• 반도체디스플레이기술학회지
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• 제21권1호
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• pp.17-21
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• 2022

In the case of the manufacturing industry that produces high-tech components such as semiconductors and large flat panel displays, the manufacturing space is made into a cleanroom to increase product yield and reliability, and various environmental factors have been managed to maintain the environment. Among them, airborne particle is a representative management item enough to be the standard for actual cleanroom grade, and a sequential particle monitoring system is usually used as one parts of the FMS (Fab or Facility monitoring system). However, this method has a problem in that the measurement efficiency decreases as the length of the sampling tube increases. In this study, in order to solve this problem, a multiple regression model was created. This model can correct the measurement error due to the decrease in efficiency by sampling tube length.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2009년도 학술논문요약집
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• pp.84-85
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• 2009

New approaches for detecting, preventing and remedying environmental damage are important for protection of the environment. Procedures must be developed and implemented to reduce the amount of waste produced in chemical processes, to detect the presence and/or concentration of contaminants and decontaminate fouled environments. Contamination can be classified into three general types: airborne, surface and structural. The most dangerous type is airborne contamination, because of the opportunity for inhalation and ingestion. The second most dangerous type is surface contamination. Surface contamination can be transferred to workers by casual contact and if disturbed can easily be made airborne. The decontamination of the surface in the nuclear facilities has been widely studied with particular emphasis on small and large surfaces. The amount of wastes being produced during decommissioning of nuclear facilities is much higher than the total wastes cumulated during operation. And, the process of decommissioning has a strong possibility of personal's exposure and emission to environment of the radioactive contaminants, requiring through monitoring and estimation of radiation and radioactivity. So, it is important to monitor the radioactive contamination level of the nuclear facilities for the determination of the decontamination method, the establishment of the decommissioning planning, and the worker's safety. But it is very difficult to measure the surface contamination of the floor and wall in the highly contaminated facilities. In this study, the poly(styrene-ethyl acrylate) [poly(St-EA)] core-shell composite polymer for measurement of the radioactive contamination was synthesized by the method of emulsion polymerization. The morphology of the poly(St-EA) composite emulsion particle was core-shell structure, with polystyrene (PS)as the core and poly(ethyl acrylate) (PEA) as the shell. Core-shell polymers of styrene (St)/ethyl acrylate (EA) pair were prepared by sequential emulsion polymerization in the presence of sodium dodecyl sulfate (SOS) as an emulsifier using ammonium persulfate (APS) as an initiator. The polymer was made by impregnating organic scintillators, 2,5-diphenyloxazole (PPO) and 1,4-bis[5-phenyl-2-oxazol]benzene (POPOP). Related tests and analysis confirmed the success in synthesis of composite polymer. The products are characterized by IT-IR spectroscopy, TGA that were used, respectively, to show the structure, the thermal stability of the prepared polymer. Two-phase particles with a core-shell structure were obtained in experiments where the estimated glass transition temperature and the morphologies of emulsion particles. Radiation pollution level the detection about under using examined the beta rays. The morphology of the poly(St-EA) composite polymer synthesized by the method of emulsion polymerization was a core-shell structure, as shown in Fig. 1. Core-shell materials consist of a core structural domain covered by a shell domain. Clearly, the entire surface of PS core was covered by PEA. The inner region was a PS core and the outer region was a PEA shell. The particle size distribution showed similar in the range 350-360 nm.

• 항공우주시스템공학회지
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• 제16권4호
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• pp.60-67
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• 2022

일반적인 항공기의 전자광학추적장비(Electro-Optical Tracking System, EOTS)는 EO/IR, 레이저 센서 등의 구성품으로 구성된다. 표적 획득 시 요구되는 표적 좌표는 내부 구성품인 관성측정장비(Inertial Measurement Unit, IMU)에서 측정되는 자세와 가속도 측정값을 이용하여 획득된다. 특히 무장시스템을 운용하는 항공기의 경우, 무장 발사를 위한 표적 좌표를 얼마나 신속하고 정확하게 획득하는가에 따라 무장시스템의 성능이 좌우된다. 무장시스템에서 요구하는 좌표 정확도를 충족하기 위해서는 IMU가 정렬 완료 상태에서 운용되어야 하므로 신속하게 자세와 가속도를 측정하여 IMU 초기 안정화 시간을 단축하여야 한다. IMU의 정렬은 IMU의 자세 오차를 해소하여 초기 자세를 결정하는 과정이며, 항공용 EOTS와 같은 임무장비의 IMU는 항법용 GPS/INS의 속도 정보를 기준으로 하는 속도정합 전달정렬을 수행한다. 본 논문에서는 이러한 속도정합 전달정렬 시간 단축을 위해 항공기와 임무장비의 자세 변화를 통한 전달정렬 성능 개선방안을 제시하였다. 먼저 전달정렬 모델과 시뮬레이션 결과를 통해서 EOTS의 전달정렬이 지연되는 요소가 방위각 오차임을 식별하였다. 그리고 EOTS의 방위각 오차 해소를 위해 항공기의 가속도 기동 및 EOTS의 자세 변화가 요구됨을 확인하였다. 최종적으로 OOO 항공기 체계에 적용한 비행시험 결과, 항공기 가속도 약 0.2g 이상이 발생하면서 EOTS가 6.7deg/s 각속도로 고각 운동 시 그렇지 않을 때보다 5배 이상 빠르게 정렬이 완료되어 전달정렬 성능이 개선되었다.

• 한국환경복원기술학회지
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• 제22권5호
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• pp.1-12
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• 2019

It is important to measure the height of trees as an essential element for assessing the forest health in urban areas. Therefore, an automated method that can measure the height of individual tree as a three-dimensional forest information is needed in an extensive and dense forest. Since airborne LiDAR dataset is easy to analyze the tree height(z-coordinate) of forests, studies on individual tree height measurement could be performed as an assessment forest health. Especially in urban forests, that adversely affected by habitat fragmentation and isolation. So this study was analyzed to measure the height of individual trees for assessing the urban forests health, Furthermore to identify environmental factors that affect forest growth. The survey was conducted in the Mt. Bongseo located in Seobuk-gu. Cheonan-si(Middle Chungcheong Province). We segment the individual trees on coniferous by automatic method using the airborne LiDAR dataset of the two periods (year of 2016 and 2017) and to find out individual tree growth. Segmentation of individual trees was performed by using the watershed algorithm and the local maximum, and the tree growth was determined by the difference of the tree height according to the two periods. After we clarify the relationship between the environmental factors affecting the tree growth. The tree growth of Mt. Bongseo was about 20cm for a year, and it was analyzed to be lower than 23.9cm/year of the growth of the dominant species, Pinus rigida. This may have an adverse effect on the growth of isolated urban forests. It also determined different trees growth according to age, diameter and density class in the stock map, effective soil depth and drainage grade in the soil map. There was a statistically significant positive correlation between the distance to the road and the solar radiation as an environmental factor affecting the tree growth. Since there is less correlation, it is necessary to determine other influencing factors affecting tree growth in urban forests besides anthropogenic influences. This study is the first data for the analysis of segmentation and the growth of the individual tree, and it can be used as a scientific data of the urban forest health assessment and management.

• 대한원격탐사학회지
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• 제30권1호
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• pp.61-73
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• 2014

본 연구는 항공 초분광영상을 사용한 수질추정 활용을 검토하고 한강일부분에 대해 가용한 측정자료를 이용하여 초분광영상 기반의 수질추정을 테스트하였다. 원격탐사에 의한 수질추정은 수체에 대한 downwelling과 수체 내에서의 산란과 반사에 대한 관측정보를 이용하는 방법과 원격탐사 센서에 도달하는 upwelling과 수질측정정보와의 선형적 회귀분석을 구하는 방법이 선호된다. 두 방법 모두 유의미한 결과를 도출하지만 수질정보나 산란정보 등 추정에 필요한 보조자료에 의한 영향이 더 클 것으로 판단되었다. 수질 추정 테스트는 팔당댐 하류에 위치한 한강의 일부분에 대해서 적용되었다. AISA eagle 초분광센서로 취득된 자료와 수질관측정보를 선형적 회귀분석을 통한 방법을 적용하였다. 기존 문헌에서 제시된 밴드조합에 대해서 회귀분석한 결과 유의미한 밴드조합으로 $-24.847+0.013L_{560}$의 회귀식을 얻었다 ($L_{560}$은 560 nm 파장에서의 radiance로 $R^2$=0.985). 다중분광영상을 이용했을 경우의 결과와 비교하기 위해서 spectral resampling을 통해 Landsat TM 영상을 생성하여 -55.932 + 33.881(TM, TM3)의 회귀식을 얻을 수 있었다(TM, TM3는 radiance로, $R^2$=0.968). 부유물질 농도는 수질측정지점에서 약 3.75 mg/l 이고, 초분광영상으로 추정된 농도는 약 3.65 mg/l, 시뮬레이션된 TM은 약 5.85 mg/l 로 다중분광영상을 이용했을 경우 과대 추정하는 경향을 보였다. 항공 초분광영상의 활용가치를 높이고 보다 정밀한 값을 추정하기 위해서 영상 전반에 걸친 sun glint 와 같은 영향을 최소화하기 위해 태양고도각을 고려하여 정교한 비행계획을 구성하고 체계적 전처리와 검 보정 체계를 갖출 필요가 있다고 사료된다. 일반적으로 적용된 방법에 따른 테스트로, 대기보정의 정밀성과 부족한 수질측정 샘플자료, 분광밴드의 검색, 적합한 선형회귀모델의 선택, 그리고 정량적 검증방법과 같은 몇 가지 문제점과 제약사항들을 발견할 수 있었다.

• 대한환경공학회지
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• 제36권6호
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• pp.434-441
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• 2014

본 연구에서는 석면해체 제거작업에 따른 작업자 및 주변 환경에 미치는 영향 등을 파악하기 위해 서울시내 건축물 석면해체 제거 사업장을 대상으로 공기 중 석면농도를 조사하고, 측정결과가 "석면안전관리법"에서 명시된 사업장 주변의 석면배출허용기준에 적합한지를 살펴보았다. 서울시내 총 37개소 석면해체 제거 사업장에서 총 288개의 공기 중 시료를 분석하였으며, 전체 288개 시료 중 101개 시료에서(35%) 검출한계($7fiber/mm^2$) 이하로 나타났다. 이 때 전체 공기 중 석면농도 평균값은 $0.003{\pm}0.002f/cc$로(최대 0.013 f/cc) 대부분의 공기 중 석면농도는 "석면안전관리법"에서 명시된 사업장 주변의 석면배출허용기준 0.01 f/cc 이하로 나타나 서울시내 건축물 석면해체 제거 사업장에서의 석면 노출가능성은 우려할 수준이 아닌 것으로 판단된다. 채취지점별로 살펴보면, 부지경계선(148개), 위생설비입구(25개), 작업장주변(실내)(7개), 작업장주변(실외)(11개)에 대한 공기 중 석면농도 결과, 각각 53개(36%), 5개(20%), 1개(14%), 4개(36%) 시료에서 검출한계 이하로 나타났으며 평균농도는 각각 $0.002{\pm}0.002f/cc$(최대 0.008 f/cc), $0.004{\pm}0.002f/cc$(최대 0.009 f/cc), $0.004{\pm}0.002f/cc$(최대 0.007 f/cc), $0.004{\pm}0.002f/cc$로(최대 0.008 f/cc) 나타났다. 또한 음압기(13개), 폐기물보관지점(27개), 폐기물반출구(9개), 거주자주거지역(48개)에 대한 공기 중 석면농도 결과, 각각 3개(23%), 8개(30%), 2개(22%), 25개(52%) 시료에서 검출한계 이하로 나타났으며 평균농도는 각각 $0.004{\pm}0.002f/cc$(최대 0.009 f/cc), $0.005{\pm}0.004f/cc$(최대 0.013 f/cc), $0.005{\pm}0.003f/cc$(최대 0.009 f/cc), $0.003{\pm}0.002f/cc$0로(최대 0.009 f/cc) 나타났다.

• 한국환경과학회지
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• 제13권3호
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• pp.205-214
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• 2004

This study focuses on the measurement of airborne Volatile Organic Compounds (VOCs) in the Kumi electronic industrial complex during the time periods of August and September, 2002 and January and February, 2003. This study was based on the US-EPA method TO-14 while the VOCs were analyzed with GC/MSD. The toluene level revealed high concentration at all measurement sites. The areal rank of average concentrations of VOCs is as follows: industry1 > industry2 > urban > middle > residential. Concentrations of VOCs in Kumi electronic industrial ones were generally higher than at Yeochon and Ulsan industrial complexes. Dichloromethane and trichloroethylene, which are used as a cleaner in the process of electronic industries, were observed 4 to 8 times higher than those of other areas. Among the aromatic compounds, toluene showed the highest level, while the concentrations of dichloromethane and trichloroethylene were higher than those of other halogen compounds. In Kumi, toluene, trichloroethylene, and dichloromethane were confirmed as the major compounds of VOCs by this research.

• 한국대기환경학회지
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• 제18권5호
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• pp.355-362
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• 2002

There has been relatively a few studies that focused on evaluation of uncertainty for standard methods by which criteria pollutants are analyzed in ambient air. Especially, uncertainty evaluation has not been made yet for sampling and analysis of airborne NO$_2$. Ambient NO$_2$ has been thought to be a major criteria pollutant worldwide because of the potential of ozone formation as well as of its own toxicity. In this study, we tried to assess uncertainties associated with the every step of sampling and of analytical procedure of Griess-Saltzman method. Quality assurance (QA) and quality control (QC) were also emphasized with the uncertainty characterization. The use of Griess-Saltzman method for ambient NO$_2$ analysis showed very uniform daily concentration distribution with the mean of 10.8 ppb and the standard deviation of 1.08ppb during the sampling period. However, seven daily samples collected at the same sampling time and place exhibited highly different concentration distribution. Therefore, we evaluated uncertainties associated with sampling and analysis through the precise application of ISO Guide. Estimates of expanded uncertainties for a total of 62 samples fell in a relatively broad range of 5.17% to 11.85%. On the other hand. the expanded uncertainties were smaller for the high concentration range of greater than 15ppb.

• 한국가시화정보학회지
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• 제20권1호
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• pp.45-51
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• 2022

Airborne particulate matter(PM) has been a global environmental problem. PM whose diameter is smaller than 10 ㎛ can permeate respiratory organs and has harmful effects on human health. Therefore, PM monitoring systems are necessary for management of PM and prevention of PM-induced negative effects. Conventional PM monitoring techniques are expensive and cumbersome to handle. In the present study, two types of PM monitoring devices were designed for measuring indoor PM concentration, portably. We experimentally investigated the performance of three commercial PM concentration measurement sensors in a closed test chamber. As a result, PM2008 sensor showed the best PM concentration measurement accuracy. Linear regression method was applied to convert PM concentration value acquired from PM2008 sensor into ground truth value. A mobile application(app.) was also created for users to check the PM concentration, easily. The mobile app. also provides safety alarm when the PM₁₀ concentration exceeds 81 ㎛/m³. The developed hand-held system enables the facile monitoring of surrounding air quality.

• Asian Journal of Atmospheric Environment
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• 제7권3호
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• pp.139-151
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• 2013

The purpose of this study is to understand distributional characteristics in the atmospheric concentrations of $O_3$ and its precursors based on data taken at the southern Korean coast. The average $O_3$ concentration in the high altitude was found to range from 32.3 to 90.8 ppb with a maximum concentration of 132 ppb. The ambient $O_3$ concentration was high at altitudes of 1000 m and 500 m above the southern sea near Gwangyang Bay and an industrial area containing emission sources. The daily mean concentrations of $NO_y$ and CO were 6.7-24.2 ppb and 0.152-0.487 ppm, respectively. During the aerial measurement period, the highest mean concentration of $O_3$ was observed on June 1. The aerial measurement results showed that the maximum ozone concentration was observed to be 132 ppb in the high altitude the southernmost part of Yeosu. The measurement of vertical wind fields in the air indicated that $O_3$ formed in the southernmost part of Yeosu was transported by strong southwesterly winds to the northeast of Gwangyang Bay. This led to a ground $O_3$ concentration of over 100 ppb in Jinju, the northeastern part of Gwangyang Bay. On August 9, when the maximum $O_3$ concentration was 50 ppb, the measurement results showed that $O_3$ concentrations were relatively low compared to other days. In particular, low $NO_2$ and TVOC concentrations were observed, both of which serve to form $O_3$ in photochemical reactions.