• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 하계종합학술대회 논문집(1)
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• pp.265-268
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• 2004

In this paper. we propose an adaptive step-size algorithm for the adaptive interference canceller (AIC) in the space-time trellis coded DS-CDMA system. In the AIC, the performance of the blind LMS algorithms that updates the tap-weight vector of the AIC is heavily dependent on the choice of step-size. To improve the performance of the fixed step-size AIC (FS-AIC), the regular adaptive step-size algorithm is extended in complex domain and applied to the joint AIC and ML decoder scheme. Simulation results show that the joint adaptive step-size AIC (AS-AIC) and ML decoder scheme using the proposed algorithm has boner performance than not only the conventional ML decoder but also the joint FS-AIC and ML decoder scheme without much increase of the decoding delay and complexity.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2016년도 춘계 학술논문 발표대회
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• pp.22-23
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• 2016

This study aims to derive the optimal condition that ensures the monolithicity of ultra-high performance concrete (UHPC), through the evaluation of bonding shear performance with respect to the time of cold joint occurrence during the placement. From the direct shear test, while the normalized bonding shear strength reduction of UHPC with the delay time of 15 minutes was the lowest at around 8%, a dramatic degradation of bonding shear performance was observed after 15 minutes. XRD analysis of the middle and surface sections was performed in order to analyze the composition of the thin film formed at the surface of UHPC, and as a result, the main ingredient appeared to be SiO₂ from the XRD pattern of middle and surface sections, which is believed to be the result of the rising of SiO₂-based filler, used as anadmixture in this study, toward the surface, due to its low specific gravity.

• 구강회복응용과학지
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• 제32권1호
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• pp.38-46
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• 2016

목적: 단순악관절 진동군에서 좌/우 진동 중 유의한 진동의 감별법을 연구하는 것이다. 연구 재료 및 방법: 단순악관절 진동만을 갖고 있고 측두하악관절 질환의 제 증상이 없는 단순악관절 진동그룹 30명의 60개 관절에서 44쌍의 진동을 기록하였고 대상자의 인지와 검사자의 촉진, JVA 검사 결과를 비교하였다. JVA로 기록된 진동의 주파수 스펙트럼, 진동파형 시간차 위상변위 분석, 수치 분석을 통해 좌/우 진동 중 유의한 진동을 감별하였다. 결과: JVA 분석결과 양측성 진동은 한 건도 없었으며 유의한 편측 진동은 42개로 감별되었다. 시간차 위상변위를 보이는 것은 11쌍이었고 이 중 한 쌍을 제외한 모든 진동에서 전달된 측의 진동이 발생측 진동보다 진동 총에너지(total integral) 값은 더 작고 > 300 / < 300 ratio는 같거나 더 큰 특징을 보이는 것을 관찰하였다. 또한 진동 총에너지 값이 10 이하로 작고 시간차 위상변위를 보이지 않아 좌/우 감별의 근거가 모호한 나머지 진동 모두에서 진동 총에너지 값이 더 작은 쪽의 > 300 / < 300 ratio가 더 큼을 관찰하여 이를 좌/우 감별의 근거로 삼을 수 있었다. 결론: JVA로 좌/우 진동 중 유의한 진동을 감별하기 위해서는 주파수 스펙트럼, 시간차 위상변위 및 수치 분석 등이 모두 고려되어야 한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제18권1호
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• pp.211-232
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• 2024

In this paper, we consider the resource allocation and offloading decisions of device-to-device (D2D) cooperative UAV-assisted mobile edge computing (MEC) system, where the device with task request is served by unmanned aerial vehicle (UAV) equipped with MEC server and D2D device with idle resources. On the one hand, to ensure the fairness of time-delay sensitive devices, when UAV computing resources are relatively sufficient, an optimization model is established to minimize the maximum delay of device computing tasks. The original non-convex objective problem is decomposed into two subproblems, and the suboptimal solution of the optimization problem is obtained by alternate iteration of two subproblems. On the other hand, when the device only needs to complete the task within a tolerable delay, we consider the offloading priorities of task to minimize UAV computing resources. Then we build the model of joint offloading decision and power allocation optimization. Through theoretical analysis based on KKT conditions, we elicit the relationship between the amount of computing task data and the optimal resource allocation. The simulation results show that the D2D cooperation scheme proposed in this paper is effective in reducing the completion delay of computing tasks and saving UAV computing resources.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.306-309
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• 2005

This parer describes the tracking control simulation of 6-DOF shaking table with a bell crank structure, which converts the direction of reciprocating movements. For the Joint coordinate-based control which uses lengths of each actuator, the trajectory conversion process inverse kinematics is performed. Applying the Newton-Euler approach, the dynamic equation of the shaking table is derived. To cope with nonlinear problems, time-delay control(TDC) is considered, which has been noted for its exceptional robustness to parameter uncertainties and disturbance, in addition to steady-state accuracy and computational efficiency. If the nominal model is equal to the real system, joint coordinate-based control can be very efficient. However, manufacturing tolerances installation errors and link offsets contaminate the nominal values of the kinematic parameters used in the kinematic model of the shaking table. To compensate differences between the nominal model and the real system. the joint coordinate-based control using acceleration feedback in the Cartesian coordinate space is proposed.

• 한국운동역학회지
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• 제17권1호
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• pp.111-119
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• 2007

The purpose of this study was to investigate muscle activity and gait pattern in lower limb depending on the outsole of heel rockers. Fifteen healthy men volunteered for this experiment. Each subject performed totally three trails with two pairs of different heel rocker shoes and a pair of normal running shoes at speed of 1.33m/s for 1 minute during walking on a treadmill. Kinematic data gathered in 100Hz was recorded and analyzed by using the 3D motion capture system to measure the trunk tilt and joint angle of the right lower limb. And the lower extremity muscle activities were simultaneously recorded in 1000Hz and assessed by using EMG. The statistical analysis was the one-way ANOVA with the repeated measures to compare among the three kinds of shoes. The level of statistical significance for all tests was 0.05. Joint angle of lower limb was showed statistically significant different in MST(hip joint), LHS(ankle joint), and RTO(knee and ankle joint). Muscle activity of rectus femoris and biceps femoris was statistically increased in both heel rocker shoes during gait cycle on treadmill. The maximum peak time of tibialis anterior in the negative heel rocker showed the delay of approximately 23.8%time than normal shoes. Gait pattern variability of the negative heel rocker was increased in the first half of the stance phase and the variability of the positive heel rocker was increased in the terminal stance phase. In Conclusion, stability was decreased in between joints of lower limb on positive heel rocker than negative heel rocker. This study found that there were different joint angle, muscle activity, gait pattern and coordinate system of the lower limb in each kind of shoes. These unstability affected the lower extremity and the whole body. A further study has to be continued with study of rehabilitation and exercise for a long-term.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2022년도 가을 학술논문 발표대회
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• pp.15-16
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• 2022

This study is to confirm the integration performance of joints according to the method of applying the super retarding agent. When the super-delay system was applied, the integration performance was found to decrease somewhat on the 7th day of age. In the case of the 28th of age, it was found that the integration performance is improved. When a diluent is injected and a super delay agent is sprayed, shear bond strength is the highest.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2020년도 가을 학술논문 발표대회
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• pp.75-76
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• 2020

In this study, in order to check whether the adhesion strength can be secured when installing concrete by mixing super-retarding agents, the splitting tensile strength of the joints of each mold was measured and then analyzed. The results of the experiment showed that the bonding performance of the joint is adversely affected if the installation delay is delayed for more than 24 hours, and that the attachment performance can be secured if the installation is delayed within about 24 hours.

• 천문학회보
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• 제46권2호
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• pp.44.2-44.2
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• 2021

Detecting lensed quasar systems and estimating their time delays using the unresolved joint light curves can be the next frontier among the cosmological probes in the near future. One can get the independent measurement of the Hubble constant from the time delays but without requiring the systems to be resolved a priori followed by monitoring the image light curves using high-resolution telescopes for years. In this work, we propose a novel technique that can identify lensed quasars only using the observed unresolved light curves and without assuming a template or any prior information. Following a set of conservative selection criteria that gives zero false-positive outcome, we can accurately estimate the time delay for almost all the lensed systems with marginal noise in the data. For the case of noisy data, our approach can still correctly identify a substantial number of lensed systems with high certainty and measure the time delay accurately.

• ETRI Journal
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• 제45권5호
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• pp.887-898
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• 2023

Aerial base stations (ABSs) seem promising to enhance the coverage and capacity of fifth-generation and upcoming networks. With the flexible mobility of ABSs, they can be positioned in air to maximize the number of users served with a guaranteed quality of service (QoS). However, ABSs may be overloaded or underutilized given inefficient placement, and user association has not been well addressed. Hence, we propose a three-dimensional ABS placement scheme with a delay-QoS-driven user association to balance loading among ABSs. First, a load balancing utility function is designed based on proportional fairness. Then, an optimization problem for joint ABS placement and user association is formulated to maximize the utility function subject to statistical delay QoS requirements and ABS collision avoidance constraints. To solve this problem, we introduce an efficient modified gray wolf optimizer for ABS placement with a greedy user association strategy. Simulation results demonstrate that the proposed scheme outperforms baselines in terms of load balancing and delay QoS provisioning.