• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.317-322
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• 2004

In this paper, It was describe the processes of development of HiFi speaker system. Woofer and tweeter were fabricated by unskilled students and their 1.5 parameters were identified by known mass method. Based on T-S parameters port enclosure was designed and built by means of software. Acoustic radiation phenomena of port enclosure were simulated and compared to test result. Acoustic pressure difference between lower frequency and higher frequency was flattened by adopting optimal crossover network. Finally, built HiFi speaker system was showed good sound quality and sound pressure and electrical impedance was well agreed with test results each other.

• Journal of Astronomy and Space Sciences
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• 제40권4호
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• pp.247-258
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• 2023

Studying the accretion phenomena provides a window into understanding most heavenly bodies, from the birth of stars to active galactic nuclei (AGN). We would adopt the effect of the radiation pressure, which reduces accretion rates (Ṁ), on the accretion phenomena. The Shakura-Sunyaev α-disk model of disk accretion is a good candidate theory of advection dominated accretion flow (ADAF). Reduction in the angular velocity leads to the suppression the disk luminosity and surface temperature, essentially indicating the transition of the standard accretion disk model from convection dominated accretion flow (CDAF) to ADAF.

• 한국산림과학회지
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• 제87권4호
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• pp.601-610
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• 1998

본 연구는 시설에서 자란 콘테이너 묘목(苗木)의 경화과정(硬化過程)에 UV-B의 이용 가능성을 탐색하고자 생장상(生長箱)에서 4개월간 생육(生育)시킨 자작나무 묘목을 대상으로 UV-$B_{BE}$ $3.2KJ\;m^{-2}\;day^{-1}$과 $5.2KJ\;m^{-2}\;day^{-1}$ 수준의 UV-B 처리와 수분(水分)스트레스 처리(處理)를 4주간 실시하여 경화처리 전(前), 후(後)의 생장(生長) 및 생리적(生理的) 특성을 비교 분석하였다. UV-B 또는 수분스트레스 처리는 수고생장(樹高生長), 잎의 건물량축적(建物量蓄積)을 감소시켰다. UV-B 처리는 근원경생장(根元徑生長)을 감소시켰으나 수분스트레스 처리는 근원경생장을 증진시켰다. UV-B 처리 또는 수분스트레스 처리에 의한 잎의 건물량감소는 묘목의 T/R율을 감소시켰다. T/R율의 감소효과는 수분스트레스 처리에서 가장 크게 나타났다. 엽록소(葉緣素) 지수(指數)는 UV-B 5.2에서 가장 낮았으며 UV-B 3.2와 수분스트레스 처리에서는 비슷한 수준이었다. UV-B 또는 수분스트레스 처리는 콘테이너 묘목의 함수율(含水率)과 수분포텐셜을 낮추었으며 삼투압(滲透壓)을 높혔다. 경화처리에 의한 잎과 줄기의 함수율 감소는 UV-B 처리에 의해서는 빠르게 일어났으나 수분스트레스 처리에 의해서는 보다 서서히 일어났다. 이상의 결과를 보면, 자작나무 콘테이너 묘목의 경화단계에 처리된 UV-B에 의한 생장반응(生長反應) 및 수분생리(水分生理) 변화는 수분스트레스 처리에서의 효과와 유사한 면이 관찰되었다.

• Journal of Mechanical Science and Technology
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• 제15권8호
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• pp.1181-1187
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• 2001

The radiation driven response function (R$\_$q/) for AP and HMX propellant was obtained and compared with experimental results by using a simple $\alpha$$\beta$γ flame model rather than with detailed chemistry. For an AP propellant, the profile of heat release was assumed by the experimental data. The calculated R$\_$q/ shows a frequency shift of the peak amplitude to the higher frequency and a decrease in the maximum amplitude as radiation increases. In addition, it was found the increase in the total flux could enhance the mean burning rate γ$\_$b/ while the phase differences between the radiation and resulting conduction could consequently reduce the fluctuating amplitude Δγ$\_$b/. Fortunately, this is the qualitative duplication of the behavior recently observed in the experiments of RDX propellants. For HMX, the response function R$\_$q/ has been calculated and showed a quite good agreement with the experimental data. Even though the fairly good agreement of R$\_$q/ with experimental ones, the unsteady behavior of HMX was not reproduced as the radiation input increased. This is due to lack of the material properties of HMX or the physical understanding of HMX burning at high pressure.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.938-941
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• 2004

Sound generation and radiation from the duct-rotor system are calculated numerically. The wake geometries of a two-bladed rotor are calculated by using a time-marching fiee-wake method without a non-physical model of the far wake. Acoustic free field due to a rotating rotor is obtained by Lowson's equation. Using Kirchhoff source, rotating sources are modeled as stationary ones and can be inserted in the thin body boundary element method. The Kirchhoff source is validated through calculation of acoustic pressure due to a rotating point force. The thin body boundary element method (thin body BEM) is validated through calculation of acoustic radiation of ducted dipole. Using Kirchhoff source and thin body BEM, acoustic radiation of a ducted rotating source is calculated. Acoustic shielding is observed by inserting a duct and shows different phenomena at each major frequency. Acoustic radiation of a real duct-rotor system is also calculated using this method and the ducted acoustic field is significantly different from rotor only.

• 천문학회보
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• 제32권2호
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• pp.49.1-49.1
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• 2007

• Nuclear Engineering and Technology
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• 제20권3호
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• pp.203-213
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• 1988

• 한국광학회:학술대회논문집
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• 한국광학회 1990년도 광학 및 양자전자학 워크샵
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• pp.106-115
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• 1990

레이저 광압력을 써서 나트륨 원자선다발을 감속시키고, 냉각시키며, 허공에 붙잡아두는 일과 관련된 이론과 실험에 관해 설명하였다.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2003년도 추계학술발표대회 요약집
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• pp.367.2-367.2
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• 2003

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2003년도 추계학술발표대회 요약집
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• pp.446.2-446.2
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• 2003