• Pediatric Infection and Vaccine
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• v.23 no.3
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• pp.202-208
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• 2016

Purpose: Rotavirus vaccine (RV) was introduced in Korea since 2007, and intussusception (IS) remains an important safety concern. This study investigated the trend of IS occurrence related to RV as well as the temporal relevance between vaccination and IS in children. Methods: We collected data of the patient aged ${\leq}18$ years with IS admitted to Gachon University Gil Medical Center, 2003 to 2015. For the patients that have occurred since 2008, the immunization records of RV were collected. The proportion of cases <1 year was calculated by the year and the temporal relationship between vaccination and IS occurrence was analyzed. Results: A total of 696 IS cases were noted. The cases <1 year were 30.7% (214/696). Although the incidence of all IS has increased over the 13-year period (from 74.1 in 2003 to 89.5 in 2015, linear by linear association, P=0.003), the incidence of IS <1 year has not increased (from 56.9 in 2003 to 53.3 in 2015, P=0.910), and the proportion of cases <1 year has decreased (from 35.4 in 2003 to 18.8 in 2015, P=0.000). Of 128 cases <1 year since 2008, 53.9% received RV. In the vaccinated group, 10 cases of IS occurred within 30 days, and eight cases did within 31 to 60 days. Numbers of IS after first, second, and third dose were three, 10, and five cases, respectively. Conclusions: Occurrence of IS in children <1 year of age did not increase since the introduction of RV. Further monitoring is essential for evaluation of vaccine safety.

• Journal of Korea Water Resources Association
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• v.50 no.4
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• pp.253-261
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• 2017

A lot of nonstationary frequency analyses have been studied in recent years as the nonstationarity occurs in hydrologic time series data. In nonstationary frequency analysis, various forms of probability distributions have been proposed to consider the time-dependent statistical characteristics of nonstationary data, and various methods for parameter estimation also have been studied. In this study, we aim to introduce a parameter estimation method for nonstationary Gumbel distribution using ensemble empirical mode decomposition (EEMD); and to compare the results with the method of maximum likelihood. Annual maximum rainfall data with a trend observed by Korea Meteorological Administration (KMA) was applied. As a result, both EEMD and the method of maximum likelihood selected an appropriate nonstationary Gumbel distribution for linear trend data, while the EEMD selected more appropriate nonstationary Gumbel distribution than the method of maximum likelihood for quadratic trend data.

• Journal of the Korea Concrete Institute
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• v.27 no.4
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• pp.331-341
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• 2015

The main purpose of this study is reducing the cost and effort for characterization of tensile strength of fiber reinforced concrete, in order to use in structural design. For this purpose, in this study, test for fiber reinforced concrete was carried out. Because fiber reinforced concrete is consisted of diverse material, it is hard to define the correlation between mix proportions and strength. Therefore, compressive strength test and tensile strength test were carried out for the range of smaller than 100 MPa of compressive strength and 0.25~1% of steel fiber volume fraction. as a results of test, two types of tensile strength were highly affected by compressive strength of concrete. However, increase rate of tensile strength was decreased with increase of compressive strength. Increase rate of tensile strength was decreased with increase of fiber volume fraction. Database was constructed using previous research data. Because estimation equations for tensile strength of fiber reinforced concrete should be multiple variable function, linear regression is hard to apply. Therefore, in this study, we decided to use the ANN(Artificial Neural Network). ANN was constructed using multiple layer perceptron architecture. Sigmoid function was used as transfer function and back propagation training method was used. As a results of prediction using artificial neural network, predicted values of test data and previous research which was randomly selected were well agreed with each other. And the main effective parameters are water-cement ratio and fiber volume fraction.

• The Journal of Engineering Geology
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• v.20 no.4
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• pp.425-436
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• 2010

We established a stochastic 3-D fracture network system for fractured rock masses located in Il-Gwang Mine, Busan, to explore the relationship between the acidity of mine drainage and fracture geometry. A field scanline survey and borehole image processing were performed to estimate the best probability distributions of fracture geometry parameters. The stochastic 3-D fracture network system constructed for the rock masses was validated and deemed to be successful. The 3-D fracture network model was suitable for developing conceptual ideas on fluid flow in fractures at a field experimental site. An injection well and three observation wells were drilled at the field experimental site to monitor the acidity of mine drainage induced by the injection of fresh water. The field experiment, which was run for 29 days, yielded a significant relationship (with a high coefficient of determination) between the fracture geometry parameters and the acidity of mine drainage. The results show that pH increased with increasing relative frequency of fracture strike, and decreased with increasing fracture density. The concentration of $SO^{2-}_4$ decreased with increasing relative frequency of fracture strike, and increased with increasing fracture density.

• Journal of the Mineralogical Society of Korea
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• v.31 no.2
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• pp.75-86
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• 2018

This study analyzed precipitation environment, heavy metal concentration, mineral composition, and spectral characteristics associated with heavy metal concentration and mineral composition for the reddish brown precipitates occurred in the drainage of Dogye mining station. The pH of the reddish brown precipitates ranges from 7.59 to 7.94 resulting neutral. XRF analysis reveals that the precipitates has high Fe concentration, and contaminated with Ni, Cu, and Zn. Dolomite, calcite, goethite, magnetite, kaolinite, pyrophyllite, quartz and aluminum isopropoxide were identified based on XRD analysis. As a result of spectral analysis associated with heavy metal contamination, visible reflectance increases and infrared reflectance decreases with a increase in heavy metal concentration. The spectral characteristics of the reddish brown precipitates is turned out to be manifested by goethite, magnetite, kaolinite, pyrophyllite and aluminum isopropoxide.

• Journal of Environmental Impact Assessment
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• v.29 no.3
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• pp.210-218
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• 2020

Even though PM₁₀ in ambient air has been steadily reduced, the perception of it has been deteriorated. Forthatreason, first, it can still be mentioned the annual average concentration of PM₁₀ exceeding WHO standards, second, an increase in the number of high concentration days of PM₁₀, and third, lack of consideration for differences in causes and phenomena of PM₁₀ by regions. Therefore, this study was aimed to suggest management types for PM₁₀ in ambient air by clustering 69 cities based on the trends and current levels of PM₁₀. In addition, we proposed complementary measures such as the green infrastructure, ventilation corridors and adaptation measures (limit of exposure) for type III (distribution in the central inner region) and IV (metropolitan city, south-east coast region) where improvement of PM₁₀ was insufficient. Although this study did not consider the cause of PM₁₀ together, there is a significance that the scientific basis for responding to the near future is conducted based on past trends of PM₁₀.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.104-104
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• 2018

이수안전도의 기준이 되는 갈수량에 대해 기후변화 시나리오에 따른 전망을 제시하였다. 충주 댐 유역을 대상으로 기준기간(1986~2000년)에서의 기상청의 관측 기상자료와 IPCC 보고서의 RCP 4.5/8.5 시나리오를 대상으로 CMIP5(Coupled Model Intercomparison Project Phase 5)에서 제공하는 기후변화 자료 중 5개의 모델(ACCESS1.3 CanESM2, CNRM-CM5, GFDL-ESM2G, HadGEM2-AO)의 기준기간과 미래기간(2011~2100년)의 기상자료를 수집하였다. 기후변화 자료는 정상성/비정상성 분위사상법과 베이지안 모델 평균기법을 통해 불확실성과 통계적 오차를 저감하였다. 미래기간에서, 강우는 RCP 4.5에서 1.74mm/year, RCP 8.5에서 3.22mm/year, 실제증발산은 RCP 4.5에서 1.09mm/year, RCP 8.5에서 1.78mm/year의 증가율을 보였다. 실제증발산을 입력자료로 활용할 수 있도록 IHACRES모델의 CMD(Catchment Moisture Deficit) 비선형 모듈의 매개변수를 변이하여 유효강우량 산정 과정을 개선하였다. 기준기간에서 관측유량자료와 IHACRES의 시뮬레이션을 통해 산정된 유량자료의 R-squared는 0.65이다. 기준기간에서의 매개변수를 고정하여 미래기간의 유량을 산정하고 유황분석을 통해 갈수량 전망하였다. 유량은 RCP 4.5에서 4.41MCM/year, RCP 8.5에서 9.66MCM/year의 증가율을 보였다. 갈수량은 RCP 4.5에서 0.30MCM/year, RCP 8.5에서 -0.47MCM/year의 증감율을 보였다. 연간 강수량 대비 실제증발산의 비율의 추세분석 결과, RCP 4.5에서는 홍수기에는 0.014%/year, 비홍수기에는 0.027%/year의 증가율을 보이며 거의 변화가 없는 추세를 확인할 수 있었다. RCP 8.5의 홍수기에는 -0.042%/year, 비홍수기에서는 0.167%/year의 증감율을 보이며 홍수기에는 실제증발산에 비해 강수량의 증가가 확연히 보였으며 비홍수기에는 강수량에 비해 실제증발산의 증가가 뚜렷이 확인되었다. RCP 8.5에서 비홍수기의 강수량 대비 실제증발산의 증가가 갈수량의 감소로 반영된 것을 확인할 수 있었다. 미래기간의 RCP 4.5/8.5에서 실제증발산의 증가로 인하여 강수량이 증가함에 따라 유입량이 증가함에도 불구하고 갈수량의 증가로 이어지지 않았다. 미래 갈수량의 감소는 하천의 건전성과 이수안전도의 위협이 될 수 있다.

• Korean Journal of Cognitive Science
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• v.30 no.3
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• pp.105-132
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• 2019

This study quantitatively analyzed the speeches of the former 8 Presidents of the Republic of Korea. Unlike the previous studies, this study analyzed both the content word and the functional word related to the psychological phenomenon. In Study 1, six language style indicators such as clout, authenticity, presidentiality, cognitive complexity, femininity, and psychological health were developed. Also, as presidential speeches have been made recently, authenticity, presidentiality, psychological health tended to increase, but cognitive complexity tended to decrease. These tendencies were supported by linear trend analysis. The linguistic differences were distinct not only among individual presidents but also by groups based on the political orientation of the president. In the progressive presidential speech, more clout, cognitive complexity, femininity were observed. In contrast, more authenticity and presidentiality were observed in the conservative presidential speech. In Study 2, it was demonstrated whether the developed language style indicators show reliability in the most recent President's speeches. Finally, it was discussed that the relationship between language style indicators, fitness of the political tendency between the regime and the general public since 2000s, and the characteristics of femininity indicator.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2023.05a
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• pp.121-122
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• 2023

As containerized maritime transport began in earnest, the size of container ships has steadily increased, and recently, the operation of 24,000 TEU-class vessels has become regular. However, concerns about the efficiency and productivity of such mega container ships from a port operational perspective have continued to be raised. The 10^th Busan International Port Conference requested an in-depth study on the trends of container ship enlargement by analyzing the order status of ultra-large container ships from major global liners. Generally, the factor that drives the upsizing of ships is the realization of economies of scale that lowers transportation costs per TEU, which leads to a higher level of cost reduction per unit transportation compared to the increase in fuel consumption due to transporting large amounts of cargo with a single ship. However, it is necessary to examine whether this trend of container vessel enlargement is feasible for port operations. To this end, this study compares and analyzes the productivity and efficeiency of different ship sizes to evaluate the effect of ship size on port operations.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2023.11a
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• pp.72-73
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• 2023

As containerized maritime transport began in earnest, the size of container ships has steadily increased, and recently, the operation of 24,000 TEU-class vessels has become regular. However, concerns about the efficiency and productivity of such mega container ships from a port operational perspective have continued to be raised. The 10th Busan International Port Conference requested an in-depth study on the trends of container ship enlargement by analyzing the order status of ultra-large container ships from major global liners. Generally, the factor that drives the upsizing of ships is the realization of economies of scale that lowers transportation costs per TEU, which leads to a higher level of cost reduction per unit transportation compared to the increase in fuel consumption due to transporting large amounts of cargo with a single ship. However, it is necessary to examine whether this trend of container vessel enlargement is feasible for port operations. To this end, this study compares and analyzes the productivity and efficeiency of different ship sizes to evaluate the effect of ship size on port operations.