• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.365-365
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• 2008

In this work, Ga-doped ZnO (GZO) thin films for NOx gas sensor application were deposited on low temperature co-fired ceramics (LTCC) substrates, by RF magnetron sputtering method. The LTCC substrate is one of promising materials for this application since it has many advantages (e.g., low cost production, high manufacturing yields and easy realizing 3D structure etc.). The LTCC substrates with thickness of 400 pm were fabricated by laminating 12 green tapes which consist of alumina and glass particle in an organic binder. The structural properties of the fabricated GZO thin films with different thickness are analyzed by X-ray diffraction method (XRD) and field emission scanning electron microscope (FESEM). The GZO gas sensors are tested by gas measurement system under varing operation temperature and show good performance to the NOx gas in sensitivity and response time.

• Design & Manufacturing
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• 제13권1호
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• pp.19-24
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• 2019

Currently, the world is paying keen attention to the production of renewable energy along with environmental issues, and the share of renewable energy in the world is rising above that of nuclear power. Especially when Korea, which is heavily dependent on foreign countries, needs to reconsider its national competitiveness due to the recent high oil prices, the government's energy policy is to develop and use renewable energy that replaces fossil fuels. In particular, solar energy, the most actively studied and commercialized field of renewable energy, is the main research for solar energy and is commercialized and used. However, the efficiency of solar energy has already reached saturation. Studies are also focusing on increasing the reflectivity of solar energy to increase efficiency. Therefore, this paper proposes a solar collection system that can utilize solar energy rather than solar energy. The proposed solar heat collection system uses solar tracking systems to effectively collect solar energy, particularly those that can be easily produced using single-modular reflectors and have price competitiveness. In addition, temperature measurement experiments with temperature measuring sensors were conducted to ensure reliability in order to verify the results interpreted.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• 제32권5호
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• pp.413-417
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• 2019

In this study, the volume resistivity of XLPE materials with various voltage ratings was discussed. The volume resistivity of the developed XPLE nanocomposite was measured, and the conductivity mechanism of the material was also examined. The ASTM D 257 and IEC 60093 measurement methods were used for these tests. The equipment was designed to measure up to a temperature of $200^{\circ}C$, and the electrode structure was designed to maintain the thickness and temperature uniformity of the sample. The conductivity of the sample decreased with temperature, and the samples reached saturation within 500s, after which the conductivity leveled off. By analyzing the current density and the electric field, we can well explain the electric conductivity behavior of our sample with the Schottky mechanism.

• International Journal of Computer Science & Network Security
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• 제22권9호
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• pp.403-413
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• 2022

Classification and analysis are improved factors for the realtime automation system. In the field of agriculture, the cultivation of different paddy crop depends on the atmosphere and the soil nature. We need to analyze the moisture level in the area to predict the type of paddy that can be cultivated. For this process, Ensemble Modulation Pattern system and Block Probability Neural Network based classification models are used to analyze the moisture and temperature of land area. The dataset consists of the collections of moisture and temperature at various data samples for a land. The Ensemble Modulation Pattern based feature analysis method, the extract of the moisture and temperature in various day patterns are analyzed and framed as the pattern for given dataset. Then from that, an improved neural network architecture based on the block probability analysis are used to classify the data pattern to predict the class of paddy crop according to the features of dataset. From that classification result, the measurement of data represents the type of paddy according to the weather condition and other features. This type of classification model assists where to plant the crop and also prevents the damage to crop due to the excess of water or excess of temperature. The result analysis presents the comparison result of proposed work with the other state-of-art methods of data classification.

• Proceedings of the KIEE Conference
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 전기설비
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• pp.76-78
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• 2005

Moisture contents measurement is frequently used as one of parameters for degradation diagnosis of transformer insulation. In general Karl-Fisher method is mainly used for moisture contents till now. But this method is inconvenient because of dismounting transformer for sampling oil or paper, and also partial sampling. At latest Recovery Voltage Method(RVM) is noticed for complement of this method. RVM can directly estimate moisture contents of transformer insulations in field without dismounting transformer. In this paper the accelerated aging process of oil-paper samples have been investigated at a temperature up to 140$^{\circ}C$ for 500 hours. The oil-paper insulation samples have been measured at intervals of 100 hours. Next to, we have estimated moisture contents using both Karl-Fisher Titration Method and RVM. And we have compared with Karl-Fisher Titration Method and RVM for estimating moisture contents. At last we have verified reliability of RVM which is new measurement method.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 1999년도 유체기계 연구개발 발표회 논문집
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• pp.90-96
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• 1999

In contracts for sales of natural gas between sellers and buyers, it is not suncient to only measure a volumetric quantity of gas in flowing conditions in metering station. Therefore the measured volumetric quantity must be converted to that of reference conditions. The density of the natural gas required in such a calculation can be measured directly or estimated from the equation of sate or any other experimental methods. The specific gravity meter is the apparatus used to measure the density of fluids under the reference conditions and it can be widely used in industrial areas, especially in massive flow rate natural gas industry. This study has been carried out in an attempt to improve measurement accuracy of natural gas flow rate calculation, providing the adequate installation and proper operation conditions of specific gravity meter. The test results are 1) the density measurement errors in case of using methane and standard gas as calibration gases are smaller than using methane and nitrogen gas, 2) the periodical calibration to maintain accurate density measurements is essential, and 3) the specific gravity meter is sensitive to changes of environmental conditions, especially environmental temperature surrounding the specific gravity meter.

• Journal of the Korean Solar Energy Society
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• 제31권3호
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• pp.8-16
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• 2011

The objective of this study is to analyze the characteristic of thermal environment in the summer season by conducting the field observation of temperature, relative humidity, and globe temperature in some parts of the city. Observation point was divided to a densely populated area, a residential area, a green area, a waterfront green area and a suburban district by the distribution ratio of green area. In this study, the correlation between maximum temperature and globe temperature, study on index for intensity of the tropical night and the temperature distribution characteristic of measurement points by the distribution ratio of green area were analyzed. The results of this study are as follows. (1) The difference between temperature and globe temperature by the distribution ratio of green area is confirmed. The difference of nighttime is more clearly that of daytime. (2) The average temperature and globe temperature of the densely populated area($29.2^{\circ}C$, $33.7^{\circ}C$) are higher than that of the waterfront green area($27.9^{\circ}C$, $32.0^{\circ}C$) by $1.3^{\circ}C$ and $1.7^{\circ}C$, respectively. (3) The number of tropical nights has different days of tropical nights by the distribution ratio of green area of 17days for the Daegu weather station, 14days for adensely populated area, 14days for a residential area, 6days for a green area, 2days for a waterfront green area, and 2days for a suburban district. (4) The results of the slope of trend line for the effects of the temperature on globe temperature change and the intercept for the size of the impact of radiant energy gained around by the analysis of the correlation between the maximum temperature and globe temperature can be utilized objective evaluation index of the each point's artificial effects.

• Electrical & Electronic Materials
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• 제9권3호
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• pp.251-258
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• 1996

Sol-Gel derived ferroelectric Pb(Z $r_{0.52}$ $Ti_{0.48}$) $O_{3}$ thin films have been fabricated on Pt/Ti/ $SiO_{2}$/Si substrate. Two kinds of fast annealing methods, F-I (six times of intermediate and final annealing) and F-II(one final annealing after six times of intermediate annealing) were used for preparation of multi-coated PZT thin films. As the annealing temperature was increased, high capacitance could be obtained, for instance, 2700.angs.-thick PZT thin film annealed at 680.deg. C had a capacitance value of approximately 20nF at 1kHz. In addition, it is found that the dielectric constant is a function of the perovskite phase fraction. In case of F-I method, PZT thin film had a remanent polarization(Pr) of 8-15.mu.C/c $m^{2}$ and a coercive field( $E_{c}$) of 35-44kV/cm according to annealing temperature, whereas PZT film fabricated by F-II method had as high as 24-25.mu.C/c $m^{2}$ and 48-59kV/cm, respectively. As a result of measuring Curie temperature, PZT thin film had a range of 460-480.deg. C by F-I method and more or less higher range of 525-530.deg. C by F-II method, which implied that different microstructures could cause the different Curie temperature. Through I-V measurement, leakage current of PZT thin film fabricated by F-I and F-II methods was 64nA/c $m^{2}$ and 2.2.mu.A/c $m^{2}$ in the electric field of 100kV/cm, respectively.y.y.y.

• Journal of Radiation Protection and Research
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• 제32권1호
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• pp.27-34
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• 2007

In this paper, We are evaluated about bio-signal between general workers and nuclear medicine workers which is more radiation exposure relatively. In order to reciprocal evaluated two group, we experimented nuclear medicine workers in Chung-Buk National University Hospital at department of nuclear medicine and worker in Chon-Nam National University Hospital at CT room, general radiographic room, medical recording room, receipt room, general office room. Used of experimental Equipments as follows, for a level of radiation measurement by pocket dosimeter which made by Arrow-Tech company, for heart rate and blood pressure measurement by TONOPORT V which made by GE medical systems company, for heat flux and skin temperature and energy expenditure measurement by Armband senseware 2000 which made by Bodymedia company. Result of experiment obtains as follows: 1) Individual radiation exposure is recorded 3.05 uSv at department of nuclear medicine and order as follows CT room, general radiograpic room, medical recording room, receipt room, general office room. Department of nuclear medicine more 1.5 times than other places. 2) Radiation accumulated dose is not related to Heat flux, Skin temperature, Energy expenditure. 3) Blood pressure is recorded equal to nuclear medical workers, general officer, general people about systolic blood pressure and diastolic blood pressure. Compared to blood pressure between nuclear medical works which is more radiation exposure and other workers was not changed. Consequently, more radiation exposed workers at nuclear medicine field doesn't have hazard.

• Journal of Korean Society for Atmospheric Environment
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• 제27권3호
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• pp.313-325
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• 2011

From October 2009 to June 2010, major greenhouse gases (GHG: $N_2O$, $CH_4$, $CO_2$) soil emission were measured from upland cabbage field at Kunsan ($35^{\circ}$56'23"N, $126^{\circ}$43'14"E), Korea by using closed static chamber method. The measurements were conducted mostly from 10:00 to 18:00LST during field experiment days (total 28 days). After analyzing GHG concentrations inside of flux chamber by using a GC equipped with a methanizer (Varian CP3800), the GHG fluxes were calculated from a linear regression of the changes in the concentrations with time. Soil parameters (e.g. soil moisture, temperature, pH, organic C, soil N) were also measured at the sampling site. The average soil pH and soil moisture were ~pH $5.42{\pm}0.03$ and $70.0{\pm}1.8$ %WFPS (water filled pore space), respectively. The ranges of GHG flux during the experimental period were $0.08\sim8.40\;mg/m^2{\cdot}hr$ for $N_2O$, $-92.96\sim139.38mg/m^2{\cdot}hr$ for $CO_2$, and $-0.09\sim0.05mg/m^2{\cdot}hr$ for $CH_4$, respectively. It revealed that monthly means of $CO_2$ and $CH_4$ flux during October (fall) were positive and significantly higher than those (negative value) during January (winter) when subsoil have low temperature and relatively high moisture due to snow during the winter measurement period. Soil mean temperature and moisture during these months were $17.5{\pm}1.2^{\circ}C$, $45.7{\pm}8.2$%WFPS for October; and $1.4{\pm}1.3^{\circ}C$, $89.9{\pm}8.8$ %WFPS for January. It may indicate that soil temperature and moisture have significant role in determining whether the $CO_2$ and $CH_4$ emission or uptake take place. Low temperature and high moisture above a certain optimum level during winter could weaken microbial activity and the gas diffusion in soil matrix, and then make soil GHG emission to the atmosphere decrease. Other soil parameters were also discussed with respect to GHG emissions. Both positive and negative gas fluxes in $CH_4$ and $CO_2$ were observed during these measurements, but not for $N_2O$. It is likely that $CH_4$ and $CO_2$ gases emanated from soil surface or up taken by the soil depending on other factors such as background concentrations and physicochemical soil conditions.