• Safety and Health at Work
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• v.6 no.3
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• pp.174-183
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• 2015

The major purpose of this study is to construct a retrospective exposure assessment for benzene through a review of literature on Korea. Airborne benzene measurements reported in 34 articles were reviewed. A total of 15,729 individual measurements were compiled. Weighted arithmetic means [AM(w)] and their variance calculated across studies were summarized according to 5-year period intervals (prior to the 1970s through the 2010s) and industry type. Industries were classified according to Korea Standard Industrial Classification (KSIC) using information provided in the literature. We estimated quantitative retrospective exposure to benzene for each cell in the matrix through a combination of time and KSIC. Analysis of the AM(w) indicated reductions in exposure levels over time, regardless of industry, with mean levels prior to the 1980-1984 period of 50.4 ppm (n = 2,289), which dropped to 2.8 ppm (n = 305) in the 1990-1994 period, and to 0.1 ppm (n = 294) in the 1995-1999 period. There has been no improvement since the 2000s, when the AM(w) of 4.3 ppm (n = 6,211) for the 2005-2009 period and 4.5 ppm (n = 3,358) for the 2010-2013 period were estimated. A comparison by industry found no consistent patterns in the measurement results. Our estimated benzene measurements can be used to determine not only the possibility of retrospective exposure to benzene, but also to estimate the level of quantitative or semiquantitative retrospective exposure to benzene.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.12
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• pp.1566-1577
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• 2010

Nandrolone, 19-nortestosterone, is a synthetic androgenic-anabolic steroid promoting muscle growth. Nandrolone is also present in pig meat and sera at non-negligible levels. A number of scientific reports have suggested a positive relationship between incidence of infertility and increased meat consumption in humans. The present study was designed to determine out the effect of feeding nandrolone on the testis of the male reproductive tract. Mixtures of food and nandrolone at different concentrations (0.005 ppm and 0.5 ppm) were supplied to pubertal male rats for 6 weeks. Body weight was recorded every week during the entire experimental period. At the end of the treatment, the testis, epididymis, and epididymal fat were collected and weighted. Sperm numbers in the caudal epididymis were counted. Differential gene or protein expression of steroidogenic enzymes in the testes among experimental groups was determined by semi-quantitative real-time PCR or western blotting analysis, respectively. Histological changes of the testis induced by nandrolone treatment were examined by hematoxylin and eosin staining. Immunohistochemical analysis was employed to detect changes in the localization of steroidogenic enzymes in the testes among experimental animals. There were no significant changes on body, testis, epididymis, and epididymal fat weights among experimental groups. A significant increase of caudal sperm number was found in the 0.5 ppm nandrolone-treated group. Histological examination of the testes noted a high frequency of germ cell sloughing in seminiferous tubules of 0.5 ppm nandrolone-treated rats. Even though transcript levels of $3{\beta}$-hydroxysteroid dehydrogenase (HSD) I, $17{\beta}$-HSD4, and $17{\alpha}$-hydroxylase were influenced by nandrolone treatments, protein levels of all molecules examined in the present study were not significantly affected. Immunohistochemical analysis showed no visible changes in the localization of steroidogenic enzymes in the testes among experimental groups. The current study showed that oral intake of nandrolone in male rats for 6 weeks did not cause significant damage to the testis. It is considered that a feeding effect of nandrolone on male fertility would not be remarkable.

• Journal of Preventive Medicine and Public Health
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• v.33 no.1
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• pp.117-124
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• 2000

Objectives : It is the objective of this study to compare hepatotoxicity of nickel chloride and cadmium chloride with each other through IPRL(Isolated Perfused Rat Liver) method. Methods : Biochemical indicator of hepatic function such as AST(aspartate aminotransferase), ALT(alanine aminotransferase), LDH(lactate dehydrogenase) and perfusion flow rate were used as the indicator of hepatotoxicity. Oxygen consumption rate were used as vability indicator. $300({\pm}50)g$ - weighted rats were allocated randomly to each group($0{\mu}M,\;50{\mu}M,\;200{\mu}M\;NiCl_2\;and\;CdCl_2$ exposure) by 5, totally 25. After Krebs-Ringer bicarbonate butler solution flowed into the penal vein and passed the liver cell, it flowed out of vena cava. Liver was administered with each $NiCl_2\;and\;CdCl_2$ of each concentration and observed with buffer solution sampling time. Butler which got out of liver was sampled and then biochemical indicator of hepatotoxicity was measured. Results : AST, ALT, and LDH in buffer increased with sampling time much more in $CdCl_2$ exposure group than $NiCl_2$ exposure group in both 50 and $200{\mu}M$ and statistical significance w3s verified with 2-way repeated ANOVA. Viability was decreased more and more in all substances during passed time. Conclusions : It is inferred that $CdCl_2$ has stronger hepatotoxicity than $NiCl_2$. IPRL method would be used widely for acute hepatotoxicity when considerating the benefit of it.

• Korean Journal of Agricultural and Forest Meteorology
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• v.13 no.1
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• pp.41-46
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• 2011

Reliable information on the surface solar radiation is indispensable for rebuilding food production system in the famine plagued North Korea. However, transfer of the related modeling technology of South Korea is not possible simply because raw data such as solar radiation or sunshine duration are not available. The objective of this study is restoring solar radiation data at 27 synoptic stations in North Korea by using satellite remote sensing data. We derived relationships between MODIS radiation estimates and the observed solar radiation at 18 locations in South Korea. The relationships were used to adjust the MODIS based radiation data and to restore solar radiation data at those pixels corresponding to the 27 North Korean synoptic stations. Inverse distance weighted averaging of the restored solar radiation data resulted in gridded surfaces of monthly solar radiation for 4 decadal periods (1983-1990, 1991-2000 and 2001-2010), respectively. For a direct application of these products, we produced solar irradiance estimates for each sub-grid cell with a 30 m spacing based on a sun-slope geometry. These products are expected to assist planning of the North Korean agriculture and, if combined with the already prepared South Korean data, can be used for climate change impact assessment across the whole Peninsula.

• Journal of the Korean Vacuum Society
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• v.19 no.2
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• pp.114-120
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• 2010

Conventional surface texturing in crystalline silicon solar cell have been use wet texturing by Alkali or Acid solution. But conventional wet texturing has the serious issue of wafer breakage by large consumption of wafer in wet solution and can not obtain the reflectance below 10% in multi crystalline silicon. Therefore it is focusing on RIE texturing, one method of dry etching. We developed large scale plasma RIE (Reactive Ion Etching) equipment which can accommodate 144 wafers (125 mm) in tray in order to provide surface texturing on the silicon wafer surface. Reflectance was controllable from 3% to 20% in crystalline silicon depending on the texture shape and height. We have achieved excellent reflectance below 4% on the weighted average (300~1,100 nm) in multi crystalline silicon using plasma texturing with gas mixture ratio such as $SF_6$, $Cl_2$, and $O_2$. The texture shape and height on the silicon wafer surface have an effect on gas chemistry, etching time, RF frequency, and so on. Excellent conversion efficiency of 16.1% is obtained in multi crystalline silicon by RIE process. In order to know the influence of RF frequency with 2 MHz and 13.56 MHz, texturing shape and conversion efficiency are compared and discussed mutually using RIE technology.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.2A
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• pp.177-183
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• 2009

In this paper, we propose an improved anti-collision algorithm. We have designed an anti-collision unit using this algorithm for the 18000-6 Type C Class 1 Generation 2 standard (Gen2). The Gen2 standard uses a Q-algorithm for incremental method on the Dynamic Slot-Aloha algorithm. It has basically enhanced performance over the Slot-Aloha algorithm. Unfortunately, there are several non-clarified parts: initial $Q_{fp}$ value, weighted C, and the ending point of the algorithm. If an incorrect value is selected, it causes degradation in performance. Thus we propose an improved anti-collision algorithm by clearly defining the vague parts of the existing algorithm. Simulation results showed an improved performance of up to 34.8% using an optimized value of C and the initial $Q_{fp}$ value. With the ending condition, performance is 34.7%. The anti-collision unit is designed using the Verilog HDL. The module was synthesized using Synopsys' Design Compiler and the TSMC $0.2{\mu}m$ standard cell library. The synthesized result yielded 3,847 gates, and was guaranteed under the proposed working frequency of 19.2MHz.

• Korean Journal of Agricultural and Forest Meteorology
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• v.2 no.4
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• pp.175-182
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• 2000

Spatial interpolation of daily temperature forecasts and observations issued by public weather services is frequently required to make them applicable to agricultural activities and modeling tasks. In contrast to the long term averages like monthly normals, terrain effects are not considered in most spatial interpolations for short term temperatures. This may cause erroneous results in mountainous regions where the observation network hardly covers full features of the complicated terrain. We developed a spatial interpolation model for daily minimum temperature which combines inverse distance squared weighting and elevation difference correction. This model uses a time dependent function for 'mountain slope lapse rate', which can be derived from regression analyses of the station observations with respect to the geographical and topographical features of the surroundings including the station elevation. We applied this model to interpolation of daily minimum temperature over the mountainous Korean Peninsula using 63 standard weather station data. For the first step, a primitive temperature surface was interpolated by inverse distance squared weighting of the 63 point data. Next, a virtual elevation surface was reconstructed by spatially interpolating the 63 station elevation data and subtracted from the elevation surface of a digital elevation model with 1 km grid spacing to obtain the elevation difference at each grid cell. Final estimates of daily minimum temperature at all the grid cells were obtained by applying the calculated daily lapse rate to the elevation difference and adjusting the inverse distance weighted estimates. Independent, measured data sets from 267 automated weather station locations were used to calculate the estimation errors on 12 dates, randomly selected one for each month in 1999. Analysis of 3 terms of estimation errors (mean error, mean absolute error, and root mean squared error) indicates a substantial improvement over the inverse distance squared weighting.

• Korean Journal of Radiology
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• v.22 no.5
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• pp.751-758
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• 2021

Objective: Preoperative differentiation between inverted papilloma (IP) and its malignant transformation to squamous cell carcinoma (IP-SCC) is critical for patient management. We aimed to determine the diagnostic accuracy of conventional imaging features and histogram parameters obtained from whole tumor apparent diffusion coefficient (ADC) values to predict IP-SCC in patients with IP, using decision tree analysis. Materials and Methods: In this retrospective study, we analyzed data generated from the records of 180 consecutive patients with histopathologically diagnosed IP or IP-SCC who underwent head and neck magnetic resonance imaging, including diffusion-weighted imaging and 62 patients were included in the study. To obtain whole tumor ADC values, the region of interest was placed to cover the entire volume of the tumor. Classification and regression tree analyses were performed to determine the most significant predictors of IP-SCC among multiple covariates. The final tree was selected by cross-validation pruning based on minimal error. Results: Of 62 patients with IP, 21 (34%) had IP-SCC. The decision tree analysis revealed that the loss of convoluted cerebriform pattern and the 20th percentile cutoff of ADC were the most significant predictors of IP-SCC. With these decision trees, the sensitivity, specificity, accuracy, and C-statistics were 86% (18 out of 21; 95% confidence interval [CI], 65-95%), 100% (41 out of 41; 95% CI, 91-100%), 95% (59 out of 61; 95% CI, 87-98%), and 0.966 (95% CI, 0.912-1.000), respectively. Conclusion: Decision tree analysis using conventional imaging features and histogram analysis of whole volume ADC could predict IP-SCC in patients with IP with high diagnostic accuracy.

• Korean Journal of Radiology
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• v.21 no.4
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• pp.471-482
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• 2020

Objective: We aimed to determine the optimized image-based surrogate endpoints (IBSEs) in targeted therapies for glioblastoma through a systematic review and meta-analysis of phase III randomized controlled trials (RCTs). Materials and Methods: A systematic search of OVID-MEDLINE and EMBASE for phase III RCTs on glioblastoma was performed in December 2017. Data on overall survival (OS) and IBSEs, including progression-free survival (PFS), 6-month PFS (6moPFS), 12-month PFS (12moPFS), median PFS, and objective response rate (ORR) were extracted. Weighted linear regression analysis for the hazard ratio for OS and the hazard ratios or odds ratios for IBSEs was performed. The associations between IBSEs and OS were evaluated. Subgroup analyses according to disease stage (newly diagnosed glioblastoma versus recurrent glioblastoma), types of test treatment, and types of response assessment criteria were performed. Results: Twenty-three phase III RCTs published between 2000 and 2017, including 8387 patients, met the inclusion criteria. OS showed strong correlations with PFS (standardized β coefficient [R] = 0.719), 6moPFS (R = 0.647), and 12moPFS (R = 0.638). OS showed no correlations with median PFS and ORR. In subgroup analysis according to types of therapies, PFS showed the highest correlations with OS in targeted therapies for cell cycle pathways (R = 0.913) and growth factor receptors and their downstream pathways (R = 0.962). 12moPFS showed the highest correlation with OS in antiangiogenic therapy (R = 0.821). The response assessment in neuro-oncology criteria provided higher correlation coefficients between OS and IBSEs than the Macdonald criteria. Conclusion: Overall, PFS is an optimized IBSE in targeted therapies for glioblastoma; however, 12moPFS is optimal in antiangiogenic therapy.

• Applied Biological Chemistry
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• v.50 no.4
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• pp.295-303
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• 2007

A preliminary diet experiment utilizing Jerusalem artichoke's inulin, lotus leaf powder, nettle powder and eucalyptus powder extract indicated that combining all four elements gave the most effective result. Therefore, a study was conducted to evaluate the effectiveness of combined diet for weight loss. In this study, Sprague-Dawley, male white rats about 200 g in weight was fed with high fat diet for 8 weeks in order to induce obesity followed by 4 week administration of combined diet to look into the effect of the diet. After a total of 12 weeks of feeding, factors relevant to weight, blood, and lipid metabolism by liver in the body were researched and histologic change was examined with optical microscope. In terms of weight change, both high fat diet group and regular diet group gained weight from high fat diet for 8 weeks compared to normal group. Then, for another 4 weeks, while normal group and high fat diet group kept gaining weight, combined diet group which was provided with high fat diet for 8 weeks, lost weight to the normal group level after 3 week administration of diet. However, after the 4th week of administration, the group weighted significantly less than the normal group and the efficiency of diet also significantly dropped. In the biochemical analysis of blood, total cholesterol, LDL-cholesterol, triglyceride, glucose, GOT, GPT, ${\gamma}-GTP$ and creatine showed significant increase in high fat diet group and there was no significant difference between diet group and normal group except for GPT, ${\gamma}-GTP$ and creatine. In the biochemical analysis of liver, there was significant increase in LDL-cholesterol, triglyceride of high fat diet group compared to normal group, while there was no significant difference in term of total cholesterol and HDL-cholesterol. Compared to normal group, diet group had higher HDL-cholesterol, while total cholesterol dropped significantly. There was no significant difference in terms of LDL-cholesterol and triglyceride. Besides, in high fat diet group, observation of histologic change in liver and change in ultrastructure showed volume increase of hepatic cell and severe fatty degeneration in hepatic cell around hepatic vein. However in diet group, like normal group, no pathological change was observed in terms of cytoplasm, nucleus and capillary in hepatocyte and the alignment of hepatocyte had regularity thanks to the administration of combined diet. Therefore, combined diet utilizing Jerusalem artichoke's inulin, lotus leaf powder, nettle powder and eucalyptus powder was proven to be an effective measure to prevent and improve obesity as a result of abnormal adipose deposition.