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Flowable Resin을 이용한 접착식 보정장치의 결합강도 연구
강대근,손우성,김형일 大韓齒科器材學會 2004 대한치과재료학회지 Vol.31 No.4
This in vitro investigation was conducted to determine the bond strength of two resin material using universal testing machine and to verify the failure mode for each test specimen with stereoscope. Eighty human permanent maxillary and mandibular premolars were randomly divided into 2 groups (40 in each group). Teeth were mounted in stone block (2 teeth in each block) and a 3 mm diameter area of enamel of each sample were etched, rinsed, dried, and adhesives were applied according to the manufacturers' instructions. A bonded orthodontic retainer with triflex wire was bonded to buccal enamel surface. Debonding was then performed with a force using an Instron universal testing machine. The force was recorded at bond failure. The results data was collected and the mode of fracture failure recorded. The broken specimens were examined with 20× stereoscope to determine the fracture location or failure mode. Failures for each adhesive system were evaluated with ARI scores. The t-test was performed to determine any statistically significant differences among bond strength values of the two materials. And Chi-square test was used to compare the Modified adhesive remnant index (ARI) scores for the two groups. This in vitro study concluded that; 1. There was no statistical difference in mean bond strength between the flowable (Filtek Flow^(�)) and conventional (Filtek Z250^(�)) resin material (p=0.128). 2. The fracture modes of all samples were resin-wire interface failure or combination of enamel-resin and resin-wire interface failure. Bonded lingual retainer with flowable resin might have clinically acceptable bond strengths. Modes of failure site of flowable resin and conventional composite resin were similar.
하향링크 다중 사용자 MIMO 시스템에서의 일반화된 사용자 선택 알고리즘
강대근,최승원,신창의,금동현 (사)디지털산업정보학회 2012 디지털산업정보학회논문지 Vol.8 No.4
Recently, there are many user selection algorithms in multi user multiple-input multiple-output (MU-MIMO) systems. One of well-known user selection methods is Semi orthogonal user selection (SUS). It is an algorithm maximizing channel capacity. However, it is applicable only when user’s antenna is one. We propose a generalized user selection algorithm regardless of the number of user’s antennas. In the proposed scheme, Base station (Bs) selects the first user who has the highest determinant of channel and generates a user group that correlation with first user’s channel is less than allowance of correlation. Then, each determinant of channels made up of first user’s channel and a user’s channel in the generated group is calculated and BS selects the next user who has the highest determinant of that. BS selects following users by repeating above procedure. In this paper, we get better performance because of selecting users who have the highest determinant of channel as well as allowance of correlation optimally calculated through matrix operations.
강대근,허정호,신헌철,Kang, Dae-Keun,Heo, Jung-Ho,Shin, Heon-Cheol 한국재료학회 2008 한국재료학회지 Vol.18 No.3
The morphology of three-dimensional (3D) cross-linked electrodeposits of copper and tin was investigated as a function of the content of metal sulfate and acetic acid in a deposition bath. The composition of copper sulfate had little effect on the overall copper network structure, whereas that of tin sulfate produced significant differences in the tin network structure. The effect of the metal sulfate content on the copper and tin network is discussed in terms of whether or not hydrogen evolution occurs on electrodeposits. In addition, the hydrophobic additive, i.e., acetic acid, which suppresses the coalescence of evolved hydrogen bubbles and thereby makes the pore size controllable, proved to be detrimental to the formation of a well-defined network structure. This led to a non-uniform or discontinuous copper network. This implies that acetic acid critically retards the electrodeposition of copper.
식분환(息賁丸) 및 비기환(?氣丸)이 백혈병(白血病) 임파종(淋巴腫) 환자(患者)에서 추출(抽出)한 암세포(癌細胞)에 미치는 항암(抗癌) 효과(效果)
강대근,강병기,Kang, Dae-Geun,Kang, Byung-Ki 대한한방내과학회 1991 大韓韓方內科學會誌 Vol.12 No.2
Attempts were made to see the antitumor effects of Sigbunhwan widely used in Oh-jug(五積) employing tumor cells Lines such as K562 derived from erythroleukemia, Raji from lympoma and MO-4 from blastogenic tumor. Different concentrations of Sigbunhwan and combined therapy of Sigbunhwan and Bigihwan were treated to those tumor cells lines and then live cells were counted by Trypan blue assay and $^{3}H-Thymidine$ uptake assay. The results obtained were as follows. 1. $^{3}H-Thymidine$ uptake of various tumor cells lines when treated with high concentrations of Sigbunhwan for 48hours showed that the rate of DNA synthesis decreased 76% to 90% by the treatment of 1% Sigbunhwan but this inhibition was rather decreased when Sigbunhwan concentration was increased to 10, 15 and 20%.(Fig 3) 2. When Sigbunhwan was combined with Bigihwan which was also an antitumor drug, the effectiveness of tumor cells dealth was somewhat inceased showing a generally similar pattern to that of Bigihwan alone used.(Fig 4) This combination therapy also showed that higher concentrations of antitumor agent were no more·effective or rather harmful according to the tumor cells lines having different growth rate.(Fig 5,6) 3. The antitumor effects of combined Sigbunhwan and Bigihwan was decreased if the concentrations of this combination therapy was increased to 10 times showing relatively sluggish decrease in K562 and MO-4 but a sharp inhibitory effect in Raji which grows slowly.(Fig 7). 4. When Sigbunhwan was treated at low concentrations, K562 was more inhibited by 0.75% to 1.0% of Sigbunhwan while Raji was more inhibited by 0.25% to 0.5% of that.(Fig 8) 5. When Sigbunhwan was treated together with Bigihwan at low concentrations, the tumor cells death rate was 75% to 89% in Baji, 31% to 95% in MO-4 and 41 to 89% in K562, showing this combination therapy was more effect to Raji derived from lymphoma.(Fig 9) 6. The number of live tumor cells was correlated with optical density of MTT assay when measured with 2% Sigbunhwan treatment to tumor cells lines for 24 hours.(Fig 10) 7. 7 days treatment of 0.25% Sigbunhwan was compared with one day treatment of 1% suggesting long term treatment more effective.(Fig 11)