유한요소해석을 활용한 장신구디자인 사례연구 - 예술장신구 사례를 중심으로 -

민복기 ( Min Bog Ki ) 한국기초조형학회 2020 기초조형학연구 Vol.21 No.1

본 연구의 목적은 응용수학분야에서 연구되어 토목, 건축 등의 분야에서 활용되고 있는 유한요소해석에 대해 살펴보고, 이를 장신구 분야에 적용할 가능성을 탐색하는 데 있다. 유한요소법(Finite Element Method; FEM)은 미분방정식 문제를 다른 형태로 바꾸고 이 해(解)를 어떤 함수의 일차결합으로 나타내는 수치적인 근사해법(approximation method)의 하나이다. 이러한 수학적 원리를 바탕으로 재료역학 등의 공학분야에서 물성과 하중 등 외부적 요인을 설정하고 대상물의 물리적 변위의 근사값을 도출하여 구조를 해석하는 것이 유한요소해석(Finite Element Analysis; FEA)이다. FEA는 컴퓨터의 계산을 통한 시뮬레이션 기술로 빠르게 정립되었고, 이후 CAD의 모델링데이터를 활용할 수 있도록 통합되어 강도, 열, 유동, 진동 등 다양한 물리적 환경의 시뮬레이션을 통해 효율적 설계를 도출하는데 활용되고 있다. 장신구는 매우 작은 사물이지만 신체 위에 착용되는 필연적 조건을 가지므로 안정적 구조로 제작되어야 하지만 이를 위해 FEA를 활용한 사례는 없었다. 연구자는 이러한 장신구의 요구조건을 충족하는 새로운 난발(Prong)의 구조연구를 위해 FEA를 활용한 난발구조를 연구하였고 4개 혹은 6개로 이루어진 일반적인 난발구조에서 난발의 개수를 최소화하여 2개의 난발구조를 가지도록 하였다, 그리고 빛의 유입을 위해 오브제를 기저부에서 2mm 위로 띄워 고정할 수 있는 난발구조를 개발하였다. 이러한 사례에서와 같이 FEA는 주얼리의 구조안정성 검증 뿐 아니라 새로운 컨셉의 디자인탐색에 도움을 줄 수 있고 주얼리산업의 생산과정에서도 열과 유동의 해석을 통해 주조생산성과 품질을 개선시킬 수 있다. 또한 금속공예의 대공분야에서도 하중이나 낙하, 바람 등 다양한 물리적 외력을 시뮬레이션 하여 좀 더 안정적인 구조를 도출하는데 활용될 수 있을 것이다. The purpose of this study is to examine the Finite Element Analysis, studied in Applied Mathematics and used in the fields of Civil Engineering and Architecture, and to explore the possibilities of applying it to the field of jewelry. Finite Element Method changes differential equations into different forms and appears as one of the numerical approximation methods. With this mathematical principle background, the linear combination of the certain function’s value sets the external factors such as property and weight in the engineering field, material mechanics and Finite Element Analysis is the evaluation of the structure by approximating the physical displacement of the object. FEA quickly became a computerized simulation technology, and later integrated to utilize CAD modeling data to simulate various physical environments such as strength, heat, flow, and vibration, etc. for effective design. A jewelry is a very small object it has an inevitable condition to be worn on top of the body; therefore, needs to be made with a secure structure but, there has been no case for it with FEA. This research studies the required conditions of this kind of jewelry with new prong structure research that uses FEA and minimizes the number of prongs in the prongs’ structure to two from four or six, and developed new prong structures for the object to float 2mm above the basis for light to pass. In such a case, FEA not only verifies the structural stability but make new concept design exploration possible and can improve productivity and quality through the interpretation of heat and flow in the casting process of the jewelry industry’s production process. Moreover, various physical external forces such as weight, fall or wind can be simulated to construct safer structures for vessel making in the field of Metal Craft as well.

STRICTA 권장안에 기초한 침 연구방법론의 적절성 평가 - 새로운 평가지수를 이용한 5편 Systematic Review와 그 대상인 58편 무작위대조시험의 고찰 -

김우영,이승덕,임병묵,김갑성 대한침구의학회 2007 대한침구의학회지 Vol.24 No.5

Backgraounds : Recent studies provide the evidences that the efficacy of acupuncture may be no better than placebo or inconclusive. These results are very different from those of the actual clinical situations in many acupuncture medical institutions. Objectives : The present study was designed to evaluate the influencing factors which affect the efficacy of acupuncture scale(FEAS) as the methodological assessment tool of acupuncture for examining acupuncture interventions and to demonstrate the importance of it in randomized controlled trials of acupuncture. Data sources : Electronic data were retrieved from NDSL, Pubmed, sciencedirect, LWW, OVID, Black- Well Synergy, Wiley Interscience, EBSCO HOST, springer, PML, and Kluwer. No electronic data were collected from MEDLIS and MEDLAS. Study selection : The inclusion criteria were five systematic reviews included in Alberta study and all randomized controlled trials obtained from their references. Study analysis : The acupuncture rationale, methods of stimulation, treatment regimen, and the prac- titioner’s background were rated by FEAS, and the scores were compared with those by other methodo- logical assessment tools. Results : The number of positive conclusions of high-rank RCTs by FEAS was the same as or higher than that of high-rank RCTs by other methodological assessment tools. Conclusions : We have analysed 5 systematic reviews and their objectives 58 RCTs using FEAS. Prac- titioner’s background has been described slightly in some reviews and studies. It may directly influence the effectiveness of acupuncture negatively in the systematic reviews. Backgraounds : Recent studies provide the evidences that the efficacy of acupuncture may be no better than placebo or inconclusive. These results are very different from those of the actual clinical situations in many acupuncture medical institutions. Objectives : The present study was designed to evaluate the influencing factors which affect the efficacy of acupuncture scale(FEAS) as the methodological assessment tool of acupuncture for examining acupuncture interventions and to demonstrate the importance of it in randomized controlled trials of acupuncture. Data sources : Electronic data were retrieved from NDSL, Pubmed, sciencedirect, LWW, OVID, Black- Well Synergy, Wiley Interscience, EBSCO HOST, springer, PML, and Kluwer. No electronic data were collected from MEDLIS and MEDLAS. Study selection : The inclusion criteria were five systematic reviews included in Alberta study and all randomized controlled trials obtained from their references. Study analysis : The acupuncture rationale, methods of stimulation, treatment regimen, and the prac- titioner’s background were rated by FEAS, and the scores were compared with those by other methodo- logical assessment tools. Results : The number of positive conclusions of high-rank RCTs by FEAS was the same as or higher than that of high-rank RCTs by other methodological assessment tools. Conclusions : We have analysed 5 systematic reviews and their objectives 58 RCTs using FEAS. Prac- titioner’s background has been described slightly in some reviews and studies. It may directly influence the effectiveness of acupuncture negatively in the systematic reviews.

다양한 환경에서의 형태보존 암호 FEA에 대한 최적 구현

박철희,정수용,홍도원,서창호 한국정보보호학회 2018 정보보호학회논문지 Vol.28 No.1

형태보존 암호는 평문의 형태를 그대로 보존하여 암호화를 수행한다. 따라서 암호화 전・후에 대한 데이터베이스의 구조 변경을 최소화 시킬 수 있다. 예를 들어 신용카드, 주민등록번호와 같은 데이터에 대한 암호화를 수행할 경우 형태보존 암호는 평문과 동일한 형태의 암호문을 출력하기 때문에 형태가 갖춰진 기존의 데이터베이스 구조를 그대로 유지할 수 있다. 현재 미국표준기술연구소(NIST)는 형태보존 암호의 표준으로써 FF1과 FF3를 권장하고 있다. 최근 국내의 경우 매우 효율적인 형태보존 암호 알고리즘인 FEA를 형태보존 암호의 표준으로 채택하였다. 본논문에서는 대한민국 형태보존 암호의 표준 알고리즘인 FEA를 분석하고 다양한 환경에서 최적 구현하여 FEA의성능을 측정한다. Format preserving encryption(FPE) performs encryption with preserving the size and format of plain-text. Therefore, it ispossible to minimize the structural change of the database before and after the encryption. For example, when encryptingdata such as credit card number or social security number, it is possible to maintain the existing database structure becauseFPE outputs the same form of cipher-text as plain-text. Currently, the National Institute of Standards and Technology (NIST)recommends FF1 and FF3 as standards for FPE. Recently, in Korea, FEA, which is a very efficient FPE algorithm, hasbeen adopted as the standard of FPE. In this paper, we analyze FEA and measure the performance of FEA by optimizing itin various environments.

Wear behavior of diamond wheel for grinding optical connector ferrule - FEA and wear test -

서창민,배규석,서민수 대한기계학회 2008 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.22 No.11

The grinding characteristics and the wear behavior of diamond wheel for grinding the optical connector ferrule were investigated by finite element analysis (FEA) and wear test. FEA of contact between diamond wheel and ferrule shows that the subsurface damage area of ferrule is 13μm from the interface of abrasive particle and matrix. Fallout of abrasive particle is affected by the stress state at the interface. A 2-D finite element model was established to calculate the distribution of stress at the interface. As the result of FEA, fallout condition of abrasive was concerned with the ratio of the critical protrusion; the ratio of particle size is about 0.6. FE model was established to investigate the effects of the diamond concentration of wheel. The FEA result shows that the lower concentration of it has larger wear volume due to the small stress propagation.. To investigate grinding performance, the pin-on-disc wear test was carried out for three types of concentrations 75%, 100% and 125%. Through the wear test, it was confirmed that the 75% wheel concentration has the highest amount of wear volume. This result shows good agreement with that of FEA. And 100% concentration by considering the grinding ratio of the wheel shows the best optimized result for the grinding performance.

실리사이드를 이용한 새로운 고내구성 실리콘 전계방출소자의 제작

장지근,윤진모,정진철,김민영,Chang, Gee-Keun,Yoon, Jin-Mo,Jeong, Jin-Cheol,Kim, Min-Young 한국재료학회 2000 한국재료학회지 Vol.10 No.2

Si FEA로부터 tip의 표면을 Ti 금속으로 silicidation한 새로운 3극형 Ti-silicided Si FEA를 제작하고 이의 전계 방출특성을 조사하였다. 제작된 소자에서 단위 pixel(pixel area : $1000{\mu\textrm{m}}{\times}1000{$\mu\textrm{m}}$, tip array : $200{\mu\textrm{m}}{\times}200{$\mu\textrm{m}}$)을 통해 측정된 전계 방출 특성은 $10^8Torr$의 고진공 상태에서 turn-on 전압이 약 70V로, 아노드 방출전류의 크기와 current degradation이 $V_A=500V,\;V_G=150V$ 바이어스 아래에서 각각 2nA/tip와 0.3%/min로 나타났다. 3극형 Ti-silicided Si FEA의 낮은 turn-on 전압과 높은 전류안정성은 Si tip 표면에 형성된 실리사이드 박막의 열화학적 안정성과 낮은 일함수에 기인하는 것으로 판단된다. A new triode type Ti-silicided Si FEA(field emitter array) was realized by Ti-silicidation of Ti coated Si FEA and its field emission properties were investigated. In the fabricated device, the field emission properties through the unit pixel with $200{\mu\textrm{m}}{\times}200{$\mu\textrm{m}}$ tip array in the area of $1000{\mu\textrm{m}}{\times}1000{$\mu\textrm{m}}$ were as follows : the turn-on voltage was about 70V under high vacuum condition of $10^8Torr$, and the field emission current and steady state current degradation were about 2nA/tip and 0.3%/min under the bias of $V_A=500V\;and\;V_G=150V$. The low turn-on voltage and the high current stability during long term operation of the Ti silicided Si FEA were due to the thermal and chemical stability and the low work function of silicide layer formed at the surface of Si tip.

중국 소비자의 웨어러블 디바이스 채택요인 관한 연구: FEA모델을 중심으로

현효원,박정근,임천보,임명섭 한국국제경영학회 2018 國際經營硏究 Vol.29 No.4

기술의 발전과 네트워크 성능 향상으로 웨어러블 디바이스는 ICT산업의 차세대 성장 동력으로 주목받고 있다. 중국은 웨어러블 디바이스 업계 후발주자이지만 매년 높은 성장률을 보이며 현재 세계 최대 규모로 성장하였다. 이에 본 연구는 FEA모델(Functional, Expressive, Aesthetic)을 적용하여 중국 소비자의 웨어러블 디바이스 채택요인을 확인하고자 한다. 더불어, 웨어러블 디바이스의 채택요인이 제품의 만족, 브랜드 충성도와 브랜드 내 다른 상품에 대한 구매의도에 미치는 영향에 관해 실증적으로 분석한다. 본 연구는 실증적 분석을 위하여 중국 내 소비자 208명을 대상으로 총 5일간 온라인 설문조사를 통해 자료를 수집하였다. 분석 결과, 웨어러블 디바이스의 호환성, 유희적 동기, 하위문화적 매력요인이 채택요인으로 확인되고 웨어러블 디바이스에 대한 만족은 해당 브랜드의 충성도에 긍정적인 영향을 미치는 것으로 나타났다. 본 연구의 결과는 웨어러블 디바이스에 대한 중국 소비자의 인식과 평가를 이해하는데 학문적 시사점을 제공하고 나아가 효과적인 커뮤니케이션 전략 수립에 실무적 통찰을 제공한다. With the advancement of network technology, wearable devices have drawn the attention as the next generation growth engine of ICT industry. China, although a follower in this industry, has recorded high growth rate over the several years and become the world's largest market. This study first defined the acceptance factors of wearable devices among Chinese consumers and empirically tested the relationship between these factors and consumer performance such as product satisfaction, brand loyalty, and purchase intention of other products. We adopted FEA model for the analysis and conducted a web-based online survey. Through the Chinese consumer research panel service, we collected 208 responses and analyzed structural equation modeling with Amos 22.0. The result of the study confirmed the compatibility, hedonic motivation, and subcultural appeal as key acceptance factors. It also revealed that the satisfaction of wearable device have positive impact on the brand loyalty. Academically, this study contributes to the understanding of chinese consumers adoption behaviors toward new technology-based products. Practically, this study provides insight to design effective communication strategy for the related industry.

유방 미세석회화 조직검사에서 초음파의 유용성

김효진(Kim Hyo-Jin) 대한초음파의료영상학회 2021 대한초음파의료영상학회 학술대회 초록집 Vol.5 No.1

개요 : 유방촬영에서 보이는 석회화를 초음파로 관찰할 때 크거나 군집성으로 되어있는 경우 보일 수 있으나, 밀도가 낮은 희미한 미세석회화의 경우는 관찰하기 어려울 수 있다. 따라서 조직검사가 필요한 경우 수술적 절제 혹은 컴퓨터계측 유방촬영유도하 맘모톰 조직검사(Stereotactic Vacuum-Assisted Breast Biopsy; VABB)를 진행해야 한다. 조직검사 결과 아직 유방암이라고 명확하게 결론이 나지 않았지만 유방암과는 분명히 관련성이 있다고 보고되어지는 편평상피이형성(Flat Epithelial Atypia; FEA)은 저등급 관상피내암(DCIS)의 전구병변 혹은 위험인자로 알려지면서 최근엔 조직검사에서 FEA가 나온 경우 수술을 시행한 결과 DCIS를 포함할 진단률이 6~25%까지 보고되고 있다. Breast Cancer Res Treat 논문에 따르면 FEA로 진단될 경우 완전 절제로 최종 조직검사를 확인하라고 되어있어 수술 전 조직검사의 필요성이 요구된다. 증 례 환자 : 아르헨티나거주. 2020년 10월 last mammo, breast sono로 정기검사 받음. 6월 아르헨티나로 갈 예정. 검사기록: 2021-02-20 : ** Mammo – 1) Clustered pleomorphic microcalcifications in Rt. UOQ. -no matching nodular lesion on USG. : C4A, Low suspicion for malignancy **Breast sono – 1) A few hypoechoic nodules – Fibrocystic change or fibroadenoma. : C3, probably benign finding. Rec) FU 6- 12 months. 2021-03-30 : ** Rt magni – Grouped fine pleomorphic microcalcifications in Rt. UOQ. - no match on USG dated 2021-02-20 : C4B, moderate suspicious for malignancy Rec) Stereotactic biopsy 2021-04-07 : ** Stereotactic biopsy – 리도카인 injection 후 Rt midouter, far periphery에 위치한 병변으로 CC, LM approach 모두에서 thickness 불충분으로 리도카인 injection site 기준으로 초음파 시행. ** Diagnosis – 9 o’clock direction, right, needle biopsy; Flat epithelial atypia, Microcalcification. 결론 : 본 증례를 통하여 유방의 병변이 확인하기 어려운 위치에 있거나 유방의 두께가 불충분하여 stereotactic biopsy를 못한 경우, 리도카인 injection site를 기준으로 초음파를 통하여 의심된 타겟을 찾을 수 있었고 조직검사 결과 석회화를 확인하였다. Introduction The calcification seen in mammography may be seen when it is large or clustered by ultrasonography, but it is difficult to see in microcalcification. If buopsy is required, a surgical excision or stereotactic vacuum-assisted breast biopsy(VABB) shall be performed. Although pathology has not concluded that it is breast cancer, flat epithelial atypia(FEA) is a precursor lesion or risk factor of ductal carcinoma in-situ(DCIS), which is clearly associated with breast cancer, and 6~12% DCIS including tissue tests. According to the Breast Cancer Res Treatise, if FEA is diagnosed, the final tissue examination is to be confirmed by surgical excision, and preoperative biopsy is required. Case presentation patient : Argentina residence. 2020-10 Last mammo, Breast sono for screening. Planned to go Argentina on June. history: 2021-02-20 : ** Mammo – 1) Clustered pleomorphic microcalcifications in Rt. UOQ. -no matching nodular lesion on USG. : C4A, Low suspicion for malignancy **Breast sono – 1) A few hypoechoic nodules – Fibrocystic change or fibroadenoma. : C3, probably benign finding. Rec) FU 6- 12 months. 2021-03-30 : ** Rt magni – Grouped fine pleomorphic microcalcifications in Rt. UOQ. - no match on USG dated 2021-02-20 : C4B, moderate suspicious for malignancy Rec) Stereotactic biopsy 2021-04-07 : ** Stereotactic biopsy – The lesion located in Rt midouter, far periphery, does not thick enough breast in both CC and LM approaches. To tried ultrasound based on lidocaine injection site. ** Diagnosis – 9 o’clock direction, right, needle biopsy; Flat epithelial atypia, Microcalcification. conclusion Through this example, if stereotactic biopsy was not possible due to insufficient breast lesion position and thickness, suspicious targets could be found through ultrasound based on lidocaine injection site, and calcification was confirmed as a result of biopsy.

DOE와 FEA를 이용한 측면에어백용 Inflator 용기 설계 최적화

최진권(Jinkwon Choi),김대호(Daeho Kim),김병우(Byeongwoo Kim),최성규(Sunggyu Choi) 한국자동차공학회 2011 한국자동차공학회 부문종합 학술대회 Vol.2011 No.5

Optimizing design using DOE and FEA for inflator vessel of a side airbag was conducted in this study. ABAQUS was used for FEA and Minitab was used for optimizing design by DOE and data analysis. Experiments were designed using Full Factorial Design among Factorial Design and Central Composite Design among Response Surface Methodology. Data involved in reactive factors was obtained by Static, Dynamic Implicit, Dynamic Explicit Analysis and Query function. The results of Full Factorial Design have relatively large errors as contrasted with results of FEA. In contrast, the results of Central Composite Design have relatively small errors so those are more appropriate for optimizing design on Inflator vessel of side airbag.

A numerical simulation model of cyclic hardening behavior of AC4C-T6 for LNG cargo pump using finite element analysis

Lee, Jang Hyun,Kim, Kyung Su,Lee, Jae Beom,Yang, Yong Sik,Yoo, Mi Ji Elsevier 2009 Journal of loss prevention in the process industri Vol.22 No.6

<P><B>Abstract</B></P><P>This paper is concerned with the evaluation of cyclic hardening models within the stress–strain behavior of aluminum alloy AC4C-T6 that can be used to LNG cargo pump operating in cryogenic temperature. To insure the strength assessment of LNG cargo pump, material model of cyclic hardening and plasticity for aluminum alloy AC4C-T6 is investigated through FEA (Finite Element Analysis) with various hardening options including linear and non-linear hardening, isotropic and kinematic hardening, and combined hardening model. Monotonic tensile and cyclic tensile experiments for AC4C-T6 alloy were performed at room temperature and temperature of −165 °C. Parameters of each hardening model are obtained from the experimental data; thus five hardening models are numerically simulated thereafter. Appropriate hardening models which describe the cyclic stress–strain relationship are investigated through the simulations of cyclic hardening behavior by FEA. In order to verify the predicted behavior of cyclic hardening obtained by FEA, the results of FEA and those measured by experiments are compared.</P>

모터 다이나모를 이용한 무부하 및 부하시험 방법

배병철,이지훈,성무현,홍현정,임명섭 한국자기학회 2023 韓國磁氣學會誌 Vol.33 No.4

Motors are used in automobiles and many other applications and account for a significant portion of total power consumption. Therefore, it is important to design highly efficient motors and accurately evaluate their performance. However, the finite element analysis (FEA) used for motor design cannot fully reflect the actual test environment. Therefore, it is necessary to validate the design by comparing the FEA and test data through motor testing at the final stage of motor design. Among various motor test methods, in this paper, a 15 [kW] dynamo is used to reach the measured operating point through speed control of the load motor and current control of the test motor. The back electromotive force obtained from the no-load test of motor was measured and compared to the back electromotive force constant and torque constant values calculated from the FEA. These constants allowed the torque to be predicted without performing complex load tests of motor. Mechanical losses can be calculated by separating iron losses and permanent magnet (PM) eddy current losses from the no-load losses obtained from the no-load test. The mechanical losses are reflected in the FEA results and compared with the test results to accurately evaluate the performance of the motor design.