• Smart Structures and Systems
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• 제19권1호
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• pp.21-31
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• 2017

To control the stochastic vibration of a vibration-sensitive instrument supported on a beam, the beam is designed as a sandwich structure with magneto-rheological visco-elastomer (MRVE) core. The MRVE has dynamic properties such as stiffness and damping adjustable by applied magnetic fields. To achieve better vibration control effectiveness, the optimal bounded parametric control for the MRVE sandwich beam with supported mass under stochastic and deterministic support motion excitations is proposed, and the stochastic and shock vibration suppression capability of the optimally controlled beam with multi-mode coupling is studied. The dynamic behavior of MRVE core is described by the visco-elastic Kelvin-Voigt model with a controllable parameter dependent on applied magnetic fields, and the parameter is considered as an active bounded control. The partial differential equations for horizontal and vertical coupling motions of the sandwich beam are obtained and converted into the multi-mode coupling vibration equations with the bounded nonlinear parametric control according to the Galerkin method. The vibration equations and corresponding performance index construct the optimal bounded parametric control problem. Then the dynamical programming equation for the control problem is derived based on the dynamical programming principle. The optimal bounded parametric control law is obtained by solving the programming equation with the bounded control constraint. The controlled vibration responses of the MRVE sandwich beam under stochastic and shock excitations are obtained by substituting the optimal bounded control into the vibration equations and solving them. The further remarkable vibration suppression capability of the optimal bounded control compared with the passive control and the influence of the control parameters on the stochastic vibration suppression effectiveness are illustrated with numerical results. The proposed optimal bounded parametric control strategy is applicable to smart visco-elastic composite structures under deterministic and stochastic excitations for improving vibration control effectiveness.

• 한국중재학회지:중재연구
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• 제31권1호
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• pp.83-105
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• 2021

If aggrieving consumers or employees cannot prove both substantive and procedural unconscionability, many U.S. state courts will enforce arbitration agreements. Additionally, U.S. courts weigh a variety of factors to determine whether an arbitration agreement is substantively unconscionable. For example, U.S. courts have considered one or a combination of the following factors: (1) the fairness of contractual terms; (2) the severity of contractual terms' deviation from prevailing standards, customs, or practices within a particular industry; (3) the reasonableness of goods-and-services contract prices; (4) the commercial reasonableness of the contract terms; (5) the purpose and effect of the terms and (6) "the allocation of risks between the parties." Further, procedural unconscionability characterized by surprise or lack of knowledge focuses on terms that are deceptively hidden in a mass of contract language, the object of another concealment, or imposed in the circumstances involving haste or high-pressure tactics so that they are not likely to be read or understood. This unconscionability doctrine can be applied to a situation where an alcoholic dementia-afflicted older adult is admitted to a nursing home. At that time, because she had alcoholic dementia, which precluded her reading, comprehending, writing, negotiating, or signing of any legal document, her son, who did not understand the adhesion contract, signed the standardized residential contract and the arbitration agreement.

• 반도체디스플레이기술학회지
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• 제17권4호
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• pp.42-45
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• 2018

As The semiconductor decrease from 10 nanometer to 7 nanometer, It is suggested that "More than Moore" is needed to follow Moore's Law, which has been a guide for the semiconductor industry. Fan-Out Wafer Level Package(FOWLP) is considered as the key to "More than Moore" to lead the next generation in semiconductors, and the reasons are as follows. the fan-out WLP does not require a substrate, unlike conventional wire bonding and flip-chip bonding packages. As a result, the thickness of the package reduces, and the interconnection becomes shorter. It is easy to increase the number of I / Os and apply it to the multi-layered 3D package. However, FOWLP has many issues that need to be resolved in order for mass production to become feasible. One of the most critical problem is the warpage problem in a process. Due to the nature of the FOWLP structure, the RDL is wired to multiple layers. The warpage problem arises when a new RDL layer is created. It occurs because the solder ball reflow process is exposed to high temperatures for long periods of time, which may cause cracks inside the package. For this reason, we have studied warpage in the FOWLP structure using commercial simulation software through the implementation of the reflow process. Simulation was performed to reproduce the experiment of products of molding compound company. Young's modulus and poisson's ratio were found to be influenced by the order of influence of the factors affecting the distortion. We confirmed that the lower young's modulus and poisson's ratio, the lower warpage.

• 융합보안논문지
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• 제19권1호
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• pp.41-48
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• 2019

사물인터넷, 인공지능 시대에 데이터가 사회와 경제 전반의 핵심자원이 되어 '데이터 중심 경제'를 이끌어가고 있다. 대량 데이터의 디지털화는 필수적이 되었고, 더불어 디지털화된 개인정보가 쉽게 수집, 저장, 복제, 분석이 가능해졌다. 전통적인 개인정보의 개념이 변화되고, 디지털화된 개인정보의 보호와 활용을 위해 미국, 유럽연합(EU), 일본, 우리나라 등 세계 각 국은 비식별화, 익명화, 가명화 개념과 규정을 신설하였다. 각 국의 비식별화 정책에서 이러한 개념들이 구분 혹은 혼용되고 있는데, 이러한 각 국의 정책 현황을 조사, 비교 및 분석하고자 한다. 이를 기반으로 우리나라 비식별화 정책 개선 방향을 모색하고, 빅데이터 시대에 개인정보의 보호와 활용의 균형적 조화를 이루어 디지털 경제에 발전에 기여 할 수 있는 정책 제언을 하고자한다.

• 융합보안논문지
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• 제19권2호
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• pp.21-28
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• 2019

제4차 산업혁명 시대로 불리는 초연결-초지능 사회의 출현은 안보 환경의 새로운 변화를 가져왔다. ICT(정보통신기술) 융 복합 하이테크 기술이 전 방위적으로 도입되면서 현실 공간을 움직였던 사람 중심의 동력은 코드를 중심으로 한 사이버 공간으로 대체되고 있으며, 그 의존도는 계속 높아지고 있다. 하지만 이러한 기술적 변화는 역설적으로 우리 사회를 위협하는 또 다른 안보취약점으로 작용하고 있으며, 과학기술이 가져온 기회와 도전을 동시에 직면하며 사이버 방어체계를 구축해야 하는 당위성을 가져왔다. 이에 본 연구에서는 갈수록 지능화되고 대규모로 진화하고 있는 사이버 공격에 적극적으로 대응할 수 있는 이론적 근거로 정당방위 이론을 제시하였고, 이에 대한 자주적 사이버 안보전략 수립 방향으로 첫째, 사이버 안보법 제정의 필요성 둘째, 미국 등 사이버 강대국들과의 대응공조 체계 마련 셋째, 사이버 인력을 어떻게 양성할 것인가에 대한 방안 마련을 제언하였다.

• 한국기계가공학회지
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• 제18권5호
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• pp.29-36
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• 2019

In modern society in which the fourth industrial revolution has come to the fore and rapid technology innovations are taking place, a phenomenon of making and selling small quantities of various products that consumers want instead of mass producing one item has emerged. As the market is moving toward the multi-item small-sized production system, there is a need for a system in which a machine independently judges and carries out machining and post-processing. In order for a machine to judge processing on its own, it is necessary to measure the force applied to a product. This study aimed to develop a large-scale dynamometer that enables three-axis measurement using octagonal ring load cells. As for the device's configuration, four octagonal ring load cells, which were previously researched, were used to enable three-axis measurement. It was reconfigured by modifying the attachment position of the octagonal ring load cells' strain gauge and the Wheatstone bridge of each axis, and a system was set up to allow the monitoring of data measured through the monitor. The configured device calculated a strain rate by an experiment, and this rate was compared with the theoretical strain rate to find a correction value. The correction value was entered into a formula, deriving a modified formula. The modified formula was entered into the device, which completed the large-scale dynamometer.

• 한국항공우주학회지
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• 제49권9호
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• pp.749-757
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• 2021

쿼드로터를 활용한 운송 임무에서 임의의 유상하중을 장착하게 되면 질량, 관성모멘트, 무게중심의 위치와 같은 모델 파라미터가 변화하게 된다. 더욱이 유상하중이 기체에 장착되는 위치가 기체의 무게중심과 일치하지 않는 경우 무게중심의 변화는 야기되며 이는 제어 성능에 악영향을 미치게 된다. 이에 본 논문에서는 유상하중에 따른 모델의 불확실성을 보상하기 위하여, 선형 제차 조정기(Linear Quadratic Regulator, LQR) 기반의 모델 참조 적응 제어기법(Model Reference Adaptive Control, MRAC)을 제안한다. 먼저 고정된 유상하중을 고려한 쿼드로터의 동역학 모델을 유도하고, 선형 제차 조정기를 이용하여 기준제어기를 선정한다. 참조 모델은 과도응답을 향상하기 위해 폐루프 참조 모델을 사용하였으며, 선형 제차 조정기를 통하여 선정하였다. 또한, 안정성 분석을 통하여 모델 파라미터를 추정하기 위한 적응 제어기법을 설계하였다. 제안하는 제어기의 성능을 확인하기 위하여 모델 파라미터의 불확실성이 존재하는 상황에서 선형 재차 조정기와 성능을 비교하였다. 그리고 외란이 있는 상황에서 기존의 모델 참조 적응 제어기법과도 제안한 제어기의 결과를 비교하여 과도응답과 강건성에 대해서도 분석하였다.

• 한국직업건강간호학회지
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• 제28권4호
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• pp.271-284
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• 2019

Purpose: This study aimed to examine the process from occurrence of a hospital nurse's suicide to workers' compensation approval, responses of the parties involved, issues debated during approval deliberations, and significant policy changes resulting from the incident. Methods: We conducted in-depth interviews with involved parties and collected various documents, including newspaper articles, forum proceedings, and the agency report on determination of workers' compensation. Content analysis was performed on the collected data. Results: A Joint Task Force continuously reported its progress and findings through mass media such as newspaper, radio, and TV. These activities exerted pressure on a government agency to conduct an occupational disease review and significantly impacted the workers' compensation approval. The agency recognized associations between the hospital's inadequate nurse training and the suicide but did not confirm the excessive overtime and workplace harassment experienced by the nurse as causes of the suicide. This case's media coverage and impact resulted in a law prohibiting workplace harassment and a hospital system dedicating at least one nurse to training activities. Conclusions: This incident had a significant social impact as the first case of workers' compensation approval for a hospital nurse's suicide. However, the case produced no structural changes in nurses' working conditions such as heavy workloads.

• International Journal of Naval Architecture and Ocean Engineering
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• 제12권1호
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• pp.376-386
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• 2020

The aim of this study was to develop a new efficient strategy that uses the Vector form Intrinsic Finite-element (VFIFE) method to conduct the static and dynamic analyses of marine pipes. Nonlinear problems, such as large displacement, small strain, and contact and collision, can be analyzed using a unified calculation process in the VFIFE method according to the fundamental theories of point value description, path element, and reverse motion. This method enables analysis without the need to integrate the stiffness matrix of the structure, because only motion equations of particles established according to Newton's second law are required. These characteristics of the VFIFE facilitate the modeling and computation efficiencies in analyzing the nonlinear dynamic problem of flexible pipe with large deflections. In this study, a three-dimensional (3-D) dynamical model based on 3-D beam element was established according to the VFIFE method. The deep-sea flexible pipe was described by a set of spatial mass particles linked by 3-D beam element. The motion and configuration of the pipe are determined by these spatial particles. Based on this model, a simulation procedure to predict the 3-D dynamical behavior of flexible pipe was developed and verified. It was found that the spatial configuration and static internal force of the mining pipe can be obtained by calculating the stationary state of pipe motion. Using this simulation procedure, an analysis was conducted on the static and dynamic behaviors of the flexible mining pipe based on a 1000-m sea trial system. The results of the analysis proved that the VFIFE method can be efficiently applied to the static and dynamic analyses of marine pipes.

• 터널과지하공간
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• 제31권1호
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• pp.66-81
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• 2021

본 연구는 삼차원 절리텐서 파라미터와 DFN(discrete fracture network) 블록의 변형특성 간의 상관성 분석을 수행하여 절리텐서의 방향성분 및 일차불변량이 절리성 암반의 변형계수 및 전단탄성계수에 미치는 영향을 평가하였다. 확정적 방향성을 갖는 1~2개의 절리군을 사용하여 절리의 빈도 및 길이분포의 변화에 따라 생성한 총 224개의 DFN 블록에 대하여 절리텐서 파라미터가 산정되었다. 또한, 정육면체 DFN 블록에 대하여 개별요소법을 활용하여 서로 직교하는 세 방향으로 변형특성이 추정되었다. 절리텐서의 일차불변량이 증가할수록 변형계수 및 전단탄성계수는 대체로 저감되는 양상을 나타내지만, 감소폭이 줄어들어 일차불변량이 특정 기준값을 상회하면 변형계수 및 전단탄성계수는 거의 일정한 값을 유지하였다. 삼차원 DFN 블록에 대한 지향적 변형특성은 대응하는 방향의 절리텐서성분과 멱함수의 강한 상관관계를 도출하였다.