• 한국농공학회지
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• 제40권1호
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• pp.106-117
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• 1998

The nature of stress-path dependency, the principle that governs deformations in granular soil, and the use of Lade's double work-hardening model for predicting soil response for a variety of stress-paths have been investigated, and are examined The test results and the analyses presented show that under some conditions granular soils exhibit stress-path dependent behavior. For stress-paths involving unloading or reloading, the stress-path with the higher average stress level produces the larger strains, whereas all stress-paths having the same intial states of stress, and involving only primary loading conditions, produce strains of similar magnitudes. Experimental evidence indicates that the stress- path dependent response obtained from the double work-hardening model is also observed for real soils. It is concluded that the influence of stress history on the friction angle is negligible and the strains increment direction is uniquely determined from the state of stress but is not perpendicular to the yield surface. The strains calculated from Lade's double work-hardening model are in reasonable agreement with those measured.

• 조명전기설비학회논문지
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• 제24권10호
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• pp.163-173
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• 2010

In multi-mobile robot environment, path planning and collision avoidance are important issue to perform a given task collaboratively and cooperatively. The proposed approach is based on a potential field method and fuzzy logic system. For a global path planner, potential field method is employed to select proper path of a corresponding robot and fuzzy logic system is utilized to avoid collisions with static or dynamic obstacles around the robot. This process is continued until the corresponding target of each robot is reached. To test this method, several simulation-based experimental results are given. The results show that the path planning and collision avoidance strategies are effective and useful for multi-mobile robot systems.

• 한국군사과학기술학회지
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• 제16권6호
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• pp.726-732
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• 2013

It is required for UGV(Unmanned Ground Vehicle) to have a LPP(Local Path Plan) component which generate a local path via the center of road by analyzing binary map to travel autonomously unpaved road in rough environment. In this paper, we present the method of boundary estimation for unpaved road and a local path planning method based on RANGER algorithm using the estimated boundary. In specially, the paper presents an approach to estimate road boundary and the selection method of candidate path to minimize the problem of zigzag driving based on Bayesian probability reasoning. Field test is conducted with scenarios in rough environment in which bush, tree and unpaved road are included and the performance of proposed method is validated.

• 한국전문물리치료학회지
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• 제23권3호
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• pp.40-47
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• 2016

Background: Assessments of Sit-to-Stand (STS) and gait functions are essential procedures in evaluating level of independence for the patients after stroke. In a previous study, we developed the software to analyze center of pressure (COP) in standing position on Wii Balance Board (WBB). Objects: This purpose of this study is to measure test-retest reliability of ground reaction forces, COP and time using WBB on STS and gait in healthy adults. Methods: Fifteen healthy participants performed three trials of STS and gait on WBB. The time (s), vertical peak (%) and COP path-length (cm) were measured on both tasks. Additionally, counter (%), different peak (%), symmetry ratio, COP x-range and COP y-range were analyzed on STS, 1st peak (%), 2nd peak (%) of weight were analyzed on gait. Intra-class correlation coefficient (ICC), standard error measurement (SEM) and smallest real difference (SRD) were analyzed for test-retest reliability. Results: ICC of all variables except COP path-length appeared to .676~.946 on STS, and to .723~.901 on gait. SEM and SRD of all variables excepting COP path-length appeared .227~8.886, .033~24.575 on STS. SEM and SRD excepting COP path-length appeared about .019~3.933, .054~11.879 on gait. Conclusion: WBB is not only cheaper than force plate, but also easier to use clinically. WBB is considered as an adequate equipment for measuring changes of weight bearing during balance, STS and gait test which are normally used for functional assessment in patients with neurological problems and elderly. The further study is needed concurrent validity on neurological patients, elderly patients using force plate and WBB.

• 로봇학회논문지
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• 제8권1호
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• pp.43-50
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• 2013

$A^*$ algorithm is a global path generation algorithm, and typically create a path using only the distance information. Therefore along the path, a moving vehicle is usually not be considered by driving characteristics. Deceleration at the corner is one of the driving characteristics of the vehicle. In this paper, considering this characteristic, a new evaluation function based path algorithm is proposed to decrease the number of driving path corner, in order to reduce the driving cost, such as driving time, fuel consumption and so on. Also the potential field method is applied for driving of UGV, which is robust against static and dynamic obstacle environment during following the generated path of the mobile robot under. The driving time and path following test was occurred by experiments based on a pseudo UGV, mobile robot in downscaled UGV's maximum and driving speed in corner. The experiment results were confirmed that the driving time by the proposed algorithm was decreased comparing with the results from $A^*$ algorithm.

• 한국군사과학기술학회지
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• 제14권3호
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• pp.327-334
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• 2011

It is necessary that UGV(Unmanned Ground Vehicle) should generate a real-time travesability index map by analyzing raw terrain information to travel autonomously tough terrain which has various slope and roughness values. In this paper, we propose a local path planning method, $MA^*$(Modified $A^*$) algorithm, using DVGM (Directional Velocity Grid Map) for unmanned ground vehicle. We also present a path optimization algorithm and a path smoothing algorithm which regenerate a pre-planned local path by $MA^*$ algorithm into the reasonable local path considering the mobility of UGV. Field test is conducted with UGV in order to verify the performance of local path planning method using DVGM. The local path planned by $MA^*$ is compared with the result of $A^*$ to verify the safety and optimality of proposed algorithm.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.2172_2173
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• 2009

UL 1699 규정에서 제시된 다양한 시험방법을 분류하고, 시험방법 중의 하나인 carbonized path arc clearing time test의 시험설비를 구축하였으며, 시험방법 및 절차에 대해 소개하였다. 또한 국내에서 개발되어진 cord 타입 AFCI를 대상으로 시험을 실시하였으며 시험결과 국내에서 개발되어진 cord 타입의 AFCI는 부하전류 3[A]에서도 아크고장을 검출하며 모든 시험전류에서 적합하게 아크를 차단하는 것을 알 수 있었다.

• 한국도로학회논문집
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• 제16권3호
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• pp.119-129
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• 2014

PURPOSES : This investigational survey is to observe a proper spatial aggregation method for path travel time estimation using the hi-pass DSRC system. METHODS : The links which connect the nodes of section detectors location are used for path travel time estimation traditionally. It makes some problem such as increasing accumulation errors and processing times. In this background, the new links composition methods for spatial aggregation are considered by using some types of nodes as IC, JC, RSE combination. Path travel times estimated by new aggregation methods are compared with PBM travel times by MAE, MAPE and statistical hypothesis tests. RESULTS : The results of minimum sample size and missing rate for 5 minutes aggregation interval are satisfied except for JC link path travel time in Seoul TG~Kuemho JC. Thus, it was additionally observed for minimum sample size satisfaction. In 15, 30 minutes and 1 hour aggregation intervals, all conditions are satisfied by the minimum sample size criteria. For accuracy test and statistical hypothesis test, it has been proved that RSE, Conzone, IC, JC links have equivalent errors and statistical characteristics. CONCLUSIONS : There are some errors between the PBM and the LBM methods that come from dropping vehicles by rest areas. Consequently, this survey result means each of links compositions are available for the estimation of path travel time when PBM vehicles are missed.

• 인터넷정보학회논문지
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• 제2권1호
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• pp.1-11
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• 2001

프로토콜을 시험하기 위하여 페트리 네트나 동적인 FSM을 이용하여 시험열을 생성하는 방법이 제시되고 있지만, 이 방법은 프로토콜 오류를 허용하거나 루핑 경로가 포함되어 있는 경우에는 에러가 발생하거나 상태가 폭발하여 시험열 생성이 불가능하다. 또 프로토콜을 구현하고 시험하기 위한 시험 범위를 결정하는 것은 시간적 기술적 및 경제적으로 어려운 문제이다. 이를 위하여 정규 표현식을 이용하여 정적으로 간단하게 프로토콜 기능을 커버하는 시험열 생성 방안을 제시하였다. 제안한 방법에 의하여 Q.2971 프로토콜의 최소 시험열을 생성한 결과 38가지의 시험열을 구하였으며, 동적인 방법을 사용할 때 루프 상태의 형성에 기인하는 반복 시험 횟수 문제는 표현식을 단순화하는 과정에서 최소화시킬 수 있었다. 이 과정에서, 시험열의 생성은 정규 표현식을 사용하는 것이 간단하고 쉽다는 것을 확인하였다. 또한 구해진 정규 표현식에서 임의의 시험열의 포함 관계를 검출하기 위한 방법도 검토하였다.

• 한국항행학회논문지
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• 제22권4호
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• pp.311-318
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• 2018

본 논문에서는 소형발사체의 무선통신 시스템 검증을 위한 테스트 베드를 제안한다. 제안하는 테스트 베드는 안테나 테스트 커플러와 RF 감쇄기 및 스위칭 시스템으로 구성되어 있다. 안테나 테스트 커플러는 소형 발사체에 장착되어 있는 각 대역별 안테나를 서로 격리 시키며 무선신호를 송/수신하기 위한 장치이며 RF 감쇄기 및 스위칭 시스템은 각 대역의 안테나별 통신점검을 위하여 안테나별 경로를 선택해 주는 장치이다. 안테나 테스트 커플러 설계 결과, UHF-, S-, X-대역에서 39.3, 47.1, 56.1 dB 이상의 차폐율을 확인 할 수 있었다. 실제 소형 발사체에 적용하여 발사체 통신 시스템을 점검한 결과, 정상적으로 데이터 송/수신을 확인 할 수 있었으며, 안테나 경로 스위칭을 통하여 각 대역의 안테나별 통신 점검을 수행할 수 있었다.