• Journal of Korea Water Resources Association
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• v.51 no.8
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• pp.703-711
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• 2018

Water distribution system (WDS) pipe bursts are caused from excessive pressure, pipe aging, and ground shift from temperature change and earthquake. Prompt detection of and response to the failure event help prevent large-scale service interruption and catastrophic sinkhole generation. To that end, this study proposes a improved Western Electric Company (WECO) method to improve the detection effectiveness and efficiency of the original WECO method. The original WECO method is an univariate Statistical Process Control (SPC) technique used for identifying any non-random patterns in system output data. The improved WECO method multiples a threshold modifier (w) to each threshold of WECO sub-rules in order to control the sensitivity of anomaly detection in a water distribution network of interest. The Austin network was used to demonstrated the proposed method in which normal random and abnormal pipe flow data were generated. The best w value was identified from a sensitivity analysis, and the impact of measurement frequency (dt = 5, 10, 15 min etc.) was also investigated. The proposed method was compared to the original WECO method with respect to detection probability, false alarm rate, and averaged detection time. Finally, this study provides a set of guidelines on the use of the WECO method for real-life WDS pipe burst detection.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.2
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• pp.13-21
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• 2000

Au-black for the application of the long wavelength infrared absorber has been prepared by evaporating Au under nitrogen gas-filled low vacuum condition. Characteristics of the deposited Au-black were carefully investigated through structural analysis, infrared absorbance measurement, and patterning of the layer, all of which are dependent on the deposition condition. High density of micro-cavity that trapped infrared were obtained, and infrared absorbance in the wavelength range from 3 $\mu\textrm{g}$ to 14 $\mu\textrm{g}$ was found to be about 90% when the Au-black layer was produced under the deposition condition of mass Per area of about 600 $\mu\textrm{g}$/cm$^{2}$ and chamber pressure of above 1 Torr. Photoresist lift-off process could be performed to pattern the Au-black, of which mass per area was below 900 $\mu\textrm{g}$/cm/ sup 2/. In view of absorbance, heat capacity, and pattern formation, the deposition condition of chamber pressure of about 1 Tow and mass per area of about 600$\mu\textrm{g}$/cm$^{2}$ was most adequate for preparing the Au-black as an infrared absorber.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.23 no.5
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• pp.255-264
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• 2013

Cobalt aluminate ($CoAl_2O_4$) is a highly stable pigment with excellent resistance to light, weather, etc., which has resulted in widespread use as a ceramic pigment. Due to the unique optical characteristics, $CoAl_2O_4$ is generally used as a coloring agent to decorate porcelain products, glass, paints and plastics. Here, $CoAl_2O_4$ pigments were synthesized by polymerized complex method and solid state reaction. Then $CoAl_2O_4$ pigment were grinded using the attrition milling with 1 mm size zirconia ball for 3 hours. The attrition milling process was performed at the constant speed of 800 rpm and ball to powder weight ratio (BPR) was 100 : 1. The characteristics of synthesized pigment were analyzed by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), particle size analyser (PSA) and CIE $L^*a^*b^*$. The XRD patterns of $CoAl_2O_4$ show single phase spinel structure. The particle size of $CoAl_2O_4$ measured by FE-SEM, TEM and PSA analysis was in the range of 100~200 nm. The blue color of obtained $CoAl_2O_4$ pigments could be confirmed through CIE $L^*a^*b^*$ measurement.

• Journal of the Korea Society of Computer and Information
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• v.12 no.6
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• pp.59-68
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• 2007

The purpose of this paper is to evaluate usability quality through investigating the factors of usability for internet shopping mall websites. For this study, previous studies were investigated and experts' discussions were held. In result, six characters of usability were chosen such as content satisfaction. customer attraction satisfaction, price information satisfaction, public security satisfaction, user interface satisfaction. and process of transaction satisfaction that affect usability of shopping mall websites and the evaluation models of 72 detailed measure factors were established. Since these 72 sub-factors inc)ode the key words of HTML, XML, JSP, and ASP from the target websites. 33 measurable sub-factors in the information were measured through usability evaluation experiment. In addition, a questionnaire about usability measure factors was executed after preferable websites and not preferable websites are selected. After that, we verified the reasonability of usability measure model factors comparing the results of the evaluation experiment with the result of the questionnaire. The time it takes to measure the usability of shopping mall websites can be reduced by using this measurement supporting tool. Also, this tool may be used to estimate the usability during the development of a shopping mall website.

• The Korean Journal of Malacology
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• v.28 no.3
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• pp.215-223
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• 2012

The ecophysiological characteristics of the oyster Crassostrea gigas in Taean area, west coast of Korea, were investigated after main spawning season from September 2011 to January 2012 to confirm the recovery process of condition. The cupped oysters, from 4 different off-bottom culture areas were compared the gonad indices, histological analysis combined with measurement of RNA/DNA contents and ratios in gonad of each sex were undertaken. To evaluate the health condition of oyster after spawning, the RNA/DNA ratio in adductor muscle, fatness and condition index (CI) were used. The results showed that cupped oysters cultured in Uihang coastal area were different physiological aspects than other experiment areas, namely continuously decreasing RNA/DNA content and ratio in adductor muscle, lowest CI and fatness. Oysters cultured in Iwon Station 1 and 2 showed fast recovery in RNA/DNA, increase in fatness and CI during post-spawning stage until October rapidly and there after it decreased. Oysters in Shinduri showed rapidly decrease in fatness and CI until October. On the contrary to this factors, RNA/DNA ratio in adductor muscle increased as like protein until October. Partially spawning season could be observed until December in Shinduri and Iwon Station 1.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.8
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• pp.38-44
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• 2007

This paper describes a 12 bit 80MHz CMOS D/A converter for wireless transceiver. Proposed circuit in the paper employes segmented structure which consists of four stage 3bit thermometer decoders. Proposed D/A converter is manufactured 0.35um CMOS n-well digital standard process and measurement results show a ${\pm}1.36SB/{\pm}0.62LSB$ of INL/DNL and $46pV{\cdot}s$ of glitch energy. SNR and SFDR are measured to be 58.5dB and 64.97dB @ Fs=80MHz and Fin=19MHz with a total power consumption of 99mW. Such results proved that our work has low power consumption, high linearity, low glitch and improved dynamic performance. Therefore, our work can be appled to various high speed and high performance circuits.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.8
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• pp.16-21
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• 2007

CMOS variable gain amplifier (VGA) IC designs for the structure monitoring systems of the telemetries were developed. A three stage cascaded VGA using a differential amplifier and a linear-in-dB controller is presented. A proposed VGA is a modified version of a conventional VGA such that the gain is controlled in a linear-in-dB fashion through the current ratio. The proposed VGA circuit introduced in this paper has a dynamic range of 77 dB with 1.5 dB gain steps. It also achieved a gain error of less than 1.5 dB over 77 dB gain range. The VGA can operate up to 10MHz dissipating 13.8 mW from a single 1.8 V supply. The core area of the VGA fabricated in a Magnachip $0.18{\mu}m$ standard CMOS process was about $430{\mu}m{\times}350{\mu}m$. According to measurement results, we can verify that the proposed method is reasonable with regard to the enhancement of dynamic range and the better linear-in-dB characteristics.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.293-296
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• 2008

The member deflection is one of the most important considerations for the serviceability evaluation of reinforced concrete (RC) structures, and the concept of the effective moment of inertia has been generally used for its estimation. However, the actual service load applied on an existing RC beam may not be easily obtained, for which the estimation of beam deflection by existing methods can be difficult work. Therefore, based on the close relationships between cracks and deflection in a RC beam, this study proposed a method to estimate the deflection of RC beams directly from the condition of cracks not using the actual loads acting on the member as its input data. The proposed method extensively utilized the relationships among sums of crack widths, average strains, and curvatures, and modification factors obtained from regression analysis were also introduced to improve its accuracy. The deflections of members were successfully estimated by the proposed method independent from applied loads, which was also easy to apply compared to the existing methods based on the effective moment of inertia. This new method, however, has limitations in its applicability in that it is less accurate than the existing methods because the magnitude of acting load is not involved in the estimation process of member deflection, and that it requires the measurement of crack widths along the whole length of a member.

• The Journal of the Korean dental association
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• v.54 no.7
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• pp.521-528
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• 2016

Purpose: The aim of this study was to evaluate the erosive potential of several fruit-flavored liquors marketed in Korea by measuring pH, titratable acidity, and variations in pH utilizing an ISO method. Materials and Methods: Six fruit-flavored liquors were investigated. An orange juice and three kinds of soju were selected as the control beverage. The pH and titratable acidity of the beverages were determined by 1 M NaOH until the pH 5.5 and 7.0 (recorded as $TA_{5.5}$ and $TA_{7.0}$, respectively). All measurements were performed in triplicate. The process of ISO 28888 was used for measurement of the pH variation (${\Delta}pH$) using an under-saturated hydroxyapatite solution (screening solution) and determining the difference between the initial and final pH of the screening solution. The average ${\Delta}pH$ was determined based on 4 measurements. Results: All the fruit-flavored liquors tested in this study showed a pH lower than the critical pH for dental erosion (4.5). The average pH of the fruit-flavored liquors was 2.77 and was also lower than the pH of the soju and an orange juice (control drinks). $TA_{5.5}$ and $TA_{7.0}$ values of the fruit-flavored liquors were 4.92ml and 7.13ml, respectively. The fruit-flavored liquors showed an erosive potential capable of damaging the enamel surfaces, whereas the orange juice had the highest titratable acidity. The changes in pH determined using the screening solution confirmed that the fruit-flavored liquors had erosive potential, with ${\Delta}pH$ value of 1.53. Conclusions: The fruit-flavored liquors tested in this study might have a strong potential to erode dental hard tissues.

• 한국초등상담교육학회:학술대회논문집
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• 2004.01a
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• pp.205-222
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• 2004

Fundamental direction of the seventh education curriculum aims to nurture active and creative Koreans for globalized and information-oriented society of 21 century, and emphasizes the importance of career education identifying its subsections that are practices of student-focused education of aptitude, ability and career. Hence, as a clear targeting of career objective from elementary school through relevant career education enables them to recognize appropriate career for themselves, the basis of self- actualization and social contribution must be settled. This paper seeks to identify the relationship between career awareness and self-esteem by examining and analysing differences of sex, region and level. This study selected 536 samples from 4th and 6th year elementary school students in C city and S town of Chungcheong province. Career awareness test and self-esteem test is used as a measurement, statistical process control (SPC) of career awareness and self-esteem (M, SD, r) is made for each variable, and the significance was tested. The result of this research can be summarized as follows: First, generally there is very significant regional differences of career awareness (F=16.817, p<.001), which contains that urban children has higher career awareness (M=120.22) than that of rural children (M=113.87). In subsections of career awareness, self-esteem of urban children is higher than that of rural children, and the attitude & for career and values of girls is higher than that of boys. In terms of the career planning, urban children and 6th year students are higher than rural children and 4th year students. Second, self-esteem generally has very significant regional difference (F=12.123, p<.01), which contains that the self-esteem of urban children (M=106.50) is higher than that of rural children (M=101.80). In comparison of different forms, a very significant difference is as much as p<.01 level (F=11.046), which contains 4th year students (M=105.63) have higher self-esteem than 6th year students (M=102.05). In subsections of self-esteem, gross self-esteem and social self-esteem of urban children are higher than rural children. In terms of family self-esteem, urban children and 4th year students have higher figure than rural children and 6th year students. In school self-esteem, 4th year students had higher level than the 6th. Third, the career awareness and self-esteem are generally related as r= .50, it was very significant at p<. 001 level. All subsections of career awareness had positive relationships except the school self-esteem. According to the result, rural children had relatively low career awareness and self-esteem. This is presumably due to relatively poor circumstances for rural children, comparing to that of urban children. Therefore rural elementary schools should try to let them have appropriate career awareness by associating with family, school and local society to expand the opportunity of experiences for the self perception of aptitude, nature and interest. In addition, we have to strive for the whole-minded education increasing the self-esteem of rural children and giving them positive thinking through career counselling, personal counselling and group counselling.