고속전철 Rail 강의 기계적 성질에 미치는 Ti V 첨가원소의 영향

박치승,박재성,송진태 대한금속재료학회 1982 대한금속재료학회 학술대회 개요집 Vol.1982 No.1

고속전철용 합금강 (合金鋼) Rail 재의 내마모성에 (耐磨耗性) 관한 연구

박치승,송진태,고석수 대한금속재료학회 1983 대한금속재료학회 학술대회 개요집 Vol.1983 No.0

비파괴 검사용 초음파 탐촉자에서의 정합층 최적 설계법

박치승,김선진,Park, Chi-seung,Kim, Seon-Jin 한국재료학회 2003 한국재료학회지 Vol.13 No.10

In this study, we have tried to find the optimized design variables of the matching layer which is important part of thickness mode ultrasonic transducer and finally reach the conclusion that the electrical property of piezo-element must be under consideration when the optimized acoustic impedance is estimated. Proper expression of the effective impedance of front load at free resonant frequency(: $Z_{f}$ $^{(0)}$ /) has been induced by introducing the principle of binomial multilayer transformer and gradient based numerical method is utilized to find the most acceptable value of $Z_{ f}$/$^{(0)}$ . Optimized point of acoustic impedance can be calculated directly from $Z_{f}$ $^{(0)}$ using some simple formula which we propose. We also verify our result by both numerical and experimental method and get a good enhancement especially it concern to the bandwidth of ultrasonic transducer.

공간주파수대역에서 기저대역 확장을 통한 원전 대비시험편과 대비 보정 시험편의 초음파 영상 개선

박치승,김선진,Park, Chi-Seung,Kim, Seon-Jin 한국재료학회 2003 한국재료학회지 Vol.13 No.10

Ultrasonic microscope has been used to detect the defects on surface or inner solid. Conventionally, it has used at a single operating frequency. The resolution and quality of the measured images are determined by a characteristic of the transducer of the ultrasonic microscope. The conventional ultrasonic microscope has been used envelope detector to detect the amplitude of reflected signal, but the changes in amplitude is not sensitive enough for specimen with microstructure that in phase. In this paper, we have studied multi-frequency depth resolution enhancement with ultrasonic reflection microscope for the reflectors of a stainless steel reference specimen and a reference calibration block to be used as the material in nuclear power plants for ISI, PSI. Increased depth resolution can be obtained by taking two, three-dimensional images at more that one frequency and numerically combining the results. As results of the experiment, we could get enhanced images with the rate of contrast in proportion and high quality signal distribution for the image to the changing rate of depth for the reflectors of the two kinds of specimens.

원자력 압력용기의 피복하부 결함검출에 대한 고찰

박광희,박종현,안희성,박치승 韓國非破壞檢査學會 1989 한국비파괴검사학회지 Vol.9 No.2

It has not been performed to inspect the underclad cracking in Korea nuclear plant since there is no Code Requirments for inspection. However, underclad cracks in nuclear pressure vessels were reported firstly in 1970. The objection of this study is to be established the ultrasonic inspection techniques for underclad cracking. The ultrasonic inspection of bimetalic stainless steel weld is very difficult by high attenuation and multiple scattering at weld surface and weld/base metal interface. The various inspection methods using 70。 refracted longitudinal wave. 50/70 tandem transducer, 45。 and 60。single shear wave are compared. Experiments on limited specimens applied same condition to nuclear pressure vessels shows that 70。refracted longitudinal wave method is the best one for the detection of underclad cracks. 50/70 tandem transducer using SPOT(Satellite Pulse Observation Technique) is more effective for underclad crack sizing than other sizing methods.

원자력 압력용기의 피복하부 결함검출에 대한 고찰(Ⅱ)

박치승,강지원 한국비파괴검사학회 1993 한국비파괴검사학회지 Vol.13 No.2

국내 원자력 압력 용기의 피복하부 결함에 대한 검사는 1970년대 초부터 이 피복하부 결함에 대한 보고가 되기 시작하였으나 적용 규격은 ASME Code의 요구사항이 아니므로 현재까지는 검사를 수행해 오지 않고 있다. 본 실험의 목적은 이러한 피복하부 결함을 검출하는데 적절한 초음파검사 방법을 조건을 찾는 것이다. 실험은 70。굴절종파, 50/70 multibeam탐촉자, SLIC-50 탐촉자 등을 사용하여 원자력 압력용기의 피복용접과 같은 조건하에서 피복용접 시킨 초음파보정 시험편과 demonstration시험편에 대하여 수행하였다. 실험 결과 피복하부 결함의 검출은 50/70 multibeam탐촉자가 효과적이었으며, 피복하부 결함의 길이 평가는 70。굴절종파로 수행하는 것이 바람직한 것으로 나타났으며, 반면에 피복하부 결함의 깊이 측정은 SLIC-50 탐촉자를 이용하여 M-SPOT 방법과 M-PET 방법으로 평가하는 것이 가장 효과적인 것으로 사료된다. It has not been performed to inspect the underclad cracking of nuclear pressure vessel in Korea since there is no code requirements for inspection. However, underclad cracks in nuclear pressure vessels have been reported since the early 1970s. The aim of this experiment is to find the suitable ultrasonic inspection techniques for underclad cracking. The various transducers, for example 70, refracted longitudinal wave, 50/70 multibeam, SLIC-40, SLIC-50, are used in this investigation. Experiments on prescreening blocks and a demonstration block under the same condition as in the nuclear power pressure vessels show that the 70, refracted longitudinal wave method is the best on for the length evaluation and also gives a good signal pattern for detection of the crack, while the 50/70 multibeam transducer is more effective for the detection of underclad cracking. On the other hand, the SLIC-50 transducer using M-SPOT(Satellite Pulse Observation Technique) and M-PET (Peak-Echo Technique) methods is the most effective on for the depth of underclad crack estimation.

컴퓨터제어에 의한 자동초음파 탐상장치에 관한 연구

허형,박치승,홍순신,박종현 韓國非破壞檢査學會 1989 한국비파괴검사학회지 Vol.9 No.1

Since the nuclear power plants in Korea have been operated in 1979, the nondestructive testing(NDT) of pressure vessels and/or piping welds plays an important role for maintaining the safety and integrity of the plants. Ultrasonic method is superior to the other NDT method in the viewpoint of the detectability of small flaw and accuracy to determine the locations, sizes, orientations, and shapes. As the service time of the nuclear power plants is increased, the radiation level from the components is getting higher. In order to get more quantitative and reliable results and secure the inspector from the exposure to high radiation level, automation of the ultrasonic equipments has been one of the important research and development(R & D) subject. In this research, it was attempted to visualize the shape of flaws presented inside the specimen using a Modified C-Scan technique. In order to develope Modified C-Scan technique, an automatic ultrasonic scanner and a module to control the scanner were designed and fabricated. IBM-PC/XT was interfaced to the module to control the scanner. Analog signals from the SONIC MARK II were digitized by Analog-Digital Converter(ADC 0800) for Modified C-Scan display. A computer program has been developed and has capability of automatic data acquisition and processing from the digital data, which consist of maximum amplitudes in each gate range and location. The data from Modified C-Scan results was compared with shape from artificial defects using the developed system. Focal length of focused transducer was measured. The automatic ultrasonic equipment developed through this study is essential for more accurate, reliable, and repeatable ultrasonic experiments. If the scanner are modified to meet to appropriate purpose, it can be applied to automation of ultrasonic examination of nuclear power plants and helpful to the research on ultrasonic characterization of the materials.

기계 합금화한 AI-Ti합금의 열적 안정성에 미치는 V첨가의 영향

오준영,박치승,김선진,O, Jun-Yeong,Park, Chi-Seung,Kim, Seon-Jin 한국재료학회 1994 한국재료학회지 Vol.4 No.4

AI-Ti합금의 열적 안정성에 미치는 V첨가의 영향에 대하여 조사하였다. AI-8wt.%Ti 분말과 Ti과 V의 원자비를 3:1, 1:1로 달리한 AI-8wt.%(Ti+V)분말을 기계적 합금화 방법으로 준비하였으며 16시간의 기계적 합금화 후 모든 조성에 대해 정상상태의 혼합 분말을 얻을 수 있었다. 기계적 합금화한 분말은 진공열간압축하여 성형하였다. 열적 안정성을 평가하기 위하여 $400^{\circ}C$, $480^{\circ}C$, $550^{\circ}C$에서 최고 1000시간까지 등온열처리후 경도시험을 행하였다. AI-Ti합금에 V을 첨가함으로써 $Ai_{3}Ti$의 조대화가 억제되어 열적 안정성이 증가하였음을 확인하였다. The effect of vanadium additions on the thermal stability of Al-TI alloy \vas investigated. Al- 8wt.%Ti and Al-8wt.%(Ti+V) alloys wirh different Ti to V atomic ratios of 3 : 1 and 1 : 1 were pre- pared by mechanical alloying. The steady states wwe obtalncd after mechanical alloy~ng for ltihours for all the alloy compositions. The mechanically alloyed powders were consolidaicd by vacuum hot pressing and thermal st.ability was investigated by hardness testing afrcr aging thc specimens at $400^{\circ}C$, $480^{\circ}C$, $550^{\circ}C$ for up to 1000hrs. It was confirmed that addit~on of V- increased the thermal stability of Al-Ti alloy by reducing coarsening rate of $Ai_{3}Ti$ intermetallic compound.

Al材料에서 Ultrasonic Backscattered Energy와 Stress와의 相互關係

朴宗賢,朴致承,林亨澤 韓國非破壞檢査學會 1987 한국비파괴검사학회지 Vol.6 No.2

As a new device of stress monitoring method, ultrasonic backscattering method has been used to aluminium samples with various grain sizes at rayleigh critical angle in order to observe the relationships between applied stress and ultrasonic backscattered energy. It was found that the ultrasonic backscattered energy was observed to decrease as the grain size increased at the given applied stress. At the same grain size, the ule ultrasonic backscattered energy increased with increasing the applies stress. Through this study, we provided some possibility to evaluate stresses in materials under loads nonderstructively, and this method is expected to be used as a new stress monitoring device.

고탄소계합금강 Rail 재의 개발에 관한 기초연구

송진태,박치승 대한금속재료학회(대한금속학회) 1983 대한금속·재료학회지 Vol.21 No.10

High carbon Cr-V and Cr-Ti alloy steels based on 0.75%-0.76% C were manufactured for trial and their mechanical properties and microstructures were investigated metallographically, and then studied on the fitness of these alloy steels as the rail materials for high speed railroad. According to experimental results, their tensile strength, yield strength, and hardness were 120-130㎏/㎟, 85-90㎏/㎟, 350-370 H_B respectively, and the amount of wear was half as much as normal carbon rail steels', but their microstructures were largely different from each other. It was concluded that high carbon Cr-V and Cr-Ti alloy steels appear to have mechanical properties suitable for rail materials of high speed railroad, and good properties such as high strength and hardness of the high carbon Cr-V steel will be attributed to its fine pearlite microstructure which were distributed densely.