• Korean Journal of Fisheries and Aquatic Sciences
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• v.14 no.4
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• pp.189-193
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• 1981

An apparatus for continuous measurements of sorption isotherm of dried food was manufactured to shorten the time required for equilibration. The apparatus was so designed that the temperature, air velocity and relative humidity in the experimental chamber could be controlled. The use of dynamic stream of conditioned air with a velocity of 0.2m/sec, instead of static atmosphere, allowed a faster equilibration of dried filefish muscle at $25^{\circ}C$. The mean time necessary for the equilibration of dried filefish muscle at the water activity of a given state to a higher water activity was about 45 hours. The monolayer moisture content of dried filefish muscle calculated from BET-equation was 0.092 kg water /kg dry matter at $25^{\circ}C$.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2011.11a
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• pp.47-47
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• 2011

국내의 기능성 난연성 섬유 제조기술은 원사 자체에 난연제가 포함된 상태인 난연 PET 원사나, 일반 PET 원단에 후방염 처리한 원단이 사용되기에 난연 방염성능이 만족스럽지 못하고 친환경적이지 못한 실정이다. 오늘날 세계 난연섬유 시장 규모는 10조원에 이르고 있으며 국내에서도 화재에 대한 경각심이 높아지는 추세이므로 기능성을 갖춘 고부가가치 난연소재의 개발이 시급하다. 폴리페닐렌술피드(PPS)는 내열성 및 내화학약품성이 뛰어난 열가소성 고분자로 용융방사가 가능하다. 난연성이 높은 양모섬유 또는 아크릴계 난연섬유, 아라미드 섬유 등은 비용 문제로 범용화에 한계가 있으므로 비교적 저렴한 PPS 섬유가 개발될 경우 범용화를 기대할 수 있다. 현재는 PPS 섬유가 특수한 용도에 주로 사용되고 있으나 우수한 난연 특성을 이용하여 일반 용도로의 사용 및 수요가 급격히 늘어날 것으로 예상되며 우선적으로 인테리어용 원단, 특히 커튼이나 소파용 원단으로 용도 전개가 가능할 것으로 판단하였다. 본 연구에서는 소파용 PPS 원단의 후가공 조건의 선정 및 불소계 발수방오가공을 위한 최적의 조건을 선정하고자 하였다. Padding(wet pick up율 $80{\pm}3%$)-Drying($105^{\circ}C$, 2.5min)-Curing은 시간은 1분으로 고정시킨 후, 온도를 150, 160, 170, 180, 190, $200^{\circ}C$에서 처리하여 Yellowness값을 측정한 결과, 온도가 높아질수록 Yellowness값이 커지는 것으로 미루어 보아 PPS원단은 높은 열에 영향을 받아 황변 현상이 일어나는 것으로 사료된다. 특히 $180^{\circ}C$를 기점으로 값에 큰 변화를 보였으므로 최적의 열처리 온도는 $170^{\circ}C$로 선정하여 이후의 실험을 진행하였다. 또한 큐어링 시간이 황변에 미치는 영향을 분석한 결과 온도에 의한 영향에 비해 적은 편으로 사료되었으나, 1.5min을 기점으로 Yellowess값이 높아졌으므로 최적의 열처리 시간을 1분으로 선정하였다. 최종 가공조건인 $170^{\circ}C$, 1분에서 처리한 시험포는 처리전 원단과 비교하였을 때, ${\Delta}$Yellowness가 2.84 정도로 나타났다. 그 후, PPS 원단에 불소가공제 (TG-991N, 동인텍스켐)의 적정 농도를 선정하기 위해 1~7%까지 농도를 높이며 처리한 결과, 불소가공제의 농도가 높아짐에 따라 황변현상이 나타남을 알 수 있었다. 농도가 높아짐에 따라 Yellowness값은 증가하다가 4% 이후 완만해지는 것을 알 수 있었으므로 IPA/Water Drop test와 발수도시험 (KS K 0590;2008)을 통해 적정 농도를 선정하였다. PPS 원단은 불소가공제의 농도가 높아짐에 따라 발수도가 우수해졌으며, 가공제 농도 3% 처리만으로도 우수한 발수도를 나타내었으나 100% 발수를 위해서는 가공제 농도가 5% 이상 처리되어야 하는 것을 확인할 수 있었다.

• Food Engineering Progress
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• v.21 no.3
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• pp.267-272
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• 2017

To improve dispersibility of cereal powder without additives, granulation of cereal powder was conducted using fluidized-bed granulator. Operation condition was sample 300 g, internal temperature $40^{\circ}C$, ventilation speed $30-90m^3/h$, inlet temperature $90^{\circ}C$ and spray pressure 2.5 bar. The amount of distilled water (20-45%) as binder, granulation time (10-15 min) and drying time (3-10 min) were controlled. Mean diameter over volume (Brouckere mean, $D_{4,3}$) was increased from $123{\mu}m$ to $263{\mu}m$ and dispersibility was improved from 73% to 92.25% at experiment conditions. Wettability (wetting time) was drastically decreased from 5,000 second to 7 second. Granulation of cereal powder did not affect sinkability and mean diameter over volume as wet analysis was about the same between raw and granulated cereals. Such phenomenon means that granulation with only water as binder enables cereal powder to disperse in water or milk without rapid sedimentation.

• The Journal of Engineering Geology
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• v.32 no.1
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• pp.173-191
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• 2022

In this study, the shear wave velocity of the ground was measured using Flat TDR, and the precision analysis of the measured value and the verification of field applicability were performed. The shear wave velocity measurement value was derived in the field using the piezo-stack combined in the Flat TDR. analyzed. As a result of the experiment, the average value of the change in shear wave speed at the time of grout material injection was 10.15 m/s at the beginning of age, and the average value of the change in shear wave speed after the 7th to 14th days was 65.99 m/s, showing a tendency to increase with age. Also, it was found that dry density and shear wave speed increased as the water content increased on the dry side, and that the dry density and shear wave rate decreased as the water content increased on the wet side as the water content increased. The shear modulus value derived from the field test was confirmed to be a minimum of 17.36 MPa and a maximum of 28.13 MPa, confirming a measurement value similar to the reference value. Through this, it can be seen that the measured value of the shear modulus using Flat TDR is reliable data, and it can be determined that the compaction management of the site can be effectively managed in the future.

• Korean Journal of Soil Science and Fertilizer
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• v.33 no.4
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• pp.292-301
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• 2000

To make a better use of the beneficial bacterial inoculants in the agricultural practice, dry forms of bacterial fertilizer or pesticides are prepared with carrier materials. During the drying process of bacterial inoculant, most of the cells face a severe osmotic pressure and dehydration, and die off. Our study describes the effect of osmoprotectants such as trigonelline and trehalose on the survival of bacterial cells in high salt concentration and drying conditions. A fluorescent Pseudomonas, strain SSL3, used in this study, could grow in high salt concentration of upto 5% but the cells could not overcome the growth retardation at over 7% of salt concentration. The addition of trigonelline, even on small amount, in liquid medium containing 4% NaCl was detrimental to the cell. However, the addition of trehalose of upto 10 mM to the liquid medium containing 4% NaCl, enhanced cell growth. The cell growth was retarded when 150mM trehalose was added to the medium. Upon dry formulation of cells, trehalose was added. And the dry cells were inoculated into the soil to determine the effect of osmoprotectants on the survival of the cells. The survival of the cells, both in wet or dry soil, was improved by the addition of trehalose during the dry cell formulation. The positive effect of trehalose on the cell survival at $-20^{\circ}C$ and $-70^{\circ}C$ was oven more pronounced. The FTIR (Fourier transformation infra-red) spectroscopic analysis showed that the change of the 2nd amide group was reduced by adding trehalose to the medium containing 4% NaCl. These results suggest that trehalose can protect the cell membrane from dryness or high concentration of salt, thereby diminishing the sudden change of the protein structure of the cell membrane and, as a consequence, improving the cell survival.

• Korean Journal of Food Science and Technology
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• v.15 no.2
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• pp.150-154
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• 1983

Mushroom, Lentinus edodes which had been dried at $50^{\circ}C$ for 20 hours were extracted with small amount of ethanol, methanol, chloroform and petroleum ether, respectively. The extracts were then dissolved in edible soybean oil, and the resulting substrates and a portion of the soybean oil (control) were placed in an incubator $(37.0{\pm}1.0^{\circ}C)$ for eight weeks. Peroxide values and TBA values of control and the substrates were determined regularly during the storage period. The results of the present study were as follows: 1. The moisture contents of the mushroom which was 84.88% on wet basis at the time of harvest were reduced to 15.12% after drying. 2. Extracts obtained from alcohols were effective in retarding the POV development. 3. There was not much difference among the TBA values after 14 days, but significant difference of the TBA values in control and the substrates extracts were observed in longer storage period TBA values of substrate containing ethanol and methanol in the later stage period were smaller than that of the substrates containing petroleum ether and chloroform. 4. In view of the POV and TBA value development, ethanol and methanol were more effective solvents for the extraction of antioxidant compounds in the dried mushroom than chloroform and petroleum ether.

• Journal of Korean Society of Forest Science
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• v.60 no.1
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• pp.51-57
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• 1983

Properties and glue shear strength of each water soluble rues-phenol copolymer adhesive and phenolic resin adhesive were examined as a high temperature curing binder through the manufacture of plywood made of Kapur veneer. The former has different molar ratio and the latter was made from different catalyst method. The results are summarized as follows: 1) Specific gravities of air dried plywood manufactured from each adhesive ranged from 0.67 to 0.82 and their moisture contents met the K.S. standard 2) In dry and wet shear strength, adhesives with 60 percent of non volatile content showed higher values than those with 50 percent except phenolic resin. Urea-phenol copolymer resin with 20 percent of phenol content exhibited the highest, and that with 70 percent the lowest. Filling effect of wood flour on the bonding strength is great in urea-phenol copolymer resin with more than 50 percent of phenol content, especially significant in 50 percent of non volatile content including alkali catalyst phenolic resin. Alkali and acid catalyst methods were the highest among the adhesive manufacture methods. In wet strength, urea resin belongs to the lowest group. 3) In glue shear strength after boiling and drying test, no method for manufacturing phenolic formaldehyde resin adhesive was stronger than alkali and acid catalyst methods. Phenolic resin made from alkali catalyst method needs a wood flour filler to improve the bonding quality. Urea-phenol copolymer resin with 10 percent of phenol content showed the reasonable water resistance.

• Journal of the Korea Organic Resources Recycling Association
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• v.24 no.3
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• pp.23-33
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• 2016

The characteristics of ammonia generated from alkaline stabilization facilities was investigated which are for organic sewage sludge from wastewater treatment plants. The highest concentration of ammonia was found in mixing and curing process in alkaline stabilization facility and ammonia mainly showed a range of 87.78 ppm($66.62mg/m^3$) to 1,933 ppm($1,467.01mg/m^3$) by detection tube. This is presumed to occur because nitrogen oxides are converted into ammonia as the sewage sludge is mixed with lime. In some facilities, hydrogen sulfide and methyl mercaptan were detected in relatively high concentrations, but odor materials except ammonia were not detected in most of the facilities. The concentration of ammonia caused by process was generally high in the order of "mixing > curing > output > storage > drying > input." It was found that odor compounds are removed by wet absorption using sulfuric acid and sodium hypochlorite in the 5 alkaline stabilization facilities currently in operation. Each facility was designed to meet the concentration of after-treatment emission in 1 ppm($0.76mg/m^3$), 50 ppm($37.95mg/m^3$) or 100 ppm($75.89mg/m^3$), but no facility satisfied the design standard for their emssion limit. In case of ammonia, some workplaces in alkaline stabilization facilities exceeded the exposure limits established by the Ministry of Labor. It appears that proper ventilation should be provided for the safety of workers in future. No odor compound including ammonia was found by detection tubes in the border of the facilities, but trace amounts of odor compounds are expected to exist, given the current operational status of facilities.

• Korean Journal of Soil Science and Fertilizer
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• v.17 no.2
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• pp.147-154
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• 1984

Two Fe-hydrous oxide A,B and one Al-hydroxide minerals were synthesized precipitating Fe $Cl_3$ and $AlCl_3$ with alkali solution(NaOH) at pH 6.0, 12.0 and 4.5 respectively, for precise understanding of physico-chemical and surface charge characteristics of soils in which these minerals are dominant. Identification of these final products, effect of free and amorphous materials on X-ray diffraction analysis, particle size distribution and surface change characterics of these minerals were performed. Fe-hydroxide A and B were identified as great deal of X-ray amorphous material and as goethite with large amount of X-ray amorphous material, respectively. Dehydration by oven at $105^{\circ}C$ of these minerals exhibited akaganeite peaks with low X-ray amorphous hump and pure goethite peaks for Fe-hydroxide A and B, respectively. Both minerals, however, turned into hematite upon firing at $550^{\circ}C$. On the other hand, Al-hydroxide identified as mixture of gibbsite and bayerite of around 7:3 ratio. Application of sodium dithionite and ammonium oxalate solutions for removal of free or amorphous Fe and Al from these minerals revealed that only peak intensities of Al-hydroxide system were enhanced upon Al-extraction by oxalate solution even though dithionite solution was much powerful to extract Fe from Fe-hydrous oxide systems. Original(wet) Fe-hydrous oxide A has the highest specific surface and surface charge development(negative and positive), and the greatest amount of less than $2{\mu}m$ sized particles. Specific surface and clay sized particles(less than $2{\mu}m$) of Fe-hydrous oxide A, however, were drastically reduced upon dehydration($P_2O_5$ and oven drying) compare to the rest minerals. The Z.P.C. of these synthetic minerals were 8.0-8.5, 7.5-8.0 and 5.5-6.0 for Fe-hydrous oxide A, B and Al-hydroxide, respectively.

• Journal of Korean Society of Forest Science
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• v.42 no.1
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• pp.83-100
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• 1979

It was planned and performed to study the possibility on the use of inexpensive and easily acquirable foliage powder, which processed by pulverizing after dried, instead of imported expensive wheat flour for the extending of plywood adhesives. Pine leaves of softwood trees, Poplar, Oak and Sycamore leaves of broad leaved species were selected and harvested to pulverize into the minute foliage powder. The harvested foliages from each selected species were pulverized into 40 mesh particles after dried at $100{\sim}105^{\circ}C$ condition during 24 hours in drying oven. To compare the extending effect of plywood adhesives with these foliage powders 100 mesh wheat flour using at current plywood industry was also prepared. Foliage powder and wheat flour were extended into 10, 20, 30, 50 and 100% to the urea and phenol formaldehyde resin. After plywoods were processed by the above extending method shear strength of extended plywoods were analyzed and discussed. The results obtained at this study are as follows: 1) Among 10% extensions of urea formaldehyde resin plywood, dry shear strength of plywood extended by wheat flours was the highest and that of non-extended plywood the next. Plywood extended with foliage powder showed the lowest dry shear strength. The order of dry shear strength of plywoods extended by foliage powder was that of Oak foliage powder extension, the best, that of Sycamore, that of Pine, and that of Poplar. 2) Among 20% extensions of urea formaldehyde resin plywood, plywood extended by wheat flour showed the highest dry shear strength, and the next was plywood by Poplar foliage powder. All these two showed higher dry shear strength than non-extension plywoods. Except Poplar, dry shear strength of foliage powder extension plywoods was bad, but the order of dry shear strength of plywoods extended by foliage powder was Pine, Poplar and Oak. 3) In the case of 30% extensions of urea formaldehyde resin plywood, dry shear strength of wheat flour extension was the highest and non-extension the next. Dry shear strength of foliage powder extension plywoods was poor with a rapid falling-off in strength. 4) Among 50% and 100% extensions of urea formaldehyde resin plywood, only wheat flour showed excellent dry shear strength. In the case of foliage powder extension, low dry shear strength showed at the 50% extension of Pine and Poplar, and plywoods of 50% extension of Oak foliage powder delaminated without measured strength. All plywoods of 100% foliage powder extension delaminated, and then shear strength were not measured. 5) Among wet shear strength of 10% extensions of urea formaldehyde resin plywood, wheat flour extension was the highest as in the case of dry shear strength, and non-extension plywood the next. Except Poplar foliage extension, all foliage powder extension plywoods showed low shear strength. 6) Wet shear strength of plywoods of 20% extension lowered in order of non-extension plywood, plywood of wheat flour extension and plywood of foliage powder extension, but other plywoods of foliage powder extension except plywoods of Poplar and Oak foliage powder extension delaminated. 7) Wet shear strength of 30% or more extension of urea formadehyde resin plywood were weakly measured only at 30% and 50% extension of wheat flour, and wet shear strength of plywoods extended by foliage powder were not measured because of delaminating. 8) Dry shear strength of phenol formaldehyde plywoods extended by 10% wheat flour was the best, and shear strength of plywoods extended by foliage powder were low, but the order was Oak, Poplar, and Pine. Plywood of Sycamore foliage powder extension delaminated. 9) In the case of 20% extensions of phenol formaldehyde resin, dry shear strength of plywood extended by wheat flour was the best, but plywood of Pine foliage powder extension the next, and the next order was Oak and Poplar foliage powder. Plywood of Sycamore foliage powder extension delaminated. 10) Among dry shear strength of 30% extensions of phenol formaldehyde plywood, that of Pine foliage powder extension was on the rise and more excellent than plywood of wheat flour extension, but Poplar and Oak showed the tendency of decreasing than the case of 20% extension. Plywood of Sycamore foliage powder extension delaminated. 11) While dry shear strength of 50% and 100% extension plywoods were excellent in the case of Pine foliage powder and wheat flour extension, that of hardwood such as Poplar, Oak, and Sycamore foliage powder extension were not measured because of delaminating. 12) As a filler the foliage powder extension of urea formaldehyde resin is possible up to 20% with Poplar foliage powder. And also as an extender for phenol formaldehyde resin, Pine foliage powder can be added up to the same amount as that in the case of wheat flour.