Korohoda, Przemysław
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inżynieria biomedyczna
automatyka, elektronika, elektrotechnika i technologie kosmiczne
automatyka, elektronika, elektrotechnika i technologie kosmiczne
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Item type:Article, Access status: Open Access , Porównanie dwóch metod trójwymiarowego modelowania obrazu za pomocą szeregu Taylora drugiego rzędu(Wydawnictwa AGH, 2008) Korohoda, PrzemysławIn the paper a comparative study of two methods, based on the second order Taylor series, is presented. The 3x3 pixel block modelling is performed with the derived convolution filters. It has been shown, that the 3-D edge detection with Hessian eigenvalues ratio, as suggested in the SIFT algorithm, depends strongly on the computation technique, and therefore an alternative method, also based on the Hessian eigenvalues, has been derived. The study is illustrated with the computational examples.Item type:Article, Access status: Open Access , Porównawcze studium wzorów referencyjnych do wyznaczania przesączania kłębuszkowego nerek na podstawie stężenia cystatyny C(Wydawnictwa AGH, 2008) Korohoda, PrzemysławW artykule sporządzono zestawienie 9 najczęściej spotykanych wzorów do wyznaczania przesączania kłębuszkowego z wyszczególnieniem wybranych cech eksperymentu, w wyniku którego dany wzór został wyznaczony. Zaproponowano metodę ujednolicenia postaci funkcyjnej porównywanych wzorów i z jej pomocą dokonano przekształcenia wszystkich wzorów do postaci nawiązującej bezpośrednio do modelu jednokompartmentowego. Zaprezentowane nietypowe podejście do porównania wzorów na przesączanie kłębuszkowe umożliwiło wyznaczenie nowych wzorów uśredniających, będących rozwiązaniem kompromisowym dla kilku różniących się wzajemnie zależności referencyjnych. Dla kompletności rozważań przeprowadzono także dyskusję porównawczą dwóch najbardziej popularnych zależności na pole powierzchni ciała.Item type:Article, Access status: Open Access , Analiza wrażliwościowa wyznaczanego optymalizacyjnie klirensu komórkowego w modelu dwuprzedziałowym(Wydawnictwa AGH, 2006) Korohoda, PrzemysławThe paper considers the kinetic urea modelling, a tool used in the haemodialysis treatment. The efforts to introduce the two-compartmental model to the practical applications are mitigated by the lack of numerical value for the cellular clearance, Kc, being the crucial parameter of this model. The optimisation procedure, utilising the adjusted model technique to assess the Kc value, should be applied with the knowledge about relevant sensitivity of the resulting values to the changes in the input parameters. The changes that result from the inevitable measurement errors. In the paper a method of evaluating the required sensitivity values is described and a computational example based on the typical values is provided. The obtained results may be used to indicate the input parameters which must be measured with particular care. Application of the described procedure should provide arguments to recognise if the differences between the obtained Kc values result from inaccuracy of the input values or indicate the important phenomena.Item type:Article, Access status: Open Access , Pośredni pomiar bioimpedancji kończyn i tułowia człowieka(Wydawnictwa AGH, 2008) Korohoda, PrzemysławW artykule zaproponowano pośrednią metodę wyznaczania wartości bioimpedancji wybranych segmentów ciała ludzkiego: kończyn i tułowia. Stosując cztery, zlokalizowane na kończynach, prądowo napięciowe punkty pomiarowe i przeprowadzając sześć pomiarów wieloczęstotliwościowych, dla 5 kHz, 50 kHz oraz 100 kHz, pomiędzy tymi punktami, pozyskano dane umożliwiające wyliczenie wartości bioimpedancji dla poszczególnych segmentów. Zaproponowano trzy alternatywne metody wyliczenia i na przykładzie pomiarów przeprowadzonych dla 10 osób porównano wyniki uzyskane dla tych trzech metod.Item type:Article, Access status: Open Access , Zastosowanie sieci neuronowych w modelowaniu kinetycznym mocznika(Wydawnictwa AGH, 2010) Korohoda, Przemysław; Grabska-Chrząstowska, JoannaIn the paper an experiment aimed at verification of the thesis that the multilayer perceptron network may be succesfully used to assess the intercompartmental clearance and the volumes of both compartments has been descibed. The results with satisfactory precision were obtained when data simulating measurements of urea in blood concentration every 10 minutes, accompanied by other numerical data available via measurement where applied. In the experiment a set of ten thousand simulated hemodialysis sessions were utilized. Additionaly, it has been shown, that the high precision of assessed parameters drops rapidly while reducing the number of measurements of the concentration values to 5 and 2 during each session.Item type:Article, Access status: Open Access , Model kompartmentowy w wyznaczaniu przesączania kłębuszkowego nerek za pomocą wstrzykniętej dawki markera(Wydawnictwa AGH, 2009) Korohoda, PrzemysławIn the paper an updated approach to multicompartment modeling used for the renal efficiency assessment is presented. The technique is based on the injection of a dose of the artificial marker. The vital feature of the proposed solution is that instead of the fixed final formulas, typically presented in the literature, the possible computational formulas are described, suited to match the relevant modern tools. The presented approach makes it possible to conduct multiaspect investigations based on simulations. The examples of such research are also provided based on the most common two-compartment model. The described modeling technique should be used to verify the suggested in the literature formulas for the clinical application of the GFR calculations after taking only a single blood sample to measure the marker concentration.Item type:Article, Access status: Open Access , Uproszczony przepływowy model hemodializy - porównanie z klasycznym modelem dwuprzedziałowym(Wydawnictwa AGH, 2009) Korohoda, PrzemysławIn the paper a simplified blood flow model of hemodialysis is sugested, being a modified version of the classical two-compartment model. A method of pseudorandom hemodialysis data generation has been designed to enable relevant comparative study of both models. For such test data, N = 1000, it has been shown that the flow model has very similar capability of modeling the concentration runs, as the classical two-compartment model. For the randomly generated data, the mutual relationship between the crucial model parameters has been shown. Such property makes the convertion between discussed models very simple. However, some differences in the runs obtained from both models were also indicated, which encourages further investigation of the blood-flow models.Item type:Article, Access status: Open Access , Efektywność wykrywania punktów charakterystycznych w obrazach stereoskopowych za pomocą wartości własnych hesjanu(Wydawnictwa AGH, 2009) Korohoda, PrzemysławIn the paper a computational experiment performed for the stereoscopic image pair has been described. The aim of the designed experiment was to investigate the similarities and differences between three methods used to localize the keypoints, basing on the Hessian matrix eigenvalues. The keypoints were obtained for the four-level Gaussian pyramid, and then the ones common for all levels were selected. Afterwards their locations were visually and statistically compared and then the disparity maps were computed. The disparity in that task was calculated with use of the correlation coefficient. The results indicate noticeable differences between theoretically similar techniques utilizing the eigenvalues ratio. The advantegous properties of the third method, based on the difference between eigenvalues, have been confirmed.Item type:Article, Access status: Open Access , Projektowanie banków filtrów wyższych rzędów dla potrzeb transmultipleksacji(Wydawnictwa AGH, 2005) Korohoda, PrzemysławThe author presents a filter design method for transmultiplexation. The synthesis and analysis filters are assumed to be of higher length than the number of transmultiplexed signals. The reasoning based on the matrix description of the up-sampled signals led to formulation of the conditions of perfect reconstruction in such case. The general discussion has been illustrated with a numerical example for 3 signals and filters of assumed length of 5.Item type:Article, Access status: Open Access , Dyskusja możliwości dostosowania opisu algorytmów filtracji adaptacyjnej do wybranej dyskretnej transformacji(Wydawnictwa AGH, 2005) Korohoda, PrzemysławIn the paper the author presents possibility of the commonly known adaptive filters algorithms description adjusted to selected orthogonal discrete transformation. Thus the transformation may be selected to represent given signal in a simpler way. The proposed solution is based on the generalized circular convolution concept, while typically the algorithms make use of the filter impulse response resulting from the Fourier frequency theory. The theory is illustrated with the examples of successful simulations for the Haar, Hadamard, Hartley transformations and DCT-III.