• Journal of the Korean Ceramic Society
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• v.28 no.5
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• pp.365-372
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• 1991

LAS (lithium aluminosilicate) sol was synthesized using the hydrolysis-condensation reaction of TEOS, chelated Al(OBus)3 and Li-salt with H2O in alcohol (EtOH+2-Propanol) medium. Effects of important reaction parameters on the properties of sol and gel-derived LAS were examined. The crystallization of the sol-gel derived LAS with ${\beta}$-spodumene composition began at ∼600$^{\circ}C$, and a series of polymorphic transformations occurred as temperature was increased to 1100$^{\circ}C$: amorphous LAS\longrightarrowhexagonal LiAl(SiO3)2\longrightarrow${\beta}$-spodumene. Lowering Li content in the gel enhanced densification and retarded the crystallization significantly. Optimum reaction conditions of LAS sol formation for thin coating applications were derived from rheological measurements, and these can be summarized as: H2O/total alkoxides molar ratio=4, pH=∼2.5, and aging time of ∼250h.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.1130-1133
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• 1993

In this paper, it is discussed the correlation between shape of tree and internal partial discharge in low density polyethylene(LDPE) blended with organic compounds that used to improve the effect of resistance to treeing. Initiation and growing of tree are retarded in specimens blended with organic compounds that comprised radical having large electron affinity, and also discharge magnitude and counts of discharging pulse per unit time in these samples are more than those in others. It is observed that the shape of tree in these samples is bush type, but in case of pure LDPE samples dendrite type.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.1393-1393
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• 2001

This paper reviews the Lawson formula which predicts the sound field of a point force in arbitrary motion. The acoustic density was represented by an integral of integrand including the generalized function and its partial derivative at retarded time. After skillful integration, a mathematically exact formula was yielded with some terms which were still remained in need of numerical calculations. The significance of further mathematical progress is discussed in this paper. And also, the adequacy of procedures deriving the far- and near-field terms is investigated from the viewpoint of radiation.

• Journal of the Korean Society of Mechanical Technology
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• v.13 no.4
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• pp.101-108
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• 2011

On cold start operation of an SI engine, a catalyst shows poor performance before it reaches activation temperature. Therefore, fast warmup of the catalyst is very crucial to reduce harmful emissions. In this study, an appropriate control strategy is investigated to increase exhaust gas temperature through changes of spark timing. Combustion stability is also considered at the same time. Exhaust gas temperature and pressure of combustion chamber are measured to investigate the effects of spark timings on cold start and idle performance. Experiments showed that retarded spark timing promotes the combustion at the end of expansion stroke and increases exhaust gas temperature during cold start.

• Korean Journal of Poultry Science
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• v.2 no.1
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• pp.4-6
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• 1975

Field trials and research works have shown that the sexually retarded pullets are better equipped to lay larger eggs at the commencement of lay than the pullets grown under the natural conditions with no control over the rate of maturity. The method of delaying the sexual maturity by restricting the nutrient intake is receiving a considerable attention from the research workers, since the nutrient restriction can be a method of reducing the rearing cost. Many experiments were carried out to study the effect of different methods of restricting the nutrient intake of the chicken. But the comparisons between these experiments are difficult because of the differences in the environment, management, type of breed and feed, and in the length of the time during which the feed intake was restricted. In addition the comparisons were not made on an economic basis in these experiments. This experiment was designed to provide information on the reproductive responses to three different methods of restricting the nutrient intake in a egg type stock and to establish which methods are economically profitable. (omitted)

• Archives of Metallurgy and Materials
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• v.64 no.3
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• pp.913-916
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• 2019

For the reliable applications of silver nanowires, AgNW, which is used as a conductive transparent film in electronic devices, the isothermal degradation behaviors of AgNW films with and without overcoating were investigated. Accelerated isothermal degradation was performed as a function of temperature, time, and atmosphere. Electrical resistance and optical transmittance were measured and correlated with the microstructural damages, such as formation of oxide particles and fragmentations of AgNW, which were quantitatively determined from the scanning electron micrographs. The overcoating retarded the formation of oxide particles and subsequent fragmentations as well as resulting degradation in electrical resistance without affecting the optical transmittance.

• Journal of Korean Academy of Nursing
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• v.35 no.1
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• pp.5-15
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• 2005

Purpose: This study was conducted to develop a behavioral checklist to predict an autistic disorder and to identify the earliest detecting time. Method: One hundred and fifty eight children including normal, autistic, institutionalized normal, and retarded were assessed using critical interaction behavioral markers from literature review. Data was collected by semi-structured mother-child interaction by videotape recording and analyzed byfactor analysis, Cronbach a, Kappa, $x^2$, and Duncan. Result: Ten behavioral markers were sorted into 2 factors; joint-attention and synchronized behavior. Autistic children were impaired in pretend play, odeclarative pointing, proimperative pointing, gaze-monitoring, referential looking, showing, joint-attention, rhythmical vocal exchange, and synchronized laughing. The sychronized behavior was also a critical marker to predict the autistic disorder. However, it was difficult to differentiate autistic disorder from mental retardation. In addition, the appropriate detecting time was around 18 months after birth. Conclusion: This checklist should be behavior markers to predict autistic disorder and could be useful as educational material at children's clinics, parents class, and for caregivers in the health center. In addition, early detection should lead to treatment being started as soon after 18 months of age as possible.

• Korean journal of food and cookery science
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• v.18 no.6
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• pp.619-624
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• 2002

To enhance the nutritional quality of the Soboru bread, a dietary fibers extracted from Kombu was added into wheat flour in the amounts of 0, 1, 3, and 5% and the quality of the baked products was characterized. The inherent water holding capacity of the added dietary fibers raised weight of the bread while specific volume and density values were decreased at the same time. Increasing the amount of dietary fiber resulted in the decreased setback time of the raw materials in amylogram. The lower textural hardness of the dietary fiber-enriched bread after one-day storage at room temperature could be attributed to the retarded retrogradation of the starch. Darkened surface of the bread as indicated by the Hunter colorimetric values and the accompanied change in flavor did not significantly influence the sensory evaluation of the products. Judging from texture, taste and overall acceptability of the product, recommended substitution level for the dietary fiber in Soboru bread was 3% or less. Increased intake of the dietary fibers, accompained with more use of seaweed, was expected through the suggested functional bread.

• Korean Journal of Food Science and Technology
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• v.20 no.5
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• pp.637-643
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• 1988

The useful life of frying oil was increased by treating the frying oil with a composited powder comprising water, citric acid and porous rhyolite carrier. The color darkening and foaming tendency of the oil during frying operation was apparently retarded. Increase rates of polar lipid components, dielectric constant and formation of the conjugated dienes and trienes of the used frying oil were reduced to two thirds of the oil without treatment during 84 hr frying operation. Iodine value and polyenoic index was also much less decreased by treatment. The treatment, however, have no significant effect to inhibit the decrease of smoke point and the increase of viscosity.

• Bulletin of the Korean Chemical Society
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• v.23 no.4
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• pp.580-586
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• 2002

We investigated the effect of ionic component on crystalline morphology development during isothermal annealing in a sodium neutralized sulfonated poly(ethylene terephthalate) ionomer (Ion-PET) by time-resolved small-angle x-ray scattering (TR-SAX S) using synchrotron radiation. At early stage in Ion-PET, SAXS intensity at a low annealing temperature (Ta = 120 $^{\circ}C)$ decreased monotonously with scattering angle for a while. Then SAXS profile showed a peak and the peak position progressively moved to wider angles with isothermal annealing time. Finally, the peak intensity decreased, shifting the peak angle to wider angle. It is revealed that ionic aggregates (multiplets structure) of several nm, calculated by Debye-Bueche plot, are formed at early stage. They seem to accelerate the crystallization rate and make fine crystallites without spherulite formation (supported by optical microscopy observation). From decrease of peak intensity in SAXS,it is suggested that new lamellae are inserted between the preformed lamellae so that the concentration of ionic multiplets in amorphous region decreases to lower the electron density difference between lamellar crystal and amorphous region. In addition, analysis on the annealing at a high temperature (Ta = 210 $^{\circ}C)$ by optical microscopy, light scattering and transmission electron microscopy shows a formation of spherulite, no ionic aggregates, the retarded crystallization rate and a high level of lamellar orientation.