Cutting reactor pressure vessels (RPV) into acceptable sizes for waste disposal is a key process in dismantling nuclear power plants. In the case of Kori-1, a remote oxyfuel cutting method has been developed by Doosan Heavy Industry & Construction to dismantle RPVs. Cutting radioactive material, such as RPV, generates a large number of fine and ultrafine particles incorporating radioactive isotopes. To minimize radiological exposure of dismantling workers and workplace surface contamination, understanding the characteristics of radioactive aerosols from the cutting process is crucial. However, there is a paucity of knowledge of the by-products of the cutting process. To overcome the limitations, a mock-up RPV cutting experiment was designed and established to investigate the characteristics of fine and ultrafine particles from the remote cutting process of the RPV at the Nuclear Decommissioning Center of Doosan Heavy Industry & Construction. The aerosol measurement system was composed of a cutting system, purification system, sampling system, and measurement device. The cutting system has a shielding tent and oxyfuel cutting torch and remote cutting robot arm. It was designed to prevent fine particle leakage. The shielding tent acts as a cutting chamber and is connected to the purification system. The purification system operates a pressure difference by generating an airflow which delivers aerosols from the cutting system to the purification system. The sampling system was installed at the center of the pipe which connects the shielding tent and purification system and was carefully designed to achieve isokinetic sampling for unbiased sampling. Sampled aerosols were delivered to the measurement device. A high-resolution electrical low-pressure impactor (HR-ELPI+, Dekati) is used to measure the size distribution of inhalable aerosols (Aerodynamic diameter: 6 nm to 10 μm) and to collect size classified aerosols. In this work, the mock-up reactor vessel was cut 3 times to measure the number distribution of fine and ultrafine particles and mass distribution of iron, chromium, nickel, and manganese. The number distribution of aerosols showed the bi-modal distribution; two peaks were positioned at 0.01−0.02 μm and 0.04–0.07 μm respectively. The mass distribution of metal elements showed bi-modal and trimodal distribution. Such results could be criteria for filter selection to be used in the filtration system for the cutting process and fundamental data for internal dose assessment for accidents. Future work includes the investigations relationships between the characteristics of the generated aerosols and physicochemical properties of metal elements.

This study investigates ventilation and processing methods for industrial facilities by analyzing the distribution chart and concentration of fine particles generated. Analyses of fine particles were conducted in crushing rooms, sorting room, Primary manufacturing room and packing room, where the concentration of 0.3~10.0 μm particles were measured for 10 minutes during processing of herb medicines. The result revealed that particles with sizes greater than or equal to PM2.685 took up most of the space, and the concentration of fine particles (PM10) was 1,672.24 μg/m3 in 1th crushing room, 3,144.7 μg/m3 in crushing 2nd room, 262.45 μg/m3 in sorting room, prior to processing (2,302.3 μg/m3 for Aralia continentails and 5,564.9 μg/m3 for Poria cocos), 4,656.5 μg/m3 in Primary manufacturing room, and 20,213.3 μg/m3 in packing room. The concentration of fine particles generated during manufacture of herb medicines was, in comparison to the standard of 150 μg/m3 established in the Indoor Air Quality Control Act, 1.7 to 135 times higher. High concentrations of fine particles were found in all rooms, except for packing, even with partial ventilation. Also, it can be inferred that adequate deodorization system may be required in order to control unpleasant herb odors. Through this study, it is recommended that the use of scrubbers and concealment may facilitate control of fine particles containment.

This study tried to survey air quality inside and outside the schools where are located in about 5km of industrial complex targeting aldehyde, PM10, PM2.5. Also, the aim was also to examine both a change in indoor air after 3 years and within 3 years of addition and improvement, and a change according to season. It collected specimens at totally 20 places. Aldehyde was analyzed through HPLC. PM10 and PM2.5 were measured by using Met One 831. Formaldehyde and Acetaldehyde were detected with 42.1 μg/m3 and 5.7 μg/m3 at the school where is located inside 5km of the industrial complex, and were detected with 55.0 μg/m3 and 6.8 μg/m3 at the school where is located outside 5 km. This could be confirmed to have been detected more highly in the indoor air than the outdoor air regardless of the distance from the industrial complex. Most substances were indicated to be higher by about 150% in the indoor air within 3 years than the indoor air following 3 years of addition and improvement. However, PM10 and PM2.5 were measured with 32.6 μg/m3 and 14.9 μg/m3 after 3 years and were gauged with 22.4 μg/m3 and 14.2 μg/m3 within 3 years. Seeing a seasonal change, Formaldehyde and Propionaldehyde were detected with 5.5 μg/m3 and 1.0 μg/m3 in spring, 7.7 μg/m3 and 1.6 μg/m3 in summer, and 8.3 μg/m3 and 1.9 μg/m3 in autumn. This could be confirmed the tendency of growing according to season.

This paper describes the fabrication of AlN thin films containing iron and iron nitride particles, and the magnetic and electrical properties of such films. Fe-N-Al alloy films were deposited in Ar and N2 mixtures at ambient temperature using Fe/Al composite targets in a two-facing-target DC sputtering system. X-ray diffraction results showed that the Fe-N-Al films were amorphous, and after annealing for 5 h both AlN and bcc-Fe/bct-FeNx phases appeared. Structure changes in the FeNx phases were explained in terms of occupied nitrogen atoms. Electron diffraction and transmission electron microscopy observations revealed that iron and iron nitride particles were randomly dispersed in annealed AlN films. The grain size of magnetic particles ranged from 5 to 20 nm in diameter depending on annealing conditions. The saturation magnetization as a function of the annealing time for the Fe55N20Al25 films when annealed at 573, 773 and 873 K. At these temperatures, the amount of iron/iron nitride particles increased with increasing annealing time. An increase in the saturation magnetization is explained qualitatively in terms of the amount of such magnetic particles in the film. The resistivity increased monotonously with decreasing Fe content, being consistent with randomly dispersed iron/iron nitride particles in the AlN film. The coercive force was evaluated to be larger than 6.4×103Am-1 (80 Oe). This large value is ascribed to a residual stress restrained in the ferromagnetic particles, which is considered to be related to the present preparation process.

In T-mixer crystallization, supersaturation is generated by mixing of another solvent or non-solvent in order to reduce the solubility of the compound. Also, T-mixer is a type of continuous crystallization. In order to induce micro-mixing, two solutions were mixed rapidly by T-mixer, which formed high supersaturation. As the results, mean size of HMX crystals decreased with increasing de-supersaturation rate (Rs). Eventually, HMX particles ranging from 0.5 to 5μm can be obtained by T-mixer crystallization. Mixing efficiency in T-mixer increased with increasing Rs values. In T-mixer crystallization without surfactants, homogeneous nucleation was formed when S and Rs was over 54 and 1.6×103/sec. In T-mixer crystallization with surfactants, homogeneous nucleation was formed when S and Rs was over 26 and 7.4/sec.

The ultra-fine particles emitted by automobile are emerging issue because it is known to have adverse human health effect. Particles emitted from automobile and other engines are a complex mixture of elementary and organic carbons and other chemicals. Especially diesel particles are mainly composed of elemental carbon (soot) and volatile compounds derived from unburned and partially burned fuel, and lubricating oil and sulfate. More than 90% of particle number is usually in the ultra-fine particle size range. Ultra-fine particles are known to have increased ability to cause pulmonary inflammation. Adverse health effect may be explained by the greater surface area of the ultra-fine material, which delivered oxidative stress because of a greater surface for the generation of free radicals by as yet unknown mechanisms, or for release of redox-active transition metals and organics. In conclusion, over the past decade attention has been paid on physical/chemical characteristic, mechanism, toxicity, health effects, however, we do not have enough information about ultra-fine particles. So we need to conduct continuous research and management on ultra-fine particles.

부산지역에서 PM10 과 PM2.5중의 금속 성분 농도를 파악하기 위하여 2004년 3월부터 2004년 12월까지 조사하였다. PM10의 평균농도는 58.2μg/m3 농도범위는 8.3~161.1μg/m3이었으며, PM2.5의 평균농도는 29.3μg/m3, 농도범위는 2.8~65.3μg/m3였다. PM10의 평균 질량농도는 황사시 121.5μg/m3, 비황사시 56.0μg/m3로 나타났다. 10 이상의 지각농축계수를 보인 성분은 Cd, Cr, Cu, Ni, Pb 및 Zn로서 인위적기원을 받은 것으로 추정된다. PM10과 PM2.5 중 미량금속 성분의 지각농축계수는 황사시보다 비황사시에 높게 나타났으며, 인근의 공단지역으로부터 인위적 오염물질이 수송된 것으로 추정된다. PM10과 PM2.5의 토양입자의 평균 기여율은 각각 15.2%와17.5%였다. 토양기여율의 황사/비황사비는 PM10과 PM2.5에서 각각 1.9와 2.1로 나타났다.

반도체 산업의 wafer 가공공정에서 발생하는 폐수를 재활용하고자 한외여과 공정을 이용한 막분리 공정의 도입 가능성을 검토하였다. Pilot 규모의 장치에 분획분자량이 각각 10,000, 20.000, 30,000인 한외여과막 모듈을 이용하여 투과유속 및 제거율 등을 측정하였다. 투과수의 성상은 SDI15, 탁도, 전기전도도, 실리콘 농도분석을 통해 공정수로 재이용이 가능함을 확인할 수 있었다. 투과유속 저하를 막기 위한 역세척 방법으로는 압축공기와 물은 sweeping 하는 방법이 가장 효과적이었고, 이때 투과유속의 회복율이 높게 나타났다. 분획분자량 30,000인 한외여과막에서 가장 높은 투과유속을 나타내었다. 또한 폐수의 평균 실리콘 입자 평균 함량은 3.8-5.6mg/ℓ이고, 투과수의 실리콘 입자 함량은 0.2μg/ℓ이하로 나타나 제거율은약 96%이상으로 나타났다.

수직형 FHD증착법을 사용하여 SiO2, SiO2-P2O5, SiO2P2O5-B2O3-GeO2계 실리카 유리미립자를 형성하였으며, SEM, ICP-AES, XRD, TGA-DSC을 사용하여 그 특성을 분석하였다. XRD측정을 통해, 미립자 형성시 사용된 화염온도(1300˚C-1500˚C)와 기판온도(-200˚C)가 SiO2-P2O5계 미립자를 비정질상태로 형성하였으며, SiO2P2O5-B2O3와 SiO2P2O5-B2O3-GeO2계 미립자에서는 B2O3, BPO4, GeO2의 결정성피크들을 관찰하였다. TGA-DSC 열분석을 통해, SiO2와 SiO2-P2O5는 온도변화에 따른 질량변화가 없었으며, SiO2P2O5-B2O3-GeO2계의 경우 질량감소를 동반한 유리전이에 따른 분자이완현상 및 결정화나 회복반응을 나타내고 있다. 질량감소는 미립자가 결정상태일때 가속되는 경향을 나타냈으며, DSC열분석을 통해 SiO2, SiO2-P2O5, SiO2P2O5-B2O3-GeO2계 유리미립자들의 고밀화가 시작되는 온도를 각각 1224˚C, 1151˚C, 953˚C, 1130˚C에서 관찰하였다.

침상의 괴타이트 합성조건을 구하고 Co/가스에 의한 침탄법으로 Fe3C 단상을 얻을 조건을 구하여 그 자기적 특성을 조사한 결과 침상의 괴타이트는 공기 유입량을 1500ml/min, 반응온도 50˚C의 조건하에서 교반속도 500rpm, pH 12.0 이상에서 이상적인 분말을 합성할 수 있었으며 교반속도가 증가할수록 미세하고 입도 분포도 좁고 균일하였다. 탄화반응은 유리탄소를 방지하기 위하여 CO가스와 N2가스를 1:2로 혼입하였으며 550˚C, 60min. 이상의 반응조건하에서 Fe3C단상의 포화자화값은 탄화반응 온도에 관계없이 100/emu/g으로 일정하였으며 보자력은 780 에서 400Oe까지, 각형비는 0.35에서 0.13까지 탄화잔응 온도가 증가할수록 감소하였다.

This research investigated the characteristics of fine particles during cold front passage in Busan, on March 19, 2020. The cold front speed was 17.4 m/s (about 63k km/hr), moving from the northwest to the southeast, and with a width of about 64 km. The backward trajectory analysis showed that a southern sea air parcel flowed into Busan before the cold front passage, carrying continental materials from China transported into Busan after cold front passage. The PM10 concentration in Busan showed a rapid increase after passing through the cold front, with PM2.5 showing a high concentration during cold front passage. The PM2.5/PM10 ratio was 0.10 - 0.30. When the cold front passed, SO4 2-, NO3 -, Ca2+, NH4 +, Na+, and K+ in PM2.5 showed a rapid increase, with SO4 2- showing the most significant increase. These results indicated that understanding the characteristics of fine particles during cold front passage in Busan could provide insight into establishing a strategy to control urban air quality.

This research investigated the characteristics of PM10 and PM2.5 concentration at roadside (Choryangdong) and residential (Sujeongdong) locations in Busan. The PM10 concentration at roadside and residential locations were 50.5 and 42.9 ㎍/m3, respectively, and PM2.5 at roadside and residential were 28.1 and 23.9 ㎍/m3, respectively. The roadside/residential ratio of PM10 and PM2.5 concentration were 1.18, and the PM2.5/PM10 ratio at roadside and residential were 0.55 and 0.56, respectively. The PM10 concentration in spring at roadside were 64.6 ㎍/m3, and were the highest, followed by 48.0 ㎍/m3 and 45.2 ㎍/m3 in winter and summer. Number of exceedances per year of the daily limit value for PM10 at roadside and residential were 66 and 39 days, respectively. The PM10 and PM2.5 concentration, and PM2.5/PM10 ratio at roadside were 53.0 ㎍/m3, 29.0 ㎍/m3 and 0.55 for day, and 45.5 ㎍/m3, 26.7 ㎍/m3 and 0.59 for night, respectively. These results indicate that understanding the relationship between roadside and residential could provide insight into establishing a strategy to control urban air quality.

The study investigates the characteristics of PM10 concentration in Guducsan air quality observatory and in particular, analyzes the relationship between sudden increase of PM10 concentration in the morning of spring 2014 and meteorological parameters. PM10 concentration in April was 46.9 ㎍/㎥, the highest, followed by 45.5 ㎍/㎥ and 44.6 ㎍/㎥ in March and May, and 21.9 ㎍/㎥ in August. The low concentration in the early morning appeared on 0800 LST in spring, summer, and fall, whereas it emerged on 0900 LST in winter. High concentration in daytime lasted from 1200 LST to 1500 LST in spring and fall, whereas it continued from 1300 LST to 1600 LST in winter. The findings of PM10 concentration and change of meteorological parameters in Guducsan from April 20th to 27th in 2014 are as follows. The low concentration at dawn and in the morning decreased due to strong land breeze. Also, the sudden increase of PM10 concentration in the morning was attributable to low wind speed. Lastly, the sudden decrease of PM10 concentration in the afternoon was attributed to diffusion by strong sea breeze.

The results of particulate matters level and heavy metal concentration, which surveyed in Gwang-Yang, Dang-Jin steel industry area, are as follows; The PM2.5, PM10 of exposure area are 22.3μg/m3, 40.4μg/m3 each in Kum-Ho dong, and 28.1μg/m3, 51.5 each in Jung dong. The PM2.5, PM10 of control area are 16.4μg/m3, 29.5μg/m3 each in Bonggang-myeon. The level is higher in exposure area than control area. In case of Dang Jin, the concentration of PM10 and PM2.5 is higher in exposure area than control area (PM2.5-20.4μg/m3, PM10-39.2μg/m3). The Pb level of Dang Jin area is higher in exposure area(0.13μg/m3) than control area(0.1μg/m3), and both Gwang-Yang and Dang-Jin area lower level than the Guideline level of Korea EPA.

Several samplers using gravimetric methods such as high-volume air sampler, MiniVol portable sampler, personal environmental monitor(PEM) and cyclone were applied to determine the concentrations of fine particles in atmospheric condition. Comparative evaluation between high-volume air sampler and MiniVol portable sampler for PM10, and between MiniVol portable sampler and PEM was undertaken from June, 2003 to January 2004. Simultaneously, meteorological conditions such as wind speed, wind direction, relative humidity and temperature was measured to check the factors affecting the concentrations of fine particles. In addition, particle concentrations by cyclone with an aerodynamic diameter of 4 ㎛ were measured. Correlation coefficient between high- volume air sampler and portable air sampler for PM10 was 0.79 (p<0.001). However, the mean concentration for PM10 by high-volume air sampler was significantly higher than that by MiniVol portable sampler (p=0.018). Correlation coefficient between Minivol portable sampler and PEM for PM2.5 was 0.74 (p<0.001), and the measured mean concentrations for PM2.5 did not show significant difference. Difference of the measured concentrations of fine particle might be explained by wind speed and humidity among meteorological conditions. Particle concentration differences by measurement samplers were proportional to the wind speed, but inversely proportional to the relative humidity, though it was not a significant correlation.