• 한국산업보건학회지
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• 제31권1호
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• pp.1-12
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• 2021

Objective: The purpose of this study was to contribute to the prevention of occupational diseases through the development of an automatic analysis program for evaluating workers' exposure to hazardous chemical substances. Methods: The authors selected chemical substances that caused occupational disease in Korea and chemical substances that are frequently used in industrial sites as target substances for a GC-MS automatic analysis program. The target substances are organic compounds which can be measured by a passive sampler. The automatic analysis program was studied using various raw data obtained from GC-MS analysis for the target substances. Results: A total of 48 organic compounds that can be measured with a passive sampler were selected as target substances for the GC-MS automatic analysis program. The selected compounds included substances that caused occupational disease, substances related to C1 and D1 in special health examinations, and substances for which work environment measurements have been frequently conducted. The GC-MS automatic analysis program was developed by combining information mainly on retention time and mass spectrum. The GC-MS automatic analysis program is designed to analyze unknown samples by comparing the mass spectrum and retention time of the samples to those of reference materials. To evaluate the stability of the program, samples at about the 30-50% level of OELs were prepared and analyzed with the GC-MS automatic analysis program, resulting in stable results for all 48 organic compounds. Conclusion: An automatic analysis program for a total of 48 organic compounds was developed using a GC-MS system that can analyze organic compounds. Unknown samples that contain the 48 organic compounds can be automatically analyzed by the developed program. It is anticipated that it can contribute to the prevention of occupational diseases through an GC-MS automatic analysis program that can quickly provide workers with information on exposure to chemical substances.

• Journal of Microbiology and Biotechnology
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• 제30권4호
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• pp.533-539
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• 2020

A quantitative real-time polymerase chain reaction (QPCR) was applied to estimate biokinetic coefficients of Clostridium cadaveris and Clostridium sporogenes, which utilize protein as carbon source. Experimental data on changes in peptone concentration and 16S rRNA gene copy numbers of C. cadaveris and C. sporogenes were fitted to model. The fourth-order Runge-Kutta approximation with non-linear least squares analysis was employed to solve the ordinary differential equations to estimate biokinetic coefficients. The maximum specific growth rate (μ_max), half-saturation concentration (K_s), growth yield (Y), and decay coefficient (K_d) of C. cadaveris and C.sporogenes were 0.73 ± 0.05 and 1.35 ± 0.32 h^-1, 6.07 ± 1.52 and 5.67 ± 1.53 g/l, 2.25 ± 0.75 × 10¹⁰ and 7.92 ± 3.71 × 10⁹ copies/g, 0.002 ± 0.003 and 0.002 ± 0.001 h^-1, respectively. The theoretical specific growth rate of C. sporogenes always exceeded that of C. cadaveris at peptone concentration higher than 3.62 g/l. When the influent peptone concentration was 5.0 g/l, the concentration of C.cadaveris gradually decreased to the steady value of 2.9 × 10¹⁰ copies/ml at 4 h Hydraulic retention time (HRT), which indicates a 67.1% reduction of the initial population, but the wash out occurred at HRTs of 1.9 and 3.2 h. The 16S rRNA gene copy numbers of C. sporogenes gradually decreased to steady values ranging from 1.1 × 10¹⁰ to 2.9 × 10¹⁰ copies/ml. C. sporogenes species was predicted to wash out at an HRT of 1.6 h.

• 대한한방내과학회지
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• 제41권6호
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• pp.1030-1051
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• 2020

Objective: This study investigated the measurement interval in the ultrasonographic gastric emptying test for patients with functional dyspepsia (FD) and the correlation between gastric emptying and the findings of various questionnaires. Methods: In total, 119 patients (59 patients with FD and 60 healthy controls) were recruited from July 2018 to June 2020. Gastric volume (GV) and gastric emptying half-time (T1/2) were measured by ultrasonography at fasting and again at 0, 5, 10, 15, 30, 45, 60, 90, and 120 min after meals (apple juice, 500 mL, 224 kcal), and the average half-time (average T1/2) was calculated. Questionnaires on food retention (FRQ), phlegm pattern e (PPQ), cold and heat (CHQ), deficiency and excess (DEQ), and spleen-qi deficiency (SQDQ), stomach qi deficiency pattern (SSDQ), visual analogue scale (VAS), and Nepean dyspepsia index-Korean version (NDI-K) were completed by all participants. The differences in GV and T1/2 were analyzed in participants whose maximal GV occurred at 0 min versus after 0 min. The correlation of the average T1/2 with the questionnaire scores was also analyzed after excluding erroneous data. Results: Patients with FD who took a certain amount of time to reach maximal GV after meals had a greater gastric volume up to about 30 minutes after meals, and the PPQ, DEQ, and NDI-K scores, especially for upper gastrointestinal symptoms and general weakness-related symptoms, showed statistically significant correlations with average T1/2. Conclusions: Ultrasonography can be a quantitative evaluation tool for FD. However, further studies on measurement methods based on FD physiopathology are required.

• Journal of Information Technology Applications and Management
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• 제21권4_spc호
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• pp.415-429
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• 2014

With the advent of smart devices, users are able to connect to each other through the Internet without the constraints of time and space. Because the Internet has become increasingly important to users in their everyday lives, reliance on it has grown. As a result, the number of web sites constantly increases and the competition between these sites becomes more intense. Even those sites that operate successfully struggle to establish new strategies for customer retention and customer development in order to survive. Many companies use various customer information in order to establish marketing strategies based on customer group segmentation A method commonly used to determine the customer groups of individual sites is to infer customer characteristics based on the customers' demographic information. However, such information cannot sufficiently represent the real characteristics of customers. For example, users who have similar demographic characteristics could nonetheless have different interests and, therefore, different buying needs. Hence, in this study, customers' interests are first identified through an analysis of their Internet news inquiry records. This information is then integrated in order to identify each web category. The study then analyzes the possibilities for the practical use of the proposed methodology through its application to actual Internet news inquiry records and web site browsing histories.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.408-409
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• 2009

The memory characteristics of charge trap memory capacitor with high-k materials were investigated. I-V characteristics of the fabricated device with band gap engineered tunneling gate stacks consisted of $SiO_2$, $ZrO_2$, $Al_2O_3$ dielectrics were evaluated and compared with the one consisted of $SiO_2$ tunneling dielectric. The memory capacitor including engineered tunneling dielectrics of ($Al_2O_3/ZrO_2/SiO_2$) shows the fastest PIE speed and long data retention time.

• 한국주거학회논문집
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• 제23권6호
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• pp.31-38
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• 2012

In this paper, we draws tendency of the electricity consumption in residential buildings according to inhabitants Composition types and the level of incomes. it is necessary to reduce energy cost and keep energy security through the electricity demand forecasting and management technology. Progressive social change such as increases of single household, the aging of society, increases in the income level will replace the existing residential electricity demand pattern. However, Only with conventional methods that using only the energy consumption per-unit area are based on Energy final consumption data can not respond to those social and environmental change. To develop electricity demand estimation model that can cope flexibly to changes in the social and environmental, In this paper researches propensity of electricity consumption according to the type of residents configuration, the level of income. First, we typed form of inhabitants in residential that existed in Korea. after that we calculated hourly electricity consumption for each type through National Time-Use Survey performed at the National Statistical Office with considering overlapping behavior. Household appliances and retention standards according to income level is also considered.

• 한국환경과학회지
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• 제26권4호
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• pp.421-432
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• 2017

In this study, we examined the suitability of ten disinfection models for predicting the inactivation of Artemia sp. via single or combined physical and chemical treatments. The effect of Hydraulic Retention Time (HRT) on the inactivation of Artemia sp. was examined experimentally. Disinfection models were fitted to the experimental data by using the GInaFiT plug-in for Microsoft Excel. The inactivation model were evaluated on the basis of RMSE (Root Mean Square Error), SSE (mean Sum Square Error) and $r^2$. An inactivation model with the lowest RMSE, SSE and $r^2$ close to 1 was considered the best. The Weibull+Tail model was found to be the most appropriate for predicting the inactivation of Artemia sp. via electrolytic treatment and electrolytic-ultrasonic combined treatment. The Log-linear+Tail model was the most appropriate for modeling inactivation via homogenization and combined electrolytic-homogenization treatment. The double Weibull disinfection model was the most suitable for the predicting inactivation via ultrasonic treatment.

• 생약학회지
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• 제48권1호
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• pp.77-81
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• 2017

The aim of this study was to investigate a validation method for determination of tricin in Phragmites communis ears. Tricin was isolated with chromatographic methods and used as the standard substances for quantitative analysis. The structural determination was characterized by comparing their NMR spectral data with values reported in the literature. For validation, the specificity, linearity, precision, accuracy, detection limits, and quantification limits of tricin was measured by HPLC. The results show that the specificity was satisfied with retention time and diode array detector (DAD) spectrum by analysis of tricin using HPLC. The limits of detection (LOD) for tricin was 0.84 mg/ml. Recovery of tricin was 98.80~108.22% with R.S.D values less than 2%. Intra-day and inter-day precisions of tricin in P. communis ears were 99.96~100.96% and 99.01~100.40%, respectively. Therefore, application of tricin was validated by an analytical method as major compound in P. communis ears.

• 상하수도학회지
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• 제27권4호
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• pp.495-502
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• 2013

Hydraulic dead-zone and particle removal efficiency in the base frame of a constructed wetland was evaluated with computational fluid dynamics (CFD). The fraction of hydraulic dead-zone was estimated to be 1.2-2.1 % (v/v) and it was attributed to the artificial islands developed in the constructed wetland. Solids deposition rate could be increased with higher hydraulic retention time (HRT, ranged from 2.2 to 4.2 hr) of the wetland and larger particle size (ranged from 10 to $50{\mu}m$) in the influent. Experimental results showed that the volume concentration of the particles smaller than $10{\mu}m$ in diameter was varied from $1.99{\times}10^3{\mu}m^3/ml$ (HRT 12.8 hr) to $3.92{\times}10^3{\mu}m^3/ml$(HRT 2.2 hr) in the influent of the constructed wetland. With the effluent volume concentration data, removal efficiency of those particles was calculated to be 71.2 and 24.7 % when the HRT was 12.8 and 2.2 hr, respectively. Similar trend with the HRT variation could be identified with CFD analysis.

• Bulletin of the Korean Chemical Society
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• 제26권4호
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• pp.569-574
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• 2005

A coupled column liquid chromatography system was applied for the separation of the burnup monitors in spent nuclear fuel sample solutions. A reversed phase column was studied for the adsorption behavior of uranyl ions using alpha-hydroxyisobutyric acid as an eluent and used for the separation of plutonium and uranium. A cation exchange column prepared by coating 1-eicosylsulfate onto the reversed phase column was used for the separation of the lanthanides. In addition, retention of Np was checked with the reversed phase column and cation exchange column, respectively, according to the oxidation states to observe the interference effect for the separation of burnup monitors. This chromatography system showed a great reduction in separation time compared to a conventional anion exchange method. A good agreement from the burnup data was obtained between for this method and a conventional anion exchange method to within 1% of a difference for the spent nuclear fuel samples of about 40 GWD/MTU.