• Journal of The Korean Society of Agricultural Engineers
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• v.51 no.3
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• pp.53-62
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• 2009

This study was carried out to select optimal probability distribution based on design accumulated monthly mean inflow from the viewpoint of drought by Gamma (GAM), Generalized extreme value (GEV), Generalized logistic (GLO), Generalized normal (GNO), Generalized pareto (GPA), Gumbel (GUM), Normal (NOR), Pearson type 3 (PT3), Wakeby (WAK) and Kappa (KAP) distributions for the observed accumulative monthly mean inflow of Chungjudam. L-moment ratio was calculated using observed accumulative monthly mean inflow. Parameters of 10 probability distributions were estimated by the method of L-moments with the observed accumulated monthly mean inflow. Design accumulated monthly mean inflows obtained by the method of L-moments using different methods for plotting positions formulas in the 10 probability distributions were compared by relative mean error (RME) and relative absolute error (RAE) respectively. It has shown that the design accumulative monthly mean inflow derived by the method of L-moments using Weibull plotting position formula in WAK and KAP distributions were much closer to those of the observed accumulative monthly mean inflow in comparison with those obtained by the method of L-moment with the different formulas for plotting positions in other distributions from the viewpoint of RME and RAE.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.47 no.2
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• pp.108-117
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• 2011

In order to offer data about fisheries resources management and prediction of catch on large purse seine fisheries, the fluctuation of the fisheries condition and distributions of fishing ground for mackerel were analysed with monthly catch data for 1990.2009. The overall catch has decreased to about 70% since 1997, with approximately 70% of the mackerel (Scomber japonicus) catch and monthly fluctuations showing a similar pattern. Monthly distribution of fishing ground is like distribution of mackerel in large purse seine fishery. The main fishing grounds are near Jeju Island and the Yellow sea with the main fishing season existing between October to December. The catches fluctuations and distribution of fishing ground were related to the effect of regime shifts. Therefore, in order to prediction of catch on large purse seine fisheries should be studied these relationships.

• Journal of Korean Society of Water and Wastewater
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• v.30 no.4
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• pp.369-379
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• 2016

It was confirmed that the extreme value distribution model applies to probability of exceeding more than once a day monthly the facility capacities using data of daily maximum inflow rate for 7 wastewater treatment plant. The result of applying the extreme value model, A, D, E wastewater treatment plant has a problem compared to B, C, F, G wastewater treatment plant. but all the wastewater treatment plant has a problem except C, F wastewater treatment plant based 80% of facility capacity. In conclusion, if you make a standard in statistical aspects probability exceeding more than once a day monthly can be 'exceed day is less than a few times annually' or 'probability of exceeding more than once a day monthly is less than what percent'.

• Journal of Korea Water Resources Association
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• v.56 no.11
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• pp.705-720
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• 2023

In South Korea, ongoing incidents related to drinking water quality have eroded consumer trust. Specifically, beyond quality incidents, there have been complaints about taste, odor, and other issues stemming from the presence of chlorine. To address this, water service operators are employing various management strategies from both temporal (scheduling) and spatial (rechlorination) perspectives to ensure uniform and safe distribution of chlorine residuals. In this study, we focus on the optimal monthly management of chlorine residuals, based on water distribution network analysis. Water quality reaction coefficients, including bulk fluid and wall reaction coefficients, were estimated through lab-scale tests and EPANET water quality simulations, respectively, accounting for temperature variations in a large-scale water distribution network. Utilizing these estimated coefficients, we examined the monthly variations in chlorine residual distribution under different chlorine injection conditions. The results indicate that the efficient concentration for chlorine injection, which satisfies the residual chlorine limit range, varies with temperature changes. Consequently, it is imperative to establish a specific and quantitative chlorine injection plan that considers the accurate spatial distribution of monthly chlorine residuals.

• Journal of Distribution Science
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• v.20 no.3
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• pp.45-52
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• 2022

Purpose: This study investigated the impact of staff verbal and non-verbal communication on consumer satisfaction and revisit intention. The study sought to identify differences in demographic and eating out characteristics on perceived verbal and non-verbal communication. Research design and methodology: This study used a survey method to collect data. The questionnaire asked about previous experience with verbal and non-verbal communication with staff at a counter service restaurant. The study measured degrees of perceived verbal and non-verbal communication. In addition, the effect of verbal and non-verbal communication on satisfaction and revisit intention was measured. The principal results: Results of ANOVA showed significant differences in monthly income on verbal communication and monthly income and budget for dining out on verbal and non-verbal communication. Both verbal and non-verbal communication affected satisfaction and revisit intention significantly with slightly more power of verbal communication than non-verbal communication. Major conclusions: Results of this study suggest that consumers are affected by both verbal and non-verbal communication. Staff communication is critical to increasing consumer satisfaction and revisit intention; hence, training staff in effective communication is necessary.

• The monthly packaging world
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• s.124
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• pp.122-128
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• 2003

• The monthly packaging world
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• s.140
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• pp.64-70
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• 2004

• Journal of Korean Society for Quality Management
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• v.46 no.4
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• pp.797-820
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• 2018

Purpose: It is to seek for an appropriate cost rate analysis methodology of credit card value propositions in Korea. For this issue, it is claimed that methodologies based on probability distribution is more suitable than methodologies based on data-mining. The analysis model constructed for the cost rate estimation is called VCPM model. Methods: The model includes two major variables denoted as S and P. S is monthly credit card usage amount. P stands for the proportion of usage amount at special merchants over the whole monthly usage amount. The distributions assumed for P are positively skewed distributions such as exponential, gamma and lognormal. The major inputs to the model are also derived from S and P, which are E(S) and the aggregate proportion of usage amount at special merchants over the total monthly usage amount. Results: When the credit card's value proposition is general discount, the VCPM model fits well and generates reasonable cost rate(denoted as R). However, it seems that the model does not work well for other types of credit cards. Conclusion: The VCPM model is reliable for calculating cost rate for credit cards with positively skewed distribution of P, which are general discount card. However, another model should be built for cards with other types of distributions of P.

• Journal of Distribution Science
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• v.17 no.3
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• pp.69-83
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• 2019

Purpose - This paper investigates the long term impact of RFID investment on firm value in Korea. We wand to find out why the long term performance of some firm's RFID investment is better than others. To understand the dynamics of the long term returns from RFID investment announcements, we divide our events into groups for each of the independent firm characteristic variable such as investment time period, kind of markets, industries, solvency and growth potential. We composed portfolios based on the RFID investment announcement date for each group and evaluate the monthly abnormal excess returns. Research design, data, and methodology - Based on these calendar-time portfolios, we measure the long term returns from 86 RFID investment announcements of 46 firms from 2003 to 2017. We construct the calendar-time portfolio for 3, 6, 9, 12 months of holding periods. Using the weighted least squares method, we regress the raw monthly returns of the portfolios on the Fama-French model and Carhart(1997) model. As a result, we can get the estimated risk adjusted mean monthly abnormal excess return α_P for each of the calendar-time portfolio. Results - We found that early adopters, large firms, non-manufacturing firms have very significant excess returns. We also found modestly significant excess returns for financially stable firms and slow growing firms. Put together, top managers of the firms which plan to invest RFID should understand the strategic role of RFID adoption and the generalized business process of distribution information technology investment in Korea. Moreover, the findings of this paper provide useful trading strategies to the managers of large funds who are considering on investing in RFID adopting firms. Conclusions - Put together, the results of this paper give us a new insight into how the RFID and IT technology in general and other characteristic factors' interactions affect the long term performance of firms. Using the unbiased estimates of long term returns of the calendar-time portfolios, this paper extends the understandings on short term impact of RFID adoption of existing studies. This paper also extends the current understandings of firm characteristics that affect the long term performance of RFID adopting firms.

• Ocean Science Journal
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• v.43 no.3
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• pp.135-146
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• 2008

The monthly distribution of zooplankton communities in Han River estuary was investigated at two stations from July 1998 to June 1999. Monthly mean abundance of total zooplankton varied remarkably, with the range from 20 $indiv.{\cdot}m^{-3}$ to 19,600 $indiv.{\cdot}m^{-3}$. During the study period, dominant species of zooplankton community were dinoflagellate Noctiluca scintillans, copepods Paracalanus indicus, Paracaanus crassirostris, Acartia hongi, Acartia ohtsukai, and meroplanton cirriped larvae. According to tidal states, relative high abundance occurred at high tide without regard to season. The temporal distribution of abundance implied that the reduced salinity probably limited the zooplankton populations and the fluctuations of salinity were an important factor in the variation of abundance. However, the results of salinity tolerance test shows that the variations in salinity do not directly influence the decrease of abundance. This study shows that the relatively high abundance of zooplankton near high tide seems to be related with the expansion of abundant zooplankton inhabiting Incheon coastal waters through tidal currents.