• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 봄 학술발표회 논문집
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• pp.483-490
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• 2002

A massive amount of marine clay produced as dredging of coast and sea bed is often dumped in open sea and filled in pond. The treatment of marine clay demand a large area and make fatal environmental problems for echo system. This research work intend to manufacture a light-weight landfill materials which are produced by mixing the dredged marine clay with various amount cement and foam. An extensive Uniaxial and Triaxial compression test are carried out to investigate the strength characteristics of the light-weight cement mixed marine clay with foam under various test conditions. The results indicated that the required unit weight has been achieved with negligible change after 28days curing time in water. It is also recognized that the compressive strength of light-weight landfill materials linearly decrease with increasing initial water content, and the rate of strength decrease with increasing initial water content in water curing was smaller than that of air curing Futhermore, the rate of strength decreased with increasing initial water content, however, the rate become smaller as cement content increased.

• 한국환경보건학회지
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• 제22권3호
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• pp.28-36
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• 1996

The objects of this study were to investigate emissions of air pollutant the particles as well as the combustibility of the low grade domestic anthracite coal and imported high-calorific bituminous coal in the fluidized bed coal combustor. The production of air pollution from anthracite-bituminous coal blend combustion in a fluidized bed coal combustor was evaluated. The effects of air velocity and anthracite fraction on the reaching time of steady state condition was also evaluated. We used coal samples the domestic low grade anthracite coal with heating value of 2,010 kcal/kg and the imported high grade bituminous coal with heating value of 6,520 kcal/kg. The experimental results are presented as follows. The time of reaching to steady state was affected by the temperature variation. The steady state time was about 120 minute at 0.3 m/s which was the fastest. It has been found that $O_2$ and $CO_2$ concentration were reached steady state at about 100 minute. As the height of fluidized bed becomes higher, the concentration s of $SO_2$ and $NO_x$ mainly increased. The concentration of freeboard was the highest and emission concentration was diminished. Also, as anthracite fraction increased, the emission of $SO_x$ concentration was increased. But, it has been found that the variation of $NO_x$ concentration with anthracite fraction was negligible and the difference of emission concentration according to air flow rates was negligible, too. It has been found that $O_2$ concentration decreased and $CO_2$ concentration increased as the height of fluidized bed increased. As anthracite fraction increased, the mass of elutriation particles increased, and $CO_2$ concentration decreased. Also, as air velocity increased, $O_2$ concentration decreased and $CO_2$ concentration increased. Regardless-of anthracite fraction and flow rate, the combustible weight percentage in elutriation particles were high in the case of fine particles.

• Journal of the Korean Wood Science and Technology
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• 제34권6호
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• pp.36-43
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• 2006

유동형 급속열분해기 (fluidized bed type fast pyrolyzer, 용량 400 g/h)를 이용하여 너도밤나무와 침엽수 혼합재(독일가문비나무/전나무, 50:50) 에서 바이오오일을 생산하였다. 목질바이오매스의 열분해는 약 $470{\pm}5^{\circ}C$에서 1~2초 동안 진행되었다. 목질바이오매스의 열분해 생성물의 조성은 너도밤나무의 경우 바이오오일 60%, 탄 9% 그리고 가스가 31% 정도 생산되었으며, 침엽수 혼합재는 바이오일 49%, 탄 9%, 그리고 42% 가량의 가스가 생성되었다. 두 종류의 목질바이오매스에서 생산된 바이오오일의 수분함량은 약 17~22%이었으며, 밀도는 수종에 관계없이 $1.2kg/{\ell}$이었다. 바이오오일의 원소 조성은 탄소 45%, 산소 47%, 수소 7%, 그리고 질소 1%로 일반적인 목질바이오매스와 큰 차이는 없는 것으로 나타났다. 그러나 화석자원에서 생산되는 오일류와 비교하여 바이오일은 산소함량이 매우 높았고 황은 전혀 포함되어 있지 않았다. 바이오오일의 GC 분석 결과 총 90여종의 방향족(aromatic) 또는 비방향족(non-aromatic) 저분자량 화합물이 검출되었으며 이들의 함량은 바이오오일 전건중량의 31~33%로 분석되었다.

• 한국방재학회 논문집
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• 제10권6호
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• pp.165-174
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• 2010

블록 TTG를 이용한 교각국부세굴보호공의 적합성과 유효성을 확인하기 위해 수리모형실험을 통해 모형 블록의 조도계수를 확인하고 안전성을 검토하였다. 현장조건을 대표하는 수리학적 조건하에서 개별 블록과 블록을 연결하여 매트화한 경우의 한계 안전중량을 결정하였다. 사석, 돌망태, TTG의 세굴보수공 성능을 비교한 결과 TTG의 안전성이 가장 우수하였다. 하상재료의 유출을 막기 위해 블록의 중간 부분을 적정한 자갈로 채우고, 토목섬유의 설치 여부를 검토하여야 한다.

• 공업화학
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• 제8권3호
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• pp.517-523
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• 1997

본 연구는 유동층연소로에서 유,무연탄 혼합연소시 대기오염물질 발생과 연소효율에 관하여 실험하였으며, 실험결과는 다음과 같다. 유동층연소로 높이가 증가할수록 이산화황과 질소산화물의 농도는 증가하는 것으로 나타났으며, 무연탄 혼합비가 증가할수록 이산화황의 농도는 증가하였으나 질소산화물농도는 큰 변화가 없었다. 무연탄 혼합비가 증가할수록 비산유출율도 증가하였고 주입 가연성분에 대한 유출 가연성분비도 증가하였다. 또한, 무연탄 혼합비에 관계없이 비산유출입자의 평균입경에 따른 미연분 함량은 미세입자에서 대체로 높게 나타났다. 한편, 연소효율은 층온도 $850^{\circ}C$, 과잉공기 20% 이상에서 큰 차이를 보이지 않았으므로 유속 0.3m/s, 층온도 $850^{\circ}C$, 과잉공기비 20%의 조건으로 혼합연소시키는 것이 적절한 것으로 나타났다.

• 대한장애인치과학회지
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• 제7권1호
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• pp.38-43
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• 2011

Treatment of the mandibular fracture consists of reduction and fixation. Primary wire & Arch bar are perhaps the ideal method for intermaxillary fixation. But, daily feeding, swallowing, speech, and in some instances, respiration is difficult to maintain during the period of intermaxillary fixation, owing to muscle weakness, emotional disorder and poor oral hygiene in a position of the long-term bed disabled patient with multiple injuries. Therefore, Intermaxillary fixation is not applied in the disabled bed patient, the alternative methods must be obtained. In the case of the mandibular fracture, because of the absence of weight bearing, osseous union may eventually occur even without immobilization if the patient is maintained without wound infection on a controlled soft diet. For the purpose of the prevention of the wound infection, the establishment of an drainage on the oral lacerated wound is necessary for the removal of the hematoma & seroma in the fracture site. This is the report of a case that was managed conservatively without the intermaxillary fixation in the long-term disabled bed patient with a mandibular compound fracture.

• 반도체디스플레이기술학회지
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• 제16권2호
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• pp.32-38
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• 2017

This paper is about the analysis on the vibration characteristic of tooling units on the precision bed in high-speed automatic lathe for precision machining. An automatic lathe operating at about 25,000 RPM is a critical factor in the self-weight stress and deformation of the bed. Especially, the resonance frequency should be grasped in advance to prevent abnormal vibration that may occur during processing. If the wrong bed is used, the resonant frequency can have a fatal influence on the precision machining and increase the defective rate of precision machined parts such as semiconductor parts. In this paper, vibration characteristics were evaluated through static load and resonance frequency analysis of automatic lathe bed. As a result, the maximum stress was 0.14MPa, the maximum deformation amount was $17.9{\mu}m$, and the natural frequency was 364.72Hz. The resonance frequency was calculated as 718Hz, and the stability was confirmed by being in the range of 400Hz or more, which is the processing condition.

• 반도체디스플레이기술학회지
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• 제17권1호
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• pp.66-70
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• 2018

This paper is about the analysis on the vibration characteristic of tooling units on the precision bed in turning and hobbing automatic lathe for precision machining. An automatic lathe operating at about 12,000 RPM is a critical factor in the self-weight stress and deformation of the bed. Especially, the resonance frequency should be grasped in advance to prevent abnormal vibration that may occur during processing. If the wrong bed is used, the resonant frequency can have a fatal influence on the precision machining and increase the defective rate of precision machined parts such as semiconductor parts. In this paper, vibration characteristics were evaluated through static load and resonance frequency analysis of automatic lathe bed. As a result, the maximum stress was 14.52 MPa, the maximum deformation amount was $12.15{\mu}m$, and the natural frequency was 189.43 Hz. The resonance frequency was calculated as 500 Hz, and the stability was confirmed by being in the range of 200 Hz or more, which is the processing condition.

• Journal of Industrial and Engineering Chemistry
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• 제67권
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• pp.301-311
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• 2018

In this study, the ion-gelation method was applied to fabricate novel Fe-carbon-bentonite-alginate beads ($Fe^0$/C-BABs). $Fe^0$/C-BABs could effectively control Fe release during persulfate (PS) activation in N-acetyl-p-aminophenol (APAP) oxidation. A novel two-stage approach that combined $Fe^0$/C-BABs and an oyster-shell-filled bed (OSFB) column was developed to address the low pH and high Fe concentration of the effluent of the traditional PS process. The application of the $Fe^0$/C-BABs and OSFB column regulated pH levels and Fe release during the advanced oxidation of APAP. The characteristics of $Fe^0$/C-BABs were also investigated through scanning electron microscopy, energy dispersive spectrometry, and Fourier transform infrared spectroscopy. The long-term operation performance of $Fe^0$/C-BABs in a continuous fixed-bed reactor under simultaneous PS and APAP feeding was also evaluated. The effects of initial PS concentration, pH, fixed-bed weight, in-flow rate, and dissolved oxygen (DO) were investigated. Under selected conditions, 86.3% efficiency was achieved during the first stage of APAP degradation (effluent pH of 3.05, Fe contents: $106.25mgL^{-1}$). Water quality improved after the effluent was passed through the OSFB column (effluent pH of 6.32, Fe contents: $21.43mgL^{-1}$). Moreover, this study analyzed the free radicals and intermediates produced during APAP degradation to identify the possible routes of APAP degradation.

• Current Research on Agriculture and Life Sciences
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• 제17권
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• pp.7-13
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• 1999

고추의 뿌리에 서식하고 있는 근권미생물을 30여종 분리하여 고추 검은 곰팡이병원균 A. alteranta에 길항하는 미생물을 분리한 결과 분리주 No. J-24 균주가 가장 길항력이 우수하였으며 Bacillus subtilis로 동정되었다. B. subtilis J-24는 검은곰팡이병균(Alternaria alternata)에 대해서는 생육저지 효과가 99%로 나타났으며, 그외 갯빛곰팡이병균(Botrytis cinerea), 역병균(Phytophthora capsici), 잘록병균(Pythium ultimum), 탄저병균(Colletotrichum gloeosporioides), 겹무늬병균(Stemphylium botryosum)에도 생육저지효과를 강하게 나타내었다. 고추 유묘의 생장활력은 미생물제제가 첨가된 상토가 일반 상토 보다 엽면적이 15%, 줄기길이가 12%, 뿌리길이가 12% 증가하였고 전체 건물중이 약 13% 증가하여 고추유묘의 생장활력이 증가되었다.