• Advances in pediatric surgery
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• 제17권1호
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• pp.45-50
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• 2011

Meckel's diverticulum (MD) has various clinical presentations and due to the limitation of imaging studies, pre-operative diagnosis is a challenge in pediatric patients. Recently, laparoscopic exploration has been suggested as a favorable method for the diagnosis and treatment of complicated MD. We investigated the results of laparoscopic-assisted surgery compared with open technique. We retrospectively studied patients who underwent resection of complicated MD at our institute from 1997 to 2010 and compared 11 treated by laparoscopic-assisted diverticulectomy (LD) with 11 treated by open diverticulectomy (OD) for complicated MD. Operation time was not significantly different in the two groups. Hospital stay and time to diet were not significantly different. Two patients were re-admitted due to mechanical ileus in the LD group. None of patients in either group needed re-operation. Considering the possibility of false-positive results with imaging studies and the cosmetic benefit, laparoscopic-assisted surgery is a safe and effective treatment modality to diagnose and treat complicated Meckel's diverticulum.

• International Journal of Aeronautical and Space Sciences
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• 제14권3호
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• pp.247-255
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• 2013

The flight control of re-entry vehicles poses a challenge to conventional gain-scheduled flight controllers due to the widely spread aerodynamic coefficients. In addition, a wide range of uncertainties in disturbances must be accommodated by the control system. This paper presents the design of a roll channel controller for a non-axisymmetric reentry vehicle model using the trajectory linearization control (TLC) method. The dynamic equations of a moving mass system and roll control model are established using the Lagrange method. Nonlinear tracking and decoupling control by trajectory linearization can be viewed as the ideal gain-scheduling controller designed at every point along the flight trajectory. It provides robust stability and performance at all stages of the flight without adjusting controller gains. It is this "plug-and-play" feature that is highly preferred for developing, testing and routine operating of the re-entry vehicles. Although the controller is designed only for nominal aerodynamic coefficients, excellent performance is verified by simulation for wind disturbances and variations from -30% to +30% of the aerodynamic coefficients.

• 수산경영론집
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• 제49권4호
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• pp.69-81
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• 2018

The fishing vessel buyback program, that is, the project of fishing vessel reduction is a complex challenge that needs to take into consideration for both fishing resource protection and industrial restructuring. By the way, the fishing vessel buyback program in Korea is still poorly fruitful and there are few applications for the project in the country. For example, the buyback program of this nation has some problems like uncertainly set goals, conflicts among targets, no flexibility in the program implementation, low participation in the project and lack in follow-up actions. To solve these problems, this study offers the following alternatives. First, it is setting up detailed targets for fishing vessel buyback. Those targets should be what can be actually driven under policy support, such as reduction in illegal fishing, decrease in an exact number of fishing vessels and decline in fishing capacity rather than what seem to be comprehensive such as protection of coastal or offshore fishery and industrial restructuring. Second, it is taking measures for the livelihood of those who would face disadvantages due to fishing vessel reduction. Those measures providing or supporting the re-education and re-employment of fishery workers and building up systems that help the workers transfer fishing to another job. Third, it is adopting the governance system that overcomes lacks in communications between the fishing vessel buyback program and improves the performance effectiveness of that program. Here, governance means that businesses and authorities concerned in the program interact and cooperate with one another in making and implementing policies related to the project of fishing vessel reduction and assessing the results of that project. Fourth, it is taking actions for fishery reorganization after the fishing vessel buyback program. Factors that can be considered as those actions include supporting fishery workers' cost of fishing vessel reduction, decreasing and modernizing fishing fleets and improving the quality of fishing equipment. In conclusion, the fishing vessel buyback program should be prepared with comprehensive actions or measures that can cope well with a variety of problems that may be arisen from it while keeping itself on the track of its original goals.

• International Journal of Stem Cells
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• 제15권2호
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• pp.164-172
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• 2022

Background and Objectives: Despite advances in wound treatments, chronic diabetic wounds remain a significant medical challenge. Exosomes from mesenchymal stem cells (MSCs) and small molecule activators of nuclear factor erythroid 2-related factor 2 (Nrf2) have emerged as potential therapies for nonhealing diabetic wounds. This study aimed to evaluate the effects of exosomes from bone marrow-derived MSCs (BMSCs) alone, or in combination with a small molecule activator of Nrf2 on diabetic wound healing. Methods and Results: BMSCs and endothelial progenitor cells (EPCs) were isolated from the femur and tibia bone marrow of Sprague-Dawley (SD) rats and culture-expanded. Exosomes were harvested from the BMSC culture supernatants through ultracentrifugation. The effects of the exosomes and Nrf2 knockdown, alone or in combination, on EPC tube formation were evaluated. Streptozotocin-induced diabetic rats bearing a fresh full-thickness round wound were treated with the exosomes alone, or in combination with a lentiviral shRNA targeting Nrf2 (Lenti-sh-Nrf2) or tert-butylhydroquinone (tBHQ), a small molecule activator of Nrf2. Two weeks later, wound closure, re-epithelization, collagen deposition, neovascularization, and local inflammation were evaluated. BMSC exosomes promoted while Nrf2 knockdown inhibited EPC tube formation. BMSC exosomes accelerated wound closure, re-epithelization, collagen deposition, and neovascularization, and reduced wound inflammation in diabetic rats. These regenerative and anti-inflammatory effects of the exosomes were inhibited by Lenti-sh-Nrf2 but enhanced by tBHQ administration. Conclusions: BMSC exosomes in combination with a small molecule Nrf2 activator hold promise as a new therapeutic option for chronic diabetic wounds.

• 컴퓨터교육학회논문지
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• 제15권5호
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• pp.11-22
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• 2012

본 연구는 로봇을 활용한 STEAM 수업에서 '도전과 기술의 조화'와 같은 플로우 요인이 학습자의 학습지속 태도에 영향을 주는 과정을 TAM 모형을 적용해서 분석하고자 했다. 연구는 초등학교 6학년 2학기 과학교과의 '에너지와 도구' 단원을 재구성했으며 모두 189명에게 적용하여 유효한 174명에 대한 설문만을 분석에 활용했다. 분석결과 학생들의 학습 몰입요인(도전과 기술의 조화 요인)은 학습의 유용성 보다는 학습의 용이성 요인에 영향을 더 주었고 이는 다시 학습의 가치성 요인을 통해서 최종적으로 학습의 지속의 도에 영향을 준 것으로 파악되었다. 연구의 결과 파악된 시사점으로는 로봇을 STEAM 수업에서의 학습지속의도는 학습자의 학습에 대한 적절한 적극적인 태도와 로봇에 대한 기본적인 소양이 기본적으로 필요하며, 이를 바탕으로 STEAM 수업에 로봇이 도움을 주며 학습의 결과에 영향을 줄 수 있다는 가치적 측면이 고려되어야 함을 알 수 있었다. 반면, 학습의 용이성 및 도전과 기술의 조화 요인은 각각 학습지속의도 및 학습의 가치성 요인에 직접적인 (+)의 영향을 주지 못했다. 다만 두 요인은 유효한 범위 안에서 각각의 종속변수에게 간접적인 영향을 주고 있는 것으로 나타나 이것에 대한 분석결과도 포함시켰다.

• 한국전문물리치료학회지
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• 제23권2호
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• pp.93-99
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• 2016

Background: Parametric statistical procedures are typically conducted under the condition in which a sample distribution is statistically identical with its population. In reality, investigators use inferential statistics to estimate parameters based on the sample drawn because population distributions are unknown. The uncertainty of limited data from the sample such as lack of sample size may be a challenge in most rehabilitation studies. Objects: The purpose of this study is to review the bootstrapping method to overcome shortcomings of limited sample size in rehabilitation studies. Methods: Articles were reviewed. Results: Bootstrapping method is a statistical procedure that permits the iterative re-sampling with replacement from a sample when the population distribution is unknown. This statistical procedure is to enhance the representativeness of the population being studied and to determine estimates of the parameters when sample size are too limited to generalize the study outcome to target population. The bootstrapping method would overcome limitations such as type II error resulting from small sample sizes. An application on a typical data of a study represented how to deal with challenges of estimating a parameter from small sample size and enhance the uncertainty with optimal confidence intervals and levels. Conclusion: Bootstrapping method may be an effective statistical procedure reducing the standard error of population parameters under the condition requiring both acceptable confidence intervals and confidence level (i.e., p=.05).

• 대한족부족관절학회지
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• 제24권2호
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• pp.69-74
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• 2020

Osteochondral lesions of the talus (OLT) can heal and remain asymptomatic, or they can progress to deep ankle pain on weight bearing and the formation of subchondral cysts. Treatment varies from nonoperative treatment to open and arthroscopic procedures. Operative procedures include marrow stimulation techniques (abrasion chondroplasty, multiple drilling, microfracture), osteochondral autografts or allografts, and autologous chondrocyte implantation. Among these treatments, arthroscopic marrow stimulation techniques have been the preferred initial surgical treatment for most OLT. Despite these treatments, many patients complain of persistent pain even after surgery, and many surgeons face the challenge of determining a second line of treatments. This requires a thorough re-evaluation of the patient's symptoms as well as radiological measures. If the primary surgical treatment has failed, multiple operative treatments are available, and relatively more invasive methods can be administered. On the other hand, it is inappropriate to draw a firm conclusion in which methods are superior.

• 과학기술학연구
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• 제16권1호
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• pp.63-89
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• 2016

이 글에서는 새롭게 부상하고 있는 전환연구의 관점에서 우리나라 혁신정책담론 중의 하나인 탈추격론을 재해석하는 작업을 수행했다. 탈추격론의 지향점, 주요 연구 대상, 시스템 혁신에 대한 논의를 전환연구의 관점에서 확장하여 지속가능성, 산업과 사회의 공진화, 전환관리 등의 개념을 탈추격론에 도입했다. 이를 통해 탈추격 혁신과 정책은, 기존 시스템의 개선과 최적화가 아니라 탈추격 지속가능 시스템으로의 전환을 지향하고, 사회 환경문제의 해결을 수반하는 탈추격 혁신을 진행해야 하며, 탈추격과 지속가능성의 맹아를 담고 있는 니치를 전환의 관점에서 전략적으로 관리해야 한다는 점을 지적하였다.

• 한국문헌정보학회지
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• 제44권4호
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• pp.131-153
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• 2010

The fusion of learning, information, and technology presents dynamic challenges for all librarians, educators and students in 21st century libraries and schools. At the heart of this fusion is the growth of a pervasive, integrated information environment characterized by vast quantities of digital content, open choice, collaborative and participatory digital spaces, and the transition of the web environments from consumption of information to creation of information. This environment heralds important opportunities for librarians and teachers to rethink, re-imagine and recreate a dynamic approaches to information literacy instruction. Drawing on an extensive body of research undertaken through the Center for International Scholarship in School Libraries (CISSL), and published research on both information literacy and constructivist learning, this paper provides a critical examination of the current status of information literacy: its multiple conceptualizations, competing models, viewpoints, and its operationalizations in educational and library environments. The paper will challenge information literacy practices which center on simplistic, reductionist approaches to information literacy development, and the separation of information process and knowledge content. In particular it will address apparent contradictions in espoused conceptions of information literacy which revolve around "knowledge": knowledge construction, critical thinking, problem solving and the development of knowledgeable people; and information literacy practices which revolve around "information": a predominant focus on skills of access and evaluation of resources and with less attention given to engaging with found information to develop deep knowledge and understanding. The paper will present a series of challenges for moving forward with information literacy agendas in libraries and schools.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권3호
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• pp.1377-1399
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• 2020

In search and rescue mission, micro aerial vehicles (MAVs) are typically used to capture image and video from an aerial perspective and transfer the data to the ground station. Because of the power limitation, a cluster of MAVs are required for a large search area, hence an ad-hoc wireless network must be maintained to transfer data more conveniently and fast. However, the unstable link and the intermittent connectivity between the MAVs caused by MAVs' movement may challenge the packet forwarding. This paper proposes a delay tolerant packet forwarding algorithm based on location estimation for MAV networks, called DTN_est algorithm. In the algorithm, ferrying MAVs are used to transmit data between MAVs and the ground station, and the locations of both searching MAVs and ferrying MAVs are estimated to compute the distances between the MAVs and destination. The MAV that is closest to the destination is selected greedy to forward packet. If a MAV cannot find the next hop MAV using the greedy strategy, the packets will be stored and re-forwarded once again in the next time slot. The experiment results show that the proposed DTN_est algorithm outperforms the typical DTN_geo algorithm in terms of packet delivery ratio and average routing hops.