플라즈마 조사에 의한 전기분무합성 SiO₂ 코팅층의 물접촉각 변화

김재훈,이준성,김지영,김상섭,Kim, Jae-Hun,Lee, Junseong,Kim, Ji Yeong,Kim, Sang Sub 한국재료학회 2014 한국재료학회지 Vol.24 No.11

Hydrophilic $SiO_2$ layers were obtained by the atmospheric-pressure plasma treatment. Superhydrophobic $SiO_2$ layers were first deposited by the electrospray deposition method. The electrospunable solution that was prepared based on the solgel method was sprayed on Si (100) substrates. The surface of the electrosprayed $SiO_2$ layers consisted of the agglomeration of nano-sized grains, which led to a very high roughness and revealed a very high contact angle to water droplets over $162^{\circ}$. After having been exposed to the atmospheric $Ar/O_2$ plasma, the observed superhydrophobicity of the $SiO_2$ layers were greatly changed: a dramatic variation of the water contact angle from $162^{\circ}$ to $3^{\circ}$, namely realization of superhydrophillicity. Interestingly, the surface microstructure was almost preserved. According to the XPS analysis, it is more likely that thanks to the plasma exposure, the surface of $SiO_2$ layers will be cleaned in terms of organic species that are hydrophobic-inducing, consequently leading to the hydrophilic nature observed for the plasma-exposed $SiO_2$ layers.

RFCVD 장치를 이용하여 성장한 실리콘 나노와이어의 특성

김재훈,이형주,신석승,김기영,고춘수,김현숙,황용규,이충훈,Kim, Jae-Hoon,Lee, Hyung-Joo,Shin, Seok-Seung,Kim, Ki-Young,Go, Chun-Soo,Kim, Hyun-Suk,Hwang, Yong-Gyoo,Lee, Choong-Hun 한국전기전자재료학회 2007 전기전자재료학회논문지 Vol.20 No.2

We have synthesized silicon nanowires by using RFCVD(Radio Frequency Chemical Vapor Deposition) system on Au deposited p-type Si(100) wafers, and investigated their physical and electrical properties. The silicon nanowires had been grown in the atmospheres of $H_{2},\;N_{2}\;and\;SiH_{4}$ at 10 Torr at the substrate temperatures of $700{\pm}5^{\circ}C\;and\;810{\pm}5^{\circ}C$ respectively. FE-SEM analysis revealed that diameters of the silicon nanowires are $50{\sim}60nm$ with the length of several ${\mu}m$. XRD analysis showed that the growth direction of the nanowires is Si[111]. Field emission characteristics showed that the turn-of voltages at the current of $0.01\;mA/cm^{2}$ are $10\;V/{\mu}m\;and\;8.5\;V/{\mu}m$ for the wires grown at $700{\pm}5^{\circ}C\;and\;810{\pm}5^{\circ}C$, respectively.

시간지연과 입력포화를 갖는 T-S 퍼지 카오스 시스템의 동기화

김재훈,신현석,김은태,박민용,Kim Jae-Hun,Shin Hyunseok,Kim Euntai,Park Mignon 대한전자공학회 2005 電子工學會論文誌-SC (System and control) Vol.42 No.1

본 논문에서는 시간지연과 입력포화를 갖는 카오스 시스템에 대한 퍼지 모텔 기반의 동기화 기법을 제안한다. 시간지연을 갖는 카오스 마스터 시스템과 슬레이브 시스템을 모델링하기 위해 Takagi-Sugeno(T-S) 퍼지 모델을 이용한다. 특히 슬레이브 시스템은 제어 입력이 제한되는 입력포화 특성을 갖는다고 가정한다. 선형 오차 피드백과 병렬 분상 보상(PDC) 방법에 따라 퍼지 카오스 동기화 시스템을 설계하고 동기화 오차 시스템의 국소 안정도 조건을 해석한다. 신호 전송 채널에는 시간지연이 항상 존재하므로 채널 시간지연 또한 고려한다. 입력포화와 시간지연을 갖는 퍼지 동기화 시스템의 국소 안정도에 대한 충분 조건은 Lyapunov-Krasovskii 이론을 적용하여 선형 행렬 부등식 (LMI) 문제의 해를 통해 얻어진다. 제안된 동기화 기법의 효과를 확인하기 위해서 모의 실험을 수행한다. This paper presents a fuzzy model-based approach for synchronization of time-delay chaotic system with input saturation. Time-delay chaotic drive and response system is respectively represented by Takagi-Sugeno (T-S) fuzzy model. Specially, the response system contains input saturation. Using the unidirectional linear error feedback and the parallel distributed compensation (PDC) scheme, we design fuzzy chaotic synchronization system and analyze local stability for synchronization error dynamics. Since time-delay in the transmission channel always exists, we also take it into consideration. The sufficient condition for the local stability of the fuzzy synchronization system with input saturation and time-delay is derived by applying Lyapunov-Krasovskii theory and solving linear matrix inequalities (LMI's) problem. A numerical example is given to demonstrate the validity of the proposed approach.

카본블랙에 의한 천연고무 물성치와 피로수명 변화에 대한 실험적 연구

김재훈,김영학,정현용,Kim, Jae-Hun,Kim, Yeong-Hak,Jeong, Hyeon-Yong 대한기계학회 2001 大韓機械學會論文集A Vol.25 No.11

The effects of carbon black on the material properties and the fatigue life of the carbon-black filled natural rubbers were investigated. Different kinds of carbon blacks resulted in different fatigue lives, hysteresis, and critical J-values. It was noticed that the hysteresis was inversely proportional to the difference between DBPA and CTAB, and the critical J-value was almost the same regardless of the length of a precrack. In addition, different kinds of carbon blacks resulted in different fracture morphologies, and micro-scale and macro-scale roughnesses. The critical J-value was proportional to the micro-scale roughness. and it seemed relate to the size distribution of carbon black particles. By reviewing all the experimental data. it was finally noticed that the logarithmic value of the fatigue life could be linearly expressed by a multiplication of the critical J-value and the logarithmic value of the hysteresis.

대형구조물 구동계통 실시간 시뮬레이션 모델 유도 및 연동 특성 분석에의 응용

김재훈,최영호,유웅재,유준,Kim, Jae-Hun,Choi, Young-Ho,Yoo, Woong-Jae,Lyou, Joon 한국군사과학기술학회 2000 한국군사과학기술학회지 Vol.3 No.1

A simulation model is developed to analyze the large-structure driving system and its integrated behavior in the whole weapon system. It models every component in the driving system such as mechanical and electrical characteristics, and it is programmed by simulation language in a way which strongly reflects the system's real time dynamics and reduces computation time as well. A useful parameter identification method is proposed, and it is tuned on the given physical system. The model is validated through comparing to real test, and it is applied to analysis and prediction of integrated system functions relating to the fire control system.

CFRP로 보강된 철근콘크리트 보의 휨 보강효과에 관한 실험적 연구

김재훈,박성무,강주원,신승협,Kim, Jae-Hun,Park, Sung-Moo,Kang, Joo-Won,Shin, Seung-Hyup 한국공간구조학회 2006 한국공간구조학회지 Vol.6 No.2

최근 FRP Plate를 이용한 철근콘크리트 구조물의 보수보강 방법으로 많은 연구가 수행되어 왔다. 이러한 FRP Plate로 보강된 구조물의 경우 보강재 단부의 조기탈락에 대한 문제점이 많은 연구를 통하여 지적되었다. 본 논문은 이러한 보강재 단부의 조기탈락에 대한 대안으로 CFRP Plate 외부부착공법에 있어서 단부를 보강철물을 이용하여 2차적으로 보강하는 방법 및 CFRP-Rod 표면매립공법으로 횝 보강된 철근콘크리트 보의 구조적 거동 및 휨 보강 성능을 파악하는데 그 목적이 있다. 또한 보강 방법에 따른 효과적인 휨 보강 성능을 파악하기 위하여 CFRP Plate 외부부착공법과 CFRP-Rod 표면매립공법을 실험을 통하여 이를 비교 고찰하여 휨 보강 성능효과를 알아본다. Recently, many researches have been conducted about reinforced concrete structures strengthened with FRP plates. In case of structures strengthened with FRP plates, the issue of premature debonding FRP plate has been raised through many previous researches. The purpose of this paper is what structural behavior and flexaural capacity of reinforced concrete beams which are strengthened for flexure is investigated about the using secondary ironware in the method of external bonded CFRP plate, and the method of near surface mounted CFRP-Rod. Also, in order to evaluate flexural capacity, experiments of the reinforced concrete beams with exteranl bonded CFRP plate and near surface mounted CFRP-Rod have been compared and investigated.

차세대 LCD 구현을 위한 Printable Electronics 기술 개발 동향

김재훈,이유진,Kim, Jae-Hun,Lee, Yu-Jin 한국정보디스플레이학회 2011 인포메이션 디스플레이 Vol.12 No.1

탄소섬유 보강재로 보강한 RC 보의 보강효과에 관한 실험적 연구

김재훈,박성무,강주원,Kim, Jae-Hun,Park, Sung-Moo,Kang, Joo-Won 한국공간구조학회 2005 한국공간구조학회지 Vol.5 No.4

보강방법으로 많이 사용되고 있는 CFRP Plate 접착 공법은 보강된 부재의 내력 증가에 아주 효과적이나 에폭시를 이용하여 표면 부착하는 특성상 충분한 성능을 발휘하지 못하고 보강 판의 탈락으로 파괴에 이르는 조기파괴(premature failure)의 파괴 특성을 보인다. 이러한 보강 실험체의 파괴 특성은 철근비, 콘크리트 강도, 보강재 종류, 보강길이, 접착제인 에폭시의 물성 등의 변수들에 의해 영향을 받는다. 본 연구에서는 CFRP Plate로 휨 보강된 RC 보의 구조적 거동 및 보강재 조기 탈락에 대한 보완으로 보강 CFRP-Rod를 이용한 표면매립공법의 휨 성능효과를 보기 위하여 수행된 실험결과를 비교 고찰한다. CFRP Plate 외부부착 공법을 적용한 RC 보강보의 주요 변수로는 보강재 길이, 보강위치(보의 인장면 및 측면), 단부 보강철물 유무 등의 실험변수로, CFRP-Rod는 보강재 길이를 변수로 하여 실험을 수행하였다. Bonded CFRP Plate method used murk in reinforcement method is very efficient for stress increment of reinforced members. But CFRP plate dosen't display enough its capacity and have the destruction characteristic of premature failure that reach failure by debond plate, because near-surface-bond using epoxy. Such destruction character of reinforced specimens take the influence at variables as steel reinforcement ratio, concrete strength, kind of reinforcement materials, reinforced length, property of epoxy used in binder and so on. In this study, performed experiment results are compared and considered on flexural performance of Near Surface Mounted Reinforcement used CFRP-Rod, as complement about structural behavior of RC beam reinforced flexural capacity in CFRP plate and premature failure of reinforcement material. Main variables of RC beam applied CFRP Plate external bond method are experimental variables as reinforcement length, reinforcement position (tension face and side face of beam) and existence of ironware in end parts. In case of CFRP-Rod, variable is reinforcement length.

고로슬래그 미분말을 함유한 고유동 모르터의 유동성상에 미치는 영향 요인에 관한 연구

김재훈,윤상천,지남용,Kim, Jae-Hun,Yoon, Sang-Chun,Jee, Nam-Yong 한국건축시공학회 2002 한국건축시공학회지 Vol.2 No.4

High fluid concrete unlike OPC concrete is made with various material, and the phase of fresh concrete is considerably different. In order to understand fluidity phase and mix properties of high fluid concrete, concrete is required to access as suspension structure which consists of aggregate and paste. The focus of this paper is to analyze the test results and quantify the effect of mix proportions of mortar and fineness modulus of sand on the properties of fresh mortar. The effect of water-binder ratio. sand-binder ration. contents of ggbs (by mass of total cementitious materials). and various contents of water reducing agent on the yield stress and plastic viscosity of the mix is studied. Based on the experimental results, the fellowing conclusions can be drawn: (1) The mixing time needed for high fluid mortar was approximately two times more than that of ordinary portland mortar. (2) The fluidity phase of mortar could be explained by yield stress of mix and the fluidity of mortar. (3) As the content of ggbs increased, yield stress of mortar was decreased and plastic viscosity of it was increased. (4) For the high fluid mortar, it was appeared that sand-binder ratio should be below 1.5.

일본에서 독립행정법인으로의 이동과 영구기록 관리

김재훈,Kim, Jae-Hun 한국기록학회 2004 기록학연구 Vol.0 No.9