• Applied Microscopy
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• 제40권4호
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• pp.177-183
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• 2010

집속이온빔장치(focused ion beam, FIB)는 전자보다 무거운 양이온빔을 이용하여 시료를 10~100 nm 정도로 깎아 낼 수 있는 장비로 주로 재료분야에서 활용되어 왔다. 최근 세계적으로 의생물 분야에서의 활용이 점차 늘어나고 있는 추세에 있어 국내연구자들의 이해를 돕기 위해 간단히 기기의 메커니즘과 그 활용예를 기술 하고자 한다. FIB에 주로 사용되는 갈륨(Ga)빔의 특성 때문에 시료의 표면을 효과적으로 쳐 낼 수 있고, 전계 방사형 주사전자현미경(FESEM)을 이용하면 그 표면의 영상을 얻을 수 있다. 이 두 가지 시스템을 하나의 시스템으로 묶어낸 것을 dual beam system이라고 한다. 최근 이러한 시스템을 이용하여 효모, 병원균에 감염된 식물 등이 소개되었으며, 통상적으로 경도가 높아 처리하기 힘든 상아나 어패류의 껍질 등의 시료를 효과적으로 분석한 연구도 있다. 또한 FIB를 이용한 밀링과 FESEM을 이용한 절단면 촬영을 반복하여 얻는 영상을 이용하여 신경계의 연결망을 재구성하려는 연구가 활발하게 진행되고 있다. FIB/FESEM dual beam은 의생물학 분야의 다양한 연구에 활용될 수 있는 유용한 도구며, 의생물 시료의 3차원 연구에 크게 기여할 수 있을 것으로 판단된다.

• Toxicological Research
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• 제33권3호
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• pp.239-253
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• 2017

Neodymium is a future-oriented material due to its unique properties, and its use is increasing in various industrial fields worldwide. However, the toxicity caused by repeated exposure to this metal has not been studied in detail thus far. The present study was carried out to investigate the potential inhalation toxicity of nano-sized neodymium oxide ($Nd_2O_3$) following a 28-day repeated inhalation exposure in male Sprague-Dawley rats. Male rats were exposed to nano-sized $Nd_2O_3-containing$ aerosols via a nose-only inhalation system at doses of $0mg/m^3$, $0.5mg/m^3$, $2.5mg/m^3$, and $10mg/m^3$ for 6 hr/day, 5 days/week over a 28-day period, followed by a 28-day recovery period. During the experimental period, clinical signs, body weight, hematologic parameters, serum biochemical parameters, necropsy findings, organ weight, and histopathological findings were examined; neodymium distribution in the major organs and blood, bronchoalveolar lavage fluid (BALF), and oxidative stress in lung tissues were analyzed. Most of the neodymium was found to be deposited in lung tissues, showing a dose-dependent relationship. Infiltration of inflammatory cells and pulmonary alveolar proteinosis (PAP) were the main observations of lung histopathology. Infiltration of inflammatory cells was observed in the $2.5mg/m^3$ and higher dose treatment groups. PAP was observed in all treatment groups accompanied by an increase in lung weight, but was observed to a lesser extent in the $0.5mg/m^3$ treatment group. In BALF analysis, total cell counts, including macrophages and neutrophils, lactate dehydrogenase, albumin, interleukin-6, and tumor necrosis factor-alpha, increased significantly in all treatment groups. After a 4-week recovery period, these changes were generally reversed in the $0.5mg/m^3$ group, but were exacerbated in the $10mg/m^3$ group. The lowest-observed-adverse-effect concentration of nano-sized $Nd_2O_3$ was determined to be $0.5mg/m^3$, and the target organ was determined to be the lung, under the present experimental conditions in male rats.

• Korean Journal of Acupuncture
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• 제21권2호
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• pp.111-123
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• 2004

Objectives : It has been reported that Cordyceps militaris Mycelia(CMM) has an effect on deficiency allergic asthma(虛喘) clinically. The aim of this study was to determine an appropriate oriental treatment and the doses of CMM to treat asthma. Methods : In order to study the effect of herbal acupuncture solution of the CMM on allergic asthma, the mouse were pretreated by CMM herbal acupuncture at BL13, LU4 before antigen sensitization. 2 days later Mice were actively sensitized with a subcutaneous injection of ovalbumin(OA) and 13 days later they were provoked with OA aerosols. IL-4, lymphocyte, macrophage in bronchoalveolar lavage fluid(BALF), IgE in serum, WBC, RBC, HGB in blood, and in vitro isometric contractile responses of the isolated tracheal smooth muscle(TSM) to acetylcholine$(ACh,\;0.1-1000\;{\mu}M)$, KCl were measured. Results : Contractile responses of TSM to ACh were significantly increased in CMM herbal acupuncture 1 group $(Ach\;1000\;{\mu}M)$, CMM herbal acupuncture 2 group $(ACh\;1,\;10\;{\mu}M)$, CMM herbal acupuncture 3 group $(Ach\;0.3,\;1,\;30,\;300\;{\mu}M)$. The sensitivity of TSM to ACh was significantly decreased in CMM herbal acupuncture 3 group. The maximal contractile response of TSM to ACh was significantly decreased in CMM herbal acupuncture 1, 3 group. The maximal contractile response of TSM to KCl was significantly decreased in CMM herbal acupuncture 1, 2, 3 group. The counts of lymphocytes in BALF was significantly increased in CMM herbal acupuncture 3 group. The counts of macrophages in BALF was significantly decreased in CMM herbal acupuncture 3 group. Interleukin-4 level in BALF was significantly increased in CMM herbal acupuncture 1,3 group. and it was increased in CMM herbal acupuncture 2 group, but there was no significance. Serum IgE level was significantly decreased in CMM herbal acupuncture 1, 2, 3 group. The counts of WBC in blood was significantly increased in CMM herbal acupuncture 1, 3 group Conclusion : Based on the above results it is assumed that CMM herbal acupuncture at BL13, LU4 can help the treatment of deficiency allergic Asthm.

• 한국표면공학회지
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• 제12권3호
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• pp.207-216
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• 1979

Environmental pollution or contaminations caused by various kinds of pollutants have become one of most serious problems of our time. Environ mental pollution is the unfavoralble alteration of our surroundings, through direct or indirect effects of changes in energy patterns, rediation levels, chemical and physical constitution and abundances of organisms. These changes may affect humans directly or through their supplies of water and of agicultural and other biological products, their physical objects or possessions, or their opportunities for recreation and appreciation of nature. Pollutants that meet the criteria of this definition of environmental pollution are numerous: gases (such as sulfur dioxide and nitrogen oxides) and paniculate matter (such as smoke particles, lead aerosols, and asbestos) in the atmosphere; pesticides and radioactive isotopes in the atmosphee and in waterways; sewage, organic. chemicals, and phosphates in water; solid wastes on land; excessive heating (thermal pollution) of rivers and lakes; and many others. Some of these pollutants are introduced into the environment naturally, others by human actions, and most in both ways. Our major concer is with environmental pollution resulting wholly or largely as a by-product of human activities, because these can be controlled most readily. Environmental pollution cannot be solved by science and technology alone. It should be handled by an interdisciplinary approach with combined methods of science and technology as wen as social science disciplines for the better solution of this critical problem. In this respect, introducing "Environmental Science," a new scientific approach for the solution of environmental problems, which is now widely accepted by most developed countries of the world will be very helpful for systematization of theoretical basis for a new scientific approach to environmental pollution. Environmental science is "the study of all systems of air, land, water, energy, and life that surround Man. It includes all sciences directed to the system-level of understanding of the environment, drawing especially upon such disciplines as meteorology, geophysics, oceanography, and ecology, and utilizing to the fullest knowledge and techniques developed in such fields as physics, chemistry, biology, mathematics and engineering as well as many social science disciplines, such as economics, such as economics, law, political science and public administration." The components of this discipline are not new, for they are drawn from existing areas of science within biology chemistry, physics, and geoscience. What is really new about environmental science, however, is it siewpoint - its orientation to global problems, its conception of the earth as a set of interlocking, interacting systems, and its interest in Man as a part of these systems.

• 대기
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• 제21권1호
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• pp.57-67
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• 2011

2006년 3월부터 4년간 서울대학교에서 관측한 라이다와 스카이 라디오미터 관측 자료로부터 에어러솔의 라이다 비를 산출하고 그 계절 변화 특성을 살펴 보았다. 서울지역의 라이다 비는 여름철에 $68.1{\pm}16.8$ sr로 가장 높고 점차 감소하여 겨울철에 $57.2{\pm}17.9$ sr로 가장 낮았으며 다시 증가하는 경향을 보였다. 그러나 전 기간 동안 산출된 라이다 비가 30 sr에서 최대 110 sr까지의 범위에서 분포하며 관측 전 기간의 표준편차가 16.46 sr인 것을 감안하면 계절변동은 두드러지지는 않았다. 이처럼 계절 변동이 약하게 나타나는 이유는 도심지역에 해당하는 서울의 지리적 특성에 기인한 것으로 연중 인위적인 오염물질이 지속적으로 배출되어 영향을 미치기 때문으로 판단된다. 라이다와 스카이 라디오미터 관측으로 얻은 옹스트롬 지수, 편광소멸도 및 에어러솔 광학두께와 산출된 라이다 비의 관계도 살펴 보았다. 옹스트롬 지수와 편광소멸도는 음의 상관관계가 뚜렷하게 나타나 에어러솔 입자의 크기가 클 경우 비구형을 띄며 크기가 작을수록 구형에 가까워 짐을 확인할 수 있었다. 또한, 라이다 비가 작게 나타나는 깨끗한 날을 제외하면 라이다 비는 옹스트롬 지수가 증가할수록 (편광소멸도가 감소할수록) 증가하는 경향을 가졌다. 이를 바탕으로 에어러솔 광학두께가 하위 10%에 해당하는 깨끗한 날과 옹스트롬 지수가 하위 10%에 해당하는 황사입자가 우세한 사례, 옹스트롬 지수가 상위 10%에 해당하는 오염물질이 우세한 사례로 나누어 라이다 비의 특성을 살펴보았다. 오염물질이 우세한 사례에서의 라이다 비는 $62.2{\pm}13.2$ sr로 기존의 오염물질에 의한 라이다 비와 잘 일치하는 모습을 보였다. 그러나 깨끗한 날과 황사가 우세한 사례의 경우는 각각 $45.0{\pm}9.5$ sr와 $51.7{\pm}13.7$ sr로 나타나 선행 연구 결과보다는 다소 높은 값을 보였다. 이는 앞에서 언급하였다시피 도심지역에 해당하는 서울은 항상 주변에서 발생하는 인위적인 오염물질의 영향을 받기 때문인 것으로 판단할 수 있다.

• 청정기술
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• 제14권2호
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• pp.136-143
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• 2008

본 연구에서는 오리멀젼(orimulsion)을 연소하는 발전소에서 배출되는 가시백연의 가시도 증가를 확인하고, 그 원인을 파악하고자 하였다. 오리멀젼을 연료로 사용하는 발전소에서는 미세 먼지입자와 황화합물이 포함된 연기를 발생한다. 발전소 공정데이터를 바탕으로 미세 먼지입자의 영향에 대해서는 모니터링을 통한 로그정규분포로 배출입자의 입도분포를 대입하였고, 황화합물 에어로졸 2차 입자의 주성분$(NH_4)_2SO_4$의 생성 화학방정식을 고려하였다. 연기에 의한 가시도를 정량적으로 평가하고자 미국의 EPA에서 개발된 대표적 시정모델인 PLUVUE-II 모델을 응용하였다. PLUVUE-II 모델이 단파장에만 모사되는 문제를 개선하여 가시광선 전 영역에서 계산이 가능하도록 하여 가시도에 따른 최대 연기거리를 광학적 방법으로 계산하였다. 모델링 결과로써 미세입자의 분포와 황화합물의 농도에 따른 최대 연기거리의 변화를 평가하였다. 연구 결과로 오리멀젼의 연소로 발생된 가시백연이 미세입자와 황화합물의 2차 입자에 의해 유발될 수 있음을 확인하였으며, 이러한 가시백연의 저감을 위해서는 미세입자의 크기와 황 화합물의 배출에 대한 제어가 필요하다고 판단된다.

• 한국환경과학회지
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• 제15권8호
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• pp.701-718
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• 2006

The average ratio of the daily UV-B to total solar (75) irradiance at Busan (35.23$^{\circ}$N, 129.07$^{\circ}$E) in Korea is found as 0.11%. There is also a high exponential relationship between hourly UV-B and total solar irradiance: UV-B=exp (a$\times$(75-b))(R$^2$=0.93). The daily variation of total ozone is compared with the UV-B irradiance at Pohang (36.03$^{\circ}$N, 129.40$^{\circ}$E) in Korea using the Total Ozone Mapping Spectrometer (TOMS) data during the period of May to July in 2005. The total ozone (TO) has been maintained to a decreasing trend since 1979, which leading to a negative correlation with the ground-level UV-B irradiance doting the given period of cloudless day: UV-B=239.23-0.056 TO (R$^2$=0.52). The statistical predictions of daily total ozone are analyzed by using the data of the Brewer spectrophotometer and TOMS in East Asia including the Korean peninsula. The long-term monthly averages of total ozone using the multiplicative seasonal AutoRegressive Integrated Moving Average (ARIMA) model are used to predict the hourly mean UV-B irradiance by interpolating the daily mean total ozone far the predicting period. We also can predict the next day's total ozone by using regression models based on the present day's total ozone by TOMS and the next day's predicted maximum air temperature by the Meteorological Mesoscale Model 5 (MM5). These predicted and observed total ozone amounts are used to input data of the parameterization model (PM) of hourly UV-B irradiance. The PM of UV-B irradiance is based on the main parameters such as cloudiness, solar zenith angle, total ozone, opacity of aerosols, altitude, and surface albedo. The input data for the model requires daily total ozone, hourly amount and type of cloud, visibility and air pressure. To simplify cloud effects in the model, the constant cloud transmittance are used. For example, the correlation coefficient of the PM using these cloud transmissivities is shown high in more than 0.91 for cloudy days in Busan, and the relative mean bias error (RMBE) and the relative root mean square error (RRMSE) are less than 21% and 27%, respectively. In this study, the daily variations of calculated and predicted UV-B irradiance are presented in high correlation coefficients of more than 0.86 at each monitoring site of the Korean peninsula as well as East Asia. The RMBE is within 10% of the mean measured hourly irradiance, and the RRMSE is within 15% for hourly irradiance, respectively. Although errors are present in cloud amounts and total ozone, the results are still acceptable.

• 대기
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• 제27권2호
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• pp.225-233
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• 2017

Korea has recently suffered from severe hazes, largely being long-range transported from China but frequently mixed with domestic pollution. It is important to identify the origin of the frequently-occurring hazes, which is however hard to clearly determine in a quantitative term. In this regard, we suggest a possible classification procedure of various hazes into long-range transported haze (LH), Yellow Sand (YS), and urban haze (UH), based on mass loading of fine particles, time lag of PM mass concentrations between two sites aligned with dominant wind direction, backward trajectory of air mass, and the mass ratio of PM2.5 to PM10. The analysis sites are Seoul (SL) and Baengnyeongdo (BN), which are distant about 200 km from each other in the west to east direction. Aerosol concentrations at BN are overall lower than those of SL, indicative of BN being a background site for SL. We found distinct time lag of PM2.5 and PM10 concentrations between BN and SL in case of both LH and YS, but the intensity of YS being stronger than LH. Time scale (e-folding time scale) of LH appears to be longer and more variable than YS, which implies that LH covers much larger spatial scale. In addition, we found linear and significant correlations between ${\tau}_a$ obtained from sunphotometer and ${\tau}_{cal}$ calculated from surface aerosol scattering coefficient for LH episodes, relative to few correlation between those for YS, which might be associated with transported height of YS being much higher than LH. Therefore surface PM concentrations for the YS period are thought to be not representative for vertical integrated amount of aerosol loadings, probably by virtue of decoupled structure of aerosol vertical distribution. Improvement of various hazes classification based on the current result would provide the public as well as researchers with more accurate information of LH, UH, and YS, in terms of temporal scale, size, vertical distribution of aerosols, etc.

• 한국입자에어로졸학회지
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• 제9권2호
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• pp.39-50
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• 2013

SMPS, APS, ELPI는 실시간으로 대기 중 입자상 물질을 측정할 수 있는 장비로 많은 연구자들에 의해 사용되고 있다. 하지만 측정장비의 특성과 입자 분류 특성에 대한 충분한 이해가 없다면, 단순히 장비에 제공된 소프트웨어의 계산 결과를 여과 없이 그대로 사용할 수밖에 없다. 본 연구에서는 SMPS, APS, ELPI의 측정 메커니즘을 간단히 정리하였고, 전기적 이동도로 입자를 분리하는 SMPS와 공기역학적 거동을 이용하는 APS를 함께 사용하여 입자의 크기분포를 측정할 때 발생할 수 있는 문제점을 고찰하였다. 크기분포 측정결과를 이용해서 무게 농도를 환산하는 과정에서 대기 입자의 입경에 따른 밀도 정보를 제공하는 것이 매우 중요하다는 것을 보였다. 특히, APS 측정결과를 이용하는 경우 무게 농도의 추정 결과가 크게 영향을 받았다. ELPI의 경우 입자 밀도를 정확히 설정하지 않으면 입자의 수 농도에 오차가 크게 발생할 수 있으므로, 정확한 밀도를 설정하는 것이 중요했다. 반면에 ELPI로 대기 중입자상 물질의 무게 농도를 추정하는 경우 밀도가 실제와 다르게 설정되더라도 공기역학적 입경으로 나타내면 총 무게 농도는 수 농도에 비해 상대적으로 영향이 적었다. 향후 SMPS와 APS를 이용하여 시간에 따른 크기 분포 변화와 연간 수 농도와 무게 농도의 변화 추이를 측정하는 연구가 필요하다. 특히, 국내 대기 중입자의 입경에 따른 평균 밀도 혹은 유효 밀도를 측정하여 크기분포와 총 수 농도 혹은 PM2.5나 PM1에 해당하는 무게 농도를 정확하게 계산할 수 있는 데이터 환산 프로그램의 개발도 필요하다. 이와 같은 연구로 시간경과에 따라 변화하는 대기 입자의 오염원에 대한 영향을 규명하는 기초 자료를 얻을 수 있을 것이다.

• Nuclear Engineering and Technology
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• 제50권5호
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• pp.665-672
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• 2018

A venturi scrubber is an important element of Filtered Containment Venting System (FCVS) for the removal of aerosols in contaminated air. The present work involves computational fluid dynamics (CFD) study of dust particle removal efficiency of a venturi scrubber operating in self-priming mode using ANSYS CFX. Titanium oxide ($TiO_2$) particles having sizes of 1 micron have been taken as dust particles. CFD methodology to simulate the venturi scrubber has been first developed. The cascade atomization and breakup (CAB) model has been used to predict deformation of water droplets, whereas the Eulerian-Lagrangian approach has been used to handle multiphase flow involving air, dust, and water. The developed methodology has been applied to simulate venturi scrubber geometry taken from the literature. Dust particle removal efficiency has been calculated for forced feed operation of venturi scrubber and found to be in good agreement with the results available in the literature. In the second part, venturi scrubber along with a tank has been modeled in CFX, and transient simulations have been performed to study self-priming phenomenon. Self-priming has been observed by plotting the velocity vector fields of water. Suction of water in the venturi scrubber occurred due to the difference between static pressure in the venturi scrubber and the hydrostatic pressure of water inside the tank. Dust particle removal efficiency has been calculated for inlet air velocities of 1 m/s and 3 m/s. It has been observed that removal efficiency is higher in case of higher inlet air velocity.