• 환경위생공학
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• 제13권3호
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• pp.72-78
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• 1998

For investigation into gas permeation characteristics, the porous alumina membrane with asymmetrical structure, having upper layer with 10 nanometer under of pore diameter and lower layer with 36 nanometer of pore diameter, was prepared by anodic oxidation using DC power supply of constant current mode in an aqueous solution of sulfuric acid. The aluminium plate was pre-treated with thermal oxidation, chemical polishing and electrochemical polishing before anodic oxidation. Because the pore size depended upon the electrolyte, electrolyte concentration, temperature, current density, and so on, the the membranes were prepared by controling the current density, as a very low current density for upper layer of membrane and a high current density for lower layer of membrane. By control of current quantity, the thicknesses of upper layer of membranes were about $6{\;}{\mu}m$ and the total thicknesses of membranes were about $80-90{\;}{\mu}m$. We found that the mechanism of gas permeation depended on model of the Knudsen flow for the membrane prepared at each condition.

• 한국지반공학회논문집
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• 제24권5호
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• pp.15-25
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• 2008

본 논문에서 매년 항만개발 및 항로유지의 목적으로 발생하는 준설토사의 유효활용을 위하여 주요 항만 준설토사에 대하여 오염현황을 조사 및 분석하였다. 그리고 준설물질별 인간의 건강에 대한 피해확률을 과학적으로 추정하는 위해성 평가를 실시하여 공업 및 주거지역에서 직접 인체에 대하여 안전하고 유효하게 활용할 수 있는 기준을 제시하였다. 제시한 기준은 기존의 준설토사 처리.활용기준 및 토양환경보전법상의 환경기준보다 엄격한 것으로 나타났다. 그리고 유효활용에 대한 사전평가를 실시할 수 있는 관련 기준을 근거로 국내 주요항만의 발생준설토사에 대한 오염도를 평가한 결과, 일부 항만에서 카드뮴(Cd), 비소(As), 크롬(Cr) 및 아연(Zn)이 환경기준을 초과하는 것으로 나타나 정밀한 조사가 이루어져야 할 것으로 나타났지만 대부분 항만에서 발생한 준설토사는 유효활용이 가능한 것으로 나타났다.

• 한국지반환경공학회 논문집
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• 제13권12호
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• pp.35-42
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• 2012

연약지반에 구조물을 설치하거나 도로 또는 단지를 조성하는 경우 지지력 부족으로 인한 지반 전단파괴 및 과도한 압밀침하 등 공학적 문제가 발생하게 되어, 강도증가 및 침하억제를 위한 지반 개량공사를 필수적으로 시행하여야 한다. 연약지반을 개량함에 있어 현장계측자료를 바탕으로 한 장기침하량 예측은 선행재하 성토고 및 압밀완료시점 예측을 위한 매우 중요한 요소로 이에 관한 연구가 국내 외 여러 학자들에 의해 진행되고 있다. 본 연구에서는 선행재하 및 연직배수 공법을 적용하여 점성토 연약지반개량을 시행한 연구 대상 지역의 압밀침하 특성을 분석하였으며, 쌍곡선법, ${\sqrt{S}}$법, Asaoka법을 적용하여 압밀도에 따른 예측 침하량과 실측 최종침하량을 비교 분석하여 김포한강지구의 토질특성에 맞는 침하예측기법을 연구하였다. 연구결과에 의하면 3가지 예측방법으로 추정한 침하량과 계측침하량의 오차가 최대 ${\pm}4$% 이내로 실 침하량과 거의 일치하였으며, 예측의 정확도는 Asaoka법, 쌍곡선법, ${\sqrt{s}}$법 순으로 나타났다.

• 한국환경보건학회지
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• 제36권3호
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• pp.199-207
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• 2010

In this study, breast milk levels of indicator polychlorinated biphenyls (PCBs) were estimated, and statistics drawn, for 22 Koreans in the general population, aged 26-38, who had resided in metropolitan areas for more than 5 years without occupational exposure to organochlorine pollutants. Concentrations of indicator PCBs were measured using the isotope dilution method with a high resolution gas chromatograph/high resolution mass detector, which provided accurate and precise data for investigation of trends, and international comparisons. The geometric mean of total indicator PCB levels was 22.3 ng/g lipid, which is significantly lower than the level in individuals from European countries. Overall, the geometric mean and 95th percentile of the most abundant congener PCB 153 were 8.04 ng/g lipid and 16.4 ng/g lipid, respectively. PCB congeners 138, 153 and 180 together accounted for about 75% of the indicator congeners analyzed. Breast milk total indicator PCB concentrations were significantly associated with age and parity, but not with body mass index (BMI), rate of body weight increase, or smoking habits. The geometric mean level of PCB 153 in breast milk from mothers with a pre-pregnant BMI < $21\;kg/m^2$ was significantly higher than in pre-pregnant women with a BMI of ${\geqslant}\;21\;kg/m^2$ (p<0.05). Women who ate more fish, meat, and milk products did not have significantly higher total indicator PCB levels than those who ate less of these products, but a significant difference in PCB 153 levels was demonstrated between the subjects consuming higher (11.45 ng/g lipid) and lower (6.79 ng/g lipid) amounts of fish (p<0.05), after adjusting for confounders. These results suggest that age, parity and fish intake are the important factors affecting the concentrations of indicator PCBs in these subjects.

• 대한원격탐사학회지
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• 제37권3호
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• pp.577-589
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• 2021

드론 매핑 시스템은 재난 피해 조사, 국토 환경 모니터링, 건설 공정 모니터링 등 여러 분야에 응용 가능하다. 드론에 장착된 다양한 개별 센서를 통합하여 활용하려면 시간동기화 등 여러가지 절차가 필요했다. 최근, 영상 센서와 GPS/INS가 함께 내장된 복합센서가 다수 출시되었다. 복합센서는 여러 가지 센서 데이터를 내부적으로 통합하여, 위치/자세를 영상 파일에 바로 태깅하여 제공한다. 이러한 복합센서를 드론 매핑 시스템에 활용하려면 매핑 정확도를 확인해 볼 필요가 있다. 이에 본 연구에서는 다양한 데이터 취득 환경과 사전 캘리브레이션 여부를 중심으로 복합센서의 매핑 정확도를 확인하였다. 첫째, 매핑 정확도가 지상기준점의 개수에 따라 어떻게 변하는지 살펴보았다. 지상기준점 개수가 2개일 때부터 총 RMSE가 1 m 이상에서 약 60 cm로 40 cm가량 줄어드는 것을 확인할 수 있었다. 둘째, 데이터 취득 상황과 사전 캘리브레이션 여부에 따른 매핑 정확도를 확인하였다. 지상기준점이 있는 경우에는 개수가 적을지라도 사전 캘리브레이션의 영향이 크지 않은 것을 확인할 수 있었다. 영상의 중복도가 충분하지 않을 때는 사전 캘리브레이션 하는 것이 정확도 개선에 영향을 주는 것을 확인할 수 있었다. 지상기준점이 없는 경우에는 카메라, 탑재체 모두 사전 캘리브레이션 하는 것이 정확도를 개선시키는데 영향이 있음을 확인하였다. 본 연구를 기반으로, 향후 복합센서를 이용한 드론 매핑 수행 시 데이터 취득 조건에 따라 지상기준점 측량과 캘리브레이션 과정을 효율화 하는데 기여할 것으로 기대한다.

• 한국자동차공학회논문집
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• 제22권6호
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• pp.120-127
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• 2014

Robustness and controllability are the key factors in internal combustion engine commercialization. This study focuses on the combustion strategy to commercialize the low temperature diesel combustion technology. Various LTC combustion methods such as PPCI, MK and highly diluted mixing controlled LTC were conducted on 6.0L heavy duty diesel engine. To find the best feasible LTC strategy, emission level, fuel consumption and combustion safety during the combustion mode change were considered. Experiments were carried out under various engine operating conditions; engine speed & load, EGR level, injection timing. Finally, this study suggests realizable LTC combustion strategy; moderate EGR level and slight early injection are possible to considerably lower PM, NOx emission and expand LTC operating range up to 50% load without CO and HC emission.

• 한국지반신소재학회논문집
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• 제13권4호
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• pp.133-141
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• 2014

본 연구에서는 교량, 터널, 댐, 상수도 등 사회기반 시설물의 안전점검 및 정밀안전진단결과를 DB화하고 업무프로세스를 자동화하기 위해 각 시설물별로 점검진단에 필요한 항목을 표준화해서 분류체계를 마련하였고 사전조사에서부터 현장조사, 시설물평가, 보고서작성에 이르는 전 과정에서 걸쳐 데이터베이스 기반의 자료구조를 정의하고 파일럿시스템을 구현하였다. 또한 점검진단결과 DB가 효과적으로 활용될 수 있도록 개선방안을 제시하고, 시설물정보관리종합시스템 운영규정, 점검진단 세부지침 등 관련 규정/지침에 대한 개선방안을 제시하였다.

• Safety and Health at Work
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• 제13권2호
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• pp.227-234
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• 2022

Background and Purpose: In 2021, lung cancer in school food workers was first recognized as an occupational cancer. The classification of the carcinogenicity of cooking fumes by International Agency for Research on Cancer (IARC) was based on Chinese epidemiological data. This study aimed to determine the hazard levels of school cooking fumes in Korea. Materials and Methods: Based on public school cafeterias in one area, 25 locations were selected for the survey according to the number per school type, ventilation states, and environmental pre-assessments of cafeterias. Two inside cooking areas using a heat source and one outside cooking area were selected as control measurement points. Measurements of CO, CO₂, polycyclic aromatic hydrocarbons (PAHs), and total volatile organic compounds (TVOCs), including benzene, formaldehyde, and particulate matter (PM10, PM2.5, PM1, respectively), were taken. The concentrations and patterns of each substance in the kitchens were compared with the outdoor air quality. Result: Known carcinogens, such as the concentrations of PAHs, formaldehyde, TVOC (benzene), and particulate matter in school cooking fumes, were all detected at similar or slightly higher levels than those found outside. Additionally, substances were detected at relatively low concentrations compared to the Chinese cooking fumes reported in the literature. However, the short-term exposure to high concentrations of CO (or composite exposure with CO₂) and PM2.5 in this study were shown. Conclusion: The school cooking fumes in South Korea was a relatively less harmful than Chinese cooking fumes, however short-term, high exposure of toxic substances can cause a critical health effect.

• Journal of Electrochemical Science and Technology
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• 제15권1호
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• pp.178-189
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• 2024

This work aims to investigate the efficiency of electrocoagulation (EC) of pistachio processing industrial wastewater (PPIW) using the continuous EC process. The tubular reactor made of stainless steel with an internal diameter of 60 mm was used as a cathode electrode. The effect of some parameters was examined on the removal of chemical oxygen demand (COD) and total phenols (TP) removal efficiency. The influences of the initial pH of wastewater (from 4 to 8), flow rate (from 25 to 125 mL/min), current density (from 7 to 21 mA/cm²), and supporting electrolyte type (NaCl, NaNO₃, and Na₂SO₄), supporting electrolyte concentration (from 10 to 100 mg/L NaCl) on removal efficiency were investigated to determine the best experimental conditions. The examination of the physico-chemical parameters during the EC treatment showed that the best removal efficiency was obtained under conditions where the flow rate was 25 mL/min (20 min reaction time), the pH value was 5.2, and the current density was 21 mA/cm² has set. Under these experimental conditions, COD and TP removal efficiency were found to be 75% and 97%, respectively, while energy consumption was 18.5 kW h/m³. The study results show that the EC can be applied to PPIW pre-treatment.

• 한국산업융합학회 논문집
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• 제3권2호
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• pp.155-166
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• 2000

In order to elucidate the interrelationship between electrolytes and exercise the investigation was undertaken to determine the electrolyte levels in young males took on varied environmental temperatures ($13^{\circ}C$, $24^{\circ}C$ or $34^{\circ}C$). 10 healthy young males were used for the experiments. Our results showed the following significant changes; 1. The raising of the environmental temperature, the weight reduction were increased due to marked sweating. 2. In the electrolytes of serum, decreased the $K^+$ concentration at $13^{\circ}C$, but increased the $Na^+$ or $Cl^-$ concentration at $24^{\circ}C$, and increased the $Na^+$ or $Cl^-$, or $Mg^{+}^{+}$ concentrations at $34^{\circ}C$. 3. The raising of environmental temperature appear to be increased PRA,Ang I, Ang II and ALD levels, whereas no changed ADH level. 4. Serum levels of PRA, Ang I, Ang II and ALD were incresed after exercise, and their increments were incresed paralel ttie incresed environmental temperature. However, there no significant change in ADH, level. In conclusion, exercise induced not only changes of serum electrolytes levels such as $Na^+$, $Cl^-$, $K^+$, $Mg^{+}^{+}$, but also serum hormonal changes such as PRA, Ang I, Ang II, ALD. However, ADH level was not changed significantly, These changes were more prominent in exercise at hot temperature than in lower temperature.