• International Journal of Industrial Entomology and Biomaterials
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• 제7권1호
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• pp.75-78
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• 2003

This study was carried out to investigate the mineral content of the feces of the $5^th$ instar larvae in a few silkworm species such as a parent domestic silkworm (Jam134), a hybrid (Kumok-jam), the Japanese oak silkworm, and the Chinese oak silkworm. The major minerals of all silkworms throughout all $5^th$ instar larval period are K, P, Mg and Ca, and the result is consistent with the previous study of the mineral content in the mulberry leaves. Although the calcium content decreased sharply at $7^th$ day of the $5^th$ instar, the crude protein content significantly increased at the same age in both domestic silkworms, suggesting a direct relationship between feeding behavior of the silkworms at the larval period and mineral/protein contents. However, this trend was not observed in both oak silkworms. In the comparison of the mineral content among silkworm species, two domestic silkworms were significantly higher in the calcium content compared with two oak silkworms, and the hybrid Kumok-jam was further higher significantly than the feces of parental Jam 143. Excluding the calcium content, overall no significant content variation in other minerals was observed among four silkworm species studied in this study.

• Asian-Australasian Journal of Animal Sciences
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• 제23권12호
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• pp.1594-1600
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• 2010

A study was conducted to determine the dietary effects of a clay mineral (sodium bentonite, NaB) on manure gas emission, health, production, and meat characteristics of Hanwoo steers. Two diets fed to steers included a control diet (concentrate mix and rice straw) and a treatment diet (control diet+1.0% clay mineral/concentrate mix). Dietary NaB addition considerably reduced concentrations of gases ($H_2S$, $SO_2$ and $NH_3$) in the manure of Hanwoo steers. Growing steers fed NaB had similar blood profiles with the exception of lower (p<0.05) concentrations of blood alkaline phosphatase and lactate dehydrogenase. Dietary NaB addition tended to increase (p = 0.10) live weight by 30 kg at slaughtering and did not affect carcass yield and quality traits. Dietary NaB addition increased concentrations of P (p<0.01), Mg (p<0.01), Na (p<0.01), Zn (p<0.005), K (p = 0.08), Fe (p = 0.08) and Cu (p = 0.07) in the longissimus muscle compared to the control but did not affect (p>0.05) fatty acid composition. The study demonstrated that the dietary addition of a clay mineral could be effective in improving mineral bioavailability to Hanwoo steers, which could be one of the reasons for their improved performance.

• 한국광물학회지
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• 제22권4호
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• pp.353-358
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• 2009

CRT 브라운관 패널의 연마과정에서 배출되는 폐연마슬러지로부터 석류석 등의 연마재를 회수하고, 연마성능을 평가하였다. 재활용 부석과 석류석으로 연마한 유리의 평균표면거칠기값(Ra = $0.025{\mu}m$, = $0.029{\mu}m$)은 새 연마재로 연마한 유리에서의 값(Ra = $0.039{\mu}m$, $0.031{\mu}m$)보다 작았으며 표면의 선이나 홈도 적었다. 루즈의 경우 유리 파편이 혼입되어 연마재로 재활용하기에는 적합하지 않다. 본 기술을 이용하여 폐연마슬러지에 함유된 천연연마재 광물자원인 부석과 석류석을 회수한다면 CRT 유리 연마공정에서 재활용할 수 있고, 슬러지 매립으로 발생되는 처리비용과 환경오염문제를 줄일 수 있을 것이다.

• 한국제4기학회지
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• 제21권1호
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• pp.27-36
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• 2007

90년대 이후 세계적으로 집중호우와 같은 자연재해에 문화재가 극심한 피해를 입고 있다. '05년도 문화재 보수건수는 '86년 건수 대비 거의 6배에 달하고, 특히 경상도와 전라도의 보수실적이 전국의 63%를 차지하였다. 이는 90년대 이후 발생한 태풍이 대개 남해안으로 상륙하여 북상하는 형태였고 경로에 해당하는 전남 및 경남 지역에 막대한 피해를 주었기 때문인 것으로 판단된다. 석조문화재 보수자료를 기반으로 현지조사를 거쳐 자연재해 발생 가능성이 높은 석조문화재를 예비 분석하였다. 이의 분포현황을 보면 토사재해와 사면 붕괴 등 사면과 관련된 재해가 58% 이상을 차지하였는데, 이는 석조문화재 중 사면에 분포하는 것이 59%로 다수를 차지하고 이들은 집중호우가 발생하면 산사태나 토사이동으로 인한 재해에 대해 매우 취약하기 때문이다. 집중호우 하에서는 산사면 표층수 또한 높은 에너지를 가지고 흐르면서 석조문화재 지반의 토양을 침식시킬 수 있다. 마애불과 같이 자연상태의 암석을 이용한 석조문화재 중, 전석상태의 것은 침식이나 지반침하 등의 지반변화에 매우 민감하게 반응하여 지반에 변화가 오면 기울음이나 전도 등의 피해를 볼 수 있다. 자연재해가 발생할 수 있는 석조문화재의 분포는 '90년대 이후의 5대 태풍의 전체 강우분포와 관련성이 보여 2등급 정도의 범주 안에 들어온다. 특히 태안반도와 경기의 일부 문화재는 전체 강우분포도 보다는 태풍올가 등의 강우분포와 관련성이 높은 것으로 판단된다.

• 공업화학
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• 제27권1호
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• pp.56-61
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• 2016

본 연구에서는 천연 광물질 촉매를 사용하여 $CO_2$ 석탄가스화의 반응특성을 조사하였다. Meng Tai지역의 갈탄에 4종류의 천연 광물질(Dolomite, Silica sand, Olivine, Kaolin)을 각각 5 wt%로 물리적으로 혼합한 후 Thermogravimetric Analyzer (TGA)를 이용하여 800, 850, $900^{\circ}C$에서 $CO_2$ 가스화 반응을 수행하였다. 실험 결과를 Volumetric Reaction Model (VRM), Shrinking Core Model (SCM), Modified Volumetric Reaction model (MVRM)을 이용하여 분석하였다. MVRM이 가장 적합하였다. 반응 온도가 올라감에 따라 반응속도상수가 커졌다. 천연 광물질 촉매를 사용할 경우가 촉매를 혼합하지 않은 경우에 비해 반응속도상수는 커지고 활성화 에너지 값이 낮아졌다. Silica sand를 혼합한 시료의 활성화 에너지 값은 114.90 kJ/mol로 가장 낮은 활성화 에너지 값을 보였다. Kaolin을 혼합한 시료의 경우 $850^{\circ}C$와 $900^{\circ}C$에서 각각 가장 높은 반응속도상수를 보여주다가 $800^{\circ}C$에서 낮은 반응속도상수를 나타냈다. 따라서 Kaolin을 혼합한 경우, 반응 온도가 높아질수록 $CO_2$ 가스화에 좋은 효과가 있을 것이다.

• Advanced Composite Materials
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• 제18권2호
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• pp.167-185
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• 2009

Environmental problems caused by extensive use of polymeric materials arise mainly due to lack of landfill space and depletion of finite natural resources of fossil raw materials like petroleum or natural gas. The substitution of synthetic petroleum-based resins with natural biodegradable resins appears to be one appropriate measure to remedy the above-mentioned situation. This study presents the development of a composite that uses environmentally degradable starch-based resin as matrix and natural mineral basalt fibres as reinforcement, and investigates the fibre's and the composite's mechanical properties. The tensile strength of single basalt fibres was verified by means of single fibre tensile tests and statistically investigated by means of a Weibull analysis. Prepreg sheets were manufactured by means of a modified doctor blade system and hot power press. The sheets were used to manufacture specimens with fibre volume contents ranging from 33% to 61%. Specimens were tested for tensile strength, flexural strength and interlaminar shear strength. Composites manufactured during this study exhibited tensile and flexural strength of up to 517 MPa and 157 MPa, respectively.

• 전기학회논문지
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• 제59권10호
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• pp.1832-1838
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• 2010

Aging of transformer insulating material in natural ester insulating oil is compared to that in conventional transformer oil. Aging of insulating paper and insulating oil have been studied by performing accelerated thermal aging test. Sealed aging test vessels containing cooper, laminated core, Kraft paper and insulating oil(natural oil or mineral oil) were aged at $140^{\circ}C$ for 500, 1000, 1500 and 2000 hours. Insulating oils after aging are investigated with total acid number, breakdown voltage and viscosity. Also, degradation of insulating paper after aging is determined using breakdown voltage and mechanical strength. Accelerated aging studies demonstrate a slower aging rate for natural ester insulating oil compared to the rate for conventional mineral oil.

• Ocean and Polar Research
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• 제36권4호
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• pp.423-435
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• 2014

Verifying the similarity of environmental characteristics between an artificial impact site and a preserved or reference site is necessary to quantitatively and qualitatively evaluate the environmental impact of mining activity. Although an impact site (BIS station) and a preserved site (called KOMO station) that have been selected in the Korea manganese nodule contract area may share similar environmental characteristics, similarities in terms of the water column environment between both sites has not been investigated. In this study, we compared the chemical properties of the water columns and sinking particle fluxes between BIS and KOMO stations through two observations (August 2011 and September 2012). Additionally, we observed particle fluxes at the KOMO station for five years (July 2003~July 2008) to understand long-term natural variability. Vertical distributions of water column properties such as dissolved oxygen, inorganic nutrients (N, P, Si), total organic carbon below surface layer (within the depth range of 200 m) were not considerably different between the two sites. Especially, values of water column parameters in the abyssopelagic zone from 4000 m to bottom layer (~5000 m) were very similar between the BIS and KOMO sites. Sinking particle fluxes from the two sites also showed similar seasonality. However, natural variation of particle flux at the KOMO site varied from 3.5 to $129.9mg\;m^{-2}day^{-1}$, with a distinct temporal variation originating from ENSO events (almost forty times higher than a minimum value). These results could provide valuable information to more exactly evaluate the environmental impact of mining activity on water columns.

• 생명과학회지
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• 제23권2호
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• pp.242-248
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• 2013

본 연구의 목적은 우수한 미생물 제제 개발용 인산염 가용화 균주의 개발이다. 경작지 토양에서 분리한 인산염 가용화 균주의 특성 및 16S rDNA 염기서열을 조사한 결과 Bacillus subtilis HR-1019로 동정되었다. Bacillus subtilis HR-1019는 hydroxyapatite, tri-calcium phosphate 및 aluminum phosphate 3가지의 난용성 인산염을 모두 가용화하였다. 난용성 인산염의 분해능이 최대가 되는 배양온도는 $37^{\circ}C$이었으며, 배양초기 pH가 5.0이었다. 탄소원으로 glucose를 5% 첨가시 가용화능이 높았으며, 가용화된 유리인산의 함량이 증가함에 따라 pH가 크게 감소하였다. 분리균주 HR-1019가 식물병원균에 대하여 균의 생육을 저지하는 clear zone 확인으로 항균효과를 확인하였다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제25권3호
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• pp.12-22
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• 2020

Managed aquifer recharge (MAR) is a promising water management strategy for securing stable water resources to overcome water shortage and water quality deterioration caused by global environmental changes. A MAR demonstration site was selected at Imgok-ri, Sangju-si, Korea, based on screening for the frequency of drought events and local water supply situations. The abundant groundwater discharging from a nearby abandoned coal mine is one of the potential recharge water sources for the MAR implementation. However, it has elevated levels of arsenic (~12 ㎍/L). In this study, the potential of the natural attenuation of arsenic by the field geological media was investigated using batch and column experiments. The adsorption and desorption parameters were obtained for two drill core samples (GM1; 21.8~22.8 m and GM2; 26.0~27.8 m depth) recovered from the potentially water-conducting fracture-zones in the injection well. The effluent arsenic concentrations were monitored during the continuous flow of the mine drainage water through the columns packed with the core samples. GM2 removed about 60% of arsenic in the influent (0.1 mg-As/L) while GM1 removed about 20%. The results suggest that natural attenuation is an acitive process occurring during the MAR operation, potentially lowering the arsenic level in the mine drainage water below the regulatory standard for drinking water. This study hence demonstrates that using the mine drainage water as the recharge water source is a viable option at the MAR demonstration site.