• 한국정밀공학회지
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• 제27권1호
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• pp.49-57
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• 2010

This paper describes the design, construction, and fundamental testing of a precision rotational device that utilizes piezoelectric elements as a source of driving force and impact drive mechanism as a driving principle. A novel device structure is designed and the numerical simulations about the static displacement, stress distribution, and mode shape of the designed structure are performed. A fabricated rotational device has been rotated successfully by applying saw-shaped voltages to the piezoelectric elements. The one-step rotational angle was $0.44{\times}10^{-3}$ rad at the applied voltages of 80V. The angular velocities of the device were revealed to be increased as the driving frequency and voltage were respectively increased and the preload was decreased. The device has a feature that it can be translated as well as rotated. An experimental result shows that the device was translated by ${\pm}4.56{\mu}m$ maximum when the 120V sinusoidal voltages with a phase difference of $180^{\circ}$ were respectively supplied to two piezoelectric elements.

• 자동차안전학회지
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• 제15권3호
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• pp.59-65
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• 2023

As advanced driving assistance system (ADAS) and autonomous driving performance continue to improve, existing crash accidents and crash types are changing. Accordingly, the collision angle and the seating posture of the occupant are changed. It is necessary to study how the occupant injury mechanism changes according to these different crash types. In this regard, a representative crash test mode was derived when the automatic emergency braking system (AEB), one of the autonomous driving performance, was applied to the representative car-to-car crash scenario in Korea. The derived crash test mode was used to analyse the mechanisms of collision injuries according to both impact angle and the occupant seating posture (reclined seat-back angle). The results obtained through this study can be utilized as reference data for the development of new crash evaluation methods and improvements in crash restraint systems for enhancing crash safety.

• 천문학회보
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• 제44권2호
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• pp.59.1-59.1
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• 2019

I will compute the rate of merger events in the multi-scale initial conditions to forecast special events driving the anisotropic assembly of dark matter halos and understand their impact on galaxy formation. Beyond halo mergers, I consider all sets of mergers, including wall and lament mergers, as they impact the geometry of galactic infall. Their one- and two-points statistics are computed as a function of cosmic time. I establish the relation between merger rates and connectivity, which is then used to assess the impact the large scale structures on assembly bias. The anisotropy of the cosmic web, as encoded in this theory, is a signi cant ingredient to describe jointly the physics and dynamics of galaxies in their environment, e.g. in the context of intrinsic alignments or morphological diversity.

• 한국지반공학회지:지반
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• 제11권4호
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• pp.25-36
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• 1995

내관과 외관이 분리된, 특별하게 제작된 모형 개단 말뚝을 상이한 방법으로 압력토조내에 설치하여 정적 압축 재하 실험을 실시하였다. 개단 말뚝 각 지지부에서의 지지력을 분리.측정하여 개단 말뚝의 지지 메카니즘과 관내토의 폐색 거동 특성을 고찰하였다. 상대밀도 49%의 모형 지반에 타격 관입된 말뚝의 관내토폐색력은 관입도중 20%정도 발휘되고 압축재하시에 대부분이 발휘되며, 토조에 작용된 구속 압력은 관내토 폐색에 크게 영향을 미치지 않았다. 그러나, 진동 관입된 말뚝의 관내토 폐색력은 관입도중에는 전혀 발생하지 않으며, 압축재하시에 약하게 형성되고, 타격 관입말뚝의 그것의 0.5~0.7배 정도가 발휘되는데 토조에 작용된 구속 압력은 관내토 폐색에 크게 영향을 미쳤다. 단위 관내토 폐색력은 극한 상태에서 최대값에 도달하지 않았다. 즉, 극한 상태에서 관내토는 파괴상태에 도달되지 않았다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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• pp.11-19
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• 2004

When pile foundation constructed by driving method, it is desirable to perform monitoring and estimation of pile drivability and bearing capacity using some suitable tools. Dynamic Pile Monitoring yields information regarding the hammer, driving system, and pile and soil behaviour that can be used to confirm the assumptions of wave equation analysis. Dynamic Pile Monitoring is performed with the Pile Driving Analyser. The Pile Driving Analyser (PDA) uses wave propagation theory to compute numerous variables that fully describe the condition of the hammer-pile-soil system in real time, following each hammer impact. This approach allows immediate field verification of hammer performance, driving efficiency, and an estimate of pile capacity. The PDA has been used widely as a most effective control method of pile installations. A set of PDA test was performed at the site of Donghea-1 Gas Platform Jacket which is located east of Ulsan. The drilling core sediments of location of jacket subsoil are composed of mud and sand, silt. In this case study, the results of PDA test which was applied to measurement and estimation of large diameter open ended steel pipe pile driven by underwater hydraulic hammer, MHU-800S, at the marine sediments were summarized.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2009년도 춘계학술대회 논문집
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• pp.147-148
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• 2009

• 한국정보통신학회논문지
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• 제10권4호
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• pp.700-705
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• 2006

최근 GIS 시스템은 2차원에서 3차원으로 변환되고 있다. 3차원 GIS를 이용한 관련 분야가 급성장함에 따라 공공분야, 국방분야를 비롯한 일반산업에 이르기까지 점차적으로 다양화 되고 있다. 본 논문은 3차원 GIS기법으로 환경영향평가를 고려한 곡선부의 시거 안정성에 대한 분석가능성을 검토하였다. 시거는 입체성격을 지닌 도로 위를 입체성격의 운전자 시선과의 관계를 통해 결정하기 때문에 평면과 종단을 동시에 고려해야만 정확한 산정이 가능하다. 연구 결과 도로에 대한 설계속도 80km/h와 주행속도 60-120km/h까지 속도를 고려한 주행 시뮬레이션으로 시거 분석뿐만 아니라 기본적인 경관 주위 구조물 및 교량과의 조화, 안정성 평가뿐만 아니라 환경영향 평가가 가능할 것으로 보인다.

• 한국안전학회지
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• 제24권4호
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• pp.104-110
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• 2009

In this driving simulation study, the impairing effects of various types of electronic devices usage(i. e., destination search by using in-vehicle navigation system, TV watching and dialing cellular phone) during driving on front-to-rear-end collision avoidance were investigated. Percentage of collisions, driving speeds when the drivers collided, and initial reaction time for collision avoidance were analyzed and compared as the dependent measures. The results indicated that (1) any types of electronic devices usage during driving induced more serious collision-related impairment than control condition where no additional task was required, and (2) in general, destination search task appeared to impair drivers collision avoidance performance more than the other task requirements in terms of percentage of collisions and initial reaction time for collision avoidance, but TV watching induced most serious collision impact. These results suggested that any types of electronic device usage could distract drivers attention from the primary task of driving, and be resulted in serious outcome in potentially risky situation of front-to-rear-end collision. In particular, mandatory use of eye-hand coordination and receiving feedback seemed to one of essential factor leading the drivers visual attentional distraction.

• 한국인터넷방송통신학회논문지
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• 제10권6호
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• pp.119-123
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• 2010

마크-젠더 변조기와 광 간섭계를 이용한 10Gb/s 광 듀오바이너리 송신기의 전송 성능을 고찰하였다. 전송 거리를 증가시키기 위해서 전송 시스템이 받는 영향을 변조기의 구동 전압비와 광 간섭계의 시간 지연 관점에서 컴퓨터 모의실험을 통하여 이론적 분석을 하였다. 구동 전압비를 줄이고 부분 비트 시간 지연을 최적화하여 보다 향상된 전송 성능을 확인하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.788-792
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• 2004

In this study, the performance of the DPRMs is evaluated and the measurement precision for the pile driving is presented. The DPRMs is a visual-measurement system for the pile rebound and the penetration movement using a high speed line-scan camera. But the measurement errors of the DPRMs are caused by the strong impact for the pile driving. Therefore, the DPRMs should guarantee its measurement values for the pile driving. For this reason, the performance of the DPRMs by the vibration signal analysis is studied. It is found from this study that the measurement values of the DPRMs are reliable.