A5101580727- Wave and Wind Energy Systems
- Fluid Dynamics and Vibration Analysis
- Coastal and Marine Dynamics
- Advanced Battery Materials and Technologies
- Advancements in Battery Materials
- Ship Hydrodynamics and Maneuverability
- Engineering Applied Research
- Fluid Dynamics and Heat Transfer
- Maritime Transport Emissions and Efficiency
- Supercapacitor Materials and Fabrication
- Wind Energy Research and Development
- Laser Material Processing Techniques
- Vibration and Dynamic Analysis
- Internet of Things and Social Network Interactions
- Offshore Engineering and Technologies
- Additive Manufacturing and 3D Printing Technologies
- Advanced Battery Technologies Research
- Magnetic Bearings and Levitation Dynamics
- nanoparticles nucleation surface interactions
- Marine and Coastal Research
- Piezoelectric Actuators and Control
- Advanced Surface Polishing Techniques
- Maritime Navigation and Safety
- Earthquake and Tsunami Effects
- Nanomaterials and Printing Technologies
Hanyang University
2024
Inha University
2024
Korean Register (South Korea)
2023-2024
Korea Research Institute of Ships and Ocean Engineering
2015-2024
Korea Institute of Ocean Science and Technology
2023
Samsung (South Korea)
2020
University of Illinois Urbana-Champaign
2010-2014
Kwangwoon University
2013
Korea University
1998
We report measurements of the temperature dependence optical reflectivity, i.e., thermoreflectance dR/dT, 18 metallic elements at two laser wavelengths commonly used in ultrafast pump-probe experiments, 1.55 μm and 785 nm. The is determined using time-domain combined with power spot size comparisons between data quantitative modeling evolution surface sample. At a wavelength μm, four within this set samples, Nb, Re, Ta, V, have dR/dT comparable to or larger than 0.6×10−4 K−1. nm, highest...
Abstract The lithium deposited via the complex electrochemical heterogeneous deposition reaction (LDR) process on a foil‐based anode (LFA) forms high‐aspect‐ratio shape whenever kinetics reach its limit, threatening battery safety. Thereby, research strategy that boosts LDR is needed to construct high‐power and safe metal anode. In this study, kinetic limitations of LFA are elucidated through operando ex situ observations using in‐depth analyses. addition, ultra‐thin (≈0.5 µm) high modulus...
We study, using pump-probe optical methods with a time resolution of 1 ms, heat transfer when series water droplets impact smooth surface whose temperature exceeds the boiling point. The volume individual is ≈10 nl, between ≈0.3 and number in 3, 20, or 100. In range 100 °C < T 150 °C, our measurements transfer, residence contact surface, show that nearly all dispensed vaporizes, but more rapidly, higher temperature. At temperatures, 220 droplet shattering plays an increasingly important...
We use pump–probe thermal transport measurements and high speed imaging to study the residence time heat transfer of small (360 μm diameter) water droplets that bounce from hydrophobic surfaces whose temperature exceeds boiling point. The structure surface is a 10 nm thick fluorocarbon coating on Si substrate; substrate also patterned with micron-scale ridges using photolithography further increase contact angle. determined by high-speed constant at ≈1 ms over range our study, 110 < T 210...
Offshore wind farms on the east offshore of Korea to produce multi-GW power from floating platforms are being planned. The objectives present study develop a new TLP-type platform with 15 MW turbine for planned site and confirm feasibility TLP design under extreme typhoon environments. concept was completed installation at water depth 137 m. vertically moored highly pretensioned wire rope tendons. tendons were designed withstand conditions up 50 years. Additionally, an integrated be...
A series of experiments were carried out to investigate the performance a WEC rotor with platform motion. To achieve motion, forced motion device was installed in Ocean Engineering Basin. In this study, rotor’s examined at various phase stages between incoming waves three wave heights, and compared without PTO system. The stage where exhibited largest pitch identified, efficiencies system analyzed during stage. Without system, experienced its when rotating center positioned zero-up crossing...
We introduce a digital hologram generation of real 3D object captured by depth camera. The camera is employing time multiplexed concept for color and image acquisition in single chip sensor. information, point cloud, corresponding to the scene, extracted from taken pairs, gray texture map cloud used generate as input information. experimental results are satisfactory.
In this paper, the wave-induced motion characteristics of a floating pendulor are investigated numerically. A is movable-body-type wave energy converter. This device consists three main parts (floater, pendulum, and damping plates). order to obtain hydrodynamic coefficients exciting forces acting on bodies, higher-order boundary element method (HOBEM) using Green function applied present problems. The hinged pendulum simulated by applying penalty method. more realistic response for pendulor,...
This study conducted a numerical investigation on the non-linear motion problems between Salter duck-type rotor and large waves using CFD simulations. Regular of five different wave heights were generated. First, linear from simulation was verified by comparing it with existing experimental frequency domain analysis results. Then, series simulations performed to investigate motions rotor. In case lower height, results in good agreement However, as height increased, resonance periods each...
A numerical study was performed to investigate the applicability of linear decomposition method for hydrodynamic energy conversion an oscillating-water-column type wave converter (OWC-WEC). Hydrodynamic problems OWC chamber were decomposed into excitation and radiation with time-domain based on potential theory. finite element applied solve flow in entire fluid domain including structure. The validity examined by comparing direct interaction turbine–chamber pressure drop characteristics. In...
A power take-off (PTO) system for an oscillating water column (OWC) wave energy converter comprises a turbine-generator-power converter. In this study, only the topologies of that affect load control algorithm are compared. renewable is composed diode-dc/dc and pulse-width modulation (PWM) operating at small large capacities, respectively. However, selecting according to capacity based on characteristics converter, in which input highly fluctuating, can significantly reduce performance....
본 연구에서는 리튬이차전지의 음극활물질인 실리콘/탄소 복합소재를 제조하여 전기화학적 특성을 확인하였다. 합성물은 마그네슘의 열 환원 반응을 통해 SBA-15 (Santa Barbara Amorphous material No. 15)를 제조한 후 페놀 수지의 탄화 과정을 합성하였다. 실리콘/탄소를 음극으로 충방전, 사이클, 순환전압전류, 임피던스 테스트를 분석하였다. 실리콘에 코팅된 탄소는 전기 전도도를 향상시켜 Rct값을 235 ohm (silicon)에서 30 (실리콘/탄소)으로 낮추었고 리튬의 탈 삽입 시에 발생하는 실리콘의 팽창을 억제하여 전극을 안정화시키는 효과를 보여주었다. 사용한 리튬이차전지는 1,348 mAh/g의 용량을 나타내었고 50사이클 동안 76%의 안정성을 Silicon/carbon composites as anode materials for lithium-ion batteries were examined to find the cycle...
There has been growing interest recently in hybrid installations integrating the offshore wind farm and aquaculture as co-existence while optimizing ocean space use. The marine farms beyond coastal or sheltered areas will require mooring to ensure station-keeping of system during storms. In present work, a sub-surface longline is installed fixed at distance from foundations. designed cultivate oysters multi-compartment bags attached longlines vertically. with cultivating area 200 m ×...
실리콘의 부피팽창과 낮은 전기전도도를 개선하기 위하여 Silicon/Carbon/CNT 복합체를 제조하였다. 합성물은 SBA-15를 합성한 후, 마그네슘 열 환원 반응으로 Silicon/MgO를 제조하여 Phenolic resin과 CNT를 첨가하여 탄화하는 과정을 통해 합성하였다. 제조된 XRD, SEM, BET, EDS를 특성을 분석하였다. 본 연구에서는 충방전, 사이클, 순환전압전류, 임피던스 테스트를 CNT 첨가량에 따른 전기화학적 효과를 조사하였다. <TEX>$LiPF_6$</TEX> (EC:DMC:EMC=1 :1 vol%) 전해액에서 음극활물질을 사용하여 제조한 코인셀은 함량이 7 wt% 일 때 1,718 mAh/g으로 높은 용량을 나타내었다. 코인셀의 사이클 성능은 첨가량이 증가할수록 개선되었다. 11 wt%의 첨가한 음극은 두 번째 이후 83%의 용량 보존율을 나타냄을 알 수 있었다. composites as anode materials for...
An integrated analysis is required to evaluate the performance of control algorithms used in power take-off (PTO) systems for floating wave energy converters (FWECs). However, research on PTO based existing hydraulic device has mainly focused input generation rather than obtaining maximum through device-based electrical load control. The analyzed variables torque algorithm (TCA); however, amount each variable changes significantly cycle excitation moments. This paper proposes a obtain by...
본 연구에서는 Salters duck 형상 로터에 대한 발전성능을 평가하고자 주파수영역해석을 수행하였다. 주파수영역해석 프로그램은 파랑그린함수를 이용한 고차경계요소법이며, 그 결과의 검증을 위하여 기존의 모형시험결과와 종동요 운동크기를 직접 비교하였다. 로터의 경우 공진 파 주기 근처에서 큰 운동성능을 보이지만, 이외의 주기에서는 상대적으로 작은 보여 평균발전량이 높지 않았다. 따라서 GM 변화에 의한 운동변화와 평균발전량을 평가하여 보았으며, 평균발전량 증가를 PTO 감쇠계수의 적용방법 검토하여 보았다. 연구결과 GM과 적절한 감쇠계수 적용으로부터 발전효율을 증가시킬 수 있었으며, 로터를 파력발전장치 설계를 위한 기초자료를 제공하였다.
본 연구에서는 Salter's duck 형상 로터에 대한 규칙파 중 종동요방향 운동성능 모형시험을 수행하였다. 모형시험에서는 로터 설치를 위한 트러스 구조 플랫폼의 부력확보를 후면 폰투운을 모사하였으며, 그 유무에 따른 운동성능특성을 조사하였다. 모형시험은 선수파 세 가지 다른 파고에서 수행되었으며, 결과들은 주파수영역 해석과 직접 비교하여 보았다. 모형시험으로부터, 폰투운에 의하여 종동요운동의 고유 파 주기가 이동함을 확인하였으며, 상대적으로 높은 파고에서는 로터의 주기보다 단주기에서 의한 종동요운동변화가 큰 것을 확인하였다. 또한 폰투운 유무와 관계없이 파고에 무차원화 된 종동요운동은 파고가 증가함에 따라 단주기로 이동하며, 크기는 감소하였다.