• International journal of advanced smart convergence
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• 제12권3호
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• pp.89-103
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• 2023

Obstructive sleep apnea (OSA) is one of the most prevalent sleep disorders that can lead to serious consequences, including hypertension and/or cardiovascular diseases, if not treated promptly. Continuous positive airway pressure (CPAP) is widely recognized as the most effective treatment for OSA, which needs the proper titration of airway pressure to achieve the most effective treatment results. However, the process of CPAP titration can be time-consuming and cumbersome. There is a growing importance in predicting personalized CPAP pressure before CPAP treatment. The primary objective of this study was to optimize the CPAP titration process for obstructive sleep apnea patients through EEG feature engineering with machine learning techniques. We aimed to identify and utilize the most critical EEG features to forecast key OSA predictive indicators, ultimately facilitating more precise and personalized CPAP treatment strategies. Here, we analyzed 126 OSA patients' PSG datasets before and after the CPAP treatment. We extracted 29 EEG features to predict the features that have high importance on the OSA prediction index which are AHI and SpO2 by applying the Shapley Additive exPlanation (SHAP) method. Through extracted EEG features, we confirmed the six EEG features that had high importance in predicting AHI and SpO2 using XGBoost, Support Vector Machine regression, and Random Forest Regression. By utilizing the predictive capabilities of EEG-derived features for AHI and SpO2, we can better understand and evaluate the condition of patients undergoing CPAP treatment. The ability to predict these key indicators accurately provides more immediate insight into the patient's sleep quality and potential disturbances. This not only ensures the efficiency of the diagnostic process but also provides more tailored and effective treatment approach. Consequently, the integration of EEG analysis into the sleep study protocol has the potential to revolutionize sleep diagnostics, offering a time-saving, and ultimately more effective evaluation for patients with sleep-related disorders.

• Macromolecular Research
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• 제12권6호
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• pp.586-592
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• 2004

Poly(glycidyl methacrylate)-grafted polyethylene microbeads (POPM) presenting epoxy groups were prepared by radiation-induced graft polymerization of glycidyl methacrylate on the polyethylene microbead. The obtained POPM was characterized by IR spectroscopic, X-ray photoelectrons spectroscopy (XPS), scanning electron microscope (SEM), and thermal analyses. Furthermore, the abundance of epoxy groups on the POPM was determined by titration and elemental analysis after amination. The epoxy group content was calculated to be in the range 0.29-0.34 mmol/g when using the titration method, but in the range 0.53-0.59 mmol./g when using elemental analysis (EA) after amination. The lipase was immobilized to the epoxy groups of the POPM under various experi­mental conditions, including changes to the pH and the epoxy group content. The activity of the lipase-immobilized POPM was in the range from 160 to 500 unit/mg-min. The activity of the lipase-immobilized POPM increased upon increasing the epoxy group content. The lipase-immobilized POPM was characterized additionally by SEM, elec­tron spectroscopy for chemical analysis (ESCA), and EA.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• 제2권2호
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• pp.139-148
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• 1998

The charge densities of humic acid and humic extract have been determined by back titration using spectrophotometry as the method of end point detection and several cationic polymers of different charge density(copolymers of acylamide and dimethylaminoethylacrylate and polydiallyidimethylammonium chloride, PDDA), and a cationic indicator o-toluidine blue(o-Tb). The charge densities of humic acid and humic extract obtained depend on the charge densities of cationic polymers used. When the polymers of lower charge density are used, lower apparent charge density values are obtained, but for polymers of high charge density(above 2.5 meq/g), the measured values are almost identical, but also are nearly the same as that obtained for PDDA which has a high charge density(about 6 meq/g). For polymers of lower charge density, it is considered that the optimum dosage does not correspond to 1 :1 charge neutralization between anionic and cationic groups. Polymers of high charge density should be used in order to achieve a complete charge neutralization. As humic acid and humic extract are dissociable acids, their ionization is heavily pH dependent and so higher charge density values are obtaines with increasing pH.

• Bulletin of the Korean Chemical Society
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• 제25권8호
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• pp.1189-1194
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• 2004

The adsorption isotherms of N2 onto the metallic silver treated activated carbon fiber samples after acid treatment are Type I with a small amount of capillary condensation hysteresis. Increasing amount of acid treatment leads to a decrease in SBETs and external surface area. But, micropore volume and average pore diameter are presented in constant regular values with increasing amount of sulfuric acid treatment. SEM observes the surface morphology and crystal grown state of metal on the fiber surface. The results of EDX of Ag-activated carbon fiber pre-treated with acid show the spectra corresponding to almost all samples rich in silver with increasing the amount of acid treated. The FT-IR spectra of Ag-activated carbon fiber show that the acid pre-treatment is consequently associated with the homogeneous dispersion of metal with the increased surface acidity of the activated carbon fiber. The type and quality of oxygen groups are determined with Boehm titration method. From the those results, a positive influence of the acidic groups on the carbon fiber surface by acid treatment is also demonstrated by an increase in the contents of metallic silver with increasing of acidic groups.

• Carbon letters
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• 제7권1호
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• pp.34-41
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• 2006

The objective of this paper is to compare the variation of surface properties by hydrochloric acid pre-treatment and of metallic potassium and their salts loading effect for activated carbon after surfaces transformation by acid. From the results of nitrogen adsorption, each isotherm shows a distinct knee band, which is closely related to the characteristic of microporous carbons with capillary condensation in micropores. In order to present the causes of the differences in surface properties and $S_{BET}$ after the samples were treated with hydrochloric acid, pore structure and surface morphology are investigated by adsorption analysis. X-ray diffraction (XRD) patterns indicate that activated carbons show better performance for metallic potassium and potassium salts by pre-treatment with hydrochloric acid. Scanning electron microscopy (SEM) pictures of potassium/activated carbon particles provide information about the homogeneous distribution of metal or metal complex on the surface. For the chemical composition microanalysis for potassium treatment of the activated carbon pre-treated with hydrochloric acid, samples were analyzed by energy disperse X-ray (EDX). Finally, the type and quality of oxygen groups are determined from the method proposed by Boehm. A positive influence of the acidic groups on the carbon surface by acid treatment is also demonstrated by an increase in the contents of potassium salts with increasing of acidic groups calculated from Boehm titration.

• Bulletin of the Korean Chemical Society
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• 제25권6호
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• pp.819-822
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• 2004

Protonation constants of calix[4]-cyclen-benzo-crown-6, L in 1X$10^{-2}$ M $Bu_4NCF_3SO_3$ in 40% $CH_2Cl_2/CH_3OH$ at $25^{\circ}C$ determined by potentiometric titration are log $K_1$ = 10.91, log $K_2$ = 10.30, log $K_3$ = 6.24 and log $K_4$ = 2.55. Stability constants for the receptor L complexes with Cu(II) and Zn(II) in 1X$10^{-2}$ M $Bu_4NCF_3SO_3$ in 40% $CH_2Cl_2/CH_3OH$ at $25^{\circ}C$ were determined by UV-VIS spectrometric titration. Stability constants of the CuL and ZnL complexes as log $\beta$ are 4.37 and 3.45, respectively. Stabilization energies for protonations of receptor L, derived from ab initio Hartree-Fock method with 6-31G basis set, are ${\Delta}E_1$ = -290.1, ${\Delta}E_2$ = -205.0, ${\Delta}E_3$ = -124.9 and ${\Delta}E_4$ = -26.9 kcal/mol and complexation energy of ZnL complex is -370.3 kcal/mol.

• Bulletin of the Korean Chemical Society
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• 제17권9호
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• pp.820-826
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• 1996

The p2H dependence of the NMR chemical shifts of the proton signals of heme methyl groups and ionizable groups in the vicinity of the heme were investigated. The p2H titration of heme methyl signals in four macroscopic oxidation states by saturation tranfer method was performed in the range between p2H 5.2 and 9.0. While the p2H dependence of the heme methyl resonance in fully oxidized state was small, most resonances in the intermediate oxidation states showed certain shifts. Particularly, methyl resonances of heme 1 (sequential heme numbering) exhibited sharp p2H dependence in acidic range. β-CH2 of the propionate of hemes 1 and 4 were titrated in the range of p2H 4.5-9.0. Only the 6-propionate group of heme 1 was protonated in this p2H range and its titration curve was similar to those of methyl resonances of heme 1 in intermediate oxidation states. Analysis of the microscopic redox potentials showed that they change depending on p2H. The ionizable groups responsible for the p2H dependence of these potentials are 6-propionate of heme 1 in acidic range and His 67 in basic range.

• 공업화학
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• 제9권3호
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• pp.377-382
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• 1998

본 연구는 낮은 활성으로 활용성이 제한된 ${\gamma$-알루미나의 이용을 높이기 위하여 표면을 처리한 알루미나의 계면전기적 특성과 표면활성간의 상관성을 규명하기 위하여 수행되었다. 질산알루미늄을 출발 물질로 하고 암모니아수를 침전제로 사용하여 제조한 알루미나와 황산, 질산, 염산으로 표면 처리한 알루미나를 질량이동법과 site-binding theory를 이용하여 영점전하점을 측정하였다. Amine Titration법과 Hammett 지시약법으로 표면활성점을 구하였다. 전해질에 분산된 알루미나의 계면특성은 전위차적정방법에 의하여 측정된 표면 전하밀도값을 이용하여 분석하였다. 표면전하밀도와 산량의 결과를 이용하여 얻은 ${\gamma$-알루미나의 표면특성과 계면전기적 특성의 상관성은 다음과 같다. 표면을 처리하지 않은 알루미나는 $H_o{\leq}+9.3$인 조건에서 소성온도가 증가함에 따라 산도는 감소한다. 표면처리한 알루미나는 표면을 처리하는 데 사용한 음이온의 농도가 증가하면 표면 이온화상수와 영점전하점은 감소한다. 표면을 처리한 알루미나의 표면전하밀도와 산량은 $H_o{\leq}+4.8$인 조건에서 다음과 같은 상관관계를 갖는다. $SO_4^2-/Al_2O_3:Q_A=-0.172ln(0.0418{\sigma}+1.448)$ $NO_3^-/Al_2O_3:Q_A=-0.024{\sigma}-0.0189$ $Cl^-/Al_2O_3:Q_A=-0.01{\sigma}-0.2006$.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1988년도 한국자동제어학술회의논문집(국내학술편); 한국전력공사연수원, 서울; 21-22 Oct. 1988
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• pp.476-481
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• 1988

In this paper a pH process of a weak acid with a strong base is modeled into a bilinear form, and a self-tuning pH control algorithm which is robust against initial values of solution and disturbances is presented. The control algorithm employs the recursive least square method for the parameter estimation and the generalised minimum variance criterion as the objective function. The computer simulation shows that the tracking of desired pH values is obtained in satisfactory manner regardless of the initial values chosen for the process.

• 한국의류학회지
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• 제20권4호
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• pp.682-689
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• 1996

A preparative method has been proposed for obtaining chitosan products which have a desired degree of deacetylation (DD, %) without much decrease in molecular weight. Deacetylation was prepared by two methods. The method I which was proposed by Domard etc. was that DMSO/thiophenol was used repeatedly only during the deacetylation, the method II was that DMSO/thiophenol was used after the alkali treatment. Then, effective deacetylation was performed by the method ll. To determine the degree of deacetylation, potentiometric titration method was adopted. According to the increase of DD, the viscosity average moleclar weght $(\overline{M\upsilon}$) and the DP of the chitosan products were decreased. The intensity of FT-lR peak appeared at $1655cm^{-1}, which was characteristic peak of amide I (Nacetyl secondary amide group), was gradually decreased with deacetylation. X-ray analysis showed that the lattice-spacing in the chitosan film increased with the degree of deacetylation, but the difference of the transparency of the chitosan products was not diverged significantly.