• Earthquakes and Structures
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• v.4 no.5
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• pp.557-585
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• 2013

The recent huge earthquake ground motion records in Japan result in the reconsideration of seismic design forces for nuclear power stations from the view point of seismological research. In addition, the seismic design force should be defined also from the view point of structural engineering. In this paper it is shown that one of the occurrence mechanisms of such large acceleration in recent seismic records (recorded in or near massive structures and not free-field ground motions) is due to the interaction between a massive building and its surrounding soil which induces amplification of local mode in the surface soil. Furthermore on-site investigation after earthquakes in the nuclear power stations reveals some damages of soil around the building (cracks, settlement and sand boiling). The influence of plastic behavior of soil is investigated in the context of interaction between the structure and the surrounding soil. Moreover the amplification property of the surface soil is investigated from the seismic records of the Suruga-gulf earthquake in 2009 and the 2011 off the Pacific coast of Tohoku earthquake in 2011. Two methods are introduced for the analysis of the non-stationary process of ground motions. It is shown that the non-stationary Fourier spectra can detect the temporal change of frequency contents of ground motions and the displacement profile integrated from its acceleration profile is useful to evaluate the seismic behavior of the building and the surrounding soil.

• Korean Journal Plant Pathology
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• v.14 no.5
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• pp.433-439
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• 1998

The studies on the ecology of virus disease on Chinese cabbage (Brassica campestris subsp. pekinensis) cultivated in alpine area of Kangwon province during summer season to analyse its influence on damage and develope a prediction model were performed from 1993 to 1997. Virus disease on Chinese cabbage occurring in the alpine area showed various symptom types and among there, necrotic spots and dwarf were mainly detected. The disease was increased from early August and continued mid September in every year. The occurrence of virus disease was the highest in 1994 with 20.5%, and the number of aphid vectors were also the highest during the same period. The number of aphids in the alpine areas showed twice peaks every year. For the analysis of damage by virus infection, the infection and injured ratio of all treatments were more than 90% and 80%, respectively. The most important factor for the occurrence of virus disease on Chinese cabbage was temperature. Factors influencing the development of the viral disease in the alpine area were maximum temperature and number of aphid vectors.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.233-242
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• 2009

Based on the data obtained from field investigation and soil testing to slope hazards occurrence section and non-occurrence section in crystalline rocks like gneiss, granite, and so on, a prediction model was developed by the use of a decision tree model. The classification standard of the selected prediction model is composed of the slope angle, the coefficient of permeability and the void ratio in the order. The computer program, SHAPP ver. 1.0 for prediction of slope hazards around an important national facilities using GIS technique and the developed model. To prove the developed prediction model and the computer program, the field data surveyed from Jumunjin, Gangneung city were compared with the prediction result in the same site. As the result of comparison, the real occurrence location of slope hazards was similar to the predicted section. Through the continuous study, the accuracy about prediction result of slope hazards will be upgraded and the computer program will be commonly used in practical.

• Childhood Kidney Diseases
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• v.4 no.1
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• pp.11-16
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• 2000

Purpose. Urinary calcium excretion using a 24-hr urine colledtion has been used for the diagnosis of hypercalciuria up to now. But It takes a lot of time and costs much. We have investigated on a more simple method for screening of hypercalciuria in children. Methods: We had retrospectively analyzed sodium, potassium, calcium and creatinine in spot urine of eighty-four patients with urinary symptoms from May 1998 to July 1998 in Korea university Guro hospital and compared the urinary Ca/Cr ratio with the Nin ratio. Using a urinary Nan ratio >2.68 as a cutoff value in predicting the occurrence of hypercalciuria, we measured its sensitivity, specificity, positive predictive value and the negative predictive value. Results: A direct relationship was found between urinary Na/K and Ca/Cr ratio (r=0.496, P<0.001, Ca/Cr : Na/K x 0.0167+0.061). Using a urinary Na/K ratio >2.68 as a cutoff value in predicting the occurrence of hypercalciuria, its sensitivity was found to be $100\%$ and its specificity $54.5\%$. The positive predictive value was $37.5\%$ and the negative predictive value $100\%$. Conclusions : Spot urine Na/K ratio is a valuable test for the screening of hypercalciuria in children.

• Resources Recycling
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• v.27 no.6
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• pp.59-67
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• 2018

Efflorescence is a white deposit of powders in the surface of cement concrete which can also occur in geopolymers. Efflorescence occurs when sodium ions in alkali activator react with atmospheric carbon dioxide to form sodium carbonate components. In this study, we investigated whether the secondary efflorescence can be reduced by controlling the Na/Al mole ratio or by changing the curing temperature and heat curing time in fly ash-based geopolymers. The 28 days compressive strength in geopolymers having Na/Al ratio of 1.0 was higher than geopolymers having Na/Al ratio of 0.8. The strength increased with the increasing curing temperature and longer heat curing time. On the other hand, efflorescence was lower when the curing temperature was high and the heat curing time was longer in the geopolymers having Na/Al ratio of 1.0. The geopolymers having Na/Al ratio of 0.8 showed accelerated efflorescence occurrence than the geopolymers having Na/Al ratio of 1.0. In order to reduce the occurrence of the secondary efflorescence of fly ash-based geopolymers, it will be advantageous to maintain the Na/Al ratio at 1.0, increase the curing temperature, and lengthen the heating curing time.

• Tuberculosis and Respiratory Diseases
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• v.84 no.2
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• pp.125-133
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• 2021

Background: The coronavirus disease (COVID-19) can manifest in a range of symptoms, including both asymptomatic systems which appear nearly non-existent to the patient, all the way to the development of acute respiratory distress syndrome (ARDS). Specifically, COVID-19-associated pneumonia develops into ARDS due to the rapid progression of hypoxia, and although arterial blood gas analysis can assist in halting this deterioration, the current environment provided by the COVID-19 pandemic, which has led to an overall lack of medical resources or equipment, has made it difficult to administer such tests in a widespread manner. As a result, this study was conducted in order to determine whether the levels of oxygen saturation (SpO₂) and the fraction of inhaled oxygen (FiO₂) (SF ratio) can also serve as predictors of ARDS and the patient's risk of mortality. Methods: This was a retrospective cohort study conducted from February 2020 to Mary 2020, with the study's subjects consisting of COVID-19 pneumonia patients who had reached a state of deterioration that required the use of oxygen therapy. Of the 100 COVID-19 pneumonia cases, we compared 59 pneumonia patients who required oxygen therapy, divided into ARDS and non-ARDS pneumonia patients who required oxygen, and then investigated the different factors which affected their mortality. Results: At the time of admission, the ratios of SpO₂, FiO₂, and SF for the ARDS group differed significantly from those of the non-ARDS pneumonia support group who required oxygen (p<0.001). With respect to the predicting of the occurrence of ARDS, the SF ratio on admission and the SF ratio at exacerbation had an area under the curve which measured to be around 85.7% and 88.8% (p<0.001). Multivariate Cox regression analysis identified that the SF ratio at exacerbation (hazard ratio [HR], 0.916; 95% confidence interval [CI], 0.846-0.991; p=0.029) and National Early Warning Score (NEWS) (HR, 1.277; 95% CI, 1.010-1.615; p=0.041) were significant predictors of mortality. Conclusion: The SF ratio on admission and the SF ratio at exacerbation were strong predictors of the occurrence of ARDS, and the SF ratio at exacerbation and NEWS held a significant effect on mortality.

• Korean Journal of Weed Science
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• v.8 no.2
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• pp.133-140
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• 1988

One hundred and one noxious weeds on cultivated land of Taiwan were investigated for the occurrence of "Kranz" leaf anatomy and activities of PEP carboxylase and $C_4$ acid decarboxylating enzymes : NADP-malic enzyme, NAD-malic enzyme, PEP carboxykinase. Based on the leaf anatomy and a/b chlorophyll ratio, twenty-seven species exhibit "Kranz" type leaf anatomy, and seventy-four species were found without it. Among the species investigated, Digitaria radicosa (Presl) Miq., Leptochloa chinensis (L.) Nees, and Sporobolus fertilis (Steud.) W. D. Clayton in the Gramineae were first recorded as $C_4$ plants. Twenty-sven species of "Kranz" type leaf anatomy, include those of monocotyledon ; sixteen species in Gramineae, six species in Cyperaceae. Those of dicotyledon ; two species each in Euphorbiaceae and Amaranthaceae and one species in Portulacaceae. The subtype of fourteen previously uninvestigated species among twenty-seven species were further determined. The properties of the three decarboxylating enzyme from representative species were also characterized.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.3
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• pp.202-208
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• 1997

The knocking is one of major parameters to improve engine performance in a spark ignition engine. Many researches have been carried out to identify them using cylinder pressure, vibration signal and so on. In the present study, measurement and analysis was conducted to set up the criteria of knock occurrence by using microphone signal. Cylinder pressure was measured for the reference signal of knocking. It has been observed that resonance frequencies of pressure wave are nearly independent of engine operating conditions such as engine speed, air fuel ratio, load and octane number of fuel within to limited experimental conditions. SDBP(sum of different band-pass data) method using resonance frequency of knock was proposed for estimating knock intensity. SDBP method is superior to identify knock occurrence and its intensity in case of sound pressure measurement.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.957-960
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• 2006

In order to predict the accumulated damages by cyclic freeze-thaw, a regression analysis by the Response Surface Method (RSM) is used. RSM has merits when the other probabilistic simulation techniques can not guarantee the convergence of probability of occurrence or when the others can not differentiate the derivative terms of limit state functions, which are composed of random design variables in the model of complex system or the system having higher reliability. For composing limit state function, the important parameters for cyclic freeze-thaw-deterioration of concrete structures, such as water to cement ratio, entrained air pores, and the number of cycles of freezing and thawing, are used as input parameters of RSM. The predicted results of relative dynamic modulus and residual strains after 300 cycles of freeze-thaw for specimens show very good agreements with the experimental results. The RSM result can be used to predict the probability of occurrence for designer specified critical values. Therefore, it is possible to evaluate the life cycle management of concrete structures considering the accumulated damages by the cyclic freeze-thaw by the use of proposed prediction method.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.141-143
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• 2003

The aim of this study is to evaluate the susceptibility of landslides at Clicap area, Indonesia , using a Geographic Information System (GIS). Landslide locations were identified from field surveys. The topographic and geological map were collected and constructed into a spatial database using GIS. The factors that influence landslide occurrence, such as slope, aspect and curvature of topography, were calculated from the topographic database and lihology and fault was extracted from the geological database. Then landslide susceptibility was analyzed using the landslide-occurrence factors by likelihood methods. The results of the analysis were verified using the landslide location data. The GIS was used to analyze the vast amount of data efficiently . The results can be used to reduce associated hazards, and to plan land use and construction.