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베이지안 기법에 기반한 수명자료 분석에 관한 문헌 연구
원동연(Dong-Yeon Won),임준형(Jun Hyoung Lim),심현수(Hyun Su Sim),성시일(Si-il Sung),임헌상(Heonsang Lim),김용수(Yong Soo Kim) 한국신뢰성학회 2017 신뢰성응용연구 Vol.17 No.3
Purpose: The purpose of this study is to arrange the life data analysis literatures based on the Bayesian method quantitatively and provide it as tables. Methods: The Bayesian method produces a more accurate estimates of other traditional methods in a small sample size, and it requires specific algorithm and prior information. Based on these three characteristics of the Bayesian method, the criteria for classifying the literature were taken into account. Results: In many studies, there are comparisons of estimation methods for the Bayesian method and maximum likelihood estimation (MLE), and sample size was greater than 10 and not more than 25. In probability distributions, a variety of distributions were found in addition to the distributions of Weibull commonly used in life data analysis, and MCMC and Lindley’s Approximation were used evenly. Finally, Gamma, Uniform, Jeffrey and extension of Jeffrey distributions were evenly used as prior information. Conclusion: To verify the characteristics of the Bayesian method which are more superior to other methods in a smaller sample size, studies in less than 10 samples should be carried out. Also, comparative study is required by various distributions, thereby providing guidelines necessary.
건설업 일용직 근로자를 위한 비대면 구인/구직 플랫폼 ‘인력거’
원동연(Dong Yeon Won),정선우(Sun Woo Jeong),전소연(So Yeon Jeon),김영진(Yeong Jin Kim),김지심(Ji Sim Kim),안유정(You Jung Ahn),김경아(Kyong Ah Kim) 한국컴퓨터정보학회 2021 한국컴퓨터정보학회 학술발표논문집 Vol.29 No.1
이른 새벽, 건설업 일용직 근로자들은 '오늘 일을 할 수 있을까?'란 불안감과 COVID-19의 감염 위험을 안고 인력사무소에 출근한다. 새벽 건설업 시장은 높은 업무 강도와 비효율적인 구인/구직 프로세스로 인해 진입장벽이 높고, 건설기능인력의 고령화로 불법체류 근로자 고용 등의 난항을 겪고 있다. 이에 따라 본 연구에서는 건설업 시장의 구인/구직 정보를 제공하여 앱 내에서 근로자 채용을 가능하게 하고, 외부 API를 사용하여 출퇴근 관리, 안전 이수증 촬영을 통한 인증 등 근로자와 구인자를 위한 비대면 구인/구직 앱 '인력거'를 개발하였다. ‘인력거’ 앱을 통해 간소화된 구인/구직 프로세스 등을 통해 건설업에서 청년 일자리 증대가 기대된다.
최소수리 블록교체 모형을 활용한 상태기반 보전 정책 연구
임준형,원동연,심현수,박철홍,고관주,강준규,김용수,Lim, Jun Hyoung,Won, Dong-Yeon,Sim, Hyun Su,Park, Cheol Hong,Koh, Kwan-Ju,Kang, Jun-Gyu,Kim, Yong Soo 한국신뢰성학회 2018 신뢰성응용연구 Vol.18 No.2
Purpose: This study proposes a process for evaluating the preventive maintenance policy for a system with degradation characteristics and for calculating the appropriate preventive maintenance cycle using time- and condition-based maintenance. Methods: First, the collected data is divided into the maintenance history lifetime and degradation lifetime, and analysis datasets are extracted through preprocessing. Particle filter algorithm is used to estimate the degradation lifetime from analysis datasets and prior information is obtained using LSE. The suitability and cost of the existing preventive maintenance policy are each evaluated based on the degradation lifetime and by using a minimum repair block replacement model of time-based maintenance. Results: The process is applied to the degradation of the reverse osmosis (RO) membrane in a seawater reverse osmosis (SWRO) plant to evaluate the existing preventive maintenance policy. Conclusion: This method can be used for facilities or systems that undergo degradation, which can be evaluated in terms of cost and time. The method is expected to be used in decision-making for devising the optimal preventive maintenance policy.
Y-Ba-Cu-O계에서 $Y_1Ba_2Cu_3O_{7-\delta}$상의 성장에 미치는 $SnO_2$의 효과
임대호,송명엽,원동연,홍계원,Im, Dae-Ho,Song, Myeong-Yeop,Won, Dong-Yeon,Hong, Gye-Won 한국재료학회 1994 한국재료학회지 Vol.4 No.4
Y-Ba-Cu-O 계에서 123상의 성장에 미치는 Sn의 효과를 관찰하기 위하여 Sn이 첨가된 123+Sn성형체와 Sn이 첨가되지 않은 123성형체와의 couple시편을 만들었다. $1100^{\circ}C$에서 24시간 유지한 후 $970^{\circ}C$에서 1시간 유지한 시편에서 123상은 Sn이 첨가된 123+Sn 성형체의 표면에서부터 생성되어 Sn이 첨가되지 않은 123성형체 내부쪽으로 성장하였다. $1100^{\circ}C$에서 48시간 유지한 후 $970^{\circ}C$에서 1시간 유지한 시편에서는 123상이 관찰되지 않았으며 Y-Ba-Sn으로 구성된 결정립이 관찰되었다. In order to investigate the effect of $SnO_2$ on the growth of 123 phase in Y-Ba-Cu-0 system, O.1Sn-doped 123+Sn compact was coupled with Sn-free 123 compact by placing the former on the latter. In case of the coupled samples which were held at $1100^{\circ}C$ for 24hr and then at $970^{\circ}C$ for lhr, 123 phase grew from the surface of O.1Sn-doped 123+Sn compact toward the inner of Sn-free 123 compact. In case of the coupled samples which were held at $1100^{\circ}C$ for 48hr and then at $970^{\circ}C$ for lhr, it was not the 123 phase but Ba-Y-Sn grains that were observed. Ba-Y-Sn grains with a shape of bar was composed of Ba : Y : Sn=5 : 3 : 2, approximately.
분말충진법에 의한 Ag/Bi-2223고온초전도 선재의 제조공정에 관한 연구
김우곤,이호진,원동연,홍계원,Kim, U-Gon,Lee, Ho-Jin,Won, Dong-Yeon,Hong, Gye-Won 한국재료학회 1994 한국재료학회지 Vol.4 No.4
The effects of fabrication method and condition on critical current density of Ag sheathed Bi- 2223 superconducting tapes by powder-in-tube method were studied. The highest critical current density (Jc) in the whole process was measured in the repeative heat treatment of 250 hour and mechanical deformation of 2 times. These results are suggested that the high-Tc phase at the heat treatment of 250 hour was superior and the good grain alignment at the mechanical deformation of 2 times was analyzed by XRD pattern. The highest critical current density obtained by pressing method was $1.05\times 10^4A/\textrm{cm}^2$ and $0.78\times 10^4A/\textrm{cm}^2$ in case of rolling method. The multifilamentary wires with 7 and 49 filaments were fabricated to check the applicability of pressing and rolling method for preparing multifilaments wire. The critical current density of 7 filaments tapes prepared by pressing showed $0.45 \times 10^{4}A/\textrm{cm}^2$ and $0.20 \times 10^{4}A/\textrm{cm}^2$ for 49 filaments tapes prepared by rolling. 분말충진법에 의한 Ag/Bi-2223고온초전도선재의 제조방법 및 제조조건에 따른 임계전류밀도를 조사하였다. 전체공정에서 250시간의 열처리 및 2회의 반봅가공 조건에서 임계전류밀도가 가장 높게 측정되었다. 이와 같은 결과는 250시간의 열처리에서 고온상이 크게 성장되었으며, 2회의 반복가공으로 결정입자들이 일방향으로 잘 배열되는 공정조건임을 알 수 있었다. 공정별로는 pressing방법으로 제조한 시편의 임계전류밀도가 $1.05\times 10^4A/\textrm{cm}^2$로 다른 공정에 비해 가장 높았으며, rolling 공정으로는 $0.78\times 10^4A/\textrm{cm}^2$를 갖는 선재를 제조하였다. 7개 및 49개의 세심을 갖는 다심선재를 제조하여 임계전류밀도를 조사하였다. 7개의 다심선재에서 임계전류밀도값은 pressing방법에서 $0.45 \times 10^{4}A/\textrm{cm}^2$ 였으며, 49개 다심은 rolling방법으로 $0.20 \times 10^{4}A/\textrm{cm}^2$를 갖는 선재를 제조하였다.
화학증착법에 의한 고온 초전도 Y - Ba - Cu - O 박막의 제조 조건 확립에 관한 연구
박정식,조익준,김춘영,이희균,원동연,신형식 ( Joung Shik Park,Ik Joon Cho,Chun Yeong Kim,Hee Gyoun Lee,Dong Yeon Won,Hyung Shik Shin ) 한국공업화학회 1992 공업화학 Vol.3 No.3
단결정 기판위에 증착된 고온 초전도 박막은 microelectronic 장치의 실제적인 응용을 위한 가능성을 보여주고 있다. 고온 초전도 Y-Ba-Cu-O 박막을 원료물질로서 Y(thd)_3, Ba(thd)_2,와 Cu(thd)_2의 유기금속 킬레이트를 사용하였고 단결정 MgO(100), YSZ(100), SrTiO_3(100)와 다결정 SrTiO_3 기판에 화학증착법을 통해 제조하였다. 박막의 증착두깨는 증착시간이 증가함에 따라 선형적으로 증가하였다. 단결정 MgO(100), YSZ(100), SrTiO_3(100) 기판 위에 증착한 Y-Ba-Cu-O 박막은 액체질소 비등온도(T_(C,onset)=87∼89K, T_(C,zero)=85∼86K) 이상에서 초전도성을 나타내었으나 다결정 SrTiO_3 기판은 액체질소 비등온도 이상에서 제로저항을 갖지 않았다. The superconducting thin films have shown a growing possibility for practical application in microelectronic fields in recent years. In this study, the high Tc superconducting Y-Ba-Cu-O thin films were prepared on various substrates by chemical vapor deposition method using organic metal chelates of Y(thd)_3, Ba(thd)_2, and Cu(thd)_2 as source materials. The deposition reactions were carried out on single crystalline MgO(100), YSZ(100), SrTiO_3(100), and polycrystalline SrTiO_3 substrates. Deposition thickness of thin films was linearly increased with the increase of deposition time. It turned out that the Y-Ba-Cu-O thin films on MgO(100), YSZ(100), and SrTiO_3(100) single crystal substrates showed superconductivities above liquid nitrogen temperature(T_(C,onset)=87∼89K, T_(C,zero)=85∼86K), but the one on polycrystatline SrTiO_3 substrate did not.
Superconductivity of Ce$O_2$-added Y-Ba-Cu-0 Superconductors Prepared by Partial Melt Process
김찬중,김기백,이규원,원동연,Kim, Chan-Joong,Kim, Ki-Baik,Lee, Kyu-Won,Won, Dong-Yeon Materials Research Society of Korea 1992 한국재료학회지 Vol.2 No.3
$CeO_2$를 첨가한 Y-Ba-Cu-0 초전도체를 포정반응을 포함한 준용용법으로 제조하여 미세조직과 초전도성을 관찰하였다. 첨가한 $CeO_2$는 포정반응중에 $BaCeO_3$로 변화하였으며, 이 $BaCeO_3$는 방향성 성장한 1-2-3 초전도상의 기지에 미세하게 분산된다. 초전도체의 $T_{c}$는 첨가된 $CeO_2$함량에 관계없이 90K 이상으로 매우 높았다. 이는 준용융공정을 적용함으로서 제2상물질을 초전도상으로부터 분리할 수 있었기 때문으로 사료된다. The $CeO_2$-added Y-Ba-Cu-O oxides were prepared by the partial melt process involving the peritectic reaction, liquid + 2-1-1 phase ${\rightarrow}$ 1-2-3 phase, to investigate the effect of the dopant on microstructure and superconductivity. During the peritec reaction, all the added $CeO_2$ was converted to $BaCeO_3$ particles which were finely dispersed in large 1-2-3 grains. Superconducting transition temperature($T_{c}R=0$ point) of the partial-melted samples was as high as 90K regardless of $CeO_2$ content up to 5wt%, which is owing to the separation of the second phase from the 1-2-3 superconducting phase.