• International Journal of Naval Architecture and Ocean Engineering
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• v.9 no.6
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• pp.655-667
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• 2017

The results of a numerical study on the performance of a propeller operating near a free surface are presented. The numerical simulations were performed for the various advance coefficients and the submergence depths of the model propeller. The effects of the model propeller size were investigated using two different model propeller sizes for all cases. The wave pattern of the free surface and the flow structure around the propeller as well as the hydrodynamic characteristics of the propeller were investigated through simulation results. The thrust and torque fluctuated and the trajectory of the tip vortex was distorted due to the interaction with the free surface. The wave pattern of the free surface was related to the tip vortex of the propeller. The decreases in thrust and torque at the small model propeller were greater than those of the large model propeller. The reduction rate of the thrust and torque increased with the advance coefficient.

• Architectural research
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• v.8 no.1
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• pp.69-76
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• 2006

The purpose of this study is to suggest policies to improve the price escalation system in a construction contract through a Policy Delphi technique. The Delphi, including two times questionnaires and a group discussion, was conducted by joining 14 experts. Also, the escalation provisions of various countries were examined. Results of the Delphi showed that the minimum fluctuation rate for price escalation was desirable at a level of 3%. To compute the fluctuation rate, calculating the price fluctuation of overall articles was more desirable than using price indices. A bidding date was more reasonable as the initial date of change in price. Losses caused by price change should be shared between contractor and owner; therefore a deduction rate should be introduced in price escalation. Meanwhile, overhead and profit should be adjusted in proportion to the fluctuation rate; but advance payment or the delayed construction amount should be deducted from the adjusted amount.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.6
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• pp.689-699
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• 2007

The accurate estimation of water pipe deterioration is indispensable to prevent pipe breakage and manage in advance. In this study, corrosion of water pipe is adopted, which is relatively underestimated although it takes most part of deteriorating pipeline. Predicting corrosion rate and corrosion depth of a pipe can make an increase the life span of the pipeline, which is laid under the ground according to characteristics of soil and water corrosion. For the purpose, mathematical models that can presume nominal depth through estimation of pit corrosion and corrosion rate is introduced. As comparison of results with conventional methods in other foreign countries, it is evaluated that the external corrosion depth is estimated less than the models, proposed by other researchers and the internal corrosion rate was processed faster than the external corrosion rate.

• East Asian mathematical journal
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• v.39 no.5
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• pp.493-503
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• 2023

Tendency prediction of daily confirmed cases is an important issue for public health authorities. To protect the tendency, we estimate the transmission rate of stochastic SEIR model for COVID-19 in Korea using particle Markov chain Monte Carlo method. The results show that the increasing and decreasing tendency of estimated transmission rate appear one or two days in advance compared to daily incidence cases, and as time evolves the standard deviation of the estimates of transmission rate reduces. Since ten months have passed since the first incident case of COVID-19 in Korea, we expect to forecast the tendency of daily confirmed cases for the next one or two days more accurately using our method.

• The Korean Journal of Archival Studies
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• no.68
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• pp.73-105
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• 2021

The aim of this study was to investigate the current state of operation of information disclosure system in Busan Metropolitan Police Agency and to suggest recommendations for improvement. To achieve this goal, this study quantitatively analyzed the data on information disclosure claims (2010~2020.6), appeal cases (2010~2020.6), the disclosure rate of original documents (2014~2019) and so on. Furthermore, it examined how and how much information is announced in advance through the agency's homepage and the information disclosure portal site. Results show that the agency has various problems regarding information disclosure including the high rate of transferring information to other institutions, the low disclosure rate of original documents, the high rate of information released publicly only after an administrative appeal, a small number of information announced in advance, and a not user-friendly website. To solve these problems, this study proposes providing accurate information about the scope of information the agency and other related institutions own, expanding the disclosure of original documents, discovering more information to announce in advance, and enhancing the usability of the website.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.7B
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• pp.685-696
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• 2004

Real-time multimedia applications that require large amount of bandwidth need resource reservation before starting service for providing the QoS(i.e., Quality of Service). To reserve resources in advance, each reservation request has to notify its expectation on the required amount of resources and service duration. Using this information, a resource manager can schedule advance reservations. However, most existing resource management systems are adopting straightforward call admission control process (i.e., only immediate reservation) by checking currently available resources without considering the service duration. Hence, the resource management system that supports advance reservation has to manage confliction caused by indefinite service duration of immediate reservation. Even though the separation of resource pool according to type of reservation can prevent the confliction, it causes low resource utilization. In this paper, we propose an effective resource management scheme that supports both immediate and advance reservations by sharing resources dynamically. Using network cost function, the proposed scheme determines and adaptively adjusts resource boundary according to the confliction rate by varying weight parameters. And also, we define user utility function to quantify user satisfaction based on how well the reserved resource is guaranteed during service time. Simulation results using NS-2 network simulator show that the proposed scheme can achieve better resource utilization with preferable QoS than other schemes like static resource partitioning.

• Korean Journal of Veterinary Service
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• v.17 no.3
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• pp.198-207
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• 1994

4, 919 Samples of the slaughtered cattle(female) were investigated the abattoir in southern Kangwon to reveal the incidence rates of abdominal fat necrosis from June to December 1993. The results obtained were summarized as follows ; 1. The incidence rate of abdominal fat necrosis investigated from 4, 919 samples was 4.39%. 2. It revealed that the incidence rate of abdominal fat necrosis increased gradually with the advance in the age, 2.5% in below 5 years, 6.0% in 6 years, 7.2% in 7 years, 8.5% in 7 years, 8.9% in older than 9 years and that incidence rate of the sites of lesion, pericolonic fat 84.7%, perirectumic fat 48.6%, perirenal fat 37.9%. mesenteric fat 24.0%, others 7.8%. 3. The size of necrotic fat were $2{\times}3cm{\sim}10{\sim}18{\times}15{\sim}25cm$ in average and color was yellowish white or milk white.

• Asia pacific journal of information systems
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• v.4 no.1
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• pp.3-31
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• 1994

Potential employers considering locations for production or service facilities typically equire detailed advance knowledge of the wages they will be expected to offer for workers in various occupational categories. The State of Missouri s Department of Labor and Industrial Relations is often contacted by organizations requesting such information. The current wage rate survey approach, initiated in 1988, allows the Department to predict an appropriate wage rate for a given occupation in certain counties, adjusted for changes in the Consumer Price Index (CPI). However, both Department employees and firms have indicated that improved prediction responsiveness and accuracy are desirable. A major deficiency of the current approach is its inability to predict wages for unsurveyed counties. This paper describes a knowledge-based system (KBS), currently in the prototype testing stage, that is expected to supplement the wage rate survey in the near future.

• Journal of Fisheries and Marine Sciences Education
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• v.27 no.4
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• pp.1092-1098
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• 2015

Fishing population has been increasing with national income improvement and the five-day workweek in Korea. Recently commercial fishing facilities like pay fishing pond are emerging as demand of saltwater fishing increases, unlike the past when inland fishing was prominent. In order to do businesses, economic analysis should be done in advance. This study aimed to make an Economic analysis of Uljin pay-fishing place by estimating the cost and benefit, and calculating the rate of economic return. The results show the Uljin pay-fishing place's net present value of 3.5 billion won, internal rate of return of 14%, and benefit cost ratio of 1.16 at 5.5% social discount rate.

• Journal of Ocean Engineering and Technology
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• v.35 no.2
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• pp.99-112
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• 2021

The prediction of maneuverability is very important in the design process of an underwater vehicle. In this study, we predicted the steady turning ability of a symmetrical underwater vehicle while considering interactions between the yaw rate and drift/rudder angle through a simulation-based methodology. First, the hydrodynamic force and moment, including coupled derivatives, were obtained by computational fluid dynamics (CFD) simulations. The feasibility of CFD results were verified by comparing static drift/rudder simulations to vertical planar motion mechanism (VPMM) tests. Turning motion simulations were then performed by solving 2-degree-of-freedom (DOF) equations with CFD data. The turning radius, drift angle, advance, and tactical diameter were calculated. The results show good agreement with sea trial data and the effects on the turning characteristics of coupled interaction terms, especially between the yaw rate and drift angle.