• 한국군사과학기술학회지
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• 제19권4호
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• pp.435-442
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• 2016

For inertial navigation systems, initial information such as position, velocity and attitude is required for navigation. Self-alignment is the process to determine initial attitude on stationary condition using inertial measurements such as accelerations and angular rates. The accuracy of self-alignment is determined by inertial sensor error. As soon as an inertial navigation system is powered on, the temperature of accelerometer rises rapidly until temperature stabilization. It causes acceleration error which is called temperature stabilizing error of accelerometer. Therefore, temperature stabilizing error degrades the alignment accuracy and also increases alignment time. This paper suggests a method to calculate azimuthal attitude using curve fitting of horizontal control angular rate in fixed-gain self-alignment. It is verified by simulation and experiment that the accuracy is improved and the alignment time is reduced using the proposed method under existence of the temperature stabilizing error.

• 한국지반공학회논문집
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• 제31권5호
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• pp.35-46
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• 2015

본 연구에서는 최근 국내에서 사용이 증가하고 있는 2열 자립식 흙막이 공법에 있어서 안정성에 영향을 미치는 주요 설계인자들을 분석하고 설계기준을 제안하기 위하여 현장적용 결과의 분석 및 3차원 유한차분 해석을 수행하였다. 지반특성에 따른 본 공법의 거동을 분석하기 위하여 사질토가 지배적인 현장과 점성토가 지배적인 2개의 현장에 적용을 수행하였으며, 굴착에 따른 흙막이 벽체의 수평변위 및 휨모멘트를 분석하였다. 3차원 유한차분 모델링 기법의 타당성을 검증하기 위하여 현장적용 결과와 비교 분석을 수행한 결과, 본 연구의 수치해석 모델링 기법은 본 공법의 굴착에 따른 거동을 합리적으로 모사하는 것으로 나타났다. 또한 흙막이 벽체를 구성하는 전열말뚝(엄지말뚝) 및 후열말뚝(억지말뚝)의 간격(S), 전열말뚝과 후열말뚝간의 거리(D), 굴착심도(H) 및 말뚝의 근입깊이(Z) 등, 본 공법의 주요 설계인자들의 영향 정도를 분석하기 위하여 다양한 경우의 3차원 유한차분 모델링 및 해석을 수행하였다. 그 결과, 굴착에 따라 발생하는 흙막이 벽체의 최대 수평변위는 전열말뚝 및 후열말뚝의 간격의 감소, 전열말뚝과 후열말뚝간의 거리의 증가 및 말뚝 근입심도의 증가에 따라 감소하였으며, 이러한 특징은 점성토 조건의 지반보다는 사질토 조건의 지반에서 보다 명확하게 나타나는 것을 확인할 수 있었다.

• 한국생활과학회지
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• 제18권3호
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• pp.609-618
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• 2009

The study examined the effects of parenting process(supportive and involving mother-adolescent relationship, father-adolescent relationship) and school process(teachers' support, school life satisfaction) on adolescents' academic achievement and self-evaluation. Participants were 1787 middle school students (902 boys, 885 girls) in KEEP(Korean Education and Employment Panel). Structural equation modeling indicated that parenting and school process influenced adolescents' self-evaluation through adolescents' academic achievement. Also, the analysis with One Way ANOVA revealed that positive school (parenting) processes can serve a protective-stabilizing function when parenting(school) processes are negative.

• 한국항공우주학회지
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• 제39권8호
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• pp.796-803
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• 2011

정지 상태에서 관성항법장치를 구성하는 가속도계 및 자이로 측정치를 이용하여 초기 자세를 구하는 것을 초기정렬 혹은 자가정렬이라 한다. 초기정렬의 정밀도는 관성항법장치에 탑재되는 관성센서의 성능에 의하여 결정되며 수평축 자세는 수평축 가속도계, 수직축 자세는 E축 자이로 성능에 의해 결정된다. 그러므로 관성센서에서 발생된 불확실한 오차는 초기정렬의 정밀도를 저하시키는 주요원인이 된다. 논 논문에서는 관성센서의 불확실한 오차 중에서 관성항법장치에 전원이 인가되어 온도가 안정화 되는 상태에서의 관성센서 오차가 초기정렬 성능에 어떠한 영향을 미치는 가를 이론적으로 분석하고 시뮬레이션을 통하여 검증한 결과를 제시한다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국제학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.434-439
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• 1993

Described is a stabilizing circuit of the Doppler beat signal obtained by the coherence-dependent fiber-optic laser Doppler velocimeter (LDV), which employs both a self-mixing laser diode (SM-LD) and a 10m-100m long optical fiber. The stabilizing circuit maintains the SM-LD drive current at an optimum value, which gives a maximum Doppler signal during long hours.

• 한국지반공학회논문집
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• 제25권1호
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• pp.41-54
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• 2009

본 연구는 터파기 형태의 건설공사에서 레이커나 지반앵커 등의 추가적인 버팀이 필요 없는 2열 H-파일을 이용한 자립식 흙막이(SSR) 공법에 대한 것이다. SSR 공법은 사면파괴 방지용 억지말뚝의 역할을 하는 후열말뚝으로 1차적인 토압을 감소시켜 흙막이 벽체의 토압을 분담하고 억지말뚝과 흙막이 벽체의 일체화를 통해 흙막이 벽체의 강성을 증대시킴으로써 레이커나 지반앵커 등의 지보재가 필요 없이 지반굴착을 수행할 수 있는 자립식 흙막이 공법이다. 본 연구에서는 SSR 공법에 대한 실내모형실험 결과를 통하여 굴착에 따른 지반 및 흙막이 구조체의 변협과 토압특성을 분석하였으며, 여러 현장적용 사례와 계측결과를 통하여 굴착방법에 따른 흙막이 가시설의 실제 변형 특성 및 공법의 적용성을 평가하였다. 평가결과, 발생변위가 모두 계측 허용치 이내에서 만족하였다.

• PNF and Movement
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• 제7권4호
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• pp.9-16
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• 2009

Objective : The purpose of this study was to analyze the effect on psychosocial status in elderly women with chronic low back pain after practicing lumbar stabilizing exercise using the gym ball, and to developed and activated on exercise program for healthy senile life. Methods : The subjects were 23 elderly women with chronic low back pain. Mean age of subjects was $67{\pm}13$ years. The lumbar stabilizing exercise using the gym ball was performed 3 times a week during the 8 weeks study period. The research tool were ODI(Oswestry Disability Index), VAS(Visual Analogue Scale), SES(Self-esteem Scale), GDSSF-K(Geriatric Depression Scale Short Form Korea Version), PSS (perceived stress scale), Life satisfaction, and MMSE-K. The analysis of data was processed by the statistical program SPSS 12.0 and paired t-test and frequency analysis were used to compare psychosocial status between the pretest and post tests. Result : The lumbar stabilizing exercise using the gym ball increased significantly SES and Life satisfaction of subjects, and ODI, VAS(trunk flexion & trunk extention), GDSSF-K, and PSS were decreased significantly(p<.05). While VAS(trunk rotation) were not significantly. Conclusion : The lumbar stabilizing exercise using the gym ball improved psychosocial status in elderly women with chronic low back pain.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.1251-1258
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• 2008

The purpose of this research is to introduce the new temporary earth retaining wall system using landslide stabilizing piles. This system is a self-supported retaining wall(SSR) without installing supports such as tiebacks, struts and rakers. The SSR is a kind of gravity structures consisting of twin parallel lines of piles driven below dredge level, tied together at head of soldier piles and landslide stabilizing piles by beams. There are three types of excavation wall structures: standard method for medium retained heights(<8.0m), internal excavation method and slope excavation method for deep-excavation applications(>8.0m). In the present study, the measured data from seven different sites which the SSR was used for excavation were collected and analyzed to investigate the characteristic behavior lateral wall movements associated with urban excavations in Korea.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.2030-2035
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• 2005

In this paper, we study the distributed coordination of a set of synchronous, anonymous, memoryless mobile robots that can freely move on a two-dimensional plane but are unable to communicate directly. Based on this model, we analyze the application problem that consists in having a group of robots form a barricade line to protect from car traffic a crowd of demonstrators parading on the street. For the sake of robustness, we privilege fully decentralized solutions to the problem. In particular, we give a self-stabilizing distributed algorithm to address the problem, in this presentation

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권11호
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• pp.2577-2596
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• 2013

In this paper, we present an Energy-Aware Self-Stabilizing Distributed Clustering protocol based on message-passing model for Ad Hoc networks. The latter does not require any initialization. Starting from an arbitrary configuration, the network converges to a stable state in a finite time. Our contribution is twofold. We firstly give the formal proof that the stabilization is reached after at most n+2 transitions and requires at most $n{\times}log(2n+{\kappa}+3)$ memory space, where n is the number of network nodes and ${\kappa}$ represents the maximum hops number in the clusters. Furthermore, using the OMNeT++ simulator, we perform an evaluation of our approach. Secondly, we propose an adaptation of our solution in the context of Wireless Sensor Networks (WSNs) with energy constraint. We notably show that our protocol can be easily used for constructing clusters according to multiple criteria in the election of cluster-heads, such as nodes' identity, residual energy or degree. We give a comparison under the different election metrics by evaluating their communication cost and energy consumption. Simulation results show that in terms of number of exchanged messages and energy consumption, it is better to use the Highest-ID metric for electing CHs.