• 한국보건간호학회지
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• 제27권1호
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• pp.153-165
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• 2013

Purpose: The purpose of this study was to identify the relationships between physical activity, health status, and quality of life (QOL) of University students. Methods: The research design was based on a descriptive research design model. This study sample consisted of 183 K University students in D city. Data was collected from December 2012 to January 2013 and analyzed with descriptive statistics (frequency, percentage, analysis of variance (ANOVA), t-test, and Pearson's correlation analysis) using SPSS 19.0. Subjects completed questionnaires on their demographics, physical activity, health status, and QOL. Results: The overall physical activity of participants was $2529.40{\pm}5057.896$ min/week on average. The average health status was $28.66{\pm}6.3$ and the average physical health and mental health were $16.45{\pm}3.955$ and $12.31{\pm}3.446$, respectively. The overall degree of QOL was $3.429{\pm}0.379$. A positive relationship existed between moderate and vigorous activity and health status. In addition, QOL positively correlated with physical health (under health status). However, physical activity was not related with both mental health (under health status) and QOL. Conclusion: Based on the results of this study, health educational programs are needed to promote sufficient physical activity in university students.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권5호
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• pp.2529-2543
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• 2019

Scanning electron microscopy (SEM) image can link with the microscopic world through reflecting interaction between electrons and materials. The SEM images are easily subject to blurring distortions during the imaging process. Inspired by the fact that dark channel prior captures the changes to blurred SEM images caused by the blur process, we propose a method to evaluate the SEM images sharpness based on the dark channel prior. A SEM image database is first established with mean opinion score collected as ground truth. For the quality assessment of the SEM image, the dark channel map is generated. Since blurring is typically characterized by the spread of edge, edge of dark channel map is extracted. Then noise is removed by an edge-preserving filter. Finally, the maximum gradient and the average gradient of image are combined to generate the final sharpness score. The experimental results on the SEM blurred image database show that the proposed algorithm outperforms both the existing state-of-the-art image sharpness metrics and the general-purpose no-reference quality metrics.

• Nuclear Engineering and Technology
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• 제54권7호
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• pp.2529-2539
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• 2022

Stochastic and an empirical Green's function (EGF) methods are preliminarily applied to simulate strong ground motions (SGMs) at seismic stations within nuclear power plant (NPP) sites in South Korea by an assumed large earthquake with M_W6.5 (scenario earthquake) on the causative fault of the 2016 Gyeongju earthquake with M_W5.5 (mainshock). In the stochastic method, a ratio of spectral amplitudes of observed and simulated waveforms for the mainshock is assumed to be an adjustment factor. In the EGF method, SGMs by the mainshock are simulated assuming SGMs by the 2016 Gyeongju earthquake with M_W5.0 (foreshock) as the EGF. To simulate SGMs by the scenario earthquake, a ratio of fault length to width is assumed to be 2:1 in the stochastic method, and SGMs by the mainshock are assumed to be EGF in the EGF method. The results are similar based on a bias of the simulated response spectra by the two methods, and the simulated response spectra by the two methods exceeded commonly standard design response spectra anchored at 0.3 g of NPP sites slightly at a frequency band above 4 Hz, but considerable attention to interpretation is required since it is an indirect comparison.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권7호
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• pp.2512-2529
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• 2015

Wireless mesh networks (WMNs) provide an efficient and flexible method to the field of wireless networking, but also bring many security issues. A mesh point may lose all of its available links during its movement. Thus, the mesh point needs to handover to a new mesh point in order to obtain access to the network again. For multi-domain WMNs, we proposed a new ID-based signcryption scheme and accordingly present a novel ID-based handover protocol for mesh points. The mutual authentication and key establishment of two mesh points which belong to different trust domains can be achieved by using a single one-round message exchange during the authentication phase. The authentication server is not involved in our handover authentication protocol so that mutual authentication can be completed directly by the mesh points. Meanwhile, the data transmitted between the two mesh points can be carried by the authentication messages. Moreover, there are no restrictions on the PKG system parameters in our proposed multi-domain ID-based signcryption scheme so our handover scheme can be easily applied to real WMNs circumstances. Security of the signcryption scheme is proved in the random oracle model. It shows that our protocol satisfies the basic security requirements and is resistant to existing attacks based on the security of the signcryption. The analysis of the performance demonstrates that the protocol is efficient and suitable for the multi-domain WMNs environment.

• 한국산학기술학회논문지
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• 제10권9호
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• pp.2523-2529
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• 2009

본 연구는 시판중인 어린이 음료가 치아 표면의 탈회에 미치는 영향에 대해 평가하고자 하였다. 치아우식이 없는 건전한 표면의 우치로 만든 시편 15개를 4개의 실험군(n=12)과 대조군(n=3)으로 각각 나누었다. 모든 샘플은 각 각의 음료에 담근 후 48시간 동안 $37^{\circ}C$의 배양기에서 처리 한 후 표면의 변화를 관찰하였다. 음료처리 후 법랑질 표면의 탈회로 인해 표면미세경도 값은 감소하였고, DIGNOdent 값은 증가하였다. 이러한 현상은 특히 탄산음료에서 통계적으로 유의한 차이를 보였다. 한편, 음료 처리 후 주사전자현미경 상의 법랑질 표면은 어린이음료에서 가장 많은 탈회 현상이 관찰되었다

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제16권8호
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• pp.2529-2551
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• 2022

Visual servoing (VS) based on the Kalman filter (KF) algorithm, as in the case of KF-based image-based visual servoing (IBVS) systems, suffers from three problems in uncalibrated environments: the perturbation noises of the robot system, error of noise statistics, and slow convergence. To solve these three problems, we use an IBVS based on KF, African vultures optimization algorithm enhanced extreme learning machine (AVOA-ELM), and fuzzy logic (FL) in this paper. Firstly, KF online estimation of the Jacobian matrix. We propose an AVOA-ELM error compensation model to compensate for the sub-optimal estimation of the KF to solve the problems of disturbance noises and noise statistics error. Next, an FL controller is designed for gain adaptation. This approach addresses the problem of the slow convergence of the IBVS system with the KF. Then, we propose a visual servoing scheme combining FL and KF-AVOA-ELM (FL-KF-AVOA-ELM). Finally, we verify the algorithm on the 6-DOF robotic manipulator PUMA 560. Compared with the existing methods, our algorithm can solve the three problems mentioned above without camera parameters, robot kinematics model, and target depth information. We also compared the proposed method with other KF-based IBVS methods under different disturbance noise environments. And the proposed method achieves the best results under the three evaluation metrics.

• 한국정보통신학회논문지
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• 제18권10호
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• pp.2523-2529
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• 2014

실외에서는 GPS를 기반으로 하는 다양한 위치 추정 시스템을 사용하여 위치 추정 서비스를 제공할 수 있으나, 실내에서는 가시위성의 부족과 신호의 미약으로 GPS를 사용할 수 없어 실내에 존재하는 자원을 기반으로 하는 위치 추정시스템을 사용하고 있다. 특히 WLAN의 신호를 이용하는 fingerprinting 기법은 AP에서 제공하는 RSSI를 이용하여 위치를 추정하기에 실내에서 이용하기에 적합하다. 하지만 fingerprinting 기법은 fingerprinting map을 구축하는 offline 단계에서 얼마나 정확한 데이터를 이용하였는가에 따라 위치 추정의 정확도가 달라지는 단점이 존재한다. 본 논문에서는 이러한 단점을 보완하기 위해 fingerprinting map을 구축하는 단계에서 다수의 데이터를 샘플링 하여 그 중 빈도가 높은 데이터를 저장하여 위치 추정 정밀도를 높이는 위치 추정 시스템을 제안한다. 제안하는 머저리티 샘플링 데이터 기반의 위치 추정 시스템은 map에 저장되어야 하는 RSSI를 클라이언트와 서버에서 가장 빈도가 높은 RSSI데이터를 필터링하여 map을 구축한 후 유사거리측정방식에 의해 위치를 추정하는 시스템이다. 실험결과 최소 87.5 %, 최대 90.4%의 위치 추정 정밀도를 가지는 것을 알 수 있으며, 최소 0.25 ~ 2.72m의 오차 범위를 가지는 것을 확인 할 수 있었다.