물질의 입자성 도입 전과 후 온도에 따른 기체의 부피 변화 과학 설명 텍스트 특성: 동성 체계의 과정 유형 분석을 통하여

백명주 학습자중심교과교육학회 2024 학습자중심교과교육연구 Vol.24 No.18

Objectives This study is intended to provide an in-depth understanding of the difficulties of first-year middle school (7th) students beginning to deal with the particle nature of matter in explaining phenomena in terms of scientific explanationtexts. Methods For this purpose, the phenomenon of changing gas volume according to temperature was focused on science textbooks for the 6th and 7th grades. This was before and after the introduction of the particle nature of matter. The composed scientific explanatory texts were classified based on whether they contained particulate concepts. In addition, the types of processes in transitivity systems were analyzed. Results The type of process presented in the science explanatory texts of the 6th grade and 7th grade was dominated by material process. In texts that did not include the particle nature of matter, the science texts of the 6th grade and the 7th grade differed in the existential process. In the first-year middle school text, which considered the particle nature of matter, participants and circumstances showed continuity and complexity of explanation but differed mostly in attribute and relational processes. Conclusions Through the analysis of the types of processes, the difficulties of students in reading the explanatory texts before and after the introduction of the particle nature of matter were understood, and the discussion points on the method of introducing the particle nature of matter were derived.

DPF 장착 경유승용차의 재생시 미세입자 배출특성 연구

권상일(Sang-Il Kwon),김종춘(Jong-Choon Kim),박용희(Yong-Hee Park),이창식(Chang-Sik Lee) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

Nano-Particles is main subject in health effect. The relationships between transient vehicle operation and nano-particle emissions are not well-known, especially for diesel passenger vehicle with DPF. In this study, a diesel passenger vehicles were measured on a chassis dynamometer test bench with and without DPF regeneration. The particulate matter (PM) emissions of these vehicles were investigated by number, size and mass measurement. The mass of the total PM was evaluated using the standard gravimetric measurement method, the total number and size concentrations were measured on a NEDC driving cycle using Condensation Particle Counter (CPC) and EEPS. Total number concentration by CPC was 1.5×10¹¹N/㎞ and was 20% of result by EEPS. This means about 80% of total particle emission is compromise of volatile and small-size particle(<22㎚). In regeneration, particle emission was 6.2×10¹²N/㎞ and was emitted 400 times compared to without regeneration. and particle of 22~100㎚ size was emitted mainly, showed peak value nearby 40㎚ size. This means regeneration decreased mean size of particle. In before and after regeneration, PM showed no change but particle number showed about 6 times difference. The regeneration influence on particle number emissions is believed to be related to DPF-fill state and filtration efficiency.

Characterization of metal-bearing diesel nanoparticles using single-particle mass spectrometry

Lee, D.,Miller, A.,Kittelson, D.,Zachariah, M.R. Elsevier 2006 Journal of aerosol science Vol.37 No.1

<P><B>Abstract</B></P><P>Acute and chronic health effects have been associated with diesel particulate matter (DPM). Since both ultrafine particles and metals have been implicated in this correlation, we are conducting investigations to characterize the metal content of diesel nanoparticles. For this study, DPM was generated by a 1.5l engine and ferrocene was added to the fuel to raise the level of metal in the system. The exhaust particles were analyzed in real time using a recently developed single-particle mass spectrometer (SPMS) that has the capability of ablating each particle down to its elemental constituents, thereby yielding the relative mass of elements in each particle. Particle-size calibration of the instrument was achieved by correlating the SPMS signal intensity with measured DPM size. Using this approach, we present size- and composition-resolved elemental species distributions for both the nuclei mode and ultrafine portion of the accumulation mode of DPM. Results show that when the fuel is doped with ferrocene, iron-rich nanoparticles are formed and their number and size increase with level of doping. Larger iron-bearing particles are also formed, but it is observed that the metal to carbon ratios increase for smaller particle sizes. Hydrogen to carbon ratios were measured as a function of particle size, which allowed us to determine the relative amounts of organic carbon and elemental carbon in the particles and showed that the hydrogen to carbon ratios increase for smaller sized particles. The combined results are used to discuss the effects of metal doping level and engine load on particle nucleation and mechanisms of DPM formation.</P>

Evaluation of the time-resolved nanoparticle emissions and the vehicle performance characteristics for a turbocharged gasoline direct-injection vehicle with a metal-foam gasoline particulate filter

Baek, Sungha,Jin, Dongyoung,Jang, Wonwook,Myung, Cha-Lee,Park, Simsoo,Lee, Jeongmin Professional Engineering Publishing Ltd 2016 Proceedings of the Institution of Mechanical Engin Vol. No.

<P>The nanoparticle emissions from gasoline direct-injection engines are of concern because of the high particle number concentrations compared with those from a gasoline port fuel injection engine. A gasoline particulate filter is a potential solution for reducing the particulate matter emissions. In this study, a 2.0 l turbocharged gasoline direct-injection vehicle with a metal-foam-type gasoline particulate filter was tested using the New European Driving Cycle and steady vehicle operating conditions. The particle number concentration, the particle-size distribution and the filtration efficiency were determined using a condensation particle counter and a fast response differential mobility spectrometer (DMS500). The particle number emissions (particle numbers per vehicle travelling distance (particles/km)) over the New European Driving Cycle were 1.95x10(12) particles/km for a base vehicle equipped with a three-way catalytic converter and 5.68x10(11) particles/km for the additional installation of a gasoline particulate filter on the base gasoline direct-injection vehicle. The filtration efficiency of the particle number and the particulate matter mass reached approximately 71% and 67% respectively. The nucleation-mode particles in the size range less than 23nm for the gasoline direct-injection vehicle equipped with a three-way catalytic converter were further reduced on installation of a gasoline particulate filter at the downstream position of the three-way catalytic converter. A sharp pressure drop between the gasoline particulate filter of 21.0 mbar was obtained at a vehicle speed of 120km/h in the New European Driving Cycle. The exhaust gas temperature before the gasoline particulate filter reached around 380-610 degrees C at steady vehicle speeds of 60-120km/h. The installation of the gasoline particulate filter has the potential to satisfy the Euro 6c particle number emissions regulations for light-duty gasoline direct-injection vehicles.</P>

Learning Progression을 적용한 중,고등학생의 물질의 입자성에 관한 지식과 미시적 표상에 대한 특성 분석

신남수 ( Nam Soo Shin ),고은정 ( Eun Jung Koh ),최취임 ( Chui Lm Choi ),정대홍 ( Dae Hong Jeong ) 한국과학교육학회 2014 한국과학교육학회지 Vol.34 No.5

Learning progressions (LP), which describe how students may develop more sophisticated understanding over a defined period of time, can inform the design of instructional materials and assessment by providing a coherent, systematic measure of what can be regarded as level appropriate. We developed LPs for the nature of matter for grades K-16. In order to empirically test Korean students, we revised one of the constructs and associated assessment items based on Korean National Science Standards. The assessment was administered to 124 Korean secondary students to measure their knowledge and submicroscopic representations, and to assign them to a level of learning progression for the particle nature of matter. We characterized the level of students`` understanding and models of the particle nature of matter, and described how students interpret various representations of atoms and molecules to explain scientific phenomena. The results revealed that students have difficulties in understanding the relationship between the macroscopic and molecular levels of phenomena, even in high school science. Their difficulties may be attributed to a limited understanding of scientific modeling, a lack of understanding of the models used to represent the particle nature of matter, or limited understanding of the structure of matter. This work will inform assessment and curriculum materials development related to the fundamental relationship between macroscopic, observed phenomena and the behavior of atoms and molecules, and can be used to create individualized learning environments. In addition, the results contribute to scientific research literature on learning progressions on the nature of matter.

바이오디젤 사용에 따른 경유승용차의 미세입자 배출특성 연구

권상일(Sang-Il Kwon),김종춘(Jong-Choon Kim),박용희(Yong-Hee Park),임철수(Cheol-Soo Lim) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

Recently, lots of researchers have been attracted to develope various alternative fuels and to use renewable fuels as a solution of environmental problems from automobile. and nano-Particles is main subject in health effect. The relationships between transient vehicle operation and nano-particle emissions are not well-known, especially for using biodiesel fuel. In this study, we have been performed experimental test for the exhaust emission and nano particle reduction characteristics by mixed ratio of biodiesel and analyzed the regulated biodiesel components. The particulate matter (PM) emissions were investigated by number and mass measurement. The mass of the total PM was evaluated using the standard gravimetric measurement method, the total number concentrations were measured on a ECE 15+EUDC driving cycle using Condensation Particle Counter (CPC). Total PM was reduced 2 -38% and number concentration was reduced ]-27% by mixed ratio of biodiesel. Total PM was reduced more than particle because volatile particle was measured in Total PM but was not measured in particle.

대형디젤엔진용 Metal Foam Filter의 미세입자 특성

송호영(Hoyoung Song),이민호,김재권(Jaigueon Kim),정충섭(Choongsub Jung),박만호(Manho Park),이정민(Jungmin Lee) 한국자동차공학회 2010 한국자동차공학회 학술대회 및 전시회 Vol.2010 No.11

Fine particles have the greatest demonstrated impact on human health. Their small size allows them to get deep into the lungs and from there they can reach or trigger inflammation in the lung, blood vessels or the heart, and perhaps other organs. Recently many studies have been performed about fine particles, specially nano particle less than 100㎚ size. In this study, we have performed experimental study on SFC reduction characteristics of emission, specially PM and PN(nano particle) and confirmed whether SFC have an advantage of reduction of particulate matter. EEPS measured the sample gas directly extracted from the tailpipe and used first dilutor between tailpipe and EEPS. We found that SFC reduced PM about 49% and PN about 62% and have a high reduction performance of nano particles.

누가 암흑물질을 주문했나?: 암흑물질의 필요성

박성찬 한국물리학회 2016 새물리 Vol.66 No.8

Dark matter is a component of matter in the Universe, whose existence is apparent only via gravitational interactions, not via electromagnetic interactions. The amount of dark matter in the energy budget of the Universe is about five times larger than that of the baryonic component in the standard model, but its origin is still not understood. So in this article, we discuss various astrophysical phenomena, virial motion of stars, the flat rotation curve of galaxies, weak gravitational lensing and cosmic microwave background radiation, which clearly show the effects of dark matter and provide theoretical opportunities to explain it. 암흑물질은 중력적으로 그 존재가 드러났으나, 그 이외의 다른 상호작용, 특히 전자기적 상호작용을 통해서는 그 존재가 드러나지 않은 우주의 물질 성분이다. 암흑물질이 차지하는 우주의 에너지 성분은 표준모형이 설명하는 바리온 양에 비해 대략 다섯배에 해당하며 우주의 팽창과 구조 형성에 대단히 중요한 역할을 하지만 그 기원에 대해서는 이해가 부족하다. 본 문에서는 다양한 천체물리학적 현상 중 천체의 비리얼 운동, 은하 회전 곡선, 중력 렌즈 효과, 우주배경복사 등을 통해 나타난 암흑물질의 관측적 증거를 일별하고, 암흑물질의 이론적 가능성에 대해 논의한다.

Computational Science-based Research on Dark Matter at KISTI

조기현 한국우주과학회 2017 Journal of Astronomy and Space Sciences Vol.34 No.2

The Standard Model of particle physics was established after discovery of the Higgs boson. However, little is known about dark matter, which has mass and constitutes approximately five times the number of standard model particles in space. The cross-section of dark matter is much smaller than that of the existing Standard Model, and the range of the predicted mass is wide, from a few eV to several PeV. Therefore, massive amounts of astronomical, accelerator, and simulation data are required to study dark matter, and efficient processing of these data is vital. Computational science, which can combine experiments, theory, and simulation, is thus necessary for dark matter research. A computational science and deep learning-based dark matter research platform is suggested for enhanced coverage and sharing of data. Such an approach can efficiently add to our existing knowledge on the mystery of dark matter.

공기조화기 장착용 축상유입식 싸이클론의 입자제거효율에 대한 실험적 연구

김세영(Seyoung Kim),권순박(Soon-Bark Kwon),박덕신(Duck-Shin Park),조영민(Youngmin Cho),김진호(Jinho Kim),김명준(Myungjoon Kim),김태성(Taesung Kim) 한국대기환경학회 2011 한국대기환경학회지 Vol.27 No.3

A novel particle removal system for air handling unit (AHU) of subway station was evaluated experimentally. The novel system was designed in order to minimize the maintenance cost by applying axial-flow cyclones. The system consists of multiple cyclone units and dust trap. Based on our previous numerical study, it was found to be effective for removal 1~10 ㎛ sized dust particles. In this study, we manufactured the mock-up model and evaluated the model experimentally. Liquid and solid test particles were generated for evaluating collection efficiency of the system and the pressure drop was monitored. The collection efficiency was varied from 41.2% to 85.9% with increasing the sizes of particle from 1 to 6.5 ㎛ by particle count ratio of inlet and outlet. The pressure drop was maintained constant less than 20㎜H₂O. In addition, the collection efficiency was estimated by total mass for solid test particles. It was found that the collection efficiency was 65.7% by particle mass ratio of inlet and outlet. It shows that present system can replace current pre-filters used in subway HVAC system for removing particulate matters with minimal operational cost.