• Advances in concrete construction
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• 제16권2호
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• pp.79-89
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• 2023

The occurrence of unexpected horizontal offset in the instrument or target will result in accumulated horizontal deviation in segment alignment with traditional short-line match method. A geometry control method, the four-point method, is developed for precast segmental bridges to avoid the influences of unexpected horizontal offset. The concept of the four-point method is elucidated. Furthermore, the detailed instruments and instructions are introduced. Finally, the four-point method is validated through a practical engineering application. According to the survey data, after short-line match precast construction, the vertical deviations on both sides vary between -5 mm and 5 mm in almost all segments, and the horizontal deviations vary between -4 mm and 4 mm in all segments. Without on-site adjustment, the maximum vertical and horizontal closure gaps are 12.3 and 26.1 mm, respectively. The four-point method is suggested to alleviate the issues associated with relatively poor soil conditions in casting yard.

• 한국CDE학회논문집
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• 제6권1호
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• pp.9-16
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• 2001

Electrical discharge machining(EDM) is an important process of machining the injection mold. This paper includes efficient design processes of electrodes for EDM. Based on the solid modeler, electrodes can be created by boolean and offset operations with core/cavity models. The built-in offset operations of the solid modeler may occur unexpected results due to the limitations of the solid modeler. We proposed the multi-step and moving-face offset processes in order to apply the EDM clearances. The proposed design processes are implemented with Unigraphics Vl5 API functions and C language and tested on Windows NT 4.0.

• 한국자동차공학회논문집
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• 제20권3호
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• pp.113-118
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• 2012

Collision detection plays a key role in collision mitigation system. The malfunction of the collision mitigation system can result in another dangerous situation or unexpected feeling to driver and passenger. To prevent this situation, the collision time, offset, and collision decision should be determined from the appropriate collision detection algorithm. This study focuses on a method to determine the time to collision (TTC) and frontal offset (FO) between the ego vehicle and the target object. The path prediction method using the ego vehicle information is proposed to improve the accuracy of TTC and FO. The path prediction method utilizes the ego vehicle motion data for better prediction performance. The proposed algorithm is developed based on laser scanner. The performance of the proposed detection algorithm is validated in simulations and experiments.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2002년도 추계학술대회 논문집(II)
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• pp.1086-1093
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• 2002

In Korea mid chord offset method has been used to measure the track irregularities. This method has been also used all over the world widely because of its accessibility and the operational excellence for measured data. But it has been pointed out recently that track irregularities reconstructed from measured data have unexpected noise in the high frequency area as the defect of this way. This study shows the cause of noise which occurs during reconstructing process and mentions the solutions briefly.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2006년도 추계학술대회 특별세미나 특별세션
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• pp.189-197
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• 2006

Maglev using EMS becomes unstable by unexpected big air-gap disturbance. The main causes of the unexpected air-gap disturbance are step-wise rail joint and large distance between rail splices. For the stable operation of the Maglev, the conventional system uses the threshold method, which selects one gap sensor among two gap sensors installed on the magnet to read the gap between magnet and guide rail. But the threshold method with a wide bandwidth makes the discontinuous air-gap signal at the rail joints because of the offset in air gap sensors and/or the step-wise rail joins. Further more, in the case of the one with a narrow bend-width, it makes Maglev system unstable because of frequent alternation. In this paper, a new method using fuzzy rule to reduce air-gap disturbances proposed to improve the stability of Maglev system. It treats the air-gap signal from dual gap sensors effectively to make continuous signal without air gap disturbance. Simulation and experiment results proved that the proposed scheme was effective to reduce air-gap disturbance from dual gap sensors in rail joints.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 B
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• pp.1071-1072
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• 2006

Maglev using EMS becomes unstable by unexpected big air-gap disturbance. The main causes of the unexpected air-gap disturbance are step-wise rail joint and large distance between rail splices. For the stable operation of the Maglev, the conventional system uses the threshold method, which selects one gap sensor among two gap sensors installed on the magnet to read the gap between magnet and guide rail. But the threshold method with a wide bandwidth makes the discontinuous air-gap signal at the rail joints because of the offset in air gap sensors and/or the step-wise rail joins. Further more, in the case of the one with a narrow bend-width, it makes Maglev system unstable because of frequent alternation. In this paper, a new method using fuzzy rule to reduce air-gap disturbances proposed to improve the stability of Maglev system. It treats the air-gap signal from dual gap sensors effectively to make continuous signal without air gap disturbance. Simulation and experiment results proved that the proposed scheme was effective to reduce air-gap disturbance from dual gap sensors in rail joints.

• 한국항공우주학회지
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• 제39권2호
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• pp.162-169
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• 2011

현대의 고성능 전투기는 공력성능 및 조종성능의 향상을 위하여 대부분 세로축 방향으로 항공기를 불안정하게 설계하는 정안정성 완화 개념을 채택하고 있다. 항공기는 비행제어법칙에 필요한 피치, 롤, 요우각속도, 수직가속도와 같은 항공기 상태정보를 각속도(RSA: Rate Sensor Assembly)와 가속도센서(ASA: Acceleration Sensor Assembly)로부터 획득한다. 항공기에 적용되는 센서는 항공기의 안전을 보장하는 최소한의 허용 가능한 측정 오차를 갖지만, 잡음, 오프셋 등과 같은 허용 범위내의 오차로 인하여 원하지 않는 항공기 운동을 발생시킨다. 비행시험 결과, ASA의 허용 범위내의 측정 오차는 1g 수평비행시에 원하지 않는 기수 숙임 현상을 일으켰다. 본 논문에서는 이러한 오차로 인하여 발생하는 기수 숙임 현상을 개선하기 위해 1g 수평비행 조건에 피치자세각 궤환을 세로축 제어법칙에 적용하였다. 비행시험 결과, 피차자세각 궤환은 1g 수평 비행 시에 기수 숙임현상을 제거하고 항공기의 기본적인 안정성에는 영향을 미치지 않는다는 것을 확인할 수 있었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.310-312
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• 2006

Maglev using EMS becomes unstable by unexpected big air-gap disturbance. The main causes of the unexpected air-gap disturbance are step-wise rail joint and large distance between rail splices. For the stable operation of the Maglev, the conventional system uses the threshold method, which selects one gap sensor among two gap sensors installed on the magnet to read the gap between magnet and guide rail. But the threshold method with a wide bandwidth makes the discontinuous air-gap signal at the rail joints because of the offset in air gap sensors and/or the step-wise rail joins. Further more, in the case of the one with a narrow bend-width, it makes Maglev system unstable because of frequent alternation. In this paper, a new method using fuzzy rule to reduce air-gap disturbances proposed to improve the stability of Maglev system. It treats the air-gap signal from dual gap sensors effectively to make continuous signal without air gap disturbance. Simulation and experiment results proved that the proposed scheme was effective to reduce air-gap disturbance from dual gap sensors in rail joints.

• 한국광학회지
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• 제25권1호
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• pp.29-37
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• 2014

두 개의 회전하는 사분파장판으로 구성된 타원편광분석기의 체계적인 오차를 보정하는 방법을 연구하고 이를 실증하였다. 두개의 사분파장판으로 구성된 타원편광분석기의 5가지 오차(두 개의 회전 사분파장판들의 회전 시작 각도 오차 및 상 지연 값의 오차, 그리고 편광 분석기의 정렬 각도 오차)를 근사 과정 없이 계산하기 위하여 시료가 없이 타원편광신호를 얻고 이로부터 25개의 퓨리에 성분을 추출하였다. 25개의 퓨리에 계수에서 관련된 11개의 성분만 이용하여 상호 비선형적으로 얽혀 있는 5개의 값을 비선형 최적화 방법으로 구할 수 있었다. 오차 보정 결과 회전광소자들의 정렬 각도 오차(${\epsilon}_3$, ${\epsilon}_4$, ${\epsilon}_5$)가 위상지연 오차(${\epsilon}_1$, ${\epsilon}_2$)보다 더 중요하며, 모든 오차에서 0.05 rad 이하의 정밀도를 지니면 충분히 그 오차를 보정할 수 있다는 것을 확인할 수 있었다. 최종적으로는 이렇게 구한 광학계의 초기 정렬 오차 값을 미지의 광학 부품에 적용하여 미지의 광학부품의 위상 지연의 양과 빠른 축을 알 수 있었다. 오차 보정 검증을 위하여 미지의 샘플로 반파장판을 이용하였으며, 반파장판의 위상 지연 양과 빠른 축을 찾을 수 있었다.