• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.6
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• pp.1731-1741
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• 2014

Recently, many overpasses, highway, and advanced transit systems have been constructed to distribute the traffic congestion, thus small size of curved bridges with small curvature such as ramp structures have been increasing. Many of early curved bridges had been constructed by using straight beams with curved slabs, but curved steel beams have replaced them due to the cost, aesthetic and the advantage in building the section form and manipulating the curvature of beams, thereby large portion of curved bridges were applied with steel box girders. However, steel box girder bridges needs comparatively high initial costs and continuous maintenance such as repainting, which is the one of the reason for increasing the cost. Moreover, I-type steel plate girder which is being studied by many researchers recently, seem to have problems in stability due to the low torsional stiffness, resulting from the section characteristics with thin plate used for web and open section forms. Therefore, in recent studies, researchers have proposed curved precast PSC girders with low cost and could secured safety which could replace the curved steel girder type bridges. Hence, this study developed a Smart Mold system to manufacture efficient curved precast PSC girders. And by using this mold system a 40 m 2-girder bridge was constructed for a static flexural test, to evaluate the safety and performance under ultimate load. At the manufacturing stage, each single girder showed problems in the stability due to the torsional moment, but after the girders were connected by cross beams and decks, the bridge successfully distributed the stress, thereby the stability was confirmed. The static loading test results show that the initial crack was observed at 1,400 kN when the design load was 450 kN, and the load at the allowable deflection by code was 1,800 kN, which shows that the safety and usability of the curved precast PSC bridge manufactured by Smart Mold system is secured.

• Journal of Environmental Policy
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• v.8 no.4
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• pp.125-147
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• 2009

The Basic Environmental Policy Act (BEPA) (Law No. 4257 effective 1. August 1990) sets forth the basic policies and administrative framework for environmental preservation, leaving more detailed regulations, and emission controls to separate laws targeting air, water, and solid waste, etc. The BEPA Article 31 adopts an unprecedented strict liability standard for damages as an absolute liability. The BEPA Article 31 provides for liability as follows. If a company is alleged to have caused damage through pollution of the environment, it will be liable for damages unless it can show that the pollution did not cause damages, or that it did not actually cause pollution. If the company did cause pollution, and if the pollution is the cause for the damages in question, the company will be liable irrespective of whether it was negligent or otherwise at fault. If there are two or more companies involved in the pollution, but it is unclear which company caused the damages, all of the companies will be jointly and severally liable for the damages. In this paper, the author attempts to uncover the problems of BEPA Article 31 and then seeks desirable amendments by comparing it to the German Environmental Liability Act. First, it will be necessary to provide definitions of 'companies etc.'. Second, it will be necessary to enumerate the kinds of company facilities. Third, it will be necessary to provide exclusionary clauses on material damages. Fourth, it will be necessary to show 'presumption of cause and effect'. Fifth, it will be necessary to provide a clause on 'right to information'. Sixth, it will be necessary to provide a clause for force majeure. Seventh, it will be necessary to take measures to secure abundant liability for damages which can be caused by the owner of the facility, the potential polluter. Finally, it is appropriate that Korea now legislate an Environmental Liability Act akin to the German Environmental Liability Act.

• Journal of Gastric Cancer
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• v.6 no.1
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• pp.1-5
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• 2006

Purpose: A proximal gastrectomy is performed for gastric cancer in the upper part of the stomach to preserve the function of the stomach after surgery. An esophagogastrostomy is one of the common reconstruction methods for a proximal gastrectomy, but this method results in a high incidence of reflux esophagitis. This study was undertaken to compare subjective and functional results between esophagogastrostomy and jejunal interposition reconstructions. Materials and Methods: From June 1998 to December 2002, proximal gastrectomies were performed in 33 patients with tumors in the upper third of the stomach; 8 had reconstruction using jejunal interposition between the esophagus and the remnant stomach (JI group) while 25 had reconstruction using esophagogastrostomy (EG group). The postroperative courses of the patients were reviewed in terms of symptoms, weight changes, and endoscopic findings. Results: The mean age of the patients was 59 years; 26 were men and 7 were women. There were no significant differences in general complications, operating times, or histologic features between the two groups. Fifty-two percent (52%) of the EG group complained of dysphagia, and 16% them experienced heartburn and acid belching. Twelve percent (12%) of the JI group complained of dysphagia, but heartburn and acid belching did not occur. Incidences of reflux esphagitis (36%) and balloon dilatation for anastomotic stricture (16%) were more common in the EG group than in the JI group (0% and 12%). Conclusion: To prevent or minimize complications, such as reflux esophagitis and postoperative symptoms, a proximal gastrectomy with a jejunal interposition is an alternative method as an organ-preserving surgical strategy to improve quality of life for patients. (J Korean Gastric Cancer Assoc 2006;6:1-5)

• Journal of The Korean Association For Science Education
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• v.36 no.5
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• pp.739-756
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• 2016

The purpose of the study is to reflect on 'myself' as a teacher educator of college of education in depth and to improve my instruction through self-study with three critical collaborators. 17 pre-service science teachers and I have participated in this study of a teacher educator's course since March 2016 after the preliminary practice in 2015. The video recorded the course for 11 weeks with about 40 hours of lessons. The data source also included teacher educator's reflective journals, lecture evaluations, online boards and so on. Questionnaires were distributed and answered both at the beginning and at the end of the course and pre-service teachers wrote their reflective journals. Four of them were in the focus group interviews. During the course, the weekly group meeting of critical collaborators analyzed the emerging issues based on the lesson clips and teacher educator's reflective journals with discussion for the course innovation. Four phases were revealed in the process and for the purpose of the course such as exploration, conflicts, challenges, and changes. The results showed that first, we identified tensions among the teacher educator's multiple identities as a lecturer, a faculty member, and a researcher. Second, there were differences between goals of teacher educator and pre-service teachers in the course, and this obstructed the success of the course sometimes. Third, these practices led to explore balanced alternative views and interpretations of the problem by critical views and to expand and improve our teaching practice and thinking. In addition, the self-study with critical collaborators helped to bring conflicts and issues below my practice to light for collaborative reflection and it gave a chance to understand ourselves as teacher educators in different ways.

• The Korean Journal of Air & Space Law and Policy
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• v.26 no.2
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• pp.203-237
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• 2011

Since USSR successfully launched its satellite "Sputnik"in 1957, many countries including US and USSR began military use of space, and engaged in arms race in space, which is against spirit and ideals of peaceful use of space as common heritage of mankind stipulated in many treaties such as Outer Space Treaty. With worsening Cold War between East and Western Bloc, this military use of space and arms race in space has been intensifying. Regarding the ideals of peaceful use of space, it is interpreted that military use of space is possible unless it does not have the purpose of aggression. The military use of space may have diverse forms such as attacking satellites in space, or attacking from satellites, making use of present and future technologies available which should include the use of nuclear and kinetic/hyper-speed weapons, laser, particle beams, near explosion, disturbance weapons in different directions (i.e., surface to space, space to space, and space to surface). Arms control is being implemented by the efforts of many countries in different formalities including legislature of international treaties under the auspices of UNCOPUOS and prohibition of weapons of mass destruction. Taking outstanding examples aiming at arms control by international community, there are confidence building measures (CBM), strengthening implementation of existing treaties, partial ban of nuclear tests, countryand regional approach, comprehensive approach and measures having legally binding force. While U.S. has surpassed other countries concerned in the area of military useof space, it withdrew from OST in early 2000s, thereby raising concern of international community. It requires concerted efforts of cooperationand implementation by international society to make sure peace of mankind and environmental conservation through arms control in space. Observing de facto possession of nuclear weapons by North Korea following series of nuclear tests and launching satellites, and efforts of launching rockets by South Korea, it is strongly needed for both countries to take part in arms control efforts by international community.

• Tuberculosis and Respiratory Diseases
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• v.45 no.6
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• pp.1277-1283
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• 1998

Background : Surgical tracheostomy(ST) is usually performed by surgeons in operating room. For a patient with mechanical ventilation, however, transportation to operating room for ST could be dangerous for patients. In addition, ST is often delayed due to unavailability of operating room or surgeon. Percutaneous dilatational tracheostomy(PDT), although novel in Korea, is gaining popularity as a bedside procedure in the hospitals of western countries. We evaluated the technical ease and safety of PDT in comparison with ST. Method : Thirty-eight patients in medical intensive care unit (ICU) who were either under mechanical ventilation for more than 7 days or required airway protection, were randomly assigned to ST(18 patients) or PDT(20 patients). Between two groups, there was no significant clinical difference except that female to male ratio was higher in the ST group. ST was performed by second year residents of the department of otolaryngology while PDT was performed by third grade medical resident and pulmonologist under bronchoscopic guide using Ciaglia Percutaneous Tracheostomy Set(Cook Critical Care, Bloomington, USA) in medical ICU. The following factors were compared between two groups : number of delayed cases after the decision for tracheostomy, procedural time, complications related to tracheostomy. Results : Delayed cases were 11 in ST group and 3 in PDT group (P<0.05). Procedural time was significantly shorter in PDT group ($15.6{\pm}7.1min$) than in ST group ($29.1{\pm}11.6min$, P<0.0001). Complications related to tracheostomy occurred in 5 cases in ST group : accidental decannulation (1), subcutaneous emphysema (2) and minor bleeding (2), and in 4 cases in PDT group : minor bleeding (2), subcutaneous emphysema (1) and premature extubation (1) (P>0.05). Conclusion : Since percutaneous dilatational tracheostomy was easy to practice and its complications were not different from surgical tracheostomy, PDT can be a useful bedside procedure for mechanically ventilated patients.

• Journal of Korean Home Economics Education Association
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• v.31 no.4
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• pp.41-62
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• 2019

The purpose of this study was to examine how the contents and pedagogical styles of Food and Nutrition in the middle school home economics textbooks could promote constructivist learning. For this, Food and Nutrition contents of 12 current textbooks were analyzed, based upon the learning factors derived from both a practical problem-focused curriculum from the constructivist perspective, and the current home economics curriculum from the objectivist perspective. Pedagogical styles of the texts and exercises were classified into four types- neutral informative, injunctive, persuasive, and participative, out of which 'persuasive' and 'participative', in particular reflect the constructivist perspective. The major findings were as follows: First, the analysis results of Food and Nutrition contents showed that of 14 learning factors, 13 of the textbooks corresponded well to the current curriculum(92.9%). On the other hand, Out of the 26 learning factors, 18 of the textbooks corresponded to the practical problem-focused curriculum(72.4%). Classified into each stage of the practical problem solving processes, only learning factors related with 'the concepts of the valued ends' were fully covered. However, the other learning factors related with the concepts of 'the practical problem', 'the context', 'the action' and 'the consequence', that is the factors particularly related with 'the concepts of the context', were not properly addressed. Besides, learning factors were not addressed from diverse viewpoints, especially from the social perspective. Second, the analysis of pedagogical style related to Food and Nutrition illustrated that the neutral informative(59.9%) in texts, and the participative in exercises(60.4%), were most common. However, persuasive and participative were insufficient in texts(22.1%). Furthermore even though the exercises, are more likely to be described from the constructivist perspective, nearly none of the exercises was considered from the social perspective. In conclusion, this study showed that Food and Nutrition in Korean home economics textbooks need to reflect constructivist learning better.

• Journal of the Korean Chemical Society
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• v.62 no.4
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• pp.299-313
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• 2018

Inquiry-centered education is important in science education, but in the actual education field, scientific research is being done in a uniform manner due to realistic difficulties. In this study, we use RS (Reverse Science) as a secondary chemistry class to provide opportunities for students to engage in inquiry learning and scientific thinking through process-oriented activities. In this study, we developed and applied it to explore the effects on the scientific inquiry abilities of middle school students and checked the students' perception of it. For the application of the program, 128 students were selected from 6 classes of the 2nd grade in D district middle school, 64 from the experimental group and 64 from the comparative group. The experimental group taught RSP-based the chemistry inquiry programs and the comparative group taught instructor-led classes and verification experiments on the same topic over the seventh hour with three themes. In addition, we analyzed the results of the pre- and post-test by using the science inquiry ability test, and discussed the effects of the program based on the students' perceptions through class observation, student activity area, questionnaire and interview. As a result, the class using the program showed statistically significant changes in the science inquiry ability of secondary school students. Specifically, the experimental group was found to be significant in its prediction among the subcomponents of basic exploration ability compared to the comparative group. The differences have also been shown to be significant in terms of data translation, hypothesis setup and variable control, which are subcomponents of integrated exploration capabilities (p <. 05). In addition, students became interested in the process of creating the theory of science, and were highly interested in collaborating with their friends. It also provided students with opportunities to experience scientific thinking through process-oriented inquiry. Finally, based on the positive impact of the RSP-based chemistry inquiry program on students, we were able to identify the potential use of the program.

• Management & Information Systems Review
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• v.39 no.1
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• pp.93-114
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• 2020

Platform is considered as an alternative strategy to the traditional linear pipeline based business. Moreover, in the 4th industrial revolution period, efficiency driven pipeline business model needs to be changed to platform business. We have such success stories about platform as Apple, Google, Amazon, Uber, and so on. However, for those smaller corporations, it is not easy to find out the transformation strategy. The essence of platform business is to leverage network effect in management. Thus platform based management can be rephrased as network management across the business functions. Research on platform business is popular and related to diverse facets. But few scholars cover what the research trend of the domain is. The main purpose of this paper is to identify the research trend on platform business in Korea. To do that we first propose the analytical model for platform architecture whose components are consumers, suppliers, artifacts, and IT platform system. We conjecture that mapping of the research work on platform to the components of the model will make us understand the hidden domain of platform research. We propose three hypotheses regarding the characteristics of research and one proposition for the transitional path from pipeline to platform business model. The mapping is based on the research articles filtered from the Korea Citation Index, using keyword search. Research papers are searched through the keywords provided by authors using the word of "platform". The filtered articles are summarized in terms of the attributes such as major component of platform considered, platform type, main purpose of the research, and research method. Using the filtered data, we test the hypotheses in exploratory ways. The contribution of our research is as follows: First, based on the findings, scholars can find the areas of research on the domain: areas where research has been matured and territory where future research is actively sought. Second, the proposition provided can give business practitioners the guideline for changing their strategy from pipeline to platform oriented. This research needs to be considered as exploratory not inferential since subjective judgments are involved in data collection, classification, and interpretation of research articles.

• The korean journal of orthodontics
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• v.38 no.4
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• pp.275-282
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• 2008

Objective: The purpose of this study was to investigate the effect of using laser for ceramic bracket bonding of porcelain surfaces and to compare it with conventional treatment of porcelain surfaces. Methods: Ninety feldspathic porcelain specimens were divided into 9 groups of 10, with each group having different surface treatments performed. Surface treatment groups were orthophosphoric acid, orthophosphoric acid with silane, hydrofluoric acid, hydrofluoric acid with silane, sandblasted, sandblasted with silane, laser etched, laser etched with silane, and glazed surface served as a control group. In the laser etched groups, the specimens were irradiated with 2-watt superpulse carbon dioxide ($CO_2$) laser for 20 seconds. Ceramic brackets were bonded with light-cure composite resin and all specimens were stored in water at $37^{\circ}C$ for 24 hours. Shear bond strength was determined in megapascals (MPa) by shear test at 1 mm/minute crosshead speed and the failure pattern was assessed. For statistical analysis, one-way ANOVA and tukey test were used. Results: Statistical analysis showed significant differences between the groups. The HFA + S group showed the highest mean shear bond strength ($13.92{\pm}1.94\;MPa$). This was followed by SB + S ($10.16\;{\pm}\;1.27\;MPa$), HFA ($10.09\;{\pm}\;1.07\;MPa$), L + S ($8.25\;{\pm}\;1.24\;MPa$), L ($7.86\;{\pm}\;0.96\;MPa$), OFA + S ($7.22\;{\pm}\;1.09\;MPa$), SB ($3.41\;{\pm}\;0.37\;MPa$), OFA ($2.81\;{\pm}\;0.37\;MPa$), G ($2.46\;{\pm}\;1.36\;MPa$), Bond failure patterns of HFA and silane groups, except L + S, were cohesive modes in porcelain while adhesive failure was observed in the control group and the rest of the groups. Conclusions : A 2-watt superpulse $CO_2$ laser etching of porcelain surfaces can provide a satisfactory result for porcelain surface treatment for ceramic bracket bonding. Laser irradiation may be an alternative conditioning method for the treatment of porcelain surfaces.