• International Journal of Aerospace System Engineering
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• v.2 no.1
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• pp.1-5
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• 2015

The Unmanned Air Vehicle (UAV) systems are indispensable tools of air surveillance and reconnaissance nowadays. Via this systems, hazardous end risky intelligence gathering activities are handled easily. Although they are named as "Unmanned" the UAV systems are commanded by pilots/operators. So, because of weather conditions, enemy attacks etc. as well as pilot error it is possible to face with sudden Round per Minute (RPM) drops and subsequently engine cut/stop during a mission flight at high altitudes. In this case, there are some very urgent decisions to make and rapid "emergency procedure" steps to take in a very short time before Line of Sight (LOS) is lost. The time before crash and the distance to landing air base need to be calculated, the Return Home route need to be checked and the landing/crash side need to be determined. Therefore it is a vital necessity that UAV pilots have some extra qualifications like being determined, well instructed and trained, experienced apart from operating ability. Within this scope, for an education process of a UAV pilot experience sharing and lessons learned are as important as simulators even more. By means of lessons learned it is possible to find out the reasons, mistakes and prevent the likely UAV accidents. In this study it is told about a real UAV crash, experienced of the pilot, the dos and don'ts and the difficulties. Thus it is aimed to help the people who can experience the same or similar situations in future.

• Proceedings of the KOR-BRONCHOESO Conference
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• 1983.05a
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• pp.18.3-19
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• 1983

Choanal atresia, described first by Johann Roedere (1755) is an obstruction between the nasal cavity and nasopharyngeal vault, and the diagnosis and treatment were developed because of severity of the disease. Embryologically, incomplete development of olfactory pit, or failure of nasobuccal membrane to rupture, or persistent remaining of buccopharyngeal membrane, etc, all forms the congenital choanal atresia. And the acquired type was the result from syphilis or diphtheria with a resultant stenosing cicatrix and after the inexpert surgery and the trauma. Multiple abnormalities may be present particularly affecting the head, the heart and the alimentary system in the congenital type. The operative technique employed would depend upon the type of obstruction(whether membranous or bony), the age of the patient, and the presence or absence of any associated pathologic condition. Since Emmert (1853) first tried blind puncture of the atretic plate with the trocar, other surgical techniques have been introduced over the years for the correction of choanal atresia, which were the transnasal, transpalatal, transantral and the transseptal approach. Among them, transpalatal approach was proved to be a popular technique, that it provides a direct route, thus permitting an exact reconstruction and low restenosis rate. Recently, we have experienced two cases of choanal atresia and treated successfully with transpalatal approach, so authors report these cases with a review of the literature.

• Aerospace Engineering and Technology
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• v.7 no.1
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• pp.229-235
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• 2008

The ground flight termination system(GFTS) could be used for the termination of launch vehicle in flight motion when the launch vehicle deviates from the designated route due to the system malfunction or failure as well as the launch vehicle can't be tracked by the ground tracking system. This paper introduces the basic concept and design of the ground flight termination system to be used for KSLV launch mission in NARO space center. In order to design the optimal ground flight termination system for KSLV launch application, the operational concept reflected on the flight trajectory and system characteristics of KSLV launch vehicle should be considered. Moreover the RF link budget analysis, and the analysis for system availability and reliability are done. Based on the analysis above, the each subsystem of ground flight termination to transmit the termination signal in stable is designed for KSLV launch mission.

• Korean Journal of Metals and Materials
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• v.56 no.11
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• pp.835-843
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• 2018

In this work, we report a delta rosette strain sensor based on highly stretchable silver nanowire (AgNW) percolation piezoresistors. The proposed rosette strain sensors were easily prepared by a facile two-step fabrication route. First, three identical AgNW piezoresistive electrodes were patterned in a simple and precise manner on a donor film using a solution-processed drop-coating of the AgNWs in conjunction with a tape-type shadow mask. The patterned AgNW electrodes were then entirely transferred to an elastomeric substrate while embedding them in the polymer matrix. The fabricated stretchable AgNW piezoresistors could be operated at up to 20% strain without electrical or mechanical failure, showing a maximum gauge factor as high as 5.3, low hysteresis, and high linearity ($r^2{\approx}0.996$). Moreover, the sensor responses were also found to be highly stable and reversible even under repeated strain loading/unloading for up to 1000 cycles at a maximum tensile strain of 20%, mainly due to the mechanical stability of the AgNW/elastomer composites. In addition, both the magnitude and direction of the principal strain could be precisely characterized by configuring three identical AgNW piezoresistors in a delta rosette form, representing the potential for employing the devices as a multidimensional strain sensor in various practical applications.

• Convergence Security Journal
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• v.17 no.5
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• pp.87-92
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• 2017

MANET is a network composed itself because mobile nodes are connected wirelessly. It has been applied to various fields for group communication. However, the dynamic topology by the movement of the nodes causes routing failure frequently because it is difficult to maintain the position information of the nodes participating in the group communication. Also, it has a problem that network performance is decreased due to high overhead for managing information of member nodes. In this paper, we propose a multicast technique using location-based 2-tier virtual group that is flexible and reliable in management of member nodes. The network is composed of cellular zones and the virtual group is constructed using the location information of the nodes in the proposed technique. The virtual group management node is selected to minimize the overhead of location information management for member nodes in the virtual group. In order to improve the reliability for management of member nodes and multicast data transmission, it excludes the gateway node with low transfer rate when setting the route after the packet transmission rate of the member nodes is measured. The excellent performance of the proposed technique can be confirmed through comparative experiments with AMroute method and PAST-DM method.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.44 no.1
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• pp.26-36
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• 2021

The topic of this study is the field of humanitarian logistics for disaster response. Many existing studies have revealed that compliance with the golden time in response to a disaster determines the success or failure of relief activities, and logistics costs account for 80% of the disaster response cost. Besides, the agility, responsiveness, and effectiveness of the humanitarian logistics system are emphasized in consideration of the disaster situation's characteristics, such as the urgency of life-saving and rapid environmental changes. In other words, they emphasize the importance of logistics activities in disaster response, which includes the effective and efficient distribution of relief supplies. This study proposes a mathematical model for establishing a transport plan to distribute relief supplies in a disaster situation. To determine vehicles' route and the amount of relief for cities suffering a disaster, it mainly considers the urgency, effectiveness (restoration rate), and uncertainty in the logistics system. The model is initially developed as a mixed-integer nonlinear programming (MINLP) model containing some nonlinear functions and transform into a Mixed-integer linear programming (MILP) model using a logarithmic transformation and piecewise linear approximation method. Furthermore, a minimax problem is suggested to search for breakpoints and slopes to define a piecewise linear function that minimizes the linear approximation error. A numerical experiment is performed to verify the MILP model, and linear approximation error is also analyzed in the experiment.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.8 no.2
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• pp.657-666
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• 2018

This study was carried out to investigate what kind of problems gender equality in Chinese married immigrant women have in marriage. We interviewed five Chinese marriage immigrant women married to Korean men for research. Using the case study method, which is a qualitative research method, five research participants analyzed gender equality awareness and gender equality conflict after migration. As a result, the marital conflicts, which are the difference of recognition of gender equality among married immigrant women, were different according to the family life culture of their home countries, the route of meeting with their husbands, and their understanding of Chinese culture. Nonetheless, most of the research participants showed that they accepted the Korean women's values in the form of conforming to the Korean patriarchal system while taking the inequality by attempting to assimilate positively in Korean society. And some of them resulted in the failure of the family because of the patriarchal values of the Korean husband. Based on the results of this study, we discussed the problems of gender equality in multicultural families in Korea and discussed ways to improve them.

• Journal of Chest Surgery
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• v.34 no.11
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• pp.843-847
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• 2001

Background: Replacement of the esophagus remains a challenge for surgeons involved in esophageal disease. From 1996 to 1999, a total of 27 patients with esophageal cancer underwent free jejunal transfer(12cases) or esophagogastrostomy(15cases). To determine the results such as leakage of anastomosis site, stenosis, reflux esophagitis and operation time, respiratory complications, etc. we reviewed the 4 years experiences. Material and method: Palliative bypass surgery or esophageal prosthesis and cancers of the pharyngoesophageal or esophagogastric junction were excluded in this study. Resection was usually peformed through right thoracotomy and anastomosis was made with EEA staplers in esophagogas-trstomy. In cases of jejunal free transfer, 6cases of proximal esophagojejunostomy were stapled anastomosed and remaining 6 cases and all distal site were hand-sewn anastomosed. All reconstruction was done through posteromediastinal route. Result: There were two mortalities from thoracic esophagogastrostomy and one from jeunal free transfer. Major and minor complications(anastomosis site leakage: 3 cases, graft failure: 2cases etc) occurred in 27 cases. In 15 thoracic esophagogastrostomy cases, 11 patients had mild to moderate reflux esophagitis and 5 patients incurred stricture of the anastomosis. Operation time was about 550$\pm$280 minutes in jejunal free transfer, and about 300$\pm$ 160 minutes in esophagogastromy patients. Conclusion: Post operative reflux esophagitis and dysphagia were more frequent in Ivor-Lewis operation group than jejunal free transfer group; however, respiratory complications and operation time were significantly longer in jejunal (roe transfer group(p<0.05). To minimize the incidence of postoperative reflux esophagitis and dysphagia, patient evaluation focused on jejunal free transfer surgery is better than esophagogastrostomy followed by adequate post operative care.

• Journal of The Korean Society of Clinical Toxicology
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• v.5 no.1
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• pp.27-35
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• 2007

Purpose: Organophosphate (OP) compounds insecticides are the most commonly associated with serious human toxicity all over the world. The aim of this study was to identify sociocultural factors that contribute to high incidence of pure OP poisoning and prevent OP poisoning in order to reduce the factors responsible for deaths in South Korea. Methods: This is the 38 multi-centers survey and prospective study of pure OP poisoning by structural reporting system and hospital records from August 2005 to July 2006. 238 patients with acute pure OP poisoning were enrolled. We collected patient information regarding poisoning, clinical, and demographic features. Results: The mean age was $55.32{\pm}17.3$ years old. The most frequent site of exposure was their own residence(85.7%). Frequent compounds involving pure OP poisoning were dichlorvos(22.7%), methidathion(8.4%), and phosphamidon(6.7%). Intentional poisoning was 77.9%. The most frequently route of exposure was ingestion(94.5%). The mean arrival time to hospital after poisoning was 12.7 hours and mean hospitalization duration was 12.9 days. 2-PAM was administered to 101 patients in mean doses of 6.3 g/day intravenously. Atropine was administered to 81 patients in mean doses of 74.6 mg/day (maximal 910 mg/day). The presence of lower level of GCS score, respiratory complications, hypotension, acute renal failure, and serious dysrhythmia was associated with serious and fatal poisoning. Overall final mortality in pure OP poisoning was 9.7%(23/238). Conclusion: This study highlights the problem of pure OP poisoning in South Korea as a basic national survey. Futhermore this might help the establishment of strict policies availability of OP and the statistics of OP poison exposure in South Korea.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.11
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• pp.604-609
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• 2016

This study evaluated the long-term performance of RSR (Reinforced Subgrade for Railways) technology which increases the railway line capacity without the need for additional land. Its characteristics include the use of a short reinforcement with rigid wall, which make it possible to apply it in confined spaces. The 7m high and 40m long testbed employed to evaluate the long-term performance was designed and constructed near Jupo station on the Chang-hang line. This line, located close to a local bus route, had collapsed at the subgrade following heavy rainfall. The performance of the new type of subgrade was verified with long term measurements over a 2 year period including the surface and ground settlement, horizontal displacement of the wall, tensile strain of the reinforcement, and settlement of the rail top on the side track. Based on the results of the measurements made until now, we concluded that it had sufficient safety and serviceability for use as a railway subgrade. It is expected that RSR technology could be frequently used at sites which lack the necessary construction materials for an embankment and are located close to functional railway lines and boundaries, in order to settle civil complaints.