• 한국물환경학회지
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• 제33권3호
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• pp.302-310
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• 2017

The morphological characteristics of granules developing in anaerobic-anoxic (An-Ax) and anaerobic-aerobic (An-Ox) sequencing batch reactors (SBRs) were examined. The granules developed in the both SBRs after 200 days of laboratory operation. The average diameters of the granules were $2.2{\pm}1.7mm$ in the An-Ax SBR and $0.4{\pm}0.3mm$ in the An-Ox SBR. To determine the possible factors affecting morphology of granules a comparative analysis of various operating conditions from reference data indicated that the availability and type of electron acceptors is a key factor determining the granulation process and granular morphology.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 춘계학술대회 논문집
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• pp.119-122
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• 2005

In this study, the design simulation for optimal wire batch around service line was made to improve the dielectric strength at the primary winding using Finite Element Method. The automatic convergence algorithm for finding of limit object value using loop circulation method was developed to make the optimal design simulator. The modulation method was suggested to make division time faster which was very important for full simulation efficiency. As a result, the simulation time was reduced and the optimal wire batch design was obtained.

• 해양환경안전학회지
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• 제2권1호
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• pp.67-75
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• 1996

An innovative batch electrolytic system consisted of electrolytic basin, which was equipped with DSA(Dimensionally Stable Anode) type insoluble electrode, Ti/IrO2 anode and H-C metal cathode, and flotation separator was developed for the efficient treatment of shipboard emulsified oily wastewater. The electorod cleance and current density of elecrolytic basin to ensure maximum treatment efficiency of oily wastewater was evaluated as 6 mm, 3 A/dm3, respectively. The electrolytic efficiency of oily wastewater was affected by the operationtemperature, and it means that the temperature controller to ensure the stabiity of the process is required. The conductivity in the electrolytic basin was increased with the percentage of sea water in the oily wastewater, and over 90% of treatment efficiency of oily wastewater could be obtained at 7% of sea water. The oil removal rate was increased according to the increase of the quantity of electricity, and the maximum value of electrilyic rate constant was 288 mgoil/A.min. The information obtained from this study might be used for development of an efficient continuous electrolytic system treating the emulsified oily wastewater.

• Journal of Microbiology and Biotechnology
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• 제29권3호
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• pp.392-400
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• 2019

Chondroitin, the precursor of chondroitin sulfate, which is an important polysaccharide, has drawn significant attention due to its applications in many fields. In the present study, a heterologous biosynthesis pathway of chondroitin was designed in a GRAS (generally recognized as safe) strain C. glutamicum. CgkfoC and CgkfoA genes with host codon preference were synthesized and driven by promoter Ptac, which was confirmed as a strong promoter via GFPuv reporter assessment. In a lactate dehydrogenase (ldh) deficient host, intracellular chondroitin titer increased from 0.25 to 0.88 g/l compared with that in a wild-type host. Moreover, precursor enhancement via overexpressing precursor synthesizing gene ugdA further improved chondroitin titers to 1.09 g/l. Chondroitin production reached 1.91 g/l with the engineered strain C. glutamicum ${\Delta}L-CgCAU$ in a 5-L fed-batch fermentation with a single distribution $M_w$ of 186 kDa. This work provides an alternative, safe and novel means of producing chondroitin for industrial applications.

• 산업경영시스템학회지
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• 제39권4호
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• pp.7-14
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• 2016

Unlike most researches that focus on single manufacturer or single buyer, this research studies the cooperation policy for two participants of supply chain such as single vendor and single buyer. Especially, this paper deals with single vendor-single buyer integrated-production inventory problem. If the buyer orders products, then the vendor will start to make products and then the products will be shipped from the vendor to the buyer many times. The buyer is supposed to order again when the buyer's inventory level hits reorder point during the last shipment and this cycle keeps repeated. The buyer uses continuous review inventory policy and customer's demand is assumed to be probabilistic. The contribution of this paper is to present a mixed approach and derive its cost function. The existing policy assumes that the size of shipping batch from single vendor to single buyer is increasing, called Type 1, or constant, called Type 2. In mixed approach, the size of shipping batch is increasing at the beginning part of the cycle, and then its size is constant at the ending part of the cycle. The number of shipping for Type 1 and Type 2 in a cycle in mixed approach is determined to minimize total cost. The relationship between parameters, for example, the holding cost per product, the set up cost per order, and the shortage cost per item and decision variables such as order quantity, safety factor, the number of shipments, and shipment increasing factor is figured out via sensitivity analysis. Finally, it is statistically proved that the mixed approach is superior to the existing approaches.

• 경영과학
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• 제13권2호
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• pp.25-48
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• 1996

Mixed Model Assembly Lines (MMALs) are increasingly used to produce differentiated products on a single assembly line without work-in-process storage, Usually, a typical MMAL consists of a number of (1) stations doing exactly the same operation on every job, (2) stations involving operations with different choices, and (3) stations offering operations that are not performed on every job, or that are performed on every job but with many options. For stations of the first type there is no sequencing problem at all. However, for the second type a set-up cost is incurred each time the operation switches from one choice to another. At the third type of stations, different models, requring different amounts and choices of assembly work, creates an uneven flow of work along the line and variations in the work load at these stations. When a subsequence of jobs requires more work load than the station can handle, it is necessary to help the operations at the station or to complete the work elsewhere. Therefore, a schedule which minimize the sum of set-up cost and utility work cost is desired. So this study has developed Fixed Random Ordering Rule (FROR), Fixed Ascending Ordering Rule (FAOR), Fixed Descending Ordering Rule, and Extended NHR (ENHR). ENHR is to choose optimal color ordering of each batch with NHR, and to decide job sequence of the batch with it, too. As the result of experiments, ENHR was the best heuristic algorithm. NHR is a new heuristic rule in which only the minimum addition of violations from both partial sequence and unassigned sequence at every branch could be considered. And this is a heuristic sequencing rule for the third type of stations at MMAL. This study developed one more heuristic algorithm to test the performance of NHR, which is named as Practical Heuristic Rule (PHR).

• 한국식품과학회지
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• 제37권2호
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• pp.318-320
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• 2005

Lactobacillus reuteri는 사람과 동물의 장관 내에 존재하는 유산균의 일종으로서 혐기적 조건에서 glycerol을 대사하여 항균 물질인 루테린을 생산한다. 본 연구의 목적은 고정화된 L. reuteri를 이용하여 회분식 또는 연속식 생산 공정을 이용하여 루테린 생산의 반응 조건을 조사하는데 있었다. Agarose를 사용하여 고정화된 L. reuteri는 250mM glycerol과 반응시켜 루테린을 생산하였다. Agarose 농도를 0.5%로 조정한 회분식 생산 공정에서는 약 36시간 동안 루테린 생산이 지속되었고 시간 경과에 따라 루테린의 생산이 점차 감소하였다. 연속식 공정에서는 고정화 균이 현탁세포에 비하여 루테린 생산 시간이 약 2배 정도 연장되었으며 총 루테린의 생산 또한 502mM로 현탁 세포에 비하여 약 1.5배 증가하였다. 본 연구의 결과는 고정화 세포를 이용한 루테린 생산의 증가 가능성을 제시하였다.

• 한국물환경학회지
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• 제24권6호
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• pp.670-675
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• 2008

Batch type adsorption and desorption tests were performed with different types (Powder, Granule) of Layered double hydroxides (LDHs) saturated with phosphate. The adsorption isotherm was approximated as a modified Langmuir type equation. The maximum adsorption capacity was 55 mg-P/g-LDH for powder type LDH, and 46 mg-P/g-LDH for granule type LDH. The highest phosphate desorption (79.6%) was obtained with 20% NaOH solution, whereas the desorption degrees were 4.8, 22.2% and 46.7% in the solutions of acidic condition (pH 4), 30% NaCl, and 3% NaOH, respectively. It was suggested that the optimal condition for the phosphate desorption from LDH was 30% NaCl + 3~6% NaOH solutions. The desorption characteristics of LDH was little influenced by adsorbent type.

• KSBB Journal
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• 제18권4호
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• pp.249-254
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• 2003

Candida magnoliae M26에 의한 erythritol의 산업적 생산을 위한 산업용 질소원의 선정과 이를 이용한 유가식 배양에서의 erythritol 생산을 위한 최적 조건의 결정에 대한 실험을 수행하였다. 실험결과에서 산업용 질소원으로 가격이 가장 저렴하면서 erythritol의 수율과 생산성이 거의 yeast extract와 유사한 light steep water (LSW)를 선정하였다. 즉 선정한 LSW 43.3 mL/L과 glucose 250 g/L을 이용한 회분식 발효에서 52.6％의 수율과 0.52 g/L-hr의 생산성으로 131.6 g/L의 erythritol을 생산하였다. 생산성 향상을 위한 2단계 유가식 배양에서 고농도 균체를 얻기 위한 최적이 C/N ratio는 1.7으로서 glucose 100 g/L와 LSW 500 mL/L를 이용한 회분식 배양에서 71.0 g/L의 세포농도를 얻을 수 있었다. 배지의 초기 pH 조절방법에 대한 연구에서는 28％ 암모니아 용액으로 pH 6.5로 조절할 경우 erythritol의 수율은 감소하였으나 높은 생산성으로 erythritol을 얻을 수 있었다. 따라서 erythritol의 수율 향상을 위한 생산단계에서의 최적 glucose 농도는 450 g/L이 되도록 하는 경우이며, 이때에 37.3％의 수율과 1.66 g/L-hr의 생산성으로 185.5 g/L의 erythritol을 생산할 수 있었다. 따라서 산업용 질소원으로 선정된 LSW를 이용한 2단계 유가식 발효 공정을 통하여 회분식 배양과 비교해 볼 때 수율은 1.4배 정도 감소되었지만 erythritol의 생산성은 3.2배로 향상시킬 수 있었다.

• Korean Chemical Engineering Research
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• 제54권4호
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• pp.437-442
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• 2016

재활용 PET (Poly ethylene terephthalate)로부터 PBT (Poly butylene terephthalate)를 생산할 수 있는 새로운 방법을 모색하였다. 이 방법은 PET와 BD (1,4-butanediol)의 에스테르 교환반응을 통하여 BHBT (Bishydroxybutylterephthalate) 올리고머를 생성하는 글리콜리시스 반응과 BHBT의 축합 중합 반응을 통하여 PBT 올리고머를 생성하는 축중합 반응으로 이루어져 있다. 이를 통해 단기 수명 주기 제품인 버려지는 PET 페자원을 장기 수명 주기 제품인 PBT로 변환시켜 더 가치 있고 바람직한 재활용을 하고자 하였다. 본 연구에서는 글리콜리시스와 축중합 촉매로 zinc acetate를 사용하였고, 글리콜리시스 반응에 대하여 회분식 반응기와 반 회분식 반응기를 적용하여 성능을 비교하였다. 이를 위하여 생성되는 에틸렌글리콜(EG)의 양을 정량하여 해중합도를 추정할 수 있는 EG 수율과 부산물인 THF 생성량을 성능 척도로 하였다. 반응 도중에 EG를 제거하는 반회분식 반응기의 성능이 회분식 반응기에 비하여 보다 우수한 것으로 나타났다. 또한 반회분식 반응기의 경우 최적의 반응조건은 BD/PET 비율 4, 반응온도 $220^{\circ}C$ 이었으며, 최고 EG 수율은 91% 이었다. 또한 축 중합 반응이 진행됨에 따라 PBT 올리고머의 분자량이 증가하는 것을 보였다.