• 한국환경농학회지
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• 제28권2호
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• pp.165-170
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• 2009

환원상태가 발달된 담수상태의 토양이나 습지생태계에서 $NO_3^-$는 환원상태의 진전을 지연시키는 완충역할을 할 수 있다. 논토양에서 $NO_3^-$가 Fe의 환원과 그에 따른 P의 가용화에 미치는 영향을 조사하였다. 담수 후 10 cm 깊이 토양의 산화환원전위 변화는 $NO_3^-$를 처리한 토양과 처리하지 않은 토양에서 현저하게 달리 나타났으며, $NO_3^-$의 환원이 일어나는 동안에는 산화환원전위가 330${\sim}$360 mV 범위에서 유지되었다. 그리고 이 기간 동안 Fe의 환원은 현저히 억제되었다. $NO_3^-$를 처리한 토양 용액의 $PO_4^{3-}$ 함량은 담수 이후 0.2${\sim}$0.3 mg/L 수준 또는 그 이하로 유지되었으며, 반면 $NO_3^-$를 처리하지 않은 경우에는 담수 후 9일째부터 Fe의 환원과 함께 토양 용액의 $PO_4^{3-}$ 함량이 급격히 증가하였다. 일반적인 토양에서 무기태 P의 상당부분이 Fe 산화물에 고정된 형태 및 Fe와 결합된 형태로 존재하므로 Fe의 환원에 따라서 $PO_4^{3-}$가 함께 용출되는 것이다. 이상의 결과를 보면 토양중의 $NO_3^-$가 $Fe^{2+}$와 $PO_4^{3-}$의 용출을 조절하는 요인인 것으로 확인할 수 있다. 토양 용액중의 $NO_3^-$ 농도가 1 mg/L 이상으로 유지되는 상태에서는 토양의 산화환원전위가 330 mV 이하로 낮아지지 못하며, 따라서 Fe의 환원과 그에 따른 P의 용출 또한 현저히 억제되는 것으로 판단된다.

• Asian-Australasian Journal of Animal Sciences
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• 제32권5호
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• pp.637-647
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• 2019

Objective: The study aimed at quantifying seasonal and spatial variations in availability and nutritive value of herbaceous vegetation on native pastures and supplement feedstuffs for domestic ruminants in Western Kenya. Methods: Samples of herbaceous pasture vegetation (n = 75) and local supplement feedstuffs (n = 46) for cattle, sheep, and goats were collected in 20 villages of three geographic zones (Highlands, Mid-slopes, Lowlands) in Lower Nyando, Western Kenya, over four seasons of one year. Concentrations of dry matter (DM), crude ash (CA), ether extract (EE), crude protein (CP), neutral detergent fibre (NDF), gross energy (GE), and minerals were determined. Apparent total tract organic matter digestibility (dOM) was estimated from in vitro gas production and proximate nutrient concentrations or chemical composition alone using published prediction equations. Results: Nutrient, energy, and mineral concentrations were 52 to 168 g CA, 367 to 741 g NDF, 32 to 140 g CP, 6 to 45 g EE, 14.5 to 18.8 MJ GE, 7.0 to 54.2 g potassium, 0.01 to 0.47 g sodium, 136 to 1825 mg iron, and 0.07 to 0.52 mg selenium/kg DM. The dOM was 416 to 650 g/kg organic matter but differed depending on the estimation method. Nutritive value of pasture herbage was superior to most supplement feedstuffs, but its value strongly declined in the driest season. Biomass yields and concentrations of CP and potassium in pasture herbage were highest in the Highlands amongst the three zones. Conclusion: Availability and nutritive value of pasture herbage and supplement feedstuffs greatly vary between seasons and geographical zones, suggesting need for season- and region-specific feeding strategies. Local supplement feedstuffs partly compensate for nutritional deficiencies. However, equations to accurately predict dOM and improved knowledge on nutritional characteristics of tropical ruminant feedstuffs are needed to enhance livestock production in this and similar environments.

• Journal of the korean society of oceanography
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• 제34권1호
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• pp.49-57
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• 1999

A red tide organism, Amphidinium carterae was incubated under different iron/chelator and nitrate concentrations to investigate the factors controlling the growth. The chelation capacity played a critical role in regulating the nitrate reductase (NR) activity and in vivo fluorescence of this organism. However, there was a significant difference between the NR activity and in vivo fluorescence in response to trace metals and chelator treatments. In vivo fluorescence was the highest in FeEDTA 10 ${\mu}$M treatments and the lowest in DTPA 10 ${\mu}$M treatments. This indicates that the availability of the trace metal is important in regulating the in vivo fluorescence of this photosynthetic microalgae In contrast, NR activity showed the highest values in trace metal enriched treatments, and trace metal + DTPA treatments showed fairly high NR activities. This suggests that DTPA treatment did not hinder the NR activity as much as it did in vivo fluorescence. In vivo fluorescence and NR activity increased with nitrate concentration of up to 50 ${\mu}$M and remained relatively constant or the rate of increase decreased above that concentration, indicating that initial nitrate concentration of higher than a certain level would not accelerate the growth of A. carterae. Further investigation is needed to elucidate the reason for the difference in timing sequence between the NR and in vivo fluorescence in response to different metal treatments and chelation capacity.

• 한국환경농학회지
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• 제33권1호
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• pp.1-8
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• 2014

BACKGROUND: Recent studies using many amendments for heavy metal stabilization in soil were conducted in order to find out new materials. But, the studies accounting for the use of appropriate amendments considering soil pH remain incomplete. The aim of this study was to investigate the effects of initial soil pH on the efficiency of various amendments. METHODS AND RESULTS: Acid soil and alkali soil contaminated with heavy metals were collected from the agricultural soils affected by the abandoned mine sites nearby. Three different types of amendments were selected with hypothesis being different in stabilization mechanisms; organic matter, lime stone and iron, and added with different combination. For determining the changes in the extractable heavy metals, water soluble, Mehlich-3, Toxicity Characteristic Leaching Procedure, Simple Bioavailability Extraction Test method were applied as chemical assessments for metal stabilization. For biological assessments, soil respiration and root elongation of bok choy (Brassica campestris ssp. Chinensis Jusl.) were determined. CONCLUSION: It was revealed that lime stone reduced heavy metal mobility in acid soil by increasing soil pH and iron was good at stabilizing heavy metals by supplying adsorption sites in alkali soil. Organic matter was a good source in terms of supplying nutrients, but it was concerning when accounting for increasing metal availability.

• 한국지하수토양환경학회지:지하수토양환경
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• 제19권1호
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• pp.54-62
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• 2014

To better understand dissimilatory iron and sulfate reduction (DIR and DSR) by subsurface microorganisms, we investigated the effects of sulfate and electron donors on the microbial goethite (${\alpha}$-FeOOH) reduction. Batch systems were created 1) with acetate or glucose (donor), 2) with goethite and sulfate (acceptor), and 3) with aquifer sediment (microbial source). With 0.2 mM sulfate, goethite reduction coupled with acetate oxidation was limited. However, with 10 mM sulfate, 8 mM goethite reduction occurred with complete sulfate reduction and x-ray absorption fine-structure analysis indicated the formation of iron sulfide. This suggests that goethite reduction was due to the sulfide species produced by DSR bacteria rather than direct microbial reaction by DIR bacteria. Both acetate and glucose promoted goethite reduction. The rate of goethite reduction was faster with glucose, while the extent of goethite reduction was higher with acetate. Sulfate reduction (10 mM) occurred only with acetate. The results suggest that glucose-fermenting bacteria rapidly stimulated goethite reduction, but acetate-oxidizing DSR bacteria reduced goethite indirectly by producing sulfides. This study suggests that the availability of specific electron donor and sulfate significantly influence microbial community activities as well as goethite transformation, which should be considered for the bioremediation of contaminated environments.

• 한국환경과학회지
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• 제31권1호
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• pp.77-85
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• 2022

Environmental contamination by organic compounds are not only restricted to water, but extends to soil and groundwater as well. However, highly oxidized compounds, such as halogenated organics and nitro-compounds, can be detoxified employing reducing methods. Permeable reactive barrier is one of the representative technologies where zero-valent metals (ZVMs) are employed for groundwater remediation. However, organics contaminates often contaminate the unsaturated zone above the groundwater. Despite the availability of technologies like soil vapor extraction and bioremediation, removing organic compounds from this zone represents several challenges. In this study, the reduction of nitrobenzene to aniline was achieved using zero-valent iron (ZVI) under unsaturated conditions. Results indicated that the water content was an important variable in this reaction. Under dry conditions (water content = 0.2%), the reduction reaction was inhibited; however, when the water content was between 10% and 25% (saturated condition), ZVI can reduce nitrobenzene. Palladized iron (Pd/Fe) can be used to reduce nitrobenzene when the water content is between 2.5% and 10%. The reaction was evaluated over a wide range of temperatures (10 - 40 ℃), and the results indicated that increasing the temperature resulted in increased reaction rates under unsaturated conditions.

• 한국정밀공학회지
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• 제20권5호
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• pp.225-231
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• 2003

The injection molding is a traditional manufacturing method that can make plastic parts by just one time in mold. Therefore, the injection molding has become one of a manufacturing method, which is widely applied in a producing of plastic products. Nowadays, to use of plastic parts has increased and plastic product-model using term has been shorten. By these reasons, using term of a injection mold has fast been reduced. These produced molds will be disused and leaved in a storage after a regular term to use it. These leaved molds are sometime sold as scrap iron. But, these molds have lots parts for recycling except special parts for example, cavities, cores and eject pins, etc. In this research, we investigated when the cavity and core of in injection mold would be changed, the injection mold could be recycled. We suggested the structures and standardizations for recycling of a moldbase. We also developed a program in which can be used when the recycling moldbase design in the Auto-CAD with the recycling standards. We called this program as the Recy-Mold. For the availability of the program and moldbase structure fur the recycling standards, we experimented a used mold for automobile lens, which was remanufactured by the recycling standard. The results of this test showed feasibility for the recycling mold.

• Membrane and Water Treatment
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• 제13권2호
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• pp.97-104
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• 2022

With a small particle size, specific surface area and chemical nature, Pd/Cu-Fe nanocomposites can efficiently remove the organic compounds. In order to understand the applicability for in situ remediation of contaminated groundwater, the degradation of p-nitrophenol by Pd/Cu-Fe nanoparticles was investigated. The degradation results demonstrated that these nanoparticles could effectively degrade p-nitrophenol and near 90% of degradation efficiency was achieved by Pd/Cu-Fe nanocomposites for 120 min treatment. The efficiency of degradation increased significantly when the Pd content increased from 0.05 wt.% and 0.10 wt.% to 0.20 wt.%. Meanwhile, the removal percentage of p-nitrophenol increased from 75.4% and 81.7% to 89.2% within 120 min. Studies on the kinetics of p-nitrophenol that reacts with Pd/Cu-Fe nanocomposites implied that their behaviors followed the pseudo-first-order kinetics. Furthermore, the batch experiment data suggested that some factors, including Pd/Cu-Fe availability, temperature, pH, different ions (SO42-, PO43-, NO3-) and humic acid content in water, also have significant impacts on p-nitrophenol degradation efficiency. The recyclability of the material was evaluated. The results showed that the Pd/Cu-Fe nanoparticles have good recycle performance, and after three cycles, the removal rate of p-nitrophenol is still more than 83%.

• Asian-Australasian Journal of Animal Sciences
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• 제23권8호
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• pp.1028-1033
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• 2010

The effects of delta-aminolevulinic acid (DALA) or chito-oligosaccharide (COS) in layer diets on production performance, egg quality and hematological characteristics were investigated in this 8-week trial. Two hundred and seventy 27-week-old (Hy-Line brown) layers were randomly assigned to 5 treatments with 9 replications per treatment. Dietary treatments were i) Control (basal diet); ii) DALA1 (basal diet+DALA 2 mg/kg); iii) DALA2 (basal diet+DALA 4 mg/kg); iv) COS1 (basal diet+COS 100 mg/kg) and v) COS2 (basal diet+COS 200 mg/kg). In this study, no significant difference was observed in feed intake and egg shell quality (eggshell breaking strength and egg shell thickness) among treatments. The inclusion of DALA increased egg production during the first 4 weeks. Egg weight was increased in both DALA (quadratic, p<0.05) and COS (linear, p<0.05) treatments compared with the control treatment. Laying hens fed the DALA treatment had an increased yolk color unit (quadratic, p<0.05) and haugh unit (linear, p<0.05) compared with the control group. Similarly, these characteristics were also affected by COS treatments, with both values being linearly increased (p<0.05) in COS treatments compared with the control treatment. Additionally, birds fed DALA treatments significantly increased (quadratic, p<0.05) the number of RBC, WBC and lymphocytes compared with the control treatment. Dietary DALA supplementation linearly increased (p<0.05) the serum iron concentration at the end of the 8th week. The inclusion of COS increased (linear, p<0.05) the concentration of RBC, WBC and lymphocytes compared with the control treatment. In conclusion, dietary DALA at the lower dosage (2 mg/kg) could exert better effects in laying hens than higher dosage (4 mg/kg). Birds fed DALA supplemented diet had an increased iron availability, egg weight, eggshell quality and immunity. Moreover, the inclusion of COS (200 mg/kg) can increase egg weight, eggshell quality and immunity in laying hens. Therefore, both the utilization of COS and DALA could be considered as a new strategy for optimizing egg quality and health condition of laying hens.

• Journal of Yeungnam Medical Science
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• 제10권1호
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• pp.58-67
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• 1993

1986년 5월부터 1991년 6월까지 약 5년간 영남대학교 외과대학 부속병원에 내원하여 혈액학적 소견상 빈혈이 동반된 환자 210명과 정상인 200명 도합 410명을 대상으로 Coulter Counter S-plus II로 일반혈액검사를 실시하여 MCV와 RDW 및 여러 적혈구 지수를 얻어서 빈혈의 새로운 분류를 시도하였고 외국인에 비하여 빈혈의 병인 양상이 다른 한국인의 혈액질환의 감별진단에 도움이 되는 가를 알아 보고자 본 연구를 시행하였다. 거의 모든 경우에 MCV의 증감은 MCH와 MCHC의 증감을 동반하였으나 RDW와는 무관하였다. 따라서 저색소성빈혈 혹은 정색소성빈혈등의 용어보다는 이질성빈혈 혹은 동질성빈혈의 용어를 사용함이 빈혈의 형태학적 분류에 더욱 의미있는 것으로 사료되었다. 이질성소구성빈혈에는 철결핍성빈혈이 속하였고 이질성정구성빈혈에는 급성백혈병과 골수로성빈혈이 여기에 속하였으며 이질성대구성빈혈에는 거대적아구성빈혈과 용혈성빈혈이 속하였다. 동질성소구성빈혈에는 만성질환에 의한 빈혈이 여기에 속하였으며 동질성정구성빈혈에는 급성출혈, 만성백혈병 및 다발성 골수종등에 의한 빈혈이 여기에 속하고 동질성대구성빈혈에는 재생활량성빈혈이 여기에 속하였다. 진단적인 의의가 큰 혈색소병은 본 연구에는 관찰되지 않았지만 한국인에 가장 많은 빈혈의 원인인 철결핍성빈혈과 만성질환에 의한 빈혈의 감별진단에 RDW가 유용한 것으로 생각되었다.