• 한국문화재보존과학회:학술대회논문집
• /
• 2004.10a
• /
• pp.15-24
• /
• 2004

The Seokgatap pagoda composed of mainly alkali granite and other minor pink-feldspar granite, fine-grained granite, granodiorite, diorite, gabbro, and tuff. Despite the small loss and damage derived from joints, its peel-off and exfoliation are serious enough to cause the heavy deterioration on the stone surface. The chemical and petrological weathering has partly replaced the original rock-forming minerals with clay minerals and iron oxyhydroxides. Based on the petrogenesis, rock materials of the pagoda is very similar to rocks of Dabotap pagoda and the Namsan granite in the Gyeongju. The central fart of the pagoda has sunken highly, which caused all the corners to split and the structural transformation to become worse. The reverse V-shaped gaps between the materials have broken stones filled in a coarse way. The iron plates inserted between the upper flat stone laid on other stones and tile pagoda body in the north and east side has been exposed in the air and corroded, discoloring of the adjacent stones. The overall diagnosis of the Seokgatap pagoda is the deteriorated functions of the stone materials, which calls for a long-term monitoring and plans to reinforce the stone surfaces. But the main body including the pagoda roof stone needs washing on a regular basis, and the many different cracks should be fixed with glue by using the fillers or hardeners designed for stone cultural properties after removing the cement mortar. In case of the replacement of the stone materials with new stones, it's necessary to examine the pagoda for the center of gravity and support intensity of the materials. The structural stability of the pagoda can be attained by taking a reinforce measure in geotechnical engineering and making a drainage. The ground humidity, which has aggravated weathering and structural instability, should be resolved by setting up a humidity reduction facility. The contamination of lichens and bryophyte around the pagoda and on the surface is serious. Thus biochemical treatments should be given too in order to prevent further biological damages and remove the vegetation growing on the discontinuous planes.

• Journal of Korean Society of Environmental Engineers
• /
• v.32 no.2
• /
• pp.209-218
• /
• 2010

The fifty six components of volatile organic compounds(VOCs) were continuously measured by the hour to see the distributions their of its concentration and the ozone creating contribution of nitric oxides and VOCs in Gamjeon Odor and VOCs Monitoring Network from April to September, 2008. Aromatics occupied 51.3% of VOCs and paraffins, alkanes and olefins came in order. The monthly concentration of VOCs in Gamjeon was high in July and low in September. As for hourly concentration of ozone and nitric oxides, ozone started to increase since 10am having the highest in the daytime, and nitric oxides had the different trend from that of ozone, showing the lowest in the daytime. The photochemical ozone creating potentials(POCPs) of toluene, propane, m/p-xylene, ethylbenzene, and 1,2,4-trimethylbenzene were 30.6%, 10.2%, 9.4%, 7.4% and 5.2% respectively. These five components occupied 62.8% of total POCPs, which means they contributed to the ozone creation mainly. Related with the ozone creating contribution, the ratio of VOCs to NOx was generally under 6 occupied 72.0%, which came under the area coexisting the limit of VOCs. Therefore it is thought that the management of emission source of VOCs is very important for the reduction of ozone.

• Journal of the Microelectronics and Packaging Society
• /
• v.14 no.1
• /
• pp.49-53
• /
• 2007

The direct methanol fuel cell (DMFC) is a promising power source for portable applications due to many advantages such as simple construction, compact design, high energy density, and relatively high energy-conversion efficiency. In this work, an electrochemical methanol sensor for monitoring the methanol concentration in direct methanol fuel cells was fabricated using a thin composite nafion membrane as the electrolyte. We have analyzed the I-V characteristic of the fabricated methanol sensor as a function of methanol concentration, catalyst electrode and platinum(Pt) thickness. The fabricated sensor was analyzed by I-V measurement with various methanol concentration. When we measured the sensor characteristics with 10nm Pt and at 1V, the current value was $1.30{\times}10^{-6}A,\;1.96{\times}10^{-6}A\;and\;2.80{\times}10^{-6} A$ for three methanol concentration of 1M, 2M and 3M, respectively. When the methanol concentration was fixed at 2M, the current value of the fabricated device with Pt layers of 5, 10 and 15 nm thickness was $3.06{\times}10^{-6}A,\;1.96{\times}10^{-6}A\;and\;1.00{\times}10^{-6}A$, respectively. These results lead us to the conclusion that when the methanol concentration increases, the output current increases and when the catalyst electrode become thinner, the current increase more. It showed that, the thinner the catalyst electrode, the more electrochemistry become activation.

• Journal of the Korean Institute of Gas
• /
• v.21 no.2
• /
• pp.41-49
• /
• 2017

Recently, as the number of facilities using chemicals is increasing, the amount of handling is rapidly increasing. However, chemical spills are occurring steadily, and if large quantities of chemicals are leaked in time, they are likely to cause major damage. These industrial complexes use information obtained from a number of sensors to detect and monitor leaking areas, and are used in industrial fields by applying existing fixed sensors to robots and drones. Therefore, it is necessary to propose a sensor placement method at the interface for rapid detection and response based on various leaking scenarios reflecting leaking conditions and environmental conditions of the chemical handling process. In this study, COMSOL was used to analyze the actual accident scenarios by applying the medium parameter to the case of chemical leaks. Based on the accident scenarios, the objective function is selected so that the velocity of each robot is calculated by attaching importance to each item of sensor detection probability, sensing time and sensing scenario number. We also confirmed the feasibility of this method of reliability analysis for unexpected leak accidents. Based on the above results, it is expected that it will be helpful to trace back the leakage source based on the concentration data of the portable sensor to be applied later.

• Korean journal of applied entomology
• /
• v.54 no.4
• /
• pp.443-448
• /
• 2015

The attractant effect to Platypus koryoensis (Murayama), an insect vector of Korean oak wilt disease, was determined using a multi-funnel trap and trap logs treated with ethanol and ethanol extract of the bark of the Mongolian oak Quercus mongolica (Fisher). The number of entrance holes in ethanol and bark ethanol extract treatments was higher than that in the control (blank bottle). However, the number of entrance holes in ethanol and bark ethanol extract treatments was not significantly different. The number of entrance holes in the logs increased with increase in diameter of the logs. The lower part of the trap logs had significantly more number of entrance holes than that in the upper part (p < 0.05). The lower part of trap logs tends to be rarely exposed to direct sunlight resulting in desiccation of the logs, which in turn provides good conditions for microbial growth, a food source for P. koryoensis. The results show, that ethanol could be used effectively in the monitoring and maintenance of P. koryoensis because of the cheaper cost of ethanol than bark ethanol extracts, and thus, having a higher economical advantage. Further research of oak bark ethanol extracts is necessary to improve its efficiency.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.17 no.3
• /
• pp.257-264
• /
• 2011

On April 20, 2010, semi-submersible offshore drilling unit Deepwater Horizon was exploded and sank, and 4.9 million barrels(about 778 thousand tons) of crude oil was spilled into the Gulf of Mexico. As more than one year has been passed since the incident, a lot of investigation reports and lessons learned have been made public and also a lot more will be released soon. This paper studies the final report of the National Commission on "the BP Deepwater Horizon Oil Spill and Offshore Drilling", which was organized by the executive directive of U.S. President Barack Obama, and the interim report of Joint Investigation team of U.S. Coast Guard and BOEMRE of "Report of Investigation into the Circumstances Surrounding the Explosion, Fire, Sinking and Loss of Eleven Members Aboard the Mobile Offshore Drilling Unit Deepwater Horizon". The review is focused on the response to the oil spill. And the paper suggests how to improve national marine pollution response policy. In the paper, the Korean governments is suggested to reinforce the capability for instructing and supervising the responsible party's source control measures, to review how to introduce in-situ burning and vessel of opportunity program into our country, and to continue monitoring on the progress of developments of R&D projects related to oil spill response in the U.S..

• Journal of Wetlands Research
• /
• v.17 no.4
• /
• pp.325-331
• /
• 2015

Due to urbanization and increase in impervious area, changes in natural water circulation system have become a cause of groundwater recharge reduction, streamflow depletion and other hydrological problems. Therefore, this study developed the infiltration planter techniques applied in an LID facility treating roof stormwater runoff such as, performance of small decentralized retention and infiltration through the reproduction of natural water circulation system and use of landscape for cleaning water. Assessment of an infiltration planter was performed through rainfall monitoring to analyze the water balance and pollutant removal efficiency. Hydrologic assessment of an infiltration planter, showed a delay in time of effluent for roof runoff for about 3 hours and on average, 79% of facilities had a runoff reduction through retention and infiltration. Based on the analysis, pollutant removal efficiency generated in the catchment area showed an average of 97% for the particulate matter, 94% for the organic matter and 86-96% and 92-93% for the nutrients and heavy metals were treated, respectively. Comparative results with other LID facilities were made. For this study, facilities compared the SA/CA to high pollutant removal efficiency for the determination to of the effectiveness of the facility when applied in an urban area.

• Economic and Environmental Geology
• /
• v.49 no.3
• /
• pp.167-179
• /
• 2016

Water quality of Oseepchun, Dogye area, was investigated quantitatively for its origin and hydrogeochemistry in relation to the influence of groundwater. Groundwater appears to be the principal source of Oseepchun from the water-quality monitoring data including redox potentials, composition of dissolved ions and their correlations, hydrogen and oxygen stable isotopic ratios, and the distribution and occurrence of contaminants. Water-quality type of the surface water was grouped by the water-rock interactions as $Ca-HCO_3$ type originated from carbonated bed-rocks in the Joseon Supergroup, (Ca, Mg)-$SO_4$ type related with dissolution of surfide minerals in coal beds of Pyeongan Supergroup, and (Ca, Mg)-($HCO_3$, $SO_4$) type of the mixed one. Locally water pollution occurs by high $SO_4$ from mine drainage and $NO_3$ from waste-treatment facility. Intensive precipitation in summer has no effect on the water type of Oseepchun, but increases the inflow of nitrate and chloride originated from land surface. Results of this study direct that groundwater-surface water interaction is intimate, and thus surface-water resource management should begin with groundwater characterization.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
• /
• v.13 no.5
• /
• pp.436-442
• /
• 2020

ESS(energy storage system) has recently become an important power source in various areas due to increased renewable energy resources. The more ESS is used, the less the effective capacity of the ESS. Therefore, it is important to manage the remaining useful lifetime(RUL). RUL can be checked regularly by inspectors, but it is common to be monitored and estimated by an automated monitoring system. The accurate state estimation is important to ESS operator for economical and efficient operation. RUL estimation model usually requires complex mathematical calculations consisting of cycle aging and calendar aging that are caused by the operation frequency and over time, respectively. A lightweight RUL estimation model is required to be embedded in low-performance processors that are installed on ESS. In this paper, a lightweight ESS RUL estimation model is proposed to operate on low-performance micro-processors. The simulation results show less than 1% errors compared to the original RUL model case. In addition, a performance analysis is conducted based on ATmega 328. The results show 76.8 to 78.3 % of computational time reduction.

• Journal of the Korean Institute of Gas
• /
• v.12 no.2
• /
• pp.38-41
• /
• 2008

In this research, we propose a new method for tracking the release rate using the concentration data obtained from the sensor. We used a sensor network that has already been set surrounding the area where hazardous gas releases can occur. From the real-time sensor data, we detected and analyzed releases of harmful materials and their concentrations. Based on the results, the release rate is estimated using the neural network. This model consists of 14 input variables (sensor data, material properties, process information, meteorological conditions) and one output (release rate). The dispersion model then performs the simulation of the expected dispersion consequence by combining the sensor data, GIS data and the diagnostic result of the source term. The result of this study will improve the safety-concerns of residents living next to storage facilities containing hazardous materials by providing the enhanced emergency response plan and monitoring system for toxic gas releases.