• 한국농공학회논문집
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• 제50권4호
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• pp.17-24
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• 2008

Exposure risk assessment of pesticide molinate using the RICEWQ model in a rice paddy plot was performed to observe the effects of various water and pesticide management scenarios. Several scenarios were developed to represent the specific water and pesticide management practices of rice cultivation in Korea. The results of the scenario analysis using the RICEWQ model simulation from the previous studies were analysed. The molinate risk for aquatic organisms is evaluated by the ratio of the predicted environmental concentration(PEC) and the predicted no-effect concentration(PNEC). The results showed that the no-effect periods for aquatic organisms for the deep, shallow and very shallow irrigation conditions were 33.3, 28.9 and 25.6 DATs for the lable rate application and 36.4, 33.7 and 30.8 DATs for the double lable rate application, respectively. The higher application rate showed greater exposure risk to the aquatic organisms. Based on this study, the withholding period of molinate practiced in Korea, that is 3 to 4 DATs, must be much longer. The results of this study can be used for the non-point source pollution control and environmental policy making regarding pesticides.

• 한국광학회지
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• 제15권5호
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• pp.405-408
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• 2004

나뉜 렌즈를 사용하는 스펙클 전단 간섭계로 전단링(shear)에 따라 변형을 가하지 않은 상태에서 물체에 대한 동일한 두 장의 스펙클그램 쌍들을 제작하여, 이중 스펙클 기법을 사용함으로서 전단량에 따라 이 전단간섭계의 측정한계를 구하였다. 이 측정한계는 기존의 방법으로 얻어지는 값과 잘 일치함을 알 수 있었다.

• Imaging Science in Dentistry
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• 제31권4호
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• pp.209-214
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• 2001

Purpose: To investigate the ability of double TMJ view by multifunctional panorama to view the bony components and the space of the temporomandibular joint. Materials and Methods: Ten dry skulls fitted with resin shims over the articular surface of the condyle were used to reproduce the temporomandibular joint space. Fine metal wires were attached to the three portions of contours of the condylar head and the articular eminence. With 10 dry skulls and 20 cases having TMJ dysfunction, double TMJ views by multifunctional panorama (Planmeca 2002 Proline CC) and transcranial views were taken, analyzed from the anatomical view point, and compared statistically in view of the widths of the posterior joint space and the condylar head. Results: In double TMJ view, the supero-anterior part of the condyle represented the lateral 1/3, the most superior part represented center portion, and the posterior part medial l/3 of the condyle. In maximum mouth opening, no other structures were superimposed with the condyle in double TMJ view. In double TMJ view, petrous bone was moderately superimposed with the superior part of the condyle and the posterior increment of angle exposure made wider the images of the articular eminence and the condyle. The tendency of reduction in the posterior joint space appeared in the side of TMJ dysfunction compared with the normal side. The posterior joint spaces in double TMJ view were statistically wider (p<0.05) than those in transcranial view. The correlation coefficient was 0.5179 between the widths of the posterior joint spaces in two radiographic views. Conclusions: Double TMJ view can be substituted for transcranial view in evaluating the TMJ dysfunction.

• Journal of electromagnetic engineering and science
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• 제15권3호
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• pp.134-141
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• 2015

The effect of a 60 Hz time-varying electric field was studied using a facing-electrode device (FED) and a coplanar-electrode device (CED) for further investigation of the genotoxicity of 60 Hz time-varying magnetic field (MF) from preceding research. Neither a single 30-minute exposure to the CED or to the FED had any obvious biological effects such as DNA double strand break (DSB) and apoptosis in cancerous SCC25, and HeLa cells, normal primary fibroblast IMR90 cells, while exposures of 60 Hz time-varying MF led to DNA damage with induced electric fields much smaller than those used in this experiment. Nor did repetitive exposures of three days or a continuous exposure of up to 144 hours with the CED induce any DNA damage or apoptosis in either HeLa or IMR90 cells. These results imply that the solitary electric field produced by time-varying MF is not a major cause of DSBs or apoptosis in cancer or normal cells.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2002년도 Proceedings
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• pp.436-438
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• 2002

As the use of virtual simulation expands, digitally reconstructed radiographs (DRRs), which mimic conventional simulation films, play an increasingly important role as reference images in the verification of treatment fields. The purpose of our study is to develop an algorithm for computation of digitally reconstructed radiographs based on Monte Carlo simulation that take into account almost all possible physical processes by which photons interact with matter. The Monte Carlo simulation based DRRs have the following features. 1) Account has been taken of almost all possible physical processes of interaction of photons with matter, including a detector (film) response. In principle, this is equivalent to X-ray radiography. 2) Arbitrary photon energies (from diagnostic to therapeutic) can be used to produce DRRs. One can even use electrons as the source. 3) It is easy to produce a double exposure, which mimics the double exposure portal image and may have superior visual appeal for treatment field verification, with weighting within the treatment field.

• 환경위생공학
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• 제15권4호
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• pp.134-141
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• 2000

The person' spending time in underground s[aces within indoor environment show a tendency to increase every year, but in Korea, levels and sources of pollutant in underground spaces have not been well-characterized. Therefore, as part or a larger indoor environmental study, conducted at subway station in Seoul, nitrogen dioxide was measured using passive samplers in 16 subway stations, 2 tunnels and 70 workers of subway station. The mean concentrations of nitrogen dioxide in subway stations were $27.87{\pm}7.15$ ppb at station office, $35.76{\pm}8.35$ ppb at platform, $52.60{\pm}13.04$ ppb at outdoor, respectively, and the Indoor/Outdoor ratio were 0.49~0.93. The mean concentrations of nitrogen dioxide in tunnels were $44.91{\pm}4.67$ ppb in Chunggye-Nowon tunnel with a single track, $42.55{\pm}3.33$ ppb in Mokkol-Taenung tunnel with double track, respectively, and as a result of t-test, a single track levels were higher than double track levels(p<0.05). The mean personal exposure of the subject of station workers was $29.40{\pm}9.75$ ppb.

• Restorative Dentistry and Endodontics
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• 제22권1호
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• pp.220-227
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• 1997

The purpose of our study is to evaluate the ability of nickel-titanium(NiTi) files in maintaining the original curvature of a curved root canal during canal preparation. Curved canals on translucent resin blocks were prepared with NiTi and stainless steel files, and they were placed at the platform which can reproduce the same position. The unprepared and prepared canal forms were accurately compared by double exposure technique of photography. By finite element methods we also analyzed stress distributions of NiTi and stainless steel files in a curved canal. The results were as follows : 1. NiTi files were excellent in maintaining the original curvature of a curved canal than stainless steel files after canal preparation. 2. The results of canal preparation with these files were well verified by the analysis of stress distributions using finite element methods.

• 한국HCI학회논문지
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• 제9권1호
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• pp.1-9
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• 2014

최근 스마트폰 사용 등으로 소셜 네트워크 서비스(SNS)에 대한 접근이 용이해졌으며 사용자의 수 또한 폭발적으로 증가 하였다. 그 중 많은 사용자를 보유하고 있는 Facebook은 소극적인 개인정보 보호정책으로 인해 다양한 사회적 문제를 야기하고 있으나, 개인정보 보호정책은 큰 변화를 보이지 않고 있고 사용자 수는 지속적으로 증가하는 추세이다. 본 연구는 소극적인 개인정보 보호정책에도 불구하고 사용자가 늘어나는 현상을 Facebook 사용자의 양면성을 통해 조명하였다. 즉, Facebook 사용자들은 자신의 개인정보와 다양한 활동들이 손쉽게 노출되는 것에 대해 불안감을 느끼지만 또한 반대로 다른 사용자들의 개인정보와 활동에 대해서는 알고 싶어 하며 그것을 열람하는데 큰 흥미를 느끼기 때문에 Facebook을 이용한다는 것이다. 이를 검증하기 위해 설문지와 반대시나리오 검증을 통해 사용자들의 양면적 욕구 (자신의 정보보호, 타인의 활동 열람)를 파악하였으며, 적절한 수준의 개인정보와 활동공개는 Facebook이 지속적인 인기를 얻는 중요한 요인이 될 수 있음을 확인하였다. 많은 연구들이 자아의 표출이라는 측면에서의 SNS를 연구하였다. 본 연구는 보여주기와 감추기의 적절한 수위조절이 Facebook과 같은 SNS의 중요한 요소임을 보여준다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2022년도 봄 학술논문 발표대회
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• pp.93-94
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• 2022

The presence of chloride (Cl-) ions in environments causes localized corrosion resulting decrease the durability of the structures. In this study, 5% Mg containing Al alloys (Al-5Mg) wire used vis-à-vis compared its corrosion resistance with pure Al in 3.5wt.% NaCl solution with exposure periods. Initially both wires exhibited identical open circuit potential (OCP) attributed to the presence of native oxide film on the surface but with the exposure periods it shifted towards active direction owing to the dissolution of oxide film. The pure Al continuously shifted the OCP towards active direction while Al-5Mg shows stabilization of OCP after 8 days of exposure. The OCP of Al-5Mg is slightly higher compared to pure Al wire owing to the activeness of Mg. The total impedance of the Al-5Mg alloy is almost three times greater than pure Al with exposure periods in 3.5 wt.% NaCl solution. It might be formation of Al-Mg LDH (layered double hydroxide) thin film onto the surface.

• Elastomers and Composites
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• 제51권1호
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• pp.1-9
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• 2016

Characterization of the UV oxidation for raw natural rubber (NR) was investigated in controlled conditions through image and FT-IR analysis. The UV oxidation was performed on a thin film of natural rubber coated on a KBr window at 254 nm and room temperature to exclude the thermal oxidation. Before or after exposure to UV light, image of the NR thin film was observed at a right or tilted angle. FT-IR absorption spectra were measured in transmission mode with the UV irradiation time. The UV oxidation of NR was examined by the changes of absorption peaks at 3425, 1717, 1084, 1477, 1377, and $833cm^{-1}$ which were assigned to hydroxyl group (-OH), carbonyl group (-C=O), carbon-oxygen bond (-C-O), methylene group $(-CH_2-)$, methyl group $(-CH_3)$, and cis-methine group $(cis-CCH_3=CH-)$, respectively. During the initial exposure period, the results indicated that the appearance of carbonyl group was directly related to the reduction of cis-methine group containing carbon-carbon double bond (-C=C-). Most of aldehydes or ketones from carbon-carbon double bonds were formed very fast by chain scission. A lot of long wide cracks with one orientation at regular intervals which resulted in consecutive chain scission were observed by image analysis. During all exposure periods, on the other hand, it was considered that the continuous increment of hydroxyl and carbonyl group was closely related to the decrement of methylene and methyl group in the allylic position. Therefore, two possible mechanisms for the UV oxidation of NR were suggested.