TiNi/A16061 형상기억복합재료의 피로균열진전에 대한 냉간압연효과

이진경,박영철,이규창,이상필,조윤호,이준현,Lee Jin-Kyung,Park Young-Chul,Lee Kyu-Chang,Lee Sang-Pill,Cho Youn-Ho,Lee Joon-Hyun 대한기계학회 2005 大韓機械學會論文集A Vol.29 No.10

TiNi alloy fiber was used to recover the original shape of materials using its shape memory effect. The shape memory alloy plays an important role within the metal matrix composite. The shape memory alloy can control the crack propagation in metal matrix composite, and improve the tensile strength of the composite. In this study, TiNi/A16061 shape memory alloy(SMA) composite was fabricated by hot press method, and pressed by a roller for its strength improvement. The four kinds of specimens were fabricated with $0\%,\;3.2\%,\;5.2\%\;and\;7\%$ and volume fraction of TiNi alloy fiber, respectively. A fatigue test has performed to evaluate the crack initiation and propagation for the TiNi/A16061 SMA composite fabricated by かis method. In order to study the shape memory effect of the TiNi alloy fiber, the test has also done under both conditions of the room temperature and high temperature. The relationship between the crack growth rate and the stress intensity factor was clarified for the composite, and the cold rolling effect was also studied.

웹 기반 학습을 위한 평가 시스템의 설계 및 구현

이진경,전우천,Lee, Jin-Kyung,Jun, Woo-Chun 한국정보교육학회 2000 정보교육학회논문지 Vol.4 No.1

인터넷 기술의 발달로 인하여 웹 기반 학습이 증가추세에 있다. 웹 환경에서 학습도 전통적인 학습과 마찬가지로 학습 내용과 더불어 학습한 과정이나 결과에 대한 평가도 포함되어야 진정한 교육의 과정(Process)이 완성된다고 할 수 있다. 현재까지 웹 기반 학습의 평가는 학습의 결과나 지식 이해 위주의 평가가 주를 이루고 있으며 평가 결과에 대한 적절한 피드백이 제공되지 못하고 있다. 본 논문에서는 학습자가 웹 기반 학습을 하는 과정에 평가를 할 수 있도록 하였으며 즉각적인 피드백의 제공으로 학습자가 자기주도적인 학습을 해 나가는데 도움을 주도록 하였다. 즉, 교사가 작성한 문제를 문제은행화하여 데이타베이스에 저장하고 주제어, 학년, 학기, 단원별 검색이 가능하도록 하였으며 각 문제마다 정답과 오답에 대한 피드백을 줄 수 있도록 하였다. 또한 학습자는 학습을 해 나가면서 문제를 풀고 즉각적인 피드백을 제공받음으로써 문제 해결에 도움을 주며 학습의 동기를 유발하여 웹을 통한 교수 학습의 질을 향상시킬 수 있는 시스템을 설계하고 구현하였다. Web based learning has been used for many educational systems by aid of the development of internet technique. The true process of education includes not only learning contents but also learning process and the evaluation. So far, Web-based evaluation mainly consists of the evaluation of the learning products or the evaluation of the cognitive domain. But, there is lack of the appropriate feedback for learning effects. In this paper, we design and implement an evaluation system for Web-based instruction. In our system, the learners are evaluated during the process of Web-based learning. Our system provides learner-centered instruction for students with instant feedback. The questions made up by teachers are stored in the database and can be searched by a keyword, grade, semester or unit. The evaluation system can also provide the feedback to right or wrong answer for each question. Our system provides the learners with instant feedback after solving the questions and also can improve the quality of learning process using the Web.

노화효과를 고려한 저전력 셀프 튜닝 디지털 시스템의 설계

이진경,김경기,Lee, Jin-Kyung,Kim, Kyung Ki 대한임베디드공학회 2018 대한임베디드공학회논문지 Vol.13 No.3

It has become ever harder to design reliable circuits with each nanometer technology node; under normal operation conditions, a transistor device can be affected by various aging effects resulting in performance degradation and eventually design failure. The reliability (aging) effect has traditionally been the area of process engineers. However, in the future, even the smallest of variations can slow down a transistor's switching speed, and an aging device may not perform adequately at a very low voltage. Therefore, circuit designers need to consider these reliability effects in the early stages of design to make sure there are enough margins for circuits to function correctly over their entire lifetime. However, such an approach excessively increases the size and power dissipation of a system. As the impact of reliability, new techniques in designing aging-resilient circuits are necessary to reduce the impact of the aging stresses on performance, power, and yield or to predict the failure of a system. Therefore, in this paper, a novel low power on-chip self-tuning circuit considering the aging effects has been proposed.

M.엘리아데의 종교현상학 관점으로 본 현대 기독교공간의 특성에 관한 연구

이진경,김문덕,Lee, Jin-Kyung,Kim, Moon-Duck 한국실내디자인학회 2017 한국실내디자인학회논문집 Vol.26 No.4

Modern Christian spaces are developing from the past architectural styles to the phenomenological aspects. This study was conducted since it was judged that research and analysis is desirable with the application of religious phenomenological theories which fit the characteristics of religious spaces. A scholar of religion, M. Eliade studied religious phenomenology based on religious studies. This study analyzed the characteristics of religious phenomenology of the Christian spaces based on his theory. As a research method, this study analyzed the category of religious studies and religious phenomenology derived from them and selected M. Eliade as one of the theorists in the field of religious phenomenology. Study drew out the characteristics of Christian spaces from the perspective of M. Eliade's religious phenomenology as follows; In the Christian spaces, characteristics of experiential spatiality and ambiguous spatiality appeared in relation to the spaces of 'Sacred' and 'Profane' which M. Eliade aimed to explain. The characteristics of Christian spaces drawn out from the time of 'Sacred' and 'Profane', which is M. Eliade's theory, were fundamental temporality, environmental temporality and subjective temporality. From the structure and form of 'Sacred' and 'Profane', which is M. Eliade's theory, the characteristics of Christian spaces can be considered to be formative symbolism and physical naturalness. Various characteristics of Christian spaces materialize the concepts of 'hierophany' and 'sublimity' vaguely felt in religious spaces. The results of this study is expected to provide researchers, religious people and general public who study Christian spaces with research basis to further objectify results of their studies as well as basic data on the phenomenological methodology of religion.

Al 7075/CFRP 샌드위치 복합재료의 강도 및 손상특성에 대한 비파괴 평가

이진경,윤한기,이준현,Lee, Jin-Kyung,Yoon, Han-Ki,Lee, Joon-Hyun 대한기계학회 2002 大韓機械學會論文集A Vol.26 No.11

A hybrid composite material has many potential usage due to the high specific strength and the resistance to fatigue, when compared to other composite materials such as fiber reinforced plastic(FRP) and metal matrix composite(MMC). However, the fracture mechanism of hybrid composite material is extremely complicated because of the bonding structure of metals and FRP. In this study, Al 7075 sheets and carbon epoxy preprags were used to fabricate the hybrid composite. Recently, nondestructive technique has been used to evaluate the fracture mechanism of these composite materials. AE technique was used to clarify the microscopic damage behavior and failure mechanism of A17075/CFRP hybrid composite. It was found that AE paralneters such as AE event, energy and amplitude were effective to evaluate the failure process of Al 7075/CFRP composite. In addition, the relationship between the AE signal and the characteristics of fracture surface using optical microscope was discussed.

AE 기법을 이용한 TiNi/A16061 형상기억복합재료의 파괴특성평가

이진경,박영철,구후택,박동성,이규창,Lee, Jin-Kyung,Park, Young-Chul,Ku, Hoo-Taek,Park, Dong-Sung,Lee, Kyu-Chang 대한기계학회 2002 大韓機械學會論文集A Vol.26 No.2

Tensile residual stress happen by difference of coefficients of thermal expansion between fiber and matrix is one of the serious problems in metal matrix composite(MMC). In this study, TiNi fiber was used to solve the tensile residual stress as the reinforced material. TiNi fiber improves the tensile strength of composite by occurring compressive residual stress in matrix using shape memory effect of it. Pre-strain was added to generate compressive residual stress inside TiNi/A16061 composite. It was also evaluated the effect of compressive residual stress corresponding to pre-strains variation. AE technique was used to clarify the microscopic damage behavior at high temperature and the effect of pre-strain difference of TiNi/A16061 shape memory alloy composite.

스테인레스 316L강의 배관용접결함에 대한 유도초음파 특성 평가

이진경,이준현,Lee, Jin-Kyung,Lee, Joon-Hyun 한국비파괴검사학회 2015 한국비파괴검사학회지 Vol.15 No.1

스테인레스강은 고온, 고압에서 부식에 효과적인 재료로써 액화수소, 가스 등을 저장하는 저장용기 및 고온의 유체들을 이송하는 배관재료로 널리 사용되고 있다. 일반적으로 스테인레스강의 용접은 TIG용접이 이용되어지고 있으며 용접후 용접부위에 발생하는 초기 용접결함 및 사용중 발생하는 열적 피로균열 등이 재료의 신뢰성을 저하하는 요인들로 지적되고 있다. 본 논문에서는 레이저 유도초음파를 이용하여 초기 용접결함에 대한 초음파 특성 규명을 위하여 스테인레스강의 용접부에 인공균열의 크기를 5 mm, 10 mm, 20 mm 길이로 가공후 유도초음파의 결함 길이 변화에 따른 특성을 평가하였다. 배관의 두께 등을 고려하여 L(0,1)모드와 L(0,2)모드를 이용하였으며 각각의 모드가 결함의 길이 변화에 따라 변화를 보였지만 L(0,2)모드가 L(0,1)모드보다 결함 길이에 더욱 민감하게 반응하였다. 본 연구에서는 L(0,1)모드와 L(0,2)모드의 진폭비를 구하여 결함과의 연관성을 평가한 결과 결함 길이와 선형적인 관계를 나타냄으로써 각 모드를 단독적으로 평가하는 것보다는 두 모드의 진폭비를 이용하여 결함을 평가하는 것이 더욱 효과적임을 알 수 있었다. Stainless steel is a popular structural materials for liquid-hydrogen storage containers and piping components for transporting high-temperature fluids because of its superior material properties such as high strength and high corrosion resistance at elevated temperatures. In general, tungsten inert gas (TIG) arc welding is used for bonding stainless steel. However, it is often reported that the thermal fatigue cracks or initial defects in stainless steel after welding decreases the reliability of the material. The objective of this paper is to clarify the characteristics of ultrasonic guided wave propagation in relation to a change in the initial crack length in the welding zone of stainless steel. For this purpose, three specimens with different artificial defects of 5 mm, 10 mm, and 20 mm in stainless steel welds were prepared. By considering the thickness of s stainless steel pipe, special attention was given to both the L(0,1) mode and L(0,2) mode in this study. It was clearly found that the L(0,2) mode was more sensitive to defects than the L(0,1) mode. Based on the results of the L(0,1) and L(0,2) mode analyses, the magnitude ratio of the two modes was more effective than studying each mode when evaluating defects near the welded zone of stainless steel because of its linear relationship with the length of the artificial defect.

Evaluation on Damage of Pipe using Ultrasonic and Acoustic Emission

Jin Kyung Lee(이진경),Sang Pill Lee(이상필),Joon Hyun Lee(이준현),Moon Hee Lee(이문희) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5

An elastic waves like ultrasonic and acoustic emission were used to evaluate the propagating properties of the wave in pipe, and study on mode conversion of the elastic wave due to the defects on the pipe was performed. In this study an acoustic emission (AE) sensor was used to receive the propagated ultrasonic wave. AE technique has a advantage that it can identify the received ultrasonic wave by the analysis of the AE parameters such as count, energy, frequency, duration time and amplitude. For transmitting and receiving of the wave, an universial angle wedge was manufactured. The optimum angles for transmitting of ultrasonic wave and signal receiving at the attached AE sensor on the pipe were determined. Theoretical dispersion curve was compared with the results of the time-frequency analysis based on the wavelet transformation. The received modes showed a good agreement with theoretical one. The used ultrasonic sensor was 1㎒, and AE sensor was broadband. The artificial cracks were induced in the pipe to measure the propagation characteristics of the elastic wave for the cracks. AE parameters for the received signals were also varied with the crack types in the pipe. AE parameters of amplitude and duration time were more effective factors than the analysis of mode conversion for evaluation of the cracks in the pipe.

유방암의 조기진단에 있어서 Hook-wire Guided Biopsy의 의의

이진경(Jin-Kyung Lee),안세현(Sei-Hyun Ahn),박건춘(Kun-Choon Park),최혜영(Hyeu-Young Choi) 대한외과학회 1995 Annals of Surgical Treatment and Research(ASRT) Vol.49 No.5

비동기 설계 방식기반의 저전력 뉴로모픽 하드웨어의 설계 및 구현

이진경 ( Jin Kyung Lee ),김경기 ( Kyung Ki Kim ) 한국센서학회 2020 센서학회지 Vol.29 No.1

This paper proposes an asynchronous circuit design methodology using a new Single Gate Sleep Convention Logic (SG-SCL) with advantages such as low area overhead, low power consumption compared with the conventional null convention logic (NCL) methodologies. The delay-insensitive NCL asynchronous circuits consist of dual-rail structures using {DATA0, DATA1, NULL} encoding which carry a significant area overhead by comparison with single-rail structures. The area overhead can lead to high power consumption. In this paper, the proposed single gate SCL deploys a power gating structure for a new {DATA, SLEEP} encoding to achieve low area overhead and low power consumption maintaining high performance during DATA cycle. In this paper, the proposed methodology has been evaluated by a liquid state machine (LSM) for pattern and digit recognition using FPGA and a 0.18 μm CMOS technology with a supply voltage of 1.8 V. the LSM is a neural network (NN) algorithm similar to a spiking neural network (SNN). The experimental results show that the proposed SG-SCL LSM reduced power consumption by 10% compared to the conventional LSM.