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검색결과 1,550건 처리시간 0.031초

Does Strategy of Downward Stepping Stair Due to Load of Additional Weight Affect Lower Limb's Kinetic Mechanism?

  • Ryew, Checheong;Yoo, Taeseok;Hyun, Seunghyun
    • International journal of advanced smart convergence
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    • 제9권4호
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    • pp.26-33
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    • 2020
  • This study measured the downward stepping movement relative to weight change (no load, and 10%, 20%, 30% of body weight respectively of adult male (n=10) from standardized stair (rise of 0.3 m, tread of 0.29 m, width of 1 m). The 3-dimensional cinematography and ground reaction force were also utilized for analysis of leg stiffness: Peak vertical force, change in stance phase leg length, Torque of whole body, kinematic variables. The strategy heightened the leg stiffness and standardized vertical ground reaction force relative to the added weights (p<.01). Torque showed rather larger rotational force in case of no load, but less in 10% of body weight (p<.05). Similarly angle of hip joint showed most extended in no-load, but most flexed in 10% of body weight (p<.05). Inclined angle of body trunk showed largest range in posterior direction in no-load, but in vertical line nearly relative to added weights (p<.001). Thus the result of the study proved that downward stepping strategy altered from height of 30 cm, regardless of added weight, did not affect velocity and length of lower leg. But added weight contributed to more vertical impulse force and increase of rigidity of whole body than forward rotational torque under condition of altered stepping strategy. In future study, the experimental on effect of weight change and alteration of downward stepping strategy using ankle joint may provide helpful information for development of enhanced program of prevention and rehabilitation on motor performance and injury.

5.1~5.8 GHz 무선랜용 CPW 급전 소형 모노폴 안테나 (A CPW-fed Small Monopole Antenna for 5.1~5.8 GHz WLAN)

  • 최인태;신호섭
    • 한국정보통신학회논문지
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    • 제23권12호
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    • pp.1659-1665
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    • 2019
  • 본 논문에서는 WLAN (wireless local area network) 응용을 위한 소형 인쇄형 모노폴 안테나의 새로운 설계에 대해 연구했다. 선폭이 다른 패치와 계단 모양의 접지면이 있는 복사체는 안테나 크기를 줄이기 위해 사용된다. 안테나의 크기는 16 × 17 × 1 ㎣이며 포토리소그래피(photolithography) 기술로 제작되었다. 시뮬레이션 및 측정 결과가 잘 일치한다. 연구된 안테나의 공진 주파수는 약 5.2 GHz이며 측정 결과 1 GHz의 임피던스 대역폭을 가진다. 또한 측정된 방사패턴을 제시하고 필요한 WLAN 5 GHz 주파수 대역 (5.15 - 5.825 GHz)에서 측정된 이득 및 효율을 제시했으며, 5 GHz 대역 WLAN 안테나로 사용할 수 있음을 확인했다. 연구된 안테나는 소형, 경량, 저비용, 전방향성 복사패턴, 고이득 및 고효율을 갖는다.

Precise System Models using Crystal Penetration Error Compensation for Iterative Image Reconstruction of Preclinical Quad-Head PET

  • Lee, Sooyoung;Bae, Seungbin;Lee, Hakjae;Kim, Kwangdon;Lee, Kisung;Kim, Kyeong-Min;Bae, Jaekeon
    • Journal of the Korean Physical Society
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    • 제73권11호
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    • pp.1764-1773
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    • 2018
  • A-PET is a quad-head PET scanner developed for use in small-animal imaging. The dimensions of its volumetric field of view (FOV) are $46.1{\times}46.1{\times}46.1mm^3$ and the gap between the detector modules has been minimized in order to provide a highly sensitive system. However, such a small FOV together with the quad-head geometry causes image quality degradation. The main factor related to image degradation for the quad-head PET is the mispositioning of events caused by the penetration effect in the detector. In this paper, we propose a precise method for modelling the system at the high spatial resolution of the A-PET using a LOR (line of response) based ML-EM (maximum likelihood expectation maximization) that allows for penetration effects. The proposed system model provides the detection probability of every possible ray-path via crystal sampling methods. For the ray-path sampling, the sub-LORs are defined by connecting the sampling points of the crystal pair. We incorporate the detection probability of each sub-LOR into the model by calculating the penetration effect. For comparison, we used a standard LOR-based model and a Monte Carlo-based modeling approach, and evaluated the reconstructed images using both the National Electrical Manufacturers Association NU 4-2008 standards and the Geant4 Application for Tomographic Emission simulation toolkit (GATE). An average full width at half maximum (FWHM) at different locations of 1.77 mm and 1.79 mm are obtained using the proposed system model and standard LOR system model, which does not include penetration effects, respectively. The standard deviation of the uniform region in the NEMA image quality phantom is 2.14% for the proposed method and 14.3% for the LOR system model, indicating that the proposed model out-performs the standard LOR-based model.

경주 월성 해자 유적 출토 목제방패의 형태, 연대 및 수종분석을 통한 신라 방패의 기초적 연구 (A Fundamental Study of the Silla Shield through the Analysis of the Shape, Dating, and Species Identification of Wooden Shields Excavated from the Ruins of Wolseong Moat in Gyeongju)

  • NAM, Tae-Gwang;KIM, Hun-Suk
    • Journal of the Korean Wood Science and Technology
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    • 제49권2호
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    • pp.154-168
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    • 2021
  • 경주 월성의 본격적인 발굴조사로 다양한 종류의 목제유물이 출토되고 있다. 특히 월성의 주위를 둘러싸고 있는 해자에서 다량 출토되었다. 본 연구에서는 월성 해자에서 출토된 목제방패 2점의 수종분석, 방사성탄소연대측정, 그리고 형태분석을 통해 신라시대 방패에 대한 기초자료를 확보하고자 하였다. 연대측정 결과, 4세기 중반에서 5세기 초반에 벌채된 목재를 사용하여 제작되었음이 확인되었다. 수종분석 결과, 유물의 몸체는 소나무속 연송류로, 손잡이는 느티나무속 느티나무로 식별되었다. 출토 목제방패의 제작 순서는 판목으로 가공된 판에 얇은 선으로 구획을 표시한 후 이중동심원을 구획하고 작은 구멍을 투공한 것으로 확인되었다. 구획선 사이의 간격을 측정한 결과 약 6cm로 일정하고, 붉은 색과 검은 색으로 채색되어 있다. 형태 분석을 통해 유물의 너비는 각각 50cm, 36cm 이상으로 추정했다.

Digital Micromirror Device와 Polygon scanner의 Lithography 특성에 따른 산업적 분석 (Industrial analysis according to lithography characteristics of digital micromirror device and polygon scanner)

  • 김지훈;박규백;박정래;고강호;이정우;임동욱
    • Design & Manufacturing
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    • 제15권4호
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    • pp.65-71
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    • 2021
  • In the early days of laser invention, it was simply used as a measuring tool, but as lasers became more common, they became an indispensable processing tool in the industry. Short-wavelength lasers are used to make patterns on wafers used in semiconductors depending on the wavelength, such as CO2 laser, YAG laser, green laser, and UV laser. At first, the hole of the PCB board mainly used for electronic parts was not thin and the hole size was large, so a mechanical drill was used. However, in order to realize product miniaturization and high integration, small hole processing lasers have become essential, and pattern exposure for small hole sizes has become essential. This paper intends to analyze the characteristics through patterns by exposing the PCB substrate through DMD and polygon scanner, which are different optical systems. Since the optical systems are different, the size of the patterns was made the same, and exposure was performed under the optimal conditions for each system. Pattern characteristics were analyzed through a 3D profiler. As a result of the analysis, there was no significant difference in line width between the two systems. However, it was confirmed that dmd had better pattern precision and polygon scanner had better productivity.

무봉제 니트웨어의 소매디자인 향상을 위한 연구 (A study on the improvement of seamless knitwear sleeve design)

  • 강희명;기희숙
    • 한국의상디자인학회지
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    • 제23권4호
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    • pp.57-71
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    • 2021
  • The purpose of the study is to derive an appropriate knitting method that can increase the appearance, wearability, and functionality through empirical research on the sleeve height knitting ratio of seamless knit wear. The study was conducted by producing seven types of experiment clothes according to knitting ratio to examine the characteristics according to the body armhole and sleeve height ratio. Specifically, after fit evaluatins, variance analysis (ANOVA) was performed to analyze the results of the evaluation, and the evaluated contents were converted into data. Among them, the items with significant results were intensively studied using the Duncan-test. The result showed that the height and the width of the sleeves vary depending on the knitting ratio. Test sweater A was the highest at 16cm, followed by test sweater B, test sweater C, test sweater D, test sweater E, test sweater F, and test sweater G at 4cm. The 1:1 ratio of test sweater A, was the highest, which is knitted in the same course as the body. The larger the difference in the ratio of body and sleeve, the lower the height of the sleeves. As a result of the appearance sensory evaluation, a significant difference was confirmed in the result values (p<0.001) from all items on the front, side, and rear. Specifically, the appearance of the test sweater B(2:4:2) on the front and test sweater C(2:4:3) on the side and rear side was the best. When the sleeves height is properly set, the ratio of the arm line to fit the design with a natural curve is analyzed as a very important factor. The results of this study are expected to be of practical use in product development and production that can increase the feeling when wearing and design satisfaction.

Study on bearing characteristic of rock mass with different structures: Physical modeling

  • Zhao, Zhenlong;Jing, Hongwen;Shi, Xinshuai;Yang, Lijun;Yin, Qian;Gao, Yuan
    • Geomechanics and Engineering
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    • 제25권3호
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    • pp.179-194
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    • 2021
  • In this paper, to study the stability of surrounding rock during roadway excavation in different rock mass structures, the physical model test for roadway excavation process in three types of intact rock mass, layered rock mass and massive rock mass were carried out by using the self-developed two-dimensional simulation testing system of complex underground engineering. Firstly, based on the engineering background of a deep mine in eastern China, the similar materials of the most appropriate ratio in line with the similarity theory were tested, compared and determined. Then, the physical models of four different schemes with 1000 mm (height) × 1000 mm (length) × 250 mm (width) were constructed. Finally, the roadway excavation was carried out after applying boundary conditions to the physical model by the simulation testing system. The results indicate that the supporting effect of rockbolts has a great influence on the shallow surrounding rock, and the rock mass structure can affect the overall stability of the surrounding rock. Furthermore, the failure mechanism and bearing capacity of surrounding rock were further discussed from the comparison of stress evolution characteristics, distribution of stress arch, and failure modes in different schemes.

초고속 미세 액적 충돌을 이용한 나노미터 크기 입자상 오염물질의 세정에 대한 CFD 시뮬레이션 (CFD simulation of cleaning nanometer-sized particulate contaminants using high-speed injection of micron droplets)

  • 박진효;김정건;이승욱;이동근
    • 한국입자에어로졸학회지
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    • 제18권4호
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    • pp.129-136
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    • 2022
  • The line width of circuits in semiconductor devices continues to decrease down to a few nanometers. Since nanoparticles attached to the patterned wafer surface may cause malfunction of the devices, it is crucial to remove the contaminant nanoparticles. Physical cleaning that utilizes momentum of liquid for detaching solid nanoparticles has recently been tested in place of the conventional chemical method. Dropwise impaction has been employed to increase the removal efficiency with expectation of more efficient momentum exchange. To date, most of relevant studies have been focused on drop spreading behavior on a horizontal surface in terms of maximum spreading diameters and average spreading velocity of drop. More important is the local liquid velocity at the position of nanoparticle, very near the surface, rather than the vertical average value. In addition, there are very scarce existing studies dealing with microdroplet impaction that may be desirable for minimizing pattern demage of the wafer. In this study, we investigated the local velocity distribution in spreading liquid film under various impaction conditions through the CFD simulation. Combining the numerical results with the particle removal model, we estimated an effective cleaning diameter (ECD), which is a measure of the particle removal capacity of a single drop, and presented the predicted ECD data as a function of droplet's velocity and diameter particularly when the droplets are microns in diameter.

중국 재배지역별 단삼의 내부형태 및 이화학적 패턴 연구 (A Study on Internal Morphology and Physicochemical Patterns of Salvia miltiorrhiza Bunge Root According to Cultivation Regions in China)

  • 구법성;유지현;길기정
    • 대한본초학회지
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    • 제34권1호
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    • pp.33-42
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    • 2019
  • Objectives : This study aimed to be used as basic data for obtaining excellent quality of Salvia miltiorrhiza (SM) root. Methods : SM cultivated in Anhui Bozou, Henan, Shandong, Henan Wenxian, Zhejiang, Hebei, Liaoning, Shanxi, Shaanxi Shangluo, Sichuan Zhongjiang, Sichuan Minyang and Jiangsu in China were gathered and its internal morphology and physicochemical patterns were analyzed. Results : Cross-section of sang plants according to cultivated regions in China showed that cork layers consisted of cells with four to six layers, cortex width was wide, and phloem was semilunar-shaped. Although there are forms layers, yet boundary was vague. It was observed that eight to ten vascular bundles were arranged in wooden parts in all directions and as a single line of vascular was distributed nearby form layers as it nears to the center. Tanshinon IIA identified a spot in the same location with standard product near by Rf 0.9 in the test identifying TLC of SM according to cultivated areas in China. The largest amount was 0.535% identified in Shandong and the lowest amount of 0.05% in Hebei. Salvianolic acid B identified a spot in the same location with standard product near by Rf 0.7 in the test identifying TLC of SM according to cultivated areas in China. The largest amount was 2.72% identified in Liaoning and the lowest amount of 0.825% in Jiangsu. Conclusions : The results are assumed to be used as basic data for obtaining excellent quality of SM oriental medical hers and distinguishing authentic or fake herbs.

T자형 급전선과 스파이럴구조를 이용한 이중대역 소형패치 안테나 설계에 관한 연구 (A Study on the Design of Dual-Band Small Pacth Antenna using T-shaped Feeder and Spiral Structure)

  • 이윤민;신진섭
    • 한국인터넷방송통신학회논문지
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    • 제22권4호
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    • pp.35-40
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    • 2022
  • 본 논문은 전자제품의 PCB 기판 외곽에 위치시켜 ISM 대역에서 무선통신이 가능하도록 하는 안테나를 제안하였다. PCB에서는 부품의 간섭 또는 디자인에 방해가 되지 않도록 소형화하기 위해 T자형 OPEN - STUB 급전선을 설계하였다. T자형 스터브 급전선과 스파이럴 구조를 이용하여 각각 2.4GHz, 5.8GHz 대역에서 안테나의 특성을 확인하였다. 실험을 위하여 안테나 크기는 가로 5mm × 세로 6.5mm의 크기로 하였으며 PCB두께는 1.2T로 하여 제작하였다. 제작된 안테나의 실험 측정결과 2.4GHz, 5.8GHz에서 -10dB 이상의 반사손실을 얻을 수 있었다. 또한 E-plane에서 이득은 -4.45dBi로 나타났으며, H-plane에서 이득은 -1.05dBi 나타났다. 따라서 여기서 제안된 무선통신용 소형안테나에서 우수한 성능을 나타내었다.