• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• 제19권9호
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• pp.640-646
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• 2007

The cooling heat transfer coefficient of $CO_2$ (R-744) for tube and coil diameter (CD), inclined angle of tube and coil pitch of inclined helical coil type copper tubes were investigated experimentally. The main components of the refrigerant loop are a receiver, a variable-speed pump, a mass flow meter, a pre-heater and a inclined helical coil type gas cooler (test section). The test section consists of a smooth copper tube of 2.45 and 4.55 mm inner diameter (ID). The refrigerant mass flukes were varied from 200 to 800 [$kg/m^2s$] and the inlet pressures of gas cooler were 7.5 to 10.0 [MPa]. The heat transfer coefficients of $CO_2$ in inclined helical coil tube with 2.45 mm ID are $5{\sim}10.3%$ higher than those of 4.55 mm. The heat transfer coefficients of 41.35 mm CD are $8{\sim}32.4%$ higher than those of 26.75 mm CD. Comparison between $45^{\circ}\;and\;90^{\circ}$ of coil angle, the heat transfer coefficients of $45^{\circ}$ are higher than those of $90^{\circ}$. For coil pitch of gas cooler, the heat transfer coefficients of inclined helical coil gas cooler with coil pitch of 5 mm are similar to those of 10 and 15 mm.

• Journal of Environmental Science International
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• 제25권5호
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• pp.737-744
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• 2016

For electrolysis process using an insoluble electrode, electrochemical performance was greatly affected by the manufacturing method and procedure, such as the firing temperature, pre-treatment, type of precursor solution, coating method, electrode material, etc. Components of the electrode therein is one of the most important factors in electrochemical reaction. To achieve such characteristics, a appropriate ratio of the electrode material should be carefully chosen. The aim of this research was to apply experimental design method in the optimization of electrode component for the maximum generation of oxidants in electrochemical oxidation process. Mixture design, especially expanded simplex lattice design, in DOME (design of mixture experiments) with Design Expert - commercial software - was used to analyze the data. Analysis of variance (ANOVA) showed a high coefficient of determination ($R^2$) value of 0.9470, thus ensuring a satisfactory adjustment of the $3^{rd}$ order special cubic regression model with the experimental data. The application of response surface methodology (RSM) yielded the following regression equation, which is an empirical relationship between the TRO generation concentration and independent variables(mol ratio of 3 electrode components) in a real unit: TRO generation concentration $(mg/L)=TRO\;conc.=98.25{\times}[Ir]+49.71{\times}[Sn]+95.29{\times}[Sb]-16.91{\times}[Ir]{\times}[Sn]-29.47{\times}[Ir]{\times}[Sb]-22.65{\times}[Sn]{\times}[Sb]+703.19{\times}[Ir]{\times}[Sn]{\times}[Sb]$. The optimized formulation of the 3 component electrode for an high TRO (total residual oxidants) generation was acquired at mol ratio of Ir 0.406, Sn 0.210, Sb 0.384 (desirability d value, 1).

• Journal of the Korean Institute of Gas
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• 제11권3호
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• pp.1-6
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• 2007

The heat transfer coefficient and pressure drop during gas cooling process of $CO_2$ (R-744) in inclined helical coil copper tubes were investigated experimentally. The main components of the refrigerant loop are a receiver, a variable-speed pump, a mass flow meter, a pre-heater and a inclined helical coil type gas cooler (test section). The test section consists of a smooth copper tube, which is specified as the inner diameter of 4.55 mm. The refrigerant mass fluxes were varied from 200 to $600kg/m^2s$ and the inlet pressures of gas cooler were done 7.5 to 10.0 (MPa). The heat transfer coefficients of $CO_2$ in the inclined helical coil tubes increase with the increase of mass flux and gas cooling pressure of $CO_2$. The pressure drop of $CO_2$ in the gas cooler shows relatively good coincidence with those predicted by Ito's correlation developed for single-phase in a helical coil tube. The local heat transfer coefficient of $CO_2$ is well coincident with the correlation by Pitla et al. However, at the region near pseudo-critical temperature, the experiments indicate higher values than the Pitla et al. correlation.

• Hip & pelvis
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• 제30권4호
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• pp.219-225
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• 2018

Purpose: Ischiofemoral impingement (IFI)-primarily diagnosed by magnetic resonance imaging (MRI)-is an easily overlooked disease due to its low incidence. The purpose of this study was to evaluate the usefulness of false profile view as a screening test for IFI. Materials and Methods: Fifty-eight patients diagnosed with IFI between June 2013 and July 2017 were enrolled in this retrospective study. A control group (n=58) with matching propensity scores (age, gender, and body mass index) were also included. Ischiofemoral space (IFS) was measured as the shortest distance between the lateral cortex of the ischium and the medial cortex of lesser trochanter in weight bearing hip anteroposterior (AP) view and false profile view. MRI was used to measure IFS and quadratus femoris space (QFS). The receiver operating characteristics (ROC), area under the ROC curve (AUC) and cutoff point of the IFS were measured by false profile images, and the correlation between the IFS and QFS was analyzed using the MRI scans. Results: In the false profile view and hip AP view, patients with IFI had significantly decreased IFS (P<0.01). In the false profile view, ROC AUC (0.967) was higher than in the hip AP view (0.841). Cutoff value for differential diagnosis of IFI in the false profile view was 10.3 mm (sensitivity, 88.2%; specificity, 88.4%). IFS correlated with IFS (r=0.744) QFS (0.740) in MRI and IFS (0.621) in hip AP view (P<0.01). Conclusion: IFS on false profile view can be used as a screening tool for potential IFI.

• Women's Health Nursing
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• 제8권2호
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• pp.301-313
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• 2002

The purpose of this study was to develop the frame for standardized manual for Sanhujoriwon by finding out the status of the management of women & newborn in Sanhujoriwon, like postpartum care center. The subjects were 95 staffs of 22 Sanhujoriwon agreed on oral consent, in Seoul and Bundang, Korea. Data were collected from Sep. 15 to Oct. 24, 2001. The instrument used for this study was a structured questionnaire consisted of 16 items of general characteristics & educational characteristics about postpartum care, 31 items of degree of management of women's postpartum care (Cronbach's $\alpha$.93 ), 24 items of degree of management of newborn's care(Cronbach's $\alpha$.94 ), 10 items of methods of management of women's postpartum care, 8 items of methods management of newborn's care. The data were analyzed by the SPSS/PC+ program using frequency, percentage, mean, standard deviation, t-test, ANOVA and Pearson correlation coefficient. The results of the study were as follows ; 1. The mean of the degree of management for postpartum women was 4.1. The mean score for the degree of management of general postpartum care for women was 4.00 & traditional postpartum care(Sanhujori) was 4.20. The degree of management of traditional postpartum care was higher than general postpartum care for women. 2. The degree of management for newborn : The mean score for the degree of management of newborn was 4.37. 3.There was a strong positive correlation between general postpartum care and traditional postpartum care($r=.744^{**}$), and postpartum mother care and newborn care($r=.798^{**}$). 4.The basic frame for the management of the women and newborn in Sanhujoriwon. 1) For women: Integrated postpartal care Physical management : Vital sign & BP check, contraction of uterus, form and amount of lochia, management of personal hygiene, management of breast & breast-feeding, management of postpartum exercise, prevention of infection, symptom & sign of high risk and prevention & management of high risk condition; Emotional-psychological management: assessment and management of mother-baby attachment, emotional state; Educational management : education of vaccination schedule, urinary incontinence, rearing infant, breast-feeding ; and Environmental management : temperature, humidity, disinfection, cleaning, light, infection control integrated with 6 principles of Sanhujori. 2) For newborn Physical management : check of vital sign, management of umbilical cord, jaundice, prevention of infection, management of diaper rash; Emotional-psychological management : assessment of sleep, crying, activity, response of mother-baby attachment; and Environmental management : temperature, humidity, disinfection, cleaning, light, infection control integrated with 6 principles of Sanhujori. In conclusion Sanhujoriwon must be health care center for the postpartum women and newborn. Therefore, the establishment of various laws and regulations in such a way to meet the realistic needs of Sanhujoriwon as a health care center for women and infants future health should be done. The standardized management manual based on the results is absolutely required above all.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제29권1호
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• pp.5-13
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• 2003

The purpose of this study is to determine the value of serum concentration of C-reactive protein(CRP) in comparison with ESR and leukocyte as the tools for diagnosis and follow-up study of infection. For this study, thirty-one patients with head and neck infection and thirty-two patients performed the orthognathic surgery were selected for experimental and control groups each other. we analyzed the blood sample daily to measure CRP, ESR and leukocytosis. The results of this study are as the following : 1. Serum C-Reactive Protein levels in the experimental group were higher than control group and the pattern of CRP changes continued to decline in both groups(P<0.001). 2. ESR changes in both groups were scattered without any special pattern. 3. Correlation between CRP and Leukocyte was higher than others(r=0.664, P<0.01). 4. In the Receiver Operating Characteristic(ROC) Curve of experimental group, rapid increase of CRP curve and Area under the curve(AUC) value, 0.774, indicate the high accuracy of estimation. 5. In experimental group, sensitivity of CRP, ESR, and Leukocytosis on recovery day were 83%, 17% and 71%. Based on the results of this study, we could conclude that determination of CRP is more useful method to diagnosis and follow-up study of infection than other commonly used variables in oral and maxillofacial region.

• Journal of Mushroom
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• 제17권3호
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• pp.136-143
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• 2019

In this study, we analyze the antioxidant and anti-inflammatory activities of various extracts of Cryptoporus volvatus. Three extracts were prepared using hot-water, 70% ethanol, and 70% methanol. Compared to the hot-water and 70% methanol extracts, the 70% C. volvatus ethanol extracts showed significantly higher DPPH radical scavenging activities (76.1%), nitrite scavenging activities (29.5%), and total polyphenol content (9.17 mg GAE/g). The DPPH radical and nitrite scavenging activities of C. volvatus both correlated significantly with the total polyphenol content. The Pearson's correlation coefficient of DPPH radical and nitrite scavenging activities with total polyphenol content were r = 0.744 (p<0.05) and r = 0.921 (p<0.01), respectively. To test their anti-inflammatory effects, nitric oxide production and cell viability were measured by performing nitric oxide (NO) and MTT assays on lipopolysaccharide-treated RAW 264.7 cells. The NO production levels of the 70% ethanol extract-treated cells were slightly lower than those of the others. In our MTT assay, the hot-water extracts showed higher cell viabilities (81.4%) than those of 70% ethanol and 70% methanol extracts. The ${\beta}$-glucan content of C. volvatus was 37.8%. From the results of this study, it is suggested that C. volvatus, an easily accessible wild mushroom, has potential to be used in the development of medicines, cosmetics, and functional health foods.

• Transactions of the Korean hydrogen and new energy society
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• 제33권1호
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• pp.95-104
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• 2022

Micro hydropower is a readily available renewable energy source that can be harvested utilizing hydrokinetic turbines from shallow water canals, irrigation and industrial channel flows, and run-off river stream flows. These sources generally have low head (<1 m) and low velocity which makes it difficult to harvest energy using conventional turbines. A horizontal-axis screw turbine was designed and numerically tested to extract power from such low-head water sources. The 3-bladed screw-type turbine is placed horizontally perpendicular to the incoming flow, partially submerged in a narrow water channel at no-head condition. The turbine hydraulic performances were studied using Computational Fluid Dynamics models. Turbine design parameters such as the shroud diameter, the hub-to-shroud ratios, and the submerged depths were obtained through a steady-state parametric study. The resulting turbine configuration was then tested by solving the unsteady multiphase free-surface equations mimicking an actual open channel flow scenario. The turbine performance in the shallow channel were studied for various Tip Speed Ratios (TSR). The highest power coefficient was obtained at a TSR of 0.3. The turbine was then scaled-up to test its performance on a real site condition at a head of 0.3 m. The highest power coefficient obtained was 0.18. Several losses were observed in the 3-bladed turbine design and to minimize losses, the number of blades were increased to five. The power coefficient improved by 236% for a 5-bladed screw turbine. The fluid losses were minimized by increasing the blade surface area submerged in water. The turbine performance was increased by 74.4% after dipping the turbine to a bottom wall clearance of 30 cm from 60 cm. The final output of the novel horizontal-axis screw turbine showed a 2.83 kW power output at a power coefficient of 0.63. The turbine is expected to produce 18,744 kWh/year of electricity. The design feasibility test of the turbine showed promising results to harvest energy from small hydropower sources.

• Journal of Korean Society for Geospatial Information Science
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• 제21권4호
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• pp.73-81
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• 2013

Ordinary least squares (OLS) regression is the primary statistical method in previous studies for vegetation distribution patterns in relation to landform. However, this global regression lacks the ability to uncover some local-specific relationships and spatial autocorrelation in model residuals. This study employed geographically weighted regression (GWR) to examine the spatially varying relationships between NDVI (Normalized Difference Vegetation Index) patterns and changing trends of landform (elevation, slope) and solar intensity (insolation and duration of sunshine) in Mt Geum-gang of North-Korea. Results denoted that GWR was more powerful than OLS in interpreting relationships between NDVI patterns and landform/solar intensity, since GWR was characterized by higher adjusted R2, and reduced spatial autocorrelations in model residuals. Unlike OLS regression, GWR allowed the coefficients of explanatory variables to differ by locality by giving relatively more weight to NDVI patterns which are affected by local landform and solar factors. The strength of the regression relationships in the GWR increased significantly, by showing regression coefficient of higher than 70% (0.744) in the southern ridge of the experimental area. It is anticipated that this research output will serve to increase the scientific and objective vegetation monitoring in relation to landform and solar intensity by overcoming serious constraints suffered from the past non-GWR-based approach.

• Journal of agricultural medicine and community health
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• 제41권3호
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• pp.129-139
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• 2016

Objective: The purpose of this study was to identify the predictors and frailty level in the frail elderly receiving home visiting health care services. Methods: The subjects were 177 frail elders aged over 65 registered in the home visiting health care services of three public health centers in Daegu. The data collection was performed from June 9 to June 24, 2015. This study used descriptive statistics, t-test, ANOVA, scheffe test and stepwise multiple regression by SPSS Win 18.0 program. Results: The mean of the frailty score was 10.05 (${\pm}4.52$). Age and life satisfaction were the significant factors related to the frailty score in frail elderly. Health promotion behavior, empowerment, social participation and perceived health status had a negative correlation with the frailty score. Thirty seven point four percent of the variance in the frailty score can be explained by perceived health status (${\beta}=-0.398$, p<0.001), health promotion behavior (${\beta}=-0.251$, p<0.001) and age (${\beta}=0.232$, p<0.001)(Cum $R^2=0.374$, F=25.744, p<0.001). Perceived health status was the most important factor related to the frailty score in our study. Conclusions: An integrative care program which includes these significant variables of subjects is essential to prevent the deterioration of frailty in frail elderly.