• Steel and Composite Structures
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• 제36권3호
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• pp.307-319
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• 2020

The upper chords in half-through truss bridges are prone to buckling due to a lack of the upper transverse connections. Taking into account geometric and material nonlinearity, nonlinear finite-element analysis of a simple supported truss bridge was carried out to exhibit effects of different types of initial imperfections. A half-wave of initial imperfection was proved to be effective in the nonlinear buckling analysis. And a parameter analysis of initial imperfections was also conducted to reveal that the upper chords have the greatest impact on the buckling, followed by the bottom chords, vertical and diagonal web members. Yet initial imperfections of transverse beams have almost no effect on the buckling. Moreover, using influence surface method, the combinatorial effects of initial imperfections were compared to demonstrate that initial imperfections of the upper chords play a leading role. Furthermore, the equivalent effective length coefficients of the upper chord were derived to be 0.2~0.28 by different methods, which implies vertical and diagonal web members still provide effective constraints for the upper chord despite a lack of the upper transverse connections between the two upper chords. Therefore, the geometrical and material nonlinear finite-element method is effective in the buckling analysis due to its higher precision. Based on nonlinear analysis and installation deviations of members, initial imperfection of l/500 is recommended in the nonlinear analysis of half-through truss bridges without initial imperfection investigation.

• 천문학회지
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• 제39권4호
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• pp.147-150
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• 2006

In this paper, initial value problem for dynamical astronomy will be established using parabolic cylindrical coordinates. Computation algorithm is developed for the initial value problem of gravity perturbed trajectories. Applications of the algorithm for the problem of final state predication are illustrated by numerical examples of seven test orbits of different eccentricities. The numerical results are extremely accurate and efficient in predicating final state for gravity perturbed trajectories which is of extreme importance for scientific researches as well as for military purposes. Moreover, an additional efficiency of the algorithm is that, for each of the test orbits, the step size used for solving the differential equations of motion is larger than 70% of the step size used for obtaining its reference final state solution.

• 한국지진공학회논문집
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• 제27권2호
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• pp.119-127
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• 2023

In this paper, seismic performance evaluation was carried out for eight circular reinforced concrete columns designed seismically by KRTA[1]and KCI[8]. Primary design parameters for such columns included many longitudinal reinforcements, yield strength of reinforcements, the vertical spacing of spirals, aspect ratio, and axial force ratio. The test results showed that all the columns exhibited stable hysteretic and inelastic responses. Based on the test results, drift ratios corresponding to each damage state, such as initial yielding, initial cover spalling, initial core concrete crushing, buckling, and fracture of longitudinal reinforcement and final spalled region, were evaluated. Then, those ratios were compared with widely accepted damage limit states. The comparison revealed that the existing damage states were considerably conservative. This implies that additional research is required for the damage limit states of such columns designed seismically by current Korean design codes.

• 한국게임학회 논문지
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• 제4권1호
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• pp.58-66
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• 2004

본 논문에서는 반례를 도달성 게임 풀이에 활용했다. 도달성 게임이란, 게임 규칙을 준수하면서 초기 상태에서 목표 상태로 가는 경로를 찾는 것이다. 게임의 초기 상태를 유한 상태 모델로 표현하고 목표 상태의 부정(오답)을 시제 논리식으로 표현해서 모델 검사기에 입력하면, 반례로 오답에 대한 부정 즉 정답을 출력한다. 다시 말해서 반례로 출력된 것이 문제를 해결하는 정답인 것이다. 이와 같은 아이디어를 푸쉬푸쉬 게임 풀이에 적용했다. 그 결과 크기가 작은 푸쉬푸쉬 게임의 경우 게임을 해결하는 최단 경로를 쉽게 찾아냈다. 그러나 게임의 크기가 큰 경우 제한된 시간(실험에서는 3시간)내에 찾아내지 못했다. 왜냐하면 게임의 크기가 커질 경우 검사해야할 상태의 수가 지수적으로 증가하는 상태 폭발 문제가 발생했기 때문이다. 상태 폭발 문제를 해결하기 위해 추상화 기법을 이용해서 검사해야 할 상태공간을 축소하였다. 상태 공간을 줄인 결과, 기존 모델체킹으로 해결하지 못했던 게임을 풀 수 있었다.

• 동의생리병리학회지
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• 제16권3호
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• pp.537-541
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• 2002

When a Kigong master concentrates the Qi at Yintang, Laogong(P8), Qihai(CV6) meridian points during Kigong state, the change of magnetic field around acupoints Yintang, Laogong points has been measured using DROS-SQUID apparatus. After smoothing process of the continuously measured magnetic signal around acupoints for a few minutes, we could observe that a series of peaks, magnitude of 1～2 pT and period of 5 sec, appeared and find that these peaks were clearly changed as if switch on and off according to Qi concentration state. Before Qi radiation, a series of the peaks measured on Yintang or Laogong point of a Kigong master shows one of either SW-ON state or SW-OFF state as initial state. During Qi radiation, its state becomes inverse of initial state. After Qi radiation, it returns to the initial state for some cases (called P type ; push button switch type) or it remains inversion state for other cases (called T type; toggle switch type). From the data of peaks measured at different position from the Qi concentration acupoint, we found that the Qi radiation on an acupoint makes the switching effect even not at the acupoint that Qi is concentrated but at the other acupoints that Qi is not concentrated.

• International Journal of Naval Architecture and Ocean Engineering
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• 제13권1호
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• pp.877-888
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• 2021

The water entry behaviors of projectiles with different cone-headed angles were studied numerically, experimentally and theoretically, mainly focusing on the hydrodynamic impact in the initial stage. Based on MMALE algorithm, it was proposed a formula of impact deceleration, which relied on the initial entry velocity and cone-headed angle. Meanwhile, in order to verify the validity of the simulation model, experiments using accelerometer and high-speed camera were carried out, and their results were in a good agreement with simulation results. Also, theoretical calculation results of cavity diameter were compared with experiments and simulation results. It was observed that the simulation method had a good reliability, which would make forecast on impact deceleration in an engineering project.

• PNF and Movement
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• 제19권3호
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• pp.351-359
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• 2021

Purpose: This purpose of this study was to investigate the effects of initial cognitive status on the recovery of functional status in patients with subacute stroke. Methods: The participants were 111 patients with subacute stroke, divided into two groups: mini-mental state examination (MMSE) <20 (n=49) group and MMSE ≥20 (n=62) group. Clinical evaluation scores were collected before and after rehabilitation. The repeated measurements ANOVA was used to confirm the changes in functional status before and after intervention in the two groups. Changes in functional status within the group were examined through a paired test. A Pearson correlation coefficient analysis was performed to identify the correlation between MMSE change amount and functional status score. Results: In each of the two groups, according to the initial cognitive status, the clinical evaluation score increased statistically significantly, but there was no difference between the two groups in the degree of significant increase. When examining the correlation between the MMSE change amount, according to the initial cognitive state and the functional state score change amount, it was found, only in the group with MMSE <20, that the larger the change in the MMSE score, the greater the functional state change of Berg balance scale, Rivermead Mobility Index, and motor assessment scale. This did not apply to the group with MMSE ≥20. Conclusion: Initial cognitive status should be considered when setting the patient's goal, and considering cognitive improvement when constructing a rehabilitation program is thought to have a positive effect on rehabilitation services.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1998년도 봄 학술발표회 논문집
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• pp.93-100
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• 1998

The basic systems of spatial structures such as shells, membrane, cable-nets and tensegrity structure have been developed to create the large spaces without column. These structures may have large freedom in scale and form, and especially tensegrity structures are received much attention from the view points of their light weight and aesthetics. But There re some difficulties concerning structural stability, surface formation and construction method. One of the way to solve these problems reasonably is a combination of tensile members and rigid members. A structural system based on this concept is referred to as the "HTS ( Hybrid Tension Structure )". This is a type of flexible structural system which is unstable initially, because the cable material has little initial rigidity. As cable - dome hybrid structures is a type of HTS, the initial stress for the self- equilibrated system having stable state have to be introduced. To determine initial stress having stable state, the shape finding analysis is required before the stress - deformation analysis. In this paper, the primary objective is to derive the nonlinear finite element formula of cable and truss members considering geometric nonlinearity for shape finding of cable-dome, and to propose the method to decide the initial stress by the shape analysis of cable-dome hybrid structure with the self-equilibrated state.

• 대한의용생체공학회:의공학회지
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• 제18권4호
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• pp.477-484
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• 1997

본 논문에서는 각성도 평가시 초기 각성상태 차이에 따른 보상방법을 제안하고 보상상수를 결정하였다. 각성도는 IRI와 Nz에 의하여 측정되었다. BI는 초기 저각성상태의 영향을 많이 받게 되며 이는 각성도의 지표인 Nz 값에 영향을 주게 되어 각성수준이 실제보다 높게 평가된다. 따라서 본 연구에서는 BI의 과대평가로 인한 오판정 문제를 해결하기 위하여 수정된KSS 측도(mKSS)를 이용한 보상법을 제안하고 각성수준에 따른 수정된 KSS 측도에 대응하는 보상상수를 결정하였다. 이 보상상수를 개발된 휴대형 각성도 측정 시스템에 적용하여, 실시간으로 각성도를 평가 및 제어한 결과, 본 연구에서 제안한 보상법 및 보상상수의 유용성을 확인하였다.

• 영어어문교육
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• 제10권2호
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• pp.1-23
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• 2004

This article reports a bi-directional interlanguage study designed to investigate the initial state of L2 acquisition with regard to English and Korean wh-questions. Based on the UG system in line with the minimalist theory, it was hypothesized that the L2 initial state is characterized by the most economical form of syntax in which no overt wh-movement to Spec-CP is assumed. Results of the early interlanguage study showed that 1) L1 Korean learners of L2 English predominantly produced wh-questions with the fronted wh-word, but without productive wh-movement to the Spec-CP position; and 2) L1 English learners of L2 Korean overwhelmingly produced wh-questions with the wh-word remaining in-situ. These results were interpreted as supporting the minimalist account of the L2 initial grammar in that no overt syntactic wh-movement were adopted in early interlanguages of both English and Korean regardless of the learner's L1.