• Transactions of Materials Processing
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• v.12 no.4
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• pp.408-413
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• 2003

Dies may have to be replaced for a number of reasons, such as changes in dimensions due to die wear or plastic deformation, deterioration of the surface finish, break down of lubrication and cracking or breakage. In this paper, die cooling methods have been suggested to improve die service life considering die wear and plastic deformation in hot forging process. The yield strength of die decreases at higher temperatures and is dependent on hardness. Also, to evaluate die life due to wear, modified Archard's wear model has been proposed by considering the thermal softening of die expressed in terms of the main tempering curve. It was found that the use of die with cooling hole was more effective than that of direct cooling method to increase the die service life for spindle component.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.862-865
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• 2012

유사량은 하천의 단면을 단위시간 동안 통과하는 토사의 양을 의미하며, 하천 구조물의 설계 및 유지관리를 위한 기본자료로 활용된다. 유사량은 하천 유역의 지형적인 특성과 기상요소에 영향을 받으며, 이를 규명하기 위한 많은 연구들이 수행되어 왔다. GIS기반의 유사량 예측모델로서 국내에서는 개정범용토양유실공식과 유사운송비(Sediment Delivery Ratio)를 이용하여 유역단위 유사량을 예측하는 연구가 이루어져왔다. Gavrilovi$\acute{c}$ 모델은 유역의 총 연유사량을 예측하고 토양침식의 정도를 정량화할 수 있는 경험적 모형으로 지질 및 토양, 지형조건, 기후인자(연평균 강우량, 연평균 온도), 토지이용의 6가지 입력변수로 구성되어 있다. 본 연구는 Gavrilovi$\acute{c}$ 모델의 국내 적용성을 검토하기 위한 것으로서, 왕숙천 유역을 대상으로 Gavrilovi$\acute{c}$ 모델을 적용하여 유사량을 산정해본 결과, 실측값을 약 20% 내외로 비교적 근사하게 추정할 수 있음을 알 수 있었다.

• Smart Structures and Systems
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• v.30 no.3
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• pp.239-243
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• 2022

We investigate the influence of nonlinear viscoelastic damping on the response of a cantilever sensor covered by piezoelectric layers in a symmetric or asymmetric configuration. We formulate an initial-boundary-value problem which consistently incorporates both geometric and material nonlinearities including the effect of viscoelastic damping which cannot be ignored for micro- and nano-mechanical sensor operation in a vacuum environment. We employ an asymptotic multiple-scales methodology to yield the system nonlinear frequency response near its primary resonance and employ a model-based estimation procedure to deduce the system damping backone curve from controlled experiments in vacuum. We discuss the effect of nonlinear damping on sensor applications for scanning probe microscopy.

• International conference on construction engineering and project management
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• 2015.10a
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• pp.294-298
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• 2015

In the United States, the completion of Construction Work Zone (CWZ) impact assessments for all federally-funded highway infrastructure improvement projects is mandated, yet it is regarded as a daunting task for state transportation agencies, due to a lack of standardized analytical methods for developing sounder Transportation Management Plans (TMPs). To circumvent these issues, this study aims to create a spatiotemporal modeling framework, dubbed "SWAT" (Spatiotemporal Work zone Assessment for TMPs). This study drew a total of 43,795 traffic sensor reading data collected from heavily trafficked highways in U.S. metropolitan areas. A multilevel-cluster-driven analysis characterized traffic patterns, while being verified using a measurement system analysis. An artificial neural networks model was created to predict potential 24/7 traffic demand automatically, and its predictive power was statistically validated. It is proposed that the predicted traffic patterns will be then incorporated into a what-if scenario analysis that evaluates the impact of numerous alternative construction plans. This study will yield a breakthrough in automating CWZ impact assessments with the first view of a systematic estimation method.

• Fire Science and Engineering
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• v.25 no.5
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• pp.93-99
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• 2011

In the present study, a numerical simulation was conducted to estimate the prediction performance of FDS on the carbon monoxide production in the under-ventilated compartment fires. Methane and heptane fires located in the a 2/5 scale compartment based on the ISO-9705 standard room was simulated using FDS Ver. 5.5. Through the comparison between the computed results and the earlier published experimental data, the performance of FDS was estimated on the predictions of the combustion gases concentration in the hot upper layer of the compartment and the effects of CO yield rate on the estimation of CO production at local points were analyzed. From the results, it was known that FDS Ver. 5.5, in which the two-step reaction mixture fraction model implemented, was more effective on the prediction of CO concentration compared to the previous FDS version. In addition, controlling CO yield rate made the predicted CO concentration get closer to the experimental data for the fires of the under-ventilated condition.

• Asian-Australasian Journal of Animal Sciences
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• v.28 no.4
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• pp.476-484
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• 2015

The objective of this study was to estimate genetic and phenotypic parameters for linear type traits, as well as milk yield (MY), fat yield (FY) and protein yield (PY) in 18,831 Holstein cows reared in 495 herds in Brazil. Restricted maximum likelihood with a bivariate model was used for estimation genetic parameters, including fixed effects of herd-year of classification, period of classification, classifier and stage of lactation for linear type traits and herd-year of calving, season of calving and lactation order effects for production traits. The age of cow at calving was fitted as a covariate (with linear and quadratic terms), common to both models. Heritability estimates varied from 0.09 to 0.38 for linear type traits and from 0.17 to 0.24 for production traits, indicating sufficient genetic variability to achieve genetic gain through selection. In general, estimates of genetic correlations between type and production traits were low, except for udder texture and angularity that showed positive genetic correlations (>0.29) with MY, FY, and PY. Udder depth had the highest negative genetic correlation (-0.30) with production traits. Selection for final score, commonly used by farmers as a practical selection tool to improve type traits, does not lead to significant improvements in production traits, thus the use of selection indices that consider both sets of traits (production and type) seems to be the most adequate to carry out genetic selection of animals in the Brazilian herd.

• Journal of Korea Water Resources Association
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• v.54 no.11
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• pp.915-924
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• 2021

In this study, the probability of exceeding capacity for 4 check dams in Muju mountain region have been estimated. From the results, optimum design of check dam and safety according to wild fire have been discussed. Reliability model has been established by using MSDPM for calculating debris yield to estimate the probability of exceeding capacity of check dam. Probability of exceeding capacity for 4 check dams has been estimated according to maximum rainfall intensity of return periods (10year, 50year, 100year, and 200year). It was found that 1 check dam of Samga-ri basin and 1 check dam of Jeungsan-ri basin were designed by overestimation and 61% and 47% of capacity should be reduced, respectively. Furthermore, probability of exceeding capacity according to burned area has been estimated and compared. It was found that check dam of Sanga-ri basin is the weakest for the wild fire effect in this study area.

• Korean Journal of Soil Science and Fertilizer
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• v.30 no.3
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• pp.209-225
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• 1997

Daily rainfalls and evaporations from copper pan measured in Suweon from 1964 to 1996 were figured respectively so that past soil moisture deficits can be understood clearly at a glance in relation to the characteristics of weather. Past drought intensities in Suweon were computed on the basis of Oh's 50mm pan model estimating drought in terms of daily, monthly shortage of evapotranspiration and growthless time fraction. Yearly differences in drought seem to result mainly from yearly differences in rainfall distribution and intensity, because there is the periodical similarity in evaporation from year to year. The most intense drought continued from December, 1964 to June, 1965 for 190 days and the most frequent rainfalls were observed from June, 1989 to August, 1990 for 15 months. The applied Oh's drought estimation model was reinforced with figuring programs with a view to later application for other districts. Present economic value index of irrigation were distributed in the range of 120% to 210% of one season yield for spring chinese cabbage, calculated on the basis of 10 year's accumulation of its expectable future yield increase. Therefore, the same value can be invested for the installation of new irrigation system even only for spring chinese cabbage, if its depreciation period is 10 years.

• Journal of Korea Water Resources Association
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• v.34 no.2
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• pp.131-140
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• 2001

The present study is focused on improving the methodology for the determination of parameters involved in USLE(Universal Soil Loss Equation) based on distributed system concept and investigation of sediment delivery ratio. Generally the distributed system concept consists of grid networks throughout the watershed and sediment can be traced from grid to rid in the direction of the steepest descent. The sediment yield data together with physical data of 10 small irrigation reservoirs in Kyounggi-Do are collected. After the sediment delivery ratio of a grid is defined to be related tothe fraction of forested or covered with delivery proofing area of the grid, the preportionality coefficient(C$_1$) is introduced. The distributed system model is calibrated using the available data for 8 reservoirs and is verified with the data for the ramaining 2 reservoirs, and regression analysis is made to express the proportionality coefficient $C_1$ in terms of watershed physical characteristics. By applying this results the verification of the distributed system model for 2 reservoirs showed a fair result, which justifies the applicability of the proposed method in the present study.

• Journal of Korean Society of Forest Science
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• v.90 no.6
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• pp.742-746
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• 2001

This study was carried out to develop volume equations for Japanese Res Cedar(Cryptomeria japonica D. Don) trees which were widely planted from 1920s throughout the southern regions in south Korea. The 31 trees for stem analysis were selected in 6 different sites in the southern and 29 trees data were used for developing volume equation. The best equation in estimating Japanese Red Cedar trees's volume was suggested as $V=-0.002908+0.000125D^{1.907114}H^{0.645131}$. The simultaneous F-test for this equation revealed that the estimated individual tree volume was not significantly different (p=0.1936) from the observed tree volume for model evaluation. Therefore, this individual tree volume prediction equation could provide basic information for the construction of yield table and forest management.