• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2008년도 춘계학술대회논문집
• /
• pp.522-525
• /
• 2008

A vacuum cleaner is the widely used home equipment. However, it has a trouble with too much power consumption. Most losses occur at the centrifugal fan. To remedy this trouble the investigation of motor, which is the main component of vacuum cleaner, is required. The flow characteristics around the high-speed rotating centrifugal fan which is influenced by the very low inlet pressure is quite different from a commonly used fan. Hence it is quite difficult to analyze the flow by the experimental means or by the numerical simulation. In this research, it is aimed to improve the air-suction performance of a vacuum cleaner through the flow analysis around a motor. The efficiency of the centrifugal fan is affected by blade shape, blade number, blade pitch, etc. The influence of the shape of impeller on the flow is investigated in this study. The flow around the centrifugal fan is simulated by applying the moving mesh. To verify the validity of the computation results, the air flow rate and the pressure field to the cleaner is compared with the experimental data. All simulations are performed by using commercial code SC/Tetra. The calculated results show good agreement with the experimental ones and it is believed to be promising to use computational simulation in the improvement of the vacuum cleaner performance.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
• /
• pp.151.2-151.2
• /
• 2014

Broadband impedances for the 3-GeV pohang light source-II (PLS-II) storage ring have been numerically estimated using a full three dimensional finite-difference time-domain code, CST particle studio. The total broadband impedance of all the vacuum components was estimated as 0.256 ohm, which is a small fraction of the total machine impedance budget.

• 센서학회지
• /
• 제26권5호
• /
• pp.360-365
• /
• 2017

In this study, a heat treatment process was applied to ZnS nano-powder to improve the optical properties of ZnS ceramic, and the characteristics of heat treatment time were studied. The ZnS nano-powders were synthesized by hydrothermal synthesis. The heat treatment was carried out at $550^{\circ}C$ for 0.5, 1, 2, and 4 hours in a vacuum atmosphere ($10^{-2}torr$). X-ray diffraction and scanning electron microscope analyzes confirmed the change of crystal phase and grain size to confirm the structural change with heat treatment time. The heat treated ZnS nano-powder was sintered by hot pressing, and the change of optical properties of the ZnS ceramic was analyzed by infrared spectroscopy.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
• /
• pp.246.2-246.2
• /
• 2014

Green-light emitting OLED with single layer of Alq3 and orange-light emitting OLED with double layer of rubrene/Alq3 as EML were fabricated and characterized comparatively. The two OLED devices were based on an anode of ITO, HTL of TPD, and cathode of Al, respectively. The green light emitting OLED was then prepared with Alq3 as both ETL and EML, while the orange-light emitting OLED was prepared with rubrene deposited on Alq3. All the component layers of the OLED devices were deposited by a thermal evaporation technique in vacuum. Photoluminescence characteristics of the EML layers were investigated. Electrolumiscence characteristics of the OLED devices were comparatively investigated.

• 한국재료학회지
• /
• 제16권8호
• /
• pp.485-489
• /
• 2006

The preparation conditions of $YBO_3$:Eu phosphor particles having the maximum photoluminescence intensity under vacuum ultraviolet in the spray pyrolysis were optimized. The $YBO_3$:Eu phosphor particles prepared from spray solution with stoichiometric amount of boric acid had the maximum photoluminescence intensity. The $YBO_3$:Eu phosphor particles with pure phases were formed at low post-treatment temperatures because of fast reaction of yttrium and boron components without volatilization of boron component. The prepared $YBO_3$:Eu phosphor particles by spray pyrolysis had fine size, narrow size distribution and regular morphology. The photoluminescence intensity of the prepared $YBO_3$:Eu phosphor particles under vacuum ultraviolet was 103% of the commercial $(Y,Gd)BO_3$:Eu phosphor particles.

• 한국광학회지
• /
• 제15권4호
• /
• pp.325-330
• /
• 2004

진공자외선 파장영역에서 광학부품의 분광특성을 측정할 수 있는 중수소광원과 진공단색화장치, 시료챔버 및 광 검출기 구조의 진공자외선 분광반사율계를 제작하였다. 제작된 진공자외선 분광반사율계는 115nm∼330 nm의 분광영역에서 약 3.0${\times}$$10^{-4}$ Pa의 기압에서 작동하였다. 253.652 nm와 184.95 nm의 수은 선스펙트럼으로 진공단색화장치의 파장을 교정하여 그 분해능이 0.012 nm이고, 파장정확도가 $\pm$0.03 nm 임을 확인하였다. 중수소 광원을 이용하여 115 nm∼230 nm 파장대역의 진공자외선 영역에서 여러 가지 광학부품들에 이용되고 있는 재료(MgF$_2$, CaF$_2$, BaF$_2$, SiO$_2$, Sapphire)들의 분광투과율과 반사율을 측정하였다.

• 한국항공우주학회지
• /
• 제43권11호
• /
• pp.1008-1015
• /
• 2015

위성체의 지상 검증 시험에는 열진공 챔버가 사용되며, 열제어 시스템은 열진공 챔버의 핵심이라고 할 수 있다. 특히, 기체 질소를 이용한 폐회로 열제어 시스템의 성능은 극저온 블로워의 성능에 의해 결정된다. 본 연구의 최종 목표는 설계 요구조건 $-150^{\circ}C{\sim}150^{\circ}C$의 온도 조건, 유량 150 CFM, 0.5 bara 이상의 차압을 갖는 극저온 블로워를 개발하는 것으로, 1차원 해석툴 및 CFD를 이용한 성능해석을 통해 임펠러를 설계 하였으며, 구동부와 유체부의 열전달 방지를 위한 열장벽, 모터의 과열 방지를 위한 냉각 시스템 등이 설계되었다. 표준대기상태에서 실험을 통해 성능을 검증하였으며, 최종적으로 열진공 챔버내에 설치하여 운영 조건에서 극저온 블로워의 성능을 확인하였다.

• 한국균학회지
• /
• 제11권4호
• /
• pp.147-150
• /
• 1983

To investigate a possibility of producing the antitumor component by shake culture method, the mycelia of Flammulina velutipes were cultured in flasks on a shaker at $26{\sim}28^{\circ}C$ at 180 rpm for seven days. The extract of the mycelia was concentrated under vacuum. The precipitate obtained by adding a three-fold volume of ethanol was centrifugated and freeze-dried after dialysis. The fraction was tested against sarcoma 180 in the mice. The inhibition ratio of the fraction against the tumor was 68.0% at the dose of 20 mg/kg/day for the period of ten days and the tumors in three of the mice were completely regressed. The results showed, therefore, that the antitumor component was produced by the shake culture method.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
• /
• pp.232-232
• /
• 2012

The doping of semiconducting elements is essential for the development of silicon quantum dot (QD) solar cells. Especially the doping elements should be activated by substitution at the crystalline sites in the crystalline silicon QDs. However, no analysis technique has been developed for the analysis of the activated dopants in silicon QDs in $SiO_2$ matrix. Secondary ion mass spectrometry (SIMS) is a powerful technique for the in-depth analysis of solid materials and the impurities analysis of boron and phosphorus in semiconductor materials. For the study of diffusion behaviour of B and P by SIMS, Si/$SiO_2$ multilayer films doped by B or P were fabricated and annealed at high temperatures for the activated doping of B and P. The distributions of doping elements were analyzed by SIMS. Boron found to be preferentially distributed in Si layer rather than the $SiO_2$ layer. Especially the B in the Si layers was separated to two components of an interfacial component and a central one. The central component was understood as the activated elements. On the other hand, phosphorus did not show any preferred diffusion.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
• /
• pp.415.2-415.2
• /
• 2014

Cost-effective, robust devices for solid-state lighting industry that converts electricity to light revolutionize the current lighting industry. Phosphor materials used in these devices should be synthesized in a low-cost and effective method for use in WLEDs. In this presentation, the synthesis of Eu3+ ions doped BaMoO4 phosphor samples by a facile synthesis process for red component of WLEDs will be shown. The tetragonal phase of the host lattice was substantiated by the X-ray diffraction patterns. The morphological studies were carried out by using a field-emission scanning electron microscope and transmission electron microscope. These confirmed the formation of a shuttle like particles with perpendicular protrusions in the middle of the particle. The photoluminescence (PL) properties exhibited good emission with a high asymmetry ratio when excited with ultraviolet B wavelengths (~ 280-315 nm). The cathodoluminescence (CL) spectra showed similar results to the PL spectra, indicating the rich red emission. The results suggest that this phosphor is a good material as red region component in the development of tri-band UV excitation based WLEDs.