Prediction of welding residual stress with real-time phase transformation by CFD thermal analysis

Cheon, Jason,Na, Suck-Joo Elsevier 2017 International journal of mechanical sciences Vol.131 No.-

<P><B>Abstract</B></P> <P>A new method of numerical thermal-metallurgical-mechanical analysis for the gas metal arc welding process is proposed. The latest thermal-metallurgical analysis method, using real-time temperature and phase fraction history was employed in this study. The thermal-metallurgical strain behavior of a wide temperature range of austenization is considered, using dilatometry information and temperature and phase fraction dependent mechanical properties. A simple volumetric strain balance was used to describe the effect of phase transformation in the mechanical analysis. Following validation of the thermal-metallurgical analysis, the stress distribution predicted by the thermal-metallurgical-mechanical analysis was compared with measured directional stresses. In the results, the phase transformed weldment did not always appear to be expanded when a wide range of austenization temperatures was considered in the heating process. Moreover, the thermal-metallurgical-mechanical analysis of the welding process identified stress concentration on the near welding line, and nonlinear deflection by the gradient of total volumetric strain, and phase dependent yield strength. However, the model for this study did not consider the mechanical history reset of the liquid state. Also, the limitation of the stress measurement method made it difficult to make a detailed comparison with the calculated results. The model change method to allow treatment of the liquid state, and a neutron diffraction method for complete validation, will be utilized in future work to overcome these limitations.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A new method of numerical thermal-metallurgical-mechanical analysis is proposed. </LI> <LI> A new thermal-metallurgical strain behavior of welding process is proposed. </LI> <LI> A simple volumetric strain balance was used to describe the strain history. </LI> <LI> The phase transformed weldment is apparently not always expanded. </LI> <LI> The stress concentration was affected due to the phase dependent strain and yield strength. </LI> </UL> </P> <P><B>Graphic abstract</B></P> <P>[DISPLAY OMISSION]</P>

Mixed Phase Confirmation of InAsxP1−x Nanowire Array Using Modified Reciprocal Space Mapping

In-Young Jeong,Minhyuk Choi,Jeongtae Kim,Young Heon Kim,Jae Cheol Shin,Eun Kyu Kim,Chang-Soo Kim,Seungwoo Song 대한금속·재료학회 2022 ELECTRONIC MATERIALS LETTERS Vol.18 No.1

In most cases, despite the bandgap tuning flexibility of ternary semiconducting nanowires, phase mixing during nanowiregrowth is inevitable because of the surface energy competition between the bulk stable zinc blende (ZB) and the metastablewurtzite (WZ) phase. As the electronic structure of the grown nanowires depends on not only the composition but also thecrystal structure of the nanowires, careful characterization of the phase mixing phenomena in the nanowires is significant. However, because most of the phase analysis of grown nanowires relies on transmission electron microscopy (TEM), thephase analysis should be local, requires destructive sample preparation, and has a high time cost. Here, we developed amodified reciprocal space mapping method exploiting laboratory-based high-resolution X-ray diffraction (HR-XRD) forphase analysis in a one-dimensionally grown nanowire array on a (111) Si substrate in one measurement sequence. Themain difficulty of phase analysis in a nanowire array using HR-XRD is the overlap of the diffraction peaks resulting fromthe structural similarity between ZB and WZ. Using the proposed method, we could successfully separate the diffractionoverlapping of the WZ and ZB phases and reveal the lattice constants, composition, and effect of the strain of an InAsxP1−xnanowire array corresponding to the growth conditions in one measurement sequence. We also found that the crystallinityof metastable WZ was considerably lower than that of the bulk stable ZB in InAsxP1−x and that a phase fraction of WZ andZB in InAsxP1−x nanowire arrays could be tuned by adjusting their composition and diameter.

발목 PPG 신호 처리 개선을 위한 Zero Phase Filter 설계 및 시스템 연구

이재원(Jae-Won Lee),윤서진(Seo-Jin Yoon),김경호(Kyung-Ho Kim) 대한전기학회 2021 전기학회논문지 Vol.70 No.1

One of the areas of steady interest in modern society is health. In addition, in order to keep the individual’s health at its best, the healthcare device market is undergoing many trials and developments. The latest threat to COVID-19 is a major threat to heart disease patients, and it is time for continuous monitoring technology to be needed to prevent it. In particular, PPG sensor technology is relatively commercialized amid various attempts to analyze cardiovascular conditions. In general, we prefer to measure signals from fingers and wrists, which have a stable advantage in obtaining signals. However, there are cases where it is not suitable for the user’s lifestyle, which creates inconvenience. In this study, signal is measured from the ankles to minimize the inconvenience that users may experience when wearing them. And IIR Filter is applied for stable signal acquisition and analysis. Phase Delay, one of the disadvantages of this, is an unnecessary factor in real-time analysis. Zero Phase Filter is designed and applied to the system for further signal analysis. The results of the study compared three types of raw data, IIR Filter data, and Zero Phase Filter data acquired from PPG sensors, and were able to confirm the tendency of Zero Phase Filter data to match the peak points of raw data relative to IIR Filter data. The above results indicate the tendency for in-depth analysis of signals free from Phase Delay in the real-time acquisition of ankle PPG signals. Through peak-to-peak analysis and deep development of algorithms, various applications are expected to be possible by designing stress estimation and fatigue estimation systems that do not constrain users’ upper bodies.

장기구득 면담대화의 기능단계 원형

정연옥,김찬웅,김정선,이정우,박용익 한국텍스트언어학회 2022 텍스트언어학 Vol.53 No.-

Jeoung Yeonok, Kim Chanung, Kim Jungsun, Lee Jungwoo, Bak Yongik. 2022. The structure and procedure of organ procurement interview. Texlinguistics 53. The organ donation as the first prerequisite for organ transplantation is decided through an interview between the family of the brain dead person and the organ procurement coordinator. The efficient conduct of the interview is very important for the positive decision of the family for organ donation. One of the most important conditions for the efficient conduct of the interview is the coordinator's overview of global structure, procedure of the organ procurement interview and communicative acts in the individual phases. This overview allows the coordinator to anticipate, plan and prepare to perform the interview appropriately. The aim of this paper is based on the theory of dialogue grammar and the methods of qualitative research to reconstruct the pattern of dialog phases in the organ procurement interview with the family and to find and systematize the communicative acts in each phase. It was found in this research that the structure and progress of the organ procurement interview dialogue consist of six phases: Beginning phase - Relationship building phase - Preliminary phase - Informing phase - Donation consent phase - Closing phase. The communicative acts which are to perform in the individual phases are also identified and systematized. The pattern of phases of the organ procurement interview allows the coordinator to review and evaluate his own conducted interviews in order to improve the interview skill. This can also be used to train the interviewing skills of inexperienced coordinators.

가족치료 대화의 구조와 기능에 대한 대화분석적 연구

조용길(Cho Yong-Gil),유명이(Yu Myung-Yee),박태영(Park Tai-Young) 한국사회복지학회 2008 한국사회복지학 Vol.60 No.4

본 연구는 가족치료 상담자의 의사소통 능력향상을 위해 훈츠누어셔의 대화문법론을 기반으로 가족치료 전체 회기에 나타나는 상담자와 내담자 간 의사소통의 전형적인 구조인 ‘대화연속체 원형’을 기술하고 설명하는 것을 목적으로 한다. 먼저 선행연구를 통하여 가족상담의 과정단계를 초기, 중기와 종결단계로 분류하고, 각 과정단계의 부분적 기능단계를 분위기 조성단계, 가족사정단계, 인식변화 유도단계, 변화체험 확인단계, 종결단계로 나누어 대화연속체 원형을 구축하였다. 그리고 2명의 상담자와 30명의 내담자가 참여한 실제 가족치료 대화를 분석하여 각 기능단계에서 나타나는 대화연속체 원형을 설명하였다. 본 연구를 통해 구축된 대화원형은 일반적인 가족치료의 대화구조를 분석하는 틀로써 상담의 목적에 맞게 가족치료를 구조화시키고 상담자들의 효과적인 의사소통 능력을 평가하는데 사용될 수 있다. This study investigated dialog sequence prototype that was the structure of communication, which could be shown in family counseling conversation between therapists and clients. The study was intended to review the process stages of family counseling through literature review, and divided functional phases into 'atmosphere formation phase', 'family evaluation phase', 'persuasion phase of cognitive change', 'confirmation phase of change experience', and 'termination phase'. The study selected two family therapists and 30 clients for research objects. They allowed data collections for the study after the explanation about the research objects. The transcribers were trained by the consent of transcription, which used particular symbol for verbal and nonverbal contents in conversation. The transcribed data were analyzed by dialog grammar, one of the linguistic dialog analysis method developed by Hundsnurscher(1994). This study described and explained dialog sequence prototype that displayed in conversation between family therapist and client through the total sessions in family therapy. The study found three types of dialog sequence prototype in 'atmosphere formation phase', eight types in 'family evaluation phase', nine types in 'persuasion phase of cognitive change', eight types in 'confirmation phase of change experience', and eight types of 'termination phase'. Even if the dialog sequence prototype mentioned above cannot be applied to the process of family therapy at its face value, these findings may contribute to beginners in counseling and graduate students majoring family therapy to do practice in counseling. The research has a limitation in which the study investigated dialog sequence prototype of conversation in two persons. Future research needs to include dialog sequence prototype of conversation among more than three persons. Specifically, when a family therapist do family counseling,he/she treats more than three family members as usual. Therefore, the researchers hope that future study investigates dialog sequence prototype between therapist and client, client and client, among therapist, client and other family members.

Phase Advance Control to Reduce Torque Ripple of Brush-less DC Motor According to Winding Connection, Wye and Delta

Tae-Yong Lee,Jun-Young Song,Jaehong Kim,Yong-Jae Kim,Sang-Yong Jung,Jung-Moon Je 대한전기학회 2014 Journal of Electrical Engineering & Technology Vol.9 No.6

In this research, the characteristics of Brush-less DC (BLDC) motor in accordance with winding connection method, both Y-connection and △ -connection, has been identified with design methodology simply. BLDC motor has been designed for both winding connections, and their torque analysis has been performed considering ideal current source analysis and voltage source analysis with 6-step control. In addition, to reduce torque ripple of BLDC motor, caused by coil inductance, on voltage source analysis with 6-step control, we have proposed suitable control method which is Phase Advance Control. It is verified that the torque ripple has been decreased by virtue of phase advance control, advancing and widening conduction angle of switching, via performance analysis by Finite Element Analysis.

Phase Advance Control to Reduce Torque Ripple of Brush-less DC Motor According to Winding Connection, Wye and Delta

Lee, Tae-Yong,Song, Jun-Young,Kim, Jaehong,Kim, Yong-Jae,Jung, Sang-Yong,Je, Jung-Moon The Korean Institute of Electrical Engineers 2014 Journal of Electrical Engineering & Technology Vol.9 No.6

In this research, the characteristics of Brush-less DC (BLDC) motor in accordance with winding connection method, both Y-connection and D -connection, has been identified with design methodology simply. BLDC motor has been designed for both winding connections, and their torque analysis has been performed considering ideal current source analysis and voltage source analysis with 6-step control. In addition, to reduce torque ripple of BLDC motor, caused by coil inductance, on voltage source analysis with 6-step control, we have proposed suitable control method which is Phase Advance Control. It is verified that the torque ripple has been decreased by virtue of phase advance control, advancing and widening conduction angle of switching, via performance analysis by Finite Element Analysis.

Gait Analysis based on a Hidden Markov Model

Joonbum Bae 제어로봇시스템학회 2012 제어로봇시스템학회 국제학술대회 논문집 Vol.2012 No.10

For effective rehabilitation treatments, the status of a patient’s gait needs to be analyzed precisely. Since the gait motions are cyclic with several gait phases, the gait motions can be analyzed by gait phases. In this paper, a hidden Markov model (HMM) is applied to analyze the gait phases in the gait motions. Smart Shoes are utilized to obtain the ground contact forces (GRFs) as observed data in the HMM. The posterior probabilities from the HMM are used to infer the gait phases. The proposed gait phase analysis methods are applied to actual gait data, and the results show that the proposed methods can be used to diagnose the status of a patient and evaluate a rehabilitation treatment.

생활체육 탁구 참여자들을 위한 4단계 지표 평가 이론 바탕의 경기 기술력 및 전술 분석에 대한 이해 : 진지한 관람 경험으로서의 생활체육에 대한 의미

이학,조남기,신민혜 한국사회체육학회 2024 한국사회체육학회지 Vol.- No.96

Purpose: The purpose of this study is to analyze the technical and tactical aspects of Chinese player Chen Meng’s performance using the four-phase evaluation theory. Method: The research data consisted of 10 matches played by Chen Meng in table tennis tournaments from 2019 to 2022, spanning a period of 4 years. Video analysis of the matches was conducted. A total of 10 videos were collected from YouTube and YouKu. Data analysis was performed using SPSS version. 22. Results: Firstly, in the analysis of Chen-meng’s serve landing points, the forehand short service (landing point ①) was used 191 times, resulting in 111 points scored. Secondly, Chen-meng scored a total of 57 points from serves and incurred 8 points in the serve and preemptive attack phases. In the third game, a total of 134 points were scored, with 79 points scored, and in the fifth game, a total of 70 points were scored. Thirdly, in the serve-round rally phase, Chen-meng scored a total of 66 points in the fifth game and a total of 62 points after the seventh game, accumulating a total of 106 points. Fourthly, in the phase following the reception and preemptive attack, Chen-meng scored a total of 83 points in the second game and lost 53 points. In the fourth game, a total of 74 points were scored, but 97 points were lost. Fifthly, in the receive-round rally phase, Chen-meng scored a total of 131 points after the sixth game, with a total of 136 points accumulated. Conclusion: It was found that the third ball is Chen Meng’s primary scoring opportunity, and she lacks proactive attacking consciousness in the receive phase, while the serve-round rally phase is disadvantageous to Chen Meng.

희토류 산화물이 첨가된 YSZ 기반의 열차폐 코팅용 소재의 상 형성 및 기계적 특성

최용석,이계원,남산,오윤석 한국분말재료학회 2023 한국분말재료학회지 (KPMI) Vol.30 No.5

This study focused on improving the phase stability and mechanical properties of yttria-stabilized zirconia (YSZ), commonly utilized in gas turbine engine thermal barrier coatings, by incorporating Gd2O3, Er2O3, and TiO2. The addition of 3-valent rare earth elements to YSZ can reduce thermal conductivity and enhance phase stability while adding the 4-valent element TiO2 can improve phase stability and mechanical properties. Sintered specimens were prepared with hot-press equipment. Phase analysis was conducted with X-ray diffraction (XRD), and mechanical properties were assessed with Vickers hardness equipment. The research results revealed that, except for Z10YGE10T, most compositions predominantly exhibited the t-phase. Increasing the content of 3-valent rare earth oxides resulted in a decrease in the monoclinic phase and an increase in the tetragonal phase. In addition, the t(400) angle decreased while the t(004) angle increased. The addition of 10 mol% of 3-valent rare-earth oxides discarded the t-phase and led to the complete development of the c-phase. Adding 10 mol% TiO2 increased hardness than YSZ.