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씨호크 항공수심라이다 데이터를 활용한 연안침식 시계열 분석 - 강원도 표사계 GW36을 중심으로 -
이재빈,김지영,김가현,허현수,위광재,Lee, Jaebin,Kim, Jiyoung,Kim, Gahyun,Hur, Hyunsoo,Wie, Gwangjae 대한원격탐사학회 2022 大韓遠隔探査學會誌 Vol.38 No.6
As coastal erosion of the east coast is accelerating, the need for scientific and quantitative coastal erosion monitoring technology for a wide area increases. The traditional method for observing changes in the coast was precision monitoring based on field surveys, but it can only be applied to a small area. The airborne bathymetric Light Detection And Ranging (LiDAR) system is a technology that enables economical surveying of coastal and seabed topography in a wide area. In particular, it has the advantage of constructing topographical data for the intertidal zone, which is a major area of interest for coastal erosion monitoring. In this study, time series analysis of coastal seabed topography acquired in Aug, 2021 and Mar. 2022 on the littoral cell GW36 in Gangwon was performed using the Seahawk Airborne Bathymetric LiDAR (ABL) system. We quantitatively monitored the topographical changes by measuring the baseline length, shoreline and Digital Terrain Model (DTM) changes. Through this, the effectiveness of the ABL surveying technique was confirmed in coastal erosion monitoring.
이재빈,곽상현,김형준,박희대,김영식,Lee, Jae-Bin,Kwak, Sang-Hyon,Kim, Hyeong-Joon,Park, Hee-Dae,Kim, Young-Sik 한국재료학회 1999 한국재료학회지 Vol.9 No.12
An FBAR(Solidly Mounted Resonator) was fabricated using reflector layers which prohibit the penetration of bulk acoustic wave into substrate. The SMR consisted of top and bottom electrodes(Al films), a piezoelectric layer (ZnO film), reflector layers(W/$Si_2$ films) and Si substrate. The electrodes were deposited by dc sputtering. The piezoelectric layer and the reflector layers were deposited by rf magnetron sputtering. The control of crystallinity, microstructures and electric properties of each layer was essential for attaining the optimum FBAR characteristics. Under the best deposition conditions for FBAR devices, the ZnO films had highly c-axis preferred orientation(${\sigma}=2.17^{\circ}$), resistivity of $10^4\;{\omega}cm$, and surface roughness of 10.6 ${\AA}$. On the other hand, the surface roughness of W and $Si_2$ films was 16 ${\AA}$ and 33 ${\AA}$, respectively, and the resistivity of Al film was $5.1{\times}10^{-6}\;{\Omega}cm$. The SMR devices were fabricated by the conventional semiconductor processes. In the resonance conditions of the SMR, the series resonance frequency (fs) and the parallel resonance frequency(fp) were 1.244 GHz and 1.251 GHz, respectively and the quality factor(Q) was 1200. 본 실험에서는 반사층(reflector)을 이용한 FBAR (Film Bulk Acoustic Resonator) 즉, SMR (Solidly Mounted Resonator) 제조에 필요한 재료들의 최적 증착 조건을 설정하여, 이를 바탕으로 제조한 SMR의 특성을 보여주었다. SMR은 상하부 전극층, 압전 박막층, 반사층, 기판으로 구성된다. 상하부 전극으로 알루미늄(Al) 금속 박막을 사용하였고 압전 박막층으로 산화아연(ZnO) 박막을 사용하였다. 실리콘(Si) 기판과 하부 전극 사이에 위치하는 반사층은 5층의 이산화규소 ($Si_2$)와 텅스텐(W) 박막으로 구성되었다. 상하부 전극은 dc 스퍼터링 방법으로 증착아였으며 반사층과 압전 박막층은 rf 스퍼터링 방법으로 증착하였다. 최적 증착 조건에서 증착된 산화아연 (ZnO) 박막은 rocking curve에서 표준편차가 $2.17^{\circ}$의 우수한 c축 우선배향성, 비저항은 $10^4\;{\Omega}cm$이상, 막 표면 거칠기(rms roughness)는 10.6${\AA}$의 특성을 나타내었다. 최적 증착 조건에서 증착된 텅스텐(W)과 이산화규소($Si_2$) 박막의 특성은 박막 거칠기 (rms roughness)가 각각 16 ${\AA}$, 33 ${\AA}$을 나타내었다. 또한 증착된 알루미늄 금속 박막의 비저항은 $5.1{\times}10^{-6}\;{\Omega}cm$이었다. 반도체 기본 공정을 이용하여 면적 $250{\times}250\;{\mu}m^2$의 SMR 소자를 만들고, 네트웍 분석기로 SMR 소자의 공진 특성을 분석하였다. 공진특성은 1.244 GHz에서 직렬공진, 1.251 GHz에서 병렬공진을 나타내었다. SMR 소자의 공진특성에서 공진기의 Q값은 1200이었다.
펨토초 레이저가 조사된 나노스케일 금박막 내의 전자-포논 비평형 특성에 대한 수치해석 연구
이재빈(Jae Bin Lee),이진운(Jin Woon Lee),이성혁(Seong Hyuk Lee) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5
The present article aims to investigate numerically electron-phonon nonequilibrium characteristics of nanoscale gold films irradiated by the femtosecond pulse lasers. In particular, the influence of electron¬phonon coupling factor on micro scale energy transport between electrons and phonons is examined extensively for different film thickness and laser fluence. The well-established two-temperature model is used in estimating electron and phonon temperatures. Through the comparison of numerical predictions with experimental data, it should be noted that the electron-phonon coupling factor becomes no longer constant, indicating that the coupling between electrons and phonons should be determined by considering the ballistic and diffusive effects due to the scale difference. In addition, considerable nonequilibrium state is observed in nanoscale gold films and the present study provides the estimated melting fluence threshold for different film thicknesses and pulse durations.
이재빈 ( Jae Bin Lee ),신동환 ( Dong Hwan Shin ),이민정 ( Min Jung Lee ),김남일 ( Nam Il Kim ),이성혁 ( Seong Hyuk Lee ) 한국분무공학회 2012 한국액체미립화학회지 Vol.17 No.4
This paper reports on breakup characteristics of fuel droplet which includes metal nanoparticles. In order to develop a new injection system for nanoparticle-coated layers overcoming the conventional flame spray system, fundamental experiments were conducted to examine the interaction between a fuel droplet with nanoparticles and the external energy induced by the laser. In the experiments, this study used nickel nanoparticles whose size was under 100 nm to mix with kerosene as the fuel, and utilized a syringe pump and a metal needle to inject a fuel droplet. In particular, the Nd-YAG laser was adopted to give additional energy to the nanoparticles for evaporation of a fuel droplet containing nanoparticles. When the laser energy as 96 mJ was irradiated during the injection, it was observed that such an explosive evaporation occurred to break up a fuel droplet including nanoparticles, making the rapid increase in the ratio surface area to liquid volume. From this work, we suggest the possibility that the laser energy can be used for rapid evaporation of a fuel droplet.
소수성 표면에서 액적 응축 시 액적 성장 거동과 열전달 특성 연구
이재빈(Jae Bin Lee),최창경(Chang Kyoung Choi),이정호(Jung Ho Lee),이성혁(Seong Hyuk Lee) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11
The present study aims to experimentally examine heat transfer and the characteristics of droplet growth during dropwise condensation process on hydrophobic surfaces. For modification of surface wettability, copper surface was coated by self-assembled monolayer. Two different hydrophobic surfaces with contact angles of 148° and 124° were used with the K2 lens for capturing clear images of droplets during condensation. The surface temperature was measured by using RTD sensors. From the results, it was observed that as the droplets was growing up toward larger droplets with time, there are three distinct regimes. In the regime 1, a homogeneous pattern of small droplets (≤ 20 ㎛) covered on copper surface. During regime 2, however, it is obviously observed that coalescence is dominant among the adjacent droplets. Especially, in the regime 3, the liquid area fraction decreases rapidly because broad copper surface is exposed with coalescence between relatively large droplets. In particular, fast fall-off time appears in case of 148° contact angle because of relatively low surface energy. Moreover, it was found that the heat transfer coefficient decreased in the mixed regime where the droplet size substantially increased. This result would be useful in understanding the transient droplet growth mechanism and controlling heat/mass transfer on the surfaces.
펄스레이저 조사 시 니켈 나노입자가 포함된 연료 액적의 분열 특성
이재빈(Jae Bin Lee),신동환(Dong Hwan Shin),이민정(Min Jung Lee),김남일(Namil Kim),이성혁(Seong Hyuk Lee) 대한기계학회 2012 대한기계학회 춘추학술대회 Vol.2012 No.11
The present research is the fundamental study for developing the thermal spray technique using the nanoparticles. In this experiment, the nanoparticle-suspended fuel was used for nanoparticle feeding method. The nanoparticle-suspended fuel was mixed kerosene with the nickel nanoparticles whose size is under 100 ㎚ and the experimental apparatus were consisted with syringe pump and metal needle. At the first experiment, we checked the possibility of transporting the nanoparticles in this study. However, the additional energy source should be needed beside the flame in order to remove the not-evaporated liquid containing the nickel nanoparticles. In this study, the behavior of the single nanoparticle-suspended fuel droplet was investigated by irradiating the Nd-YAG laser. When the 106 mJ energy was induced, the case of the nanoparticle-suspended fuel droplet was broken up while it did not happen in the case of the droplet without nanoparticle. We found that when the droplet was broken up, the surface area to the volume became increased then it had the advantage for phase change of the liquid and metal nanoparticles before impacting on the target substrate.
화염 스프레이 공정에서 다양한 연료에 따른 열-유동 특성 해석
이재빈(J.B. Lee),김대윤(D.Y. Kim),이동기(D.K. Lee),이성혁(S.H. Lee) 한국전산유체공학회 2013 한국전산유체공학회 학술대회논문집 Vol.2013 No.5
The present study aims to examine the characteristics of flow with respect to various fuel conditions in the flame spray coating process. The flame spray flow is characterized by very complex phenomena including combustion, turbulent flows, and convective and radiative heat transfer. In this study, we simulated flame spray process by using a commercial computational fluid dynamics (CFD) code of FLUENT (ver. 13.0) to predict gas dynamics involving combustion, gas temperature and velocity distributions. Also, we examined the effect of type of fuel and equivalence ratio on the flame spray process. It was found that axial gas temperature increased from initial temperature to maximum temperature while flame goes to the substrate because fuel reacts additionally to oxygen in the air in radial direction.