氣泡發生에 依한 液體의 張力에 關한 硏究

金龍澤 慶北工業專門大學 1980 論文集 Vol.17 No.-

When the cavitation in the real liquid took place, the tension of real liquid was studied by analytical method and checked by experiment. A spherical bubble is assumed to grow from a bubble nucleus inside an infinite body of real liquid and conical cavity of solid surface. Agreement of the analytical and experimental results was good.

垂直 等溫 얼음 平面에서 固體-液體 界面의 移動速度가 自然對流에 미치는 影響

芮龍澤 慶一大學校 1986 論文集 Vol.2 No.1

When an isothermal solid flat plate is in contact with a surrounding pure water which is at a temperature different from that of the wall, it is well known that fluid motion occurs in the vicinity of the wall. This motion is induced by the existence of a density distribution within the fluid as a result of the temperature difference between the wall and the fluid far from the wall. An analytical study has been performed on influence of melting velocity of a vertical ice surface in natural convection immersed in pure cold water. The governing equation with boundary conditions are solved numerically by using code BOUNDS and FDN. The results are as follows; first, in the calculation of the velocity components, u and v of parallel and vertical derection to ice surface, FDM( ?? ≠0) agree with the results of FDM( ?? =0) than similarity. Second, in the mean Nusselt number FDM( ?? ≠0) agree with the results of FDM( ?? =0) than similarity for ?? .

수직적 안모형태와 치아성숙도의 상관관계에 대한 연구

구용한,현홍근,김정욱,장기택,이상훈,한세현,김종철 大韓小兒齒科學會 2010 大韓小兒齒科學會誌 Vol.37 No.1

본 연구는 수직적 안모형태와 치아성숙도의 관계를 평가하고 이러한 연관성에 대한 사춘기 성장의 영향을 평가하기 위한 것이다. 이번 연구를 위해 7세에서 9세, 13세에서 15세 환자 1306명을 Ricketts의 VERT index를 이용하여 수직적 안모 형태를 분류하였고 환자들의 치령을 Demirjian법으로 평가하여 다음과 같은 결과를 얻었다. 1. 모든 군에서 치령이 역령과 비교 시 통계적으로 유의한 수준에서 크게 측정되었다. 2. 사춘기 연령군에서 brachyfacial type의 경우가 dolichofacial type 보다 치아성숙도가 크게 나타나는 경향을 보였다. 여성의 경우는 통계적으로 유의성있게 차이가 나타났으며, 남성의 경우는 통계적 유의성은 보이지 않았다. 3. Brachyfacial type의 경우 사춘기전 군들과 비교 시 사춘기 군들에서 치아성숙도가 유의성있게 높게 나타났으며, dolichofacial type의 경우는 연령층간 치아성숙도의 차이를 보이지 않았다. The purpose of this investigation was to study the relationship between vertical facial pattern and dental maturation in children in pubertal and pre-pubertal periods. The material consisted of lateral head films and panoramic radiographs of 1306 patients. The subjects were selected according to Ricketts's VERT index and other including criteria. These subjects were divided by VERT index to brachyfacial group and dolichofacial group. In each selected subject, dental age was determined according to Demirjian's dental maturity score. All subjects were distributed according to age, vertical facial type and sex, mean and standard deviation of chronological age, dental age and age difference were determined in each group. And the data were analysed to find the difference of tooth maturation by facial pattern. Findings of this study include: 1. In all groups, dental age was determined higher than chronological age in statistically significant level. 2. Compared by vertical facial pattern, in pubertal age groups, it seems that subjects with brachyfacial type presented the tendency to have an advanced dental maturation, only in female group. 3. Compared by pubertal period, brachyfacial groups presented more advanced dental maturation in pubertal groups than pre-pubertal groups.

균일 열유속 조건의 원기둥에 의한 자연대류에서 원기둥의 경사각이 열전달특성에 미치는 영향

芮龍澤,秋弘錄,方昌焄 慶一大學校 1997 論文集 Vol.14 No.2

Natural convection heat transfer of circular cylinder is investigated experimentally. The main purpose of this study is to investigate the effect of inclined angles of the cylinder on natural convection characteristics. The cylinder is made of aluminum, and air is used as the cooling fluid. In this experiments, local temperature measurements are made along the surface of the cylinder. In this study, results are obtained for heat flux of 150 W/m2∼600 W/m2, inclined angle of 0o∼90o. Results indicate that the local heat transfer coefficient is increased with the increasing of heat flux at the constant inclined angle. Also, at the same heat flux, the local heat transfer coefficient is increased with the increasing of inclined angle from the vertical position.

TSMG법에 의한 RE-123계 초전도 단결정 제도에 미치는 seed의 영향

오용택,신동찬 조선대학교 생산기술연구소 2004 生産技術硏究 Vol.26 No.2

This study investigated the phase transformation of the REBa₂Cu₃O_(7-x) (RE=Nd, Gd, Dy) superconductor, and CCT (Continuous-Cooling-Transformation) along with the TTT (Time-Temperature-Transformation) diagrams are suggested according to the isothermal and continuous cooling heat-treatments. According to result of fabricated single crystal of RE-123 superconductor through TSMG method based on phase transformation neted among heat-treatment process, which the ionic radius elements was decreased, RE-211 phase was well-distributed. The highest Jc intensity was obtained in the RE-211 supercondoctors heat-treated used seed of high miscut angle and heat-treatment in O₂ atmosphere.

低溫의 물 속에 잠겨있는 水平 平面에 의하여 惹起되는 自然對流

芮龍澤 慶一大學校 1992 論文集 Vol.8 No.1

The natural convection from upward and downward facing horizontal isothermal plate immersed in cold water is studied numerically. The temperature of the plate is from 0.0℃ to 8.0℃ and the ambient water temperature is from 1.0℃ to 10.0℃. Numerical results are presented for the velocity profiles, temperature profiles, local heat transfer coefficient, and average Nusselt numbers over the entire flow fields. For the upward facing surface there are upflow and unsteady flow. And the ranges of the ambient water temperatures which give rise to the upflow are more extensive as the temperatures of the isothermal surfsce become more distant from the density extremum temperature. For the downward facing surface, only the downflow region is shown. For the upward facing horizontal isothermal surface, the average Nusselt number is 28.86(Ra)??. And for the downward facing surface, the average Nusselt number is C?(Ra)>??.

서울대학교치과병원 소아치과를 내원한 교정환자의 분포양상에 대한 연구

구용한,현홍근,김정욱,장기택,이상훈,한세현,김종철 大韓小兒齒科學會 2009 大韓小兒齒科學會誌 Vol.36 No.4

과거에 비해 소아 및 청소년기에 교정치료를 시작하는 경우가 증가하고 있으며 따라서 소아치과에서 교정치료가 차지하는 비율 역시 증가하는 추세이다. 이러한 변화에 맞추어 소아치과에 내원하는 교정환자의 분포 양상을 파악하기 위하여 본 연구를 시행하였다. 2006년 1월부터 2008년 12월까지 서울대학교 치과병원 소아치과를 내원한 환자 중 교정 진단 받은 792명을 대상으로 조사를 진행하였으며 다음과 같은 결과를 얻었다. 1. 교정 진단을 받은 환자의 연령 분포는 8세가 22%로 가장 많았고 7세(19%), 9세(16%) 순서로 나타났다. 2. 골격 분포는 골격성 1급 부정교합이 52%로 가장 많았고 3급(29%), 2급(19%)순서로 나타났으며 연령이 낮은 경우 3급 부정교합 환자의 비율이 높은 경향을 보였다. 3. 총 792명의 환자 중 28%인 218명에서 전치부 반대교합을 보였으며 연령이 낮은 경우 그 비율이 높은 경향을 보였다. Distribution of orthodontic patients in pediatric dental clinics has increased recently. So it is worth to study about the present status of orthodontic patients in pediatric dental clinics. The purpose of this study was to recognize the characteristics and orthodontic patterns of orthodontic patients in pediatric dental clinics. The material consisted of distribution and orthodontic analysis records of 792 new patients in the department of pediatric dentistry, Seoul National University Dental Hospital, from 2006 to 2008. Results were as follows 1. In age distribution, 8-year-olds group comprised 22%, 7-year-olds 19%, 9-year-olds 16%, 10-year olds 15%, 11-year-olds 11%, and other age groups comprised 18%. 2. In skeletal patterns, skeletal class Ⅰ patients comprised 52%, class Ⅱ 29%, and class Ⅲ 19%. 3. In vertical facial types mesofacial comprised 41%, brachyfacial 35%, and dolichofacial 24%. 4. Out of 792 patients 218 patients(28%) showed anterior cross-bite, and the occurrence ratio of anterior cross-bite increased as the age decreased.

기계적으로 정착된 철근의 이음길이에 관한 실험적 연구

이용택,황홍순 한밭대학교 2004 한밭대학교 논문집 Vol.21 No.-

In this study, the lap length of headed bars are evaluated through the experimental works. Headed bars are lap-spliced perpendicular to the direction of longitudinal bars in beam. Five beam specimens were tested for the performance evaluation on lap splice. Their variable examined was the lap length of headed bars. Two concentrated loads were applied at the end of lapped bars to make the same magnitude of bending moment for the lapped region. Performances of lap splice were evaluated on the basis of strength, stiffness, and drift capacity. Test results show that 14 times the diameter of bar is suitable as lap length.

농촌지역 소규모 중학교 수학학력 저하의 변인 연구

최택영,신용국 한국학교수학회 2002 韓國學校數學會論文集 Vol.5 No.1

The purpose of this study is to find out if there are meaningful differences between small rural middle schools and nearby urban ones in the mathematical diagnostic evaluation. It also says how to improve students' scholastic abilities, making up a question of attitudes towards math to know the mathematical abilities lowering cause in small rural middle schools. Findings are, 1. Students must recognize that studying math is essential and be interested in it. 2. The mathematical confidence is needed. 3. A strong will of studying math hard is important. 4. Students must have a motivational triggering, while solving math problems and then checking answers for themselves. 5. Backward countries' humanistic and social environmental factors should be overcome. In conclusion, we expect the mathematical abilities improvement, making students remove the mathematical abilities lowering cause after having a learning experience suitable for the rural community instead of negative attitudes towards math.

CO₂를 作業流體로한 原動所의 硏究

金龍澤 慶北工業專門大學 1979 論文集 Vol.16 No.-

Until now a power plant has been used to a medium of working by steam in a heat engine of producing great generating power, but it did not increase and effect of high temperature, high pressure, regeneration, and reheating. In this study, instead of steam dioxide carbon was used with the object of development for the power plant of high efficiency. And small power plant in a medium of working was designed with the dioxide carbon in the pump, the regenerator, the turbine and concentrator. These results lead to a conclusion that the power plant in a medium of working with the dioxide carbon is utilized.