隔板을 가진 傾斜 4角密閉空間內의 自然對流 流動特性

鄭仁基,金重燁,洪性吉 嶺南大學校 工業技術硏究所 1987 연구보고 Vol.15 No.2

Two-dimensional natural convection in a partially divided inclined square enclosure is investigated experimentally. Two opposite walls of the enclosure are adiabatic while the other two isothermal walls are maintained at different temperatures, and a partition is situated perpendicularly at the mid-height of one adiabatic wall. The flow visualization experiments are carried out with water, Pr=4.95, for two Rayleigh numbers, Ra=1.968x10?? and 3.936x10??. The inclination of enclosure is varied from -30°to 90°, and the length of a partition is varied from L=0 to L=11/13W. The length of a partition and the inclination of an enclosure are to significantly effect on the flow patterns within the enclosure. The transition to the primary circulating flow is occured at the inclination of 30°∼40°, and the strongest wall-boundary flow and the wide core-stagnation region are presented at the inclination of 50°∼60°regardless the partition length. An oscillatory motion of natural convection is also found to occur in certain lengths of a partition at θ=0°, such as an enclosure heated from below with a horizontal partition.

圓住針狀形 Fin 群에서의 强制對流 熱傳達 特性

鄭仁基,金重燁,李判錫 嶺南大學校 工業技術硏究所 1981 연구보고 Vol.9 No.2

Experiments on forced convection of air for the cylindrical pin-fin arrays were performed for a Reynolds number range of 210.5 to 1052.6. The effect of interfin spacing, ?//d×??/d=2×2 and 3×3, was investigated for in-line and staggered pin-fin arrays. Data were also obtained for changing of the pin-fin height. The experimental data were utilized to compare with the values calculated for the tube banks. The results were as follows; 1) The average heat transfer coefficients for staggered array are higher than those for in-line array. Those for both pin-fin arrays more affected are more affected in Reynolds number than tube banks, and lower pin-fin arrays. 2)The heat-transfer rate for staggered array in the same interfin spacing are higher than those for in-line array, and the heat transferred increases as the spacing of pin-fins becomes narrow. 3)The fin efficiency of pin-fin arrays decreases as the Reynolds number increase, and this situation is more in lower pin-fin arrays. The fin efficiency for in-line arrays is higher than that for staggered arrays.

壓縮比 變化에 따른 CI機關의 熱發生率 및 機關性能에 關한 實驗的 硏究

鄭仁基,金重燁,金學洙,金壽淵 嶺南大學校 工業技術硏究所 1982 연구보고 Vol.10 No.2

The study on the heat release and the engine performance of CI engine is experimentally performed with variation of compression ratio and inlet pressure. In this experiment, compression ratio in cylinder is decreased and inlet pressure is increased. The results of this study are as follow: the thermal efficiency increases and the maximum combustion pressure decreases as compression ratio declines and inlet pressure rises. For the case of the same mean effective pressure, specific fuel consumption and smoke become to be low. According to the results, the advantages are achieved for the noise, vibration, performance and smoke.

가스交煥過程을 包含하는 4行程 CI 機關의 Cycle Simulation

金重燁,金壽淵,權俊博,鄭仁基 嶺南大學校 工業技術硏究所 1985 연구보고 Vol.13 No.1

A comprehensive cycle simulation was developed to predict the performance of CI engine including intake and exhaust systems with variation of operating conditions and design factors. In this work, the gas-exchange model, compression and expansion model, single-zone combustion model and heat transfer model were used. In order to confirm the feasibility of the simulation program, the calculated results were compared with the experimental results. Pressure diagram, I.M.E.P. and S.F.C. by means of calculations showed acceptable quantitative agreement with the experimental data. A parametric study of the effect of variations in injection timing and inlet pressure was carried out. Therefore, the optimal design of CI engine will be possible by the cycle simulation using this program.

Methanol을 副燃料로 한 디젤機關의 性能에 關한 實驗的 硏究

金重燁,鄭仁基,金宇燮 嶺南大學校 工業技術硏究所 1982 연구보고 Vol.10 No.1

An experimental study on the performance of the diesel engine using methanol as an additional fuel was performed. In order to increase the amount of methanol, dual injection method has been used that a carburettor for methanol injection was connected with the inlet system. The performance tests have been conducted, and the power output, heat consumption and smoke have been evaluated up to 40% methanol in volume. As the results, it was shown that the rate of methanol mixed was differed from the load. The stable running was possible by 50%(wt.) of the methanol mixing at full range of the output. On the viewpoint of specific heat consumption and excess air ratio, the methanol mixing was profitable at high load. As the increasing of mixing rate, the inlet air and exhaust gas temperatures and the cooling loss were reduced, and smoke density was reduced significantly. By heating the methanol-air mixture, the output was increased, but according to the rate of methanol mixing and the load, inlet air temperature was limited by knock.

휜을 가진 空氣式 太陽熱 集熱器의 性能에 關한 硏究 : For Longitudinal Straight Fins 第1報, 流動方向으로 直線흰을 가진 경우

鄭仁基,許重九,金重燁 嶺南大學校 工業技術硏究所 1982 연구보고 Vol.10 No.1

A performance of the solar air heaters with longitudinal straight fins was estimated theoretically and experimentally. The experiment has been carried out with two air heaters which have the ratio of fin-height to the parallel-plate spacing, 0.4 and 0.8 respectively, and the Reynolds number in flow duct was varied from 2.6×10³to 7.7×10³. In the theoretical analysis a new equation predicting collector efficiency factor was derived from heat balance, and the performance of these solar collectors was computed over the range of Reynolds number from 2.6×10³to 1.54×10⁴. The results of the theoretical calculation are very well approached to those of the experiment. It is conceivable that the collector efficiency factor derived from this study is applicable to the interpretation of the performance of the finned type solar collectors. The efficiency of these solar air heaters was not inferior to the other air-type and liquid-type solar collectors.

측부 인두강 조절 피판술(Lateral port Control Postrior Pharyngeal Flap)의 임상적 고찰

마흥수,정중길,함기선 大韓成形外科學會 1983 Archives of Plastic Surgery Vol.10 No.2

In 1973, Hogan first reported the lateral port control(L.P.C.) pharyngeal flap surgery, modification of the superiorly based posterior pharyngeal flap, introducing the concept of positive port control utilizing a “catheter technique”. This modification is superior to the classical posterior pharyngeal flap for speech improvement, but there have been some reports that complications occurred during the postoperative period. This method of operation has not been fully accdepted by plastic surgeons throughout the world, even though it has many advantages for better speech improvement. So, there are still many unclarified clinical problems: what are the reasons for the occurrence of complications following the surgery, how long the insertion of the catheter should be kept or how the complications can be reduced. There are some recent interesting reports about the reduction of these complications to the same level as in the classical flap when operation is performed after a complete preoperative study including nasopharyngoscopy and lateral or basal cineradiography for an accurate evaluation of velopharyngeal function. The authors caried out this analysis based on a retrospective review of clinical recordings of 217 patients operated on during the past 5 years from 1977 to 1982 at St. Mary's Hospital in Seoul. 142 patients out of the 217 underwent nasoendoscopy and lateral cineradiography study, and 87 patients of the 142 were subjected to complete speech evaluation by the above examinations. The study of complications was made on the 142 patients by two objective fimls, and the speech evaluation was conducted for the 87 patients by means of two objective films and a subjective examination. The patients were divided into three groups preoperatively according to the width & distance of velophavryngeal gap on endoscopy and lateral cineradiography. The incidence of complications was observed as to the duration of cthete insertion, with the catheter remoed within three days after operation in one group and fie days in another group. The following results were obtained. 1. Speech improvement has no relation with the degree of the preoperative V.P.I., but L.P.C. has a higher frequency of speech improvement and the frequency of complications is similar to that in the clasical posterior pharyngeal flap surgery. 2. Based on endoscopic findings and a long-term follow-up study, it is recommendable that the catheter by inserted for five days for the acquisition of an adequate port size and resulting speech ability. 3. The most frequent complications were nasal obstruction, oral breathing and snoring.

치과용 금합금에 대한 금속 프라이머 처리와 열순환 처리가 교정용 브라켓의 전단결합강도에 미치는 영향

이영기,차정열,유형석,황충주 대한치과교정학회 2009 대한치과교정학회지 Vol.39 No.5

치과용 금합금에 교정용 브라켓 접착 시 금속 프라이머와 열순환 처리가 전단결합강도에 미치는 영향을 알아보기 위하여 80개의 치과용 금합금 시편을 샌드블라스팅만 처리한 군과 3종류의 금속 프라이머(Alloy Primer, Metaltite, V-Primer)처리를 시행한 군으로 분류하고, 이를 열순환 처리 시행 여부에 따라 모두 8개 군으로 분류하였다. 만능물성 시험기를 사용하여 브라켓의 전단결합강도를 측정하고, modified ARI (Adhesive Remnant Index) scores를 통해 브라켓 접착면의 파절 양상을 평가하였다. 열순환 처리 미시행 시에는 금속 프라이머의 적용 시 샌드블라스팅만 단독으로 처리한 경우에 비하여 통계적으로 유의성 있는 전단결합강도의 증가가 있었다 (p < 0.05). 열순환 처리를 시행한군에는 금속 프라이머의 처리에 의한 전단결합강도의 변화는 유의한 차이가 없었다 (p > 0.05). 금속 프라이머를 적용한 경우 열순환 처리 미시행 시에는 파절 양상이 브라켓과 접착제 계면에서의 파절 발생 빈도가 높았으나, 열순환 처리 시행 시에는 각 군 간 파절 양상에 유의한 차이가 없었다. 이상의 결과로 금속 프라이머의 적용이 치과용 금합금에 대한 교정용 브라켓 접착 시 초기 접착 강도에서는 유의성 있는 결합력의 증가를 보이나, 열순환 처리 시행 후에는 결합 강도에서는 유의한 차이가 없는 것으로 나타나 금속 프라이머에 의한 결합력 증가가 감소하는 것으로 생각한다. Objective: The aim of this study was to evaluate the effect of metal primers and thermocycling on shear bond strength between the orthodontic bracket and gold alloy. Methods: For this study, 80 specimens made of dental gold alloy were divided into 8 groups based on the combination of metal primers (none, Alloy primer, Metaltite, V-primer) and thermocycling (with and without thermocycling). Shear bond strength testing was performed with a universal testing machine. Bond failure sites were classified by a modified ARI (Adhesive Remnant Index) score. Results: All metal primer treated groups showed a significantly higher shear bond strength than the only sandblasting treated group without thermocycling (p < 0.05). There were no significant differences on shear bond strength in the groups with thermocycling (p > 0.05). Bond failure sites of the metal primer treated group without thermocycling occurred at gold alloy/adhesive interface, whereas there were no differences on bonding failure sites in the groups with thermocycling. Conclusions: These findings suggest that using metal primer on gold alloy enhances the initial bracket bond strength. But, this effect was not shown with thermocycling.

후방 도달 척추 절제술을 이용한 강직성 요천추 변형의 치료

석세일,정의룡,이정희,김진혁,김성수,이지호,최원기,박용원 대한척추외과학회 2004 대한척추외과학회지 Vol.11 No.2

隔板에 의해 分離된 四角密閉空間內의 自然對流

金壽淵,鄭仁基,金重燁,朴日均 영남대학교 공업기술연구소 1984 연구보고 Vol.12 No.1

Natural convection heat transfer in a two-dimensional, square enclosure fitted with a partial vertical partition was investigated numerically using ADI and SOR methods. The vertical walls of the enclosure were maintained isothermal at different temperatures, while the horizontal walls and the partition were insulated. The computation were carried out with air, Pr=0.733, in the Grashof numbers range 1.25×10³≤Gr≤2×10⁴, for seven cases as the lengths and positions of the partition were varied. The partition were found to significantly effect on the heat transfer and the flow pattern within an enclosure.