• 제어로봇시스템학회논문지
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• 제6권6호
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• pp.447-453
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• 2000

Using the scattering theory of laser light, we analyze the particle sizing method. The scattered profile measured by the photodetector is sampled, scale conditioned by a 32 channel analog-to-digital converter, and is analyzed with the transform matrix from the light energy signals to the weights of the particle sizes. The particle size distribution is classified using the Hopfield neural network method as well as the conventional nonnegative least square method.

• 한국입자에어로졸학회지
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• 제13권3호
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• pp.133-139
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• 2017

In this paper, we proposed an emulsification method without using an emulsifier and investigated the effects of particle size distribution in fluids on dispersion stability. Surfactant-free oil in water emulsion was prepared with 1 % (w/w) of olive oil by using high speed agitation, high pressure and ultrasonic dispersion methods. The particle size, microscopic observation, and dispersion stability of each sample were evaluated and dispersion stability according to various dispersion methods was compared. As a result, the emulsion dispersed by the ultrasonic dispersion method showed the smallest particle size and uniform distribution of $0.07{\sim} 0.3{\mu}m$ and was the most stable in a 7 days stability evaluation. In the above experiment, four olive oil emulsions having different particle sizes were prepared using ultrasonic dispersion technology that was capable of producing stable emulsions. The dispersion stability of each samples with oil droplet sizes of (A) 0.1 to $0.5{\mu}m$, (B) 0.3 to $4{\mu}m$, (C) 1 to $10.5{\mu}m$ and (D) 2 to $120{\mu}m$, was observed for 7 days, and the relationship between the stability and performance was studied. Emulsion (A) with particle size less than $0.5{\mu}m$ displayed the dispersion stability showing below 5 % change in a 7 days stability evaluation. In the case of (B), (C), and (D) that had larger particle than $0.5{\mu}m$, the changes of dispersion stability were 10 %, 13 % and 35 % respectively. From these results, it was proved that dispersion stability of emulsion with uniform particle size of $0.5{\mu}m$ or less was confirmed to be very stable.

• 한국환경보건학회:학술대회논문집
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• 한국환경보건학회 2005년도 국제학술대회
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• pp.381-385
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• 2005

Characterization of particle behavior is becoming more important in performance evaluation of water treatment system as well as in operation of the system because conventional parameter, turbidity has lack of explaining ability on small sized microorganisms such like Cryptosporidium etc. Accordingly, particle counter has been introduced in evaluation and operation of the treatment system. However researches on the relationship between turbidity, particle count and/or different sand/anthracite sizes have not been concurrent. Therefore in this study, the relationship was investigated to improve performance evaluation of sand filter so as to help choosing sand/anthracite effective size as a design parameter of water treatment facility. According to the results, too small or too large effective size media filter reached to turbidity limit(0.1 NTU)earlier. However, because shallow sand layer may cause early breakthrough, the depth of sand layer should be provided enough in order to compromise water quality and productivity.

• Journal of Mechanical Science and Technology
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• 제20권11호
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• pp.1972-1979
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• 2006

This study was conducted in order to generate model particles which were similar to particles in diesel emission. Spark discharge was used for carbon agglomerates and hydrocarbon condensation for particles that consist of carbon agglomerates and hydrocarbon. The size of the carbon agglomerates, whose mean size were 30 and 70 nm, ranged between 15 and 200 nm, and the total number concentration of the particles ranged from 3 to $5{\times}10^7#/cm^3$ as the controllable variables in spark discharge generator changed. The result of the hydrocarbon condensation experiment showed that the final sizes of the particles enlarged by condensation did not depend on the initial sizes, but the maximum condensational growth of carbon agglomerates by dodecane ($C_{12}H_{26}$) condensation was 112 times the initial size of 40 nm, while the size of the agglomerates by benzene ($C_6H_6$) was 3.25 times its initial size.

• 한국염색가공학회지
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• 제21권1호
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• pp.30-37
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• 2009

Studies on plants such as lotus leaf suggested that dual-scale structure could contribute to super-hydrophobicity. We introduced super-hydrophobicity onto poly(ethylene terephthalate)(PET) fabric with dual-scale structure by assembling $TiO_2$ nano sol. PET fabric was treated with $TiO_2$ sol, water-repellent agent using various parameters such as particle size, concentration. Morphological changes by particle size were observed using field emmission scanning electron microscopy(FE-SEM) and AFM measurement, contact angle measurement equipment. The contact angle of water was about 138.5$^{\circ}$, 125.8$^{\circ}$, 125.5$^{\circ}$ and 108.9$^{\circ}$ for PET fabric coated with 60.2nm, 120.1nm, 200nm and 410.5nm $TiO_2$ particles, compared with about 111.5$^{\circ}$ for PET fabric coated with water repellent. When we mixed particle sizes of 60.2nm and 120.1nm by 7:3 volume ratio, the contact angle of water was about 132.5$^{\circ}$. And we mixed particle sizes of 60.2nm and 200nm by 7:3 volume ratio, the contact angle of water was about 141.8$^{\circ}$. Also we mixed particle sizes of 60.2nm and 410.5nm by 7:3 volume ratio, the best super-hydrophobicity was obtained. In this paper, we fabricated various surface structures to the water-repellent surfaces by using four types of $TiO_2$ nano-particles, and we found that the nanoscale structure was very important for the super-hydrophobicity.

• 공업화학
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• 제25권6호
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• pp.564-569
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• 2014

지르코니아 나노분말을 수열합성법으로 제조하였으며, 반응온도, 반응시간, 침전제의 종류 및 농도, 전구체의 종류를 실험 변수로 하였고, 각각의 제조된 분말을 X-선 회절(XRD)과 주사전자현미경(FE-SEM)을 통해 입자크기 및 결정상을 측정하였다. 침전제의 농도 증가에 따라 지르코니아 입자크기가 증가하였으며, 입자의 결정화도도 높아졌고, KOH 보다 NaOH 침전제를 사용하였을 경우, 입자 성장 속도가 증가하였다. 이는 입자의 크기 컨트롤에 있어 NaOH를 사용하는 경우보다 KOH를 사용하는 것이 더 효과적이었다. 4 h의 수열반응시간에서는 4 h의 수열반응시간에서는 비정질의 지르코니아 입자가 발견되었지만, 8 h 이상 합성 시, 단사정상의 지르코니아 입자가 생성됨을 확인하였고, 반응시간이 길어짐에 따라 지르코니아 입자의 폭이 소폭으로 줄어들고, 길이는 소폭 늘어남을 확인하였다. 동일한 합성 조건에서 전구체로서 zirconium (IV) acetate, zirconium nitrate, zirconium chloride 중에서 zirconium chloride를 사용하여 합성하였을 경우, 입자의 크기가 가장 작게 형성되었다.

• Korean Chemical Engineering Research
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• 제60권4호
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• pp.613-619
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• 2022

전도성 입자로 제조된 전기유변(Electrorheological) 유체에서 입자 크기 및 서로 다른 크기의 입자들의 혼합이 전기유변 현상에 어떤 영향을 미치는지 살펴보기 위해 Onsager 이론으로 확장된 Maxwell-Wagner 분극 모델을 이용하여 전산 모사를 수행하였다. 전산 모사 결과 입자의 부피 분율이 같은 경우 단일한 크기의 입자로 구성된 균일한 전기유변 유체의 동적 항복응력은 입자 크기에 무관하였고, 크기가 서로 다른 입자들로 혼합된 비균일 전기유변 유체의 동적 항복응력은 균일한 전기유변 유체에 비해 감소하였다. 입자 부피 분율이 같은 경우 ${\dot{\gamma}}^*$≧0.01인 범위에서 큰 입자로 구성된 균일한 전기유변 유체가 작은 입자로 구성된 균일한 전기유변 유체보다 전단응력이 큰 것으로 나타났으며, ${\dot{\gamma}}^*$≧1인 경우에는 전기유변 유체는 큰 입자의 비율이 증가할수록 전단응력이 증가함을 보였다. 모든 입자 크기 및 조성에 대해 전도성 입자로 제조된 전기유변 유체의 특성인 비제곱 전기유변 현상(∆_𝛕 ∝ Eⁿ, n ≈ 1.55)도 예측하였다.

• 한국농공학회지
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• 제17권3호
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• pp.3833-3839
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• 1975

The object of this experiment is to find out some flow characteristics of water through sand layer, to prevent moving sands in the filters of the fill Dam, infiltration gallery, well and Deversion Weir. This experiment was accomplished with different particle Sizes of Six Samples and different hydraulic gradient. The results obtained are Summarized as follows. 1. The critical hydraulic gradients for laminar flow was found to be between 1 and 2 when the sand used had the effective diameter, D10 of between 0.18cm and 0.45cm. 2. The critical hydraulic gradients for different particle sizes of sands were varied considerably. 3. There was a negative correlation between critical hydraulic gradient and critical Velocity, and between effective particle diameter D10 and critical hydraulic gradient respectively. 4. In spite of relatively small variation of void ratio of sands used, the values of the coefficient of permeability varied considerably. There was a negative correlation between coefficient of permeability and void ratio.

• 한국자기공명학회논문지
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• 제6권1호
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• pp.38-44
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• 2002

60% Pt on Vulcan XC-72 with similar Pt sizes to fuel cell grade Pt black was investigated by $\^$13/C nuclear magnetic resonance spectroscopy (NMR), cyclic voltammery (CV), transmission electron microscopy (TEM). Experiments were carried out on electrochemically cleaned samples as well as as-received. The TEM and CV results showed that the average particle sizes were changed by cleaning. However, the chemical shift （$\delta$$\_$G/） of $\^$13/C of $\^$13/CO absorbed on Pt surfaces did not show any appreciable variation with particle size change as did in Pt black. These results indicate that a combination of different analytic techniques is essential to understand the properties of the metal particle catalysts and that the presence of carbon black support strongly influences the NMR data, probably through metal-support interaction.

• 한국식품조리과학회지
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• 제14권5호
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• pp.584-588
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• 1998

Red pepper powders with variuos seed contents (0%, 10%, 20%) and particle sizes were stored at 0$^{\circ}C$, 20$^{\circ}C$, and 30$^{\circ}C$ for 90 days, and the changes in their characteristics were monitored. The initial moisture content was about 13%, and the powders were packed in 0.1 mm-thick polypropylene (PP) bags. Moisture content of each power remained constantly, so PP bags appeared to be effective to prevent moisture transmission. All the values of L＊, a＊ and b＊ were higher in fine particles than in coarse particles. Storage at 0$^{\circ}C$ did not change any color values, however, overall color values devreased apparently when stored at 30$^{\circ}C$ for 90 days. Capsanthin contents decreased gradually at all storage temperatures and more rapidly at higher temperature. The contents of capsaicinoids in fine particles (49∼59 mg%) were twic as much as those in coarse particles (15∼36 mg%), and they did not change throughout the storage.