With the increase in installed solar energy capacity, comparison and analysis of the physical property values of solar cells are becoming increasingly important for production. Therefore, research on determining the physical characteristic values of solar cells is being actively pursued. In this study, a diode equation, which is commonly used to describe the I-V behavior and determine the electrical characteristic values of solar cells, was applied. Using this method, it is possible to determine the diode ideality factor (n) and series resistance (Rs) based on light I-V measurements. Thus, using a commercial screen-printed solar cell and an interdigitated back-contact solar cell, we determined the ideality factor (n) and series resistance (Rs) with a modified diode equation method for the light I-V curves. We also used the sun-shade method to determine the ideality factor (n) and series resistance (Rs) of the samples. The values determined using the two methods were similar. However, given the error in the sun-shade method, the diode equation is considered more useful than the sun-shade method for analyzing the electrical characteristics because it determines the ideality factor (n) and series resistance (Rs) based on the light I-V curves.

울시 가로수의 79%를 차지하는 은행나무, 메타세콰이어, 느티나무, 양버즘나무를 대상으로 흉고직경 을 이용하여 4개의 상대생장식을 비교하였다. 최적의 상대생장식을 개발하기 위하여 이용된 통계량은 결정계수, 잔차 평균, 절대평균 잔차제곱이다. 이를 통하여 추정된 수종별 상대생장식은 양버즘나무에 서  , 은행나무, 메타세콰이어, 느티나무에서    식이고 결정계수는 0.873이상의 수치를 나타내 어 가로수 탄소저장량 추정에 사용이 적합한 것으로 판단된다. 본 연구에서 개발된 재적식을 이용하여 추정된 서울시 가로수의 주요 4종에 저장된 탄소량은 약 33,760tC이다. 본 연구의 결과로 제시된 서울 시 가로수의 재적식과 탄소저장량은 가로수의 수종별 생장 및 재적정보를 제시하고 도시녹지의 탄소저 장량 평가에 활용이 가능할 것으로 판단된다.

This study was conducted to develop local stem volume tables reflecting the local growth pattern and climate condition using stem taper equations for Pinus rigida. We developed the local stem volume table for P. rigida, which is the widely planted species following Pinus denisflora and Larix kamepferi in South Korea. Three Functions of Max & Burkhart, Kozak and Parresol et al. were applied and compared to derive the most suitable taper function. Their suitability was statistically analyzed by using the Fitness Index, Bias and Standard Error of Bias. The result showed that there was a significant difference in all three functions, and the Fitness Index of the Kozak’s function was the highest among the three functions for estimating the tree growth pattern of P. rigida. Therefore, the Kozak’s function was chosen for generating stem taper equation and local stem volume tables for P. rigida. The developed stem volume tables of each region were compared to the standard stem volume table that was driven by the data of tree growth obtained throughout the nation. The result showed that the local stem volume table was higher than standard volume tables in two regions of Muju and Boeun. There was a statistically significant difference (p<α=0.05), but there was no significant (p >α=0.05) between the local stem volume.

The rheological properties of complex materials such as colloid dispersion show complicated non-Newtonian flow phenomena when they are subjected to shear flow. These flow properties are controlled by the characteristics of flow units and the interactions among the flow segments. The rheological parameters of relaxation time (β2)0, structure factor C2 and shear modulus X2/α2 for various thixotropic flow curves was obtained by applying thixotropic equation to flow curves. The variations of rheological parameters are directly related to non-Newtonian flows, viscosities and activation energies of flow segments.

The purpose of this paper is to investigate the determinants of new product diffusion. We seek to document and explain systematic features of product diffusion. In this essay, we examine the well-documented empirical regularity that the speed of diffusion has accelerated during the twentieth century. The empirical results show that the main source of acceleration are faster declines in prices. Faster price declines make the product affordable to more consumers within a given period of time. Based on theories of intertemporal price discrimination and learning-by-doing, the association between the speed of adoption and the speed of price decline was explained. Faster price declines are attributed to several product characteristics as well as changes in income distribution. Above all, the introduction of consumer electronic products in more recent years can be regarded as the most important factor in accelerating price declines. Consumer electronic products are technologically different from non-electronic goods, in that semiconductors are important components. As the price of semiconductors has dropped rapidly, the falling production costs can be rapidly incorporated to the price of consumer electronic goods. Furthermore, most of the recently introduced consumer electronic products have network externalities, and many products with network externalities require complementary products. A complementary product becomes more readily or cheaply available as more people have the main product. One major difference between previous studies and this study is that the former focuses only on the factors that operate directly on the speed of adoption, while this study incorporated factors that work through price changes as well as the factors that work directly on the speed of adoption.

Modern football has transformed into a scientific football based on data. With this trend, various methods for tactics studies and outcome prediction have been developed on the perspective of data analysis. In this paper, we propose a structural equation model for football game. We analyze critical factors that affect to the winning of game except psychological parts and the causal relationship between latent variables and observed variables is statistically verified through the proposed structural equation model. The results show that the Passing ability and the Ball possession affect to the Attack ability, and consequently it has a positive impact on the winning of game.

PURPOSES: The purpose of this study is to verify traffic accident injury severity factors for elderly drivers and the relative relationship of these factors. METHODS: To verify the complicated relationship among traffic accident injury severity factors, this study employed a structural equation model (SEM). To develop the SEM structure, only the severity of human injuries was considered; moreover, the observed variables were selected through confirmatory factor analysis (CFA). The number of fatalities, serious injuries, moderate injuries, and minor injuries were selected for observed variables of severity. For latent variables, the accident situation, environment, and vehicle and driver factors were respectively defined. Seven observed variables were selected among the latent variables. RESULTS: This study showed that the vehicle and driver factor was the most influential factor for accident severity among the latent factors. For the observed variable, the type of vehicle, type of accident, and status of day or night for each latent variable were the most relative observed variables for the accident severity factor. To verify the validity of the SEM, several model fitting methods, including , GFI, AGFI, CFI, and others, were applied, and the model produced meaningful results. CONCLUSIONS: Based on an analysis of results of traffic accident injury severity for elderly drivers, the vehicle and driver factor was the most influential one for injury severity. Therefore, education tailored to elderly drivers is needed to improve driving behavior of elderly driver.

An algebraic model for turbulent heat fluxes is proposed on the basis of the elliptic blending equation. The algebraic model satisfies the temperature-pressure gradient correlation characteristics of near-wall region and the flow center region far away from the wall. That is, the turbulent heat flux conditions for both regions are connected by the solution of the elliptic blending equation. The predictions of turbulent heat transfer in a plane channel flow have been carried out with constant wall heat flux and constant wall temperature difference boundary conditions respectively. Also, the rotating channel flow with constant wall temperature difference is considered to test the applicability of the model. The prediction results show that the distributions of the turbulent heat fluxes and mean temperature are well captured by the present algebraic heat flux model.

본 연구는 제주시험림 일대의 삼나무 임분을 대상으로 간곡선식을 추정하여 임목의 간재적표를 작성하였다. 조사대상지는 제주시험림 내 삼나무조림지에서 임분을 대표할 수 있는 표준지를 선정하여 직경이 골고루 분포하도록 총 20그루의 표본목을 공시목으로 사용하였다. 본 연구에서 간곡선식은 Kozak 모형을 이용하여 모수를 추정하였다. 추정된 모형의 적합성 지수는 99%, 오차는 0.008, 절대평균편차는 0.832로 나타났다. 본 연구에서 제시된 삼나무림 간재적표는 제주도 지역에 분포하고 있는 삼나무림의 합리적 경영을 위한 정보를 제공해 줄 것으로 사료된다.

PURPOSES: Daejeon is basically divided into an old downtown and a new downtown, and the recent relocation of the Chungcheongnam-do Provincial Government of Republic of Korea from the old downtown and the opening of governmental buildings in the new downtown as well have made this new downtown only densely populated with industrial and business facilities. Such changes in the downtowns have promoted the conditions of the new downtown while, consequently, dragging down the old downtown. Out of concern for those unbalanced developments of the two downtowns, Daejeon is now carrying out several city projects to revive the old downtown. In the light of that, as a part of the project to promote the old downtown, this study aims to conduct an evaluation on landscape of the culture and arts street in Daeheungdong which was built upon those ideas of a theme street project by Daejeon. METHODS: Based on the findings from the questionnaire not only on the components that would design the streetscape of the culture and arts street but also on the public satisfaction with the streetscape, the study defined how those changes in the components affect emotional factors of the pedestrians. In order to achieve the research goal, the study made changes in D/H ratio of the street structural components as well as the roadside trees. In terms of the questionnaire method, the study used the SD scale, and proceeded with its investigation through the frequency analysis, the principal component analysis (the factor analysis) and the structural equation model. RESULTS : According to the results from the factor analysis and the regression analysis, of those three factors, such as the openness, the comfortable sensation and the safety, the openness followed by the comfortable sensation and the safety was determined to have the most positive influence on the total satisfaction. The structural model analysis reported that the D/H and the structural components of the roadside trees and planting have a positive effect on the emotional image, and this emotional image also appeared to be positively related to the total satisfaction. CONCLUSIONS : This study looked into how the changes in the street structural components of the culture and arts street in Daeheungdong would affect the satisfaction with the streetscape, and finally confirmed that the D/H and the planting are what would have a positive effect on this satisfaction. What has been learned from this study will be the basic data to figure out how to promote and improve the culture and arts street in Daeheung-dong as this data will also help designing and developing of those specialized streets in other regions.

본 논문에서는 유공형 형상의 GFRP 판으로 전단 보강된 플랫 플레이트의 전단거동을 실험을 통해 평가하였다. GFRP 판은 개구부가 있는 판의 형태로서 콘크리트와의 일체화 거동을 위하여 콘크리트에 매립하여 시공하였다. 실험 변수로는 기둥면과 첫 번째 GFRP 판의 세로 스트립 사이의 간격, GFRP 판의 세로 스트립의 개수를 선정하였다. GFRP 판의 세로 스트립의 개수가 증가할수록 전단강도도 증가하는 결과를 보여주었다. 실험결과를 바탕으로 GFRP 판으로 보강된 플랫 플레이트의 전단강도가 ACI 318, BS 8110, EUROCODE 2, KCI에서 제시하고 있는 전단강도와 비교하여 가장 합리적인 규준을 평가하였다.

In this paper, the wakes behind a square cylinder were simulated using two kinds of different turbulence models for the eddy viscosity concept such as the zero- and the one-equation model in which the former is the mixing length model and the latter is the k-equation model. For comparison between numerical and analytical solutions, we employed three skill assessments: the correlation coefficient(r) for the similarity of the wake shape, the error of maximum velocity difference(EMVD) for the accuracy of wake velocity and the ratio of drag coefficient(RDC) for the pressure distribution around the structure. On the basis of the numerical results, the feasibility of each model for wake simulation was discussed and a suitable value for the empirical constant was suggested in these turbulence models. The zero-equation model, known as the simplest turbulence model, overestimated the EMVD and its absolute mean error(AME) for r, EMVD and RDC was ranging from 20.3 % to 56.3 % for all test. But the AME by the one-equation model was ranging from 3.4 % to 19.9 %. The predicted values of the one-equation model substantially agreed with the analytical solutions at the empirical mixing length scale L=0.6b1/2 with the AME of 3.4 %. Therefore it was concluded that the one-equation model was suitable for the wake simulation behind a square cylinder when the empirical constant for eddy viscosity would be properly chosen.

The Notched Ring Test(NRT) has proven to be very useful in determining the slow crack growth behavior of polyethylene pressure pipes. In particular, the test is simple and an order of magnitude shorter in experimental times as compared to the currently used Notched Pipe Test(NPT), which makes this method attractive for use as the accelerated slow crack growth test. In addition, since the NRT specimen is taken directly from the pipe, having maintained the cross-section, processing induced artifacts that would affect the slow crack growth behavior are not altered. This makes the direct comparison to the slow crack growth specimen in pipe from more meaningful. In this study, for comparison with other available slow crack growth methods, including the NPT, the stress intensity factor equation for NRT specimen was developed and demonstrated of its accuracy within 3% of that obtained from the finite element analysis. The equation was derived using a flexure formula of curved beam bending along with numerically determined geometric factors. The accuracy of the equation was successfully tested on 63, 110, 140, 160, 250, and 400 mm nominal pipe diameters, with crack depth ranging from 15 % to 45 % of the pipe wall thickness, and for standard dimensional ratio(SDR) of 9, 11, and 13.6. Using this equation the slow crack results from 110SDR11 NRT specimen were compared to that from the NPT specimen, which demonstrated that the NRT specimen was equivalent to the NPT specimen in creating the slow crack, however in much shorter experimental times.

본 연구는 온실의 관류전열량을 분석하고 예측하는데 필요한 기초자료 제공을 위하여, 공기막 이중 PO필름의 열저항식을 모델링하였고, 전도, 복사, 대류에 의한 열저항 특성을 규명하였다. 또한 열저항식의 타당성 검증을 위해 열저항식에 의한 관류전열량의 계산값과 실험값을 비교·분석하였다. 공기막 이중 PO필름의 열저항식은 PO필름, 공기막, PO필름의 직렬 열저항식으로 구성되며, 공기막은 복사와 대류에 의한 병렬 열저항식으로 구성된다. 고온부 T1의 평균온도는 276.1K, 저온부 T2의 평균온도는 266.8K로 나타났으며, 다른 조건들이 동일할 경우 챔버 내부온도가 높을수록 T1과 T2의 평균온도와 온도차가 증가하는 것을 확인할 수 있었다. 전도열저항은 0.00091K ·W−1로 전체 열저항의 1% 미만으로 매우 미미한 수준이고, 공기막의 열저항이 0.18K ·W−1로 전체 열저항의 99% 이상을 차지하는 것으로 나타났다. 공기막의 경우 대류열 저항이 복사열저항에 비해 1.33~2.08배 정도 크게 나타났으며, 복사열저항은 평균온도의 3제곱에 반비례하고 대류열저항은 온도차가 4.7, 5.3, 5.5, 5.7, 12.3, 13.2, 13.3, 13.5, 13.8 및 14.0K로 증가할 때 각각 0.78, 0.75, 0.74, 0.73, 0.57, 0.56, 0.56, 0.56, 0.55 및 0.55K ·W−1 로 감소하였다. 관류전열량의 계산값과 실험값의 차이는 실험조건별로 0.6~17.2W의 범위로 평균 6.9W였으며, 실험값은 계산값의 79.8~97.7% 범위로 평균 87.3% 수준으로 나타났다. 전체적인 계산값과 실험값의 관류전열량 경향성은 잘 일치하고 있으며, 공기막 이중필름의 열 저항은 공기막 두께 및 주입공기의 종류와는 직접적인 상관관계를 보이지 않았다.

Estimation approaches for casual relation model with high-order factors have strict restrictions or limits. In the case of ML (Maximum Likelihood), a strong assumption which data must show a normal distribution is required and factors of exponentiation is impossible due to the uncertainty of factors. To overcome this limitation many PLS (Partial Least Squares) approaches are introduced to estimate the structural equation model including high-order factors. However, it is possible to yield biased estimates if there are some differences in the number of measurement variables connected to each latent variable. In addition, any approach does not exist to deal with general cases not having any measurement variable of high-order factors. This study compare several approaches including the repeated measures approach which are used to estimate the casual relation model including high-order factors by using PLS (Partial Least Squares), and suggest the best estimation approach. In other words, the study proposes the best approach through the research on the existing studies related to the casual relation model including high-order factors by using PLS and approach comparison using a virtual model.

The research is a correlational study to look for causes and factors relating to the design of written documents (professional reading materials) and identify those relationships that are useful for communication designers. The research specifically targeted the relationships between perception and reader’s past experiences and appearance of the written documents. A preliminary survey, such as interviews, discussions, questionnaires and brainstorming sessions are conducted to establish the observable attributes related to perception which are reader’s interests, importance of information and written documents complexity. Finally, the research used Structural Equation Model (SEM) to identify significant differences and analyze strong and weak correlations between these attributes. In general, the results of the study shows that the attribute appearances of a written documents with excellent visualizations for information display shows a strong correlation with interests while the attributes importance is weakly correlated with the complexity of the documents.

본 연구의 목적은 6개의 수간곡선을 비교하여 우리나라 남부지역 해송에 적합한 수간곡선식을 개발 하는데 있다. 59본의 입목을 벌채하여 1년 단위 수간석해를 통해 자료의 전체 수고, 단면고별 수피 외직경, 단면고별 수피 내 직경, 임령을 측정하였다. 수간곡선식의 적합도는 적합도 지수(fit index, FI), 편차(bias), 평균오차제곱근(root mean square error, RMSE)을 이용하였다. 남부 지방 해송의 수간곡선 추정을 위하여 6종의 수간곡선식을 비교한 결과, Kozak(1988) 식에서 높은 적합도를 보였으며 FI, Bias, RMSE는 각각 0.9802, 0.0284, 1.2165로 나타났다. 본 연구의 주요한 결과로 추정된 수간곡선식은 남부지방의 주요 수종인 해송의 생장 정보 제공이 가능한 것으로 판단된다.

This study describes the amendment of Durbin's k-∈-v2-f model and its application to turbulent channel flow to test the model’s performance. Modeling redistribution and dissipation rate terms for the scalar v2 transport equation is considered by the elliptic blending equation which is used in the second moment closure generally. The prediction results are directly compared to the DNS and Durbin's original k-∈-v2-f model to assess the performance of the new model predictions and to show their reasonable agreement with the DNS and Durbin's model for all the flow characteristics that are analyzed for the present study.