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최선진,허준호,김철위 大韓齒科器材學會 1990 대한치과재료학회지 Vol.17 No.1
The aim of the present investigation was assess the thermal reaction during hardening of representative fourteen commercially available conventional dental amalgam alloys: DA HA HV KA AC CA FC IH MM OT SS SCA SA UT and six high-copper dental amalgam alloys: A-21 KS LA OP PM PA used in Korea. These tests were performed with a thermistor probe (YSI Model 42 SC) using physiograph(MK-IV, Narco, Biosystems, U.S.A.). The peak temperature of the thermal reactions of dental amalgams were determined by the mean value of three measurements. From the experiments, the results were as follows: 1. The results indicate that the peak temperature of exothermic reactions of the conventional amalgams was attained during 7.67 ±1.76℃ and 15.50 ±0.50℃, respectively. 2. The results suggest that the exothermic peak temperature for the high-copper amalgams was considerably higher than those of the conventional amalgams. 3. The results for the recommended ratio revealed significant increases in exothermic reactions and the (+) modified ratio showed significantly less exothermic reactions than the (-) modified ratio. 4. The results show that the peak temperature rise of dental amalgams was attained during 7.17 ±0.29℃ and 24.17 ±0.29℃ according to the type of amalgamators, respectively.
Time Frequency Domain Reflectometry 기법을 이용한 Coaxial Cable에서의 결함 감지 및 추정
송은석,신용준,최덕선,육종관,박진배,Powers, Edward J. 한국항행학회 2003 韓國航行學會論文誌 Vol.7 No.1
본 논문에서는 도선사에서 발생하는 결함 위치와 이상 유무를 감지하는 새로운 고분해능 반사측정법인 시간-주파수 영역반사측정법 (TFDR, Time-Frequency Domain Reflectometry)을 제안하였다. 고전적인 반사측정법들은 단지 시간 또는 주파수의 한 영역에서 분석되어져 왔으나, 본 논문에서 제시한 TFDR은 도선의 결함 위치와 이상 유무를 발견하기 위해 과도신호의 시간과 주파수 영역의 정보를 동시에 이용할 수 있는 시간-주파수 분석기법으로 특성화하였다. TFDR의 기준신호 설계는 측정 케이블의 물리적 성질들을 고려하여 주파수 밴드를 결정하며, 도선의 결함감지와 추정은 시간-주파수 상호상관관계 함수에 의해 이루어진다. TFDR 시스템을 이용하여 여러 결함 상태를 가진 실제 coaxial cable (RG-142, RG-400)에 대해 실험하였고 정확성을 입증하기 위해 TDR (Time Domain Reflectometry) 장비와 성능은 비교하였다. 본 논문에서는 TFDR이 TDR보다 작은 오차로 결함을 찾아냄을 나타내고 있으며, 측정된 정확도는 TFDR의 오차율이 0.5%이하로 TDR (54750A/54754A) 장비보다 성능이 월등히 우수하다는 것을 알 수 있다. In this paper, a new high resolution reflectometry scheme, time-frequency domain reflectometry (TFDR), is proposed to detect and locate fault in wiring. Traditional reflectometry methods have been achieved in either the time domain or frequency domain only. However, time-frequency domain reflectometry utilizes time and frequency information of a transient signal to detect and locate the fault. The time-frequency domain reflectometry approach described in this paper is characterized by time-frequency reference signal design and post-processing of the reference and reflected signals to detect and locate the fault. Design of the reference signal in time-frequency domain reflectometry is based on the determination of the frequency bandwidth of the physical properties of cable under test. The detection and estimation of the fault on the time-frequency domain reflectometry relies on the time-frequency domain reflectometry is compared with commercial time domain reflectometry (TDR) instrument. In these experiments provided in this paper, TFDR locates the fault with smaller error than TDR. Knowledge of time and frequency localized information for the reference and reflected signal gained via time-frequency analysis, allows one to detect the fault and estimate the location accurately.
Hydroxyapatite 비드에 부착한 [^3H] - 표지된 세균의 씬틸레이션 측정에 관한 연구
이시영,이장희,최선진 대한구강생물학회 1989 International Journal of Oral Biology Vol.13 No.2
This study investigated the possible involvement of sample self absorption when [^3H]-labeled Streptococcus mutans cells that adhered to spheroidal hydroxyapatite beads were counted by scintillation spectrophotometer. To determine whether or not the beads cause self absorption of the energy of β particles, the beads-adhered bacterial cells were removed and counted alone. Two procedures were employed to remove bacterial cells from the beads. First, bacteria-adhered beads were dissolved with 0.33 N HCl, the dissolved solution was filtered to collect bacteria, and the filter was counted. Second, the bacteria adhered to beads were desorbed with potassium phosphate buffer, bacteria were collected on filter, and the filter was counted. Whatman glass microfibre filters GF/A and GF/F were used and filtration was carried out either with suction or without suction (i.e., by blotting). When the radioactivity was counted by blotting on GF/F filter, the count rate was increased to 280% in HA and 240% in SHA as compared with CPM of the control. Count rate of the bacteria was lower when filtered with suction than without suction. However, there was no difference in count rate when intact cell suspensions filtered either with suction of without were counted. Though HCl-treated cells were observed as intact by Gram staining, the above results seem to indicate that cells were damaged when treated with HCl, thus some of the DNA leaked out of the cells when filtered with suction. When the buffer-desorbed bacterial cells were filtered by blotting and counted, the count rate was increased to 290% in HA and 350% in SHA as compared with CPM of the control. The results of the present study mean that a high count rate is obtainable when the sample self absorption is removed. Therefore, the sample self absorption should be considered in order to measure the correct number of bacteria adhered to HA beads.
한국산 인삼의 Polyphenol 분획물의 항산화, Phospholipase A2 및 암세포증식 억제효과
최희진 ( Choe Hui Jin ),한호석 ( Han Ho Seog ),박정혜 ( Park Jeong Hye ),손준호 ( Son Jun Ho ),배종호 ( Bae Jong Ho ),성태수 ( Seong Tae Su ),최청 ( Choe Cheong ) 한국응용생명화학회 2003 Applied Biological Chemistry (Appl Biol Chem) Vol.46 No.3
The polyphenol fractions of Korean ginseng were purified using Sephadex LH-20, MCI gel, Bondapak C_(18), TLC, and HPLC from the 60% acetone soluble fraction. Fraction I showed 48.16%, 79.71% and 43.55% inhibition at 150 ppm against lipid oxidation in the presence of copper ion, superoxide and hydrogen peroxidation. Electron donating abilities of fraction Ⅱ showed 35.17% inhibition at 200 ppm. Fraction Ⅲ showed 48.49% and 25% inhibition at 150 ppm against lipid oxidation in the presence of ferrous ion and hydroxy radical ion. The phospholipase A₂ inhibitory effect of fraction Ⅲ was 48.9% at the concentration of 60 ㎍/m/. The cytotoxic effects of fraction Ⅱ was the highest (73.29% at 0.25 ㎎/m/) among the tested polyphenol fractions.
손재진(Son Jae-Jin),이두진(Lee Doo-Jin),최민권(Choe Min-Kwon) 대한건축학회 2003 大韓建築學會論文集 : 構造系 Vol.19 No.12
Recently, As large scale construction works are widely prevalent a more scientific approach to construction management is required. Also, each construction company is searching for a new computer information management system as part of computerization of construction management. Especially in the field of process control management, which constitutes the core of construction management business, a software system that is already available in the market is used, while new software systems are being developed. but, the effective ness of process control softwares as they are used today is yet to be verified.<br/> Therefore, the purposes of this study are to identify the problems of process control through investigating the operational realities of process control software in the construction field, and to search for ways of its active and effective use.