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        검색결과 21

        1.
        2019.10 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        In order to analyze the effect of hot asymmetric rolling on the microstructure and texture of aluminum alloy and to investigate the effect of the texture on the formability and plastic anisotropy of aluminum alloy, aluminum 6061 alloy is asymmetrically rolled at room temperature, 200 ℃, 350 ℃, and 500 ℃, and the results are compared with symmetrically rolled results. In the case of asymmetric rolling, the equivalent strain (εeq) is greatest in the upper roll part where the rotational speed of the roll is high and increases with increasing rolling temperature. The increase rate of the mean misorientation angle with increasing temperature is larger than that during symmetrical rolling, and dynamic recrystallization occurs the most when asymmetrical rolling is performed at 500 ℃. In the case of hot symmetric rolling, the {001}<110> rotated cube orientation mainly develops, but in the case of hot asymmetric rolling, the {111}<110> orientation develops along with the {001}<100> cube orientation. The hot asymmetric rolling improves the formability (r) of the aluminum 6061 alloy to 0.9 and reduces the plastic anisotropy (Δr) to near zero due to the {111}<110> shear orientation that develops by asymmetric rolling.
        4,000원
        3.
        2015.12 구독 인증기관 무료, 개인회원 유료
        The spatial resolution of 3-Dimensional numerical model has a very important influence on the model result. The land-use and orographic effect is also influenced by the spatial resolution of the model. A large errors in model performance are produced depending on the terrain complexity. In this study we performed Air Quality Forecast model (AQF) simulation and analyzed the change in the ozone concentration depending on spatial resolution at small and medium-sized mixed areas with urban and rural area types. As the result, improving the spatial resolution improved the simulation of the downward trend of ozone at night. This was mainly due to improvement of local concentration contaminants at fragmented grid. In the case of wind speed, the model with high-resolution shows better agreement with observation at night.
        4,000원
        4.
        2015.06 구독 인증기관 무료, 개인회원 유료
        Ozone precursor emissions and meteorological conditions have large impact on ozone concentrations. In this research, Data referring to an approximately 14-year period (1996~ 2009) are analyzed in order to estimate the trend of the daily maximum hourly value of ozone concentration at national capital region. A Kolmogorov-Zurbenko (KZ) filter is applied to remove the short-term component from the raw time series of ozone and meteorological variables. Meteorological effects are removed from filtered ozone series using multiple linear regression based on meteorological variables. The results show significant differences in local ozone concentrations. Especially, Ulsan area shows continuously increasing trend in ozone concentrations.
        4,000원
        5.
        2013.06 구독 인증기관 무료, 개인회원 유료
        In this research, we analyzed the relation between agricultural productivity and climatological data in highlands of Pyeongchang, Gangwon-do. Highland agricultural productivity index (HAPI) was developed using existing agriculture climate index and observation data set. Climate modeling system was constructed for simulations over complex mountainous terrain. Additionally a relation between the productivity and spatial HAPI was studied. The result shows a close corelation between temperature, important for vegetable growth, and vegetable productivity. Climate simulation was performed and the computed 10 years data were compared with data from regional meteorological office in Daegwallyeong. Using the result the HAPI was estimated for each grid (1 km) of the model domain.
        4,000원
        6.
        2010.06 구독 인증기관 무료, 개인회원 유료
        This study was performed to assess the level of ozone risk for wheat and potato in the central region of the Korean Peninsula by using ozone indices, the ozone-concentration based index (AOT40). The AOT40 indices were calculated for wheat and potato, respectively, at 25 sites in the central region of the Korean Peninsula during a period of three months from April 1 to June 30, 2006. The results for both indices, AOT40, showed that agricultural crops could be seriously damaged by ozone in the central region of the Korean Peninsula. In the result of AOT40, ozone may affect about 60% of the sites for wheat and 20% of the 25 sites for potato.
        4,000원
        7.
        2009.12 구독 인증기관 무료, 개인회원 유료
        In this research were used observation meteorological data and meteorological model to understand an influence of rising ocean temperature on climate change in Korean Peninsula. In the case of meteorological data, were examined inland ocean temperatures as mean annual temperature change during 28 years period (1980-2006) on six shore sites and four inland sites. Also, it have been used MM5 meteorological model to study climate change due to rising ocean temperature and simulate increasing ocean temperature of Korean Peninsula by 2oC. Results shows that the temperature on the shore sites were increasing two times more than temperature on the inland sites. The meteorological model shows similar result and the highest temperature appears on the south shore sites.
        4,000원
        8.
        2009.04 구독 인증기관 무료, 개인회원 유료
        Recently Environmental issues is Product development for ease of disassembly and recycling requires methodical toolboxes and respective infrastructures of information and communication technology. Therefore, today's designers have a very high level of product responsibility as disassembly is a major cost factor of product recycling. A study on the product redesign Methods and tools for sustainable management.
        4,000원
        9.
        2008.06 구독 인증기관 무료, 개인회원 유료
        Purpose of CH4 reference gases Intercomparison is to evaluate measurement ability among different laboratories and to improve problems in analyzing reference gases. As a result, the goal is for being reached a scale within the limits of the possibility in intercomparison. Korea Meteorological Administration (KMA) and Korea Research Institute of Standards and Science (KRISS) carried out CH4 reference gases intercomparison of the Far East Asia managed by Japan and CH4 intercomparison among standard institutions managed by Consultative Committee for Amount of Substance (CCQM) respectively. CH4 reference gas and standard gases is injected to calibrate instrument drift by turns and checked uncertainty of measurement additionally. Expanded uncertainty in intercomparison among meteorological administrations in the Far East Asia showed 1784.3 ppb±0.26%, 1935 ppb±0.29% respectively. Expanded uncertainty in the case of one point calibration and multipoint calibration showed 1903 ppb±0.11%, 1904 ppb±0.32% respectively. One point calibration obtained better result than mult-point calibration because of having an extent of different manufacturing uncertainty in the case of using various standard gases and having an instrument drift caused by long-time analysis. Through these intercomparison experiment, we could know that concentration of CH4 standard gases produced in CMDL was higher about 1.3~1.4% (about 24~26 ppb) than those of KRISS. This is reason caused a difference between manufactured by gravimetric method and manometric method. Therefore, the standard gases is required to intervalidation with standard institutions and GAW observatories. Also, a low level standard gases need to be calibrated by upper level standard gases periodically.
        4,000원
        10.
        2007.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        양안시기능 관련 검사에서 포롭터를 이용한 다소 제한적인 공간에서 측정한 값과 시험테를 이용한 보다 자유로운 시야가 제공되는 상태에서 측정한 값의 차이를 비교 분석하였다. 본 연구의 취지에 동의한 전신질환과 안질환이 없는 20세 이상의 성인 67 (26.11±2.56세) 남자 32명, 여자 35명)을 대상으로 하였으며, 굴절이상 수술 또는 사시 수술 병력이 있는 자는 대상에서 제외하였다. 자동굴절검사 (KR-7100P, Topcon Co.)와 자각식 굴절검사로 원거리 굴절이상도를 측정하였고, Phoropter(Shin-Nippon BR-7), Chart project(TopconACP-7), Trial Frame(FM 580), Lens Holder Kit(Gulden Ophthalmics co.), Loose Prism, MIM Card(Bernell co.)를 이용하여 양안시 검사를 실시하였다. 포롭터로 측정한 사위도는 VG(distance) -0.78±2.14△, VG(near) -2.63±4.64△, MR(distance) -0.35±1.85△, MR(near) -1.69±4.80△, MT(distance) -0.40±1.81△, MT(near) -1.78±4.52△였다. 시험테로 측정한 사위도는 VG(distance) -0.36±1.70△, VG(near) -1.43±4.00△, MR(distance) -0.08±1.54△, MR(near) -1.07±4.15△, 였다. 원거리 수평 융합버전스 측정 에서는 Smooth Vergence NFV(break/recovery) 10.15△/6.37△, PFV 18.58△/9.43△이었고, 근거리에서 NFV 19.01△/12.18△, PFV 20.13△/11.65△이었다. Step Vergence는 원거리에서 NFV 8.46△/4.73△, PFV 14.40△/7.89△이었고 근거리에서 NFV 15.78△/9.97△, 17.90△/11.03△이었다. 자유공간과 제한된 공간에서 각각 실시된 3가지 사위측정법에 대하여 1차 측정과 2차 측정값의 차이를 비교 분석한 결과 자유공간과 제한된 공간에서 원거리와 근거리 모두 MT측정법> MR측정법> VG측정법 순으로 신뢰도가 높았고 특히 포롭터에 의한 VG측정법의 신뢰도가 가장 낮았으며 시험테에 의한 MT측정법의 신뢰도가 가장 높았다. 양성융합버전스의 분리점은 원거리와 근거리 모두 Smooth vergence가 높았고 회복점도 원거리에서는 Smooth vergence가 높았으나 근거리에서는 통계적으로 유의한 차이가 없었다. 음성융합버전스는 분리점과 회복점 모두 Smooth vergence가 Step vergence보다 더 높았다. 따라서 자유공간과 비교하여 제한된 공간에서 실시하는 양안시 관련 검사가 사위도에는 크게 영향을 미치지는 않지만 MT측정법이 다른 측정법보다 신뢰도가 좋았으며 융합버전스를 평가할 때는 검사 방법에 따라 차이가 있을 수 있으므로 사위자의 자각증상 완화를 위한 프리즘 처방량을 산출할 때 융합버전스 예비량 측정법에 따라 처방량이 다르게 적용될 수 있을 것으로 사료된다.
        4,900원
        11.
        2007.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Recently, all kind of 21C-typed electronic goods show the tendency of hightechnology and digital convergence rapidly. Also, failure mechanism which differs from original goods concept presents. Today, failure mechanism which differs from one that was happened by restricted harmful environment material before adapted the raw of environment material is changing the paradigm of reliability engineering. Thus, when applied the environment matter of original and secondary material at the electronic goods were removed, reliability assessment method and prediction stay into low level. This study suggests as solution to overcome these phenomenon. The study on the management method of environmental restriction substances which is recognized as important element in the reliability assessment about environment material of electronic goods and the study on reliability assessment method of PWB without environment material are progressed.
        4,600원
        12.
        2007.12 구독 인증기관 무료, 개인회원 유료
        Weather is an important variable to form the characteristic natural ecosystem of the region along with topography and soil. Since the ecosystem change is expected by the global warming, the preparation for the change has to be made to accumulate the investigative data for the relationship on local weather and ecosystem. As the study method, the measurement data and sea surface temperature data were analyzed and the atmospheric model was performed. As the result, the weather characteristics, changing patterns and the causes of the weather change in Ulreungdo and Dokdo regions could be analyzed. For the last 67 years since the weather measurement was started in Ulreungdo, annual temperature elevation rate was 0.013oC and 0.88oC was elevated for 68 years, and the temperature elevation rate during the winter season recorded the highest elevation rate of 0.024oC/year. The amount of rainfall in Ulreungdo has been significantly increased recently. The strength of a typhoon that had affects on the peninsula and the increase of rainfall was mainly attributable to the increase of sea surface temperature alleviation at the East Sea. Sea surface temperature near Ulreungdo and the weather of the Ulreungdo weather station has high correlation each other. The acute sea surface temperature elevation could be assumed to cause the temperature elevation in Ulreungdo. According to the weather model of MM5, the simulated effect of sea surface temperature elevation on the atmospheric temperature resulted the average 1.3oC temperature increase in Ulreungdo as the sea surface temperature was increased 2oC. Therefore, it was able to confirm that the major reason of temperature elevation at the Ulreungdo weather station was attributable to sea surface temperature elevation.
        4,000원
        13.
        2007.11 구독 인증기관 무료, 개인회원 유료
        Recently, all kind of 21C-typed electronic goods show the tendency of hightechnology and digital convergence rapidly. Also, failure mechanism which differs from original goods concept presents. Today, failure mechanism which differs from one that was happened by restricted harmful environment material before adapted the raw of environment material is changing the paradigm of reliability engineering. Thus, when applied the environment matter of original and secondary material at the electronic goods were removed, reliability assessment method and prediction stay into low level. This study suggests as solution to overcome these phenomenon. The study on the management method of environmental restriction substances which is recognized as important element in the reliability assessment about environment material of electronic goods and the study on reliability assessment method of PWB without environment material are progressed.
        6,100원
        15.
        1989.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        4,500원
        18.
        2015.02 서비스 종료(열람 제한)
        최근 이상기후로 인해 전세계적으로 하천 제방 유실, 해안침식으로 인한 해안 사구의 유실, 도로 사면 및 절개지 붕괴, 산사태등에서 발생하였으며, 발생빈도가 계속적으로 증가하여 이로 인한 인명과 재산의 피해가 심각한 문제로 부각되고 있습니다. 그러나 홍수, 산사태 등에 대하여 안전하게 제방과 사면을 보호할 수 있는 공법이 확립되지 않아, 선진국에서도 이로 인한 자연재해에 대하여 대책이 확실하게 제시되지 않고 있다. 자연재해에 대한 복원 및 복구시 기존에 사용되고 있는 토목공법이나 재료들은 튼튼한 기초를 전제로 하여 시공되므로 기초를 할 수 없는 지역이나 기초가 붕괴되는 경우에는 사용 할 수 없는 공법이 대부분이며. 그러나 재난이 발생하는 지역은 아예 기초를 시공할 수 없는 지역이 대부분이므로 기존의 토목공법들을 사용하기 어렵기 때문에 재난 발생지역의 환경특성에 맞는 공법의 개발이 시급하며, 최근 자연형 하천 조성공법으로 조성되고 있거나 추진 중이지만 대부분의 경우 지금까지 경험적으로 시공되었던 종래의 공법을 무분별하게 적용함으로써 구조적인 안전성을 확보하지 못하여 수해가 발생하고 있는 실정이다. 따라서, 본 연구는 자연재해에 대한 구조적인 안정성 확보가 가능하고, 블록의 연결로 구조물을 축조하는 에코매직블록을 이용하여 현장시험을 통한 옹벽의 거동특성을 파악하였고, 수치해석을 실시하여 현장시험과 비교분석하였다. 현장시험결과와 수치해석의 결과를 비교하여 하중에 따른 변위가 거의 유사하게 나타났다.
        19.
        2001.11 KCI 등재 서비스 종료(열람 제한)
        본 연구에서는 21C 핵심산업이라 할 수 있는 IT분야를 선정하여 설문의 신뢰도와 관여도를 높이기 위하여 표본대상을 구매자로 하여 내적 준거가격이 결과변수에 주는 영향력이 관여도에 따라 조절되는가를 분석하기 위하여 선행 연구 검토와 실증 조사를 한 결과 관여도에 따라 결과 변수에 주는 영향력이 조절될 수 있다는 것이다.
        20.
        2001.02 KCI 등재 서비스 종료(열람 제한)
        This study was carried out estimating the dry deposition flux of SO2 at eight urban areas in Korea during one year of 1996. To calculate the deposition flux, deposition velocities were calculated by turbulence parameters estimated from routine meteorological data. Also, hourly averaged SO2 concentrations which calculated from air pollution monitoring data of each city were used. The dry deposition velocities were mostly higher in the coastal areas than the other areas, which would be caused by relatively strong wind. And, they were high in the daytime because of turbulence activities. The deposition flux of SO2 is mainly related to the atmospheric concentration. The annual average SO2 concentration and the deposition flux were 22.62ppb and 1510.52g/㎢/hr at Pusan respectively. Also, the flux was higher in winter than other season, which was a significant contribution of exhausted fuel for heating. While the deposition velocity was high to 0.688㎝/sec at Yosu in case of strong wind and small cloud cover, the deposition flux was high to 1597.4g/㎢/hr at Pusan in case of weak wind and small cloud cover.
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