• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.2
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• pp.126-131
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• 2014

In this paper, plant crops used in the region to grow crops for the LED lighting area of a rectangle to fit the light distribution to maximize the efficiency of a rectangular distribution was made of LED lights. After the fabrication of LED lamps, light distribution, and in the area of $1.2m{\times}3m$ was the analysis of Illuminance chart. As a result of examining the performance light distribution for total Emin/Eav is 56%, and the target area of the light distribution compared to normal lamps Emin/Eav is improved by about 17%. In addition, plants grown in the area to minimize the outgoing light distribution can be focused on the cultivation area, according to the distance of the plants and be able to have the best luminous efficacy is judged.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.9 no.2
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• pp.243-247
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• 2016

Driving Event Data such as the rapid acceleration, the rapid deceleration, the sudden braking, and the sudden departure, and over speeding provide important information to predict or analyze the driving habits and accident risk of a driver. Most of the data that represent the driver's driving habits generally fit to the parametric distribution, whereas extreme parts of the data to estimate the accident risk of a driver may not. This paper presents an empirical distribution that is divided into two regions, one is from the normal distribution, and the other is from the general pareto distribution for the driving habits of a driver.

• Journal of Preventive Medicine and Public Health
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• v.21 no.2 s.24
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• pp.374-379
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• 1988

In order to prepare the fundamental data for preventing the hazardous effects at toluene exposure in many kinds of industry, the authors determined the level of urinary hippuric acid on 592 toluene exposed women(exposed group) and 102 unexposed women(control group) in Pusan area, from April. 1 to October 31, 1986. Hippuric acid was measured by high performance liquid chromatography. The results were summarized as follows; 1. The mean value of urinary hippuric acid concentration of the control group was $0.44{\pm}0.21g/l$(0.11-0.89g/l). The distribution of urinary hippuric acid concentration of the control group was not fit to the normal distribution. 2. The mean value of urinary hippuric acid concentration of the exposed group was $1.56{\pm}0.95g/l$(0.44-4.57g/l). The distribution of urinary hippuric acid concentration of control group was not fit to the normal distribution. 3. The urinary hippuric acid concentration by age group was not statistically significant in the control group, but in the exposed group the urinary hippuric acid concentration was highest in women between 20-29 years old($1.71{\pm}0.95g/l$) and was statistically significant(p<0.01). 4. The urinary hippuric acid concentration by duration of working hours was not statistically significant (p>0.1).

• Journal of Forest and Environmental Science
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• v.34 no.6
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• pp.451-456
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• 2018

The use of single component distribution to describe the irregular stand structure of degraded forest often lead to bias. Such biasness can be overcome by the application of finite mixture distribution. Therefore, in this study, finite mixture distribution was used to characterise the irregular stand structure of the Gmelina arborea plantation in Omo forest reserve. Thirty plots, ten each from the three stands established in 1984, 1990 and 2005 were used. The data were pooled per stand and fitted. Four finite mixture distributions including normal mixture, lognormal mixture, gamma mixture and Weibull mixture were considered. The method of maximum likelihood was used to fit the finite mixture distributions to the data. Model assessment was based on negative loglikelihood value ($-{\Lambda}{\Lambda}$), Akaike information criterion (AIC), Bayesian information criterion (BIC) and root mean square error (RMSE). The results showed that the mixture distributions provide accurate and precise characterisation of the irregular diameter distribution of the degraded Gmelina arborea stands. The $-{\Lambda}{\Lambda}$, AIC, BIC and RMSE values ranged from -715.233 to -348.375, 703.926 to 1433.588, 718.598 to 1451.334 and 3.003 to 7.492, respectively. Their performances were relatively the same. This approach can be used to describe other irregular forest stand structures, especially the multi-species forest.

• Earthquakes and Structures
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• v.5 no.4
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• pp.439-459
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• 2013

Main objective of the present study is to determine the statistical properties and suitable probability distribution functions of spectral displacements from nonlinear static and nonlinear dynamic analysis within the frame work of Monte Carlo simulation for typical low rise and high rise RC framed buildings located in zone III and zone V and designed as per Indian seismic codes. Probabilistic analysis of spectral displacement is useful for strength assessment and loss estimation. To the author's knowledge, no study is reported in literature on comparison of spectral displacement including the uncertainties in capacity and demand in Indian context. In the present study, uncertainties in capacity of the building is modeled by choosing cross sectional dimensions of beams and columns, density and compressive strength of concrete, yield strength and elastic modulus of steel and, live load as random variables. Uncertainty in demand is modeled by choosing peak ground acceleration (PGA) as a random variable. Nonlinear static analysis (NSA) and nonlinear dynamic analysis (NDA) are carried out for typical low rise and high rise reinforced concrete framed buildings using IDARC 2D computer program with the random sample input parameters. Statistical properties are obtained for spectral displacements corresponding to performance point from NSA and maximum absolute roof displacement from NDA and suitable probability distribution functions viz., normal, Weibull, lognormal are examined for goodness-of-fit. From the hypothesis test for goodness-of-fit, lognormal function is found to be suitable to represent the statistical variation of spectral displacement obtained from NSA and NDA.

• The Journal of the Korean dental association
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• v.56 no.7
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• pp.366-374
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• 2018

Purpose : The purpose of this study was to compare the marginal fit of monolithic zirconia restorations fabricated form the conventional and the digital impression technique. Materials and methods : Ten patients were restored with monolithic zirconia restorations fabricated from the digital and the conventional impression technique. Before definitive insertion, silicone replicas were produced from all twenty crowns. The silicone replicas were cut in three sections; each section was evaluated at two points. The measurement was carried out by using a measuring microscope (Olympus BX 51) and I-Solution. Data from the silicone replica scores were analyzed by Shapiro-Wilk test for normal distribution and the t-test for equality of two population's mean. All tests were performed with ${\alpha}-level$ of 0.05. Results : The average marginal gaps of monolithic zirconia restorations were $133.81{\pm}36.46{\mu}m$ for the conventional impression technique, $90.07{\pm}9.47{\mu}m$ for the digital impression technique. No statistical differences were found between the two impression techniques Conclusion : Both prostheses presented clinically acceptable results with comparing the marginal fit.

• Journal of ILASS-Korea
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• v.20 no.3
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• pp.175-180
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• 2015

A series of sprinkler discharging tests was conducted to measure the droplet size and its distribution of residential fire sprinkler heads. Droplet sizes in sprinkler spray were measured using a laser diffraction method for the flush, circular and pendent type sprinkler head. In this study, the $D_{v,50}$ of the flush type sprinkler heads were ranged between $530{\sim}1040{\mu}m$ and those of circular and pendent type were $988{\mu}m$ and $916{\mu}m$, respectively. The measured cumulative volume distributions were followed by a combination of the log-normal and Rosin-Rammler distribution which is widely used in the computational fire analysis and the parameters of distribution function were obtained from the best fit line through the measured data.

• Journal of the Korean Society of Safety
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• v.32 no.5
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• pp.157-167
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• 2017

Millions of People die every year from diseases caused by exposure to outdoor air pollution. Especially, one of the most severe types of air pollution is fine particulate matter (PM10, PM2.5). South Korea also has been suffered from severe PM. This paper analyzes regional risks induced by PM10 and PM2.5 that have affected domestic area of Korea during 2014~2016.3Q. We investigated daily maxima of PM10 and PM2.5 data observed on 284 stations in South Korea, and found extremely high outlier. We employed extreme value distributions to fit the PM10 and PM2.5 data, but a single distribution did not fit the data well. For theses reasons, we implemented extreme mixture models such as the generalized Pareto distribution(GPD) with the normal, the gamma, the Weibull and the log-normal, respectively. Next, we divided the whole area into 16 regions and analyzed characteristics of PM risks by developing the FN-curves. Finally, we estimated 1-month, 1-quater, half year, 1-year and 3-years period return levels, respectively. The severity rankings of PM10 and PM2.5 concentration turned out to be different from region to region. The capital area revealed the worst PM risk in all seasons. The reason for high PM risk even in the yellow dust free season (Jun. ~ Sep.) can be inferred from the concentration of factories in this area. Gwangju showed the highest return level of PM2.5, even if the return level of PM10 was relatively low. This phenomenon implies that we should investigate chemical mechanisms for making PM2.5 in the vicinity of Gwangju area. On the other hand, Gyeongbuk and Ulsan exposed relatively high PM10 risk and low PM2.5 risk. This indicates that the management policy of PM risk in the west side should be different from that in the east side. The results of this research may provide insights for managing regional risks induced by PM10 and PM2.5 in South Korea.

• Health Policy and Management
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• v.18 no.2
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• pp.19-38
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• 2008

Financial ratios are key indicators of an organization's financial and business conditions. Among various financial indicators, profitability, financial structure, financial activity and liquidity ratios are frequently used and analyzed. Using the structural equation modeling(SEM) technique, this study examines the structural causal relationships among key financial indicators. Data for this study are taken from complete financial statements from 142 hospitals that passed the standardization audit undertaken by the Korean Hospital Association from 1998 to 2001 for the purpose of accrediting teaching hospitals. In order to improve comparability, ratio values are standardized using the Blom's normal distribution. The final model of the SEM has four latent constructs: financial activity(total asset turnover, fixed asset turnover), liquidity(current ratio, quick ratio, collection period), financial structure(total debt to equity, long-term debt to equity, fixed assets to fund balance), and profitability(return on assets, normal profit to total assets, operating margin to gross revenue, normal profit to gross revenue). While examining several model fit indices(Chi-square (df) = 178.661 (40), likelihood ratio=4.467, RMR=.11, GFI=.849, RMSEA=.157), the final SEM we employed shows a relatively good fit. After examining the path coefficient of the constructs, the financial structure of the hospital affects the hospital's profitability in a statistically significant way. A hospital which utilizes its liabilities, more specifically fixed liabilities, and makes a stable investment decision for fixed assets was found to have a higher profitability than other hospitals. Then, the standard path coefficients were examined to directly compare the influence of variables. It was found that there were no statistically significant path coefficients among constructs. When it comes to variables, however, statistically significant relationships were found. between. financial activity and. fixed. asset turnover, and between profitability and normal profit to gross revenue. These results show that the observed variables of fixed asset turnover and normal profit to gross revenue can be used as indicators representing financial activity and profitability.

• Journal of Korean Society on Water Environment
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• v.39 no.4
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• pp.302-315
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• 2023

Distribution characteristics and altitudinal gradient of four species (E. strigata, E. separigata, E. orientalis-sachalinensis group) of the mayfly genus Ephemera (Order Ephemeroptera) were analyzed with probability distribution models (exponential, normal, lognormal, logistic, Weibull, gamma, beta, Gumbel). Data was collected from 23,846 sampling units of 6,787 sites in Korea from 2010 to 2021. The beta distribution model showed the best fit for positively skewed E. orientalis-sachalinensis and little-skewed E. strigata along with altitudinal gradient. The reversed lognormal distribution model showed the best-fit for negatively skewed E. separigata. E. orientalis-sachalinensis distributed at the range of altitude 1~700 m (mean 251 m, median 226 m, mode 124 m, and standard deviation 161 m), E. strigata distributed at the range of altitude 5~871 m (mean 474 m, median 478 m, mode 492 m, and standard deviation 200 m), E. separigata distributed at the range of altitude 7~846 m (mean 620 m, median 659 m, mode 760 m, and standard deviation 181 m). Altitudinal habitat suitability ranges were estimated to be 42~257 m for E. orientalis-sachalinensis, 335~644 m for E. strigata, and 641~824 m for E. separigata. Based on the altitudinal spectrum of suitability and altitude-related temperature analysis results, E. orientalis-sachalinensis was estimated to be thermophilic, E. strigata to be mesophilic, and E. separigata to be thermophobic. This is the first national-scale evaluation of the altitudinal distribution of Ephemera in Korea. These results will be used in a further research study on altitudinal shift of the species of Ephemera under climate change.