• Steel and Composite Structures
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• 제32권4호
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• pp.423-441
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• 2019

This study aims to accurately predict the first ply failure loads of laminated composite hypar shell roofs with different boundary conditions. The geometrically nonlinear finite element method (FEM) is used to analyse different symmetric and anti-symmetric, cross and angle ply shells. The first ply failure loads are obtained through different well-established failure criteria including Puck's criterion along with the serviceability criterion of deflection. The close agreement of the published and present results for different validation problems proves the correctness of the finite element model used in the present study. The effects of edge conditions on first ply failure behavior are discussed critically from practical engineering point of view. Factor of safety values and failure zones are also reported to suggest design and non-destructive monitoring guidelines to practicing engineers. Apart from these, the present study indicates the rank wise relative performances of different shell options. The study establishes that the angle ply laminates in general perform better than the cross ply ones. Among the stacking sequences considered here, three layered symmetric angle ply laminates offer the highest first ply failure load. The probable failure zones on the different shell surfaces, identified in this paper, are the areas where non-destructive health monitoring may be restricted to. The contributions made through this paper are expected to serve as important design aids to engineers engaged in composite hypar shell design and construction.

• 한국항해항만학회지
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• 제27권6호
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• pp.639-643
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• 2003

The emphasis is put on the detailed knowledge on manoeuvring characteristic for the safe navigation while avoiding terrible collision between ships and on the guideline to the design and operation of the ship-waterway system The numerical simulation of manoeuvring motion was carried out parametrically for different ship types, ship-velocity ratios, separation and stagger between ships. As for the calculation parameters, the ratios of velocity difference (hereafter, $U_2$/$U_1$ ) between two ships were considered as 0.6, 1.2, 1.5. From the inspection of this investigation, it indicates the following result. Considering the interaction force only as parameter, the lateral distance between ships is necessarily required for the ship-velocity ratio of 1.2, compared to the cases of 0.6 and 1.5 regardless of the ship types. Furthermore, regardless of the ship-velocity ratio, an overtaking and overtaken vessel can be manoeuvred safely without deviating from the original course under the following conditions: the lateral distance between two vessels is approximately kept at 0.5 times of ship-length and 5 through 10. degrees of range in maximum rudder angle. The manoeuvring characteristic based on this investigation will be very useful for keeping the safety of navigation from the practical point of ships design and traffic control in restricted waterways.

• Korean Chemical Engineering Research
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• 제50권4호
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• pp.743-748
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• 2012

본 논문에서는 미세 환경이 Pseudomonas aeruginosa의 운동성에 주는 영향을 조사하기 위하여 다양한 크기의 미세유로 내에서 박테리아의 운동성을 분석하였다. 본 논문에서는 미세유체 칩을 사용하여 2차원 공간을 만들며, $10{\sim}100{\mu}m$ 너비의 채널 안에서 단일 박테리아의 운동 변수인 이동속도, 'run'운동 지속시간, 'tumble' 각도를 측정하였고 각 미세유로 내에서 박테리아의 운동을 표현할 수 있는 물리적 상수인 random motility coefficient를 구하였다. 상기의 물리적 측정치를 분석한 결과, 박테리아는 공간제약이 있는 경우 편모의 운동이 채널의 벽의 영향으로 인하여 회전 운동에 영향을 받게 되고, 'run' 운동 지속 시간이 짧아지는 것을 확인하였다. 따라서, 공간의 제한이 박테리아의 운동성을 감소시킴을 알 수 있었다. 본 연구의 결과는 박테리아의 운동성을 쉽고 정확하게 분석할 수 있는 측정 방법으로 널리 활용될 것으로 기대된다.

• 국제물리치료학회지
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• 제7권2호
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• pp.1041-1045
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• 2016

The aim of this study was to investigate the effect of Maitland mobilization and Kaltenborn-Evjenth mobilization on the SLR angle. Subjects randomly divided into Kaltenborn-Evjenth group(n=8) and Maitland group(n=7). The mean height, age, body weight was $176.00{\pm}5.10cm$, $22.75{\pm}1.83years$, $72.63{\pm}10.65kg$ respectively in Kaltenborn-Evjenth group. The mean height, age, body weight was $175.00{\pm}5.60cm$, $22.29{\pm}3.68years$, $78.00{\pm}12.36kg$ respectively in Maitland group. Hip joint accessary movements with Grade III or IV were applied depend on the patient's condition to the restricted direction for 1 minute each set, and performed 5 set in a Maitland group. Hip joint anteroposterior gliding with Grade III were applied 60 for 1 minutes each set, and performed 5 set in a Kaltenborn-Evjenth group. The angle of first pain was referred to as P1 and subjects were pointed out that they could not bend the knee anymore, then examiner measure SLR angle. The SLR was significantly increased in the Maitland group compared to the Kaltenborn-Evjenth group after intervention(p<.05). In a within group difference, SLR significantly increased in the both groups(p<.05). These results indicated that Maitland mobilization could be recommended the excellent technique to increase the hip flexion in patient with hip hypo-mobility.

• Macromolecular Research
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• 제17권10호
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• pp.757-762
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• 2009

The micro domain structures and crystallization behavior of the binary blends of poly(methyl methacrylate)-b-poly(pentafluorostyrene)-b-poly(methyl methacrylate) (PMMA-PPFS-PMMA) triblock copolymer with a low molecular weight poly(vinylidene fluoride) (PVDF) were investigated by small-angle X-ray scattering (SAXS), small-angle light scattering (SALS), transmission electron microscopy (TEM), optical microscopy, and differential scanning calorimetry (DSC). A symmetric, PMMA-PPFS-PMMA triblock copolymer with a PPFS weight fraction of 33% was blended with PVDF in N,N-dimethylacetamide (DMAc). In the wide range of PVDF concentration between 10.0 and 30.0 wt%, PVDF was completely incorporated within the PMMA micro domains of PMMA-PPFS-PMMA without further phase separation on a micrometer scale. The addition of PVDF altered the phase morphology of PMMA-PPFS-PMMA from well-defined lamellar to disordered. The crystallization of PVDF significantly disturbed the domain structure of PMMA-PPFS-PMMA in the blends, resulting in a poorly-ordered morphology. PVDF displayed unique crystallization behavior as a result of the space constraints imposed by the domain structure of PMMA-PPFS-PMMA. The pre-existing microdomain structures restricted the lamellar orientation and favored a random arrangement of lamellar crystallites.

• 한국자동차공학회논문집
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• 제16권2호
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• pp.93-98
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• 2008

To investigate the characteristics of water droplet on the gas diffusion layer from both top-view and side-view of the flow channel, a rig test apparatus was designed and fabricated with prism attached plate. This experimental device is used to simulate the growth of single liquid water droplet and its transport process with various air flow velocity and channel height. The contact angle hysteresis and height of water droplet are measured and analyzed. It is found that droplet tends towards to be instable by decreasing channel height, increasing flow velocity or making GDL more hydrophobic. Also, the simplified force balance model matches with experimental data only in a restricted range of operating conditions and shows discrepancy as the air flow velocity and channel height increases.

• 산업공학
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• 제18권3호
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• pp.247-252
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• 2005

In the automated production environment in the present days, the minimization of manual operation becomes a very important factor in increasing the efficiency of the production system. The exit burr produced through the milling operation on the edge of workpiece usually requires manual deburring process to enhance the level of precision of the resulting product. So far, researchers have developed various methods to understand the formation of exit burr in cutting process. One method to analytically identify the formation of exit burr was to use the geometrical information of CAD and CAM data used in automated machining. This method, in turn, generated the information resulting from the analysis such as burr type, cutting region, and exit angle. Up to now, the geometrical data were restricted to the single feature and single path. In this paper, a method to deal with the complicated geometric features such as line segment, arc, hole, and spline will be presented and validated using the field data. This method also deals with the complex workpiece shape which is a combination of multiple features. As for the cutting path, multiple tool path is analyzed in order to simulate the real cutting process. All this analysis is combined into a Windows based software and real data are used to validate the program in the conclusion.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2009년도 정보 및 제어 심포지움 논문집
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• pp.408-410
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• 2009

We present an efficient and robust measurement model for visual tracking. This approach builds on and extends work on subspace representations of measurement model. Subspace-based tracking algorithms have been introduced to visual tracking literature for a decade and show considerable tracking performance due to its robustness in matching. However the measures used in their measurement models are often restricted to few approaches. We propose a novel measure of object matching using Angle In Feature Space, which aims to improve the discriminability of matching in subspace. Therefore, our tracking algorithm can distinguish target from similar background clutters which often cause erroneous drift by conventional Distance From Feature Space measure. Experiments demonstrate the effectiveness of the proposed tracking algorithm under severe cluttered background.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2002년도 종합학술발표회 논문집 Vol.12 No.1
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• pp.263-267
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• 2002

For driver's convenience, the ACC (Adaptive Cruise Control) requires a system which controls the vehicle to keep the distance among the automobiles constant. This paper describes the microstrip array antennas designed to operate at 24 GHz, and used as a direction indicator of moving vehicles. $8{\times}2$ transmit away antenna with wide beamwidth, $8{\times}4$ receive center array antenna, and two $8{\times}8$ receive array antennas with narrow beamwidth were designed. The measured result shows that the designed array antennas arc suitable fur detecting 3 directions of the vehicle when the scan angle is within the restricted area.

• Journal of applied mathematics & informatics
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• 제6권3호
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• pp.859-866
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• 1999

In Eucliden k-space the cone of vectors x=($\chi$1, $\chi$2, ...,$\chi$k) satisfying $\chi$1$\leq$$\chi$ 2, $\leq$...$\leq$$\chi$k and {{{{ SUM { }`_{j } ^{k } }}= 1 $\chi$j=0 is generated by the vectors vj=(j-k,...j-k...j) having j-k's in its first j coordinates and j's for the remaining k-j coordinates for 1$\leq$j$\leq$i