Multiscale simulations for estimating mechanical properties of ion irradiated 308 based on microstructural features

곽동현,심재민,장윤석,공병서,장창희 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.8

Austenitic stainless steel welds (ASSWs) of nuclear components undergo aging-related degradations caused by high temperature and neutron radiation. Since irradiation leads to the change of material characteristics, relevant quantification is important for long-term operation, but limitations exist. Although ion irradiation is utilized to emulate neutron irradiation, its penetration depth is too shallow to measure bulk properties. In this study, a systematic approach was suggested to estimate mechanical properties of ion irradiated 308 ASSW. First of all, weld specimens were irradiated by 2 MeV proton to 1 and 10 dpa. Microstructure evolutions due to irradiation in d-ferrite and austenite phases were characterized and micropillar compression tests were performed. In succession, dislocation density based stress-strain (SeS) relationships and quantification models of irradiation defects were adopted to define phases in finite element analyses. Resultant microscopic SeS curves were compared to verify material parameters. Finally, macroscopic behaviors were calculated by multiscale simulations using real microstructure based representative volume element (RVE). Validity of the approach was verified for the unirradiated specimens such that the estimated SeS curves and 0.2% offset yield strengths (YSs) which was 363.14 MPa were in 10% agreement with test. For irradiated specimens, the estimated YS were 917.41 MPa in 9% agreement.

수중 광통신 환경에서 최적 파장을 도출하기 위한 실험적 해석

곽동현,전승일,최정락,한민석 한국정보전자통신기술학회 2023 한국정보전자통신기술학회논문지 Vol.16 No.6

This paper investigates the naval application of laser communication as a potential replacement for traditional acoustic wave communication in underwater environments. We developed a laser transceiver using Arduino and MATLAB, conducting a water tank experiment to validate communication feasibility across diverse underwater conditions. In the first experiment, when transmitting data through a laser, the desired message was converted into data and transmitted, received, and confirmed to be converted into the correct message. In the second experiment, the operation of communication in underwater situations was confirmed, and in the third experiment, the intensity of light was measured using the CDS illuminance sensor module and the limits of laser communication were measured and confirmed in various underwater situations. Additionally, MATLAB code was employed to gather data on salinity, water temperature, and water depth for calculating turbidity. Optimal wavelength values (532nm, 633nm, 785nm, 1064nm) corresponding to calculated turbidity levels (5, 20, 55, 180) were determined and presented. The study then focuses on analyzing potential applications in naval tactical communication, remote sensing, and underwater drone control. Finally, we propose measures for overcoming current technological limitations and enhancing performance. 본 논문은 수중 환경에서의 전통적인 음파 통신을 대체할 수 있는 레이저 통신의 해군 적용 방안을 연구한다. 아두이노 및 MATLAB을 활용한 레이저 송수신기를 구성하여 수조 실험을 진행하여 다양한 수중 환경에서 통신 가능 여부를 확인하였다. 첫 번째 실험에서는 레이저를 통해 데이터를 전송할 때, 통신 간 원하는 메시지를 데이터화하여 전송하고 이를 수신하여 올바른 메시지로 변환되는지 확인하였다. 두 번째 실험에서는 수중 상황에서의 통신 작동 여부를 확인하였으며, 세 번째 실험에서는 CDS 조도 센서 모듈을 사용하여 빛의 세기를 측정하고 다양한 수중 상황에서 레이저 통신의 한계를 측정하여 확인하였다. 또한, MATLAB Code를 활용해 염도, 수온, 수심 등의 데이터를 수집하여 탁도를 계산하고 계산된 탁도(5, 20, 55, 180)에 대해서 최적의 파장값(532nm, 633nm, 785nm, 1064nm)을 제시하였다. 이를 바탕으로 해군 전술 통신, 원격 센싱, 수중 드론 제어 등의 분야에서의 활용방안을 중점적으로 분석한다. 마지막으로 현재의 기술 한계를 극복하고 성능을 향상하는 개선방안을 제시하였다.

지진하중 입사각이 사용후핵연료 건식 저장시설의 구조건전성에 미치는 영향 분석

곽동현,장윤석 한국압력기기공학회 2021 한국압력기기공학회 논문집 Vol.17 No.2

This study aims to assess the effect of postulated seismic loads on the structural integrity of a spent nuclear fuel dry storage facility. Firstly, three-dimensional modal and response spectrum analyses were carried out. With regard to the latter analysis, the effect of incident angles against two horizontal and one vertical response spectra was also considered. Results showed that even though two critical locations were predicted at the longitudinal axis central part of upper flow path as well as the end discontinuity part of upper and lower flow paths connector, their maximum principal stress values were less than the tensile strength. Moreover, since the influence of vertical angle was 87% higher than that of horizontal angle in particular, which should be carefully handled to demonstrate integrity of the facility.

빅데이터를 활용한 새로운 관점의 서비스 측정항목 개발

곽동현,이병철 한국이벤트컨벤션학회 2018 이벤트 컨벤션 연구 Vol.14 No.4

Purpose –This research is based on Churchill (1979)’s Scale development method that has been widely applied for scale development and the general application methods of big data that contain how to collect and analysis big data. Research design, data, and methodology –Step 1. Domain of constructs. Step 2. Generate sample of measurement items from big data, collect data, and purify measurement. Step 3. To collect data and to assess reliability and validity. Step 4. To present measurement items. To identify actual words that consumers use for describing tangible and intangible service factors of hospital (clinic), 5,946,317 blog posts from searching engine were collected and natural language analysis was performed. Result –Through the process of finding extracted items from big data, total 7 measurement items including 4 intangible sections and 3 tangible sections were generated. Conclusions –In the section of intagible:'Kindness of staff', 'skill of doctor', 'comfortableambience', 'treatment method'. In the section of tangible: 'modern medical facility of interior', 'modern medical facility of medical device', 'the number of staff'.

영남 소리판노래의 음악적 연구 -효빈가(效嚬歌)를 중심으로-

곽동현 한국음악문헌학회 2020 음악문헌학 Vol.- No.11

연결망 분석을 통한 이벤트컨벤션분야 연구동향분석 -이벤트컨벤션연구를 중심으로-

곽동현,이병철 한국이벤트컨벤션학회 2019 이벤트 컨벤션 연구 Vol.15 No.1

Purpose – The purpose of this study is to identify research trends in the field of events, convention, festival and an international conference by using social network analysis. Research design, data, and methodology – This study examined event and convention studies that were published event and convention research (KCI indexed) in the last ten years. Keyword network and author network were mainly analyzed including network connection, centrality and cohesion. This study covers 153 research papers published from 2008 to 2018. Result – This study confirmed that the field of event and convention research shows continued growth in terms of quantity. This study did not find a meaningful link between research keywords. Also, this study concluded that core keywords have not yet formed meaning that event and convention research stay at the early stages of network formation. Conclusions – This study suggests that although this study found quantitative growth of the event and convention-related research, the topics of studies and authors need to be expanded to generated more research keywords for network formation.

의료관광객이 인지한 의료서비스품질이 서비스가치와 행동의도에 미치는 영향연구

곽동현,이병철 (사)한국관광레저학회 2019 관광레저연구 Vol.31 No.7

This study aimed at developing a model that explains the intention formations of international medical travelers by examining the impact of medical service quality on service value, satisfaction, and behavioral intention. Based on literature review, medical service was divided into two factors: tangible and intangible service. Service value was divided into two components: hedonic and utilitarian value. Data was collected from international medical tourists visiting South Korea from July 1 to July 31, 2018. A total of 311 samples were used for hypotheses test. Findings from the analysis of structural equation model indicated a good fit for the proposed model. Most hypothesis paths were statistically significantly except for three relationships: intangible service quality and hedonic value, hedonic value and satisfaction, and hedonic value and behavioral intention. This result implies that due to the clear purpose of medical tourists, more practical service and value are key factors strongly influencing medical tourists’ satisfaction and behavioral intention.

Analysis of Single-RF MIMO Receiver with Beam-Switching Antenna

곽동현,손일수,이승환 한국전자통신연구원 2015 ETRI Journal Vol.37 No.4

This paper proposes a single-RF MIMO receiver that adopts a beam-switching antenna (BSA) instead of a conventional array antenna. The beauty of the proposed single-RF MIMO receiver with BSA is that it can be deployed in a very small physical space while achieving a full spatial multiplexing gain. Our analysis has revealed that the use of a BSA inevitably results in the spectrum spreading effect at the RF output, which in turn causes an SNR decrease and adjacent channel interference (ACI). Two novel receiver techniques are proposed to mitigate the issues of redundant sub-band suppression and ACI avoidance. Numerical analysis results verify the performance improvement from the proposed receiver techniques.

경남 가창유희요에 나타난 토리의 활용 양상

곽동현 한국음악문헌학회 2014 음악문헌학 Vol.- No.5

가창유희요란가창을목적으로 하는유희요. 즉특별한기능없이 노래 부르기 자체에 목적이 있는 노래를 말한다. 경남지역 민요들 중에서는 고정된 악곡이 없는 밭매는소리, 베틀소리, 시집살이 같은 노래나 주로 독창으로 불리는 타령류에 속한 노래들이 가창유희요에 속한다. 경남지역은 경상북도와 전라북도의 인접해있기도 하고 해안을 끼고 있기 때문에 바다를 통한 음악적 교류도 가능한 그런 지역이다. 또한 경 남민요에는 다른 노동요 못지않게 많은 유희요들이 존재하는데 이에 대 한 선행연구는 별로 없었다. 경남민요에는 예로부터 채록된 민요들, 전 라도 혹은 서울지방의 민요도 포함하고 있었고, 경상남도 고유의 민요는 이들타지방민요의영향으로변질된것이많다고한다. 따라서경남지 역은 가창유희요가 외부로부터 어떤 영향이 어떻게 나타났는지가 궁금 하다.

음악 부문 유성기음반 수록 정유색 민요 <남도방아타령>과 <쾌지나칭칭>의 고찰

곽동현 한국고음반연구회 2014 한국음반학 Vol.24 No.-