Fe-Hf-N 박막의 미세조직과 자기적 특성에 관한 연구

맹기호,강계명 서울産業大學校 2005 논문집 Vol.54 No.1

The electronic components with high functionality and high integration have been successfully developed by virtue of thin film and grain refinement techniques, allowing industrial devices to be high-functionalized and miniaturized. Considering a strong demand for high-speed transmission and high-density storage of data by further miniaturization and high frequency operation, the control of the soft magnetic properties in the components is strongly required. It has been reported that thin film technique in the fabrication processing of the soft magnetic materials makes the miniaturization of the components possible, because thin film device shows an excellent magnetic properties. In this research, to suggest an optimal condition for fabrication of the magnetic thin film with excellent magnetic properties, microstructural characteristics and properties of the Fe-Hf-N thin film are analyzed. The amorphous thin films of Fe-Hf with different composition of Hf are prepared by a RF magnetron sputtering method. To synthesize crystalline thin films of Fe-Hf-N, as-deposited Fe-Hf films are heat-treated at 550°C under a nitrogen atmosphere. The microstructure of thin films is observed by the transmission electron microscopy, and the relationship between microstructure and magnetic properties is analyzed.

Austenite계 SUS 강의 피로강도에 미치는 결정입도의 영향

박은수,강계명 서울産業大學校 1994 논문집 Vol.40 No.1

The effect of grain size on the characteristics of fatigue of Austenitic SUS 316 steel was examined. Especially, under the variations of loads and the overloads/underloads, the behavior of crack propagation on those fatigue strengths was investigated by using bending fatigue tester. The experimental results showed that the fatigue strength was decreased with increasing its grain size and the rate of crack propagation was closely related to the grain size. The smaller grain size the specimen had, the slower rate of crack propagation it appeared. It has been thought that the characteristics of fatigue strength with the variation of grain size resulted from the phenomena of acceleration or deceleration of crack propagation rate.

배관망 해석 방법을 이용한 스프링클러 시스템의 수리계산 프로그램 개발

송철강,이명호,강계명 한국화재소방학회 2002 한국화재소방학회논문지 Vol.16 No.1

본 연구는 배관에서의 정확한 압력손실과 유량을 측정하기 위하여 스프링클러 시스템중 격자배관방식에 대한 수리계산 프로그램을 개발하는데 그 목적이 있다. 본 프로그램 개발은 배관망 해석방법 등 여러 가지 자료로 근거하며, 격자배관방식이 국내에서 현행 시행되고 있는 규약배관방식의 단점을 보안하여 스프링클러 시스템을 성능기준화재안전설계로 이끌어 내기 위함이다. 소화설비의 전산화로 인한 작업의 편리성과 정확한 계산을 측정함으로서 전진적인 화재안전설계를 이룩하게 될 것이다. 이러한 프로그램의 개발은 미국 등에서 먼저 이루어져 오고 있으며 국내에서의 소방에 대한 발전이 한 단계 발전되는 계기를 마련하게 될 것이다. The purpose of this study is developing the computer program for hydraulic design sprinkler systems have performed the means for the general use of network analysis method. The computer program is based on the theoretical concept of the related Hazen-Williams equations, a modified Bernoulli equations, and the Hardy Cross method of pipe network analysis. Looped piping calculations are solved by using either the Hardy Cross method or the other iteration methods. While the other methods are solved using simultaneous equations, the Hardy Cross method is concerned with one loop at a time using reiterative process. Due to its simplicity the Hardy Cross method will be the primary method described in this thesis. The purpose of this study is to develope hydraulic calculation program by using algorithm for network analysis method. The development of computer program for the hydraulic design of sprinkler systems will perform the means in the performance-based sprinkler system design.

Laser- Plume Effects on Radiation Energy Transfer in Materials Processing

Kang, Kae-Myung,Kim, Kwang-Ryul Materials Research Society of Korea 2002 한국재료학회지 Vol.12 No.1

In laser materials processing, localized heating, melting and evaporation caused by focused laser radiation forms a vapor on the material surface. The plume is generally an unstable entity, fluctuating according to its own dynamics. The beam is refracted and absorbed as it traverses the plume, thus modifying its power density on the surface of the condensed phases. This modifies material evaporation and optical properties of the plume. A laser-produced plasma plume simulation is completed using axisymmetric, high-temperature gas dynamic model including the laser radiation power absorption, refraction, and reflection. The physical properties and velocity profiles are verified using the published experimental and numerical results. The simulation results provide the effect of plasma plume fluctuations on the laser power density and quantitative beam radius changes on the material surface. It is proved that beam absorption, reflection and defocusing effects through the plume are essential to obtain appropriate mathematical simulation results. It is also found that absorption of the beam in the plume has much less direct effect on the beam power density at the material surface than defocusing does and helium gas is more efficient in reducing the beam refraction and absorption effect compared to argon gas for common laser materials processing.

590MPa급 DP강 표면층의 미소경도와 조직특성에 미치는 수소주입의 영향

강계명(Kae Myung Kang),박재우(Jae-Woo Park) 한국가스학회 2010 한국가스학회 학술대회논문집 Vol.2010 No.5

Design and Construction of Ceramic Filters Utilizing Harmonic Modes of Energy-Trapped Thickness Extentional Vibration

Lee, Kae-Myung,Kim, Kyu-Su,Park, Chang-Yub 연세대학교 산업기술연구소 1991 논문집 Vol.23 No.2

The ceramic filter utilizing the third harmonic extentional vibration mode of a PMN-PZT ceramic substrate was designed and fabricated, and its frequency characteristics were measured. Designing was carried out by analyzing one dimensional distributed constant circuit. From comparing the measured characteristics with the calculated values, the error was obtained to be compensated in designing ceramic filters

음극전기분해법을 이용한 수소주입 및 수소취성평가

강계명(Kae Myung Kang),박재우(Jae-Woo Park) 한국가스학회 2011 한국가스학회 학술대회논문집 Vol.2011 No.5

어닐링처리시킨 SnO₂ 가스센서의 박막성장특성

강계명(Kae-Myung Kang),최종운(Jong-Un Choi) 한국표면공학회 2007 한국표면공학회지 Vol.40 No.6

Relationships between the electrical resistivity and the growth characteristic of SnO₂ thin films were investigated. SnO₂ thin films with thickness from 64 ㎚ to 91 ㎚ were made by controlling the RF deposition energy from 80 to 150 W. These SnO₂ thin films were annealed at 200℃~700℃ temperature range of 100℃ interval in the O₂ gas condition. After annealing treatments, the microstructures of the SnO₂ thin films were changed mixed structure(amorphous & crystalline) to lamina columnar crystalline structure. Both the film thickness and the grain size were increased with increasing the local crystallization of SnO₂ microstructure of thin films by annealing treatment. Their electrical resistivity increased up to the annealing temperature of 400℃, and then slowly decreased.

수소주입시킨 다상조직강의 Subsurface Zone 내 취성화 거동

강계명(Kae-Myung Kang),박재우(Jae-Woo Park),최종운(Jong-Un Choi) 한국표면공학회 2013 한국표면공학회지 Vol.46 No.1

In the present work, it was investigated a behavior of hydrogen embrittlement at the subsurface zones of 590 DP steels by using the micro-Vickers hardness test. The micro-Vickers hardnessess of DP steels were measured to evaluate the degree of embrittlement as the effective hardening depths of subsurface zones with hydrogen charging conditions. The results showed that the distributions of micro-Vickers hardness in width varied from maximum hardness 239.5 Hv to minimum hardness 174 Hv, while the depth of effective hardening layer at the subsurface zones of DP steels was from 320 ㎛ to 460 ㎛ with hydrogen charging conditions, respectively. It was proposed that the distribution of microhardness be used as the evaluation index of the degree of embrittlement. But the variations of martensite volume fractions were not affected along depth of hardening at the same changing time, hydrogen charging times were appeared as an effective factor of the degree of embrittlement. Therefore, the micro-Vickers hardness test is an attractive tool for evaluation of hydrogen embrittlement at the subsurface zones of these DP steels.

친환경 도금표면처리 기술동향

강계명(Kae-Myung Kang),김유상(Yu-Sang Kim) 한국표면공학회 2009 한국표면공학회지 Vol.42 No.6

Recently, it has been increasing for the eco-environment plating and surface treatment of eco-environment to decrease hazardous materials. Particular eco-environment can be applied to electronics or automotive parts of industry. In the case of mobile phone, if there were fired, the products bearing dye may be contaminated with the hazardous and wasted. we can obtain the original metal color by electro coloring by metal salt, get rid of hazardous gas, decrease the wasted sludges. Now, the industrial patent number is increasing in Korea, we can accomplish the development of green industry by supporting technical trend of the plating and surface treatment in eco-environment.