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Development of a radiological emergency evacuation model using agent-based modeling
Hwang, Yujeong,Heo, Gyunyoung Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.7
In order to mitigate the damage caused by accidents in nuclear power plants (NPPs), evacuation strategies are usually managed on the basis of off-site effects such as the diffusion of radioactive materials and evacuee traffic simulations. However, the interactive behavior between evacuees and the accident environment has a significant effect on the consequential gap. Agent-based modeling (ABM) is a method that can control and observe such interactions by establishing agents (i.e., the evacuees) and patches (i.e., the accident environments). In this paper, a radiological emergency evacuation model is constructed to realistically check the effectiveness of an evacuation strategy using NetLogo, an ABM toolbox. Geographic layers such as radiation sources, roads, buildings, and shelters were downloaded from an official geographic information system (GIS) of Korea, and were modified into respective patches. The dispersion model adopted from the puff equation was also modified to fit the patches on the geographic layer. The evacuees were defined as vehicle agents and a traffic model was implemented by combining the shortest path search (determined by an A <sup>*</sup> algorithm) and a traffic flow model incorporated in the Nagel-Schreckenberg cellular automata model. To evaluate the radiological harm to the evacuees due to the spread of radioactive materials, a simple exposure model was established to calculate the overlap fraction between the agents and the dispersion patches. This paper aims to demonstrate that the potential of ABM can handle disaster evacuation strategies more realistically than previous approaches.
Chulsoon Hwang,Jaemin Kim,Eakhwan Song,Yujeong Shim,Joungho Kim IEEE 2011 IEEE transactions on electromagnetic compatibility Vol.53 No.1
<P>A wideband and compact partial electromagnetic bandgap (PEBG) structure and a corresponding stopband-estimation model are proposed for the suppression of simultaneous switching noise (SSN) coupling in a multilayer printed circuit board. The proposed PEBG structure achieves a wide stopband with a compact size by adopting a geometric arrangement of patches that allows for a periodic narrow via pitch (NVP). In addition, the lumped capacitance model of the previously reported effective phase constant equation is replaced with the resonant cavity model to obtain the precise impedance of the patch in high frequency. Finally, it was successfully verified that, by applying the NVP-PEBG structure, wideband suppression of SSN coupling to the signal via is achieved with a bandwidth of 11.2 GHz below -40 dB. The proposed estimation model was validated through experimental measurements.</P>
Korean Sentiment Analysis Using Natural Network: Based on IKEA Review Data
Sim, YuJeong,Yun, Dai Yeol,Hwang, Chi-gon,Moon, Seok-Jae The Institute of Internet 2021 International Journal of Internet, Broadcasting an Vol.13 No.2
In this paper, we find a suitable methodology for Korean Sentiment Analysis through a comparative experiment in which methods of embedding and natural network models are learned at the highest accuracy and fastest speed. The embedding method compares word embeddeding and Word2Vec. The model compares and experiments representative neural network models CNN, RNN, LSTM, GRU, Bi-LSTM and Bi-GRU with IKEA review data. Experiments show that Word2Vec and BiGRU had the highest accuracy and second fastest speed with 94.23% accuracy and 42.30 seconds speed. Word2Vec and GRU were found to have the third highest accuracy and fastest speed with 92.53% accuracy and 26.75 seconds speed.
Home-built sub-Kelvin scanning tunneling microscope with electron spin resonance capability
Jiyoon Hwang,Denis Krylov,Taehong Ahn,Lei Fang,Kyungju Noh,Andreas J. Heinrich,Yujeong Bae 한국자기학회 2021 한국자기학회 학술연구발표회 논문개요집 Vol.31 No.1
Scanning tunneling microscopy is a powerful tool to characterize the electronic and magnetic properties of atomic scale structures on a surface. Recent advances in increasing energy resolutions have been achieved functionalizing the STM tip by a well-characterized molecule [1,2] or integrating electron spin resonance with STM (ESR-STM) [3]. We present the design and performance of home-built STM with high frequency cabling, which is incorporated with a Joule-Thomson refrigerator and 2-axes vector magnets. Applying high frequency (microwave) electric fields to the STM junction through 50 Ohm coaxial cables causes significant loss of insertion power due to the impedance mismatch at the STM junction of ~1 GOhm, which limits the frequency range of applicable microwaves. To overcome this limitation, we introduced a microwave antenna and terminated the cable at 50 Ohm. Applying microwaves to the antenna rather than the STM tip allows us to reduce the formation of standing waves as well as to increase the transmission. Our work shows using the specially designed mechanical damper and optimizing the electrical noise levels provide the outstanding performance of STM for the single atom ESR experiment.
An On-Chip Electromagnetic Bandgap Structure using an On-Chip Inductor and a MOS Capacitor
Chulsoon Hwang,Yujeong Shim,Kyoungchoul Koo,Myunghoi Kim,Jun So Pak,Joungho Kim IEEE 2011 IEEE microwave and wireless components letters Vol.21 No.8
<P>An on-chip electromagnetic bandgap (EBG) structure using a CMOS process is proposed. The proposed structure is the first EBG structure devised to suppress simultaneous switching noise coupling in an on-chip power distribution network (PDN). The on-chip EBG structure utilizes an on-chip inductor and a MOS capacitor to generate a stopband with a range of several GHz in an extremely small size; thus, the EBG structure can be embedded in on-chip PDNs. The proposed on-chip EBG structure was fabricated using a MagnaChip 0.18 μm CMOS process, and we successfully verified a 9.24 GHz stopband, from 1.26 to 10.5 GHz, with an isolation level of 50 dB.</P>
구유정(Yujeong Ku),장원섭(Wonsup Chang),이민영(Minyoung Lee),이진희(Jinhee Lee),황정산(Jeongsan Hwang) 한국직업교육학회 2021 職業 敎育 硏究 Vol.40 No.4
본 연구는 장원섭(2015)의 장인성 개념에 기반하여 고안한 개념인 장인적 일하기 척도를 개발하고, 타당화하는 데 목적이 있다. 관련 개념 및 측정도구에 관한 문헌 고찰을 통해 장인적 일하기의 개념을 확립하고, 5개의 하위요인을 정의하였다. 교육학 및 인적자원개발 분야 전문가 24인을 대상으로 2회의 델파이 조사를 시행하여 5개 요인의 26개의 예비문항을 개발하였다. 예비조사는 국내 직장인 219명을 대상으로 수행하였으며, 척도의 신뢰도 및 타당도를 확인하였다. 분석 결과, 3개 요인구조 모형이 적합한 것으로 나타나 장인적 일하기 척도를 일 지향성, 주체적 일하기, 일의 창조로 재구성하였고, 일부 문항을 수정・삭제하여 25개의 문항을 도출하였다. 본 조사는 국내 직장인 525명을 대상으로 수행하였고, 이를 토대로 신뢰도 분석 및 탐색적 요인분석(EFA)을 실시하여 척도의 구성요인과 문항의 신뢰도와 타당성을 확인하였다. 확인적 요인분석(CFA)을 통해 모형의 적합도를 검증하였으며, 동일 하위요인 내의 타 문항과 상관이 높은 1개 문항을 삭제하였다. 최종적으로 일 지향성, 주체적 일하기, 일의 창조의 3개 요인과 24개의 문항을 확정하였다. 마지막으로 본 연구에서 개발한 척도의 의의 및 제한점을 토대로 후속 연구에 대해 제언하였다. This study aims to develop and validate Masteristic Work Scale (MWS). The definition of masteristic work was established based on Masterity presenting the characteristics of a master s work and life from a modern perspective (Chang, 2015). 26 items and 5 factors were developed based on literature review and expert reviews using the Delphi method. The reliability and validity test of the scale was conducted on the data from a preliminary survey of 219 employees. The model was revised and reconstructed into the 3-factor model with 25 items based on factor analysis results. The validation on the main survey data of 525 employees was conducted, and 1 item with a high correlation to other items was removed. As a final version of MWS, 3 factors: work orientation, proactive work, and work creation, and 24 items were validated and confirmed. Implications and limitations of MWS and suggestions for future studies were suggested.