• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.859-863
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• 2008

축산폐수, 침출수 등의 고농도 폐수를 생물학적으로 처리할 경우 최종 방류수는 강한 색도를 띠며 고분자량의 유기물질을 다량 함유한다. 이는 생물학적으로 분해하기 어려운 유기성 복합체와 생화학적 반응에 의한 중간생성물로 색도를 띠는 천연유기물질(NOM)을 포함한다. 생물학적 처리수의 색도는 심미적인 불안감, 방류수역의 수질오염 및 공중보건상의 잠재적 위해성을 갖는다. 또한, 수자원 이용측면에서 정수처리공정에서의 약품투입량 증가와 특히, 소독부산물 생성이라는 잠재적 문제점이 뒤따른다. 따라서 이러한 문제점을 해소하기 위한 생물학적 2차 처리수의 후속처리가 요구되며, 실제로 난분해성 유기물과 색도를 제거하기 위한 흡착, 막 분리, 고급산화(AOP) 및 화학적 응집 등의 물리-화학적 공정에 대한 연구가 수행되어왔다. 특히, 화학적 응집은 무기응집제 또는 고분자중합체(Polymer)를 이용하여 콜로이드성 입자와 색도를 띠는 난분해성 유기물을 전기적 불안정화를 유도함으로서 흡착 및 응집과정을 통해 제거하는 공정으로 많은 연구자들에 의해 연구되어왔다. 그러나 난분해성 유기물과 색도제거는 대상원수의 성상과 화학적 특성 등에 따라 각각의 제거효율과 최적 운전조건이 상이하게 나타난다. 화학적 응집공정은 비교적 높은 제거효율을 보이지만, 운전 및 유지관리의 기술적 어려움, 경제적 비효율성 등으로 인하여 적용에 어려움을 겪고 있는 실정이다. 본 논문에서는 생물학적 혐기-호기성 공정에서 방류되는 축산폐수의 2차 처리수를 대상으로 화학적 응집에 의한 색도 및 난분해성 유기물의 제거거동을 고찰하였다. 대상 처리수의 $TCOD_{Cr}$ 농도는 평균 410 mg/L인 반면, $BOD_5$는 7-15 mg/L 범위로 난분해성 유기물을 다량 함유하고 있음을 알 수 있었다. 이에 황산알루미늄(Aluminium sulfate; $Al_2(SO_4){\cdot}14H_2O$)과 염화철(ferric chloride)의 무기응집제를 이용하여 자 테스트(jar test)를 수행한 결과, 동일한 응집제 주입량에서 염화철의 유기물 제거 효율이 높은 것으로 나타났다. 황산알루미늄과 염화철의 경우 각각의 응집제 주입율 5.85mM에서 89%, 7.03mM에서 97.5%의 최대 유기물 제거효율을 보여주었으며, 이 때 최종 pH는 4.0-5.6 범위이었다. 한편, 대상 원수 내의 콜로이드성 입자 또는 용존성 유기물의 작용기(functional group)는 일반적으로 음으로 하전 되어 있어 응집에 의해 잘 제거되지 않는 특성을 가지고 있다. 따라서 과량의 응집제를 주입하여 다가의 양이온성 금속염을 흡착시켜 전기적으로 중화시키고, 생성된 침전성 수화물 내에 포획 또는 여과시켜 제거하게 된다. 이 때, 금속염 수화종의 전하밀도가 응집효율에 영향을 주는 것으로 알려져 있는데, 다가의 양이온은 전기적 이중층(Double layer) 압축에 의한 불안정화를 향상시킬 수 있기 때문에다. 또한, 2가 금속염은 색도유발물질과 흡착하여 humate 또는 fulvate 등의 착화합물(complex)을 형성시켜 응집효율을 향상시킬 수 있다. 따라서 본 연구에서는 생물학적 2차 처리수의 화학적 응집처리에 있어서 알루미늄염 등의 다가이온 첨가가 응집에 미치는 영향을 관찰하고, 후속되는 플록형성 및 침전공정에 의한 제거효율을 비교, 평가함으로써 2차 처리수로부터 난분해성 유기물과 색도를 보다 효과적이고 경제적으로 제거할 수 있는 최적인자를 도출하고자 하였다.

• Journal of Sensor Science and Technology
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• v.10 no.5
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• pp.292-303
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• 2001

This work reports the tunneling effects of the lateral field emitters. Tunneling effect is applicable to the VMFS(vacuum magnetic field sensors). VMFS uses the fact that the trajectory of the emitted electrons are curved by the magnetic field due to Lorentz force. Polysilicon was used as field emitters and anode materials. Thickness of the emitter and the anode were $2\;{\mu}m$, respectively. PSG(phospho-silicate-glass) was used as a sacrificial layer and it was etched by HF at a releasing step. Cantilevers were doped with $POCl_3(10^{20}cm^{-3})$. $2{\mu}m$-thick cantilevers were fabricated onto PSG($2{\mu}m$-thick). Sublimation drying method was used at releasing step to avoid stiction. Then, device was vacuum sealed. Device was fixed to a sodalime-glass #1 with silver paste and it was wire bonded. Glass #1 has a predefined hole and a sputtered silicon-film at backside. The front-side of the device was sealed with sodalime-glass #2 using the glass frit. After getter insertion via the hole, backside of the glass #1 was bonded electrostatically with the sodalime-glass #3 at $10^{-6}\;torr$. After sealing, getter was activated. Sealing was successful to operate the tunneling device. The packaged VMFS showed very small reduced emission current compared with the chamber test prior to sealing. The emission currents were changed when the magnetic field was induced. The sensitivity of the device was about 3%/T at about 1 Tesla magnetic field.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2003.10a
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• pp.15-15
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• 2003

치과재료에 사용되는 금속재료는 주로 스테인리스강, 타이타늄, Ni-Ti, Co-Cr등과 같은 특수합금이 주로 사용되고 있다. 이들 재료는 치과 보철물과 교정재료 및 충전재료로 주로 사용되고 있으며 그 외 치과에서 사용되는 기기나 기구에도 많이 활용되고 있다. 특히 치과 보철물을 사용하여 치료를 원하는 환자가 최근에 급격히 증가하면서 임플란트 고정체와 나사 등을 이용한 치료법의 연구와 개발이 필요하게 되어 세계적으로 연구와 투자가 활발히 진행되고 있다. 그러나 재료의 설계나 합금의 설계 및 제품의 설계상의 문제로 인하여 생체조직과 결합하는데 많은 문제점이 임상적으로 발생되고 있다. 즉 임플란트 표면의 생체적합성부여, 고정체와의 결합시 파절이나 풀림현상, 골에 고정체로 사용하는 나사의 강도와 내마모성문제 등이 개선되어야 할 문제점으로 남아있다. 또한 총의치에 사용되는 자석 어태치먼트의erosion-corrosion문제, 교정선의 탄성 과 마모저항문제 등은 앞으로 계속적인 연구를 행하여야할 과제로 남아있다. 또한 국소의치에서 사용되는 frame은 정밀주조법을 통하여 제조하며 주조상의 결함 등으로 인한 클라스프의 파절 문제점이 발생되고 있다. 따라서 본 연구에서는 치과재료로 사용되는 임플란트 고정체, 나사, 교정용 선등의 문제점을 고찰하고, 지금까지 이루어진 연구를 중심으로 최적의 개선 조건을 찾고자하였다. 최근첨단소재 및 금속재료를 사용하여 치과재료 합금을 설계할 수 있는 연구가 활발히 진행된다면 수입에 의존하고 있는 고가의 치과재료를 값이 싼 고성능의 제품으로 대체할 수 있는 효과가 클 것으로 생각된다.>$\rho$$\sub$0/=1.8 %. As t$\sub$Co/ increases, a transition from the regime of co-existence of superparamagnetic and ferromagnetic behaviors to ferromagnetic behavior was observed. Tunneling barrier called "decay length for tunneling" for the films having the thickness of Co layer from 1.4 to 1.6 nm was measured to be ranged from 0.004 to 0.021 ${\AA}$$\^$-1/.문에 기업간 관계를 연구하는 측면에서는 탐험적 연구성격이 강하다. 더 나아가 본 산업의 주된 연구가 질적이고 기업내부만을 연구했던 것에 비교하면 시초적이라고 할 수 있다. 또한 관계마케팅, CRM 등의 이론적 배경이 되고 있는 신뢰와 결속의 중요성이 재확인하는 결과도 의의라고 할 수 있다. 그리고 신뢰는 양사 간의 상호관계에서 조성될 수 있는 특성을 가진 반면, 결속은 계약관계 초기단계에서 성문화하고 규정화 할 수 있는 변수의 성격이 강하다고 할 수가 있다. 본 연구는 복잡한 기업간 관계를 지나치게 협력적 측면에서만 규명했기 때문에 많은 측면을 간과할 가능성이 있다. 또한 방법론적으로 일방향의 시각만을 고려했고, 횡단적 조사를 통하고 국내의 한 서비스제공업체와 관련이 있는 컨텐츠 공급파트너

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.5
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• pp.684-691
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• 2010

The present study was conducted to evaluate the effect of resistant starch (RS) on the large bowel function and plasma lipids in rats with constipation induced by Loperamide. Animals were divided into six groups: normal control-5% cellulose, constipation-5% cellulose, constipation-5% pectin, constipation-5% RS-type 2 (RS2), constipation-8% RS2 and constipation-5% RS type 3 (RS3) groups, and fed experimental diets for five weeks. The results from RS groups were compared with those from other dietary fiber groups. The groups supplemented with RS3 or high level of RS2 showed significantly increased counts of bifidobacteria in the cecum than the other groups. The production of total short chain fatty acids in the cecal contents was significantly high in pectin, RS3 and high RS2 groups. The pH in the cecal contents of the RS supplemented groups was significantly decreased compared with the cellulose supplemented groups. The production of prostaglandin E2 in the colon mucus of the RS groups was higher than the normal group; however, it was significantly decreased compared to the cellulose or pectin supplemented constipated groups. The thickness of the mucus layer and the production of mucus from epithelial cells were significantly increased in RS3 group compared to the constipated cellulose group. Supplementation of resistant starch significantly elevated the ratio of HDL-cholesterol to total cholesterol and significantly lowered plasma atherogenic index compared with cellulose or pectin supplementation in constipated rats. The results of the present study demonstrated that resistant starch supplementation may help in improving the large bowel environment by stimulation of bifidobacterial proliferation, reduction of pH and inflammation factor and by increased production of mucus. It has also been found that an additional health benefit is improvement in lipid levels of serum.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.6 no.2
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• pp.81-92
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• 2001

According to analyses of high-resolution seismic profiles (air gun, sparker, and SBP) and a deep-drill core(YSDP 105) in the mid-eastern Yellow Sea, stratigraphic and geoacoustic models have been established and seismo-acoustic modeling has been fulfilled using ray tracing of finite element method. Stratigraphic model reflects seismo-, litho-, and chrono-stratigraphic sequences formed under a significant influence of Quaternary glacio-eustatic sea-level fluctuations. Each sequence consists of terrestrial to very-shallow-marine coarse-grained lowstand systems tract and tidal fine-grained transgressive to highstand systems tract. Based on mean grain-size data (121 samples) of the drill core, bulk density and P-wave velocity of depositional units have been inferred and extrapolated down to a depth of the recovery using the Hamilton's regression equations. As goo-acoustic parameters, the 121 pairs of bulk density and P-wave velocity have been averaged on each unit of the stratigraphic model. As a result of computer ray-tracing simulation of the subsurface strata, we have found that there are complex ray paths and many acoustic-shadow zones owing to the presence of irregular layer boundaries and low-velocity layers.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.5 no.3
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• pp.224-232
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• 2000

Inorganic nutrient concentrations in relation to springtime physical parameters of the Yellow Sea were investigated during April 1996. Three major water masses, i.e., the Yellow Sea Warm Current Water (YSWC), Coastal Current Water (CCW) and Changjiang River Diluted Water (CRDW), prevailed in the study area. Water masses were vertically wel1 mixed throughout the study area, and nutrients were supplied adequately from bottom to surface layer. As result of ample nutrients supplied by vertical mixing together with progressed daylight condition, springtime phytoplankton blooms were observed, which was responsible for the depletion of inorganic nutrients in surface water column. Low nutrients concentration in bottom water of the central Yellow Sea (Stn. D9; nitrate: <2 ${\mu}$M, phosphate: <0.3 ${\mu}$) was associated with the entrance of YSWC which is characterized by high temperature and salinity. Influenced by runoff and vertical tidal mixing, CCW with high nutrient concentrations probably associated with China and Korea coastal waters with high nutrients concentration. For the local scale of inorganic nutrient distribution, nutrient transfers from coast to central areas were limited due to restriction imposed by tidal fronts (Stn. D6) and thus affected the horizontal nutrient profiles. Relatively high phytoplankton biomass was observed in the tidal front (Chl-${\alpha}$=12.38 ${\mu}$gL$^{-1}$) during the study period. Overall, the springtime nutrient distribution patterns in the Yellow Sea appeared to be affected by: (1) Large-scale influx of YSWC with low nutrient concentrations and CCW with high nutrient concentrations influenced by Korea and China coastal waters; (2) vertical mixing of water mass and phytoplankton distribution; and (3) local-scale tidal front as well as phytoplankton blooms alongthe tidal front.

• Korean Journal of Environmental Agriculture
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• v.23 no.1
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• pp.15-21
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• 2004

Objectives of this study were to monitor the distribution of heavy metals, to compare extractable heavy metal with total content and to investigate the relationships between soil physico-chemical properties and heavy metals in orchard soil. Sampling sites were 48 in Gyeonggi, 36 in Gangwon, 36 in Chungbuk, and 44 in Chungnam, Soils were collected farm form two depths, 0 to 20 and 20 to 40 cm (here after referred to as upper and lower layers) from March to May in 1998. Total contents of heavy metal in soils were analyzed by ICP-OES after acid digestion ($HNO_3$:HCl:$H_2O_2$) whereas extractable contents were measured after successive extraction of 0.1N-HCl, 0.05 M-EDTA, and 0.005 M-DTPA. Mercury was analysed by mercury atomizer. The average contents of Cd Cu, and Pb in the extractant with 0.1N-HCl at upper layer were 0.080, 4.23, and 3.42 mg/kg, respectively. As content in the extractant with 1N-HCl was 0.44 mg/kg, and total contents of Zn, Ni and Hg were 78.9, 16.1, and 0.052 mg/kg, respectively. The ratios of concentrations of heavy metals to threshold values (Cd 1.5, Cu 50, Pb 100, Zn 300, Ni 40, Hg 4 mg/ke in Soil Environmental Conservation Act in Korea (2001) were low in the range of $1/2.5{\sim}1/76.9$ in orchard soils. The ratios of extractable heavy metal to total content ranged $5.4{\sim}9.21%$ for Cd, $27.9{\sim}47.8%$ for Cu, $12.6{\sim}21.8$% for Pb, $15.8{\sim}20.3%$ for Zn, $5.3{\sim}6.3%$ for Ni, and $0.7{\sim}3.6%$ for Zn, respectively. Cu and Pb contents in 0.05 M-EDTA extractable solution were higher than those in the other extractable solution. Total contents of Cd, Ni and Ni in soils were negatively correlated with sand content but positively correlated with silt and clay contents. Ratios of extractable heavy metal to total content were negatively correlated with clay content but ai and Ni contents were positively correlated with soil pH, organic matter, and available phosphorous. Therefore, the orchard soil was safe because the heavy metal contents of orchard soil were very low as compared to its threshold value in the Soil Environmental Conservation Act. However, it need to consider the input of agricultural materials to the agricultural land for farming practices for assessment of heavy metals.