• Journal of Korean Society on Water Environment
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• v.18 no.3
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• pp.283-290
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• 2002

In this study, home-made detection system by means of noble FIA is introduced on the measurement of toxic nitrite in the water samples collected from the area of Kwangju. As the standard calibration between 30 to 1000 ppb, the linearity has been shown more than 0.9999 as the correlation coefficient($R^2$) with the detection limit 1.5 ppb(S/N>2). The distribution of sample concentration was monitored as N.D. - 123 ppb which is wide span of concentrations in field water samples. The low level of nitrite is hardly detectable with other expensive sophisticated instruments including ion chromatography. Whereas the result of high concentration brings forth the necessity monitoring constantly our precious water resources. Successfully, the FIA system has played a very important role detecting wide span of nitrite in water sample. This technique can be adopted for controlling our environment in the near future.

• Journal of The Korean Astronomical Society
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• v.39 no.4
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• pp.115-123
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• 2006

We present $JHK_S$ near-infrared CCD photometric study for the Galactic open clusters NGC 1641 and NGC 2394. These clusters have never been studied before, and we provide, for the first time the cluster parameters; reddening, distance, metallicity and age. NGC 1641 is an old open cluster with age $1.6{\pm}0.2$ Gyr, metallicity $[Fe/H]=0.0{\pm}0.2$ dex, distance modulus$(m-M)_0=10.4{\pm}0.3\;mag(d=1.2{\pm}02\;kpc)$, and reddening $E(B-V)=0.10{\pm}0.05$ mag. The parameters for the other old open cluster NGC 2394 are estimated to be $age=1.1{\pm}0.2$ Gyr, $[Fe/H]=0.0{\pm}0.2$ dex, $(m-M)_0=9.1{\pm}0.4\;mag(d=660{\pm}120\;pc)$, and $E(B-V)=0.05{\pm}0.10$ mag. The metallicities and distance values for these two old open clusters are consistent with the relation between the metallicities and the Galactocentric distances of other old open clusters. We find the metallicity gradient of 53 old open clusters including NGC 1641 and NGC 2394 to be ${\Delta}[Fe/H]/{\Delta}R_{gc}=-0.067{\pm}0.009\;dex\;kpc^{-1}$.

• Journal of Magnetics
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• v.3 no.4
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• pp.105-111
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• 1998

The low energy excitations of spin waves (SWR) in thin films can be used for determination of the surface anisotropy constant and the nonhomogeneities of magnetization in the close-to-surface layer. The dispersion relation in SWR is sensitive on the geometry of experiment. We report on temperature dependence of surface magnetic anisotropy energy constant in magnetic semiconductor thin films of$ CdCr_{2-2x}In_{2x}Se_4$ at spin glass state. Samples were deposited by rf sputtering technique on Corning glass substrate in controlled temperature conditions. Coexistence of the infinite ferromagnetic network (IFN) and finite spin slusters (FSC) in spin glass state (SG) is know phenomena. Some behavior typical for long range magnetic ordering is expected in samples at SG state. The spin wave resonance experiment (microwave spectrometer at X-band) with excited surface modes was applied to describe the energy state of surface spins. We determined the surface magnetic anisotropy energy constant versus temperature using the surface inhomogeneities model of magnetic thin films. It was found that two components contribute to the surface magnetic anisotropy energy. One originates from the exchange interaction term due to the lack of translation symmetry for surface spin as well as from the originates from the exchange interaction term due to the lack of translation symmetry for surface spin as well as from the stray field of the surface roughness. The second one comes from the demagnetizing field of close-to surface layer with grad M. Both term linearly decrease when temperature is increased from 5 to 123 K, but dominant contribution is from the first component.

• Journal of the Society of Naval Architects of Korea
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• v.29 no.2
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• pp.123-131
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• 1992

In ship structural design procedures structural analyses are performed using the scantlings of structural elements determined at the initial design stage based on relevent rules and previous experiences. Modifications of scantlings will be carried out in case that the analysis results do nut satisfy design criteria. Reanalysis method s are efficient to analyse the structures of slightly modified using information obtained from the previous analysis. In this paper various approximate reanalysis techniques will be compared and their characteristics will be described. Furthermore sensitivity analyses are adapted to provide information from which selection of most influential design variables will be made and amount of modification can be determined. Redesign procedures described herein are demonstrated using examples.

• Archives of Pharmacal Research
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• v.6 no.2
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• pp.123-131
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• 1983

Polysaccharide fractions were prepared from Ginseng root, Mori Radicis Cortex (M. R. C. ), Phellodendri Cortex (Ph. C. ), Sappan Wood (S. W. ) and Tigli Semen (T. S.). Water extract was also prepared from the mixture of ph. C., S. W. and T. S. Ginseng polysaccharide and water extract of the mixture showed marked antitumor activity against sarcoma 180. Ginseng polysaccharide showed a mild increasing effect on the number of circulating leucocytes and a marked increasing effect on the number leucocytes and a marked increasing effect on the number of plaque forming cells (PEC). Polysaccharides from ginsing root, S. W., Ph. C. + T. S. and water extract of the mixture showed dramatic inducing activities of periotoneal exudate cells (PEC), polymorphonuclear leucocytes (PMN) and macrophages. These results suggest the possibility that water extract of the mixture may have the lentinan like effect and ginseng polysaccharide may have stimulating effects on the general immune system.

• Mycobiology
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• v.28 no.3
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• pp.123-126
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• 2000

Sodium hypochlorite alkaline was tested against Pseudomonas tolaasii causing bacterial blotch on cultivated oyster mushroom (Pleurotus ostreatus). The minimum inhibitory concentration of sodium hypochlorite against P. tolaasii contained active chlorine (AC) at 1.4 mg/l on plate assay. The highest cultivation yield was obtained from the treatment of AC 5.7 mg/l. Treatment of sodium hypochlorite at the rate of higher than AC 11.4 mg/l resulted in reduced yields at the harvest. However, the population of total bacteria on the bed surface treated with AC 5.7 mg/l of sodium hypochlorite was maintained to some extent. Inhibitory concentration against total bacteria on the bed surface was over AC 22.8 mg/l. Mushroom mycelium was damaged and its growth strongly inhibited at the concentration of AC 200 mg/l. Mushroom caps showed yellowish symptom by chemical injury by treatments of AC 74.1 mg/l or higher. Sporocarps infected by P. tolaasii were irrevocable at any concentration of sodium hypochlorite. Routine watering with AC 5.7 mg/l from mushroom initiation to the end of picking resulted in reduced bacterial blotch incidence of 40% and 86% at two mushroom farms. The treatment resulted in higher quality mushroom production compared to that conventionally watered with tap water alone.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.9 no.3
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• pp.424-433
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• 2002

This study was done to compare death orientation scores for student nurses before and after studying a major. The participants were 130 student nurses before the major and 123 student nurses after the major at C university in Kwang Ju city. The data were gathered from March, 1998 to September, 2001 using a questionnaire. The data were analysed by Chi square test, t-test, ANOVA and Pearson correlation coefficients. The results of this study are summarized as follows ; 1 The mean scores for death orientation before and after the major were 57.8 and 60.2 respectively. The mean score of death orientation after the major tended to be higher than before but they were not significantly different. 2. There were significant differences in death orientation scores between the two groups before the major for 'physical function (F=3.83, p=.023)' and 'attending a lecture on spiritual nursing (F=2.58, p=.010)'. After the major there were significant difference for 'feeling of health (F=4.76, p= .001)'. 3. The death orientation scores before the major showed an inverse correlation with religiosity score (r=-.239, p=.006). After the major there was no correlation with religion.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.12a
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• pp.123-125
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• 2006

The $TiO_2$ sol was prepared hydrothermally in an autoclave from aqueous $TiOCl_2$ solutions as a starting precursor. Hollow fibers were obtained when the sol-gel-derived $TiO_2$ sol was treated chemically with a NaOH solution and subsequently heated in the autoclave under various conditions. A systematic analysis of the influence of different NaOH concentrations on the formation of nanotubes was carried out. The details of the nanotubular structure were investigated by using transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray diffraction (XRD). From the TEM images, the outer and the inner diameters of the tubes were measured to be about 8 and 4 nm, respectively, the lengths were measured to be several hundreds of nanometers.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.10
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• pp.830-836
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• 2012

An efficient cooling system is essential for the electronic packaging such as a high-luminance LED lighting. A special heat transport technology, Pulsating Heat Pipe (PHP), can be applied to the cooling of LED lighting. In this paper, the operational characteristics of the PHP in the imposed thermal boundary conditions of LED lighting were experimentally investigated. The experimental PHP was made of copper tubes of internal diameter of 2.1 mm. The working fluids of ethanol, FC-72, water, acetone and R-123 were chosen for comparison. The results showed that an optimum range of charging ratio exists for high cooling performance; 50% for most of the fluids. Among the five working fluids, water showed the highest heat transfer rate of 260 W. Two distinguished characteristics of pulsating direction were identified. It is also identified that high vapor pressure gradient is one of key parameters for better heat transfer performance.

• Journal of Korea Foundry Society
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• v.25 no.3
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• pp.123-127
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• 2005

0.8wt.% C과 $0.75{\sim}3.2$(0.75, 1, 1.26, 1.44, 1.89, 2.1, 2.46, 2.94, 3.22)wt.% Si을 함유한 고탄소 고실리콘 강에서 Si의 함량이 미세조직과 processing window에 미치는 영향에 대해 조사하였다. 열처리는 $940^{\circ}C$에서 1시간 동안 오스테나이징을 실시한 후, $320^{\circ}C$에서 $0.2{\sim}300$분 동안 오스템퍼링을 하였다. 미세조직에서, 0.75 wt.% Si을 함유한 강에서 국부적으로 오스페라이트(ausferrite)가 존재하는 것을 확인하였다. Processing window는 경도 및 XRD 측정으로 결정하였다. $t_{1}$은 Si의 함량이 2.5 wt.% 이하에서는 거의 변화가 없다가,2.5 wt.% 이상에서는 감소하는 결과를 보였다. 반면, $t_{2}$는 Si의 함량이 증가함에 따라 연속적으로 증가하였다. 즉, 0.8 wt.% C을 함유한 강에서 processing window는 Si의 함량이 약 2.5 wt.%일 때 열렸다.