• Journal of Environmental Science International
• /
• v.20 no.12
• /
• pp.1533-1540
• /
• 2011

This study was conducted to identify the sedimentation quantity and settling velocity, sediment fundamental data that an important position of water quality management of Seston, POC, PP and PN in Nakdong river basin using a sediment traps to collect suspended material pollutants. Nakdong river basin is that average sedimentation quantity of seston, POC, PP and PN were 124~1,125 g/$m^2$/d, 2,963~25,072, 26~347, 445~2,184 mg/$m^2$/d, respectively. Settling velocity of Seston, POC, PP and PN were 17.0, 35.5, 8.7, 2.4 m/d. It was appeared that various results according to the river flow, weather and other environmental factors. There was no significant correlation, each suspended material pollutants. Sedimentation rates are likely to be overestimated because the flow is not considered to resuspended materials. Therefore diversification through continued monitoring is needed to be analyzed.

• Journal of the Institute of Convergence Signal Processing
• /
• v.13 no.3
• /
• pp.150-155
• /
• 2012

POC(Phase-Only Correlation) is a useful method that can conduct face recognition without using feature extraction or eigenface, but uses Fourier transformation for square areas. In this paper, we propose an effective face area to increase the performance of face recognition using POC. Specifically, three areas are experimented for POC. The frist area is the square area that includes head and space. The second area is the square area from ear to ear horizontally and from the end of chin to the forehead vertically. The third area is the square area from the line under the lips to the forehead vertically and from cheek to cheek horizontally. Experimental results show that the second face area has the best advantage among the three types of areas to define the threshold for POC.

• Journal of Korean Society on Water Environment
• /
• v.27 no.1
• /
• pp.88-97
• /
• 2011

To identify the inflow and outflow characteristics of allchthonous organic matters and examine the change of allochthonous organic matter load pattern due to the climate change, we investigated the temporal variations of DOC and POC concentrations within inflow water and dam discharge water and spatio-temporal distribution of POM within the lake water in Lake Soyang which is the largest dam reservoir in Korea in 2006. Most of allochthonous DOC flowed into the lake water during initial rain and was not affected by the amount of precipitation, whereas most of allochthonous POC flowed into during concentrated heavy rain and the concentration of POC was significantly associated with the amount of inflow water and precipitation. Calculated annual allochthonous organic matter loads in Lake Soyang from 2003 to 2006 using the regression equation between the amount of inflow water and the concentration of POC indicate allochthonous organic matter loads are mainly affected by total influx and extreme influx of inflow water. The spatio-temporal distribution of POM indicated allochthonous organic matter of inflow river during flood period in July transported from upper part to middle and lower part of the lake a month later respectively along the middle layer of water column in Lake Soyang.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.39 no.11
• /
• pp.1123-1129
• /
• 2015

A pair of two-way valves typically is used in automotive washing machines, where the water flow direction is frequently reversed and highly pressurized clean water is sprayed to remove the oil and dirt remaining on machined engine and transmission blocks. Although this valve system has been widely used because of its competitive price, its application is sometimes restricted by surging effects, such as pressure ripples occurring in rapid changes in water flow caused by inaccurate valve control. As an alternative, one three-way reversing valve can replace the valve system because it provides rapid and accurate changes to the water flow direction without any precise control device. However, a cavitation effect occurs because of the complicated bottom plug shape of the valve. In this study, the cavitation index and percent of cavitation (POC) were introduced to numerically evaluate fluid flows via computational fluid dynamics (CFD) analysis. To reduce the cavitation effect generated by the bottom plug, the optimal shape design was carried out through a parametric study, in which a simple computer-aided engineering (CAE) model was applied to avoid time-consuming CFD analysis and difficulties in achieving convergence. The optimal shape design process using full factorial design of experiments (DOEs) and an artificial neural network meta-model yielded the optimal waist and tail length of the bottom plug with a POC value of less than 30%, which meets the requirement of no cavitation occurrence. The optimal waist length, tail length and POC value were found to 6.42 mm, 6.96 mm and 27%, respectively.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.26 no.2
• /
• pp.145-166
• /
• 2021

For several decades, sediment traps have served as one of the key tools for constraining the biological carbon pump (BCP), a process that vertically exports particulate organic carbon (POC) and associated biogenic materials from marine primary production in surface waters to the deep ocean interior. In this paper, I introduced the general methods, the current status of global sediment trap studies, and importance of it to understand the deep ocean carbon cycling. Recent studies suggest that sinking POC in the deep ocean are more complex and spatio-temporally heterogeneous than we considered. Especially researches those studied resuspended and laterally transported particles are presented. Researches that used organic (radiocarbon; ¹⁴C) and inorganic (Al) tracers to understand the oceanic POC cycling and the significance of resuspended particles are reviewed, and the importance of radiocarbon study by using MICADAS (Mini radioCarbon Dating Systems) is emphasized.

• The Journal of Korean Academic Society of Nursing Education
• /
• v.14 no.2
• /
• pp.262-272
• /
• 2008

Purpose: This study examined the validity and reliability of the Korean version of the Revised Process of Change for Weight Control Scale (POC-WCS) in adults with metabolic syndrome. Method: A methodological research design with an exploratory factor analysis for validity and correlational coefficients for reliability was used. The Korean version of the Revised POC-WCS was translated into Korean and a translation equivalency was obtained. It was tested with one hundred and fifty-one obese adults with metabolic syndrome in a university hospital. The data were analyzed using Cronbach's alpha and Guttman coefficients and a principal component factor analysis with SPSS/WIN 12.0. Result: The factor analysis identified eight factors explaining 64.7% of the total variance. The Korean version of the Revised POC-WCS included stimulus control (9 items), dramatic relief (6 items), reinforcement management (6 items), helping relationships (4 items), consciousness raising (3 items), self liberation (3 items), self reevaluation (3 items), and social liberation (4 items). The internal consistency was acceptable with Cronbach's alpha (.94) and Guttman coefficient (.92). Conclusion: The Korean version of the Revised POC-WCS had adequate validity and reliability in adults with metabolic syndrome. It can be used to assess the strategies and processes for weight control in a variety of populations with obesity.

• Journal of Information Science Theory and Practice
• /
• v.5 no.4
• /
• pp.26-38
• /
• 2017

Even through many professional organizations increasingly use Q&A sites in their online communities for information sharing, there are few studies which examine what is really going on in the Q&A activities in professional online communities (POC). This study aims to examine the interaction patterns and contents posted in the Q&A site of a POC, KOSEN, a science and technology online community in South Korea, focusing on how actively scientific information and knowledge are shared. The interaction patterns among the participants were identified through social network analysis (SNA) and the contents in the Q&As were examined by content analysis. The results show that the overall network indicated a moderate level of participation and connection and answerers especially tended to be active. Also, there are different interaction patterns depending on academic fields. Relatively few participants were posting leaders who seemed to steer the overall interactions. Furthermore, some content related to manipulation and explanation for experiments, which are in urgent need, seem to be posted in the sites more frequently with more amounts. Combining both SNA and content analysis, this study demonstrated how actively information and knowledge is shared and what types of contents are exchanged. The findings have practical implications for POC managers and practitioners.

• Journal of Environmental Science International
• /
• v.29 no.5
• /
• pp.531-539
• /
• 2020

To understand the composition, quantity, and quality of Suspended Particulate Organic Matter (SPOM) in the Gangneung Namdae Stream, Korea, we examined spatiotemporal variations in water temperature, salinity, chlorophlly a (Chl a), Particulate Organic Carbon (POC) and nitrogen (PON), and carbon stable isotope (δ¹³C) of SPOM at six stations in June (pre-monsoon), July (monsoon), and September (post-monsoon) 2017. With increasing precipitation, the average POC and C/N values increased significantly in July than in June. In September, the values decreased with decreasing precipitation. The δ¹³C values showed irregular spatiotemporal fluctuations among the stations and periods, thereby suggesting a greater contribution of autochthonous organic matter to the pool of SPOM than that of allochthonous organic matter derived from upstream. In addition, the large and irregular changes in POC, C/N ratio, C:Chl a, and δ¹³C compared to that of PON were observed for all periods among the stations, indicating a serial discontinuity of the stream. Our results suggest that the Gangneung Namdae Stream is significantly influenced by the increase in freshwater discharge caused by heavy rainfalls during the summer monsoon and post-monsoon periods.

• Journal of Korean Society on Water Environment
• /
• v.30 no.5
• /
• pp.512-516
• /
• 2014

Two different methods for TOC (Total Organic Carbon) analysis of livestock manure including high strength solid organics were evaluated. Firstly, an analyzing method by dilution after pre-treated by Ultrasonicator and 100 mesh sieve for homogenization was defined as TOC 1; and secondly method divided by particulate organic carbon (POC) and dissolved organic carbon (DOC) was defined as TOC 2. 116 samples collected from 56 farms were analyzed in TOC1, TOC2, BOD and VSS. TOC1 method showed higher accuracy at less than 30,000 mg/L of TOC while TOC2 method presented significant reliability at over that concentration. Regarding to the sample with the same VSS concentration, the correlation between TOC 2 and VSS (${\rho}$: 0.806) was slightly higher than that between TOC 1 and VSS (${\rho}$: 0.784), resulted from a relatively low loss of solids and a low error probability (dilution and homogenization effects) in the analyzing procedures. In addition, the reliability between POC and VSS in TOC2 was high and the POC was about 4.4 fold that of the VSS. Consequently, TOC 2 without dilution effect was assessed as a proper method to increase the analyzing accuracy of swine manure including high solid organics.

• Environmental Analysis Health and Toxicology
• /
• v.5 no.3_4
• /
• pp.19-28
• /
• 1990

Nitroarenes are ubiquitous environmental pollutants displaying potent mutagenicity in bacteria and carcinogenicity in mammal. In this study, the concentration of nitroarenes in coarse and fine particles and mutagenicity of POC$\_$N/ fraction was investigated in suspended particulates at the Shinchon and Bulkwang area of Seoul. The suspended particulates were collected bimonthly by a high volume cascade impactor air sampler from July 1987 to May 1988. Extractable organic matter was obtained by ultrasonic extraction on diethly ether/cyclohexane (8/2, v/v). Neutral fraction was obtained by liquid-liquid extraction. Polar neutral organic compounds (POC$\_$N/) was fractionated by thin-layer chromatography. Finally, the concentrations of nitroarenes in POC$\_$N/ fraction were measured and determined by capillary gas chromatography. Direct and indirect mutagenicity of POC$\_$N/ fraction were measured using Salmonella typhimurium TA 98. The result were as follows: 1) Major nitroarenes at the Shinchon area was 1-nitropyrene and at the Bulkwang area it was 2,7-dinitro-9-fluorenone during the year. 2) Average concentration of total nitroarenes measured was 67.26 ng/m$^3$in fine particles which was 1,3 folds higher that in coarse particle (52.30 ng/m$^3$). 3) Annual pattern of nitroarenes concentrations revealed that concentration during heating season (Feb., Jan., Mar.) was 2.2 folds higher than that in non heating season (May, Jul., Sep.). Concentration of each season has 157.68 ng/m$^3$and 80.39 ng/m$^3$. 4) The mutagenic activity of POC$\_$N/ fraction from fine particles was higher compared to that of coarse particles and was increased when metabolically activated, with 59 mixture. Mutagenicities, Metabolically activated, were significantly different between Shinchon and Bulkwang area, 322.8 rev/250 $\mu\textrm{g}$/plate and 286.8 rev/250 $\mu\textrm{g}$/plate, respectively. 5) Annual pattern of mutagenicity of POC$\_$N/ fraction revealed that mutagenicity during the heating season was 1.7 folds higher at Shinchon area and 1.2 folds higher at Bulkwang than during the non heating season. The variable contents and levels of nitroarenes in suspended particulates may affect human health significantly. Further studies such as risk assessment should be conducted on the basis of these kind of studies.