• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.13 no.2
• /
• pp.139-148
• /
• 2001

Phenomena induced by waves, such as overtopping, sediment transport, vibration/fluctuation and destruction of structures are highly influenced by the directionality of wave propagation. These phenomena are often dominated by non-linearity, and so hydraulic model experiments are widely adopted for stability analysis rather than numerical modeling, Thus, stability ofrubblc mound breakwaters(RMB) due to wavc directionality was experimentally investigated in this study. The incident wave angle $30^{\circ}$ was found more risky on the damage rate of RMB under directional regular waves, and the incident wave angle $40^{\circ}$ was found relatively risky under directional irregular waves. These results clarified the wave directionality effect on the stability ofRMB, These facts were found correspondent to the occurrence of the peak between $20^{\circ}$-$40^{\circ}$ with the directional frequency distribution of lIlO maximum water particle velocity.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.39 no.spc1
• /
• pp.214-222
• /
• 2006

Dominant species of macrobenthos were analyzed based on differentiation of three distinct methods: the density based method, the biomass based method and LeBris method, by considering the frequency of occurrence using quantitative data collected over 5 years (1993-1998) at 21 stations in Chonsu Bay. Sedimentary environments as well as species composition and diversity showed the spatial and temporal distribution patterns. The ranks of dominant species as determined by the density based method were more similar to the results by the LeBris method than to those from the biomass based method. Considering the temporal variation, LeBris method were more efficient than any other methods for the determination of dominant species in Chonsu Bay. Lumbrineris longifolia, Theora fragilis, and Moerella jedoensis were recognized by all three methods. A one-way analysis of variance indicated spatial distributions patterns among most of the dominant species. These species showed positive correlations to sedimentary parameters such as mean grain size. However, T. fragilis and Paraprinospio pinnata showed the temporal patterns in their distribution, and were also correlated to the benthic environment, organic content and dissolved oxygen. Some dominant species, e.g., T. fragilis, S. scutata, G. gurjanovae proved to be useful benthic indicators based on the environmental variations determinated by long-term benthic ecological monitoring in Chonsu Bay.

• Fire Science and Engineering
• /
• v.20 no.2 s.62
• /
• pp.54-63
• /
• 2006

The number of forest fire under various conditions such as year, month, time, day of the week, region, damaged species, cause, and damaged area are checked, and the statistics of the forest fire causing materials in recent 14 years ('91-'04) are analyzed. The result shows that the year majority of forest fires had happened in last 14 year was 2001 and most of forest fire occurred in April, Sunday, around 14:00 to 15:00. The most damaged region is Gyeongsangbuk-Do, followed by Gangwon-Do, Jeollabuk-Do, and Gyeonggi-Do. The most damaged species is pine tree. The main causes of forest fires are accidental fire and incineration of a field boundary; however, recently, incendiarism is increased. The result of analysis on the damaged area shows that small fires under 5 ha occurred most frequently and large fires (over 30 ha) occurred mostly in Kangwon province (44.2%). The result also shows that the large forest fires (1,113 minutes) require 7.5 time more than the small forest fires (148 minutes). Especially, since average damaged area caused by large forest fire was about 470 ha per incident.

• Proceedings of the Korean Institute Of Construction Engineering and Management
• /
• 2008.11a
• /
• pp.475-480
• /
• 2008

In BTL project, the operation cost covering upcoming 20 years is usually alloted more than construction cost although its plan is made in short time. Therefore, it is a key issue to forecast and to analyze operation risks in the process of making contract in order to successfully finish the BTL project and to ensure the profitability of business. However, only a few domestic professional management companies are capable to carry out funding and facility management. To manage the potential risks efficiently in BLT project, it's essential to prioritize the risk factors by means of considering economical risk level, non-economical risk level and occurrence frequency. Thus, this study suggests risk analysis model for improving efficiency of BTL project from operation company's perspective by means of survey. The suggested risk analysis model is expected to establish a risk management strategy which can improve the efficiency of management affairs in BTL project.

• Journal of the Korean Data and Information Science Society
• /
• v.23 no.4
• /
• pp.717-725
• /
• 2012

Data mining is a method to find useful information for large amounts of data in database. One of the well-studied problems in data mining is exploration for association rules. Association rule mining searches for interesting relationships among items in a given database by support, confidence, and lift. If we use the existing association rules, we can commit some errors by information loss not to consider the size of occurrence frequency. In this paper, we proposed a new association rule thresholds considering the number of possible rules of interest items and compare with existing association rule thresholds by example and real data. As the results, the new association rule thresholds were more useful than existing thresholds.

• Fire Science and Engineering
• /
• v.5 no.3
• /
• pp.5-14
• /
• 1991

Now a days, according that the occurrence of industrial disaster is on the increase, the necessity of protective goods is increasing. Specially estimate of safety helmet for protect of head is very important. On this, in this paper, amplification ratio and natural frequencies of fire safety helmet and general safety helmet are estimated by falling impect test and frequency analysis. Also. trend of damping is estimated by using these test results. And we know that the fire safety helmet is more safe than general safety helmet for protect of head.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2014.05a
• /
• pp.479-482
• /
• 2014

Nowadays open-source hadoop systems have been using widely to efficiently manage a fast-growing big data. Hadoop systems consist of distributed file processing system called HDFS (Hadoop Distributed File System) and distributed parallel processing system called MapReduce. The MapReduce reads and processes big data from HDFS and then processed results are written in HDFS again by the MapReduce. Such a processing method has different system structure respectively according to hadoop version. Therefore, this paper shows analysis results for performance of hadoop systems. For this, we devise a way which monitors hadoop systems and measure occurrence frequency of processes, threads, and variables generated in hadoop system itself using the devised way. So, by using the measured results as analysis indicator, we help the indicator predict inner performance of hadoop systems.

• Journal of Korean Society of Forest Science
• /
• v.100 no.3
• /
• pp.417-422
• /
• 2011

In general, forest tending work contributes to preventing landslides by enhancing forest health. In order to quantify beneficial effects of forest tending, landslide occurrences in forest tending area and those in non-forest tending area were compared and analyzed. The landslide had been hit hard in Inje and Pyeongchang county, Gangwon province, following Typhoon 'Bilis' on July 15, 2006. Data on forest tending of Pinus koraiensis and Larix kaempferi stands were acquired from the Inje National Forest Station, North regional forest service. The rate of landslide occurrence was increased sharply just after forest tending work and was decreased as time goes by. The analysis also found that the change in landslide frequency was slight by age class in the non-forest tending area, while it decreased as age class increased in the forest tending area.

• Journal of the Korean Institute of Gas
• /
• v.26 no.1
• /
• pp.41-49
• /
• 2022

Chemicals are widely used throughout society, and usage is expected to increase in the future. As a result, various accidents related to chemicals and dangerous substances are occurring, and the frequency of occurrence is expected to continue to increase. Thus, it is expected that this study will present problems and improvement directions through analysis of each associated agency's accident report and management system, and improve the research input system to increase efficiency in collecting and statistical calculation of chemical and hazardous accident.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2022.05a
• /
• pp.334-334
• /
• 2022

Improvement of old-fashioned rain gauge systems for automatic, timely, continuous, and accurate precipitation observation is highly essential for weather/climate prediction and natural hazards early warning, since the occurrence frequency and intensity of heavy and extreme precipitation events (especially floods) are recently getting more increase and severe worldwide due to climate change. Although rain gauge accuracy of 0.1 mm is recommended by the World Meteorological Organization (WMO), the traditional rain gauges in both weighting and tipping bucket types are often unable to meet that demand due to several existing technical limitations together with higher production and maintenance costs. Therefore, we aim to introduce a newly developed and cost-effective hybrid rain gauge system at 0.1 mm accuracy that combines advantages of weighting and tipping bucket types for continuous, automatic, and accurate precipitation observation, where the errors from long-term load cells and external environmental sources (e.g., winds) can be removed via an automatic drainage system and artificial intelligence-based data quality control procedure. Our rain gauge system consists of an instrument unit for measuring precipitation, a communication unit for transmitting and receiving measured precipitation signals, and a database unit for storing, processing, and analyzing precipitation data. This newly developed rain gauge was designed according to the weather instrument criteria, where precipitation amounts filled into the tipping bucket are measured considering the receiver's diameter, the maximum measurement of precipitation, drainage time, and the conductivity marking. Moreover, it is also designed to transmit the measured precipitation data stored in the PCB through RS232, RS485, and TCP/IP, together with connecting to the data logger to enable data collection and analysis based on user needs. Preliminary results from a comparison with an existing 1.0-mm tipping bucket rain gauge indicated that our developed rain gauge has an excellent performance in continuous precipitation observation with higher measurement accuracy, more correct precipitation days observed (120 days), and a lower error of roughly 27 mm occurred during the measurement period.