• 수산해양기술연구
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• 제50권3호
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• pp.233-243
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• 2014

The difference of mooring tension by type of buoy was investigated in the circulating water channel and the wave tank for deducting the most stable buoy from the current and the wave condition. 5 types of buoy made up of short cylinder laid vertically (CL-V), short cylinder laid horizontally (CL-H), capsule (CS), sphere (SP) and long cylinder (CL-L) were used for experiments. A mooring line and a weight were connected with each buoy. A tensile gauge was installed between a mooring line and a weight. All buoy's mooring tension was measured at the same time for the wave test with periods of 1.5~3.0 sec and wave heights of 0.1~0.3 m, and the current test with flow speeds of 0.2~1.0 m/sec. As a result, the order of tension value in the wave test was CL-H > CL-V > SP > CS > CL-L. In the current test CL-V and CL-H were recorded in the largest tension value, whereas SP has the smallest tension value. So it seems that SP buoy is the most effective in the location affected by fast current. CS is predicted to be suitable for a location that influence of wave is important more than that of current if practical use in the field is considered. And it was found that the difference of mooring tension among buoys in wave is related to the product of the cross sectional area and the drag coefficient for the buoy's bottom side in high wave height. The factor for the current condition was not found. But it was supposed to be related to complex factors like a dimension and a shape by buoy's posture to flow.

• 패션비즈니스
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• 제7권5호
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• pp.108-118
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• 2003

Surface properties, including the texture and the luster, of cotton fibers and yarns thereof play an important role in textile technology. The convolutions and the cross-sectional shape of the cotton fiber affect the fabric texture and the luster accordingly. Mercerization of the cotton fabric affects the luster, strength, and other properties of the fabric. In this study, the effect of mercerization was examined on the luster of the cotton fabric, together with the effect of polishing treatment. One of the traditional methods determining the fabric luster is the use of glossmeter or goniometric glossmeter. The use of glossmeter gives successful results in determining the gloss of rather flat and continuous surface such as plastic sheet, painted surface, or paper products. Since the textile fabrics have diverse surface structures and textures, these could be regarded as having three-dimensional surface. Such complexity imposes some difficulties for differentiating subtle surface luster properties of diverse textile fabrics. The advancement in the area of imaging technologies has enabled the micro-scale analysis of the surface textures and the fabric luster recently. Using a CCD camera, the surface luster images were taken at various incident illumination conditions. Microscale analysis, including the blob analysis, of the images could differentiate the subtle luster properties present in a group of cotton fabric samples comprising mercerized cotton fabric, non-mercerized cotton fabric, polished cotton fabric, and a 'standard' cotton fabric. The glossmeter measurement gave satisfactory but limited differentiation among the samples, whose luster differences are easily recognizable with visual observation, except for the mercerized cotton fabric sample and the non-mercerized cotton fabric. The microscale analysis of the fabric luster could, therefore, help understand the nature of diverse textile fabric luster.

• 대한조선학회지
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• 제11권1호
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• pp.9-16
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• 1974

To contribute towards more accurate estimation of the virtual inertia coefficient for the horizontal vibration of ships, three dimensional correction factor $J_H$ for the added mass of finitely long elliptic prismatic bars in horizontal vibration in a free surface of an ideal fluid are calculated. In the problem formulation Dr. T. Kumai's quasi-finite length concept[1,11,12] is employed. Now that, in Dr. Kumai's work[1] for the horizontal vibration the mathematical model was a circular cylinder, the principal aim of the authors' work is to investigate the influence of the beam-draft ratio B/T on $J_H$. The numerical results of this work are shown in Fig.3 graphically, from which we may recognize that the influence of B/T on $J_H$ is remarkable as much as that of the length-draft ratio L/T(refer to Fig.1 also). In Fig.3 the curves for B/T=2.00 are of those based on Dr. Kumai's result[1]. On the other hand, the experimental data obtained by Burril et al.[9] for the horizontal vibration of finitely long prismatic bars of various cross-section shapes are compared with the theoretical added mass coefficients defined by combination of the authors' $J_H$ from Fig.3 and two dimensional coefficients $C_H$ obtained by Lewis form approximation for the corresponding sections. They are in reasonable correspondence with each other as shown in Fig.2. Finally, considering that the longitudinal profile of full-form ship's hull is well resembled to that of an elliptic cylinder and that the influences of other factors such as the sectional area coefficient and the shape of section contour itself can be well merged in the two dimensional added mass coefficient, the authors recommend that the data given in Fig.3 may be successfully adopted for the three dimensional correction factor the added mass in the horizontal vibration of hull-form ships.

• 한국항공우주학회지
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• 제47권9호
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• pp.642-648
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• 2019

본 연구에서는 미세 단층 영상을 이용하여 삭마 복합재료의 전산 모델링 및 해석을 수행하였다. 탄소/페놀릭(carbon/phenolic) 복합재료의 삭마 실험은 0.4MW 아크 가열 풍동을 이용하여 수행하였다. 미세 단층 촬영기(Micro-CT)로 삭마 실험 전후의 복합재료 시편을 촬영하여 이진화된 단층 영상을 생성하였다. 생성된 이진화 영상을 활용하여, 삭마 복합재료의 실제 미시 구조가 반영된 전산 모형을 개발하였다. 영상 기반 전산 모형은 시편 횡방향의 특정 영역의 영상을 적층하여 개발하였다. 전산 모형은 실험 전 시편 영상에서 1종, 실험 후 시편 영상에서 8종, 총 9종의 전산 모형을 개발하였다. 영상 기반 전산 모형을 통해 삭마에 의한 유효 물성을 예측하였으며, 기공도 증가에 따른 유효 물성 저하를 확인하였다.

• Steel and Composite Structures
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• 제30권5호
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• pp.483-492
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• 2019

In the current study, the influence of the initial lateral (sweep) shape and the cross-sectional twist imperfection on the lateral torsional buckling (LTB) response of doubly-symmetric steel I-beams was investigated. The material imperfection (residual stress) was not considered. For this objective, standard European IPN 300 beam with different unbraced span was numerically analyzed for three imperfection cases: (i) no sweep and no twist (perfect); (ii) three different shapes of global sweep (half-sine, full-sine and full-parabola between the end supports); and (iii) the combination of three different sweeps with initial sinusoidal twist along the beam. The first comparison was done between the results of numerical analyses (FEM) and both a theoretical solution and the code lateral torsional buckling formulations (EC3 and AISC-LRFD). These results with no imperfection effects were then separately compared with three different shapes of global sweep and the presence of initial twist in these sweep shapes. Besides, the effects of the shapes of initial global sweep and the inclusion of sinusoidal twist on the critical buckling load of the beams were investigated to unveil which parameter was considerably effective on LTB response. The most compatible outcomes for the perfect beams was obtained from the AISC-LRFD formulation; however, the EC-3 formulation estimated the $P_{cr}$ load conservatively. The high difference from the EC-3 formulation was predicted to directly originate from the initial imperfection reduction factor and high safety factor in its formulation. Due to no consideration of geometric imperfection in the AISC-LFRD code solution and the theoretical formulation, the need to develop a practical imperfection reduction factor for AISC-LRFD and theoretical formulation was underlined. Initial imperfections were obtained to be more influential on the buckling load, as the unbraced length of a beam approached to the elastic limit unbraced length ($L_r$). Mode-compatible initial imperfection shapes should be taken into account in the design and analysis stages of the I-beam to properly estimate the geometric imperfection influence on the $P_{cr}$ load. Sweep and sweep-twist imperfections led to 10% and 15% decrease in the $P_{cr}$ load, respectively, thus; well-estimated sweep and twist imperfections should considered in the LTB of doubly-symmetric steel I-beams.

• 대한토목학회논문집
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• 제41권1호
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• pp.39-48
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• 2021

본 논문에서는 정적 수직하중을 받는 barrette 말뚝의 고유진동수를 산정할 수 있는 해석모델을 제안하였다. 비균질 지반에 설치된 직사각형 마찰말뚝의 자유진동을 지배하는 미분방정식을 유도하였다. 이 지배방정식을 Runge-Kutta 법을 이용하여 수치적분하였고, 미분방정식의 고유치인 고유진동수는 Regula-Falsi 법을 이용하여 산정하였다. 말뚝의 고유진동수는 유한요소해석의 결과와 잘 일치하였다. 말뚝의 고유진동수를 증가시키는 말뚝변수는 단면형상비, 마찰저항비, 지반강성비이고, 감소시키는 말뚝변수는 마찰형상비, 세장비, 압축계수이다.

• 마이크로전자및패키징학회지
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• 제29권3호
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• pp.31-35
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• 2022

최근 4차산업혁명으로 대용량 데이터 처리를 위한 고집적 반도체에 대한 수요가 증가하고 있다. 반도체 제품에 장착되는 소자들의 크기가 작아 짐에 따라 표면실장기술(SMT)의 신뢰성에 대한 연구가 관심을 받고 있다. 본 연구에서는 PCB의 패드 디자인이 수동소자의 조립 및 접합 신뢰성에 미치는 영향을 실험 계획법(design of experiment, DOE) 이용하여 분석하였다. 수동소자를 실장하기 위한 PCB의 패드 길이, 너비 및 두 패드간 거리를 변수로 하여 실험계획법을 수립하였다. 저항칩의 오배치(misplacement) 방향에 따른 수동소자의 톰스톤(tombstone)불량률을 도출하였다. 전단테스트를 통해 수동소자와 PCB 사이의 전단력을 측정하였다. 또한, 단면분석을 통해 패드 디자인에 따른 솔더의 형상을 분석하였다.

• Composites Research
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• 제35권5호
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• pp.334-339
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• 2022

본 연구에서는 복합재료 제조 공정 과정 중 수지의 유동 저항성을 대변하는 인자인 투수 계수를 예측하는 알고리즘을 개발하였다. 단방향 연속 섬유 복합재료 내부에서 섬유와 수직인 방향 투수 계수의 정확한 예측을 위해 대표 체적 요소의 단면 형상을 고려하였다. 섬유의 유체 유동 저항성을 정량화하기 위한 인지로 섬유 간 간격이 사용되었고, 등가 길이는 섬유 배열에 따른 수지의 유로 변화를 나타내는 인자로 사용되었다. 전기-유압 유사성을 접목하여 투수 계수 예측 알고리즘을 개발하고 그 타당성을 확인하였다. 알고리즘은 Matlab과 Python으로 구성되고, 타당성 검증을 위해 FLUENT를 통해 예측된 투수 계수와 비교하였다. 알고리즘과 수치 해석을 통해 얻은 투수 계수가 거의 일치함을 확인하여 알고리즘을 검증하였으며, 소요 시간은 수치 해석 대비 약 1/450로 감소하였다.

• 품질경영학회지
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• 제52권1호
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• pp.95-113
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• 2024

Purpose: This study focused on the societal changes associated with the entry into an ultra-aged society and the increase in single-person households. The core objective of this research is to investigate how social intelligent robots can bring about positive changes in the lives of individuals in single-person households and how such changes influence user satisfaction and the intention to use these robots. Methods: The study employed a cross-sectional analysis using a structural equation model. A survey designed to assess the impact of social intelligent robots' characteristics, such as perceived encouragement, empathy, presence, appearance, and attachment, on user satisfaction and usage intentions was conducted. Data were collected from a total of 335 users and analyzed using the structural equation model. Results: In the characteristics of social intelligent robots for single-person households, it was found that empathy, presence, and attachment significantly influenced satisfaction, while perceived encouragement, empathy, and attachment significantly influenced usage intentions. The research results indicate differences between enhancing user satisfaction and increasing the intention to use social intelligent robots. The findings suggest the essential need for a user-centric approach in the design and development of social intelligent robots. Additionally, it was observed that emotional support plays a crucial role in users' experiences with social intelligent robots. Conclusion: This study verified the impact of social intelligent robots on satisfaction and usage intentions based on users' experiences. It examined the influence of linguistic, visual, and personal characteristics of robots on user experiences, providing insights into how technological and human aspects of social intelligent robots interact to shape user satisfaction and usage intentions. Consequently, the study confirmed that social intelligent robots can bring positive changes to human life, emphasizing the necessity for the advancement of robot technology in a human-centric direction.

• 대한토목학회논문집
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• 제5권3호
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• pp.49-59
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• 1985

탄성(彈性) 이론(理論)에 의하여 트러스의 형상최적화(形狀最適化) 문제(問題)를 형성(形成)하게 되면 부재(部材)의 단면적(斷面積)과 절점(節點)의 좌표(座標)를 동시에 고려(考慮)해야 하는 복잡(複雜)한 비선형(非線型) 계획문제(計劃問題)가 된다. 이런 비선형(非線形) 계획문제(計劃問題)를 해석(解析)할 수 있도록 제시(提示)된 기법(技法)이 별로 없고 현재 사용(使用)하고 있는 기법(技法)들도 실제(實際)의 적용(適用)에 제한(制限)을 받는 경우가 많다. 그러므로 트러스의 형태(形態), 재하조건(載荷條件) 등에 구애됨이 없이 트러스의 형상(形狀)을 최적화(最適化)할 수 있는 일반(一般) 해석기법(解析技法)이 필요(必要)한 것이다. 이에 본연구(本硏究)에서는 전(全) 해석과정(解析過程) two-phases로 나누어 phase 1 에서는 단면(斷面)을 최적화(最適化)하고 phase 2 에서는 트러스의 절점좌표(節點座標)를 변수(變數)로 하여 형상(形狀)을 최적화(最適化)하는 알고리즘을 개발(開發)한 것이다. 이 알고리즘의 phase 1 에서 유도(誘導)된 비선형(非線型) 계획문제(計劃問題)를 SUMT 문제(問題)로 변환(變換)시켜 Modified Newton-Raphson Method에 의한 SUMT 법(法)을 채택(採擇)하고 phase 2 에서는 Rosenbrock Method의 일방향(一方向) 탐사기법(探査技法)에 의해 목적함수(目的凾數)만이 최소(最小)가 되도록 하는 기법(技法)을 도입(導入)하여 최적화(最適化) 알고리즘 개발(開發)하였다. 개발(開發)된 알고리즘을 트러스의 형태(形態), 설계제약조건(設計制約條件), 재하조건(載河條件) 등을 변화(變化)시켜 가면서 수종(數種)의 트러스에 적용(適用)하여 수치계산(數値計算)을 실시(實施)하고 그 결과(結果)를 다른 알고리즘의 결과(結果)와 정교(正較)하므로서 개발(開發)된 알고리즘의 타당성(妥當性) 안정성(安定性) 적용성(適用性)을 검토(檢討)하였다. 연구(硏究) 결과(結果) 개발(開發)된 이 two-phases 알고리즘은 트러스의 설계조건(設計條件)에 구애받지 않고 트러스의 형상최적화(形狀最適化)에 적용(適用)할 수 있으며 안정성(安定性)있게 빠른 속도(速度)로 최적해(最適解)에 수렴(收斂)한다는 사실(事實)이 확인(確認)되었다. 이에 본(本) 알고리즘을 트러스의 형상최적화(形狀最適化) 알고리즘으로 새로이 제안(提案)하고 본(本) 알고리즘이트러스의 경제적(經劑的)인 설계(設計)에 도움을 줄 수 있을 것으로 사료(思料)된다.