• Korean Journal of Soil Science and Fertilizer
• /
• v.28 no.3
• /
• pp.249-255
• /
• 1995

This study was conducted to investigate the effects of some soil conditioners, such as polyacrylamide(PAM), polyvinylalcohol(PVA) and Bitumen emulsion, on aggregate formation and stability, wetting angle, sorptivity and penetrability of the soil with different textures : sand, sandy loam, loam and clay loam. A pot experiment was carried out to find out the effect of treatment on the germination and growth of lettuce with three textures : sand, sandy loam and silt loam. Soil aggregates larger than 2mm in untreated soils at dry condition were naught in sand, 45% in sandy loam, 80% in loam and 90% in clay loam. Treatments of soil conditioners tended to increase the occurrence of soil aggregate larger than 2mm, which were 20~25% in sand, 55~75% sandy loam, but not affected greatly aggragate occurence in loam and clay loam. The aggregate instability was decreased by the soil conditioner treatment. The wetting angles of the soils were greatly changed by hydrophobic of Bitumen, but those were changed slightly by PVA and PAM application. The sorptivity and penetrability data indicated that the effects of different materials on these parameters differed depending upon soil texture. Application of PVA and PAM were no effect exceptive in sand. Application of Bitumen revealed that water movement was not showed in all soils. The germination rate, root weight and top plant weight of lettuce were increased in all soils by PAM treatment as compared to untreated soils. Particularly the greater effect was occurred in sand soil than in sandy loam and silt loam. PAM increased greatly the moisture content and air phase of soils.

• Journal of Korean Ophthalmic Optics Society
• /
• v.13 no.3
• /
• pp.45-50
• /
• 2008

Purpose: A soft contact lens was manufactured by adding naringin known as natural anti-bacterial material to resin solution. With solution eluted from manufactured contact lens, we examined its optical properties, physical and chemical states of naringin in the polymer, and elution properties. Methods: The soft contact lens with naringin was synthesized by bulk polymerization method. IR spectrum and HPLC were used to define the bonding type of naringin itself in the soft contact lens contained naringin, elution process of naringin to the saline solution, and the amount of naringin solution eluted from the lens with elapsed time. Results: Naringin was continuously eluted with constant concentration from the soft contact lens for about a month and the structure ofnaringin which is eluted was as same as before it was added to resin solution. Any change in optical properties such as transmittance couldn't be found. Bonding state and the structure of naringin in contact lens were explained with IR spectrum and HPLC results. Conclusions: In the contact lens with naringin, naringin remained in the contact lens bonding with weak hydrogen bonding and/or van der Waals force between naringin and polymer. Naringin was continuously eluted from the contact lens contained naringin during about 1 month. Even after 1 month, it showed that the concentration of the naringin eluted was approximately 10 ppm in a day. From the results, adding naringin to the soft contact lens resin is very effective method for manufacturing the soft contact lens which has anti-bacterial function for a period of time.

• Applied Chemistry for Engineering
• /
• v.16 no.6
• /
• pp.809-814
• /
• 2005

In this work, the thermal properties of epoxy coating system on the liner plate in the containment structure of nuclear power plants had been examined by irradiation and design basis accident (DBA) conditions. The effect of immersion in hot water on adhesion strength of the coating system had been also studied. The glass transition temperature ($T_g$) and thermal stability of ET-5290/carbon steel A 32 epoxy coating systems were measured by DSC and TGA analyses, respectively. Contact angle measurements were used to determine the effect of immersion on the surface energetics of epoxy coating system, with a viewpoint of surface free energy. Adhesion tests were also executed to evaluate the adhesion strength at interfaces between carbon steel plate and epoxy resins. As a result, it was found that the irradiation led to an improvement of internal crosslinked structure in cured epoxy systems, resulting in significantly increasing the thermal stability, as well as the $T_g$. Also, the immersion in hot water made a role in the post-curing of epoxy resins and increased the mechanical interlocking of the network system, resulting in increasing the adhesion strength of the epoxy coating system.

• Korean Journal of Food Science and Technology
• /
• v.48 no.1
• /
• pp.20-26
• /
• 2016

This study invesigated the physicochemical properties of rice flours from conventional and high-yielding rice varieties in order to enhance usability processing of high-yielding rice varieties. Moisture content was not remarkably different among rice flours by cultivar. The highest content of total free sugars was detected in Hopum rice. Apparent amylose content of Anda was higher than that of other rice varieties. The total amount of amino acids was highest in Anda rice among the rice cultivars. Contents of vitamin $B_1$ in Hanarum were highest among the rice cultivars. Initial pasting temperature was lowest in Anda rice ($60.10^{\circ}C$). Hanarum rice showed the lowest setback values among the rice flours. Therefore, Anda and Hanarum rice cultivars were suggesting the possibility of a processed rice food source.

• Korean Journal of Food Science and Technology
• /
• v.46 no.3
• /
• pp.347-351
• /
• 2014

We studied the green synthesis and antibacterial activity of chitosan-silver (Ag) nanocomposite films for application in food packaging. Green synthesis of Ag nanoparticles (AgNPs) was achieved by a chemical reaction involving a mixture of chitosan-silver nitrate ($AgNO_3$) in an autoclave at 0.1 MPa, $121^{\circ}C$, for 15-120 s. The formation of AgNPs in chitosan was confirmed by both UV-Visible spectrophotometry and transmission electron microscopy (TEM) and the effects of chitosan-$AgNO_3$ concentration and reaction time on the synthesis of AgNPs in chitosan were examined. The resulting chitosan-Ag composite films were characterized by various analytical techniques and their antibacterial activity was evaluated based on the formation of halo zones around films, indicating inhibition of the growth of Escherichia coli. A fourier-transform infrared (FTIR) spectroscopy analysis showed that free amino groups in chitosan acted as effective reductants and AgNP stabilizers. The composite films exhibited enhanced antibacterial activity with increasing Ag content on the surface of as-prepared composite films.

• Journal of Digital Convergence
• /
• v.17 no.10
• /
• pp.373-379
• /
• 2019

Polymethyl methacrylate (PMMA), a self-polymerizing resin for removable orthodontic devices, has been used as a dental orthodontic device for many years because of its advantages such as color stability, volume stability, and tissue compatibility. However, such a removable orthodontic device has a disadvantage that the longer the use in the oral cavity due to the low strength of the PMMA fracture of the orthodontic device resin in use. In this study, zinc nanoparticles (ZNP) were mixed with orthodontic PMMA to introduce strength effect. Rectangular samples ($1.4{\times}3.0{\times}19.0mm$) of orthodontic PMMA (0, 0.5, 1.0, 2.0 and 4.0%) containing ZNP were prepared. The finished specimen was tested for three-point bending strength at a speed of 1 mm / min, and the Vickers hardness was measured three times using a hardness tester. The surface roughness was measured with a surface roughness. As a result, the 3-point bending strength did not change significantly (p>0.05). Surface energy increased significantly. As a result, we successfully synthesized ZNP in this study and prepared the dispersed resin specimen for calibration. It will be possible to develop high-density dental orthodontic resins.

• Korean Journal of Food Science and Technology
• /
• v.51 no.5
• /
• pp.459-465
• /
• 2019

Three kinds of foods (strawberry jam, J; braised lotus root, B-LR; stir-fried anchovies, SF-A) containing fructooligosaccharide (FOS) or isomaltooligosaccharide (IMO) were prepared, and the changes of physical properties and sugar composition were compared with control (sample containing sucrose). For the samples contaning oligosaccharides, $a^*$ value increased, and $b^*$ value decreased after cooking. The sample with sucrose showed higher hardness than those with FOS or IMO. For sugar composition and stability of the oligosaccharides after cooking, the amount of IMO was almost remained in each food, however, that of FOS decreased from 47.2, 49.5, 48.9 to 20.5, 49.0 and 28.8%, for J, B-LR and SF-A, respectively. Based on the above results, softer cooked food could be prepared with oligosaccharide than sucrose, and when considering to functionalitiy, IMO is more suitable for general cooking at home than FOS.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.12 no.2 s.25
• /
• pp.107-113
• /
• 2006

Water treatment plant sludge occurred in sedimentation and inverse wash process is generally disposed by ocean dumping or reclamation after dehydration processing using mechanical or natural dry method. Recently, ocean dumping of sludge is limited actually by London Convention. Physical, chemical, and geotechnical characteristics of water treatment plant sludge were analyzed by experiments. The possibilities for recycling of the dehydration sludges as materials for covering sanitary landfill were examined. Experiments performed with sludges mixed with general soil to improved the sludge properties are the hydrometer analysis, the liquid and plastic limit test, the specific gravity test, the compaction test, and the unconfined compression test. The value of ${\gamma}_{dmax}$ is increased and OMC(Optimum Moisture Content) is lessened with mixed sludge. The value of maximum compressive strength and friction angle are increased and the cohesion is decreased with mixed sludge. The ratio between sludge and soil in mixed sludge was 3:7 and the strength of mixed sludge showed $3.6kg/cm^2$. These results satisfy the regulation of U.S. E.P.A regarding materials for covering sanitary landfill.

• Proceedings of the SCSK Conference
• /
• 1996.07a
• /
• pp.33-51
• /
• 1996

화장품의 변질요인은 크게 물리적 또는 화학적 변화에 의한 요인과 미생물오염으로 인한 각종 문제점으로 대별될 수 있다. 이 중에서 미생물 오염문제는 제품의 상품가치에 미치는 영향 뿐만 아니라 지속적인 사용에 의한 피부의 위생적 측면때문에 그 중요성에 대한 인식이 높아지고 있다. 따라서, 제품개발시는 화장품 처방중의 영양성분의 배합, pH, 유화형태, 방부제의 혼합, 분배계수 및 그 안정성을 고려하여야 함은 물론이고 처방중의 모든 원료의 각각에 대한 항균능 및 피부자극여부를 사전에 미리 조사하여 각 제품별로 적당한 방부체계를 선택하는 것은 매우 중요한일이다. 독성실험방법에 있어서 in vivo 실험에 대체할 수 있는 새로운 in vitro 실험방법 수립 즉, 동물실험을 하지 않고 in vitro 실험결과로부터 in vivo 결과를 예측할 수 있도록 새로운 in vitro 실험체계의 가능성을 실험하였다. 4종의 cell line중 transformed mouse fibroblast L929가 본 실험에서 사용하기에 배양상의 용이성과 안정성, 재현성의 관점에서 가장 알맞은 cell line이었다. transformed mouse fibroblast L929를 사용한 NR$_{50}$ assay와 Draize score간의 regression coefficient ${\gamma}$값은 0.91이었다. 혈청은 시험물질의 세포에 대한 민감성에 영향을 주었다. 따라서, modified serum-free method를 이용함으로써 regression coefficient가 증가된 즉, 상관성 및 재현성이 높은 결과를 얻을 수 있었다. 이러한 기술은 독성실험에 실험동물을 사용하지 않고 in vivo test에 대체 할 수 있고, 또한 화학물질에 대한 prescreening으로 이용할 수 있을 것으로 판단된다.원과 섭식장소, 수중생물의 경우는 특히 수온, 수량 영양원등이다.(중략). 본 연구의 접근방법으로는 ASRS의 개념적인 Reference Model을 수립하고 이 Reference Model에 대한 Formal Model로 DEVS(Discrete Event System Specification)을 이용하여 시스템을 Modeling하였다. 이의 Computer Simulation을 위하여 DEVS형식론 환경에서의 Simulation Language인 DEVSim ++ⓒ를 이용하여 시스템을 구현하였다.. 실형 결과로는 먼저 선형 상미분방정식의 예로 mass-damper-spring system, 비선형 상미분방정식의 예로는 van der Pol 방정식, 연립 상미분방정식의 예로는 mixing tank problem 등을 보였으며, 그의 공학에서 일어나는 여러 가지 문제들도 다루었다.화물에 대한 방어력이 증가되어 나타난 결과로 여겨지며, 또한 혈청중의 ALT, ALP 및 LDH활성을 유의성있게 감소시키므로서 감잎 phenolic compounds가 에탄올에 의한 간세포 손상에 대한 해독 및 보호작용이 있는 것으로 사료된다.반적으로 홍삼 제조시 내공의 발생은 제조공정에서 나타나는 경우가 많으며, 내백의 경우는 홍삼으로 가공되면서 발생하는 경우가 있고, 인삼이 성장될 때 부분적인 영양상태의 불충분이나 기후 등에 따른 영향을 받을 수 있기 때문에 앞으로 이에 대한 많은 연구가 이루어져야할 것으로 판단된다.태에도 불구하고 [-wh]의미의 겹의문사는 병렬적 관계의 합성어가 아니라 내부구조를 지니지 않은 단순한 단어(minimal $X^{0}$ elements)로 가정한다. 즉, [+wh] 의미의 겹의문사는 동일한 구성요 소를 지닌 병렬적 합성어([$[W1]_{XO-}$ $[W1]_{XO}$ ]

• Food Science and Preservation
• /
• v.16 no.4
• /
• pp.525-533
• /
• 2009

To explore cattail pollen powder as a functional food ingredient, we analyzed the general components of pollen powder, tested changes in the physical properties of dough containing the powder, and investigated the process ability of powder-containing dough in bread making by adding 3%, 6%, or 9% by weight of pollen powder to wheat flour. Cattail pollen powder consisted of (all w/w) 12.7-13.2% water, 15.7-17.8% crude protein, 1.3% crude fat, 7.5-7.7% free sugar, 14.7-18.6% crude fiber, 3.4-4.9% pollen, and 49.7-55.9% soluble nitrogen-free extract (NFE). Analysis of the physical properties of dough mixed with pollen powder showed that as more pollen powder was added, the absorption rate increased, but dough stability decreased. With increasing levels of cattail pollen powder, the falling number decreased, and amylase activity increased. Fermentability was highest in dough made with 3% by weight of pollen powder, and the bread product made from such dough had the greatest volume. As more cattail pollen powder was added, the moisture activity in dough tended to decrease to a greater extent than seen in control dough, and this tendency increased with time. We found that longer storage periods were associated with greater hardness and springiness, which indicated degradation in product quality. Therefore, it is suggested that bread products containing cattail pollen powder should be consumed within 3 days of preparation. In a taste survey, bread baked with 3% (w/w) cattail pollen powder scored highest in all questionnaire items.