• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.4 no.1
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• pp.15-21
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• 2005

One of the core technology in WDM-PON system is a generation and modulation technique of the optical source in Optical Network Unit (ONU). In this paper, we propose a reflective semiconductor optical amplifier (RSOA) as a modulator in WDM-PON system. Its performance is analyzed by simulation and actual experimentation. Using RSOA in WDM-PON system as a modulator, it obtains higher gain compared to the conventional SOA due to the double pass gain effect. Furthermore RSOA can provide high gain with comparatively low input power. This is very helpful when we set up the actually system because using lower input power, it can reduce the load of the driving circuit which makes very economical module structure. Therefore, when RSOA is used as a modulator, not only it gives noise suppression effect, but also provides certain amount of gain as well. In addition, comparing with conventional SOA which gives fairly large insertion loss, RSOA can provides more important merits.

• Journal of Forest and Environmental Science
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• v.38 no.1
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• pp.12-20
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• 2022

Pongamia (Pongamia pinnata L.) as a source of non-edible oil, is potential tree species for biodiesel production. For several reasons, both technical and economical, the potential of P. pinnata is far from being realized. The exploitation of genetic diversity for crop improvement has been the major driving force for the exploration and ex situ/in situ conservation of plant genetic resources. However, P. pinnata improvement for high oil and seed production is not achieved because of unsystematic way of tree improvement. Performance of P. pinnata planted by Karnataka Forest Department was assessed based on yield potential by collecting 157 clones out of 264 clones established by Karnataka Forest Department research wing under different research circles/ranges. It was evident that the all the seed and pod traits were significantly different. Further, selection of superior germplasm based on oil and pod/seed parameters was achieved by application of Mahalanobis statistics and Tocher's technique. On the basis of D² values for all possible 253 pairs of populations the 157 genotypes were grouped into 28 clusters. The clustering pattern showed that geographical diversity is not necessarily related to genetic diversity. Cluster means indicated a wide range of variation for all the pod and seed traits. The best cluster having total oil content of more than 34.9% with 100 seed weight of above 125 g viz. Cluster I, II, III, IX, XV, XIX, XXI, XXIII, XXVI and XXVII were selected for clonal propagation.

• International Journal of Internet, Broadcasting and Communication
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• v.16 no.3
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• pp.158-163
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• 2024

Virtual world technology is driving major advances in education, entertainment, and professional training. Metaverse and extended reality (XR) technologies maximize immersion to enhance learning, provide global learning environments, and expose students to situations that are difficult to experience in real life. Career exploration is an important developmental task in adolescence, and virtual training maximizes learning by providing life-like experiences with imagery training. Virtual training overcomes spatial, financial, performance, and situational constraints and is effective in a variety of fields, including military and disaster training. It provides customized learning for various users such as youth, job seekers, and people with disabilities, deepening their understanding of professional activities and improving their problem-solving skills. It also improves the quality of learning through repetitive learning and contributes to the improvement of teamwork and communication skills, and helps to solve financial problems by using unlimited internal resources and space in virtual space, and enables people with disabilities to perform in various professions. This paper investigated the value of virtual training as a comprehensive educational tool through an economical and efficient learning experience.

• Korean Institute of Interior Design Journal
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• v.23 no.2
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• pp.136-146
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• 2014

As of 2010, apartment occupies more than half of all houses in Korea. It took just half a century since 1960 when apartment was introduced to ordinary people for the first time. The apartment has spread over the nation very swiftly since then. This phenomena needs more inclusive explanations than the investigations into the government's policies or economical situations. Without satisfaction and consensus of people, the universal spread of apartment might be fairly unrealizable. In this vein, the research and analysis has been performed in order to grasp the picture of everyday life's discourse based on the related articles from five major newspapers and five women's magazines during 1960~1989. From the articles' discourses we tried to understand how modern apartment has been accepted and evaluated through people's living life in it. First, the discourse of living life was generated mostly by housewives through the comparison between apartment and traditional house. Second, the most influential aspect of apartment's popularization was the convenience of efficient housekeeping system by modern equipment and home appliance installed in apartment. This efficiency could allow housewives to perform various urban activities such as work, shopping, and simple going out. Third, the satisfaction from efficiency and privacy brought about a sense of alienation at the same time. As a result, the rapid proliferation of apartment in Korea could be attained not only by the institutional driving forces but through the fulfillments of Korean people's housing needs from modern everyday life.

• Proceedings of the KSR Conference
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• 2003.10c
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• pp.322-326
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• 2003

Dae-gu subway accident raise whole points in connection with safety facilities and operating of national urban transit system like rolling stocks, facilities, management of human. Rolling stock is made every effort for improvement of performance, guarantee of comfortableness, insurance of economical efficiency. But Security like safety of fire is not thoroughgoing enough. Especially, interior material has used although it is not prove its degree of safety. it is a main cause of Dae-gu subway accident. Safety regulation of urban transit vehicle that legislate for security in March 2000 does not applied manufacturing vehicles before in 2000. It has be prescribed in the regulations that incombustibles must be used. But detailed test standard related with incombustibles is not prescribe. Thus that regulation be required reinforcement of detailed test standard. Main cause of Dae-Gu subway accident is a fire in vehicle. However, many defects are found in infrastructure and operating vehicle of urban transit, such as inexperienced disposal of driver and CCC in early stage of the fire accident, unskilled opening and closing doors, insufficient escape facilities and safety facilities of a station house and tunnel, and incomplete communication system between vehicle and CTC, extraordinary step. Thus the aims of this study are prevention of urban transit accident, improvement plan of safety driving, and proposal of quick action plan through analysis of total faculty of vehicle.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.454-456
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• 2010

The demands for (a) individual vehicle has been gradually increasing recently due to increase of personal income and spare time. In 2009, the quantities of registered vehicles exceeds over 17,325,210 millions pieces, and the risks of traffic accidents and traffic jam are increasing days by days. It has some limitations to solve the problem of traffic jam by transportation facilities and causes lots of time and costs. For a possible solution, ITS(Intelligent Transport System) has been introduced, but it is an insufficient way for abrupt incidents or risks on roads. The riskiest matter on driving a vehicle is unforeseen situation. In this paper, the most efficient and economical system that communicates with a driver about unexpected accident by sensor network and GPS information, is introduced rather than a traditional method associated with lots of time and costs.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.1
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• pp.211-217
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• 2019

Oil extraction from oil sands, a non-traditional crude oil resource, is attracting attention as the oil price fluctuates due to recent economical and political issues. Many oil sands sites are mainly located in the polar regions. For plant construction to extract crude oil from oil sands in harsh environment of the polar regions, fast and simple installation of plant foundation is necessary. However, typically-used conventional foundations such as drilled shafts and driven piles are not suitable to construct under cold temperature and organic surface layers. In this study, helical piles enabling rapid and simple constructions using small rotary equipment without driving or excavation was considered. The helical pile consists of steel shaft and several helices attached to the steel shaft; therefore, the behavior of the helical pile depends on the number and shape of the helices. The effect of the helices' configuration (number and diameter of helices) on helical pile behavior was analyzed based on the numerical analysis results.

• Journal of Korean Association for Spatial Structures
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• v.20 no.4
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• pp.53-62
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• 2020

This study examines the optimum shape of a trolley, the driving device of the retractable membrane roof. The closed-type trolley was determined as the model of the study, and a trolley composed of cylindrical-shaped inner and outer holders was selected as the basic model. Based on this model, a cylindrical-based optimal trolley model was proposed. In the basic trolley model, steel was used for the outer holder, and steel, titanium, and aluminum were used for the inner holder. In each case, the most economical shape for the external load of the basic model was newly proposed through the topology optimization process, and the finite element analysis results of the proposed model were compared to define the durability and economics. Here, topology optimization analysis and finite element analysis used the commercial software ANSYS. As a result of optimization, the volume of the outer holder of the trolley was reduced by 58.2% and the volume of the inner holder was reduced by 25.0% compared to the basic model. In the case of stress, a stress increase of 43.2 to 79.2% occurred depending on the material of the inner holder, but it was found to be significantly lower than the yield strength, thereby ensuring safety.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.3
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• pp.133-138
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• 2022

Digital radiation inspection equipment is a medical device that deals with human life and requires stability and high reliability. However, this system is currently the most advanced technology and the domestic market is almost occupied by European products including Japan. Therefore, research and development are needed not only to replace domestic medical devices, which are largely dependent on expensive imported products, but also to develop more economical and user-oriented products that are easy to operate and produce devices that lead to accurate diagnosis. In particular, among the digital X-ray systems, the motor driving technology and the mechatronics technology related to the development of mechanical devices have matured to some extent in Korea. In this paper, selection of AC servomotor for digital radiation inspection suitable for imaging purpose, and application of conversion device and control method to check performance and improve problems.

• Journal of the Korean Association of Geographic Information Studies
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• v.19 no.3
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• pp.114-126
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• 2016

Domestic risk factors that are thought to be correlated with highly pathogenic avian influenza (HPAI) outbreak are migratory birds and moving objects such as poultry farm vehicles. In particular, the commercial vehicles that routinely circulate the local and/or remote poultry farms produce are thought to be major HPAI risk factors in South Korea. In this study, the driving histories of the vehicles belonging to poultry farms and/or commercial companies registered in the Korea Animal Integrated System (KAHIS) were analyzed using statistical and social networking tools in a Geographic Information System (GIS) in order to understand the pattern of the HPAI (H5N8) outbreak that occurred in 2014 in South Korea. Based on the 2014 HPAI outbreak patterns, HPAI-infected poultry farms were categorized according to geological features. The HPAI-infected poultry farms were categorized as 'regional-accumulation', 'regional-distribution', 'metropolitan-accumulation', 'metropolitan-distribution' and 'national-distribution' in endemic or non-endemic regions. We were able to categorize most HPAI-infected poultry farms into the five proposed categories, but further studies are required to categorize all such farms. Based on this categorization system, we propose efficient but economical prevention boundaries in South Korea. We strongly believe that our research could hugely impact government decisions to estimate the prevention area.