• Title/Summary/Keyword: angle of incidence

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Influence of geometrical parameters of reentry capsules on flow characteristics at Mach 6

  • R.C. Mehta
    • Advances in aircraft and spacecraft science
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    • v.11 no.2
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    • pp.177-194
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    • 2024
  • The objective of this paper is to compute entire flow field over Apollo-II, Aerospace Reentry Demonstrator (ARD), Orbital Experiment (OREX) with sharp shoulder and rounded shape shoulder and Space Recovery Experiment (SRE) at different flare-cone half-angle of 20° and 35°. This paper addresses numerical solutions of the compressible three-dimensional Euler equations on hexahedral meshes for a freestream Mach 6 and at an angle of incidence 5°. Furthermore, spatial discretization is accomplished by a cell centred finite volume formulation solution and advanced in time by an explicit multi-stage Runge-Kutta method. The flow field characteristics, distribution of surface pressure coefficient and Mach number on fore-body and aft-body are presented as a function of the geometrical parameters of many reentry capsules. The surface pressure variation is numerically integrated to obtain the aerodynamic drag and compared well with impact theory. The present numerical study has observed the significant dependence of the blunt body and the aft-body geometry of the vehicle and can be used to study atmospheric conditions during re-entry trajectory. The numerical analysis reveals the significant influence of capsule geometry on the flow characteristics of the mechanism of upstream and structure of the flow near the wake region and aerodynamic drag coefficient.

Black Matrix with Scattering Particles for the Enhancement of Visibility of Laser Beam (레이저 빔 시인성 향상을 위한 산란입자가 분산된 Black Matrix)

  • Park, June Buem;Shin, Dong-Kyun;Han, Seun Gjo;Park, Jong-Woon
    • Journal of the Semiconductor & Display Technology
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    • v.16 no.4
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    • pp.36-40
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    • 2017
  • With an attempt to enhance the visibility of laser beam, we have investigated a black matrix with scattering particles by ray tracing simulations. As the scattering particle density is increased, the detected power by the receiver is increased, thereby enhancing the visibility. In reality, the visibility is reduced with increasing incident angle (away from the normal incidence) of laser beam, a phenomenon also observed by ray tracing simulations. It is due to the fact that the mean path is increased within a highly absorptive BM layer or a smaller number of rays hit the BM area when the incident angle is high. Embedding a number of scattering particles into BM may bring in crosstalk among pixels. However, it is negligible because scattered rays inside highly absorptive BM are re-scattered due to the high scattering particle density, decreasing the power of scattered rays into the active areas.

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Radiologic Assessment of Normal Acromial Arch (정상인의 견봉궁 형태에 대한 방사선 계측)

  • Hahn Sung Ho;Yang Bo Kyu;Yi Seung Rim;Jung Sun Uk;Yoo Sung Hwan
    • Clinics in Shoulder and Elbow
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    • v.2 no.2
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    • pp.106-109
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    • 1999
  • Purpose : The purpose of this study is to evaluate morphology of acromion in relation to age and symmetry in asymptomatic adults. Materials and Methods: Seventy five asymptomatic adults were divided into two groups by age(A group of age twenties and B group of age over forty) and both acromial outlet views were obtained. One hundred fifty radiographs were typed and assessed radiologically by methods of Getz and Liotard. Results: The relative percentages of acromial types I, Ⅱ, and Ⅲ were 3%, 90% and 7% in the A group and 6%, 82% and 12% in the B group respectively, Subacromial peak and spinoacromial angle were 4.3mm, 82 degrees in the A group and 4.6mm, 78 degrees in the B group. Conclusion: Incidence of type is not related to age in normal adult and type II is the most common type. Spinoacromial angle is decreased in older age group and type Ⅲ.

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The Effect of Pre-Operative Patient Controlled Analgesia Education on Elderly Patients with Total Knee Arthroplasty (슬관절 전치술 노인 환자의 수술 전 자가통증조절기 사용 교육이 수술 후 환자에게 미치는 효과)

  • Shim, Joohee;Choi-Kwon, Smi
    • Journal of Korean Biological Nursing Science
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    • v.16 no.4
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    • pp.318-325
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    • 2014
  • Purpose: The purpose of this study was to investigate the effects of preoperative patient controlled analgesia (PCA) education on total knee replacement arthroplasty (TKRA) patients' PCA usage, level of pain, the frequency of pro re nata (prn) administrations, number of ambulations/day and continuous passive motion (CPM) angle after TKRA. Methods: This research used the non-equivalent control group pre-test and post-test design. Forty-five TKRA patients at a hospital in Seoul, Korea were included for in the study. For the experimental group, a 20-minute education session was provided a day before surgery. Data were analyzed using Windows SPSS Statistics 21.0 program. Results: Knowledge was higher in the experimental group than in the control group (p<.001). Incidence of nausea was lower in the experimental group (p=.01). No significant differences were found in post-operative pain scores, the frequency of prn analgesics administrations, dizziness, number of ambulations/day and CPM angle. Conclusion: This study showed that pre-operative PCA education could be an effective nursing intervention for increasing patient knowledge on PCA and nausea reduction after TKRA.

Enhancement of Light Guiding Efficiency in CMOS Image Sensor by Introducing an Optical Thin Film (광학 박막을 채용한 CMOS 이미지 센서 픽셀의 수광 효율)

  • Kang, Myung-Hoon;Ko, Eun-Mi;Lee, Je-Won;Cho, Guan-Sik
    • Korean Journal of Optics and Photonics
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    • v.20 no.1
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    • pp.57-60
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    • 2009
  • We consider introducing an optical thin film to the light guiding wall of a pixel in order to enhance the light guiding efficiency of a CMOS image sensor. Simulating the reflectance as a function of the incidence angle using the Essential Macleod program, we find that the range of total internal reflection is greatly increased for several materials. Particularly when air is chosen as the thin film material, the critical angle of total internal reflection could be shifted to about 50 degrees.

An Experimental Study on the Lift and Thrust Generation of a Dragonfly-type Model (잠자리유형 모델의 추력 및 양력생성에 관한 실험적 연구)

  • Kim, Song-Hak;Chang, Jo-Won
    • Journal of the Korea Institute of Military Science and Technology
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    • v.9 no.4
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    • pp.120-127
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    • 2006
  • An experimental study was carried out in order to investigate the effects on the fore- and hind-wings of a dragonfly-type model. A model with two pairs of wing was developed to measure the lift and thrust of a dragonfly-type model. The fore-wing and hind-wing had incidences angle of $0^{\circ}\;and\;10^{\circ}$. The freestream velocity is 1.6m/sec and the corresponding chord Reynolds number was $Re=2.88{\times}10^3$. Also, these experiments were carried out with a phase difference of $90^{\circ}$ between the fore- and hind-wing, aerodynamic forces caused by fore-wing only and two pairs of wings were investigated according to the reduced frequency. The results show that the model with fore-wings only generates a thrust component; however, the dragonfly-type model with hind-wings with an incidence angle of $10^{\circ}$ generates a drag component. The total drag is also increased with reduced frequency due to the increased lift of hind-wings.

Optical Properties of Hydrogenated Amorphous Chalcogenide Thin Films (수소화 처리된 비정질 칼코게나이드 박막의 광학적 특성)

  • Nam Gi-Yeon;Kim Jun-Hyung;Cho Sung-June;Lee Hyun-Yong
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.19 no.5
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    • pp.450-456
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    • 2006
  • In this paper, we report the changes of morphology, transmittance and photoluminescence (PL) in hydrogenated amorphous $As_{40}Ge_{10}Se_{15}S_{35}$ thin films, thermally deposited at the vapor incidence angles (${\theta}$) of $0^{\circ},\;45^{\circ}\;and\;80^{\circ}$. The hydrogenation was carried out under the condition of a $H_2$ pressure ($P_H$) of 20 atm and an annealing temperature range, $T_{Anneal}$ of $150^{\circ}C{\sim}210^{\circ}C$. A columnar structures with an inclination angle of approximately $65{\sim}70^{\circ}$ was formed in $80^{\circ}$-deposited films and then the columnar was broken after hydrogenation. Transmittance increases with an increase of deposition angle and by the hydrogenation. In particular, a broad PL band on the extended region is observed in obliquely deposited films and it increases during the hydrogenation.

Characteristics and analysis of clamp-type optical current transformer using faraday effect (Faraday효과를 이용한 클램프형 광-전류 변류기의 특성 및 분석)

  • 김수길;이용욱;이병호;송민호;임용훈
    • Korean Journal of Optics and Photonics
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    • v.14 no.4
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    • pp.399-405
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    • 2003
  • We manufactured a clamp-type optical current transformer (COCT) head using FD10 glass. It was manufactured of two parts of FD10 glass with symmetrical structure and was designed so that light propagates along the critical angle in order to avoid a phase difference with the light within the sensor head at reflection. Also, we measured and analyzed the current of conductor from 0 to 1,000 AT, change of optical power with incidence angle of light, temperature and polarization of light, long-term current measurement using COCT head, and demonstrated the feasibility of manufactured COCT through those experiments.

Effect of Blade Angles on a Micro Axial-Type Turbine Operated in a Low Partial Admission Rate (부분분사 마이크로 축류형터빈에서의 익형각 효과에 관한 연구)

  • Cho, Soo-Yong;Cho, Bong-Soo;Cho, Chong-Hyun
    • Journal of the Korean Society of Propulsion Engineers
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    • v.11 no.4
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    • pp.10-18
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    • 2007
  • A tested micro axial-type turbine consists of two stages and its mean radius of rotor flow passage is 8.4 mm. This turbine could be applied to a driver of micro power system, and its rotational speed in the unloaded state reaches to 100,000 RPM. The performance of this system is sensitive depending on the blade angles of the rotor and stator because it is operated in a low partial admission rate, so a performance test is conducted through measuring the specific output power and the net specific output torque with various blade angles on the nozzle, stator and rotor. The experimental results show that the net specific output torque is varied by 15% by changing the rotor blade angle, and the optimal incidence angle is about $10.3^{\circ}$.

A Study on the Incident Angle Estimation Method of Target at Coherent Interference (상관성 간섭에서 표적의 입사각 추정 방법에 대한 연구)

  • Shin, Ho-Sub
    • Journal of the Korea Society of Computer and Information
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    • v.15 no.5
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    • pp.75-81
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    • 2010
  • Adaptive array antenna system estimates target signal, as making a null pattern toward the interference signal. However, receiving a coherent interference signal at adaptive array antenna system, as target signal is regarded as interference signal, the performance of system rapidly decreases. The main beam does not direct an incidence direction of target signal due to sensitivity in directivity error. This paper proposes beamforming algorithm which combines high order limit condition and directivity error modify method. And it minimizes degree of freedom and decreases interference signal and directivity error using proposed algorithm. This paper compares and analyzes the performance of proposed algorithm and general algorithm using simulation. In this paper, the proposed algorithm correctly estimates an incident angle, but general algorithm occurs an error of about $0.8^{\circ}$.