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In 2014, the United Nations Framework Convention on Climate Change (UNFCCC) agreed to submit the Intended Nationality Determined Contributions (INDCs) at the conference of parties held in Lima, Peru. Then, the South Korean government submitted the INDCs including GHGs reduction target and reduction potential on July, 2015. The goal of this study is to predict GHGs emission and to analyze reduction potential in agricultural sector of Korea. Activity data to estimate GHGs emission was forecast by Korea Agricultural Simulation Model (KASMO) of Korea Rural Economic Institute and estimate methodology was taken by the IPCC and guideline for MRV (Measurement, Reporting and Verification) of national greenhouse gases statistics of Korea. The predicted GHGs emission of agricultural sectors from 2021 to 2030 tended to decrease due to decline in crop production and its gap was less after 2025. Increasing livestock numbers such as sheep, horses, swine, and ducks did not show signigicant impact the total GHGs emission. On a analysis of the reduction potential, GHGs emission was expected to reduce 253 Gg CO₂-eq. by 2030 with increase of mid-season water drainage area up to 95% of total rice cultivation area. The GHGs reduction potential with intermittent drainage technology applied to 10% of the tatal paddy field area, mid-drainage and no organic matter would be 92 Gg CO₂-eq. by 2030.
The chamber method is widely used for measuring methane emission from paddy rice fields. The closed static chamber has advantages of easy installation and removal in the field and low manufacturing cost. However, the manual chamber method requires a lot of labor and has a limited sampling time and frequency. To overcome the disadvantages of the manual chamber, the auto‐chamber system is used for measuring methane emission. We compared the differences in methane flux between the auto‐chamber and manual chamber. To investigate methane emissions by the two methods, a chamber was installed for each of the following treatments : control without rice straw (NA), spring plowing after autumn rice straw application (SPRA) and autumn plowing after autumn rice straw application (APRA). The total methane emission was lowest in the control and highest in APRA with both methods. There was no significant difference in total methane emission between the methods, but dynamic fluctuation in methane with temperature change was accurately measured in the auto‐chamber. Measuring methane emission with an auto‐chamber system is expected to reduce uncertainty and increase accuracy, accompanied by labor reduction.
Greenhouse gases (GHGs) from agricultural sector were categorized in a guideline book from Intergovernmental Panel on Climate Change (IPCC) as methane from rice paddy fields and nitrous oxide from agricultural soils. In general, GHG emissions were calculated by multiplying the activity data by emission factor. Tier 1 methodology uses IPCC default factors and Tier 2 uses country specific emission factors (CS). The CS and Scaling factors (SF) had been developed by NAAS (National Academy of Agricultural Science) projects from 2009 to 2012 to estimate how the advanced emissions. The purpose of this study was to compare GHG emissions calculated from IPCC default factors and NAAS CS and SF of agricultural sector in Korea. Methane emissions using CS and SF in rice paddy field was about 79% higher than those using IPCC default factors. In the agricultural soils, nitrous oxide emissions using CS from the 5 crops were about 40% lower than those using IPCC default. Except those 5 crops, approximately up to 52% lower emissions were calculated using CS compared to those using IPCC default factors. The total GHG emissions using CS and SF were about 33% higher than those using Tier 1 method by IPCC default factors.
Nitrous oxide is one of the main sources of greenhouse gases and its concentration has increased from 273 ppb in 1,750 to 315 ppb in 2005. Specially, nitrogen fertilizer used in agricultural soils is considered as an important source of atmospheric N2O emission. This study was conducted to estimate the difference of nitrous oxide emission as chamber position on furrow and ridge and crop existence in gas sampling chamber on upland. Four treatments used in this experiment were ① no-fertilizer without crop in chamber on ridge, ② fertilizer application without crop in chamber on ridge, ③ fertilizer application with crop in chamber on ridge, ④ fertilizer application without crop in chamber on ridge and furrow. Nitrous oxide emission at fertilizer application with crop in chamber on ridge were the highest while were the lowest at no-fertilizer without crop in chamber on ridge. There was no significant difference of nitrous oxide emission by chamber position, but total emission by crop existence in chamber was significant difference. Therefore, in order to estimate greenhouse gases emission using chamber method in upland, it should be considered in correlation with crop existence in chamber and characteristic changes like as the soil moisture, microbial flora by crop growth stage.
This research was conducted to estimate methane emission from paddy field of 16 local government levels using the DNDC(DeNitrification-DeComposition) model from 1990 to 2010. Four treatments used in DNDC model for methane emission calculations were ① midseason drainage with rice straw, ② midseason drainage without rice straw, ③ continuous flooding with rice straw, and ④ continuous flooding without rice straw. Methane emissions at continuous flooding with rice straw were the highest (471 kg C ha?1) while were the lowest (187 kg C ha?1) at midseason drainage without rice straw. The average methane emission for 21 years was the highest (1,406 Gg CO2-eq.) in Jeonnam province because of its large cultivation area. Jeju province had the highest the average methane emission per unit area due to the organic content in soil.
VoIP는 인터넷을 통해 사용자에게 다양한 서비스를 제공 하며, 기존의 서비스들 보다 저렴하여 새로운 비즈니스 모델로 주목받고 있다. 하지만 VoIP는 인터넷을 이용하기 때문에 기존의 인터넷에서 문제가 되었던 보안 위협이 VoIP에서도 쉽게 이루어질 수 있는 문제점을 가지게 되었다. 또한 기존의 전화망에서 문제가 되지 않았던 새로운 보안 위협들이 VoIP에서 발생하였다. 다행히 지금은 VoIP에서 나타났던 많은 문제점들에 대한 해결책들이 제시 되었으며, 그 외의 보안 위협들은 대부분 관리상의 오류로 인한 문제이거나 VoIP 시스템 마다 다르게 나타나는 사소한 보안 위협들로 일반화 될 수 없는 것들만 존재 하게 되었다. 하지만, 이 보안 위협들이 기존의 다른 인터넷 서비스와 함께 사용된다면 또 다른 보안 위협으로 악용 될 수 있다는 것을 본 논문에서 제시 하였다. 본 논문에서는 VoIP의 기본 구성에 대해서 설명하고, VoIP 동작 과정에서 나타날 수 있는 취약점과 다른 인터넷 서비스와 함께 사용 될 때 어떻게 보안 위협이 될 수 있는지에 대한 사례를 제시 하며 이에 대한 해결책에 대해서 논의 하고자 한다.
The major greenhouse gases (GHGs) in agricultural sector are methane (CH₄), nitrous oxide (N₂O), carbon dioxide (CO₂). GHGs emissions are estimated by pertinent source category in a guideline book from Intergovernmental Panel on Climate Change (IPCC) such as methane from rice paddy, nitrous oxide from agricultural soil and crop residue burning. The methods for estimation GHGs emissions in agricultural sector are based on 1996 and 2006 IPCC guideline, 2000 and 2003 Good Practice Guidance. In general, GHG emissions were calculated by multiplying the activity data by emission factor. The total GHGs emission is 10,863 Gg CO₂-eq. from crop cultivation in agricultural sector in 2013. The emission is divided by the ratio of greenhouse gases that methane and nitrous oxide are 64% and 34%, respectively. Each gas emission according to the source categories is 7,000 Gg CO₂-eq. from rice paddy field, 3,897 Gg CO₂-eq. from agricultural soil, and 21 Gg CO₂-eq. from field burning, respectively. The GHGs emission in agricultural sector had been gradually decreased from 1990 to 2013 because of the reduction of cultivation. In order to compare with indirect emissions from agricultural soil, each emission was calculated using IPCC default factors (D) and country specific emission factors (CS). Nitrous oxide emission by CS applied in indirect emission, as nitrogen leaching and run off, was lower about 50% than that by D.