• Journal of the Korean Magnetics Society
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• v.18 no.1
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• pp.1-8
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• 2008

We have manufactured and evaluated reference samples for the use of low magnetic moment measurements. Before the measurements, SQUID magnetometers were magnetically shielded from external magnetic noise. We considered the purity including magnetic impurities, the optimum thickness, the modification method, and the shape in the preparation of the samples. Three paramagnetic polycrystaline metal plates of Ti, W, and Al with the area of $4mm{\times}6mm$ were prepared finally. The magnetic moments of these three samples are measured very linear up to the field of 5 T without magnetic hysteresis. The temperature deviated ratios of the magnetic moments for Ti, Al, and W from 290 K to 310 K are 0.7, 1.5, and 0.1 %, respectively. The measured magnetic moments for Ti and W samples by our research team are very well agreeable with those by two SQUID magnetometers and a VSM at Quantum Design via international round robin test. The results suggest that the prepared reference samples are well suited for the use in the low magnetic moment measurement with SQUID based magnetometers.

• The Korean Journal of Mycology
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• v.31 no.3
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• pp.141-147
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• 2003

The pileus of Pleurotus cystidiosus was attached at the side and was spatular-shape. It grew to the size of $7.6{\sim}9.8\;cm$ with dark brown color. The length of stem was $1.4{\sim}2.9\;cm$. The individual weight of fruiting-body was 25.4 g in average. This study was conducted to Investigate the physiological characteristics and to develop the artificial cultivation technique of P. cystidiosus. To find out the optimum condition of mycelial growth of P. cystidiosus, physiological conditions such as media, temperature, pH carbon sources and nitrogen sources were investigated. Various cultural media were used for the cultivation of P. cystidiosus and compost dextrose agar was favorable for mycelial growth. The optimal growing temperature and pH were in range of 25 to $30^{\circ}C$, pH $7{\sim}9$, respectively. When different carbon sources were compared, glucose was found to be best. However nitrogen sources were different with each strains. When different C/N ratio were compared, 20:1 of C/N ratio was found to be best.

• Polymer(Korea)
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• v.37 no.4
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• pp.486-493
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• 2013

The structure, morphology, and physical properties of syndiotatic poly(vinyl alcohol) (s-PVA) gel spun fibers were investigated to prepare polymeric embolization coils. S-PVA was prepared by saponification of the poly(vinyl acetate)/poly(vinyl pivalate)(PVAc/PVPi) copolymer. The viscosity of s-PVA solutions showed shear thinning behavior and the solution formed a homogeneous phase. Based on shear viscosity change with concentration, the optimum dope concentration was selected as 13 wt%, after which s-PVA fibers were spun and the solvent was removed. The fibers were then drawn with a maximum draw ratio of 15. A polymeric embolization coil was made of the s-PVA gel-spun fibers. The fibers were wound densely onto rigid rod and then annealed at different annealing temperatures. The polymeric embolization coil annealed at $200^{\circ}C$ was similar to metallic coils and its shape was maintained well after extension. Overall, gel-spun PVA fibers performed well for the preparation of primary and secondary coils to replace metallic coils.

• Korean Journal of Plant Resources
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• v.22 no.6
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• pp.483-488
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• 2009

The main objective of this breeding program is to develop high yielding, disease resistance and good processing potato cultivar. 'Gui Valley' is a clonal selection resulting from a cross between 'ND2471-8' and 'Cona'. It has medium plant height and light green foliage. 'Gui Valley' has medium flowering habit and light pink flowers. 'Gui Valley' is a medium maturing potato cultivar and tubers are smooth, yellow skin, light yellow flesh, long-oval tuber shape, distinct red eyes with medium depth and medium dormancy. It has high level of tuber uniformity and good keeping quality. 'Gui Valley' demonstrates resistance to potato virus Y (PVY), soft rot, but moderately susceptible to late blight and common scab. It is also resistant to most of the internal and external physiological disorders particularly dehiscence, hollow heart and internal brown spot. The specific gravity of 'Gui Valley' is significantly higher (1.097) than that of 'Shepody' (1.078). 'Gui Valley' has suitable for processing mainly French fries and chips. This cultivar has high level of tuber uniformity and capable of yielding 37.6 $t{\cdot}ha^{-1}$, which is 18.2% higher than the control potato cultivar 'Shepody' under optimum agronomical practices.

• Korean Chemical Engineering Research
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• v.43 no.3
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• pp.407-411
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• 2005

YAG:Tb($Y_3Al_5O_{12}:Tb$) phosphor particles were prepared by spray pyrolysis from spray solution containing various types of flux materials. The effects of type of flux, organic material and post-treatment temperature on the characteristics of morphology, crystallinity and photoluminescence of YAG:Tb phosphor particles were investigated. Citric acid and ethylene glycol used as organic additive improved the photoluminescence intensity of the YAG:Tb phosphor particles without destruction of the morphology after post-treatment at high temperature. However, the spherical shape of the precursor particles obtained by spray pyrolysis from spray solution containing high amount of flux material disappeared after post-treatment at $1300^{\circ}C$. YAG:Tb phosphor particles prepared from spray solution containing lithium carbonate flux had fine size and regular morphology after post-treatment. Lithium carbonate used as flux material was also efficient in improvement of the photoluminescence intensity of the YAG:Tb phosphor particles. The optimum photoluminescence intensity of the YAG:Tb phosphor particles prepared from spray solution containing lithium carbonate flux was 189％ of that of the phosphor particles prepared from spray solution without flux material.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.1
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• pp.17-25
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• 2020

In this study, three-dimensional fluid flow analyses have been performed in order to investigate the performance characteristics of a horizontal axis tidal turbine (HATT) by solving three-dimensional Reynolds-averaged Navier-Stokes equations utilizing the shear-stress-transport turbulence model. The computational domain for the flow analysis has been composed of hexahedral grids, and the grid dependency test has been carried out so as to determine the optimum grid size. Performance characteristics of the HATT have been investigated in consideration of the effects of hub nose geometry, inflow angle, and the tower. It has been found that the power output can be enhanced along with an increase of the ratio of the length to the diameter of the turbine nose, and the power of HATT has been reduced by approximately 10% when the primary fluid flow had an inflow angle of 15°. The power output of downstream HATT is found to be lower than that of the upstream HATT by about 1%.

• Analytical Science and Technology
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• v.25 no.2
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• pp.146-151
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• 2012

An analytical method was developed for the measurement of uranium isotope in ground water using the liquid scintillation counting technique. A LKB Wallac Quantulus 1220 liquid scintillation counter (LSC) equipped with pulse shape analyzer (PSA) and a solvent extraction method were used for the measurement of uranium isotope in ground water samples. The effect of solution volume on the extraction efficiency was evaluated for 100 to 1000 mL solutions using a NIST standard reference material (NIST SRM 4321C). The effect of groundwater pH on the extraction efficiency was also investigated for pH ranging from 0.5 to 10. It was found that the extraction efficiency had a strong dependence on pH showing a maximum at pH 2. In contrast, the effect of groundwater volume on the extraction efficiency was negligible in the range investigated. According to the method, the extraction efficiency of uranium isotopes was near 96% and the lower detection limit for uranium was 0.018 Bq/L with the counting time of 300 min. The result of this study was also verified by the conventional ICP-MS measurement. It is demonstrated that the suggested method is valuable to the determination of the optimum extraction and measurement conditions for uranium in ground water. The method was successfully applied to the ground water at four locations near the Daejeon province. It was found that the uranium content and the isotopic ratio of $^{234}U/^{238}U$ at the locations ranged 0.59~6.69 Bq/L and 0.72~1.40, respectively.

• Journal of Bio-Environment Control
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• v.14 no.2
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• pp.128-136
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• 2005

The objective of this study was to determine the effect of calcium concentrations in fertilizer solution on growth and cut flower quality of chrysanthemum 'Biarritz' To achieve this, deficiency symptom and growth characteristics as influenced by controlled Ca concentrations in fertilizer solution were investigated. The analysis of plant tissue and soil solution of root media were also conducted to secure optimum concentration for plant growth. Calcium deficiency developed on the very youngest leaves and the young leaves developed 'cupped' shape as they expand. The cut flower length of 0, 3.0 and 6.0 mM treatments were 105.8, 106.5, and 107.3cm, respectively. Elevated Ca concentration within the range from 0 to 6.0mM in fertilizer solution increased cut flower weight. The cut flower weight of control and 6.0mM treatment were 51.6 and 59.4 g, respectively. The tissue Ca content of 6.0mM treatment in which crops showed the highest growth among treatments was $3.09\%$ based on the dry weight of the youngest fully expanded leaves. From the results, it seems necessary to maintaining tissue Ca content higher than $2.8\%$. Soil Ca concentrations increased as K concentrations in fertilizer solution were elevated. Ca concentration in 0.0, 1.5, 3.0, 4.5 and 6.0mM treatments were 5.0, 7.4, 12.1, 16.5 and $28.2mg{\cdot}L^{-1}$, respectively, at harvesting stage. It is suggested that Ca concentration higher than $25.4mg{\cdot}L^{-1}$ in soil solution of root media is required to maintain normal growth.

• Journal of Navigation and Port Research
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• v.33 no.1
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• pp.57-63
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• 2009

In order to effectively isolate the marine wastes with an effluent standard, the pretreatment process is required to isolate solid materials from the liquid-solid mixed wastes. The more effective the pretreatment becomes, the more processing capacity of posttreatment will be improved and process facilities will be downsized. In this paper, we suggested the vibrating reverse-slant screen, investigated the optimal vibration frequency and vibrator installation angle for the separation of the liquid solid mixed wastes. Several experiments for separation efficiency were conducted under the condition of various vibration frequency($35{\sim}60Hz$, 5Hz interval) and vibrator angle($0^{\circ}$, $30^{\circ}$, $45^{\circ}$, $90^{\circ}$) considering the crack of screen. The screen inclination angle is set up the gradient as $3^{\circ}{\sim}5^{\circ}$ through the preliminary experiments. Also, we made two types of screen(respectively rectangle and square screen). The separation device has shown the optimum efficiency at vibrator angle $0^{\circ}$ and vibration frequency 60Hz, and has no relation with the shape of screen. And the proposed technology is verified by comparing with quantity of suspended solids before and after filtration.

• Journal of the Korean Institute of Gas
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• v.21 no.1
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• pp.27-33
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• 2017

In this study, the stability of trench slope was analysed in summer and winter seasons for the construction of pipelines in permafrost regions. The construction standards of Korea, Russia and UK were compared for obtaining an optimum trench shape for a pipeline of 30 in. diameter. Using the geotechnical properties of soil in Yakutsk (Russia), the stability of trench slope was analysed using Strength Reduction Method (SRM) according to the horizontal slope angle values of $0^{\circ}$, $10^{\circ}$, $20^{\circ}$ and $30^{\circ}$ and vertical slope angle values of $20^{\circ}$, $30^{\circ}$ and $40^{\circ}$. In both seasons, an increase in the slope angle results in a decrease in the factor of safety. The results show that horizontal slope angle of $30^{\circ}$ was not safe in summer season. At the vertical slope angle of $20^{\circ}$, trench side failure was observed, whereas, ground slope failure was observed at the vertical slope angles of $30^{\circ}$ and $40^{\circ}$. Due to the solidification of pore water at temperatures below $0^{\circ}C$, cementation of soil particles take place. Therefore, the trench slope was found to be stable in the winter season at all vertical and horizontal slop angles, except for special load cases and abrupt temperature changes.