• The Korean Journal of Nuclear Medicine Technology
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• v.13 no.1
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• pp.116-119
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• 2009

Background: Preanalytical factors can affect reliability of hormone assay results. Adrenocorticotropic hormone (ACTH) in blood is considered highly unstable because of proteolytic degradation, so storage of blood samples on ice until analysis is recommended. In clinical practice, however, this procedure may present logistical problems because most samples for ACTH measurement must be shipped from the place of sample collection to the laboratory. Therefore, we studied the impact of time and temperature before plasma separation and analysis on the results of ACTH assays. Methods: A total number of 22 patients were enrolled in this study. We obtained 2 blood samples. ACTH concentrations were 35~126 pg/mL. ACTH concentrations were measured by immunoradiometric assay (IRMA) using commercial kits (CIS Biointernational, Gif-sur-Yvette, France). Results: ACTH levels showed a significant difference between the samples of $22^{\circ}C$ EDTA and $4^{\circ}C$ EDTA. Measured ACTH concentrations significantly decreased with time before freezing at $-20^{\circ}C$. ACTH levels showed no significant difference between the groups of after storage for 24 hr without centrifugation at $22^{\circ}C$ and $4^{\circ}C$. Conclusion: We recommend that blood samples be obtained on pre-chilled EDTA collection tubes. The shortest possible time between sample collection and processing is always the best laboratory practice.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.6
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• pp.145-152
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• 1998

This paper presents an optimum design of a rotor-bearing spindle system for a ultra centrifuge (80,000 RPM) supported by ball bearings with nonlinear stiffness characteristics. To obtain the nonlinear bearing stiffnesses, a ball bearing is modeled in five degrees of freedom and is analyzed quasi-statically. The dynamic behaviors of the nonlinear rotor-bearing system are analyzed by using a transfer-matrix method iteratively. For optimization. we use the cost function that simultaneously minimizes the weight of a rotor and maximizes the separation margins to yield the critical speeds as far from the operating speed as possible. Augmented Lagrange Multiplier (ALM) method is employed for the nonlinear optimization problem. The result shows that the rotor-bearing spindle system is optimized to obtain 9.5％ weight reduction and 21％ separation margin.

• Journal of the Korean Chemical Society
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• v.36 no.6
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• pp.849-856
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• 1992

We prepared a simple, economic and versatile preparative system for an enantiomeric separation. Hydrophobic amino acid enantiomers were resolved in the preparative scale by a centrifugal liquid chromatography on the N-hexadecyl-L-proline coated reversed phase. The factors controlling the retention and resolution of racemic amino acids such as the concentration of Cu(Ⅱ), pH of the eluent, the type and content of organic modifier, and rpm of CLC were examined. Several mg of hydrophobic amino acid enantiomers were separated preparatively. To separate all of different amino acid enantiomers, various coating material will be investigated.

• 한국생물공학회:학술대회논문집
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• 2005.10a
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• pp.889-893
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• 2005

Cell lysis method is very important to study intracellular metabolites in microorganisms. In this study, various cell lysis methods were compared to find a good method analysing intracellular metabolites in P. pastoris. P. pastoris was cultivated in YPD medium at 30 $^{\circ}C$, 200 rpm for 24 hours and its morphology as well as the change in strain's shape were observed by microscopy. The UV/vis spectrophotometer was used to measure intracellular protein concentrations.

• Korean Journal of Food Science and Technology
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• v.36 no.2
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• pp.321-328
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• 2004

Raw mulberry (Morus spp.) juice was prepared by minimal processing using several filter aids, fining agents, and clarifying enzymes, followed by filtration, centrifugation, and membrane filtration. Control of browning in minimally processed mulberry juices by anti-browning agents, sodium hydrosulfite, L-ascorbic acid, citric acid, and NaCl, was investigated using quantitative measurements of color changes during storage. Clarification of mulberry juice was improved by adding several filter aids, fining agents, and enzymes, followed by filtration and centrifugation. Several fining agents, including chitosan, chitin, PVPP, gelatin, and casein at a concentration of 1%, and combination of ultrafiltration and centrifugation at 8,000 rpm were not suitable for clarification of juice owing to strong adsorption of anthocyanin pigment. Combination of $0.01\;{\mu}m$ membrane filtration and centrifugation at 8,000 rpm was effective for clarification of mulberry juice. Browning of minimally processed mulberry juice was inhibited significantly by adding 200 ppm sodium hydrosulfite, and 0.1% L-ascorbic acid (L-AsA) and 0,1% citric acid (CA) also showed considerable browning inhibition. Combination of L-AsA and CA, which was moderately effective for browning inhibition of juice, may be useful as a sulfite alternative for mulberry juice. Optimum sugar ($^{\circ}Brix$)/acid ratio and commercial sterilization of minimally processed mulberry juice were approximately 40 and 10 min at $85-90^{\circ}C$, respectively.

• Proceedings of the Korean Aquaculture Society Conference
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• 2003.10a
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• pp.129-129
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• 2003

해양저질에서 휴면포자의 분포와 분포량에 대한 조사는 미래의 와편모조류 적조발생 시기나 장소를 예측할 수 있게 한다. 그러므로 저질내의 휴면포자를 찾고 분리하는 기술이 기본적으로 수행되어야 하며 지금까지 여러 방법이 개발되어 왔다. 이 연구의 목적은 기존의 휴면포자 계수방법들을 비교함으로써 연구의 효율을 제고 하고자 하는데 있다. 이 실험에서는 새만금 해역의 동일정점 저질내에 존재하는 휴면포자를 형광 염색하여 계수하는 Primuline 염색법, 해수, 휴면포자, sodium polytungstate의 비중차이를 이용하여 밀도구배원심법으로 분리하는 방법, 그리고 10% HCl로 탄산질을 제거하고 47% HF로 규산질을 제거한 뒤 휴면포자를 계수하는 고전적 계수방법 (palynological technique)을 사용하여 저질 내의 휴면포자를 분리 비교하였다. Primuline 염색법을 이용하였을 경우 Alexandrium famarense/catenella complex, Alexandrium sp. (spherical), Gonyaulax verior, Gonyaulax scrippsea, Gonyaulax spinifera complex등의 일부 종만 염색되어 관찰되었다. sodium polytungstate를 비중 1.3 g$cm^{-3}$으로 조정한 후 휴면포자를 분리한 밀도구배 원심법은 생물에 거의 무해한 것으로 알려져 있어서 발아가 가능해 휴면포자와 영양세포간의 관계를 규명할 수 있다는 장점이 있으나 계수에 있어서는 재현성이 떨어졌다. 반면 Palynological technique은 발아는 되지 않지만 석회질 벽을 가지는 휴면포자를 제외한 대부분의 종들이 관찰되었다. 이 결과는 실험 목적별로 휴면포자 계수방법을 달리 할 수 있음을 보여준다. 즉 발아실험을 할 경우에는 밀도구배원심법을, Alexandrium과 같은 특정종의 계수목적시에는 Primuline 염색법을, 정점 내 정확한 종 분포 파악을 위해서는 palynological technique을 사용하는 것이 효과적일 수 있다. 하지만 종분포 파악시에는 시간이 많이 소요되므로 좀더 신속하고 정확한 실험을 위해 분자생물학적인 기법들이 요구된다.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.10
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• pp.148-155
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• 2003

In this paper, based on the concept of solid particles' hovering problem the working formula for the channel design of a Decanter-type centrifuge were derived. The Shields' diagram and its curve-fitting formula were used in determining the criterion of particle size for the sediment. By using these formula the designer can determine the sectional configuration of the channel, such as the liquid depth, the normal pitch of the screw-blade arrangement and the bowl diameter.

• Proceedings of the Membrane Society of Korea Conference
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• 1998.04a
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• pp.110-112
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• 1998

1. 서론 : 분석화학의 중요한 과제중 하나 고효율(high efficiency)과 고해상도(high resolution)를 가지고서 혼합물에서 분자나 입자의 분리능을 개선하는 것과 낮은 수준의 농도에서 이런 분획들(fractions)을 정량화 하는 것이다. 현재의 추세는 분리하고자 하는 분자의 상한선을 증가시키는 것이 순수과학과 산업에서 중요하게 되었다. 이런 분리 기술의 응용은 거대분자(macromolecules)와 입자들(particles)인 cell fragments, plasmides, chromosomes, liposomes, synthetic polymers 등에 적용되고 있는데, 고전적인 분석방법으로는 한외여과, 원심분리, 크기배제 크로마토그래피 등이 있지만 시간이 걸리고 해상도와 효율에 제한이 있다.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.44 no.3
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• pp.267-275
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• 2018

This study attempts to quantify amount of coacervate generated in a formulation of shampoo with three methods using optical transmission, suspension in a glass tube, and centrifugation. For the correct data acquisition, each method has been optimized to estimate the amount of coacervate with minimum standard deviation. To simply and quantitatively estimate amount of coacervate, two formulations of shampoo were employed as a large or small amount of coacervate generated. Comparisons of the two formulations in repetitive measurement elucidated that the methods by the centrifugation efficiently can be utilized to estimate the accurate amount of coacervate. Additionally, the amount of coacervate by the centrifugation does not exhibit the difference of patterns before and after drying in a shampoo formulation with different conditioning polymers, and this suggests that the centrifugation is a superior method to compare amount of coacervate in liquid.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.9
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• pp.118-125
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• 2003

In this study, we carried out the finite element analysis for the screw of centrifuge that is the weakest part of the centrifuge for sewage management. Centrifugal force caused by rotation with velocity of 4000rpm was applied at the screw. Structural analysis was done with respect to the change of the ratio of blade pitch($R_P$), shaft diameter($R_D$) and extended hole($R_E$). When the area of circular hole is equal to that of extended holes, maximum equivalent stresses in the screw with circular and extended circular hole were compared. And then natural frequency analysis was executed for the same model. Three mode shapes were used to explain the vibration characteristics of each screw. Convergence study was accomplished fur more accurate results.