• 상하수도학회지
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• 제21권4호
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• pp.503-508
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• 2007

Small scale D-water treatment plant(WTP) where has slow sand filtration was using raw water containing high concentration of manganese (> 2mg/l). The raw water was pre-chlorinated for oxidation of manganese and resulted in difficulty for filtration. Thus, sometimes manganese concentration and turbidity were over the water quality standard. Two stage rapid manganese sand filtration pilot plant which can treat $200m^3/d$ was operated to solve manganese problem in D-WTP. The removal rate of manganese and turbidity were about 38% and 84%, respectively without pH control of raw water. However, when pH of raw water was controlled to average 7.9 with NaOH solution, the removal rate of manganese and turbidity increased to 95.0% and 95.5%, respectively and the water quality of filtrate satisfied the water quality standard. Manganese content in sand was over 0.3mg/g which is Japan Water Association Guideline. The content in upper filter was 5~10 times more than that of middle and lower during an early operation but the content in middle and lower filter was increased more and more with increase of operation time. This result means that the oxidized manganese was adsorbed well in sand. Rapid manganese sand filter was backwashed periodically. The water quality of backwash wastewater was improved by sedimentation. Thus, turbidity and manganese concentration decreased from 29.4NTU to 3.09NTU and from 1.7mg/L to 0.26mg/L, respectively for one day. In Jar test of backwash wastewater with PAC(Poly-aluminum chloride), optimum dosage was 30mg/L. Because the turbidity of filtrate was high as 0.76NTU for early 5 minute after backwash, filter-to-waste should be used after backwash to prevent poor quality water.

• 한국식품조리과학회지
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• 제24권3호
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• pp.282-293
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• 2008

The purpose of this study was to acquire basic data on Jeolpyun added with Baekbokryung powder to aid the product's commercial production. Initially a sensory test was performed with consumers to the identify preferred amount of Baekbokryung powder to add according to age. The results revealed that those in their 20's to 40's preferred the 3% treatment, while those 50 and older preferred the 5% treatment. Next, the optimum water content of Jeolpyun was chosen by examining select quality characteristics in samples containing 20, 25, 30, 35 and 40% water while the amounts of added Baekbokryung powder were fixed at 3% and 5%, respectively, as based on the sensory panel results. For the color characteristics of the samples, lightness(L), redness(a) and yellowness(b) values increased in proportion to the added amount of water regardless of the Baekbokryung level. However, the ${\Delta}E$ values of the samples increased with storage time along with the darkening of their surfaces. The samples with high moisture contents, such as the 35 and 40% treatments, maintained a relatively softer texture during 24 hr of storage as compared to the other samples. Also noted was an initial slow increase in hardness up to 12 hr of storage, and then accelerated hardening until 24 hours of storage. Throughout the storage period, th 30% treatment received low scores: the 40% treatment was especially disliked in terms of mashing of the product due to the excess water. Overall, for a soft and moderately chewy product, the optimum Baekbokryung powder and moisture level for Jeolpyuns were suggested as 3 to 5% ranges and 35% respectively. Ultimately, the results of this research will contribute to the possible commercialization of a Jeolpyuns product that contains added Baekbokryung.

• The Korean Journal of Ecology
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• 제15권4호
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• pp.377-386
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• 1992

Seasonal changes of symbiotic nitrogen-fixation activity and growth characteristics of four different natural populations of kummerowia striata were quantitatively analyzed during the growing period. the nitrogen-fixation activity of root nodules attained the maximum rates of 148, 132, 102 and 100$\muM\;C_2H_4\;\cdot\;g\;fw\;nodule^{-1}\;\cdot\;hr^{-1}$, respectively for sunny, multibranched, shade and unibranched populations at the optimum growth conditions. and the seasonal changes showed fluctuations by environmental conditions such as light, temperature, nutrient contents, water stress and plant ages, etc. The multibranched plant showed the greater amount of leaf and root nodule biomass, and the higher nitrogenase activity than the unibranched plant. the optimum conditions of leaf chloropht11 and water content of each organ indicated the active growth and the maximum fresh biomass of 4 different populations were 1.92, 1.85, 0.97 and 0.56 g $fw\cdotplant^{-1}$ for shade multibranched, sunny and unibranched populations, respectively.

• 한국식품영양과학회지
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• 제31권3호
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• pp.405-410
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• 2002

생전분 분해효소를 이용한 타피오카의 당화 및 알콜 병행복발효에 적합한 조건을 조사하였다. 그 결과 가수량 250% (v/w), 효소제 사용량 0.5%(w/w)를 사용하여 96시간 발효하였을 때 알콜 함량이 가장 높았다. 알콜발효 96시간째에 알콜함량 및 환원당은 11.7% 및 306mg%으로 각각 나타났다. pH 변화는 발효초기 pH 6.2에서 발효 후 pH 4.2 범위로 감소하였으며, 총산은 발효초기 0.11에서 0.43가지 증가하였으나 큰 변화는 없었다. 알콜성분은 ethanol, methanol, iso-propanol, n-proylalcohol, iso-butylalcohol 및 iso-amylalcohol이 분석되었으며 그외에 acetaldehyde가 확인되었다. 생전분분해효소제를 이용한 타피오카의 알콜발효 조건은 가수량250%, 효소제 0.5%로 설정할 수 있었다. 그러나 전반적인 발효수율은 증자방법에 비하여 낮게 나타났다.

• Macromolecular Research
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• 제16권7호
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• pp.596-603
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• 2008

To improve the mechanical properties, dimensional stability and blood compatibility, the biomedical material $Pellethene^{(R)}$ was blended with multiblock polyurethane (MPU) containing phospopholipid/long alkyl chain (C-18) at the various MPU contents and crosslinked using dicumyl peroxide as a crosslinking agent. The maximum MPU content for stable $Pellethene^{(R)}$/MPU blended films was approximately 30 wt%. The optimum crosslinking agent content and crosslinking time with respect to the mechanical properties were 4 wt% and 3 h, respectively. The mechanical properties (tensile strength and elongation at break) and water absorption of the crosslinked blend film increased with increasing MPU content. The test of platelet adhesion on the surfaces of the crosslinked blend film showed a decrease in the level of platelet adhesion from 70% to 6% with increasing MPU content from 0 to 30 wt%. These results suggest that the crosslinked $Pellethene^{(R)}$/MPU-30 (MPU content: 30 wt%) sample has strong potential as a novel material for blood compatible material applications.

• 한국주조공학회지
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• 제4권2호
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• pp.89-95
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• 1984

A Study on the Mechanical Properties of Molding Sand with Various Water/Clay Ratio A standard sample of molding sand was prepared by adding a various amount of bentonite, which has water/clay ratio from 0.4 to 0.6, into artificial sand, Hanyoung #6. The results obtained by measuring the room temperature properties of green mold are as follows. 1. This compressive strength of green molds which have 4% and 10% of bentonite decreased with increasing water/clay ratio, but the maximum strengths of 4.3 (psi) and 7.2 (psi) were observed in the samples with 6%, 8% bentonite respectively when the water/clay is 0.45. 2. The optimum water/clay ratio for strength and permeability increased from 0.4 to 0.5 with increasing clay. 3. The green compressive strength was proportional to the hardness. 4. Deformation increased with increasing water/clay ratio. 5. Flowability decreased with increasing water/clay ratio and clay content in molding sand.

• 한국작물학회지
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• 제62권2호
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• pp.134-142
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• 2017

Crop production in rice paddy fields is of great importance because of declining rice consumption and the low self-sufficiency ratio for field crops in Korea. A controlled drainage system (CDS) is recognized as an effective means to adjust water table (WT) levels as needed and control soil water content to improve the soil environment for optimum crop growth. The present study evaluated the effects of a CDS on soil characteristics, including soil water distribution and soybean development in paddy fields. The CDS was installed with two drain spacing (3 m and 6 m) at the experimental paddy field at the National Institute of Crop Science, Miryang, Korea. It was managed with two WT levels (0.3 m and 0.6 m) during the growing season. Soil water content, electrical conductivity and plant available nitrogen content in the soil were significantly greater in the 0.3 m WT management plots than in the 0.6 m plot and the control. At the vegetative stage, chlorophyll content was significantly lower with higher WT control because of excess soil moisture, but it recovered after the flowering stage. Soybean yield increased with WT management and the 0.6 m WT treatment produced the greatest grain yield, $3.38ton\;ha^{-1}$, which was 50% greater than that of the control. The CDS directly influenced outflow through the drains, which significantly delayed nutrient loss. The results of this study indicated that WT management by CDS can influence soil characteristics and it is an important practice for high yielding soybean production in paddy fields, which should be considered the crop growth stages for stable crop production.

• 한국식품영양과학회지
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• 제32권8호
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• pp.1270-1277
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• 2003

두유박과 옥분 혼합물의 압출성형물을 제조하기 위한 공정 조건의 위하여 스크류 속도 150∼250 rpm, 혼합물의 수분함량 20∼30%, 온도 100∼15$0^{\circ}C$의 조건에서 압출 성형하고, 반응표면분석법 (RSM)을 이용하여 최적 조건을 분석하였다. 공정 조건에 따른 팽화율에서는 스크류 속도가 높고 수분함량이 낮을수록 팽화가 크게 일어났고, 수분함량이 많을수록 용적 밀도를 높이는 것으로 나타났다. 절단강도의 경우 수분 함량에 따라 감소하다 증가하는 추세를 보여주었고, WSI는 스크류 속도와 수분함량에 WAI는 수분함량과 온도에 많은 영향을 받았다. 색도에서는 b＊ 값을 제외하고는 유의적인 차이를 보이지 않았다. 각 조건별 실험결과를 반응표면분석을 한 결과 팽화율과 용적 밀도, WSI, b＊ 값은 linear모델로 결정되었고, 절단강도와 WAI는 quadratic 모델이 유의성을 나타내었다. 압출 성형 공정의 최적화는 결정된 반응식과 반응표면 그래프를 이용한 결과 수치 최적화에서는 스크류 속도 250 rpm, 수분함량 22.43%, 온도 128.16$^{\circ}C$이었고, 모형적 최적화에서는 desirability가 0.727인 스크류 속도 250 rpm, 수분함량 22.43%, 온도 128.02$^{\circ}C$로 결정되었다.

• 한국식품영양학회지
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• 제13권2호
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• pp.152-157
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• 2000

In order to select the optimum drying method for the production of cinnamon extract, water extract and 70% ethanol extract of cinnamon were prepared. And then several drying method of oven drying, vacuum evaporation, spray drying and freeze drying were performed. Content of cinnamic acid, cinnamic aldehyde, eugenol, tannin and free sugar, and antioxidant activity, degree of browning, pH, color value, turbity and solubility were compared. In water extract, contents of cinnamic acid, cinnamic aldehyde, eugenol were 29.45mg/100g, 94.86mg/100g, 120.75mg/100g and decreased to 4.76%∼44.21%, 5.30%∼48.05%, 3.66%∼21.83% by oven dyring, vaccum drying, spray drying respectively, but freeze drying showed a little decrease of those components. In 70% ethanol extract, effectual components decreased to 76.05%∼88.38% and 26.86%∼78.76% by freeze drying and vacuum evaporation respectively. Antioxidant activity decreased by drying and decreasing rate in 70% ethanol extract was lower than water extract. Degree of browning increased as the drying temperature increased. Tannin and free sugars were little affected by drying temperature. Solubility decreased in oven drying and 70% ethanol extract. Overall data suggested that optimum drying methods of cinnamon extract were freeze drying in case of water extract and freeze drying and vaccum drying in case of 70% ethanol extract.

• Food Science and Biotechnology
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• 제18권4호
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• pp.985-990
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• 2009

Response surface methodology (RSM) was applied to determine the optimum drying conditions for pork jerky. The physicochemical properties of pork jerky, such as final moisture content, water activity (Aw), pH, and shear force were investigated. In addition, sensory characteristics of pork jerky were evaluated and were used as a parameter for determining the optimum condition. Pork jerky samples were dried at different temperatures between 40 to $80^{\circ}C$ for the time ranged from 0 to 10 hr. The predicted values for moisture content, Aw, and shear force of dried pork samples were in good agreement with the experimental values with correlation coefficients ($R^2$) of 0.95, 0.96, and 0.97, respectively. Both drying temperature and time significantly (p<0.01) affected moisture content, Aw, pH, and shear force and their interactions were also significant at p<0.01 except for Aw. RSM showed the optimum drying conditions for pork jerky, based on moisture content, shear force, and sensory evaluation to be oC$65-70^{\circ}C$ for 7-8 hr.