• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.3
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• pp.1123-1140
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• 2019

Many Internet of Things (IoT) applications involving bursty traffic have emerged recently with event detection. A power management scheme qualified for uplink bursty traffic (PM-UBT) is proposed by distinguishing between bursty and general uplink traffic patterns in the IEEE 802.11 standard to balance energy consumption and uplink latency, especially for stations with limited power and constrained buffer size. The proposed PM-UBT allows a station to transmit an uplink bursty frame immediately regardless of the state. Only when the sleep timer expires can the station send uplink general traffic and receive all downlink frames from the access point. The optimization problem (OP) for PM-UBT is power consumption minimization under a constrained buffer size at the station. This OP can be solved effectively by the bisection method, which demonstrates a performance similar to that of exhaustive search but with less computational complexity. Simulation results show that when the frame arrival rate in a station is between 5 and 100 frame/second, PM-UBT can save approximately 5 mW to 30 mW of power compared with an existing power management scheme. Therefore, the proposed power management strategy can be used efficiently for delay-intolerant uplink traffic in event-driven IoT applications, such as health status monitoring and environmental surveillance.

• Journal of Korean Society of Steel Construction
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• v.16 no.1 s.68
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• pp.21-32
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• 2004

In this study, a continuous optimum design model with its application program for plane steel frame structures developed. In the model, the sequential unconstrained minimization technique (SUMT) transforming the nonlinear optimization problem with multidesign variables and constraints into an unconstrained minimization problem and the refined plastic hinge analysis method as one of the most effective second-order inelastic analysis methods for steel frame structures were implemented. The total weight of a steel frame structure was taken as the objective function, and the AISC-LRFD code requirements for the local and member buckling, flexural strength, shear strength, axial strength and size of the cross-sectional shapes of members were used for the derivation of constraint equations. To verify the appropriateness of the present model, the optimum designs of serveral plane steel frame structures subject to vertical and horizontal loads were conducted.

• Science of Emotion and Sensibility
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• v.16 no.2
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• pp.177-186
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• 2013

This study aimed to investigate the differential effects of self-relevance on framing effects. For this purpose, the participants were allocated into two frame type conditions(positive vs. negative), and asked to respond on six decision-making scenarios manipulated by self-relevance levels(low vs. high). The results can be summarized as followings. First, although self-relevance level made no significant difference in framing effects, the positive frame condition tended to induce larger framing effects than the negative frame condition. Second, no significant interaction effect between frame type and self-relevance level condition was found in the positive condition, whereas high self-relevance level condition induced smaller framing effects than law self-relevance level condition in the negative frame condition. These results indicated that although self-relevance tended to reduce framing effects, this effect can be differed in frame types.

• Journal of Navigation and Port Research
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• v.37 no.2
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• pp.221-229
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• 2013

To find the influence of incident angle of wave on the moment of 3 storied steel moment resisting frame which is placed on the concrete rectangular pontoon, the fluid dynamic analysis is carried out, varying the period of wave from 5 to 15 second by 2 seconds. As increasing incident angle of wave to longitudinal axis, the influence of RAO-rolling is increased. The moment of longitudinal frame is increased apparently by the wave pressure when the incident angle is $0^{\circ}$. And the moment of the frame due to the wave pressure is decreased as the incident angle is increased. But the moment of frame due to acceleration caused from pitching and rolling is increased. It is shown that the increased moment when incident angle is $90^{\circ}$ is much greater than that of incident angle $0^{\circ}$.

• Journal of the Korea Computer Graphics Society
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• v.27 no.5
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• pp.55-61
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• 2021

The character motion control based on physics simulation using reinforcement learning continue to being carried out. In order to solve a problem using reinforcement learning, the network structure, hyperparameter, state, action and reward must be properly set according to the problem. In many studies, various combinations of states, action and rewards have been defined and successfully applied to problems. Since there are various combinations in defining state, action and reward, many studies are conducted to analyze the effect of each element to find the optimal combination that improves learning performance. In this work, we analyzed the effect on reinforcement learning performance according to the state representation, which has not been so far. First we defined three coordinate systems: root attached frame, root aligned frame, and projected aligned frame. and then we analyze the effect of state representation by three coordinate systems on reinforcement learning. Second, we analyzed how it affects learning performance when various combinations of joint positions and angles for state.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.7 no.2
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• pp.52-59
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• 2008

The objective of this study is to develop an automatic object changer unit to improve processing problems existed in the conventional horizontal machining center. To achieve this goal, this study designed a horizontal transfer as the second project continued to the first project that designed a upward and downward traverse unit. A horizontal traverse unit shows a symmetric structure and consists of frame, which consists of four unit tools, motor and reducer, which are fixed at a frame, operation unit with pinions, first traverse unit, and second traverse unit. Constraint conditions based on the operation mechanism with these elements were configured and obtained following results after modeling a model for a traverse motor. In the kinematic expression of sliding motion with one degree of freedom, the sliding motion is constrained. Also, the rack 3 installed at a frame is used to configure possible kinematic constraint conditions of the rack 2 according to the rolling motion of the pinion 2 in the first traverse unit. In addition, the moment of inertia that is a type of kinetic energy in a converted horizontal traverse unit in the side of the reducer can be applied to introduce the moment of inertia of a converted horizontal traverse unit in the side of the reducer by using the sum of kinetic energy in the rack and pinion, which is a part of the horizontal traverse unit. Also, the equation of motion of the converted upward and downward traverse unit in the side of the motor using the equation of motion of the motor. Furthermore, the horizontal traverse unit predetermines the mass of the first and second traverse unit and applied load including the radius and reduction ratio of the pitch circle in the pinion 1 and applied load to the rack 2. Then, a proper motor can be determined using several parameters in the upward and downward traverse unit in order to verify such predetermined specifications. In future studies later this study, a simulation that verifies the results of the previous two stages of studies using a finite element method.

• ETRI Journal
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• v.34 no.2
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• pp.184-189
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• 2012

In this paper, we propose a novel approach to statistical model-based voice activity detection (VAD) that incorporates a second-order conditional maximum a posteriori (CMAP) criterion. As a technical improvement for the first-order CMAP criterion in [1], we consider both the current observation and the voice activity decision in the previous two frames to take full consideration of the interframe correlation of voice activity. This is clearly different from the previous approach [1] in that we employ the voice activity decisions in the second-order (previous two frames) CMAP, which has quadruple thresholds with an additional degree of freedom, rather than the first-order (previous single frame). Also, a soft-decision scheme is incorporated, resulting in time-varying thresholds for further performance improvement. Experimental results show that the proposed algorithm outperforms the conventional CMAP-based VAD technique under various experimental conditions.

• Journal of Korea Game Society
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• v.14 no.6
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• pp.29-38
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• 2014

In the large scale indoor 3D game scenes, the data amount of potentially visible set (PVS) which pre-computes the information of occlusion culling can be huge. However, the large part of them can be represented as zero. In this paper, the effective hardware structure is designed, which compresses PVS data as the way of zero run length encoding (ZRLE) during building the scene trees of 3D games in mobile environments. The compression ratio of the proposed structure and the rendering speed (frame per second: FPS) according to both PVS culling and frustum culling are analyzed under 3D game simulations.

• Journal of Korea Game Society
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• v.13 no.4
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• pp.25-34
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• 2013

Spatial partitioning trees are needed for processing collision detections efficiently. In order to select split planes for spatial partitioning trees, the tree balance and the number of polygons overlapped with the split plane should be considered. In this paper, the heuristic algorithm controlling weight values of tree build criteria is proposed for spatial partitioning trees of 3D games. As the weight values are changed, tree build time, T-junction elimination time which can cause visual artifacts in splitting polygons overlapped with the split plane, rendering speed (frame per second: FPS) according to tree balance are analysed under 3D game simulations.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2016.11a
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• pp.63-65
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• 2016

DVB (Digital Video Broadcasting)-S2 (Satellite - Second Generation) 표준은 현재 위성방송 시스템으로 가장 많이 사용되고 있는 표준이나, 추가적인 성능향상과 보다 다양한 응용분야에 적용하기 위해 DVB-S2 기술을 확장한 DVB-S2x (Satellite - Second Generation Extension) 시스템이 제정되었다. 그 중에서도 612,540 심볼 길이의 수퍼프레임 (Super-frame) 구조를 선택적으로 도입하여 긴 데이터 길이에 대해 스크렘블링 (Scrambling)을 적용하는 방법과 PLS (Physical Layer Signaling) 코드와 같은 참조 데이터 필드를 반복적으로 사용하는 방법 등을 사용할 수 있도록 하였다. 이를 통해 동일채널 간섭 (co-channel interference)에 대한 강인성을 증가시키고, 매우 낮은 SNR (Signal to Noise Ratio) 환경에서의 수신기 성능 향상 효과를 제공하게 된다 본 논문에서는 버스트 슈퍼프레임 전송 기반의 DVB-S2x 수신기를 위한 동기부를 설계하고 구조를 제안한다. 슈퍼프레임의 포맷은 DVB-S2x Annex E 의 규격 중 2 번 포맷을 이용하였으며, 2 번 슈퍼프레임 포맷은 버스트 (burst) 기반의 전송 방식에 용이한 측면이 있다. 동기부는 크게 버스트 검출부, 주파수 복구부, 신호 이득 조절부 그리고 심벌 타이밍 복구부로 구성된다.