316 스테인리스강의 입계부식에 미치는 열사이클과 응력의 영향

정병호,김무길,Jung, Byong-Ho,Kim, Moo-Gil 한국마린엔지니어링학회 2006 한국마린엔지니어링학회지 Vol.30 No.6

The effects of thermal cycle condition and applied stress on the intergranular corrosion in austenitic 316 type stainless steels were investigated. Specimens were solution-treated at 1100$^{\circ}C$ for one hour and then sensitized in the temperature range of $500{\sim}800^{\circ}C$ by holding $2{\sim}300s$ with a various applied stresses of $0{\sim}8kg/mm^2$. Degree of sensitization. DOS %, was measured through polarization curve by electrochemical DL-EPR test. Microstructural observations were also conducted DOS % increased with an increase of sensitization temperature and/or holding time. Increase of applied stress resulted in increase of DOS % and more corroded surface because of acceleration of intergranular corrosion and fine grain size due to the stress. Cr depleted zone near grain boundary was observed. The amount of depletion was profounded with an increase of sensitization temperature, holding time and applied stress. $M_{23}C_6$ carbides were precipitated discontinuously at grain boundary. However, its amount was relatively small in the thermal cycle condition of 800$^{\circ}C$, 300sec and 4kg/mm$^2$.

ER2594 용착금속의 전기화학적 부식특성에 미치는 시그마상의 영향

정병호(Byong-Ho Jung),김시영(Si-Young Kim),서기정(Gi-Jeong Seo),박주영(Joo-Young Park) 한국동력기계공학회 2015 동력시스템공학회지 Vol.19 No.6

A deposited metal specimen of ER2594 which is a super duplex steel welding wire used to investigate the effect of sigma(σ) phase on electrochemical corrosion characteristics was prepared by gas tungsten arc welding. Aging treatment was conducted for the specimen at the temperature range of 700°C to 900°C for 5 to 300 minutes after annealing at 1050℃. Corrosion current density has decreased a little with an increase of aging time over 60 minutes at 700℃ to 900℃ and the uniform corrosion of deposited metal had more influence on the precipitation of ferrite than the precipitation of sigma phase. Therefore, the precipitation of sigma phase did not have much effect on the uniform corrosion. Pitting potential representing pitting corrosion has shown decreasing tendency as the precipitation of sigma phase increased. The degree of sensitization representing intergranular corrosion has shown increasing tendency as the precipitation of sigma phase increased at 700℃ to 800℃, while it has decreased at 900℃ for 60 to 300 minutes.

429EM 강의 내식성에 미치는 결정립 크기의 영향

정병호 ( Byong Ho Jung ),안용식 ( Yong Sik Ahn ) 한국열처리공학회 2010 熱處理工學會誌 Vol.23 No.2

적외선 카메라를 이용한 웹 서비스 기반 원격 트래킹 방범 시스템의 설계 및 구현

정병호 ( Chung Byong Ho ),곽노정 ( Kwak No Jung ),김영만 ( Kim Young Man ) 한국정보처리학회 2008 한국정보처리학회 학술대회논문집 Vol.15 No.1

범죄 예방과 자원 보호를 위해 CCTV 카메라를 이용하는 방범 시스템의 필요성은 점차 커지고 있다. 아날로그 형식에서부터 디지털 형식으로 발전된 형태의 방범 시스템이 개발되고 사용 중이지만, 비용이 높고 효율성이 떨어지는 문제가 있다. 본 논문에서는 웹 서비스 기반의 서버에 적외선 카메라를 연결하고 사용자가 사전 인지 없이도 클라이언트에서 실시간으로 침입을 탐지하여 적절하게 대처할 수 있는 방범 시스템을 설계하고 구현한다.

슈퍼듀플렉스 스테인리스강의 TIG 용접에서 질소 침투 모델에 관한 연구

이재형,정병호,조상명,전재호,Lee, Jae-Hyoung,Jung, Byong-Ho,Cho, Sang-Myung,Jun, Jae-Ho 대한용접접합학회 2015 대한용접·접합학회지 Vol.33 No.3

Superduplex stainless steels are important materials to the oil and gas industry, especially for off-shore production. TIG welding of super duplex stainless steels to obtain the optimal phase balance between austenite and ferrite is mainly achieved by controlling the cooling rate and the weld chemistry. The latter depends on the filler wire chosen and the shielding gas used. If TIG welding of superduplex stainless steels is performed with argon shielding gas only, then nitrogen gets lost from the weld pool, which can result in a ferrite-rich weld metal, with an inferior corrosion resistance than parent metal. In the present study, nitrogen permeation model from the shield gas which gets into the weld metal in DCEN-TIG welding has suggested. This plasma stream model shows characteristics of permeation of nitrogen ions into the molten metal due to the strong physical effect of plasma stream which formed by the arc pressure rather than the permeation of nitrogen ions caused by electric effect.

DCSP-GTAW에 의한 고력 Al합금의 고온균열감수성에 대한 연구

하려선,정병호,박화순,Ha Ryeo-Sun,Jung Byong-Ho,Park Hwa-Soon 대한용접접합학회 2004 대한용접·접합학회지 Vol.22 No.5

The tendency and degree of hot cracking of high strength 5083, 6N01 and 7N01 Al alloy welds by using DCSP-GTAW through modified Varestraint test and autogenous butt welding were investigated. In hot cracking test, 6N01 alloy showed the highest susceptibility to hot cracking in the weld metal and HAZ. Cracking susceptibilities generally increased with increase of solidification temperature range of the base metal and bead penetration-to-width ratio of the weld metal. The cracks in welds of the alloys vertically formed to solid-liquid interface and propagated along with columnar grain boundaries. The fracture facets of cracks showed the typical morphology of solidification crack observed as dendritic structures. Especially, in 6N01 alloy, liquation cracks which were due to elements of Si, Fe and Mg also observed in HAZ near fusion boundary. In butt welding of different Al alloys, the bead crack was mainly occurred in the welds of 6N01, 7N01 and other Al alloys together with 6N01 or 7N01. In the butt welds of 7N01, it was found that the component of Cu had an effect on the higher susceptibility to the hot cracking.

진공침탄을 위한 처리조건 설정에 관한 연구

이상길,강순배,정병호,김한군 ( Sung Gill Lee,Sun Bae Kang,Byong Ho Jung,Han Goon Kim ) 한국열처리공학회 1992 熱處理工學會誌 Vol.5 No.4

SCM 415 has been vacuum carburized in the carburizing pressure of 60-65kpa and the carburizing temperature of 1233k and 1273k after varied to 0-20 in the ratio of N₂/C₃H_8 and then diffusion treated for various times at 1123k. The results obtained from the experiment are as follows. 1. With increasing from 0 to 20 in ratio of N₂/C₃H_8 the sooting formation of surface after carburizing considerably decreased. 2. The hardness control and surface carbon content of carburizing surface has been modified by the addition of nitrogen to the propan. 3. The appoximate value of k is indirectry calculated at 1123k which results are obtained to 0.58×10^(-2)(wt.%.s^(-1/2)). 4. A great deal of propan by addition of nitrogen gas in carburizing gas was possible to saving without considerable change in case hardening depth. 5. The effective carburizing depth range is obtained to 0.8-1.1㎜ by diffusion temperature of 1123k after carburization at 1273k-3.6ks, and the surface hardness is increased as the increasing of T_D/T_C in our experimental condition, and the maximum hardness as reachin distance from surface is decreased.

진공침탄 열처리 기술개발에 관한 연구

이상길,강순배,정병호,김한군 ( Sang Gil Lee,Sun Bae Kang,Byong Ho Jung,Han Goon Kim ) 한국열처리공학회 1990 熱處理工學會誌 Vol.3 No.3

SCM 21 and D.P steel were carburized in vacuum using prophane at a temperature ranging from 1228k to 1308k under a gas pressure ranging from 21.3kpa to 61.8kpa, and the following results were obrained. 1) D.P. steel has considerable efficiency in depressing the grain growth during the high temperature carburizing and it has fine structure even at 1268k for 14.4ks when carburizied. Therefore this steel is expected to be suitable for vacuum carburizing at a high temperature. 2) Case depth was increased as the carburizing temperature increases and it was 3.2㎜ at max, temperature of 1308k, for max, time of 14.4ks and under max, pressure of 61.8kpa. Thus vacuum-carburizing was considered effective for the materials which need case depth, which is necessary for machine structure use. 3) The rate of case depth of SCM 21 was faster than D.P. steel under same carburizing conditions and the increasing rate of the case depth was constant. 4) Case depth was increased as the gas pressure becomes high under same carburizing temperature. 5) Case carbon concentration, C_s, of SCM 21 obeys to a formula, C_s=kt^½+C_0 Where k is 2.15×10^(-2)(wt%.S^(-1/2)) and this value is a little bit lower than that of SNCM 815.

Inconel 718 선재의 경도에 미치는 냉간신선가공의영향

정용권,조창용,정병호,김인배,Jeong, Yong-Kwon,Jo, Chang-Yong,Jung, Byong-Ho,Kim, In-Bae 한국재료학회 1998 한국재료학회지 Vol.8 No.4

Inconel 719 선재의 경도에 미치는 냉간신선가공량과 시효시간의 영향을 경도측정과 전자현미경을 사용하여 조사하였다. 고용화처리된 재료의 경도는 245Hzv이었으나 50% 냉간신선가공으로 450Hv까지 증가했다. 경도값은 시효시간이 증가함에 따라 초기에 증가하다 감소하는 것으로 나타났으며, 시효 초기 경도증가는 $\gamma^{"}$과 $\gamma^{'}$ 상의 석출에 의한 것이며, 최고경도 이후의 경도감소는$\gamma^{'}$상이 $\delta$상으로 변태되었기 때문이다. 냉간가공도가 증가함에 따라 최고경도에 이르는 시간은 감소되어 0, 30, 50%가공재들에 대해 각각 30, 10, 5분으로 나타났다. 이는 냉간가공으로 인해 $\gamma^{'}$ / $\gamma^{'}$ 상의 석출이 촉진되었기 때문이다. 50%가공재의 경우 1116K에서 5분 시효로$\Upsilon^{'}$ 및 $\Upsilon^{'}$상들이 석출되었다. 또한 50%가공재에서는 초기경도 이하로 경도값이 감소되었는데, 이와 같은 경도값의 큰 감소는 재결정이 일어났기 때문이다. Effect of cold drawing ratio and aging time on the hardness of lnconel 718 wire aged at 11l6K were investi￢gated by hardness measurement and scanning & transmission electron microscopy. Hardness which was 245Hv in as￢solution treated condition increased very rapidly to 450Hv as cold drawing ratio increased to 50%. The hardness in the early stage of aging was increased by the precipitation of $\gamma^{'}$ and $\gamma^{'}$ phases and after the peak hardness, the hardness was decreased by the transformation of $\gamma^{'}$ phase to $\delta$ phase. The time to reach peak hardness during aging appeared to be reduced with the increase of cold drawing ratio, and those times were 30, 10, and 5 minutes for 0, 30 and 50% cold drawn materials, respectively. For the 50% cold drawn material. $\gamma^{'}$ and $\gamma^{'}$ were precipitated by aging for 5 minutes at 1116K. The hardness in the same material was largely decreased under the initial hardness by the recrystallization.

지하수 관정개발 기초조사사업 업무지원을 위한 Desktop GIS와 2D 지하수 모델 WHPA 통합 연구

김만규 ( Kim Man-kyu ),정병호 ( Jung Byong-ho ),임창영 ( Lim Chang-young ),박종철 ( Park Jong-cheol ) 한국농공학회 2002 한국농공학회 학술대회초록집 Vol.2002 No.-

이 연구는 지하수개발사업 타당성 분석을 지원하기 위한 Desk GIS에 기반한 지하수사업기초조사지원 시스템을 개발하는 것이 목적이다. 개발된 시스템을 이용하면, 신규 개발 예정관정에 대하여 GIS안에서 모의 양수실험을 할 수 있으며, 기설관정의 채수영향반 경과의 중첩여부, 오염원 등과 비교하여 지하수관정개발사업의 허가여부를 판단할 수 있다. 농업기반공사 등 지하수 관련 부서들이 전사적으로 지하수 관련자료를 공유할 수 있으며, 자료의 정확성, 신뢰성 그리고 최신정보를 공유할 수 있을 것이다. This study develops a GIS-based system which examines the adequacy of the Groundwater development project before the actual designing of the project. Using the system developed here, we can transfer simulation results obtained by WHPA regarding Groundwater levels in new development projects into GIS. We can also judge whether a Groundwater development project should be permitted through examining overlaps of the effects of the development and comparing with other pollutants. Since a two-tiered system which shares DB using inter- and intranets is developed, all the departments in the ministry of agriculture and forest and the agriculture base corporation can share accurate, reliable and latest information related to Groundwater.