부록 / 제 3 회 ( 1986 학년도 ) 졸업생 졸업 논문 요약 : 한국 구비설화에 나타난 선악 연구

최상우 새얼어문학회 1987 새얼語文論集 Vol.3 No.-

Ti-6Al-4V 합금의 내부 미소결함에 따른 초음파 신호 특성 연구

최상우,이준현,--,-- 한국비파괴검사학회 2001 한국비파괴검사학회지 Vol.21 No.6

Ti합금은 고온환경에서 고강도가 요구되는 항공기의 엔진 부품등의 소재로 적용되고 있다. Ti합금은 이와 같이 기계적 성능이 우수함에도 불구하고 α상과 β상의 조성에 의한 두 상의 띠세 구조에 의한 초음파 산란으로 초음파를 이용한 비파괴 평가에서 피로균열 검출이 어려운 단점이 있다. 합금내의 결정립에서 산란되는 초음파 신호에 의하여 결함이 존재하지 않는 경우에도 산란 신호가 검출되는 결정립 산란 잡음 신호가 존재하며, 이들 결정립 산란 잡음신호는 합금내부에 존재하는 기공 및 불순물 등의 결함 검출을 어렵게 하는 요인이다. 본 연구에서는 Ti합금의 효율적인 초음파를 이용한 비파괴 평가의 적용을 위하여 Ti합금 시험편에 대하여 초음파 전파속도 측정 및 미세 드릴 가공에 의한 인공 결함의 검출능 평가 등을 수행하였다. Ti alloy is used for essential parts of aircraft for high temperature environment. Although Ti alloy has excellent performance in regard to mechanical properties, it is difficult to find fatigue cracks by nondestructive ultrasonic inspection due to its two-phase microstructure, which consists of hard alpha and beta phases. Sound energy reflected from microstructural features in the component produces a background inspection noise which is seen even when no defects are present. This noise can inhibit the detection of critical internal defects such as pores cracks or inclusions. To obtain fundamental data on ultrasonic inspection of Ti alloy, ultrasonic testing was performed using a specimen with small drill holes and ultrasonic wave propagation velocities were measured.

원자로 스터드 볼트의 비파괴 평가를 위한 초음파 Phased Array 기법 적용

최상우,이준현,박문호,박민수,조윤호 한국비파괴검사학회 2004 학술대회 논문집 Vol.- No.-

The stud bolt is one of crucial parts for safety of reactor vessels in nuclear power plants. Cracks initiation and propagation were reported in stud bolts using closure of reactor vessel and head. Stud bolts are inspected by ultrasonic technique during overhaul periodically for the prevention of stud bolt failure and radioactive leakage from nuclear reactor. In conventional ultrasonic testing for inspection of stud bolts, crack was detected by using shadow effect. It take too much time to inspect stud bolt by using conventional ultrasonic technique. In addition, there were numerous spurious signal reflected from every thread. In this study, the advanced ultrasonic phased array technique was introduced for inspect stud bolts. The phased array technique provide fast inspection and high detectability of defects. There are sector scanning and linear scanning method in phased array technique, and these scanning methods were applied to inspect stud bolt and detectability was investigated.

배관부 부식 및 결함 평가를 위한 레이저 유도 초음파 적용 기술

최상우,이준현,조윤호 한국비파괴검사학회 2004 학술대회 논문집 Vol.- No.-

There are many tube and pipe-line in nuclear power plant under high temperature and high pressure. Erosion and corrosion defects were expected on these tube and pipe-line by environmental and mechanical factors. These erosion and corrosion defects can evaluated by ultrasonic technique. In these study, Scanning Laser Source(SLS) technique was applied to detect defect and construct image. This technique also makes detection possible on rough and curved surfaces such as tube and pipe-line by scanning. Conventional ultrasonic scanning technique requires immersion of specimen or water jet for transferring ultrasonic wave between transducer and specimen. However, this SLS technique does not need contacting and couplant to generate surface wave and to get flaw images. Therefore, this SLS technique has several advantages, for complicated production inspection, non-contact, remote from specimen, and high resolution. In this study, SLS images were obtained with various conditions of generation laser ultrasound and receiving in order to enhance detectability of flaws on the tube. Stress corrosion cracks were produced on tube and imgaes of stress corrosion cracks were constructed by using SLS technique.

초음파 판파와 신경회로망 기법을 적용한 리벳홀 부위의 균열 크기 평가

최상우,이준현 한국비파괴검사학회 2001 한국비파괴검사학회지 Vol.21 No.4

리벳이음은 응력집중 등에 의한 피로균열 발생 가능성이 높은 구조특성을 가지므로 구조물의 안전성 확보를 위하여 비파괴 평가 방법에 의하여 리벳홀 주위 균열에 대한 평가가 요구되고 있다. 유도 초음파의 일종인 Lamb 파는 판형상의 구조물의 비파괴 평가에 적합하며, 신경회로망은 비파괴 평가 기술에서 결함의 크기 및 종류 인식에 관하여 가장 효율적인 기법으로 많은 연구자들에 의해 적용되어 왔다. 본 연구에서는 항공기의 스킨재료로 적용되는 A12024-T3판재에 대하여 유도초음파의 일종인 판파를 적용하여 리벳홀 주위 균열 신호를 검출하였으며, 또한 리벳홀주위의 균열의 크기 평가를 위하여 백프로퍼게이션 알고리즘을 적용한 신경회로망을 적용하였다. 이때, 초음파 트랜스듀서와 시험편 사이의 불균일 접촉에 의한 오차를 줄이기 위하여 초음파 파형에서 시간 및 주파수 성분의 특성을 추출하여 신경회로망에 적용하였다. 그리고 이들 판파신호에서 추출한 시간 및 주파수 성분의 특성은 균열 크기 결정에 유용하게 적용될 수 있음을 증명하였다. The rivet joint has typical structural feature that can be initiation site for the fatigue crack due to the combination of local stress concerntration around rievet hole and the moisture trapping. From a viewpoint of structural assurance, it is crucial to evaluate the size of crack around the rivet holes by appropriate nondestructive evaluation techniques. Lamb wave that is one of guided waves, offers a more efficient tool for nondestructive inspection of plates. The neural network that is considered to be the most suitables for pattern recognition has been used by researchers in NDE field to classify different types of flaw and flaw sizes. In this study, crack size evaluation around the rivet hole using the neural network based on the back-propagation algorithm has been carried out by extracking some features from the ultrasonic Lamb wave for A12024-T3 skin panel of aircraft. Special attention was paid to reduce the coupling effect between the transducer and the specimen by extracting some features related to time and frequency component data in ultrasonic waveform. It was demonstrated clearly that features extracted form the time and frequency domain data of Lamb wave signal were very useful to determine crack size initiated from rivet hole through neural network.

리폭시지나아제, 쿠니츠트립신인히비터, 7S 알파다시 서브유닛 단백질이 없으며 스타키오스 함량이 낮은 대립 노란콩 품종 ‘하영’

최상우,리사랏,이정환,오현수,김세영,정종일 한국육종학회 2022 한국육종학회지 Vol.54 No.2

Soybean [Glycine max (L.) Merr.] is an excellent source of protein, oil, carbohydrates, and many other bioactive ingredients. However,its raw mature seeds also contain several antinutritional components. The newly developed soybean cultivar ‘Hayoung’ has large yellow seedsand a low stachyose content, and is free of lipoxygenase, Kunitz trypsin inhibitor (KTI), and 7S α’-subunit proteins. ‘Hayoung’ was selectedfrom the population derived from a cross between the intermediate parent (F4-4) and the breeding line (15G1). It has purple flowers, tawnypubescence, a determinate growth habit, and light-yellow pods at maturity. The seed of the cultivar has a yellow hilum and yellow seedcoat color. The dry weight seed protein and oil content were 37.9 and 16.0%, respectively. The stachyose content was 3.1 g/kg, which wasmuch lower than 12.7 g/kg of the check cultivar, ‘Daewon’. ‘Hayoung’ has shown resistance to soybean necrosis, soybean mosaic virus,Cercospora leaf spot and blight, black root rot, pod and stem blight, and bacterial pustule. ‘Hayoung’ matured on 22 October with a plantheight of 56 cm and a 100-seed weight of 32.3 g. The average yield of the cultivar was 3.12 (Ton/ha), based on regional yield trials in2018 at four locations. ‘Hayoung’ has been registered as a soybean cultivar (registration number: 8625, registration date: June 08, 2021) bythe Korea Seed & Variety Service, Republic of Korea.

Development of Self-compensated Technique for Evaluation of Surface-breaking Crack by Using Laser Based Ultrasound

최상우,이준현,조윤호 한국비파괴검사학회 2005 한국비파괴검사학회지 Vol.25 No.3

It is required to evaluate nondestructively depth of surface-breaking cracks in structures. In this paper, the self-compensated technique by laser-based ultrasound is used to measure the depth of surface-breaking defect. Optical generation of ultrasound produces a well defined pulse with reliable frequency content. It is broad banded and suitable for measurement of attenuation and scattering over a wide frequency range. The self-calibrated signal transmission data of surface wave shows good sensitivity as a practical tool for assessment of surface-breaking defect depth. It is suggested that the relationship between the signal transmission and crack depth can be used to predict the surface-breaking crack depths in structures.

Silicone Metal CNT 복합체의 열적 기계적 특성

최상우,윤관한,이대열,정성실 한국고분자학회 2010 한국고분자학회 학술대회 연구논문 초록집 Vol.2010 No.4

Phased array 기법을 이용한 초음파 SH-wave 빔 조향에 관한 연구 ( A study on ultrasonic SH-wave beam steering using phased array technique )

최상우,이준현 대한기계학회 1998 대한기계학회 춘추학술대회 Vol.- No.-

고로 노체 냉각기구의 마모 진단을 위한 초음파 두께 측정 기술

최상우,유정열,최태화 제어로봇시스템학회 2010 제어로봇시스템학회 국내학술대회 논문집 Vol.2010 No.5

The blast furnace is used to smelt iron in the steel industry. Ore and cokes are input and hot air is blown into the chamber of the blast furnace. In the high temperature environment, the wear between the stave and the materials makes the cooling stave thinning during the downward of materials in the blast furnace. The thickness of the cooling stave should be aware in order to prevent leakage of coolant into the furnace chamber and to make actions before the failure. A novel ultrasonic transducer which can approach the cooling stave through the cooling line was developed to measure thickness of the worn cooling stave and the optimal measurement was proposed.