• Wind and Structures
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• 제12권4호
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• pp.313-332
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• 2009

This paper numerically and experimentally investigates the control performance of the active mass damper (AMD) systems in a 26-story high-rise building in use. This is the first full-scale application of the AMD system for suppressing the wind-induced vibration of a building structure in Korea. In addition, the AMD system was installed on top of the building already in use, which may be the world's first implementation case. In order to simultaneously mitigate the transverse-torsional coupled vibration of the building, two AMD systems were applied. Moreover, the H-infinity control algorithm has been developed to utilize the maximum capacity of the AMD system. From the results of numerical simulation using the wind load obtained from the wind tunnel tests, it was found that the maximum acceleration responses of the building were reduced significantly. Moreover, the control performance of the installed AMD system was examined by carrying out the free and forced vibration tests. The acceleration responses on top of the building in the controlled case measured under strong wind loads were compared with those in the uncontrolled case numerically simulated by using the wind load deduced from the measured data and a structural model of the building. It is demonstrated that the AMD system shows good control performance in reducing the building accelerations.

• Current Industrial and Technological Trends in Aerospace
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• 제7권1호
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• pp.32-42
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• 2009

Required system and technology for the civil helicopter and the military helicopter are almost similar. A lot of mount helicopters are converted from military to civil, or converted oppositely, or new developed considering civil-military dual use in order to reduce development cost and period. In the case of converting the military to the civil, the military helicopters are developed based on sufficient requiring amount following conversion to the civil helicopters with minor modification. This paper presents the investigation and the analysis for the case and the approach of dual use helicopter development from military helicopters to civil helicopters.

• The Korea Journal of Herbology
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• 제38권2호
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• pp.9-16
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• 2023

Objectives : Many people use natural soap instead of commercially available bar type general soap for skin care. They tend to prefer cp (cold process) type soaps that go through a sufficient maturation process in formulation. The purpose of this study was to investigate the efficacy of PCPS (placenta cp soap). Methods : The researcher selected 36 subjects, 28 as the experimental group and 8 as the control group. I asked participants to wash their face twice a day in the morning and evening, and the period was set for 6 weeks. The researcher had the people who were selected as the control group use a commercially available foam cleanser, meanwhile the experimental group use PCPS. They performed a skin test before the start of the test, and the change status was continuously investigated after 2 weeks, 4 weeks, and 6 weeks after using the soap. Results : In the case of U zone oil and pores, there was a significant decrease and in the case of skin tone, there was a significant increase in the group of using PCPS. In T zone oil change, there was no significant effect in both the experimental group and the control group. Conclusion : In the case of PCPS, it is recommended to use it in the effect of reducing the size of pores and increasing skin tone, but it can reduce u-zone oil content.

• Journal of the Korea Institute of Information Security & Cryptology
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• 제14권3호
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• pp.85-100
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• 2004

All information system is information security system that enforced security function. To improve qualify of information security system, suity requirement analysis and specification must be Performed by consistently and typically at early requirement analysis step. In this paper, we propose a security requirements analysis and specification model and process by using Misuse Case Model that extends UML's Use Case Model. And, we propose a cost-effective security product selection algorithm that security product is sufficient of all constructed security functional requirements. It may raise quality of information security system that developed through proposed model and process.

• Proceedings of the Korea Water Resources Association Conference
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• 한국수자원학회 2008년도 학술발표회 논문집
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• pp.102-106
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• 2008

This study is to evaluated the impact of varying spatial resolutions of DEM (2 m, 10 m, and 30 m), land use (QuickBird, 1/25,000 and Landsat), and soil data (1/25,000 and 1/50,000) on the uncertainty of Soil and Water Assessment Tool (SWAT) predicted streamflow, sediment, T-N, and T-P transport in a small agricultural watershed ($1.21\;km^2$). SWAT model was adopted and the model was calibrated for a $255.4\;km^2$ watershed using 30 m DEM, Landsat land use, and 1/25,000 soil data. The model was run with the combination of three DEM, land use, and soil map respectively. The SWAT model was calibrated for 2 years (1999-2000) using daily streamflow and monthly water quality (SS, T-N, T-P) records from 1999 to 2000, and verified for another 2 years (2001-2002). The average Nash and Sutcliffe model efficiency was 0.59 for streamflow and the root mean square error were 2.08, 4.30 and 0.70 tons/yr for sediment, T-N and T-P respectively. The hydrological results showed that output uncertainty was biggest by spatial resolution of land use. Streamflow increase the watershed average CN value of QucikBird land use was 0.4 and 1.8 higher than those of 1/25,000 and Landsat land use caused increase of streamflow.

• The Journal of Information Systems
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• 제19권3호
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• pp.209-236
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• 2010

Recently, utilization of mobile Internet services is rapidly increasing. To properly accelerate the vitalization of mobile Internet usage, we have to know exactly about the factors affecting potential users' value recognition and intention to use. Technology acceptance model (TAM) is one of the most powerful reference framework for the individual user's adoption of IT innovations. This research borrowed core concept of TAM, and tried to explain users' intention to use mobile Internet by understanding the direct and indirect effects of subjective norm and perceived usefulness. To increase the explanatory power of the model, this paper introduced personal innovativeness as a key moderator variable. The research findings include; i) subjective norm has strong positive influence on perceived usefulness and intention to use, ii) perceived usefulness has positive influence on intention to use, iii) the influence of subject norm is greater than that of perceived usefulness, iv) positive influence of subjective norm on the perceived usefulness and intention to use are significantly stronger in the case of low personal innovativeness sub-group than the case of high personal innovativeness sub-group, and v) high personal innovativeness sub-group have shown strongly positive influence of perceived usefulness on the intention to use while there is no such significant relationship in the case of low personal innovativeness sub-group. Based on these findings, this paper proposed several guidelines to increase the adoption and the usage of mobile Internet; i) word-of-mouth is extremely important, ii) to form a good word-of-mouth, it will be very important to make early adopters and heavy users have positive direct experiences of using mobile Internet.

• Journal of the Korean Institute of Landscape Architecture
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• 제30권6호
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• pp.38-46
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• 2003

Perceived crowding is known as a necessary method to evaluate social carrying capacity in recreational settings. But according to the results of previous research, perceived crowding, use density, and satisfaction have shown weak and indirect correlations. The theory of visitors’ adjustment is one of several possible explanations for this poor relation. But the validity of the visitors’ adjustment theory has not been not inspected clearly. Therefore, the purposes of this study are to understand visitors’ adjustment theory and to examine visitors’ adjustment to the overuse of recreational settings. Study hypotheses were formulated through literature review and related to visitors’ adjustment in recreation density. Pour hypotheses were established and inspected with the case study, i.e., Rationalization : Visitors’ satisfaction isn't related to use density in recreation setting, 2) Product-shift : Preference norm is related to current use density, 3) Self-selection : Visitors’ satisfaction for the use level is generally high, and 4) Displacement : Norm interference is related to willingness to revisit. The case study was conducted during May and June,2001. According to the results of this survey, visitors adjust to overuse of recreation setting through rationalization and product shift (hypotheses l/2 acceptance). Current use density isn't related to visitors’ satisfaction and willingness to revisit (see table 3). And visitors’ preference norm is modified by situation (see table 4). Visitors’ satisfaction and willingness to revisit don't show a high correlation but moderately high (see table 5, hypothesis 3 acceptance). Differences between visitors’ preference norm and current use density is norm interference. Norm interference isn't related to willingness to revisit (see table 7). Therefore, the norm interference concept is not a useful method to explain visitors’ adjustment to the degree of overuse in a recreational setting (hypothesis 4 rejection). As for future directions, the following are proposed: 1) correctly understanding and reestablishing the visitor norm and norm interference concept, 2) introducing a composite research method to monitor visitors’ behavior and survey visitors’ attitudes and coping responses. These efforts would be helpful in the Planning and management of recreational settings to improve the quality of visitors’ experiences.

• Journal of Korean Society of Rural Planning
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• 제9권2호
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• pp.49-55
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• 2003

The purpose of this study is to analyze the impact of land-use and population change in rural area by new expressway. Chungbu expressway constructed in 1987, going through the south area of Kyunggi province from Seoul, was selected as a case expressway, and also 2 cities and 18 subdivisions of county in its surrounding area, as a case study area. To analyze the change characteristics before and after the construction, land-use maps of 1986 and 1996 were collected, including the census data for the years in cities and counties yearbooks. Remote sensing technology was applied to classify the land-use maps with six types of land use. Geographic information system was also used for spatial analysis, such as the land-use and accessibility changes. A 5 km buffer zone from interchange of the expressway showed about two times increase of urbanized built-up area than a 5 km buffer zone from the expressway. Accessibility from Seoul and cities was improved in most areas, which is accessing to Seoul through existing Youngdong expressway. Ten rural areas showed increased population with accessibility of average 52 minutes to Seoul and 19 minutes to cities, while eight areas showed decreased population with average 73 minutes to Seoul and 35 minutes to cities. This shows that the threshold value, which is time distance to Seoul and cities for population increase or decrease, one and half hours, respectively. Urbanized area was increased in most areas, even in population decrease areas, so this indicates that there are thinning rural areas, increasing urbanized area while decreasing population.

• The Korean journal of internal medicine
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• 제39권2호
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• pp.228-237
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• 2024

Background/Aims: Long-term use of acid suppressants such as proton pump inhibitors (PPIs) and histamine 2 receptor antagonist (H2RA) has been associated with the risk of osteoporotic fracture. Acid suppressants and muco-protective agents (MPAs) are often used together as anti-ulcer agents. We evaluated the association between the risk of osteoporotic fracture and the combined use of these anti-peptic agents. Methods: A population-based case-control study was conducted by analyzing the Korean National Health Insurance Data from 2014 to 2020. Patients who had been prescribed anti-peptic agents, such as PPI, H2RA, or MPA, were included. Considering the incidence of osteoporotic fractures, the case group (n = 14,704) and control group (n = 58,816) were classified by 1:4 matching based on age and sex. Results: The use of all types of anti-peptic agents was associated with an increased risk of osteoporotic fractures (PPI: hazard ratio [HR], 1.31; H2RA: HR, 1.44; and MPA: HR, 1.33; all p < 0.001). Compared to PPI alone, the combined use of "PPI and H2RA" (HR, 1.58; p = 0.010) as well as "PPI, H2RA, and MPA" (HR, 1.71; p = 0.001) was associated with an increased risk of osteoporotic fracture. However, compared with PPI alone, "MPA and PPI or H2RA" was not associated with an increased risk of osteoporotic fracture. Conclusions: This study found that the combined use of "PPI and H2RA" was associated with a higher risk of osteoporotic fractures. In cases where deemed necessary, the physicians may initially consider prescribing the combination use of MPA.

• Journal of Information Technology Applications and Management
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• 제20권1호
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• pp.1-17
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• 2013

It has been found that users' characteristics are important variables that explain information systems adoption. These user groups, which are called COIs (Community Of Interests), might show different behaviors to each other to the same information system. We study differences in MDM (master data management) system adoption between military users and SI developers using TAM (Technology Acceptance Model). In case of military users, the perceived usefulness of an MDM system does not have impacts on intention to use an MDM system. Only the ease of use of an MDM system has impacts on intention to use an MDM system. However, in case of SI developers, both the perceived usefulness and the ease of use of an MDM system have impacts on intention to use an MDM system, which are similar to findings in previous studies. These results might be interpreted that users do not pay much attention to the usefulness in adopting a new information system in a centralized organization. They are obligated to use an information system whether it is useful or not. Thus the ease of use has more impacts on users than the usefulness.