• 접착 및 계면
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• 제7권4호
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• pp.10-12
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• 2006

The successful use of adhesively bonded parts depends on the defect-free bond of the components. Therefore it is necessary to detect relevant faults and defects in an early state of the production. A 100% test should be pursued, but especially at complicated structures the detection of defects is not easy. Possible testing methods, which show a high potential for the NDT of adhesively bonded parts, are thermography based NDT methods. At present mainly two different procedures of active thermography are being used: Pulse and Lock-In Thermography. With pulse thermography the examined material is warmed up with a short energy pulse (light, eddy current or ultrasonic pulse) and the heat response is recorded after a certain time. The result is an infrared image which indicates material defects in different depths. This paper presents a variety of images showing the capability of Lock-In Thermography to image subsurface defects. Several examples of adhesives joints qualify the ultrasonic Lock-In-Thermography for the in-process quality control for adhesive bonded components.

• 한국지능시스템학회논문지
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• 제27권1호
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• pp.65-71
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• 2017

기존 사물인터넷은 보안성이 취약하기 때문에 정보유출로 인한 재산피해가 일어날 수 있다. 특히 사물인터넷을 기반으로 구축된 스마트 도어락 시스템은 그 피해가 더욱 크게 발생될 수 있다. 본 논문에서는 이러한 문제점을 해결하기 위해 센서에서 발생된 데이터를 조건에 따라 분류하여 Google Cloud Message(GCM)을 통해 사용자의 스마트폰으로 알람 메시지를 전송하였다. 스마트폰 애플리케이션을 통해 실시간으로 영상을 확인할 수 있도록 하였고, TCP/IP 프로토콜을 이용하여 도어락을 제어하였다. 또한 OTP-Based Matrix SEED 알고리즘을 도어락 시스템에 적용하여 보안성을 향상시켰다.

• 구강회복응용과학지
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• 제26권1호
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• pp.33-38
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• 2010

상악의 악성 종양에 대한 치료로서 상악골 절제술이 시행되며 필연적으로 이것은 환자 구개부에 결손부를 생성한다. 이로 인해 안모의 변형, 연하, 저작, 발음 등 다양한 문제가 발생할 수 있다. 상악골 절제술 후 이런 문제들을 극복하기 위해 외과적 재건 또는 보철적 치료가 치료 방법으로 선택될 수 있으나 대부분의 상악골 절제술 환자에서 구강악안면 재건의 방법으로 구개폐쇄장치가 더 선호된다. 본 증례는 Aramany 분류 II급에 해당하는 상악골 부분 절제술을 시행한 환자에게 구개폐쇄장치의 유지와 안정을 얻고 모든 기존의 금관수복물을 유지할 수 있는 swing-lock attachment를 사용하여 수복한 임상과정 및 결과에 관하여 보고하고자 한다.

• 대한기계학회논문집B
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• 제29권8호
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• pp.895-902
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• 2005

Lock-on characteristics of flow around a circular cylinder oscillating rotationally with a relatively high forcing frequency have been investigated experimentally. Dominant governing parameters are Reynolds number (Re), angular amplitude of oscillation (${\theta}_A$), and frequency ratio $F_R=f_f/f_n,\;where\;f_f$ is a forcing frequency and $f_n$ is a natural frequency of vortex shedding. Experiments were carried out under the conditions of $Re=4.14{\times}10^3,\;{\pi}/90{\leq}{\theta_A}{\leq}{\pi}/3,\;and\;F_R=1.0$. The effect of this active flow control technique on the lock-on flow characteristics of the cylinder wake was evaluated with wake velocity measurements and spectral analysis of hot-wire signals. The rotational oscillation modifies the flow structure of near wake significantly. The lock-on phenomenon always occurs at $F_R=1.0$, regardless of the angular amplitude ${\theta}_A$. In addition, when the angular amplitude is less than a certain value, the lock-on characteristics appear only at $F_R=1.0$,. The range of lock-on phenomena expands and vortex formation length is decreased, as the angular amplitude increases. The rotational oscillation create a small-scale vortex structure in the region just near the cylinder surface. At ${\theta}_A=60^{\circ}$, the drag coefficient was reduced about $43.7\%$ at maximum.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 추계학술대회 논문집 학회본부 D
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• pp.612-614
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• 2000

ABS(Anti-lock Braking System) is a device which prevents the lock-up of car wheels during emergency braking. It helps to maintain the steerability since the tire-road slip is controlled in an acceptable range. By maintaining the maximal frictional force during braking. ABS can reduce the braking distance. Recently, ABS is accepted as a standard equipment in vehicles, especially in commercial vehicles(bus and trucks). Commercial vehicles mostly use pneumatic pressure for braking. In this paper, ECU(Electronic Control Unit) for the anti-lock braking system of a commercial vehicle which is equipped with a full-air brake system and its control algorithms are presented.

• International Journal of Automotive Technology
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• 제6권1호
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• pp.37-44
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• 2005

The creation of automotive systems of active safety with intelligent functions needs the use of new control principles for the wheel and automobile. One of such directions is the pre-extreme control strategy. Its aim is the ensuring of wheel's work in pre-extreme, stable area of tire grip wheel slip dependence. The simplest realization of pre-extreme control in automotive anti-lock brake systems consists in the threshold and gradient algorithms. A comparative analysis of these algorithms, which has been made on 'hardware in-the-loop' simulation results of the braking for bus with various anti-lock brake systems (ABS), indicated their high efficiency.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.357-360
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• 1997

This paper presents a new anti-lock brake system(ABS) using electro-rheological(ER) valve actuators for the wheel slip control. The hydraulic dynamic model of the automotive brake system is formulated by incorporating electric field-dependent Bingham properties of ER fluid obtained experimentally. The brake system designed by this hydraulic model is able to control wheel slip by controlling the intensity of electric field which tunes the braking torque. The control fields of the ER valve to command desired wheel slip are determined by a sliding mode controller. A comparison between the proposed brake system and the conventional brake system is made by providing with computer simulations of vehicle motions under ABS performance requirement condition.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.523-530
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• 2005

This paper addresses sliding mode control (SMC) of the anti-lock braking system (ABS) with a compensator of model uncertainties such as vehicle parameter variation, unmodeled dynamics, and external disturbances. A sliding mode controller (SMC) is designed with a nominal vehicle model to achieve a desired wheel slip ratio. A disturbance observer (DOB) is introduced to compensate the model uncertainties and is designed with a transfer function of a hydraulic brake dynamics. Through simulations on the model uncertainties, it is verified that the sliding mode control with the DOB can give the simulation results better than the sliding mode control without the DOB.

• 한국정밀공학회지
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• 제23권4호
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• pp.44-51
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• 2006

This paper addresses sliding mode control of the anti-lock braking system (ABS) with a disturbance observer for model uncertainties such as vehicle parameter variation, un-modeled dynamics, and external disturbances. By using a nominal vehicle model, a sliding mode controller is designed to achieve a desired wheel slip ratio for ABS control. To compensate the model uncertainties, a disturbance observer is introduced with the help of a transfer function of a hydraulic brake dynamics. A proposed sliding mode controller with a disturbance observer is evaluated through simulations for model uncertainties. The simulation results show that the disturbance observer can enhance performances of sliding mode control for ABS.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.1771-1772
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• 2008

전동기나 발전기와 같은 회전기기에 주로 발생하는 주기외란은 시스템 성능을 저하시키는 특성으로서 고급제어시스템 구현을 위하여 반드시 보상되어야 한다. 본 논문은 신호처리기법의 일종인 Lock In Amplifier(LIA) 알고리즘 기반 외란보상 제어기를 제안한다. 제안하는 제어규칙은 공칭제어기와 보조제어기로 구성되며 전자는 외란을 고려하지 않은 시스템 모델에 대하여 상태궤환 제어기법으로 산출되며 후자는 LIA 기법을 이용하여 외란특성을 실시간으로 추정하여 연산되어진다. 제안하는 제어시스템은 기존의 결정적 외란으로부터 발생되었던 실시간 제어오차를 월등히 개선하는 장점을 가지고 있다. 실시간 전동기 제어장치를 통해 제안하는 알고리즘의 성능의 우수성 및 타당성을 검증한다.