유한구체법을 위한 인공신경망 기반의 가우스 구적법

유민철(Minchul Yu),노건우(Gunwoo Noh) 대한기계학회 2020 大韓機械學會論文集A Vol.44 No.4

유한구체법은 신뢰성 높은 해석 기법으로, 유한요소법과 다르게 격자를 구성할 필요가 없으므로 매우 쉽고 편리하지만 해석 시간이 오래 걸리기 때문에 상용화에 어려움을 겪고 있다. 이 때문에 유한구체법에 특화된 가우스 구적법의 연구가 진행됐지만 해석 시간 단축에 대한 근본적인 해결책을 제시하지는 못하였다. 이와 관련하여 본 연구에서 인공신경망을 사용하여 가우스 구적법의 가중치를 최적화하는 알고리즘을 제시하고, 이를 통해 얻어낸 가중치를 실제 문제에 적용하였다. 적용한 문제는 총 두 개이며, 정적 문제와 동적 문제를 통해 향상된 가우스 구적법의 성능을 평가하였다. 결과적으로 가우스 구적법에 사용되는 적분 점 개수를 줄일 수 있었으며 해석 시간을 대폭 감소시켰다. The method of finite spheres is a novel and reliable numerical scheme. It is easy to use since it does not require a mesh, in contrast with the finite element method. However, the method of finite spheres uses rational interpolation functions based on the Shepard functions. Thus, it requires more integration points to integrate the element matrices accurately, resulting in poor computational efficiency. In this regard, research on Gaussian quadrature for the method of finite spheres has been conducted, however, it still implies a large computational cost. Therefore, we propose an algorithm for optimizing the weights of Gaussian quadrature using supervised learning. We evaluated the performance of enhanced Gaussian quadrature using the solutions of static and dynamic problems. The results establish that the number of integration points used in the Gaussian quadrature can be reduced, thereby significantly reducing the computational cost.

연속체 역학 기반 3차원 보 요소에 대한 지도학습 기반 가우스 구적법

김유영(Kim Yu-Yeong),유민철(Yu Minchul),윤경호(Yoon Kyungho),노건우(Noh Gunwoo) 한국통신학회 2023 한국통신학회 학술대회논문집 Vol.2023 No.11

A Case Study on Methodology of Dose Calculation for the Embedded Pipe of Decommissioning NPP

Jihwan Yu,Minchul Kim,Gi-lim Kim 한국방사성폐기물학회 2022 한국방사성폐기물학회 학술논문요약집 Vol.20 No.2

A significant amount of piping is embedded in nuclear power plants (NPPs). In decommissioning these materials must be removed and cleaned. It can then be evaluated for radioactivity content below the release level. MARSSIM presents Derived Concentration Guideline Levels (DCGLs) that meet release guidelines. Calculating DCGL requires scenarios for the placement of embedded pipe and its long-term potential location or use. Some NPPs choose to keep the embedded pipes in the building. Because others will dismantle the building and dispose of the piping in-situ, determining the disposal option for embedded piping requires the use of measurement techniques with the sensitivity and accuracy necessary to measure the level of radioactive contamination of embedded piping and meet DCGL guidelines. The main measuring detectors used in NPPs are gas counters that are remotely controlled as they move along the inside of the pipe. The Geiger-Mueller (GM) detector is a detector commonly used in the nuclear field. Typically, this GM detector used 3-detectors that cover the entire perimeter of the pipe and are positioned at 120-degrees to each other. This is called a pipe crawler. It is very insensitive to gamma and X-ray, only measures beta-emitter and does not provide nuclide identification. The second method is a method using a high-resolution gamma-ray detector. Although not yet commercialized in many places, embedded piping is a scanning method. The technique only detects gamma-emitting nuclides, but some nuclides can be identified. Gamma-ray scanning identifies the average concentration per pipe length by the detector collimator. It is considerably longer than a pipe crawler. In addition, several techniques, including direct measurement of dose rate and radiochemical analysis after scraping sampling, are used and they must be used complementary to each other to determine the source term. Expensive sampling and radiochemical analysis can be reduced if these detectors are used to measure the radioactivity profile and to perform waste classification using scaling factor. In the actual Trojan NPP, a pipe crawler detector was used to survey the activity profile in a 26 foot of an embedded pipe. These results indicate that the geometric averaging of the factors and a dispersion values for each nuclide are constant within the accuracy factors. However, in order to accurately use the scaling factor in waste classification, it must have sample representativeness. Whether the sample through smear or scraping is representative of the radionuclide mixture in the pipe. Since the concentration varies according to the thickness of the deposit and depending on the location of the junction or bend, a lot of data are needed to confirm the reliability of the nuclide mixture. In this study, the reliability of the scaling factor, sampling representativeness and concentration measurement accuracy problems for waste classification in decommissioning NPP were evaluated and various techniques for measuring radioactive contamination on the inner surface of embedded pipes were surveyed and described. In addition, the advantages and limitations of detectors used to measure radioactivity concentrations in embedded piping are described. If this is used, it is expected that it will be helpful in determining the source term of the pipe embedded in the NPPs.

온라인 광고의 유해성 개선과 "더 나은 광고" 실행에 관한 연구 : 광고주와 소비자 인식 비교를 중심으로

유현중(Yu, HyunJoong),김민철(Kim, Minchul),김운한(Kim, WoonHan) 한국광고홍보학회 2021 광고연구 Vol.- No.129

본 연구의 목적은 새로운 매체 환경에서 증가하는 온라인 광고의 유해성에 대한 광고주와 소비자 인식을 비교하고, 이른바 나쁜 광고에 대한 개선 정책의 방향성을 탐색하기 위한 것이다. 이를 위하여 국내 기업 광고주 90명과 소비자 147명 등 총 237명을 대상으로 온라인 광고 유형을 형식적 측면 10가지와 내용 측면 6가지로 요약하여 설문조사를 실시하였다. 조사 결과는 다음과 같다. 첫째, 광고형식 측면에서 나쁜 광고 인식에 대해 소비자들은 팝업광고, 종료버튼없는광고, 메뉴바 광고유형 등을, 광고주들은 자동재생광고, 프리스티셜광고, 밀도30%이상 광고 등을 더 부정적으로 인식했다. 둘째, 광고내용 측면에서 광고주들은 불법도박광고, 부적절한언어사용광고 등을, 소비자들은 미용수술시술광고를 가장 부정적으로 인식했다. 셋째, 나쁜 광고 책임 소재에 대해서는 광고주와 소비자 모두 언론/매체사, 기업(광고주) 순으로 책임을 크게 인식하였다. 넷째, 국내 디지털 환경개선을 위한 방안에 대해서는 광고주와 소비자 모두 ‘국내 포털의 나쁜 광고 방지관리를 위한 노력’을 우선시했으며, 그 다음으로 ‘유해 언론사 광고 영업을 관리 제한하는 법과 제도 마련’을 중요한 것으로 인식하였다. 연구 결과를 바탕으로 국내 온라인 광고 환경을 개선하기 위해 우선적으로 추진되어야 할 몇 가지 방안을 제시하였다. The study aims to understand the perception of so called "bad advertisement" in digital advertising and explore resonable policies to improve the present media circumstances. 90 advertising clients and 147 consumers are surveyed with 10 advertisement formats and 6 types regarding ad content. The results are as follows. First, consumers have stronger negative attitude toward pop-up ads and flash video advertising toward which clients have relatively little negative attitudes. Second, in respect to ad content, consumers have negative attitude toward beauty and operation advertising, while clients have negative attitude toward ads of illegal gambling, those in bad-words, and those of sexual content. Third, in respect to the responsibility of bad advertisements, both clients and consumers selected advertising media company(including representatives) as most highly responsible subjects. Based on the results, some methods are suggested to improve domestic digital advertising including laws and systems.

Development the direct inverse mass matrix in the method of finite spheres using meta heuristic optimization algorithm

Insu Jeong,Minchul Yu,Gunwoo Noh 대한기계학회 2023 대한기계학회 춘추학술대회 Vol.2023 No.11

Efficient Trace Modeling for PCB Warpage Simulation

Yoonha Hwang,Minchul Yu,Chanju Lee,Jinwoo Lee,Gunwoo Noh 대한기계학회 2023 대한기계학회 춘추학술대회 Vol.2023 No.11

증폭후전송 기반 에너지 하베스팅 릴레이 네트워크의 비직교 다중접속 방식 성능분석

유혜민(Hyemin Yu),주민철(MinChul Ju) 한국통신학회 2017 한국통신학회 학술대회논문집 Vol.2017 No.6

메타-휴리스틱을 이용한 유한구체법의 직접 질량 역행렬법 개발

정인수(Insu Jeong),유민철(Minchul Yu),노건우(Gunwoo Noh) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.11

The method of finite spheres is a kind of non-element method that overlaps spheres of a certain radius in the analysis area without the need to construct a complex grid. When solving the explicit dynamics equation using this MFS, the inverse of the global mass matrix needs to be found, but since the size of the global mass matrix is very large, high computational cost is required to find the inverse matrix. In this case, there is a method to obtain the inverse matrix in the local area instead of in the global area using the direct mass inverse matrix method. In this regard, we will find the appropriate direct mass inverse matrix method and parameters using a meta-heuristic algorithm. We evaluated the superiority of the solution by comparing the accuracy and operation speed of the solution with the existing method when the improved direct mass inverse matrix method is applied.

젤라틴 코팅을 이용한 광섬유형 방향성 결합기 기반 습도 센서

손경호(Gyeongho Son),김민철(Minchul Kim),유경식(Kyoungsik Yu) 한국전자파학회 2017 한국전자파학회논문지 Vol.28 No.11

본 논문에서는 기존의 플루오린화 수소산(hydrofluoric acid)을 이용한 꼬인 형태의 광섬유형 결합기 표면에 젤라틴 수용액을 코팅한 뒤 흡수체로 활용하여 상대 습도 측정에 이용하였다. 제안한 광섬유형 습도 측정 센서는 기존 전자 소자를 이용한 감지 방식과 비교하면 값이 매우 저렴하며 광섬유 및 빛이 갖는 다양한 장점들을 취하고 있다. 본 논문에서 제시한 광섬유형 습도 센서는 상대습도 기준 약 40 %에서부터 85 %까지 측정한 결과를 보여주었으며, 계산 결과와도 그 경향이 잘 일치하는 것을 알 수 있다. 본 논문에서 제시한 광섬유형 결합기 센서 구조는 향후 센서 분야에서 습도 및 다양한 위험 기체를 감지할 수 있는 역할로 유망한 역할을 맡을 수 있을 것으로 기대된다. In this paper, a gelatin layer was formed on the surface of the twisted fiber-optic couplers fabricated by hydrofluoric acid, which can be used to measure relative humidity. The proposed method of sensors has advantage of low cost compared with the sensors based on the conventional electronic devices and takes beneficial characteristics of optical fibers and light. The fiber-optic sensors presented in this study show a measurement from about 40% to 85% relative humidity, and the experimental results agree well with the calculated results. Based on the design presented in this paper, the structure will enable promising applications in the detecting humidity and various hazardous gases.

메타-휴리스틱을 이용한 유한구체법의 직접 질량 역행렬법 개발

정인수(Insu Jeong),유민철(Minchul Yu),노건우(Gunwoo Noh) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.11

The method of finite spheres is a kind of non-element method that overlaps spheres of a certain radius in the analysis area without the need to construct a complex grid. When solving the explicit dynamics equation using this MFS, the inverse of the global mass matrix needs to be found, but since the size of the global mass matrix is very large, high computational cost is required to find the inverse matrix. In this case, there is a method to obtain the inverse matrix in the local area instead of in the global area using the direct mass inverse matrix method. In this regard, we will find the appropriate direct mass inverse matrix method and parameters using a meta-heuristic algorithm. We evaluated the superiority of the solution by comparing the accuracy and operation speed of the solution with the existing method when the improved direct mass inverse matrix method is applied.