• Nuclear Engineering and Technology
• /
• v.44 no.5
• /
• pp.551-560
• /
• 2012

The Wolsong-1 (W-1) Phase-B pre-simulations were carried out in preparation for tests to be conducted for the restart of the reactor after a major refurbishment project that included replacement of the pressure tube. These pre-simulations for Wolsong-1 Phase-B differ from those in the past that were performed for the Wolsong-1,2,3,4 tests in that these tests use the WIMS/DRAGON/RFSP-IST code suite for verification of the tests and gadolinium instead of the traditional PPV/MULTICELL/RFSP code system and boron as poison in the moderator system. The use of gadolinium is deemed not to have domestically accumulated experience gained from the previous Phase-B tests. Thus, it is appropriate to conduct a study in order to gain a correct understanding and interpretation of potential differences in test results stemming from using gadolinium rather than boron. Although the calibration of the reactivity device will not be noticeably different using boron and gadolinium at a constant moderator temperature, the temperature dependency of the neutronic behavior due to the presence of gadolinium in the moderator system might be pronounced. The results of the pre-simulations using gadolinium revealed that the moderator temperature reactivity coefficients indeed showed significant differences in comparison with those with boron. In order to secure the validity of the analysis results, the newly acquired WIMS/DRAGON/RFSP-IST code suite was verified against the W-2,3,4 Phase-B test results. The results of the new code suite verifications revealed some overall improvements in accuracy; justification of the use of the code can be claimed for the validation of the W-1 Phase-B test results.

• Journal of Sensor Science and Technology
• /
• v.25 no.1
• /
• pp.57-64
• /
• 2016

To understand a two-phase flow, a liquid film thickness is one of the important factors. A lot of researches have been performed to measure liquid film thickness with various approaches. Recently, an electrical conductance method which uses the conductivity of the liquid film has been widely applied on measuring the liquid film thickness. Though the electrical method has an advantage in high spatial resolution, as the conductivity of liquid can be affected by its temperature variation, the conventional electrical conductance methods have a limitation in being applied on varying temperature conditions where a heat transfer is involved. The purpose of this study is to develop a three-ring liquid film sensor that overcomes the limitation of the conventional method. The three-ring conductance method can measure the film thickness regardless of temperature variation by compensating the change of liquid conductivity. Considering its application on a wide range of conditions such as high temperature or curved surfaces, the sensor was fabricated on flexible printed circuit board (FPCB) in this study. This paper presents the concept of the measurement method, design procedure, prototype sensor fabrication and calibration results.

• Economic and Environmental Geology
• /
• v.39 no.5 s.180
• /
• pp.525-535
• /
• 2006

A study on stream-groundwater exchange was performed using head and temperature data of stream water, streambed, and groundwater. Groundwater level and temperature were obtained from multi-depth monitoring wells in small-scale watershed. During the summer and winter season, time series of temperature data at streambed and groundwater were monitored for six months. In the winter time, we measured the temperature gradient between stream water and streambed. The observed data showed three typical types of temperature characteristics. First, the temperature of streambed was lower than that of stream water; second, the temperature of streambed and stream water was similar; and the last, the temperature of streambed was higher than that of stream water. The interconnections between the stream and the streambed were not homogeneously distributed due to weakly developed sediments and heterogeneous bedrock exposed as bed of the stream. The temperature data may be used in formal solutions of the inverse problems to estimate groundwater flow and hydraulic conductivity.

• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.40 no.3
• /
• pp.135-144
• /
• 2003

This work proposes on-chip full CMOS current and voltage references for high-speed mixed-mode circuits. The proposed current reference circuit uses a digital-domain calibration method instead of a conventional analog calibration to obtain accurate current values. The proposed voltage reference employs internal reference voltage drivers to minimize the high-frequency noise from the output stages of high-speed mixed-mode circuits. The reference voltage drivers adopt low power op amps and small- sized on-chip capacitors for low power consumption and small chip area. The proposed references are designed, laid out, and fabricated in a 0.18 um n-well CMOS process and the active chip area is 250 um x 200 um. The measured results show the reference circuits have the power supply variation of 2.59 %/V and the temperature coefficient of 48 ppm/$^{\circ}C$ E.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.20 no.8
• /
• pp.730-738
• /
• 2009

In this paper, we present a equivalent circuit considered parasitic elements about LTCC multi-layer BPF structure that was studied previously and a process of extraction of the element value using SOC technique. By applying extracted element values to equivalent circuit, 2th LTCC filter was designed and fabricated that was applied to satellite DMB. The filter was fabricated of Dupont951 substrate with relative permittivity of 7.8, the dimension of the fabricated filter is $2.4{\times}3.8{\times}0.378mm^3$. The measurement results indicate 1.4 dB of insertion loss and 32.3 dB of return loss, which are in good agreement with simulated ones.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
• /
• 2001.06a
• /
• pp.1156-1156
• /
• 2001

This work aimed to prove the feasibility of NIR spectroscopy to detect vegetable protein isolates (soy, pea and wheat) in milk powder. Two hundred and thirty-nine samples of genuine and adulterated milk powder (NIZO, Ede, NL) were analysed by NIRS using an InfraAlyzer 500 (Bran+Luebbe). NIR spectra were collected at room temperature, and data were processed by using Sesame Software (Bran+Luebbe). Separated calibrations for each non-milk protein added, in the range of 0-5%, were calculated. NIR data were processed by using Sesame Software (Bran+Luebbe). Prediction and validation were made by using a set of samples not included into the calibration set. The best calibrations were obtained by the PLSR. The type of data pre-treatment (normalisation, 1$\^$st/ derivative, etc..) was chosen to optimize the calibration parameters. NIRS technique was able to predict with good accuracy the percentage of each vegetable protein added to milk powder (soy: R$^2$ 0.994, SEE 0.193, SEcv 0.301, RMSEPall 0.148; pea: R$^2$ 0.997, SEE 0.1498, SEcv 0.207, RMSEPall 0.148, wheat: R$^2$ 0.997, SEE 0.1418, SEcv 0.335, RMSEPall 0.149). Prediction results were compared to those obtained using other two techniques: capillary electrophoresis and competitive ELISA. On the basis of the known true values of non-vegetable protein contents, the NIRS was able to determine more accurately than the other two techniques the percentage of adulteration in the analysed samples.

• Journal of Korean Society on Water Environment
• /
• v.25 no.1
• /
• pp.7-17
• /
• 2009

Soil and Water Assessment Tool (SWAT) was used to assess the impact of potential future climate change on the water cycle and soil loss of the Daecheong reservoir watershed. A sensitivity analysis using influence coefficient method was conducted for two selected hydrological input parameters and three selected sediment input parameters to identify the most to the least sensitive parameters. A further detailed sensitivity analysis was performed for the parameters: Manning coefficient for channel (Cn), evaporation (ESCO), and sediment concentration in lateral (LAT_SED), support practice factor (USLA_P). Calibration and verification of SWAT were performed on monthly basis for 1993~2006 and 1977~1991, respectively. The model efficiency index (EI) and coefficient of determination ($R^2$) computed for the monthly comparisons of runoffs were 0.78 and 0.76 for the calibration period, and 0.58 and 0.65 for the verification period. The results showed that the hydrological cycle in the watershed is very sensitive to climate factors. A doubling of atmospheric $CO_2$ concentrations was predicted to result in an average annual flow increase of 27.9% and annual sediment yield increase of 23.3%. Essentially linear impacts were predicted between two precipitation change scenarios of -20, and 20%, which resulted in average annual flow and sediment yield changes at Okcheon of -53.8%, 63.0% and -55.3%, 65.8%, respectively. An average annual flow increase of 46.3% and annual sediment yield increase of 36.4% was estimated for a constant humidity increase 5%. An average annual flow decrease of 9.6% and annual sediment yield increase of 216.4% was estimated for a constant temperature increase $4^{\circ}C$.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.12 no.6
• /
• pp.279-283
• /
• 2012

In is paper, we design and implement the low power, high speed touch screen controller that calculates and outputs the coordinate of touch point on the touch screen of mobile devices. The system clock is 10HMz, the number of input channels is 21, standby current is $20{\mu}A$, dynamic range of input is 140pF~400pF and the response time is 0.1ms/frame. It contains the power management unit for low power, automatic impedance calibration unit in order to adapt to humidity, temperature and evaluation board, adjacent key and pattern interference suppression unit, serial interface unit of I2C and SPI. The function and performance is verified by using FPGA and $0.18{\mu}m$ CMOS standard process. The implemented touch screen is designed for using in the double layer ITO(Indium Thin Oxide) module with diamond pattern and single layer ITO module for cost-effective which are applied to mobile phone or smart remote controller.

• KSBB Journal
• /
• v.11 no.1
• /
• pp.86-91
• /
• 1996

Optimal reaction condition for the starch hydrolysis by ${\alpha}$-amylase was determined and the sugar produced under the optimal condition was measured for estimating the biodegradation of strach-filled polyethylene film. Optimal ranges of temperature and pH were 70~$80^{\circ}C$ and 6.3~7.3, respectively. The 100 units of ${\alpha}$-amylase per mg starch were enough for the enzyme reaction. Reaction with polyethylene film containing 5%, 10%, 15% and 20% starch in the above condition showed that the sugar produced was proportional to the starch content in film. This relationship provides a calibration curve for determining the starch content of search-filled polyethylene film. The average amount of hydrolyzed starch was about 40% of total starch in film. The rest of the starch is considered to be still dispersed in the film and not to be attacked by ${\alpha}$-amylase. In this experiment, we could obtain the higher biodegradability through the $\alpha$-amylase reaction in the above optimal condition than the reported one which had been Improved by adding surfactant.

• International Journal of Highway Engineering
• /
• v.10 no.4
• /
• pp.79-89
• /
• 2008

The pavement performance model is the most important factor to determine the pavement life in the mechanistic-empirical pavement design guide (MEPDG). As part of Korean Pavement Research Program (KPRP), the Korean Pavement Design Guide (KPDG) is currently being developed based on mechanistic-empirical principle. In this paper, the rutting prediction model of asphalt mixtures, one of the pavement performance model, has been developed using triaxial repeated loading testing data. This test was conducted on various types of asphalt mixtures for investigating the rutting characteristics by varying with the temperature and air void. The calibration process was made for the coefficients of rutting prediction model using the accelerated pavement testing data. The accuracy of prediction model can be increased when by considering the effect of individual rutting properties of materials rather than shear stresses with depths.