• Journal of the Korean Wood Science and Technology
• /
• v.23 no.4
• /
• pp.10-17
• /
• 1995

본 연구는 화염에 노출된 목재 부재의 거동에 관련된 자료를 얻기 위해 수행되었다. 목재 보에 대한 현행 내화 모델들은 외곽부 섬유의 MOE나 휨강도의 감소, 그리고 화염노출의 계속으로 인한 단면의 감소 등에 기초하고 있다. 하지만 이런 모델들은 정확한 거동 예측이 힘들다. 따라서 목재 보의 거동을 정확히 예측하기 위해 본 연구에서는 변형 단면을 이용한 내화거동 모델을 개발하고자 하였다. 이 변형 단면모델을 개발하기 위하여 온도분포 온도와 목재의 물리적 성질간의 상관관계를 이용하였다. 본 연구를 통해 온도와 목재의 휨성질간의 정확한 관계가 제공되기만 한다면 본 방법이 화염에 노출된 목재 보의 변형을 잘 예측할 수 있음을 알 수 있었다.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.40 no.3
• /
• pp.259-265
• /
• 2016

Recently, life prediction models for Pb-based and Pb-free solders used in chip resistor assemblies under thermal cycling have been introduced. The models suggest that the field lifetimes of Pb-free solders would be better than those of Pb-based solders when used for chip resistors under thermal cycling conditions, while the lifetime of the chip assemblies under accelerated test conditions show a reverse relationship. In this study, the prediction models were verified by applying the model to another research case. Finite element models were built, thermal cycling conditions were applied, and the energy densities were calculated. Finally, life prediction analysis was conducted for the cases where Pb-based and Pb-free solders were used. The prediction results were then compared with the test data of the case. It was verified that the predictions of the developed life cycle models are on the practical scale.

• Proceedings of the KIEE Conference
• /
• 2008.07a
• /
• pp.1539-1540
• /
• 2008

운전자의 경험과 판단에 전적으로 의존하는 빙축열 시스템의 기존 운전방식에서는 운전자의 그릇된 판단과 미숙한 운전으로 인해 과잉 축열이나 냉방공급량 부족현상이 자주 초래된다. 본 논문에서는 경제적이고 효율적인 빙축열 시스템의 운용을 위해 다음날의 구간별 온도, 습도와 냉방부하를 예측하는 자기구성퍼지모델 구축방안을 제안한다. 제안된 방법의 성능과 실제 적용가능성을 검증학기 위하여 한국전력 속초 생활연수원을 대상으로 제안된 방법과 신경회로망, 퍼지모델, 선형회귀모델 등을 이용한 기존의 방법을 적용하여 구한 냉방부하, 온도, 습도의 예측정확도를 비교 분석한다.

• Korean Journal of Remote Sensing
• /
• v.36 no.5_3
• /
• pp.1077-1093
• /
• 2020

Sea Surface Temperature (SST) is an important environmental indicator that affects climate coupling systems around the world. In particular, coastal regions suffer from abnormal SST resulting in huge socio-economic damage. This study used Long Short Term Memory (LSTM) and Convolutional Long Short Term Memory (ConvLSTM) to predict SST up to 7 days in the south sea region in South Korea. The results showed that the ConvLSTM model outperformed the LSTM model, resulting in a root mean square error (RMSE) of 0.33℃ and a mean difference of -0.0098℃. Seasonal comparison also showed the superiority of ConvLSTM to LSTM for all seasons. However, in summer, the prediction accuracy for both models with all lead times dramatically decreased, resulting in RMSEs of 0.48℃ and 0.27℃ for LSTM and ConvLSTM, respectively. This study also examined the prediction of abnormally high SST based on three ocean heatwave categories (i.e., warning, caution, and attention) with the lead time from one to seven days for an ocean heatwave case in summer 2017. ConvLSTM was able to successfully predict ocean heatwave five days in advance.

• Proceedings of the KWS Conference
• /
• v.43
• /
• pp.130-132
• /
• 2004

석출물의 용해 온도보다 낮은 온도에서의 석출물의 야금학적인 거동을 예측하였다. 평균 사이즈 석출물의 지속적인 성장만을 고려하는 기존의 모델과 달리, 본 연구에서 제안된 모델의 경우에는, Gibbs-Thomson equation으로부터 유도되는 critical particle size를 고려하였다. 제안된 모델을 이용해서 TiN석출물의 거동을 예측하였으며, 이를 실험 결과 및 기존의 모델에 의한 예측 값과 비교하였다. 석출물들의 분포는 전형적인 log-normal 분포를 따르는 것으로 관찰되었으며, 본 연구에서 제안된 모델이 기존의 모델에 비해서 실험결과와 잘 일치함을 확인할 수 있었다.

• Korean Journal of Food Science and Technology
• /
• v.37 no.5
• /
• pp.850-855
• /
• 2005

Model was developed to predict the growth of Listeria monocytogenes in raw pork. Experiment condition for model development was full 5-by-7 factorial arrangements of temperature (0, 5, 10, 15, and $20^{\circ}C$) and time (0, 1, 2, 3, 18, 48, and 120 hr). Gompertz values A, C, B, and M, and growth kinetics, exponential growth rate (EGR), generation time (GT), lag phase duration (LPD), and maximum population density (MPD) were calculated based on growth increased data. GT and LPD values gradually decreased, whereas EGR value gradually increased with increasing temperature. Response surface analysis (RSA) was carried out using Gompertz B and M values, to formulate equation with temperature being main control factor. This equation was applied to Gompertz equation. Experimental and predictive values for GT, LPD, and EGR, compared using the model, showed no significant differences (p<0.01). Proposed model could be used to predict growth of microorganisms for exposure assessment of MRA, thereby allowing more informed decision-making on potential regulatory actions of microorganisms in raw pork.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.49 no.5
• /
• pp.437-446
• /
• 2021

As flying vehicle's speed is getting faster, the magnitude of aerodynamic heating is getting bigger. High-speed vehicle's exterior skin is heated to hundreds of degrees, and electrical equipments inside the vehicle are heated, simultaneously. Since allowable temperature of electrical equipments is low, they are vulnerable to effect of aerodynamic heating. These days, lots of techniques are applied to estimate temperature of electrical equipments in flight condition, and to make them thermally safe from heating during flight. In this paper, new model building technique for thermal safety analysis is introduced. To understand internal thermal transient characteristic of electrical equipment, simple heating experiment was held. From the result of experiment, we used our new building technique to build thermal analysis model which reflects thermal transient characteristic of original equipment. This model can provide internal temperature differences of electrical equipment and temperature change of specific unit which is thermally most vulnerable part in the equipment. So, engineers are provided much more detailed thermal analysis data for thermal safety of electrical equipment through this technique.

• Journal of the Korea Concrete Institute
• /
• v.14 no.2
• /
• pp.137-147
• /
• 2002

Maturity models involving curing temperature and curing ages have been widely used to predict concrete strength, which can accurately estimate concrete strength. However, they may not consider physical quantities such as the characteristics of hydrates and the capillary porosity of microstructures associated with strength development. In order to find out the effects of both factors on a strength increment, the hydration model and the estimation method of the amount of capillary porosity were established, and the compressive strength test of concrete nth various water/cement ratios was carried out considering two test parameters, curing temperature and curing age. In this study, by analyzing the experimental results, a strength estimation model for early-age concrete that can consider the microstructural characteristics such as hydrates and capillary porosity was proposed. Measured compressive strengths were compared with estimated strengths and good agreements were obtained. Consequently, the proposed strength model can estimate compressive strength of concrete with curing age and curing temperature within an acceptable error.

• Horticultural Science & Technology
• /
• v.32 no.2
• /
• pp.241-251
• /
• 2014

This study was carried out to develop a simple, rapid and reliable assessment model to predict cold tolerance in Pittosporum tobira, a broad-leaved evergreen commonly used in the southern region of South Korea, which can minimize the possible experimental errors appeared in a electrolyte leakage test for cold tolerance assessment. The modeling procedure comprised of regrowth test and a electrolyte leakage test on the plants exposed to low temperature treatments. The lethal temperatures estimated from the methodological combinations of a electrolyte leakage test including tissue sampling, temperature treatment for potential electrical conductivity, and statistical analysis were compared to the results of the regrowth test. The highest temperature showing the survival rate lower than 50% obtained from the regrowth test was $-10^{\circ}C$ and the lethal was $-10^{\circ}C{\sim}-5^{\circ}C$. Based on the results of the regrowth test, several methodological combinations of electrolyte leakage tests were evaluated and the electrolyte leakage lethal temperatures estimated using leaf sample tissue and freeze-killing method were closest to the regrowth lethal temperature. Evaluating statistical analysis models, linear interpolation had a higher tendency to overestimate the cold tolerance than non-linear regression. Consequently, the optimal model for cold tolerance assessment of P. tobira is composed of evaluating electrolyte leakage from leaf sample tissue applying freeze-killing method for potential electrical conductivity and predicting lethal temperature through non-linear regression analysis.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2019.05a
• /
• pp.309-309
• /
• 2019

기후예측모델을 통해 일단위 강수의 예측정보가 제공되고 있지만, 실제 강수량자료와 시공간적 편의로 인해 수문학적 활용은 한계가 있다. 일반적으로 기후모델의 시공간적 해석 규모 및 예측정확성을 고려할 때 계절단위에서 예측정보의 활용이 가장 현실적인 것으로 알려지고 있다. 그러나 수문해석 시 시공간적 해상도가 낮아 직접적인 활용은 어려운 상황이며, 수문해석 모형의 입력자료로 활용 시 편의보정 및 상세화 과정이 일반적으로 요구된다. 본 연구에서는 기후모델로부터 얻은 강우예측결과에 Bayesian 모델 기반의 편의보정-상세화 기법을 개발하여 강우예측정보의 활용성을 개선하고자 한다. 이 과정에서 Bayesian Copula 모델을 이용한 이변량 형태의 예측강수의 검보정 방법을 개발하였으며, 특히 기후모델 이외의 기상 상태변량인 해수면온도(sea surface temperature, SST)를 예측인자로 추가하여 Hybrid 형태의 계절 앙상블 강우예측모델을 개발하고자 한다.