• Journal of the Korean Society for Nondestructive Testing
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• v.19 no.1
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• pp.8-15
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• 1999

In order to develop an effective way of measuring the mode I stress intensity factor, $K_I$, by the technique based on the alternating current potential drop (ACPD), the effect of the magnetic flux in the air on the change in potential drop due to load for both ferromagnetic and paramagnetic materials containing a two-dimensional surface crack was investigated. Additionally the effects of the demagnetization and the crack length on the change in potential drop were examined. In the case that the measuring system was designed to induce a large amount of electromotive force, the amount of the change in potential drop due to load was shown to increase largely Also the relationship between the change in potential drop and that in $K_I$ was indicated to be linear without any treatment and it was shown that the demagnetization had almost no effect on the change in potential drop. The change in potential drop did not depend on the crack length but on the measuring system. For the application of the ACPD technique to determine $K_I$.

• Fire Science and Engineering
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• v.30 no.4
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• pp.82-87
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• 2016

The ventilation system for the efficient operation of the building services systems in the ventilation plan of super high-rise buildings is used to combine smoke control systems. This study evaluated models of super high-rise buildings with four basement levels and 59 stories and investigated the pressure distribution of each floor by the smoke driving forces by numerical analysis. The smoke driving forces on the building of analytical model was analyzed to determine the effects of the ventilation plan and smoke control plane. In addition, when a combination with ventilation and smoke control of the kitchen ventilation damper in the ventilation plan of analysis model building was designed based on the these results, the relationship between the opening and closing force of the damper and smoke driving combined forces to act on the design pressure of the damper by a motion analysis simulation. The driving units of the damper were selected from the analytical results.

• The korean journal of orthodontics
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• v.50 no.1
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• pp.42-51
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• 2020

Objective: The objective of this study was to evaluate the effects of cetirizine, a histamine 1 receptor antagonist, on bone remodeling after calvarial suture expansion. Methods: Sixty male Sprague-Dawley rats were divided into 4 groups; the phosphate-buffered saline (PBS)-injected no expansion group, cetirizine-injected no expansion group, PBS-injected expansion group, and cetirizine-injected expansion group, and were observed at 7, 14, and 28 days. Five rats per group were examined at each observation day. Daily injections of cetirizine or PBS were administered to the relevant groups starting 2 weeks prior to expander insertion. A rapid expander was inserted in the calvarial bone to deliver 100 cN of force to the parietal suture. The specimens were prepared for hematoxylin and eosin and tartrate-resistant acid phosphatase (TRAP) staining. Suture opening and bone regeneration were evaluated using microcomputed tomography and bone histomorphometric analysis. Serum blood levels of osteocalcin and carboxy-terminal collagen crosslinks (CTX) were also evaluated. Results: TRAP-positive cell counts and CTX levels decreased while osteocalcin levels increased in the cetirizine-injected expansion group at observation day 28. In the expansion groups, the mineralized area gradually increased throughout the observation period. At day 28, the cetirizine-injected expansion group showed greater bone volume density, greater mineralized area, and narrower average suture width than did the PBS-injected expansion group. Conclusions: Cetirizine injection facilitated bone formation after suture expansion, mostly by suppressing osteoclastic activity. Histamine 1 receptor antagonists may aid in bone formation after calvarial suture expansion in the rat model.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.208-208
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• 2013

Graphene has emerged as a fascinating material for next-generation nanoelectronics due to its outstanding electronic properties. In particular, graphene-based field effect transistors (GFETs) have been a promising research subject due to their superior response times, which are due to extremely high electron mobility at room temperature. The biggest challenges in GFET applications are control of carrier concentration and opening the bandgap of graphene. To overcome these problems, three approaches to doping graphene have been developed. Here we demonstrate the decoration of Ni nanoparticles (NPs) on graphene films by simple annealing for p-type doping of graphene. Ni NPs/graphene films were fabricated by coating a $NiCl2{\cdot}6H2O$ solution onto graphene followedby annealing. Scanning electron microscopy and atomic force microscopy revealed that high-density, uniformly sized Ni NPs were formed on the graphene films and the density of the Ni NPs increased gradually with increasing $NiCl2{\cdot}6H2O$ concentration. The formation of Ni NPs on graphene films was explained by heat-driven dechlorination and subsequent particlization, as investigated by X-ray photoelectron spectroscopy. The doping effect of Ni NPs onto graphene films was verified by Raman spectroscopy and electrical transport measurements.

• The Korean Journal of Ecology
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• v.22 no.1
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• pp.31-37
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• 1999

The developmental process of Paracolopha morrisoni's galls on Zelkova serrata until the emergence of alatae from the galls was studied at Chonju, Korea. The galls were formed from late April to early May, 1997 and the galls began to open in early June. The length and width of galls and leaves were measured during the period from gall formation to opening. The length and width of galls have been increased until mid May continuously. The galls stopped growing at 12th of May. Fundatrices (the first generation in the gall) began to larviposit from May 15th and the second generation developed in late May. The alatae of the second generation arrived at the final stadium, that was escaped from the gall, in early June. Thus, there were only 2 generations in the gall. The close correlationship between gall growth and leaf growth suggests that leaf growth force may have a great influence on gall development.

• The korean journal of orthodontics
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• v.50 no.3
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• pp.206-215
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• 2020

Osteochondroma is a common benign tumor of bones, but it is rare in the mandibular condyle. With its outgrowth it manifests clinically as deviation of the mandible limitation of mouth opening, and facial asymmetry. After the tumor is diagnosed on the basis of clinical symptoms and radiographic examination including cone-beam computed tomography (CBCT) analysis, an appropriate surgery and treatment plan should be formulated. Herein, we present the case of a 44-year-old female patient who visited our dental hospital because her chin point had been deviating to the left side slowly but progressively over the last 3 years and she had difficulty masticating. Based on CBCT, she was diagnosed with skeletal Class III malocclusion accompanied by osteochondroma of the right mandibular condyle. Maxillary occlusal cant with the right side down was observed, but it was confirmed to be an extrusion of the molars associated with dental compensation. Therefore, after intrusion of the right molars with the use of temporary anchorage devices, sagittal split ramus osteotomy was used to remove the tumor and perform orthognathic surgery simultaneously. During 6 months after the surgery, continuous bone resorption and remodeling were observed in the condyle of the affected side, which led to a change in occlusion. During the postoperative orthodontic treatment, intrusive force and buccal torque were applied to the molars on the affected side, and a proper buccal overjet was created. After 18 months, CBCT revealed that the rate of bone absorption was continuously reduced, bone corticalization appeared, and good occlusion and a satisfying facial profile were achieved.

• Journal of Korean Port Research
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• v.13 no.2
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• pp.313-322
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• 1999

Pusan the principal port of South Korea, has opened its door since 1876. Currently, the four-stage port construction project is under way to handle ever-growing marine transportation volume. While the port unloading capabilities are increasing the infrastructure to deal with all the transportation volume failed to catch up with them. Accordingly the city had to suffer from worst traffic congestion on due to the increasing container traffic volume causing logistical costs to rise. This study was designed to inspect the enforcement of infrastructure construction plan and suggest systematical and effective ways to improve the plan. The study focused on :\circled1The decision-making procedure, \circled2Financial resource for the plan, \circled3Effectiveness of the project enforcement, and \circled4Who will be in charge of the project. As a result from the study, these followings were suggested to improve the plan. First, Pusan Port Infrastructure consisting of (Inter-city Free way, Belt Highway and Outer Highway) should be immediately legally-regulation project. Second, the method to finance the project should be deter-mined and investment consultation among the central government the city government and private sector should be also made. Measures to make the central government budget allocation for the project mandatory should be discussed. Third, Effectiveness of the project can be doubled by gradually or partialyl opening the routes based on long-term or short-term operating plans. Fourth, The organizer of the project should be appointed, or a special task-force team in charge of the plan can be formed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.11
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• pp.1741-1751
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• 2004

It is commonly requested that the steam generator tubes wall-thinned in excess of 40% should be plugged. However, the plugging criterion is known to be too conservative for some locations and types of defects and its application is limited to a single crack in spite of the fact that the occurrence of multiple through-wall cracks is more common in general. The objective of this research is to propose the optimum failure prediction models for two adjacent through-wall cracks in steam generator tubes. The conservatism of the present plugging criteria was reviewed using the existing failure prediction models for a single crack, and six new failure prediction models for multiple through-wall cracks have been introduced. Then, in order to determine the optimum ones among these new local or global failure prediction models, a series of plastic collapse tests and corresponding finite element analyses for two adjacent through-wall cracks in thin plate were carried out. Thereby, the reaction force model, plastic zone contact model and COD (Crack-Opening Displacement) base model were selected as the optimum ones for assessment of steam generator tubes with multiple through-wall cracks. The selected optimum failure prediction models, finally, were used to estimate the coalescence pressure of two adjacent through-wall cracks in steam generator tubes.

• Korean Chemical Engineering Research
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• v.43 no.3
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• pp.331-343
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• 2005

Development of hydrogen station system is an important technology to commercialize fuel cells and fuel cell powered vehicles. Generally, hydrogen station consists of hydrogen production process including desulfurizer, reformer, water gas shift (WGS) reactor and pressure swing adsorption (PSA) apparatus, and post-treatment process including compressor, storage and distributer. In this review, we investigate the R&D trends and prospects of hydrogen station in domestic and foreign countries for opening the hydrogen economy society. Indeed, the reforming of fossil fuels for hydrogen production will be essential technology until the ultimate process that may be water hydrolysis using renewable energy source such as solar energy, wind force etc, will be commercialized in the future. Hence, we also review the research trends on unit technologies such as the desulfurization, reforming reaction of fossil fuels, water gas shift reaction and hydrogen separation for hydrogen station applications.

• Journal of Society of Preventive Korean Medicine
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• v.12 no.2
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• pp.73-83
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• 2008

The rapid change of the health and medical environment and the globalization of medicine has driven doctors to converge and analyse of new and up-to-date medical information and decide to what to make decision for diagnosis and treatments in clinical practice. Medical environment goes with the changes with social environment such as rapid increase of aging population, changes of disease pattern, formation of new area of experts except doctors, government intervention for the medical system, medical insurance of the charges of medical treatment, a increased desire for human rights. These trends should be adopted rapidly to the education system for the students of medical school. The learning objectives of the preventive medicine was developed in 1995 and underwent necessary revision of the contents to create the first revision in 2006. However, the required educational contents of health promotion and disease prevention have been changed by the new trends of medical education such as PBL and integrated curriculum and the 2006 revision does not satisfy these needs. We formed a task force which surveyed all the Western and Traditional Korean medical colleges to describe the state of preventive medicine education in Korea, analyzed the changing education demand according to the change of health environment and quantitatively measured the validity and usefulness of each learning objective in the previous curriculum. With these results, for the good education for preventive medicine, each Traditional Korean medicine schools need more preventive medicine faculties and teaching assistants and opening of some required subjects such as Yangsaeng and Qigong. And future studies of the learning process and ongoing development of teaching materials according to the new learning objectives should be undertaken with persistence in order to ensure the progress of preventive medicine education.