• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.7
• /
• pp.517-524
• /
• 2020

In line with the recent wave of the 4th Industrial Revolution, the environment for defense R&D is transforming into a center of high-tech military technology. In particular, developed countries are strengthening control of technology exports and technology transfer to protect advanced defense science and technology. For this reason, the budget demand for securing the ability to develop independently high-tech weapons and core technologies suitable for the future battlefield environment is increasing, and increasing efficiency in R&D investment has been highlighted for efficient distribution of limited budgets. This study examined the efficiency of the defense basic R&D project using the non-parametric approach, DEA. The R&D budget, R&D researcher, and R&D period were selected as the input variables, and the number of papers and patents were used as output variables. The efficiency of basic R&D projects was analyzed through CCR, BCC models, and SE. Lastly, based on the efficiency measurements, the cause of the inefficiency of R&D projects was suggested, and ways to improve efficiency were suggested. This study is expected to be used as useful information that can be applied to project performance management through efficiency analysis of basic defense R&D projects and be reflected in the project planning stage through feedback.

• Journal of Labour Economics
• /
• v.25 no.1
• /
• pp.47-74
• /
• 2002

Since the Economic Crisis at the end of 1997, unemployment rate soared up to the record-high 8.6% (February 1999) and, for youth aged 15~29, it was 14.6% (27.8% for aged 15~19). In spite of economic recovery after the crisis, new participants in labor market at the school-to-work transition have faced with difficulties in finding their first jobs and, even further, the ratio of youth at out-of the labor force but not in school has remained at a higher level. It is important to calibrate the negative effects of nonemployment in the short-run as well as in the long-run, but there has been few study on the school-to-work transition in Korea. This study focus on the nonemployment duration to first job after formal education and comparison of its pattern before and after the crisis. A proportional hazard model, considering job prenaration before graduation (21.4% of the sample), with the semi-parametric baseline hazard is applied to the sample from the Korean Labor and Income Panel Survey(1998~2000) and its Youth Supplemental survey(2000). Interview of the Survey is conducted, by the Korea Labor Institute, to the same 5,000 household and 13,738 individual sample, guaranteeing nationwide representativeness. The Supplemental Survey consists of 3,302 young individuals aged 15 to 29 at the time of survey and 1,615 of them who are not in school and provide appropriate information is used for the analysis. The empirical results show that there exists negative duration dependence at the first three or for months at the transition period and no duration dependence since a turning point of the baseline hazard rate and that unemployment rate reflecting labor demand conditions has a positive effect on exiting the nonemployment state, which is inconsistent with a theoretical conclusion. Estimation with samples separated by the date of graduation before and after the crisis shows that the effect of unemployment rate on the hazard was negative for the pre-crisis sample but positive for the post-crisis sample.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.4 no.3
• /
• pp.175-184
• /
• 2002

Ground reaction curve is very useful information for estimating the installation time of the tunnel support. The ground reaction curve can be estimated by analytical closed form solutions derived in case of circular section and isotropic stress condition. The nature of the ground reaction, however, depends significantly on tunnel configurations. Nevertheless, few purely analytical and experimental studies of this problem due to tunnel configurations appear to have been carried out. Therefore, it is necessary to investigate the influence of tunnel configurations in order to use simply in practical design. This paper describes a numerical study for the intial elastic displacement in the ground reaction curve due to configuration of tunnel excavation. In order to evaluate the applicability of analytical closed form solution in practical design, the parametric studies were carried out by numerical analysis in elastic tunnel behaviour. In the studies, S value, namely configuration factor, defined as the ratio between tunnel height (b) and width (a), varies between 0.5 and 3.0, initial ground vertical stress varies between 5~30 MPa for each S values. The results indicated that the self-supportability of ground is larger in the ground having low S value. It, however, is suggested that the applicability of closed form solution may not be adequate to determine directly the installation time of the support and self-supportability of ground. It should be necessary to perform the additional numerical analysis.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.20 no.2
• /
• pp.513-525
• /
• 2018

A 3 dimensional numerical analysis for shield TBM tunnel should take into account various characteristics of the shield TBM excavation, such as gap, tail void, segment installation, and backfill injection. However, analysis method considering excavation characteristics are generally mixed with various method, resulting in concern of consistency and reliability degradation of the analytical results. In this paper, a parametric study is carried out by using actually measured ground settlement data on various methods that can be used for 3 dimensional numerical analysis of shield TBM tunneling. As a result, we have analyzed and arranged an analytical method to predict similarly the behavior of ground settlement and tunnel face pressure at the design stage. Skin plate pressure, backfill pressure and soil model have been identified as the most significant influences on the ground settlement. The grout pressure model is considered to be applicable when there is no volume loss information on the excavated ground, such as seabed tunnels, or when it is important to identify the behavior around a tunnel, such as surface settlement as well as face pressure. And it is considered that designers can use these guidelines as a base material to perform a reasonable 3 dimensional numerical analysis that reflects the ground conditions and the features of the shield TBM tunneling.

• Journal of Korean Society of Environmental Engineers
• /
• v.27 no.10
• /
• pp.1081-1089
• /
• 2005

In order to examine the application feasibility of Orimulsion fuel in a commercial boiler using heavy fuel oil, a numerical and experimental research efforts have been made especially to figure out the fundamental combustion characteristics of this fuel in a small-scale boiler. One of the notable combustion features of Orimulsion fuel is the delayed appearance of flame location with the flame shape of rather broad distribution, which is found experimentally and confirmed by numerical calculation. This kind of flame characteristics is considered due to the high moisture content included inherently in the process of Orimulsion manufacture together with micro-explosion by the existence of fine water droplets. In order to investigate the effect on the combustion characteristics of Orimulsion, a series of parametric investigation have been made in terms of important design and operational variables such as injected amount of fuel, types of atomization fluid, and phonemenological radiation model employed in the calculation, etc. The delayed feature of peak flame can be alleviated by the adjustment of the flow rate of injected fuel and the generating features of CO, $SO_2$ and NO gases are also evaluated in the boiler. When the steam injection as atomizing fluid is used, the combustion process is stabilized with the reduced region of high flame temperature. In general, the calculation results are physically acceptable and consistent but some refinements of phenomenological models are necessary for the better resolution of pollutant formation. From the results of this small-scale Orimulsion boiler, it is believed that a number of useful information are obtained with the working computer program for the near future application of Orimulsion fuel to a conventional boiler.

• Journal of Korean Public Health Nursing
• /
• v.7 no.2
• /
• pp.39-52
• /
• 1993

The primary purpose of this study is to promote and establish the development of home health care in Korea. It focuses on identifying and classifying the nursing activities that were provided by health professionals for patients who were admitted to two hospitals with cerebral vascular disease. And also. the study was conducted for comparison of client selection criteria between health professionals, and identifying patients who needed home health care The subjects of this study were 38 patients with cerebral vascular disease who were admitted to neuro-surgery wards at 2 hospitals with more than 500 beds in Daegu from November 1. through 30. 1991. Survey instruments were questionnaires to identify nursing activities and classify patients who needed home health care. Data was collelected by 1 doctor and 2 nurses per patient independently. They checked the same patient with the questionnaire on the same day and never communicated their information about patients with each other. All the questionnaires checked by doctor and nurses completely were 90. Statistical methods for analyzing data were non-parametric tests (Kruskal Wallice test and sign test). Correlation and percentages were used for further analysis. From this study. the following summarized conclusions have been drawn. 1. 10. 2 kinds of treatment and nursing activities were provided by health professionals for patients with cerebral vascular disease in hospital. 2. The points of nursing needs were between 32-37 out of a total of 500 as a result of the assessment about the health status of patients who were admitted to neuro-surgery ward with cerebral vascular disease. The points of Barthel Index of Functional Status Assessing Devices were between 24-34. Client Selection Criteria for Home Health Care was congruent between the Health professionals because the difference were not found to be statistically significant. 3. Patients classfied as home health care clients were $70-80\%$ of all patients who were admitted in hospital. There was not significant difference in patient selection criteria for home health care between health professionals statistically. As a result. the validity of different tools used in classifying home health care client were found to be congruent. 4. $80-85\%$ patients who could be discharged and sent to their homes early were identified as home health care clients. This study using client selection criteria. for home health care contributed to tool development because the validity of tools was verified. And also, this research represented that there was congruency in patient selection criteria for home health care between different health professionals. As a result, this study represented that many patients who were admitted to hospitals could be classified as a home health care clients. On the basis of the findings. further studies are required to develop client selection criteria using universal tools for classifying home health care clients in other chronic diseases. It is also recommended that comparative studies for client selection criteria between health professionals treating in other chronic diseases are necessary.

• Journal of the Korean Geotechnical Society
• /
• v.18 no.6
• /
• pp.33-42
• /
• 2002

Ground reaction curve is a very important information for evaluating the side wall displacements and installation time of the tunnle support. The ground reaction curve can be estimated by analytical closed form solutions derived on the supposition of circular section and isotropic stress condition. The conditions of stress field and tunnel configurations, however, are quite different in practice. Therefore, it is necessary to investigate the effects of stress anisotropy and tunnel configurations in order to use simply in practical design. This paper describes a study of influence factors in the ground reaction curve. In order to evaluate the applicability of analytical closed form solution in practical design, two sets of parametric studies were carried out by numerical analysis in elastic tunnel behaviour: one set of studies investigated the influence of the K and the other set investigated the influence of the tunnel configurations such as circular and horse-shoe shape. In the studies, K value varies between 0.5 and 3.0, initial ground vertical stress varies between 5～30MPa far each K values. The results indicated that the self-supportability of ground is larger in the ground having lower K value. However, it is suggested that the applicability of closed form solution may not be adequate to determine directly the installation time of the support and self-supportability of ground. It is necessary to consider stress anisotropy and tunnel configurations.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.35 no.2
• /
• pp.501-514
• /
• 2015

Earthwork is a basic operation for all forms of civil works and affects construction time, cost and productivity. It is a mechanized operation that needs various construction equipment as a group and uses a lot of fuel for construction equipment. But, the problem is that earthwork operation is usually performed by equipment operator's heuristic and intuition, which can cause low productivity, high fuel consumption, and high carbon dioxide emission. As one of solutions for this problem, the fleet management system for construction equipment is suggested for effective earthwork planning, optimal equipment allocation, efficient machine operation, fast information exchange, and so forth. The purpose of this research is to suggest core methods for developing the equipment fleet management system. The methods include 3D solid parametric model generation, soil distribution using Cctree data structure, equipment fleet construction and equipment fleet operation. A simulation test is performed to verify the effectiveness of the equipment fleet management system in terms of equipment operating ratio, fuel usage, and $CO_2$ emission.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.31 no.6C
• /
• pp.203-212
• /
• 2011

This paper investigates the caharactheristics of the earth pressure magnigue and distribution in jointed rockmass for a safe and economic design and construction of earth retaining structures installed in rock stratum. For this purpose, this study will first investigate the limitations and problems of the existing earth pressure studies and then to overcome them th study will conduct the discontinuum numerical parametric studies based on the Discrete Element Method (DEM), which can consider the joint characteristics in rock stratum. The controlled parameters include rock type and joint conditions (joint shear strength and joint angle), and the magnitude and distribution characteristics of earth pressure have been investigated considering the interactions between the ground and the retaining structures. In addition, the comparison between the earth pressures induced in rock stratum and Peck's earth pressure for soil ground has been carried out. From the comparison, it is found that the earth pressure magnitude and distribution in jointed rockmass has been highly affected by rock type and joint condition and has shown different characteristics compared with the Peck's empirical earth pressure. This result would hereafter be utilized as an important information and a useful data for the assessment of earth pressure for designing a retaining structures installed in jointed rockmass.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.31 no.5
• /
• pp.267-274
• /
• 2018

For successful BIM settlement, it is a key technic for engineer to design structures in the 3-dimensional digital space and to work out related design documents directly. Lately many BIM tool has been released and each supports their 3-dimensional object libraries. But it is not easy to apply those libraries to design transportation infra structures that were placed along the route(3-dimensional line). Moreover, in case of design changes, it is so difficult to reflect those changes with the integrated model that was assembled by them. Because of they were developed without consideration for redundancy of parameters between objects that were placed nearby or were related each other. In this paper, a method to develop module for modeling and placing 3-dimensional object for transportation infra structures is presented. The modules are employed by a parametric method and can deal with design changes. Also, for a railroad bridge, through developing user interface of the integrated 3-dimensional model that was assembled by those modules the applicability of them was reviewed.