• Journal of applied mathematics & informatics
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• v.13 no.1_2
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• pp.53-65
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• 2003

Here we present a study of small-amplitude, shallow water waves on sloping beds. The beds considered in this analysis are linear and quadratic in nature. First we start with stating the relevant governing equations and boundary conditions for the theory of water waves. Once the complete prescription of the water-wave problem is available based on some assumptions (like inviscid, irrotational flow), we normalize it by introducing a suitable set of non-dimensional variables and then we scale the variables with respect to the amplitude parameter. This helps us to characterize the various types of approximation. In the process, a summary of equations that represent different approximations of the water-wave problem is stated. All the relevant equations are presented in rectangular Cartesian coordinates. Then we derive the equations and boundary conditions for small-amplitude and shallow water waves. Two specific types of bed are considered for our calculations. One is a bed with constant slope and the other bed has a quadratic form of surface. These are solved by using separation of variables method.

• Advances in environmental research
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• v.7 no.1
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• pp.29-37
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• 2018

A simple mathematical model for predicting fixed bed adsorption dynamics is described. The model is characterized by a linear adsorption isotherm and a linear driving force expression for mass transfer. Its analytic solution can be approximated with an algebraic equation in closed form which is easily evaluated by spreadsheet computation. To demonstrate one application of the fixed bed model, a previously published adsorption system is used as a case study in this work. The adsorption system examined here describes chromium breakthrough in a fixed bed adsorber packed with imidazole functionalized adsorbent particles and is characterized by a nonlinear adsorption isotherm. However, the equilibrium behavior of the fixed bed adsorber is in essence governed by a linear adsorption isotherm due to the use of a low influent chromium concentration. It is shown that chromium breakthrough is predicted reasonably well by the fixed bed model. The model's parameters can be easily extracted from independent batch experiments. The proposed modeling approach is very simple and rapid, and only Excel is used for computation.

• Journal of applied mathematics & informatics
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• v.20 no.1_2
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• pp.197-208
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• 2006

This paper deals with the exact solution of surface gravity waves in an ocean with irregular bed topography. In order to obtain water surface elevation and run-up of infra-gravity waves when the bed is either wavy or exponential, closed form solutions are obtained. Numerical computations indicate that when solitary wave or sinusoidal wave conditions are applied at the boundary, water surface elevation attains near Gaussian profile.

• Structural Engineering and Mechanics
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• v.27 no.1
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• pp.33-48
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• 2007

An Articulated tower is one of the compliant offshore structures connected to the sea-bed through a universal joint which is the most vulnerable location of the tower that sustains the randomly fluctuating shear stresses. The time history response of the bottom hinge shear is obtained and presented in the spectral form. The fatigue and fracture reliability assessment of the tower joint against randomly varying shear stresses have been carried out. Non-linear limit state functions are derived in terms of important random variables using S-N curve and fracture mechanics approaches. Advanced First Order Reliability Method is used for reliability assessment. Sensitivity analysis shows the influence of various variables on the hinge safety. Fatigue life estimation has been made using probabilistic approach.

• Journal of the Korean Chemical Society
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• v.36 no.3
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• pp.393-404
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• 1992

The response properties of continuous automated system using an enzyme reactor for determination of urea were investigated. The enzyme reactor was constructed to packed-bed form which filled with nylon-6 beads (42∼48 mesh), which immobilized urease with glutaraldehyde, in teflon tube (2 mm I.D., 20 cm length). The system was composed of the enzyme reactor, gas dialyzer, and tublar PVC-nonactin membrane ammonium ion-selective electrode as an indicator electrode in serial order. The response characteristics of this system were as follows. That is, the concentration range of linear response, slope of linear response, detection limit, and conversion percentage were $5.5{\times}10^{-6}$∼$2.4{\times}10^{-3}M$, 57.8 mV/decade, $1.5{\times}10^{-6}$, and 80.8%, respectively. The optimum buffer and life time of urease reactor were 0.01M Tris-HCl buffer solution (pH 7.0∼7.8) and 0.01M phosphate buffer solution (pH 6.9∼7.5) and about 150 days, respectively. And the urease reactor had no interferences of the other physiological materials.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.7
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• pp.98-105
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• 2001

The machining accuracy is affected by geometric, volumetric errors of the machine tools. To improve the product quality, we need to enhance the machining accuracy of the machine tools. To this point of view, measurement and inspection of finished part as error analysis of machine tools ahas been studied for last several decades. This paper suggests the enhancement method of machining accuracy for precision machining of high quality metal reflection mirror or optics lens, etc. In this paper, we study 1) the compensation of linear pitch error with NC controller compensation function using laser interferometer measurement, 2) the method for enhancing the accuracy of NC milling machining by modeling and compensation of volumetric error, 3) the spherical surface manufacturing by modeling and compensation of volumetric error of the machine tool, 4) the system development of OMM without detaching work piece from a bed of machine tool after working, 5) the generation of the finished part profile by OMM. Furthermore, the output of OMM is compared with that of CMM, and verified the feasibility of the measurement system.

• Research in Community and Public Health Nursing
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• v.10 no.1
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• pp.70-79
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• 1999

This study attempts to encourage the development of a rehabilitation delivery system as a substitute service for hospitalization such as a community based intermediate facility or home health care. We need substitute services for hospitalization to curtail the length of stay for inpatients due to car accidents. It focused on developing an estimation for early discharge based on a detailed statement of treatment from medical records of 109 inpatients who were hospitalized at General Hospital in 1997. This study has three specific purposes: First, to find the mean length of stay and mean medical expenditure. Second, to estimate the mean of early discharge from the mean length of stay. Third, to analyize the income effect per bed from early discharge. In order to analyze the length of stay and medical expenditure of inpatients the author conducted a micro and macro-analysis with medical expenditure records. To estimate the early discharge we examined with a group of 4 experts decreases in the amount of treatment after surgery, in treatments, in tests, in drug methods. We also looked their vital signs, the start of ROM exercise, the time removel, a patient's visitations, and possible stable conditions. In addition to identifing the income effect due to an early discharge, the data was analyzed by an SPSS-PC for windows and Excell program with a regression analysis model. The research findings are as follows: First, the mean length of stay was 47.56 days, but the mean length of stay due to early discharge was 32.26 days. The estimation of early discharge days was shown to depend on the length of stay. The longer the length of stay, the longer the length before discharge. For example, if the patient stayed under 14 days the mean length of stay was 7.09 while an early discharge was 6.39, whereas if the mean length of stay was 155.73, the early discharge time was 107.43. The mean medical expenditure per day of car accident patients was found to be 169,085 Won, whereas the mean medical expenditure per day was shown to be in a negative linear form according to the length of stay. That is the mean expenditure for under 14 days of stay was 303,015 Won and the period of the hospitalization of 15 days to 29 days was 170,338 Won and those of 30 days to 59 days was 113,333 Won. The estimation of the income effect due to being discharged 16 days was around 2,350,000 Won with a regression analysis model. However, this does not show the real benefits from an early discharge, but only the income increasing amount without considering prime medical cost at a general hospital. Therefore, we need further analysis on cost containments and benefits incending turn over rates and medical prime costs. From these research findings, the following suggestions have been drawn, we need to develop strategies on a rehabilitation delivery system focused on consumers for the 21st century. Varions intermediate facilities and home health care should be developed in the community as a substitute for shortening the length of stay in hospitals. In home health care cases, patients who want rehabilitation services as a substitute for hospitalization in cooperation with private health insurance companies might be available immediately.