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서울시 구로구에서 COVID-19 발생 전ㆍ후 초미세먼지(PM2.5) 농도 변화에 따른 인구집단 노출평가
김동준,민기홍,최영태,신준섭,우재민,김동준,신정현,조만수,성경화,최윤형,이채관,최길용,양원호 한국환경보건학회 2021 한국환경보건학회지 Vol.47 No.6
Background: The coronavirus disease (COVID-19) has caused changes in human activity, and these changes may possibly increase or decrease exposure to fine dust (PM2.5). Therefore, it is necessary to evaluate the exposure to PM2.5 in relation to the outbreak of COVID-19. Objectives: The purpose of this study was to compare and evaluate the exposure to PM2.5 concentrations by the variation of dynamic populations before and after the outbreak of COVID-19. Methods: This study evaluated exposure to PM2.5 concentrations by changes in the dynamic population distribution in Guro-gu, Seoul, before and after the outbreak of COVID-19 between Jan and Feb, 2020. Guro- gu was divided into 2,204 scale standard grids of 100 m×100 m. Hourly PM2.5 concentrations were modeled by the inverse distance weight method using 24 sensor-based air monitoring instruments. Hourly dynamic population distribution was evaluated according to gender and age using mobile phone network data and time-activity patterns. Results: Compared to before, the population exposure to PM2.5 decreased after the outbreak of COVID-19. The concentration of PM2.5 after the outbreak of COVID-19 decreased by about 41% on average. The variation of dynamic population before and after the outbreak of COVID-19 decreased by about 18% on average. Conclusions: Comparing before and after the outbreak of COVID-19, the population exposures to PM2.5 decreased by about 40%. This can be explained to suggest that changes in people’s activity patterns due to the outbreak of COVID-19 resulted in a decrease in exposure to PM2.5.
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고성능 전자청진기를 이용한 태아 심박률 추정에 관한 연구
김동준 청주대학교 산업과학연구소 2002 産業科學硏究 Vol.20 No.1
Conventional stethoscopes can not store and record their signals. This prevents accurate and objective diagnosis. If the electronic stethoscope, which can store the stethoscopic sound, is developed, the auscultation will be greatly improved. This study describes an algorithm for fetal heart rate(FHR) estimation using phonogram. For this a fetal phonogram amplifier is implemented. The FHR estimation algorithm consists of a lowpass filter, decimation, envelop detection, pitch detection, and post-processing. Using the developed amplifier, clean heart sounds of fetus can be heard in noisy environment, such as a consultation room of a university hospital, a laboratory of a university. Even though the fetal phonogram amplifier detects the fetal heart sounds well, the sound quality is not so good as the ultrasonography. In case of very week fetal heart sound, autocorrelation of it showed clear periodicity. But two main peaks in one period is an obstacle in pitch detection and peaks are not so vivid. The proposed FHR estimation algorithm showed very accurate and stable results.
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김동준 한국색채디자인학회 2007 한국색채디자인학회 학술대회 Vol.2007 No.1
제품디자인에 있어서 컬러는 짧은 시간동안 사람들의 시선을 사로잡고 끌 수 있는 매우 중요한 요소로서 제품의 이미지를 향상 시키고 변화를 주어 구매 욕구를 증진시킨다. 그러므로 컬러는 제품 디자인의 핵심 경쟁력으로 부각되고 있으며, 급격히 변화하는 소비자의 다양한 기호를 만족시키는 절대적 요소이다. 본 연구에서는 설문조사와 컬러별 유모차 판매현황을 알아봄으로써 구매자의 선호 컬러와 구매에 직접적인 영향을 주는 구매컬러에 대하여 비교·분석함을 목적으로 하였다. 유모차의 선호색은 레드, 라임, 그레이 순으로 나타났고, 유모차의 구매색 또한 레드, 그레이, 아쿠아 순으로 나타났다. 선호컬러와 구매컬러의 일치율은 비교적 높게 나타났으며(72%), 유모차 구매컬러를 선택한 이유로는 선호컬러, 보편성, 세탁의 용이성 순으로 나타났다. 본 연구의 결과는 선호컬러는 구매컬러에 큰 영향을 끼칠 수 있으며, 제품의 특징, 목적, 기능 등에 따라 구매컬러에 영향이 있을 수 있음을 시사한다
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김동준,현상훈 한국세라믹학회 1996 한국세라믹학회지 Vol.33 No.5
Silica Aerogels with the density and porosity of 0.1g/cm3 and 96% were synthesized by two different supercri-tical drying processes (i.e additional solvent and intial pressure methods) Isoptopanol was chosen as sol-gel and supercritical drying solvents in order to synthesize aerogels at the lower temperature and pressure because the critical values of isopropanol are lower than those of methanol and ethanol commonly used. The P-V-T relationship of isopropanol was experimentally described for optimizing supercritical drying conditions such as the amount of extra solvent and supercritical drying temperature and pressure. In the addional solvent method monolithic and transparent aerogels were obtained by supercritical drying at 25$0^{\circ}C$ and 900 psing after 40% of the reactor volume was filled with isopropanol. Crack-free aerogels were synthesized at 25$0^{\circ}C$ and 1100~1200 psig by the initial pressure method with an intial nitrogen gas pressure of 400 psig and the isopropanol amount of 5% of the reactor volume.
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Causality of Roundwood Import and Macro-economic Variables
김동준 한국산림과학회 2004 한국산림과학회지 Vol.93 No.6
This study confirmed econometrically the causality of roundwood import and macro-economic variables using Korean data. One national product variable and one demand sector variable were selected among macro-economic variables. National product variable was represented by gross domestic product(GDP), and demand sector variable was represented by building permit area(BPA). The relationships between roundwood import and GDPㆍBPA were represented by bivariate vector autoregressive model. The causality of roundwood import with GDPㆍBPA was measured by the causality test of Granger.There appeared to be evidence of the causal relationship between change in roundwood import and change in GDPㆍBPA. That is, change in GDPㆍBPA causes change in roundwood import in Korea. The causality test value of roundwood import with BPA was larger than that with GDP. That is, roundwood import can be more efficiently explained by demand sector variable than national product variable in Korea.
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