• 대한기계학회논문집A
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• 제38권11호
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• pp.1283-1290
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• 2014

최근에는 법공학 분야에 구조해석 및 구조-유동 연성해석을 이용한 다양한 시뮬레이션 기법을 활용하여 안전사고 및 재난사고에 대한 법적 책임문제를 해명하고 보다 정확한 원인분석을 통해 원인을 규명하고 있는 추세이다. 본 연구에서는 법공학적 관점에서 DCM(Deep Cement Mixing) 선박의 침몰 사고의 원인을 밝혀내고자 하였다. 사고 선박은 선박 건조 당시 SCP(Sand Compaction Pile) 전용 선박으로 건조되었으며, DCM 선박으로 구조 변경을 위해 안정성 검토 없이 리더부 높이 변경 및 증설을 하였다. 이러한 구조물의 증설 및 변경이 본 침몰 사고에 미치는 영향을 알아내고자 상용 구조 해석프로그램인 ADINA를 이용하여 구조안정성 평가를 수행하였으며, 본 연구를 통하여 구조물의 증설 및 변경에 따른 ADINA 해석 결과를 비교, 분석함으로써 DCM 선박 침몰 사고의 정확한 원인을 밝혀낼 수 있었다.

• 상하수도학회지
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• 제21권3호
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• pp.359-366
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• 2007

Slow sand filtrations have been widely used for water treatment in small communities, however their capacity is often limited by high turbidity in the raw water. For this reason, several pre-treatment facilities were required for a slow sand filter. Turbidity removal from the highly turbid raw water was investigated in roughing filters as a pre-treatment process. The roughing filters followed by rapid mixing tank were operated in the form of a contact filtration. In several jar tests, the predetermined optimum aluminium sulfate (alum) doses for turbid water of 30 and 120NTU were 30 and 50mg/L, respectively. At the optimum alum dose, physically optimum parameters including G value of $220sec^{-1}$ and rapid mixing time of 3 minutes were applied to the contact filtration system. Without addition of alum, the filtrate turbidity from the roughing filters, packed respectively with different media such as sand, porous diatomite ball and gravel, was in the range of 5~30NTU at filtration velocities of 30 and 50m/day. However, the application of a contact filtration to roughing filters showed stably lower filtrate turbidity below 1.0NTU at filtration velocity of 30 m/day. Although the filtration velocity increased to 50m/day, filtrate turbidity was still below 1.0NTU in both single and double layer roughing filters. At influent turbidity of 120NTU, the filtrate turbidity was over 5 NTU in the triple layer roughing filter, which shortened the filter run time. The flocs larger than $10{\mu}m$, formed in the rapid mixing tank, were almost captured through the roughing filter bed, while the almost flocs smaller than $10{\mu}m$ remained in filtrate.

• 폴리머
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• 제25권5호
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• pp.691-698
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• 2001

에폭시 (diglycidyl ether of bisphenol A: DGEBA), 경화제 (dicyandiamide; DICY), 촉매 (benzyl dimethyl amine : BDMA), 그리고 유기치환된 실리케이트 (organically modified mica type silicate: OMTS)를 용융법 및 용액법을 이용해 나노복합체를 제조하였고, $170^{\circ}C$에서 시간에 따라 경화 반응을 진행하면서 X선 회절분석기 (XRD)와 소각 X선 산란장치 (SAXS)를 이용하여 구조 변화를 관찰하였다. 용융법으로 제조된 치료의 경우 박리된 구조를 관찰할 수 없었으나 용액법에 의해 제조된 경우 박리된 구조를 관찰할 수 있었다. 이는 OMTS 층 내ㆍ외부의 경화 속도차이 때문인 것으로 생각된다. 박리된 에폭시 나노복합체의 OMTS 첨가량에 따른 기계적 물성을 동적기계적 분석기 (DMA)를 이용해 측정한 결과 OMTS의 첨가량이 증가할수록 모둘러스는 증가하였으나 유리전이온도는 큰 차이가 없었다. OMTS 첨가량에 따른 열적 성질을 열중량분석기(TGA)와 한계산소지수 (LOI)를 이용해 측정한 결과 OMTS양이 증가할수록 OMTS 판의 차단효과로 인해 열분해 시작 온도와 LOI 값이 증가하였다.

• Journal of Mechanical Science and Technology
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• 제14권10호
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• pp.1131-1142
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• 2000

In an effort to illustrate the global variation of SMD (Sauter mean diameter, or $D_{32}$) and AMD (Arithmetic mean diameter, or $D_{10}$) at five axial downstream locations (i. e., at Z=30, 50, 80, 120, and 170 mm) under the different experimental conditions, the radial coordinate is normalized by the spray half-width. Experimental data to analyze the atomization characteristics concerning with an internal mixing type have been obtained using a PDPA(Phase Doppler Particle Analyzer). The air injection pressure was varied from 40 kPa to 120 kPa. In this study, counterflowing internal mixing nozzles manufactured at an angle of $15^{\circ}$with axi-symmetric tangential-drilled four holes have been considered. By comparing the results, it is clearly possible to discern the effects of increasing air pressure, suggesting that the disintegration process is enhanced and finer spray droplets can be obtained under higher air assist. The variations in $D_{32}$ are attributed to the characteristic feature of internal mixing nozzle in which the droplets are preferentially ejected downward with strong axial momentum, and dispersed with the larger droplets which are detected in the spray centerline at the near stations and smaller ones are generated due to further subsequent breakup by higher shear stresses at farther axial locations. The poor atomization around the centre close to the nozzle exit is attributed to the fact that the relatively lower rates of spherical particles are detected and these drops are not subject to instantaneous breakup in spite of the strong axial momentum. However, substantial increases in SMD from the central part toward the edge of the spray as they go farther downstream are mainly due to the fact that the relative velocity of droplet is too low to cause any subsequent disintegration.

• 한국지하수토양환경학회지:지하수토양환경
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• 제7권4호
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• pp.24-30
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• 2002

본 연구에서는 카올리나이트에 대한 납의 흡착 특성을 규명코자 실내에서 회분식 흡착시험을 수행하였다. 회분식 흡착시험에서는 흡착평형도달시간, 흡착능 및 흡착등온식을 연구하였고 pH와 혼합비에 따른 카올리나이트에 대한 납의 흡착특성에 미치는 영향을 분석하였다. 실험결과 카올리나이트에 대한 납의 흡착은 24시간 이내에 평형에 도달하였고 초기오염농도가 증가함에 따라 카올리나이트에 대한 납의 흡착량은 증가하나 초기농도 198mg/l 이상에서는 흡착율은 감소하였다 Freundlich 흡착등온식에 적용한 결과 흡착강도를 나타내는 계수 1/n은 0.9584이다. 그리고 pH 값이 증가함에 따라 초기오염농도에 관계없이 카올리나이트에 대한 납의 흡착량 및 흡착율은 증가되었으며 pH 8 이상에서는 일정한 값에 수렴하였다. 또한 혼합비가 증가함에 따라 흡착량은 증가하였다. 반면에 흡착율은 점점 증가하다가 일정 혼합비 8 이상에서는 감소하는 경향이 있음을 알 수 있었다.

• 상하수도학회지
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• 제23권4호
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• pp.459-469
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• 2009

It is well known that coagulation pretreatment can reduce foulants prior to membrane filtration. The purpose of this research was to investigate the effects of coagulation on fouling of ceramic microfiltration membrane($0.1 {\mu}m$) using pilot plant of $150m^3/day/train$ capacity. Train A membrane system has pretreatment process of ozonation and coagulation while train B has only coagulation. Two types of coagulation operation were investigated: back mixer(rapid mixing with or without slow mixing) which is a conventional mechanically stirred mixer and an inline static mixer. Ozone dose rate for train A was 1 mg/L and ozone contact time was 12 min. The coagulation dose(PACl 10% as $Al_2O_3$) rate was changed 20~40 mg/L according to experimental schedule. In this experimental conditions, the coagulation of back mixer type with rapid mixing(GT=72,000) and slow mixing(GT=45,000) was the best effective in reduction of ceramic membrane fouling regardless preozonation. Especially, the effect of inline static mixer was sensitive to change in water quality. Ozonation mainly affected irreversible fouling rather than reversible fouling in accordance with less adsorption of NOM on the membrane surface. Thus, the increase rate of the nomalized TMP(trans membrane pressure) at $25^{\circ}C$ for train A was relatively lower than that of train B under same coagulation process with same coagulant dosage. The best performance of ceramic membrane appeared in case of combined process with ozonation, therefore this integrated process is able to archive less coagulant dosing and secure a stability of ceramic membrane system.

• 펄프종이기술
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• 제32권4호
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• pp.49-57
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• 2000

This study was carried out to investigate the effect of the type of base papers containing rice straw-BKP on the properties and printabilities of coated papers. Also, it was intended to evaluate the effect of coated paper prepared with anionic and amphoteric latex based coating color. The results obtained from this study were as follows. The fiber length of rice straw-BKP was observed much shorter than those of the wood pulps(Sw-BKP, Hw-BKP). This has effect on physical properties. Therefore, the results of measured physical properties were much lower than those of wood pulps. Also, physical properties tended to increase slightly with the increase of the mixing ratio of Sw-BKP. Opacity of the base paper containing rice straw-BKP, was higher than that of the wood pulps. As the mixing ratio of Sw-BKP increases the opacity tended to decrease. On the other hand, smoothness and roughness to rice straw-BKP were similar with Sw-BKP and its air permeability was lower than those of wood pulps. The optical properties of coated papers containing rice straw-BKP tended to be similar to those of other base papers. The ink receptivity of coated papers containg rice straw-BKP was higher than those of wood pulps and printing gloss was similar to wood pulps. The mixing ratio of Sw-BKP, the ink receptivity and printing gloss of rice straw-BKP were showed no difference irrespective the mixing ratio of Sw-BKP. Meannwhile, amphoteric latex improved the optical properties and printability of coated papers.

• 폴리머
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• 제35권2호
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• pp.99-105
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• 2011

컴파운드의 물성을 최적화하기 위해서는 충전제 입자들의 분배와 분산이 잘 일어나도록 효율적으로 훈련하는 것이 중요하다. 혼련 효용을 향상시키고자 다양한 종류의 혼련 요소들이 이축압출기에 이용되고 있다. 본 연구에서는 탄산칼슘이 충전된 폴리스티렌을 대상으로 충전제 분산에 대한 이축압출기의 스크루 조합 영향을 알아보았다. 충전제의 분산 상태는 포토다이오드가 장착된 광학현미경으로 조사하였다. 실험 결과는 충전제의 분산 정도가 혼련 요소들의 형태 및 위치에 주로 영향을 받는다는 것을 보여주었다.

• 한국식품저장유통학회지
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• 제9권2호
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• pp.189-193
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• 2002

천연식초를 이용하여 분말식초의 제조방법을 개발하고자 부형제의 비율을 달리하여 제조한 분말식초의 품질특성을 평가하여 분말식초의 제조 가능성을 검토하였다. 혼합 피복 물질로 제조된 분말식초의 품질특성을 비교한 결과 $\beta$-cyclodextrin과 gum arabic이 2.5:7.5의 비율로 제조한 분말식초가 비교적 낮은 수분함량을 나타내었고 산도는 높은 수치를 나타내 식초를 포집하는 능력이 가장 좋은 것으로 나타났다. 또한 이 비율로 제조한 분말식초의 흡습성 또한 비교적 낮은 값을 나타내었으며 열안정성은 모든 시료가 높은 수치를 나타내 열에는 모두 안정함을 알 수 있었다. 주사 현미경으로 관찰한 분체의 형태는 모두 구형을 형성하여 분말식초에서 캡슐이 형성되었음을 알 수 있었다. 관능검사 결과도 신맛의 증가로 높은 점수를 받았다. 이상의 결과로 분말식초의 제조시 피복물질의 혼합비율별은 $\beta$-cyclodextrin 과 gum arabic을 2.5:7.5의 비율로 제조하는 것이 가장 우수한 것으로 나타났다.

• 한국환경보건학회지
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• 제35권3호
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• pp.226-234
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• 2009

The main objective of this study was to evaluate the effects on shape and size, compressive strength, water absorption and heavy metals leaching with various weight mixing ratios in waste ash brick products using waste recycling MSWI(Municipal Solid Waste Incinerator) bottom ash, steel slag and waste building material. The manufacturing processes for the waste ash brick consist of screening, mixing, conveyor transmission, compaction.forming, and curing steps of raw materials. The weight mixing ratios of steel slag around bottom ash were adjusted within the ranges of 10% to 30%. The reported results show that the width and thickness of the manufactured waste ash brick could be satisfied with $90{\pm}2mm\;and\;57{\pm}2mm$, respectively which are K.S. standards of products qualities. And in case of length, only 20-Ba50Ss30, 20-Ba60Wb20 and 20-Ba50Wb30 for the mixing ratios could be satisfied with $190{\pm}2mm$ that is K.S. standards of products quality. The compressive strength and water absorption for 20-Ba50Ss30 and 20-Ba70Wb10 were over $8N/mm^2$ and below 15% respectively that are K.S. standards of manufactured waste ash brick. The results of tests for the heavy metals leaching in the all manufactured waste ash bricks are also passed to the wastes management regulations. The cost analysis of 20-Ba50Ss30 is evaluated. The manufacturing cost is evaluated 34.3 won/brick with 8 hours and 20tons of raw material per day. Incinerators with problems in bottom ash disposal can therefore derive significant benefits from the application of waste ash brick production.