• 한국멀티미디어학회논문지
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• 제4권5호
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• pp.406-413
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• 2001

일반 적인 고속 블록정합 알고리즘들은 현재 프레임의 탐색 블록과 참조 프레임의 탐색영역 내의 블록간 MAD(Mean Absolute Distance)를 비교하기 때문에 탐색점 수만큼 MAD를 구해야 하는 단점이 있다. 이와 같은 고속 블록정합 알고리즘들의 단점을 해결하기 위해 "이웃한 화소는 서로 간에 거의 같은 값을 지니고 있다"라는 특성을 이용한 MMAD 연산법에 의한 고속 DS알고리즘을 제안하였다. 본 논문에서는 각 탐색 단계별로 새로운 탐색점의 MAD를 산출하는 기존의 MAD 연산법을 탈피하고, 이전 단계에서 연산된 MAD를 MMAD 연산법에 의해 현재의 탐색점의 MAD로 사용하기 때문에 불필요한 탐색점의 블록간 MAD 연산을 없앨 수 있었다. 움직임 추정 오차는 기존 고속 블록정합 알고리즘과 비교했을 때 비슷한 성능을 나타내었고, 총 연산량은 2F$N_2$Ep만큼 크게 줄어들었다. 크게 줄어들었다.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2007년도 가을 학술발표논문집 Vol.34 No.2 (C)
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• pp.510-515
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• 2007

2차원 영상으로부터 3차원 정보를 획득하기 위해서는 disparity map의 정확한 계산이 요구된다. Disparity map을 구하기 위한 기존의 알고리즘은 크게 상관도 기반 방법과 특징 기반 방법으로 분류되는데, 본 논문에서는 이들 각 방법에 대한 분석을 통해서 좀 더 정확한 disparity map을 구하는 방법을 모색한다. 이를 위해 스테레오 카메라로부터 획득된 2차원 영상에서 건물에 대한 깊이 정보 추출을 위해 SIFT 기법을 이용한 disparity map 생성 알고리즘을 제안한다. 제안된 기법은 수정된 MAD인 MMAD(Modified Mean of Absolute Differences) 알고리즘을 새로 제안하여 영역 기반의 유사도 측정을 기반으로 하면서 특징 기반 방법의 하나인 SIFT를 적용하여 거짓 정합(false matching)에 의한 에러를 줄이고 폐색(occlusion) 영역에 대한 오류를 보정한 disparity map을 생성하는데 초점을 둔다.

• Clinical and Experimental Pediatrics
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• 제46권12호
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• pp.1235-1241
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• 2003

목 적 : 현재 시중에 판매되고 있는 연무기 기종에 따라 그 성능이 다를 것으로 보고 제품 선택에 도움이 되고자 국내 시판중인 16가지 연무기 기종의 성능을 실험을 통하여 비교하였다. 방 법 : 16가지 연무기/압축기 제품(Pariboy Type 38/Long life, Pariboy Type N/Long life, Pariboy Type N/Salter 8900, Pariboy Type N/LC, Devilbiss pulmoaid-LT/Hudson, Devilbiss pulmoaid/Hudson, Mesmed neb-300/Own, San-up 3040/Hudson, Midas(Basic)/Own, AirJolie2/Hudson, Thomas 1127/Salter 8900, Noel NE-2000/Salter 8900, Omron CX3/Hudson, Chang Woo CWN-100/Salter 8900, Voyage/Mefar, ASI-Pro/Medel jet pluse)을 가지고 Mass output과 입자 크기를 측정하였다. Mass output은 생리식염수 4 mL를 2분간 분무 전, 후의 무게변화를 정밀 전자저울로 측정하였다. 동일한 방법으로 생리식염수 3 mL를 채워 실험하였다. 입자의 크기는 0.9% 생리식염수 4 mL를 채우고 5분간 작동하면서 laser diffraction법을 이용하여 측정하였다. 결 과 : 분당흡입량은 Pariboy type N/Long life이 0.184 mg/min로 가장 높은 값을 보였으며 0.019 mg/min로 가장 낮은 수치를 나타낸 Mesmed Neb-300/Own과는 약 9.6배의 차이를 보였다. Pariboy Type N/Long life이 Mass output이 0.68 mg/min로 가장 컸고 0.13 mg/min으로 가장 작은 수치를 보인 Mesmed-Neb/Own과는 5.2 배 차이가 있었다. 모든 제품은 5분간의 입자의 크기를 측정하였으나 검사시간 동안 입자크기의 차이는 보이지 않았다. $5{\mu}m$ 이하의 입자크기의 최대값은 64%였고 최소값의 연무기는 20%였다. MMAD는 Pariboy Type N/Long life이 $3.76{\mu}m$로 가장 작았으며 나머지 제품은 모두 $5{\mu}m$ 이상이었다. 결 론 : 시중에 판매되는 연무기들의 기능이 다양하므로 제품의 선택에 있어서 그 성능을 고려할 필요가 있다.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2009년도 IWAIT
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• pp.418-422
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• 2009

Generally, algorithms for generating disparity maps can be clssified into two categories: region-based method and feature-based method. The main focus of this research is to generate a disparity map with an accuracy depth information for 3-dimensional reconstructing. Basically, the region-based method and the feature-based method are simultaneously included in the proposed algorithm, so that the existing problems including false matching and occlusion can be effectively solved. As a region-based method, regions of false matching are extracted by the proposed MMAD(Modified Mean of Absolute Differences) algorithm which is a modification of the existing MAD(Mean of Absolute Differences) algorithm. As a feature-based method, the proposed method eliminates false matching errors by calculating the vector with SIFT and compensates the occluded regions by using a pair of adjacent SIFT matching points, so that the errors are reduced and the disparity map becomes more accurate.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 G
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• pp.2527-2529
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• 1998

Measurement equipment, which consists of He-Ne laser, objective lens, CCD camera and position sensitive detector, was developed for the dynamic response of micromirror. This equipment can measure the tilting direction and angle, the rise time and frequency response of micromirror to the input signal. It was found that the rise time of the micromirror was less than 10${\mu}m$ and the resonant frequency was about 25kHz.

• 한국산업보건학회지
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• 제24권4호
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• pp.453-461
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• 2014

Objective: Based on the fact that fine particles are more likely to produce negative influences on the health of occupants as well as the quality of indoor air compared to coarse particles, it is critical to determine concentrations of aerosol particles with different sizes. Thus, this study focused on the size distribution and concentrations of aerosol particles in university buildings. Method: Aerosol particles in indoor air were collected from four areas: corridors in buildings(In-CO), lecture rooms(In-RO), laboratories(In-LR), and a cafeteria(In-RE). Samples were also collected from outside for comparison between the concentrations of indoor and outdoor particles. For the collection of the samples, an eight stage non-viable cascade impactor was used. Result: The average concentration of $PM_{10}$ in the samples collected from indoor areas was $34.65-91.08{\mu}g/m^3$,and the average for $PM_{2.5}$ was $22.65-60.40{\mu}g/m^3$. The concentrations of the aerosol particles in the corridors, lecture rooms, and laboratories were relatively higher than the concentrations collected from other areas. Furthermore, in terms of mass median aerodynamic diameter(MMAD), the corridors and lecture rooms had higher numbers due to their characteristics, showing $2.36{\mu}m$ and $2.11{\mu}m$, respectively. Laboratories running an electrolysis experiment showed $1.58{\mu}m$, and the cafeteria with regular maintenance and ventilation had $1.96{\mu}m$. Conclusion: The results showed that the $PM_{10}$ concentrations of all samples did not exceed indoor air quality standards. However, the $PM_{2.5}$ concentration was over the standard and, in particular, the concentration of fine particles collected from the laboratories was relatively higher, which could be an issue for the occupants. Therefore, it is important to improve the quality of the indoor air in university buildings.

• 한국환경보건학회지
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• 제22권3호
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• pp.64-71
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• 1996

Measurement of concentration and size distribution of TSP, ammonium, nitrate and sulfate were made from Mar., 1991. to June., 1992 in Seoul. The seasonal variation of concentration and size distribution of aerosols has been investiated. Aerosol were collected and size frationated by Andersen air sampler. Size classified samples were extrated with deionized water and analyzed for ammonium, nitrate and sulfate by ion chromatography. As the results of measurement, the average of concentration and MMAD(mass median aerodynamic diameter) were $118.58 \mu g/m^3$, and $2.77 \mu m$ for TSP, $1.92 \mu g/m^3$ and $1.35 \mu m$ for ammonium, $1.34 \mu g/m^3$ and $1.58 \mu m$ for nitrate, $8.52 \mu g/m^3$ and $2.15 \mu m$ for sulfate. The Seasonal variation of concentration and size distribution was observed for ammonium, nitrate and sulfate. The concentration peak of TSP was observed in coarse particles in spring and observed in fine particles in winter. The concentration's distribution of TSP, ammonium, nitrate and sulfate was observed bimodal type during all season.

• 한국환경보건학회지
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• 제28권4호
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• pp.12-16
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• 2002

Workers' exposure to lead particles with diverse characteristics was assessed using personal cascade impactors in four different industries. Correlation analyses found that total airborne lead (PbA) concentrations could not explain the variation on MMAD of lead particles. From regression analysis, the concentrations of lead particles smaller than 1 um in AD were found to rise very slowly with increases in total PbA. They rarely contributed more than 50 ㎍/㎥ of total PbA over the range of 5.6-7,740 ㎍/㎥ although there are a few high values greater than 100 ㎍/㎥ while respirable lead concentrations significantly increased with increasing total PbA concentrations. In the secondary smelting and radiator manufacturing industries requiring high temperatures, the average fraction of respirable concentration in total PbA was 43.3% and 48.9%, respectively, which indicated an important contribution to the total PbA. In lead powder and battery manufacturing, it was less than 27%. Our study results concluded that workers' exposure to lead particles with diverse characteristics might not be effectively monitored by the current total PbA sampling alone. To protect workers exposed to different sizes of lead particles generated in many operations, an occupational standard for respirable lead particles should be added to the current total lead standard.

• 한국환경과학회지
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• 제29권1호
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• pp.79-93
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• 2020

To determine the size distributions of water-soluble inorganic ionic species (WSIS) in roadside aerosols, sampling experiments were carried out in the urban roadside area of Jeju City on August 2018 and January 2019 by using the eight-stage cascade impactor sampler. The mass of roadside aerosols were partitioned at 57% in fine fraction, 36-37% in coarse fraction, and 6-7% in giant fraction, regardless of summer and winter. The mass concentrations of WSIS except for Na+ and SO42- in roadside aerosols were higher in winter than in summer. The size distributions of Na⁺, Mg²⁺, Ca²⁺ and Cl^- were characterized by bimodal types with coarse particle mode peaking around 3.3-4.7 ㎛ and 5.8-9.0 ㎛. The size distributions of NO₃^- and K⁺ shifted from a single fine mode peaking around 0.7-1.1 ㎛ in winter to bimodal and/or trimodal types with peaks around coarse mode in summer. SO₄^2- and NH₄⁺ showed a single fine mode peaking around 0.7-1.1 ㎛. The MMAD of roadside aerosols was lower than that of Na⁺, Mg²⁺, Ca²⁺ and Cl-. Based on the marine enrichment factors and the ratio values of WSIS and the corresponding value for sea water, the composition of roadside aerosols in Jeju City may be practically affected by terrestrial sources rather than marine source.

• 한국산업보건학회지
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• 제26권1호
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• pp.30-37
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• 2016

Objectives: This study was performed to measure and evaluate the concentration, size distribution and fugitive emission of particulate matter from process operations at foundries. Methods: Particle matter was collected from three foundries, and samples were also collected from a background site for calculating the fugitive emission concentration of the foundries. For the collection of the samples, a Nanosampler cascade impactor was used. Results: The concentration of TSP in the samples collected from the three foundries was $0.675{\sim}1.222mg/m^3$, $PM_{10}$ was $0.525{\sim}1.018mg/m^3$ and $PM_{2.5}$ was $0.192{\sim}0.615mg/m^3$. The mass size distribution was bimodal or monomodal with maximum peak at two stage(size $2.5{\sim}10{\mu}m$). The mass median aerodynamic diameter(MMAD) was $1.80{\sim}3.98{\mu}m$. The fugitive emission concentration of TSP varies in the range of 0.65 to $1.21mg/m^3$, which exceeds the emission standard of fugitive dust($0.5mg/m^3$). Conclusions: Particle concentration and size is an important industrial hygiene factor to protect foundry workers. Furthermore, the presence of high emission of particulate pollutants has a significant negative impact on the ambient air of the study area. Therefore, it is important to improve both the process and prevention facility in oder to reduce particulate pollutants in foundries.