• Journal of Korean Society of Forest Science
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• v.90 no.3
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• pp.242-248
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• 2001

Changes in land-use can affect soil organic matter content and fertility. We compared total soil carbon and nitrogen concentrations, soil respiration, and nitrogen availability under three land-use types in central Korea; conversion of old rice field to natural willow-maple (Salix-Acer) forest, conversion of old field to artificial Korean pine (Pines koraiensis) forest, and indigenous oak (Quercus spp.) forest. After 20 years of fallow the area of rice field conversion to forest had higher soil carbon and nitrogen concentrations in the soil depth of 0-10cm and 10-20cm than the areas of field conversion to Korean pine forest and indigenous forest. In general, soil carbon and nitrogen concentrations decreased with soil depth. Organic matter accumulation as a balance of input and decomposition seemed to be higher in the soil of previous rice field, and carbon and nitrogen accumulation was largely confined to the topsoil. Soil respiration rates were greatest at the area of rice field conversion to forest, and appeared to be related to soil carbon and soil moisture. Soil nitrogen availability measured by the ion exchange resin bag method differed significantly among land-use types; soil inorganic nitrogen ($NH_4{^+}+NO_3{^-}$) and ammonium availability were highest in the soil under indigenous oak forest followed by conversion of old field to artificial Korean pine forest and conversion of old field to natural willow-maple forest.

• Korean Journal of Agricultural and Forest Meteorology
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• v.7 no.1
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• pp.107-114
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• 2005

Soil CO₂ emission is one of the primary components in carbon balance of terrestrial ecosystems. In soil CO₂ flux measurements, chamber method is currently the most common technique. Prior to compare or synthesize the data collected from different chamber methods, potential biases must be quantified for each measurement system. We have conducted an intercomparison experiment among four closed dynamic chamber systems and an automatic open-closed chamber system in a temperature-controlled phytotron. Due to the disturbed CO₂ concentrations inside the phytotron during the measurements with closed dynamic chambers and the changes in soil water content, the interpretation of the data was difficult to quantify the biases of individual methods. However, the experiment provided not only valuable information on the performance characteristics of the five instruments to varying soil temperature and CO₂ concentration but also useful insights for better designs and strategy for future intercomparison in a controlled environment.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 1999.10a
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• pp.433-435
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• 1999

대기 중에 존재하는 에어로졸은 물리ㆍ화학적인 반응에 의하여 생성되며 금속, 수용성 성분을 비롯한 탄소입자 등으로 복잡하게 이루어져 있다. 이들은 대기중에서 시정감소와 광산란을 야기시킬 뿐 아니라 인체에 흡입되어 호흡기질환등을 야기 시킨다(Holt,1988). 또한 분진은 입자의 크기가 작을수록 상대적으로 표면적이 증가하여 각종 유해 대기오염물질과 흡착하여 인체에 악영향을 미친다(Simpson, 1992; John et al., 1990).(중략)

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2002.11a
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• pp.112-113
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• 2002

주물작업이란 용융된 금속을 미리 준비한 주형에 부어 원하는 형태의 주물을 만드는 금속성형작업으로서, 생산 공정에서 고열을 이용하여 금속을 용해, 주조하는 등의 작업 특성상 부유분진의 발생이 필연적이며, 일산화탄소, 금속 흄, 휘발성 코울타르 피치, 소음 및 진동, 고열, 전리방사선 등의 유해인자로 인한 피해가 극심하다. 특히 분진은 주물의 생산공정 중 용해, 조형, 탈사 및 후처리 등 거의 전 공정에서 발생되며, 결정형 유리규산(SiO$_2$)을 다량 함유하고 있어 인체에 흡입되었을 때, 건강의 악화 및 직업병의 원인으로서 작업 능률을 떨어뜨리는 요인으로 작용하고 있다(Burgess, 1995). (중략)

• Fire Science and Engineering
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• v.27 no.5
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• pp.44-56
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• 2013

This research is to identify how much toxic combustion gases are produced from Korea standardized real fire test (Class A&B) by using Room Corner Tester (RCT) and how much those gases are possibly dangerous to testing personnel by estimating the level of carboxyhemoglobin (% COHb). It is confirmed that testing personnel can be affected as more than 40% COHb from Class A 9th and 10th rating in respiration minute volume (RMV) 2 and from Class A 5th to Class A 10th rating in RMV 3 during the time for initial three minutes. Also, in the case of Class B real fire tests, although it is considered rather safe for the initial 1 minute, testing personnel can be affected as more than 20% COHb from Class B 16th to 20th rating in RMV 3 during total test time. Currently, the Korea standard is only focusing on the protection measures against the heat, but the it is neglecting the protection measures against toxic combustion gases. Therefore, according to this study, it is strongly recommended that testing personnel should wear a self-contained breathing apparatus, or the equivalence depending on the real fire test rating.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.2
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• pp.253-259
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• 2012

Disposal of high amount of coal combustion by-products, such as fly ash and bottom ash, is of a great concern to the country, due to the huge treatment cost and land requirement. On the other hand, those coal-ash wastes are considered to have desirable characteristics that may improve physical, chemical, and biological properties of soils. Especially, compared with fly ash, bottom ash has a larger particle size, porous surface area, and usable amount of micronutrients. In the present study, we examined bottom as a soil amendment for mitigating $CO_2$ emission and enhancing carbon sequestration in soils fertilized with organic matter (hairy vetch, green barely, and oil cake fertilizer). Through laboratory incubation, $CO_2$ released from the soil was quantitatively and periodically monitored with an enforced-aeration and high-temperature respirometer. We observed that amendment of bottom ash led to a marked reduction in $CO_2$ emission rate and cumulative amount of $CO_2$ released, which was generally proportional to the amount of bottom ash applied. We also found that the temporal patterns of $CO_2$ emission and C sequestration effects were partially dependent on the relative of proportion labile carbon and C/N ratio of the organic matter. Our results strongly suggest that amendment of bottom ash has potential benefits for fixing labile carbon as more stable soil organic matter, unless the bottom ash contains toxic levels of heavy metals or other contaminants.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.3
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• pp.323-329
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• 2005

In this paper, performance of a hybrid sequential aerobic-anaerobic natural system was investigated. Continuous aerobic and anoxic conditions were created by alternatively placing waste stabilization pond (WSP) and wale. hyacinth pond (WHP). Two pilot-scale treatment lines were built and operated; The first consists of WSP integrated with WHP and the second of WSP connected with Dark Pond(DP), namely control system ponds which were used to examine the effects of water hyacinth on nitrification and de-nitrification. The overall performance in nitrogen was 86% reduction in WSP-WHP and 36% in WSP-control pond system. Nitrogen was mostly removed by nitrification and de-nitrification which simultaneously occurred in the same water hyacinth ponds. For the de-nitrification, benthic layer was found out to be adequate support as a carbon source. In addition, WSP-WHP system was very effective in reducing phosphorus. Overall P removal efficiency in WSP-WHP is 81%, while it is only 16% in WSP-control. difference in phosphorus reduction between those two systems is thought to be caused by the plants and probably their roots producing extra-cellular materials, but these aspects need to be further studied.

• Journal of Animal Environmental Science
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• v.18 no.1
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• pp.19-24
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• 2012

The first objective of this study is to estimate emission coefficient of organic carbon regarding its inflow and discharge for dairy farm through reviewing domestic and foreign literature published or reported previously. Its second objective is to provide fundamental data to establish carbon cycle system related to livestock production. Based on literature review, emission coefficients by inflow of organic carbon into dairy farm were 5.9 ton C/head/year for feedstuff ingestion by milk cow, 2.3 ton C/head/year for recycling manure compost of milk cow to grassland, 318 g C/$m^2$/year for contents in grassland, 145 g C/$m^2$/year for contents in fodder crop, and 17 g C/$m^2$/year for $CO_2$ uptake by fodder crop, respectively. on the other hand, emission coefficients by discharge of organic carbon from dairy farm were 2,9 ton C/head/year for emission of $CO_2$ and $CH_4$ by respiration and burp of milk cow, 0.4 ton C/head/year for emission of $CO_2$ and $CH_4$ by decomposition of organic carbon in manure of milk cow, 440 g C/$m^2$/year for emission of $CO_2$ from grassland, and 0 for elution of organic carbon in grassland into underground water, respectively.

• Journal of Science Education
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• v.45 no.3
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• pp.275-291
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• 2021

The purpose of this study is to analyze the level and characteristics of system thinking of middle and high school students on cycle of matter in the Earth system considering the impact of human activities on the cycle. For this purpose, we developed items for assessment and assessment rubric through the analysis of 2015 revised curriculum and applying systems thinking, respectively. Middle and high school students who participated in the Korea Earth Science Olympiad were the subjects of this study. The level of system thinking was determined using the assessment rubric for student responses collected using items for assessment. The characteristics of system thinking were identified using word analysis. Based on these, the improvement of the curriculum considering the impact of human activities was discussed. The results of the study are as follows: first, the system thinking level of most secondary school students was low in identifying or classifying system elements for matter cycle, and high levels, such as system relationship or generalization of patterns, were found to be relatively small. It was found that students had a higher level of system thinking in the carbon cycle than in the water cycle. Second, in terms of the characteristics of system thinking about water cycle, water was recognized as a major system element and mainly related with evaporation between atmosphere and other system elements. Whereas, in the carbon cycle, carbon dioxide was regarded as a major system element, and photosynthesis and respiration were represented in relation with the biosphere. Third, for education considering the impact of human activities on the matter cycle in the Earth system, it is proposed improving the curriculum considering the socio-ecological system by extending the existing earth system.

• Fire Science and Engineering
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• v.26 no.3
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• pp.40-48
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• 2012

Fire patterns have been used to determine the origin and cause of fires in every setting imaginable. However, it is very difficult to identify fire patterns and causes from the fire-damaged remains of a devastated structure. If someone was killed by the fire, it is possible to identify fire patterns by analyzing the Hb-CO concentration in charred bodies of deceased as well as the pace of the fire. For example, a low level of Hb-CO concentration in the charred bodies indicate a rapid fire with accelerants and the death was caused by severe heat and thick toxic fumes. However, a high level of Hb-CO concentration in the charred bodies demonstrates that the fire was slow and/or there was a flameless form of combustion. Thus, it is possible to identify fire patterns through analyzing the level of Hb-CO concentration on the dead from the fire. In this study, the Hb-CO concentration in the charred bodies was from 3 % at the case of gas burning oneself to death to 93 % at the death caused by smoldering fire.