• Structural Engineering and Mechanics
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• v.39 no.4
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• pp.465-498
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• 2011

Concrete structures are generally cracked in flexural tension at working loads. Concrete beams with asymmetric section details and crack patterns exhibit different flexural rigidity depending upon the sense of the applied flexural moment. In this paper, three different models, having the same natural period, of such SDOF bilinear dynamical systems have been proposed. The Model-I and Model-II have constant damping coefficient, but the latter is characterized by two stiffness coefficients depending upon the sense of vibration amplitude. The Model-III, additionally, has two damping coefficients as well. In this paper, the dynamical response of Model-III to sinusoidal loading has been investigated and compared with that of Model-II studied earlier. It has been found that Model-III exhibits regular and irregular sub-harmonics, jump phenomena and strong sensitivity to initial conditions, forcing frequency, system period as well as the sense of peak sinusoidal force. The constant sustained load has been found to affect the natural period of the dynamical system. The predictions of Model-I have been compared with those of the approximate linear model adopted in present practice. The behaviour exhibited by different models of the SDOF cracked elastic concrete structures under working loads and the theoretical and practical implications of the approach followed have been critically evaluated.

• Journal of architectural history
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• v.27 no.2
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• pp.17-28
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• 2018

This study explores the space and society of Seorin-bang(瑞麟坊), using the Hanseong-bu family registry from the Gwangmu period to demonstrate the urban organizational units used during the late Joseon dynasty known as Seo(署)-Bang(坊)-Gye(契)-Dong(洞)-Tong(統)-Ho(戶). It seeks to examine how Seorin-bang's space and society changed with time. First, the study offers approximate demarcation for Gye and Dong through spatial verification of Bang-Gye-Dong-Tong-Ho of Seorin-bang in late Joseon Dynasty, whose precise locations were formerly undetermined. Second, it explores the relationships between Bang-Gye-Dong-Tong-Ho which has been widely understood to be hierarchical by previous studies, and classifies the relationship dynamics between Gye and Dong into four types. Third, the study finds that Seorin-bang retained much of its urban structure including roads, plots, and streams and maintained stable population distribution under the Japanese colonial rule, and continuously served as place of residency for many throughout the Gwangmu period. This study has major implications in that it illustrates space and society of Seorin-bang by converting the family registry from the late Joseon Dynasty into spatial data, and observes its changes subsequent to the Japanese colonial rule.

• Journal of the Earthquake Engineering Society of Korea
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• v.12 no.1
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• pp.79-87
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• 2008

Seismic performance evaluation of structure requires an estimation of the structural performance in terms of displacement demand imposed by earthquakes on the structure. Incremental Dynamic Analysis(IDA) is a analysis method that has recently emerged to estimate structural performance under earthquakes. This method can obtained the entire range of structural performance from the linear elastic stage to yielding and finally collapse by subjecting the structure to increasing levels of ground acceleration. Most structures are expected to deform beyond the limit of linearly elastic behavior when subjected to strong ground motion. The nonlinear response history analysis(NRHA) among various nonlinear analysis methods is the most accurate to compute seismic performance of structures, but it is time-consuming and necessitate more efforts. The nonlinear approximate methods, which is more practical and reliable tools for predicting seismic behavior of structures, are extensively studied. The uncoupled modal response history analysis(UMRHA) is a method which can find the nonlinear reponse of the structures for ESDF from the pushover curve using NRHA or response spectrum. The direct spectrum analysis(DSA) is approximate nonlinear method to evaluate nonlinear response of structures, without iterative computations, given by the structural linear vibration period and yield strength from the pushover analysis. In this study, the practicality and the reliability of seismic performance of approximate nonlinear methods for incremental dynamic analysis of mixed building structures are to be compared.

• Korean Journal of Construction Engineering and Management
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• v.22 no.6
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• pp.107-119
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• 2021

Recently, interest in remodeling apartment houses has been increasing due to problems such as a lack of parking spaces for old apartment houses. However, no method was suggested to predict the construction period of the apartment remodeling project. Unlike general apartment new construction, apartment remodeling construction involves demolition or reinforcement work, so a realistic remodeling construction period calculation plan differentiated from the existing construction period should be proposed. Therefore, this study intends to present a model for deriving the construction period of the underground parking lot of the apartment remodeling construction. Each construction period was calculated based on 19 activities of underground parking lot remodeling work through review of previous studies and expert advice. Activity's workload data and productivity data were derived to calculate the construction period, and the number of inputs and equipment inputs by Activity were determined to correct the productivity data. The construction period of Activity was calculated using the derived data, and the criteria for calculating the overlapping period for each Activity were presented to enable realistic construction period and scheduled schedule. As a result of predicting the accuracy of the construction period through the verification of the case complex, it is expected that it will be possible to predict the approximate construction period of the underground parking lot of the apartment remodeling construction in the future.

• Toxicological Research
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• v.28 no.2
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• pp.99-102
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• 2012

Bee venom (Apis mellifera L. BV) has been used as a cosmetic ingredient for anti-ageing, anti-inflammatory and antibacterial functions. The aim of this study was to evaluate the acute toxicity after a single dermal administration of BV, BV was administered to 2 groups of Sprague-Dawley (SD) male and female rats (5 animals/group) at doses of 0 and 1,500 mg/kg body weight (BW). Mortality, clinical signs, body weight changes and gross findings were continually monitored for 15 days following the single dose. There were no unscheduled deaths in any groups during the study period. No BV related clinical signs and body weight changes were observed in any groups during the study period. There were no abnormal gross findings at necropsy on day 15 after the treatment. On the basis of the above results, it was concluded that there were no treatment-related effect on mortality, clinical signs, body weight changes and gross findings in SD rats treated with a single dermal dose of BV at dose of 1,500 mg/kg BW. Therefore, the approximate lethal dose of BV was considered to be over 1,500 mg/kg/day for both sexes of rats. BV may provide a developmental basis for a cosmetic ingredient or external application for topical uses.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.48 no.5
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• pp.739-744
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• 2015

The sexual maturation and spawning time of female ocean sunfish Mola mola in Korean waters were studied by observing the gonads histologically. Specimens were purchased in a fish market in October 2013 and May, June, and October 2014. Nine females (total length 100-250 cm, gonad weight 31-3,470 g) and one male (total length 131 cm, gonad weight 60 g) were studied. Histologically, the ovaries became active in May and spawning began in July and continued until October. In July, mature oocytes and yolk globule stage oocytes were observed; parts of the gonad showed traces of spawning, while others had degenerated and absorbed any oocytes. By October, many oocytes had degenerated and been absorbed. Therefore, the approximate spawning period of ocean sunfish is from July to October based on histological changes in the gonads. The asynchronous oocyte development suggests that the ocean sunfish is a multiple spawner, as reported previously. The catch distribution data suggest that the waters around Jeju Island are a sunfish spawning area.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.5
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• pp.1069-1075
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• 1999

The sterilization was attempted to improve the quality deterioration of soybean paste during its storage. For this experiment, soybean paste was sterilized at 80oC for 30 minutes and stored during 6 months at 15oC and 30oC, respectively. The total approximate composition contents were moisture 52.5%, crude protein 11.94%, crude fat 2.0%, amino nitrogen 413.3mg%, sodium chloride 11.61% and ash 15.5%. According to the increase of storage period, pH was decreased gradually because of the increase of organic acids by the metabolism of microorganisms and the acid accumulation by acid forming bacteria, but titratable acidity was increased during storage. Amino nitrogen was rapidly increased for the first one or two month storage period and maintained as the same level for the rest of them. Each amino acid contents of soybean paste, which were glutamic acid, tryptophan, proline, arginine, and aspartic acid, had much higher level than others. In color changes sterilized soybean paste(SSP) was much lower than that of raw ones(RSP). Hunter L and b values on the surface of soybean paste were decreased during storage, and the decreasing levels were higher at 30oC than at 15oC. Hunter a value, however, was increased a little in the initial storage, and thereafter it was decreased. Lactic acid bacteria, yeasts, and molds were disappeared completely by the sterilization. However, the bacteria of aerobes and anaerobes were not disappeared by this processing.

• Journal of Communications and Networks
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• v.5 no.3
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• pp.249-257
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• 2003

Ring networks are very commonly exploited among local area and metropolitan area networks (LAN/MAN), whereas cells or small fixed-size packets are widely used in synchronized ring networks. In this paper, we present an analytical method for evaluating the delay-throughput performance of a MAC protocol with multiple self-tokens in a slotted ring network under uniform traffic. In our analysis, we introduce the stationary probability, which indicates the number of packets in a node. Also, it is assumed that each node has a sufficiently large amount of self-tokens, and a slotted ring has the symmetry. The analytical results with respect to delay-throughput performance have similar values to computer simulated ones. Furthermore, in order to achieve fair access under non-uniform traffic, we propose an adaptive MAC protocol, where the number of self-tokens in a node dynamically varies, based on the number of packets transmitted within a specified period. In the proposed protocol, when the number of packets transmitted by a node within a specified period is larger than a specified threshold, the node decreases the number of self-tokens in a per-node distributed method. That results in creating free slots in the ring, thus all nodes can obtain an equal opportunity to transmit into the ring. Performance results obtained by computer simulation show that our proposed protocol can maintain throughput fairness under non-uniform traffic.

• Structural Engineering and Mechanics
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• v.85 no.5
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• pp.655-664
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• 2023

Reinforced concrete (RC) shear wall structures are one of the most widely used structural systems to resist seismic loading all around the world. Although there have been several efforts to provide conceptually simple procedures to reasonably assess the seismic demands of structures over recent decades, it seems that lesser effort has been put on a number of structural forms such as RC shear wall structures. Therefore, this study aims to represent a simple linear response spectrum-based method which can acceptably predict the nonlinear displacements of a non-ductile RC shear wall structure subjected to an individual ground motion record. An effective period and an equivalent damping ratio are introduced as the dynamic characteristics of an equivalent linear SDOF system relevant to the main structure. By applying the fundamental mode participation factor of the original MDOF structure to the linear spectral response of the equivalent SDOF system, an acceptable estimation of the nonlinear displacement response is obtained. Subsequently, the accuracy of the proposed method is evaluated by comparison with another approximate method which is based on linear response spectrum. Results show that the proposed method has better estimations for maximum nonlinear responses and is more utilizable and applicable than the other one.

• Journal of Preventive Medicine and Public Health
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• v.42 no.4
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• pp.267-273
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• 2009

Objectives : To compare the performance of three comorbidity measurements (Charlson comorbidity index, Elixhauser s comorbidity and comorbidity selection) with the effect of different comorbidity lookback periods when predicting in-hospital mortality for patients who underwent percutaneous coronary intervention. Methods : This was a retrospective study on patients aged 40 years and older who underwent percutaneous coronary intervention. To distinguish comorbidity from complications, the records of diagnosis were drawn from the National Health Insurance Database excluding diagnosis that admitted to the hospital. C-statistic values were used as measures for in comparing the predictability of comorbidity measures with lookback period, and a bootstrapping procedure with 1,000 replications was done to determine approximate 95% confidence interval. Results : Of the 61,815 patients included in this study, the mean age was 63.3 years (standard deviation: ${\pm}$10.2) and 64.8% of the population was male. Among them, 1,598 2.6%) had died in hospital. While the predictive ability of the Elixhauser's comorbidity and comorbidity selection was better than that of the Charlson comorbidity index, there was no significant difference among the three comorbidity measurements. Although the prevalence of comorbidity increased in 3 years of lookback periods, there was no significant improvement compared to 1 year of a lookback period. Conclusions : In a health outcome study for patients who underwent percutaneous coronary intervention using National Health Insurance Database, the Charlson comorbidity index was easy to apply without significant difference in predictability compared to the other methods. The one year of observation period was adequate to adjust the comorbidity. Further work to select adequate comorbidity measurements and lookback periods on other diseases and procedures are needed.