치아 수복용 불소함유 glass filler의 제조 및 특성

김대성,최세영,김경남,김광만,김중곤 대한치과기재학회 1998 대한치과재료학회지 Vol.25 No.3

The purpose of this study was the reaching test of restorative glass according to composition. Mixtures of SrF₂, CaF₂and SiO₂were fused in platinum crucible. The glasses were ground and fraction which passed through a 400 mesh (38㎛) sieve were collected. The powder specimens were analyzed by a DTA and XRD. Then powder specimen were inserted to D. I. water with various of dissolution time and composition at 37℃. Fluoride ion, cation release, solubility, and pH change were estimated. It was clear that the glasses were formed except S0.65. In S0.40, Tg, Ts, and Tc were 630, 672, and 813℃ respectively. In initial 0.5 hrs., amounts of released fluoride ion and cation were about 90% of total released amounts and released rate was decreased with dissolution time. Amount of released fluoride ion and cation were increased with decreasing SiO₂ in glass filler. And released rate was decreased rapidly by adding CaF₂. This was caused by structural variation in glass filler. Solubility was similar tendency with ion released. The pH of D.I. water was 4.5. But in intial 0.5 hrs., pH was 8.2∼9.8., and decreased according to dissolution time. This is caused by ionic changing with cation and H* ion.

메탄과 에탄의 흡착평형에 대한 활성탄의 기공 크기 분포의 영향

김대규,금경호,서양곤 경상대학교 환경보전연구소 2000 環境保全硏究所報 Vol.8 No.-

The adsorption equilibria of methane and ethane in a slit pore model of activated carbon were studied by using Monte Carlo method. In potential caculation. the fluid-fluid interactions are described using the "12-6" Lennard-Jones potential function. and fluid-pore surface interactions are described using the "10-4-3" potential function proposed by Steele. It showed that the pore size distributions effected isotherms from the simulation results in pure component adsorption of methane and ethane at 1∼30 bar pressure. Also adsorbed moleculars could identified occuping location and density from density profiles and snapshots.

품종 및 성별에 따른 쇠고기의 지방산조성 비교

김대곤,성삼경,정근기,최창본 대구산업정보대학 1995 논문집 Vol.9 No.2

Dae Gon The study was conducted to investigate the effect of breed, sex on fatty acid compostition. Hanwoo and Holstein used, in the study were classified by sex. The results are summarized as follows ; Oleic acid and unsaturated fatty acids(UFA) percentages of total fatty acids in Hanwoo were higher than in Holstein, but palmitic acid and saturated fatty acids(SFA) were lower in Hanwoo. Oleic acid in steers of Hanwoo and Holstein tended to increase compared with bulls. Oleic acid in rib loin and top round were considerably higher in Hanwoo steers than in Holstein steers. In Hanwoosteers, oleic acid and UFA tended to increased while stearic acid and SFA decreased as marbling degree increased.

한우거세우의 도체 육질등급과 쇠고기 이화학적 성질과의 상관관계

김대곤,성삼경,정근기 대구산업정보대학 2000 논문집 Vol.14 No.2

The study was conducted to investigate the effect of castration on the carcass grade of Hanwoo reared under the same feed and feeding condition. The carcass grading scores were measured by the Korean carcass grading standards. The results were compared with respect to Hanwoo by sex. Hanwoo steers showed significantly higher marbling degree than Hanwoo bulls. In Hanwoo steers, moisture content was lower while crude fat was higher than in Hanwoo bulls. Water holding capacity and L value of rib loin were higher in steers than in bulls. Collagen content was higher in bulls than in steers. The degree of hardness and chewiness in steers were significantly lower than those in bulls. Moisture contents and cooking loss of water were decreased where crude fat contents and water holding capacity were increased as marbling degree increased.

다양한 비스테로이드성 소염진통제의 쥐 피부 투과

김민정,도희정,조원제,용철순,최한곤,이치호,김대덕 한국약제학회 2002 Journal of Pharmaceutical Investigation Vol.32 No.4

Rat skin permeation of various nonsteroidal antiinflammatory drugs (NSAIDs) was investigated in vitro using Franz diffusion cell at 37℃. The effect of various skin permeation enhancers was also observed as a preliminary study of developing transdermal delivery systems of NSAIDs. Lipophilicity of NSAIDs was determined from the partition coefficient (log P) in 1-octanol/water and 1-octanol/IPB mutual-saturated solutions. The solubility was determined in water, isotonic phosphate buffer (IPB), and propylene glycol (PG) at 37℃. The rat skin permeation rate of acetaminophen, piroxicam, and aceclofenac was almost negligible, although they were saturated in PG. Addition of 1 % permeation enhancer increased the permeation rate of ketoprofen, ketorolac, and diclofenac. However, the skin permeation rate of ibuprofen did not increase with the addition of various enhancers. Among the permeation enhancers tested, oleic acid was the most effective for various NSAIDs. Based on the daily dose, lipophilicity, and the skin permeation rate achieved in this study, ketoprofen and ketorolac seem to be the most promising drug candidates for transdermal delivery systems, especially when formulated with unsaturated fatty acids, such as oleic acid.

각형강관을 이용한 스틸콘크리트 단위벽체의 축내력에 관한 실험적 연구

김곤묵,홍석일,이대현,김호수 대한건축학회 2003 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.23 No.2(구조계)

The steel house, one of new construction methods, has been mainly adapted to a lot of housing and developed in construction skill. But the disadvantage of steel house system is that the system is limited to small housing because it is composed of light gauge steel. Therefore, in order to solve it, this study presents the new system which is made of a carbon steel square for general structural purpose. The framed wall system which is presented in this study is composed of the steel stud members by using the carbon steel square and is reinforced by the horizontal members called runner. So, this system has more sufficient strength and axial load capacity than the steel house wall system. Besides, this system gives us the improved effects of the adiabatic and sound insulation by filling up the autoclaved lightweight concrete. Accordingly, this study evaluates on the axial capacity of unit wall of the system through the experimental study according to the experimental variable and analysis on the structural performance of the framed wall system using carbon steel square.

3-5㎜ 강판절단용 아크플라즈마 절단기 팁 개발

김대철,김곤호,박강석 漢陽大學校 工學技術硏究所 1999 工學技術論文集 Vol.8 No.1

3-5mm 강판 절단용 플라즈마 토치의 핵심 부품인 토치 팁의 개발을 위하여 기존의 전원부 및 토치 팁의 특성을 관찰하였다. 강판의 두께, 강판과 팁 사이의 간격 그리고, 유입 가스의 압력 변화에 따른 절단 속도를 측정하였다. 전산 모사를 통하여 가스 흐름에 대한 최적의 조건을 얻어 swirl number=2.5에서 최대 온도 분포를 갖음이 관찰되었다. 이 결과를 이용하여 Electrode를 가공하였으며 높은 온도를 가진 Plasma Jet의 분포를 얻을 수가 있었다. 또한 Nozzle의 모양을 V자 형태로 변화하여 Slag 형성이 최소한으로 발생하는 최적의 토치 팁을 개발하였다. In order to develop new torch tip, major component of the plasma torch for cutting steel plate with 3-5mm thickness, the characterization of power supply and torch tip was carried on the jutting speed with steel thickness, the distance between steel and tip, and inlet pressures. The optimum design condition of gas flow to provide the high temperature distribution in the torch, the swirling number 2.5, was obtained from the computer code (DC plasma torch) simulation. It was also observed that a new torch tip manufactured with the of optimum conditions, swirling number=2.5, and V-shaped nozzle formed less slag after the cutting process.

화소 간축과 블록의 MAD를 이용한 고속 적응 블록 정합 기법

김준한,박준호,전대성,김상곤,윤영우 영남대학교 공업기술연구소 1999 工業技術硏究所論文集 Vol.27 No.2

We propose a fast block matching technique that adaptively limits searching depth using the value of MAD and the adjustment of the number of searching points by pixel decimation when estimating motions in the field of video compression. The underlying schemes of the proposed technique are the three step searching(TSS) scheme, pixel decimation, and the MAD as block matching criterion. In block matching schemes, the picture quality is proportional to the number of searching points that are used in estimating block motions. It also enhances the quality by increasing the points to be searched, because the probability of falling into the local minima can be decreased compared to the TSS scheme. The increasing computational complexity, proportional to the increased searching points, is reduced by introducing the pixel decimation method. Moreover, we can reduce the amount of computation by determining the search depth using the block MAD. With the proposed algorithm, we performed a lot of simulation for the various MPEG video data. As a consequence, it can improve the picture quality while reducing the amount of computation involved comparing to the TSS scheme.

정전탐침을 이용한 ICP Plasma에서의 E-H mode변환에 관한 연구

김대철,김곤호 한양대학교 이학기술연구소 2001 이학기술연구지 Vol.3 No.-

Plasma potential using the Radio frequency is fluctuate as RF field. When there is Rf that is changed as the time-varying plasma potential. negative shift phenomena of floating potential that decreases as the increasing of induced RF Voltage is observed in I-V curve trace obtained by Langmuir probe. In this paper we investigate the changing of floating potential when the input power is changed from 50 to 800 W in N2 gas and Ar gas on ICP plasma. In case of N2 and Ar, we can investigate that the floating potential become fixed after negative shift phenomena in 500 W and 200 W. This result shows that there is no more fluctuation caused by electric field and the change of mode is expected. When we use the capacitive probe and the magnetic probe, the different tendencies are measured at the each positions of mode change. Thus the mode changes of ICP plasma can be measured from investigation of the changing of floating potential. RF(radio frequency)를 이용한 플라즈마의 공간 전위(plasma potential)는 인가되는 RF field에 따라 변동한다. 시간에 따라 공간 전위가 변동하는 RF가 존재할 때 정전탐침으로 얻은 전류-전압 곡선에서의 부유전위(floating potential)는 인가해준 RF 전압이 증가함에 따라 감소하는 부유전위의 negative shift하는 특성을 갖는다. 이와 같은 부유전위의 변동을 ICP 플라즈마에서 N_(2) 기체와 Ar 기체에서 입력 전력을 50에서 800 W까지 변화시켜가며 정전탐침을 이용하여 관찰한 결과 N_(2)의 경우 500 W Ar의 경우는 200 W에서 negative shift 현상을 보인 후 일정해지는 것을 관찰할 수 있었다. 이는 정전기장에 의한 변동이 더 이상 커지지 않음을 의미하며 plasma의 발생 특성의 변화를 예상할 수 있다. 이 결과는 Capacitive 탐침과 magnetic 탐침의 결과에서도 mode가 변환하는 지점에서 서로 다른 경향을 나타내었다. 따라서 부유전위 변동의 관찰만으로도 ICP 플라즈마에서의 mode 변환 여부를 알 수 있다.

웨이블렛 변환을 이용한 정전 탐침 자료 분석

김용현,김대경,김곤호 한양대학교 이학기술연구소 2001 이학기술연구지 Vol.3 No.-

정전탐침으로 얻은 플라즈마 자료를 보다 객관적이고 일관성 있게 해석하기 위하여 해석 프로그램을 개발하였다. 이 프로그램은 저온 저밀도의 DC 플라즈마 정전탐침자료에 대하여 기존의 방법과는 달리, 이중직교 웨이블렛을 이용하여 플라즈마 공간전위를, Daubechies wavelet을 통하여 이온과 전자의 포화전류를 정의한 후 Newton-Raphson 방법을 이용한 비선형 곡선 적합(non linear fitting)에 의해 전자온도를 결정함과 동시에 이중 직교 웨이블렛이 가지고 있는 오차를 보정하는 특징을 가진다. 이 프로그램은 자료를 분석하기 위한 분석자의 입력값이 전혀 필요하지 않기 때문에 분석결과의 객관성을 높일 수 있었다. 모의 플라즈마 자료에 대한 프로그램 정확도 시험결과는 전자온도, 플라즈마 전위, 전자 포화 전류값 등에 있어서 95%이상의 정확도를 갖는 것으로 나타났다. A new program has been developed for an analysis of an electrical probe data. Unlike an usual data analysis algorithm, this program has used a wavelet transform for low temperature DC plasma data filtering and determining plasma parameters. Biorthogonal wavelet transform has been adopted to determine the initial plasma potential and Daubechies wavelet to an electron and ion saturation current. By using a nonlinear data fitting, Newton-Raphson method, the electron temperature has been determined after compensating an error from the biorthogonal transform algorithm. This program can reduce an uncertainty from data analysis because it is not necessary to input a pre-defined input data. When a sample data has been tested, plasma parameters, plasma potential, temperature and electron saturation current, can be decided within 95 % accuracy.