세계 명작 속의 사랑이야기

김병걸 문예운동사 2001 문예운동 Vol.- No.69

Mechanical mixing 법으로 제조된 비고용 Si/Pb 계 및 SiO2/Pb 계 복합재료의 Percolation 전기전도특성

김병걸 대한금속재료학회(대한금속학회) 1999 대한금속·재료학회지 Vol.37 No.10

An inter-relationship between electrical conductivity and microstructure of mechanically mixed dual phase materials was investigated to clarify the conductive mechanism using insoluble systems such as Si SiO₂ and Pb elements. The microstructure of Si/Pb system showed a typical granular structure that Pb particles with a diameter of 0.2㎛ to 5㎛ were dispersed in Si matrix. On the other hand, SiO₂/pb system exhibited a percolation structure that Pb particles with non-uniform shape of sub-㎛ sizes were embedded in amorphous SiO₂ matrix. The morphologies of two mechanically mixed systems were quite different each other. This is believed to be due to the difference of plastic deformability of Si and SiO₂ elements. We also found that no considerable dissolution of Si and SiO₂ into Pb was detected. The two insoluble systems showed a positive TCR(Temperature Coefficient of Resistance) property from 4.2K to 300K and had a same conductor-insulator (semiconductor) transition composition at 15 vol.% of Pb. This can be concluded that the mechanism of electrical conductivity in these systems can be interpreted as a percolation theory. A very high electrical resistivity of these systems is attributed to the percolation structure (clusters) having many links and deadends, and introduced many defects (dislocation, void, vacancy, stacking fault) and internal stress during mechanical mixing process. These factors will interfere with the movement of conductive electrons significantly. The mechanism of electrical conductivity of these systems can be explained by Cayley-tree networks.

Al-0.11Fe계 합금에서의 Zr, Sc원소 미세첨가에 따른 연속주조재 및 압연재의 특성

김병걸,김상수,김성규,김지상,김진한,Kim, Byung-Geol,Kim, Shang-Shu,Kim, Sung-Kyu,Kim, Ji-Sang,Kim, Jin-Han 한국전기전자재료학회 2007 전기전자재료학회논문지 Vol.20 No.12

In order to develop non-heated STAl(super thermal resistant Aluminum alloy) for ampacity gain conductor, the systematic research was carried out. Especailly, the effect of a very small amount of Zr, Sc element in EC grade Al ingot on mechanical and electrical properties was our priority. As a result, it was found that the strength and recrystallization temperature of designed alloy was gradually increased with Zr, Sc addition up to 0.3 wt.%. However, the electric conductivity showed no drastic change. The tensile strength and recrystalliztion temperature, $17.75{\sim}20.05\;kgf/mm^2$ and $420{\sim}520\;^{\circ}C$, was obtained at 0.3 wt.% Zr, Sc addition, respectively. Particles of the $Al_3Zr$ and $Al_3Sc$ phase affected the ambient and elevated-temperature strength of the alloys.

통전 중 산불에 노출된 가공송전선의 온도 및 장력 변화 거동

김병걸,장용호,김상수,한세원,Kim, Byung-Geol,Jang, Young-Ho,Kim, Shang-Shu,Han, Se-Won 한국전기전자재료학회 2009 전기전자재료학회논문지 Vol.22 No.4

The authors have published several technical reports on the deterioration of conductor due to forest fire in series so far. This is because even we have been experiencing hundreds of forest fires every year, no systematic research on conductor which is very vulnerable to fire have been fulfilled. This paper describes the sag-tension behavior of conductor under loading current normally when only partial area of a long conductor is exposed to fire. Temperatures of Overhead Conductor were different with measurement position. When the partial area of conductor was heated up to $500^{\circ}C$, 20 % of permanent tension loss was observed. This results in the increase of sag of 1.5 m when span is 300 m. The other results will be presented in the text.

산불에 의한 가공송전선의 열화거동

김병걸,김상수,한세원,김진한,Kim, Byung-Geol,Kim, Shang-Shu,Han, Se-Won,Kim, Jin-Han 한국전기전자재료학회 2007 전기전자재료학회논문지 Vol.20 No.12

Because forest fire can give a serious damage to overhead conductors, the thorough understanding about aging behavior of burned conductor is very important in maintaining the transmission line safely. Therefore, a systematic investigation was carried out by heating method. As the heating temperature increases, drastic change of tensile strength of Al wire due to the softening of Al wire occurred. When Al wire is exposed to the flame(about $800\;^{\circ}C$) during only 13 seconds, the remained tensile strength of Al wire showed under 90 %. The detailed results will be given in the text.

문학과 역사 : 계급전쟁의 서사시 , 스탕달의「 적과 흑 」

김병걸 사회평론 1991 월간 사회평론 Vol.91 No.11

가공송전선 (ACSR) 용 고탄소강선의 Tension-tension 피로특성

김병걸,우병철,김상수 대한금속재료학회(대한금속학회) 2001 대한금속·재료학회지 Vol.39 No.6

This paper describes the tension-tension fatigue properties of high-carbon steel wire containing around 0.6wt.% C, which is used as a stranded wire for ACSR(Aluminum Stranded Conductors Steel Reinforced) in transmission power lines. ACSR which consists of galvanized steel strand and aluminum core always experiences serious vibration by wind. Therefore, it is very important to clarify the fatigue property of core wire for ACSR to determine its lifetime and stability of power delivery. Since steel wires are produced by a wire drawing process, they possess a very long fiber-lamellar microstructure which has a very short inter-layer distance between ferrite and cementite layer. The long fiber-lamellar microstructure is expected to have a different fatigue behavior compared to conventional plate and bulk-type materials. In order to characterize the fatigue property of steel wire having the unique microstructure mentioned above, tension-tension fatigue tests were carried out on specimens drawn to various strains. The fatigue strength was 106.7㎏f/㎟ at ε=1.79, and 92.0㎏f/㎟ at ε=1.19, which showed an inverse relationship with drawing strains. The fatigue strength of a hard-drawn wire was as high as 66∼70% level of its tensile strength. This value was very high compared to that of rolled or full-annealed materials, which exhibited 40∼60% level of their tensile strength. The high fatigue strength is attributed to the very fine elongated pearlitic microstructure formed by the drawing process, which suppresses formation and growth of microcracks. A good correlationship between theoretical fatigue strength and experimental one was found, which meant that yield and tensile strength were the main factors to affect the fatigue property of the steel wire.

가공전선의 이도거동에서 탄성계수와 선팽창계수의 영향

김병걸,김상수,왕윤찬,Kim, Byung-Geol,Kim, Shang-Shu,Wang, Yun-Chan 한국전기전자재료학회 2008 전기전자재료학회논문지 Vol.21 No.10

The effects of elastic modulus coefficient and linear expansion coefficient of overhead distribution power line(ACSR $58 mm^2$) on sag behavior in distribution line have been investigated to clarify the difference between specification and experimental level. The elastic modulus coefficients of Al wire and steel wire were $5,182.6 kgf/mm^2,\;18,348.8 kgf/mm^2$, respectively Therefore, the computational composition elastic modulus coefficient of the power line was $7,063.5 kgf/mm^2$, while that of experimentally measured was $7681.1 kgf/mm^2$. As a result, we found that elastic modulus coefficient which was experimentally measured was higher than that of computational by 8.7 %. However, when planner designs the sag of disoibution line, the elastic modulus coefficient of power line $8,400 kgf/mm^2$ should be generally adopted. These two different using values lead to the sag difference of 0.62 m. The other results will be discussed.

전자식 안정기용 비정질 함침코어의 자기장거동 해석

김병걸 대한금속재료학회(대한금속학회) 2000 대한금속·재료학회지 Vol.38 No.11

Computer simulation was carried out to investigate the behavior of magnetic field and eddy current property using FLUX2D on an amorphous mold core. Magnetostatics analysis shows that flux density distributes uniformly throughout the amorphous core and its value was about 0.92 T. It was found that when the direction of magnetic path changes drastically within the angle of 90°in an amorphous core, an uniform magnetic flux density was obtained throughtout the core. Magnetodynamics analysis at the frequency of 30 ㎑ revealed that eddy current was concentrated on both sides of edge, but almost cancelled out at the center. The Flux density induced by eddy current shows almost similar behavior. This can be interpreted that the eddy currents formed at each shell on center were cancelled out each other, while those on both sides of edge remain alive. A Weak leakage of fluxes was detected and it might act as EMI noise. Since the EMI noise can cause some errors on operation and increase the temperature of system, shield materials are useful to reduce leakage flux. The skin depth was calculated to be about 0.17 ㎜ from the equation of skin effect, while the penetration was totally achieved at the most outer and its neighboring shell on both sides of edge by simulation. Although the skin depth obtained from equation corresponds to 1/e of its real value, there was a little difference between simulation and calculation. It may be assumed that the relative permeability and electrical conductivity of a amorphous core would drastically reduce after molding.

고강도 저손실 가공송전선의 개발(II) - 전기적 특성

김병걸,김상수,박주환,Kim, Byung-Geol,Kim, Shang-Shu,Park, Joo-Hwan 한국전기전자재료학회 2005 전기전자재료학회논문지 Vol.18 No.12

New conductor is developed by using high strength nonmagnetic steel(NM) wire as the core of overhead conductor This conductor is called ACNR overhead conductor(Aluminum Conductor Nonmagnetic Steel Reinforced). Formed by the combination of aluminum alloy wire and high strength nonmagnetic steel wire, it has about the same weight and diameter as conventional ACSR overhead conductor. To enhance properties beneficial in an electrical and mechanical conductor during the Process of high strength nonmagnetic steel wire, we made a large number of improvements and modifications in the working process, aluminum cladded method, and other process. ACNR overhead conductor, we successfully developed, has mechanical and electrical properties as good as or even better than conventional galvanized wire. Microstructure of raw material NM wire was austenite and then deformed martensite after drawing process. Strength at room temperature is about $180kgf/mm^2\~200kgf/mm^2$. The conductivity at 0.78 mm thickness of Aluminum cladded M wire is about $7\%$ IACS higher than $20\%$IACS of HC wire used as core of commercial ACSR overhead conductor. The corrosion resistance is about 3 times higher than that of HC wire.