• Magazine of the Korean Society of Agricultural Engineers
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• v.22 no.3
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• pp.75-87
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• 1980

Most hydro]ogic phenomena are the complex and organic products of multiple causations like climatic and hydro-geological factors. A certain significant correlation on the run-off in river basin would be expected and foreseen in advance, and the effect of each these causual and associated factors (independant variables; present-month rainfall, previous-month run-off, evapotranspiration and relative humidity etc.) upon present-month run-off(dependent variable) may be determined by multiple regression analysis. Functions between independant and dependant variables should be treated repeatedly until satisfactory and optimal combination of independant variables can be obtained. Reliability of the estimated function should be tested according to the result of statistical criterion such as analysis of variance, coefficient of determination and significance-test of regression coefficients before first estimated multiple regression model in historical sequence is determined. But some error between observed and estimated run-off is still there. The error arises because the model used is an inadequate description of the system and because the data constituting the record represent only a sample from a population of monthly discharge observation, so that estimates of model parameter will be subject to sampling errors. Since this error which is a deviation from multiple regression plane cannot be explained by first estimated multiple regression equation, it can be considered as a random error governed by law of chance in nature. This unexplained variance by multiple regression equation can be solved by stochastic approach, that is, random error can be stochastically simulated by multiplying random normal variate to standard error of estimate. Finally hybrid model on estimation of monthly run-off in nonhistorical sequence can be determined by combining the determistic component of multiple regression equation and the stochastic component of random errors. Monthly run-off in Naju station in Yong-San river basin is estimated by multiple regression model and hybrid model. And some comparisons between observed and estimated run-off and between multiple regression model and already-existing estimation methods such as Gajiyama formula, tank model and Thomas-Fiering model are done. The results are as follows. (1) The optimal function to estimate monthly run-off in historical sequence is multiple linear regression equation in overall-month unit, that is; Qn=0.788Pn+0.130Qn-1-0.273En-0.1 About 85% of total variance of monthly runoff can be explained by multiple linear regression equation and its coefficient of determination (R2) is 0.843. This means we can estimate monthly runoff in historical sequence highly significantly with short data of observation by above mentioned equation. (2) The optimal function to estimate monthly runoff in nonhistorical sequence is hybrid model combined with multiple linear regression equation in overall-month unit and stochastic component, that is; Qn=0. 788Pn+0. l30Qn-1-0. 273En-0. 10+Sy.t The rest 15% of unexplained variance of monthly runoff can be explained by addition of stochastic process and a bit more reliable results of statistical characteristics of monthly runoff in non-historical sequence are derived. This estimated monthly runoff in non-historical sequence shows up the extraordinary value (maximum, minimum value) which is not appeared in the observed runoff as a random component. (3) "Frequency best fit coefficient" (R2f) of multiple linear regression equation is 0.847 which is the same value as Gaijyama's one. This implies that multiple linear regression equation and Gajiyama formula are theoretically rather reasonable functions.

• Journal of Preventive Medicine and Public Health
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• v.35 no.1
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• pp.24-32
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• 2002

Objective : Few studies have examined the relationship between the risk of cancer and exposure to pesticides in Korea or in other East Asian that have until recently used chlorophenoxy herbicides. The aim of this study was to evaluate the relationship between the exposure to pesticides and cancer incidence. Methods : We conducted a prospective cohort study with a follow-up period of 13 years (1985-1998). The subjects included 2,687 male and 3,589 female Kangwha Island residents, Koreans aged fifty-five or more as of March 1985, who received a personal health interview and completed a health examination survey. A Cox proportional hazards models were used to estimate relative risks(RR). Results : At baseline, the mean age of the study participants in 1985 was 66.4 for males and 67.1 for females. During the 13 years follow-up, a total of 300 incidents of cancer in males and 140 in females developed. In males, the total cancer incidence in the highest group was RR, 1.4 (95%. CI=1.0-1.9), p for trend=0.041, for digestive organ cancer Incidence in the highest group, RR, 1.5 (95% CI=1.0-2.3), p for trend=0.057, for stomach cancer, incidence in the highest group, RR, 1.6 (95% CI=0.9-2.8), p for trend=0.094, for gallbladder cancer incidence in the highest group, RR, 9.1 (95% CI=1.1-77.0), p for trend=0.014 were elevated according to the higher frequency of pesticide use per year. In particular, the risk of gallbladder cancer was very high. Although not significant, the risk of liver cancer was higher than in the non-exposed group (in the highest group, RR, 2.0(95% CI=0.7-5.9)). In females, although not significant, breast cancer incidence in the highest exposure group was higher than in the non-exposed group (in the highest group, RR, 4.7 (95% CI=0.5-27.9)). Conclusions : This study demonstrates that Korean farmers who use pesticides, particularly males, have a significantly higher total cancer incidence, particularly from digestive organ cancers such as, stomach, gallbladder, and liver cancer. In particular, the risk of gallbladder cancer was very high.

• Korean Journal of Remote Sensing
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• v.34 no.2_2
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• pp.407-418
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• 2018

The frequency and risk of disasters are increasing due to environmental and social factors. In order to respond effectively to disasters that occur unexpectedly, it is very important to quickly obtain up-to-date information about target area. It is possible to intuitively judge the situation about the area through the image-map generated at high speed, so that it can cope with disaster quickly and effectively. In this study, we propose an image-map generation and visualization system from UAV images for real-time disaster monitoring. The proposed system consists of aerial segment and ground segment. In the aerial segment, the UAV system acquires the sensory data from digital camera and GPS/IMU sensor. Communication module transmits it to the ground server in real time. In the ground segment, the transmitted sensor data are processed to generate image-maps and the image-maps are visualized on the geo-portal. We conducted experiment to check the accuracy of the image-map using the system. Check points were obtained through ground survey in the data acquisition area. When calculating the difference between adjacent image maps, the relative accuracy was 1.58 m. We confirmed the absolute accuracy of the image map for the position measured from the individual image map. It is confirmed that the map is matched to the existing map with an absolute accuracy of 0.75 m. We confirmed the processing time of each step until the visualization of the image-map. When the image-map was generated with GSD 10 cm, it took 1.67 seconds to visualize. It is expected that the proposed system can be applied to real - time monitoring for disaster response.

• The Korean Journal of Applied Statistics
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• v.29 no.1
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• pp.85-98
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• 2016

This study makes an empirical comparison of various realized volatilities (RVs) in terms of overnight returns. In financial asset markets, during overnight or holidays, no or few trading data are available causing a difficulty in computing RVs for a whole span of a day. A review will be made on several RVs reflecting overnight return variations. The comparison is made for forecast accuracies of several RVs for some financial assets: the US S&P500 index, the US NASDAQ index, the KOSPI (Korean Stock Price Index), and the foreign exchange rate of the Korea won relative to the US dollar. The RV of a day is compared with the square of the next day log-return, which is a proxy for the integrated volatility of the day. The comparison is made by investigating the Mean Absolute Error (MAE) and the Root Mean Square Error (RMSE). Statistical inference of MAE and RMSE is made by applying the model confidence set (MCS) approach and the Diebold-Mariano test. For the three index data, a specific RV emerges as the best one, which addresses overnight return variations by inflating daytime RV.

• Proceedings of the Korean Society of Toxicology Conference
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• 2006.11a
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• pp.32-33
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• 2006

There is compelling evidence that chronic inflammation predisposes to biliary tract cancer. Previously we found that aspirin use and variants in the PTGS2 gene, both of which are closely linked to inflammation, were associated with biliary tract cancer risk in a population-based study in China. To test the inflammation hypothesis further, we examined the associations of variants in 20 genes involved in the inflammation pathway with risk of biliary tract cancer and stones in a large population-based case-control study in Shanghai, China. We genotyped 56 single nucleotide polymorphisms (SNPs)from 20 inflammation genes in 411 biliary tract cancer cases (237 gallbladder cancers, 127 extrahepatic bile duct cancers, and 47 ampullary cancers), 895 subjects with biliary stones, and 786 population controls. Unconditional logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (Cls) for the association of individual SNPs and haplotypes with biliary stones and biliary tract cancer risk. Of the 56 SNPs examined, 20 showed some associations with biliary cancer and stones. Specifically, variants of the IL8, IL8RB, RNASEL, TGF-beta, and TNF-alpha genes were associated with gallstone risk, while variants in the IL1A, IL10, VEGF, and RNASEL genes were associated with gallbladder cancer risk. Adjustment for multiple comparisons did not materially change these results. Of the 10 genes with multiple SNPs, we inferred halotypes; only one haplotype in the IL8RBgene was associated with gallstones. The haplotype frequency was significantly different between bile dict cancer cases and control (p=0.007). A haplotype comprising 3 SNPs in the IL8RB gene (rs2230054, rs1126579, rs1126580) was associated with a 54% increased risk of bile duct stones (95% CI 1.14-2.07, p=0.02), relative to the most frequent haplotype. In summary, common variants in immune-related genes influencing inflammatory responeses were associated with gallstones and biliary tract cancer, lending further support to the role of inflammation in the pathogenesis of biliary stones and biliary tract cancer. Future larger studies with more complete gene coverage are needed to confirm these results.

• Parasites, Hosts and Diseases
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• v.35 no.1
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• pp.9-17
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• 1997

During the period of 1933-1994, house dusts were collected from 65 homes at 10 different localities by operating electric vacuum cleaners. House dust mites were isolated from 10 g dust by applying the modified wet sieving method. Total 7,257 mites were collected and 23 species were identified. Among them, Demctophqgoines loyinaf (DF) was predominant (65. Soy) of the total) , followed by D. pteronvssinus (DP) (20.6%) and Tyrophagus nutrescentios (TP) (6.5%) . Rhizoglvphur robini, Sancqsscnin phvIlophogiann, Cheyletus trcussarti and Scheloribates latipes were the first findings from Korea. DF was predominant in Seoul (66.8%), Kwangju (63.6%), inland of Pusan (79.6%1, Inchon (96.5%), Taejon (83.9%), Chouju (87.15) and Chongiu (95.2%), whereas DP was predominant in Yongkwang-ub (72.5%) and Yongdo (island) of Pusan (64.9%), and TP in Chunchon (38.2%) The localities where DP and TP were predominant showed higher relative humidity in air (> 73% RH) . Among 62 study homes, DF, DP and TP were found in 24.6% of the homes, co-habitat of two species in 48.1% and one species in 27.3%. DF was predominant in 63.5% of the homes studied, DP in 29.6% and TP in 6.9%. In 10 g of the house dust, less than 99 mites were found in 49 homes (70.0%), 100-499 mites in 11 homes (15.7%), 500-999 mites in 3 homes (4.3%) and more than 1,000 mites in 2 homes (2.9%). No mite was found in 5 homes (7.1%). In order to evaluate environmental factors affecting the population density of house dust mites, house type, age of house construction, size of the house, number of the family and frequency of the cleaning were compared with the number of mites, and none of the above factors were statistically correlated with the mite density.

• Korean Journal of Materials Research
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• v.9 no.9
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• pp.943-947
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• 1999

The crystal structure and the microwave dielectric properties of $La(Mg_{1/2}Ti_{1/2})O_3$ ceramics have been investigated. $La(Mg_{1/2}Ti_{1/2})O_3$ has the 1:1 ordered monoclinic structure with the lattice parameters of $a = 5.5467(3){\AA}, b = 5.5616(3){\AA}, c = 7.8426(5) {\AA} and \beta = 89.9589 (2)^{\circ}$ The spacegroup of LMT is $P2_1/n$. Monoclinic LMT has the in­phase and anti-phase tilting of octahedra with the $a^_a^_c^_$ tilting system. Anti-parallel shift of A-site cations was also found in LMT. The relative density of the specimens sintered above $1600^{\circ}C$ was ranged between 95 % and 96 % of the theoretical density and the dielectric constant of specimens was about 28. The highest $Q\timesf$ achieved in this investigation was 63,100 for the specimen sintered at $1630^{\circ}C$ for 5 hr. Temperature coefficient of resonance frequency ranged from $>-74 ppm/^{\circ}C ~ -79 ppm/^{\circ}C$.

• Korean Journal of Head & Neck Oncology
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• v.28 no.1
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• pp.3-7
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• 2012

Background and Objectives : Nasopharyngeal carcinoma(NPC) shows a distinct geographic and demographic distribution with high incidences in Chinese and Southeast Asians. Current WHO classification divides NPC into nonkeratinizing carcinoma(NKC)(differentiated and undifferentiated subtypes), keratinizing squamous cell carcinoma(KSCC), and basaloid squamous cell carcinoma(BSCC). Relative frequency of histologic subtypes of NPC is known to vary according to the incidence of NPC. Korea is one of the low-incidence countries according to the GLOBOCAN 2008 database by IARC. The aim of this study is to assess the histopathologic types and EBV status of NPC of Koreans. Materials and Methods : We reviewed and reclassified 168 cases of NPC(132 males and 36 females) diagnosed from January 1996 through July 2006. In situ hybridization for EBV-encoded early RNA(EBER) was performed on 146 cases and the results were compared among different histologic types, genders, and age and stage groups. Results : NKC, undifferentiated subtype(NKC-U) was identified in 106 cases(63.1%) and differentiated subtype(NKC-D) in 49 cases(29.2%). Remaining 13 cases(7.7%) were classified as KSCC. NKC and NKC-U were more common in females than in males. EBV prevalence was higher in NKC than in KSCC(NKC-U, 90% ;, NKC-D, 84.1% ; KSCC, 7.7%) and more common in younger age(${\leq}40$) than older age(>40) group. Conclusion : Histologic type distribution and EBV prevalence of NPC in Korean patients corresponded to that of intermediate incidence area. Pathogenesis of nasopharyngeal KSCC is assumed to be different from that of NKC.

• Journal of Environmental Impact Assessment
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• v.24 no.2
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• pp.190-203
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• 2015

VRI(Vulnerability-Resilience Index), which is defined as a function of 3 variables: climate exposure, sensitivity, and adaptive capacity, has been quantified for the case of Typhoon which is one of the extreme weathers that will become more serious as climate change proceeds. Because VRI is only indicating the relative importance of vulnerability between regions, the VRI quantification is prerequisite for the effective adaptation policy for climate in Korea. For this purpose, damage statistics such as amount of damage, occurrence frequency, and major damaged districts caused by Typhoon over the past 20 years, has been employed. According to the VRI definition, we first calculated VRI over every district in the case of both with and without weighting factors of climate exposure proxy variables. For the quantitative estimation of weighting factors, we calculated correlation coefficients (R) for each of the proxy variables against damage statistics of Typhoon, and then used R as weighting factors of proxy variables. The results without applying weighting factors indicates some biases between VRI and damage statistics in some regions, but most of biases has been improved by applying weighting factors. Finally, due to the relations between VRI and damage statistics, we are able to quantify VRI expressed as a unit of KRW, showing that VRI=1 is approximately corresponding to 500 hundred million KRW. This methodology of VRI quantification employed in this study, can be also practically applied to the number of future climate scenario studies over Korea.

• The Journal of Korean Medicine
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• v.16 no.2 s.30
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• pp.44-61
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• 1995

Arranging 63 kinds of separate volumes and papers published on Oriental medicine, I could get the result as follows. 1. The herbs for internal application used commonly in vitiligo are 155 kinds totally. The herbs for external application are 67 kinds. The herbs for external and internal both application examined into 23 sorts. 2. Herbs for weakness syndrome in vitiligo are 49 kinds. Another type, excess syndrome is 105 sorts, the'latter is roughly twice as many as the former. 3. It is as follows that the results of study in relations to kinds, factors, and medical treatments of herbs about vitiligo in and out of the country with the division of former times to 1900, 1901 to 1980, 1981 to 1990, and 1991 to the latest day. In comparative study of inner and outer of thc country about factors and medical treatments of vitiligo in chronicle classification, its factors in the internal documents are classified by outside factors. Although there arc the differences of factors by each epoch, however, the factors of vitiligo according to external documents are blood stasis(血熱), deficiency of um of the liver and kidneys(肝腎陰虛), deficiency of blood(血虛), excess of exhaustion(勞倦過多) etc. Moreover, the medical treatment is more diverse and the differences by each epoch as to the medical treatment is also put down more saliantiy than in internal documents. 4. In comparison with herbs in experimental and no experimental documents, herbs applied for weakness syndromes in experimental method are 40 kinds totally. The herbs in no experimental methods are 35 kinds. The herbs used by experimental method are 65 kinds. The common herbs for excess syndrome by no experimental method are 78 kinds. We can see comparable difference from kinds of herbs used by experimental method. In brief, there are the differences classified by each epoch in Oriental medicine for treatment. Especially one of the most important feature, the frequency in use of weakness syndrome herbs has increased more than that of excess syndrome herbs. In external documents (china) and experimental study, generally the differences of common herbs and factors have disappeared through many experimentsitudy. The classification of its factors have been fractionalized clinically. Besides, in Western medicine and Orienal medicine, vitiligo tends to be prescribed not to simple skin disease but a mental and physical disease, a whole body and an internal disease.