• 한국컴퓨터정보학회논문지
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• 제25권4호
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• pp.1-9
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• 2020

본 논문에서는 데이터 압축을 통해 메모리 시스템의 에너지 효율 및 성능을 향상시키는 동적랭크 서브세팅 기법 (Dynamic Rank Subsetting, DRAS)을 제안한다. DRAS 기법은 하나의 메모리 랭크 (Rank)를 두 개의 서브랭크 (Sub-rank)로 동작되도록 하여, 데이터가 절반 크기로 압축될 경우 압축된 데이터를 하나의 서브랭크에만 저장한다. 이를 통해 DRAS 기법은 압축된 데이터에 대한 읽기 및 쓰기 동작의 메모리 대역폭을 두 배로 높일 수 있고, 동적 전력 소모도 절반으로 감소시킬 수 있다. 만약 데이터가 절반 크기로 압축되지 않는다면 기존 메모리 시스템에서와 같이 데이터를 두 서브랭크에 저장한다. 따라서 DRAS 기법은 데이터가 압축되지 않는 경우에 대해서는 기존 메모리 시스템 수준의 메모리 대역폭과 전력 효율성을 보장한다. 메모리 시뮬레이터를 사용한 실험 평가를 통해 DRAS 기법이 컴퓨터 시스템 성능을 평균 12% 향상시키고 메모리 시스템의 전력소모를 평균 24% 감소시킬 수 있음을 보인다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 B
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• pp.983-985
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• 2002

This paper is the machine that is able to estimate a new built power convertor in a production line. Generally, this machine test can be achieved by connecting it to a dynamometer consisting of a three-phase machine joined by a rigid shaft to a DC load machine. But the proposal system is controlled to create some specific load characteristic needed for the test without any mechanical equipment. The suggested test stand consists only of a converter to be test and a simulator converter. Both devices are connected back-to-back on the AC-side via smoothing reactors. The simulator operates in real-time as an equivalent load circuit, so that the device under test will only notice the behaviour of a three-phase machine under consideration of the load. And then, to obtain a superior characteristic for dynamic reference used the feedforward control.

• 한국정밀공학회지
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• 제22권1호
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• pp.89-96
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• 2005

This paper is concerned with a balancing motion formulation and control of the ZMP (Zero Moment Point) for a biped-walking robot that has a prismatic balancing weight or a revolute balancing weight. The dynamic stability equation of a walking robot which have a prismatic balancing weight is conditionally linear but a walking robot's stability equation with a revolute balancing weight is nonlinear. For a stable gait, stabilization equations of a biped-walking robot are modeled as non-homogeneous second order differential equations for each balancing weight type, and a trajectory of balancing weight can be directly calculated with the FDM (Finite Difference Method) solution of the linearized differential equation. In this paper, the 3dimensional graphic simulator is developed to get and calculate the desired ZMP and the actual ZMP. The operating program is developed for a real biped-walking robot IWRⅢ. Walking of 4 steps will be simulated and experimented with a real biped-walking robot. This balancing system will be applied to a biped humanoid robot, which consist legs and upper body, as a future work.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 G
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• pp.3092-3094
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• 1999

This paper deals with the gait generation of Biped Walking Robot (IWR-III) to have a continuous walking pattern like human. For this, trajectory planning with the consideration of kick action is done in each walking step, and the coordinate transformation is done for simplifying the kinematics. The trunk moves continuously for all walking time and moves toward Z-axis. Balancing motion is acquired by FDM(Finite Difference Method) during the walking. By combining 4-types of pre-defined steps, multi-step walking is done. Using numerical simulator, dynamic analysis and system stability is confirmed. Walking motion is visualized by 3D-Graphic simulator. As a result, the motion of balancing joints can be reduced by the trunk ahead effect during kick action, and impactless smooth walking is implemented by the experiment.

• Journal of Multimedia Information System
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• 제6권2호
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• pp.61-66
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• 2019

VANET (Vehicular Ad-hoc Network) is a mobile Ad-hoc Network which deals with the moving vehicles. VANET supports Intelligent Transport Systems (ITS) which is related to different modes of transport and traffic management techniques. VANETs enabled users to be informed and make them safer. VANET uses IEEE 802.11p standard wireless access protocol for communication. An important and necessary issue of VANET is to design routing protocols. In a network, communication takes place by the use of the routing protocols. There are mainly two types of communications used such as Vehicle to Vehicle (V2V) and Vehicle to Infrastructure (V2I) in VANET. Vehicles can send and receive messages among them and also to and from infrastructure used. In this paper, AODV, DSR and DSDV are compared by analysing the results of simulation on various metrics such as average throughput, instant throughput, packet delivery ratio and residual energy. Findings indicates utilization of AODV and DSR is more applicable for these metrics as compared to DSDV. A network simulator (NS2) is used for simulation.

• 한국화재소방학회논문지
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• 제33권5호
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• pp.55-60
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• 2019

랙크식 창고에서 화재가 발생되는 경우 건물이 전소되거나 붕괴되는 상태까지 발생된다. 이러한 현상이 발생되는 이유는 랙크식 창고가 층고가 높고, 물품을 수직으로 적재하고 있어 화재 시 천장에 설치되어 있는 감지기에 의한 조기감지가 어렵고, 그로 인하여 초기에 소화하지 못하기 때문이다. 본 연구에서는 수치해석 프로그램인 Fire dynamic simulator (FDS)를 이용하여 랙크식 창고 내에서 화재 시 발생되는 열과 연기의 유동을 분석하였다. 이러한 분석을 통하여 랙크식 창고 내에서 조기 화재감지를 위한 화재감지기의 최적 설치조건을 확인하였다. 그 결과 랙크식 창고에서 조기 화재감지를 위하여 열과 연기의 복합적인 감지가 필요하며, 복합형 감지기를 랙크의 3 level 마다 설치해야 하며, 정온식 감지기는 랙크식 창고에 적합하지 않은 것을 알 수 있었다.

• 한국정보통신학회논문지
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• 제19권2호
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• pp.308-316
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• 2015

본 논문에서는 이동 애드혹 네트워크에서 사용하는 네 가지 라우팅 프로토콜들을 NS-3 네트워크 시뮬레이터를 사용하여 성능비교를 수행하였다. 성능비교에 사용한 라우팅 프로토콜은 proactive 기법을 사용하는 DSDV(destination-sequenced distance vector)와 OLSR(optimized link state routing)기법과 reactive 기법을 사용하는 AODV(ad-hoc on-demand distance vector)와 DSR(dynamic source routing) 라우팅 프로토콜이다. 성능평가 척도는 시스템처리량과 패킷 전달 비율을 사용하였으며, 주어진 정사각형 모양의 통신영역 내에서 가변 개수의 통신노드들이 상호 독립적으로 이동할 경우 네 가지 라우팅 프로토콜의 성능을 평가하여 상호 비교하였다. 성능평가 결과에 따르면 AODV 라우팅 프로토콜의 성능이 전반적으로 우수함을 확인할 수 있었다.

• 대한기계학회논문집B
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• 제41권2호
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• pp.135-143
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• 2017

밀폐된 공간내의 공조 문제에 있어서 실내의 기류 및 온도 특성을 전산유체역학기법을 통해 쉽게 예측할 수 있는 맞춤형 시뮬레이터를 개발하였다. 본 시스템에서는 사용자가 직접 해석 대상 평면도를 입력하고 적절한 경계조건을 설정하면 전산유동해석을 위한 계산 격자가 자동으로 생성되고 유한체적법으로 이산화된 공개 전산유체코드를 통해 주어진 공간내의 열유체 해석 결과를 얻게 된다. 초기 실내 평면도면 입력부터 경계조건 설정, 전산유동해석 결과까지 하나의 사용자 인터페이스 상에서 작업할 수 있으며 격자생성과 유동해석 알고리듬은 공개 라이브러리를 사용하여 구현하였다. 간단한 실험 데이터를 통해 해석결과를 검증하였으며 실제 실내 공조에 대한 기류해석을 통해 유동의 경향성을 파악할 수 있는 맞춤형 유동전산모사 시스템을 구성하였다.

• Journal of Electrical Engineering and Technology
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• 제9권3호
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• pp.1104-1111
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• 2014

The digital substations are being built based on the IEC 61850 network. The cooperation and protection of power system are becoming more intelligent and reliable in the environment of digital substation. This paper proposes a novel method to prevent the malfunction caused by the Transformer Magnetizing Inrush Current(TMIC) using the IEC 61850 based data sharing between the IEDs. To protect a main transformer, the current differential protection(87T) and over-current protection(50/51) are used generally. The 87T IED applies to the second harmonic blocking method to prevent the malfunction caused by the TMIC. However, the 50/51 IED may malfunction caused by the TMIC. To solve that problem, the proposed method uses a GOOSE inter-lock signal between two IEDs. The 87T IED transmits a blocking GOOSE signal to the 50/51 IED, when the TMIC is detected. The proposed method can make a cooperation of digital substation protection system more intelligent. To verify the performance of proposed method, this paper performs the real time test using the RTDS (Real Time Digital Simulator) test-bed. Using the RTDS, the power system transients are simulated, and the TMIC is generated. The performance of proposed method is verified in real-time using that actual current signals. The reaction of simulated power system responding to the operation of IEDs can be also confirmed.

• International Journal of Computer Science & Network Security
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• 제21권2호
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• pp.110-119
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• 2021

The Coronavirus or COVID-19 is contagiousness virus that infected almost every single part of the world. This pandemic forced a major country did lockdown and stay at a home policy to reduce virus spread and the number of victims. Interactions between humans and robots form a popular subject of research worldwide. In medical robotics, the primary challenge is to implement natural interactions between robots and human users. Human communication consists of dynamic processes that involve joint attention and attracting each other. Coordinated care involves sharing among agents of behaviours, events, interests, and contexts in the world from time to time. The robotics arm is an expensive and complicated system because robot simulators are widely used instead of for rehabilitation purposes in medicine. Interaction in natural ways is necessary for disabled persons to work with the robot simulator. This article proposes a low-cost rehabilitation system by building an arm gesture tracking system based on a depth camera that can capture and interpret human gestures and use them as interactive commands for a robot simulator to perform specific tasks on the 3D block. The results show that the proposed system can help patients control the rotation and movement of the 3D arm using their hands. The pilot testing with healthy subjects yielded encouraging results. They could synchronize their actions with a 3D robotic arm to perform several repetitive tasks and exerting 19920 J of energy (kg.m².S^-2). The average of consumed energy mentioned before is in medium scale. Therefore, we relate this energy with rehabilitation performance as an initial stage and can be improved further with extra repetitive exercise to speed up the recovery process.