• Journal of Magnetics
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• v.16 no.4
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• pp.457-460
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• 2011

In this paper, magnetic property and magnetocaloric effect (MCE) in perovskite manganites of the type $La_{(0.75-X)}Ce_XCa_{0.25}MnO_3$ (x = 0.0, 0.2, 0.3 and 0.5) synthesized by using the standard solid state reaction method have been reported. From the magnetic measurements as a function of temperature and applied magnetic field, we have observed that the Curie temperature ($T_C$) of the prepared samples strongly dependent on Ce content and was found to be 255, 213 and 150 K for x = 0.0, 0.2 and 0.3, respectively. A large magnetocaloric effect in vicinity of $T_C$ has been observed with a maximum magnetic entropy change (${\mid}{\Delta}S_M{\mid}_{max}$) of 3.31 and 6.40 J/kgK at 1.5 and 4 T, respectively, for $La_{0.55}Ce_{0.2}Ca_{0.25}MnO_3$. In addition, relative cooling power (RCP) of the sample under the magnetic field variation of 1.5 T reaches 59 J/kg. These results suggest that $La_{0.55}Ce_{0.2}Ca_{0.25}MnO_3$ compound could be a suitable candidate as working substance in magnetic refrigeration at 213 K.

• Journal of Digital Contents Society
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• v.17 no.1
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• pp.11-21
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• 2016

To provide more efficient and exact search result, internet systems will rely more and more on semantic web. Ontology is one of the important methods for implementation of semantic web. Ontology is used to implement an explicit formal vocabularies to share. However, important problems rise when dealing with ontology. Ontologies are typically subject to change because they are living. In order to handle ontology data change situation, a version handling system is needed to keep track of changes. For example, the queries subject to the previous ontology may become inconsistent and must be updated according to the newest version of ontology. Although many research was done in this area, there are still many problems to overcome. In this paper, we propose class and property transition graph for query transformation. The graph is created when ontology data is changed and applied to query transformation.

• Journal of Technologic Dentistry
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• v.23 no.1
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• pp.31-43
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• 2001

This study was performed to observe the micro-structure change of surface, behavior of oxide change of element, the component transformation of the alloy and the bonding strength between the porcelain interface in order to investigate effects of indium, tin on interfacial properties of porcelain fused to low gold alloy. Hardness of castings was measured with a micro-Vicker's hardness tester. The compositional change of the surface of heat-treated specimen was analyzed with an EDS and an EPMA. The interfacial shear bonding strength between alloy specimen and fused porcelain was measured with a mechanical testing system(MTS 858.20). The results were as follows: 1) The hardness value of alloy increased as increasing amount of indium addition. 2) The formation of oxidation increased as increasing indium and tin contents after heat treatment. 3) Diffusion of indium and tin elements increased as increasing indium and tin contents in metal-porcelain surface after porcelain fused to metal firing. 4) The most interfacial shear bonding strength was increased as increasing a composition of adding elements, and a heat-treatment time, and an oxygen partial pressure. From the results of this study it was found that the addition of alloying elements such as indium and tin increase hardness of as-cast alloy, produce surface oxide layer of adding elements by heat-treatment which may improve interfacial bonding strength between alloy and porcelain.

• The Journal of Korean Academy of Prosthodontics
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• v.45 no.6
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• pp.769-779
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• 2007

Statement of problem. When TiN coating is applied to the abutment screw, occurrence of greater preload and prevention of the screw loosening could be expected due to decrease of frictional resistance. However, the proper thickness of TiN coating on abutment screw has not been yet reported. Purpose. The purpose of this study is to find out the appropriate TiN coating thickness by evaluating the detorque force and the surface change of titanium abutment screw with various TiN coating thickness. Material and methods. 1. Material Thirty five non-coated abutment screws were prepared for TiN coating. TiN coatings were prepared by Arc ion plating method. Depending on the coating deposition time(CDT), experimental groups were divided into 6 groups(CDT 30min, 60min, 90min, 120min, 150min, 180min) and those of 1 group was not coated as a control group. Each group was made up of 5 abutment screws. 2. Methods FE-SEM(Field Emission Scanning Electron Microscoper) and EDX(Energy Dispersive X-ray Spectroscopy) were used to observe the surface of the abutment screw. Electric scales was used to measure the weight of the abutment screw after the repeated closing and opening of 10 trials. Detorque force was measured with digital torque gauge, at each trial. Results. 1. As the coating deposition time increased, the surface became more consistent and smooth. 2. As for the abutment screws that were TiN coated for more than 60 minutes, no surface change was found after the repeated closing and opening. 3. The TiN coated abutment screws showed less weight change than the non-coated abutment screws. 4. The TiN coated abutment screws showed higher mean detorque force than the noncoated abutment screws. 5. The abutment screw coated for 60 minutes showed the highest mean detorque force. Conclusion. The coating layer of proper thickness is demanded to obtain consistent and smooth coating surface, resistance to wear, and increased detorque force of the abutment screw. In conclusion, the coating deposition time of 60 minutes indicated improved mechanical property, when TiN coating was conducted on titanium abutment screw.

• Journal of dental hygiene science
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• v.10 no.6
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• pp.459-464
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• 2010

The purpose of this study was to evaluate the physical properties of hydrophilic polyvinyl siloxane impression materials as change of material's storage temperatures. Working time, strain-in-compression, elastic recovery and consistency were tested according to ISO Standard NO. 1563. The results are as followed. 1. Working time decreased in cold storage. 2. Strain-in-compression was different in storage temperatures. Material's strain-in compression in cold temperatures were higher than in room temperature and in incubator. 3. A coefficient of elastic recovery varied by storage temperatures. The rate in cold temperature was the lowest and in incubator was the highest. 4. Consistency of impression substance different in storage temperatures. The extent in cold temperature is the highest and in incubator was the lowest. Statistical analysis(SPSS 14.0k, p>0.05) showed that storage temperature affect to material's physical properties. We recognized that the physical properties of polyvinyl siloxane impression materials were changed according to storage temperature.

• Journal of the Korean Society of Costume
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• v.59 no.8
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• pp.49-65
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• 2009

As basic materials in this research, 874 pieces of engraving that recorded the garment produced by diverse authors in the 17-18th century were collected among the collections of male and female garment in the engraving kept by National Library of France and 216 pieces of engraving were classified among them to observe justaucorps as stated in the materials. Since type of justaucorps in the 18th century can be classified by difference in shape and change through the above engraving materials in large quantity and the shape and composition can be compared and analyzed with other materials such as picture, stored garment, written materials without difficulty, the chronology can be composed by single type of justaucorps. Intending to understand the change in composition caused by type classification and pattern making as per analysis of type property of justaucorps, the men's upper garment in France in the 18th century. Checking change in design per from and materials, justaucorps of 1680-1700s was in silhouette where waist in the length above knee was adhered and slightly spread to lower part. In the type of 1710-1750s, waist adhered remarkably and many pleats were made under waist to produce volume of form that spread to lower part like skirt. In the type of 1760-1780s, straight silhouette was attached to whole body and end of front adjustment in slant line turns to rear part. The developmental aspect of construction can be checked by making pattern. Changing the cutting line of body plate to smoothly connect section and to try to adhere to the body, the development of simpler and delicate pattern production technique was confirmed.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1657-1658
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• 2006

An external electrode fluorescent lamps (EEFLs) have the advantage of a long lifetime in the early stages of the study on plasma discharge, interest in the lamp continues. Studies on the operation of external electrode fluorescent lamps have focused mainly on its use of a type of high frequency (MHz). By performing high brightness using a square wave operation method with the low frequency below 100kHz, which is applied to a narrowed tube type lamp that has several mm of lamp diameter. To solve these problems of CCFL, EEFL (External Electrode Fluorescent Lamp) is introduced. Because electrode of EEFL is on the outer surface of discharge tube, the electrode is perfectly prevented from the sputtering by accelerated ions. And it is possible to drive the many CCFLs at the same time, because EEFL shows the positively resistant characteristic. But EEFL has the large non-radiative power loss in sheath. In this study the novel electrode structure was introduced in order to reduce non-radiative power loss in sheath of EEFL. The novel electrode structure comes from the idea to combine conceptually capacitive discharge with inductive discharge. Thus, this study verifies the change in the optical characteristics according to the change in electrode structure through a Maxwell's electromagnetic field simulation and examines the relationship between the change in the EEFL electrode structure and brightness by measuring the optical characteristics.

• Journal of Plant Biotechnology
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• v.48 no.4
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• pp.271-277
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• 2021

The present study aimed to assess and compare the quality characteristics and antioxidant activities of apple juice and blueberry juice at hourly intervals over a period of time based on the presence or absence of vacuum blending (0 and 800 hPa) using a household blender. Measurement of the dissolved oxygen content revealed that the removal rates of dissolved oxygen were approximately 83% and 86% in the apple and blueberry juice samples, respectively, after vacuum blending. Moreover, compared with general blending, there was little change in the antioxidant property and degree of browning over time with vacuum blending. Furthermore, hourly assessments revealed that the decrease in the polyphenol and flavonoid contents in the apple and blueberry juice samples was significantly lesser with vacuum blending for 3, 6, and 12 h than with general blending. Assessment of the change in ferric reducing antioxidant power (FRAP) activity over time revealed that the rate of decrease in FRAP activity over time was lower with vacuum blending than with general blending for both juice samples. ABTS and DPPH radical scavenging assays performed to determine the change in free radical scavenging activity revealed inhibitory activity at 0, 3, 6, and 12 h and confirmed that vacuum blending resulted in long-lasting antioxidant activities in both apple and blueberry juice samples. Taken together, the present results confirmed that vacuum blending is associated with superior quality maintenance and antioxidant properties in comparison with general blending.

• Journal of the Korean Society of Safety
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• v.37 no.1
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• pp.12-19
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• 2022

Circuit breakers are a crucial factor in ensuring the safety of a Direct Current (DC) grid. One type of DC circuit breaker, the Z-source DC circuit breaker (ZCB), uses a thyristor, which is a type of semiconductor switch. In the event of a fault in the circuit, the ZCB isolates the fault by generating a zero crossing current in the thyristor. The thyristor quickly and actively isolates the fault while generating a zero crossing current, but thyristor switch cannot control turn-off and the allowable current is lower than the current of the mechanical switch. Therefore, it is best to use a mechanical switch with a high allowable current capacity that is capable of on/off control. Due to the slow reaction time of mechanical switches, they may not isolate the fault during the zero crossing current time interval created by the existing circuit. In this case, the zero crossing current time can be increased by using the property that hinders the rapid change in the current of the inductor. This paper will explore whether adding system inductance to increase the zero crossing current time interval is a solution to this problem. The simulation of changing inductor and capacitor (LC) of the circuit is repeated to find an optimal change in the zero crossing current time according to the LC change and provides an inductor and capacitor range optimized for a specific load. The inductor and capacitor range are expected to provide optimization information in the form LC values for future applications of ZCB's using a mechanical switch.

• Journal of Families and Better Life
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• v.2 no.1
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• pp.35-55
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• 1984

This study aims to present basic data for a reasonable home management through investigating the change of home economy conditions incidental to the family life cycle, also through analyzing the effect of socio-anthropological variables on the family-life cycle. The data investigation using the questionnaires method was conducted on housewives in Seoul as the central census tract. Housewives as the subject of investigation were chosen by the method of the purpose-sampling in consideration of the regional differences and the socio-economical strata. Nine hundred and forty questionnaires were distributed to housewives but seven hundred questionnaires were collected. Only five hundred and ten questionnaires of them were analyzed in this study. The frequency and the percentage of collected data, first of all, were founded in order to grasp the general characteristics of the subject of investigation. To classify the stage of family life cycle, the correlations of the classifying factors among each group were examined x2 Test and One-Way ANOVA were applied to explore the differences among each stage of the change of household-economy. And the effect of socio-anthropological variables on the change of household- economy was analyzed by Two-way ANOVA. the conclusions derived from the results of this study are as follows; 1) The marriage-period and the educational conditions of the first child were selected as the classifying factors through analyzing correlation among the age, the marriage-period and the educational conditions of their children. As a result of this analysis, the family life cycle were classified into seven stages: Stage 1; Establishment Stage 2; Preschool family Stage 3; Elementary school family stage 6; Adult period family Stage7; Marriage period family . 2) The change of household economy incidental to the progress of family life cycle has a significant differences in all of variables (except the other member of family's income) Stage 1; Though the husband's income and the income from property are on a low level, the total income is on a high level due to the housewife's income. Stage 2; The total income is on a low level owing to the decrease of house wife's income, though the husband's income keep growing. Stage 3; Owing to the increase of husband's income, the cost of living as well as the total income keeps growing but the savings are on the decrease. Stage 4; Compared with Stage 3, the total income tends to be on a low level but the living expenses are on the increase. Stage 5; The husband's income is on the highest level in the stages of family life cycle. The total income and the living expenses are on a high level. Stage 6; The income of husband and housewife are on the remarkable decrease but the children's income is on the increase. Stage 7; Owing to the increase of the children's income and the income from property, the total income is on the highest level in the stages of family life cycle. 3) Considering the effect of socio-anthropological variables on the conditions of household-economy, family system has an significant effect on children's income. the husband's occupation exerts a significant effect upon the housewife's and children's income. The husband's schooling exercises an effect upon the children's income. S.E.S has a important effect on the income of husband, housewife and children. From the above results, it is found that the change of household-economy conditions is incidental to the progress of family life cycle. Therefore, a suitable measure to cope with the desire of family and the conditions of household-economy should be prepared, in order to carry on a reasonable home management.