• Analytical Science and Technology
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• v.21 no.2
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• pp.143-147
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• 2008

U(IV) ion, the valance state of uranium presumed at in a deep-depth disposal of a spent fuel, was prepared and separated from U(VI) ion. In order to prepare U(IV) ion, tests were performed by adding several reducing agents into a uranyl solution or by dissolution of uranium oxide in a mixed acid added with a reducing agent. The valance states of the uranium in the prepared solutions were identified by separating two ions with a Dowex AG 50W-X8 cation exchange resins and measuring the solutions using a laser-induced fluorescence spectroscopy. However, U(IV) and U(VI) were not separated by a Lichroprep Si60 exchange resin in the same separation condition of Pu(IV) and Pu(VI).

• Journal of Ocean Engineering and Technology
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• v.23 no.3
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• pp.40-45
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• 2009

With the increase in the annealing temperature, the volume fraction of austenite phase increased and the volume fraction of ferrite phase decreased. In compliance with the addition of N, not only the volume fraction of austenite phase was increased but also the austenite structure was made larger. Volume fraction of ${\sigma}$ phase was increased by decreasing of the volume fraction of ferrite phase, with the increase in the aging time and in compliance with the addition of N. As increasing in volume fraction of ${\sigma}$ phase, tensile strength and hardness increased, while elongation and impact value decreased. Elongation slowly decreased and impact value rapidly decreased at the early stage of aging. By the added N, tensile strength, elongation, hardness and impact value was increased.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05b
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• pp.627-632
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• 1998

Using an ammonium oxalate-ammonium sulfate electrolyte, a simple, quantitative, and fast technique for preparing sources for analytical alpha spectrometry was developed. To determine the optimum conditions for plating plutonium, parameters such as current density .and pH of electrolyte affacting the electrodeposition of the plutonium have been investigated. An optimized electrodeposition step for the determination of plutonium has been validated with a result of application to IAEA-Reference Soils. The new method of fallout Pu determination has been applied to environmental samples such as soil, sediment and moss samples in Korea.

• Proceedings of the Korea Information Processing Society Conference
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• 2013.05a
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• pp.865-866
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• 2013

다양한 웹 사이트에서 '맛집' 어플의 제공은 다양하게 제공하고 있다. 본 연구도 기존의 제공 서비스와 유사한 기능을 사용하고 있지만, 차이점은 사용자의 의사결정에 효율적으로 도움을 주기 위해 맛집 방문 이력 정보를 이용한 개인 맞춤형 음식점을 추천하는 어플리케이션을 설계한다. 이는 기존의 '맛집' 정보 제공과 방문한 이력에 따른 '맛집' 추천 정보를 제공하는 어플리케이션이다. 사용자는 현재 위치에 따라 과거 방문기록을 등록한 인근 '맛집' 방문 빈도와 방문 순서를 분석하여 현재 위치에서 개인별 맞춤 음식점을 추천받을 수 있다.

• Polymer(Korea)
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• v.38 no.3
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• pp.333-337
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• 2014

PVC (polyvinyl chloride) intravenous fluid bags and tubes that contain DEHP (diethylhexyl phthalate) as a plasticizer have several associated disadvantages for intravenous injections. We investigated the drug absorption behaviors on the inner surface of an infusion tube that consisted of commercialized PVC/PU (polyurethane). We developed a non-PVC (polyolefin) tube in order to improve the efficacy of this drug administration method. We prepared four types of non-PVC (polyolefin) infusion tubes using a polyethylene (PE), polypropylene (PP), syndiotactic 1,2-polybutadiene (PB), and styrene-ethylene (SE) copolymer elastomers were prepared using a single screw extruder. The four types of manufactured non-PVC (polyolefin) infusion tubes had good mechanical properties that were equivalent to PVC tube properties. The four types of prepared non-PVC (polyolefin) infusion tubes also prohibited drug absorption when compared to the commercialized PVC and PU tubes. Therefore, based on the results of this study, prepared non-PVC (polyolefin) tubes are good candidates for infusion because they prevent drug absorption and the release of DEHP.

• Archives of Plastic Surgery
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• v.32 no.4
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• pp.503-510
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• 2005

If we could predict the necrosis of the flap caused by reperfusion injury, we can minimize the necrosis of the flap by taking appropriate action before necrosis begins. In this study, we examined whether we can predict the survival of flap under reperfusion injury or not, by measuring laser doppler flow meter values. We divided the group into the control and experimental groups corresponding to 6, 8, 9, 10, and 12hours after reperfusion(hours after ligation of auricular central artery). In each group, we examined necrotic change, perfusion unit (PU), serum superoxide dismutase (SOD), glutathione peroxidase, angiography and pathologic findings. No necrosis was observed in the 6 and 8 hours group but 8, 18, 20 hours after ligation, necrosis was observed, Also in each of 9, 10 and 12 hours group (each group consisted of 20 flaps), necrosis were noted. According to the above data, the critical time of necrosis in the auricular skin flap model lies between about 8 to 9 hours. Comparing the PU between the necrosis and non-necrosis groups, the former group showed a mean 39.57 PU increase after 60 min of reperfusion, and the latter group showed a mean increase of 21.21 PU. We can conclude that better flow can dilute oxygen free radical into systemic circulation, and this means less injuries are caused on vessels. Our study implies that if blood flow increase is less than 30 PU, intensive care is needed to save the flap. Additionally, we found significant decrease of serum SOD and glutathione peroxidase in the necrotic group. Therefore, monitoring these serum markers will be helpful in predicting reperfusion injury and supplementing these enzymes could be helpful to save the flap. The laser doppler flow meter is thought to be helpful in clinical circumstances for evaluating the circulation of the flap after the operation. However, more accumulation of clinical studies should be necessary establishing useful clinical data.

• Applied Chemistry for Engineering
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• v.7 no.2
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• pp.341-349
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• 1996

To improve the dyeability of polyurethane (PU) resin, low molecular weight diols containing dye site in the molecular structure was added as a chain-extender. PU resin were synthesized with the variations in the chain extender, polyol type, and hard segment/soft segment (HS/SS) ratio. When HS/SS ratio is 1.4 and dimethylolpropionic acid(DMPA) or N-butyldiethanolamine (BDEA) was used as a chain extender, because of heterogeneity of reaction mechanical properties were diminished. But when N-methyldiethanolamine (MDEA) was used as a DCE, and HS/SS ratio lowed to 1.3, mechanical properties and dyeability improved. In particular, when linear type 1,4-BD was formulated with MDEA, hydrolysis resistance and mechanical properties of PTMG type PU was improved. And initial elasticity, tensile strength and elongation could be controlled by the variation of HS/SS ratio, DCE mixing ratio of 1,6-HD or NPG.

• Journal of Environmental Science International
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• v.18 no.3
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• pp.333-343
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• 2009

This study presents the analysis of an atmospheric flow around a single-doppler radar located in a pseudo-site. The use of a doppler radar in meteorological field of wind engineering has become widespread over the last several decades, but it has generally been recognized that the single-Doppler radar yields only one single velocity component - the radial velocity($V_r$) so that some additional hypotheses or simplifications must be necessary to get proper wind forecast. Therefore, in order to get an accurate radial velocity($V_r$) in this study, the existing methods such as VAD(Velocity Azimuth Display) and VARD(Velocity Area Display) are reformulated and applied to match the previous study(Waldteufel and Corbin), which have been an important indicator for retrieving a radar velocity. The results presented in this study include the results from different assessment methods in a peudo-site of different wind fields. Unless the existing method can consider the proper decomposition of radial velocity in the real site, then authors suggest an appropriate curve-fitting to decrease the uncertainty errors by changing a grid adaptation rate or applying a weighting function with respect to the wind angle. It is concluded that provided properly formulated fitting function are used, the wind retrieval from the Doppler radar using VAD and VARD methods can be a viable tool for use in wind engineering problems searching for the wind resources.

• Journal of Ocean Engineering and Technology
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• v.20 no.6 s.73
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• pp.101-107
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• 2006

Recently, with the increase in requirements for marine development, a marine urbanism is being visualized, with more and more huge-scale structures at the scope of the ocean space utilization. In particular, a pontoon-type structure has attracted attention, since The Floating Structures Association of Japan proposed a new concept as the most suitable one of floating airports. The Very Lage Floating Structure (VLFS) is considered a flexible structure, for a quite large length-to-breadth ratio and its geometrical flexibility. The main objective of this study is to makean exact and convenient prediction about the hydro-elastic response on very large offshore structures in waves. The numerical approach for the hydro-elastic responses is based on the combination of the three dimensional source distribution method and the dynamic response analysis method, which assumed a dividing pontoon type structure, as many rigid bodies connected elastic beam elements. The established hydo-elastic theory was applied to the radiation forces caused by motions of a whole structure, formulated using the global coordinate system, which has the origin at the center of the structure. However, in this paper, we took radiation forces, occurred by individual motions of floating bodies, into consideration. The calculated results show good agreement with the experimental and calculated results by Yago.

• Applied Chemistry for Engineering
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• v.31 no.5
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• pp.487-494
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• 2020

Polyurethane/modified boron nitride (PU/m-BN) composite was synthesized from the poly(tetra methylene glycol) (PTMG), 4,4'-methylenebis(phenyl isocyanate) (MDI), and modified boron nitride (m-BN). The modification of boron nitride and synthesis of PU/m-BN composite were confirmed by Fourier transform infrared (FT-IR) spectroscopic analyses. The mechanical properties of the PU/m-BN composites were measured using the universal testing machine (UTM) and the thermal properties of the composites were investigated ser flash analysis (LFA) and UL94 measurements. As a result, the thermal conductivity of the polyurethane composite increased to 1.19 W/m·K, and the flame retardancy of the easy to burn polyurethane, which was not self-extinguishing was improved to UL94 V-1 grade.