• 로봇학회논문지
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• 제18권2호
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• pp.197-202
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• 2023

This paper studies the method to extend the sensing range of a fiducial maker using a tilt camera. In the system that uses a fiducial marker to estimate their position on a map, the sensing range of the marker is an important issue. Although there are markers around, a robot with a fixed camera often misses nearby markers in the case that the viewing angle of the camera does not cover the sensing range of the marker. If the robot adjusts the viewing angle of a camera by adjusting the position information of the markers, this problem will be solved. The contribution of this paper is as follows. 1) Structural considerations for the tilting module of cameras attached to robots. 2) Tilting module control method considering the position of a marker and a robot. 3) Finally, verification of the differences in the sensing range of markers between the proposed system and the previous system.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2016년도 전력전자학술대회 논문집
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• pp.75-76
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• 2016

This paper proposes a power factor correction circuit with a high efficiency over a wide load range characteristics for a communication power supply. And the characteristic verification is applied to produce a design of prototype. Power factor correction circuit can reduce conduction losses by applying Bridgeless Boost Converter for efficiency. Over a wide load range to maintain the efficient, the control method of a PWM controller is divided by two sections according to the load area. In the low-load region, it was reduced switching losses by applying the critical conduction mode control method. On the other hand, in the heavy-load area, the hysteresis current control method is used to maintain the high efficiency over a wide load range by limiting the peak noise of the inductor.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 봄 학술발표회 논문집
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• pp.183-190
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• 2000

Effective range of Hydraulic Hammer Compaction was studied by numerical analysis instead of empirical method. Numerical analyses were carried out with commercial FEM code, ABAQUS, and verified by comparing the numerical results with field tests of Hydraulic Hammer Compaction. Most of material properties were evaluated by data from laboratory and in-situ tests. Vertical effective range was estimated by distribution curve of plastic strain energy dissipated through soil layers under dynamic load and these results were in good agreement with field tests. Based on verification, the effects of governing properties of Hydraulic Hammer Compaction such as number of hit can be determined by numerical analyses. In addition, vertical effective range can also be determined by Menard's empirical equation using the external work at converging time of plastic strain energy in numerical analysis. This implies that the minimum energy of Hydraulic Hammer Compaction for improvement can be determined by Menard's equation.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1990년도 한국자동제어학술회의논문집(국제학술편); KOEX, Seoul; 26-27 Oct. 1990
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• pp.1021-1026
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• 1990

Accuracy improvement of a self-mixing semiconductor laser range finder is predicted by simulation, in which the laser modulation current is reshaped to give an ideal triangular waveform of the optical frequency change. The maximum range measurement error of less than 0.1% in a wide range of O.1m to 1m is expected by the reshaping of the modulation current. Experimental verification of the effect of current reshaping on the linearization of the derivative of the optical frequency change curve is given.

• 로봇학회논문지
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• 제11권3호
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• pp.140-145
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• 2016

In this paper, we fabricate arrayed-type flexible capacitive touch sensor using liquid metal (LM) droplets (4 mm spatial resolution). Poly-4-vinylphenol (PVP) layer is used as a dielectric layer on the electrode patterned Polyethylene naphthalate (PEN) film. Bonding tests between hydroxyl group (-OH) on the PVP film and polydimethylsiloxane (PDMS) are conducted in a various $O_2$ plasma treatment conditions. Through the tests, we can confirm that non-$O_2$ plasma treated PVP layer and $O_2$ plasma treated PDMS can make a chemical bond. To measure dynamic range of the device, one-cell experiments are conducted and we confirmed that the fabricated device has a large dynamic range (~60 pF).

• 조명전기설비학회논문지
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• 제22권3호
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• pp.66-73
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• 2008

This paper presents a position sensorless control system of SRM over wide speed range. Due to the doubly salient structure of the SRM, the phase inductance varies along with the rotor position. Most of the sensorless control techniques are based on the fact that the magnetic status of the SRM is a function of the angular rotor position. The rotor position estimation of the SRM is somewhat difficult because of its highly nonlinear magnetizing characteristics. In order to estimate more accurate rotor position over wide speed range, Neural Network is used for this highly nonlinear function approximation. Magnetizing data patterns of the prototype 1-hp SRM are obtained from locked rotor test, and used for the Neural Network training data set. Through measurement of the flux-linkage and phase currents, rotor position is able to estimate from current-flux-rotor position lookup table which is constructed from trained Neural Network. Experimental results for a 1-hp SRM over 16:1 speed range are presented for the verification of the proposed sensorless control algorithm.

• 전자공학회논문지
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• 제50권3호
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• pp.23-32
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• 2013

이동 통신 기술이 발달함에 따라 통신 기기간의 메시지 교환이 가능한 서비스가 생겨나고, 그 사용 횟수가 폭발적으로 늘고 있다. 기기간의 통신을 위해서는 통신 기기간의 서비스 구성원이라는 인증이 선행되어야 한다. 하지만, 기존 인증 기술은 Trusted party와 같은 제 삼자와의 통신이 수반되는데, 이로 인하여 대역폭이 낭비되거나, 기지국 범위 밖의 이동 통신 기기는 기기간 통신에 참여할 수 없다는 문제점이 발생할 수 있다. 본 논문에서는 제 삼자의 개입이 없는 새로운 이동 통신 기기간 인증 기법을 소개할 것이다. 제안된 기술에 대하여, 서비스의 가입 여부 및 서비스 가입 시간을 모두 검증해야 하므로, 이를 가능하게 하는 새로운 영지식 증명 기법을 개발하여 적용할 것이다. 또한, 이 영지식 증명 기법은 인증정보를 암호화된 그대로 검증하기 때문에 증명 하고자 하는 기기의 프라이버시가 보장이 되며, 질의-응답 방식을 사용하기 때문에 다른 기기의 인증 메시지를 재사용하는 공격으로부터 보호할 수 있다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2008년도 정기 학술대회
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• pp.495-498
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• 2008

In this paper applicable range of U-Channel Bridge (UCB) that has recently been introduced as a new bridge type was studied. For structural analysis models used with the frame and plate elements was proposed, and verification of the models were performed. Using these structural models structural analysis of models with span length of 20m-45m and inner width of 5m-13m were performed. As a result for U-shape sections were applicable in the range of 20m span and 35m span, slab was applicable in the range of 5m inner width and 12m inner width. To increase applicable range of UCB H-shape sections and slab with rib were proposed. As a result UCB were applicable in the range of 20m span and 45m span, in the range of 5m inner width and 13m inner width.

• 한국항공우주학회지
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• 제39권2호
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• pp.153-161
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• 2011

한국항공우주연구원에서는 GBAS 기준국의 무결성 감시 알고리즘 개발을 위한 데이터 제공 및 시험을 위하여 무결성 감시 테스트베드를 구축하였다. 개발된 알고리즘의 정확한 구현 및 시험을 위해서는 기반이 되는 시설 및 소프트웨어의 기본 기능이 국제 표준에 부합하게 구현되어 있어야 하므로, 본 논문에서는 현재 구축된 테스트베드의 GBAS 기준국으로서의 기본 기능에 대한 검증시험을 수행한다. 이를 위해 국제적으로 신뢰받고 있는 프로그램인 PEGASUS와의 비교를 통하여 GBAS 보정 정보의 타당성을 확인하였으며, 이를 적용한 사용자 측면에서의 거리 영역 및 위치 영역에서의 데이터 분석을 통하여 시스템의 무결성 및 가용성 성능을 확인하였다.

• Nuclear Engineering and Technology
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• 제51권4호
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• pp.968-976
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• 2019

This paper presents a number of verification case studies for a recently developed sensitivity/uncertainty code package. The code package, ROMUSE (Reduced Order Modeling based Uncertainty/Sensitivity Estimator) is an effort to provide an analysis tool to be used in conjunction with reactor core simulators, in particular the Virtual Environment for Reactor Applications (VERA) core simulator. ROMUSE has been written in C++ and is currently capable of performing various types of parameter perturbations and associated sensitivity analysis, uncertainty quantification, surrogate model construction and subspace analysis. The current version 2.0 has the capability to interface with the Design Analysis Kit for Optimization and Terascale Applications (DAKOTA) code, which gives ROMUSE access to the various algorithms implemented within DAKOTA, most importantly model calibration. The verification study is performed via two basic problems and two reactor physics models. The first problem is used to verify the ROMUSE single physics gradient-based range finding algorithm capability using an abstract quadratic model. The second problem is the Brusselator problem, which is a coupled problem representative of multi-physics problems. This problem is used to test the capability of constructing surrogates via ROMUSE-DAKOTA. Finally, light water reactor pin cell and sodium-cooled fast reactor fuel assembly problems are simulated via SCALE 6.1 to test ROMUSE capability for uncertainty quantification and sensitivity analysis purposes.