• Journal of the Korean Society of Safety
• /
• v.29 no.6
• /
• pp.68-75
• /
• 2014

It is very important to classify explosion hazardous area (EHA) suitably and to use proper explosion-proof electric installations for facilities using flammable gases and liquids. In the past, various examples in the Notification of Ministry of Employment and Labor were referred to in classifying EHA. But, at present, many companies use the hypothetical volume in Korean Standards (KS). This study reviews the validity of EHA classification based on the hypothetical volume by comparing the calculated radii of EHA with those obtained by a consequence analysis program called PHAST and a mathematical approach in British Standards (BS). The radii of EHA by the hypothetical volume were found to be slightly larger than those by the other two methods. This was attributed to rather conservative uses of a safety factor(k) and a correction factor(f) for availability of ventilation in calculating the hypothetical volume. Since the differences are not so conspicuous, however, it is concluded that the hypothetical volume in KS is a valid means for the classification of EHA. This study also presents a table of the radii of EHA for easy reference by small-scale companies using city gas, C3-LPG and flammable liquid(toluene), respectively. The table consists of 25 leakage scenarios corresponding to combinations of 5 pipe(nozzle) sizes and 5 operating conditions for each flammable gas and liquid.

• Journal of the Korean Society of Safety
• /
• v.29 no.2
• /
• pp.24-30
• /
• 2014

There have been controversies over whether explosion hazardous area(EHA) should be classified for facilities which use lighter-than-air gases such as city gas, hydrogen and ammonia. Two view points are confronting each other: an economic piont of view that these gases are lighter than air and disperse rapidly, hence do not form EHA upon release into the atmosphere, and a safety point of view that they are also inflammable gases, hence can form EHA although the extent is limited compared to heavy gases. But various standards such as KS, IEC, API, NFPA do not exclude light gases when classifying EHA and present examples of EHA for light gas facilities. This study calculates EHA using the hypothetical volume in the IEC code where the hole sizes required for the calculation were selected according to various nominal pipe sizes in such a way to conform to the EHA data in the API code and HSL. Then, 25 leakage scenarios were suggested for 5 different pipe sizes and 5 operating pressures that cover typical operating conditions of light gas facilities. The EHA for the minimum leakage scenario(25 mm pipe, 0.01MPa pressure) was found to correspond to a hypothetical volume larger than 0.1 $m^3$(medium-level ventilation). This confirms the validity of classifying EHA for facilities using lighter-than-air gases. Finally, a computer program called HACPL was developed for easy use by light gas facilities that classifies EHA according to operating pressures and pipe sizes.

• Journal of East-West Nursing Research
• /
• v.27 no.2
• /
• pp.95-103
• /
• 2021

Purpose: This study was conducted to investigate the structural equation modeling of retention intention in nurses. Methods: A total of 210 nurses from three hospitals in B city, South Korea participated in this study. A structural equation model was constructed to verify the fitness of this model. Data were analyzed using SPSS 20.0 and AMOS 21.0 programs. Results: The hypothetical model appeared to fit the data. Three of the selected six hypotheses for the hypothetical model were statistically significant. The retention intention model showed significant direct effects for job crafting and job demands and indirect effects for relation oriented culture, which explained 28% of the variation in nurses' retention intention. Conclusion: We found that nurses' job crafting behavior and job demands had significant influences on retention intention and relation oriented culture which affected by the factors job crafting.

• Spatial Information Research
• /
• v.10 no.4
• /
• pp.515-532
• /
• 2002

Planning Support System (PSS), an alternative framework of computer-aided planning system combining geographic information system (GIS), urban models, and visualization tools, has been actively researched and applied in many developed countries. This paper introduces a PSS-based land use change model, What if\ulcorner PSS, by applying it to Chongju City, Korea. This model application study used the spatial database, Restricted Development Zone (RDZ), and other hypothetical land supply- and demand-related policies of Chongju City. The collaborative PSS model supported land use planning process by helping users to speedily and easily create and test policy-oriented scenarios. The study found that the fully operational PSS model was readily applicable and useful to Korean local land use planning. The paper discusses the conceptual model framework, data requirement, application process, model output, and practical usage. This study would be considered as a prototypical approach of PSS-based land use plan making for Korean cities.

• Journal of the Korean Regional Science Association
• /
• v.6 no.2
• /
• pp.107-121
• /
• 1990

The structural change of occupational composition with the coming of post-industrial society is most evidently observed in the developed country. Specially representative of social changes is the emergence of new occupational sectors, such as the so-called quaternary and quinary sectors, which are based on the use of information technology and managerial skills. The paper raises the question of how and in what this chage of occupational components in a mtro area affects the existing residential structure over the period. In order to extend the discussion of the question, the related hypothetical statements on urban spatial impact due to transformation of the society have xtnsively considered and identified a possible multicenter structure concentration and deconcentration of new jobs and population over the metro area. For further examination, the renowned high tech city of Minneaplis -St. Paul has been selected and the occupational labour forces data for 1960 and 1980 analyzed. As a whole, this area has experienced a dispersal and reconcentration of population in new patterns which have resulted from changes in the occupational structure. In particular, the residential area of white-coller workers(the quaternary / quinary or information workers) has expanded into the city from a suburban core area. In this process, a large proportion of the manual-worker's residential areas in the central city either disappeared or diminished. Consequently, other isolated centers created by the manualworker residents are emerging in both the central city and suburbs. Thus, the development of mulitple centers or cores based on the distribution of occupational characteristics can be considered as a typical ongoing pattern of metro areas in the Unite States.

• Journal of Korean Academy of Nursing
• /
• v.44 no.6
• /
• pp.660-671
• /
• 2014

Purpose: The aims of this study were to construct a hypothetical structural model which explains the premenstrual syndrome (PMS) in adolescent girls and to test the fitness with collected data. Methods: The participants were 1,087 adolescent girls from 3 high schools and 5 middle schools in B city. Data were collected from July 3 to October 15, 2012 using self-reported questionnaires and were analyzed using PASW 18.0 and AMOS 16.0 programs. Results: The overall fitness indices of hypothetical model were good (${\chi}^2$ =1555, p<.001), ${\chi}^2$/df=4.40, SRMR=.04, GFI=.91, RMSEA=.05, NFI=.90, TLI=.91, CFI=.92, AIC=1717). Out of 16 paths, 12 were statistically significant. Daily hassles had the greatest impact on PMS in the adolescent girls in this model. In addition, PMS in adolescent girls was directly affected by menarche age, Body Mass Index (BMI), amount of menstruation, test anxiety, social support, menstrual attitude and femininity but not by academic stress. This model explained 27% of the variance in PMS in adolescent girls. Conclusion: The findings from this study suggest that nursing interventions to reduce PMS in adolescent girls should address their daily hassles, test anxiety, menstrual attitude and BMI. Also, social support from their parents, friends, and teachers needs to be increased.

• Journal of Korean Academy of Nursing
• /
• v.46 no.5
• /
• pp.630-641
• /
• 2016

Purpose: This study was designed to construct a model which explains drug misuse behaviors in community-dwelling older adults. Methods: The design of this research is a cross-sectional study using structure equation modeling. The hypothetical model consisted of two types of variables: the exogenous variables of health status, cognitive ability, and negative emotion, and the endogenous variables of number of drugs, and drug misuse behaviors. The data collection was conducted from September 2 to September 21, 2013 through self-report questionnaires. Participants were 320 community-dwelling adults over the age of 65 living in J city. Data were analyzed with SPSS 21.0 program and Amos 18.0 program. Results: The results of the model fitness analysis were satisfied. The predictor variables for the hypothetical model explained 62.3% of variance regarding drug misuse behaviors. Drug misuse behaviors were directly affected by health status, cognitive ability, negative emotion and number of drugs and indirectly affected by health status, and negative emotion through number of drugs. Conclusion: These findings indicate factors that should be used in developing effective nursing interventions for safe and proper drug use and the prevention of drug misuse behaviors in community-dwelling older adults.

• Journal of the Korean Applied Science and Technology
• /
• v.35 no.3
• /
• pp.606-611
• /
• 2018

City natural gas is classified flammable hazardous gas and should be secured according to explosion risk assessment determined by Industrial Standard KS C IEC. In this study, leak size, ventilation grade and effectiveness were adopted to the KS C IEC for risk assessment in natural gas supply system. To evaluate the applicability of the computational fluid dynamics (CFD), the risk assessment was studied for four different conditions using hypothetical volume($V_z$) valuesfrom gas leak experiments, KS C IEC calculation, and CFD simulation.

• Journal of Korean Academy of Nursing
• /
• v.48 no.5
• /
• pp.521-533
• /
• 2018

Purpose: The aims of this study are to provide a theoretical framework for improving the self-care of adults with severe hypertension and to examine the practical suitability of a middle-range theory of self-care for chronic illness by validating the structural model. Methods: Data were collected at a university hospital in D metropolitan city from July 1 to August 14, 2015. A total of 224 Korean adult patients with severe hypertension were recruited. Data were analyzed using SPSS 22.0 and AMOS 22.0. Results: The results show that the fit index of the hypothetical model meets the recommended level; 7 out of 8 hypothetical model paths were statistically significant. Motivation, self-efficacy, support from others, and accessibility to care showed statistical significance and explained 67.3% of the self-care process. The self-care process explained 45.3%, 63.6%, and 26.5% of quality of life, health, and illness stability, respectively. Conclusion: This model can be used as a theoretical framework for improving self-care among adult Korean patients with severe hypertension. Moreover, the practical suitability and validity of the middle-range theory of self-care for chronic illness is secured.

• International conference on construction engineering and project management
• /
• 2022.06a
• /
• pp.222-229
• /
• 2022

Although stochastic programming and feedback control approaches could efficiently mitigate the overdue risks caused by inherent uncertainties in ground conditions, the lack of formal representations of planners' rationales for resource allocation still prevents planners from applying these approaches due to the inability to consider comprehensive resource allocation policies for hard rock tunnel projects. To overcome the limitations, the authors developed an ontology that represents the project duration estimation rationales, considering the impacts of ground conditions, excavation methods, project states, resources (i.e., given equipment fleet), and resource allocation policies (RAPs). This ontology consists of 5 main classes with 22 subclasses. It enables planners to explicitly and comprehensively represent the necessary information to rapidly and consistently estimate the excavation durations during construction. 10 rule sets (i.e., policies) are considered and categorized into two types: non-progress-related and progress-related policies. In order to provide simplified information about the remaining durations of phases for progress-related policies, the ontology also represents encoding principles. The estimation of excavation schedules is carried out based on a hypothetical example considering two types of policies. The estimation results reveal the feasibility, potential for flexibility, and comprehensiveness of the developed ontology. Further research to improve the duration estimation methodology is warranted.