ml, injection of up to 30% volume of the vertebral body is recommended. However, less than 30% is recommended otherwise to avoid any complications from excessive PMMA because the strength has already reached the normal level.