• Journal of the Korean Institute of Gas
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• v.12 no.4
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• pp.1-7
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• 2008

In the last five years, 36 people died and 79 were wounded because of carbon monoxide poisoning accident. A CO poisoning accident is higher than any other gas accident in the rate of deaths/incidents. Most of these CO poisoning accidents were caused by defective exhaust tube in the old gas boiler and multi-use facility. In this study, the spread mechanism of CO gas released from leakage hole of exhaust tube was analyzed by concentration measuring test. A CO gas leaked form exhaust tube in a building was the highest concentrated near the ceiling. CO alarm sets installation test confirmed that the alarm sets near the ceiling operated first, and the bottom and middle sets operated after $30{\sim}40$ minutes. Through these experiments, the reasonable installation location of CO alarm was made certain and suggested.

• The Journal of the Korea Contents Association
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• v.14 no.6
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• pp.44-53
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• 2014

This study seeks to analyze vertical integration structure of Korean popular music market focused on corporation concentration and production system by applying production of culture perspective of Peterson, Subject of analysis is Melon weekly music chart(2000-2013), which is No.1 digital music distributor. The result showed vertical integration structure of Korean popular music industry was different from America. Vertical integration of American major was based on open system to be responsible for promotion and distribution by M&A of independent label but entrusted them-with total production to cope-with uncertainty of music market. On the other hand, Korean system was in charge of pure distribution only as digital service provider and it showed modified vertical structure because traditional value chain was destroyed by changing digital music environment. Especially found seriousness of oligopoly by distribution company of conglomerate affiliation. and this is harm against building healthy industry ecosystem in creative economy era and it needs improvement through study of advanced case, open system.

• Transactions of the Korean hydrogen and new energy society
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• v.20 no.5
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• pp.378-383
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• 2009

Hydrogen is the primary fuel in fuel cell systems. Because of high inflammation and explosion possibility of hydrogen, fuel cell systems require safety measures to prevent hydrogen hazard upon leakage. In this study, a model enclosure was made by referring to a commercial residential fuel cell system and hydrogen leakage experiments and computational simulations were conducted therein. Hydrogen was injected into the cavity through leakage holes located at the bottom while its flow rate was precisely controlled using MFC. The transient sensor signals from hydrogen sensors installed inside the enclosure were recorded and analyzed. The hydrogen sensor signals showed different delay times depending on their position relative to a leakage point, which indicated that hydrogen generally moves upward and accumulates at the upper region of a closed cavity. The inflammable regions with hydrogen concentration over 4% LEL were observed to locate near the leakage hole initially, and broaden towards the upper cavity region afterward. The simulation result showed that detection time at the hydrogen sensor was similar to the pattern of experimental results. However, the maximum concentration of hydrogen had a gap between experiment and simulation at detect point due to measurement errors and reaction rate.

• Journal of the Korean Institute of Gas
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• v.23 no.6
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• pp.25-32
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• 2019

In many mass-consumption gas facilities, natural gas is not supplied through the pipeline of the gas corporation. LNG is supplied from the gas corporation through the tank lorry to be vaporized. In order to prevent human or property damage due to gas leakage at these facilities, a study was conducted to analyze the concentration of odorant injected at the initial and consumption points. An analysis was performed to confirm the change in odorant concentration according to the pipe position in the gas facility when a constant flow rate flowed. For this study the gas samples were taken with aluminium cylinders(4.5 L) which were created a vacuum at the pressure regulator in which the odorants was injected and the points using the gas. Odorant levels of the samples were analyzed by Gas chromatography(Main Body : Agilent 7890A, Detector : ANTEC 7090).We suggest that the small facilities using LNG need to make the management system by the types of facilities for maintaining the odorization system.

• Journal of Korean Society on Water Environment
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• v.23 no.6
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• pp.863-871
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• 2007

Spectroscopic characteristics of river water from four major watersheds in the Ulsan area were measured to examine their potential for estimating water quality parameters. The total 176 river samples were collected from 44 sites of small streams within the watersheds during the year 2006. Spectroscopic characteristics investigated included protein-like fluorescence (FLF) intensity, fulvic-like fluorescence (FLF) intensity, terrestrial humic-like fluorescence (TLF) intensity, UV absorbance at 254 nm, and UV absorbance difference at 220 nm and 254 nm. Protein-like fluorescence intensity showed linear relationships with biochemical oxygen demand (BOD), chemical oxygen demand (COD), total phosphorous (TP) concentrations of the samples with the correlation of 0.784, 0.779, and 0.733, respectively. Due to the UV absorption characteristics of nitrate at 220 nm, UV absorbance difference at 220 nm and 254 nm was selected to represent total nitrogen (TN) concentration. Exclusion of some samples with PLF intensity higher than 5.0 improved the correlation between the UV absorbance difference and TN as demonstrated by the increase of the correlation coefficient from 0.392 to 0.784. Instead, for the samples with PLF intensity lower than 5.0, the highest correlation of TN was achieved with UV absorbance at 254 nm. The results suggest that PLF intensity could be used as the estimation index for BOD, COD, and TP concentration of river water, and as the primary screening index for the prediction of TN using UV absorbance difference. Some BOD-based water quality levels among the river water were statistically discriminated by the PLF intensity. Low p-values were obtained from the t-tests on the samples with the first level and the second level (p=0.0003) and the samples with the second and the third levels (p=0.0413). Our combined results demonstrated that the selected spectroscopic characteristics of river water could be utilized as a tool for on-site real-time monitoring and/or the primary estimation of water quality.

• Economic and Environmental Geology
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• v.41 no.4
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• pp.393-403
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• 2008

Hydrogeochemistry of groundwater was studied in order to identify the influence of cow manure, distributed to a farmland as organic fertilizer, on nitrate concentrations in shallow groundwater and its spatio-temporal variations. From monitoring wells, water levels were measured using automatic data loggers, and water samples collected and analyzed in Feb., April, June and Oct. 2007. The average electric conductivity and concentration of nitrate in the groundwater show the highest levels in April and decline in subsequent sampling times. Decreases in dissolved oxygen(DO) and nitrate concentrations from April to Oct. and corresponding increases in $HCO_3$ concentrations indicate denitrification processes by microorganisms. Spatial variation of nitrate concentration appeared to be affected by the redox conditions of groundwater controlled by geochemical reactions of Mn, Fe and DOC contents.

• Journal of the Korean Institute of Gas
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• v.13 no.5
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• pp.15-19
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• 2009

In this study, the transient responses of hydrogen sensor against abrupt hydrogen release was experimentally studied for three most common types of hydrogen sensors, i.e. the semiconductor type, electrochemical type, and catalytic combustion type. The experimental study was conducted using a 1% hydrogen - 99% nitrogen mixture gas as the standard gas, while the temperature and relative humidity (RH) of the mixture gas was varied from $25^{\circ}C$ to $50^{\circ}C$ and from 50% to 100%, respectively. The temperature of the mixture gas was found to influence the output signal levels of hydrogen sensors, especially the catalytic combustion type. However, the effect of RH on the sensor response was not noticeable in the present experimental study. Thus, the signal levels of hydrogen sensors, in case of catalytic gas sensor need to be calibrated dependent on gas temperature, when the accurate determination of hydrogen concentration is important.

• Journal of Korean Society on Water Environment
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• v.27 no.4
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• pp.523-532
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• 2011

In this study, from 2004 to 2008 influents and discharging effluents from 241 municipal public sewage treatment plants were surveyed. Statistics including average, Coefficient of Variation (CV) and Coefficient of Reliability (COR) for each season, time series analysis for removal efficiency and water quality of effluents, and a comparison of the effluent standards in Korea and other countries were presented. The average concentrations of TN and TP in influents. during winter season were 32.6 and 3.78 mg/L and during other season were 30.8 and 3.61 mg/L in 2008, respectively. The average TN concentration on the basis of the maximum monthly concentrations in the effluents during winter season ranged from 14.2~17.4 mg/L and during other season ranged from 12.2~14.8 mg/L. The TP concentration in the effluents depending on the each season was no big difference. TN removal efficiency decreased from Jan. to Feb. and TP removal efficiency decreased in Jan., Jun and July. Maximum COR during winter season were 0.61 but the COR for TN and TP during other season ranged from 0.96~1.48 and 1.09~1.81, respectively, due to big difference in the standard for TN and TP in effluents depending on the season. TN and TP standards for effluent of sewage treatment during winter season in Korea was much higher than those in other countries. Therefore the lower effluent standards during winter season is essential for the water quality improvement.

• Journal of the Korean Society of Visualization
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• v.19 no.3
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• pp.84-91
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• 2021

Effervescent tablets generate gas bubbles when chemical reaction occurs between water and tablets. Most of previous studies have been focused on pharmaceutical characteristics of tablets. However, for their applications in disinfectants, cleaners, and pesticides, physical characteristics of bubbles released from the effervescent tablets when they are in water are important. In this study, we experimentally investigated the characteristics of microbubbles generated by an effervescent tablet made of sodium bicarbonate and tartaric acid using PDPA and high-speed camera. Microbubbles were generated using different weights of effervescent tablet as well as in different water temperature. The experimental study shows increase in reaction time, bubble concentration and rise velocity as the weight of effervescent tablet increases from 1 to 20 g. The decrease in average bubble diameter was observed when the temperature of water increased from 25 to 45 ℃. Further, reaction time varies inversely with increase in water temperature, while bubble rise velocity is directly proportional to increase in water temperature. Effervescent table continuously generates the bubble with approximately constant diameter (235 ㎛) in the water. However, bubble concentration and bubble rise velocity decreased over time.

• The Plant Pathology Journal
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• v.38 no.3
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• pp.182-193
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• 2022

Turfgrass, the most widely grown ornamental crop, is severely affected by fungal pathogens including Sclerotinia homoeocarpa, Rhizoctonia solani, and Magnaporthe poae. At present, turfgrass fungal disease management predominantly relies on synthetic fungicide treatments. However, the extensive application of fungicides to the soil increases residual detection frequency, raising concerns for the environment and human health. The bacterial volatile compound, 2,3-butanediol (BDO), was found to induce plant resistance. In this study, we evaluated the disease control efficacy of a combination of stereoisomers of 2,3-BDO and commercial fungicides against turfgrass fungal diseases in both growth room and fields. In the growth room experiment, the combination of 0.9% 2R,3R-BDO (levo) soluble liquid (SL) formulation and 9% 2R,3S-BDO (meso) SL with half concentration of fungicides significantly increased the disease control efficacy against dollar spot and summer patch disease when compared to the half concentration of fungicide alone. In field experiments, the disease control efficiency of levo 0.9% and meso 9% SL, in combination with a fungicide, was confirmed against dollar spot and large patch disease. Additionally, the induction of defense-related genes involved in the salicylic acid and jasmonic acid/ethylene signaling pathways and reactive oxygen species detoxification-related genes under Clarireedia sp. infection was confirmed with levo 0.9% and meso 9% SL treatment in creeping bentgrass. Our findings suggest that 2,3-BDO isomer formulations can be combined with chemical fungicides as a new integrated tool to control Clarireedia sp. infection in turfgrass, thereby reducing the use of chemical fungicides.