• 환경위생공학
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• 제5권1호
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• pp.65-72
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• 1990

To study on the water quality of domestic purifier, twenty four samples of clean water by purifier and the raw water(tap water) were tested for biological and physico-chemical examination and were checked for style of purification and the period elapsed after changing of purification medium. The results were as follows; Biological and physico-chemical findings of raw water were not exceeded standard values. Average number of general bacteria,2.coli and pH in clean water were significantly higher than that of raw water(respectively, p<0.01), but mean contents of turbidity, chloride, nitrate and iron in clean water were significantly lower than that of raw water(respectively, p<0.01). In general count of bacteria and E.coli, a half of the clean water of ceramic filter and roverse osmosis style were exceeded standard values for drinking water. All of the pH of the ion exchange style clean water were exceeded standard values. But other findings were within standard values. In average bacterial counts and physico-chemical findings of clean water by purification style of purifier, clean water of ion exchange style purifier were lowest number of general bacteria and not detected in 2. coli. But other items were highest. The longer period elapsed after changing of purification medium were the higher contents of biological and physico-chemical findings of clean water.

• 대한기계학회논문집B
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• 제20권5호
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• pp.1613-1623
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• 1996

In this paper, two discretization methods, hybrid and QUICK, are tested for the Navier-Stokes equations written in general nonorthogonal body fitted coordinates. Comparison is made by calculating two laminar flows at low Reynolds numbers of 10 - 100. One is a two-dimensional channel of gradually expanding cross section and the other is an axisymmetric flow through a circular tube having a circular constriction. Results show that the QUICK scheme results in a numerical solution more accurate than that of hybrid. The QUICK scheme also shows faster convergence for both test cases. As the number of grid points increases, all numerical solutions converge with more oscillation. The number of grid points in the y-direction(cross stream direction) is also shown to play a significant role in the approximation of convection term within separated flow zone.

• International Journal of CAD/CAM
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• 제6권1호
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• pp.139-148
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• 2006

Catmull-Clark subdivision scheme provides a powerful method for building smooth and complex surfaces. But the number of faces in the uniformly refined meshes increases exponentially with respect to subdivision depth. Adaptive tessellation reduces the number of faces needed to yield a smooth approximation to the limit surface and, consequently, makes the rendering process more efficient. In this paper, we present a new adaptive tessellation method for general Catmull-Clark subdivision surfaces. Different from previous control mesh refinement based approaches, which generate approximate meshes that usually do not interpolate the limit surface, the new method is based on direct evaluation of the limit surface to generate an inscribed polyhedron of the limit surface. With explicit evaluation of general Catmull-Clark subdivision surfaces becoming available, the new adaptive tessellation method can precisely measure error for every point of the limit surface. Hence, it has complete control of the accuracy of the tessellation result. Cracks are avoided by using a recursive color marking process to ensure that adjacent patches or subpatches use the same limit surface points in the construction of the shared boundary. The new method performs limit surface evaluation only at points that are needed for the final rendering process. Therefore it is very fast and memory efficient. The new method is presented for the general Catmull-Clark subdivision scheme. But it can be used for any subdivision scheme that has an explicit evaluation method for its limit surface.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제19권2호
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• pp.137-170
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• 2015

In this paper, we propose and analyze three viral infection models with humoral immunity including an eclipse stage of infected cells. The incidence rate of infection is represented by bilinear incidence and saturated incidence in the first and second models, respectively, while it is given by a more general function in the third one. The neutralization rate of viruses is giv0en by bilinear form in the first two models, while it is given by a general function in the third one. For each model, we have derived two threshold parameters, the basic infection reproduction number which determines whether or not a chronic-infection can be established without humoral immunity and the humoral immune response activation number which determines whether or not a chronic-infection can be established with humoral immunity. By constructing suitable Lyapunov functions we have proven the global asymptotic stability of all equilibria of the models. For the third model, we have established a set of conditions on the threshold parameters and on the general functions which are sufficient for the global stability of the equilibria of the model. We have performed some numerical simulations for the third model with specific forms of the incidence and neutralization rates and have shown that the numerical results are consistent with the theoretical results.

• 한국축산시설환경학회지
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• 제19권2호
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• pp.169-176
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• 2013

This survey was conducted to investigate the present conditions of operational management in the 45 animal manure public resource center (APRC) in Korea. The regional distribution, processing capacity per year, capacity of liquid fertilizer storage tank, solid-liquid separation, utilization of facilities, odor reduction facility, on-site odor strength, complained in the community, liquid fertilizer sprayed area, use the Agrix, land application recipe, composting degree, quality management and general grading were surveyed and evaluated. General grading was divided with 5 stages (very good, good, fair, lack and bad). The number of evaluated "very good" animal manure public resource center was 7, and "good" was 5 and more than "fair" was 27. However, the number of evaluated negatively including "lack" and "bad" was occupied as 40% of the 45 animal manure public resource center.

• Nuclear Engineering and Technology
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• 제46권6호
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• pp.773-782
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• 2014

The general path model (GPM) is one approach for performing degradation-based, or Type III, prognostics. The GPM fits a parametric function to the collected observations of a prognostic parameter and extrapolates the fit to a failure threshold. This approach has been successfully applied to a variety of systems when a sufficient number of prognostic parameter observations are available. However, the parametric fit can suffer significantly when few data are available or the data are very noisy. In these instances, it is beneficial to include additional information to influence the fit to conform to a prior belief about the evolution of system degradation. Bayesian statistical approaches have been proposed to include prior information in the form of distributions of expected model parameters. This requires a number of run-to-failure cases with tracked prognostic parameters; these data may not be readily available for many systems. Reliability information and stressor-based (Type I and Type II, respectively) prognostic estimates can provide the necessary prior belief for the GPM. This article presents the Bayesian updating framework to include prior information in the GPM and compares the efficacy of including different information sources on two data sets.

• 한국조리학회지
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• 제14권1호
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• pp.94-106
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• 2008

This study is conducted to explore the cooks' recognition of culinary environment of school feeding among the cooks working for elementary schools, middle schools, and high schools in the Ulsan district. A total of 200 samples were distributed and 185 samples were collected; among them, 182 valid samples were selected for research. Answers were processed by SPSS 12.0. after data coding. As for factor analysis of culinary environment, three factors were extracted, which are general environment, human environment, and facilities equipment environment. It was found that general environment included ventilation(31.5%), temperature (29.0%), humidity(22.1%) in the order of importance; human environment covered cooperation among cooks (28.1%), the number of cooks(25.7%), and professionalism of cooks in the order of importance; facility equipment environment contained the design and layout of facilities and equipment(29.3%), various safety facilities, and safety device(23.3%) in the order of importance. However, a measure for improving work environment, number of cooks, deterioration of equipment, etc. should be considered.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2002년도 봄 학술발표회 논문집
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• pp.257-264
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• 2002

This study presents a life-cycle cost (LCC) effectiveness of a concrete with lightweight aggregate. A number of researchers have made their efforts to develop a lightweight concrete, since it is difficult to apply conventional concrete using general aggregate to heavy self-weight structures such as long span bridges. In this study, an optimum design for minimizing the life-cycle cost of concrete slab bridges is performed to evaluate the life cycle cost effectiveness of the lightweight concrete relative to conventional one from the standpoint of the value engineering. The data of physical properties for new concrete can be obtained from basic experimental researches. The material properties of conventional one are acquired by various reports. This study presents a LCC effectiveness of newly developed concrete, which is made by artificial lightweight aggregate. A number of researchers have made their efforts to develop a lightweight concrete, since it is difficult to apply conventional concrete using general aggregate to heavy self-weight structures such as long span bridges. From the results of the numerical investigation, it may be positively stated that the new concrete lead to, the longer span length, the more economical slab bridges compared with structures using general concrete.

• 한국병원경영학회지
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• 제13권4호
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• pp.1-26
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• 2008

This study examines the statistical relationship between medical specialists and managerial performance, using regression analysis with the number of medical specialists per 100 beds as the independent variable and the managerial performance index as the dependent variable. Managerial performance index incorporated the number of out-patients per specialist, the number of in-patients per specialist, the volume of revenue per specialist, the number of beds per specialist, and the average length of stay. To compare different groups of hospitals, dummy variable was applied to five groups of hospitals according to size: 100-299 beds, 300-599 beds, 600-899 beds, 900-1199 beds, and more than 1200 beds. The data consisted of 181 general hospitals with more than 100 beds, which included 28 public hospitals, 73 corporate hospitals, 64 university hospitals and 16 private hospitals. Of those, 87 hospitals were located in big cities and 94 hospitals in medium to small cities. This study used hospitals from the Korean Hospital Association, and data published in 2004. The collected data sample was analyzed using the SPSSWIN 12.0 version, and the study hypothesis was tested using regression analysis. The findings of this study are summarized as follows: Hypothesis 1 predicting a negative effect of the number of medical specialists on the number of out-patients per specialist was supported with statistical significance. The analysis of dummy variable showed causality in all the hospital groups larger than the group of 100-299 beds. Hypothesis 2 predicting a negative effect of the number of medical specialists on the number of in-patients per specialist was supported with statistical significance. The analysis of dummy variable showed causality in the hospital group of 300-599 beds when compared to the group of 100-299 beds. Hypothesis 3 predicting a negative effect of the number of medical specialists on the volume of revenue per specialist was not supported. However, the analysis of dummy variable showed that the volume of revenue per specialist increased in the hospital groups of 600-899 beds, 900-1199 beds, and over 1200 beds, when compared to the group of 100-299 beds. Hypothesis 4 predicting a negative effect of the number of medical specialists on the average length of stay was supported with statistical significance. The analysis of dummy variable showed causality in the hospital group of 300-599 beds, when compared to the group of 100-299 beds. Results of this study show that the number of the medical specialists per 100 beds is an important factor in hospital managerial performance. Most hospitals have tried to retain as many medical specialists as possible to keep the number of patients stable, to ensure adequate revenue, and to maintain efficient managerial performance. Especially, the big hospitals with greater number of beds and medical specialists have shown greater revenue per medical specialist despite the smaller number of patients per medical specialist. Findings of this study explains why hospitals in Korea are getting bigger.

• Journal of applied mathematics & informatics
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• 제32권1_2호
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• pp.255-266
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• 2014

For a connected graph G = (V,E) of order at least two, a set S of vertices of G is a monophonic set of G if each vertex v of G lies on an x - y monophonic path for some elements x and y in S. The minimum cardinality of a monophonic set of G is the monophonic number of G, denoted by m(G). Certain general properties satisfied by the monophonic sets are studied. Graphs G of order p with m(G) = 2 or p or p - 1 are characterized. For every pair a, b of positive integers with $2{\leq}a{\leq}b$, there is a connected graph G with m(G) = a and g(G) = b, where g(G) is the geodetic number of G. Also we study how the monophonic number of a graph is affected when pendant edges are added to the graph.