• 제목/요약/키워드: low-temperature pre-treatment

검색결과 106건 처리시간 0.033초

Updated Pretreatment Technologies for Automotive in Japan

  • Takaknwa, Hideki;Ishii, Hitoshi
    • Corrosion Science and Technology
    • /
    • 제6권5호
    • /
    • pp.245-250
    • /
    • 2007
  • Recently, to avoid global warming, reduction of $CO_2$ generation has been demanded. Each car manufacture takes positive actions for improvement in fuel consumption by various kinds of countermeasures, e.g. improving engine efficiency, using alternative fuels, lightening the car body. Regarding lightening of the car body, aluminum alloys and high tensile strength steels has been gradually adopted as lightweight materials. However, such materials are normally not easy to be treated with zinc phosphate system. Focusing the pre-treatment processes, low temperature phosphate system could be demanded for energy saving. This time, new surface conditioning process for lightweight materials and low temperature phosphate system shall be discussed.

Effect of Enzymatic Hydrolysis on Polylactic Acid Fabrics by Lipases from Different Origins

  • Lee, So-Hee;Song, Wha-Soon
    • 한국의류학회지
    • /
    • 제36권6호
    • /
    • pp.653-662
    • /
    • 2012
  • This study measured the effect of general pre-treatment on PLA fabrics to confirm the benefits of enzymatic processing on PLA fabrics in the textile industry as well as evaluated the hydrolytic activities of three lipases. The effects of lipase hydrolysis were analyzed through moisture regain, dyeing ability, tensile strength, and surface morphology. As a result, PLA fibers were easily damaged by a low concentration of sodium hydroxide and a low treatment temperature. The optimal treatment conditions of Lipase from Candida cylindracea were pH 8.0, $40^{\circ}C$, and 1,000 U. The optimal treatment conditions for Lipase from Candida rugosa were pH 7.2, $37^{\circ}C$, and 1,000 U. The optimal treatment conditions for Lipase from Porcine pancreas were pH 8.0, $37^{\circ}C$, and 2,000 U. The moisture regain and dyeing ability of PLA fabrics increased and the tensile strength of PLA fabrics decreased. The results of surface morphology revealed that there were some cracks due to hydrolysis on the surface of the fiber.

배추(Brassica campestris ssp. pekinensis ) 약 배양시 약의 발달 단계, 온도 처리 및 배지의 종류가 배 발생에 미치는 영향 (Effect of Developmental Stage, Temperature, and Medium on Embryogenesis in Anther Cultures of Chinese Cabbage (Brassica campestris ssp. pekinensis))

  • 김태일;황주광;백기엽
    • 식물조직배양학회지
    • /
    • 제22권4호
    • /
    • pp.229-234
    • /
    • 1995
  • 결구배추(Brassica campestris ssp. pekinensis)의 약배양을 통한 반수체의 유기율을 높히고 반수체의 발달과정을 알아보기 위해 본 연구를 수행하였다. 결구배추의 일대잡종 및 순계 의 약을 수정된 B/sb 5/ 배지에 전처리 및 후처리를 하여 액체 및 고체배지에 배양하였다. 접종후 9일부터 13일까지 반수체가 생겼는데 저온처리 효과는 없었으나 고온인 4$0^{\circ}C$ 1시간, 45$^{\circ}C$ 1시간 처리는 반수체 유기율을 높였다. 육성계통간에 따라 유기율이 큰 차이가 있었으며 배지는 큰 차이가 없었다. 후처리 효과는, 35$^{\circ}C$ 1일 처리후 3$0^{\circ}C$ 1일 처리효과가 있었으며 4$0^{\circ}C$ 이상 고온처리는 효과가 없었다. 배양한 약을 단계별로 조직학적으로 관찰한 결과 체세포배 유기는 약내 화분으로부터 유기되는 것을 관찰할 수 있다.

  • PDF

암모니아성질소를 함유한 금강중류 하천수의 오존-활성탄처리 (Ozone-Activated Carbon Treatment in Middle Keum River containing Ammonia-Nitrogen)

  • 김충환;정상기;김학성
    • 한국물환경학회지
    • /
    • 제18권4호
    • /
    • pp.355-363
    • /
    • 2002
  • A demonstration plant was carried out to investigate the removal efficiency of $NH_3-N$ and $KMnO_4$ consumption depending on the existence of pre-chlorination for the ozonation and activated carbon process in the S water treatment plant which is located at the middle of Keum River. The averge removal efficiency of $KMnO_4$ consumption for $O_3/GAC$ processes with pre-chlorination and $O_3/BAC$ processes without pre-chlorination were 48.6% and 50% respectively. It is similar to removal effect of $KMnO_4$ consumption for GAC and BAC process depending on the existence of pre-chlorination. Otherwise, the removal of THMFP for GAC and BAC process was 58% and 68% respectively. $NH_3-N$ was not almost removed by sand filter and ozonation, but the average removal efficiency in the BAC process was about 31%. Especially, $NH_3-N$ was not almost removed by $O_3/BAC$ processes at the low temperature (below $$10^{\circ}C$$) in the winter season, $O_3/BAC$ processes have the advantage of removal of organic substance when it is compared to pre -chlorination followed by $O_3/GAC$ processes. Pre-chlorination followed by $O_3/GAC$ processes were required to remove $NH_3-N$ in the winter season because the removal of $NH_3-N$ was almost ineffective by $O_3/BAC$ process.

Effects of an ice pack and sulfur generating pad treatment for home delivery on the quality of 'Duke' blueberry fruits

  • Lim, Byung-Seon;Choi, Mi-Hee;Lee, Jin-Su
    • 농업과학연구
    • /
    • 제45권4호
    • /
    • pp.811-821
    • /
    • 2018
  • This study focused on the improvement of blueberry delivery service using pre-cooled ice and $SO_2$ pads to prevent an increase in the fruit temperature as well as decay. To maintain the fruit quality during low temperature storage, the effect of a $SO_2$ pad and modified atmosphere packaging was also examined. Harvested blueberries were precooled at $15^{\circ}C$, sorted, and packaged. And the fruits were placed in a similar environment as that for the parcel service. Part of the fruits were stored at $0^{\circ}C$ for long term storage. The air temperature in the delivery box increased along with an increase in the simulated delivery time regardless of the treatment. However, the rate of temperature increase was lower in the ice pad treatment. No significant difference was not found after 48 h. The oxygen concentration in the box ranged between 10.5 - 14.5% in the ice pad treatment, which was higher than that of the untreated control (7.5 - 11.9%) whereas the $CO_2$ concentration was lower in the ice pad treatment. No differences were found in the occurrence of off-flavor, decay, and sensory quality loss during the 48 hours of the parcel service simulation. The combined treatment of the $SO_2$ pad and modified atmosphere packaging (MAP) using a perforated film increased the shelf-life of the blueberry fruits, the overall quality such as firmness, and the soluble solid content was not different between the treatments except for the decay incidence. No decayed fruit was found in the combined treatment. However, the percentage of decayed fruit in the control was 25% on day 15 of storage and 75% on day 33 of storage, respectively.

반탄화 과정을 통한 바이오매스의 소수성 개선 연구 (A Study on the Improved the Hydrophobicity of Torrefied Biomass)

  • 정재성;김경민;정현준;김규보;전충환
    • 한국수소및신에너지학회논문집
    • /
    • 제30권1호
    • /
    • pp.49-57
    • /
    • 2019
  • Biomass, a carbon-neutral fuel, has great advantages because it can replace fossil fuels to reduce greenhouse gas emissions. However, due to its low density, high water content, and hydrophilicity, biomass has disadvantages for transportation and storage. To improve these properties, a pretreatment process of biomass is required. One of the various pre-treatment technologies, torrefacion, makes biomass similar to coal through low-temperature pyrolysis. In this study, torrefacion treatment was carried out at 200, 230, 250, 280, and $300^{\circ}C$ for wood pellet, empty fruit bunch (EFB) and kenaf, and the feasibility of replacing coal with fuel was examined. Hygroscopicity tests were conducted to analyze the hydrophobicity of biomass, and its chemical structure changes were investigated using Infrared spectrum analysis. It was confirmed that the hygroscopicity was decreased gradually as the torrefacion temperature increased according to the hygroscopicity tests. The hydrophilicity was reduced according to the pyrolysis of hemicellulose, cellulose, and lignin of biomass.

정수장 전염소 공정 제어를 위한 침전지 잔류 염소 농도 예측모델 개발 (Prediction Models of Residual Chlorine in Sediment Basin to Control Pre-chlorination in Water Treatment Plant)

  • 이경혁;김주환;임재림;채선하
    • 상하수도학회지
    • /
    • 제21권5호
    • /
    • pp.601-607
    • /
    • 2007
  • In order to maintain constant residual chlorine in sedimentation basin, It is necessary to develop real time prediction model of residual chlorine considering water treatment plant data such as water qualities, weather, and plant operation conditions. Based on the operation data acquired from K water treatment plant, prediction models of residual chlorine in sediment basin were accomplished. The input parameters applied in the models were water temperature, turbidity, pH, conductivity, flow rate, alkalinity and pre-chlorination dosage. The multiple regression models were established with linear and non-linear model with 5,448 data set. The corelation coefficient (R) for the linear and non-linear model were 0.39 and 0.374, respectively. It shows low correlation coefficient, that is, these multiple regression models can not represent the residual chlorine with the input parameters which varies independently with time changes related to weather condition. Artificial neural network models are applied with three different conditions. Input parameters are consisted of water quality data observed in water treatment process based on the structure of auto-regressive model type, considering a time lag. The artificial neural network models have better ability to predict residual chlorine at sediment basin than conventional linear and nonlinear multi-regression models. The determination coefficients of each model in verification process were shown as 0.742, 0.754, and 0.869, respectively. Consequently, comparing the results of each model, neural network can simulate the residual chlorine in sedimentation basin better than mathematical regression models in terms of prediction performance. This results are expected to contribute into automation control of water treatment processes.

저온 플라즈마 침질탄화처리된 마르텐사이트계 석출경화형 스테인리스강의 내식성에 미치는 시효 전처리의 영향 (Effects of Pre-Aging Treatment on the Corrosion Resistance of Low Temperature Plasma Nitrocarburized AISI 630 Martensitic Precipitation Hardening Stainless Steel)

  • 이인섭;이천호
    • 한국표면공학회지
    • /
    • 제53권2호
    • /
    • pp.43-52
    • /
    • 2020
  • Various aging treatments were conducted on AISI 630 martensitic precipitation hardening stainless steel in order to optimize aging condition. Aging treatment was carried out in the vacuum chamber of Ar gas with changing aging temperature from 380℃ to 430℃ and aging time from 2h to 8h at 400℃. After obtaining the optimized aging condition, several nitrocarburizing treatments were done without and with the aging treatment. Nitrocarburizing was performed on the samples with a gas mixture of H2, N2 and CH4 for 15 h at vacuum pressure of 4.0 Torr and discharge voltage of 400V. The corrosion resistance was improved noticeably by combined process of aging and nitrocarburizing treatment, which is attributed to higher chromium and nitrogen content in the passive layer, as confirmed by XPS analysis. The optimized condition is finalized as, 4h aging at 400℃ and then subsequent nitrocarburizing at 400℃ with 25% nitrogen and 4% methane gas for 15h at vacuum pressure of 4.0 Torr and discharge voltage of 400V, resulting in the surface hardness of around 1300 HV0.05 and α'N layer thickness of around 11 ㎛ respectively.

INTERGRANULAR CORROSION-RESISTANT STAINLESS STEEL BY GRAIN BOUNDARY ENGINEERING

  • Hiroyuki Kokawa;Masayuki Shimada;Wang, Zhan-Jie;Yutaka S. Sato
    • 대한용접접합학회:학술대회논문집
    • /
    • 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
    • /
    • pp.250-254
    • /
    • 2002
  • Intergranular corrosion of austenitic stainless steels is a conventional and momentous problem during welding and high temperature use. One of the major reasons for such intergranular corrosion is so-called sensitization, i.e., chromium depletion due to chromium carbide precipitation at grain boundaries. Conventional methods for preventing sensitization of austenitic stainless steels include reduction of carbon content in the material, stabilization of carbon atoms as non-chromium carbides by the addition of titanium, niobium or zirconium, local solution-heat-treatment by laser beam, etc. These methods, however, are not without drawbacks. Recent grain boundary structure studies have demonstrated that grain boundary phenomena strongly depend on the crystallographic nature and atomic structure of the grain boundary, and that grain boundaries with coincidence site lattices are immune to intergranular corrosion. The concept of "grain boundary design and control", which involves a desirable grain boundary character distribution, has been developed as grain boundary engineering. The feasibility of grain boundary engineering has been demonstrated mainly by thermomechanical treatments. In the present study, a thermomechanical treatment was tried to improve the resistance to the sensitization by grain boundary engineering. A type 304 austenitic stainless steel was pre-strained and heat-treated, and then sensitized, varying the parameters (pre-strain, temperature, time, etc.) during the thermomechanical treatment. The grain boundary character distribution was examined by orientation imaging microscopy. The intergranular corrosion resistance was evaluated by electrochemical potentiokinetic reactivation and ferric sulfate-sulfuric acid tests. The sensitivity to intergranular corrosion was reduced by the thermomechanical treatment and indicated a minimum at a small roll-reduction. The frequency of coincidence-site-lattice boundaries indicated a maximum at a small strain. The ferric sulfate-sulfuric acid test showed much smaller corrosion rate in the thermomechanically-treated specimen than in the base material. An excellent intergranular corrosion resistance was obtained by a small strain annealing at a relatively low temperature for long time. The optimum parameters created a uniform distribution of a high frequency of coincidence site lattice boundaries in the specimen where corrosive random boundaries were isolated. The results suggest that the thermomechanical treatment can introduce low energy segments in the grain boundary network by annealing twins and can arrest the percolation of intergranular corrosion from the surface.

  • PDF

산 및 열처리에 따른 오징어의 이화학적 특성변화 (Changes in Physicochemical Characteristics of Squid upon Acid and Heat Treatment)

  • 이혜영;김성호;김덕진
    • 한국식품영양과학회지
    • /
    • 제41권4호
    • /
    • pp.539-549
    • /
    • 2012
  • 본 연구는 오징어 가공식품개발의 기초자료확보를 위하여 산(acetic acid, 0~5%) 처리와 예비가열($55^{\circ}C$, $80^{\circ}C$) 후 열처리($100^{\circ}C$)에 따른 오징어의 이화학적 성분 변화를 조사하였다. 일반성분 함량은 수분이 약 73~78%, 조단백이 약 19~24%였으며 자숙 오징어의 일반성분 함량은 산 농도에 따라서 유의적인 차이가 있었다. 자숙 오징어의 모든 시료에서 주요 유리당은 ribose와 glucose이었으며, $55^{\circ}C$ 예비가열 시료는 다른 시료보다 glucose 함량이 낮은 것으로 나타났다. 총 유리당 함량은 표피 무제거 시료와 $80^{\circ}C$ 예비가열 시료순으로 높았고 $55^{\circ}C$ 예비가열 시료가 상대적으로 매우 낮았다. 모든 시료들의 유리아미노산 함량은 proline 함량이 가장 높았고 taurine, histidine 순으로 많이 함유되어 있었으며, 모든 자숙 오징어군에서 산 용액 처리농도에 따른 유의적인 영향을 보였다(p<0.05). 총 유리아미노산 함량은 $55^{\circ}C$ 예비가열 시료가 가장 높았고 $80^{\circ}C$ 예비가열, 표피 무제거 시료순으로 나타났다. 핵산관련물질은 모든 시료에서 inosine이 검출되지 않았고 ATP 함량이 가장 낮았다. $55^{\circ}C$$80^{\circ}C$ 예비가열 시료는 hypoxanthine 함량이 가장 높고 AMP와 IMP 함량이 비슷한 수치를 보였으나 표피 무제거 시료는 IMP 함량이 표피제거 시료보다 높았다. 지방산은 포화지방산이 약 40%로 palmitic acid 함량이 매우 높았고 불포화지방산은 약 60%로 EPA와 DHA 함량이 높았다. 지방산중 DHA 함량이 가장 높고 palmitic acid, EPA 순으로 나타났으며 이 세 가지가 총 지방산의 약 85%를 차지하고 있었다. 지방산은 산 처리와 가열 방법에 따른 뚜렷한 차이가 나타나지 않았다. 무기질의 함량은 인의 함량이 가장 높았고 칼륨, 나트륨, 마그네슘, 칼슘 순이었으며 예비가열 온도 또는 산 용액 농도에 따른 유의적인 영향을 받았다. 그리고 중금속류인 카드뮴, 납, 비소는 미량으로 나타나 식품 기준치보다 낮은 수준이었다.