• Journal of Electrical Engineering and Technology
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• 제9권1호
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• pp.6-14
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• 2014

A new method to determine the total harmonic contributions of several customers and the utility at the point of common coupling is presented. The proposed method can quantify the individual harmonic impact of each suspicious harmonic source at the point of common coupling. The individual harmonic impact index is then used to assess the total harmonic contribution of each harmonic source. This index can be calculated by the results processed from instantaneous harmonic voltage and current phasor values. The results demonstrate the performance of the proposed method in terms of steady-state accuracy and response to time-varying operating conditions. The proposed index can be used for billing purposes to control harmonic distortion levels in power systems.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(4)
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• pp.33-36
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• 2002

Multiple Description Coding(MDC) is a technique used to obtain two or more (often correlated) descriptions of a source, which are transmitted over different channels to receiver. Two descriptions of the source support two levels of reconstruction quality. When all the descriptions are received and used in the reconstruction, the source should be reconstructed with acceptable quality. In this work, we consider Multiple Description Scalar Quantizer(MDSQ) to wavelet transform domain. Conventional MDSQ schemes in wavelet domain considered description with equal weights at each sub-bands after quantization. But each sub-bands is unequal contribution to whole image quality. Therefore, we experiment the multiple description with unequal weight in each sub-bands.

• 한국음향학회지
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• 제21권4호
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• pp.146-146
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• 2002

We present a new technique for achieving source separation when given only a single channel recording. The main idea is based on exploiting the inherent time structure of sound sources by learning a priori sets of time-domain basis functions that encode the sources in a statistically efficient manner. We derive a learning algorithm using a maximum likelihood approach given the observed single channel data and sets of basis functions. For each time point we infer the source parameters and their contribution factors. This inference is possible due to the prior knowledge of the basis functions and the associated coefficient densities. A flexible model for density estimation allows accurate modeling of the observation, and our experimental results exhibit a high level of separation performance for simulated mixtures as well as real environment recordings employing mixtures of two different sources. We show separation results of two music signals as well as the separation of two voice signals.

• 한국정보통신학회논문지
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• 제23권12호
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• pp.1742-1745
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• 2019

Hidden flame detection after allegedly extinguishing a fire cannot be emphasized enough. There are a few commercial hidden fire detection equipments which are imported, but the cost is relatively high. In this contribution, we propose a development of a low-cost, high-performance hidden flame detector using open-source hardware/software. We use Raspberry-pi based hardware board equipped with a TFT touch-screen LCD, a 3G modem, and an attachable battery device altogether integrated in a plastic case fabricated with a 3D printer. The proposed hidden flame detector shows the same performance of a commercial product FLIR E5 while consuming less than a half of the cost.

• 한국대기환경학회지
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• 제19권6호
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• pp.789-803
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• 2003

The purpose of this study is to compare the usefulness between Gaussian dispersion model and receptor model with the experimental result of the dispersion tracing of the particulate pollutants from Taean coal-fired power plants. For this purpose, the component analysis of the collected PM 10 samples was performed. In order to trace the pollution sources, factor analysis was done with the result of the component analysis. As a result of the correlativity analysis of the fifteen power plants' profiles offered by US EPA, the correlativity of No.11202 source profile showed highest rate up to 84.5%. Thus it was adopted as proper one and the contribution rate by each pollution source was calculated by Chemical Mass Balance (CMB)-8 model. The contribution rate, which was the effect rate of the power plants on each measuring point, were calculated with a range of 24∼52％ and the standard error was below 0.9 $\mu\textrm{g}$/㎥. This indicates the selection of the source profile was appropriate. Also, the concentrations of each point were calculated by the ISCST3 which is suggested by US EPA as one of the regulatory Gaussian dispersion model. The calculation result showed that the predicted concentration was 50∼58 $\mu\textrm{g}$/㎥, comparing with the measured result of 9∼65 $\mu\textrm{g}$/㎥. It was found that the concentration calculated by ISCST3 was underpredicted. It was thought that the receptor model was more favorable than the Gaussian dispersion model in estimating the effect of the particulate matter on a certain receptive point.

• 한국대기환경학회지
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• 제31권2호
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• pp.105-117
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• 2015

Sources related to road dust is one of the biggest sources, which is responsible for a large portion of emission. In particular, PM2.5 is a potential cause for respiratory diseases, thus it should be managed and a mitigation plan using results of statistical apportionment modeling such as chemical mass balance needs to be established. Recently, identifying sources of PM2.5 and analyzing the contribution of the road dust through a contribution assessment is required. Therefore, this study provides the chemical source profiles of PM2.5 using IC, GC/MS, OCEC, and XRF for both paved sidewalk and paved roadway collected at seven different sampling sites. As a result, for paved sidewalk, $NH{_4}^+$ (70%), $NO{_3}^-$ (12%), $PO{_4}^-$ (9%), and $SO{_4}^{2-}$ (9%) have been analyzed in PM2.5 mass. Major molecular marker such as Si has been indicated as $12.0{\pm}3.4%$ and $13.6{\pm}6.9%$ for paved sidewalk and roadway, respectively. PAHs such as Fluoranthene, Pyrene, Chrysene, and 1,3,5-Triphenylbenzene are suggested as molecular markers for road dust.

• 대한지역사회영양학회지
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• 제19권3호
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• pp.274-282
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• 2014

Objectives: The objective of this study was to revise the target pattern in food guidance system for adolescents' balanced menu planning. Methods: The food groups in the target pattern were divided into detailed food items, and intake number were assigned to each food items based on the revised standard food composition table. The validity of revised target pattern was examined. Menu planning according to the revised target pattern was made available to 305 male and female middle school students and the nutritional assessment of the menu plan were carried out using SPSS WIN 12.0. Results: The energy contents, energy contribution ratios of carbohydrate, fat, and protein, and 4 minerals' and 6 vitamins' contents of the revised target pattern were adequate. The average energy contents of the menu planned according to revised target pattern were 400~500 kcal higher than that of the revised target pattern when the revised standard food composition was applied. The energy contribution ratios of fat were 28.9%, close to maximum of acceptable macronutrient distribution range (AMDR) (30%), and that of carbohydrate were 54.5%, lower than minimum of AMDR (55%). The nutrient adequacy ratios (NARs) of calcium and vitamin C were less than 1.0. According to index of nutritional quality (INQ) of food items, kimchi, milk dairy products, and soybean curd were energy efficient source for calcium, kimchi, fruit, vegetable and seaweed were energy efficient source for vitamin C, with INQ of food items were higher or close to 2.0. Kimchi was the best energy efficient source of calcium and vitamin C. Conclusions: Revised target pattern based on the adolescent's foods intake was not good enough for balanced menu planning by adolescents, because what they ate and what they wanted to eat were very much different. Detailed guidance for food selection is necessary in each food items.

• Nuclear Engineering and Technology
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• 제51권6호
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• pp.1633-1637
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• 2019

While considering the photon attenuation coefficient (${\mu}$) and its related parameters for photons shielding, it is necessary to account for its transmitted and reflected photons energy spectra and dose contribution. Monte Carlo simulation was used to study the efficiency of clay ($1.99g\;cm^{-3}$) as a shielding material below 150 keV photon. Am-241 gamma source and an X-ray of 150 kVp were calculated. The calculated value of ${\mu}$ for Am-241 is higher within 5.61% compared to theoretical value for a single-energy photon. The calculated half-value layer (HVL) is 0.9335 cm, which is lower than that of ordinary concrete for X-ray of 150 kVp. A thickness of 2 cm clay was adequate to attenuate 90% and 85% of the incident photons from Am-241 and X-ray of 150 kVp, respectively. The same thickness of 2 cm could shield the gamma source dose rate of Am-241 (1 MBq) down to $0.0528{\mu}Sv/hr$. For X-ray of 150 kVp, photons below 60 keV were significantly decreased with 2 cm clay and a dose rate reduction by ~80%. The contribution of reflected photons and dose from the clay is negligible for both sources.

• 한국소음진동공학회논문집
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• 제25권4호
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• pp.223-231
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• 2015

Enclosures are widely used to alleviate the contribution of machinery noise. It has been long concerned with the noise transmission through the access openings of the enclosures. In this study, we investigate active noise control technology for reduction of the transmission. A numerical model based on the acoustic boundary element method is first established. Using the numerical model, the acoustic transfer functions of the field points over the opening to the primary source at arbitrary locations are estimated. The feedforward control to minimize the acoustic power through the opening is then numerically implemented. The controller drives the secondary source to destructively interfere the noise transmission through the opening. Finally, a parametric study is conducted to evaluate the effects of the location and the number of the microphones on the control performance. Furthermore, the effects of the location of the secondary source on the performance of active noise control are investigated. It is followed that the control system implemented in this study leads to a significant reduction of about 31.5 dB in the sound power through the opening using only one secondary source located at the optimized position.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.197.2-197.2
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• 2010

The study on the operation characteristics of solar space and water heating system with ground source heat pump (GSHP) as a back-up device was carried out. This system, called solar thermal and geothermal hybrid system (ST/G), was installed at Zero Energy Solar House II (KIER ZeSH-II) in Korea Institute of Energy Research. This ST/G hybrid system was developed to supply all thermal load in a house by renewable energy. The purpose of this study is to find out that this system is optimized and operated normally for the heating load of ZeSH-II. Experiment was continued for seven months, from October to April. The analysis was conducted as followings ; - the contribution of solar thermal system. - the appropriateness of GSHP as a back-up device. - the performance of solar thermal and ground source heat pump system respectively. - the adaptation of thermal peak load - the operation characteristics of hybrid system under different weather conditions. Finally the complementary measures for the system simplification was referred for the commercialization of this hybrid system.