• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.6
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• pp.751-758
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• 2017

The objective of this study was to determine the effects of moisture content and screw speed on the physical properties of extruded soy protein isolate (SPI). Expansion index, water absorption index, texture, integrity index, color, and nitrogen solubility index of extruded SPI were analyzed to determine the relationship with extrusion conditions. Extrusion conditions were moisture content (40, 50, and 60%) at a fixed die temperature ($140^{\circ}C$) and screw speed (250 rpm). The other extrusion conditions were screw speed (150, 250, and 330 rpm) at a fixed moisture content (55%) and die temperature ($140^{\circ}C$). Specific mechanical energy (SME) input decreased as moisture content increased from 40 to 60%. However, SME input increased as screw speed increased from 150 to 330 rpm. Expansion ratio and piece density decreased as moisture content and screw speed increased, and specific length increased as moisture content and screw speed increased. The extruded SPI at 40% moisture content had higher water absorption index, texture, and color differences than those of the extruded SPI at other moisture contents (50 and 60%). however, the extruded SPI at 40% moisture content had lower integrity index and cutting strength than those of the extruded SPI at other moisture contents (50 and 60%). In conclusion, the physical properties of extruded SPI were more affected by moisture content than screw speed.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.5
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• pp.455-462
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• 2000

The objective of this study was to examine the physicochemical characteristics of coagulation reaction between loess and red tide organisms (RTO) and its feasibility, in developing a technology for the removal of RTO bloom in coastal sea. The physicochemical characteristics of loess were examined for a particle size distribution, surface characteristics by scanning electron microscope, zeta potential, and alkalinity and pH variations in sea water. Two kinds of RTO that were used in this study, Cylindrothen closterium and Skeietonema costatum, were sampled in Masan bay and were cultured in laboratory. Coagulation experiments were conducted using various concentrations of loess, RTO, and a jar tester. The supernatant and RTO culture solution were analyzed for pH, alkalinity, RTO cell number. A negative zeta potential of loess increased with increasing pH at $10^(-3)M$ NaCl solution and had -71.3 mV at pH 9.36. Loess had a positive zeta potential of +1,8 mV at pH 1.98, which resulted in a characteristic of material having an amphoteric surface charge. In NaCl and $CaCl_2$, solutions, loess had a decreasing negative zeta potential with increasing $Na^+\;and\;Ca^(+2)$ ion concentration and then didn't result in a charge reversal due to not occurring specific adsorption for $Na^+$ ion while resulted in a charge reversal due to occurring specific adsorption for $Ca^(+2)$ ion. In sea water, loess and RTO showed the similar zeta potential values of -112,1 and -9.2 mV, respectively and sea sand powder showed the highest zeta potential value of -25.7 mV in the clays. EDLs (electrical double-layers) of loess and RTO were extremely compressed due to high concentration of salts included in sea water, As a result, there didn't almost exist EDL repulsive force between loess and RTO approaching each other and then LVDW (London-yan der Waals) attractive force was always larger than EDL repulsive force to easily form a floe. Removal rates of RTO exponentially increased with increasing a loess concentration. The removal rates steeply increased until $800 mg/l$ of loess, and reached $100{\%}$ at 6,400 mg/l of loess. Removal rates of RTO exponentially increased with increasing a G-value. This indicated that mixing (i.e., collision among particles) was very important for a coagulation reaction. Loess showed the highest RTO removal rates in the clays.

• Korean Journal of Food Science and Technology
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• v.48 no.2
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• pp.153-158
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• 2016

The principal objective of this study was to produce a chitosan nanoparticle (NP) system for improving blood circulation. Chitosan NPs were prepared using fucoidan and $poly-{\gamma}-glutamic$ acid (PGA), denoted as CS/Fu and CS/Fu/PGA NPs, respectively. As the chitosan concentration was increased, the activated partial thromboplastin time (APTT) of the NPs significantly increased (p<0.05). When the concentration of fucoidan and ${\gamma}-PGA$ was 5-20 and $1-10{\mu}g/mL$, respectively, the size of the CS/Fu and CS/Fu/PGA NPs was approximately 200 and 100 nm, respectively. With an increase in the fucoidan and PGA concentration, the APTT of CS/Fu and CS/Fu/PGA NPs significantly increased (p<0.05). These results suggest that CS/Fu and CS/Fu/PGA NPs could be used as a potent NP system for improving blood circulation.

• Applied Chemistry for Engineering
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• v.20 no.2
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• pp.234-240
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• 2009

$Mg(OH)_2$ particles were prepared by precipitation and a hydrothermal treatment to examine the effect of $MgCl_2$ concentration, alkali type and concentration, temperature, hydrothermal treatment on the formation of $Mg(OH)_2$ particles using full factorial design, as one of DOE (Design of experiment) methods. The primary particle size is similar to the secondary particle size for the samples after the hydrothermal treatment, where the average particle size of $Mg(OH)_2$ increased with increasing the concentration of $MgCl_2$ and hydrothermal temperature and decreasing alkali/Mg molar ratio. On the other hand, for the samples prepared from precipitation, the secondary particle size is larger than the primary particles due to aggregation. The difference in alkaline source is that the particles prepared from $NH_4OH$ exhibit the larger size with better dispersion than those from NaOH. Low density polyethylene and ethylene-co-vinyl acetate (LDPE-EVA) resin composed of the smaller secondary particle size of $Mg(OH)_2$ shows a higher limited oxygen index (LOI) at 50 and 55% loading, but the smaller primary particle size may result in a better grade in UL-94 tests. At the high loading of 60%, all samples with any preparation methods exhibit V-0 grade but the LOI value depends on not only primary particle size but also dispersion state.

• Journal of Life Science
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• v.24 no.8
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• pp.813-819
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• 2014

The spatial distribution of geographical distances at five natural populations of Camellia japonica in Busan, Korea was studied. The four plots (Mollundae, Gadeok-do, Du-do, and Jwiseum) of C. japonica were uniformly distributed in the forest community and only one plot (Amnam-dong) was aggregately distributed in the forest community. Morisita index is related to the patchiness index showed that the plot $20m{\times}50m$ had an overly steep slope when the area was larger than $20m{\times}20m$, which indicated that the degree of aggregation increased significantly with increasing quadrat sizes, while the patchiness indices did not change from the plot $5m{\times}10m$ to $10m{\times}10m$. The spatial structure was quantified by Moran's I, a coefficient of spatial autocorrelation. Ten of the significant values (76.9%) were positive, indicating similarity among individuals in the first 4 distance classes (80 m), i.e., pairs of individuals with dissimilarity characteristics can separate by more than 100 m.

• Bulletin of Food Technology
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• v.26 no.2
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• pp.125-131
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• 2013

즉석 쌀국수는 쌀 함량을 10~30% 첨가하는 수준으로 출발하여 최근에는 쌀 함량 100% 생면 및 인디카 품종을 활용한 베트남 쌀국수 타입으로 점차 쌀 함량이 높아지고 있으나, 쌀 고유의 특성으로 면의 가공적성이 어려우며, 조리 시 전분 용출량이 많은 단점이 있다. 따라서 현재 국내 시판 쌀국수 5종을 구입하여 쌀 함량별로 분류하여 품질특성과 관능특성을 비교하여 즉석 쌀국수의 품질특성을 알아봄으로써 즉석 쌀국수 개발 연구에 기초 자료를 제공하고자 하였다. 품질특성 결과 감자전분, 찰옥수수전분을 첨가한 제품의 경우 수분흡수지수가 높게 나타났으며, 조직감 측정결과 밀가루가 첨가된 처리구가 밀가루 무첨가 처리구에 비해 높은 값을 나타내어 전분 및 밀가루 첨가에 따라 경도, 응집성 및 검성이 증가하였으며, 관능특성 결과 국내쌀을 사용한 처리구가 수입쌀을 사용한 처리구보다 높게 나타내어 국내쌀로 만든 쌀국수를 더 선호하는 경향이 있는 것으로 나타났다. 따라서 향후 쌀국수 제품 개발 적용 시 쌀가루 용도별 제분기술의 발달 및 감자전분, 찰옥수수전분, 타피오카전분 등의 전분류를 첨가하여 쌀국수 개발기술을 확보하면 품질이 우수하고 다양한 형태의 즉석 쌀국수 제품개발이 기대된다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.273-273
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• 2010

최근 들어 에너지 개발과 환경문제의 해결방안으로 열전발전 및 열전냉각에 많은 관심과 연구가 진행되고 있다. 열전소재의 특성 향상을 위해 열전성능지수를 높이기 위하여 나노 입자상을 열전소재 내에 분산하고자 하는 연구가 진행되었다. Grain 내에 나노 입자를 분산하기 위해서는 원료 입자에서부터 나노 입자가 열전소재 내에 분산되어야 하며 이것은 산화물 나노입자의 코어-쉘 형성으로부터 가능하다. 이 과정에서 나노 입자를 열전소재 내에 코어로 분산하기위한 나노입자의 합성 및 제어가 필수적이다. 본 연구에서는 용융염법을 이용한 BaTiO3 나노 일자를 합성하고 이들을 용매에 분산하는 것을 목표로 하였다. 염으로는 KCl, LiCl, NaCl 및 이들의 혼합 염을 사용하였으며 염의 청가량, 염의 종류, 반응온도 및 반응시간의 변화에 따라 BaTiO3 나노 입자를 합성하였다. 또한, 합성된 나노 입자의 입자크기와 응집 제어를 통해 나노입자들의 분산 상태를 확인해 보았다. 이 결과는 SEM, TEM, 입도측정기, XRD등의 측정 결과를 통하여 확인하고자 하였다.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.55 no.1
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• pp.10-16
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• 2022

Interest in effluent treatment is currently increasing and the use of polymetric coagulants is considered as a pretreatment of physical filtration prior to effluent discharge to increase solids recovery. A jar test evaluated effluent treatment efficiency of polymeric coagulants for semi-recirculating aquaculture systems. The particle coagulation efficiency and distribution were evaluated at different polymer dosages in freshwater and seawater effluents. The polymer was added at 0.005-0.08 mL/g of total suspended solids (TSS) in the effluents. TSS in the supernatant after coagulation decreased with increasing polymer dose in the freshwater, while showing no corresponding changes with dose in the seawater. However, in all treatments for both effluents, the removal efficiency was above 90%, regardless of the dose in the tested range. Both the De Brouckere Mean Diameter (DBMD) and volumetric median diameter (VMD) were all above 100 ㎛ in the freshwater effluent. In the seawater effluent, the particle size appeared to be larger than that in freshwater, ranging from 400-1,000 ㎛ for both DBMD and VMD. Considering that the typical pore size of physical filtration in aquaculture is between 60 and 200 ㎛, the use of polymers is expected to improve the practicality of physical filtration for efficient treatment.

• Journal of Life Science
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• v.22 no.12
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• pp.1680-1687
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• 2012

Postmenopausal women are at an increased risk of developing coronary artery disease, primarily due to dyslipidemia that accompanies the loss of estrogen secretion. This study was performed to investigate the effects of Opuntia humifusa seed extracts on blood flow and serum lipid level in ovariectomized rats. Twenty-eight 9-week old female Sprague-Dawley rats were randomly assigned to four groups as sham-operated rats (SHAM), ovariectomized rats (OVX-CON), and ovariectomized rats that were treated with Opuntia humifusa seed extracts (OVX-OHS 2% and OVX-OHS 6%). The diets were fed to the rats for 7 weeks after operation. Serum total cholesterol and triglyceride contents decreased in the SHAM group compared to the OVX-CON group. Seven weeks of feeding of Opuntia humifusa seed extracts resulted in significant (p<0.05) lowering of serum triglyceride and a decreasing tendency in total cholesterol levels. The level of HDL-cholesterol in serum increased significantly by feeding diets containing the 2% and 6% Opuntia humifusa seed hot-water extract (p<0.05). Blood passage times were shorter in the Opuntia humifusa seed extract-supplemented groups than in the untreated group (OVX-CON). The platelet aggregation ability was lower in groups treated with Opuntia humifusa seed extracts than in the OVX-CON group. These results suggest that Opuntia humifusa seed extracts may have benefits in improving metabolic syndrome in menopausal women.

• Korean Journal of Environment and Ecology
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• v.37 no.4
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• pp.289-301
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• 2023

Forests within watersheds are essential in maintaining ecosystems and are the central infrastructure for constructing an ecological network system. However, due to indiscriminate development projects carried out over past decades, forest fragmentation and land use changes have accelerated, and their original functions have been lost. Since a forest's structural pattern directly impacts ecological processes and functions in understanding forest ecosystems, identifying and analyzing change patterns is essential. Therefore, this study analyzed structural changes in the forest landscape according to the time-series land cover changes using the FRAGSTATS model for the dam watershed of the Geum River upstream. Land cover changes in the dam watershed of the Geum River upstream through land cover change detection showed an increase of 33.12 square kilometers (0.62%) of forests and 67.26 square kilometers (1.26%) of urbanized dry areas and a decrease of 148.25 square kilometers (2.79%) in agricultural areas from the 1980s to the 2010s. The results of no-sampling forest landscape analysis within the watershed indicated landscape percentage (PLAND), area-weighted proximity index (CONTIG_AM), average central area (CORE_MN), and adjacency index (PLADJ) increased, and the number of patches (NP), landscape shape index (LSI), and cohesion index (COHESION) decreased. Identification of structural change patterns through a moving window analysis showed the forest landscape in Sangju City, Gyeongsangbuk Province, Boeun County in Chungcheongbuk Province, and Jinan Province in Jeollabuk Province was relatively well preserved, but fragmentation was ongoing at the border between Okcheon County in Chungcheongbuk Province, Yeongdong and Geumsan Counties in Chungcheongnam Province, and the forest landscape in areas adjacent to Muju and Jangsu Counties in Jeollabuk Province. The results indicate that it is necessary to establish afforestation projects for fragmented areas when preparing a future regional forest management strategy. This study derived areas where fragmentation of forest landscapes is expected and the results may be used as basic data for assessing the health of watershed forests and establishing management plans.