• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.9 no.4
• /
• pp.125-133
• /
• 1989

For convergent photos, which are now widely adopted for terrestrial facility survey, a number of experimental studies and theoretical studies on the developments of accuracy predictional model according to the convergent angle change have been accomplished. And such studies are basically depend on the symmetrical geometric configuration at the normal direction to the center of the object. However, in may cases of facility survey such as building facades, bridges, dam surfaces, relatively flat topography, etc., the object features are almost like planar, and frequently the surroundings do not allow the photo station at normal direction, and the sufficient convergent angle can be hardly achieved. Considering those points, in this study, the accuracy analysis on three dimensional coordinates according to the variations of photo direction and of convergent angle to the planar object were attempted, and the optimum geometric configurations at the normal, side-looking, and the most side-looking direction were investigated. The result through this study show that from normal direction to the side-looking direction angle ${\tau}=30^{\circ}$, the larger the convergent angle, the higher the accuracy, and in case that right photo is at the most side-looking direction, the better accuracy can be achieved according to the convergent angle increase up to $60^{\circ}$.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.6 no.4
• /
• pp.53-60
• /
• 1986

This study is directed to propose a probability based LRFD design code, which could possibly replace the traditional USD provisions of the current code, based on the AFOSM reliability theory. The uncertainties of resistances and load effects for each R.C. structural elements are evaluated and adopted considering our practice, and a set of rational target reliability indices are selected based on the calibration with the reliability of the current R.C. design code and by considering the desired hierarchy of safety level. Then, a set of common load factors are chosen from the results of load and resistance factors which are computed by AFOSM method using the Rackwitz-Fiessler's efficient practical algorithm which is to transform the non-normal variables into the equivalent normal variables. It may be asserted that the proposed LRFD code for the R.C. building structures may have to be incorporated into the current RC. design codes as a design provision corresponding to the USD provisions of the current R.C. design code.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.36 no.6
• /
• pp.1023-1035
• /
• 2016

Suspended sediment concentration (SSC) is a crucial riverine parameter in terms that it can be utilized for analyzing sediment transport, stability assessment of river and structure and so on. However, in case of domestic, sediment discharge data are not enough because of using conventional sediment samplers. This study aimed at developing a practical technique for estimating suspended sediment concentration in high spatial and temporal resolution by building relationship between acoustic backscatter (or SNR) from H-ADCP with actually observed data using LISST-100X. In this regard, a dedicated correction algorithm was proposed particularly for the adapted H-ADCP (SonTek SL-3000). Then, a SNR-SSC relation was built based upon a real-scale field experiment, where both H-ADCP and LISST-100X were concurrently operated to observe SNR and SSC, respectively. The coefficient of determination for the developed regression equation of SNR-SSC relation was around 0.85~0.88, thereby the relation could be evaluated to be highly correlated. The result of this study might be potentially applied for real-time and simultaneous observation of SSC when H-ADCP could be applied.

• Spatial Information Research
• /
• v.22 no.5
• /
• pp.43-52
• /
• 2014

Recently, Big Data is a buzzword in the creative economy generation. The organizations related to spatial information society focus on building the spatial big data systems. As spatial big data is a combination of spatial information and big data, the data visualization is essential in order to utilize them efficiently. One of the great methodologies for data visualization is infographics. Nationally, Chousn.com initiated the infographics news in 2010. Korean Administration Branches also recognized the importance of infographic and they adopted infographics for their briefings from 2013. Internationally, Visual.ly is leading company in the infographics market and they produced noticeable interactive infographics for Egypt Parliamentary Elections results. In the defense part, Guardian's datajournalism of Afghanistan war log was a good example of utilizing infographics. Throughout the research, five requirements are extracted. First source data should have precision and accuracy in terms of time and space manner. Second, infographics images have a compressibility. Third, the infographics is properly processed for military commanders. Fourth, sharing, openness and communication are essential for high quality infographic. Lastly, infographics should be an analytic tool for predicting future event based on the past data. Infographics is not a direct representation of data but an analytic tool for helping user's choice and decision in critical moments.

• Journal of Korea Water Resources Association
• /
• v.54 no.5
• /
• pp.321-334
• /
• 2021

A fixed reflectivity-rainfall relationship approach, such as the Marshall-Palmer relationship, for an entire year and different seasons, can be problematic in cases where the relationship varies spatially and temporally throughout a region. From this perspective, this study explores the use of long-term radar reflectivity for South Korea to obtain a nationwide calibrated Z-R relationship and the associated uncertainties within a Bayesian inference framework. A calibrated spatially structured pattern in the parameters exists, particularly for the wet season and parameter for the dry season. A pronounced region of high values during the wet and dry seasons may be partially associated with storm movements in that season. Overall, the radar rainfall fields based on the proposed modeling procedure are similar to the observed rainfall fields. In contrast, the radar rainfall fields obtained from the existing Marshall-Palmer relationship show a systematic underestimation. In the event of high impact weather, it is expected that the value of national radar resources can be improved by establishing an active watershed-level hydrological analysis system.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.25 no.4
• /
• pp.56-64
• /
• 2021

Leakage due to deterioration and damage is one of the major causes of volume change by freezing and thawing, and it leads micro-cracking and surface scaling in concrete structures. The deterioration of damaged concrete accelerates with the chloride attack. Thus, in the detailed guidelines for facility performance evaluation (2020), the quality of cover concrete and the freeze-thaw (FT) repetition cycle were newly suggested for concrete durability assessment. The quality of cover concrete should be evaluated by the rebound hammer test and the FT repetition cycle should be also considered in the deterioration environmental assessment. This study suggested the application of fast dynamic based nonlinear ultrasound method to monitor initial micro-scale damage under freezing and thawing environment. Concrete specimens were fabricated with different water-cement ratios (40%, 60%) and air contents (1.5% and 3.0%). The compressive strength, rebound number, relative dynamic modulus, and nonlinear ultrasound were measured with different FT cycles. The scanning electron microscopy was also performed to investigate the micro-scale FT damage. As a result, both the rebound number and the relative dynamic modulus had difficulty to detect early damage but the proposed method showed a potential to detect initial micro-scale damage and predict the FT resistance performance of concrete.

• 한국노년학
• /
• v.39 no.3
• /
• pp.531-548
• /
• 2019

The purpose of this study is to provide basic data in order to improve service quality based on empirical analyses about a relationship among positive psychological capitals, service quality, and job satisfaction of professional care workers under the Long-Term Care Insurance in South Korea. In this study, total 430 numbers of the workers who were currently working in nursing homes for the elderly at the cities of Ansan, Anyang, Bucheon, and Kwangmyeong in Gyeonggi Province, South Korea, participated in self-report questionnaires. Only 393 questionnaires were used for the final analyses after excluding the ones that neither were not returned nor didn't completed it all. These are major results. First, positive psychological capitals affect positively on service quality. Second, job satisfaction works as a mediating effect in the process of positive psychological capitals affect on service quality. Based on above results, it is possible to suggest it as down below. First, it is required to have policies that will be helpful for both positive psychological capitals and capacity building through human resource management in systematic approaches. Second, it is also required to acknowledge that having positive psychological capitals is effective to improve both their job satisfaction and service quality. Therefore, it is necessary to change environmental circumstances in relevant institutions where this acknowledgement will be applied.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.44 no.2
• /
• pp.173-182
• /
• 2024

In recent, there has been a trend toward primarily utilizing data-driven models employing artificial intelligence technologies, such as machine learning, for flood prediction. These data-driven models offer the advantage of utilizing pre-training results, significantly reducing the required simulation time. However, it remains that a considerable amount of flood data is necessary for the pre-training in data-driven models, while the available observed data for application is often insufficient. As an alternative, validated simulation results from physically-based models are being employed as pre-training data alongside observed data. In this context, we developed a flood mapping accelerator to generate flood maps for pre-training. The proposed accelerator automates the entire process of flood mapping, i.e., estimating flood discharge using HEC-1, calculating water surface levels using HEC-RAS, simulating channel overflow and generating flood maps using RAS Mapper. With the accelerator, users can easily prepare a database for pre-training of data-driven models from hundreds to tens of thousands of rainfall scenarios. It includes various convenient menus containing a Graphic User Interface(GUI), and its practical applicability has been validated across 26 test-beds.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2014.06a
• /
• pp.73-75
• /
• 2014

Marine transportation facility is public goods for the general public and their safety. The study used the Contingent Valuation Method (CVM), a method to estimate economic value of non-market goods, such as environmental goods. In order to analyze economic effects of marine accidents preventable by the VTS, the study estimated costs caused by marine accident cases. It conducted surveys with people and shipping companies in local areas where VTS is to be established in the future. According to a survey with people in areas where marine transportation control center is to be built (Tongyoung), the yearly benefit from building new VTS is estimated at KRW 11billion. If fees are paid in the form of income tax for five years from 2014, corresponding benefits during the same period will reach KRW 47.3 billion in current value. An analysis on economic validity of VTS establishment in Tongyong showed the B/C ration stood at 3.193, far higher than 1. The Net Present Value (NPV) was KRW 32.5 billion and the Internal Rate of Return (IRR) turned out to be 37.4% which was higher than social discount rates of 53.5%. On balance, the establishment has reasonable economic validity.

• The KIPS Transactions:PartD
• /
• v.13D no.6 s.109
• /
• pp.775-788
• /
• 2006

Many disaster monitoring systems are constantly studied to prevent disasters such as environmental pollution, the breaking of a tunnel and a building, flooding, storm earthquake according to the progress of wireless telecommunication, the miniaturization of terminal devices, and the spread of sensor network. A disaster monitoring system can extract information of a remote place, process sensor data with rules to recognize disaster situation, and provide work for preventing disaster. However existing monitoring systems are not enough to predict and prevent disaster, because they can only process current sensor data through utilizing simple aggregation function and operators. In this paper, we design and implement a disaster prevention system to predict near future dangerous area through using outside sensor network and spatial Information. The provided prediction technique considers the change of spatial information over time with current sensor data, and indicates the place that could be dangerous in near future. The system can recognize which place would be dangerous and prepare the disaster prevention. Therefore, damage of disaster and cost of recovery would be reduced. The provided disaster prevention system and prediction technique could be applied to various disaster prevention systems and be utilized for preventing disaster and reducing damages.