• 한국정밀공학회지
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• 제18권1호
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• pp.139-146
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• 2001

This paper presents a study on heat transfer and residual distortion analysis of laser welded EDFA(Erbium Doped Fiber Amplifier) LD(Laser Diode) Pump using the finite element method. In the production process of LD Pump in light-wave communication system, ferrule and saddle are welded by Nd-YAG laser. These parts experience thermal and mechanical effect during heating and cooling cycle with the laser welding. Thus distortion happens in the laser-welded packaging, and it makes an error in detecting the light signal translate through optical fiber in LD Pump. The amount of final displacement produced by the laser welding is predicted using the finite element method. And the optimal shape of saddle is proposed with the results of numerical analyses to minimize the displacement.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.346-349
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• 2001

Nowadays the amount of plastic products is increasing in modern industry. Plastic materials are continuously developed to satisfy the mechanical, physical, and chemical properties. The increasing application of plastic parts in automobile and aerospace industries is due to the fact that it can reduce the structural weight and can lessen the environmental contamination. Among many manufacturing technologies for plastic parts, the injection molding process is very attractive because of its low cost and short production time. Through various analyses of resin flow and molding process for the conventional gate and cooling mechanism, a new type of mold was designed which had different gate location and cooling systems. Newly designed ball seat has an excellent performances, i.e. diminished weld-line, residual stress density, higher magnitude less crack propagation and smaller dimensional contractions effect.

• Journal of Plant Biotechnology
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• 제3권2호
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• pp.107-112
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• 2001

The kinetics of Ti-transformed Salvia miltiorrhiza cell cultures was studied in 250-$m\ell$ shake flasks by using B5 medium with addition of 30 gfL of sucrose. In the cell cultures, the maximum cell mass obtained was 11.5 g DW/L on day 15. The highest amount of phenolic compounds - rosmarinic acid (RA) and lithospermic acid B (LAB) reached 871.3 mg/L (day 15) and 121.3 mg/L (day 13), respectively. The total tanshinone production, i.e., intracellular plus extracellular cryptotanshinone, tanshinone 1, and tanshinone IIA, was 5.3 mg/L on day 13. For the cultivations in 2.4-L stirred bioreactors, the residual sugar level and medium conductivity were a little higher in a small turbine impeller reactor ($T_s$) than those in a large turbine impeller reactor ($T_L$), while a higher cell density was obtained in the $T_L$. For the production of tanshinones and phenolics, better results were obtained in the $T_L$ than in the $T_s$. In the $T_L$, similar or even a little higher production titers of tanshinones and phenolic compounds were achieved compared to those in the flasks. The results suggest that the shake flask results could be successfully scaled up to the $T_L$ reactor. Such a large impeller reactor like $T_L$ may be better than a small impeller one for the large-scale production of the valuable metabolites by the suspension cultures of Ti transformed S.miltiorrhiza cells. This is considered due to the beneficial culture environment in the $T_L$, such as low shear rates as estimated theoretically.

• Journal of Applied Biological Chemistry
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• 제42권3호
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• pp.140-145
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• 1999

Livestock manure is generally beneficial to soil and crop production when appropriate amount is applied, but excessive application may be detrimental to soil and water environments. A proper protocol of livestock waste treatment is required to manage the quality of soil and water. A trickling filter system using rice straw media was employed to treat piggery wastewater from small-scaled livestock farms as an alternative to the currently available methods. Batches of piggery wastewater were treated with this system, and the byproducts of rice straw media and trickling filtrate were applied to the soil with cultivating rye (Secale cereale L.). Objective of this research was to characterize these byproducts for the sustainable soil amendments and rye production. Both the treated straw medium and filtrate were proven to be effective organic fertilizers for rye plant development, with the enhanced but balanced absorption of nutrients. The synergistic effects of filtrate in addition to straw application did not show, but the filtrate appeared to lead to a higher water content of the plant. No specific nutrient deficiency or toxicity symptom was shown due to the salts derived from the byproducts applied. Chemical parameters of the soil quality were significantly improved with the application of straw medium either with or without the filtrate. Judging from parameters relating to the salt accumulations, such as sodium adsorption ratio (SAR), electrical conductivity (EC), exchangeable sodium percentage (ESP), potassium adsorption ratio (KAR), and residual P concentrations, the byproducts from piggery wastewater exhibited no detrimental effects on soil quality within the ranges of treatments used. In addition to the effectiveness of the rice straw trickling filter system for the small-scaled swine farms, both rice straw medium and filtrate could be recycled for the sustainable soil amendment and plant nutrition.

• Journal of Electrochemical Science and Technology
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• 제13권2호
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• pp.186-198
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• 2022

Heavy metals recovery from Printed Circuit Boards industrial wastewater is crucial because of its cost effectiveness and environmental friendliness. In this study, a copper recovery route combining the sequential processes of acid leaching and LIX 984N extracting with an electrowinning technique from Printed Circuit Boards production's sludge was performed. The used residual sludge was originated from Hanoi Urban Environment One Member Limited Company (URENCO). The extracted solution from the printed circuit boards waste sludge containing a high copper concentration of 19.2 g/L and a small amount of iron (0.575 ppm) was used as electrolyte for the subsequent electrolysis process. By using a simulation model for multi-step current electrolysis, the reasonable current densities for an electrolysis time interval of 30 minutes were determined, to optimize the specific consumption energy for the copper recovery. The mathematical simulation model was built to calculate the important parameters of this process.

• 소성∙가공
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• 제21권7호
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• pp.397-402
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• 2012

The flange hub is a main component in an automotive steering system. In general, the flange hub are fabricated by mechanical machining, which is a process where material waste is inevitable. It is well-known that a net-shape cold forging cannot only reduce material waste but can also improve the mechanical strength of the final product. Thus, a forging process design was conducted for production of a flange hub. Significant spring-back occurs around the flange due to its small thickness in conjunction with the residual stresses after forging. In order to achieve the required dimensional accuracy, a process design with appropriate spring-back control is needed. In this study, a modification of the forging die was designed based on FE analysis with the purpose of spring-back compensation. Four kinds of different die designs were evaluated and the optimum design has two times less spring-back than the initial design. The compensation angle of the optimum design is 0.5 degrees. The results have been experimentally confirmed by cold forging of a flange hub and comparing the amount of spring-back between the actual component and the FE analysis.

• 한국미생물·생명공학회지
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• 제8권2호
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• pp.77-85
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• 1980

Protease의 생산능이 우수한 Asp. oryzae KC-15를 선정하고 다음과 같은 결과를 얻었다. 1. Wheat bran medium에서의 최적배양시간은 acid protease와 neutral protease는 약 48시간, alkaline protease는 약 72시간이었고 본 균주가 생산하는 protease는 alkaline protease와 neutral pro-tease가 주체이며 acid protease는 극히 미약하였다. 2. Wheat bran medium 에 $Na_2$HPO$_4$, NaH$_2$PO$_4$, Glucose, rice powder 및 Na-glutamate의 첨가는 alkaline protease와 neutral psotease의 생산에, (NH$_4$)$_2$HPO$_4$, glucose 및 rice powder의 첨가는 acid protease의 생산에 효과적이었다. 3. 조효소의 특징(equation omitted) 4. 내열제로서 NaH$_2$PO$_4$가장 효과적이었으며 최적첨가량은 alkaline protease와 neutral protease 에 대하여는 10mg, acid protease에 대하여는 5mg 이었다. 5. 6$0^{\circ}C$ 이상에서는 NaH$_2$PO$_4$의 내열효과는 거의 인정할 수 없었다. 6. NaH$_2$PO$_4$10mg을 첨가하고 55$^{\circ}C$에서 30분간 처리하였을 때의 잔존활성은 alkaline protease는 약 58%, neutral protease는 약 57%, acid protease는 약 55 %이었다.

• 원예과학기술지
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• 제34권1호
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• pp.77-83
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• 2016

생체중은 작물 생육의 중요한 지표이기 때문에 계획 생산을 위해서는 반드시 측정이 필요하다. 비파괴적으로 생체중을 측정하기 위하여 이미지 기반의 방법 들이 개발되어 왔으나 한계점을 가지고 있다. 또한 수경재배에서는 양액의 중량 때문에 작물 생체중을 직접 측정하기에 어려움이 있다. 본 연구의 목적은 NFT 방식의 식물공장에서 생육시기에 따른 생체중을 실시간으로 정확하게 측정할 수 있는 방법을 개발하는 것이다. 식물공장 모듈에서 로메인 상추를 재배하며 실험을 진행하였다. 정식 후 7일 간격으로 28일 까지 전체 채널의 중량, 채널 내에 남아 있던 양액의 양, 로메인 상추의 지상부와 지하부의 생체중을 측정하였다. 특히, 양액이 공급 중일 때 채널의 초기 무게(Wi)와 양액 공급을 중단한 후에 채널의 중량 변화를 매초 간격으로 측정하였다. 채널을 통해 더 이상의 배액이 발생하지 않을 때, 채널의 최종 중량(Ws)와 채널에 잔류하고 있는 양액의 양을 측정하였다. 시상수(${\tau}$)는 Wi와 Ws의 변화 추세를 고려하여 계산되었다. Wi, Ws, ${\tau}$와 실제 생체중과의 관계를 정량적으로 분석하였다. 양액 공급을 멈춘 뒤 채널의 중량은 지수적으로 감소하였다. 채널 내 지하부의 중량이 증가하면서 양액이 채널을 빠져나가는 속도는 감소하였다. 실제 작물의 생체중과 채널의 중량을 통하여 예측된 생체중 사이에는 큰 차이가 있었고, 이는 채널 내에 잔류된 양액 때문이다. 이러한 차이는 생육시기에 따라 예측하기에는 어려웠으나 시상수를 이용한 모델식은 높은 예측성을 보였다. Wi, Ws, ${\tau}$를 사용한 모델을 이용하면 작물의 실제 생체중을 추정할 수 있으리라 기대된다.

• Asian-Australasian Journal of Animal Sciences
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• 제31권5호
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• pp.748-754
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• 2018

Objective: The preference evaluation of cattle is an important factor for estimation and improvement of the grazing amounts of newly introduced or bred grasses or cultivars in barn. This study was performed to assess the grazing behavior (the amount of grazing and/or the grazing speed) of cattle as indirect method using newly bred Brachiaria ruziziensis tetraploid strain 'OKI-1'(BR) hay as treatment group and Cloris gayana 'Callide' (CG) hay as control group. It also compared the feasibility of using behavioral differences between two groups as one criteria for evaluating preference by Japanese black cattle in barn. Methods: Three experiments were carried out using 12 growing Japanese Black cattle including 6 males and 6 females. In each experiment, the four Japanese Black cattle (2 males and 2 females) were placed in separated stall and allowed to graze BR and CG in manger that was separated into two portions for about 30 min. The position and behavior of the cattle were recorded, and weighed the residual of each gay at 15 and 30 minutes after experiment start. Results: The BR was superior to CG in chemical composition such as protein, fibers and non-fibrous carbohydrate. The cattle, over all, tended to prefer BR over CG in the first half 15 minutes in terms of the time spent and amount of grazing. Additionally, growing cattle exhibited neophilia for BR bred newly. Conclusion: These findings indicated the current approach could be applied for one of criteria to evaluate the preference of hay by Japanese black cattle under indoor housing environment.

• 한국토양비료학회지
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• 제49권3호
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• pp.242-250
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• 2016

Veterinary antibiotics (VAs) has been used to treat animal disease and to increase animal weight as growth promoter. However, abused usage of VAs can cause production of antibiotic resistance genes (ARGs) in the environment and additionally, residual of VAs in soil can be transferred into crops. Therefore, main objective of this research was to examine bioaccumulation of VAs in sprouts (red cabbage, Brassica Olearacea L. var. Capitata f. rubra and red radish, Raphanus sativus) with hydroponic method. Total of 7 VAs in 2 different classes of VAs (tetracyclcines: tetracycline, oxytetracycline, chlortetracycline, sulfonamides: sulfamethoxazole, sulfamethazine, sulfamethiazole, macrolides: tylosin) were evaluated and experiment was conducted with solid phase extraction (SPE)/high performance liquid chromatography tandem mass spectrometry (HPLC/MS/MS). Initial spiked concentration of 7 VAs was $5mg\;L^{-1}$ and cultivation period was 8 days. Result showed that growth of sprouts was inhibited about 23-27% when VAs was introduced. Amount of bioaccumulated VAs was also differed depending on class of VAs. The highest amount of bioaccmulated VAs was tetracycline and sulfamethoxazole in each class with a concentration of 4.05, $7.73mg\;kg^{-1}$ respectively. Calculated transfer ratio of VAs into crops was also ranged 0.38-54.27%. Overall, bioaccumulation of VAs in crops can be varied depending on crop species and class of VAs. However, further research should be conducted to verify bioaccumulation of VAs in crops in the soil environment.