• Proceedings of the Computational Structural Engineering Institute Conference
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• 2007.04a
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• pp.235-240
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• 2007

For the identification of the 3 dimensional dynamic characteristics of the Bongjeong Temple, the dynamic test for 1/3 scaled model was performed. Dynamic test with impulse excitation and vibration table excitation can provide useful data for the estimation of dynamic characteristics such as natural frequencies, damping ratios, mode shapes and stiffness center. This will complement the previous research from the 2-dimensional static test and provide the reference data for the enhanced structural analysis of the traditional wooden structures.

• Smart Structures and Systems
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• v.13 no.5
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• pp.797-819
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• 2014

This paper presents a theoretical algorithm for constructing the mode shapes of a bridge from the dynamic responses of a test vehicle moving over the bridge. In comparison with those approaches that utilize a limited number of sensors deployed on the bridge, the present approach can offer much more spatial information, as well as higher resolution in mode shapes, since the test vehicle can receive the vibration characteristics of each point during its passage on the bridge. Basically only one or few sensors are required to be installed on the test vehicle. Factors that affect the accuracy of the present approach for constructing the bridge mode shapes are studied, including the vehicle speed, random traffic, and road surface roughness. Through numerical simulations, the present approach is verified to be feasible under the condition of constant and low vehicle speeds.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.16
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• pp.6571-6574
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• 2014

Background: Alcohol is well established as a risk factor for cancer development in many organ sites. To assess the reliability and validity of the Alcohol Use Disorders Identification Test - Consumption (AUDIT-C) for detecting alcohol use disorders or risky drinking in Japanese adults the present study was conducted. Materials and Methods: A test-retest method was applied with a 2-week interval with 113 health care employees. The k coefficient, Cronbach's coefficient alpha, Spearman's correlation coefficient, and intraclass correlation coefficient (ICC) were determined and the validity of the AUDIT-C was analyzed using the data from a nationwide survey on adult alcohol use conducted in 2008 (n=4,123). Results: The reliability of the AUDIT-C score was high (${\kappa}$ coefficient=0.63, Cronbach's alpha=0.98, correlation coefficient=0.95, and ICC=0.95). According to the likelihood ratio and Youden index, appropriate cutoffs for the AUDIT-C were ${\geq}5points$ in men and ${\geq}4$ points in women. The sensitivity and specificity of these cutoffs for identifying ${\geq}8$ points on the AUDIT were 0.88 and 0.80, respectively, for men (positive likelihood ratio [LR+]=4.5) and 0.96 and 0.87, respectively, for women (LR+=7.7). The sensitivity and specificity of the cutoffs for identifying ${\geq}12$ points on the AUDIT were 0.90 and 0.84, respectively, for men (LR+=5.8) and 0.93 and 0.94, respectively, for women (LR+=15.8). The sensitivity and specificity of the cutoffs for identifying ${\geq}16$ points on the AUDIT were 0.93 and 0.80, respectively, for men (LR+=4.7) and 0.92 and 0.98, respectively, for women (LR+=55.6). With higher scores on the AUDIT, the specificity decreased and false-positives increased. The appropriate cutoffs for identifying risky drinking were the same for both genders. Conclusions: The reliability and validity of the AUDIT-C are high, indicating that it is useful for identifying alcohol use disorders or risky drinking among the general population in Japan, a group at high risk of cancer development.

• The Journal of Korean Physical Therapy
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• v.22 no.4
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• pp.1-6
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• 2010

Purpose: This study was designed to evaluate the clinical utility of the Four square step test (FSST) for predicting falls in stroke patients, to compare the ability of the FSST test to discriminate between subgroups of fallers, and to determine if the test has any predictive value in identifying stroke patients who will fall. Methods: Stroke patients (N=37) who could walk at least 50 m with minimal assistance were recruited consecutively when attending a physical therapy session during their rehabilitation. Dynamic standing balance was measured using the FSST. The main outcome measures were FSST time and fall number. Numbers of falls were compared with FSST scores. Differences between the groups in FSST scores were examined using a t-test and 1-way analysis of variance. Post hoc analysis using the Tukey B procedure was used to identify specific group differences. Alpha was set at 0.05. Results: A total of 15 participants (40.5%) reported falls 6 had recurrent falls (2 falls) and 9 fell once. The mean FSST time differed significantly between groups with zero and multiple falls. A cutoff score of greater than 17 seconds on the FSST was associated with a sensitivity of 83% and a specificity of 84% for the identification of subjects with multiple risk factors for falls. Conclusion: The FSST is a feasible and valid clinical test of dynamic standing balance and can predict falls in post-stroke patients.

• Korean Journal of Optics and Photonics
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• v.17 no.1
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• pp.47-53
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• 2006

The Integrated Ballistics Identification Systems (IBIS) is widely used for bullet and casing signature identification. The IBIS obtains a pair of ballistic signatures from two bullets (or casings) using optical microscopy, and estimates a correlation score which can represent the degree of signature match. However, this method largely depends on lighting and surface conditions because optical image contrast is primarily a function of test surface's slope, shadowing, multiple reflections, optical properties, and illumination direction. Moreover, it can be affected with surface height variation. To overcome these problems and improve the identification system, we used well known surface topographic techniques, such as confocal microscopy and white-light scanning interferometry. The measuring instruments were calibrated by a NIST step height standard and verified by a NIST sinusoidal profile roughness standard and a commercial roughness standard. We also suggest a new analysis method for the ballistic identification. In this method, the maximum cross-correlation function CCFmax is used to quantify the degree of signature match. If the compared signatures were exactly the same, CCFmax would be $100\%$.

• Journal of Aerospace System Engineering
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• v.17 no.4
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• pp.133-143
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• 2023

As drones (also known as UAV) become popular with advanced information and communication technology (ICT), they have been utilized for various fields (agriculture, architecture, and so on). However, malicious attackers with advanced drones may pose a threat to critical national infrastructures. Thus, anti-drone systems have been developed to respond to drone threats. In particular, remote identification data (R-ID)-based UAV detection and identification systems that detect and identify illegal drones with R-ID broadcasted by drones have been developed, and are widely employed worldwide. However, this R-ID-based UAV detection/identification system is vulnerable to security due to wireless broadcast characteristics. In this paper, we analyze the security vulnerabilities of DJI Aeroscope, a representative example of the R-ID-based UAV detection and identification system, and propose a replay-attack-based neutralization method using the analyzed vulnerabilities. To validate the proposed method, it is implemented as a software program, and verified against four types of attacks in real test environments. The results demonstrate that the proposed neutralization method is an effective neutralization method for R-ID-based UAV detection and identification systems.

• Publications of The Korean Astronomical Society
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• v.12 no.1
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• pp.185-196
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• 1997

We present a code which identifies individual clouds in crowded region using IMFORT interface within Image Reduction and Analysis Facility (IRAF). We define a cloud as an object composed of all pixels in longitude, latitude, and velocity that are simply connected and that lie above some threshold temperature. The code searches the whole pixels of the data cube in efficient way to isolate individual clouds. Along with identification of clouds it is designed to estimate their mean values of longitudes, latitudes, and velocities. In addition, a function of generating individual images (or cube data) of identified clouds is added up. We also present identified individual clouds using a $^{12}CO$ survey data cube of Galactic Anticenter Region (Lee et al. 1997) as a test example. We used a threshold temperature of $5\sigma$ rms noise level of the data With a higher threshold temperature, we isolated subclouds of a huge cloud identified originally. As the most important parameter to identify clouds is the threshold value, its effect to the size and velocity dispersion is discussed rigorously.

• International Journal of Control, Automation, and Systems
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• v.1 no.1
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• pp.1-10
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• 2003

This paper presents a high-precision magnetically levitated (maglev) stage to meet demanding motion specifications in the next-generation precision manufacturing and nanotechnology. Characterization of dynamic behaviors of such a motion stage is a crucial task. In this paper, we address the issues related to the stochastic modeling of the stage including transfer function identification, and noise/disturbance analysis and prediction. Provided are test results on precision dynamics, such as fine settling, effect of optical table oscillation, and position ripple. To deal with the dynamic coupling in the platen, we designed and implemented a multivariable linear quadratic regulator, and performed time-optimal control. We demonstrated how the performance of the current maglev stage can be improved with these analyses and experimental results. The maglev stage operates with positioning noise of 5 nm rms in $\chi$ and y, acceleration capabilities in excess of 2g(20 $m/s^2$), and closed-loop crossover frequency of 100 Hz.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.12 no.3
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• pp.331-343
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• 1999

본 논문에서는 새로이 유도된 진동기초 손상검색방법을 제시하고, 제한적인 모드특성치가 측정된 구조물을 대상으로 이 알고리즘의 적합성과 손상예측의 정확도를 검증하고자 하였다. 먼저, 기존의 Kim과 Stubbs에 의해 발표된 손상발견 알고리즘들을 검토하였으며, 이 알고리즘들의 적용한계와 오류적 가정을 극복할 수 있는 손상검색 알고리즘을 새로이 유도하였다. 다음으로, 손상발생 전후에 소수의 진동모드 특성치가 측정된 2경간 연속보를 대상으로 손상예측실험을 수행하여, 이들 손상검색 알고리즘의 손상예측 정확도를 분석하였다. 기존의 손상검색 알고리즘에 비하여 새로이 유도된 손상검색 알고리즘의 손상예측 정확도가 향상된 것으로 분석되었다.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2003.09a
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• pp.106-109
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• 2003

Many diverse methods have been developing in the field of biometric identification as human-friendliness has been emphasized in the intelligent system's area. One of emerging method is to use human footprint. Automated footprint-based person recognition was started by Nakajima et al.'s research but they showed relatively low recognition result by low spatial resolution of pressure sensor and standing posture. In this paper, we proposed a modified Nakajima's method to use walking footprint which could give more stable toe information than standing posture. Finally, we prove the usefulness of proposed method as 91.4tt recognition rate in 11 volunteers' test.