• Journal of Korean Society on Water Environment
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• v.32 no.6
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• pp.589-599
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• 2016

Implemented since 2004, TPLC (Total Pollution Load Control) is the most powerful water-quality protection program. Recently, uncertainty of prediction using steady state model increased due to changing water environments, and necessity of a dynamic state model, especially the watershed model, gained importance. For application of watershed model on TPLC, it needs to be feasible to adjust the relationship (mass-balance) between discharged loads estimated by technical guidance, and arrived loads based on observed data at the watershed outlet. However, at HSPF, simulation is performed as a semi-distributed model (lumped model) in a sub-basin. Therefore, if the estimated discharged loads from individual pollution source is directly entered as the point source data into the RCHRES module (without delivery ratio), the pollutant load is not reduced properly until it reaches the outlet of the sub-basin. The hypothetic RCHRES generated using the HSPF BMP Reach Toolkit was applied to solve this problem (although this is not the original application of Reach Toolkit). It was observed that the impact of discharged load according to spatial distribution of pollution sources in a sub-basin, could be expressed by multi-segmentation of the hypothetical RCHRES. Thus, the discharged pollutant load could be adjusted easily by modification of the infiltration rate or characteristics of flow control devices.

• Journal of Soil and Groundwater Environment
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• v.17 no.3
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• pp.39-48
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• 2012

Visual MODFLOW, a three dimensional groundwater flow model, was used to analyze effects of a weir construction in an alluvial stream on the nearby groundwater flow system. A hypothetical conceptual model was developed to investigate how the groundwater level and the water budget could change after a weir construction depending on the location of tributary streams. A site example, dealing with the Juksan weir installed in the Yeongsan River, was also demonstrated to predict the effects of the weir construction. Model results show that impacts of a weir construction on the groundwater flow system greatly vary depending on how far a tributary is located and whether it is located downstream or upstream from the weir. Therefore, consideration of the location of tributaries in planning the location of a weir could effectively minimize the impacts of a weir construction on the groundwater flow system. It is also demonstrated that model results are highly dependent upon how the model is dealing with small tributaries and agricultural drainage channels, which can be easily found nearby the main streams, acting as major water bodies for groundwater discharge. The model for the Juksan area shows that the weir construction will change the direction of groundwater flow in some areas, leading to changes of groundwater quality and interaction of the Yeongsan River to the aquifer from a gaining to a losing stream. The model also predicted the areas where rise of groundwater level caused by the Juksan weir could adversely affect plant growth, and thereby suggested installing new drainage channels as a countermeasure to drawdown the groundwater level.

• Journal of Korea Water Resources Association
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• v.38 no.5 s.154
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• pp.333-343
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• 2005

The upwind model is well known to simulate shockwaves, but it is rarely applied to natural rivers because of problems caused by the source terms. Although several methods have been developed to deal with the source terms, none of them has been applied to natural rivers. This paper deals with application of the upwind model to the natural river. An implicit upwind model is applied to a hypothetical irregular channel and a natural river with highly irregular bed, width, and hydraulic structures. Different types of the flows including steady-state flow, flood wave, dam-break wave, and bore are simulated to test accuracy and applicability of the implicit upwind model. It is proved that the model can simulate various types of flows in natural rivers with high accuracy and robustness.

• Bulletin of the Korean Space Science Society
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• 2009.10a
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• pp.48.1-48.1
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• 2009

In recent years, many candidates for extra-solar planet have been discovered from various measurement techniques. Fueled by such discoveries, new space missions for direct detection of earth-like planets have been proposed and actively studied. TPF instrument is a fair example of such scientific endeavors. One of the many technical problems that space missions such as TPF would need to solve is deconvolution of the collapsed (i.e. spatially and temporally) spectral signal arriving at the detector surface and the deconvolution computation may fall into a local minimum solution, instead of the global minimum solution, in the optimization process, yielding mis-interpretation of the spectral signal from the potential earth-like planets. To this extend, observational and theoretical understanding on the spectral bio-signal from the Earth serves as the key reference datum for the accurate interpretation of the planetary bio-signatures from other star systems. In this study, we present ray tracing computational model for the on-going simulation study on the Earth bio-signatures. A multi-layered atmospheric model and sea ice variation model were added to the existing target Earth model and a hypothetical space instrument (called AmonRa) observed the spectral bio-signals of the model Earth from the L1 halo orbit. The resulting spectrums of the Earth show well known "red-edge" spectrums as well as key molecular absorption lines important to harbor life forms. The model details, computational process and the resulting bio-signatures are presented together with implications to the future study direction.

• Journal of Korean Academy of Nursing
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• v.48 no.5
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• pp.622-635
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• 2018

Purpose: This study aimed to develop and test a structural model for sleep quality in female shift work nurses. The hypothetical model was constructed on the basis of Spielman's 3P model of insomnia and previous research related to the sleep quality of shift nurses. Methods: This cross-sectional study used structural equation modeling and recruited 285 female shift work nurses from four general and university hospitals with over 300 beds located in C and J cities in Gyeongsangnamdo. Data were collected from September 27 to October 20, 2016, and then analyzed using descriptive statistics, Pearson's correlation, and structural equation modeling. The study used SPSS/Win 18.0 and AMOS 18.0 in processing the data. Results: The final model showed good fit to the empirical data: ${\chi}^2/df=2.19$, SRMR=.07, RMSEA=.07, AGFI=.85, TLI=.91, GFI=.93, GFI=.89, NFI=.87. The factors that influenced sleep quality were sleep hygiene (${\beta}=.32$), perceived shift work status (${\beta}=-.16$), stress response (${\beta}=.16$), shift work experience (${\beta}=.15$), perceived health status (${\beta}=-.14)$, and circadian rhythm (${\beta}=-.13$) explaining 36.0% of the variance. Conclusion: The model of sleep quality of the shift work nurses constructed in this study is recommended as a model to understand and predict the sleep quality of shift work nurses. The results suggest that strategies for improving the sleep quality of shift work nurses should focus on sleep hygiene, perceived health status, stress response, circadian rhythm, perceived shift work status, and shift work experience.

• Journal of Korean Academy of Nursing
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• v.43 no.6
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• pp.791-800
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• 2013

Purpose: This study was done to test a structural equation modeling of case management outcomes in order to identify parameters affecting case management outcomes for the community-dwelling vulnerable elders. Methods: Data were collected from 309 nurses (case managers) and community-dwelling vulnerable elders (clients) from public health centers. For data analysis, descriptive statistics, Pearson correlation analysis, factor analysis, and covariance structure analysis were performed using SPSS Version 18.0 for Windows and Amos 16.0. Results: The hypothetical model had an acceptable fit: GFI=.97, CFI=.95, RMSEA=.02, SRMR=.05. The factor "case managers' singularity" had the greatest impact on case management outcomes in this model. In addition, the factor "case management practice" influenced case management outcomes; however, client characteristics did not. Case managers' singularity affected case management outcomes directly and indirectly, with case management practice mediating the latter effect. Conclusion: These results suggest that the causal relationship between case management outcomes and factors influencing these outcomes should be clarified through longitudinal research including a variety of client characteristics. In addition, in future studies, analysis of the effects of programs to improve manpower quality and examine the relationships among case management outcomes should be done.

• Journal of Korean Academy of Nursing
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• v.45 no.1
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• pp.64-75
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• 2015

Purpose: This study was designed to construct and test structural equation modeling on healthy menopausal transition in middle-aged women in order to identify variables affecting healthy menopausal transition. Methods: Participants, 276 women, 45 to 60 years of age, with menopausal symptom score higher than 5 on the Korean version of Menopause Rating Scale, were recruited in three cities and one county of Gyeongnam Province. Research data were collected via questionnaires and analysed using SPSS version 18.0 and AMOS version 20.0. Results: After confirmatory factor analysis, one of the observed variables was excluded due to relatively low factor loading. The model fit indices for the hypothetical model were suitable for the recommended level: GFI=.93, CFI=.92, RMSEA=.05. Self-efficacy, self-differentiation, and menopausal symptoms explained 67.7% of variance in menopausal transition, and self-differentiation was the most influential factor for menopausal transition. Self efficacy and menopausal symptoms explained 9.6% of variance in menopausal management, although "menopausal symptoms" was not significant. Conclusion: These results suggest that nursing interventions to improve self-differentiation, self efficacy, menopausal management and decrease menopausal symptoms are critical for healthy menopausal transition in middle-aged women. Continued development of a variety of community-based nursing interventions to facilitate healthy menopausal transition is suggested.

• Journal of Distribution Research
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• v.8 no.2
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• pp.21-39
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• 2003

The objective of this study is examining regional differentiation of private brand customer. Factors found to influence private brand purchase intention included familiarity with private brand, perceived value, store loyalty, perceived risk, perceived quality variation between national and private brand products. For testing the research model, data were collected in Seoul and Busan. The hypothetical paths included in model are supported. There are regional differentiations in 1) negative relation of perceived quality variation and perceived value, 2) positive relation of familiarity and purchase intention, and 3) positive relation of store royalty and purchase intention.

• Industrial Engineering and Management Systems
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• v.4 no.2
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• pp.129-135
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• 2005

Continuous quality improvement through process refinement is a must for survival of all industries in the contemporary market place. This is true for both manufacturing and service sectors. While manufacturing has spearheaded quality efforts, the service sector has lagged behind primarily because of inherent difficulties. Customer satisfaction is perhaps the most important performance measure for service quality. There are a number of quality dimensions in service quality, such as reliability, responsiveness, assurance, empathy, and tangibles. An issue of concern is ‘how can one have a unified measure of service quality across all the dimensions?' The intent of this paper is to determine if the Analytical Hierarchy Process (AHP) method could be used to derive a single quality index. AHP is a quantitative technique that structures a multi-attribute, multi-person and multi-period problem hierarchically so that solutions are facilitated. This paper presents the development of an AHP model and the derivation of a Quality Index through it. The model is used in a hypothetical case and a quality index was developed. The advantages of using such a technique are discussed.

• Journal of Navigation and Port Research
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• v.27 no.5
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• pp.479-486
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• 2003

The concept of “Environmental Stress(ES)” can be used as a useful index when assessing the maritime traffic safety. It is composed of two parts, one due to geographical restriction and another one due to traffic congestion. In this paper, Environmental Stress due to geographical restriction is reviewed Its characteristics are surveyed from the sample calculation results for some hypothetical cases, such as approaching a breakwater, navigating in a long straight channel, and in a long bended channel. Sample calculations are also carried out for the approach channels in Busan and Kwangyang harbor. By using this ES concept, it is expected that objective ana quantitative assessment of safety is possible for various environmental conditions when navigating in a harbor or in a fairway.