http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
복합산화물이 형성된 API X80 라인파이프강의 용접열영향부 샤르피 흡수에너지
성효경 ( Hyo Kyung Sung ),신상용 ( Sang Yong Shin ),차우열 ( Woo Yeol Cha ),오경식 ( Kyung Shik Oh ),이성학 ( Sung Hak Lee ),김낙준 ( Nack J. Kim ) 대한금속재료학회 ( 구 대한금속학회 ) 2010 대한금속·재료학회지 Vol.48 No.10
This study assessed the Charpy impact properties of the heat-affected zones (HAZs) of API X80 linepipe steels containing complex oxides. Three types of steel were fabricated by adding Mg and O2 to form complex oxides and their microstructures and Charpy impact properties were investigated. The number of complex oxides increased with the amount of excess Mg and O2 that was included in the steels. Simulated HAZs containing a number of oxides showed a high volume fraction of acicular ferrite (AF) because the oxides acted as nucleation sites for AF, thereby leading to an improvement in the Charpy impact properties. According to a correlation study between the heat input, the volume fraction of the AF, and the Charpy impact properties, ductile fractures occurred predominantly when the fraction of the AF was 20% or higher; moreover, the Charpy absorbed energy was excellent at more than 100 J. These findings suggest that the improvement of the Charpy impact properties of the HAZs was associated with the active nucleation of AF in the oxide-containing steel HAZs.
논문 : 베이나이트계 고강도강의 합금원소와 냉각조건이 미세조직, 인장성질, 충격성질에 미치는 영향
성효경 ( Hyo Kyung Sung ),신상용 ( Sang Yong Shin ),황병철 ( Byoung Chul Hwang ),이창길 ( Chang Gil Lee ),김낙준 ( Nack J. Kim ),이성학 ( Sung Hak Lee ) 대한금속재료학회 ( 구 대한금속학회 ) 2010 대한금속·재료학회지 Vol.48 No.9
The effects of alloying elements and the cooling condition on the microstructure, tensile properties, and Charpy impact properties of high-strength bainitic steel plates fabricated by a controlled rolling process were investigated in the present study. Eight kinds of steel plates were fabricated by varying C, Cr, and Nb additions under two different cooling rates, and their microstructures and tensile and Charpy impact properties were evaluated. The microstructures present in the steels increased in the order of granular bainite, acicular ferrite, bainitic ferrite, and martensite as the carbon equivalent or cooling rate increased, which resulted in a decrease in the ductility and Charpy absorbed energy. The steels containing a considerable amount of bainitic ferrite or martensite showed very high strengths, together with good ductility and Charpy absorbed energy. In order to achieve the best combination of strength, ductility, and Charpy absorbed energy, granular bainite and acicular ferrite were properly included in the high-strength bainitic steels by controlling the carbon equivalent and cooling rate, while about 50 vol.% of bainitic ferrite or martensite was maintained to maintain the high strength.
이성학 ( Sung Hak Lee ),이창길 ( Chang Gil Lee ),황병철 ( Byoung Chul Hwang ),김낙준 ( Nack J. Kim ),신상용 ( Sang Yong Shin ),성효경 ( Hyo Kyung Sung ) 대한금속재료학회 ( 구 대한금속학회 ) 2010 대한금속·재료학회지 Vol.48 No.7
This study is concerned with tensile and Charpy impact properties of high-strength bainitic steels fabricated by controlled rolling process. Six kinds of steels were fabricated by varying finish rolling temperature, start cooling temperature, and cooling rate, and their microstructures and tensile and Charpy impact properties were investigated. Their effective grain sizes were also characterized by the electron backscatter diffraction analysis. The microstructures of the steels rolled in the single phase region were most similar to those of the steels rolled in the two phase region. The steels cooled from 700℃ were composed mainly of granular bainites, while those cooled from 600℃ contained a number of bainitic ferrites, which resulted in the decrease in ductility and upper shelf energy in spite of the increase in strength. In the steels cooling from 600℃, fine acicular ferrites were well formed when the cooling rate was slow, which led to the best combination of high ductility, high upper shelf energy, and low energy transition temperature according to the decrease in the overall effective grain size due to the presence of acicular ferrites having smaller effective grain size.
김선종,구탁모,성효경,최흥문,Kim, Seon-Jong,Koo, Tak-Mo,Sung, Hyo-Kyung,Choi, Heung-Moon 대한전자공학회 1998 電子工學會論文誌, S Vol.s35 No.6
This paper proposes an efficient face recognition system using phase difference between the face images. We use a Karhunen-Loeve transform for image compression and reconstruction, and obtain the phase difference by using normalized inner product of the two compressed images. The proposed system is rotation and light-invariant due to using the normalized phase difference, and somewhat shift-invariant due to applying the cosine function. The faster recognition than the conventional system and incremental training is possible in the proposed system. Simulations are conducted on the ORL images of 40 persons, in which each person has 10 facial images, and the result shows that the faster recognition than conventional recognizer using convolution network under the same recognition error rate of 8% does. 본 논문에서는 얼굴 영상간의 위상 차를 이용하여 얼굴을 인식하는 시스템을 제안하였다. 제안된 시스템에서는 KLT(Karhunen-Loeve transform)를 이용하여 복구가 가능하도록 영상을 압축하고, 계산량도 줄였다. 압축된 학습 대상 영상을 미리 제안된 시스템에서 학습시킨 후, 인식 대상 얼굴 영상을 압축시킨다. 압축된 영상과 기존의 학습된 얼굴영상들과의 위상차를 구하고 이 위상차에 여현 함수를 적용하여 그 값이 최대가 되는 얼굴로 인식하도록 하였다. 두 얼굴 영상의 위상차는 벡터 내적방법에 의해 구하여지며, 이를 이용하면 기존의 학습방법을 이용하는 시스템보다 계산이 간단하고 처리시간도 빠르다. 또한 영상간 규준화된 위상차는 조명 및 회전에 불변인식이 가능하고, 여현 함수의 적용으로 이동에도 어느정도 불변인식이 가능하다. 그리고 연결웨이트에는 영상에 대한 정보를 그대로 갖고 있어서, 기존의 신경망과 같은 전체적인 재학습을 하지 않고도 새로운 영상만을 추가학습이 가능하므로 확장학습이 용이하다. 각각 10가지 얼굴영상을 갖는 40 명의 ORL 얼굴영상에 실험한 결과, 인식률이 기존의 방법과 비슷한 8% 오차범위 내에서 학습시간이 PC에서도 수 분밖에 안 걸리는 빠른 얼굴인식이 가능함을 확인하였다.
고속도강롤의 미세조직, 고온마모특성, 표면조도에 미치는 탄소, 텅스텐, 바나듐의 영향
하대진 ( Dae Jin Ha ),성효경 ( Hyo Kyung Sung ),박준욱 ( Joon Wook Park ),이성학 ( Sung Hak Lee ) 대한금속재료학회 ( 구 대한금속학회 ) 2009 대한금속·재료학회지 Vol.47 No.7
A study was conducted on the effects of carbon, tungsten, and vanadium on the wear properties and surface roughness of four High Speed Steel (HSS) rolls manufactured by the centrifugal casting method. Hot-rolling simulation tests were carried out using a high-temperature wear tester capable of controlling speed, load, and temperature. HSS rolls contained a large amount (up to 25 vol.%) of carbides such as MC, M2C, M7C3, and M6C carbides formed in the tempered martensite matrix. The matrix consisted mainly of lath tempered martensite when the carbon content in the matrix was small, and contained a considerable amount of plate tempered martensite when the carbon content increased. The high-temperature wear test results indicated that the wear properties and surface roughness of the rolls improved when the amount of hard MC carbides formed inside solidification cells increased. The rolls distribution was also homogeneous. The best wear properties and surface roughness were obtained from a roll where a large amount of MC carbides was homogeneously distributed in the lath tempered martensite matrix. The proper contents of carbon equivalent, tungsten equivalent, and vanadium were 2.0~2.3%, 9~10%, and 5~6%, respectively.
Nb 첨가 철계 합금의 Prior austenite 결정립크기 측정 방법
고광규,배효주,정신우,성효경,김정기,설재복,Ko, Kwang Kyu,Bae, Hyo Ju,Jung, Sin Woo,Sung, Hyo Kyung,Kim, Jung Gi,Seol, Jae Bok 한국분말재료학회 (*구 분말야금학회) 2021 한국분말재료학회지 (KPMI) Vol.28 No.4
High-strength low-alloy (HSLA) steels show excellent toughness when trace amounts of transition elements are added. In steels, prior austenite grain size (PAGS), which is often determined by the number of added elements, is a critical factor in determining the mechanical properties of the material. In this study, we used two etching methods to measure and compare the PAGS of specimens with bainitic HSLA steels having different Nb contents These two methods were nital etching and picric acid etching. Both methods confirmed that the sample with high Nb content exhibited smaller PAGS than its low Nb counterpart because of Nb's ability to hinder austenite recrystallization at high temperatures. Although both etching approaches are beneficial to PAGS estimation, the picric acid etching method has the advantage of enabling observation of the interface containing Nb precipitate. By contrast, the nital etching method has the advantage of a very short etching time (5 s) in determining the PAGS, with the picric acid etching method being considerably longer (5 h).
논문 : 페라이트계 스테인리스강의 열간압연 시 발생하는 Sticking 기구 연구
하대진 ( Dae Jin Ha ),성효경 ( Hyo Kyung Sung ),이성학 ( Sung Hak Lee ),이종석 ( Jong Seog Lee ),이용득 ( Yong Deuk Lee ) 대한금속재료학회 ( 구 대한금속학회 ) 2008 대한금속·재료학회지 Vol.46 No.11
Mechanisms of sticking phenomena occurring during hot rolling of a modified STS 430J1L ferritic stainless steel have been investigated in this study by using a pilot-plant-scale rolling machine. As the rolling pass proceeds, the Fe-Cr oxide layer formed in a reheating furnace is destroyed, and the destroyed oxides penetrate into the rolled steel to form a thin oxide layer on the surface region. The sticking does not occur on the surface region containing oxides, whereas it occurs on the surface region without oxides by the separation of the rolled steel at high temperatures. This indicates that the resistance to sticking increases by the increase in the surface hardness when a considerable amount of oxides are formed on the surface region, and that the sticking can be evaluated by the volume fraction and distribution of oxides formed on the surface region. The lubrication and the increase of the rolling speed and rolling temperature beneficially affect to the resistance to sticking because they accelerate the formation of oxides on the steel surface region. In order to prevent or minimize the sticking, thus, it is suggested to increase the thickness of the oxide layer formed in the reheating furnace and to homogeneously distribute oxides along the surface region by controlling the hot-rolling process.