• 한국항공우주학회지
• /
• 제43권4호
• /
• pp.341-348
• /
• 2015

본 논문에서는 일반적인 발사체의 형상에 대하여 몬테카를로 시뮬레이션을 적용하여 분리 유격 분석을 수행하였다. 단 분리는 매우 짧은 시간동안 이루어지며, 매우 많은 운동 변수가 관계되고 충돌 발생시 발사 실패가 나타나는 매우 중요한 비행 이벤트이다. 다양한 오차요인이 무작위(random)로 발생하는 경우에도 설정된 유격조건 내에서 분리가 됨을 확인하기 위해 일반적인 발사체 형상에 대한 단 분리 분석을 수행하였다. 몬테카를로 분석 기법을 발사체 단 분리 분석에 적용함으로서 단 분리 운동시 확률적인 결과들을 제시하였다.

• 한국초전도ㆍ저온공학회논문지
• /
• 제25권3호
• /
• pp.13-17
• /
• 2023

Magnetic separation technology for small paramagnetic particles has been desired for the volume reduction of contaminated soil from the Fukushima nuclear power plant accident and for the separation of scale and crud from nuclear power plants. However, the magnetic separation for paramagnetic particles requires a superconducting high gradient magnetic separation system applied, hence expanding the bore diameter of the magnets is necessary for mass processing and the initial and running costs would be enormous. The use of high magnetic fields makes safe onsite operation difficult, and there is an industrial need to increase the magnetic separation efficiency for paramagnetic particles in as low a magnetic field as possible. Therefore, we have been developing a magnetic separation system combined with a selection tube, which can separate small paramagnetic particles in a low magnetic field. In the previous technique we developed, a certain range of particle size was classified, and the classified particles were captured by magnetic separation. In this new approach, the fluid control method has been improved in order to the selectively classify particles of various diameters by using a multi-stage selection tube. The soil classification using a multi-stage selection tube was studied by calculation and experiment, and good results were obtained. In this paper, we report the effectiveness of the multi-stage selection tube was examined.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2004년도 추계 학술대회논문집
• /
• pp.145-150
• /
• 2004

In this study the numerical analysis on staging flow with forward ejector is conducted. The forward ejector plays a vital role in staging, which jets out from aftbody. This staging environment needs careful flow analysis for securing staging safety Present study investigates the steady inviscid staging flow phenomena with variation of separation distance. The performance index is forebody base pressure coefficients. The three dominant flow phenomena are observed according to separation distance which could be told as impinging stage, cavity vortex dominancy stage, and pure base flow characteristics stage. Impinging stage shows high thrust for forebody as one might think. However, important point is that cavity vortex dominancy stage can be more favorable for separation than impinging stage as one simply think in certain separation distance.

• 한국물환경학회지
• /
• 제20권4호
• /
• pp.307-312
• /
• 2004

This study was focused on experiment for the separation and concentration process of Cu(II), Zn(II) solution with the variation of applied pressure and concentration using reverse osmosis plate and frame modules. Rejection coefficient and degree of concentration for Cu(II) component using single and multi-stage reverse osmosis process were showed 96.3~97.8%, 0.044~0.191(in single-stage), 96.3~98.4%, 0.400~2.264(in multi-stage) within the range of experimental condition, respectively. Those of Zn(II) were 93.3~97.1%, 0.019~0.395(in single-stage), 96.3~98.2%, 0.365~1.454(in multi-stage), respectively. Degree of concentration of multi-stage were higher than those of single-stage. Heavy metal[Cu(II), Zn(II)] separation was very efficient in using reverse osmosis plate and frame type modules. Separation efficiency for a mixed solution Cu(II) and Zn(II) was higher than those of each one of Cu(II) and Zn(II).

• 멤브레인
• /
• 제21권2호
• /
• pp.177-192
• /
• 2011

바이오 가스의 분리와 정제를 위해 셀룰로오스 트리아세테이트(CTA) 고분자를 이용하여 중공사형 기체분리막을 상분리법에 의해 제조하고, 제조된 기체분리막을 사용하여 유효 막면적이 0.17 $m^2$인 중공사형 기체분리막 모듈을 제조하였다. 제조된 기체분리막 모듈의 순수 기체투과도틀 메탄, 산소, 이산화탄소에 대하여 측정하였다. 메탄의 투과도는 평균 0.46 GPU를 나타내었으며, 이산화탄소의 투과도는 평균 18.52 GPU였으며 이때 ${\alpha}CO_2$/$CH_4=40.4$를 나타내어 매우 높은 선택도를 나타내었다. 순수 가스 투과 테스트 후 혼합 가스에 대한 분리 정제 테스트를 4가지 모사가스에 대하여 진행하였으며 1 stage, 2 stage, 3 stage로 기체분리막 모듈을 구성하여 stage cut의 변화에 따른 각 부분에서 발생되는 기체의 농도 및 유량을 측정하였다. 1 stage에서는 stage cut이 상승함에 따라 메탄의 농도가 상승하는 것을 알 수 있었으며, 메탄 회수 효율은 떨어지는 것을 알 수 있었다. 2 stage 테스트에서는 1 stage와 유사한 거동을 보이는 것을 알 수 있었으며 메탄의 회수 효율은 1 stage보다 상승하는 것을 알 수 있었다. 바이오 가스 내에 존재하는 메탄의 손실을 줄이기 위해 3 stage 테스트를 진행하였으며, 그 결과 메탄가스의 손실율을 5% 이내로 줄일 수 있는 모듈의 배열을 찾아내었다.

• 자원리싸이클링
• /
• 제14권2호
• /
• pp.3-9
• /
• 2005

폐자동차 ASR으로부터 염소성분을 제거하기 위하여 풍력선별 및 비중선별 실험을 수행하였다. 또한, ASR플라스틱만을 분리하여 물을 매체로 한 비중선별을 실시하였다. ASR 시료는 모두 8 mm이하로 재분쇄하여 선별실험에 사용하였으며, 플라스틱은 3가지 입도로 나누어 비중선별 실험을 하였다. 풍력선별은 공기유량 9~20 M$^3$/hr 범위의 1단계와 공기유량 25~34 M$^3$/hr 범위의 2단계로 나누어 실시하고 각 산물의 비율과 재질분포를 조사하였다. 1단계 풍력선별후 underflow 산물의 비율은 62~66%인 것으로 나타났으며, 공기유량이 큰 2단계 풍력선별에서는 overflow 산물의 비율이 크게 증가하였다. 폐플라스틱만을 대상으로 한 비중선별 실험결과 부유물질이 침강물질에 비해 다소 많게 나타났으며, 염소함량에 있어서는 최대 수백개의 염소함량 차이를 보여 순수 플라스틱의 경우 매우 우수한 염소함유 재질의 분리효과를 얻을 수 있었다.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2002년도 춘계 학술대회논문집
• /
• pp.47-52
• /
• 2002

The supersonic flow around multi-stage rocket system is analyzed using 3-D compressible unsteady flow solver. A Chimera overset grid technique is used for the calculation of present configuration and grid around the core rocket is composed of 3 zones to represent fins in the core rocket. Flow solver is parallelized to reduce the computation time, and an efficient parallelization algorithm for Chimera grid technique is proposed. AUSMPW+ scheme is used for the spatial discretization and LU-SGS for the time integration. The flow field around multi-stage rocket was analyzed using this developed solver, and the results were compared with that of a sequential solver The speed-up ratio and the efficiency were measured in several processors. As a result, the computing speed with 12 processors was about 10 times faster than that of a sequential solver. Developed flow solver is used to predict the trajectory of booster in separation stage. From the analyses, booster collides against core rocket in free separation case. So, additional jettisoning forces and moments needed for a safe separation are examined.

• Journal of Korean Society for Atmospheric Environment
• /
• 제17권E1호
• /
• pp.9-16
• /
• 2001

To evaluate the correct separation capacity of cascade impactor for liquid aerosol, theoretical and experimental calculations of 50% cut-off diameter(ECOD(sub)50) were performed. A recalculation method of original diameter for hemispheric liquid aerosol collected on casecad impactor is also proposed newly using fixation technique. Calculated values for theoretical (ECOD(sub)50) of 40stage cascade impactor are 20, 6.4, 2.8, and 1.4$\mu\textrm{m}$ at 1st- ,2nd-, 3rd- and 4th-stage, respectively. A good agreement between the result of theoretical (ECOD(sub)50) and that og experimental ones was obtained at Stage 2 and 3. On the other hand, relatively large differences were found at Stage 1 and 4. Fixation for liquid aerosols using ${\alpha}$-cyanoacrylate monomer was performed successfully. The orignal diameter of liquid aerosols collected on each stage was calculated. The maximum levels of number size distribution curves at each stage are 19.8, 6.5, 3.1 and 1.5 $\mu\textrm{m}$ at 1st-, 2nd-, 3rd- and 4th-stage, respectively. The distortion of separation capacity of cascade impactor due to the split, merger, disappearance, and evaporation of liquid aerosols in the fluid did not occur.

• 가정과삶의질연구
• /
• 제25권1호
• /
• pp.183-207
• /
• 2007

The purpose of this study was to improve the understanding of the essential experience of Separated Families in South and North Korea in a socio-cultural context and to explore their post-separation adjustment process from the perspective of the families. Major findings in this study are summarized as follows. First, 'han' was the central phenomenon that the participants experienced following their separation. Second, the core issue in the process of post-separation adjustment was 'accepting the separation and rearrangement of reality for reunion', and over time the participants went through four stages in their adjustment process: the stage of being overwhelmed, the stage of conflict, the stage of awareness, and the stage of acceptance. Third, the main factors affecting the participants' adjustment were supportive systems, available resources(individual variables) and interaction with other separated families. fourth, four types were observed in the typology of adjustment and reunion of the participants.

• Journal of Biosystems Engineering
• /
• 제39권4호
• /
• pp.299-303
• /
• 2014

Purpose: This study set out to develop a machine for separating shatter-resistant sesame after threshing. Methods: Three grades of sieve and different blower speeds were tested for a separation system that had been designed specifically for shatter-resistant sesame. Performance tests were run to evaluate the sieve and blower systems in terms of the sesame separation and loss ratios. Results: Tests of the first separation stage using the sieve system revealed the optimum sieve perforation size to be 5 mm. Tests of the second separation stage using the blower system identified the optimum blower speed as being 220 rpm. The optimum separation and loss ratios, of 96.5% and 3.5%, respectively, were obtained at a blower speed of 220 rpm. Conclusions: These results will be useful for the design, construction, and operation of threshing harvesters. For shatter-resistant sesame, an optimum blower speed of 220 rpm was identified.