288 Hits in 1.8 sec

Comparative study on pressure sensors for sloshing experiment

Sang-Yeob Kim, Kyong-Hwan Kim, Yonghwan Kim
2015 Ocean Engineering  
The distribution fitting applied in this study can be found in the work of Kim et al.(2010) .  ...  This sensor was applied by Kim et al. (2009) and Choi et al. (2010) . It has relatively large sensing diameter compared to the other pressure sensors.  ... 
doi:10.1016/j.oceaneng.2014.11.014 fatcat:6ggenoggb5fu5cmbcu5z5jqycu

Reeb flows without simple global surfaces of section [article]

Juno Kim, Yonghwan Kim, Otto van Koert
2022 arXiv   pre-print
We construct, for any given positive integer n, Reeb flows on contact integral homology 3-spheres which do not admit global surfaces of section with fewer than n boundary components. We use a connected sum operation for open books to construct such systems. We prove that this property is stable with respect to C^4+ϵ-small perturbations of the Hamiltonian given on the symplectization.
arXiv:2104.03728v2 fatcat:476yuswos5d55hvdlaqmwjmwru

Comparative study on model-scale sloshing tests

Sang-Yeob Kim, Kyong-Hwan Kim, Yonghwan Kim
2011 Journal of Marine Science and Technology  
This paper considers a comparative study on model-scale sloshing tests. There are two primary scopes of this study: comparison of sloshing pressure measured in 1/50-scale model tests at SNU with (i) the data measured at other facility for the same model, and (ii) the data measured at a smaller scaled model. For the comparative study, model tanks are excited with same irregular motions with Froude scale, and sloshing pressure signals are measured at the same locations. The statistical quantities
more » ... of 1/50-scale model tests are compared with those of other facility and 1/70-scale model tests. The differences on the statistical results are observed and discussed. KEY WORDS: Sloshing experiment; impact pressure, scale effect, comparative study.
doi:10.1007/s00773-011-0144-z fatcat:6kqqti6khvfsfjuyer2wbivhs4

Temporal Variation Dominates in Local Carabid Beetle Communities in Korean Mountains

Yonghwan Park, Taewoong Jang, Jongkuk Kim, Su-Kyung Kim, Il-Kwon Kim, Chang-Jun Kim, Yasuoki Takami
2021 Insects  
Spatial and temporal variation in ecological environments may result in spatial and temporal variation in communities. Temporal studies of biodiversity are essential for forecasting future changes in community structure and ecosystem function. Therefore, determining the mechanisms that drive temporal change in communities remains an important and interesting challenge in ecology. We quantified spatial and temporal variations in carabid beetle communities and site-specific environmental factors
more » ... or 5 years at nine study sites on three mountains in the Baekdudaegan Mountain Range, Korea. Carabid beetle communities exhibited significant temporal variation, which was larger than spatial variations between and within mountains. Environmental factors mostly varied between sites within mountains. Community variation was only weakly associated with environmental factors at wide scales, i.e., between sites on three mountains, but was strongly associated at narrow spatial scales, i.e., between sites within one mountain. Our results indicate that temporal variation in communities occurs in response to variations in the local climate, and that the patterns of temporal variation differ between mountains. Thus, temporal surveys of insect communities and climates at local scales are important for predicting temporal changes in the communities.
doi:10.3390/insects12111019 pmid:34821819 pmcid:PMC8624729 fatcat:gfddzucajrgbbmjs6s3hwq35gm

Benchmark study on motions and loads of a 6750-TEU containership

Yonghwan Kim, Jung-Hyun Kim
2016 Ocean Engineering  
impulse response function (IRF) approach. 3D BEM using a Rankine source is preferred in a time domain such as SWAN (Nakos and Sclavounos, 1990; Kring, 1994) , LAMP (Lin and Yue, 1991) , and WISH (Kim  ...  of a rigid body. most practical method to date might be a combination of 3D BEM, 3D finite element method (FEM), and a 2D slamming model, which are coupled with each other via eigenvectors of 3D FEM (Kim  ... 
doi:10.1016/j.oceaneng.2016.04.015 fatcat:czwitht4ubas5gemwv3m3bfhei

Numerical analysis on springing and whipping using fully-coupled FSI models

Jung-Hyun Kim, Yonghwan Kim
2014 Ocean Engineering  
The details follow the works of Kim et al. (2009a Kim et al. ( , 2009b Kim et al. ( , 2009c .  ...  et al., 2009a (Kim et al., , 2009b (Kim et al., , 2009c .  ... 
doi:10.1016/j.oceaneng.2014.08.001 fatcat:vi357jgotzf3xefme2dfqfwmje

Corn Silk Extract Prevents Carrageenan-Induced Inflammatory Edema

Yonghwan Kim, Han Na Choi, Taehee Kim, Su Jin Kim, Yuna Kim, Jin Soo Kim, Sang-Hoon Lee, Young-Tae Goo, Dong Woon Kim, Sang Do Lee
2022 Food Supplements and Biomaterials for Health  
Corn silk extract (CSE) has been used as a traditional medicine for edema, cystitis, gout, kidney stones, nephritis, and prostatitis. Although CSE has been shown to be effective against oxidative stress and diabetes, the effects of CSE on peripheral edema are unclear. Therefore, in this study, the effects of CSE on carrageenan-induced peripheral edema were investigated. CSE administered orally for a week suppressed the formation of edema and inhibited the swelling of epidermis and the
more » ... on of inflammatory cells into the dermis. To explore the mechanism of the anti-inflammatory action, CSE was tested on the adhesion between monocytes and endothelial cells using THP-1 cells and human umbilical vein endothelial cells (HUVECs). CSE was observed to inhibit the adhesion but only when THP-1 cells were treated with CSE but not HUVECs. This finding suggests that CSE possibly influences the expressions of the membrane proteins of the monocyte involved in the adhesion with endothelial cells. Thus, CSE was treated for 24 hours and the expressions of CD11a, CD11b, CD18, CD49d and CD162 using its respective antibody and flowcytometry. Of these proteins, CD162, also known as P-selectin glycoprotein ligand-1 (PSGL-1), was shown to be reduced in its expression. PSGL-1 is known to be required for the binding of lymphocyte function-associated antigen 1 to intercellular adhesion molecules of endothelial cells. In conclusion, CSE can suppress inflammatory edema and this action is due to the inhibition of inflammatory cells to the vascular endothelium.
doi:10.52361/fsbh.2022.2.e9 fatcat:s3acx7visnfmpgbogpcshhgtva

Multi-level approach for parametric roll analysis

Taeyoung Kim, Yonghwan Kim
2011 International Journal of Naval Architecture and Ocean Engineering  
., Corresponding author: Yonghwan Kim e-mail: 2003).  ...  The details of the experimental setup and results can be found in the report of Kim and Kim (2010) , and this paper includes only the results of the parametric roll.  ... 
doi:10.2478/ijnaoe-2013-0045 fatcat:b6ivywnuuvcuph53tbsitmhgdu

LPS-induced epithelial barrier disruption via hyperactivation of CACC and ENaC

Minkyoung Kim, Sang-woo Lee, Junchul Kim, Yonghwan Shin, Fengjiao Chang, Jin Man Kim, Xin Cong, Guang-Yan Yu, Kyungpyo Park
2020 Zenodo  
American Journal of Physiology-Cell physiology supplemental figures and methods
doi:10.5281/zenodo.4383852 fatcat:xou7lwoccrfsjjzf7hkvo32ztq

Comparison of Sloshing Pressures in 2D and 3D Tanks

Yonghwan Kim, Sang-Yeob Kim, Jieung Kim, Jae-Hoon Lee
2013 International Journal of Ocean System Engineering  
Kim et al. [9] introduced two area indices to represent the simplified impulse areas of the pressure signal. Fig. 8 shows the average of the 10 largest rise impulse areas of the two tests.  ... 
doi:10.5574/ijose.2012.3.4.225 fatcat:5lgtbaskmfde3c5srtffp4dhie

Nanostructured potassium copper hexacyanoferrate-cellulose hydrogel for selective and rapid cesium adsorption

Yonghwan Kim, Yun Kon Kim, Sungjun Kim, David Harbottle, Jae W. Lee
2017 Chemical Engineering Journal  
Potassium copper hexacyanoferrate (KCuHCF) was synthesized and immobilized in a cellulose-based hydrogel made of carboxymethyl cellulose (CMC) and hydroxyethyl cellulose (HEC) for the adsorption of cesium ions in aqueous solutions. The immobilization with the cellulose-based hydrogel facilitated the dispersion of nano-sized KCuHCF particles, showing the unprecedented adsorption capacity of the composite. In Cs + removal experiments, KCuHCF-cellulose hydrogel composites (HCF-gels) exhibited
more » ... tional Cs + adsorption capacities (2.06-2.32 mmol g -1 ) which was attributed to the presence of ion-exchangeable sites (COO -Na + ) in the cellulose hydrogel. The HCF-gels also exhibited a rapid Cs + removal (90.1% removal for 0.15 mmol L -1 of Cs + in 1 h) with the uptake reaction kinetics expressed by a pseudo-second order kinetics model. Notably, the HCF-gels could adsorb Cs + selectively (>90%) in seawater containing 0.11 mmol L -1 Cs + . Such specificity with fast kinetics is due to the high ion accessibility from the inherent nature of hydrogels and the highly dispersed KCuHCF nanoparticles in the composites.
doi:10.1016/j.cej.2016.10.136 fatcat:yjzvkkgvgjctdiszqs6iciqtgi

A Low-Cost, High-Precision Vehicle Navigation System for Deep Urban Multipath Environment Using TDCP Measurements

Jungbeom Kim, Minhuck Park, Yonghwan Bae, O-Jong Kim, Donguk Kim, Bugyeom Kim, Changdon Kee
2020 Sensors  
In this study, we developed a low-cost, high-precision vehicle navigation system for deep urban multipath environments using time-differenced carrier phase (TDCP) measurements. Although many studies are being conducted to navigate autonomous vehicles using the global positioning system (GPS), it is difficult to obtain accurate navigation solutions due to multipath errors in urban environments. Low-cost GPS receivers that determine the solution based on pseudorange measurements are vulnerable to
more » ... multipath errors. We used carrier phase measurements that are more robust for multipath errors. Without correction information from reference stations, the limited information of a low-cost, single-frequency receiver makes it difficult to quickly and accurately determine integer ambiguity of carrier phase measurements. We used TDCP measurements to eliminate the need to determine integer ambiguity that is time-invariant and we combined TDCP-based GPS with an inertial navigation system to overcome deep urban multipath environments. Furthermore, we considered a cycle slip algorithm for its accuracy and a multi-constellation navigation system for its availability. The results of dynamic field tests in a deep urban area indicated that it could achieve horizontal accuracy of at the submeter level.
doi:10.3390/s20113254 pmid:32517375 fatcat:dabefoojlnh77cn54dhjm2qrci

Treatment of Light-Induced Degradation for Solar Cells in a p-PERC Solar Module via Induction Heating

Min-gwang Seok, Junhee Kim, Yonghwan Lee, Yoonkap Kim, Yangdo Kim, Soo Min Kim
2021 Energies  
In the photovoltaic industry, there is great interest in increasing the power output of solar cells to achieve grid parity and to promote the widespread use of solar cells. However, despite many developments, a phenomenon called light-induced degradation causes the efficiency of solar cells to deteriorate over time. This study proposes a treatment that can be applied to cells within solar modules. It uses a half-bridge resonance circuit to induce a magnetic field and selectively heat Al
more » ... es in the solar cells. The electrical state of a solar module was measured in real time as it was being heated, and the results were combined with a kinetics simulation using a cyclic reaction. As the temperature of the solar module increased, the time taken to reach the saturation point and the recovery time decreased. Moreover, the value of the saturation point increased. The light-induced degradation activation energy was similar to results in the existing literature, suggesting that the kinetic model was valid and applicable even when 72 cells were connected in series. This demonstrates that an entire solar module can be treated when the cells are connected in series, and in future multiple modules, could be connected in series during treatment.
doi:10.3390/en14196352 fatcat:557hml4e5rddrpo32hpqgtcvse

Experimental and numerical analyses of sloshing flows

Yonghwan Kim
2007 Journal of Engineering Mathematics  
Fig.14 shows an example of such extension introduced by Kim et al. ([7] ).  ...  This method has been introduced by LLOYD Register of shipping and also Kim ([6] ).  ... 
doi:10.1007/s10665-006-9124-4 fatcat:55covnlnrzb7pf4yxuhx5qhhza

Crack-Assisted Layer Transfer for Cost-Effective Solar Energy Conversion Devices

Soo Min Kim, Junhee Kim, Hee-eun Song, Yonghwan Lee, Jihun Oh
2020 Ceramist  
Abstracts Recently, there has been an increasing demand for environmentally friendly renewable energy as an alternative to fossil fuels. Among the renewable energy sources, electrical/chemical energy converted by solar energy is considered a realistic alternative. However, it has been difficult to spread the solar energy conversion systems due to its high-cost compare to the conventional fossil fuel based energy system. In the photovoltaic module system, the crystalline silicon substrate used
more » ... solar light-absorbing materials is accounted for ~40% of the total manufacture cost, therefore the cost-reduction of the light-absorbing materials is one of the main research topics. In this review, we introduce a crack-assisted layer transfer technology for a cost-effective silicon substrate which enables demonstration of sub 50 μm-thick silicon without material loss in the process. The crack-assisted layer transfer approach does not require expensive processing equipment and enables the production of multiple thin films from the same donor substrate. This article also presents cost-effective and efficient solar energy conversion devices such as solar cells and photoelectrochemical cells using the ultra-thin silicon
doi:10.31613/ceramist.2020.23.4.08 fatcat:3bsi5idlwzdk3nepqwo26eigc4
« Previous Showing results 1 — 15 out of 288 results