• KOREAN JOURNAL OF CROP SCIENCE
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• v.45 no.6
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• pp.382-386
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• 2000

This study was conducted to know the optimum conditions for overwinter culture of sweetpotato stems in PE film house. The stems will be used as transplant shoots in the next year instead of sprouts produced from storage roots. Sweetpotato stems were cut at field on harvest season and planted in PE film house under three different conditions of PE film mulching, tunnel, or mulching plus tunnel in comparison with the non-treatment of PE film on October 10 and November 10. The survival rate of sweetpotato stems, which was evaluated on April 10 after overwinter, was higher in the treatment planted on October 10 than that on November 10, and with PE film treatments, it was higher in tunnel or mulching plus tunnel than that of the non-treatment of PE film. The survival rate of sweetpotato stems to planting densities was 95-96% in 10$\times$2cm (333 stems/$m^2$) or in 10$\times$4cm (250 stems/$m^2$) when compared with 10$\times$2cm (500 stems/$m^2$). The survival rate under low temperature showed 95% until 20 days at 5$\pm$1$^{\circ}C$, and 0% within 5 days at 2$\pm$1$^{\circ}C$. From these results, it was concluded that there were optimum conditions that cutting time is middle October, planting density is 10$\times$3cm, and minimum maintenance temperature is 5$^{\circ}C$ in growing conditions of sweetpotato stems. Root yield produced by trans-planting shoots using the stems was similar to yield by shoots produced from roots, and the survival rate was not different among varieties.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.9
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• pp.624-629
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• 2013

The relation between performance maintenance conditions and those cost efficiency was studied to choose an optimum operating condition in the seawater desalination pretreatment system. A hollow fiber microfiltration module, which was developed with domestic technology, was tested with the various operating conditions such as chemically enhanced backwash cycles and design dosages of a cleaning chemical. Transmembrane pressure was measured to investigate membrane fouling status and cleaning degree. In addition, economic analysis was performed to compare water production costs by the operation condition. As a result, The operation mode III, chemically enhanced backwash at once a day with 100 mg/L of sodium hypochlorite (NaOCl) was selected. The concurrent evaluation between membrane filtration performance and its economic analysis will be suitable to choose an efficient optimum condition.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.6
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• pp.1011-1019
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• 2000

The purpose of this study is to examine the basis of design condition of existing treatment processes, namely, Extended Aeration Process, Conventional Activated Process, High Rate Aeration Process and Modified Aeration Process, by clarifying the correlations of influent wastewater concentration, hydraulic retention time, food-to-microorganism ratio and sedimentation of sludge, as well as to ascertain the feasibility of design, regardless of the existing design condition. In particular, this study made a priority investigation of hydraulic retention time and sludge sedimentation, because sludge sedimentation is the main factor$^{1)}$ which determines the operating conditions of existing treatment processes. Therefore, it is generally known that in case exceeds the sphere of design presented for each treatment, sludge bulking may occur. The results of Lesperance's test$^{1)}$, which formed the basis of design, showed the sphere of loading without security of sludge sedimentation, as in Fig. 1. The reason for sludge bulking in a certain condition, as above, is due to failure in application of optimum loading corresponding to each retention time by employing a few operating condition, which proved to be consecutively workable after years of trials and failures by Lesperance, for test conditions. However, the result of this test showed that in case of proper maintenance of loading. sludge sedimentation can be ensured under 120 SVI. Therefore, this study suggested hydraulic retention time and its corresponding optimum loading, and identified the hydraulic retention time as a determinant of sludge sedimentation. And. on the basis of these findings, this study suggested the feasiblity of UHR(Ultra High Rate), a new operating process, exceeding several times the applicable loading value of High Rate Aeration Process under one hour retention time which has not yet applied to the existing treatment processes.

• Korean Journal of Food Science and Technology
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• v.32 no.5
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• pp.1079-1086
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• 2000

Pectinesterase inhibitor(PEI) of ripened kiwi fruit(Actinidia chinensis) was separated with affinity chromatography using CNBr-activated Sepharose 4B being covalently bound by orange pectinesterse(PE). The affinity resin strongly and selectively bound PEI, which could be eluted in high yield as a single peak by pH 9.5 without loss of inhibitory activity. The separated PEI had maintained almost inhibitory activity at $-25^{\circ}C$ and $5^{\circ}C$ during 30 days but lost it at room temperature in 4 weeks. The PEI possessed a molecular weight of 16.6 KDa, as estimated by 12.5% SDS-PAGE. PEI had optimum pH of 7.5, optimum temperature of below $10^{\circ}C$ and stability up to $70^{\circ}C$. Also, optimum inhibitory activity for PEI was obtained in 0.2 M NaCl of substrate solutions. The kind of inhibition on tomato pectinesterase was found to be noncompetitive, using citrus pectin as substrate. Fresh orange juice added with crude PEI extracts maintained almost the same cloud stability as pasteurized juice. In case of apple juice, the addition of crude PEI extracts to apple juice had decrease of L-ascorbic acid with nearly no effect on cloud loss.

• The Korean Journal of Mycology
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• v.10 no.2
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• pp.75-83
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• 1982

As a primary study for cell growth and alcohol production of a cider yeast, Saccharomyces sp. R-11, cultural and nutritional characteristics of the strain were investigated. The results obtained were as follows: The optimum culture medium for this strain was a synthetic medium, Henneberg B, and sucrose was the best carbon source for yeast growth and alcohol production. Optimum sugar concentrations for yeast growth and alcohol production were 15% and 25%, respectively. Optimum pH and temperature of the basal medium for growth of this strain were 4.5 and $30^{\circ}C$ respectively. The yeast growth was enhanced by the addition of 100 ppm of $Mg^{2+}$, but significantly inhibited by the addition of 100 ppm of $Co^{2+}$. Lower temperature and maintenance of optimum pH for yeast growth increased the final alcohol concentration. Under optimum condition for cell growth at stationary culture, generation time and specific growth rate of the strain were 7.5 hr and 0.092 $hr^{-1}$, respectively. At 8% initial alcohol concentration, yeast growth was inhibited about 50% and this strain could not be grown at more than 12% initial alcohol. The strain could be grown at less than 125ppm $SO_2$without alcohol addition, and at less than 75 ppm $SO_2$ with 8% initial alcohol. The higher sulfur dioxide concentration of a medium, the longer lag phase in yeast growth was observed. This strain could induced alcoholic fermentation at less than 10% initial alcohol concentration with 0 and 25 ppm $SO_2$, at less than 8% initial alcohol with 50 and 75 ppm $SO_2$, and at less than 6% initial alcohol with 100 and 125 ppm $SO_2$.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.3
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• pp.74-81
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• 2013

This research was performed to identify physical properties of polysulfide epoxy polymer concrete for ultra-thin bridge deck pavement, and improve domestic applicability. With the optimum mix ratio determined from mixing experiments of polymer concretes, compressive, flexural, and bond strength were tested to identify its strength properties along with the freezing-thawing resistance test to evaluate its durability in harsh environments. As a result, the tested polymer concretes showed excellent performance in strength and deflection characteristic and all tested strength satisfied the criteria of American Concrete Institute. Moreover, it had better performance under variable temperatures comparing to other existing pavement materials. By the results of freezing-thawing resistance test and strength measurement for specimens underwent the freezing-thawing process, it can be judged that there is no such problem to the concrete's durability. In conclusion, the newly developed polymer concrete in this research has appropriate properties for use in ultra-thin pavement on bridge deck, and moreover it has superior applicability in comparison with former materials due to its improved temperature sensitivity.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.2
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• pp.389-395
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• 2017

A study was carried out to improve the field implementation of asphalt surface reinforcement method which is a preventive maintenance. Mean Texture Depth (MTD) was measured to quantify the surface condition and used to determine the optimum application rate. Determining the application rate using MTD can reduce the material loss from 30% to 15%. In order to reduce the curing time to 30 minutes, the heat capacity of $317kcal/m^2$ is required. Therefore, the design capacity of the heating curing device requires more than 380,000 kcal/hr. The asphalt surface reinforcement method is preferably applied at a time when slight cracking occurs before the permanent deformation becomes serious. Through the analysis of the pavement survey data, it was decided to apply the surface reinforcement method at the crack rate of 3~4%. Heating the surface reinforcement agent to $50^{\circ}C$ improves workability and ensures sufficient penetration depth even at a crack width of 1 mm. The results will be utilized as basic data for the development of automated construction equipment for efficiency improvement.

• International Journal of Highway Engineering
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• v.12 no.3
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• pp.17-26
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• 2010

Maintenance of the roads and bridges is a major issue for all road administrators around the world, and various initiatives are being implemented in each region for the purpose of controlling the ever increasing road maintenance cost while ensuring the safety of the vehicles driving. Efforts for such initiatives have also been made in Asia and initiatives for managing heavy-weight vehicles have recently gained momentum in Korea and Japan. We have developed a technology for unevenly installing bar-shaped sensors (piezo quartz sensors) to enable dynamic axle load measurement at a highly accurate level, and have estimated our measurement accuracy of axle load/gross weight, etc. on an actual road. The measurement accuracy of the axle load/gross weight varies significantly depending on the number of sensors installed. In our implementation, the target accuracy was set to below ${\pm}5%$ for gross weight measurement so that automatic regulation can be applied. We have achieved our target by installing 8-point measurement system. However, to have this technology widely accepted, it was necessary to reduce the system size so that it can be easily implemented. Therefore, we have estimated the relationship between the measurement accuracy and the system size (number of measurement points), and have come up with the proposal of 3-point measurement as an optimum number of measurement points, and have estimated its performance on an actual road. Additionally, we evaluated the relationship between the measurement accuracy and vehicle velocity.

• Radiation Oncology Journal
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• v.13 no.2
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• pp.129-142
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• 1995

Purpose: Traditionally the patients with early stage non-Hodgkin's lymphoma of the head and neck was treated with radiotherapy. But the results were not satisfactory due to distant relapse. Although combined treatment with radiotherapy and chemotherapy was tried with some improved results and chemotherapy alone was also tried in recent years, the choice of treatment for the patients with early stage non-Hodgkin's lymphoma of the head and neck has not been defined Therefore, in order to determine the optimum treatment method, we analysed retrospectively the outcomes of the patients with Ann Arbor stage I and II non-Hodgkin's lymphoma localized to the head and neck who were treated at Severance Hospital. Materials and Methods: 159 patients with stage I and II non-Hodgkin's lymphoma localized to the head and neck were treated at our hospital from January, 1979 to December, 1992. Of these patients, 114 patients whose primary sites were Waldeyer's ring or nodal region, and received prescribed radiation dose and/or more than 2 cycles of chemotherapy. were selected to analyze the outcomes according to the treatment methods ( radiotherapy alone, chemotherapy alone. and combined treatment with radiotherapy and chemotherapy ). Results: Five year overall actuarial survival of the patients whose Primary site was Waldeyer's ring was $62.5\%.$ and that of the Patients whose primary site was nodal region was $53.8\%$ There was no statistically significant difference between survivals of both groups. Initial response rate to radiotherapy. chemotherapy, and combined treatment was $92\%,\;83\%,\;94\%$ respectively, and 5 year relapse free survival was $49.9\%,\;52.4\%,\;58.5\%$ respectively ( statistically not significant ). In the patients with stage I. 3 year relapse free survival of chemotherapy alone group was $75\%$ and superior to other treatment groups. In the Patients with stage II, combined treatment group revealed the best result with $60.1\%$ of 3 year relapse free survival. The effect of sequential schedule of each treatment method in the Patients who were treated by combined modality was analyzed and the sequence of primary chemotherapy + radiotherapy + maintenance chemotherapy showed the best result ( 3 year relapse free survival was $79.1\%).$ There was no significant survival difference between BACOP regimen and CHOP regimen. Response to treatment was only one significant (p(0.005) prognostic factor on univariate analysis and age and mass size was marginally significant ( p(0.1). On multivariate analysis, age (p=0.026) and mass size (p=0.013) were significant prognostic factor for the relapse free survival. Conclusion: In summary, the patients who have non-Hodgkin's lymphoma of the head and neck with stage I and mass size smaller than 10 cm, can be treated by chemotherapy alone, but remainder should be treated by combined treatment method and the best combination schedule was the sequence of initial chemotherapy followed by radiotherapy and maintenance chemotherapy.

• Microbiology and Biotechnology Letters
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• v.17 no.5
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• pp.504-509
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• 1989

Fermentation condition of Streptococcus lactis IFO 12007 for nisin production was examined. The optimal glucose concentration was 60g/ι. The pH and temperature optimum were 6.5 and 31$^{\circ}C$, respectively. The maximum nisin activity in batch culture was 2000IU/$m\ell$. The fermentation quotients after 7 hours of fermentation in batch culture were; specific glucose uptake rate:0.59g/g/h , specific nisin productivity: 34924IU/g/h, product yield: 5944IU/g, growth yield:0.24, biomass:4.81g/ι. The specific growth rate was affected by pH and temperature and the activation energy for growth was 1.35kcal/mole. pH control was essential for nisin production. Fed-batch culture using 20g/$\ell$ glucose medium produced 1420IU/$m\ell$ after 14 hours. The continuous culture could be operated at below 0.38h$^{-1}$ for nisin production. The steady state nisin concentration and specific nisin productivity were 740IU/$m\ell$ and 45000IU/g/h. The growth yield and maintenance energy were 0.144 and 207mg glucose/g-cell/h.