• Proceedings of the Korea Contents Association Conference
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• 2013.05a
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• pp.231-232
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• 2013

이 연구는 경남지역 소재 무도수련장에 다니고 있는 수련생들을 모집단으로 무도수련장 지도자의 운동지원과 재등록의사의 관계를 규명하는데 목적이 있다. 이 연구를 위해 총 220명의 무도수련장의 수련생들을 유의표집하였다. 이 연구는 SPSSWIN 18.0과 AMOS 18.0 프로그램을 활용하여 통계처리를 실시하였다. 자료처리 방법은 신뢰도분석(reliability analysis)과 공변량구조분석(structural equation modeling) 등의 통계기법이 활용되었다. 결론은 다음과 같다. 무도수련장 지도자의 정보적 지원, 물질적 지원, 사교적 지원 등이 재등록의사에 중요한 영향을 미친다.

• Journal of Korean Society of Steel Construction
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• v.19 no.1
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• pp.79-86
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• 2007

The corrosion durability of steel bridge coatings, such as organic and metallic coatings, is often evaluated by field exposure tests, but such tests take from several years to decades to complete. As a potential method for fast corrosion testing, accelerated exposure tests were considered in this study. The S6-cycle accelerated exposure test, specified in the Japanese Industrial Standards (JIS K5621), was carried out on uncoated structural steels for 30, 60, 90, 120 and 150 days, and the resultant weight loss was determined. The weight loss was compared with that obtained from previous field exposure tests, and acceleration factors of the S6-cycle test to field exposure test sites were determined. The application of the S6-cycle accelerated exposure tests to field environments was presented based on the acceleration factor and the amount of flying salt.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.4
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• pp.2391-2400
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• 2015

Weather proof steels are used for steel bridges due to its high corrosion resistance under atmospheric conditions. However, instead of forming stabilized rust layers, general rust occurs on weather proof steels under high humidity condition close to seawater or shady places. In Japan, therefore, they perform rust stabilization treatment instead of unpainted treatment due to severe atmospheric conditions. However, most of domestic weather proof steels were constructed unpainted in the form of closed box-girder, which makes the periodical repetition of dry and wet hard to occur. For the steel bridges constructed on the Han river, the evaporation of water, dew condensation due to temperature change, and stagnant water due to rain affect harmfully on the formation of passive film on weather proof steels. Thus, in this research, in order to analyze corrosion properties inside the closed box-girder for the unpainted weather proof steel bridge in the waterworks safety zone, multiple ways of analysis such as observation with eyes, cellophane-tape test, steel thickness measurement, surface corrosion potential measurement, electron microscope analysis, and X-ray diffraction analysis of the rust were performed. As a result, unstable rust layer was observed inside the closed box-girder, and severe corrosion was observed on the top and bottom of the flanges due to the effects of stagnant water caused by rain, dew condensation, and de-icing materials.

• Journal of Korean Society of Steel Construction
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• v.16 no.4 s.71
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• pp.415-423
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• 2004

To investigate the long-term corrosion resistance of an uncoated weathering steel, an important outdoor constructional steel material, skyward surfaces of the weathering steel and a control steel initially exposed to rural and industrial atmospheres for 9 years were electrochemically tested in neutral artificial rain in terms of electrochemical potentials, impedances, and anodic potentiodynamic polarization curves. Their results were then discussed. A quite passive and stable rust layer to the artificial rain was well formed on the skyward surface of the weathering steel exposed to the industrial and rural atmospheres, and its corrosion rate in the artificial rain was measured to be about a low $3{{\mu}m}/y$. Continuous immersion of all the weathered surfaces in the artificial rain revealed the gradual degradation of the weathered corrosion layers on the steel, resulting in a cathodically controlled corrosion of the substrate steel by the electrochemical measurements. Alloy components of the weathering steel were found to retard the degradation of the weathered corrosion layers on the steel in the artificial rain. For better corrosion evaluation of the weathering steel, more electrochemical measurements of surfaces that have been exposed for more than 9 years to more closely simulated atmospheric waters are needed. These measurements are almost non-destructive and can provide online and in situ information on the corrosion rate, the development of corrosion and the conditions of rust layers on any interested surface and at any exposure time of the steel, so they can be effectively applicable to the corrosion evaluation of steel structures such as bridges, towers, and architectures by forming an electrochemical cell on an interested structural surface and by using a portable electrochemical instrument.

• Proceedings of the KAIS Fall Conference
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• 2008.11a
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• pp.371-374
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• 2008

본 연구에서는 무도장 Weldless 평가금형을 이용하여 사출성형 공정조건에 따라 다양한 형태의 변형이 생기는 성형품을 CAE를 통하여 ABS와 PC의 사출조건 냉각시간, 보압의 유/무 등에 따라서 발생되는 문제점과 변형량을 예측하고, 실제 사출성형 되어진 성형품과의 비교 분석을 통하여 사출성형 CAE 해석을 실제 사출성형 공정에서의 활용방안에 대하여 검토하였다.

• Journal of Korean Society of Steel Construction
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• v.29 no.3
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• pp.193-204
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• 2017

Fatigue strength of temporary steels and painted structural steels corroded under outdoor atmospheric environments is not clear. In this study, fatigue tests were carried out on steel plates which were cut off from 7-year-old temporary structural member under subway construction environment and from 75-year-old Yeongdo bridge member under marine atmospheric environment. After removing corrosion production on the steel surface, 3-dimensional surface geometry of the corroded steel was measured at intervals of $1.0{\times}1.0mm$, and corrosion characteristics such as minimum, maximum and mean values of residual thicknesses were calculated. From the fatigue test and FEM analysis results, the relationship between corrosion characteristics and fatigue behavior was presented, and change in fatigue strength of the unpainted and painted steels corroded in outdoor environments was also presented.

• Korean Chemical Engineering Research
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• v.60 no.2
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• pp.295-299
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• 2022

In this paper, paint-free metallic plastic material, polypropylene (PP) and acrylonitrile styrene acrylate (ASA) materials were investigated on the applications for bumper skid plate and outside mirror housing parts. In order to maximize metallic effect, type, size and content of aluminum pigment were optimized based on flop index. Hybrid aluminum pigments with different aspect ratios were used to conceal weld lines. By controlling the fluidity of the material, the flow mark problem, generated on the surface of the part, was resolved. We also investigated the surface defects of flow and weld lines by using the developed modeling and simulation.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.737-740
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• 2000

Injection molded plastic parts have many appearance imperfections: weld line sink mark flow mark, gloss, shading, scratching, etc. Because these appearance faults have not accepted esthetically, so pastic parts are produced through painting or texturing. The purpose of this paper is to develop a paintless molded part of TV Mask Front, using numerical simulations and experiments. In order to minimize problems of injection, this study carried out computer aided injection mold filling simulations using MF/FLOW. Based on these numerical results we developed FR(Flame Retardant) HIPS and estabilished guidelines of part design, mold design, and processing conditions. We took effects of cost savings, inprovement of productivity, and utilization of recycling by eliminated painting process.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.1
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• pp.13-20
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• 2008

The purpose of this study is to investigate the effect of acid fog on the rust formation behavior of weathering steel (SMA50) which is used in un-coated bridges. Weathering steel didn't form the passive film under the environment of acid fog(pH5,6), whereas the environment of distilled water formed the protective oxide film. Therefore, the construction of weathering steel under the environment extremely exposed to SOx and NOx which are the main compositions of acid fog is not adequate. Fatigue limits of weathering steel under acid fog environment are remarkably decreased as compared with environment of distilled water. The corrosive constituents in acid fog has piled up the corrosion products on specimen surface and generated the corrosion pits. Because of the high stress concentration arising at this corrosion pit, relatively low fatigue limits were obtained for acid fog specimens.

• Design & Manufacturing
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• v.10 no.1
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• pp.7-11
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• 2016

Sinks occurring in the rib portion of the testing product for the unpainteds are fatal defects at surface quality. In this study, we carried out moldflow analyses for several factors that affect the sinks. The result tells us large important effective factors on sinks by analyzing sink marks estimate. We expect practical use as reference for performing analysis or manufacturing products with rib designs and injection moldings which minimize sink-marks surrounded ribs.