• 한국응용과학기술학회지
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• 제19권4호
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• pp.273-280
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• 2002

Thermal decomposition of the copolymer of butyl methacylate(BMA) with styrene(St) was investigated. The copolymer Was obtained at 80 $^{\circ}C$ in a continuous stirred tank reactor(CSTR) using toluene and benzoyl peroxide(BPO), as solvent and initiator, respectively. The reactor volume was 0.3 liters and residence time was 3 hours. The thermal decomposition followed the second order kinetics for BMA/St copolymer. The activation energies of thermal decompositon were in the ranges of 38 ${\sim}43$ kcal/mol for BMA with St copolymer and a good additivity rule was observed with the composition of copolymer. The thermogravimetric trace curve agreed well with the theoretical calculation.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1806-1813
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• 2003

The stirred tank reactor is one of the most commonly used devices in industry for achieving mixing and reaction. Here we report on results obtained from the large eddy simulations of flow inside the tank performed using a spectral multi-domain technique. The computations were driven by specifying the impeller-induced flow at the blade tip radius. Stereoscopic PIV measurements (Hill et $al.^{(1)}$) along with the theoretical model of the impeller-induced flow (Yoon et $al.^{(2)}$) were used in defining the impeller-induced flow as superposition of circumferential, jet and tip vortex pair components. Large eddy simulation of flow in a stirred tank was carried out for the three different Reynolds numbers of 4000, 16000 and 64000. The effect of different Reynolds numbers is well observed in both instantaneous and time averaged flow fields. The instantaneous and mean vortex structures are identified by plotting an isosurfaces of swirling strength for all Reynolds numbers. The Reynolds number dependency of the nondimeansional eddy viscosity, resolve scale and subgrid scale dissipations is clearly shown in this study.

• 대한기계학회논문집B
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• 제27권9호
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• pp.1290-1298
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• 2003

The stirred tank reactor is one of the most commonly used devices in industry for achieving mixing and reaction. Here we report on results obtained from the large eddy simulations of flow inside the tank performed using a spectral multi-domain technique. The computations were driven by specifying the impeller-induced flow at the blade tip radius. Stereoscopic PlY measurements (Hill et al. $^{(1)}$) along with the theoretical model of the impeller-induced flow (Yoon et al. $^{(2)}$) were used in defining the impeller-induced flow as superposition of circumferential, jet and tip vortex pair components. Large eddy simulation of flow in a stirred tank was carried out for the three different Reynolds numbers of 4000, 16000 and 64000. The effect of different Reynolds numbers is well observed in both instantaneous and time averaged flow fields. The instantaneous and mean vortex structures are identified by plotting an isosurfaces of swirling strength for all Reynolds numbers. The Reynolds number dependency of the non-dimensional eddy viscosity, resolved scale and subgrid scale dissipations is clearly shown in this study.

• Korean Chemical Engineering Research
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• 제44권5호
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• pp.520-527
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• 2006

본 연구에서는 FC(fluorocarbon) 플라즈마 반응기에서 입사하는 이온에너지에 따른 고분자 증착, 식각과 증착의 경쟁반응 및 물리적 스퍼터링 등의 여러 표면 현상들을 모델링하였다. $SiO_2$ 식각에 대한 표면반응은 식각반응 영역을 잘 혼합된 CSTR(continuous stirred tank reactor) 가정을 도입하여 이온 도움에 의한 식각으로 모사되었다. 정상상태 고분자층을 통한 식각과 증착의 경쟁반응의 모델링은 이온 도움에 의한 고분자 생성 및 분해 메커니즘을 제안하여 수행하였다. 이러한 메커니즘은 최근 발표된 실험 및 분자동력학적 전산모사 결과에 기초하였으며,모델 계수들은 빔실험 결과 및 플라즈마 실험결과들을 이용하여 구하였다. 최종 개발된 모델의 결과들은 타당성을 검증하기 위해 문헌에 보고된 실험결과들과 비교하였다.

• 한국산학기술학회논문지
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• 제11권11호
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• pp.4649-4655
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• 2010

본 논문은 A 시의 산업단지 종말처리장의 방류수 유입에 따른 K 소류지의 녹조 제어 가능성을 평가하고자 하였다. 완전혼합연속반응기로 모형화한 호소를 총인과 엽록소-a의 농도를 예측하였다. 정상상태일 때 총인과 엽록소-a 농도는 각각 $0.29\;/m^3$과 $4.0\;g/m^3$를 나타났고 실측치와 유사한 결과를 보였다. 비정상상태에서 종말폐수방류수가 최소유량 또는 최대유량으로 소류지로 유입될 때 시간경과에 따른 총인과 엽록소-a 농도 변화를 예측하였다. 또한, 현재 심각한 부영양화 단계에 있는 소류지를 중영양 또는 빈영양 단계로 전환하기 위해 소류지로 유입되는 총인부하량 ($L_p$)과 호소깊이/체류시간 ($H/{\tau}w$)값의 변화를 통해 현실적으로 적용 가능한 제어방법을 제안하였다. 이와 같은 분석기법이 소류지내 총인농도의 제어전략을 수립하기에 적합한 도구로 사용될 수 있음을 확인하였다.

• Journal of Microbiology and Biotechnology
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• 제24권11호
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• pp.1464-1472
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• 2014

The microbial community structures of two continuous stirred tank reactors digesting turkey manure with pine wood shavings as well as chicken and swine manure were investigated. The reactor fed with chicken/swine wastes displayed the highest organic acids concentration (up to 15.2 g/l) and ammonia concentration (up to 3.7 g/l ammonium nitrogen) and generated a higher biogas yield (up to $366ml/g_{VS}$) compared with the reactor supplied with turkey wastes (1.5-1.8 g/l of organic acids and 1.6-1.7 g/l of ammonium levels; biogas yield was up to $195ml/g_{VS}$). The microbial community diversity was assessed using both sequencing and profiling terminal restriction fragment length polymorphisms of 16S rRNA genes. Additionally, methanogens were analyzed using methyl coenzyme M reductase alpha subunit (mcrA) genes. The bacterial community was dominated by members of unclassified Clostridiales with the prevalence of specific clostridial phylotypes in each reactor, indicating the effect of the substrate type on the community structure. Of the methanogenic archaea, methanogens of the genus Methanosarcina were found in high proportions in both reactors with specific methanosarcinas in each reactor, whereas the strict hydrogenotrophic methanogens of Methanoculleus sp. were found at significant levels only in the reactor fed with chicken/swine manure (based on the analyses of 16S rRNA gene). This suggests that among methanogenic archaea, Methanosarcina species which have different metabolic capabilities, including aceticlastic and hydrogenotrophic methanogenesis, were mainly involved in anaerobic digestion of turkey wastes.

• 한국안전학회지
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• 제20권3호
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• pp.84-90
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• 2005

Thermal decomposition of the copolymer of ${\alpha}$-Methylstyrene(AMS) with Acrylonitrile(AN) was investigated. The copolymer was synthesized in a continuous stirred tank reactor(CSTR) at $80^{\circ}C$ using toluene and benzoyl peroxide(BPO) as solvent and initiator, respectively. The reactor volume was 0.3 liters and residence time was 3 hours. The activation energy of thermal decomposition was in the ranges of $34{\sim}54$ kcal/mol for AMS with AN copolymer. The thermogravimetric trace curves were well agreed with the theoretical calculation.

• 한국안전학회지
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• 제24권1호
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• pp.21-25
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• 2009

Extinguishing limits of laminar ethylene/oxygen flames in both normal and inverse co-flow jet burner have been determined experimentally and computationally. An inert gas($N_2$, Ar, $CO_2$) was added into the oxidizer to find the critical concentration and the effectiveness of the agents on flame extinction. The experimental results showed that the physical aspect of inert gases was main mechanism for flame blow-out as same as cup burner test, but the flow effect should be considered to determine the extinction concentration. The numerical prediction was performed with modified WSR model and the result was in good agreement with the measurements. The experimental and numerical methods could be used for the assessment of various flame suppression agents such as minimum extinguishing concentration.

• KSBB Journal
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• 제20권6호
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• pp.458-463
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• 2005

Polyurethane foam이 충진된 trickle bed reactor에서 통성혐기성 미생물인 Citrobacter amalonaticus Y19을 이용하여 일산화탄소와 물로부터 연속적인 수소생산을 살펴보았다. C. amalonaticus Y19은 설탕을 탄소원으로 할 때 호기적 조건에서 13 g/L까지 성장하였고 혐기조건에서 CO 가스를 주입하였을 때 약 60시간만에 최대 수소 생산 활성을 나타내었다. TBR 반응기에서 유입가스의 CO의 분압이 증가할수록 혹은 기체 체류시간이 감소할수록 수소 생성속도가 증가하였으나 CO의 전환율은 반대로 감소하였다. 그러나 액상의 유속변화는 반응기 운전 결과에 큰 영향을 주지 못했다. 본 실험에서 얻은 최대 수소 생성속도는 기체 체류시간 25분, 유입 CO 압력 0.4 atm에서 16 mmol/L/hr(전환율 33%)이었다. 이 값은 비슷한 반응기에 대해 보고된 Cowger의 결과보다 약 2배 이상 높은 값으로 통성혐기성균주의 고농도 배양과 다공성 충진물의 사용에 의한 높은 기-액 물질 전달 속도가 그 원인으로 추정되었다.

• Journal of Advanced Marine Engineering and Technology
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• 제39권6호
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• pp.633-641
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• 2015

선박, 발전소, 석유화학 등의 분야에서 운전되고 있는 많은 프로세스들은 강한 비선형성을 보일 뿐만 아니라 동시에 시변 특성도 가지고 있다. 이런 프로세스에 기존의 고정-파라미터 PID 제어기를 적용하면 성능이 나빠지고 경우에 따라서는 불안정해질 수도 있다. 따라서 본 연구에서는 복잡한 프로세스를 제어하기 위한 비선형 PID 제어기를 제안한다. 제안되는 제어기의 이득은 오차와 오차의 변화율의 비선형 함수로 기술되며, 사용자 파라미터들은 ITAE를 최소로 하는 관점에서 유전알고리즘으로 동조된다. 제안된 방법은 열분해반응 또는 촉매를 이용한 고분자합성에 널리 사용되는 연속 교반탱크반응기를 대상으로 시뮬레이션을 실시하며, 그 유효성을 보이기 위해 다른 두 비선형/적응 제어법과 비교한다.