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최영태(Youngtae Choe),허정(Jung Heo),박진현(Jinhyeon Park),김은채(Eunchae Kim),류현수(Hyoensu Ryu),김동준(Dong Jun Kim),조만수(Mansu Cho),이채관(Chaekwan Lee),이종대(Jongdae Lee),양원호(Wonho Yang) 한국환경보건학회 2020 한국환경보건학회지 Vol.46 No.3
Objectives: Much attention has been paid to indoor air quality. Ventilation within schools is important because of indoor air quality and its effect on health and learning performance. In this study, we evaluated the carbon dioxide (CO2) concentrations and ventilation rates in schools. Methods: This study measured the concentration of CO2 in elementary, middle, and high school classrooms over six months. The seasons during the study were summer, fall, and winter. Sensor-based monitoring was used and the basic characteristics of the classroom were investigated. The body surface area of the students was used to calculate the CO2 generation rate, and the air change per hour (ACH) was evaluated using mass balance modeling. Results: The average CO2 concentration measured in most schools exceeded 1000 ppm. The ventilation rates varied from season to season. Compared to the recommended ventilation rate of 4.9 ACH, the roughly 3 ACH calculated in this study indicates that most schools possessed insufficient ventilation. Conclusions: The concentration of CO2 in school classrooms could be an indicator of indoor air quality and can affect students learning ability. In this study, CO2 concentrations exceeding the standard indicate a lack of ventilation along with problems with indoor air quality. Therefore, appropriate improvements are needed to overcome these problems.
최영태 ( Youngtae Choe ),박진현 ( Jinhyeon Park ),김은채 ( Eunchae Kim ),김동준 ( Dongjun Kim ),민기홍 ( Kihong Min ),조만수 ( Mansu Cho ),양원호 ( Wonho Yang ) 대구가톨릭대학교 자연과학연구소 2020 자연과학연구논문집 Vol.18 No.1
As health problems caused by air pollutants and problems caused by air pollutants such as COVID-19 are caused, interest in air quality is growing. Modern people spend more than 80% of their day indoors, so most of them are exposed to air pollutants indoors. Also, contaminated air of indoor air may be generated indoors or introduced outdoors. If contaminated air is not properly ventilated or discharged indoors, contamination accumulates as it circulates inside, which can cause more problems than outdoor air pollution. In particular, indoor air quality is more important when spending a long time in a space such as a house, office, or school classroom. Unlike adults, children and adolescents have a higher respiratory rate per unit weight and a higher risk of exposure to pollutants heavier than air due to their relatively low height. Also, because students spend most of their day in the classroom, the quality of the school classroom air can have a greater impact on students’ health. The indoor air quality of school classrooms can change the PM10 concentration due to external influences. Therefore, the environment and characteristics of the school must be considered.
Monte-Carlo 모의실험을 이용한 초·중·고등학교의환기부족 평가
최영태(Youngtae Choe),박진현(Jinhyeon Park),김은채(Eunchae Kim),류현수(Hyoensu Ryu) 김동준(Dong Jun Kim),민기홍(Kihong Min),정다영(Dayoung Jung),우병렬(Byung Lyul Woo),조만수(Mansu Cho),양원호(Wonho Yang) 한국환경보건학회 2020 한국환경보건학회지 Vol.46 No.6
Objectives: Indoor air quality has become more important aspeople spend most of their times indoors. Since students spend most of their times at home or at school, they are more likely to be exposed to indoor air pollutants. Ventilation in school classrooms can affect health and learning performance. In this study, ventilation deficiency was evaluated in school classrooms using Monte Carlo simulation. Methods: This study used sensor-based monitoring for six months to measure carbon dioxide (CO2) concentrations in classrooms in elementary, middle, and high schools. The volume of the classroom and the number of students were investigated, and the students’ body surface area was used to calculate the CO2 emission rate. The distribution of ventilation rates was estimated by measured CO2 concentration and a massbalance model using Monte Carlo simulation. Results: In the elementary, middle, and high schools, the average CO2 concentrations exceeded 1000 ppm, indicating that the ventilation rates were insufficient. The ventilation rates were deficient from July to August and in December, but showed relatively high ventilation rates in October. Forty-three percent of elementary schools, 56% of middle schools, and 62% of high schools showed insufficient ventilation rates. Conclusions: The ventilation rates calculated in elementary, middle and high schools were found to be quite insufficient. Therefore, proper management is needed to overcome the lack of ventilation and improve air quality.
철산화 박테리아의 생장 및 활성 억제를 통한 산성광산배수의 발생 저감
박영태(Park, Youngtae),양중석(Yang, Jungseok),권만재(Kwon, Manjae),윤현식(Yun, Hyunshik),지민규(Ji, Minkyu),지은도(Jee, Eundo),이우람(Lee, Wooram),지원현(Ji, Wonhyun),권현호(Kwon, Hyunho),최재영(Choi, Jaeyoung) 한국지반환경공학회 2012 한국지반환경공학회논문집 Vol.13 No.4
폐광산의 산성배수(AMD)는 황철석을 비롯한 다른 금속 황화물의 산화를 통해 발생한 폐광산의 산성배수는 환경오염의 원인 중 하나이다. 본 연구에서는 이러한 폐광산의 산성배수가 생성되는 과정에서 산화미생물의 관여 정도를 알아보고, 이를 억제할 수 있는 방법에 대해여 살펴보았다. 산성배수 발생에 영향을 미치는 산화미생물로 Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans을 선정하였으며, 이 산화미생물의 활성 및 생장 속도를 측정하였으며, 이산화염소(ClO₂), NaCl, 그리고 계면활성제(ASOR-770) 를 산발생 억제제로 이용하여 실험을 진행하였다. 실험 결과 10ppm 이산화염소가 가장 효과적인 억제제였으며, 산화미생물의 활성도와 생장도를 20% 까지 감소시켜주었다. Acid mine drainage (AMD) is one of the most severe environmental problem that results from the oxidation of pyrite (FeS₂) and various other metal sulfides. In this study, the influence of microorganism was tested on the process where AMD was released and the method to inhibit AMD generated by microorganisms at abandoned mine area. The activity and growth rate of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans, common microorganisms affecting AMD occurrence, were measured. Chlorine dioxide (ClO₂), NaCl, or surfactant (ASOR-770) was used as an inhibitor for working on activity and growth of microorganism. Among the three inhibitors, 10ppm of chlorine dioxide was the most effective inhibitor for AMD control due to the reduced the activity and growth of microorganisms by 20%.
Monte-Carlo 모의실험을 통한 부분 인구집단별 벤젠 및 PM 10 의노출 및 위해성 평가
박진현(Jinhyeon Park),양소영(So Young Yang):박윤경(Yunkyung Park),류현수(Hyeonsu Ryu),김은채(Eunchae Kim),최영태(Youngtae Choe),허 정(Jung Heo),조만수(Mansu Cho),양원호(Wonho Yang) 한국환경보건학회 2019 한국환경보건학회지 Vol.45 No.3
Objectives: The Korea Ministry of Environment regulates concentrations of hazardous air pollutants (HAPs) through Atmosphere Environmental Standards to protect public health from HAPs. However, simply determining the exceedance of HAP concentrations has several limitations and more comprehensive assessment is required. In addition, integrated risk assessment is needed considering exposure in all microenvironments, including outdoor as well as indoor environments. The purpose of this study was to assess the differences in risk by sub-population groups according to time-activity patterns and reported concentrations, as well as the lifetime risk for Koreans. Methods: In this study, we calculated time-weighted average exposure concentrations for benzene and PM 10 among preschool-age children, students, housewifes, workers, and the elderly using residential time and concentrations for indoor (house, school or workplace, other), outdoor, and transport by the meta-analysis method. The risk assessments were conducted by excess cancer risk and disease death risk using 1,000,000 Monte-Carlo simulations for probabilistic analysis. Results: Preschool-age children, students, housewifes, workers, and the elderly spent 91.9, 86.0, 79.8, 82.2, and 77.3% of their day in their house, workplace, or school, respectively. The more than 99% excess cancer risk for benzene exceed 1.0E-06 in all sub-populations and lifetime. The acute disease death risk for PM 10 for housewifes and workers for lifetime were 3.35E-04 and 3.18E-04, and chronic disease death risks were 2.84E-03 and 2.70E-03, respectively. Conclusions: The risk of benzene and PM 10 by sub-population group and for the lifetime of housewifes and workers were assessed. Benzene showed risky results for this study. All disease death risks of PM 10 were higher than 1.0E-04 and showed different risks by sub-population. This study can be used as a basis for lifetime exposure and risk assessment to benzene and PM 10 .
A 4×32-Channel Neural Recording System for Deep Brain Stimulation Systems
Kim, Susie,Na, Seung-In,Yang, Youngtae,Kim, Hyunjong,Kim, Taehoon,Cho, Jun Soo,Kim, Jinhyung,Chang, Jin Woo,Kim, Suhwan The Institute of Electronics and Information Engin 2017 Journal of semiconductor technology and science Vol.17 No.1
In this paper, a $4{\times}32$-channel neural recording system capable of acquiring neural signals is introduced. Four 32-channel neural recording ICs, complex programmable logic devices (CPLDs), a micro controller unit (MCU) with USB interface, and a PC are used. Each neural recording IC, implemented in $0.18{\mu}m$ CMOS technology, includes 32 channels of analog front-ends (AFEs), a 32-to-1 analog multiplexer, and an analog-to-digital converter (ADC). The mid-band gain of the AFE is adjustable in four steps, and have a tunable bandwidth. The AFE has a mid-band gain of 54.5 dB to 65.7 dB and a bandwidth of 35.3 Hz to 5.8 kHz. The high-pass cutoff frequency of the AFE varies from 18.6 Hz to 154.7 Hz. The input-referred noise (IRN) of the AFE is $10.2{\mu}V_{rms}$. A high-resolution, low-power ADC with a high conversion speed achieves a signal-to-noise and distortion ratio (SNDR) of 50.63 dB and a spurious-free dynamic range (SFDR) of 63.88 dB, at a sampling-rate of 2.5 MS/s. The effectiveness of our neural recording system is validated in in-vivo recording of the primary somatosensory cortex of a rat.
시간활동양상에 따른 주택의 시간대별 실내·실외 초미세먼지 농도비
박진현(Jinhyeon Park),김은채(Eunchae Kim),최영태(Youngtae Choe),류현수(Hyoensu Ryu),김순신(Sunshin Kim),우병렬(Byung Lyul Woo),조만수(Mansu Cho),양원호(Wonho Yang) 한국환경보건학회 2020 한국환경보건학회지 Vol.46 No.5
Objective: The purpose of this study was to evaluate the indoor to outdoor ratio (I/O ratio) of time activity patterns affecting PM2.5 concentrations in homes in Korea through a simulation. Methods: The time activity patterns of homemakers were analyzed based on the ‘Time-Use Survey’ data of the National Statistical Office in 2014. From September 30 to October 2, 2019, the experimenter lived in multi�family housing located in Guro-gu, Seoul. The I/O ratio of PM2.5 concentration was measured by installing sensor-based instruments. Results: The average indoor and outdoor PM2.5 concentrations during the three days were 33.1±48.9 and 45.9±25.3 μg/m3 , respectively. The average I/O ratio was 0.75±0.60. The indoor concentration tended to increase when PM2.5 source activity such cooking and cleaning was present and outdoor PM2.5 was supplied through ventilation. Conclusions: This study could be used as basic data for estimating indoor PM2.5 concentrations with personal activity pattern and weather conditions using outdoor concentrations.
A 4×32-Channel Neural Recording System for Deep Brain Stimulation Systems
Susie Kim,Seung-In Na,Youngtae Yang,Hyunjong Kim,Taehoon Kim,Jun Soo Cho,Jinhyung Kim,Jin Woo Chang,Suhwan Kim 대한전자공학회 2017 Journal of semiconductor technology and science Vol.17 No.1
In this paper, a 4×32-channel neural recording system capable of acquiring neural signals is introduced. Four 32-channel neural recording ICs, complex programmable logic devices (CPLDs), a micro controller unit (MCU) with USB interface, and a PC are used. Each neural recording IC, implemented in 0.18 mm CMOS technology, includes 32 channels of analog front-ends (AFEs), a 32-to-1 analog multiplexer, and an analog-to-digital converter (ADC). The midband gain of the AFE is adjustable in four steps, and have a tunable bandwidth. The AFE has a mid-band gain of 54.5 dB to 65.7 dB and a bandwidth of 35.3 Hz to 5.8 kHz. The high-pass cutoff frequency of the AFE varies from 18.6 Hz to 154.7 Hz. The input-referred noise (IRN) of the AFE is 10.2 mVrms. A high-resolution, low-power ADC with a high conversion speed achieves a signal-to-noise and distortion ratio (SNDR) of 50.63 dB and a spurious-free dynamic range (SFDR) of 63.88 dB, at a sampling-rate of 2.5 MS/s. The effectiveness of our neural recording system is validated in in-vivo recording of the primary somatosensory cortex of a rat.
보행자 보호기준과 시험법에 대한 어린이 머리 상해치 비교연구
윤영한(Younghan Youn),양재의(Jaeeui Yang),최영태(Youngtae Choi),윤경한(Kyunghan Yoon) 한국자동차공학회 2004 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Pedestrian fatalities account for about 44% of all traffic accident fatalities in Korea. In this paper, a series of child headform test and simulation were conducted to evaluate pedestrian protection test protocol describes in the EEVC and IHRA. The developed 2.5㎏ and 3.5㎏ child headform impactors were used to evaluate the effectiveness of these test rigs in the hood component. Results from the simulations, the influence factors such as impact speed, impact angle and headform sizes were evaluate in terms of HIC.