• Journal of the Korean Magnetics Society
• /
• v.9 no.1
• /
• pp.23-28
• /
• 1999

${\Alpha}-Fe_2O_3$ was accomplished by chemical method as low temperature as possible and the crystallographic and magnetic properties have been studied by Mossbauer spectroscopy and X-ray diffraction. The sample heated at 15$0^{\circ}C$ is found to have a Corundums symmetry with the hexagonal lattice constant a=8.26$\pm$0.05$\AA$, c=8.75$\pm$0.05$\AA$. The M$\"{o}$ssbauer spectra between the 4.2K and the room temperature show that the ${\Alpha}-Fe_2O_3$ crystallized with a single phase and fine sizes. The particle size distribution has the Gaussian distribution center at 98$\AA$ and the half width of 32$\AA$.TEX>.

• Journal of the Korean Magnetics Society
• /
• v.9 no.1
• /
• pp.29-34
• /
• 1999

$Y_{2.5}La_{0.5}Fe_5O_{12}$ is fabricated by a sol-gel method and the magnetic properties of single phase garnet are investigated by using X-ray diffraction, vibrating sample magnetometer, scanning electron microscopy and M$\"{o}$ssbauer spectroscopy. The single phase powders garnet was fired at 100$0^{\circ}C$ for 8 hours. The crystal structures of samples are cubic garnet. Mossbauer spectroscopy were measured from 13 K to 750 K. M$\"{o}$ssbauer spectra show that the iron exist ferric trivalence in sample. The spin wave constants were determined $B_{3/2}=0.32{\pm}0.05,\; C_{5/2}=0.18{\pm}0.05$ and Debye temperature were determined 382 K at 24(d) site and 246 K at 16(a)-site. The saturation magnetization $M_s$ of powder is 25 emu/g. 25 emu/g.

• Analytical Science and Technology
• /
• v.20 no.4
• /
• pp.339-346
• /
• 2007

To search the ninhydrin derivatives that have high chromogenic and fluorogenic properties, molecular holographic quantitative structure property relationship (HQSPR) models on the reactivity between glycine and ninhydrin analogues as latent fingerprint detector were derived and investigated quantitatively. The ${\varepsilon}LUMO$ (e.v.) energy of ninhydrin molecule was an important factor to reactivity of ninhydrin. And, it is suggested that the nucleophilic reaction by orbital-controlled reaction from the frontier molecular orbital (FMO) interaction between glycine and ninhydrin derivatives was more superior than that of electrophilic reaction by charged controlled reaction. The analytical results in atomic contribution maps also shows that the reactivity of ninhydrin was increased by meta-substituents as strong electron withdrawing groups on the benzo ring. Therefore, it is sugested by HQSPR and QSPR model that the 5,6-dinitroninhydrin molecule would increase the reactivity as much as three times as compared to none substituted ninhydrin molecule.

• The Journal of the Korea Contents Association
• /
• v.14 no.3
• /
• pp.186-194
• /
• 2014

The purpose of this paper is to review the meaning of extended application of workers' compensation for artists. This study explains by giving specific two examples. The first case is about broadcasting extra who is permitted to receive compensation from Korea Workers' Compensation & Welfare Service without filing a suit. Whereas, The second case is about musical stage crew who is not permitted to obtain compensation for accident during work. The reason why he could not receive compensation is not because he is regarded as worker, but because he is regarded as individual businessman. Extended application of workers' compensation for artists could be a double-edged sword for workers through two cases. Firstly, Broadcasting extras could become much easier to receive workers' compensation according to precedent. Secondly, It is more difficult to get the workers' compensation by the reason of not applying for workers' compensation admission like the second case, even though the second case of forms of employment is similar to that of the first. In other words, New compensation development could generate another obstacles to enter compensation systems. Extended application of workers' compensation should be operated with covering artists' compensation case by case.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
• /
• v.4 no.1
• /
• pp.114-123
• /
• 1993

The authors applied Toddler Temperament Scale(TTS) to ADHD patient group, other disease group and normal control group to elucidate temperamental characteristics of ADHD patients in their toddler stage. 1) ADHD group showed significant difference from the control group in 'activity', 'rhythmicity', 'approach', 'adaptability', 'intensity', 'persistence' and 'threshold' categories. 2) ADHD group and other disease showed significant difference from the control group in 'adaptability' and 'persistence' categories. 3) ADHD group was significantly different from other disease group or control group in 'activity' and 'approach' categories. 4) In total scores of TTS, ADHD group and other diease group showed significant difference from control group. 5) Classification ratio of TTS for ADHD by discriminant analysis was 84.3%. Above results suggest that the ADHD patients may reveal characteristic traits in their toddler stage Further research should be focused on the development and refinement of assessment tools for the early detection and prevention for ADHD.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.8 no.4
• /
• pp.93-99
• /
• 2000

Treatment of shaving scrap, a chrome containing solid scrap generated by leather manufacturing process, has been so far depended on mainly incineration, soil landfill and ocean dumping, which give bad impact on environment and cause pollution. Shaving scrap generates from the mechanical work for controlling the final thickness of leather and its main components are collagen protein and pan of chromium compound. For the purpose of reusing this leather waste as resources, researches in connection with collagen fiber recovery, gelable protein recovery and liquid fertilizer is being speedily progressed. In the experiment, shaving scrap went through wet pulverizing treatment by physical and chemical methods. Then, making the leather sheet evenly, it is mixed with natural latex and every kind of binding materials in the container, and the mixtures were passed through experimental hydraulic press machine and applied to Fourdrinier machine respectively. Lastly, a test for fading out physical strength and properties of multiple-purpose of leather-like material was performed on a continuous leather sheet prepared by the experiment. In result, the physical strength and properties of leather-like material showed noticeable differences according to mixing ratio of binding materials, beating methods and the Ends of binding materials selected, and generally tear strength was the weakest property among others. Also, by the pilot scale experiment in sequence, it was possible to manufacture recycled goods made of soft and hard types of leather-like material with various performances.

• Journal of the Korean Magnetics Society
• /
• v.7 no.5
• /
• pp.237-242
• /
• 1997

The microstructure and soft magnetic properties of as-deposited Fe-Hf-O thin film alloys, which are produced at $P_{O2}=10%$ by rf magnetron sputtering method in $Ar+O_2$ mixed gas atmosphere, is investigated. Newly developed $Fe_{82}Hf_{3.4}O_{14.6}$ film exhibits good soft magnetic properties with $4{\pi}M_s=17.7$ kG, $H_c=0.7$ Oe and ${\mu}_{eff}$(0.5~100MHz)=2,500, respectively. The Fe-Hf-O films are composed of $\alpha$-Fe nanograins and amorphous phase with larger amounts of Hf and O elements which chemically combine each other. With increasing Hf area fraction, Hf and O contents increased proportionally. It was considered that O content in films was determined by Hf contents, because O was chemically combined with Hf. It results from decreasing the $\alpha$-Fe grain size by precipitates (Hf and O), high electrical resistivity. The $Fe_{82}Hf_{3.4}O_{14.6}$ film exhibits the quality factor (Q=$\mu$'/$\mu$") of 25 at 20 MHz. These good frequency characteristics are considered to be superior to other films already reported.o other films already reported.

• Korean Journal of Ichthyology
• /
• v.3 no.1
• /
• pp.48-57
• /
• 1991

Changes of the activities of the hepatic cells of female mud skipper, Boleophthalmus pectinirostris were investigated under transmission electron microscopy. Monthly changes of gonadosomatic index(GSI) and hepatosomatic index(HSI), variations of protein and nucleic acid contents(total RNA and DNA) of the liver tissues with the gonadal development phase were also studied. GSI began to increase from May(the growing stage), reaching the maximum value in late June(the mature stage), and then it began to decrease from late July(the degenerative stage), reaching the lowest value in late September. Monthly variations of HSI were negatively related to GSI. HSI decreased in the summer season when the ovary was getting mature and reached the maximum in mid October when the ovary was degenerating. In June(the mature stage), the female hepatic cells of the liver tissues became large and nuclei were hypertrophic. The amounts of glycogen particles and lipid droplets in the cells gradually decreased, while a number of granular endoplasmic reticulum increased. It was assumed that well-developed granular endoplasmic reticulum binding ribosomes are supposed to play the leading role in protein synthesis and deposition for vitellogenin in the cytoplasm. In July(the spawning period), glycogen particles and lipid droplets gradually increased, and then these substances were still observed in large quantity in August(the degenerative stage). The protein contents of the liver tissues with the gonadal phases of the ovaries were shown the maximum value($4.720{\pm}0.103\;mg/g$) in June, and afterwards gradually decreased being the minimum($3.640{\pm}0.130\;mg/g$) in July, and then gradually increased in August. The mean total RNA contents per gram of the liver tissues appeared the maximum($0.523{\pm}0.040\;mg/g$) in June, and afterwards gradually decreased to the minimum($0.158{\pm}0.006\;mg/g$) in July and slightly increased in August again. From these results, it could be assumed that protein contents were closely related to RNA contents. The mean total DNA contents per weight (gr) of the liver tissues appeared to be similar although there were some monthly fluctuations. The ratio of the mean total RNA/DNA were 0.745 in June, 0.262 in July, 0.341 in August respectively.

• Journal of the Korean Magnetics Society
• /
• v.13 no.6
• /
• pp.237-242
• /
• 2003

$Ti_{1-x}$$^{57}$ F $e_{x}$ $O_2$(0.0$\leq$x$\leq$0.07) compounds were fabricated using the sol-gel method, and the crystal structure and magnetic properties were investigated as a function of doped $^{57}$ Fe concentration. X-ray diffraction patterns showed a pure anatase single phase, without any segregation of Fe into particulate. With varying $^{57}$ Fe concentration, we could observe unusual magnetic phenomena in these materials. Doping $^{57}$ Fe into the Ti $O_2$ nonmagnetic semiconductor formed magnetic properties, but the gradual increase of $^{57}$ Fe concentration decreased rapidly the ferromagnetic properties rather than enhanced the ferromagnetic properties. Obvious ferromagnetic behavior was shown for the samples with x$\leq$0.01, while paramagnetic behavior was shown for the sample with x$\geq$0.03. These phenomena could be verified using Mossbauer measurement. Separation of the ferromagnetic phase (sextet) and the paramagnetic phase (doublet) of the samples with different $^{57}$ Fe concentration was characterized. Samples with x$\leq$0.01 have sextet and doublet simultaneously, but samples with x$\geq$0.03 have only doublet at room temperature. This indicates that the sample x$\leq$0.01 have the ferromagnetic phase at room temperature. This result corresponded with the M-H loops referenced above and reveals an interesting feature that there is a critical limit of $^{57}$ Fe concentration (0.01$\leq$0.01 samples was fundamentally attributable to the paramagnetic phase as well as the ferromagnetic phase.e.

• Journal of the Korean Magnetics Society
• /
• v.22 no.3
• /
• pp.85-90
• /
• 2012

Oxidation of the $Nd_2Fe_{14}B$ compound crystal and its effect on the coercivity of the fine $Nd_2Fe_{14}B$ crystal particles were investigated. Oxidation kinetics of the $Nd_2Fe_{14}B$ compound crystal was investigated using an excessively grown $Nd_2Fe_{14}B$ grains in the $Nd_{15}Fe_{77}B_8$ alloy ingot. Oxidation of the $Nd_2Fe_{14}B$ compound crystal occurred by dissociation of the phase into multi-phase mixture of ${\alpha}$-Fe, $Fe_3B$, and Nd oxides. Oxidation rate of the $Nd_2Fe_{14}B$ compound crystal showed no dependence on the crystallographic direction. The oxidation reaction was modeled according to simple linear relationship. Activation energy for the oxidation of $Nd_2Fe_{14}B$ compound crystal was calculated to be approximately 26.8 kJ/mol. Fine $Nd_2Fe_{14}B$ crystal particles in near single domain size was prepared by ball milling of the HDDR-treated $Nd_{15}Fe_{77}B_8$ alloy, and these particles were used for investigating the effect of oxidation on the coercvity. The near single domain size $Nd_2Fe_{14}B$ crystal particles (${\fallingdotseq}0.3\;{\mu}m$) had high coercivity over 9 kOe. However, the coercivity was radically reduced as the temperature increased in air (<2 kOe at $200^{\circ}C$). This radical coercivity reduction was attributed to the soft magnetic phases, ${\alpha}$-Fe and $Fe_3B$, which were formed on the surface of the fine particles due to the oxidation.