• International Journal of Naval Architecture and Ocean Engineering
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• v.10 no.4
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• pp.491-498
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• 2018

The cost evaluation for voyage route planning in an ice-covered sea is one of the major topics among ship owners. Information of the ice properties, such as ice type, concentration of ice, ice thickness, strength of ice, and speed-power relation under ice conditions are important for determining the optimal route in ice and low operational cost perspective. To determine achievable speed at any designated pack ice condition, a model test of resistance, self-propulsion, and overload test in ice and ice-free water were carried out in a KRISO ice tank and towing tank. The available net thrust for ice and an estimation of the ice resistance under any pack ice condition were also performed by I-RES. The in-house code called 'I-RES', which is an ice resistance estimation tool that applies an empirical formula, was modified for the pack ice module in this study. Careful observations of underwater videos of the ice model test made it possible to understand the physical phenomena of underneath of the hull bottom surface and determine the coverage of buoyancy. The clearing resistance of ice can be calculated by subtracting the buoyance and open water resistance form the pre-sawn ice resistance. The model test results in pack ice were compared with the calculation results to obtain a correlation factor among the pack ice resistance, ice concentration, and ship speed. The resulting correlation factors were applied to the calculation results to determine the pack ice resistance under any pack ice condition. The pack ice resistance under the arbitrary pack ice condition could be estimated because software I-RES could control all the ice properties. The available net thrust in ice, which is the over thrust that overcomes the pack ice resistance, will change the speed of a ship according to the bollard pull test results and thruster characteristics (engine & propulsion combination). The attainable speed at a certain ice concentration of pack ice was determined using the interpolation method. This paper reports a procedure to determine the attainable speed in pack ice and the sample calculation using the Araon vessel was performed to confirm the entire process. A more detailed description of the determination of the attainable speed is described. The attainable speed in 1.0 m, 90% pack ice and 540 kPa strength was 13.3 knots.

• Korean Journal of Soil Science and Fertilizer
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• v.41 no.4
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• pp.267-272
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• 2008

Mid-infrared (MIR) spectroscopy, particularly Fourier transform infrared spectroscopy (FTIR), has emerged as an important analytical tool in quantification as well as identification of multi-atomic inorganic ions such as nitrate. In the present study, the possibility of quantifying soil nitrate via diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) without change of a sample phase or with least treated samples was examined. Four types of soils were spectrally characterized in terms of unique bands of soil contents and interferences with nitrate bands in the range of $2000-1000cm^{-1}$. In order to reduce the effects of soil composition on calibration model for nitrate, spectra transformed to the 1st order derivatives were used in the partial least squared regression (PLSR) model and the classification procedure associated with input soil types was involved in calibration system. PLSR calibration models for each soil type provided better performance results ($R^2$>0.95, RPD>6.0) than the model considering just one type of soil as a standard.

• Journal of Food Hygiene and Safety
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• v.26 no.2
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• pp.91-99
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• 2011

Risk ranking must be determined for various hazards/food combinations to conduct microbial risk management effectively. Risk Ranger is a simple, easy-to-use calculation tool developed in Microsoft Excel and designed to rank the risk (low, medium, and high) for semi-quantitative microbial risk assessment. The user is required to answer 11 questions in Risk Ranger related to 1) severity of the hazard, 2) likelihood of a disease-causing dose of the hazard being present in the meal, and 3) the probability of exposure to the hazard in a defined time. This study determined the risk ranking for twenty three combinations of foodborne pathogens/potentially hazardous foods (PHFs) using a Risk Ranger. In this study, pathogenic E. coli in fresh cut produce salad was scored as 79, which was the highest rank among the 23 combinations of the foodborne pathogens and PHFs. On the other hand, zero risk was obtained with V parahaemolyticus in sushi, Salmonella in meat products and E. coli O157:H7 in hamburger patties. Although Risk Ranger is very simple method to rate the risk of foodborne pathogens and PHFs combination, the accuracy of result was mainly affected by the availability and accuracy of data in the literature. According to the result of literature review, the data are needed for contamination rate of raw materials, consumption amount/frequency of PHFs, and the effect of processing on pathogen. Risk ranking must be continuously revalidated with new data.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.3
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• pp.103-110
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• 2016

Recently, structural health monitoring system(SHMS) has been appled cable bridges as the effective maintenance tool and the management threshold is considered to assess the status of the bridge in SHMS. The threshold is generally determined by the allowable limit based on design specification because there is no method and standard for threshold calculation. In case of the conventional thresholds, it is difficult to recognize the event, abnormal behavior and gradual damage within the threshold. Therefore, this study reviewed the problem of previous methods and proposed the advanced methodologies based on probabilistic approach for threshold calculation which can be applied to practice work. Gumbel distribution is adopted in order to calculate the threshold for caution and warning states considering the expectations for return periods of 50 and 100 years. The thresholds were individually determined for measurement data and data variation to detect the various abnormal behaviors within allowable range. Finally, it has confirmed that the thresholds by the proposed method is detectable the abnormal behavior of real-time measuring data from SHMS.

• Journal of Korean Society of Transportation
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• v.27 no.4
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• pp.195-206
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• 2009

The deregulation of aviation markets in Europe and the United Sates had led airlines to reconfigure their networks into hub-and-spoke systems. Recent trends of "Open Skies" in the Asian aviation market are also expected to prompt the reformation of airlines' networks in the region. A significant connectivity index is a crucial tool for airlines and airport authorities to estimate the degree of hub-and-spoke operations. Therefore, this paper suggests a new index, Continuous Indirect Connectivity Index (CICI), for measuring the coordination of airlines' flight schedules, applying it to the Asian, European and the American aviation markets. CICI consists of three components：(i) temporal connectivity to identify the attractiveness between connection flights, (ii) spatial connectivity to differentiate the attractiveness by de-routing distance with continuous linear function, and (iii) relative intensity to reflect the effect of direct flight frequency on transfer routes. CICI is evaluated to examine a casual relationship through regression analyses with two dependent variables of the number of transfer passengers and transfer rates. Compared with Danesi's index and Doganis' index through evaluation processes, CICI has a higher coefficient value of determination, implying that it explains the relationship between connectivity and transfer passengers more precisely.

• Korean Journal of Ecology and Environment
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• v.50 no.4
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• pp.452-458
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• 2017

The nitrogen isotope value in both ammonium and nitrate ion were determined at 9 stations during both June and August 2016, in order to understand the origin of DIN at the Han river. ${\delta}^{15}N-NO_3$ and ${\delta}^{15}N-NH_4$ values in 8 stations (CP, SB, MHC, P4, SJ, SBC, P2, SC) were no significant variation. However ${\delta}^{15}N-NO_3$ and ${\delta}^{15}N-NH_4$ values in KK (Kyeongan stream) showed significant different in comparison with 8 stations, with an apparent increase of nitrogen isotope values. These results indicate that antropogenic nitrogen source influence on KK station. Also the ${\delta}^{13}C$ and ${\delta}^{15}N$ isotope ratio of phytoplankton (Diatom and Cyanobacteria) in KK (Kyeongan stream) showed heavier values, compared to other study stations. These results indicate that nitrogen isotope value in phytoplankton effects by different nitrogen source in study sites. These results suggest that the analysis of stable isotope ratios is a simple but useful tool for the identification of dissolved inorganic nitrogen origin in aquatic environments.

• Journal of Food Hygiene and Safety
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• v.3 no.2
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• pp.65-73
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• 1988

T-2 toxin is one of mycotoxins produced by fungi such as Fusarium spp. and possesses a potent cytotoxicity to eukaryotic cell. The contamination of mycotoxins in cereals and feedstuffs is one of the great concerns in health authorities. Therefore, the development of the specific, sensitive and simplified analysis method for T -2 toxin is required. During more than ten years, several chemical and biological analysis methods were proposed and applied for the detection and quantification of T-2 toxin. TLC, GLC-FID and GC-MS are widely employed, but these methods required numerous clean-up procedures before analysis, and the detection limit for T-2 toxin is more than 10 ppb. Biological analysis methods with dermal tissues and cultured cells are not specific to T-2 toxin, since T-2 toxin and other related derivatives possess a similar toxicological activity although their relative activity is different each otber. Based on tbe specific reaction between antibody and antigen, the authors tried to introduce the immunochemical methods for determination of T-2 toxin. The enzyme-linked immunosorbent assay method using monoclonal antibody for T-2 toxin was applied to analyse T-2 toxin. The detection limit of T-2 toxin by ELISA method was 0.1 ppb. The correlation between ELISA and GC-MS method on these samples was very high. ELISA method developed for the detection and quantification of T -2 toxin in this paper possesses simplicity, high sensitivity and specific for T-2 toxin. Furthermore, the ELISA method with T-2 toxin monoclonal antibody was an excellent tool for the screening of Fusarium spp. which was suspected to produce T-2 toxin.

• Journal of the Korean Magnetics Society
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• v.5 no.3
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• pp.216-221
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• 1995

Both manufacturing parameters and particles' chemical composition controll coercivity and its distribution of magnetic particles. The coercivity and its distribution are important properties for high density magnetic recording, so these are used as tool for evaluation of reproducibility of magnetic particles. We report in this paper the applications of dM/dH versus H curve, which is derived from magnetic hysteresis loop, to the evaluation of coercivity distribution of magnetic particles and oxidation studies of recording metal particles. The coercivity distri-bution can be estimated from the full width half rnaximun (FWHM) and the peak shape of the dM/dH versus H curve. The peak shape of the curve depends upon distribution of particles' coercivity. The peak of dM/dH versus H curve becomes broad and lor is splitted into two or rmre peaks. It depends on uniformity of particles' coercivity. When the coercivity difference between Ba-Ferrite and ${\gamma}-Fe_{2}O_{3}$ is larger than 600 Oe, the peak becomes broad and is consequently splitted into two peaks. Ununiformly substituted Ba-Ferrite particles show broad peak. It is apparent that the analysis of the curve is one of sensitive measuring techniques for determination of coercivity distri-bution and studies on magnetic properties of substituted Ba-Ferrite and oxidation of magnetic recording metal particles.

• 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.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.6
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• pp.394-399
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• 2005

Near Infrared Spectroscopy (NIRS) has been used as a tool for the rapid, accurate and nondestructive assay of the fresh rice leaf in nitrogen content. NIRS used in this study was visible and near infrared spectroscopy type instrument, Foss model 6500. To obtain a useful calibration equation, standard regression between the data was analyzed by chemical analysis and by NIRS method. Accuracy of calibration equation for nitrogen content on fresh leaf of rice were 0.879, 0.858 and 0.819, respectively. Accuracy of calibration equation after outlier treatment increased as 0.017, 0.02 and 0.061 improved each with 0.896, 0.878 and 0.880, respectively. Calibration equation combined using merge function after accuracy of calibration equation more increased by 0.911. Difference analysis value between calibration equation and lab value by kjeldahl showed $0.001\%$. With this as same result is the possibility of closing the deterioration of the sample in order to omit a construction and pulverization process it is judged with the fact that the nitrogen content measurement of the fresh rice leaf which the possibility of reducing an hour and an expense is by a near infrared spectroscopy technique will be possible.