• Journal of the Korean Society for Precision Engineering
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• v.20 no.10
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• pp.191-198
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• 2003

In this study, aberration free aspherical lens design method named ray reverse tracing method is introduced. Differently from the traditional design method, the ray reverse tracing method traces the shape and location of a real object by use of its virtual image. From the result, especially spherical aberration free aspherical lens could be designed by use of the ray reverse tracing method. Furthermore, it could reduce the degree of dependence of optical characteristics on designer's ability, because deformation terms and optimization can be eliminated, which has been performed in conventional lens design process.

• Proceedings of the Korea Information Processing Society Conference
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• 2024.05a
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• pp.386-388
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• 2024

UAF(Use-After-Free)는 heap 영역에서 메모리 오염을 발생시킬 수 있는 취약점이다. UAF를 방지하기 위해 다양한 방법으로 관련 연구가 활발히 이루어지고 있지만, 아직까지 여러 오버헤드 측면에서 모두 좋은 성능을 발휘한 결과는 나오지 않고 있다. 할당자 수준에서의 수정을 통하여, UAF 취약점 방어를 보장하는 동시에 높은 성능과 낮은 오버헤드를 발생시킬 수 있는 방법을 제시한다. 본 논문에서는 UAF 취약점 및 관련 연구를 소개하고, 이를 기반으로 UAF 취약점에 대처할 수 있는 방법을 제시한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2024.05a
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• pp.222-225
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• 2024

전통적 프로그래밍 언어인 C/C++는 시스템 프로그래밍 언어로 널리 사용되고 있으며, 이는 저수준 메모리 제어와 하드웨어 상호작용 등의 특성 때문이다. 하지만 C/C++가 가지고 있는 특성중 하나인 저수준 메모리 제어는 프로그래머가 직접 메모리를 관리해야한다. 다양한 메모리 버그들중에서 특히 Use-after-free버그는 오래전부터 현재까지 해결되지 않은 버그로써 존재하고 있으며, 이는 프로그래머가 수동으로 메모리를 관리함으로써 발생한다. 이 버그를 예방 및 감지하기 위한 연구가 현재까지도 활발하게 진행되고 있다. 이 버그를 차단 및 감지하는 연구들의 동향을 분석하여 앞으로의 관련 연구의 지속적인 필요성을 제시한다.

• Journal of Digital Convergence
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• v.10 no.1
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• pp.357-364
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• 2012

For the resistance of the closed intellectual property license from the Free Software Movement. It's free and also can adapt have been widely used. Software for the resistance of the closed intellectual property rights have been promoted by the free software movement. Implementation of the proposed changes in the license that anyone can freely use the software and adapt open source software is widely used. The product of open source software can reduce development time and cost. Many people who use it will improve, verification and developed. However, indiscriminate use of these advantages, as well as the risk of dispute is high. This study is analyzed open source software dispute cases for piracy protection and will show duly open source software available to users by user environment.

• Steel and Composite Structures
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• v.17 no.1
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• pp.69-81
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• 2014

The novelty of this paper is the use of trigonometric four variable plate theory for free vibration analysis of laminated rectangular plate supporting a localized patch mass. By dividing the transverse displacement into bending and shear parts, the number of unknowns and governing equations of the present theory is reduced, and hence, makes it simple to use. The Hamilton's Principle, using trigonometric shear deformation theory, is applied to simply support rectangular plates. Numerical examples are presented to show the effects of geometrical parameters such as aspect ratio of the plate, size and location of the patch mass on natural frequencies of laminated composite plates. It can be concluded that the proposed theory is accurate and simple in solving the free vibration behavior of laminated rectangular plate supporting a localized patch mass.

• Proceedings of the Korean Society for Quality Management Conference
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• 2004.04a
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• pp.298-301
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• 2004

European Union Member States shall ensure that, from 1 July 2006, new electrical and electronic equipment put on the market does not contain mercury, cadmium, lead, hexavalent chromium, polybrominated biphenyls(PBB) or polybrominated diphenyl ethers(PBDE) (by Directive 2002/95/EC of The European Parliament and the Council of 27 january, 2003 on the restriction of the use of certain hazardous substances in electrical and electronic equipment ). So, It is important to develop lead free solder and to assure the reliability of appliance. But lead free solder(i.e. Sn-3Ag-0.5Cu) have some problems such as lift off, whisker, migration and crack, etc. In this paper we discuss the reliability assurance method in lead free solder and appliance.

• Archives of Reconstructive Microsurgery
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• v.15 no.2
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• pp.51-57
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• 2006

Free flap having been used for reconstruction of skin and soft tissue defect in various areas in a body is spreading up its application for not only functional reconstruction but also aesthetic reconstruction. Authors met with good results minimizing the demerits of anastomosis using suture through microvascular anastomotic device, hereupon, we intend to report this. We worked with 27 cases that used microvascular anastomotic device for venous anastomoses among patients who were processed free flap in our hospital. Age ranged from 12 to 63 (average 43.2), and there were 12 females and 15 males. As a result of a follow-up by 3 months - 5years (average 11.3 months), there was no particular complication in the anastomosed vein except 1 cases among 27 cases that sutured their veins through microvascular anastomotic device. Use of microvascular anastomotic device at free flap shortened the time required for vascular anastomoses to reduce ischemic time of tissue, and minimized the damage of intima during anastomoses and made easy anastomoses possible even in case the difference of diameters of blood vessels being sutured is wide. As well, even for survival rate of flap, satisfactory results were obtained compared with using suture. Consequently, it is concluded that use of microvascular anastomotic device in free flap is a useful way that can substitute existing anastomosis using suture.

• Smart Structures and Systems
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• v.17 no.5
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• pp.753-771
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• 2016

This paper addresses the free and transient responses of a SDOF linear complex stiffness system by making use of the Hilbert transform and the convolution integral. Because the second-order differential equation of motion having the complex stiffness give rise to the conjugate complex eigen values, its time-domain analysis using the standard time integration scheme suffers from the numerical instability and divergence. In order to overcome this problem, the transient response of the linear complex stiffness system is obtained by the convolution integral of a green function which corresponds to the unit-impulse free vibration response of the complex system. The damped free vibration of the complex system is theoretically derived by making use of the state-space formulation and the Hilbert transform. The convolution integral is implemented by piecewise-linearly interpolating the external force and by superimposing the transient responses of discretized piecewise impulse forces. The numerical experiments are carried out to verify the proposed time-domain analysis method, and the correlation between the real and imaginary parts in the free and transient responses is also investigated.

• Journal of Trauma and Injury
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• v.20 no.2
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• pp.119-124
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• 2007

Purpose: Management of the soft tissue defect in the lower extremity caused by trauma has always been difficult. Coverage with local and free muscle flaps after complete surgical excision of necrotic soft tissue and bone is a major strategy for treatment. There is no doubt that muscle provides a good blood supply, thus improving bone healing and increasing resistance to bacterial inoculation. However, accompanying problems are seen in cases with shallow dead space. This research was conducted to assess the efficacy of raising anterolateral thigh flaps and transferring them to the defect after complete debridement of non-viable, infected, and scar tissue as an alternative way to use local or free muscle flaps. Methods: From March 2005 to October 2007, 18 cases of soft tissue defect on lower extremities were re-surfaced with an anterolateral thigh perforator free flap. Results: The follow-up period ranged from 1 to 31 months with a mean of 15.9 months. All flaps survived completely. Satisfactory aesthetic and functional results were achieved. Under a two-point discrimination test, 13 patients had sensory recovery from 11 mm to 20 mm after 6 months postoperatively. Conclusion: Reconstruction of the lower extremity with anterolateral thigh perforator free flaps after appropriate debridement is a good alternative way to use local or free muscle flaps.

• Journal of Korean Society of Archives and Records Management
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• v.14 no.4
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• pp.177-198
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• 2014

This study analyzed the meanings and other details of the provisions in line with the free use of public works introduced through the Copyright Act of Korea in Dec. 2013 in the aspect of archival information services and indicated the limitations as follows. First, not all institutions shall follow the provisions because it does not cover all institutions under the Law of Records Management in Korea. Second, even though most of works made for hire in state institutions, local governments, and public institutions are not yet made public, to enable a work to be made public is a requisite for public works to be used for free. This is to limit the scope of public works. To solve the problems, this study suggested the revision directions of the Copyright Act of Korea that every school, which creates works made for hire, are covered in the institutions that enable the free use of works and change the requisite to make a work public for the disclosure the information. This study also suggested that the element for copyright information shall be created in the records schedule for public institutions and metadata standard for records management. The copyright information shall also be described when the records are registered.