• Macromolecular Research
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• 제8권4호
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• pp.192-198
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• 2000

Cure characteristics and physical properties of carbon black-filled natural rubber (NR) compounds depending on the mixing procedure were studied using the compounds with different pre-final mixing (FM-1) stages. Carbon master batch (MB) and first and second remitting (1RM and 2RM) stages were employed as the FM-1 stage. Bound rubber content of the FM compound decreased with increasing the mixing steps. This was due to the decrease of the molecular weight distribution of the polymer by the rubber chain scission during the mixing. The Mooney viscosity decreased with increasing the mixing steps. Cure characteristics of the compounds were found to be different with the mixing procedures. The cure times of the compound became slower by increasing the number of the mixing steps. This was explained by the length of rubber chain, the carbon black network, distribution of the curatives in the compound, and immobilization of the polymeric segments. Modulus and tensile strength of the vulcanizate did not show a specific trend with the mixing procedure. Fatigue life of the vulcanizate increased by increasing the mixing stages.

• Elastomers and Composites
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• 제37권1호
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• pp.14-20
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• 2002

실리카로 보강된 고무 배합물은 보강제의 분산이 나쁘기 때문에 카본 블랙으로 보강된 배합물에 비해 더 긴 배합 시간이 필요하다. 실리카와 카본 블랙으로 보강된 천연 고무 배합물에서 배합 공정이 물성에 미치는 영향을 연구하였다. 마스터뱃치(MB) 배합물의 최종 온도를 $150^{\circ}C$로 하였을 때, 실리카와 카본 블랙을 따로 투입하는 경우가 함께 투입하는 공정보다 배합 시간을 더 길게 가질 수 있었다. 실리카를 먼저 투입하는 것이 카본 블랙을 먼저 투입하는 것보다 배합 시간이 길었다. MB 배합 공정을 한 단계로 구성한 배합물과 두단계로 구성한 배합물을 비교하였다. 두 단계 공정으로 배합한 배합물의 스코치 시간이 한 단계 공정으로 만든 배합물의 스코치 시간보다 길었고 bound rubber 함량은 작았다. 두단계 공정으로 만든 가황물은 한단계 공정으로 만든 것에 비해 신율이 높고 인장 강도도 강하고 피로 특성도 우수한 것으로 나타났다.

• 대한기계학회논문집A
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• 제30권3호
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• pp.302-309
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• 2006

Effective mixing plays a crucial role in microfluidics for biochemical applications. Owing to the small device scale and its entailing the low Reynolds number, the mixing in microchannels proceeds very slowly. In this work, we optimize the configuration of obstacles in the Y-channel mixer in order to attain maximum mixing efficiency. Before the optimum design, mixing characteristics are investigated using unstructured grid CFD method. Then, the analysis method is employed to construct the approximate analysis model to be used in the optimization procedure. The main optimization tool in the present work is sequential quadratic programming method. Using this approximate optimization procedure, we may obtain the optimum layout of obstacles in the Y-channel mixer in an efficient manner, which gives the maximum mixing efficiency.

• Elastomers and Composites
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• 제57권4호
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• pp.129-137
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• 2022

Low molecular weight liquid butadiene rubber (LqBR) is a processing aid that can resolve the migration problem of tire tread compounds. Various studies are being conducted to replace the petroleum-based processing oil with LqBR. However, the effect of the loading time of LqBR in the compounding process on silica dispersion and vulcanizate properties is not well known. In this study, we analyzed silica dispersion, vulcanizate properties, and viscoelastic properties of silica-filled tire tread compound according to the processing aid type (TDAE oil, non-functional LqBR) and, silane terminated LqBR) and input timing. In the non-functional LqBR compounds, the 'with TESPT' mixing procedure showed excellent dynamic viscoelastic properties while silane-terminated LqBR compounds showed that the 'after TESPT' mixing procedure was good for 300% modulus and abrasion resistance.

• 한국군사과학기술학회지
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• 제21권4호
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• pp.481-488
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• 2018

This study suggest the improvement of the CFRP adhesive mixing ratio about acoustic window to enhance SONAR performance. The CFRP of submarine is produced by allocation an acoustic window zone by the beam width of SONAR sensors. During the sea trial, SONAR system's bearing and range accuracy data is not in tolerance due to debonding phenomenon on CFRP. The inappropriate mixing ratio of adhesives caused that peeling phenomenon occurred in the acoustic window part, which is the reason for the deterioration of SONAR sensors performance. The report includes explanation of test procedure of SONAR, root cause analysis, CFRP manufacturing procedure, laboratory tests results, and proof of the performance at the sea trial.

• 한국건축시공학회지
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• 제18권2호
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• pp.133-140
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• 2018

이 연구의 목적은 바텀애시 및 준설토 기반의 인공 경량골재 콘크리트의 합리적 배합설계 절차를 제시하는 것이다. 25 배합의 실험결과를 바탕으로 경량골재 콘크리트의 목표성능(압축강도, 절건 밀도, 초기 슬럼프, 공기량)에 대하여 물-시멘트 비, 단위 시멘트양, 경량 잔골재 치환율을 결정하는 식을 제시하였다. 제안된 식과 절대용적 배합의 개념으로부터 각 구성요소들의 단위용적중량을 산정하였다. 제시된 배합설계 절차는 기존 결정에 효율적으로 이용될 수 있다.

• 농약과학회지
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• 제16권4호
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• pp.391-394
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• 2012

Chlorpyrifos 유제 살포액 조제 시 작업자의 손 노출량 측정하였으며, 위해성 평가를 실시하였다. 분석기기상의 검출한계는 0.25 ng, 정량한계는 1 ng로 설정하였고, 표준 검량선의 직선성과 분석재현성은 우수하였다. 장갑의 회수율은 72.3-103.4% 이었다. 살포액 조제 시 평균 손 노출은 3.9 mg이었으며, 조제 약량 대비 0.004%이었다. 위해성평가를 하기 위하여 한국 평균 남자 체중, 농작업자노출허용량(AOEL, acceptable operator exposure level) 손 노출량을 비교하였다. 또한 하루 조제 횟수는 8회로 가정하였고, 가장 많이 노출되는 최악의 경우를 확인하기 위하여 30 반복 손 노출량의 75 percentile에 해당하는 노출량(4.6 mg)을 이용하여 위해성 평가 결과 위해성이 낮은 것으로 판단되었으나, 30반복 각각의 위해성 평가 결과 2회는 노출량보다 허용량보다 많아서 위해성이 예상되었다.

• 한국공작기계학회논문집
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• 제16권1호
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• pp.47-52
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• 2007

A material mixing method to obtain an optimal topology for a structure in a thermal environment was suggested. This method is based on Evolutionary Structural Optimization(ESO). The proposed material mixing method extends the ESO method to a mixing several materials for a structure in the multicriteria optimization of thermal flux and thermal stress. To do this, the multiobjective optimization technique was implemented. The overall efficiency of material usage was measured in terms of the combination of thermal stress levels and heat flux densities by using a combination strategy with weighting factors. Also, a smoothing scheme was implemented to suppress the checkerboard pattern in the procedure of topology optimization. It is concluded that ESO method with a smoothing scheme is effectively applied to topology optimization. Optimal topologies having multiple thermal criteria for a printed circuit board(PCB) substrate were presented to illustrate validity of the suggested material mixing method. It was found that the suggested method works very well for the multicriteria topology optimization.

• 한국식품조리과학회지
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• 제12권3호
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• pp.331-338
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• 1996

The main aim of this study was to develop carrot soups with fishery products, which is improved from traditional gruel of Cheju island. For this the optimal procedure and ingredient mixing ratio for making basic carrot soup was determined through the instrumental measurement, the sensory evaluation and the nutrient analysis, and then the carrot-fishery soups were prepared by mixing the fishery products from Cheju island. The results were as follows: The optimal procedure for making basic carrot soup was to saute the sliced carrots and soaked rices with the sesame oil for 5 min, add the water, bring to a boil for 6 min, simmer for 15 min, then puree the soup. The optimal ingredient mixing ratio in the basic carrot soup was carrot 300 g: rice 45 g: water 900 $m\ell$: sesame oil 15 $m\ell$: salt 5 g. For preparing carrot-fishery soups were the optimal fishery products mixing ratio i) 30% tile fish or crab, ii) prawn, abalone, top shell, or ear shell 20%, iii) sea urchin 15%, iv) fusiform or gulf weed 5％. The order of sensory evaluation scores, on a 5-point scale, were sea urchin, crab > top shell, tile fish > abalone, ear shell > prawn > coral fish > fusiform, gulf weed. Nutrient composition analysis showed that vitamin A was 5 times higher in carrot soup than in pumpkin soup. Sensory evaluation scores show that carrot soup was prepared to pumpkin soup. A portion (200 g) of the soup would provide 144% of the recommended daily allowance of vitamin A. The results of this work indicate that an acceptable carrot-fishery soups of better nutritional and sensory values than pumpkin soup can be prepared.

• 한국연소학회:학술대회논문집
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• 한국연소학회 1997년도 제15회 KOSCO SYMPOSIUM 논문집
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• pp.113-122
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• 1997

The conditional moment closure formulation considering the molecular and turbulent diffusion is derived. A simplified solution procedure is proposed to reduce the computational burden due to the increased dimensionality of the conditionally averaged variables. A conditionally averaged variable is expressed as a linear weighted average of the two extremes, 'no reaction' and 'equilibrium' states. The modified elliptic-type conditional moment closure formulation is implemented to simulate a two dimensional nonpremixed mixing layer reacting flow. Results show good agreement for the conditional averages of the species concentration in Bilger et al.