• 천문학회보
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• 제45권1호
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• pp.33.3-34
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• 2020

The Milky Way (MW) and other systems including M31 and Cen A have flattened structures of their satellites (Disk of Satellites, DoS). Such structures are rare in simulations under the ΛCDM paradigm. DoS is known to depend mainly on 1) the alignment of satellite orbits and 2) the degree of central concentration of satellites. In this work, we examine quantitatively how these two parameters affect the flatness of a system. We find that the MW-like DoS is rare in IllustrisTNG100 simulation because its two parameters are out of the 1-s range and furthermore the MW has a structure more flattened than the other systems having similar parameters. Besides, we propose a new criterion for the MW-like systems superseding the conventional ones such as major-minor axis ratio of the MW's DoS with a value of 0.183. Each satellite system has a specific orbital combination and thus has a particular distribution of its parameters (and thus flatness). The median of the distribution is set as the representative value of each system. And the representative value of the MW can be used as a new criterion for classifying the MW-like DoS. We reconstruct the orbital combination of the observed MW satellites using GAIA DR2 data and find the systems in the simulation that have representative values similar to the new criterion from the reconstructed MW system. This allows us a new interpretation on the rarity of MW-like DoS in cosmological simulations.

• 한국분무공학회지
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• 제20권2호
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• pp.76-81
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• 2015

Swirl flow has an impact on the stabilization of the flame by the recirculation flow, improvement of the combustion efficiency. The swirl flow in the gun type burner is created by the spinner which is inside the airtube that guide the combustion air. Burner has generally the combustion device composed electronic spark plug, injection nozzle, combustion device adaptor, and spinner. These inner components change the air flow behavior passing through airtube. So, this study analyzed exhaust flow characteristics of the gun type burner according to the ratio of airtube diameter. Turbulence characteristics by the spinner was mean velocity, turbulence intensity, kinetic energy, shear stress and flattness factor of the air flow of axial direction and tangential direction from the exit of the airtube.

• 한국지식정보기술학회논문지
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• 제12권4호
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• pp.539-550
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• 2017

본 논문에서는 UHF대역 원통형 다이폴 배열 안테나에 대해서 설계, 제작 및 시험을 하였다. 제안하는 안테나는 원통형 다이폴을 수직으로 4단 배열하였다. 원통형 다이폴 내부에는 병렬구조 급전회로를 설치하여 광대역 매칭이 되도록 구현하였다. 급전회로를 원통형 다이폴 중심에 설치하여 방위각 방향 무지향 방사패턴의 이득평탄도 특성을 최적화하였다. 급전회로에서 분기되는 신호의 차이를 최소화하여 대칭적인 방사패턴을 구현하였다. 요구 규격은 UHF대역에서 대역폭 11.2% 이상, 이득 6dBi 이상, 2:1 이하의 정재파비, 수평방향 방사패턴 이득평탄도 ${\pm}1dB$ 이내, 고각 방향 방사패턴 3dB 빔폭 13도 이상이다. M&S를 통해서 구현 가능성을 확인하고, 제작 및 시험을 통해서 M&S 결과를 검증하였다. 시험결과는 UHF대역에서 대역폭 11.2%, 이득 6.30~8.31dBi, 정재파비 1.53:1 이하, 방위각 방향 방사패턴 이득평탄도 ${\pm}0.2dB$ 이내, 고각 방향 방사패턴 3dB 빔폭은 15.62~15.84도이다. 시험결과 모든 규격을 충족하였다.

• 콘크리트학회논문집
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• 제12권3호
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• pp.3-10
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• 2000

In this study, we compared a plain mortar with the CAS-system shrinkage compensation mortar for Ondol that is Korean traditional heating system. The Ondol mortar is necessary to have properties as non-crack, fine flatness and stability for thermal changes. especially, mortar'crack prevention is to be most important property in Ondol mortar. To develope the stable material on the crack-prevention, we used to calcium-sulfo-aluminate(CSA)system in shrinkage compensation mortar. And so, we confirmed the effects of calcium-sulfo-aluminate(CSA) system for mortar's physical properties such as setting time, compressive strength and expansion ratio for crack prevention. The initial and final setting time of the CSA mortar is faster than plain mortar about 2hours. And, Compressive strength increased about 20% that plain mortar. The crack length per unit area, plain mortar is 0.426∼0.481m/m2. The Results of apartment construction field test, the shrinkage compensation mortar is excellent about the crack-reduce effect.

• 한국의류산업학회지
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• 제21권6호
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• pp.789-799
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• 2019

This study classified and analyzed the upper body types of 7-13 years old elementary school boys, using 3D data from the 6th Size Korea. The results of this study are as follows. Seven factors were extracted from the factorial analysis as an independent factor for a cluster analysis. The cluster analysis generated four body types. Type 1 has large ratio of front and back depth as well as circumference, with a front protrusion. In Type 2, the vertical value of upper torso is longer than average; in addition, its flatness is the largest and produces a thin body type. Type 3 has a smaller flatness in the bust, waist, abdomen and hip than other types, while also having the largest BMI. Type 4 is characterized by a greater shoulder angle than other types and its other factors are close to average. As a result of the logistic regression analysis, the prediction model used eight variables to generate and its accuracy is 88.679%. The classification of upper body types from this study can be used as basic data to improve patternmaking for each body type. The generated prediction model is also expected to be used as a method to help classify upper body types using the eight variables.

• 한국자기학회지
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• 제16권2호
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• pp.136-139
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• 2006

자기터널접합은 일반적으로 $250^{\circ}C$ 이상의 온도에서 터널자기저항비의 저하가 발생하는데 이는 반강자성체로 사용된 IrMn 중 Mn이 강자성체인 CoFe 및 터널배리어로의 내부확산에 기인한다. 자기터널접합의 열적 안정성을 향상시키기 위하여 나노산화층을 삽입하여 Mn의 확산을 제어하였다. CoNbZr 4/CoFe 10/IrMn 7.5/CoFe 3/터널배리어/CoFe 3/CoNbZr 2(nm)와 같은 자기터널접합을 기본구조로 하여 각각의 층에 나노산화층을 삽입하여 열적안정성 및 전자기적 특성을 비교 분석 하였다. 나노산화층의 삽입에 의해 터널자기저항비, 자기터널접합의 표면 평활도 및 열적안정성이 향상되었다.

• 대한기계학회논문집
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• 제12권5호
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• pp.952-958
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• 1988

본 연구에서는 폭방향 불균일 냉각에 따른 열응력이 판변형 및 잔류응력의 주 요원인이라는 고려하에 냉각중에 압연판의 온도분포 및 열응력을 예측할 수 있는 수치 해석 모델을 구성하였다. 온도와 응력 계산에 상변태 현상을 고려하였으며, 판변형 은 압축성분 열응력에 의한 좌굴현상으로 고려하여 해석하였다.

• 한국지형학회지
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• 제21권4호
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• pp.109-120
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• 2014

강의 상류부에서도 사력퇴가 잘 발달한 홍천강의 상류 유역 중 하나인 두촌천 유역을 대상으로 역과 모래를 분석하였다. 이를 통해 각 구간별 사력퇴의 발달 양상과 퇴적물의 차이를 비교해 보고 상류에서 하류로 이동되는 퇴적물의 변화양상을 살펴봄으로써 소유역 내에서도 다양하게 나타나는 하천의 지형발달 특색을 파악하고자 하였다. 역 분석 결과, 하류로 갈수록 화강암과 편마암 역이 공급되면서 원마도와 편평도가 증감을 반복하는 불규칙한 변화 경향을 보였다. 모래의 입도 변화는 전체적으로 중 조립사의 비율이 매우 높았으나, 화강암 지대를 흐르는 지류 합류점이 편마암 지대 합류점에 비해 다소 입경이 증가하는 경향을 보였다.

• 대한방사선치료학회지
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• 제5권1호
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• pp.115-119
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• 1992

The beam characteristics and dosimetric measurements of the 6MV X-ray and 6MeV electron beam from a ML-6M linear accelerator are examined. The Percent Depth Dose(PDD) table and the tissue Maximum Ratio(TMR) table are taken from measurement as a function of the field size and the depth. The calculated TMR table from PDD table is compared with those from measurement. Other beam characteristics such as output factor, beam profile(including flatness, symmetry and penumbra), wedge, and the variation of Dmax are presented. All of these dosimetric measurements sufficiently characterized the beam to permit safe clinical use.

• 한국인쇄학회지
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• 제21권2호
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• pp.67-74
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• 2003

Barrier ribs for PDP(plasma display panel) are commonly utilized to have uniform height and width and to prevent opical crosstalk between adjacent cells. The requirements for such barrier ribs are uniform height and shape, low outgassing rate and low porosity, high aspect ratio, and fine resolution. In this study, we are studied about that to make efficiency of material and high quality barrier ribs for PDP. As a result, could got high barrier ribs of $140{\mu}m$ evenly in 1th phenomenon using watersoluble UV curing resin and know that flatness of upper part is also very good.