• Journal of Korean Tunnelling and Underground Space Association
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• v.4 no.3
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• pp.175-184
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• 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
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• v.18 no.3
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• pp.257-272
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• 2016

It is usually not an easy task to counter-measure on time and appropriately when confronting with troubles in mechanized tunnelling job-sites because of the limitation of available spaces to perform those actions with the existence of disk cutter, cutter head, chamber and other various apparatus in Tunnel Boring Machine (TBM). So, it is important to predict the ground condition ahead of a tunnel face during tunnel excavation. Efforts have been made to utilize geophysical methods such as elastic wave survey, electromagnetic wave survey, electrical resistivity survey, etc for predicting the ground condition ahead of the TBM tunnel face. Each prediction method among these geophysical methods has its own advantage and disadvantage. Therefore, it might be needed to apply several geophysical methods rather than just one to predict the ground condition ahead of the tunnel face in the complex and/or mixed grounds since those methods will compensate among others. The problem is that each prediction method will give us different answer on the predicted ground condition; how to combine different solutions into a most reasonable and representative predicted value might be important. Therefore, in this study, we proposed a methodology how to systematically combine each prediction method utilizing probabilistic analysis as well as analytic hierarchy process. The proposed methods is applied to a virtual job site to confirm the applicability of the model to predict the ground condition ahead of the tunnel face in the mechanized tunnelling.

• Journal of Yeungnam Medical Science
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• v.13 no.2
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• pp.261-271
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• 1996

Introduction: Osteoporosis, the most common metabolic bone disorder, is a condition of reduced bone density and increased susceptibility to fractures. Osteoporosis is a major public health problem and a significant cause of morbidity in postmenopausal women. Therefore family physicians as primary care physicians are in a key position for preventing and treating this disorder. So we studied the factors affecting to bone mineral density in postmenopausal women. Materials and Methods: A total of 136 spontaneous postmenopausal women were participated in the study. They have measured spinal bone mineral density by dual energy x-ray absorptiometry from January 1992 to June 1995 at Yeungnam University Hospital. Age, height, weight, age at menarche and menopause, number of child and breast feeding child, history of oral pill ingestion, family history of osteoporosis, amount of milk and coffee ingestion, consumption of tobacco and alcohol and physical activity were assessed by qustionnaire and medical records. Results: The mean age is 55.2 and mean age at menopause is 47.9. Height, weight and physical activity were significantly positive correlated to bone mineral density. But age, duration after menopause and number of child were significantly negative correlated. Also age, height, weight, physical activity and duration after menopause were significantly correlated to % age-matched bone mineral density. In multiple regression analysis, which dependent variable is bone mineral density, duration after menopause, physical activity and weight were significant contributors. Duration after menopause is most the largest contributor. In multiple regression analysis, which dependent variable is % age-matched bone mineral density to adjust the age effect, physical activity and weight were significant contributors. Physical activity is most the largest contributor. Conclusions: Among factors affecting to BMD in postmenopausal women, physical activity and weight were more important factors. Therefore continuous physical activity is significant factor to prevent osteoporosis in postmenopausal women.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.7 no.1
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• pp.25-31
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• 2009

An analytical method of $^{99}Tc$ concentration in soil was set up and discussed considering the $^{99}Tc$ concentration in Korean soil measured with its analytical method. A selective TEVA resin was used to separate and purify the $^{99}Tc$ in the soil sample. $^{99m}Tc$ from a commercial $^{99}Mo/^{99m}Tc$ generator was used as a yield tracer for the chemical separation of $^{99}Tc$ and its problem when using $^{99m}Tc$ as a tracer was discussed. The chemical recovery yield of $^{99}Tc$ was above 70%. The optimum conditions of inductively coupled plasma mass spectrometry system(ICP-MS) were set up to determine the $^{99}Tc$ after the separation process. The minimum detectable activity(MDA) was 15 mBq/kg-dry in this analytical procedure. The $^{99}Tc$ concentration in soils of Jeju and Kori were measured in the rage of 33.73-89.16 mBq/kg-dry. Those values were less than those reported in other countries and seemed to be originated from atmospheric fallout.

• Journal of the Korean Applied Science and Technology
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• v.37 no.4
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• pp.794-806
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• 2020

This study was conducted in order to attain an in-depth understanding of and describe the Ego-Integrity Phenomenon of the elderly of age 65 and older. The data was collected from June 2020 to July 2020 as an in-depth interview consisting of semi-structured questions. The data was analyzed using the Colaizzi's method, one of the phenomenology methods. All interviews were recorded and transcribed for analysis. Through analysis, 309 significant statements were extracted, and 88 formulations of meaning, 53 themes, 16 theme clusters, and 5 categories were derived. The categories and the theme clusters are as such : 'reflecting on the past life with delight' ('fruitfulness over the lifetime', 'achieving through fulfilling responsibilities', 'achieved specially and gratefully'), 'Currently lonely and distressed due to the bitter old days' ('Physical health needs and psychosocial needs are not met', 'Wasn't able to make good choices for parents and children', 'Elderly life is not easy'), 'Satisfaction from enduring tough and difficult journeys in life' ('Compensated for hard work at workplace and home', 'Problem solved through endurance and overcoming', 'Living a healthy elderly life by escaping from the habits of the past'), 'Realizing the way of life as an elderly' ('Now is the best and most satisfying moment', 'Managing self in old age', 'Living passionately, though it may be late', 'Retiring from the forefront of life with an abundant heart'), 'Passing on beautifully' ('Desires toward the later years', 'Hope during the last moments', 'Appearance and emotions when death approaches'). It was observed that during the Ego-Integrity Phenomenon of the elderly, they have come to discern the meaning of life by reminiscing the regrets and difficulties of the past, and through this reminiscence, they have come to attain a positive and transcendental hope for the rest of their lives. The Ego-Integrity of the elderly appeared to be subjective, dynamic, and occurring simultaneously rather than continuously. It is recommended to develop a variety of nursing interventions while taking into consideration the age and the type of experience of the elderly.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.1
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• pp.622-632
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• 2018

With the recent changes in the social environment, the growth in the so-called 'five major crimes' has been highlighted as one of the causes of anxiety in Koreans' lives. Many attempts have been made to solve this problem; however, it is still difficult to secure the location information of the socially vulnerable in emergency situations and to precisely identify the features and clothing of criminals and track them using current image analysis technology. Therefore, the development of precision positioning technology and support services along with intelligent security service technology based on spatial information has been given a high priority. This study suggested measures that could be continuously applied to link technologies and services with high linkability by analyzing technologies based on spatial information and other fields. To establish measures for linkage between intelligent security technology and other technologies and services, this study analyzed the existing technologies and research trends in intelligent security technology, and reviewed linkable services according to five criteria established to evaluate their linkability. Based on this analysis, three technologies with high linkability were ultimately selected, and measures for linkage were established. It is expected that the linkage measures derived using the objective evaluation criteria will serve as a stepping stone for promoting active technology linkage and commercialization in the future, even after the completion of this study.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.5
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• pp.77-83
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• 2020

4WD technology is being actively applied to passenger cars. Therefore, dry multi-plate clutches are used for transfer cases. On the other hand, dry clutches have problems related to large vibrations and poor ride quality. To solve this problem, this paper proposes a multi-plate clutch with an MR fluid. When fastening the multi-plate clutch in the transfer case, the proposed MR clutch was applied to reduce the shock and friction, which is a key component in a four-wheel-drive system. MR multi-plate clutch has a fluid coupling mode and a compression mode. A torque model equation was derived for the optimal design. The analysis was performed using Ansys Maxwell to optimize the design parameters of the multi-plate clutch. Electromagnetic field analysis confirmed the strength of the magnetic field when the number of disks and plates were changed, and the maximum strength of the magnetic field was 0.45 Tesla. By applying this to the torque equation, the spacing between the plates was 2 mm, and the inner and outer diameters of the plates were selected to be 45 mm and 55 mm, respectively. Overall, this paper proposes an optimal design technique to maximize the performance of an MR multi-plate clutch.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.2
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• pp.153-159
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• 2016

Gwangyang traffic safety designated area is composed of 3 fairways (Deep water fairway, inbound fairway, and outbound fairway). However, inbound vessels can't use this passage because of Samyeo rock and artificial fishing banks in inbound route. The problem with the rocks and artificial fishing banks has been raised by ship navigators and authorities of the port. This research is about the safety evaluation and management plan of the passage, and we conducted maritime traffic simulation using a model based on a ship operator risks. As a result, assuming that future marine traffic volume is the same as the present, and if the ship operators use 3 fairways and not two, it showed risk reduction of 46.4 % (vessels over 50,000 DWT using DW route) and 57.1 % (vessels over 10,000 DWT using DW route). Also, in a traffic volume condition which is the same as the present, to induce vessels over 50,000 DWT to use DW route is effective in mitigating of risks. Meanwhile, in a condition which increased the traffic volume by 150 %, it is more effective to induce vessels to use DW route. This research is the result of analysis using the model based on ship operator risks, and not cost-effectiveness analysis on the removal of Samyeo rock and artifical fishing banks. This research is expected to be used on setting up the sea route and management plan (particularly, restriction on passing DW route).

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.1
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• pp.126-132
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• 2018

This paper discusses about results of advanced buckling strength design for several kinds of perforated plated in the twin-hull car-ferry. For medium / small sized high speed vessels with a length of more than 50 meters and a length / width ratio of more than 12, such as car-ferries, it is highly possible that the buckling strength becomes weak due to the relatively thin thickness and the use of low strength capacity such as mild steel. Especially, it becomes big problem about weak buckling rigidity around the opening to access purpose in the perforated. As regarding safety design point of view for perforated plate, it is necessary to clarify buckling strength and ultimate strength by the distribution of in-plane load distribution around the opening. In this study, nonlinear series analysis using ANSYS was performed to clarify the influence of parameters such as aspect ratio, opening ratio and opening shape affecting the buckling and ultimate strength characteristics of the perforated plate under axial compression and we are derived the optimum design as buckling strength point of view. Based on these results, the governing factor determining the buckling strength of the perforated plate was the opening ratio, and the aspect ratio and the shape of the hole were not influenced.

• Journal of Korea Technology Innovation Society
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• v.18 no.3
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• pp.516-538
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• 2015

This study applies policy network theory to examine the main policy actors and their relations in the green growth policy making process. Also the development of and changes in South Korean government's green growth strategy are analyzed. The results demonstrate that the president and the presidential council were the key players to introduce and to push green growth policy in a short time. Policy influence and key roles were concentrated on them. The development of green growth policy were initiated from the president's change in perceived problems and preferences. He set green growth policy on the government's top priority. These changes lead to another changes in strategies, rules, norms and resources within the network. As a result, the president-led green growth policy established new laws, environmental regulations and governmental structures to facilitate the policy implementation. Green growth policy, however, was almost stopped after new presidential election in 2013. Because new government has a different national agenda, the previous governmental agenda lost its status as national priority. In addition, this study shows that government-led green growth in Korea has policy consistency problem after administration was changed by presidential election. Former president-led green growth policy making under the situation of the lack of policy participation from the private sector led to discontinuities in policy after a presidential term was over.