• 제목/요약/키워드: relative angle

검색결과 804건 처리시간 0.027초

SPECTROSCOPIC AND PHOTOMETRIC STUDY OF STARBURST GALAXIES: OPTICAL AND NEAR INFRARED PROPERTIES OF A BLUE COMPACT DWARF GALAXY MRK 49 IN THE VIRGO CLUSTER

  • Sung, Eon-Chang;Kyeong, Jae-Mann;Byun, Yong-Ik
    • 천문학회지
    • /
    • 제41권5호
    • /
    • pp.121-137
    • /
    • 2008
  • We present optical and near-infrared imaging and long-slit spectroscopy for the blue compact dwarf galaxy (BCD) Mrk 49 in the Virgo Cluster. The surface brightness distribution analysis shows that Mrk 49 consists of an off-centered blue bright compact core of r = 10" and a red faint outer exponential envelope. The $H_{\alpha}$ image and color difference suggest that these two components have different stellar populations: a high surface brightness population of massive young stars and an underlying low surface brightness population of older stars. The redder near-infrared colors of the inner most region suggest that the near-infrared flux of Mrk 49 originates from evolved massive stars associated with the current star-forming activity. The total apparent magnitude is $B_T\;=\;14.32$ mag and the mean effective surface brightness is ${\mu}_{eff}(B)\;=\;21.56$ mag $arcsec^{-2}$. Long-slit spectroscopy shows that Mrk 49 rotates apparently as a solid body within r = 10" in a plane at position angle 55 degrees with an amplitude of about $20\;km\;sec^{-1}$. The measured radial velocity of Mrk 49 was derived as $1,535\;km\;sec^{-1}$; and the total mass of stars and gases is in the range of 3 to $6\;{\times}\;10^9\;M_{\odot}$. The mass-to-light ratios for the central region of Mrk 49 in I and B band are estimated 1.0 and 0.5, respectively. The upper limit of the dark matter to visible matter ratio seems to be < 5. The oxygen abundance is $12\;+\;\log(O/H)\;=\;8.21\;{\pm}\; 0.1$ which is about one quarter of the solar value while the relative helium abundance appears to be similar to that of the sun.

대역 저지 슬롯이 추가된 역삼각형 모노폴 UWB 안테나의 설계 (A Design of Inverted-Triangle UWB Monopole Antenna with Band Rejection Slot)

  • 최형석;최경;황희용
    • 한국전자파학회논문지
    • /
    • 제22권5호
    • /
    • pp.516-521
    • /
    • 2011
  • 본 논문에서는 5 GHz WLAN 대역 저지를 위한 슬롯과 접지면에 굴곡이 있는 역삼각형 모노폴 UWB 안테나를 제안하였다. 제안된 안테나는 CPW 형태로 급전하였으며, 패치면과 접지면 사이에 3개의 각을 이용하여 모노폴 안테나의 대역폭을 확장시켜 3.1~10.6 GHz에서 약 -10 dB 이하의 반사 손실을 만족시켰다. 제작된 안테나는 비유전율 6.15, 두께 0.64 mm인 Taconic사의 RF-60A 기판을 사용하였으며, 안테나 패치의 크기는 36 mm${\times}$19.5 mm이다. 측정 결과, WLAN 대역을 제외한 UWB 시스템 전 대역에서 약 -10 dB 이하의 반사 손실과 전방향성에 근접한 복사 패턴의 특성을 나타내었다. 제안된 안테나는 접지면의 굴곡각을 이용하여 주파수 대역에 따라 임피던스를 조절하기 용이하다는 이점이 있으며, 비교적 간단한 형태의 슬롯을 삽입하여 대역 저지 특성을 나타낼 수 있다.

압밀응력비에 따른 낙동강모래의 비배수전단거통 특성 (Variation of Undrained Shear Behavior with Consolidation Stress Ratio of Nakdong River Sand)

  • 김영수;정성관;송준혁;정동길
    • 한국지반공학회논문집
    • /
    • 제19권4호
    • /
    • pp.83-93
    • /
    • 2003
  • 본 연구에서는 낙동강 하류 을숙도에 분포하는 0.558%의 세립분을 함유한 자연 사질토 지반에 대하여 느슨, 중간, 그리고 조밀한 지반 상태를 재현하여 초기정적전단응력의 영향을 정적 및 동적 시험을 통해 응력경로와 과잉간극수압 소산 및 잔류변형 거동을 규명하고, Bolton 이론에 의거한 파괴시 최대 유효마찰각을 상대밀도에 의한 영향과 구속압의 영향을 고려하여 제시하였다. 파괴선과 상전이점의 거리는 초기전단응력이 증가할수록 가까워지고, 느슨한 모래의 경우 그 영향이 커서 조밀한 모래의 응력경로로 접근하는 경향을 보인다. 압밀응력비 조건이 1.4에서 1.8로 변함에 따라, 상대밀도의 증가와 함께 보다 큰 액상화 저항강도를 보이고 조밀한 상대밀도 조건에서는 유사한 CSR값을 보였다.

모형실험에 의한 경사말뚝의 거동 특성 (Behavior Characteristics of Batter Piles by Model Test)

  • 권오균;이활;석정우
    • 한국지반공학회논문집
    • /
    • 제20권8호
    • /
    • pp.59-66
    • /
    • 2004
  • 본 연구에서는 연직말뚝과 경사말뚝에 대하여 모형실험과 수치해석을 실시하여 경사말뚝의 거동 특성을 분석하였다. 상대밀도 79%인 모래지반에 경사각도 0$^{\circ}$, $10^{\circ}$, 20$^{\circ}$, 30$^{\circ}$의 강관말뚝을 항타 관입하여 하중재하실험을 실시하였고, 상용 유한요소 프로그램인 PENTAGON 3D를 이용하여 수치해석을 수행하였다. 모형실험에 의한 경사말뚝의 축방향 지지 력은 경사각도가 $10^{\circ}$, 20$^{\circ}$, 30$^{\circ}$에서 연직말뚝에 비하여 111, 95, 81%로 나타났고, 수치해석의 결과도 다소 차이는 있지만 비슷하게 나타났다. 그러나 Petrasovits & Award의 결과는 경사각 $10^{\circ}$에서 모형실험 결과와 유사하지만, 경사각 20$^{\circ}$와 30$^{\circ}$에서는 모형실험결과를 과대평가하였다. 경사각도에 따른 주면마찰력과 선단하중은 모형실험과 수치해석 모두 $10^{\circ}$경사에서 최대값을 나타낸 후, 경사각도가 증가함에 따라 감소하였고, 전체하중에서 주면마찰력과 선단하중의 구성비율은 경사각도에 관계없이 거의 비슷하게 나타났다.

정역 회전법에 의한 고순도 알루미늄의 응고 및 정련에 관한 연구 (A Study on the Solidification and Purification of High Purity Aluminium Alternate Stirring Method)

  • 김욱;이종기;백홍구;허성강
    • 한국주조공학회지
    • /
    • 제12권3호
    • /
    • pp.220-229
    • /
    • 1992
  • The degree of purification and the macrostructure of high purity aluminium were studied through the alternate stirring method in order to improve the nonuniformity of solute concentration in the unidirectional stirring method. The $2^3$ factorial design was done to examine the effects of experimental factors more qualitatively. In the relatively low stirring speed of 1500 rpm with alternate stirring mode, the uniform solute profile and refined grain structure were obtained due to strong washing effect and turbulent fluid flow. It was induced by the transition of the momentum boundary layer by alternation of the stirrer. It was concluded from this study that the alternate stirring mode was more effective to obtain the uniformity of solute even in the stirring speed of 1500 rpm. But the degree of purification decreased below the critical alternating period. When 2N(99.8wt.%) aluminium was used as the starting material the morphology of solid-liquid showed the cellular shape and the columnar grains were inclined to the direction of rotation. This inclined grain growth resulted from the difference of relative velocities of solid and liquid. The inclined angle was increased as the stirring speed increased and solidification proceeded. In the case of 4N aluminium, there was no inclined grain growth and it was confirmed from the macrostructure and SEM work that the morphology of solid-liquid interface was planar. From the factorial design, it was found that the alternate stirring mode showed poorer purification effect than that of unidirectional stirring mode at low speed(500 rpm). In addition, the factor that had the most significant effect on the degree of purification was the stirring speed.

  • PDF

한국인 성인의 인두강에 관한 X선학적 연구 (A LATERAL CEPHALOMETRIC STUDY OF PHARYNGEAL CAVITY IN KOREAN ADULTS)

  • 이상래
    • 치과방사선
    • /
    • 제6권1호
    • /
    • pp.27-31
    • /
    • 1976
  • A study was performed to investigate the size of pharynegeal cavity and sexual differences between Korean adult male and female by introducing linear analysis of the lateral cephalogram. The radiograms were composed of 46 adult males aged 24.64 and 52 adult females aged 22.74 respectively. In order to study and measure the pharyngeal area the following skeletal landmarks were selected: S, N, A, Ptm, B, H, H', M, S' N, FH and CV, and the angle CV-FH was measured to provide a factor for correction of error resulting from improper head positioning of subjects, especially in the relative positions of A and H, while radiography. All points to be measured were projected at right angles to the Frankfort plane. For the purpose of measuring the anteroposterior dimensions of pharyngeal cavity the distances were measured in A-Ptm, A-S, S-Ptm and CV-H, and vertical measurements were made in SN-A, SN-PNS, SN-H' and M-H'. The obtained results were as follows: 1. The pharyngeal cavity is broader in the vertical than in the anteroposterior diameter in both sex and the maxium sexual differences were showed in the distances between SN and H', and minimal sexual differences in the distances between S and Ptm. 2. In general, the measurements of male were larger than those of female in the anteroposterior dimensions of pharyngeal cavity, but the distances bet-ween A and S, between CV and H showed significant sexual differences when evaluated statistically. 3. All of the measurements were larger in male than in female in vertical dimensions of pharyngeal cavity, and there were statistical significances of sexual differences in all variables.

  • PDF

Atomization Characteristics in Pneumatic Counterflowing Internal Mixing Nozzle

  • Lee, Sam-Goo;Rho, Byung-Joon
    • Journal of Mechanical Science and Technology
    • /
    • 제14권10호
    • /
    • pp.1131-1142
    • /
    • 2000
  • In an effort to illustrate the global variation of SMD (Sauter mean diameter, or $D_{32}$) and AMD (Arithmetic mean diameter, or $D_{10}$) at five axial downstream locations (i. e., at Z=30, 50, 80, 120, and 170 mm) under the different experimental conditions, the radial coordinate is normalized by the spray half-width. Experimental data to analyze the atomization characteristics concerning with an internal mixing type have been obtained using a PDPA(Phase Doppler Particle Analyzer). The air injection pressure was varied from 40 kPa to 120 kPa. In this study, counterflowing internal mixing nozzles manufactured at an angle of $15^{\circ}$with axi-symmetric tangential-drilled four holes have been considered. By comparing the results, it is clearly possible to discern the effects of increasing air pressure, suggesting that the disintegration process is enhanced and finer spray droplets can be obtained under higher air assist. The variations in $D_{32}$ are attributed to the characteristic feature of internal mixing nozzle in which the droplets are preferentially ejected downward with strong axial momentum, and dispersed with the larger droplets which are detected in the spray centerline at the near stations and smaller ones are generated due to further subsequent breakup by higher shear stresses at farther axial locations. The poor atomization around the centre close to the nozzle exit is attributed to the fact that the relatively lower rates of spherical particles are detected and these drops are not subject to instantaneous breakup in spite of the strong axial momentum. However, substantial increases in SMD from the central part toward the edge of the spray as they go farther downstream are mainly due to the fact that the relative velocity of droplet is too low to cause any subsequent disintegration.

  • PDF

Development of Awning System using Light Shelf - Focusing on the light environment and lighting energy reduction performance improvement -

  • Jeong, Jinsoo;Lee, Heangwoo;Seo, Janghoo;Kim, Yongseong
    • KIEAE Journal
    • /
    • 제17권3호
    • /
    • pp.5-13
    • /
    • 2017
  • Purpose: Various studies have been performed to address the issue of increased energy use by buildings. In particular, research on complex envelopes that combines diverse envelope element techniques is currently in progress in the building sector. The present study aimed to develop an awning system using a light shelf, and to verify its validity through performance evaluation. Method: In the present study, a testbed was established for the performance evaluation of the awning system using a light shelf, and the uniformity ratio and lighting energy consumption were compared and analyzed relative to those with no awning and light shelf installation (Case 1), awning installation (Case 2), and light shelf installation (Case 3). Result: 1) In the present study, an awning system using a light shelf (Case 4) where an opening is made on the awning screen and natural light can be introduced through the light shelf located at the bottom was developed. 2) The optimum standard for Case 4 obtained through the performance evaluation was a 0.6m lighting length and a 2m extension length at a light shelf angle of $30^{\circ}$. 3) Case 4 with the optimum standard had a 5.5% lower uniformity ratio than Case 2, but had a higher uniformity ratio than Case 1 and Case 3. 4) Case 4 with the optimum standard showed 13.3%, 44.6%, and 0%~8.7% lighting energy reductions compared to Case 1, Case 2, and Case 3, respectively. 5) Based on the above results, Case 4 suggested in the present study was found to be effective for indoor light environment improvement and lighting energy reduction.

통풍형 방음벽 개발 및 적용에 관한 연구 (A Study on the development and application of air-passing soundproofing wall)

  • 윤제원;김영찬;김금모;장강석;구본성;엄주용
    • 한국소음진동공학회:학술대회논문집
    • /
    • 한국소음진동공학회 2011년도 추계학술대회 논문집
    • /
    • pp.658-663
    • /
    • 2011
  • The purpose of this study is to develop an air-passing soundproofing panel with more improved structure to reduce the $CO_2$ emission and installation cost. To reduce the emission of $CO_2$ ; it is suggested to choose low $CO_2$ emission material relative to the aluminum and to reduce the materials by developing a specially designed air-passing soundproofing panel structure. First of all, we performed the flow analysis to predict the wind pressure according to the open angle of the air-passing soundproofing panel and the noise level analysis at the receiver point. To verify the simulation, a prototype of the soundproofing panel was made. The flow test in the wind tunnel and load test were performed. The economic evaluation for the installation of the air-passing soundproofing panel was performed and specifications of the installation was prepared. As the results of this research, it was verified that the wind load was reduced about 40% to that of the conventional one at 25m/s wind speed in the wind tunnel test. By applying the 4m span soundproofing wall with air-passing soundproofing panel and under the cost of 250 thousand $won/m^2$ instead of the conventional 2m span panel, the installation cost will always be lowered than the conventional one in the combination of (60:40~50:50) conventional to air-passing soundproofing panel from the economic evaluation. The 20% reduction of $CO_2$ was found by changing the 50% of aluminum soundproof panel to air-passing soundproofing panel.

  • PDF

THE STRUCTURE, STRATIGRAPHY AND PETROLEUM GEOLOGY OF THE MURZUK BASIN, SOUTHWEST LIBYA

  • JHO Jhoon Soo
    • 한국석유지질학회:학술대회논문집
    • /
    • 한국석유지질학회 2000년도 제7차 학술발표회 발표논문집
    • /
    • pp.57-72
    • /
    • 2000
  • The Murzuk Basin covers an area in excess of $350,000{\cal}km^2$, and is one of several intra-cratonic sag basins located on the Saharan Platform of North Africa. Compared with some of these basins, the Murzuk Basin has a relatively simple structure and stratigraphy, probably as a result of it's location on a the East Saharan Craton. The basin contains a sedimentary fill which reaches a thickness of about $4,000{\cal}m$ in the basin centre. This fill can be divided into a predominantly marine Paleozoic section, and a continental Mesozoic section. The principal hydrocarbon play consists of a glacial-marine sandstone reservoir of Cambro-Ordovician age, sourced and sealed by overlying Silurian shales. The present day borders of the basin are defined by tectonic uplifts, each of multi-phase generation, and the present day basin geometry bears little relation to the more extensive Early Palaeozoic sedimentary basin within which the reservoir and source rocks were deposited. The key to the understanding of the Cambro-Ordovician play is the relative timing of oil generation compared to the Cretaceous and Tertiary inversion tectonics which influenced source burial depth, reactivated faults and reorganised migration pathways. At the present day only a limited area of the basin centre remains within the oil generating window. Modelling of the timing and distribution of source rock maturity uses input data from AFTA and fluid inclusion studies to define palaeo temperatures, shale velocity work to estimate maximum burial depth and source rock geochemistry to define kinetics and pseudo-Ro. Migration pathways are investigated through structural analysis. The majority of the discovered fields and identified exploration prospects in the Murzuk Basin involve traps associated with high angle reverse faults. Extensional faulting occurred in the Cambro-Ordovician and this was followed by repeated compressional movements during Late Silurian, Late Carboniferous, Mid Cretaceous and Tertiary, each associated with regional uplift and erosion.

  • PDF