• 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.

• 대한안전경영과학회지
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• 제16권2호
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• pp.185-192
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• 2014

The production type of foundry industry is a small quantity batch production methods that require the highly skilled technology in the global competition in the variety of customer needs and directly under the influence of fluctuations characteristic. Therefore suitability for small quantity batch production and flexible production capacity and price competitiveness is needed more than anything. To do this, we need transcription and comprehensive innovation activities to maximize the revenue structure of the organization and field survival foundation should be developed the TPI(Total Profit Innovation) process in all aspects of the organization and all employees are involved in order to create a cost, quality, time, and service part of the overall aim how to achieve those effects within a short period of time. We applied the TPI process for S company in the foundry business innovation and productivity through cost reduction. We will expect the productivity improvement and financial performance improvement and then continually accumulate and review the results.

• 한국환경과학회지
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• 제28권11호
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• pp.927-933
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• 2019

A lipid-enriched strain of Botryococcus braunii (UTEX 572) was cultivated in a semi-batch aeration tank to enhance biomass as well as to develop intracellular lipids and fatty acids. A 30 day period of incubation produced 1.39 g/L of biomass and 0.31 g/L of total lipids in the biomass. The grown biomass was pre-treated using several methods to extract the total lipid content efficiently: ultrasonication was found to yield the highest percentage of lipids-namely 19.8% per biomass. Direct heating of biomass in an autoclave also showed better performance than when using only conventional solvent extraction. To enhance the biomass harvest and lipid extraction efficiency, coagulation and flocculation steps were added to the extraction process. It is noteworthy that not only the solvent type but also the solvent/biomass ratio greatly affected efficiency. In addition, the moisture content of the harvested(wet) biomass affected the efficiency significantly. This study elucidated the need for future research on optimizing this extraction process.

• 한국산학기술학회논문지
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• 제20권3호
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• pp.35-42
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• 2019

회분식 축합반응에 의하여 폴리에스터 수지를 제조하는 중 소규모 화학 공장에 대하여 공정안전관리제도 (PSM)의 시행에 활용되는 위험성평가 방법들 중의 하나인 K-PSR 기법을 이용하여 위험성 평가 및 분석을 진행하였다. K-PSR 기법은 중 소규모 화학공장에 대한 위험성 재평가 시에 나타나는 인프라 부족에 의한 어려운 점을 보완하기 위하여 KOSHA에서 개발한 위험성 평가 기법이다. K-PSR 기법을 적용하기 위하여 선택된 화학 공장의 전체 공정을 축합반응공정과 희석/여과 공정의 2 개의 검토구간을 설정하고, 이에 대한 4가지 가이드워드(누출, 화재 폭발, 공정 트러블, 및 상해)를 기초로 하여 공정상의 잠재위험을 찾아내어 분류하였다. 연구의 결과로서, 위험도 등급을 고려한 안전조치로는 첫째, 누출 및 화재 폭발의 잠재 위험성을 예방하기 위한 구체적인 조치로서는 노후설비에 대한 비파괴 검사 및 전기설비의 LOTO 절차서의 마련이 반드시 필요한 것으로 확인되었다. 둘째, 열매체 공급 배관에는 압력계 및 온도계를 설치하여 공정 트러블을 최소화하고, 마지막으로 국소배기장치를 설치하여 잠재적인 상해를 예방해야 함을 알 수 있었다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2008년도 추계학술대회 논문집
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• pp.307-308
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• 2008

• 한국산업정보학회논문지
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• 제12권2호
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• pp.16-23
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• 2007

Tandem queueing systems well suit for modeling many telecommunication systems. Recently, very general $BMAP/G/1/N/1{\to}{\bullet}/PH/1/M-1$ type tandem queues were constructively studied. In this paper we illustrate application of the obtained results for optimization of a buffer pool design.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2000년도 추계학술대회 논문집
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• pp.128-131
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• 2000

The technology of incremental forming has drawn attention for small-batch production of sheet metal components. In the present investigation a forming tool containing a freely-rotating ball was developed and applied to forming experiments. Deformation characteristics including crack occurred during forming with this tool was examined for full annealed Al1050 sheet. The finite element analysis was successfully applied to this special type of forming process, and provided results that agree well with the measurements.

• 한국환경보건학회지
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• 제20권2호
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• pp.22-27
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• 1994

This study is to discuss the factors influenced on the removal efficiency of a high-strength organic wastewaters investigated using the polypropyrene media which appropriate to attach microorganism in the tube type fixed biofilter reactor. The results obtained in the experiment were as follows: 1. The kinetics of reaction rate (k') were 0.125, 0.135, 0.155 varing initial COD 720, 1280, 1630 mg/l in batch reactor. 2. In the range of pH 4.0 ~12.0 was obtained the removal efficiency of COD higher than 85%. It was proved that variation of pH (4.0 ~12.0) was nothing to do with the removal efficiency of substrate in continuous reactor. 3. Temperature to obtain removal efficiency of COD higher than 85% was 10 ~ 40$\circ$C. Removal efficiency of COD was no less than those at high temperature. 4. In the continuous reactor, the volumetric loading of COD for removal efficiency higher than 95% had to be 0.5~1.5 kg COD/m$^3$.d below. And then the HRT was 8 hrs. 5. In comparison with the activated sludge process, the tube type fixed biofilter process was excellent in removal efficiency of substrate and sludge production rate.

• 산업경영시스템학회지
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• 제20권44호
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• pp.153-161
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• 1997

This paper has proposed the modelling by simulation in order to evaluate the performance of process through discrete event simulation using SIMAN language in flexible manufacturing systems. The production system is assumed to be a job shop type of system under the batch production of discrete products. In this paper, the input data is the workstation(process) time, the number of workstation(process), a probability distribution, the number of simulation runs. Also, transient period is considered. In the case study, this paper deals with three products in real flexible manufacturing systems. Finally, a number of simulation runs were executed under different experimental conditions to obtain preliminary statistics on the following performance measures: operating rate of facility and average system operating rate, transient period, central processing unit, average system throughput, and average waiting time in queues.

• 대한산업공학회지
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• 제24권4호
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• pp.559-569
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• 1998

Cellular manufacturing system (CMS) has been recognized as an alternative to improve manufacturing productivity in conventional batch-type manufacturing systems through reducing set-up times, work-in-process inventories and throughput times by means of group technology. Most of the studies on the design of CMS assumed that each part has a unique process plan, and that its demand is known as a deterministic value despite of the probabilistic nature of the real world problems. This study suggests an approach for designing CMS, considering both alternative process plans and uncertain demand. A mathematical model is presented to show how to minimize the expected amortized and operating costs satisfying these two relaxations. Four heuristic algorithms are developed based on tabu search which is well suited for getting an optimal or near-optimal solution. Example problems are carried out to illustrate the heuristic algorithms and each of them is compared with the deterministic counterpart.