• 대기
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• 제21권2호
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• pp.151-162
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• 2011

One-layer solar radiation(GWNU; Gangneung-Wonju National University) model is developed in order to resolve the lack of vertical observations and fast calculation with high resolution. GWNU model is based on IQBAL(Iqbal, 1983) and NREL(National Renewable Energy Laboratory) methods and corrected by precise multi-layer LBL(Line-by-line) model. Input data were used 42 atmospheric profiles from Garand et al.(2001) for calculation of global radiation by the Multi-layer and one-layer solar radiation models. GWNU model has error of about -0.10% compared with LBL model while IQBAL and NREL models have errors of about -3.92 and -2.57%, respectively. Global solar radiation was calculated by corrected GWNU solar model with satellites(MODIS, OMI and MTSAT-1R), RDPS model prediction data in Korea peninsula in 2009, and the results were compared to surface solar radiation observed by 22 KMA solar sites. All models have correlation($R^2$) of 0.91 with the observed hourly solar radiation, and root mean square errors of IQBAL, NREL and GWNU models are 69.16, 69.74 and $67.53W/m^2$, respectively.

• International Journal of Fluid Machinery and Systems
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• 제8권4호
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• pp.221-229
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• 2015

For efficient design process of regenerative blower, the present study provides new generalized pressure and leakage flow loss models, which can be used in the performance analysis method of regenerative blower. The present performance analysis on designed blower is made by incorporating momentum exchange theory between impellers and side channel with mean line analysis method, and its pressure loss and leakage flow models are generalized from the related fluid mechanics correlations which can be expressed in terms of blower design variables. The present performance analysis method is applied to four existing models for verifying its prediction accuracy, and the prediction and the test results agreed well within a few percentage of relative error. Furthermore, the present performance analysis method is also applied in developing a new blower used for fuel cell application, and the newly designed blower is manufactured and tested through chamber-type test facility. The performance prediction by the present method agreed well with the test result and also with the CFD simulation results. From the comparison results, the present performance analysis method is shown to be suitable for the actual design practice of regenerative blower.

• Asian-Australasian Journal of Animal Sciences
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• 제31권10호
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• pp.1670-1676
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• 2018

Objective: This study was conducted to enable on-line prediction of primal and commercial cut weights in Korean slaughter pigs by AutoFom III, which non-invasively scans pig carcasses early after slaughter using ultrasonic sensors. Methods: A total of 162 Landrace, Yorkshire, and Duroc (LYD) pigs and 154 LYD pigs representing the yearly Korean slaughter distribution were included in the calibration and validation dataset, respectively. Partial least squares (PLS) models were developed for prediction of the weight of deboned shoulder blade, shoulder picnic, belly, loin, and ham. In addition, AutoFom III's ability to predict the weight of the commercial cuts of spare rib, jowl, false lean, back rib, diaphragm, and tenderloin was investigated. Each cut was manually prepared by local butchers and then recorded. Results: The cross-validated prediction accuracy ($R^2cv$) of the calibration models for deboned shoulder blade, shoulder picnic, loin, belly, and ham ranged from 0.77 to 0.86. The $R^2cv$ for tenderloin, spare rib, diaphragm, false lean, jowl, and back rib ranged from 0.34 to 0.62. Because the $R^2cv$ of the latter commercial cuts were less than 0.65, AutoFom III was less accurate for the prediction of those cuts. The root mean squares error of cross validation calibration (RMSECV) model was comparable to the root mean squares error of prediction (RMSEP), although the RMSECV was numerically higher than RMSEP for the deboned shoulder blade and belly. Conclusion: AutoFom III predicts the weight of deboned shoulder blade, shoulder picnic, loin, belly, and ham with high accuracy, and is a suitable process analytical tool for sorting pork primals in Korea. However, AutoFom III's prediction of smaller commercial Korean cuts is less accurate, which may be attributed to the lack of anatomical reference points and the lack of a good correlation between the scanned area of the carcass and those traits.

• Journal of Forest and Environmental Science
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• 제33권4호
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• pp.305-314
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• 2017

This study aimed to predict changes in forest area using a probability density function, in order to promote effective forest management in the area north of the civilian control line (known as the Minbuk area) in Korea. Time series analysis (2010 and 2016) of forest area using land cover maps and accessibility expressed by distance covariates (distance from buildings, roads, and civilian control line) was applied to a probability density function. In order to estimate the probability density function, mean and variance were calculated using three methods: area weight (AW), area rate weight (ARW), and sample area change rate weight (SRW). Forest area increases in regions with lower accessibility (i.e., greater distance) from buildings and roads, but no relationship with accessibility from the civilian control line was found. Estimation of forest area change using different distance covariates shows that SRW using distance from buildings provides the most accurate estimation, with around 0.98-fold difference from actual forest area change, and performs well in a Chi-Square test. Furthermore, estimation of forest area until 2028 using SRW and distance from buildings most closely replicates patterns of actual forest area changes, suggesting that estimation of future change could be possible using this method. The method allows investigation of the current status of land cover in the Minbuk area, as well as predictions of future changes in forest area that could be utilized in forest management planning and policymaking in the northern area.

• Journal of Mechanical Science and Technology
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• 제20권3호
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• pp.335-344
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• 2006

A comprehensive review of through thickness transverse residual stress distributions in a range of as-welded and mechanically bent components made up of a range of steels has been carried out, and simplified generic transverse residual stress profiles for a plate and pipe components have been proposed. The geometries consisted of welded pipe butt joints, T-plate joints, tubular T-joints, tubular Y-joints and a pipe on plate joints as well as cold bent tubes and pipes. The collected data covered a range of engineering steels including ferritic, austenitic, C-Mn and Cr-Mo steels. Measured residual stress data, normalised with respect to the parent material yield stress, has shown a good linear correlation versus the normalised depth of the region containing the residual stress resulting from the welding or cold-bending process. The proposed simplified generic residual stress profiles based on the mean statistical linear fit of all the data provides a reasonably conservative prediction of the stress intensity factors. Whereas the profiles for the assessment procedures are fixed and case specific, the simple bilinear profiles for the residual stresses obtained by shifting the mean and bending stress from the mean regression line have been proposed and validated.

• 한국유체기계학회 논문집
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• 제11권2호
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• pp.55-63
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• 2008

An examination of the condition of the flow leaving the impeller exit kinetic energy often accounts for 30-50% of the shaft work input to the compressor stage, and for energy efficiency it is important to recover as much of this as possible. This is the function of the diffuser which follows the impeller. The purpose of this study is to investigate the sensitivity of how compressor performances changes as vaned diffuser geometry is varied. Three kinds of vaned diffusers were studied and its results were compared. First vaned diffuser type is based on NACA airfoil and second is channel diffuser and third is conformal transformation of NACA65(4A10)06 airfoil. Mean-line prediction method was applied to investigate the performance and stability for three kinds of diffusers. And CFD analyses have been done for comparison and detailed interior flow pattern study. NACA65(4A10)06 airfoil showed the widest operating range and higher pressure characteristics than the others.

• Advances in concrete construction
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• 제1권3호
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• pp.201-213
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• 2013

While recognizing the problem of reinforcement corrosion and premature structural deterioration of reinforced concrete (RC) structures as a combined effect of mechanical and environmental actions (carbonation, ingress of chlorides), emphasis is given on the effect of the latter, as most severe and unpredictable action. In this study, a simulation tool, based on proven predictive models utilizing principles of chemical and material engineering, for the estimation of concrete service life is applied on an existing reinforced concrete bridge (${\O}$resund Link) located in a chloride environment. After a brief introduction to the structure of the models used, emphasis is given on the physicochemical processes in concrete leading to chloride induced corrosion of the embedded reinforcement. By taking under consideration the concrete, structural and environmental properties of the bridge investigated, an accurate prediction of its service life is taking place. It was observed that the proposed, and already used, relationship of service lifetime- cover is almost identical with a mean line between the lines derived from the minimum and maximum critical values considered for corrosion initiation. Thus, an excellent agreement with the project specifications is observed despite the different ways used to approach the problem. Furthermore, different scenarios of concrete cover failure, in the case when a coating is utilized, and extreme deicing salts attack are also investigated.

• 대한전자공학회논문지
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• 제26권3호
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• pp.160-166
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• 1989

공간영역 예측기의 계수를 계산하기 위한 적응 알고리듬이 제안되었다. 제안된 방법은 LMS 알고리듬을 사용하여 TDL(tapped-delay-line)과 ESC(escalator) 구조를 갖는 공간영역 예측기의 계수를 계산한다. 기종존의 일반적인 예측기와 다른점은 순방향과 역방향 예측 오차의 평균 자승값의 합을 최소화하며 예측기의 계수를 계산함으로 향상된 선형예측 공간 스펙트럼을 얻을 수 있다. 제안된 방법을 선형으로 배열된 센서에 의하여 얻어진 협대역신호의 입사각 추정문제에 적용시켜 기존의 적응예측 알고리듬과 컴퓨터 시뮬레이션을 통하여 성능을 비교하였다.

• 한국작물학회지
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• 제46권3호
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• pp.241-247
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• 2001

우리나라 벼 수량의 기상반응을 종합적으로 검토하여 벼 수량예측모델을 구축하고자 1985년부터 1999년까지 15년간 수행한 20개 지역의 벼 지역적응시험 자료를 이용하여 기상에 대한 수량반응의 최대경계선(boundary line)분석을 하였으며, 이에 근거하여 수량예측모형을 설정하였다. 1. 벼의 생육기간을 영양생장기, 생식생장기, 등숙기로 구분하고 각 발육단계를 15-20일 간으로 구분하여 각 시기의 기상요소에 대한 수량반응의 최대경계선은 평균기온( $T_{a}$ )과 일조시수( $S_{h}$)에 대해서는 지수함수 f( $T_{a}$ )=$\beta$$_{0}$(1-exp(-$\beta$$_1$/$\times$ $T_{a}$ ), f( $S_{h}$)=$\beta$$_{0}$(1-exp(-$\beta$$_1$$\times$ $T_{h}$)로 나타났으며 일교차(Tr)는 2차함수 f( $T_{r}$)=$\beta$0(1-( $T_{r}$-$\beta$$_1$)$^2$)로, 이 식에서 상수항 $\beta$$_{0}$를 제거하여 수량에 대한 각 기상요소의 영향도를 0-1로 나타내는 기상지수로 나타내었다. 2. 각 생육시기의 평균기온, 일조시간 및 일교차에 대한 수량반응의 최대경계선이외에 불임에 의한 등숙률 저하와 그에 따른 수량감소를 고려하기 위하여 Uchijima(1976)가 제안한 냉각도일수(cooling degree day)를 출수전 30일간의 생식생장기에 계산하여 이에 대한 수량과 등숙률 반응의 최대경계선을 계산하였는데 냉각도일수가 증가하면 수량이 감소하는 지수함수로 잘 표현되어 기존의 연구들과 같은 결과였다. 3. 기상지수는 벼의 생육기간을 영양생장기, 생식생장기 및 등숙기로 구별하고 각 시기별로 수량 기상지수를 각 기상요소 기상지수를 기하평균하여 산출하였는데 각 시기별 수량기상지수의 수량변이 설명도는 각각 0.383-0.430, 0.460-0.534, 0.4603-0.587로 결정계수는 영양생장기＜생식생장기＜등숙기의 순으로 컸다. 4. 최대경계선 분석방법을 통하여 얻어진 각 생육시기별 수량기상지수를 기하평균하여 구한 종합수량기상지수와 수량과의 직선회귀식을 구하여 수량예측모형(Model I, II, III)을 작성하였다. Model I, II, III)은 각각 결정계수가 0.6512, 0.6703, 0.6129로 모든 생육단계에 걸쳐서 기간을 15-20일 단위로 세분하여 모든 기간의 수량에 대한 기상지수를 고려하여 전 생육기간의 종합수량기상지수를 산출한 Model II가 기상변화에 따른 수량변이의 설명도가 가장 높았다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 I
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• pp.504-511
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• 2001

In this research, we developed a computer program that designs a centrifugal impeller and diffuser, and predicts the far-field noise from the impeller. To design the impeller optimally, the TEIS model, which was originally developed by Japkise(1985), and the mean-line analysis are combined to predict the performance and design the optimal impeller simultaneously. The geometric configurations are provided by a GUI software (iDesignComp). The noise from impeller can be computed by the rapid loading procedure, which generates a surface between two blades and calculates the pressure distributions on the suction and pressure sides. The steady loading noise is computed by the rotating dipole source distribution via Ffowcs Williams & Hawkings equation.