• Composites Research
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• v.22 no.5
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• pp.30-36
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• 2009

The failure strengths and modes in carbon fiber reinforced polymeric composites, with two serial bolt-fastened composite joints, were investigated to evaluate the typical joint configurations of composite components. The parametric studies were performed experimentally at room temperature dry and elevated temperature wet, $82.2^{\circ}C$ on several different laminate configurations. Based on the experimental data presented, two basic load-displacements curves are observed. Each failure mode has the characteristic curve. It is showed that the bearing failure mode occurs in elevated temperature wet condition. It is analysed that the strength of bearing failure mode is not highly depending on the effective modulus of specimen. The failure strength at elevated temperature wet is decreased by the cause of interfacial deterioration between fiber and matrix with moisture absorption.

• Coupled systems mechanics
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• v.12 no.2
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• pp.127-149
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• 2023

A theoretical method is developed to analyze the free vibration of an elastic annular plate in contact with an ideal liquid. The displacement potential functions of the contained liquid are expressed as a combination of the Bessel functions that satisfy the Laplace equation and the liquid boundary conditions. The compatibility condition along the interface between the annular plate and the contained liquid is taken into account to consider the fluid-structure coupling. The dynamic displacement of the wet annular plate is assumed to be a combination of dry eigenfunctions, allowing for prediction of the natural frequencies using the Rayleigh-Ritz method. The study investigates the effect of radial liquid boundary conditions on the natural frequencies of the wet annular plate, considering four types of liquid bounding: outer container bounded, outer and inner bounded, inner bounded, and radially unbounded. The proposed theoretical method is validated by comparing the predicted wet natural frequencies with those obtained from finite element analysis, showing excellent accuracy. The results indicate that the radial liquid bounding effect on the natural frequencies is negligible for the axisymmetric vibrational mode, but relatively significant for the mode with one nodal diameter (n =1) and no nodal circle (m' = 0). Furthermore, the study reveals that the wet natural frequencies are the largest for the plate with an inner bounded cylinder among the radial liquid boundary cases, regardless of the vibration mode.

• Asian-Australasian Journal of Animal Sciences
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• v.9 no.3
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• pp.319-329
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• 1996

During the monsoon in Bangladesh, the possibility of preserving wet ($700g\;H_2O$) straw by urea (50 g/kg straw DM) with or without polythene cover has been studied. The quality of preserved straw (PS) in terms of colour, smell and fungal infestation were recorded. Nutritive value of the PS was compared to that of a dry straw (DS) in two separate feeding trials on growing bulls (about 290 kg) without (Expt. 1) or with (Expt. 2) concentrate supplements. Over 96% of the wet straw was excellently preserved for over 5 months when covered with polythene in horizontal heaps (of appx. 4 tons). Whereas only 33% of the straw was well preserved in the uncovered (dome shaped) heaps (of approximately 9.5 tons). Each ton of wet straw costed Tk. 1413 and its preservation cost incurred Tk. 345. Urea preservation increased the crude protein content (95 vs. 50 g/kg), dry matter (DM) degradability at all (8, 16, 24, 48, 72 and 96) hours of incubation and at 48 hours, DM degradability (%) were 45 and 25 respetively for the PS and the DS. When fed alone, DM intake (75 vs. $106g/kg\;W^{0.75}/d$), total microbial N yield (27 vs. 54 g/d) and growth rate (-379 vs. 283 g/d) were higher (p < 0.01) in the PS than the DS. Supplementation of concentrate reduced the straw DM intake both in the DS ($51g/kg\;W^{0.75}/d$) and the PS ($958g/kg\;W^{0.75}/d$), but the substitution rate (SR%) was higher in the PS (42) than the DS (27). Higher substitution rate was probably responsible for the reduction in the differences between the DS and PS in their nutrient digestibilities, total microbial N yield (62 vs. 64 g/d) and growth rate(669 vs 339 g/d) when supplemented with concentrate. On 28th day of Expt. 2, feeding PS from one of the polythene covered heaps resulted nervous disorder due to unknown reason(s). Further studies on the effect of size and shape of heap on the preservation quality need to be determined.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.3
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• pp.262-272
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• 2005

This study was undertaken to obtain design concentrations for the natural system treating stream water flowing into estuarine lake(Sapgyo). This lake has three major, so called, national-class streams: one is Gokgyo flowing through two medium-size municipal areas and the others are Muhan and Sapgyo placed in mostly rural area nested with some small towns. The results of three year's investigation showed big changes in water quality during the period between dry and wet seasons. Nitrogen concentration usually decreases as the flow rate increases. The change of phosphorus concentration in Gokgyo was the same pattern as nitrogen, but in other two streams it was inversely related with flow rates. This is probably due to the chemical property of the particles washed out from the different stream basins during wet season. It was found that about 40 to 60% of the total nitrogen are in soluble form and on average, 35% of the total phosphorus consists of dissolved-P. Representative concentration of these streams has to be separately determined based on dry and wet season. TDS and SS could be indicating parameters useful to depict and characterize a change of water quality with respect to flow rate because their measurement is easy and also includes a small analytical error. TDS values measured during dry season are related with high nitrogen concentration while during wet season, SS values effectively reflect a high concentration of phosphorus. For design purpose, cumulative concentration distribution graph presented in this paper can be directly or indirectly applied to other streams through a brief comparative and verificative study.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.11
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• pp.1596-1602
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• 2012

Eight rice cultivars grown in Korea were analyzed to investigate the quality of flour prepared using wet and dry grinding methods. The hardness of the kernel was related with starch damage following dry grinding but not following wet grinding. Although Chenmaai had the hardest steeped kernel, its flour exhibited minimal starch damage, a lower water absorption index (WAI), and a smaller difference between the RVA properties of wet and dry ground flour. However, Seolgan and Suweon517 are soft grains, and their flours had more starch damage and a higher WAI. In general, soft kernels produce better grinding characteristics. However, our wet grinding results indicated that grain hardness was not the main factor affecting the grinding characteristics. Even Chenmaai, with its hard kernels, had good grinding characteristics, whereas the softer kernels of Seolgan and Suweon517 did not show the appropriate grinding characteristics.

• Journal of Conservation Science
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• v.25 no.2
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• pp.161-169
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• 2009

The objective of this study was to investigate stability of Korean Paper(Hanji) which is being sold in the Korean markets according to aging treatment. In order to know the aging characteristics, the optical and mechanical properties of before and after wet and dry-heat aging treatment were examined. The optical and mechanical properties were shown higher reduction in the dry-heat aging treatment compared to the wet-heat aging treatment. The Soonji (pure mulberry Hanji) made from black mulberry bast pulp was shown a great reduction of the brightness and whiteness, and increase of the opacity in the aging treatment. On the other hand, in case of mechanical properties, the breaking length of Soonji made from white mulberry bast pulp was significantly higher than that of the others, and the tensile strength was shown drastic reduction in according to Soonji made from black mulberry bast pulp in the aging treatment. The burst strength of Soonji made from black and white mulberry bast pulp was shown the similar value in the wet-heat aging treatment. The folding endurance of Soonji made from white mulberry bast pulp was significantly higher than that of others before and after aging treatment. Consequently, Hanji was affected sensitive in the temperature compared to the humidity. Meanwhile, the density and color of the chinese ink was no significant changes before and after wet and dry-heat aging treatment.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.5
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• pp.880-887
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• 2004

This study was carried out to examine the effect of added Doenjang on wheat flour dough and gluten rheological properties using Micro-extensigraph method and correlation between factors relating with Doenjang or dough rheology and bread Quality. There were big differences in pretense activity and free amino acid contents among seven commercial Doenjangs. The addition of Doenjang to wheat flour dough required increased mixing time for gluten development. Dry gluten content increased significantly with addition of less than 5.0% of Doenjang powder. As the amount of Doenjang powder increased, dough peak force decreased and extensibility increased up to a certain level an then decreased, producing the weak dough. This phenomena was seen more obviously in wet gluten than wheat flour dough. Especially, the Doeniang having high pretense activity and high cystein content, caused highly extensible weak dough resulting in bread with high loaf volume and tender texture at the levels of 2.5% added Doenjang. Increase of dry gluten content and extensibility of wheat flour dough or wet gluten positively correlated (r=0.76, 0.91, 0.93), with loaf volume and negatively with hardness values, respectively. Therefore, it was concluded that improvement of bread quality with Doenjang resulted from increase of gluten content and dough extensibility.

• Journal of Korea Water Resources Association
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• v.56 no.9
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• pp.529-541
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• 2023

Due to the growing concern over forecasting extreme weather events such as droughts caused by climate change, there has been a rising interest in seasonal meteorological forecasts that offer ensemble predictions for the upcoming seven months. Nonetheless, limited research has been conducted in South Korea, particularly in assessing their effectiveness at the catchment-scale. In this study, we assessed the accuracy of ECMWF's seasonal forecasts (including precipitation, temperature, and evapotranspiration) for the period of 2011 to 2020. We focused on 12 multi-purpose reservoir catchments and compared the forecasts to climatology data. Continuous Ranked Probability Skill Score method is adopted to assess the forecast skill, and the linear scaling method was applied to evaluate its impact. The results showed that while the seasonal meteorological forecasts have similar skill to climatology for one month ahead, the skill decreased significantly as the forecast lead time increased. Compared to the climatology, better results were obtained in the Wet season than the Dry season. In particular, during the Wet seasons of the dry years (2015, 2017), the seasonal meteorological forecasts showed the highest skill for all lead times.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.5B
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• pp.397-408
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• 2009

In this study, a stochastic precipitation generation framework for simultaneous simulation of daily precipitation at multiple sites is presented. The precipitation occurrence at individual sites is generated using hybrid-order Markov chain model which allows higher-order dependence for dry sequences. The precipitation amounts are reproduced using Anscombe residuals and gamma distributions. Multisite spatial correlations in the precipitation occurrence and amount series are represented with spatially correlated random numbers. The proposed model is applied for a network of 17 locations in the middle of Korean peninsular. Evaluation statistics are reported by generating 50 realizations of the precipitation of length equal to the observed record. The analysis of results show that the model reproduces wet day number, wet and dry day spell, and mean and standard deviation of wet day amount fairly well. However, mean values of 50 realizations of generated precipitation series yield around 23% Root Mean Square Errors (RMSE) of the average value of observed maximum numbers of consecutive wet and dry days and 17% RMSE of the average value of observed annual maximum precipitations for return periods of 100 and 200 years. The provided model also reproduces spatial correlations in observed precipitation occurrence and amount series accurately.

• Water Engineering Research
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• v.2 no.2
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• pp.139-148
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• 2001

The teleconnections between El Nino/Southern Oscillation (ENSO) and droughts in Korea and the continental United States(U.S.) are investigated using cross analysis. For this purpose, monthly ENSO data and Palmer Drought Severity Index (PDSI) for Korea and for seven states in the U.S. are used. This study shows that there are significant statistical associations between ENSO indices and PDSI for Korea; however, the associations are very weak. It is found that dry conditions in Korea are positively correlated with El Nino, while wet conditions with La Nina. SOI, SSt in the Nino 4 and Ship track 6 regions among ENSO indices are more strongly correlated with PDSI than the other ENSO indices when using the original standardized data, but the SST Nino 3, SST Nino 4, and Darwin SSP exhibit abetter correlations with PDSI when using filtered data to be removed autocorrelation components of the original standardized data. The response time lag for maximum correlation between ENSO indices and PDSI appears to be affected by filtering the data. This is expecially true for Korea than for state analyzed in U.S. In addition, it is found that the PDSI in the continental U.S. is more strongly correlated wiht ENSO than in Korea. Furthermore, in analyzing the El Nino and La Nina aggregate composite data, it is found that the dry anomalies in Korea occur from the year following El Nino to about tow years after while the wet anomalies occur from La Nina year for a period of about two years.