• Journal of the Korean Institute of Telematics and Electronics
• /
• v.26 no.5
• /
• pp.52-59
• /
• 1989

The reliability of the thin thermal oxide was investigated by using constant current stress method. Polysilicon gate MOS capacitors with oxide thickness range of 20-25nm were used in this experiment. Automatic measurement and statistical data analysis which were essential in reliability evaluation of VLSI process preformed by HP 9000 computer. Based on TDDB results, defect density, breakdown charge (Qbd) and lifetime of oxide film were evaluated. According to the polarity of the stress, some different characteristics were shown. Defect density was 62/$cm^2$ at negative gate injection. The value of Qbd was about 30C/$cm^2$ at positive gate injection, and about 21C/$cm^2$ at negative. The current density acceleration factor was 1.43$cm^2$/A for negative gate injection, and 1.25$cm^2$/A for positive gate injection.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.15 no.2
• /
• pp.273-278
• /
• 2015

In order to meet increasing power demands, electrical capacity of equipment for power transfers should become larger accordingly. The equipment used for producing and delivering high-voltage power is also required to operate with a high degree of reliability. The stable operation of power equipment is a necessity, not an option. The current through the power cable, the only device to deliver high power, generates a Joule heat, which causes a deteriorating process on the cable system. The XLPE cable is manufactured in such a manner that it can operate for 30 years at $90^{\circ}$, but there is no guarantee that each cable will reach its projected lifetime of 30 years. In this paper, we have measured the temperatures of nine power cables in operation, based on the theory of cable longevity. In order to study the relationship between temperature and longevity, we have devised a new set of equipment and installed it at Korea Western Power Co., Ltd. located in Taean.

• Journal of Korean Society of Steel Construction
• /
• v.18 no.5
• /
• pp.585-596
• /
• 2006

This study focuses on the seismic behavior of 3-, 9-, and 20-story steel moment resisting frame (MRF) structures designed in accordance with the 2000 International Building Code using different Response Modification factors (R factors), i.e., 8, 9, 10, 11, and 12. For a detailed case study, 30 different structures were evaluated for 20 ground motions representing the hazard level, which is equal to a 2% probability in 50 years (2% in 50 years). The results showed that the current R factors provide conservative designs for the 3- and 9-story buildings for the Collapse Prevention performance objective. the 20-story buildings, which were designed without using the minimum requirement of spectral acceleration CS prescribed in IBC 2000, did not satisfy the seismic performance for Collapse Prevention performance.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.29 no.6
• /
• pp.270-275
• /
• 2019

Mica capacitor is being adopted for high voltage firing unit of guided weapon system because of its superior impact enduring property relative to ceramic capacitor. Reliability of localized mica high voltage capacitors was verified through environmental test like terminal strength test, humidity test, thermal shock test and accelerated life test for application to high voltage firing unit. Failure mode of mica capacitor is a decrease of insulation resistance and its final dielectric breakdown. Main constants of accelerated life model were derived experimentally and voltage constant and activation energy were 5.28 and 0.805 eV respectively. Lifetime of mica capacitor at normal use condition was calculated to be 38.5 years by acceleration factor, 496, and lifetime at accelerated condition and this long lifetime confirmed that mica high voltage capacitor could be applied for firing unit.

• Journal of the Korean GEO-environmental Society
• /
• v.15 no.9
• /
• pp.29-36
• /
• 2014

Under the situation that the seismic vulnerability are a worsening problem in many world's megacities, the disaster preparedness including earthquake hazards is a matter of primary concern in the capital city of Korea, Seoul. Especially, because it is hard to move or dismantle the architectural heritages, the mitigation of earthquake damages is potentially more difficult than other structures. Moreover, in order to decide the proper preparedness plan against future earthquakes, it is very important to understand how soils pass the seismic waves to architectural heritages. In this paper, therefore, the ground condition and depth of bedrock was investigated by the MASW-method at heritages located in Seoul. Then one-dimensional seismic response analysis was conducted based on the distribution of shear wave velocity. As the major result of analyses, peak acceleration, site amplification factor and natural period are proposed in each site for recurrence period.

• Journal of the Korean Geosynthetics Society
• /
• v.11 no.1
• /
• pp.47-56
• /
• 2012

Discharge capacity of PBD is sensitive in proportion to thickness and ground condition, and drainage of PBD declines due to disturbance effect in surrounding ground by mandrel used for vertical drainage setting and setting machines and type. Also, deviation of discharge capacity gets larger according to ground condition, construction condition and soil properties. But cause and analysis of those problems like reduced discharge of capacity and delayed dissipation of pore water pressure for discharge capacity is lack. Thus, in this text, ground improvement and discharge capacity is investigated by implementing composite discharge capacity test for analysis of an effect factor of PBD discharge capacity with in-situ ground condition. After fixing the vertical drain on a cylindrical cylinder, put churned sample into the cylinder. After in-situ ground and reclamation of ground are dredged, load following the loading step of 30, 70 and 120kPa using a pressure device. Result of the test, The discharge capacity was SM>ML>CL>CL(dredged soil) in situ condition and more fine-grained content, the amount of discharge was greater.

• Earthquakes and Structures
• /
• v.18 no.1
• /
• pp.27-44
• /
• 2020

This work presents a comparison of three performance-based seismic design methods (PBSD) as applied to plane steel frames having eccentric braces (EBFs) and buckling restrained braces (BRBFs). The first method uses equivalent modal damping ratios (ξ_k), referring to an equivalent multi-degree-of-freedom (MDOF) linear system, which retains the mass, the elastic stiffness and responds in the same way as the original non-linear MDOF system. The second method employs modal strength reduction factors (${\bar{q}}_k$) resulting from the corresponding modal damping ratios. Contrary to the behavior factors of code based design methods, both ξ_k and ${\bar{q}}_k$ account for the first few modes of significance and incorporate target deformation metrics like inter-storey drift ratio (IDR) and local ductility as well as structural characteristics like structural natural period, and soil types. Explicit empirical expressions of ξ_k and ${\bar{q}}_k$, recently presented by the present authors elsewhere, are also provided here for reasons of completeness and easy reference. The third method, developed here by the authors, is based on a hybrid force/displacement (HFD) seismic design scheme, since it combines the force-base design (FBD) method with the displacement-based design (DBD) method. According to this method, seismic design is accomplished by using a behavior factor (q_h), empirically expressed in terms of the global ductility of the frame, which takes into account both non-structural and structural deformation metrics. These expressions for q_h are obtained through extensive parametric studies involving non-linear dynamic analysis (NLDA) of 98 frames, subjected to 100 far-fault ground motions that correspond to four soil types of Eurocode 8. Furthermore, these factors can be used in conjunction with an elastic acceleration design spectrum for seismic design purposes. Finally, a comparison among the above three seismic design methods and the Eurocode 8 method is conducted with the aid of non-linear dynamic analyses via representative numerical examples, involving plane steel EBFs and BRBFs.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.32 no.7
• /
• pp.1137-1148
• /
• 2008

The purposes of this study were to investigate the differences in clothing consumption behaviors among female consumer groups in their twenties and to understand the type of consumer group pursuing fast fashion. Questionnaire survey was conducted to 230 female consumers residing in Seoul and Kyung Gi area from June 18 to 29 in 2007, and 178 were used for data analysis. Data analysis were conducted with SPSS 12 program on the reliability test, factor analysis, cluster analysis, correlation analysis, ANOVA, Duncan's multiple range test. Factors analyses were employed for the attitude toward fashion and shopping, and shopping motives. Four factors were formulated for the attitude toward fashion: interest in fashion, fashion-orientation, fashion leadership and fashion conformity. Six factors for the attitude toward shopping were found: information searching, shopping enjoyment, store patronage, impulse buying, brand-orientation and convenience. Buying motives for fashion goods were classified into 3 factors: for matching & occasion, to-be-in-fashion and for necessity. Four clusters were identified based on the attitude toward fashion: the fashion-interested, the fashion-indifferent, fashion leaders and the individuality-oriented. Among the groups, significant differences were found in information searching, shopping enjoyment and store patronage. Fashion leaders tended to spend more for expensive and up-to-dated fashion items, and for higher quantity than other groups. Consequently fashion leaders showed attractive customer characteristics for the fast fashion companies.

• 한국신재생에너지학회:학술대회논문집
• /
• 2011.11a
• /
• pp.104-104
• /
• 2011

The fuel economy estimates essentially serve two purposes : to provide consumers with a basis on which to compare the fuel economy of different vehicles, and to provide consumers with a reasonable estimate of the range of fuel economy they can expect to achieve. The current fuel economy label values utilize measured fuel economy over city driving cycles. However, this test driving mode can not be evaluated the variety factor of the real-world. These factors include differences between the way vehicles are driven on the road and over the test cycles, air conditioning use, widely varying ambient temperature and humidity, widely varying trip lengths, wind, precipitation, rough road conditions, hills, etc. The purpose of this paper is to account for three of these factors on the fuel economy : 1) on-road driving patterns (i.e. higher speeds and more aggressive driving (higher acceleration rates)), 2) air conditioning, and 3) colder temperatures. The new test methods will bring into the fuel economy estimates the test results from the five emissions tests in place today : CVS-75, HWFET, US06, SC03 and Cold CVS-75. Based on these new test methods, this paper discusses the characteristics of driving condition on Hybrid electric vehicle (HEV). And this paper assesses the fuel economy label of HEV.

• Journal of Ginseng Research
• /
• v.28 no.3
• /
• pp.143-148
• /
• 2004

Brown color intensity has been a major factor to estimate the quality of red ginseng and its products. This study deals with the relationship between the browning reaction of ginseng root and two compounds, arginyl-fructosyl-glucose(Arg-fru-glc) and arginyl-fructose (Arg-fru), in the model system of steaming and heat-drying processes for the preparation of red ginseng. During the steaming process, a marked decrease of starch and a considerable formation of maltose occurred in main roots of raw ginseng, but the formation of glucose was scarcely observed. After the heat-drying process, the brown color intensity of the powdered preparation of steamed main roots was 3 to 4 times higher than that of the powdered preparation of raw main roots. Also, when the heat- drying process was done with the addition of L-arginine, brown color intensity of the powdered preparation of steamed main roots was 12 to 13 times higher than that of the powdered preparation of raw main roots. The amount ratios of browning reaction products formed from sugar compounds and amino acids in the model system of steaming and heat-drying treatments in vitro were in order of xylose > glucose > fructose > maltose > dextrin (DE 9) > sucrose > dextrin (DE 8) and soluble starch. Each solution of Arg-fru-glc and Arg-fru that were synthesized chemically from maltose plus L-arginine and glucose plus L-arginine, respectively, changed from colorless to brown color during the heat-drying treatment. Amino acids or sugars were effective on the acceleration of each browning reaction of Arg-fru-gIc and Arg-fru during the heat-drying treatment.