검색결과

검색조건
좁혀보기
검색필터
결과 내 재검색

간행물

    분야

      발행연도

      -

        검색결과 7

        1.
        2022.09 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        The Ionospheric Anomaly Monitoring by Magnetometer And Plasma-probe (IAMMAP) is one of the scientific instruments for the Compact Advanced Satellite 500-3 (CAS 500-3) which is planned to be launched by Korean Space Launch Vehicle in 2024. The main scientific objective of IAMMAP is to understand the complicated correlation between the equatorial electro-jet (EEJ) and the equatorial ionization anomaly (EIA) which play important roles in the dynamics of the ionospheric plasma in the dayside equator region. IAMMAP consists of an impedance probe (IP) for precise plasma measurement and magnetometers for EEJ current estimation. The designated sun-synchronous orbit along the quasi-meridional plane makes the instrument suitable for studying the EIA and EEJ. The newly-devised IP is expected to obtain the electron density of the ionosphere with unprecedented precision by measuring the upper-hybrid frequency (fUHR) of the ionospheric plasma, which is not affected by the satellite geometry, the spacecraft potential, or contamination unlike conventional Langmuir probes. A set of temperaturetolerant precision fluxgate magnetometers, called Adaptive In-phase MAGnetometer, is employed also for studying the complicated current system in the ionosphere and magnetosphere, which is particularly related with the EEJ caused by the potential difference along the zonal direction.
        2.
        2021.03 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        In this paper, we present observations of the Space Radiation Detectors (SRDs) onboard the Next Generation Small Satellite-1 (NEXTSat-1) satellite. The SRDs, which are a part of the Instruments for the study of Stable/Storm-time Space (ISSS), consist of the Medium-Energy Particle Detector (MEPD) and the High-Energy Particle Detector (HEPD). The MEPD can detect electrons, ions, and neutrals with energies ranging from 20 to 400 keV, and the HEPD can detect electrons over an energy range from 0.35 to 2 MeV. In this paper, we report an event where particle flux enhancements due to substorm injections are clearly identified in the MEPD A observations at energies of tens of keV. Additionally, we report a specific example observation of the electron distributions over a wide energy range in which we identify electron spatial distributions with energies of tens to hundreds of keV from the MEPD and with energy ranging up to a few MeV from the HEPD in the slot region and outer radiation belts. In addition, for an ~1.5-year period, we confirm that the HEPD successfully observed the well-known outer radiation belt electron flux distributions and their variations in time and L shell in a way consistent with the geomagnetic disturbance levels. Last, we find that the inner edge of the outer radiation belt is mostly coincident with the plasmapause locations in L, somewhat more consistent at subrelativistic energies than at relativistic energies. Based on these example events, we conclude that the SRD observations are of reliable quality, so they are useful for understanding the dynamics of the inner magnetosphere, including substorms and radiation belt variations.
        3.
        2015.04 KCI 등재 서비스 종료(열람 제한)
        Environmental regulations on the management of waste electrical and electronic equipments (WEEE) have been strengthened in many developed countries. Improper management and disposal of such waste, especially in informal sectors, may pose serious threats to the environment and human health. In Korea, there are very few available statistical data regarding distribution flow and treatment of WEEE in informal sectors (i.e., unreported private collection and recycling facilities). In order to provide additional measures related to proper management of WEEE, there is an urgent need for a quantitative material flow study on the amount of the waste found in the sectors. This can be achieved by conducting a statistical analysis of the flow of WEEE in the sectors and by drawing significant results and implications of such analysis. In this study, the relevant data were collected from literature review and a number of field site visits to informal private collection and recycling sites with survey in Daejoen Metropolitan City. Statistical analysis of the survey related to the distribution of WEEE in informal sectors was conducted to determine the quantitative flow of WEEE in the sectors. According to the results of this study, 3.38 kg/person/year were introduced into informal sectors in 2013, while 2.48 kg/ person/year was recycled in formal sectors in 2012. This study implies that there are significant amounts of WEEE that are present and processed in the sectors, which are not regulated by government. Small private collectors of WEEE in informal sectors received approximately 60.6 unit/month on average. The results of this statistical study indicate that there are no significant differences among the factors such as the amount of treatment, the number of employee, and the degree of dismantle process. However, there is significant difference among the WEEE category large home appliance, small-sized home appliance, and audio-video equipment. Further study may be warranted to focus the flow of WEEE in informal sectors in more large scale in order to accurately determine the final destination and disposal of such waste in the environment.
        4.
        2014.06 KCI 등재 서비스 종료(열람 제한)
        The management of household hazardous waste (HHW), a component of municipal solid waste (MSW) has become a major of concern partly due to their potential toxicity upon disposal. Improper management of such waste can deteriorate the environment and cause serious damage to the human health. This paper discusses the current fundamental management practices, which include the generation rate, collection systems and treatment using the survey reviews of households and interviews held with experts in the Daejeon metropolitan city. Surveys of more than 378 people in Daejeon Metropolitan City were conducted to investigate the characteristics, generation rate, social behavior and awareness regarding disposal of HHW. The target items used in this study includes used lamps, used batteries, pharmaceuticals, and household pesticide chemicals. According to the survey conducted, the generation rates of HHW varied depending upon the dwelling type, collection system, and waste type. Apartment complex residents participated actively in source separation, using the established collection system with limited items (e.g., fluorescent lamps and batteries), while single family housing residents tend to store HHW at households. There is still a need for public awareness, detailed policies and legislation requiring source segregation at households, and better collection systems for HHW. The results of this study can be used for developing better management of HHW in municipal solid waste streams to prevent potential environmental impacts and human health risks.
        5.
        2014.06 KCI 등재 서비스 종료(열람 제한)
        Global increase in the demand for the new Electrical and Electronic Equipment (EEE) results in the rapid increase of waste electrical and electronic equipment (WEEE) (or electronic waste). Significant efforts on developing diverse WEEE recycling policy and programs such as extended producer responsibility (EPR), WEEE directive, and the restriction of the use of hazardous substances (RoHS) directive are being made by many developed nations. This study focuses on determining priority among proposed WEEE recycling policy research projects by a number of experts from academia, institutions and recycling industry using quality function deployment (QFD) method to better manage and recycle WEEE in Korea. In order to develop effective WEEE recycling policy, a total of 12 different WEEE recycling policy research projects were proposed by a total of 11 experts related WEEE recycling. Reliability and validity evaluation of the proposed projects were conducted, along with SPSS statistical software. By using the QFD method, a survey regarding potential problems, suggestions, and difficulties at several WEEE recycling facilities were conducted and evaluated. Evaluation of the proposed projects was made by house of quality (HOQ). In this study, proposed research projects with higher importance index include WEEE collection system, development of WEEE recycling guideline, and establishment of WEEE generation/collection/recycling national database. The QFD method employed in this study can be effectively used as a decision-making process tool in WEEE recycling policy and road map.
        6.
        2014.03 KCI 등재 서비스 종료(열람 제한)
        There are many stringent environmental regulations on the management of waste electrical and electronic equipments(WEEE) in most developed countries. WEEE directive aims at increasing collection and recycling rate of WEEE whereas,while the restriction of the use of certain hazardous substances (RoHS) aims at restricting hazardous materials duringthe production of electrical and electronic equipment (EEE). TV housing rear covers consist of small portion of brominatedflame retardants (BFRs). Improper management and disposal of such waste can pose impacts on the environment andhuman health. In Korea, there are very few available statistical data regarding BFRs levels in TVs housing rear covers.In order to provide additional measures related to management of BFRs, there is a need for a quantitative material flowstudy on the amount of BFR found in TVs. This can be achieved by the aid of material flow analysis of the TV setsand by studying the Deca-BDE components present in the TV housing read covers. In this study, the relevant data werecollected from the statistical reports and through field site visits to the WEEE recycling facilities with surveys. Staticand dynamic material flow analysis (MFA) was conducted to determine material flow of BFRs (Deca-BDE) in themanagement of waste TVs. According to this study, in 2011, households in Korea use 73,821ton of TV sets of which23,592ton of waste TV sets were collected and recycled by municipalities and producers. Extended ProducerResponsibility (EPR) played a major role in recycling of WEEE. In this study, it was predicted that Deca-BDE in usestage would reach down to 51.73ton by 2016. In addition, the amount of Deca-BDE present at the disposal and recyclingstage is estimated to be approximately 2.45ton by 2018.
        7.
        2013.10 KCI 등재 서비스 종료(열람 제한)
        The development of recycling technology and process of waste electrical and electronic equipment (WEEE), also called electronic waste is becoming a growing interest in the world from the perspective of material recovery and resource conservation. In this study we examined the recycling technology levels of WEEE by both group category and recycling process using expert surveys. Based on the results of the expert surveys conducted, the level of large home appliances was found to be approximately 81.1% (± 6.2% std) when compared with that of the advanced countries, while small home appliances and IT equipment and audio/video equipment were 73.5% (± 6.2% std) and 76.2% (± 6.2% std), respectively. In case of recycling pre-treatment process (e.g., disassembly, size reduction, and separation), the technological levels was found to be approximately 82.2%, while the material recovery process followed by the pretreatment process was estimated to be approximately 68.5%. The results of reliability test for the expert survey showed that the values of coefficient of variation (CV) for the pre-treatment process and material recovery process by group category and recycling process are less than 0.5, which is a guidance limit for the coefficient. Based on the statistical tests (ANOVA and t-test), there is no significant difference of the recycling technological levels among the group category (large home appliances, small home appliances, IT equipment, and audio/video equipment. However, the statistical difference between the pre-treatment process and material recovery process within the group category existed (p-value < 0.05) using t-test. In this study, the results imply that there is still a need for developing a variety of more advanced recycling technologies of WEEE to effectively recover valuable metals and materials from it, especially in the fields of metal recovery and extraction processes.