• 대한간호학회지
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• 제46권3호
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• pp.431-442
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• 2016

Purpose: This paper was conducted to validate the Korean version of the Peer Group Caring Interaction Scale (PGCIS-K) that measures caring behaviors as experienced by nursing students. Methods: Translation of the PGCIS-K was validated through forward-backward translation methods. Survey data were collected from 218 nursing students in a nursing school. Construct validity and criterion-related validity were evaluated. Internal consistency and the Guttman split-half coefficient were calculated to assess reliability. Results: The PGIS-K showed reliability except for 4 items (Cronbach's ${\alpha}=.91$, Guttman split-half coefficient=.85), which were low (<.30) or negatively correlated with the total scale. A 12-item reduced form of the PGCIS-K was developed by item-analysis and construct validity evidence. Factor loading for the 12 items on 2 factors ranged from .47~.82, which explained 58.4% of the total variance. Two factors were named 'modeling and assistance (Cronbach's ${\alpha}=.87$)' and 'communication and sharing (Cronbach's ${\alpha}=.82$)'. Convergent validity, discriminant validity, and criterion validity were supported according to the correlation coefficients of the 2 factors with other measure. Conclusion: The findings suggest preliminary evidence that the 12-item PGCIS-K can be used to measure nursing students' peer group caring interactions in Korea. Additional studies are recommended to continue the psychometric evaluation of this scale. Also, it can be extended to measure graduate nursing students or staff nurses' peer group caring interaction.

• 한국수학교육학회지시리즈A:수학교육
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• 제40권2호
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• pp.179-194
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• 2001

The seventh curriculum put into operation gradually from first-year student in 2000 academic years of elementary school is subject to form and apply a step-wise level curriculum. Mathematics(correspond to junior high school course from 7th school year to 9th school year) should apply a step-wise level curriculum from 7th school year in 2001 academic years. Accordingly, mathematics teachers must diagnose actual conditions of educations, distribution tables of test results, step-wise teaching-studying programs etc. They also make proper plans suitable for actual situations of each school, prepare appropriate teaching materials and aids. I investigated preceding studies planned for preparation of putting into operation of a step-wise level curriculum. It showed that most of the studies were conducted at schools of medium or large scale and studies conducted at schools of small scale was rare. There were 113 small scale middle schools out of total 297 middle schools in Kyongsangbuk-do area in 2000. In this situation, I felt necessities of modeling of a step-wise level curriculum suitable for small scale schools. In this study, I modeled a step-wise level curriculum suitable for small scale middle schools, applied this model to 44 students in M middle school. I modeled two types of curriculum. One is a step-wise level curriculum that execute special supplementation process to students who do not complete 7-가 step successfully. The other is a step-wise level curriculum which is a regular model for a step-wise level of 7-나 step. I carried out an academic achievement test and intimacy test about mathematics before and after the application of the model. In this study, I found out that this model was very effective in academic achievement of students and helpful to declined students in scholarship. In the intimacy test, It was found out that most of the students gained confidence in mathematics, felt less anxiety, formed positive self consciousness. Therefore, I think that this model will be helpful to the application of the seventh step-wise level curriculum.

• 한국지반공학회논문집
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• 제15권4호
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• pp.221-234
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• 1999

본 논문에서는 불연속암반내 시공되는 터널의 유한요소해석에 있어서 절리요소를 이용한 불연속면의 모델링에 관한 내용을 다루었다. 불연속 암반터널의 모델링이 가능한 유한요소해석 프로그램의 개발을 위해 기존의 유한요소해석 프로그램 GEOFE2D에 불연속면의 모델링이 가능한 절점변위 절리요소를 적용하고 모형실험 및 기존의 상용프로그램과의 비교를 통해 그 타당성을 검증하였다. 또한 검증된 GEOFE2D를 이용하여 불연속면이 터널의 거동에 미치는 영향을 고찰하기 위해 불연속면이 터널을 관통하는 경우에 대한 해석을 수행하고, 그 과정에서 불연속면과 숏크리트 라이닝 교차부에서의 변위 적합조건을 만족시킬 수 있는 불연속면 모델링 기법을 제시하였다. 한편, 해석결과를 분석한 결과 불연속면은 터널 주변의 응력-변형률 상태에 현저한 영향을 미치며, 특히 불연속면이 관통하는 부위에서의 숏크리트 라이닝 축력 및 휨 모멘트가 현저히 증가하는 것으로 나타났다. 따라서, 불연속면을 포함하는 터널의 거동해석시에는 불연속면에 대한 보다 상세한 모델링이 수반되어야 실제 거동에 보다 근접하는 해석결과를 도출시킬 수 있을 것으로 판단된다.

• Nuclear Engineering and Technology
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• 제48권4호
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• pp.859-869
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• 2016

Component-scale modeling of boiling is predominantly based on the Eulerian-Eulerian two-fluid approach. Within this framework, wall boiling is accounted for via the Rensselaer Polytechnic Institute (RPI) model and, within this model, the bubble is characterized using three main parameters: departure diameter (D), nucleation site density (N), and departure frequency (f). Typically, the magnitudes of these three parameters are obtained from empirical correlations. However, in recent years, efforts have been directed toward mechanistic modeling of the boiling process. Of the three parameters mentioned above, the departure diameter (D) is least affected by the intrinsic uncertainties of the nucleate boiling process. This feature, along with its prominence within the RPI boiling model, has made it the primary candidate for mechanistic modeling ventures. Mechanistic modeling of D is mostly carried out through solving of force balance equations on the bubble. Forces incorporated in these equations are formulated as functions of the radius of the bubble and have been developed for, and applied to, low-pressure conditions only. Conversely, for high-pressure conditions, no mechanistic information is available regarding the growth rates of bubbles and the forces acting on them. In this study, we use direct numerical simulation coupled with an interface tracking method to simulate bubble growth under high (up to 45 bar) pressure, to obtain the kind of mechanistic information required for an RPI-type approach. In this study, we compare the resulting bubble growth rate curves with predictions made with existing experimental data.

• 대한원격탐사학회지
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• 제18권1호
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• pp.1-12
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• 2002

Landslide prediction modeling has been regarded as one of the important environmental applications in GIS. While, landslide stability in a certain area as collateral process for prediction modeling can be characterized by DEM-based hydrological features such as flow-direction, flow-accumulation, flow-length, wetness index, and so forth. In this study, Slope-Area plot methodology followed by stability index mapping with these hydrological variables is firstly performed for stability analysis with actual landslide occurrences at Boeun area, Korea, and then Landslide prediction modeling based on likelihood ratio model for landslide potential mapping is carried out; in addition, KOMPSAT EOC imagery is used to detect the locations and scalped scale of Landslide occurrences. These two tasks are independently processed for preparation of unbiased criteria, and then results of those are qualitatively compared. As results of this case study, land stability analysis based on DEM-based hydrological variables directly reflects terrain characteristics; however, the results in the form of land stability map by landslide prediction model are not fully matched with those of hydrologic landslide analysis due to the heuristic scheme based on location of existed landslide occurrences within prediction approach, especially zones of not-investigated occurrences. Therefore, it is expected that the resets on the space-robustness of landslide prediction models in conjunction with DEM-based landslide stability analysis can be effectively utilized to search out unrevealed or hidden landslide occurrences.

• 한국터널지하공간학회 논문집
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• 제8권2호
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• pp.151-163
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• 2006

대단면 터널에서 시공되는 사전보강공법에 의한 보강영역의 보강효과를 수치해석적으로 모델링하기 위한 다양한 방법이 제시되고 있지만 실무자들은 공학적인 방법보다는 경험적인 방법과 문헌을 참고하여 설계를 수행하고 있다. 따라서 본 연구에서는 상용 프로그램에서 직접적으로 적용할 수 있는 사전보강 영역의 물성치 결정에 있어서 거시적 접근법의 개념을 기반으로 미시적 접근법을 적용한 등가 물성치를 결정하는 기법을 제시하고 3차원 수치해석을 통한 실제모델 해석결과와 다른 여러 미시적 접근법들과의 비교 분석을 수행하여 타당한 보강영역 물성치 결정기법을 제시하였다. 해석 결과 구근과 강관의 병렬연결 강성이 원지반과 직렬로 연결되는 사전보강영역의 직병렬 강성 시스템과, 구근과 강관의 직렬 강성 시스템이 실해와 가장 근사한 변위를 예측하였으나 후자의 경우 그 모델링 과정이 복잡하므로 본 연구에서는 간편법으로써 직병렬 강성 시스템을 제안한다. 직병렬 강성 시스템은 천단변위에 대해 풍화암 지반에서는 약간 안전측으로, 내공변위와 지표면 변위에 대해서는 정밀모델의 결과와 거의 동일하게 거동하는 것으로 분석되었으며 풍화토와 풍화암 지반에서 동일한 변위 경향성을 나타낸다. 본 연구에서 제시된 사전보강영역의 직병렬 강성 시스템은 실제모델로 대표되는 보강지반의 거동 메카니즘을 효과적으로 나타내는 것으로 분석된다.

• 한국물환경학회지
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• 제24권1호
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• pp.54-62
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• 2008

It is often believed that a more complex water quality model is better able to simulate reality. The more complex a model, however, the more parameters are involved thus increases the cost and uncertainty of modeling processes. The objective of this study was to compare the performance of two steady-state river water quality models, QUAL2E and QUAL-NIER, that have different complexity. QUAL-NIER is recently developed by National Institute of Environmental Research aiming to enhance the simulation capability of QUAL2E for eutrophic rivers. It is a carbon based model that considers different forms, such as dissolved versus particulate and labile versus refractory, of carbon and nutrients, and the contribution of autochthonous loading due to algal metabolism. The models were simultaneously applied to Nakdong River and their performance was evaluated by statistical verification with field data. Both models showed similar performance and satisfactorily replicated the longitudinal variations of BOD, T-N, T-P, Chl.a concentrations along the river. The algal blooms occurred at the stagnant reaches of downstream were also reasonably captured by the models. Although QUAL-NIER somewhat reduced the magnitude of errors, the hypothesis tests revealed no statistical evidence to justify its better performance. The contribution of autochthonous carbon and nutrient load by algal metabolism was insignificant because the hydraulic retention time is relatively short compare to the time scale of kinetic reactions. The results imply that the kinetic processes included in QUAL-NIER are too complex for the nature and scale of the real processes involved, thus needs to be optimized for improving the modeling efficiency.

• 한국대기환경학회지
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• 제23권4호
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• pp.405-419
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• 2007

A series of tracer experiments for the evaluation of atmospheric dispersion was performed over the urban area of Seoul using two inert, non-deposition perfluorocarbon (PMCH and m-PDCH) gases during three years campaign on 2002, 2003 and 2005. 30 sampling sites for collecting these tracers were located along two arcs of 2.5 and 5 kilometers downwind from the release point. About ten measurements which each lasted for 2 hours or 4 hours were made over the two consecutive days during each campaign. CALPUFF and MM5 meteorological model were applied to evaluate the urban dispersion in detail. Size of Modeling domain was $27\;km{\times}23\;km$ and the fine nest in the modeling domain had a grid size of 0.5 km. The results showed that CALPUFF dispersion model had a tendency to estimate tracer concentrations about $2{\sim}5$ times less than those of ambient samples under many conditions. These consistent inaccuracy in urban dispersion was attributed to inherent inaccuracy and lack of details in terrain data at urban area.

• 전기학회논문지
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• 제60권12호
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• pp.2183-2189
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• 2011

Since main portion of the required electric power in Jeju Island is provided from the mainland through two HVDC lines, Jeju HVDC has a most significant impact on Jeju power system. Average wind speed of Jeju Island is the highest among several candidates in South Korea. So, Jeju Island has been a suitable site for the construction of wind farms where several wind farms are now operating and several others to be sited. Since the large-scale wind generation could have adverse impacts on the stable operation of Jeju power system, wind power is also important for the stability of Jeju power system. Therefore, accurate modeling of Jeju HVDC and wind farms is required for stability analysis of Jeju power system. In this paper, PSS/E-based dynamic modeling of Jeju HVDC and DFIG wind farms is proposed. Model-writing technique of PSS/E is used to develop USRAUX model and USRMDL model for controlling the frequency of HVDC and imposing an operation limit of wind power, respectively. Dynamic characteristics of Jeju HVDC and DFIG wind farms are analyzed through the dynamic simulations. The simulation results show the effectiveness of the developed models for Jeju power system.

• 상하수도학회지
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• 제27권1호
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• pp.139-146
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• 2013

A process diagnosis method for membrane water treatment plant was developed using a constant flux membrane fouling model. This diagnosis method can be applied to a real-field membrane-based water treatment plant as an early alarming system for membrane fouling. The constant flux membrane fouling model was based on the simplest equation form to describe change in trans-membrane pressure (TMP) during the filtration cycle from a literature. The model was verified using a pilot-scale microfiltraton (MF) plant with two commercial MF membrane modules (72 m2 of membrane area). The predicted TMP data were produced using the model, where the modeling parameters were obtained by the least square method using the early plant data and modeling equations. The diagnosis was carried out by comparing the predicted TMP data (as baseline) and real plant data. As a result of the case study, the diagnsis method worked pretty well to predict the early points where fouling started to occur.