• Journal of Microbiology and Biotechnology
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• v.19 no.1
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• pp.108-112
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• 2009

A simplified method for the purification of cholera toxin was developed. The 569B strain of Vibrio cholerae, a recognized hyper-producer of cholera toxin, was propagated in a bioreactor under conditions that promote the production of the toxin. The toxin was separated from the bacterial cells using 0.2-${\mu}m$ crossflow microfiltration, the clarified toxin was passed through the membrane into the permeate, and the bacterial cells were retained in the retentate. The 0.2-${\mu}m$ permeate was then concentrated 3-fold and diafiltered against 10 mM phosphate buffer, pH 7.6, using 30-kDa crossflow ultrafiltration. The concentrated toxin was loaded onto a cation exchange column, the toxin was bound to the column, and most of the impurities were passed unimpeded through the column. The toxin was eluted with a salt gradient of phosphate buffer, pH 7.0, containing 1.0 M NaCl. The peak containing the toxin was assayed for cholera toxin and protein and the purity was determined to be 92%. The toxin peak had a low endotoxin level of $3.1\;EU/{\mu}g$ of toxin. The purified toxin was used to prepare antiserum against whole toxin, which was used in a $G_{M1}$ ganglioside-binding ELISA to determine residual levels of toxin in an oral inactivated whole-cell cholera vaccine. The $G_{M1}$ ganglioside-binding ELISA was shown to be very sensitive and capable of detecting as little as 1 ng/ml of cholera toxin.

• Restorative Dentistry and Endodontics
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• v.38 no.3
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• pp.134-140
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• 2013

Objectives: There has been a growing interest in glass ceramic systems with good esthetics, high fracture resistance and bonding durability, and simplified fabrication techniques using CAD/CAM. The aim of this study is to compare flexural strength before and after heat treatment of two lithium disilicate CAD/CAM blocks, IPS e.max CAD (Ivoclar Vivadent) and Rosetta SM (Hass), and to observe their crystalline structures. Materials and Methods: Biaxial flexural strength was tested according to ISO 6872 with 20 disc form specimens sliced from each block before and after heat treatment. Also, the crystalline structures were observed using field-emission scanning microscopy (FE-SEM, Hitachi) and x-ray diffraction (XRD, Rigaku) analysis. The mean values of the biaxial flexural strength were analyzed by the Mann-Whitney U test at a significance level of p = 0.05. Results: There were no statistically significant differences in flexural strength between IPS e.max CAD and Rosetta SM either before heat treatment or after heat treatment. For both ceramics, the initial flexural strength greatly increased after heat treatment, with significant differences (p < 0.05). The FE-SEM images presented similar patterns of crystalline structure in the two ceramics. In the XRD analysis, they also had similar patterns, presenting high peak positions corresponding to the standard lithium metasilicate and lithium disilicate at each stage of heat treatment. Conclusions: IPS e.max CAD and Rosetta SM showed no significant differences in flexural strength. They had a similar crystalline pattern and molecular composition.

• Asian-Australasian Journal of Animal Sciences
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• v.9 no.6
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• pp.705-709
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• 1996

A simplified dilutor for cock spermatozoa at ambient temperature was achieved by adjusting the 5% concentration of fructose in isotonic saline. Motility of cock spermatozoa was arrested completely for maximum 6 hrs without affection the survivability of spermatozoa by employing this sugar. To study the effect of high concentration of fructose on fertility, sperm were inseminated with or without fructose at different hrs. Fructose from semen samples was removed by centrifugation. High fertility obtained in the hens inseminated with fructose free sperm (washed). In addition, washed sperm maintained the 85.00% fertility for 6 hrs in winter season ($17-21^{\circ}C$) and 82.67% fertility for 3 hrs in summer season ($31-35^{\circ}C$). Whereas control groups showed 47.33 and 25.33% fertility in winter and summer season respectively. No significant difference was found in percent motility and live counts between the control and washed experimental groups during winter season. However, these measures differed significantly in summer. Washing of cock spermatozoa more than once, high speed centrifugation and more duration for centrifugation proved harmful to fertility. It may be concluded that fructose (5%) can be used as a motility or metabolic inhibitor of spermatozoa for short-term storage of cock semen at ambient temperatures.

• Journal of Microbiology
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• v.42 no.3
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• pp.228-232
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• 2004

In this paper, we investigated the development of a simplified and rapid primary capture step for the recovery of M13 bacteriophage from particulate-containing feedstock. M13 bacteriophage, carrying an insert, was propagated and subsequently purified by the application of both conventional multiple steps and expanded bed anion exchange chromatography. In the conventional method, precipitation was conducted with PEG/NaCl, and centrifugation was also performed. In the single step expanded bed anion exchange adsorption, UpFront FastLine$\_$TM/20 (20mm i.d.) from UpFront Chromatography was used as the contactor, while 54$m\ell$ (H$\_$o/=15cm) of STREAMLINE DEAE (p=1.2 g/㎤) from Amersham Pharmacia Biotechnology was used as the anion exchanger. The performance of the two methods were evaluated, analysed, and compared. It was demonstrated that the purification of the M13 bacteriophage, using expanded bed anion exchange adsorption, yielded the higher recovery percentage, at 82.86％. The conventional multiple step method yielded the lower recovery percentage, 36.07％. The generic application of this integrated technique has also been assessed.

• International Journal of CAD/CAM
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• v.6 no.1
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• pp.199-211
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• 2006

Practical automated flat pattern generation with inbuilt production features for doubly curved sheet metal components (SMCs) is addressed here utilizing a new and unique Point Transformation Algorithm (PTA). This is the third in the series of papers on practical Flat Pattern Development (FPD) [8] and Production Loft Generation Systems (PLGS) [9] complementing the pioneering work [6,7]. In the first two publications, automated loft generation programs have addressed sheet metal components having a Principal Flat Surface (PFS) only. The flat pattern development of 3-D components that do not have the flat surface(termed as Non-PFS components) having complex features of double curvature in addition to cutouts and nibbled holes typical of aircraft components were so far not addressed due to lack of relevant published algorithms. This paper traces the evolution of developments and provides the record of fully illustrated, automated loft generation scheme for aircraft SMCs including the Non-PFS components which underwent validation through production tests by sponsors. Details of some of the unique features of the system like simplified surface model generation, termed as topological model and powerful algorithms deployed with potential for CAD/CAM applications are included.

• KSBB Journal
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• v.5 no.2
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• pp.183-189
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• 1990

An efficient method has been developed for the purification of urokinase from 1, 000 liter batches of human urine. The procedure involved precipitation of urokinase with 2mM zinc chloride, resuspension of the precipitate with 0.1M EDTA/0.5M Glycine solution, and CM-Toyopearl and benzamidine-Sepharose column chromatography. The purified urokinase was fully active and possessed a specific activity of 1.07$\times$105IU/mg. The recoveries ranged from 42 to 65% in several preparations(mean value was 51%). And the urokinase purified by this process consisted of about 13% of single chain urokinase (pro-urokinase) as evaluated by SDS-polyacrylamide gel electrophoresis in reducing condition and by S-2444 amldolytic activity under plasmin treatment.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.04a
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• pp.210-213
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• 2004

We study the fracture behavior of the lumbar No.4 and No.5 vertebra subjected to posteroanterior (PA) forces, a three dimensional finite element method (FEM). The lumbar spine was modeled 3-dimensionally using commercial software based on the principle of convert stacked two dimensional CT scan images into three dimensional shapes. Determination of the boundary conditions corresponding to actual surgical conditions was not easy, so that the simplified spine beam analyses were performed. The results were used in three dimensional finite element (FE) analysis. This FE analysis, indicates that the fracture loads of the lumbar No.4 and No.5 vertebra are respectively 1550 N and 1500 N. These fracture loads are for static loading, but in actual conditions the load on the lumbar spine varies dynamically. We found that the fracture load of lumbar No.4 vertebra is larger than that of lumbar No.5 vertebra, as a result of the total stress difference by the moment.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.31 no.3
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• pp.287-295
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• 1995

fishing boat is a specialized vessel which is intended to perform certain well defined tasks. Its size, deck-layout, carrying capacity and equipment are all related to its function in carrying out its planned operations. Therefore the process of fishing boat design is inherently combined with optimization of the design variables called the economic optimization criteria. Optimization then is a process in which minimum value of weight or cost is established through evaluation of consecutive designs in which one or more design parameters are varied. This paper is to study the basic-design of Stow-net fishing vessel in the Mok-Po region. The main task is developed the preliminary design model of engineering economic system in order to use optimization techniques from operation research the design problem needs to be expressed in terms of objective function and numerous constrains like : speed, fish hold capacity, fishing range, displacement and weight, ratio of main dimensions, etc. The objective function represents the criterion which is NPV such as the ratio of revene/cost. When using computers of limited capacity like P/C, the developed basic-design model of the economic optimization procedure must be simplified to V, Cb, L/B, Dv, Db and less than 15 constraint equations. The main conclusions of this study have attempted to show that economic considerations are essential in Stow-net fishing vessel basic design and operations, and that techno-economic evaluation is an important tool for the design of Stow-net fishing vessel in 69ton and 79ton.

• Nuclear Engineering and Technology
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• v.25 no.3
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• pp.447-456
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• 1993

A simplified model to assess the performance of engineered barrier for the retardation of radionuclide release in a low- and intermediate-level radioactive waste repository was developed. The model is based on the repository design concept being suggested in Korea, and considers two types of release scenario ; a design-bas release for the design of engineered barrier and a realistic release for the performance assessment. For the numerical illustration, the sample calculations were performed for five radionuclides with different chemical characteristics, and the results were analyzed.

• The Korean Journal of Ecology
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• v.21 no.5_3
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• pp.713-721
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• 1998

The effects of artificial interference on the vegetation landscape in Mt. Nam of Seoul, Korea were clarified by analysing the distribution of vegetation landscape element and the number and size of patch depicted as a vegetation map in terms of landscape ecological principles. The effects of artificial interference on vegetation were also confirmed from the environmental gradient analysis on plant community extended from the lowland to the peak of that mountain. Vegetation landscape elements were divided into plantation and secondary forest in actual vegtation map. The ratio of plantation to secondary forest was higher in the lowland below mid-slope and the southern slope. Most afforested land were occupied by Robinia pseudoacacia and Populus tomentoglandulosa, Pinus rigida, P. koraiensis, Metasequoia glyptostroboides, Alnus hirsuta and so on are localy planted. In addition, projects to replace those afforested trees by P. densiflora as a kind of campaign for "Restoration of the one original feature of Mt. Nam" or to replace those tree species by planting young Abies holophylla or P. koraiensis under the mature afforested trees are also carried out in recent years. In cases of secondary forest, the southern slope was dominated by P. densiflora and the northern one by Q. mongolica. But the lowland of the northern slope is dominated by P. densiflora as the same as that in the southern slope. Vegetation landscape elements in Mt. Nam were much simplified comparing with that of suburban area around Seoul. The number of patches, which reflects the degree of diverse artificial interference was more in the lower area than in the upper area and more in the southern slope than in the northern one. On the other hand, the size of patch showed the antagonistic tendency to that of the number of patch. As a result of environmental gradient analysis, vegetation distribution in Mt. Nam was different from that in suburban area around Seoul. For example, Alnus japonica community, Zelkova serrata community, and Carpinus laxiflora community, which is established in mountain comparatively rare in artificial interference disappeared in Mt. Nam. As a result of analysis on vegetational succession in P. densiflora community and Q. mongolica community, both communities showed a tendency of retrogressive succession differently from that in control site located in suburban area around Seoul. In addition, species composition of P. densiflora and Q. mongolica communities in Mt. Nam were also different from those in Mt. Surak located around Seoul. It was interpreted that those results were originated from the environmental pollution and excessive arti ficial interferences.rferences.