Dong‐Han Seo

Chung-Ang University

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Jang-Yong Yoo

Pohang Iron and Steel (South Korea)

Woo-Hyun Song

Pohang Iron and Steel (South Korea)

Ki-Bong Kang

Pohang University of Science and Technology

Jong-Won Shin

Chung-Ang University

Jin‐Woo Lee

University of Ulsan

Seong-Soo Ahn

Pohang Iron and Steel (South Korea)

Jong‐Kyo Choi

Pohang Iron and Steel (South Korea)

Jae‐il Jang

Hanyang University

Seung-Uk Yong

Chung-Ang University

Seokwon Kim

Chung-Ang University

Cooperative Institutions

Pohang Iron and Steel (South Korea)

Hanyang University

Chung-Ang University

Korea Advanced Institute of Science and Technology

Pohang University of Science and Technology

Korea Atomic Energy Research Institute

Korea University

Research Institute of Industrial Science and Technology

Yonsei University

Seoul National University

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Microstructure And Mechanical Properties of X80/X100 Grade Plates And Pipes

The Seventeenth International Offshore and Polar Engineering Conference (2007)

Dong‐Han Seo Choong-Myeong Kim Jang-Yong Yoo Ki-Bong Kang

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Citations (8)

Optimizing inductance for minimizing reactive power in single-phase-shift modulated dual active bridge converters under variable input voltage

Journal of Power Electronics (2024)

Seung-Uk Yong Dong‐Han Seo Seokwon Kim Jong-Won Shin Wonhee Kim

Half bridge

Three-phase

10.1007/s43236-024-00961-8

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Citations (0)

Development Trend of Linepipe Seel and It's Weldability

Journal of Welding and Joining (2009)

Woo-Hyun Song Dong‐Han Seo Jang-Yong Yoo

Weldability

10.5781/kwjs.2009.27.1.034

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Citations (7)

New Development of High Grade X80 to X120 Pipeline Steels

Materials and Manufacturing Processes (2011)

Jang-Yong Yoo Seong-Soo Ahn Dong‐Han Seo Woo-Hyun Song Ki-Bong Kang

An overview of the manufacturing technology for high-strength pipeline steels was introduced. The microstructure and mechanical properties of X80, X100, and X120 grade steel plates and pipes were analyzed and discussed. Through the UOE simulator, the changes of mechanical properties after pipe-forming from plate to pipe were evaluated. The microstructure of X80 steel was composed of acicular ferrite containing M/A (Martensite/Austenite Constituent) phase. Tested X80 steel plate and pipe were found to have excellent drop weight tear test (DWTT) property. DWTT 85% SATT of X80 steel was about −40°C in pipe. The deformation capacity of X80 pipeline was evaluated by large-scale deforming machine operating under the loading of bending and axial compression force. It was found that the developed X80 pipeline was within the specification of DNV and API codes in terms of buckling capacity. In case of X100 steel, bainitic ferrite exhibiting lath and granular type morphology were major phase, and M/A existed as second phase. It was shown that the developed X100 steel can be realized to have appropriate properties for UOE pipe. DWTT 85% SATT of X00 steel pipe was shown below −40°C. Also, the development of X120 grade pipeline steel was tried. The microstructure of X120 steel was composed of bainitic ferrite and acicular ferrite. The tensile properties of developed X120 steel plate and pipe fully satisfied the property target required in the current research. DWTT 75% SATT of the developed X120 steel plate and pipe was below −30°C.

Acicular ferrite

Lath

10.1080/10426910903202534

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Citations (53)

Tensile Strain Capacity of X80 and X100 Welds

Yong-Yi Wang Fan Zhang Ming Liu Woo-Yeon Cho Dong‐Han Seo

High-strength pipelines (API 5L grade X70 and above) provide viable economic options for large-diameter and high-pressure transmission of energy products. To facilitate the understanding and potential use of high-strength pipelines, the tensile strain capacity (TSC) of X80 and X100 girth welds was evaluated through a series of mechanical tests and analytical/computational modeling. The experimental tests include tensile, Charpy, SENT, and curved-wide-plate (CWP) tests. The TSC measured from CWP tests is compared with the prediction from TSC models developed at CRES. The TSC of the girth welds is assessed by comparing experimentally measured values with the expected TSC from similar welds. The assessment confirms that this particular set of X80 and X100 girth welds provide very good tensile strain capacity.

Charpy impact test

Strain (injury)

Tensile testing

10.1115/omae2012-84240

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Citations (1)

Effect of Heat Input on Girth Welds Properties of High Strain Steel Pipe

Journal of Welding and Joining (2009)

Jin‐Woo Lee Woo-Hyun Song Dong‐Han Seo Jong‐Sub Lee

SBD (Strain-based design) of pipe lines have gained world-wide attention in recent years. The present research aims to evaluate the fracture characteristics of API (America Petroleum Institute) SBD X100 girth weldment that typically applied for cold climate and deep water offshore, with the focus on the influence of heat input changing with 6kJ/cm and 10kJ/cm from GMAW (Gas Metal Arc Welding). At a low heat input at 6kJ/cm, the weld metal had Multi-phase matrix (Acicular ferrite + Banite + Martensite) that could fill up both fracture toughness and strength as reported previously. Also, the weld metal exhibited 859MPa YS (Yield strength), 108J impact toughness at $-40^{\circ}C$ and 0.52mm CTOD (Crack Tip Open Displacement) at $-10^{\circ}C$. These results can be satisfied with the requirement of API SBD X100 girth weldment and Alaska pipe line project.

Acicular ferrite

Girth (graph theory)

10.5781/kwjs.2009.27.6.025

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Citations (3)

Effect of Parasitic Components on Dynamic Response in Buck Converters

2022 International Power Electronics Conference (IPEC-Himeji 2022- ECCE Asia) (2022)

Hanhim Sung Dong‐Han Seo Dong-Wook Kim Jong-Won Shin

The effect of parasitic components such as equivalent series resistance, equivalent series inductance, and parasitic inductance of the load, on the dynamic response is presented. The analysis is useful in minimizing the output capacitor while meeting the voltage regulation of a buck converter. The proposed analysis quantifies the parasitic effects by an equivalent circuit model of the output stage. The effectiveness and preciseness of the analysis were verified by comparing estimation, simulation, and experimental results which is obtained by a 400-kHz 15 V-3.3 V prototype buck converter.

Buck converter

Parasitic element

Equivalent series resistance

Equivalent series inductance

10.23919/ipec-himeji2022-ecce53331.2022.9807113

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Citations (0)

Digital Linear Slope Control for Boost Converter to Improve Load Transient

IEEE Access (2024)

Seokwon Kim Dong‐Han Seo Seonghwan Kim Seung-Uk Yong Jong-Won Shin

Digital linear slope control (DLSC) method is proposed to attenuate the undershoot and overshoot of the output voltage during the load transient of a boost converter without sensing current. The proposed DLSC method adjusts the slope of the control signal to improve the load transient response. DLSC requires the information of output voltage only and is realized by adding only a few lines of extra program code to the conventional VMC. A mathematical analysis is performed to demonstrate the viability of the LSC method, and the corresponding algorithms are introduced. A 10 V-15 V, 100-W boost converter operating at 100-kHz switching frequency was built and experimented to validate the effectiveness of the DLSC technique.

Overshoot (microwave communication)

Transient (computer programming)

10.1109/access.2024.3407102

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Citations (0)

The Characteristics of Girth Welds for Strain-Based Design API-X100 Grade Plate and Pipe

2010 8th International Pipeline Conference, Volume 1 (2010)

Hyun-Byung Chae Woo-Hyun Song Jin‐Woo Lee Dong‐Han Seo

As the major oil wells run dry, many efforts on exploring a new one are under way especially in the northern area of the Earth. In this cold environment, the pipelines should have a distinctive ability of being able to endure the large longitudinal strain caused by the ground movements, such as seismic activity, slope instability, frost heave and so on. To overcome these difficulties strain-based design (SBD) of pipeline is getting spotlighted, and POSCO has developed SBD API-X80 including higher grades of line pipe steels. In this work noticing that the reliability of girth welds becomes more important in SBD compared with stress-based design, ways to improve the reliability of girth welds in a SBD API-X80 grade steel have been investigated. Mechanical and metallurgical properties were evaluated, and further CTOD tests in mechanized gas metal arc (GMA) girth welding with narrow gap grooves were conducted and the results were discussed.

Girth (graph theory)

10.1115/ipc2010-31242

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Citations (0)

Development of X80/X100 Linepipe Steels With High Strain Aging Resistance

The Eighteenth International Offshore and Polar Engineering Conference (2008)

Jang-Yong Yoo Dong‐Han Seo Seong-Soo Ahn Ki-Bong Kang

Strain (injury)

Source

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Citations (4)