• Journal of Korean Society on Water Environment
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• v.20 no.6
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• pp.603-609
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• 2004

The objective of this study was to determine the optimal operation conditions in an anoxic oxic process to eliminate both organic and nitrogen matters in swine wastewater. For the purpose of this, the removal efficiency was evaluated with various HRTs and internal recycling ratio. During the whole 580 days of experiment, HRTs had been gradually decreased in an order of 20, 14, 12 and l0days, and the internal recycle ratio was kept at 20Q. So as to determine the effect of the internal recycle ratio on the nitrogen removal, the internal recycle ratio had been gradually increased from 20Q to 50Q while HRT was maintained at 12days. As a result, it was shown that the removal efficiency of organic matter was above 95% regardless of changing of HRTs. The average influent concentration of TCODcr and SCODcr were 24,854 mg/L and 18,920 mg/L, respectively. Average removal efficiency of TKN was shown to be nearly 98% when HRT was kept at 12days; however, the $NH_4{^+}-N$ concentration of effluent was shown to be increased when the loading rate of $NH_4{^+}-N$ was increased to $0.602 kgNH_4{^+}-N/m^3$-day by means of decreasing HRT to 10days. It was concluded that nitrogen loading rates should be more considered rather than organic loading rates in case of determining an optimal HRT. When gradually increasing the internal recycle ratio from 20Q to 50Q, the removal efficiency of organic matters and TKN were 96% and 98%, respectively so that no significant changes in removal efficiency was detected. However, when the internal recycle ratio was kept at 50Q, it was revealed that the $NO_3-N$ concentration of effluent seemed to drop and the average $NO_3-N$ concentration of effluent was around 52 mg/L.

• The Mathematical Education
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• v.57 no.1
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• pp.1-36
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• 2018

The purpose of this study is to examine the relationship between utilization of technology and TPACK in mathematics teachers, and to analyze needs and retentions, difference between needs and retentions, and educational needs of TPACK in mathematics teachers. Furthermore, we will prioritize TPACK items that mathematics teachers want to change, and provide implications for teacher education related to TPACK in the future. To do this, we analyzed 328 mathematics teachers nationwide by using survey on the utilization of technology, averages of TPACK's needs and retentions, t-test of two averages, Borich's educational needs analysis, and the Locus for Focus model. The results are as follows. Firstly, the actual utilization rate was lower than the positive recognition of utilization of technology by mathematics teachers, and many mathematics teachers mentioned the lack of knowledge related to TPACK. Secondly, the characteristics of in-service mathematics teacher's needs and retentions for TPACK were clear, and TPACK's starting line of in-service mathematics teacher can be different from pre-mathematics teacher's. The retentions was high in the order of CK, PCK and PK, and the needs was higher in the order of TPACK, TCK, TK and TPK. All of the higher retentions were knowledge related to PCK, and the value of CK was extremely high among them. In addition, mathematics teachers recognized needs for integrated knowledge related to technology, and they needed more TCK than TPK. The difference between needs and retentions showed that all items except two items in the PK were significant. Retentions of all items in CK was higher than needs, needs of all items in TK, TCK, TPK and TPACK was higher than retentions, PK and PCK were mixed. Thirdly, based on the analysis of Borich's educational needs and the Locus for Focus model, teacher education on TPACK for mathematics teachers needs to focus on TPACK, TK, TCK, and TPK. Specifically, TPACK needs to combine technology in terms of creativity-convergence, mathematical connections, communication, improvement of evaluation quality, and TK needs to new technology acquisition, function of utilizing technology, troubleshoot problems with technology, TCK needs to mathematical value(esthetic, practical) with technology, and TPK needs to consider technology in terms of evaluation methods, teaching and learning methods, improvement of pedagogy. Therefore, when determining the direction of teacher education related to TPACK in the future, if they try to reflect these items in detail, the teachers could participate more actively and receive practical help.

• Fire Science and Engineering
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• v.31 no.2
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• pp.52-60
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• 2017

Numerical simulations were performed to evaluate the habitability of an operator for a cabinet fire in the main control room of a nuclear power plant presented in NUREG-1934. To this end, a Fire Dynamics Simulator (FDS), as a representative fire model, was used. As the criteria for determining the habitability of operator, toxic products, such as CO, were also considered, as well as radiative heat flux, upper layer temperature, smoke layer height, and optical density of smoke. As a result, the probabilities of exceeding the criteria for habitability were evaluated through the sensitivity analysis of the major input parameters and the uncertainty analysis of fire model for various fire scenarios, based on V&V (Verification and Validation). Sensitivity analyses of the maximum heat release rate, CO and soot yields, showed that the habitable time and the limit criterion, which determined the habitability, could be changed. The present methodology will be a realistic alternative to enhancing the reliability for a habitability evaluation in the main control room using uncertain information of cabinet fires.

• Journal of Korean Society on Water Environment
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• v.28 no.3
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• pp.347-358
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• 2012

The SWAT (Soil and Water Assessment Tool) should be calibrated and validated with observed data to secure accuracy of model prediction. Recently, the SWAT-CUP (Calibration and Uncertainty Program for SWAT) software, which can calibrate SWAT using various algorithms, were developed to help SWAT users calibrate model efficiently. In this study, three algorithms (GLUE: Generalized Likelihood Uncertainty Estimation, PARASOL: Parameter solution, SUFI-2: Sequential Uncertainty Fitting ver. 2) in the SWAT-CUP were applied for the Soyang-gang dam watershed to evaluate these algorithms. Simulated total streamflow and 0~75% percentile streamflow were compared with observed data, respectively. The NSE (Nash-Sutcliffe Efficiency) and $R^2$ (Coefficient of Determination) values were the same from three algorithms but the P-factor for confidence of calibration ranged from 0.27 to 0.81 . the PARASOL shows the lowest p-factor (0.27), SUFI-2 gives the greatest P-factor (0.81) among these three algorithms. Based on calibration results, the SUFI-2 was found to be suitable for calibration in Soyang-gang dam watershed. Although the NSE and $R^2$ values were satisfactory for total streamflow estimation, the SWAT simulated values for low flow regime were not satisfactory (negative NSE values) in this study. This is because of limitations in semi-distributed SWAT modeling structure, which cannot simulated effects of spatial locations of HRUs (Hydrologic Response Unit) within subwatersheds in SWAT. To solve this problem, a module capable of simulating groundwater/baseflow should be developed and added to the SWAT system. With this enhancement in SWAT/SWAT-CUP, the SWAT estimated streamflow values could be used in determining standard flow rate in TMDLs (Total Maximum Daily Load) application at a watershed.

• Fire Science and Engineering
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• v.32 no.5
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• pp.46-51
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• 2018

The purpose of this study was to assess the evacuation route in a disaster information map to evacuate people to a shelter quickly and precisely during a disaster situation. For this purpose, this study examined the current status of domestic and international disaster information maps and related laws and conducted experiments to derive effective types of intersecting routes. The problems of the disaster information map were obtained through the first preliminary experiment and a survey. Based on these problems, experiments for each type were conducted to provide effective indication information for a disaster information map. To investigate the gait characteristics according to the number of crossing paths, the reduction rate in the crossing path was derived for each type by comparing the previous speed and passing speed. This will enable suggestions to judge the route quickly and accurately when determining the intersecting route in the search for an evacuation route. In conclusion, the experiment of this paper aims to make rapid and accurate evacuations using the disaster information map in response to disasters, and provide guidelines to citizens to contribute to a reduction of casualties.

• Journal of Korean Society for Geospatial Information Science
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• v.17 no.3
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• pp.23-31
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• 2009

The border of the shorelines in a nation is an important factor in determining the border of a national territory, but Korea's shorelines are rapidly changing due to the recent rise in sea level from global warming and growth-centered economic policy over the decades of years. This research was done centering on the areas having well-preserved shorelines as they naturally are and other areas having damaged shorelines in their vicinities due to artificial structures at the two beaches located at the neighboring areas and having mutually homogeneous ocean conditions with each other. First, this research derived the shorelines using the aerial photographies taken from 1947 until 2007 and revised the tidal levels sounding data obtained from a hydrographical survey automation system consisting of Echosounder[Echotrac 3100] and Differential Global Positioning System[Beacon]by using topographical data and ships on land obtained by applying post-processing Kinematic GPS measuring method. In addition, this research evaluated the changes and dimensional variations for the last 60 years by dividing these determined shorelines into 5 sections. As a result, the Haewundae Beach showed a total of 29% decrease rate in dimension as of the year 2007 in comparison with the year 1947 due to a rapid dimensional decline centering on its west areas, while the dimension of the Gwanganri Beach showed an increase in its dimension amounting to a total of 69% due to the decrease in flow velocity by artificial structures built on both ends of the beach-forming accumulation; thus, it was found that there existed a big difference in deposition & accumulation tendency depending on neighboring environment in spite of the homogeneous ocean conditions.

• Publications of The Korean Astronomical Society
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• v.27 no.5
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• pp.419-429
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• 2012

In this paper, we propose a new re-quantization method after FFT processing to prevent the distortion of correlation result of VCS (VLBI Correlation Subsystem). The re-quantization is used to rearrange the data bit so as to reduce the data rate processed as 16-bit of FFT result of VCS. Having done this procedure, we found that the distorted spectrum of correlation result occurred in the delay tracking experiments by the re-quantization method introduced for initial design of VCS. In order to solve this, two kinds of re-quantization method, that is, the comparison and selection-type, are proposed. The first is to re-quantize the FFT result as a valid-bit by comparing with the input data after determining the adequate threshold. The second is manually to select the valid-bit of FFT result after finding the valid-field of data according to the bit-distribution of input data. We confirmed that the second is more effective compared with the first through the experimental result, and it will be implemented without so much modification of applied method in the condition of the limited resource of FPGA. The re-quantization is, however, carried out with 4-bit in the proposed second method for FFT result, and then the distortion of correlation result is also appeared. To fix this problem, the bit for re-quantization is extended to 8-bit. The proposed 8-bit selection-type is effectively verified so that the distortion of correlation result disappeared by applying to VCS in consequence of the simulation and correlation experiments.

• Tuberculosis and Respiratory Diseases
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• v.81 no.2
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• pp.99-105
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• 2018

Acute exacerbation(s) of chronic obstructive pulmonary disease (AECOPD) tend to be critical and debilitating events leading to poorer outcomes in relation to chronic obstructive pulmonary disease (COPD) treatment modalities, and contribute to a higher and earlier mortality rate in COPD patients. Besides pro-active preventative measures intended to obviate acquisition of AECOPD, early recovery from severe AECOPD is an important issue in determining the long-term prognosis of patients diagnosed with COPD. Updated GOLD guidelines and recently published American Thoracic Society/European Respiratory Society clinical recommendations emphasize the importance of use of pharmacologic treatment including bronchodilators, systemic steroids and/or antibiotics. As a non-pharmacologic strategy to combat the effects of AECOPD, noninvasive ventilation (NIV) is recommended as the treatment of choice as this therapy is thought to be most effective in reducing intubation risk in patients diagnosed with AECOPD with acute respiratory failure. Recently, a few adjunctive modalities, including NIV with helmet and helium-oxygen mixture, have been tried in cases of AECOPD with respiratory failure. As yet, insufficient documentation exists to permit recommendation of this therapy without qualification. Although there are too few findings, as yet, to allow for regular andr routine application of those modalities in AECOPD, there is anecdotal evidence to indicate both mechanical and physiological benefits connected with this therapy. High-flow nasal cannula oxygen therapy is another supportive strategy which serves to improve the symptoms of hypoxic respiratory failure. The therapy also produced improvement in ventilatory variables, and it may be successfully applied in cases of hypercapnic respiratory failure. Extracorporeal carbon dioxide removal has been successfully attempted in cases of adult respiratory distress syndrome, with protective hypercapnic ventilatory strategy. Nowadays, it is reported that it was also effective in reducing intubation in AECOPD with hypercapnic respiratory failure. Despite the apparent need for more supporting evidence, efforts to improve efficacy of NIV have continued unabated. It is anticipated that these efforts will, over time, serve toprogressively decrease the risk of intubation and invasive mechanical ventilation in cases of AECOPD with acute respiratory failure.

• Korean Journal of Acupuncture
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• v.18 no.1
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• pp.165-170
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• 2001

A rapid increasing in cultivation area due to favorable price temporarily and decreasing in consumer's demands caused by economic depressions recently, lead the price of Cynanchum wilfordii Hemsley to decline sharply. Thus, it may give rises to weakening of cultivation bases in Cynanchum wilfordii Hemsley. To investigate optimal mechanical peeling conditions of Cynanchum wilfordii Hemsley, protruded rubber, plastic pad, diamond shape's steel and palstic brush were introduced as blades and artificial stone, sand and small pebble were done as abrasives. The main results obtained were summarized as follows; 1. It took 2 minutes per 1kg in mechanical peeling of Cynanchum wilfordii Hemsley's raw root whereas 36 minutes in manual peeling and values of lightness showed more higher in manual peeling than in mechanical peeling. 2. Yield in combination of diamond shape's steel blade and sand abrasive showed the lowest at 89.9% among treatments and peeling rates in combination of diamond shape's steel blade and small pebble showed the highest at 71.3% in mechanical peeling. 3. Lightness, one of the most important factors in determining quality of Cynanchum wilfordii Hemsley, showed the highest in combination of diamond shape's steel blade and small pebble brasive at 61.90 in mechanical peeling. 4. As the speed of rotation gets faster, yields tend to lower in mechanical peeling. Peeling rates and lightness showed the highest at 66.8%, 57.96 respectively among treatments at 30 r.p.m. in mechanical peeling.

• Water for future
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• v.21 no.4
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• pp.399-406
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• 1988

Presented in this paper is a brief summary of the basic theory and observation from a laboratory investigation aimed at determining flow characteristics and ice jam topography in a sinuous channel, and in a single-bend channel. The sinuous channel comprised thirteen $90^{\circ}$ bends and was of comparatively small s\aspect ratio. The single-bend channel was a $180^{\circ}$ bend, which was an order of magnitude large in width as well as aspect ratios than the sinuous channel. The simulated ices were polyethylene and polypropylene beads and block. The streamwise velocities near the bottom were larger than that of surface in sinuous channel and forming ice jam in sinuous channel, this phenoumena were found strongly. Jams were generally thicker along the inner bank of bends. The path of maximum-streamwise velocity was displaced towards approachs side of the inner bank of bends. Radial variation of jam thickness was to be regular by increasing size of ice fragments. The rate of jam head progression around outer bank of the single bend was faster than that of inner bank and its velocity was roughly steady. With increasing Froude number, jm thickness became less uniformly distributed; being generally thicker along the inner bank and near the jam's toe. Two-layer model might be adaptable for the computing the streamwise velocity in shallow river bends. Two cells of secondary flow cound be expected in ice covered-river bends.