• The Journal of Korea Robotics Society
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• v.14 no.3
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• pp.228-235
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• 2019

This paper presents a multiple DoFs (degrees-of-freedom) prosthetic forearm and sEMG (surface electromyogram) pattern recognition and motion intent classification of forearm amputee. The developed prosthetic forearm has 9 DoFs hand and single-DoF wrist, and the socket is designed considering wearability. In addition, the pattern recognition based on sEMG is proposed for prosthetic control. Several experiments were conducted to substantiate the performance of the prosthetic forearm. First, the developed prosthetic forearm could perform various motions required for activity of daily living of forearm amputee. It was able to control according to shape and size of the object. Additionally, the amputee was able to perform 'tying up shoe' using the prosthetic forearm. Secondly, pattern recognition and classification experiments using the sEMG signals were performed to find out whether it could classify the motions according to the user's intents. For this purpose, sEMG signals were applied to the multilayer perceptron (MLP) for training and testing. As a result, overall classification accuracy arrived at 99.6% for all participants, and all the postures showed more than 97% accuracy.

• Journal of the Earthquake Engineering Society of Korea
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• v.26 no.3
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• pp.117-125
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• 2022

In this study, centrifuge model tests were performed to evaluate the seismic response of multi-DOF structures with shallow foundations. Also, elastic time history analysis on the fixed-base model was performed and compared with the experimental results. As a result of the centrifuge model test, earthquake amplification at the fundamental vibration frequency of the soil (= 2.44 Hz) affected the third vibration mode frequency (= 2.50 Hz) of the long-period structure and the first vibration mode (= 2.27 Hz) of the short-period structure. The shallow foundation lengthened the periods of the structures by 14-20% compared to the fixed base condition. The response spectrum of acceleration measured at the shallow foundation was smaller than that of free-field motion due to the foundation damping effect. The ultimate moment capacity of the soil-foundation system limited the dynamic responses of the multi-DOF structures. Therefore, the considerations on period lengthening, foundation damping, and ultimate moment capacity of the soil-foundation system might improve the seismic design of the multi-DOF building structures.

• The Journal of Korea Robotics Society
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• v.18 no.2
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• pp.164-171
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• 2023

To control the spread of COVID-19, it is important to identify the infection in its incipient stages so that the infected persons can be dealt with accordingly. The currently used face to face sampling method may increase the risk of infection for medical professionals as it exposes them to the asymptomatic yet infectious patients. This can result in further increases in the load on the medical system and workload of the medical staff. As a solution to this problem, in this paper, we present a robotic system for rapid non-face-to-face automatic nasopharyngeal swab sample collection. The system consists of a custom designed 7-DoF manipulator equipped with a specially developed safety mechanism for restricting the maximum force applied by the tip of the swab. During the swab sampling process, the force applied by the tip of the swab is continuously monitored in real-time by a 3-axis force sensor in order to detect contact with the nasopharynx. The possibility of using this system for automaticnasopharyngeal swab sample collection is proven through experimentation with a phantom model.

• Journal of the Earthquake Engineering Society of Korea
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• v.28 no.4
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• pp.165-170
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• 2024

This study investigated the impact of soil-structure interaction on multi-degree-of-freedom structures using the shallow-foundation Winkler model, known as the BNWF model. The model's period was determined through eigenvalue analysis and compared to results obtained from FEMA's formula. Results indicated that considering the soil, the structure's period increased by up to 8.7% compared to the fixed-base model, aligning with FEMA's calculations. Furthermore, with adequate ground acceleration, roof displacement increased by 3.4% to 3.8%, while base shear decreased by 4% to 10%. However, roof displacement and base shear increased in some earthquake scenarios due to spectral shape effects in regions with extended structural periods. Foundation damping effects, determined through the foundation's moment-rotation history, grew with higher ground acceleration. This suggests that accounting for period elongation and foundation damping can enhance the seismic design of multi-degree-of-freedom structures.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.5
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• pp.65-73
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• 2008

Retaining large stability margin is essential in designing a feedback control system to deal with the uncertainties inherently existing in the mathematical model and the control apparatus. The LQG controller in general loses the stability margin due to the embed Kalman filter. The performance of a control system called LTR with a DUOX structure(LTR/DOUX) to overcome the demerit of LQG controller is to be investigated from the responses in both the time and the frequency domain. The results indicated that the LTR/DOUX recovered the gain margin of 30dB approximately 20 times more than that of LQG/DOUX, resulting in a robust stable control system.

• Journal of the Earthquake Engineering Society of Korea
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• v.12 no.2
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• pp.69-80
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• 2008

In this study, improved capacity spectrum method (CSM) is proposed. The method can account for higher mode contribution to the seismic response of MDOF systems. The CSM has been conveniently used for determining maximum roof displacement using both demand spectrum and capacity curve of equivalent SDOF system. Unlike the conventional CSM, the maximum roof displacement is determined without iteration using inelastic displacement ratio and R factor calculated from demand spectrum and capacity curve. Three moment resisting steel frames of 3-, 9- and 20-stories are considered to test the accuracy of the proposed method. Nonlinear response history analysis (NL-RHA) for three frames is also conducted, which is considered as an exact solution. SAC LA 10/50 and 2/50 sets of ground motions are used. Moreover, this study estimates maximum story drift ratios (IDR) using ATC-40 CSM and N2-method and compared with those from the proposed method and NL-RHA. It shows that the proposed CSM estimates the maximum IDR accurately better than the previous methods.

• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.5 s.51
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• pp.99-106
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• 2006

The Real-Time Hybrid Test system presented in this paper is based on the pseudodynamic test method, and it combines physical testing with model-based simulation. The system is designed to achieve a rate of loading that is significantly higher than that of a conventional pseudodynamic test approaching the real-time response of a structure subjected to earthquake loads. To provide robust computation environment for the analysis of many degree-of-freedom structures, the system adopts an implicit time integration scheme in the model-based simulation. This paper presents an overview of the developed system and numerical simulations that were conducted to evaluate the performance of the computation scheme adopted here. Results of these studies have demonstrated the good performance of the computation scheme for real-time multiple-degree-of-freedom tests.

• Journal of the Korean Geographical Society
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• v.39 no.1
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• pp.1-12
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• 2004

This paper deals with a possible contribution to international relations and affairs by the discipline of geography and raises the necessity of a new field in geography that would study relations between nations. The proposed change of the name 'East Sea' is used as a case study in promoting international standardization. Two major international organizations oversee the international standardization of geographical names. One is the UN Conferences of the Standardization of the Geographical Names which work in association with the UN Group of Experts on Geographical Names, and the other is the International Hydrographic Organization. These two organizations have in the past passed all the relevant resolutions pertaining to geographical names. From recent developments on the Korean Peninsula, however, it has become evident that international disputes on place names sometimes require a long process of consultation with the relevant parties. Efforts being made to restore the historically appropriate name of 'East Sea' as opposed to the 'Sea of Japan' have only now begun to diffuse in many areas. It would be appropriate if geographers could develop a new area of 'Geography of International Relations' that deals with WTO, oceans, environment and climatic issues, FAT, as well as territories and boundaries. Furthermore, it would improve the quality of discourse if geographers participated more in the decision-making processes in international affairs.

• Strategy21
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• s.45
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• pp.188-211
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• 2019

중국 해군의 성장은 동아시아의 안보환경 변화에 지대한 영향을 미치고 있으며, 한국 해군 또한 그 영향에서 벗어날 수 없는 실정이다. 대한민국은 중국과 지리적으로 맞닿아 있으며, 현재 불법 중국어선 및 이어도 문제 등 중국과의 수많은 해양갈등을 겪고 있는 상황으로, 이에 대한 적절한 대응을 위해서 한국 해군은 중국 해군의 현대화에 대한 대응을 준비해야만 한다. 본고는 중국과 한국의 해군력을 로버트 토마스 전 미 해군 중장이 제시한 지휘, 통제, 능력, 수량의 네 가지 측면에서 분석 및 비교하였다. 중국 해군은 적의 접근을 원해에서부터 차단하는 것을 목표로 하고(지휘), 그에 걸맞게 C4I 능력을 확충해나가고 있으며(통제), 전력투사. 수중/수상전, 해상재보급 역량을 늘려가고(능력), 최근 4년간 세계 대다수 해군의 총 톤수를 능가하는 수준의 함정건조 추세를 보이고 있다(수량). 한국 해군은 90년대 이후 "대양해군"을 목표로 해왔으며(지휘) 아덴만까지 실시간으로 통제 가능한 뛰어난 C4I 능력을 갖추었으나(통제), 아직 대양해군에 걸맞는 능력 및 전력을 구비하였다고 보기는 어렵다. 한국 해군이 상기 네 가지 측면에서 중국 해군을 따라잡는 것은 거의 불가능에 가깝다. 중국은 GDP의 2% 이내에서 국방비를 책정함에도 매년 GDP의 2.7%를 국방비에 투자하는 한국 국방비의 6배를 상회하며, 이 격차는 계속 커져가는 추세이다. 따라서, 대한민국 해군은 첫째, 잠수함 등 비대칭 전력 확보에 주력하고 방공/대잠능력 등 방어력을 향상시켜야 하며, 둘째, 관련국과의 긴밀한 협력을 통해 동아시아 및 서태평양 지역에서의 해양안보 안정화를 위해 노력해야한다. ADMM+3 등 다자 안보의 틀 안에서 역내 해양의 안정을 꾀할 수 있도록 한국 해군은 정책적 노력을 경주해야할 것이다.

• Journal of the Earthquake Engineering Society of Korea
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• v.6 no.5
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• pp.19-27
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• 2002

Dynamic responses of a multi-span simply supported bridge are investigated to examine the effect of bearing damage under seismic excitations. The damaged bearings are modeled as sliding elements with friction between the superstructure and the top of the pier. Various values of the friction coefficients are examined to figure out the effect of damaged bearings with various levels of peak ground accelerations. It is found that the global seismic behaviors are significantly influenced by the occurrence of bearing damage. It should be noticed that the most possible location of unseating failure of superstructures differs from that in the bridge model without considering the bearing damage. It can be concluded that the bearing damage may play the major role in the unseating failure of a bridge system, so that the damage of bearings should be included to achieve more rational seismic safety evaluation.