• 대한조선학회논문집
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• 제48권5호
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• pp.445-450
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• 2011

In order to estimate a yacht sail performance, measuring system of aerodynamic forces acting on the yacht sail is constructed and experiments of flexible model sail are carried out at the medium-size subsonic wind tunnel of Chungnam National University. Experimental results for a flexible sail are compared with experimental and numerical results of fixed shape sail. In case of a fixed shape sail, lift and drag coefficients are rarely changed at all velocity conditions. However, those of the flexible sail are decreased as the incoming velocity is increased. These are understandably resulted from shape variations due to the flexible material. Therefore aero-elastic similarity should be more carefully considered in the model test rather than other similarities.

• 디지털콘텐츠학회 논문지
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• 제18권7호
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• pp.1451-1456
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• 2017

본 연구에서는 형상기억합금(SMA)을 응용한 스마트 액추에이터의 효율적 제어를 위한 통합 액추에이터-제어기 시스템 설계를 논의한다. 이를 위하여 두 개의 스마트 SMA 액추에이터 유닛과 함께 제어를 위한 싱글 칩 마이크로프로세서, 액추에이터 드라이버, 센서를 통합한 새로운 액추에이터-제어기 모듈을 설계하고 제작하였다. 제안된 시스템에서는 피드백 제어를 위해 모듈의 회전을 측정하는 6축 모션센서 칩과 SMA의 저항을 측정하는 회로를 포함한다. 실험을 통하여 액추에이터의 구동과 센서 신호와 통신을 확인하였고 이를 통하여 실제 액추에이터-제어기 시스템의 작동을 확인하였다.

• 한국기계가공학회지
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• 제16권3호
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• pp.69-75
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• 2017

There are two types of expensive measuring instruments currently on the market shape measurement and roundness measurement instruments. As they are very expensive, from tens of millions to more than 200 million won, buying them is economically burdensome for small companies or individuals. Therefore, in order to integrate the shape and roundness measurements into a single transfer device, this study aimed to reduce the trial and error by 3D modeling and simulation, and we confirmed the feasibility of operation. Based on these outcomes, a prototype hybrid measuring instrument was fabricated. As a result of performance evaluation and comparative evaluation, we verified the feasibility of implementation and application of the hybrid measuring instrument.

• 한국자동차공학회논문집
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• 제19권5호
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• pp.113-117
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• 2011

The frame for automotive assembly can be deformed and remained on the residual stress due to high temperature thermal attacks when in welding. The frame deformation can be made to problems when in assembly with body and the residual stress can affect the negative effect on durability performance of the automobile. In order to analyze the frame deformation, the simplified test frame which had the similar shape (form) of the real automotive frame was fabricated. The contactless optical 3D scanner was used for the shape difference measurement of the frame between before and after the welding. The FE-model of the test frame was composed and the heat transfer and thermal stress simulation were performed. The simulated results were compared with the measured results for the reference of the frame design. The deformation shape of the frame by simulation was in good agreement with that by the experimental measurement.

• 한국컴퓨터정보학회논문지
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• 제25권5호
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• pp.137-146
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• 2020

20대 미혼 여성 182명의 직접 계측치를 이용한 유방유형 분류에 유방전체 형상 요인, 유방상부내측형상 요인, 유방볼륨 요인, 유방하부외측형상 요인 등 4가지 요인이 추출되었다. 군집분석을 통해 '상부발달 유방', '밋밋한 유방', '하부 발달 유방', '돌출한 유방' 등 4유형의 유방유형으로 분류하였다. 유방유형은 목앞점~젖꼭지점길이, 목옆점~젖꼭지점길이, 유방안쪽점 사이간격, 젖꼭지 간격, 유방아래직경, 유방내측깊이, 유방바깥쪽길이, 유방아래길이, 젖가슴가쪽점~젖가슴위쪽점길이, 젖가슴 밑 윤곽선길이 등 10개 항목으로 판별 가능하다.

• Journal of Welding and Joining
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• 제17권6호
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• pp.53-61
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• 1999

The use of thick plate in increasing in recent years due to the rapid expansion of chemical plants, nuclear plants, ships and other industrial plants. Welding is the most popular joining techniques employed in manufacturing industrial machineries and structures. Normally, Groove shapes are prepared according to appropriate rules and regulations such as KS, JIS, AWS, LR, DNV and etc. for various thicknesses of plate. However those groove angles tend to be too large. As a result of large groove angle, residual stress, deformation of material and strength reduction is obtained. Therefore, the reliability and safety of structures and machinery tend to be decreasing. Therefore, in this paper, theoretical as well as experimental study are carried out to find optimum groove shapes for T-welded joint of mild steel. The test specimen are made in same condition with simulation model. Welding residual stresses measurement by sectional cutting method. ⅰ) The mechanical difference for change the thickness of plate and groove angle are not appeared. ⅱ) In a mechanical point of view minimum preparation angle(40°) is more suitable than maximum groove angle(60℃). ⅲ) The measurement value and distribution of welding residual stresses are not effected largely by groove angle. It is mechanical restraint that mainly affect welding residual stresses distribution. In mechanical point of view minimum groove angle is more suitable than maximum groove angle. Therefore, it is appropriate to minimize the size of groove shape in strength and safety.

• 한국의류학회지
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• 제29권2호
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• pp.367-378
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• 2005

The purpose of this study was to analyse craniofacial shape by 3D scanner for female adults with age groups. In this study, heads of 452 female adults were measured by 3D scanner. The obtained 25 measurements were analyzed by statistical methods. The results can be summarized as follows; 1. From the basic statistical data analysis, vertex-tragion and the length between the pupils were the longest in their twenties, and grew shorter in elderly groups. The length of nasion-subnasale and the width of mouth increased with an increased in age. 2. According to the analysis of the craniofacial proportions, the head type of female aduls was short-headed. The size of lower face increased with an increase in age. 3. The statistically noticeable differences were found in the measurement of the left and the right sides of face in the age groups of 20, 30, and 40. 4. High correlations were found in two perpendicular lengths, two horizontal lengths and two widths. 5. The order of factor analysis was as follows; the horizontal length, the perpendicular length and the width from highest.

• 한국기계가공학회지
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• 제20권7호
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• pp.25-32
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• 2021

In the previous study, a study was conducted to improve the exhaust gas intake efficiency by improving the existing soot measurement probe in the shape and angle of the exhaust port. As a result, it can be seen that the smoke measurement performance according to the shape and angle is improved. In previous studies, the performance of the soot probe was not confirmed for the Korean KD 147 mode, which has a low suction flow rate and a long inspection time. So, we would like to confirm the improvement of the smoke probe performance of the Korean KD 147 mode, which is close to the actual driving conditions. The probe used in this study is another type of probe, and has a circular ring shape instead of a rib and variable center position unit, so the probe center hole is located close to the center of the exhaust pipe.

• 한국재료학회지
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• 제29권1호
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• pp.59-64
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• 2019

This study investigates the optical characteristics of InGaN multiple quantum wells(MQWs) light emitting diodes(LEDs) on planar sapphire substrates(PSSs), nano-sized PSS(NPSS) and micro-sized PSS(MPSS). We obtain the results as the patterning size of the sapphire substrates approach the nanometer scale: The light from the back side of the device increases and the total light extraction becomes larger than the MPSS- and planar-LEDs. The experiment is conducted by Monte Carlo ray-tracing, which is regarded as one of the most suitable ways to simulate light propagation in LEDs. The results show fine consistency between simulation and measurement of the samples with different sized patterned substrates. Notably, light from the back side becomes larger in the NPSS LEDs. We strongly propose that the increase in the light intensity of NPSS LEDs is due to an abnormal optical distribution, which indicates an increase of extraction probability through NPSS.

• 한국지형학회지
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• 제27권2호
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• pp.19-28
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• 2020

Grain size analysis is the most basic procedure for identifying the origin, transport and sedimentation processes of sediments, and is widely used in geomorphology and sedimentology. Traditionally, grain size was determined by a sieve-pippette method, but the use of automated analyzers is increasing in recent years. These analyzers have many advantages over traditional techniques, but the measurement results are not always the same. It is still difficult to solve the pretreatment problem such as incomplete diffusion and residual organic matter, and inappropriate results may be obtained. This study compared image-based grain size analysis and sieve analysis to verify its statistical reliability, and conducted experiments to enhance the measurement accuracy using shape parameters. The results showed that the image-based analysis overestimated the grain size of sand dunes by about 7% compared to the sieve analysis, but the two measurements were not statistically different. In addition, by using shape parameters, such as aspect ratio, sphericity, and convexity, improved statistics were obtained compared to the original data. Using the morphological properties of the individual grains is a complementary method to the incomplete pretreatment of the grain size analysis process, and at the same time, it will contribute to improving the accuracy and reliability of the results.