• Composites Research
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• v.19 no.1
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• pp.29-35
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• 2006

The avoidance of enemy's radar detection is very important issue in the modem electronic weapon system. Researchers have studied to minimize reflected signals of radar. In this research, two types of radar absorbing structure (RAS), 'C'-type shell and 'U'-type shell, were fabricated using fiber-reinforced composite materials and their radar cross section (RCS) were evaluated. The absorption layer was composed of glass fiber reinforced epoxy and nano size carbon-black, and the reflection layer was fabricated with carbon fiber reinforced epoxy. During their manufacturing process, undesired thermal deformation (so called spring-back) was observed. In order to reduce spring-back, the bending angle of mold was controlled by a series of experiments. The spring-back of parts fabricated by using compensated mold was predicted by finite element analysis (ANSYS). The RCS of RAS shells were measured by compact range and predicted by physical optics method. The measured RCS data was well matched with the predicted data.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.11a
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• pp.155-158
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• 1998

This paper is calculated at electron swarm simulation by Back Prolongation of Boltzmann equation for range of E/N values from 0.1~200[Td], pressure P= 1.0[Torr], temperature T=300[ 。K], the electron swarm parameter(drift velocity, longitudinal . transverse diffusion coefficients, characteristic energy, etc) in He gas is used by electron collision cross section, particularly explicate the simulation technique, and consider electrical conduction characteristic of He gas.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2013.06a
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• pp.166-168
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• 2013

본 연구는 기존 필터의 Back-flushing에 의한 단점을 극복할 수 있는 Cross-flushing Type으로 설계하여 필터의 막힘을 순간적으로 재생할 수 있는 역세척 원리인 Cross flushing 방식으로 새롭게 고안하여 HYDAC 필터의 역세척이 가지는 단점을 근본적으로 보완한 새로운 형태의 Filter로서 필터의 막힘을 수직방향으로 강력한 와류세척에 의해 순간적으로 재생 시킬 수 있는 기능 가지고 있어 해수의 대용량 정밀여과가 가능하다.

• Steel and Composite Structures
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• v.33 no.1
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• pp.37-66
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• 2019

In cold-formed steel structures, such as trusses, wall frames and portal frames, the use of back-to-back built-up cold-formed stainless-steel lipped channels as compression members are becoming increasingly popular. The advantages of using stainless-steel as structural members are corrosion resistance and durability, compared with carbon steel. The AISI/ASCE Standard, SEI/ASCE-8-02 and AS/NZS do not include the design of stainless-steel built-up channels and very few experimental tests or finite element analyses have been reported in the literature for such back-to back cold-formed stainless-steel channels. Current guidance by the American Iron and Steel Institute (AISI) and the Australian and New Zealand (gAS/NZS) standards for built-up carbon steel sections only describe a modified slenderness approach, to consider the spacing of the intermediate fasteners. Thus, this paper presents a numerical investigation on the behavior of back-to-back cold-formed stainless-steel built-up lipped channels. Three different grades of stainless steel i.e., duplex EN1.4462, ferritic EN1.4003 and austenitic EN1.4404 have been considered. Effect of screw spacing on the axial strength of such built-up channels was investigated. As expected, most of the short and intermediate columns failed by either local-global or local-distortional buckling interactions, whereas the long columns, failed by global buckling. All three grades of stainless-steel stub columns failed by local buckling. A comprehensive parametric study was then carried out covering a wide range of slenderness and different cross-sectional geometries to assess the performance of the current design guidelines by AISI and AS/NZS. In total, 647 finite element models were analyzed. From the results of the parametric study, it was found that the AISI & AS/NZS are conservative by around 10 to 20% for cold-formed stainless-steel built-up lipped channels failed through overall buckling, irrespective of the stainless-steel grades. However, the AISI and AS/NZS can be un-conservative by around 6% for all three grades of stainless-steel built-up channels, which failed by local buckling.

• Journal of Preventive Medicine and Public Health
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• v.51 no.5
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• pp.227-233
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• 2018

Objectives: Chronic diseases, including back pain, result in significant patient morbidity and societal burden. Overall improvement in physical fitness is recommended for prevention and treatment. Walking is a convenient modality for achieving initial gains. Our objective was to determine whether neighbourhood walkability, acting as a surrogate measure of physical fitness, was associated with the presence of chronic disease. Methods: We conducted a cross-sectional study of prospectively collected data from a prior randomized cohort study of 227 patients referred for tertiary assessment of chronic back pain in Ottawa, ON, Canada. The Charlson Comorbidity Index (CCI) was calculated from patient-completed questionnaires and medical record review. Using patients' postal codes, neighbourhood walkability was determined using the Walk Score, which awards points based on the distance to the closest amenities, yielding a score from 0 to 100 (0-50: car-dependent; 50-100: walkable). Results: Based on the Walk Score, 134 patients lived in car-dependent neighborhoods and 93 lived in walkable neighborhoods. A multivariate logistic regression model, adjusted for age, gender, rural postal code, body mass index, smoking, median household income, percent employment, pain, and disability, demonstrated an adjusted odds ratio of 2.75 (95% confidence interval, 1.16 to 6.53) times higher prevalence for having a chronic disease for patients living in a car-dependent neighborhood. There was also a significant dose-related association (p=0.01; Mantel-Haenszel chi-square=6.4) between living in car-dependent neighbourhoods and more severe CCI scores. Conclusions: Our findings suggest that advocating for improved neighbourhood planning to permit greater walkability may help offset the burden of chronic disease.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.8A
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• pp.581-590
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• 2003

This paper proposes the routing path selection mechanism for source routing-based PtMP (Point-to-Multipoint) call in ATM switching system. Especially, it suggests PtMP routing path selection method that can share the maximum resource prior to the optimal path selection, guarantee the reduction of path calculation time and cycle prevention. The searching for the nearest branch point from destination node to make the maximum share of resource is the purpose of this algorithm. Therefore among neighbor nodes from destination node by back-tracking, this algorithm fixes the node crossing first the node on existing path having the same Call ID as branch node, constructs the optimal PtMP routing path. The optimal node to be selected by back-tracking is selected by the use of Dijkstra algorithm. That is to say, PtMP routing path selection performs the step of cross node selection among neighboring nodes by back-tracking and the step of optimal node selection(optimal path calculation) among neighboring nodes by back-tracking. This technique reduces the process of search of routing information table for path selection and path calculation, also solves the cycle prevention easily during path establishment.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.10a
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• pp.297-300
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• 2009

The roll forming process is often used to manufacture long, thin-walled products such as a pipe. The final cross-section is a comparatively simple open-channel, a closed tube section or a complex profile with several bends. In recent years, that process is often applied to the bumper beam in the automotive industries. In this study, a optimal Center Floor Cross Member manufacturing technology, model deign and proper roll-pass sequences can be suggested by forming number of roll-pass and bending angle, and also effects of the process parameters on the final shape formed by roll forming defects were evaluated.

• ETRI Journal
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• v.32 no.2
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• pp.312-318
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• 2010

A small reconfigurable patch antenna is proposed to achieve polarization diversity for digital multimedia broadcasting systems at 2.6 GHz. To obtain polarization diversity, a pair of on-slit PIN diodes is inserted in each diagonal of a cross-shaped patch. Thus, four PIN-diodes on these slits are utilized to change the connection of the slits and thus achieve polarization. Bias circuits for the diodes are allocated in the cutting corner of the cross-shaped patch to minimize the antenna size. The antenna produces left-hand circular polarization, right-hand circular polarization, or linear polarization, depending on the PIN-diode status. Analysis of circular polarization operation is explicated. Measurements show a gain of about 1.5 dB, a cross polarization of about -20 dB, and an axial ratio of about 2.5 dB.

• The Research Journal of the Costume Culture
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• v.1 no.2
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• pp.145-157
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• 1993

This study aimes to investigate the garment ease of pe-school children's clothing in accordance with arm movement. The experiment was done with 4 per-school children fro mage 3 to age 5, and 3 types of experimental clothes were made ; sleeveless, half sleeve, and long sleeve. The waist pattern and the sleeve pattern of each experimental clothes has no garment ease. And experimental clothes were examined to obtain the necessary ease of armcye line and waist lien by cross-cut method. The results of investigation can be summarized as follows ; 1. The resulting movement ranges of experimental clothes with no garment ease were 131.5°(sleeveless), 71.75°(half sleeve), and 62.25°(long sleeve). 2. The size order of cross-cut opening of waist lien movement were (side>front>back), and (half sleeve>long sleeve>sleeveless). 3. When the base point of measurement was set to armpit point by arm the latitudinal length of cross-cut opening of armcye line by arm movement was (anterior armpit part > posterior armpit part), and longitudinal length of cross-cut opening was (upper part>lower part).

• Physical Therapy Korea
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• v.25 no.1
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• pp.53-61
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• 2018

Background: The process of language translation, adaptation, and cross-cultural validation of tools for use in multiple countries requires the adoption of well-established, comprehensive, and rigorous methodological approaches. Back translation, which is the most recommended method, permits the detection of errors in the translation and the identification of words or phrases that cannot be accurately or literally translated. Objects: The aim of this study was to verify the content validity of a Korean version of a Balance Evaluation Systems test (BESTest) by using a back-translation method. Methods: This research was conducted in six steps: 1) translation of the BESTest into Korean, 2) evaluation of the translation conformity of Korean-translated BESTest, 3) evaluation of the degree of translation comprehension, 4) back translation of Korean BESTest, 5) evaluation of the technical and conceptual equivalence, and 6) completion of the Korean version of BESTest by the translation verification committee. Results: In this study, Korean version of the BESTest achieved a rating of more than 3 (moderate) for translation comprehension, and technical equivalence and conceptual equivalence of back translation were evaluated as 3 (moderate) or more. Conclusion: The Korean version of the BESTest has proven content validity and is an appropriate tool to measure balance function.