• 방사성폐기물학회지
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• 제11권3호
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• pp.245-251
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• 2013

NaI(Tl) 섬광검출기로 측정한 에너지 스펙트럼으로부터 공간 감마 선량률을 계산하기 위하여 에너지밴드 방법과 G-factor 방법의 결과를 비교 검토하였다. 먼저 한국원자력연구원 내 운영 중인 환경방사선감시기 EFRD 3300에 장착된 3"${\Phi}X3$" NaI(Tl) 검출기의 G-factor를 MCNP 모델링을 통하여 입사 방사선의 방향에 따라 각각 구하였으며, 이로부터 계산된 선량률과 에너지밴드 방법으로 계산된 결과의 차이를 비교 검토함으로써 EFRD 3300에 적용 가능한 최적의 G-factor 값을 유도하였다. 그리고 EFRD 3300 방사선감시기가 운영되고 있는 지역 주변에 위치한 HPIC 방사선감시기의 선량률과 비교 검토를 수행하였으며, 3"${\Phi}X3$" NaI(Tl) 검출기 기반의 EFRD 3300에서 $7.7{\mu}R/h$의 측정값을 얻어 약 $3{\mu}R/h$ 정도의 차이를 보였다. 일반적으로 HPIC 방사선감시기는 고에너지 우주방사선량도 측정할 수 있는 것으로 알려져 있으므로, 이 차이는 3"${\Phi}X3$" NaI 계측기로 측정되지 못하는 고에너지 영역의 우주방사선에 의한 영향으로 평가할 수 있었다.

• 한국환경보건학회지
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• 제41권6호
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• pp.369-379
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• 2015

Objectives: The lack of reliable information on environmental pollution and health impacts related to asbestos contamination from abandoned mines has drawn attention to the need for a community health study. This study was performed to evaluate asbestos-related health symptoms among residents near abandoned asbestos mines located in the Chungcheong Provinces. In addition, exposure assessment for asbestos is needed although the exposure to asbestos was in the past. Methods: Past exposure to asbestos among inhabitants near abandoned asbestos mines was estimated by using surface sampling of deposited dust in indoor and outdoor residences. A total of 54 participants were divided into two groups with (34 cases) and without (20 controls) diseases related to asbestos. Surface sampling of deposited dust was carried out in indoor and outdoor residences by collecting 105 samples. Deposited dust for sampling was analyzed by polarization microscope (PLM) and scanning electron microscope?energy dispersive x-ray spectrometer (SEM-EDX) to detect asbestos. Subsequently, the elements of the deposited dust with asbestos were analyzed by SEM-EDX to assess the contribution of sources such as abandoned mines, slate and soil. Results: Among the 105 samples, asbestos was detected by PLM in 29 (27.6%) sampling points, and detected by SEM in 56 (48.6%) sampling points. Asbestos in indoor residences was detected by PLM in four sampling points, and by SEM in 12 sampling points. Asbestos detection in indoor residences may be due to ventilation between indoors and outdoors, and indicates long-term exposure. The asbestos detection rate for outdoor residences in the case group was higher than that in the control group. This can be explained as the case group having had higher exposure to asbestos, and there has been continuous exposure to asbestos in the control group as well as the case group. Conclusion: Past residential asbestos exposure may be associated with asbestosis among local residents near abandoned asbestos mines. Odds ratios were calculated for asbestos detection in outdoor residence by logistic regression analysis. Odds ratio between asbestos detection and asbestosis pulmonum was 3.36 (95% CI 0.90-12.53) (p=0.072), adjusting for age, sex, smoking status and work history with multi-variable logistic regression by PLM analysis method.

• 한국환경보건학회지
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• 제36권5호
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• pp.351-359
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• 2010

The objectives of this study were to understand the characteristics of residents in industrial areas and factors affecting exposure to the Volatile Organic Compounds(VOCs : Benzene, Toluene, Xylene) as well as to assess exposure levels according to house-type, and whether residents were indoors or outdoors. This research was designed to assess the differences in exposure levels to indoor, outdoor and personal VOCs in a case group and a control group across all areas, as well as in each different area, from May to October 2007, in. 110 residents of the G, Y and H industrial areas of the Jun-nam province. The geometric mea-levels of airborne benzene for the case group 1.31part per billion(ppb) indoor, 1.29 ppb outdoor, and 1.32 ppb for personal exposure were significantly higher than for the control group 0.99, 0.87 and 0.57 ppb, respectively. The geometric mean level for toluene personal exposure across the G, Y and H areas was 5.70 ppb for the case group and 6.31 ppb for the control group. While the outdoor level was 4.27 ppb for the case group and 5.06 ppb for the control group, The indoor level for the case group was 4.78 ppb, similar to that of the control group 4.69 ppb. The geometric mean levels for airborne xylene across the G, Y and H areas were 0.16 ppb(outdoor), 0.12 ppb(personal exposure) and 0.10 ppb(indoor) for the case group, and for the control group were 0.17(personal exposure) and 0.09 ppb(indoor and outdoor). The indoor/outdoor(I/O) ratio for case group is 1.19, while that of the control group is 1.15, indicating that the indoor level was higher than the outdoor level. The interrelationship differences among the three different types of levels in the air in the G, Y and H areas are statistically significant, except for the difference between the indoor and outdoor figures for xylene. In terms of the different types of houses and energy type uesd, the geometric mean level for airborne benzene, toluene and xylene for houses were 1.61, 5.39 and 0.12 ppb, respectively. while the figures for flats were 0.67, 3.32 and 0.05 ppb, respectively. Outdoors, the levels of benzene and toluene in flats were 0.71 and 2.62 ppb, respectively. and 1.58 and 5.35 ppb in houses. For personal exposure, the house levels of benzene, toluene and xylene were all higher than for flats. Houses using oil for heating have significantly higher levels than flats, which use gas for heating.

• 대한디지털의료영상학회논문지
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• 제12권1호
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• pp.51-58
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• 2010

Ionization chambers often exhibit a stem effect, caused by interactions of radiation with air near the chamber end, or with dielectric in the chamber stem or cable. In this study measured stem effect correction factor for length of ionization chamber from medical linear accelerator recommend to with the use of stem correction method. For a model of the Farmer-type chamber, were used to calculate the beam quality correction factor. These interactions contribute to the apparent measured exposure. Additionally, it needs to consider ionization chamber use of small volume and stem effect of cable by a large field. Linear accelerator generated photons energy and increased dose repeatedly measured by using stem correction method. Stem effect was dependence of the energy and increases with photon energy conditions improved of beam quality. In conclusion, stem effect correction factor was measured within 0.4% calculated according to the exposures stem length and also supposed to determined below 1% of another stem correction method.

• Nuclear Engineering and Technology
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• 제13권3호
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• pp.161-167
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• 1981

자주달개비(Tradescantia) BNL clone 4430을 본 연구소 감마농장(${\gamma}$-field)에 거리별로 배치하고 ${\gamma}$-선을 3.6mR/day~182R/day의 선량율로 완조사시켜, 이 식물의 수술털에 나타나는 분홍색 체세포돌연변이를 대상으로 돌연변이의 출현율을 조사하는 한편 화기에 미치는 형태변화를 조사하였다. 분홍색 체세포돌연변이율은 22.2R/day의 선량율에서 수술털 1,000개당 85.81$\pm$6.45개로 가장 높았고, 이보다 높은 선량율에서는 오히려 변이율이 감소하여 포화선량효과를 초래하였다. 또한 3.6mR/day의 낮은 선량율체서도 이 체세포돌연변이율이 자연돌연변이율보다 증가하였음을 볼 수 있었으며 비교적 낮은 선량율 조사에서는 꽃, 수술, 수술털등의 형태적 변화가 없이 돌연 변이율만의 증가를 볼수가 있어 감마농장내에서 과수나 화목등 영년식물에 저선량의 완조사를 통해 체세포돌연변이의 유기가 가능할것으로 보이며, 한편 이 식물의 특성을 이용하여 저위 방사선에 의한 유전적변화를 탐지하는데에도 적절한 수단이 될 것 같다.

• 한국세라믹학회지
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• 제48권5호
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• pp.426-432
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• 2011

The oxidation behavior of CVD ${\beta}$-SiC was investigated for Very High Temperature Gas-Cooled Reactor (VHTR) applications. This study focused on the surface analysis of the oxidized CVD ${\beta}$-SiC to observe the effect of impurity gases on active/passive oxidation. Oxidation test was carried out at $950^{\circ}C$ in the impurity-controlled helium environment that contained $H_2$, $H_2O$, CO, and $CH_4$ in order to simulate VHTR coolant chemistry. For 250 h of exposure to the helium, weight changes were barely measurable when $H_2O$ in the bulk gas was carefully controlled between 0.02 and 0.1 Pa. Surface morphology also did not change based on AFM observation. However, XPS analysis results indicated that a very small amount of $SiO_2$ was formed by the reaction of SiC with $H_2O$ at the initial stage of oxidation when $H_2O$ partial pressure in the CVD ${\beta}$-SiC surface placed on the passive oxidation region. As the oxidation progressed, $H_2O$ consumed and its partial pressure in the surface decreased to the active/passive oxidation transition region. At the steady state, more oxidation did not observable up to 250 h of exposure.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 추계학술대회 초록집
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• pp.159.2-159.2
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• 2010

Asbestos is the collective name for a group of naturally occurring minerals in their fibrous form and hydrous silicates of magnesium and a mineral fiber that has been used commonly in a variety of building construction materials for insulation and as a fire-retardant. Asbestos has been used for a wide range of manufactured goods, because of its fiber strength and heat resistant properties. Nevertheless harmful of asbestos is quite serious. Exposure to airborne friable asbestos may result in a potential health risk because persons breathing the air may breathe in asbestos fibers. Continued exposure can increase the amount of fibers that remain in the lung. Fibers embedded in lung tissue over time may cause serious lung diseases including asbestosis, lung cancer. In this paper, we carried out as fundamental study for dispose of asbestos cement slate safely and perfectly. Melting Temperature of asbestos need to more than $1,520^{\circ}C$ and specially asbestos cement slate need more energy than that of pure asbestos. We need to decrease melting temperature of asbestos cement slate for economical efficiency. To the purpose, glass and bottom ash were chosen as additives for basicity control. we analyzed about properties of asbestos cements slate, melting characteristics on the additives ratio and temperature. We confirmed about harmlessness of melting slag through analysis of scanning electron microscope(SEM) and x-ray diffractometer(XRD).

• 한국결정성장학회지
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• 제9권2호
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• pp.173-179
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• 1999

본 연구에서는 비정질 규소 박막의 결정화를 촉진시키기 위하여 표면 활성화 처리의 영향을 관찰하였다. 표면 활성화 방법으로는 습식 연마법(Wet Blasting)과 Nd:YAG 레이저의 빔을 사용하였고, 700~$800^{\circ}C$에서 관상로 열처리를 행하여 고살 결정화에 미치는 영향을 보았다. 결정화 정도의 기준으로는 XRD 분석을 통해 얻은 (111) 피크강도를 이용하였으며, 결정의 품질을 분석하기 위해 Raman 분석을 행하였다. 결정화의 표면 형상에 대한 관찰은 주사전자 현미경(SEM)을 사용하였다. 본 실험 결과 표면 활성화 처리는 비정질 규소박막의 결정화를 촉진하고, 결정의 품질을 향상시키는 것으로 확인되었다. 습식 연마법(Wet Blasting)의 경루 2 Kgf/$\textrm{cm}^2$의 압력이 가장 효과적이었고, 레이저의 에너지는 100~200mJ/$\textrm{cm}^2$가 효과적이었다. 이것은 표면활성화처리를 통하여 비정질 실리콘 박막의 표면에 strain energy가 형성되어 결정화에 필요한 엔탈피에 영향을 미친 효과 때문으로 예상된다.

• Environmental Engineering Research
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• 제19권4호
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• pp.375-380
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• 2014

Macro fouling due to blue mussels (Mytilus edulis) has affected negatively on the operation efficiency and eventual system failure of offshore structures and coastal power stations. A certain range of chlorine (0.05, 0.1, 0.3, 0.5, 0.7 and 1.0 mg/L) was applied on the mussel larvae to identify the survival rate with respect to various exposure times under laboratory condition. The ciliary movement of the larvae was used to check their survival. The 1.0 mg/L of chlorine shows to 97% of larvae mortality whereas 0.7 mg/L of chlorine shows only 16% of larvae mortality. Minimum exposure times for 100% larvae mortality ranged from 300 to 20 min for increasing concentrations of chlorine (0.05~1.0 mg/L). It was found that 1 mg/L of chlorine was 4 times more efficient than 0.7 mg/L of that, and 15 times more than 0.05 mg/L of chlorine dose. Data collected and analyzed here will help plant operators to optimize chlorine dosage and its scheduling.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.64-64
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• 2010

This paper presents the results of changes of optical properties of front materials in crystalline PV modules. If PV modules on the outdoor, transmittance of front materials is reduced by solar light. That is UV, IR included Solar spectrum will have change the properties of glass. Therefore decrease in transmittance leads to loss of the PV modules output. All the PV modules showed the loss in Isc by 1~5% within few hors. To investigate the changes we are analyzed using spectrophotometer from raw glass to laminated glass.