복합재 블레이드의 1차원 보 모델링

이민우,배재성,이수용,이석준,전부일,Lee, Min-Woo,Bae, Jae-Sung,Lee, Soo-Yong,Lee, Seok-Joon,Jeon, Boo-Il 항공우주시스템공학회 2008 항공우주시스템공학회지 Vol.2 No.1

The three-dimensional finite element modeling of a composite rotor blade is very hard and requires much computation effort. The efficient method to model a composite beam is necessary for the dynamic and aeroelastic analyses of rotor blades. In this study, the beam modeling method of a composite rotor blade is studied using VABS. The computer program, VABS (Variational Asymptotic Beam Section Analysis), uses the variational asymptotic method to split a 3-D nonlinear elasticity problem into 2-D cross-sectional analysis and 1-D nonlinear beam problem. The VABS can produce the sectional stiffness coefficients of composite rotor blades with various cross section and initial twist/curvatures, and recover the original 3-D distribution of displacement/strain/stress fields. The results of various cross section beams show that VABS gives us the accurate results comparared to commercial codes and does not need much computation effort. It can be concluded that VABS provides the efficient method to establish the FE model of a composite rotor blade.

Ag(II)를 매개체로 사용하는 전기화학적 매개산화에 의한 NO_x 제거

이민우,박소진,이근우,최왕규,Lee, Min-Woo,Park, So-Jin,Lee, Kune-Woo,Choi, Wang-Kyu 한국방사성폐기물학회 2011 방사성폐기물학회지 Vol.9 No.3

전기화학적으로 생성되는 $Ag^{2+}$를 사용하는 MEO 공정에 의한 NO 제거에 전류밀도, $AgNO_3$ 농도, 세정 용액의 유속 및 NO-공기 혼합가스 유속이 미치는 영향을 조사하였다. 전류밀도가 증가할수록 NO의 산화 반응 속도 및 제거 효율이 증가하였으며, 0.1 M 이상의 $AgNO_3$ 농도 조건에서 ㅍ 농도가 NO의 제거 효율에 미치는 영향은 무시할 만 하였다. 세정용액의 유속이 증가할수록 NO의 제거효율은 점진적으로 증가한 반면에 NO-공기 혼합가스의 유속이 증가할수록 NO의 제거효율은 점진적으로 감소하였다. 실험 범위 내에서 도출한 최적조건을 적용한 MEO 공정 및 3 M 질산 흡수 공정을 복합적으로 적용하여 NO-공기 혼합가스를 처리하였으며, NO 및 $NO_x$의 제거 효율은 각각 95% 및 63%를 얻었다. The effects of the applied current density, the $AgNO_3$ concentration, the scrubbing liquid flow rate and the NO-air mixed gas flow rate on the NO removal efficiency were investigated by using $Ag^{2+}$ mediated electrochemical oxidation (MEO). Results showed that the NO removal efficiency increased with increasing the applied current density. The effect of the $AgNO_3$ concentration on the NO removal efficiency was negligibly small in the concentration of $AgNO_3$ above 0.1 M. When the scrubbing liquid flow rate increased, the NO removal efficiency was gradually increased. On the other hands, the NO removal efficiency decreased with increasing the NO-air mixed gas flow rate. As a result of the treatment of NO-air mixed gas by using the MEO process with the optimum operating condition and the chemical absorption process using 3 M $HNO_3$ solution as a scrubbing liquid, the removal efficiency of NO and $NO_x$ was achieved as 95% and 63%, respectively.

수변공원과 체육공원의 중요 속성

홍성권 ( Sung Kwon Hong ),이상우 ( Sang Woo1 Lee ),이민우 ( Min Woo Lee ),이상민 ( Sang Min Lee ) 한국환경복원기술학회 2007 한국환경복원기술학회지 Vol.10 No.6

무기체계 획득에서 인공지능-시스템엔지니어링 융화를 위한 최상위 수준의 AI4SE, SE4AI 구현방안

이민우,Min Woo Lee 한국시스템엔지니어링학회 2023 시스템엔지니어링학술지 Vol.19 No.2

Artificial Intelligence (AI) is a prominent topic in almost every field. In Korea, Systems Engineering (SE) procedures are applied in Defense Acquisition, and it is anticipated that SE procedures will also be applied to systems incorporating AI capabilities. This study explores the applicability of the concepts "AI4SE (AI for SE)" and "SE4AI (SE for AI)," which have been proposed in the United States, to the Korean context. The research examines the feasibility of applying these concepts, identifies necessary tasks, and proposes implementation strategies. For the AI4SE, many attempts and studies applying AI to SE Processes both Requirements & Architectures Define, System implementation & V&V, and Sustainment. It needs Explainability and Security. For the SE4AI, the Functional AI implementation level, Quality & Security of the Data-set, AI Ethics, and Review policies are needed. Furthermore, it provides perspectives on how these two concepts should ultimately converge and suggests future directions for development.

입계확산처리된 Nd-Fe-B 소결자석에서 Dy의 확산에 미치는 Cu와 Al 분말의 혼합 효과

이민우,장태석,Lee, Min Woo,Jang, Tae Suk 한국분말야금학회 2016 한국분말재료학회지 (KPMI) Vol.23 No.6

We investigate the microstructural and magnetic property changes of $DyH_2$, $Cu+DyH_2$, and $Al+DyH_2$ diffusion-treated NdFeB sintered magnets with the post annealing (PA) temperature. The coercivity of all the diffusion-treated magnets increases with increasing heat treatment temperature except at $910^{\circ}C$, where it decreases slightly. Moreover, at $880^{\circ}C$, the coercivity increases by 3.8 kOe in Cu and 4.7 kOe in Al-mixed $DyH_2$-coated magnets, whereas this increase is relatively low (3.0 kOe) in the magnet coated with only $DyH_2$. Both Cu and Al have an almost similar effect on the coercivity improvement, particularly over the heat treatment temperature range of $790-880^{\circ}C$. The diffusivity and diffusion depth of Dy increases in those magnets that are treated with Cu or Al-mixed $DyH_2$, mainly because of the comparatively easy diffusion path provided by Cu and Al owing to their solubility in the Nd-rich grain boundary phase. The formation of a highly anisotropic $(Nd,\;Dy)_2Fe_{14}B$ phase layer, which acts as the shell in the core-shell-type structure so as to prevent the reverse domain movement, is the cause of enhanced coercivity of diffusion-treated Nd-Fe-B magnets.

SoC 전원 관리를 위한 인덕터와 커패시터 내장형 100MHz DC-DC 부스트 변환기

이민우,김형중,노정진,Lee, Min-Woo,Kim, Hyoung-Joong,Roh, Jeong-Jin 대한전자공학회 2009 電子工學會論文誌-SD (Semiconductor and devices) Vol.46 No.8

본 논문은 SoC 전원 관리를 위한 고성능 DC-DC 부스트 변환기 설계에 관한 것이다. DC-DC 변환기에서 일반적으로 전하 축전용으로 사용되는 인덕터와 커패시터를 칩 안에 집적하기 위해 그 크기를 크게 감소시키고, 스위칭 주파수를 100MHz로 하였다. 고속 동작에서 전압 방식의 제어를 선택하여 신뢰성을 높였으며 적절한 주파수 보상으로 안정적인 동작 특성을 확보하였다. 설계한 DC-DC 변환기는 thick gate oxide 옵션이 포함된 0.18${\mu}m$ CMOS 표준 공정으로 제작하였다. 내부 필터 커패시터를 포함한 칩의 면적은 8.1$mm^2$ 이고, 제어기가 차지하는 면적은 1.15$mm^2$ 이다. 부하 전류 300mA 이상에 대하여 4V의 출력을 얻는 변환기의 최대 효율은 76% 이상, load regulation은 100mA의 변화에 대하여 0.012% (0.5mV) 의 특성을 갖는다. This paper presents a design of a high performance DC-DC boost converter as a power module for SOC designs. It applied to this chip that reduced inductor and capacitor for integrating on a chip, and it operates with a switching frequency of 100MHz. It has reliability and stability in high switching frequency. The controller of DC-DC boost converter is designed by voltage-mode control method and compensated properly. The designed DC-DC converter is fabricated with the 0.18${\mu}m$ standard CMOS technology with a thick-gate oxide option. The overall die size is 8.14$mm^2$, and controller size is 1.15$mm^2$. The converter has the maximum efficiency over 76% for the output voltage of 4V and load current larger 300mA. The load regulation is 0.012% (0.5mV) for the load current change of 100mA.

과루지실탕(瓜蔞枳實湯)이 흡연(吸煙)으로 인(因)한 만성호흡기질환(慢性呼吸器疾患)의 임상적(臨床的) 고찰(考察)

이민우,박동일,Lee, Min-Woo,Park, Dong-I 대한한방내과학회 1998 大韓韓方內科學會誌 Vol.19 No.1

This study involved 45 man-smoker outpatients of Han-lim oriental medical hospital from Feb. 1, 1998 to May 31, 1998. The results of this study are as follows ; 1. In sex distinction, the average age was 51.9 years with persons aged 25 to 83 years. 40's and 50's are the most as 12 persons (26.7%) respectively, and in order of the next 30's and 60's are 7 persons (15.55%) respectively, more than 71 years are 5 persons (11.10%), less than 30 years are 2 persons. 2. In occupational distinction, farmers are the most as 20 persons (44.4%), and then common desk workers are 11 persons (24.44%), fishermen are 8 persons (17.78%), the others are 6 persons (13.34%) in that order. 3. In the distinction of chief complaint, cough 39 persons (88.67 %), sputum 29 persons (64.44%), dyspnea 13 persons (28.89%), loss of appetite 7 persons (15,56%), chest pain 5 persons (11.11%) in that order 4. the effects after dosage are as follows ; favorable turn of sputum is the most 89.66%, cough 64.10%, chest pain 60%, dypsnea 53.85%, loss of appetite 28.57%. As a whole, more than 68.32% was improved. As the above, it was thought that Kwarujisiltang administration was evidently effective on a chronic disease of the respiratory organs.

하이힐을 자주 착용하는 20대 여성의 허리, 무릎, 발목 및 발가락 통증, 다리 길이 그리고 족저압과의 상관분석

이민우,정연우,Lee, Min-woo,Jeong, Yeon-woo 대한정형도수물리치료학회 2020 대한정형도수물리치료학회지 Vol.26 No.2

Background: The purpose of this study is to examine the correlation between high heels and body imbalance among female college students in their twenties who mainly wear high heels and prevent associated problems. Methods: The subjects included 89 female college students in their twenties. They were measured in plantar pressure with a gait analyzer. Their legs were measured in length with a tape measure. Their pain intensity and pain frequency were measured in visual analog scale and in pain rating score. Results: There were statistically positive correlations between right leg length and low back pain frequency (p<.05) and negative correlations between the left hindfoot and low back pain frequency (p<.05). There were statistically positive correlations between right leg length and knee pain frequency (p<.05) and positive correlations between the ankle pain intensity and right leg length (p<.05). Conclusion: The stronger the pain was in the ankle, the stronger and more frequent their lumber pain was. When the pressure of the left heel was lower, the frequency of lumbar pain increased.

현삼(玄蔘)이 $SO_2$로 손상된 흰쥐의 호흡기 조직에 미치는 영향

이민우,전종철,박동일,Lee, Min-Woo,Jeon, Jong-Choul,Park, Dong-Il 대한한방내과학회 2000 大韓韓方內科學會誌 Vol.21 No.4

Objective : This experiment was performed in order to study the effects of Scrophulariae Radix on the injured tracheal tissue induced So, in rats. Methods : Healthy adult male rats weighting about 250g were divided into 4 groups - the Normal group, the Control group, the group of Scrophulariae Radix administration for 5 days after $SO_2$, gas exposure(Sample I), and the group of Scrophulariae Radix administration for 10 days before and for 5 days after $SO_2$, gas exposure(Sample II). Results : In the trachea Control group, the lesion of the ciliated epithelium was severe and the mucus secretion of the respiratory tract was increased significantly. In the trachea of Sample I group, the lesion of the ciliated epithelium and the mucus secretion of the respiratory tract were decreased compared with Control group. In the trachea of Sample II group, the lesion of the ciliated epithelium and the mucus secretion of the respiratory tract were decreased compared with Control and Sample I group. conclusions : According to the above results, Scrophulariae Radix has significant effects on the injuried tracheal tissue caused by $SO_2$ in rats.

장기폭로 시험과 철근 부식 촉진시험의 시간적 상관성에 관한 연구

이민우,박상순,Lee, Min-Woo,Park, Sang-Soon 한국건설순환자원학회 2014 한국건설순환자원학회 논문집 Vol.2 No.4

부식촉진시험의 가장 확실하고 신뢰성이 높은 방법은 해양폭로 시험장에 직접 폭로시켜 철근부식모니터링을 실시하는 방법이지만 장기간이 소요되는 단점이 있다. 그래서 이를 대체하는 수단으로 많은 연구들이 진행되어 왔다. 하지만 부식촉진시험이 폭로환경의 어느 정도 기간에 상응하느냐는 상관성에 대한 규정은 정해져 있지 않은 상황이다. 본 논문에서는 간만대, 침지내 환경을 재현한 철근부식촉진시험과 장기폭로시험을 실시하였다. 환경조건을 변수로 시험을 실시하였으며, 반전지전위법을 통한 철근부식 모니터링을 실시하였다. 부식촉진 시험결과 시험조건 별 상대부식개시시점 도출을 할 수 있었으며, 내구성 해석 프로그램인 Life365와 염화물적정시험을 통해 염화물침투해석을 실시하였다. Recent interest in the increased structural performance and durability evaluation of this concrete structure in a salt damage environment is increasing. The most secure and reliable method of accelerated corrosion test is a method to carry out the rebar corrosion monitoring can be exposed directly to the marine test site exposure. However, long-term exposure testinghas the disadvantage that a long period is necessary. So, a lot of research on RC of salt damage environment have beenpromoted as alternatives to replace this. However, accelerated corrosion test, in the short term only is appropriate and is but an accelerated test method to evaluate the critical chlorine concentration, there is a difficult problem that you still get the answer. It is one of the correlation problems accelerated test correspond to a certain period of exposure environment. Therefore, in this study, to clarify the differences rebar corrosion beginning, through the actual corrosion accelerated test in corrosion time and laboratory test chamber of the structure of the marine environment results in both environments, it is an object of correlation coefficient derived.