• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.3
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• pp.370-374
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• 2003

Cell cracking method using a non-collision was evaluated for the possibility of new red ginseng grinding technique. Based on particle size distribution analysis by 1size shaker, the ratios of 100 mesh penetrated particles were 94.9% for hammer mill (group A) and 95.6% for cell crack (group B). The ratio of 120 mesh penetrated particle of group A was higher than that in group B. The particle size distributions for 100 mesh non-penetrated Powder between 2 groups were not significantly different, and particle size distribution analysis by laser scattering analyzer showed that the particle size ranges were 0.77~128.07 ${\mu}{\textrm}{m}$ for group A and 4.24~180.07 ${\mu}{\textrm}{m}$ for group B. The Particle size distribution in group A was more broad than that in group B. The mean particle size in group B was larger than that in group A, while the standard deviation of particle size distribution in group B was less than that in group A. Structural surface characteristics, in group A, particle size distribution was broad and the distribution curve was amorphous. The structure of individual particles was similar to unequal stone which was roughly grinded and had soft cotton-like surface. In the contrary, in group B, particle size distribution was relatively narrow and also individual size particles were ubiquitously distributed. The structure of individual particles was unequal cut stone shape.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.3
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• pp.25-31
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• 2019

This study was conducted to evaluate the penetration performance of the Silane Surface Protection Material (SSPM) penetrating the micro pore of concrete surface. The results was indicated microstructure, porosity and penetration depth of applied SSPM. Silica sand and conventional sand were used as fine aggregate in mortar. And liquid and cream types SSPM were used. The amounts of SPM were applied the 127, 255, 382, 510 g/m2 on the surface of mortar. The penetration depth specimens were made with $100{\times}30mm$ in according with KS F 4930. Penetration depth was evaluated according to KS F 4930, divide specimen and then spraying with water in cross section of specimens, and measure the depth of the non-wetted area. The microstructure result of mortar applied SSPM, it was obtained liquid and cream SSPM in mortar. The porosity results of SSPM application specimens were improved with than that of plain specimens. Test results indicated that the penetration depth of SPM were improved with increasing in amounts of SSPM. As a result of test, application of SSPM to concrete surface, it will improve durability.

• Journal of the Korean Ceramic Society
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• v.35 no.10
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• pp.1055-1060
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• 1998

The effects of particle size distribution have been investigated on the high frequency low loss Mn-Zn fer-rites. The particle size distribution was controlled by milling time. Zirconia ball and engineering plastic jar were employed to avoid iron contamination from the milling media. As increasing the milling time BET value was increased from 0.55 to 3.21m2/g and mean particle size was decreased from 2.1 $\mu\textrm{m}$ to 1.0$\mu\textrm{m}$ The large specific surface area of initial powder resulted in the high density of sintered core. However starting powders with high BET lead to inhomogeneous grain growth as well as poor electromagnetic pro-perties at sintering temperature above 1300$^{\circ}C$.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.41 no.1
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• pp.46-53
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• 2005

This paper describes the mean grain size and shear strength properties related to subsidence characteristics using sediment samples and acoustic images obtained from artificial reef areas in Tongyoung and Jangsungpo offshore. The acoustic images collected from chirp sonar and side scan sonar show well the attitude/orientation, the distribution pattern, and the degree of subsidence of artificial reefs, suggesting the possibility of suitable site investigation and the management of the reefs using acoustic sonar. The sediments were largely composed of clayey silt and silty clay. The mean grain sizes in Tongyoung and Jangsungpo offshore show the ranges of 5${\sim}$9${\Phi}$ and 8${\sim}$9${\Phi}$, respectively. The shear strength was significantly increased at the depths of 20cm in Tongyoung offshore and 80cm in Jangsungpo offshore, corresponding to the subsidence depth of artificial reefs. The relationship between mean grain size and shear strength did not show a correlation, suggesting the shear strength does not totally depend on mean grain size. Provided subsidence characteristics with respect to various artificial reefs and seabed condition are investigated in more details, the constructing area of the reef can be more extended.

• The Korean Journal of Quaternary Research
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• v.10 no.1
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• pp.27-52
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• 1996

금강 퇴적물의 지화학적 특성을 파악하기 위하여 상류에서 하류까지 21개의 표층 퇴적물을 채취하고 총금속(Al, Fe, Mn, Cr, Co, Ni, Cu, Zn, Pb) 입도별 금속 및 존재형태별 금속을 분석하였다. 또한 하천에서 연안역까지 미량금속의 공간적 변화를 보기 위해 부유물 을 일정 간격으로 채취하여 미량금속을 분석하였다. 퇴적물 중 미량 금속 함량을 평균 입도 와 밀접히 관계하여 변화하며 세립질실트 이하 부분에서 가장높은 함량을 보였고 이 높은 함량은 하천 부유물 중 금속 함량과 Mn을 제외하고 거의 유사한 수준이었다. Pb은 조립질 모래에서도 높은 함량을 보이는데 이는 조립질 모래에 많이 포함된 정장석에 의한 영향이 되고 세립질 실트에서의 높은 금속 함량은 세립한 중광물에 의한 영향이다. Mn과 Pb을 제 안한 금속들은 퇴적물 중 주로(70% 이상) 결정 격자와 관계하여 존재하는데 이는 퇴적물의 주구성 입도가 조립하여 금속이 풍부하고 세립한 중광 물에 의한 영향이 크기 때문이다. 하 천에서 염하구로 금속 함량이 급격히 감소하는데 이는 용존 $Mn^{+2}$이온이 $MnO_2$로 변화하는 산화반응과 하천구역에서의 퇴적 그리고 염하구에서 금속이 적어 진 입자(염하구 내에서 유기물 분해/용해로 만들어지거나 재부유 작요에 의한 조립질 물질) 와 하천 부유물과의 혼합작용에 의해 이루어진다.

• Polymer(Korea)
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• v.28 no.1
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• pp.10-17
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• 2004

Poly(vinyl acetate) (PVAc) nanoparticles were synthesized in oil/water miniemulsion polymerization in the presence of low amount of hexadecane as a cosurfactant. The nanoparticles were tested to apply as a drug carrier. The shape of nanoparticles was observed by scanning electron microscopy, and the average particle size and size distribution were examined by particle size analyzer. Inclusion of antibiotic drugs into the nanoparticles was confirmed by CHO, C=O, and OH peak of FT-IR. Size of the nanoparticles were adjusted between 80∼300 nm by changing the homogenization rate and amount of cosurfactant and surfactant. The monomer droplets prepared by miniemulsion method using a cosurfactant were homogeneous and stable compared with those prepared by conventional emulsion polymerization. This might be occurred due to the prevention of Ostwald ripening and coalescence between droplets by using hexadecane as a cosurfactant.

• Journal of the Korean Ceramic Society
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• v.41 no.9
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• pp.670-676
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• 2004

The synthesis of highly concentrated silver nano sol assisted by polymeric dispersant (polyelectrolytes) for inkjet method was studied. The silver nano sol was prepared with AgNO$_3$, polyelectrolytes (HS5468cf ; polyacrylic ammonium salt), and reducing agent. The polyelectrolytes play an important role in formation of complex composed of Ag$\^$+/ion and carboxyl group (COO$\^$-/), result in preparation of highly dispersed silver nano particles. The optimization of added amount of polyelectrolytes, and concentration of silver nano sol was studied. The silver nanoparticles were evaluated by XRD, particle size/zeta potential analyzer and FE-TEM. The silver nanoparticles with the range of 10 nm in diameter were produced. The concentration of batch-synthesized silver nano sol was possible up to 40 wt%.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2012.03a
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• pp.109-109
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• 2012

아라미드 섬유는 태양광의 직사광선에 계속 노출될 경우 120주 경과 후에는 강도가 3분의 1로 떨어지는 단점이 있다. 이와 같은 단점을 보완하기 위해 나노 크기의 금속산화물인 $TiO_2$ 졸-겔 나노합성법을 이용하여 나노졸을 제조하고 이를 직물에 함침하는 공정을 통하여 아라미드 섬유의 내광성 증진에 대해 연구하였다. TTIP, TEOS 등의 금속전구체를 이용하여 구형의 나노졸 합성에 의한 $TiO_2$ 나노졸을 수분산형태의 졸로서 섬유가공 공정상에 접목하였다. 제조된 나노크기의 $TiO_2$ 입자분포와 크기, 미세구조 및 결정상을 알아보기 위해 입도분포분석기, TEM, XRD를 이용하였다. $TiO_2$ 나노졸을 함침한 아라미드 직물은 내광성은 24, 48, 96시간 동안 Xenon-arc 광조사한 후, 물성변화를 분석하였다. 나노졸 합성시 반응물의 농도 및 용액의 pH 조건에 따른 나노졸의 미세구조를 TEM을 이용하여 관찰한 결과, 반응물의 농도에 따라 평균입도는 313.7nm, 500.5nm, 840.3nm, 1002nm로 커졌다. 하지만, 반응물의 농도가 증가할수록 시간이 지남에 따라 입자들이 층 분리 현상이 관찰되었으며, 단분산된 나노졸 입자를 제조하기 위해서는 TTIP의 투입량을 0.67mole(200ml)로 유지하였다. 또한 이를 아라미드 직물에 함침하여 광조사 시간에 따른 아라미드 섬유의 물리적 특성의 변화를 분석하였다.

• Korean Journal of Food Science and Technology
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• v.38 no.6
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• pp.751-755
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• 2006

Physicochemical properties of black rice flours (BRFs) produced under different milling conditions were investigated to explore their applications for various processed rice products. Moisture contents of BRFs after roll milling and subsequent hot-air drying or microwave drying were 10.3% and 14.4%, respectively. The BRFs with jet milling and subsequent hot-air drying or microwave drying showed moisture contents of 7.9% and 7.5%. Mean particle sizes of the BRFs obtained from roll milling, jet milling, and following air-classification were 150, 41.5, and 9.4 ${\mu}m$, respectively. Hunter L value and water soluble index (WSI) of BRFs increased with decreasing particle size, while Hunter a value decreased. Total polyphenol contents of 91.4-115.8 mg/100 g and total amino acids of 75.0-96.4 mg/100 g in three types of BRFs were higher as compared to those (6.3 mg/100 g and 30.5 mg/100 g) of polished rice flour (PRF). Physicochemical properties such as moisture content, color parameter, and WSI have close relationship with the particle size of BRFs prepared under different milling conditions.

• Polymer(Korea)
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• v.27 no.4
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• pp.377-384
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• 2003

High impact polystyrene/organically modified layered silicate (HIPS/OLS) nanocomposites by in situ polymerization were synthesized to investigate the effect of clay on the particle size and properties of rubber. In the OLS, the montmorillonite having benzyl group showed best dispersion in polystyrene phase. With the addition of clay, the intercalated peak from XRB was confirmed, but the peak gradually shifted to lower angle as rubber concentration increased. Thus, it is speculated that the organoclay disperses better in rubber phase than in polystyrene phase. The average rubber particle size increased and the particle size distribution widened as the amount of clay increased, which may be caused by the increase of the viscosity ratio of rubber to polystyrene phases and the unstable dispersion. The materials having clay showed improved thermal properties from thermogravimetric analysis. Rheological properties such as complex viscosity and storage modulus increased as the amount of clay increased.