• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.11
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• pp.843-850
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• 2020

The purpose of this study is to evaluate the structural risk and weakness of a railway tank car through nonlinear collision analysis according to overseas collision safety standards. The goal is to propose a crash safety design guideline for railway tank cars for transporting dangerous goods in Korea. We analyzed the buffer impact test procedure of railway freight cars prescribed in EN 12663-2 and the tank puncture test criteria prescribed in 49CFR179. A nonlinear finite element model according to each standard was modeled using LS-DYNA, a commercial finite element analysis solver. As a result of the buffing impact test simulation, it was predicted that plastic deformation would not occur at a collision speed of 6 km/h or less. However, plastic deformation was detected at the rear of the center sill and at the tank center supporting the structure at a collision speed of 8 km/h or more. As a result of a head-on test simulation of tank puncture, the outer tank shell was destroyed at the corner of the tank head when 4% of the kinetic energy of the impacter was absorbed. The tank shell was destroyed in the area of contact with the impacter in the test mode analysis of tank shell puncture when the kinetic energy of the moving vehicle was reduced by 30%. Therefore, the simulation results of the puncture test show that fracture at the tank shell and leakage of the internal material is expected. Consequently, protection and structural design reinforcement are required on railway tank cars in Korea.

• Journal of KIISE:Computer Systems and Theory
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• v.31 no.3_4
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• pp.224-238
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• 2004

Multi-modality image registration is a widely used image processing technique to obtain composite information from two different kinds of image sources. This study proposes an image registration method based on moment information and surface distance, which improves the previous surface-based registration method. The proposed method ensures stable registration results with low registration error without being subject to the initial position and direction of the object. In the preprocessing step, the surface points of the object are extracted, and then moment information is computed based on the surface points. Moment information is matched prior to fine registration based on the surface distance, in order to ensure stable registration results even when the initial positions and directions of the objects are very different. Moreover, surface comer sampling algorithm has been used in extracting representative surface points of the image to overcome the limits of the existed random sampling or systematic sampling methods. The proposed method has been applied to brain MRI(Magnetic Resonance Imaging) and PET(Positron Emission Tomography), and its accuracy and stability were verified through registration error ratio and visual inspection of the 2D/3D registration result images.

• Journal of Conservation Science
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• v.25 no.4
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• pp.399-409
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• 2009

Outdoor iron artefacts are easily corroded by affection of environmental pollutants directly. Especially they need to be removed $Cl^-$ ions, but outdoor iron artefacts are excluded for desalination owing to their special features. Therefore this study contains the conservation processes of an iron stele of the Joseon Dynasty as the sample as well as desalination experiments that were carried out the desalting method using spill pads and the immersion desalting method together in order to compare. Desalting methods were compared by analyses such as an optical and metallurgical microscope, SEM-EDS, pH meter, Ion Chromatography and X-ray diffraction. As a result of the analysis, the optical and metallurgical microscopy show that the corrosion products are constituted by the layers and the metallurgical microstructure is a white cast iron. The SEM-EDS results of corrosion products detected mainly Fe, O, and especially Cl upto 2.48wt%. The results of pH and anion analysis for the washing solution, the desalting method using spill pads shows the similar effect to the immersion desalting method. As a result of XRD analysis before and after desalting corrosion products, goethite, magnetite, lepidocrocite and akaganeite are detected before desalting, but akaganeite is not detected after desalting at the desalting methode using spill pads, which indicates to have an effect on desalination. Therefore the results show that the desalting method using spill pads has an effect on desalination similar to the immersing desalting method.

• Journal of Navigation and Port Research
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• v.30 no.6 s.112
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• pp.439-446
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• 2006

In ship structures many of the structural plates have cutouts, for example, at inner bottom structure, girder, upper deck hatch, floor and dia-frame etc. In the case where a plate has a cutout it experiences reduced buckling and ultimate strength and at the same time the in-plane stress under compressive load produced by hull girder bending will be redistributed In general, actual ship structure adopted reinforcement of stiffener around the cutout in order to preventing from buckling so it need to examine a buckling and ultimate strength behaviour considering a cutout because In many ship yards used class rule for calculating buckling strength but it is difficult to evaluate perforate stiffened plate with random size. In the present paper, we investigated several kinds of perforated stiffened model from actual ship and then was performed finite element series analysis varying the cutout ratio, web height, thickness and type of cross-section using commercial FEA program(ANSYS) under compressive load.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2018.10a
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• pp.54-54
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• 2018

숨은물뱅듸 산림유전자원 보호구역은 해발 950 m 이상 지역의 습지로서 오름으로 둘러싸인 넓은 웅덩이 형태로 환경부 멸종위기 2급 야생식물인 자주땅귀개를 비롯한 다양한 습지 식물과 이를 둘러싸고 있는 산림지역을 포함하여 산림청에서는 산림유전자원 보호구역으로 지정 관리되고 있다. 본 조사는 숨은물뱅듸 산림유전자원 보호구역을 대상으로 식물상을 조사하여 식물종 다양성을 보존하기 위한 기초자료를 만들기 위해 실시하였다. 본 연구는 2018년 7월 24일부터 8월 28일까지 총 4회에 걸쳐 현장조사를 통하여 표본을 채집하고 기록하여 정리하였다. 그 결과, 숨은물뱅듸에 자생중인 식물은 양치식물 8과 11속 17종 17분류군, 나자식물 2과 2속 2종 2분류군, 피자식물 56과 121속 167종 5변종 1품종 173분류군 총66과 134속 186종 5변종 1품종의 총 192분류군이 조사되었다. 이 중 환경부 멸종위기야생식물은 자주땅귀개 1종이 확인되었고, 제주특산식물 6분류군, 한국특산식물 2분류군이 확인되었다. 식물구계학적특정식물은 총37분류군이며 V등급 5분류군, IV등급 5분류군, III등급 12분류군, II등급 5분류군, I 등급 10분류군이 확인되었다. 한국의 적색목록 식물은 위기(EN) 1분류군, 취약(VU) 1분류군, 준위협(NT) 1분류군, 관심대상(LC) 6분류군, 미평가(NE) 3분류군으로 나타났다. 조사된 식물들 대상으로 생활형을 분석해보면, 휴면형은 Ch 47분류군으로 가장 많이 나타났고, G(30분류군), MM(24분류군), HH(23분류군) 순으로 나타났다. 번식형은 R5가 101분류군, 산포기관형은 D4가 84분류군, 생육형은 e가 89분류군으로 가장 많이 나타났다. 반면, 외래식물 1분류군이 출현한 것으로 보아 숨은물뱅되는 아직까지 보전이 잘 되어 있고, 식물종다양성이 우수하며 식물학적으로 가치가 매우 높은 것으로 판단되었다.

• Journal of dental hygiene science
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• v.14 no.2
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• pp.207-213
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• 2014

How to eliminate health disparity to ensure health equity is one of major issues that are handled across the world. The purpose of this study was to examine any possible differences in self-rated oral health state according to socioeconomic status and the relationship between the two based on the data of the 5th National Health & Nutrition Examination Survey of 2010~2012. As for differences in self-rated oral health state according to sociodemographic characteristics, the women considered themselves to be in poorer oral health than the men. The older respondents found themselves to be in poorer oral health, and there was a tendency that the respondents who were less educated and whose household income was smaller rated their own health as worse. When a logistic regression analysis was made to determine influential factors for self-rated oral health status, the women perceived they were in better oral health than the men did, and the better-educated respondents were more likely to consider themselves healthier. Concerning disparities in self-rated health state according to income level, there were broader differences in that regard according to an increase of income. The findings of the study illustrated that there was oral health inequity according to social stratum. It's required to make a nationwide effort to promote national oral health, and appropriate support should especially be provided for disadvantaged people at the same time in order to get rid of the gap in oral health among different social classes, as there is a yawning gap between them and the other classes.

• Journal of the korean academy of Pediatric Dentistry
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• v.43 no.3
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• pp.264-274
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• 2016

It is a trend that carbonated drink intake among adolescents is increasing, which makes young people more vulnerable to dental erosion. However, in Korea, public knowledge about dental erosion is very insufficient. The aim of this study was to investigate the prevalence of dental erosion and to assess its risk indicators among 13-15 years old students in Yangsan, Korea. A total of 1,371 adolescents were examined by one calibrated clinician. Dental erosion was assessed by using the Visual Erosion Dental Examination system. Correlation between their dietary habit, oral hygiene and dental erosion was assessed. The data showed that 676 (49.3%) adolescents had dental erosion. The prevalence of dental erosion was significantly higher in females than in males. The prevalence of tooth erosion in mandible is higher than in maxilla. Dental erosion was generalized to develop mostly on anterior teeth, especially lateral incisor, however, the severity score was highest in canines. Following questionnaire analysis, dental erosion was significantly associated with milk and flavored milk. No other associations were detected. The prevalence of dental erosion in this study is higher than those of previous reports. On the contrary to previously reported studies, the prevalence of dental erosion in females is higher than in males.

• The Journal of the Korea Contents Association
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• v.12 no.1
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• pp.48-58
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• 2012

With the development of sensing devices and wireless communication technologies, wireless sensor networks are composed of a large number of sensor nodes that are equipped with limited computing performance and restricted communication capabilities. Besides, the sensor nodes are deployed in hostile or unattended environments. Therefore, the wireless sensor networks are vulnerable to security. In particular, the fatal damage may be occurred when data are exposed in real world applications. Therefore, it is important for design requirements to be made so that wireless sensor networks provide the strong security. However, because the conventional security schemes in wired networks did not consider the limited performance of the sensor node, they are so hard to be applied to wireless sensor networks. In this paper, we propose a secure multipath transmission scheme based on one-way hash functions in wireless sensor networks considering the limited performance of the wireless sensor nodes. The proposed scheme converts a sensor reading based on one of one-way hash functions MD5 in order to make it harder to be cracked and snooped. And then, our scheme splits the converted data and transfers the split data to the base station using multi-path routing. The experimental results show that our proposed scheme consumes the energy of just about 6% over the existing security scheme.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.12
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• pp.150-156
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• 2017

This study examined the stress recovery length due to the local damage of a 7-wire strand, which is applied widely to PSC (Post Tensioned Concrete) bridges and cable-stayed bridges. The 7-wire strand is a multiple stranded steel of PC prestressing strand. Owing to the nature of the material, it is damaged continuously after completion with corrosion being the main cause of damage. On the other hand, due to its structural characteristics, it is difficult to grasp the degree of damage inside the cable and the pattern of stress variation. In the case of cables applied to bridges, the parts that are susceptible to corrosion are generated depending on the water supply and installation shape, which may cause local damage. This study analyzed the tendency of performance degradation and stress recovery length according to local damage of a 7-wire strand, which is applied mainly to bridge post-tensioning or stay cables. This study developed a computer-based simulation model that was validated with experimental results. The model developed in this study can be used to evaluate the safety level and estimate the remaining life span of P SC bridges or cable-stayed bridges.

• Journal of Food Hygiene and Safety
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• v.24 no.1
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• pp.86-93
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• 2009

This study was conducted to determine microbiological assessment on edible ices, which is one of mandatory items for HACCP application, and to provide basic scientific data for the improvement of HACCP system. In HACCP applied edible ice companies, the contamination levels of total counts, yeast and mold, and coliform from raw materials, mixed samples before sterilization, mixed samples after sterilization, and final products of edible ices were lower than those of non-HACCP applied edible ice companies. Foodborne pathogens, such as L. monocytogenes, Salmonella spp., B. cereus, B. aureus, Y. enterocolitica were not detected in all samples of edible ices from HACCP applied edible ice companies, but S. aureus was isolated1 from 1 raw material, 1 mixed samples before sterilization and 1 final product of edible ices from non-HACCP applied edible ice companies, respectively.