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        검색결과 8

        1.
        2023.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        High-entropy alloys (HEAs) are attracting attention because of their excellent properties and functions; however, they are relatively expensive compared with commercial alloys. Therefore, various efforts have been made to reduce the cost of raw materials. In this study, MIM is attempted using coarse equiatomic CoCrFeMnNi HEA powders. The mixing ratio (powder:binder) for HEA feedstock preparation is explored using torque rheometer. The block-shaped green parts are fabricated through a metal injection molding process using feedstock. The thermal debinding conditions are explored by thermogravimetric analysis, and solvent and thermal debinding are performed. It is densified under various sintering conditions considering the melting point of the HEA. The final product, which contains a small amount of non-FCC phase, is manufactured at a sintering temperature of 1250oC.
        4,000원
        3.
        2017.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES :This study evaluates the reasonableness of the recommended amount of deicing chemicals based on historical data for snow removal. The result can be used to aid decision-making for the reservation of cost-effective de-icing chemicals.METHODS :First, the recommended amount of de-icing chemical to use and historical usage data were evaluated to identify specific usage characteristics for each region. Road maintenance length and snow-removal working days were analyzed over the past five winter seasons. Next, differences in the recommended amount of chemical to use and actual use were compared using the Kolmogorov-Smirnov test. Last, the two types of data were analyzed using a chi-square test to verify if the two distributions of variation pattern are statistically significant. We found that there are significant differences between the data from each region during the past five winter seasons.RESULTS :The results showed that the equation for calculating the amount of de-icing chemical to use appears to be revised.CONCLUSIONS :The results imply that the equation for calculating the amount of de-icing chemical to apply as a national standard is very important when the public agency makes decisions related to snow-removal.
        4,000원
        4.
        2017.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES:This study suggests a specific methodology for the prediction of road surface temperature using vehicular ambient temperature sensors. In addition, four kind of models is developed based on machine learning algorithms.METHODS:Thermal Mapping System is employed to collect road surface and vehicular ambient temperature data on the defined survey route in 2015 and 2016 year, respectively. For modelling, all types of collected temperature data should be classified into response and predictor before applying a machine learning tool such as MATLAB. In this study, collected road surface temperature are considered as response while vehicular ambient temperatures defied as predictor. Through data learning using machine learning tool, models were developed and finally compared predicted and actual temperature based on average absolute error.RESULTS:According to comparison results, model enables to estimate actual road surface temperature variation pattern along the roads very well. Model III is slightly better than the rest of models in terms of estimation performance.CONCLUSIONS :When correlation between response and predictor is high, when plenty of historical data exists, and when a lot of predictors are available, estimation performance of would be much better.
        4,000원
        5.
        2017.05 서비스 종료(열람 제한)
        Background : The practice of keeping the medicinal herbs at room temperature causes many problems, but due to lack of sufficient field research and study, it is difficult to improve related regulations and safety management. Methods and Results : The Cnidium Rhizome and Angelica gigas Root were inoculated with Lasioderma serricorne F. and incubated at 28℃ for 2.5 months and 5 months. After five months, the number of Lasioderma serricorne F. in Cnidium Rhizome increased from 30 to 1,429 (about 47 times). In the same period, the number of insects in Angelica gigas Root increased from 30 to 663 (about 22 times). Due to the rapid increase in pest population, hygiene deteriorated, changes in the active ingredient and appearance quality of the herbal medicines, which greatly damaged the value of the herbal medicine. Conclusions : These results show that current regulation requiring only sealing and not specifying the storage temperature do not guarantee quality safety. Therefore, it is necessary to establish appropriate preservation standards and improve management regulations in order to preserve safety.
        6.
        2016.10 서비스 종료(열람 제한)
        Background : Angelica dahurica Bentham et Hooker, Angelica gigas Nakai, Ostericum koreanum Maximowicz and Peucedanum japonicum Thumberg are a major medicinal plant in north Geungbuk province. Using medicinal plants are impotant it`s ingredient. Dry condition and stroage method are not standard manual. The ingredient variation of dry condition and stroage method were not researched. Methods and Results : Using plant material were cutivated on Gyongsangbukdo Bonghwa area. It were studied ingredient variation after dry and storage condition by HPLC methods. Major ingredient of Angelica gigas Nakai are decurusin, decurusinangelate. Heated air bulk dry get more decursin than natuarl dry and decurusinangelate of natural bulk dry was higher than heated air bulk dry. Major ingredient of Ostericum koreanum Maximowicz are imperatorin and isoimperatorin.. Imperatorin of Ostericum koreanum was highest peak on 50℃ heated-air dry after plastic bag sorage and isoimperatorin was highest peak on 40℃ heated-air dry after mountain cultivation. Imperatorin is a major ingredient Angelica dahurica Bentham et Hooker. Heated air bulk dry get more decursin and decursinangelate than natuarl dry and small heated-air dry. Peucedanol-7o_glucoside is a major ingredient Peucedanum japonicum Thumberg. Natural bulk dry get more peucedanol-7o_glucoside than heated-air bulk dry. Conclusion : Ingredient of Angelica dahurica Bentham et Hooker, Angelica gigas Nakai, Ostericum koreanum Maximowicz are different under various cutivation, drying method, storage. Diffent Ingedients of Angelica gigas Nakai, Ostericum koreanum Maximowicz were not accord it’s optical conditon.
        7.
        2016.10 서비스 종료(열람 제한)
        Background : Schisandra chinensis is being weighted difficulties in stable production, there is increasing drought damage caused by climate change as shallow rooted crops. Therefore, the study was performed for water supply capacity and growth characteristics analysis by setting the irrigation method for the drought damage reduction. Methods and Results : Test material was used sophomore V-shaped planting Schisandra chinensis. Irrigation method were surface watering, underground watering, sprinkler and untreated. Underground irrigation was irrigation that buried hose and then dug up the 15㎝. Soil moisture tension was the irrigation after fixed at -30 ㎪(23%). Irrigation timing was performed in June-July that high drought damage and made the most fruit enlargement. The main investigating items were investigated fruit growth, normal fault rate, soil moisture and EC content according to the irrigation method. Normal fruit rate according to irrigation method were appeared in sprinkler(81, 74 %)>underground irrigation(76, 69 %)>surface irrigation(76, 67%)>untreated(66, 52 %). Cluster length of yield component was determined to effective irrigation method in fruit growth the highest in sprinkler. Soil moisture contents was maintained at appropriate level with significant -30㎪(23 %) in the sprinkler. EC content low with a downward trend in underground irrigation and sprinkler. Water supply capacity according to Irrigation Method were sprinkler 40 tons, underground irrigation 85 tons, surface irrigation 138 tons. Conclusion : Appropriate watering methods for drought damage reduction of Schisandra chinensis caused by climate change was determined in the most efficient irrigation method in sprinkler that high fruit growth and normal fruit rate, lower the required of water supply capacity.
        8.
        2016.05 서비스 종료(열람 제한)
        Background : Aralia cordata and Polygonum multiflorum GAP cultivation requires a stable drying and storage settings after harvesting. therefore, this experiment was performed in order to effectively manage the physical, chemical and biological hazards. Methods and Results : Test materials were used biennial Aralia cordata, Polygonum multiflorum harvested from the medicinal testing ground. The drying temperatures were treated with 40, 50, 6 0℃ and natural drying. Storage containers were stored in plastic boxes, styrofoam boxes and kraft paper containers, examined the color and quality changes for eight months. Aralia cordata and Polygonum multiflorum drying temperature is dry it took natural drying 720 hours, 40℃ hot air drying 180 hours, 50℃ hot air drying 168 hours and 60℃ hot air drying 108 hours. However, the difference chromaticity of the Lab value corresponding to the temperature does not appear, it was good to dry in a short time at 60℃. Aralia cordata and Polygonum multiflorum stored in a styrofoam box storage method but can be stored at room temperature for up to four months, began to decay caused by moisture content it continues to increase. In plastic box in case of Aralia cordata and kraft vessel in case of Polygonum multiflorum can be stored for eight months in room temperature without decay. Styrofoam boxes stored at 5℃ cold storage were higher water absorption such as room temperature, but decay did not occur. Plastic box and styrofoam box were a tendency such as room temperature. Conclusion : Aralia cordata and Polygonum multiflorum are thought that the color change is not large depending on the drying temperature the lower the water content. Styrofoam storage box, the air permeability is higher than plastic boxes and containers Kraft vessel, decay occurs expected increase.