원자력발전소 주조 배관 용접부 위상배열 초음파검사 기술 개발

윤병식,양승한,김용식,Yoon, Byungsik,Yang, Seunghan,Kim, Yongsik 한국압력기기공학회 2010 한국압력기기공학회 논문집 Vol.6 No.1

Cast austenitic stainless steel(CASS) is used in the primary cooling piping system of nuclear power plant for it's relative low cost, corrosion resistance and easy of welding. However, the coarse-grain structure of cast austenitic stainless steel can strongly affect the inspectability of ultrasonic testing. The major problems encountered during inspection are beam skewing, high attenuation and high background noise of CASS component. So far, the best inspection performance involving CASS components have been achieved using low frequency TRL(Transmitter/Receiver side-by-side L wave) angle beam probe. But TRL technique could not detect shallow defect and it contains an uncertainty for sizing capability. Currently, most of researchers are studying to overcome these challenge issue. In this study, low-frequency phased array TRL technique used to detect and sizing the flaws in CF8A cast austenitic stainless steel.As conclusion, we could detect and size not only axial flaw but also circumferential flaw using low frequency phased array technique.

원자력발전소 배관 내부 매질이 초음파검사에 미치는 영향 평가

윤병식,김용식,양승한,Yoon, Byung Sik,Kim, Yong Sik,Yang, Seung Han 한국압력기기공학회 2013 한국압력기기공학회 논문집 Vol.9 No.1

The periodic inspection of piping and pressure vessels welds in nuclear power plant has to provide reliable result related to weld flaws, such as location, maximum amplitude response, ultrasonic length, height and finally the nature or flaw pattern. The founded flaw in ultrasonic inspection is accepted or rejected based on these data. Specially, the amplitude of flaw response is used as basic parameter for flaw sizing and it may cause some deviation in length sizing result. Currently the ultrasonic inspections in nuclear power plant components are performed by specific inspection procedure which describing inspection technique include inspection system, calibration methodology and flaw characterizing. To perform ultrasonic inspection during in-service inspection, reference gain should be established before starting ultrasonic inspection by the requirement of ASME code. This reference gain used as basic criteria to evaluate flaw sizing. Sometimes, a little difference in establishing reference gain between calibration and field condition can lead to deviation in flaw sizing. Due to this difference, the inspection result may cause flaw sizing error. Therefore, the objective of this study is to compare and evaluate the ultrasonic amplitude difference between air filled and water filled pipe in nuclear power plant. Additionally, the accuracy of flaw sizing is estimated by comparing both conditions.

횡파 위상배열 초음파탐촉자를 이용한 원자력발전소 저압 터빈 검사 적용 타당성 연구

윤병식,김용식,김진회,Yoon, Byung Sik,Kim, Yong Sik,Kim, Jin Hoi 한국압력기기공학회 2013 한국압력기기공학회 논문집 Vol.9 No.1

Steam turbine blades and discs of nuclear power plants are one of the most highly stressed areas of turbine rotor, and periodic inspection of the blade roots is essential for monitoring integrity and preventing turbine failure. Ultrasonic technique is applied for volumetric inspection of blade root. However, the complexity of blade root geometry imposes challenges to inspection of blades and discs. Recently, phased array ultrasonic inspection technology is being applied to numerous power generation inspection applications including turbine rotor. The phased array ultrasonic technique requires customized inspection wedges which are generally necessary to generate effectively higher incident angle. But the usage of this wedge can cause access limitation for the lower stage blades of turbine because of the wedge front length. Therefore, the shear wave phased array probe which can generate high inspection angle without wedge is essentially necessary. In this study, feasibility study is conducted for the shear wave phased array ultrasonic probe application to blade and disc inspection. As results, the experimental results show that the shear wave phased array probe can detect the flaw and measure its size with reliable accuracy. Therefore if this shear wave phased array probe is applied to field inspection of blade and disc, more reliable inspection is expected for turbine having access limitation.

인쇄체 한글 문자인식을 위한 피쳐추출 및 성능비교 ( Feature Extraction and Its Performance Comparsion for Printed Korean Character Recognition )

윤병식,김우태,박인규,진성일 대한전자공학회 1991 대한전자공학회 학술대회 Vol.1991 No.1

도시자영자 가입실태와 정책과제

윤병식 한국보건사회연구원 1999 보건복지포럼 Vol.34 No.-

차세대 음성/음향 부호화기 기술 동향

윤병식,최송인,강상원,Yun Byeong-Sik,Choe Song-In,Gang Sang-Won 한국통신학회 2006 정보와 통신 Vol.23 No.7

작업관리방식이 작업여건에 미치는 영향 분석 - 주단위작업관리방식과 일단위작업관리방식을 중심으로 -

윤병식,유정호,김창덕,Yoon, Byong-Sik,Yu, Jung-Ho,Kim, Chang-Duk 한국건설관리학회 2010 한국건설관리학회 논문집 Vol.11 No.5

Construction industries is a labor intensive industries. According to Korea Productivity Center, most OECD members indicate high labor productivity more than Korea labor productivity in construction industries. First of all, for increasing labor productivity work efficiency and work condition should be managed by administrator in work site. Especially, work condition could be controlled by the management behaviors of administrator in work site such as work management type. This indicates that work management type could influence strongly work condition. But although that work management type could influence work condition is the characteristic of construction work is recongized to many people, the quantitative analysis on the relationship between work condition and work management type is not enough. Therefore the purpose of this study is to analyze the Influence of Work Management Type on Work Condition. 건설산업은 노동집약적 산업으로 단위작업마다 작업자가 작업을 얼마나 효율적으로 수행했는가에 따라 노동생산성은 큰 영향을 받으며 노동생산성 향상을 위해 작업여건(work condition)이 관리되어야 한다. 작업여건은 자재, 장비, 타 작업간섭, 작업장 안전 등 작업자의 작업수행과정에 영향을 미치는 요소들로서, 작업의 특성에 따라 작업여건을 구성하는 요소들의 종류는 다양하다. 또한 작업여건들은 현장관리조직의 작업관리 행위 즉 작업관리방식에 의해 제어될 수 있다. 하지만 작업관리방식이 작업여건에 영향을 줄 수 있다는 것은 학계 및 산업차원에서 많은 사람들에게 인식되고 있지만 이를 정량적으로 검증하기 위한 노력은 부족하였다. 따라서 본 연구의 목적은 국내 건설현장에서 활용되고 있는 작업관리방식이 작업여건에 미치는 영향을 정량적으로 검증하는 것이다.

IPS-Empress 도재에 대한 콤포짓트 레진의 전단결합강도

윤병식,임미경,이용근 大韓齒科保存學會 1998 Restorative Dentistry & Endodontics Vol.23 No.1

Dental ceramics exhibit excellent esthetic property. compressive strength. chemical durability, biocompatibility and translucency. This study evaluated the shear bond strength of composite resin to the new heat-pressed ceramic material(IPS-Empress System) depending on the surface treatments and bonding agents. The surface treatments were etching with 4.0% hydrofluoric acid, application of silane, and the combination of the two methods. Composite resin was bonded to ceramic with four kinds of dentin bonding agents(All Bond 2, Heliobond, Scotchbond Multi-purpose and Tenure bonding agents). The ceramic specimen bonded with composite resin was mounted in the testing jig, and the universal testing machine(zwick 020, Germany) was used to measure the shear bond strength with the cross head speed of 0.5 mm/min The results obtained were as follows : 1. The mean shear bond strength of the specimens of which the ceramic surface was treated with the combination of hydrofluoric acid and silane before bonding composite resin was significantly higher than those of the other surface treatment groups(p<0.05). 2. In the case of All-Bond 2 and Scotchbond Multi-purpose bonding agent group, the surface treatment methods did not influenced significantly on the shear bond(p>0.05). 3. Of the four bonding agents tested, the shear bond strength of Heliobond was significantly lower than those of other bonding agents regardless of the surface treatment methods(p<0.05). 4. The highest shear bond strength(12.55+-1.92 MPa) was obtained with Scotchbond Multipurpose preceded by the ceramic surface treatment with the combination of 4% hydrofluoric acid and silane.

IPS-Empress 도재에 대한 콤포짓트 레진의 전단결합강도

윤병식,임미경 원광대학교 치의학연구소 1998 圓光齒醫學 Vol.8 No.1

Dental ceramics exhibit excellent esthetic property, compressive strength, chemical durability, biocompatibility and translucency. This study evaluated the shear bond strength of composite resin to the new heat-pressed ceramic material(IPS-Empress System) depending on the surface treatments and bonding agents. The surface treatments were etching with 4.0% hydrofluoric acid, application of silane, and the combination of the two methods. Composite resin was bonded to ceramic with four kinds of dentin bonding agents(All-Bond 2, Heliobond, Scotchbond Multi-purpose and Tenure bonding agents). The ceramic specimen bonded with composite resin was mounted in the testing jig, and the universal testing machine(Zwick 020, Germany) was used to measure the shear bond strength with the cross head speed of 0.5㎜/min. The results obtained were as follows 1. The mean shear bond strength of the specimens of which the ceramic surface was treated with the combination of hydrofluoric acid and silane before bonding composite resin was significantly higher than those of the other surface treatment groups(p<0.05). 2. In the case of All-Bond 2 and Scotchbond Multi-purpose bonding agent group, the surface treatment methods did not influenced significantly on the shear bond(p>0.05). 3. Of the four bonding agents tested, the shear bond strength of Heliobond was significantly lower than those of other bonding agents regardless of the surface treatment methods(p<0.05). 4. The highest shear bond strength(12.55 1.92㎫) was obtained with Scotchbond Multipurpose preceded by the the ceramic surface treatment with the combination of 4% hydrofluoric acid and silane.

輪廻理論의 起源

尹炳植(윤병식) 한국학중앙연구원 1983 한국학 Vol.6 No.2