• Journal of the Korean institute of surface engineering
• /
• v.32 no.2
• /
• pp.172-181
• /
• 1999

The effect of the DMAB concentration, temperature, deposition time, and stabilizer concentration on the precipitation reaction of the electroless nickel plating using dimethylamine borane (DMAB) as reducing agent was investigated to by the weight gain and electrochemical method. The deposition rate was dependent with DMAB concentration. The polarization resistance of the precipitation reaction was reduced with DMAB concentration. The precipitation reaction rate of Ni-B deposits was controlled by the oxidation rate of DMAB as the source of electron. The boron content of the deposit was constant at about 5.5wt%, even when DMAB concentration in the solution was increased. The effect of temperature and stabilizer ($Pb(NO_3)_2$) concentration on deposition rate was shown to have co-dependent behaviors.

• Journal of the Mineralogical Society of Korea
• /
• v.11 no.1
• /
• pp.20-31
• /
• 1998

Adsorption of metal elements onto illite and halloysite was investigated at $25^{\circ}C$ using pollutant water collected from the gold-bearing metal mine. Incipient solution of pH 3.19 was reacted with clay minerals as a function of time: 10 minute, 30 minute, 1 hour, 12 hour, 24 hour, 1 day, 2 day, 1 week, and 2 week. Twenty-seven cations and six anions from solutions were analyzed by AAs (atomic absorption spectrometer), ICP(induced-coupled plasma), and IC (ion chromatography). Speciation and saturation index of solutions were calculated by WATEQ4F and MINTEQA2 codes, indicating that most of metal ions exist as free ions and that there is little difference in chemical species and relative abundances between initial solution and reacted solutions. The adsorption results showed that the adsorption extent of elements varies depending on mineral types and reaction time. As for illite, adsorption after 1 hour-reaction occurs in the order of As>Pb>Ge>Li>Co, Pb, Cr, Ba>Cs for trace elements and Fe>K>Na>Mn>Al>Ca>Si for major elements, respectively. As for halloysite, adsorption after 1 hour-reaction occurs in the order of Cu>Pb>Li>Ge>Cr>Zn>As>Ba>Ti>Cd>Co for trace elements and Fe>K>Mn>Ca>Al>Na>Si for major elements, respectively. After 2 week-reaction, the adsorption occurs in the order of Cu>As>Zn>Li>Ge>Co>Ti>Ba>Ni>Pb>Cr>Cd>Se for trace elements and Fe>K>Mn>Al, Mg>Ca>Na, Si for major elements, respectively. No significant adsorption as well as selectivity was found for anions. Although halloysite has a 1:1 layer structure, its capacity of adsorption is greater than that of illite with 2:1 structure, probably due to its peculiar mineralogical characteristics. According to FTIR (Fourier transform infrared spectroscopy) results, there was no shift in the OH-stretching bond for illite, but the ν1 bond at 3695 cm-1 for halloysite was found to be stronger. In the viewpoint of adsorption, illite is characterized by an inner-sphere complex, whereas halloysite by an outer-sphere complex, respectively. Initial ion activity and dissociation constant of metal elements are regarded as the main factors that control the adsorption behaviors in a natural system containing multicomponents at the acidic condition.

• Journal of the Mineralogical Society of Korea
• /
• v.9 no.1
• /
• pp.1-6
• /
• 1996

Woolastonite from Susan occurs as intercalations in limestone beds of Lower Paleozoic Joseon Supergroup. It is a thermal metamorphic product of impure limestone. Electron microprobe analysis shows that it is considerably pure wollastonite. It has triclinic cell with a=7.932$\AA$, b=7.328$\AA$, c=7.069$\AA$, $\alpha$=89.995$^{\circ}$, $\beta$=$95.255^{\circ}$, and $ \Upsilon=103.367^{\circ}$.Dissolution behaviors of wollastonite have been studied conducting three different dissolution experiments; two different reactions with HC1 (one batch and one re-initialization experiment) and one traction with distilled water. In the batch type powder wollastonite-HCl reaction, pH of solution rapidly increases in the early stage and then its rate of increase slows down to reach plateau resulting in parabolic relationship with time. It is represented by the early rapid rise and fall in pH giving a sharp pH-edge and succeeding slow rise in the re-initialization experiment. The early rapid rise in pH is due to the rapid sorption of H- in solution to oxygens on the reactive surface of wollastonite and the fall in pH means that all reactive surface sites are occupied by H- ions and no more H- adsorption occurs. The slow rise in pH following the pH- edge is due to the dissolution of wollastonite as evidenced by the correlation of pH variation and cation concentration. Dissolution of powder wollastonite in HCl shows linear trend with time. Si is dissolved predominantly over Ca at a constant rate. Ca is dissolved predominantly in the very early stage. Dissolution rate of coarse-grained wollastonite fragments in distilled water is parabolic with times howing a rapid reaction in the early stage and a slow reaction in the advanced stage. The Ca/Si ratio in solution is high in the case of coarse-grained wollastonite fragment as compared with powder wollastonite. The coarse-grained wollastonite fragment-water (acid) reaction resulted in the solution with an elevated constant pH value (alkaline) giving an important significance on the environmental view point.

• Textile Coloration and Finishing
• /
• v.9 no.6
• /
• pp.42-50
• /
• 1997

Bola-form electrolytes were synthesized by the reaction of pyridine with 1, 4-dibromobutane or 1, 10-dibromodecane, respectively. The effects of these electrolytes were studied in the dyeing of wool fabric with Orange II. The depth of shade of wool fabric with pretreated electrolyte were independent to the dyeing temperature and higher than those of one untreated. In the case of pretreating the electrolytes, there are no differences in the effects in dyeing behaviors between the 1, 4-dipyridiniumbutane and 1, 10-dipyridiniumdecane. But when the wool fabrics were dyed in water containing these electrolytes, dyeing behaviors were different to the numbers of carbon atom in electrolytes. 1, 4-dipyridiniumbutane has positive effects on the dyeing.

• Polymer(Korea)
• /
• v.37 no.2
• /
• pp.240-248
• /
• 2013

The curing behaviors of diglycidyl ether of bisphenol A (DGEBA) with mercaptan hardener were studied by the comparison with amine-adduct type hardener. Curing behaviors were evaluated by DSC at dynamic and isothermal conditions. In the DSC, the dynamic experiments were based on the method of Kissinger's equation, and the isothermal experiments were fitted to the Kamal's kinetic model. Activation energy of epoxy/amine-adduct type hardener was ca. 40 kcal/mol. As the functional group of mercaptan hardener, -SH increased, on epoxy/mercaptan hardeners, the activation energies decreased from 28 to 19 kcal/mol. Epoxy/amine-adduct type hardener was initiated at $90^{\circ}C$ or higher. However, epoxy/mercaptan hardeners reduced the initiation temperatures below $80^{\circ}C$ and shortened the durations of curing reaction within 10 min. We found out that the reaction kinetics of epoxy with mercaptan hardener followed the autocatalytic reaction models, and the maximum reaction rates were shown at the conversions of 20~40%.

• Proceedings of the Korean Radioactive Waste Society Conference
• /
• 2018.11a
• /
• pp.299-300
• /
• 2018

Electrochemical behaviors of Nb ion in the $LiCl-KCl-NbCl_5$ molten salt were examined. Cyclic voltammograms with different scan rates and scan range at $450^{\circ}C$ showed possible electrochemical redox reactions which were identified by comparison to the literature data. Peak potentials for each redox reaction were consistent with the literature, but some redox reactions were not clearly defined due to the formation of subchloride compound in chloride salt. The electrochemical behaviors of Nb ion related to the subchloride formation as well as Nb metal deposition will be investigated for the future work.

• Journal of Korean Association for Spatial Structures
• /
• v.22 no.1
• /
• pp.25-32
• /
• 2022

The seismic behaviors of the arch structure vary according to the rise-span ratio of the arch structure. In this study, the rise-span ratio (H/L) of the example arch structure was set to 1/4, 1/6, and 1/8. And the installation angle of the seismic isolator was set to 15°, 30°, 45°, 60° and 90°. The installation angles of the seismic isolator were set by analyzing the horizontal and vertical reaction forces according to the rise-span ratio of the arch structure. Due to the geometrical and dynamic characteristics of the arch structure, the lower the rise-span ratio, the greater the horizontal reaction force of the static load, but the smaller the horizontal reaction force of the dynamic load. And if the seismic isolator is installed in the direction of the resultant force of the reaction forces caused by the seismic load, the horizontal seismic response becomes small. Also, as the installation angle of the seismic isolator increases, the hysteresis behavior of the seismic isolator shows a plastic behavior, and residual deformation appears even after the seismic load is removed. In the design of seismic isolators for seismic response control of large space structures such as arch structures, horizontal and vertical reaction forces should be considered.

• Korean Journal of Child Studies
• /
• v.3
• /
• pp.63-81
• /
• 1982

The purpose of this study is to relate social behaviors and child-rearing practices to the popularity of preschool children in Korea. Specifically, four major questions were raised and studied First, the relationship between a child's popularity and his/her social behaviors was examined. Second, this relationship was explored as a function of the child's sex. Third, the relationship between a child's popularity and maternal childrearing practices was investigated. Fourth, this relationship was explored as a function of the child's sex. The subjects of this study were 113 middle class preschool aged children and their mothers. Sociometric choices and peer-perceived social behaviors were obtained from these children using Moore's (1973) Sociometric Status Test. Mothers of these children described their childrearing practices in a Q-sort format of Child-Rearing Practices Report (CRPR) developed by Block (1965). The analyses of the data using Kendall's Tau Correlation Coefficient bore the following results: 1. Patterns of social behaviors shown by either popular or unpopular children were distinct; Popular children were friendly and conformative, while unpopular children were aggressive, non-conformative and independent. 2. Patterns of social behaviors in relation to the popularity and the unpopularity differed as a function of the child's sex; Popular boys tended to be active while popular girls were likely to be unaggressive, independent and not-teasing. Unpopular boys showed a great amount of discipline their daughters by means of non-punitive punishment and to express negative reaction to the sibling rivalry among their children. These mothers tended not to enjoy their 3. Certain patterns of maternal child-rearing practices tended to be related to the popularity status of the child; The mothers of popular children as compared to those of unpopular children enjoyed their roles as mothers and didn't use non-punitive punishment. 4. Patterns of maternal child-rearing practices in relation to the child's popularity and unpopularity differed as a function of the child's sex; The mothers of popular boys unlike those of popular girls tended to emphasize on their sons' achievement and perceived that their husbands were greatly involved with their sons. The mothers of unpopular boys appeared to show negative affection toward their sons. The mothers of unpopular girls were likely to displine their daughters by means of non-punitive punishment and to express negative reaction to the sibling rivalry among their children. These mothers tended not to enjoy their roles as mothers and did not believe that their daughters would behave as they should.

• Journal of Ginseng Research
• /
• v.31 no.3
• /
• pp.137-141
• /
• 2007

To evaluate the antiatopic effect of Korea Red Ginseng (RG, steamed root of Panax ginseng C.A. Meyer, Family Araliaceae), its inhibitory effect on passive cutaneous anaphylaxis reaction and itching in mice was measured. RG and its ingredient saponin fraction (SF) potently inhibited passive cutaneous anaphylaxis (PCA) reaction and scratching behaviors. RG at a dose of 100 mg/kg and SF at a dose of 50 mg/kg significantly inhibited the scratching frequency by 32% and 38%, respectively. RG and SF also inhibited the degranulation and protein expression of tumor necrosis factor $(TNF)-{\alpha}$ and interleukin (IL)-4 of RBL-2H3 cells induced by IgE-antign complex. However, polysaccharide fraction of RG did not inhibit it. Based on these findings, RG can improve allergic skin disorders atopic dermatitis and contact dermatitis by the regulation of $TNF-{\alpha}$, and IL-4 produced by mast cells and basophils and their membrane stabilization.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.13 no.4
• /
• pp.318-325
• /
• 2000

Dynamic behaviors of saturated-fatty acids $C_{16}$, $C_{18}$, $C_{20}$ and 8A5H with azobenzene were measured by displacement current method when the molecules are stimulated by pressure light and heat. When a barrier was compressed I-A, $\pi$-A isotherms of $C_{16}$, $C_{18}$, and $C_{20}$ were similar to each other but the displacement current of $C_{20}$ which has a long alkyl chain was relatively low. 8A5H showed the form of double liquid films and had a reversible reaction when a barrier was compressed and then expanded. When the molecules of 8A5H were stimulated by 365[nm] light the positive currents which were generated by the structural changes from trans to cis were measured. But the negative currents of the structural changes from cis to trans by 450[nm] light were too weak to detect. When the temperature of the water subphase was increased the surface pressures of the monolayers were increased early because of the thermal activations of the molecules and the double liquid films of 8A5H were disappeared above 40[$^{\circ}C$]EX>].