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        검색결과 16

        1.
        2022.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The PoN (Proof of Nonce) distributed consensus algorithm basically uses a non-competitive consensus method that can guarantee an equal opportunity for all nodes to participate in the block generation process, and this method was expected to resolve the first trilemma of the blockchain, called the decentralization problem. However, the decentralization performance of the PoN distributed consensus algorithm can be greatly affected by the network transaction transmission delay characteristics of the nodes composing the block chain system. In particular, in the consensus process, differences in network node performance may significantly affect the composition of the congress and committee on a first-come, first-served basis. Therefore, in this paper, we presented a problem by analyzing the decentralization performance of the PoN distributed consensus algorithm, and suggested a fairness control algorithm using a learning-based probabilistic acceptance rule to improve it. In addition, we verified the superiority of the proposed algorithm by conducting a numerical experiment, while considering the block chain systems composed of various heterogeneous characteristic systems with different network transmission delay.
        4,000원
        2.
        2020.03 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Two different casting speeds of 60 and 80mm/min are adopted to determine the effect of casting speed on the microstructure and mechanical properties of Al-Mg-Si/Al hybrid material prepared by duo-casting. The obtained hybrid material has a uniform and straight macro-interface between the pure Al side and the Al-Mg-Si alloy side at both casting speeds. When the casting speed is increased to 80mm/min, the size of primary α phases in Al-Mg-Si alloy decreases, without change of shape. Although the Al-Mg-Si alloy produced at higher casting speed of 80mm/min shows much higher ultimate tensile strength (UTS) and 0.2 % proof stress and lower elongation, along with higher bending strength compared to the case of the 60mm/min in casting speed, the tensile properties and bending strength of the hybrid material, which are similar to those of pure Al, are the same regardless of the increase of casting speed. Despite the different casting speeds, deformation and fracturing in hybrid materials are observed only on the pure Al side. This indicates that the macro-interface is well-bonded, allowing it to endure tensile and bending deformation in all hybrid materials.
        4,000원
        3.
        2020.02 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        In this study, three kinds of metal chills such as SS400, AC4CH and brass, with different thicknesses of 40 ~ 80 mm, were applied for low pressure casting of Al-Si alloy to control cooling rate. The microstructural characteristics with increasing cooling rate were represented using factors including D1, D2, size of primary α phases and shape factor and size of eutectic Si. The tensile properties were investigated and additionally analyzed based on the microstructural characteristics. As the cooling rate increased, D1, D2, and sizes of primary α phases and eutectic Si apparently decreased and the shape factor of eutectic Si increased to over 0.8. The ultimate tensile strength (UTS) and yield strength (YS) increased with decreasing D1, D2, and size of primary α phases, while elongation increased with decreasing size of eutectic Si and concurrently increasing shape factor of eutectic Si. This indicated that the primary α phases and eutectic Si in Al-Si alloy were refined with increasing cooling rate, resulting in improvement of UTS and YS without sacrificing elongation. After the tensile test, preferential deformation of primary α phases was observed in the Al-Si alloy produced at higher cooling rates of more than 0.1 K/s.
        4,000원
        4.
        2018.09 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        This investigates the microstructure and mechanical properties of Al hybrid material prepared by electromagnetic duo-casting to determine the effect of heat treatment. The hybrid material is composed of an Al-Mg-Si alloy, pure Al and the interface between the Al-Mg-Si alloy and pure Al. It is heat-treated at 373, 573 and 773K for 1h and T6 treated (solution treatment at 773K for 1h and aging at 433K for 5h). As the temperature increases, the grain size of the Al-Mg-Si alloy in the hybrid material increases. The grain size of the T6 treated Al-Mg-Si alloy is similar to that of one heat-treated at 773K for 1h. The interface region where the micro-hardness becomes large from the pure Al to the Al-Mg-Si alloy widens with an increasing heat temperature. The hybrid material with a macro-interface parallel to the tensile direction experiences increased tensile strength, 0.2% proof stress and the decreased elongation after T6 heat treatment. On the other hand, in the vertical direction to the tensile direction, there is no great difference with heat treatment. The bending strength of the hybrid material with a long macro-interface to the bending direction is higher than that with a short macro-interface, which is improved by heat treatment. The hybrid material with a long macro-interface to the bending direction is fractured by cracking through the eutectic structure in the Al-Mg-Si alloy. However, in the hybrid material with a short macro-interface, the bending deformation is observed only in the limited pure Al.
        4,000원
        9.
        2017.05 서비스 종료(열람 제한)
        Background : This study aimed to determine the use of proper organic fertilizer through side dressing application in the environmental cultivation of Adenophora triphylla var. japonica Hara. to improve farming income. Methods and Results : In the cultivation of eco-friendly and environmental medicinal plant like Adenophora triphylla var. japonica Hara., it is necessary to use organic instead of chemical fertilizer. Organic fertilizers such as HL, CK, OK were applied three (3) times during the last ten days of July, August, and September. There was no significant difference between CF and NT, in terms of the number of rooting per 1㎡ which was 12.1 -12.9. There were also no significant differences in plant length, leaf length, leaf width and dry weight. The root length was 19.9 ㎝, which was the longest in CK, and 16.8 ㎝, the shortest in ST, but described as no significant difference. The root width was 14.8 – 5.5 ㎜, and the number of rootlet was 5.7 - 7.1, but was considered not a significant difference. The dry weight was 16.6 g in HL, 16.3 g in CK and ST, and 15.6 g in OK, but still there were no significant differences observed. However, it was 14.6 g in NT, which was considered the lowest, thus there was a significant difference. The number of dry root per 10 a was 149 ㎏ which is considered the most in HL, 141 ㎏ in CK, 140 ㎏ in ST, and 138kg in OK yet there were no significant differences observed. While NT only had 123 ㎏ hence, there was a significant difference on the number of dry root per 10a as compared with the group applied with the three organic fertilizers. Conclusion : In conclusion, it is proper to use Organic Fertilizer HL and CK through side dressing application in growing Adenophora triphylla var. japonica Hara.
        10.
        2017.05 서비스 종료(열람 제한)
        Background : This project was conducted to determine proper seed harvest time and seed storage methods of Adenophora triphylla var. japonica Hara. Methods and Results : When Adenophora triphylla var. japonica Hara. transplanted this year, seeding can only be done the following year. Therefore, the seeds harvested in the interval of ten (10) days were investigated for seed harvest amount, germination rate, seed storage temperature and storing on container, between the period late August and mid-October. It is when the seed fructification started and ended. The seeds harvested from the first ten (10) days of October to mid October were 87.9% in whole seeds. The proper seed harvesting time was mid October which has a germination rate of 75% in whole seed harvest time. The lowest germination rate of 27.3% was at the germination temperature of 15℃. As the temperature rises, the germination rate increases. In 29℃, the germination rate was at 79% which is the highest; and from 30℃, the germination rate decreased to 71%. When the storage temperature was at 0℃ after storage of 5 months, the germination rate was at 83%. However, after storage of 12 months, it decreased by 7% that was 76%. When in 4℃, after storage of 5 months the germination rate was at 85%. However, after storage of 12 months it decreased by 8% which was 77%. In room temperature after storage of 5 months, germination rate was at 77%, but after storage of 12 months it decreased by 22% which was 55%. When seeds were stored in vinyl container, it was observed that the germination rate was at 86% after 5 months of storage, which was 9% higher than seed stored in paper which was 77%. After 12 months storage, seed in vinyl container had a germination rate of 71%, which was 3% higher than seed in paper at 68%. Conclusion : It is concluded that the proper time of seed gathering of Adenophora triphylla var. japonica Hara. is during the first ten (10) days of October to mid-October. When the long time storage is needed, below zero temperature with vinyl container is more appropriate.
        11.
        2013.12 KCI 등재 서비스 종료(열람 제한)
        Post-thawed larval rearing in Pacific oyster Crassostrea gigas was performed to investigate the survival rate with time course in three kinds of larvae cryopreserved. The highest survival rate and larval activity index (LAI) of post-thawed larvae were obtained from the permeation in 0.2 M sucrose and 2.0 M ethylene glycol (EG) at -1℃/min in freezing speed showing the survival rates just after thawing of 63.8% in trochophore, 84.1% in D-shaped veliger and 56.3% in early umbo veliger. In post-thawed larval rearing with food supply, the larvae lasted their lives until 24 hours in trochophore, 75 hours in D-shaped veliger and 57 hours in early umbo veliger. The results suggested that each larval stage post-thawed revealed no more further development to subsequent respective stage.
        13.
        2010.09 서비스 종료(열람 제한)
        In the present study, to understand the process of abnormal pigmentation (hypermelanosis) on the blind side of olive flounder P. olivaceus during early development, we investigated an time that staining on the blind side is initially observed with the naked eyes, counted the number of stained spot on the blind, and calculated the ratio of area stained on the blind side, and the ratio of fish pigmented on the blind side with growth. The present experiment was initiated at 24-day after hatching (dah), just after the starting of metamorphosis, in which fish mean size is total length (TL) 12.4±0.2 ㎜ and body weight (BW) 19.9±0.7 ㎎, and was finalized at 94-dah (TL 72.0±0.6 ㎜, BW 3,912.3±119.4 ㎎). The experimental animals were reared in FRP tank at 20±0.5℃ in water temperature and 30.9±0.1 psu. The experimental animals were feed with rotifer, Artemia nauplii and commercial food according growth stage. As results, the pigmented spots are composed with adult-type melanophores. The first spot was found in microscopy level at 38-dah (TL 18.3±0.4 ㎜, BW 57.6±4.1 ㎎), but the first staining spot observed with the naked eye was found 52-dah (TL 37.6±0.5 ㎜, BW 534.2±30.9 ㎎) around the pectoral fin and the caudal peduncle. The pigmented spots became more distinctive and expanded around the edge of rear on the blind side. The number of spots and the ratio of area stained on the blind side sharply increased between 31-dah and 80-dah, and between 66-dah and 94-dah, respectively. The ratio of fishes stained on the blind side increased between 45-dah and 73-dah, and then was stagnated to 94-dah. Therefore, these results concluded that the pigmentation on the blind side of olive flounder is not an temporary and reversible color change but an irreversible abnormal phenomenon that pigment cells is continuously differentiated on the blind side with growth for early development just after metamorphosis in artificial culture conditions.
        16.
        2003.06 KCI 등재 서비스 종료(열람 제한)
        This study was carried out to understand the genetic pattern of self-sterility, using a self-fertile variety Cheongyangnative 1 and nine self-sterile cultivars in cultivated boxthorn (Lycium chinense Mill., 2n=24). The inheritance of self-fertility (SF)wa