• Journal of Families and Better Life
• /
• v.33 no.5
• /
• pp.87-102
• /
• 2015

The purpose of this study was to examine the relationship between job stress, turnover intention, and the moderating roles of motivation for child care work. The subjects were 238 child-care teachers who were worked at child-care centers in Seoul. Questionnaires were used to rate job stress, turnover intention, and the motivation for child care work of teachers. The collected data were mainly analyzed by descriptive statistics, t-test, one-way ANOVA, Duncan test, Pearson's correlation and the multiple regression analysis. The main results of this study were as follows. First, there were differences in turnover intention according to individual characteristics such as career at the current child-care center and total career. Second, job stress was positively correlated with turnover intention, and negatively correlated with active motivation and material motivation. And turnover intention was negatively correlated with active motivation and material motivation. Third, a moderator effect of the active motivation was found in the relationship between the job stress and the turnover intention. Especially the active motivation is suggested to reduce the negative results of job stress and turnover intention. Therefore, the results indicate the importance of the active motivation which is considered as an aptitude, interest, affection for children and self realization when child-care teachers make a decision to enter the child-care work profession.

• Journal of the Korean Chemical Society
• /
• v.39 no.12
• /
• pp.946-954
• /
• 1995

The physico-chemical nature of the rare earth oxide which was produced by the caustic fritting of monazite was studied to furnish fundamental data that are required for its efficient use and processing. It was found that the material which was mainly constituted of light rare earths and thorium was a solid solution phase of oxide whose structure was fluorite-type face centered cubic. Its density was 6.75 g/$cm^3$ and it had a uniform particle size distribution at around 1 ${\mu}m.$ The crystallinity improved by heating to elevated temperatures, whereas the solubility in HCl decreased as the crystallinity improved. Complete dissolution in conc. HCl solution in short time (30 min.) was attained by heating to 70$^{\circ}C$. The measurement of zeta potential showed its I.E.P. to be at pH 8.6 of the suspension.

• Korean Journal of Agricultural Science
• /
• v.38 no.4
• /
• pp.747-752
• /
• 2011

Wireless technology has enabled farmers monitor and control protected production environment more efficiently. Utilization of USN (Ubiquitous Sensor Network) devices also brought benefits due to reduced wiring and central data handling requirements. However, wireless communication loses signal under unfavorable conditions (e.g., blocked signal path, low signal intensity). In this paper, performance of commercial wireless communication devices were evaluated for application to protected crop production. Two different models of wireless communication devices were tested. Sensors used in the study were weather units installed outside and top of a greenhouse (wind velocity and direction, precipitation, temperature and humidity), inside ambient condition units (temperature, humidity, $CO_2$, and light intensity), and irrigation status units (irrigation flow and pressure, and soil water content). Performance of wireless communication was evaluated with and without crop. For a 2.4 GHz device, communication distance was decreased by about 10% when crops were present between the transmitting and receiving antennas installed on the ground, and the best performance was obtained when the antennas were installed 2 m above the crop canopy. When tested in a greenhouse, center of a greenhouse was chosen as the location of receiving antenna. The results would provide information useful for implementation of wireless environment monitoring system for protected crop production using USN devices.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.27 no.2
• /
• pp.87-94
• /
• 2014

In solid mechanics, the peridynamics theory has provided a suitable framework for material failure and damage propagation simulation. Peridynamics is computationally expensive since it is required to solve enormous nonlocal interactions based upon integro-differential equations. Thus, multiscale coupling methods with other local models are of interest for efficient and accurate implementations of peridynamics. In this study, peridynamic models are restricted to regions where discontinuities or stress concentrations are present. In the domains characterized by smooth displacements, classical local models can be employed. We introduce a recently developed blending scheme to concurrently couple bond-based peridynamic models and the Navier equation of classical elasticity. We demonstrate numerically that the proposed blended model is suitable for point loads and static fracture, suggesting an alternative framework for cases where peridynamic models are too expensive, while classical local models are not accurate enough.

• Geophysics and Geophysical Exploration
• /
• v.10 no.4
• /
• pp.314-321
• /
• 2007

Recently, multi-dimensional joint inversion of geophysical data based on fundamentally different physical properties is being actively studied. Joint inversion can provide a way to obtaining much more accurate image of the subsurface structure. Through the joint inversion, furthermore, it is possible to directly estimate non-geophysical material properties from geophysical measurements. In this study, we developed a new algorithm for jointly inverting dc resistivity and seismic traveltime data based on the multiple constraints: (1) structural similarity based on cross-gradient, (2) correlation between two different material properties, and (3) a priori information on the material property distribution. Through the numerical experiments of surface dc resistivity and seismic refraction surveys, the performance of the proposed algorithm was demonstrated and the effects of different regularizations were analyzed. In particular, we showed that the hidden layer problem in the seismic refraction method due to an inter-bedded low velocity layer can be solved by the joint inversion when appropriate constraints are applied.

• Archives of Pharmacal Research
• /
• v.29 no.8
• /
• pp.707-711
• /
• 2006

Bifidobacteria-loaded alginate poly-l-lysine microparticles (bap microparticles) were prepared using an air atomization method and then freeze-dried. The viability of the bap microparticles was investigated as a function of the amount of the bifidobacteria cultures, and the addition of a yeast extract, cryoprotectants, antioxidants and neutralizer. The size of the bap microparticles with and without the bifidobacteria was $84.8{\pm}28.5\;{\mu}m$ ($mean{\pm}standard$ deviation) and $113.1{\pm}38.5\;{\mu}m$, respectively. The surface morphology was slightly ellipsoid and wrinkled regardless of the incorporating bifidobacteria. The viability gradually decreased with increasing freeze-drying time. Free-flowing powdered bap microparticles were obtained at least 12 h after freeze-drying the wetted slurry of bap microparticles. However, the particles tended to aggregate when either lactose or ascorbic acid was added. The addition of a yeast extract, cryoprotectants (glycerol and lactose), antioxidants ($NaHSO_3$ and ascorbic acid) and neutralizer $(Mg_3(PO_4)_2)$ resulted in a significantly higher viability of the bifidobacteria in the bap microparticles after freeze-drying (0.34-1.84 log) compared with the culture alone.

• Journal of Digital Convergence
• /
• v.13 no.5
• /
• pp.259-267
• /
• 2015

This study is aimed at understanding the factors affecting rehospitalization of a tuberculosis patient. In a public hospital with a tuberculosis ward in Seoul, the data of 360 patients who discharged the hospital from July 1, 2012 to December 31, 2012. Data was selected from 'nursing information survey' or 'discharge analysis DB' of the department of medical records. The possibility of rehospitalization was higher in the group with those who has no job, those with medical care assistant than with health insurance, drinks about 10 times a month, personally came to the hospital, main guardian is the patient's spouse, have discharged from hospital against the doctor's advise, and principle diagnosis is not a pulmonary tuberculosis but the other respiratory disease. Therefore, it is expected that the possibility of rehospitalization would be effectively reduced if an intensive intervention is taken on the first hospitalized patients who have the features described above.

• Journal of The Korean Astronomical Society
• /
• v.28 no.2
• /
• pp.169-175
• /
• 1995

Deep V I CCD photometry of the Pegasus dwarf irregular galaxy shows that the tip of the red giant branch (RGB) is located at I = $21.15{\pm}0.10$ mag and (V - I) = $1.58{\pm}0.03$. Using the I magnitude of the tip of the RGB (TRGB), the distance modulus of the Pegasus galaxy is estimated to be $(m\;-\;M)_o\;=\;25.13{\pm}0.11$ mag (corresponding to a distance of d = $1060{\pm}50$ kpc). This result is in a good agreement with the recent distance estimate based on the TRGB method by Aparicio [1994, ApJ, 437, L27],$ (m\;-\;M)_o$ = 24.9 (d = 950 kpc). However, our distance estimate is much smaller than that based on the Cepheid variable candidates by Hoessel et al.[1990, AJ, 100, 1151], $(m\;-\;M)_o\;=\;26.22{\pm}0.20$ (d = $1750{\pm}160$ kpc) mag. The color-magnitude diagram illustrates that the Cepheid candidates used by Hoessel et al.are not located in the Cepheid instability strip, but in the upper part of the giant branch. This result shows that the Cepheid candidates studied by Hoessel et al.are probably not Cepheids, but other types of variable stars. Taking the average of our distance estimate and Aparicio's, the distance to the Pegasus galaxy is d= $1000{\pm}80$ kpc. Considering the distance and velocity of the Pegasus galaxy with respect to the center of the Local Group, we conclude that the Pegasus galaxy is probably a member of the Local Group.

• Journal of Microbiology and Biotechnology
• /
• v.9 no.5
• /
• pp.529-533
• /
• 1999

In addition to catalyzing the synthesis of dextran from sucrose as a primary reaction, dextransucrase also catalyzes the transfer of glucose from sucrose to other carbohydrates that are present or are added to the reaction digest. We have synthesized new glucans having new structures and new characteristics, by transferring D-glucose of sucrose to $\alpha$-cellulose and by using the constitutive dextransucrase obtained from Leuconostoc mesenteroides B-742CBM. The final reaction products were composed of soluble- and insoluble-glucans. The yields of soluble- and insoluble-glucans were theoretically 21% $\pm$ 2.2 and 68% $\pm$ 5.1, respectively. The remainder of the reaction products was recovered as a mixture of olgiosaccharides that could not be precipitated by 67%(v/v) ethanol. Treating the modified glucans with endo-dextranase and/or cellulase, oligosaccharides were produced that were not formed from the hydrolysis of native cellulose or B-742CBM dextran. The modification of the cellulose was confirmed by methylation and acid hydrolysis of the soluble-and insoluble-glucan. Both (1->4) and(1->6) glycosidic linkages were found in both of the glucans.

• Journal of Applied Biological Chemistry
• /
• v.49 no.1
• /
• pp.28-32
• /
• 2006

Effect of organic-C on immobilization and nitrification patterns in acidic soil was examined during 20 weeks incubation period to verify if organic amendments such as composted material can increase soil retention of N by stimulating microbial immobilization of $NH_4^+$. Four treatments were laid out: control without fertilizer N and glucose (treatment code: S), ammonium sulfate (SN), ammonium sulfate with single glucose at the commencement (0 week) of incubation (SNG), and ammonium sulfate with double glucose at 0 and 4 weeks of incubation (SNGG). Glucose application (SNG) significantly increased microbial immobilization of $NH_4^+$ within 1 week of incubation over SN. Immobilization was followed by remineralization thereafter; however, second-application of glucose (SNGG) restored $NH_4^+$ immobilization. At the same time, nitrification was significantly inhibited by glucose application as indicated by consistently low $NO_3^-$ concentration in SNG and SNGG soils, suggesting that microbial assimilation of $NH_4^+$ is predominant compared to nitrification when available C-source is abundant. These results suggest application of chemical fertilizer-N with organic amendment would have beneficial effect on soil-N retention and environmental conservation by reducing production of $NO_3^-$ which is likely to be lost through leaching or denitrification.