• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.2
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• pp.325-331
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• 2017

Due to the climate change, natural disaster has been occurred more frequently and the number of snow disasters has been also increased. Therefore, many researches have been conducted to predict the amount of snow damages and to reduce snow damages. In this study, snow damages over last 21 years on the Natural Disaster Report were analyzed. As a result, Chungcheong-do, Jeolla-do, and Gangwon-do have the highest number of snow disasters. The multiple linear regression models were developed using the snow damage data of these three provinces. Daily fresh snow depth, daily maximum, minimum, and average temperatures, and relative humidity were considered as possible inputs for climate factors. Inputs for socio-economic factors were regional area, greenhouse area, farming population, and farming population over 60. Different regression models were developed based on the daily maximum snow depth. As results, the model efficiency considering all damage (including low snow depth) data was very low, however, the model only using the high snow depth (more than 25 cm) has more than 70% of fitness. It is because that, when the snow depth is high, the snow damage is mostly caused by the snow load itself. It is suggested that the 25 cm of snow depth could be used as the snow damage threshold based on this analysis.

• Journal of Korean Physical Therapy Science
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• v.27 no.3
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• pp.1-11
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• 2020

Background: The purpose of this study was to investigated the effects of threshold resistance inspiratory muscle training on respiratory function in chronic stroke patients. Design: Randomized Controlled Trial Methods: Eighteen patient with stroke were randomly assigned to the experimental group (n=9) and control group (n=9) all testing and training. The experimental group underwent threshold resistance inspiratory muscle training with resistance adjusted of maximal inspiratory pressure, 60 breathing a day and general physical therapy 30 minutes a day, 5 times a week for 4 weeks. The control group was taken general respiratory muscle training and general physical therapy for 4 weeks in the same way. Respiratory function, walking ability were evaluated before and after the intervention. Statistical significance of the results were evaluated by ANCOVA between control group and experimental group after intervention. Results: There was a significant increase in FVC and FEV1 in the experimental group in pulmonary function tests (p<0.05). There was a significant difference with the maximum inspiratory pressure and the maximum inspiratory flow rate between experimental and control group (p<0.05). There was no significant difference with the maximum inspiratory capacity between experimental and control group (p>0.05) but the maximum inspiratory capacity of experimental group some increased than that of control group. Conclusion: These finding gave some indications that the threshold resistance inspiratory training may benefit on pulmonary function in people with stroke, and it is feasible to be included in rehabilitation interventions with this population.

• Korean Journal of Agricultural and Forest Meteorology
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• v.9 no.4
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• pp.228-233
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• 2007

Pear psylla, Caccopsylla pyricola (Homoptera: Psyllidae), is a serious insect pest in pear orchards. C. pyricola overwinters as adults under rough bark scales of pear trees. When the weather warms up in the spring, the overwintered adults become active, climb up to the tree branches, and inhabit on fruit twigs to lay eggs. This study was conducted to develop a forecasting model for the onset of upward-movement of overwintered C. pyricola adults to control them by timely spraying of petroleum oil. The adult population densities were observed under rough barks (B) and on fruit twigs (T) of pear trees. Relative upward-movement rates (R) were calculated as T/(B+T). Low threshold temperatures for the activation of overwintered C. pyricola adults were selected arbitrarily from 5 to $9^{\circ}C$ at a $1^{\circ}C$ interval. Then, the days (D) when daily maximum air temperatures were above each low threshold temperature were counted from 1 February until to the dates with R $\geq$ 0.8. The same methods were applied for the prediction of the first observation of eggs. The variation of coefficients (CV) for the mean Des were lowest with the low threshold temperature of $6^{\circ}C$. At this selected threshold temperature, the upward movement of C. pyricola adults occurred with 12 D and they started laying eggs with 25 D. In the field validation, the model outputs with the $6^{\circ}C$ threshold temperature reasonably well explained the observed data in Suwon and Cheonan in 2002. Practical usages of the model were also discussed.

• Journal of Preventive Medicine and Public Health
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• v.53 no.6
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• pp.405-408
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• 2020

In epidemiology, the basic reproduction number (R₀) is a term that describes the expected number of infections generated by 1 case in a susceptible population. At the beginning of the coronavirus disease 2019 (COVID-19) pandemic, R₀ was frequently referenced by the public health community and the wider public. However, this metric is often misused or misinterpreted. Moreover, the complexity of the process of estimating R₀ has caused difficulties for a substantial number of researchers. In this article, in order to increase the accessibility of this concept, we address several misconceptions related to the threshold characteristics of R₀ and the effective reproduction number (R_t). Moreover, the appropriate interpretation of the metrics is discussed. R₀ should be considered as a population-averaged value that pools the contact structure according to a stochastic transmission process. Furthermore, it is necessary to understand the unavoidable time lag for R_t due to the incubation period of the disease.

• Proceedings of the Korean Institute of Interior Design Conference
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• 2007.05a
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• pp.131-136
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• 2007

According to the OECD Report, Korea passed the first threshold to an "aging society" in which the elderly aged over 65 make up at least 7 percent of the population in 2000, and in 2018, are due to pass the second to an "aged society" in which they make up at least 14 percent-just 18 years later. It took France (starting in 1864) 115 years to complete this transition. Even Japan, legendary for the rapidity of its aging, required 24 years. It means Korea has to prepare for the aging of its population within a very short time without mistakes. Meanwhile, in a 2005 survey of the elderly, 85.5% of them preferred aging in place to moving to elderly care facilities. That means housing planning for the elderly which provides them with independent living needs to be considered seriously. The digital technology integrated home may be one of the alternatives to support this idea. In order to find a way to user oriented digital homes for the elderly, this study identified the their needs on the physical features of the ideal home and the digital services necessary through digital life scenarios.

• Nuclear Engineering and Technology
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• v.49 no.6
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• pp.1157-1164
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• 2017

The Monte Carlo criticality simulation of decoupled systems, as for instance in large reactor cores, has been a challenging issue for a long time. In particular, due to limited computer time resources, the number of neutrons simulated per generation is still many order of magnitudes below realistic statistics, even during the start-up phases of reactors. This limited number of neutrons triggers a strong clustering effect of the neutron population that affects Monte Carlo tallies. Below a certain threshold, not only is the variance affected but also the estimation of the eigenvectors. In this paper we will build a time-dependent diffusion equation that takes into account both spatial correlations and population control (fixed number of neutrons along generations). We will show that its solution obeys a traveling wave dynamic, and we will discuss the mechanism that explains this biasing of local tallies whenever leakage boundary conditions are applied to the system.

• Korean journal of applied entomology
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• v.48 no.3
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• pp.355-359
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• 2009

By releasing predatory mite, Amblyseius swirskii Athias-Henriot, with 25 individuals per cucumber plant in a commercial greenhouse (1,600 $m^2$), the population of western flower thrips, Frankliniella occidentalis (Pergande), was kept under the economic threshold level. The initial thrips population of 18.3 individuals per leaf decreased to 2.1 individuals per leaf after four weeks, while the number of A. swirskii reached to 16.6 individuals per leaf. It was also observed that at a point where the thrips occurred in high density of about 34.3 individuals per leaf, A. swirskii population built up on the lower part of cucumber plant first, but as time passed the predatory mites moved upward to the top of the plant and aggregated.

• Gut and Liver
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• v.12 no.6
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• pp.655-663
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• 2018

Background/Aims: The association between metabolic syndrome and colorectal cancer (CRC) has been suggested as one of causes for the increasing incidence of CRC, particularly in younger age groups. The present study examined whether the current age threshold (50 years) for CRC screening in Korea requires modification when considering increased metabolic syndrome. Methods: We analyzed data from the National Health Insurance Corporation database, which covers ~97% of the population in Korea. CRC risk was evaluated with stratification based on age and the presence/absence of relevant metabolic syndrome components (diabetes, dyslipidemia, and hypertension). Results: A total of 51,612,316 subjects enrolled during 2014 to 2015 were analyzed. Among them, 19.3% had diabetes, hypertension, dyslipidemia, or some combination thereof. This population had a higher incidence of CRC than did those without these conditions, and this was more prominent in subjects <40 years of age. The optimal cutoff age for detecting CRC, based on the highest Youden index, was 45 years among individuals without diabetes, dyslipidemia, and hypertension. Individuals with at least one of these components of metabolic syndrome had the highest Youden index at 62 years old, but the value was only 0.2. Resetting the cutoff age from 50 years to 45 years achieved a 6% increase in sensitivity for CRC detection among the total population. Conclusions: Starting CRC screening earlier, namely, at 45 rather than at 50 years of age, may improve secondary prevention of CRC in Korea.

• Journal of Yeungnam Medical Science
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• v.36 no.2
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• pp.141-147
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• 2019

Background: The present study aimed to evaluate the clinical association between cadmium exposure and hearing impairment among the Korean population. Methods: This retrospective cross-sectional study used the data obtained from the Korean National Health and Nutrition Examination Survey were used for our study. Finally, 3,228 participants were included in our study, which were then divided into quartiles based on their blood cadmium levels: first quartile (1Q), second quartile (2Q), third quartile (3Q), and fourth quartile (4Q) groups. The hearing thresholds were measured using an automatic audiometer at 0.5, 1, 2, 3, 4, and 6 kHz. Hearing loss (HL) was defined as >25 dB average hearing threshold (AHT). Results: All the groups had 807 participants each. The area under the receiver operating characteristic curves of cadmium level for HL were 0.634 (95% confidence interval [CI], 0.621-0.646). The participants in the 4Q group had higher Low/Mid-Freq, High-Freq, and AHT values than those in the other groups in the multivariate analysis after adjusting for confounding factors. The logistic regression showed that the OR for HL per $1{\mu}g/L$ increase in cadmium was 1.25 (95% CI, 1.09-1.44; p=0.002) on the multivariate analysis. Moreover, the multivariate logistic regression analyses revealed that the participants in the 4Q group exhibited a 1.59-, 1.38-, and 1.41-fold higher odds for HL than those in the 1Q, 2Q, and 3Q groups, respectively. Conclusion: High cadmium level quartile was associated with increased hearing thresholds and HL among the Korean adult population.

• Korean Journal of Schizophrenia Research
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• v.23 no.2
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• pp.65-70
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• 2020

Objectives: This study aimed to explore whether common genetic variants that confer the risk of schizophrenia have similar effects between Korean and European ancestries using the polygenic risk score (PRS) analysis. Methods: Study subjects included 713 Korean patients with schizophrenia and 497 healthy controls. The Korea Biobank array was used for genotyping. Summary statistics of the most recent genome-wide association study (GWAS) of the European population were used as baseline data to calculate PRS. Logistic regression was conducted to determine the association between calculated PRS of European patients with schizophrenia and clinical diagnosis of schizophrenia in the Korean population. Results: Schizophrenia PRS was significantly higher in patients with schizophrenia than in healthy controls. The PRS at the p-value threshold of 0.5 best explained the variance of schizophrenia (R²=0.028, p=4.4×10^-6). The association was significant after adjusting for age and sex (odds ratio=1.34, 95% confidence interval=1.19-1.51, p=1.1×10^-6). The pattern of the association remained similar across different p-value thresholds (0.01-1). Conclusion: Schizophrenia PRS calculated using the European GWAS data showed a significant association with the clinical diagnosis of schizophrenia in the Korean population. Results suggest overlapping genetic risk variants between the two populations.