• Journal of Environmental Health Sciences
• /
• v.34 no.3
• /
• pp.199-206
• /
• 2008

This study was conducted to estimate nitrogen dioxide levels and health risk in various locations/situations for two groups. The nitrogen dioxide levels were measured for residents of a study group (industrial area within 5 km) and a control group (15 km farther), respectively using the nitrogen dioxide filter badge as a passive sampler from August, 2006 to September, 2006. The means of indoor, outdoor, work and personal levels of nitrogen dioxide were $34.65{\pm}1.95\;{\mu}g/m^3$, $34.83{\pm}11.78\;{\mu}g/m^3$, $34.98{\pm}19.11$ and $35.38{\pm}10.74$ respectively in the study area. Mean ratio of indoor to outdoor $NO_2$ concentration was 0.99. The means of indoor, outdoor and personal level of nitrogen dioxide were $23.66{\pm}7.19\;{\mu}g/m^3$, $18.22{\pm}4.06\;{\mu}g/m^3$ and $27.27{\pm}18.93\;{\mu}g/m^3$ respectively in the control area. Mean ratio of indoor to outdoor $NO_2$ concentration was 1.39. People spent 80.9% of their time in indoor at the study area and 76.9% at the control area. The percentages of time spent in outdoor were 14.9% and 20.9% at the study area and the control area respectively. The percentages of time spent in a car were 4.2% and 2.2% in the study and control areas respectively. The levels of indoor, outdoor, workplace nitrogen dioxide in the study area and the control area were found below the permissible level of health-hazardous effects.

• The Journal of the Korea Contents Association
• /
• v.11 no.3
• /
• pp.1-8
• /
• 2011

Automatic vehicle license plate recognition technology is widely used in gate control and parking control of vehicles, and police enforcement of illegal vehicles. However inherent geometric information of the license plate can be transformed in the vehicle images due to the slant and the sunlight or lighting environment. In this paper, a distortion invariant vehicle license plate extraction and recognition algorithm is proposed. First, a binary image reserving clean character strokes can be achieved by using a DoG filter. A plate area can be extracted by using the location of consecutive digit numbers that reserves distortion invariant characteristic. License plate is recognized by using neural networks after geometric distortion correction and image enhancement. The simulation results of the proposed algorithm show that the accuracy is 98.4% and the average speed is 0.05 seconds in the recognition of 6,200 vehicle images that are obtained by using commercial LPR system.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.32 no.4
• /
• pp.501-506
• /
• 1999

This study was conducted to evaluate the purification efficiency in rearing water of the land based fish farm by screen filter and ultra violet (UV) irradiation. Purification efficiency for rearing seawater has been examined with screen filter of 60 $\mu$m pore size and UV irradiation at dose of 0.5 $mWS/cm^2$ for 5 months. Purification efficiency by changing of temperature, salinity, pH, DO, total bacteria and Vibrio species in rearing seawater by filtering and UV irradiation were not significant during 5 months, However, the removing rate of suspended solid and turbidity of rearing seawater were $43.8\~45.6\%$ (average, $44,7\%$) and $29.2\~33.2\%$ (average, $31,3\%$) by filtering, respectively. Also, Purification efficiency for the $NO_3^{-}-N,\;NO_2^{-}-N,\;NH_4^{+}-N$ and $PO_4^{3-}-P$ were $21.3\~21.9\%$ (average, $21.6\%$), $24.1\~25.2\%$ (average, $24.7\%$), $17.6\~17.8\%$ (average, $17.7\%$) and $19.0\~20.4\%$ (average, $19.7\%$) respectively by the system used on this study.

• Journal of radiological science and technology
• /
• v.32 no.1
• /
• pp.45-52
• /
• 2009

Digital Mammography is an efficient imaging technique for the detection and diagnosis of breast pathological disorders. Six mammographic criteria such as number of cluster, number, size, extent and morphologic shape of microcalcification, and presence of mass, were reviewed and correlation with pathologic diagnosis were evaluated. It is very important to find breast cancer early when treatment can reduce deaths from breast cancer and breast incision. In screening breast cancer, mammography is typically used to view the internal organization. Clusterig microcalcifications on mammography represent an important feature of breast mass, especially that of intraductal carcinoma. Because microcalcification has high correlation with breast cancer, a cluster of a microcalcification can be very helpful for the clinical doctor to predict breast cancer. For this study, three steps of quantitative evaluation are proposed : DoG filter, adaptive thresholding, Expectation maximization. Through the proposed algorithm, each cluster in the distribution of microcalcification was able to measure the number calcification and length of cluster also can be used to automatically diagnose breast cancer as indicators of the primary diagnosis.

• Korean Journal of Ecology and Environment
• /
• v.39 no.2 s.116
• /
• pp.271-283
• /
• 2006

A systematic water quality survey was conducted in August, 2005 for a drinking water supply reservoir (the Jeolgol reseuoir located in an island), which is at an early stage of impoundment, to investigate the causes of water color deterioration of the reservoir and the clogging of filter beds of a water treatment plant. The reservoir shape was simple and its average depth was 5.5 m, increasing from upreservoir toward the downreservoir end near the dam. Dissolved oxygen (DO) and chloropllyll-a (chi-a) showed a large variation while water temperature had a smaller range. Transparency ranged from 0.6 to 0.9 m (average 0.7 m). The average value of turbidity was 9.3 NTU, ranging from 8.0 ${\sim}$ 12.1 NTU. The transparency and the turbidity appear to be affected by a combination of biological and non-biological factors. The poor transparency was explained by an increase of inorganic colloids and algal bloom in the reservoir. The blockage of the filter bed was attributed to the oversupply of phytoplanktons from the reservoir. The range and the average concentration of chi-a within the reservoir were 31.6 ${\sim}$ 258.9 ${\mu}g\;L^{-1}$, 123.6 ${\mu}g\;L^{-1}$ for the upper layer, and 17.0 ${\sim}$ 37.4 ${\mu}g\;L^{-1}$, 26.5 ${\mu}g\;L^{-1}$ for the bottom layer, respectively. A predominant species contributing the algal bloom was Dinophyceae, Peridinium bipes f. occultatum. The distribution of Peridinium spp. was correlated with chi-a concentrations. The standing crop of phytoplankton was highest in the upreservoir with $8.5\;{\times}\;103\;cells\;mL^{-1}$ and it decreased toward the downresevoir. Synedra of Bacillariophyceae and Microcystis aeruginosa of Cyanophyceae appeared to contribute to the algal bloom, although they are not dominated. It is mostly likely that sloped farmlands located in the watershed of the reservoir caused water quality problems because they may contain a significant amount of the nutrients originated from fertilizers. In addition, the aerators installed in the reservoir and a shortage of the inflowing water may be related to the poor water quality. A long-term monitoring and an integrated management plan for the water quality of the watersheds and the reservoir may be required to improve the water quality of the reservoir.

• Journal of Environmental Science International
• /
• v.19 no.9
• /
• pp.1119-1127
• /
• 2010

The behavior of copper throughout the whole process of wastewater treatment plant that uses the activated sludge process to treat the wastewater of petrochemical industry that contains low concentration of copper was investigated. Total inflow rate of wastewater that flows into the aeration tank was $697\;m^3$/day with 0.369 mg/L of copper concentration, that is, total copper influx was 257.2 g/day. The ranges of copper concentrations of the influent to the aeration tank and effluent from the one were 0.315 ~ 0.398 mg/L and 0.159 ~ 0.192 mg/L, respectively. The average removal rate of copper in the aeration tank was 50.8 %. The bioconcentration factor (BCF) of copper by microbes in the aeration tank was 3,320. The accumulated removal rate of copper throughout the activated sludge process was 71.3%, showing a high removal ratio by physical and chemical reactions in addition to biosorption by microbes. The concentration of copper in the solid dehydrated by filter press ranged from 74.8 mg/kg to 77.2 mg/kg and the concentration of copper by elution test of waste was 2.690 ~ 2.920 mg/L. It was judged that the copper concentration in dehydrated solid by bioconcentration could be managed with the control of that in the influent.

• ETRI Journal
• /
• v.43 no.4
• /
• pp.660-673
• /
• 2021

To efficiently use frequency resources, the next 6th generation mobile communication technology must solve the problem of out-of-band emission (OoBE) of cyclic prefix (CP) orthogonal frequency division multiplexing (OFDM), which is not solved in 5th generation technology. This study describes a new zero insertion technique to replace an existing filtering scheme to solve this internal problem in OFDM signals. In the development of the proposed scheme, a precoder with a two-dimensional structure is first designed by generating a two-dimensional mapper and using the specialty of each matrix. A spectral shaping technique based on zero insertion instead of a long filter is proposed, so it can be applied not only to long OFDM symbols, but also very short ones. The proposed method shows that the transmitted signal is completely blocked at the bandwidth boundaries of signals according to the current standards, and it is confirmed that the proposed scheme is ideal with respect to bit error rate (BER) performance because its BER is the same as that of CP-OFDM. In addition, the proposed scheme can transformed into a real time structure through vectorizing process with minimal complexity.

• Korean Journal of Environmental Biology
• /
• v.35 no.4
• /
• pp.492-500
• /
• 2017

The purpose of this study was to investigate the seasonal distribution of phytoplankton as prey for oysters and to characterize the environmental factors controlling their abundance from June 2016 to May 2017, in the northeast coast between Tongyeong and Saryang Island, particularly for the oyster farming area. During the survey period, water temperature changed from $7.54^{\circ}C$ in February to $29.5^{\circ}C$ in August. The abnormal high temperature persisted during one month in August. Salinity was low due to summer rainfall and typhoon. The lowest level was 30.68 psu in September, and it peaked at 34.24 psu in May. The dissolved oxygen (DO) concentration ranged from $6.0-9.45mg\;L^{-1}$, and the DO concentration in the surface layer was like that in the bottom layers. The seasonal trends of pH were also like those of DO. The pH ranged from 7.91 to 8.50. Nitrate with nitrite, phosphate, and silicate concentrations ranged from $0.14{\mu}M$ to $7.66{\mu}M$, from $0.01{\mu}M$ to $4.16{\mu}M$, and from $0.27{\mu}M$ to $20.33{\mu}M$, respectively. The concentration of chlorophyll a (Chl. a) ranged from $0.37{\mu}g\;L^{-1}$ to $2.44{\mu}g\;L^{-1}$ in the surface layer. The annual average concentration was $1.26{\mu}g\;L^{-1}$. The annual mean phytoplankton community comprised Bacillariophyta (69%), Dinophyta (17%), and Cryptophyta (10%), respectively. Dinoflagellate Prorocentrum donghaiense in June was the most dominant at 90%. In the summer, diatom Chaetoceros decipiens, Rhizosolenia setigera and Pseudo-nitzschia delicatissima were dominant. These species shifted to diatom Chaetoceros spp. and Crytophyta species in autumn. In the winter, high densities of Skeletonema spp. and Eucampia zodiacus were maintained. Therefore, the researchers thought that the annual mean Chl. a concentration was relatively lower to sustain oyster feeding, implying that the prey organism (i.e., phytoplankton) was greatly controlled by continuous filter feeding behavior of oyster in the vicinity area of the oyster culture farm.

• Journal of the Korean Society for Precision Engineering
• /
• v.30 no.9
• /
• pp.901-908
• /
• 2013

The introduction of industrial intelligent robot using vision sensor has been interested in automated factory. 2D and 3D vision sensors have used to recognize object and to estimate object pose, which is for packaging parts onto a complete whole. But it is not trivial task due to illumination and various types of objects. Object image has distorted due to illumination that has caused low reliability in recognition. In this paper, recognition method of complex shape object has been proposed. An accurate object region has detected from combined binary image, which has achieved using DoG filter and local adaptive binarization. The object has recognized using neural network, which is trained with sub-divided object class according to object type and rotation angle. Predefined shape model of object and maximal slope have used to estimate the pose of object. The performance has evaluated on ETRI database and recognition rate of 96% has obtained.

• Journal of Korean Society of Water and Wastewater
• /
• v.21 no.1
• /
• pp.123-130
• /
• 2007

The effects of hydrogen peroxide treatment on the reduction of waterworks sludge were investigated in this study. Sludge treated by peroxidation $H_2O_2$ oxidation) was dewatered using a pressure filter at 3atm. It was observed that $H_2O_2$ treatment at the acidic condition significantly reduce both cake water content and specific resistance to filtration (SRF), indicating the enhancement of dewaterability and filterability. The filterability by hydrogen peroxide treatment at pH 3.5 was better than acidic treatment and became comparable with polymer conditioning. The sludge filterability evaluated by SRF was optimal at a dose 2ml $H_2O_2$/sludge($0.02g\;H_2O_2/gTS$) after adjusting of pH to 3.5. The $H_2O_2$ oxidation at pH 3.5 also produced even more dewatered cake when compared with polymer conditioning. The reduction rate of sludge mass at an optimal condition showed 34% compared with untreated sludge. The effects of peroxidation on sludge properties including zeta potential, bound water and particle size were also evaluated. Peroxidation at the acidic condition reduced both bound water and zeta potential. By $H_2O_2$ combined with sulfuric acid leached iron caused Fenton's reaction, which showed a potential to significantly reduce the amount of solids mass and to produce more compact cake with higher filterability.