• 지질공학
• /
• 제20권1호
• /
• pp.35-45
• /
• 2010

본 연구에서는 10여년 동안 국내 산사태 발생지역 및 인근 미발생지역에서 채취된 자연사면에서의 토층을 대상으로 획득된 약 1,150여개소의 토질시험결과를 토대로 지질조건에 따른 토층의 평균 물성치를 산정하고, 통계적인 분석을 실시하여 지질조건별 투수계수에 대한 간편식을 제안하였다. 투수계수는 화강암지역과 이암지역에서 큰 것으로 나타났으며, 세립토함유량은 이암지역과 편마암지역에서 큰 것으로 나타났다. 지질조건에 따른 토층의 투수계수를 산정하기 위해서 상관성 분석을 실시한 결과 종속변수를 투수계수로 하고 독립변수를 세립토함유량, 함수비, 건조단위중량 및 간극비로 선정하였다. 회귀분석결과 지질조건별 제안된 선형회귀식에서는 공통적으로 세립토함유량 및 간극비가 가장 많이 포함되었다. 제안된 선형회귀식을 검증하기 위하여 타 지역의 토층을 대상으로 수행된 투수계수 측정결과와 선형회귀식으로 예측된 결과를 서로 비교하였다. 비교결과 일부 측정된 결과와 예측된 결과가 차이가 있는 것으로 나타났으나, 그 차이는 비교적 작은 것으로 나타났다. 본 연구에서 제안된 지질조건별 투수계수 산정을 위한 선형회귀식은 국내 지반을 대상으로 적용이 가능할 것으로 판단되나, 추후 지속적인 검증 및 수정이 필요할 것으로 판단된다.

• 한국농림기상학회지
• /
• 제14권2호
• /
• pp.89-97
• /
• 2012

우리나라의 자생 활엽수종 중에서 상수리나무와 신갈나무는 분포면적이나 자원으로서의 잠재적 효용성을 고려할 때 매우 중요한 수종이다. 본 연구는 다양한 환경인자를 독립변수로 하는 상수리나무와 신갈나무의 지위지수 추정식을 개발하고, 이에 근거한 수종별 적지를 추정하기 위해 수행하였다. 본 연구에서 개발한 상수리나무와 신갈나무의 수종별 최종 지위지수 추정식은 모두 5~6개의 환경 인자에 의하여 지위지수를 추정하는 것으로 평가 되었다.수종별 지위지수 추정식에서 채택된 독립변수는 지형인자, 토양인자, 그리고 기후인자를 포괄하고 있어 임지생산력에 영향을 미치는 산림생태계의 특성을 비교적 잘 반영하고 있으며, 설명력을 나타내는 결정계수의 범위는 034~0.50인 것으로 나타났다. 이 결과는 임목의 생육에 다양한 입지조건과 생물환경 인자들이 복합적으로 작용하는 것을 고려하면 지위지수 추정에 큰 무리가 없는 것으로 평가된다. 이와 함께 본 연구에서 개발된 수종별 지위지수 추정식에는 그동안 반영하지 못하였던 기후인자를 독립변수에 포함시켰다는데 의의가 있다. 또한 본 연구에서는 수종별 지위지수 추정식에 근거하여 수종별 적지면적뿐만 아니라 적지의 공간적 분포를 파악하였다. 따라서 앞으로 기후변화시나리오에 따른 수종별 적지분포의 변화를 예측할 수 있는 정보로 활용될 수 있을 것으로 기대된다.

• 화약ㆍ발파
• /
• 제35권1호
• /
• pp.1-17
• /
• 2017

공기를 통해 이동하는 폭발파에 의한 압력 및 압력에 의해 지표 및 지하구조물에 미치는 영향을 이해하는 것은 매우 중요하다. 폭발의 충격이 구조물에 미치는 영향을 컴퓨터 시뮬레이션하기 위해서는 시간과 거리에 따른 압력의 변화를 결정하여야 한다. 기존의 연구를 통해 압력의 변화와 관련되는 인자들을 추정하기 위한 여러 경험식들이 개발되었다. 본 연구에서는 최대압력, 양압지속기간, 임펄스, 최소음압, 음압지속기간, 폭발파 도착시간과 감쇠상수를 예측하는 경험식들을 조사 분석하였으며 가장 널리 사용되고 있는 Kingery 경험식과 다른 경험식에 의한 압력 변화를 비교하였다.

• Smart Structures and Systems
• /
• 제2권1호
• /
• pp.81-100
• /
• 2006

To calculate the shear capacity of concrete beams reinforced with fibre-reinforced polymer (FRP), current shear design provisions use slightly modified versions of existing semi-empirical shear design equations that were primarily derived from experimental data generated on concrete beams having steel reinforcement. However, FRP materials have different mechanical properties and mode of failure than steel, and extending existing shear design equations for steel reinforced beams to cover concrete beams reinforced with FRP is questionable. This paper investigates the feasibility of using artificial neural networks (ANNs) to estimate the nominal shear capacity, Vn of concrete beams reinforced with FRP bars. Experimental data on 150 FRP-reinforced beams were retrieved from published literature. The resulting database was used to evaluate the validity of several existing shear design methods for FRP reinforced beams, namely the ACI 440-03, CSA S806-02, JSCE-97, and ISIS Canada-01. The database was also used to develop an ANN model to predict the shear capacity of FRP reinforced concrete beams. Results show that current guidelines are either inadequate or very conservative in estimating the shear strength of FRP reinforced concrete beams. Based on ANN predictions, modified equations are proposed for the shear design of FRP reinforced concrete beams and proved to be more accurate than existing equations.

• 호남수학학술지
• /
• 제31권1호
• /
• pp.109-124
• /
• 2009

Based on the observed data for Clarithromycin released, three commonly used inflow models: the power, the exponential, and the logarithmic models are considered. Among them, the power model is used most in practice for simplicity. Using the numerical parameter estimation techniques, the parameters appeared in the model equations are estimated. Through the numerical estimation results using the several experimental data sets, the exponential model turns out to be best among the three models. More specifically, the sum of squares of absolute errors and the sum of squares of relative errors for the exponential model are reduced by 80-95 % for the experimental data sets and 60-90 % for the noise added data sets compared with those for the power and logarithmic models. A typical experimental data set is used in this paper to show the estimation method and its numerical results. The proposed numerical method and its algorithm are designed for estimating the parameters appeared in the model differential equations for which the exact form of the solution is unknown in general. The methodology developed can be applied to more general cases such as the nonlinear ordinary differential equations or the partial differential equations.

• Animal Bioscience
• /
• 제34권4호
• /
• pp.558-566
• /
• 2021

Objective: Objectives were to estimate energy and protein requirements of dairy crossbred steers, as well as to evaluate equations previously described in the literature (HH46 and CS16) to predict the carcass and empty body chemical composition of crossbred dairy cattle. Methods: Thirty-three Holstein×Zebu steers, aged 19±1 months old, with an initial shrunk body weight (BW) of 324±7.7 kg, were randomly divided into three groups: reference group (n = 5), maintenance level (1.17% BW; n = 4), and the remaining 24 steers were randomly allocated to 1 of 4 treatments. Treatments were: intake restricted to 85% of ad libitum feed intake for either 0, 28, 42, or 84 d of an 84-d finishing period. Results: The net energy and the metabolizable protein requirements for maintenance were 0.083 Mcal/EBW0.75/d and 4.40 g/EBW0.75, respectively. The net energy (NEG) and protein (NPG) requirements for growth can be estimated with the following equations: NEG (Mcal/kg EBG) = $0.2973_{({\pm}0.1212)}{\times}EBW^{0.4336_{({\pm}0.1002)}$ and NPG (g/d) = 183.6(±22.5333)×EBG-2.0693(±4.7254)×RE, where EBW, empty BW; EBG, empty body gain; and RE, retained energy. Crude protein (CP) and ether extract (EE) chemical contents in carcass, and all the chemical components in the empty body were precisely and accurately estimated by CS16 equations. However, water content in carcass was better predicted by HH46 equation. Conclusion: The equations proposed in this study can be used for estimating the energy and protein requirements of crossbred dairy steers. The CS16 equations were the best estimator for CP and EE chemical contents in carcass, and all chemical components in the empty body of crossbred dairy steers, whereas water in carcass was better estimated using the HH46 equations.

• 통상정보연구
• /
• 제12권1호
• /
• pp.99-121
• /
• 2010

This paper reviews the categories and properties of risk measures, analyzes the classes and structural equations of volatility forecasting models, and presents the practical methodologies and their expansion methods of estimating and forecasting the volatilities of exchange rates using Excel spreadsheet modeling. We apply the GARCH(1,1) model to the Korean won(KRW) denominated daily and monthly exchange rates of USD, JPY, EUR, GBP, CAD and CNY during the periods from January 4, 1998 to December 31, 2009, make the estimates of long-run variances in the returns of exchange rate calculated as the step-by-step change rate, and test the adequacy of estimated GARCH(1,1) model using the Box-Pierce-Ljung statistics Q and chi-square test-statistics. We demonstrate the adequacy of GARCH(1,1) model in estimating and forecasting the volatility of exchange rates in the monthly series except the semi-variance GARCH(1,1) applied to KRW/JPY100 rate. But we reject the adequacy of GARCH(1,1) model in estimating and forecasting the volatility of exchange rates in the daily series because of the very high Box-Pierce-Ljung statistics in the respective time lags resulting to the self-autocorrelation. In conclusion, the GARCH(1,1) model provides for the easy and helpful tools to forecast the exchange rate volatilities and may become the powerful methodology to overcome the application difficulties with the spreadsheet modeling.

• 한국태양에너지학회 논문집
• /
• 제32권2호
• /
• pp.28-34
• /
• 2012

It is necessary to estimate the regression coefficients in order to predict the daily global radiation on a horizontal surface. Therefore many different equations have proposed to evaluate them for certain areas. In this work a new correlation has been made to predict the solar radiation for 16 different areas over Korea by estimating the regression coefficients taking into account cloud hours of bright sunshine. Particularly, the multiple linear regression model proposed shows reliable results for estimating the global radiation on a horizontal surface with monthly average deviation of-0.26 to +0.53% and each station annual average deviation of -1.61 to +1.7% from measured values.

• 대한설비공학회:학술대회논문집
• /
• 대한설비공학회 2009년도 하계학술발표대회 논문집
• /
• pp.315-320
• /
• 2009

Thermoeconomics or exergoeconomics can be classified into the three fields of cost estimating, cost optimization, and internal cost analysis. The objective of cost estimating is to estimate each unit cost of product and allocate each cost flow of product such as electricity or hot water. The objective of optimization is to minimize the input costs of capital and energy resource or maximize the output costs of products under the given constraints. The objective of internal cost analysis is to find out the cost formation process and calculate the amount of cost flow at each state, each component, and overall system. In this study, a new thermoeconomic methodology was proposed in the three fields. The proposed methodology is very simple and obvious. That is, the equation is only each one, and there are no auxiliary equations. Any energy including enthalpy and exergy can be applied and evaluated by this equation. As a new field, the cost allocation methodology on cool air or hot air produced from an air-condition system was proposed. Extending this concept, the proposed methodology can be applied to any complex system.

• 한국태양에너지학회:학술대회논문집
• /
• 한국태양에너지학회 2011년도 추계학술발표대회 논문집
• /
• pp.232-235
• /
• 2011

Radiation data are the best source of information for estimating average incident radiation. Lacking this or data from nearby locations of similar climate, it is possible to use empirical relationships to estimate radiation from days of cloudiness. It is necessary to estimate the regression coefficients in order to predict the daily global radiation on a horizontal surface. There fore many different equations have proposed to evaluate them for certain areas. In this work a new correlation has been made to predict the solar radiation for 16 different areas over Korea by estimating the regression coefficients taking into account cloud cover. Particularly, the straight line regression model proposed shows reliable results for estimating the global radiation on a horizontal surface with monthly average deviation of-0.26 to +0.53% and each station annual average deviation of -1.61 to +1.7% from measured values.