• 제목/요약/키워드: Alignment degree

검색결과 197건 처리시간 0.029초

Physical modeling of dust polarization spectrum by RAT alignment and disruption

  • Lee, Hyeseung;Hoang, Thiem
    • 천문학회보
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    • 제46권2호
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    • pp.38.1-38.1
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    • 2021
  • Dust polarization depends on the physical and mechanical properties of dust, as well as the properties of local environments. To understand how dust polarization varies with grain mechanical properties and the local environment, in this paper, we model the wavelength-dependence polarization of starlight and polarized dust emission by aligned grains by simultaneously taking into account grain alignment and rotational disruption by radiative torques (RATs). We explore a wide range of the local radiation field and grain mechanical properties characterized by tensile strength. We find that the maximum polarization and the peak wavelength shift to shorter wavelengths as the radiation strength U increases due to the enhanced alignment of small grains. Grain rotational disruption by RATs tends to decrease the optical-near infrared polarization but increases the ultraviolet polarization of starlight due to the conversion of large grains into smaller ones. In particular, we find that the submillimeter (submm) polarization degree at 850㎛(P850) does not increase monotonically with the radiation strength or grain temperature (Td), but it depends on the tensile strength of grain materials. Our physical model of dust polarization can be tested with observations toward star-forming regions or molecular clouds irradiated by a nearby star, which have higher radiation intensity than the average interstellar radiation field. Finally, we compare our predictions of the P850-Td relationship with Planck data and find that the observed decrease of P850 with Td can be explained when grain disruption by RATs is accounted for, suggesting that interstellar grains unlikely to have a compact structure but perhaps a composite one. The variation of the submm polarization with U (or Td)can provide a valuable constraint on the internal structures of cosmic dust

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국내 도로노선의 친환경도 평가 분석 (Assessment of Environment - Friendly Degree in Road routes)

  • 강호근;김상태;김흥래;박태권;안성순;이상은
    • 한국도로학회논문집
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    • 제13권1호
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    • pp.129-138
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    • 2011
  • 본 연구에서는 노선선정과정에서 정량적으로 환경성을 평가할 수 있는 방법에 대한 각종 제도 및 문헌을 고찰해 보고, 이를 바탕으로 도로노선의 정량적 환경성 평가 방법을 제안하였으며 이를 국내에 계획된 도로노선에 적용하여, 국내도로에 대한 친환경성을 평가하였다. 이에 따라 중부권, 강원권, 남부권의 지역별 사례구간을 선정하고 제안된 환경성 평가방법을 수행하였다. 그 결과 각 지역별 사례구간의 해당 지역에 대한 환경점수대의 분포가 다양하게 나타남을 확인하였다. 또한 각 노선의 환경적인 정도를 나타낼 수 있도록 해당지역의 환경영향 최소화 경로를 생성한 후 이를 기준으로 각 노선의 친환경도를 분석하였다. 그 결과 지역의 환경적 민감도가 큰 지역 즉, 높은 점수대가 많은 지역인 강원권에 설계된 노선의 친환경도가 가장 낮게 분석된 결과를 볼 수 있었다.

광시야 망원경 3호기 (NEOPAT-3)의 광학계 특성 및 조정 (OPTICAL PROPERTY AND ALIGNMENT OF KAO WIDE FIELD TELESCOPE (NEOPAT-3))

  • 육인수;경재만;윤요나;윤재혁;임홍서;문홍규;한원용;변용익;강용우;유성렬
    • Journal of Astronomy and Space Sciences
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    • 제21권4호
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    • pp.417-428
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    • 2004
  • 광시야 망원경 3호기의 광학계 특성을 조사하고 이를 바탕으로 광학계를 조정하였다. 보정렌즈를 쓰기 때문에 필터는 V, R, I로 제한된다. 광시야 망원경 3호기는 초점비가 작기 때문에 광학계의 정렬 상태에 매우 민감하다. 2도${\times}2$도의 시야각 내에서 성상의 RMS 반경을 $8{\mu}m$ 이내로 맞추려면 다음의 조건을 만족해야 한다: 1) 관측기기는 초점면에 대하여 0.05도 이상 기울어지면 안된다. 2) 주경과 보정렌즈의 축간 거리(decenter)를 1mm 이내로 맞추어야 한다. 3) 주경과 보정렌즈 사이를 최적 거리에서 2.3mm 이내로 맞추어야 한다. 광시야 망원경 3호기는 곡률감지법을 이용한 수차 측정법으로 광학계를 조정하고 있으며 마무리 단계에 있다. 현재 대덕전파천문대 옥상에 임시로 설치되어 시스템 정상화와 인공위성 관측을 수행하고 있다.

순서형 프로빗모형에 의한 이륜차 사고심각도의 영향요인 분석 (Analysis of Factors influencing Severity of Motorcycle Accidents using Ordered Probit Model)

  • 최정우;금기정
    • 한국도로학회논문집
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    • 제16권5호
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    • pp.143-154
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    • 2014
  • PURPOSES : This study drew factors affecting motorcycle accidents in Seoul by severity using an ordered probit model and aimed to analyze and verify the drawn influence factors. METHODS : As the severity of the accidents could be classified into three types (fatal injury, serious injury and minor injury), this study drew the factors affecting accidents by a comparative analysis employing an ordered probit model, removed the variables that would not secure significance sequentially to construct a model with high explanatory power regarding the factors affecting the severity of motorcycle accidents, and calculated the marginal effect of each factor to understand the degree of each factor's impact on the severity. First, Model 1 put in all variables; Model 2 was constructed by removing the variables of the road surface conditions that could not meet the level of significance (p=0.608); Model 3 was constructed by removing gender variable (p=0.423); and Model 4 was constructed finally by removing age variable (p=0.320). RESULTS : As a result of an analysis, statistically significant variables were time of occurrence, type of accident, road alignment and motorcycle displacement, and it turned out that the impacts on the severity were in the following order: a road alignment of left downhill, the type of motorcycle-to-vehicle accidents and a road alignment of a flatland on the left. The significance of the models was tested using the likelihood ratio, the level of significance and suitability statistics about them, and as a result of the test, the significance level and suitability of the constructed models were all excellent. In addition, the model accuracy indicating the accuracy of a predicted value compared to that of the value actually observed was 70.3% for minor injury; 70.1% for serious injury; and 68.6% for fatal injury, and the overall accuracy was 70.2%, which was very high. CONCLUSIONS : As a result of an analysis of motorcycle accidents in Seoul through the ordered probit model and the marginal effect, it turned out that their severity increased in nighttime accidents as compared to daytime ones and gradually increased in the order of motorcycle-to-vehicle accidents, motorcycle-to-person ones and the ones involving motorcycle only. As a result of an analysis, the severity of accidents in road alignments of left downhill, left flatland and straight downhill increased as compared to those in a road alignment of straight flatland and that the severity of accidents of motorcycles with a displacement larger than 50cc was higher than that of those with a displacement smaller than 50cc.

소형위성용 모터 구동형 포커싱 메커니즘 (A Motor-Driven Focusing Mechanism for Small Satellite)

  • 정진원;최준우;이동규;황재혁;김병규
    • 항공우주시스템공학회지
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    • 제12권4호
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    • pp.75-80
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    • 2018
  • 위성용 카메라의 경우 광학계의 초점을 제어하기 위한 포커싱 메커니즘이 필수적이다. 그러나 국내의 위성용 광학계 포커싱 메커니즘 관련 연구는 시작 단계이며, 관련 보유 기술 또한 열제어형에 국한되어있다. 따라서 본 논문에서는 소형위성용 광학계에 적용 가능한 모터 구동형 포커싱 메커니즘을 제안하였다. 제안된 메커니즘은 모터 구동에 의해 secondary mirror에 z축 변위를 발생시키도록 설계하였다. 또한 서포터에 flexure hinge를 설치하여 사전하중을 가하도록 하여 메커니즘내 부품간 제작공차 및 조립공차로 인한 정렬도 오차를 최소화하도록 하였다. 메커니즘 제작 후 LVDT 센서(linear variable differential transformer sensor)와 레이저 변위측정기로 정렬도(de-space, de-center, tilt)를 측정한 결과 소형위성광학계에 적용 가능한 수준의 정렬도를 갖는 것을 확인하였다.

The Alignment of Liquid Crystals on the Film Surfaces of Soluble Aromatic Polyimides Bearing t-Butylphenyl and Trimethylsilylphenyl Side Groups

  • Hahm, Suk-Gyu;Jin, Kyeong-Sik;Park, Sam-Dae;Ree, Moon-Hor;Kim, Hyung-Sun;Kwon, Soon-Ki;Kim, Yun-Hi
    • Macromolecular Research
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    • 제17권12호
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    • pp.976-986
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    • 2009
  • With the study goal of firstly elucidating the anisotropic interactions between oriented polymer chain segments and liquid crystal (LC) molecules, and secondly of determining the contributions of the chemical components of the polymer segments to the film surface topography, LC alignment, pretilt, and anchoring energy, we synthesized three dianhydrides, 1,4-bis(4'-t-butylphenyl)pyromellitic dianhydride (BBPD), 1,4-bis(4'-trimethylsilylphenyl)pyromellitic dianhydride(BTPD), and 2,2'-bis(4"-tert-butylphenyl)-4,4',5,5'-biphenyltetracarboxylic dianhydride (BBBPAn), and a series of their organosoluble polyirnides, BBPD-ODA, BBPD-MDA, BBPD-FDA, BTPD-FDA, and BBBPAn-FDA, which contain the diamines 4,4'-oxydianiline (ODA), 4,4'-methylenediamine (MDA), and 4,4'-(hexafluoroisopropylidene)dianiline (FDA). All the polyimides were determined to be positive birefringent polymers, regardless of the chemical components. Although all the rubbed polyimide films exhibited microgrooves which were created by rubbing process, the film surface topography varied depending on the polyimides. In all the rubbed films, the polymer chains were unidirectionally oriented along the rubbing direction. However, the degree of in-plane birefringence in the rubbed film varied depending on the polyimides. The rubbing-aligned polymer chains in the polyimide films effectively induced the alignment of nematic LCs along their orientation directors by anisotropic interactions between the preferentially oriented polymer chain segments and the LCs. The azimuthal and polar anchoring energies of the LCs ranged from $0.45{\times}10^{-4}\;-\;1.37{\times}10^{-4}\;J/m^2$ and from $0.86{\times}10^{-5}\;-\;4.26{\times}10^{-5}\;J/m^2$, respectively, depending on the polyimides. The pretilt angles of the LCs were in the range $0.10-0.62^{\circ}$. In summary, the soluble aromatic polyimides reported here are promising LC alignment layer candidates for the production of advanced LC display devices.

펄스자장을 이용한 고이방화 Nd-Fe-B자석의 종축자장성형방법 (Axial Pressing Method Using Pulse Magnetizing Field for the Preparation of Nd-Ee-B Sintered Magnets)

  • 김동환;강병길;장동열;김승호;김상면;장태석
    • 한국자기학회지
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    • 제13권4호
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    • pp.182-186
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    • 2003
  • 펄스자장종축성형법(pulse die press, PDP)을 이용하여 32 wt%RE-67 wt%TM-1 wt%B(RE: 희토류원소, TM: 30천이금속)조성을 갖는 소결자석을 제조함에 있어서 자장성형시 분말의 탭밀도, 성형밀도, 인가자장세기 및 인가방법의 변화에 따라 얻어지는 자석의 배향율과 감자곡선상의 각형성 변화를 조사하였다. 출발합금 제조방법으로서 strip casting process에 의하여 $\alpha$-Fe 편석없이 미세하고 균일한 조직을 갖는 합금 flake가 얻어졌고, 합금 flake를 수소처리한 후 고압가스를 이용한 건식분쇄방법(jet mill)에 의하여 평균입도, 표준편차가 각각 3.65 $\mu\textrm{m}$, 1.39인 미세하고 균일한 입도의 분말로 제조하였다. 제조된 분말은 30-50 kOe치 고펄스자장에 의하여 분말을 배향시키고 동일한 펄스자장을 인가하면서 종축성형을 실시함으로써 배향율을 향상시킬 수 있었다. 결과적으로 32 wt%RE조성의 분말을 이용하여 종전의 자장성형방법인 TDP(transverse die press)와 본 연구에서 제안된 PDP에 의하여 제조된 자석의 최대자기에너지적은 각각 42.0 MGOe 및 44.8 MGOe가 얻어져, PDP가 분말의 배향율과 감자곡선상의 각 형성을 향상시키는데 효과적인 자장성형방법임을 알 수 있었다.

안굽이 및 밖굽이 무릎을 가진 젊은 성인들에게서 등척성 운동 시 안쪽넓은근과가쪽넓은근의 근수축 개시시간 차이 (Differences of Onset Timing Between Vastus Medialis and Lateralis during Knee Isometric Contraction on Individuals with Genu Varum or Valgum)

  • 박설;이우진;박지원
    • The Journal of Korean Physical Therapy
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    • 제26권1호
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    • pp.9-14
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    • 2014
  • Purpose: The purpose of this study was to investigate how different knee alignments (genu varum and genu valgum) affected activations of quadriceps muscles with measurements of onset-time differences between vastus medialis and vastus lateralis during isometric contractions at both 30 and 60 degree knee flexion. Methods: Fifty-two adults (20 genu varum, 12 genu valgum, and 20 control) were enrolled in this study. Subjects with over 4cm distance between knee medial epicondyles were assigned to Genu varum, while subjects with over 4cm distance between ankles medial malleolus were considered as genu valgum group. Surface EMG was used to measure onset time of both vastus medialis and vastus lateralis during isometric contraction at 30 and 60 degree knee flexion. Results: The onset time of vastus lateralis was delayed in genu varum group, and that of vastus medialis was delayed in genu valgum group at both 30 and 60 degree knee flexions. Moreover, onset time difference at $30^{\circ}$ knee flexion between muscles was larger in genu valgum group than genu varum group. Conclusion: Subjects with genu varum or valgum activated quadriceps muscles with different orders pending on flexion degrees. Therefore, when quadriceps training program were planned to prevent pain or deformities, the findings that quadriceps were activated with different orders affected by knee alignments and joint degree at which trainings were performed, must be considered. If the selective training programs of quadriceps femoris are planned to prevent pain or deformities due to poor knee alignments, these should consider the subject's knee alignment condition.

CEO 가치관 및 컨설턴트 역량이 전략컨설팅 성공과 성과에 미치는 영향 (The Effect of CEO Values and Consultant Capabilities on Strategic Consulting Success and Performance)

  • 송명도;유연우;김정렬
    • 산업융합연구
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    • 제20권8호
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    • pp.15-23
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    • 2022
  • 본 논문은 CEO의 가치관, 컨설턴트의 역량, 근로자와의 가치일치성이 전략컨설팅 성공과 성과에 미치는 영향에 대하여 조사, 연구하였다. 설문을 통한 180부의 자료로, 요인분석, 신뢰성 및 타당성 분석을 실시하였고 최종 연구 모형에 대한 구조방정식을 실시하였다. 분석 결과는, 혁신성과 관리역량은 가치일치성에 유의한 영향을 미치는 것으로 나타났고. 가치일치성은 완성도와 활용도에, 완성도와 활용도는 만족도와 경영성과기여도에 유의한 영향을 미치는 것을 확인할 수 있었다.

Fuzzy logic based estimation of effective lengths of columns in partially braced multi-storey frames

  • Menon, Devdas
    • Structural Engineering and Mechanics
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    • 제11권3호
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    • pp.287-299
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    • 2001
  • Columns in multi-storey frames are presently categorised as either braced or unbraced, usually by means of the stability index criterion, for estimating their effective length ratios by design aids such as 'alignment charts'. This procedure, however, ignores the transition in buckling behaviour between the braced condition and the unbraced one. Hence, this results in either an overestimation or an underestimation of effective length estimates of columns in frames that are in fact 'partially braced'. It is shown in this paper that the transitional behaviour is gradual, and can be approximately modelled by means of a 'fuzzy logic' based technique. The proposed technique is simple and intuitively agreeable. It fills the existing gap between the braced and unbraced conditions in present codal provisions.