• 한국강구조학회 논문집
• /
• 제25권6호
• /
• pp.587-599
• /
• 2013

본 연구에서는 EC4의 내화설계 관점에서 표준화재하의 무피복 콘크리트충전강관기둥의 내화성능을 해석적으로 예측하는 개선된 방안을 제시하고자 하였다. Lawson 등이 제안한 콘크리트충전강관기둥에 대한 단면온도평가식의 한계를 분석하고, 기존 실험결과와 유한요소 열전달해석을 바탕으로 콘크리트충전강관기둥의 단면온도분포 예측식을 새로이 제안하였다. 본 연구에서 제안한 온도분포 예측식과 EC4의 내화설계법을 이용하여 예측한 콘크리트충전강관기둥의 축강도는 기존 설계법과 비교하여 더욱 정확하고 설계목적에 합당하다고 판단된다. 본 연구의 결과는 무피복 콘크리트충전강관기둥의 내화설계 및 성능평가에 매우 편리하게 활용될 수 있다.

• 설비공학논문집
• /
• 제28권12호
• /
• pp.467-476
• /
• 2016

As the energy saving issues become one of the important global agenda, the building simulation method is generally used to predict the inside energy usage to establish the power-saving strategies. To foretell an accurate energy usage of a building, proper and typical weather data are needed. For this reason, typical weather data are fundamental in building energy simulations and among the meteorological factors, the solar irradiation is the most important element. Therefore, preparing solar irradiation is a basic factor. However, there are few places where the horizontal solar radiation in domestic weather stations can be measured, so the prediction of the solar radiation is needed to arrive at typical weather data. In this paper, four solar radiation prediction models were analyzed in terms of their applicability for domestic weather conditions. A total of 12 regions were analyzed to compare the differences of solar irradiation between measurements and the prediction results. The applicability of the solar irradiation prediction model for a certain region was determined by the comparisons. The results were that the Zhang and Huang model showed the highest accuracy (Rad 0.87~0.80) in most of the analyzed regions. The Kasten model which utilizes a simple regression equation exhibited the second-highest accuracy. The Angstrom-Prescott model is easily used, also by employing a plain regression equation Lastly, the Winslow model which is known for predicting global horizontal solar irradiation at any climate regions uses a daily integration equation and showed a low accuracy regarding the domestic climate conditions in Korea.

• 한국식품과학회지
• /
• 제20권2호
• /
• pp.280-286
• /
• 1988

이상과 같이, 기존 data의 정확도에 대한 고찰과 본 연구에서 소개한 단순한 해석적 방법에 의한 식품의 동결 시간예측 model로서, 실제 측정한 시료별 실험치와 기존 model을 비교 검토하였다. 기 발표된 lean beef등 109개의 data중, Hung & Thompson의 data는 Nagaoka 및 Pham의 model에, Cleland & Earle의 data는 Hung $ Thompson의 model에 매우 접근함을 볼 수 있으며, 시료별로 살펴볼 때, tylose등 5품목의 시료는 Nagaoka 및 Pham의 model에 잘 적용됨을 알 수 있다. 그러나 본 실험에서 사용한 pine mushroom등 4품목은 Cleland & Earle, Hung & Tompson 및 Pham의 model에 잘 부합되며, 제안된 model의 간편성과 정확도에 있어서도 단지 3가지의 실험적 매개변수와 7가지의 물성치 만으로 실험치와 비교한 결과, 공학적 최소오차 범위인 ${\pm}10%$ 이내로 나타났다.

• 한국항만학회지
• /
• 제13권1호
• /
• pp.155-166
• /
• 1999

The construction of the coastal structures and reclamation work causes the circulation reduced in the semi-closed inner water area and the unbalanced sediment budget of beach results in an alteration of beach topography. Among the various fluid motions in the nearshore zone water particle motion due to wave and wave-induced currents are the most responsible for sediment movement. Therefore it is needed to predict the effect of the environmental change because of development and so the prediction of wave transformation dose. The purpose of this study is to introduce the relation between waves wave-induced currents and sediment movement. In this study we will show numerical method using energy conservation equation involving reflection diffraction and reflection and the surfzone energy dissipation term due to wave breaking is included in the basic equation. For the wave-induced current the momentum equation was combined with radiation stresses lateral mixing and friction Various information is required in the prediction of wave-induced current depending on the prediction tool. We can predict changes in wave-induced current from the distribution of wave especially near the wave breaking zone. To evaluate these quantities we have to know the local condition of waves mean sea level and so on. The results from the wave field and wave-induced current field deformation models are used as input data of the sediment transport and bottom change model. Numerical model were established by a finite difference method then were applied to the development plan of the eastern Pusan coastal zone Yeonhwa-ri and Daebyun fishing port. We represented the result with 2-D graphics and made comparison between before and after development.

• 한국안전학회지
• /
• 제20권2호
• /
• pp.162-168
• /
• 2005

노말프로판올과 노말데칸의 가연성혼합물의 하부인화점을 Tag개방식 장치를 이용하여 측정하였다. 실험결과 인화점과 조성의 관계에서 혼합물 보다 낮은 인화점을 보여주었다. 노말 프로판올의 몰분율 0.71에서 $27^{\circ}C$였으며, 노말프로판올의 인화점은 $28^{\circ}C$였다. 실험 결과는 이상용액을 근거로 한 예측 값과 활동도계수 예측식인 van Laar식을 사용하여 계산된 값을 각각 비교하였다. 이상용액 개념을 이용한 예측 값은 실험 값과 차이를 보였으나, van Laar 식에 의한 예측 값은 실험 값과 일치하였으며, van Laar식에 의한 예측 값과 실험 값은 평균 $0.83^{\circ}C$차이를 보였다. 본 연구에서 제시된 방법론은 가연성물질에 대해 안전한 저장 및 취급하는 조건의 결정과 같은 화학공정 설계의 본질적 안전 설계에 적용할 수 있다.

• Nutrition Research and Practice
• /
• 제6권1호
• /
• pp.51-60
• /
• 2012

Weight-controlling can be supported by a proper prescription of energy intake. The individual energy requirement is usually determined through resting energy expenditure (REE) and physical activity. Because REE contributes to 60-70% of daily energy expenditure, the assessment of REE is very important. REE is often predicted using various equations, which are usually based on the body weight, height, age, gender, and so on. The aim of this study is to validate the published predictive equations for resting energy expenditure in 76 normal weight and 52 obese Korean children and adolescents in the 7-18 years old age group. The open-circuit indirect calorimetry using a ventilated hood system was used to measure REE. Sixteen REE predictive equations were included, which were based on weight and/or height of children and adolescents, or which were commonly used in clinical settings despite its use based on adults. The accuracy of the equations was evaluated on bias, RMSPE, and percentage of accurate prediction. The means of age and height were not significantly different among the groups. Weight and BMI were significantly higher in obese group (64.0 kg, $25.9kg/m^2$) than in the non-obese group (44.8 kg, $19.0kg/m^2$). For the obese group, the Molnar, Mifflin, Liu, and Harris-Benedict equations provided the accurate predictions of > 70% (87%, 79% 77%, and 73%, respectively). On the other hand, for non-obese group, only the Molnar equation had a high level of accuracy (bias of 0.6%, RMSPE of 90.4 kcal/d, and accurate prediction of 72%). The accurate prediction of the Schofield (W/WH), WHO (W/WH), and Henry (W/WH) equations was less than 60% for all groups. Our results showed that the Molnar equation appears to be the most accurate and precise for both the non-obese and the obese groups. This equation might be useful for clinical professionals when calculating energy needs in Korean children and adolescents.

• 한국구조물진단유지관리공학회 논문집
• /
• 제10권3호
• /
• pp.97-105
• /
• 2006

고성능 콘크리트의 자기수축은 초기균열을 유도할 수 있기 때문에 내구성 측면에서 매우 중요하다. 이에 따라, 본 연구에서는 실험을 통해 혼화재료를 혼입한 고성능 콘크리트의 자기수축 특성을 분석한 후 예측모델을 제안하였다. 이를 위해 다양한 실험변수를 가진 시편에 대해 광범위한 실험을 수행하였다. 주요 실험변수는 혼화재료의 종류 및 혼입률로 설정하였으며 물-시멘트비는 30%로 고정하였다. 실험결과 플라이애시를 치환한 경우에는 자기수축량이 다소 감소하였으며, 고로슬래그를 사용한 경우에는 자기수축이 증가하였다. 또한, 수축저감제 및 팽창재의 혼입량이 클수록 고성능 콘크리트의 자기수축은 감소하는 경향을 보였다. 한편, 본 논문에서는 회귀분석을 통해 혼화재료를 사용한 고성능 콘크리트의 자기수축 예측식을 제안하였으며, 제안된 자기수축 예측식은 실험결과와 비교적 일치하였다

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2003년도 The Fifth Asian Computational Fluid Dynamics Conference
• /
• pp.66-66
• /
• 2003

• 한국해양공학회지
• /
• 제9권2호
• /
• pp.112-122
• /
• 1995

In this work, prediction of fatigue life and fatigue crack growth are studied. 4th order polynominal function is presented to describe the crack growth behaviors from artifical pit of SM45C steel. Crack growth curves obtained from 4th order polyminal growth equations are in good agreement with experimental data The crack growth behaviors at arbitrary stress levels and investigated by the concept of elastic-plastic fracture mechanics using ${\Delta}J$. Fatigue life prediction are carried out by numerical integral method. Prediction lives obtained by proposed method in this study, is in good agreement with the experimental ones. Life prediction results calculated by using of ${\Delta}J$ better than those of ${\Delta}K$.

• Computers and Concrete
• /
• 제12권4호
• /
• pp.377-392
• /
• 2013

This paper investigates prediction models estimating the hydration properties of concrete, such as the compressive strength, the splitting tensile strength, the elastic modulus,and the autogenous shrinkage. A prediction model is suggested on the basis of an equation that is formulated to predict the compressive strength. Based on the assumption that the apparent activation energy is a characteristic property of concrete, a prediction model for the compressive strength is applied to hydration-related properties. The hydration properties predicted by the model are compared with experimental results, and it is concluded that the prediction model properly estimates the splitting tensile strength, elastic modulus, and autogenous shrinkage as well as the compressive strength of concrete.