• Macromolecular Research
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• 제17권10호
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• pp.739-745
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• 2009

N,N'-(bicyclo[2,2,2]oct-7-ene-tetracarboxylic)-bis-L-amino acids 3a-g were synthesized by the condensation reaction of bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride 1 with two equimolars of Lalanine 2a, L-valine 2b, L-leucine 2c, L-isoleucine 2d, L-phenyl alanine 2e, L-2-aminobutyric acid 2f and L-histidine 2g in an acetic acid solution. Seven new poly(amide-imide)s PAIs 5a-g were synthesized through the direct polycondensation reaction of seven chiral N,N'-(bicyclo[2,2,2]oct-7-ene-tetracarboxylic)-bis-L-amino acids 3a-g with bis(3-amino phenyl) phenyl phosphine oxide 4 by two different methods: direct polycondensation in a medium consisting of N-methyl-2-pyrrolidone (NMP)/triphenyl phosphite (TPP)/calcium chloride ($CaCl_2$/pyridine (py), and direct polycondensation in a tosyl chloride (TsCl)/pyridine (py)/N,N-dimethylformamide (DMF) system. The polymerization reaction produced a series of flame-retardant and thermally stable poly(amide-imide)s 5a-g with high yield. The resulted polymers were fully characterized by FTIR, $^1H$ NMR spectroscopy, elemental analyses, inherent viscosity, specific rotation and solubility tests. Data obtained by thermal analysis (TGA and DTG) revealed that the good thermal stability of these polymers. These polymers can be potentially utilized in flame retardant thermoplastic materials.

• 한국세라믹학회지
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• 제53권1호
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• pp.116-121
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• 2016

The amount of carbon dioxide ($CO_2$) released while producing building materials is substantial and has been targeted as a leading contributor to global climate change. One of the most typical methods of reducing $CO_2$ in building materials is the addition of slag and fly ash, like pozzolan material another method is to reduce $CO_2$ production by developing carbon negative cement. MgO-based cement from the low-temperature calcination of magnesite required less energy and emitted less $CO_2$ than the manufacturing of Portland cements. It is also believed that adding reactive MgO to Portland-pozzolan cements can improve their performance and also increase their capacity to absorb atmospheric $CO_2$. In this study, basic research on magnesia cement using $MgCO_3$ and magnesium silicate ore (serpentine) as the main starting materials, as well as blast furnace slag for the mineral admixture, was carried out for industrial waste material recycling. In order to increase the overall hydration activity, $MgCl_2$ was also added. In the case of the addition of $MgCl_2$as accelerating admixture, there was a promoting effect on the compressive strength. This was found to be due to the production of needle-like dense Mg-Cl hydrates. Mgnesia cement has a high viscosity due to its high specific surface area therefore, when the PC-based dispersing agent was added at a level of more than 1.0%, it had the effect of improving fluidity. In particular, the addition of $MgCl_2$ in magnesia cement using $MgCO_3$and magnesium silicate ore (serpentine) as main starting materials led to a lower expansion ratio and an increase in the freeze-thaw resistance finally, the addition of $MgCl_2$ as accelerating admixture led to good overall durability.

• 상하수도학회지
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• 제26권2호
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• pp.177-189
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• 2012

Sediment load deposited in sewers and manholes reduces not only the capacity of pipes but also the efficiency of the whole sewer system. This causes the inundations of the low places and overflows at manholes, Moreover, sulfides and bad odor can occur due to deposited sediment with organic loads in manholes. Movements of sediment load in manholes are complicated depending on manhole size, location, inside structure, sediment load type, and time. Therefore, it is necessary to understand the movements of sediment load in manholes by experiments. In this study, experiments were implemented by a square manhole with straight path to measure deposited sedimentation quantity. The experimental apparatus was consisted of a high water tank, an upstream tank, test pipes, a sediment supplier, a manhole, and a downstream tank to measure the experimental discharge. The quantity of deposited sediment load was measured by different conditions, such as the inflow condition of sediment(continuous and certain period), the amount of inflow sediment, discharge, and the type of sediment. Jumoonjin sand(S=2.63, D50=0.55mm), general sand(GS, S=2.65, D50=1.83mm) and anthracite (S=1.45, D50=0.80mm) were employed for the experiment. The velocities in inflow pipe were 0.45 m/s, 0.67 m/s, and 0.9 m/s. Sediment load movement and sedimentation quantity in manhole were influenced by many factors such as velocity, shear stress, viscosity, amount of sediment, sediment size, and specific gravity. Suggested regression equations can estimated the quantity of deposited sediment in the straight path square manholes. The connoted equations that were evaluated through the experimental study have velocity range from 0.45 to 0.9m/sec. The study results illustrates that appropriation of design velocity ragne between 1.0 and 2.0m/sec could implement to maintain and manage manholes.

• 동아시아식생활학회지
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• 제14권1호
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• pp.39-46
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• 2004

본 연구에서는 옐로우 레이어 케이크의 재료 중 쇼트닝 대신 시판 탄수화물계 지방대체물인 waxy maize starch의 사용 가능성을 측정하고, 저 열량 레이어 케이크를 제조하기 위한 최적 비율을 결정하기 위해 여러 가지 비율로 대체하여 제조한 케이크의 물리적 및 관능적 특성을 평가하였다. 지방대체율이 증가할수록 케이크의 비중은 증가하지만 점도는 감소하였다. 주사전자 현미경 측정 결과, 지방 대체물이 증가함에 따라 air cell과 함께 지방구의 수와 크기는 감소하였고, 점도가 높을수록 치밀한 구조를 보였다. 또한, 물성특성 측정결과 대체율이 증가할수록 hardness, springiness, cohe-ssiveness, gumminess, chewiness 및 resilience는 감소하였다. 관능적 평가에서 색의 경우에만 waxy maize starch 대체 45%에서 가장 우수한 것으로 평가되었고 지방 대체율이 크게 증가했을 때 전반적인 관능적 평가에서 좋지 않은 것으로 나타났다. 따라서 지방 대체물인 waxy maize starch는 저 열량 레이어 케이크 제조 시 적은 비율의 쇼트닝 대체로 사용한다면, 새로운 저 열량 레이어 케이크 제조를 위한 새로운 소재로 사용 가능성이 시사되었다.

• 수산해양기술연구
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• 제23권2호
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• pp.72-79
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• 1987

국산 소형어선용 예연소실식 디이젤기관에 혼합연료유(정유+중유)를 사용할 경우 혼합연료유의 성질, 연소특성 및 기관성능에 관하여 실험한 결과를 요약하면 다음과 같다. 1) 혼합연료유의 혼합비율(중량비율)이 증가함에 따라 비중은 선형적으로 증가하였고, 점도-온도 곡선은 Walther-ASTM 식과 일치하였으며, 착화성지수인 CCAI의 값은 기울기 1.0에 가까운 직선으로 증가하였다. 2) 동일운전조건에서 착화지연은 CCAI의 값이 810(혼합비율 60%)까지는 미소하게 증가하였으나, 그 이상의 값에서는 현저하게 증가하였다. 따라서, 혼합연료유의 착화성을 나타내는 CCAI의 값은 810 이상에서 적용하는 것이 타당하다. 3) 연소최고압력은 혼합비율 40%까지 증가하다가 감소하였으며, 그을음농도는 60%부터 현저하게 증가하였으므로, 본 실험에서 무그을음 연료비절감의 안전운전 혼합비율은 50%가 적당하다

• 수산해양기술연구
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• 제23권2호
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• pp.26-26
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• 1987

국산 소형어선용 예연소실식 디이젤기관에 혼합연료유(정유+중유)를 사용할 경우 혼합연료유의 성질, 연소특성 및 기관성능에 관하여 실험한 결과를 요약하면 다음과 같다. 1) 혼합연료유의 혼합비율(중량비율)이 증가함에 따라 비중은 선형적으로 증가하였고, 점도-온도 곡선은 Walther-ASTM 식과 일치하였으며, 착화성지수인 CCAI의 값은 기울기 1.0에 가까운 직선으로 증가하였다. 2) 동일운전조건에서 착화지연은 CCAI의 값이 810(혼합비율 60%)까지는 미소하게 증가하였으나, 그 이상의 값에서는 현저하게 증가하였다. 따라서, 혼합연료유의 착화성을 나타내는 CCAI의 값은 810 이상에서 적용하는 것이 타당하다. 3) 연소최고압력은 혼합비율 40%까지 증가하다가 감소하였으며, 그을음농도는 60%부터 현저하게 증가하였으므로, 본 실험에서 무그을음 연료비절감의 안전운전 혼합비율은 50%가 적당하다

• Applied Biological Chemistry
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• 제50권3호
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• pp.160-166
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• 2007

본 연구는 초미세 분체기술을 이용하여 쌀 전분의 입자구조 파괴가 이루어졌을 때 분자구조적, 물리적 변화가 어떻게 이루어지는지를 구명하고자 하였다. 분쇄 후 쌀 전분의 평균직경은 약 20% 감소가 이루어졌으며 비표면적은 25% 증가하였다. 분쇄 전후의 쌀 전분에 대한 분자량분포를 GPC(gel permeation chromatography)로 측정한 결과 Peak II의 면적이 36.5%에서 59.5%로 상승하였다. 분쇄 전후 손상전분 정도는 각각 16.40%와 99.2%로 나타났다. 분쇄 전에 비하여 분쇄 후 쌀 전분의 물결합능력, 용해도와 광 투과도에서도 월등히 높았다. $30^{\circ}C$에서 20 rpm을 기준으로 분쇄후의 쌀 전분의 겉보기점도는 상대적으로 분쇄 전의 7% 수준에 불과하였으며 측정온도가 높아짐에 따라서 차이는 더욱 커졌다.

• Asian-Australasian Journal of Animal Sciences
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• 제26권1호
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• pp.97-107
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• 2013

The aim of this study was to establish relationships between chemical and physical parameters of wheat with performance and digestibilities of feed components in broiler chickens fed on wheat-based diets. Ninety-four wheat samples were selected for inclusion in four bird trials. Birds were housed in individual wire metabolism cages from 7 to 28 d and offered water and feed ad libitum. Dry matter intake (DMI), liveweight gain (LWG) and gain:feed were measured weekly. A balance collection was carried out from 14 to 21 d for determination of apparent metabolizable energy (AME), ME:gain, dry matter retention, oil and neutral detergent fibre (NDF) digestibility. At 28 d the birds were humanely killed, the contents of the jejunum removed for determination of in vivo viscosity and the contents of the ileum removed for determination of ileal dry matter, starch and protein digestibility. When wheat parameters were correlated with bird performance data, it was found that specific weight was not significantly (p>0.05) related to bird performance. Bird DMI, LWG and gain:feed were best correlated (p<0.05) with the rate of starch digestion, although the coefficients of correlation (r) were still low (0.246 to 0.523). A negative relationship (p<0.01) between AME and total (r = -0.432) and soluble (r = -0.304) non starch polysaccharide (NSP) was observed in this study. Thousand grain weight (TG) was positively correlated with DMI (r = 0.299), LWG (r = 0.343) and gain:feed (r = 0.371). When establishing multiple regression relationships, correlation coefficients greater than 0.8 were achieved for DMI, LWG, gain:feed and ileal crude protein digestibility. However, the economics involved in determining the parameters involved in the regressions make the process impractical.

• 한국수소및신에너지학회논문집
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• 제13권4호
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• pp.259-269
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• 2002

A battery based on the lithium/elemental sulfur redox couple has the advantage of high theoretical specific capacity of 1,675 mAh/g-sulfur. However, Li/S battery has bad cyclic durability at room temperature due to sulfur active material loss resulting from lithium polysulfide dissolution. To improve the cycle life of Li/S battery, PEGDME (Poly(ethylene glycol) dimethyl ether) 500 containing 1M LiTFSI salt which has high viscosity was used as electrolyte to retard the polysulfide dissolution and nano-sized $Mg_{0.6}Ni_{0.4}O$ was added to sulfur cathode as additive to adsorb soluble polysulfide within sulfur cathode. From experimental results, the improvement of the capacity and cycle life of Li/S battery was observed( maximum discharge capacity : 1,185 mAh/g-sulfur, C50/C1 = 85 % ). Through the charge-discharge test, we knew that PEGDME 500 played a role of preventing incomplete charge-discharge $behavior^{1,2)$. And then, in sulfur dissolution analysis and rate capability test, we first confirmed that nano-sized $Mg_{0.6}Ni_{0.4}O$ had polysulfide adsorbing effect and catalytic effect of promoting the Li/S redox reaction. In addition, from BET surface area analysis, we also verified that it played the part of increasing the porosity of sulfur cathode.

• Journal of Biosystems Engineering
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• 제32권3호
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• pp.166-172
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• 2007

Egg quality indices are related with freshness, size of air chamber, loss of weight, and viscosity of the yolk and the protein. However, since the described quality parameters require measured in a destructive way, it is not suitable to inspect the egg quality with complete enumeration. Therefore, this study was performed to investigate the potential of image analysis method for evaluation of internal egg quality. Samples of 90 fresh eggs were collected immediately after laying and stored up to 24 days. Five eggs were randomly drawn from each storage condition (packing vs unpacking) at a regular interval and loss of weight, specific gravity and size of air chamber were measured. The image analysis for nondestructive measurement of size of air chamber was also studied. Results showed that the egg weight and gravity gradually decreased with increasing of storage days, while the size of air chamber linear increased caused by evaporation of water through the shell. A relationship a between conventional method and the image analysis method for measuring the size of air chamber was developed with the correlation coefficient of 0.928. The new finding implied that image analysis might provide a useful nondestructive tool to assess internal egg quality.