• Safety and Health at Work
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• 제2권3호
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• pp.282-289
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• 2011

Objectives: We sought to establish a novel method to generate nano-sized carbon black particles (nano-CBPs) with an average size smaller than 100 nm for examining the inhalation exposure risks of experimental rats. We also tested the effect of nano-CBPs on the pulmonary and circulatory systems. Methods: We used chemical vapor deposition (CVD) without the addition of any additives to generate nano-CBPs with a particle size (electrical mobility diameter) of less than 100nm to examine the effects of inhalation exposure. Nano-CBPs were applied to a nose-only inhalation chamber system for studying the inhalation toxicity in rats. The effect on the lungs and circulatory system was determined according to the degree of inflammation as quantified by bronchoalveolar lavage fluid (BALF). The functional alteration of the hemostatic and vasomotor activities was measured by plasma coagulation, platelet activity, contraction and relaxation of blood vessels. Results: Nano-CBPs were generated in the range of 83.3-87.9 nm. Rats were exposed for 4 hour/day, 5 days/week for 4 weeks to $4.2{\times}10^6$, $6.2{\times}10^5$, and $1.3{\times}10^5$ particles/$cm^3$. Exposure of nano-CBPs by inhalation resulted in minimal pulmonary inflammation and did not appear to damage the lung tissue. In addition, there was no significant effect on blood functions, such as plasma coagulation and platelet aggregation, or on vasomotor function. Conclusion: We successfully generated nano-CBPs in the range of 83.3-87.9 nm at a maximum concentration of $4.2{\times}10^6$ particles/$cm^3$ in a nose-only inhalation chamber system. This reliable method can be useful to investigate the biological and toxicological effects of inhalation exposure to nano-CBPs on experimental rats.

• Asian Pacific Journal of Cancer Prevention
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• 제14권4호
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• pp.2461-2476
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• 2013

To assess environmental contamination with carcinogens, carbonaceous compounds, water-soluble ionic species and trace gaseous species were identified and quantified every three hours for three days st three different atmospheric layer at the heart of chiang-Mai, bangkok and hat-Yai from December 2006 to February 2007. A DRI model 2001 Themal/Optical Carbon Analyzer with the IMPROVE thermal/optical reflectance (TOR) protocol was used to quantify the organic carbon(OC) and elemental carbon content in $PM_{10}$. Diurnal and vertical variability was also carefully investigated. In general, OC and EC contenttration shoeed the highest values at the monitoring period o 21.00-00.00 as consequences of human activities at night bazaar coupled with reduction of mixing layer, decreased wind speed and termination of photolysis nighttime. Morning peaks of carboaceous compounds were observed during the sampling period of 06:00 -09:00, emphasizing the main contribution of traffic emission in the three cities. The estimation of incremental lifetime partculate matter exposure (ILPE) raises concern of high risk of carbonaceous accumulation over workers and residents living close to the observatory sites. The average values of incremental lifrtime particulate matter exposure (ILPE) of total carbon at Baiyoke Suit Hotel and Baiyoke Sky Hotel are approsimately ten time shigher then those air sample collected at prince of songkla University Hat-Yai campus corpse incinerator and fish-can maufacturing factory but only slightly higher than those of rice straw burnig in Songkla province. This indicates a high risk of developing lung cancer and other respiratory diseases across workers and residents living in high buildings located in Pratunam area. Using knowledge of carbonaceous fractions in $PM_{10}$, one can estimate the gas-particle partitioning of polycyclic aromatic hydrocarbons (PAHs). Dachs-Eisenreich model highlights the crucial role of adsorption in gas-particle partitioning of low molecular weight PAHs, whereas both absorption and adsorption tend to account for gas-particle partitioning of high molecular weight PAHs in urban residential zones of Thailand. Interestingly, the absorption mode alone plays a minor role in gas-partcle partitiining of PAHs in Chiang-Mai, Bangkok and hat-Yai.

• 한국환경과학회:학술대회논문집
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• 한국환경과학회 2001년도 가을 학술발표회 발표논문집
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• pp.198-200
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• 2001

Grager-Induced colony formation was examined using strains of green alga Scenedemus dimorphus (Turpin) Kutzing. Alga was cultured in a medium with or without filtered water in which Daphnia magna or Moina macrocopa had been reared. Colony formation was obviously promoted in S. dimorphus by exposure to zooplankton filtered water (ZFW), showing in proportion to the volume of zooplankton filtered water in cultured media. The particle volume as well as the number of cells per one colony of S. dimorphus increased between 24 and 48 hours after exposure to ZFW, which were caused by an infochemical released from from Daphnia or Moina probably as a part of defense mechanism against zooplankton grazing.

• 한국연소학회지
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• 제8권2호
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• pp.41-49
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• 2003

Ultrasonic field of 28kHz with sound pressure level 162dB has been employed to agglomerate the fine soot particle produces in a diffusion flame in a chamber. The agglomeration process has been investigated with digital camcorder and analysed in terms of the decrease of number density with exposure time. From the observation of agglomeration process, the initial agglomeration has been carried out during the short time, and it has been dominated by the orthokinetic collision. Thereafter, a slower agglomeration mechanism, driven by acoustic streaming in the chamber takes over and agglomeraters grew to diameters of several millimeters were levitated at the pressure node of the acoustic wave. And, the circular disk shape of large agglomeraters with the rotational and translational motion is observed.

• 한국환경보건학회지
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• 제17권1호
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• pp.32-38
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• 1991

Airborne suspended particulate concentration in drilling sites of underground coal mines in Taebaek area was evaluated. And respirable coal dust exposure level was evaluated. Airborne suspended particulate mass include total suspended particle(TSP) and thoracic particle(TPM). TSP (by open-face filter holder) and TPM(by elutriator) concentration were determined by low volume air samplers. Personal air samplers were attached to the coal workers including drillers, coal cutters, and their assistants. Normality and log-normality of TSP, TPM, and respirable dust(RPM) concentration were tested by Kolmogorov-Smirnov one-sample test. Differences of means of TSP, TPM, and RPM concentration were tested by paired t-test. Relation between TSP, TPM, and RPM with pairs were tested by regression test and Pearson's correlation.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2001년도 Proceedings of 2001 Korea-Japan Joint Seminar on Particle Image Velocimetry
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• pp.123-137
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• 2001

PIV (particle image velocimetry) systems use a camera to take snapshots of particles carried by a fluid at some precise instants. Signal processing methods are then used to compute the flow velocity field. In this paper, the design of the camera objective (optics) is addressed. The optimization is done in order to maximize the signal-to-noise ratio of in-focus particles. Four different kinds of noise are considered: photon shot noise, thermal and read noise, background glow shot noise, and noise made by the other particles. A semi-empirical model for the lens aberrations of a two-doublet objective is first addressed, since further, it is shown that lens aberrations (low f-value $f_{\#}$) should be used instead of the Fraunhofer diffraction (high f-value) for the fitting of the particle image size with the pixel size. Other important conclusions of the paper include the expression of optimum values for the magnification M, for the exposure period $\tau$ and for the pixel size $\xi$.

• 한국자동차공학회논문집
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• 제9권4호
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• pp.34-43
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• 2001

Analysis and control of intake charge motion such as swirl and tumble are very important to improve the performance of gasoline engines. In this paper, single frame double exposure PTV(particle tracking velocimetry) is used to investigate intake flow characteristic in a steady flow test rig of gasoline engine with 2-valve and pent-roof combustion chamber. To validate this PTV method, we confirmed reliability of this PTV method using chopper, and coaxial burner experiments. The velocity Held of intake flow is measured with the intake valve lift variation. It is shown that maximum flow velocity is increased and tumble flow become stronger than inverse tumble flow as valve lift increase.

• 한국입자에어로졸학회지
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• 제5권3호
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• pp.133-138
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• 2009

Airborne microorganisms, termed bioaerosols, are etiological agents of many respiratory and skin diseases. There are high demands of controlling the concentration of bioaerosols, specifically in indoor environments. Here, a new system for controlling indoor bioaerosols is designed and evaluated. An idea of a short time exposure to a thermal energy is used in the design of the equipment. The system was tested in laboratory environments. The experimental results show that the new system can reduce the concentration of viable bioaerosols of indoor laboratory environments.

• Nuclear Engineering and Technology
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• 제40권7호
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• pp.533-538
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• 2008

In some situations, for example at very low doses, in microbeam irradiation experiments, or around high energy heavy ion tracks, use of the absorbed dose to describe the energy transferred to the irradiated target can be misleading. Since absorbed dose is the expected value of energy per mass it takes into account all of the targets which do not have any energy deposition. In many situations that results in numerical values, in Joules per kg, which are much less than the energy deposited in targets that have been crossed by a charged particle track. This can lead to confusion about the biochemical processes that lead to the consequences of irradiation. There are a few alternative approaches to describing radiation that avoid this potential confusion. Examples of specific situations that can lead to confusion are given. It is concluded that using the particle radiance spectrum and the exposure time, instead of absorbed dose, to describe these irradiations minimizes the potential for confusion about the actual nature of the energy deposition.

• Toxicological Research
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• 제21권2호
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• pp.87-98
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• 2005

Human exposure to nano-sized particles (NSP) has increased over the last century with anthropogenic sources, and the rapid development of nanotechnology becomes an another source of such exposure. Information regarding the safety of nanotechnology and its product, nanoparticles, is urgently needed when assuming exposure through inhalation, oral intake, and penetration across skin is ever increasing as growing nanotechnology rapidly. The recent advancement of biokinetic studies with NSP and newer epidemiologic and toxicologic studies with ultrafine particles can be the basis for the nanotoxicology. Some concepts of nanotoxicology can be known from the results of these results. Specific small size of NSP, when inhaled, facilitates deposition by difusional mechanism in all regions of the respiratory tract and uptake into cells, ranscytosis across epithelial and endothelial cells into the blood and lymph circulation to reach target sites. Translocation along axons and dendrites of neuron makes an access to CNS and ganglia. These biokinetics are dependent on NSP surface chemistry. Risk assessments of NSP include appropriate and relevant doses/concentration selections, the increase effects in the organism and the benefits of possible desirable effects. An interdisciplinary team approach is desirable for nanotoxicology research and an appropriate risk assessment.