• 대한의용생체공학회:의공학회지
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• 제28권6호
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• pp.727-731
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• 2007

All of us has an experience of using the word 'stress'. During the life, we are influenced with various physical and spiritual pressure, complication, discouragement and shortage. That much, stress exists everywhere and everytime around us. It is not easy to examine how much stress you are getting. You can examine only through the health institutions. The examining method is constituted with the psychological method and physiological method, but these methods have the low accuracy about stress index because of disproportion of subjectivity, objectivity and scientific. Consequently, this thesis suggests the algorithms of processing index to help easing stress which is able to examine personally and indexing with the mixing of results of psychological and physiological methods.

• 한국토양비료학회지
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• 제50권6호
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• pp.623-633
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• 2017

Food waste has been recognized as a organic sources for composting and many research was conducted to efficiently utilize or treat. This study was to evaluate a feasibility for producing food waste compost under co-composting with mixture of food and animal waste. The mixing ratio of food and animal waste was 35% as main material, which additionally mixed 30% of sawdust for co-composting. Total days of composting experiment were 84 days and each sub samples were collected at every 7 days from starting of composting. Results showed that inner temperature in composting was rapidly increased to $70{\pm}4^{\circ}C$ within 3~5 days depending on mixing animal waste of cattle, pig, and chicken base compared to sole food waste base. Expecially, the CN ratio in the mixture of food and pig water was the highest (16.2) among compost. After finishing composting experiment, maturity was evaluated with solvita and germination test. Maturity index (MI) of the mixture of food and animal waste was ranged between 6~7, but was 3 in sole food waste. Calculated germination index (GI) was at the range of about 100 irrespectively of mixing of food and animal waste. However, NaCl content and heavy metal as Cr, Cu, Ni, Pb, and Zn contents was increased in the mixture of food and animal waste. which was the highest in compost mixed the food and pig waste. Both MI and GI showed that manufactured fertilizer was suitable for fertilizer criteria while sole food waste was not adequate for composting due to composting periods. Overall, mixing the food and animal waste can be utilized for improving compost maturity, but more research should be conducted to make high quality of food waste compost with animal waste in agricultural fields.

• 한국건축시공학회지
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• 제1권2호
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• pp.174-178
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• 2001

This study was performed to control the thermal crack of the mat footing slab in the multi-purposed buildings. In this study, we executed the mixing design of concrete to satisfy the workability and the quality according to the site conditions. And, we evaluated quantitatively about the possibility of thermal crack by using hydration heat analysis system. Finally, we proposed the optimal mixing conditions, curing methods and curing period which all factors are considered. As a result, the optimal mixing conditions were : W/B 41%, unit binder 375kgf/$\textrm{m}^3$, FA replacement ratio 20%. Lowest thermal stress was 22.0kgf/$\textrm{cm}^2$ and at that time thermal crack index was over 1.5, when the coefficient of thermal conductivity was lowest among the curing conditions. And, the total curing time was estimated at 6.7 days according to curing steps.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.533-538
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• 2001

This study was peformed to control the thermal crack of the mat footing slab in the multi-purposed buildings. In this study, we executed the mixing design of concrete to satisfy the workability and the quality according to the site conditions. And, we evaluated quantitatively about the possibility of thermal crack by using hydration heat analysis system. Finally, we proposed the optimal mixing conditions, curing methods and curing period which all factors are considered. As a results, the optimal mixing conditions were : W/B 41%, unit binder 375kg/$cm^{2}$, FA replacement ratio 20%. Lowest thermal stress was 22.0kgf/$cm^{2}$ and at that time thermal crack index was over 1.5, when the coefficient of thermal conductivity was lowest among the curing conditions. And, the total curing time was estimated at 6.7 days according to curing steps.

• 한국자동차공학회논문집
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• 제16권6호
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• pp.192-199
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• 2008

The key issues for the reduction technologies of the exhaust gas from diesel engine being developed are to reduce particulate matters and NOx. The SCR system is known to be one of the most efficient and stable technologies to remove NOx through the mixing of NOx and urea solution. In the present research, the effects of mixer configurations of SCR system have been investigated to enhance the SCR performance. First, a Schlieren technique is employed to visualize the mixing characteristics of urea solution and exhaust gas. The results show that a mixer is essential to obtain proper fluid mixing. In addition, numerical studies have been made to understand the mixing characteristics through the comparison of the mal-distribution index of concentration at the several locations of the diffuser. In particular, the effects of number of blade and mixer angles on mixing characteristics were studied. The results show that the blade angle has a larger effect on the mixing characteristics than the number of blades.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.3452-3457
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• 2007

Experiments were carried out in an atmopheric pressure, lab-scale gas turbine combustor to see the effect of partial premixing on unstable flame structure and $NO_X$ emission characteristics. The swirl angle is 45 deg., fuel-air mixing degrees were varied 0, 50, and 100% respectively at equivalence ration ranging from 0.53 to 0.79. The evaluation of phased-locked OH chemiluminescence images were acquired with an ICCD. $NO_X$ emission characteristics were also investigated at each experimental condition. The effect of the fuel-air mixing degree on the flame structure was obtained from phase-locked $OH^*$ images. And it was obtained from local heat release characteristics that the information about the region which the combustion instability was amplified or damped. It also could be confirmed that ${\sigma}$ has greatly influence on $NO_X $emission characteristics at lean regimes. It would be expected that it could provide invaluable data for understanding the mechanism of combustion instability

• 한국가시화정보학회지
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• 제8권4호
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• pp.13-18
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• 2010

This paper presents an experimental study on the performance of a micro-mixer using AC electro-osmotic flow. The microchannel is made of PDMS for the side and top walls and glass patterned with ITO for the bottom wall. We first investigated the effect of the applied potential as well as the frequency on the slip velocity. We have found that the slip velocity is roughly proportional to the applied voltage in line with the Helmholtz-Smoluchowski equation and there is an optimum frequency at which the slip velocity becomes maximized. To find the optimum parameters for mixing device we tested our device for various design parameters. It turned out that the best mixing effect is obtained approximately when the electrode angle is $30^{\circ}$, electrode width $200\;{\mu}m$, and the frequency of power supply 700 Hz.

• 청정기술
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• 제18권4호
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• pp.404-409
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• 2012

본 연구는 교반강도 및 응집제 주입량의 변화에 따라 플럭의 성장특성이 인의 제거에 미치는 영향을 파악하고자 수행되었다. 본 연구에서는 Al/P 몰비를 1.0, 1.5와 2.0으로 급속혼화강도 G값을 100, 300과 500 $s^{-1}$로 변화시켜 수행하였다. 응집시 발생되는 응집지수(floc size index, FSI)와 크기가 다른 여과지를 이용하여 인의 제거율을 측정하여 성장 특성을 파악하였다. 연구결과 교반강도가 높을수록 용존인의 제거효율이 증가하였으며 Al/P 몰비가 낮을수록 교반강도의 영향이 컸다. T-P의 제거율은 Al/P 몰비 1.0 이하에서는 급속혼화 교반강도가 높을수록 높았으나 Al/P 몰비 1.0 이상에서는 G값 300 $s^{-1}$에서 가장 높은 제거 효율을 나타내었다. Al/P 비 1.0 이하에서는 G값 500 $s^{-1}$에서 가장 큰 FSI값을 나타내었으며, Al/P 몰비 1.0 이상에서는 G값 300 $s^{-1}$에서 가장 큰 FSI값을 나타내었다. 실제하수처리장 유출수를 대상으로 응집에 의한 인 제거에 Al/P 몰비와 급속혼화 강도의 영향은 인공조제수의 결과와 유사하였다.

• Macromolecular Research
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• 제17권8호
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• pp.616-622
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• 2009

In-depth understanding of the influence of hot pressing and melt processing on the properties of thermoplastic polyurethane (TPU) is critical for effective mechanical recycling of TPU scraps. Therefore, this study focused on the effects of hot pressing and melt mixing on molecular weight (MW), polydispersity index (PDI), melt index (MI), characteristic IR peaks, hardness, thermal degradation and mechanical properties of TPU. The original TPU pellet (o-TPU) showed two broad peaks at lower and higher MW regions. However, four TPU film samples, TPU-0 prepared only by hot pressing of o-TPU pellet and TPU-1, TPU-2 and TPU-3 obtained by hot pressing of melt mixed TPUs (where the numbers indicate the run number of melt mixing), exhibited only a single peak at higher MW region. The TPU-0 film sample had the highest $M_n$ and the lowest PDI and hardness. The TPU-1 film sample had the highest $M_w$ and tensile modulus. As the run number of melt mixing increased, the peak-intensity of hydrogen bonded C=O stretching increased, however, the free C=O peak intensity, tensile strength/elongation at break and average MW decreased. All the samples showed two stage degradations. The degradation temperatures of TPU-0 sample (359 $^{\circ}C$ and 394 $^{\circ}C$)were higher than those of o-TPU (342 $^{\circ}C$ and 391 $^{\circ}C$). While all the melt mixed samples degraded at almost the same temperature (365 $^{\circ}C$ and 381 $^{\circ}C$). The first round of hot pressing and melt mixing was found to be the critical condition which led to the significant changes of $M_n$/$M_w$/PDI, MI, mechanical property and thermal degradation of TPU.

• 한국치위생학회지
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• 제1권1호
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• pp.89-99
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• 2001

Estimating by clinical index the efficacy of three cases, where chewing gum is mixed with nanoparticle containing chlorhexidine, where chewing gum doesn't contain neither of them, and where with chlorhexidine only, this study has come to the following conclusion. 1. The chewing gum with chlorhexidine and chlorhexidine nanoparticle has shown more reduction of plaque index and gingival index than that with no chlorhexidine. 2. There could be seen a difference between the gum with chlorhexidine and the gum with chlorhexidine nanoparticle. 3. The gum with chlorhexidine nanoparticle has shown less level of plaque index than that chlorhexidine, which difference was only slight. 4. The gum with chlorhexidine nanoparticle wasn't absorved any tooth coloring. To put these results together, it is proposed that mixing chewing gum with chlorhexidine nanoparticle can be an efficient application.