• Journal of the Korea Concrete Institute
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• v.24 no.3
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• pp.259-266
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• 2012

A general earthquake resistant design philosophy of ductile frame buildings allows beams to form plastic hinges adjacent to beam-column connections. In order to carry out this design philosophy, the ultimate bond or shear strength of the beam should be greater than the flexural yielding force and should not degrade before reaching its required ductility. The behavior of RC members dominated by bond or shear action reveals a dramatic reduction of energy dissipation in the hysteretic response due to the severe pinching effects. In this study, a method was proposed to predict the deformability of reinforced concrete members with short-span-to-depth-ratios, which would result in bond failure after flexural yielding. Repeated or cyclic loading produces a progressive deterioration of bond that may lead to failure at lower cyclic bond stress levels. Accumulation of bond damage is caused by the propagation of micro-cracks and progressive crushing of concrete in front of the lugs. The proposed method takes into account bond deterioration due to the degradation of concrete in the post yield range. In order to verify bond deformability of the proposed method, the predicted results were compared with the experimental results of RC members reported in the technical literature. Comparisons between the observed and calculated bond deformability of the tested RC members showed reasonably good agreement.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.19 no.2
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• pp.62-73
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• 2020

Access management is aimed at preserving the road's high intercity mobility. In urbanized areas, immoderate acceleration lane-length requirements restrict the accessibility of land. Therefore, there are many opinions to revise the minimum acceleration lane-length requirement. For this purpose, it is important to diagnose the effects of slow vehicles on the mainline. This study analyzed a single merging vehicle's total delay occurrence depending on the mainline traffic flow rate and merging speed. A linear relationship was observed between the mainline traffic flow rate and total delay. As a merging speed increases gradually from 40km/h to 100km/h in 20km/h intervals, the total delay decreases by 5.0, 1.6, and 5.1 times, respectively. This shows that the ideal condition with the total delay is less than 0.5 vehicle·sec when there is no speed difference between the mainline and merging vehicle. On the other hand, given the one-second response time of drivers, the total delay occurrence was slightly low when the speed difference between the mainline and merging vehicle was less than 20km/h.

• Phonetics and Speech Sciences
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• v.12 no.2
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• pp.63-72
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• 2020

This study aims to develop a video-based smart utterance deep analyser (SUDA) application that analyzes semiautomatically the utterances that child and mother produce during interactions over time. SUDA runs on the platform of Android, iPhones, and tablet PCs, and allows video recording and uploading to server. In this device, user modes are divided into three modes: expert mode, general mode and manager mode. In the expert mode which is useful for speech and language evaluation, the subject's utterances are analyzed semi-automatically by measuring speech and language factors such as disfluency, morpheme, syllable, word, articulation rate and response time, etc. In the general mode, the outcome of utterance analysis is provided in a graph form, and the manger mode is accessed only to the administrator controlling the entire system, such as utterance analysis and video deletion. SUDA helps to reduce clinicians' and researchers' work burden by saving time for utterance analysis. It also helps parents to receive detailed information about speech and language development of their child easily. Further, this device will contribute to building a big longitudinal data enough to explore predictors of stuttering recovery and persistence.

• Korean Journal of Construction Engineering and Management
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• v.16 no.6
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• pp.112-123
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• 2015

Many disputes are happened with various causes in overseas construction projects. One of major disputes is closely related with nominated subcontractors (NSC). This paper investigates 30 judical precedents for Singapore, Malaysia and Hongkong to analyze the detailed disputes related with the NSC, and then the judical precedents are classified into 6 categories: Delay and Defect Trouble (T1), Contract Relation (T2), Payment Trouble (T3), Set-off (T4), Liquidation (T5) and so forth (T6). According to the analytical results, the frequency of occurrence of disputes is considerably related with social and economical changes, and the dispute between NSC and employer for residential and commercial building projects is the most frequently happened case. As the results of analysis, therefore, it is concluded that the employer needs to response aggressively to the problems related with NSC, and it is also important to make the council for communication among related bodies. Furthermore, the institutional reform that make the role and the responsibility of employer consistent under considering contract terms and conditions is considered as the most important and fundamental issue.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.5
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• pp.1-9
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• 2016

Railroad bridges account for 25% of the entire high-speed rail network. Railway bridges are subject to gradual structural degradation or fatigue accumulation due to consistent and repeating excitation by fast moving trains. Wireless sensing technology has opened up a new avenue for bridge health monitoring owing to its low-cost, high fidelity, and multiple sensing capability. On the other hand, measuring the transient response during train passage is quite challenging that the current wireless sensor system cannot be applied due to the intrinsic time delay of the sensor network. Therefore, this paper presents a framework for monitoring such transient responses with wireless sensing systems using 1) real-time excessive vibration monitoring through ultra-low-power MEMS accelerometers, and 2) post-event time synchronization scheme. The ultra-low power accelerometer continuously monitors the vibration and trigger network when excessive vibrations are detected. The entire network of wireless smart sensors starts sensing through triggering and the post-event time synchronization is conducted to compensate for the time error on the measured responses. The results of this study highlight the potential of detecting the impact load and triggering the entire network, as well as the effectiveness of the post-event time synchronized scheme for compensating for the time error. A numerical and experimental study was carried out to validate the proposed sensing hardware and time synchronization method.

• Korean Journal of Remote Sensing
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• v.30 no.5
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• pp.587-596
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• 2014

Soil moisture is one of the most important interests in hydrological response and the interaction between the land surface and atmosphere. Estimation of Antecedent Wetness Conditions (AWC) which is soil moisture condition prior to a rainfall in the basin should be considered for rainfall-runoff prediction. In this study, Soil Wetness Index (SWI), Antecedent Precipitation Index ($API_5$), remotely sensed Soil Moisture ($SM_{rs}$), and 5 days ground Soil Moisture ($SM_{g5}$) were selected to estimate the AWC at four study area in the Korean Peninsula. The remotely sensed soil moisture data were taken from the AMSR-E soil moisture archive. The maximum potential retention ($S_{obs}$) was obtained from direct runoff and rainfall using Soil Conservation Service-Curve Number (SCS-CN) method by rainfall data of 2011 for each study area. Results showed the great correlations between the maximum potential retention and SWI with a mean correlation coefficient which is equal to -0.73. The results of time length representing the time scale of soil moisture showed a gap from region to region. It was due to the differences of soil types and the characteristics of study area. Since the remotely sensed soil moisture has been proved as reasonable hydrological variables to predict a wetness in the basin, it should be continuously monitored.

• Korean Security Journal
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• no.61
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• pp.87-107
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• 2019

With the government policy on converting contract workers to full-time employees, there have been significant changes about the security personnel at the nation's critical facilities, including the National Assembly Building and airports. Moreover, the scheduled disbandment of the conscripted police force in 2023 has raised concerns about security management at different government agencies. To examine the college students' perceptions on the possible alternatives to fill the expected security gap, 234 undergraduate students of security management and protection in the Seoul metropolitan region were surveyed. Particularly, a comparative analysis was conducted on the legal bases and supervision, the employment types and salaries, and the scopes of responsibility and authority of suggested alternatives were compared. The results showed that utilization of private police forces was thought to be the most effective option. Based on the research findings, the university departments should develop and maintain a quality curriculum to educate their students to be prepared security professionals with a focus on emergency response capabilities and martial arts, including the courses on private police law and emergency rescue and cardiopulmonary resuscitation (CPR).

• Korean Security Journal
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• no.61
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• pp.235-254
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• 2019

This study identifies a factor structure regarding the criterion of terror awareness by using confirmatory factor analysis. The study provides information whether the criterion fits in the analysis of terror awareness in Korea or not. Data of 176 public officials working at the National Assembly collected in 「Study on the Improvement of Security in the National Assembly Building」(Choi O-Ho and others, 2016) was used in the analysis. Study results showed the fit statistics of 3 questions regarding concern in terror, 5 questions regarding cognition of terror occurrence, 3 questions regarding countermeasure of terror, and 3 questions regarding equipments against terror satisfied the standard. Also, standard regression coefficient exceeded the standard and was shown to be fit. Concern in terror, as a latent variable, was below the standard value of average variance extracted. However, focused validity was secured by obtaining other values fit. This study proceeded distinct validation test to supplement data. The test results showed that the criterion level was fit. Thus, further survey should include questions that are appropriate to measure the awareness of terror based not only on theories and previous studies but also on questions of terror awareness tested in this study. Such development in surveys will support the means of data measurement.

• Journal of Information Management
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• v.39 no.1
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• pp.83-108
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• 2008

This thesis investigated disabled students' actual status of applying for university libraries. This thesis investigated how many times the university disabled students utilized the libraries, if facilities, apparatuses, materials, and regular employees were operated properly, and if they were established actually on the target at thirty private university libraries located at Seoul and Gyeonggi regions in operation of specially screening the objective students for special education in 2008. The investigation found that the general operation level of university libraries for disabled students were less than "medium"(average 2.38). As for utilization ratio, the most university students responded that "they didn't utilize libraries so many times(60%)". As for the response ratio of university library facilities and services, the most university students responded, "very insufficient", 99 items(32.27%), and the least university students responded, "very excellent", 28 items(7.0%). On the other hand, as for the analysis of each field, building facilities, in all of the items, were established more than "medium"(average 3.26), but material preparation level(average 1.8 point), employee education for softly supporting disabled students, and library utilization education on the target at disabled students(average 1.87) were less than "insufficient". Especially, the field of service was "insufficient level"(average 2.48), and standard deviation was more than 1.4. Manpower stationing and material delivery services have the biggest standard deviation between universities. So, this investigation found that university libraries reformed access to facilities a lot, but that its level of fundamental policy for library, such as materials, manpower, and the education on utilization, were in insufficient level.

• Journal of the Earthquake Engineering Society of Korea
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• v.6 no.4
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• pp.65-73
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• 2002

It has been recognized that the damage control must become a more explicit design consideration. In an effort to develop design methods based on performance it is clear that the evaluation of the nonlinear response is required. The methods available to the design engineer today are nonlinear time history analyses, monotonic static nonlinear analyses, or equivalent static analyses with simulated nonlinear influences. Some building codes propose the capacity spectrum method based on the nonlinear static analysis(pushover analysis) to determine the earthquake-induced demand given by the structure pushover curve. These procedures are conceptually simple but iterative and time consuming with some errors. This paper presents a nonlinear direct spectrum method(NDSM) to evaluate seismic performance of structures, without iterative computations, given by the structural initial elastic period and yield strength from the pushover analysis, especially for MDF(multi degree of freedom) systems. The purpose of this paper is to investigate the accuracy and confidence of this method from a point of view of various earthquakes and unloading stiffness degradation parameters. The conclusions of this study are as follows; 1) NDSM is considered as practical method because the peak deformations of nonlinear system of MDF by NDSM are almost equal to the results of nonlinear time history analysis(NTHA) for various ground motions. 2) When the results of NDSM are compared with those of NTHA. mean of errors is the smallest in case of post-yielding stiffness factor 0.1, static force by MAD(modal adaptive distribution) and unloading stiffness degradation factor 0.2~0.3.