濟州道內 高等學校 物理敎育 正常化에 關한 硏究

李相法,尹志洪 제주대학 1980 논문집 Vol.12 No.2

In this stuay we investigated the status of physics education at high schools in Jeju-do and measured the experimental experiences of students graduated from high schools. We collected the data from 20 science or physics teachers and 383 freshmen in natural science classes in Jeju national college. The results of the investigations are as follows. (1) Most students and school administrators thought physics as an unimportant subject, and none of the students selected physics as an optional subject among those offered as natural sciences. (2) Experimental apparatus was not sufficiently availabie in each school and the students hardly made any physical experiments in the high schools. (3) The mean teaching hours assigned to physics teachers were nearly 21 hours per week. Many teachers were charged two or more subjectsin addition to physics. (4) Most teachers thought that an effective physics education was possible only through experimental study, but the lack of experimental apparatus made it impossible. Given these data we suggested that : (1) The necessity of physics education should be explained to the students and school administrators. (2) The teaching methods should be changed from those traditional ones to methods based on experiments and observations. (3) The physics teachers and school administrators should make an effort to improve all of the experimental equipment. (4) The physics teachers must be rid of their overload, and henceforth teach only their own major subjects.

퍼콜레이션 감수율의 진폭비의 보편성

이상법 경북대학교 과학교육연구소 1997 科學敎育硏究誌 Vol.21 No.-

We study the universality of two off-lattice percolation models, i.e., the continuum percolation of randomly centered disks and spheres for penetrable concentric shell(PCS) model and the randomly bonded percolation of uniformly distributed points, and also of the irreversible kinetic gelation model. We specifically consider the amplitude ratio of percolation susceptibilities R=C_-/C_+ (C_- and C_+ being the amplitudes below and above the percolation susceptibilities which is supposed to be universal but found to be different from the ordinary lattice percolation values in both two and three dimensions. By numerical investigation, we find that R depends strongly on the size of system for the former two off-lattice percolation models; after a finite size effect is carefully taken into account, R is found to be consistent with the known lattice value, indicating a strong universality between lattice and off-lattice percolation models. For the kinetic gelation model, on the other hand, we find that R does not depend strongly upon the size of system and is close to the lattice value, again indicating a strong universality between these two models. We point out that the primary cause of such differences may be the different (approximate) sampling techniques for the percolation susceptibilities. We discuss some subtleties of finite size scaling analyses.

연속 퍼콜레이션 모형의 감수율의 진폭비의 보편성

安駿浩,李相法 경북대학교 과학교육연구소 1994 科學敎育硏究誌 Vol.18 No.-

We study the universality-related problem of continuum percolations. We specifically consider the amplitude ratio of susceptibilities, R=C_-/C_+, which is supposed to be universal but found to be different from the lattice value. We discuss several possible sources of errors in estimating R by computer simulations and present simulation data for penetrable-concentric-shell model, with the finite size effect being carefully taken into account. Results from any finite-sized system were found to be significantly larger than the known lattice values: however, after taking extrapolations to the infinite-system-limit, we obtained R very close to the lattice values for both two and three dimensions. Based upon these, we conclude the strong universality between continuum and lattice percolation models for at least PCS model.

중등학교 에너지 보존 실험의 검증 및 새로운 실험 방법의 고안

서종식,기대연,이상법 慶北大學校 師範大學 科學敎育硏究所 1999 科學敎育硏究誌 Vol.23 No.-

We examined experiments for kinetic energy conservation in the high school textbook of Physics I and Physics II for the 6th National Science Curriculum and designed a new kit which enables to reduce experimental errors. Most experiments in the existing textbooks deal with the energy conservation for gravitational potential energy transforming to kinetic energy of the same object. We carried out the most commonly used two experiments and found that the experimental errors exceed more than 10~20 percent if carried out without carefulness. This may possibly make students suspect the mechanical energy conservation law. Our new kit, on the other hand, exhibits that the mechanical energy conserves with an error of less than 6% even in the process of transferring the elastic potential energy of one object to the kinetic energy of an another object.

Invasion Percolation Between Two Wells in Continuous Media

Sang Bub Lee 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.68 No.6

Invasion percolation between two wells was studied in continuous media consisted of overlapping disks and spheres. The invasion percolation between injection and extraction wells occurs when a fluid injected through the injection well invades less pressurized neighboring pores until it reaches the extraction well. Attention was paid to whether the probability distribution of the invading mass m and the fractal dimension of the clusters of invaded pore particles remain similar to those of the lattice model. Our results indicated that the power characterizing the probability distribution via P(m) / m− was considerably larger than that of the lattice model for a reduced volume density = c of pore particles, c being the percolation critical density, and that it converged to the value for the lattice model for pe = 0 as was increased, where pe is the pressure of an extraction site for the lattice model. The fractal dimension of the invaded clusters was found to be similar to that of the ordinary lattice percolation clusters generated at the percolation threshold. The scaling of the invaded clusters was also examined, and it held in both two and three dimensions.

DEVELOPMENT OF THE MULTI-DIMENSIONAL HYDRAULIC COMPONENT FOR THE BEST ESTIMATE SYSTEM ANALYSIS CODE MARS

SUNG WON BAE,BUB DONG CHUNG 한국원자력학회 2009 Nuclear Engineering and Technology Vol.41 No.10

A multi-dimensional component for the thermal-hydraulic system analysis code, MARS, was developed for a more realistic three-dimensional analysis of nuclear systems. A three-dimensional and two-fluid model for a two-phase flow in Cartesian and cylindrical coordinates was employed. The governing equations and physical constitutive relationships were extended from those of a one-dimensional version. The numerical solution method adopted a semi-implicit and finitedifference method based on a staggered-grid mesh and a donor-cell scheme. The relevant length scale was very coarse compared to commercial computational fluid dynamics tools. Thus a simple Prandtl’s mixing length turbulence model was applied to interpret the turbulent induced momentum and energy diffusivity. Non drag interfacial forces were not considered as in the general nuclear system codes. Several conceptual cases with analytic solutions were chosen and analyzed to assess the fundamental terms. RPI air-water and UPTF 7 tests were simulated and compared to the experimental data. The simulation results for the RPI air-water twophase flow experiment showed good agreement with the measured void fraction. The simulation results for the UPTF downcomer test 7 were compared to the experiment data and the results from other multi-dimensional system codes for the ECC delivery flow.

퍼콜레이션 감수율의 진폭비의 보푠성

( Sang Bub Lee ) 경북대학교 과학교육연구소 1997 科學敎育硏究誌 Vol.21 No.-

We study the universality of two off-lattice percolation models, i.e., the continuum percolation of randomly cenyered disks and spheres for oenetrable concentric shell(PCS) model and the randomly bonded percolation of uniformly distributed points, and also of the irreversible kinetic gelation model. We specifically consider the amplitude ratio of percolation susceptibilities R=C_/C+ (C_ and C+ being the amplitudes below and above the percolation threshold) which is supposed to be universal but found to be different from the ordinary lattice percolation values in both two and three dimensions. By numerical investigation, we find that R depends strongly on the size of system for the former two off-lattice percolation models; after a finite size effect is carefully taken in to account, R is found be consistent with the known lattice valusm indicating a strong universality between lattice and off-lattice percolation models. For the kinetic gelation model, on the other hand, we find that R does not depend strongly upon the size of system and is close to the lattice value, again indicating a strong universality between these two models. We point out that the primary cause of such differences may be the different subtleties of finite size scaling analyses.

A simulation analysis about rewetting of a vertical hot surface by MARS code

Sung Won Bae,Seok Cho,Ki Yong Choi,Bub Dong Chung 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6

A 6×6 vertical hot rod reflood test has been performed by KAERI to inspect the rewetting mechanism and evaluate the reflood simulation capability of the MARS code. The MARS code, which was developed by an integration of the one-dimensional RELAP5/MOD3 code and the multi-dimensional COBRA-TF code, has been improved to perform a subchannel analysis of light water reactors. The test section consists of a 6×6 rod bundle array, a flow housing, 4 pairs of borosilicate glasses for a visual observation and measurement instruments. Based on the subchannel analysis capability of the MARS code, a 6×6 reflood test case has been modeled and calculated by using MARS3.1. The test section has been modeled as a single channel and 3 sorts of rods. The differences between the single channel simulation and the experimental results are discussed.

Tension Estimation of Stay Cable Using Image Signal Processing Under Weather Conditions

Sung-Wan Kim(김성완),Bub-Gyu Jeon(전법규),Dong-Uk Park(박동욱),Nam-Sik Kim(김남식) 한국소음진동공학회 2016 한국소음진동공학회 학술대회논문집 Vol.2016 No.10

청소년기 대퇴간부 골절의 치료

조성도,조현오,곽경덕,류철수,이법재 대한골절학회 1995 대한골절학회지 Vol.8 No.3

Treatment of the femoral shaft fractures in adolescents with open physis is somewhat controversial. Historically, these fractures have been treated with nonoperative methods, but adolescents are less tolerant to the prolonged immobilization than younger children. Futhermore, conservative treatment in this age group may be prone to result in more complicati.ons such as malunion and shortening than that in the younger age group. Therefore many authars prefer the aperative method for femoral shaft fractures in the adolescents. The authors reviewed 22 cases of adolescent femoral shaft fractures treated during the period from January, 1988 to June 1992. Seven cases were treated conseratively, eleven by open reduction and intenal fixation with DCP, and four by closed intramedullary nailing. The patients treated with traction and casting showed more often complications such as angular deformity and bone shortening than in the operative methods. In comparing with those cases of plating, the patients of intramedullary nailing had statistically signiticant shorter ansthesic time and less blood loss in operation. All of the fractures treated with the intramedullary nails healed without malunion or leg length discrepancy, and there was no evidence of growth plate arrest. Results of this study suggest that closed intramedullary nailing of femur fractures in aldolescents is an effective treatment aption.