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Arctic Primary Aerosol Production Strongly Influenced by Riverine Organic Matter
Park, Jiyeon,Dall’Osto, Manuel,Park, Kihong,Kim, Jung-Hyun,Park, Jongkwan,Park, Ki-Tae,Hwang, Chung Yeon,Jang, Gwang Il,Gim, Yeontae,Kang, Sujin,Park, Sanghun,Jin, Yong Keun,Yum, Seong Soo,Simó American Chemical Society 2019 Environmental science & technology Vol.53 No.15
<P>The sources of primary and secondary aerosols in the Arctic are still poorly known. A number of surface seawater samples-with varying degrees of Arctic riverine and sea ice influences-were used in a sea spray generation chamber to test them for their potential to produce sea spray aerosols (SSA) and cloud condensation nuclei (CCN). Our interdisciplinary data showed that both sea salt and organic matter (OM) significantly influenced the SSA production. The number concentration of SSA in the coastal samples was negatively correlated with salinity and positively correlated with a number of OM tracers, including dissolved and chromophoric organic carbon (DOC, CDOM), marine microgels and chlorophyll <I>a</I> (Chl-<I>a</I>) but not for viral and bacterial abundances; indicating that OM of riverine origin enhances primary aerosol production. When all samples were considered, transparent exopolymer particles (TEP) were found to be the best indicator correlating positively with the ratio number concentration of SSA/salinity. CCN efficiency was not observed to differ between the SSA from the various samples, despite differences in organic characteristics. It is suggested that the large amount of freshwater from river runoff have a substantial impact on primary aerosols production mechanisms, possibly affecting the cloud radiative forcing.</P> [FIG OMISSION]</BR>
Comparison of Continuous and Filter-Based Carbon Measurements at the Fresno Supersite
Park, Kihong,Chow, Judith C.,Watson, John G.,Trimble, Dana L.,Doraiswamy, Prakash,Park, Kihong,Arnott, W. Pat,Stroud, Kenneth R.,Bowers, Kenneth,Bode, Richard,Petzold, Andre,Hansen, Anthony D.A. Informa UK (TaylorFrancis) 2006 Journal of the Air & Waste Management Association Vol.56 No.4
Observational evidence for the formation of DMS-derived aerosols during Arctic phytoplankton blooms
Park, Ki-Tae,Jang, Sehyun,Lee, Kitack,Yoon, Young Jun,Kim, Min-Seob,Park, Kihong,Cho, Hee-Joo,Kang, Jung-Ho,Udisti, Roberto,Lee, Bang-Yong,Shin, Kyung-Hoon Copernicus GmbH 2017 Atmospheric chemistry and physics Vol.17 No.15
<P>Abstract. The connection between marine biogenic dimethyl sulfide (DMS) and the formation of aerosol particles in the Arctic atmosphere was evaluated by analyzing atmospheric DMS mixing ratio, aerosol particle size distribution and aerosol chemical composition data that were concurrently collected at Ny-Ålesund, Svalbard (78.5° N, 11.8° E), during April and May 2015. Measurements of aerosol sulfur (S) compounds showed distinct patterns during periods of Arctic haze (April) and phytoplankton blooms (May). Specifically, during the phytoplankton bloom period the contribution of DMS-derived SO42− to the total aerosol SO42− increased by 7-fold compared with that during the proceeding Arctic haze period, and accounted for up to 70 % of fine SO42− particles (< 2.5 µm in diameter). The results also showed that the formation of submicron SO42− aerosols was significantly associated with an increase in the atmospheric DMS mixing ratio. More importantly, two independent estimates of the formation of DMS-derived SO42− aerosols, calculated using the stable S-isotope ratio and the non-sea-salt SO42− ∕ methanesulfonic acid ratio, respectively, were in close agreement, providing compelling evidence that the contribution of biogenic DMS to the formation of aerosol particles was substantial during the Arctic phytoplankton bloom period. </P>
Development of Hardware-in-the-Loop Simulation System for Use in Design and Validation of VDC Logics
Park, Kihong,Heo, Seung-Jin Korean Society for Precision Engineering 2003 International Journal of the Korean Society of Pre Vol.4 No.3
The objective of the Vehicle Dynamics Control (VDC) system is to maintain vehicle stability under critical lateral motions, It has a good potential of becoming one of the chassis control necessities since the system can be realized with little additional cost on top of the ABS/TCS system, Developed in this research is a hardware-in-the-loop simulator for VDC with a valve control system that modulates the brake pressures at four wheels: Two VDC control logics, a simple control logic and an LQR control logic, have been developed and incorporated in the HILS system. Their performance under various driving conditions was tested in the HILS system and the results are presented.
A Study of Dark Photon at the Electron-Positron Collider Experiments Using KISTI-5 Supercomputer
Kihong Park,Kihyeon Cho 한국우주과학회 2021 Journal of Astronomy and Space Sciences Vol.38 No.1
The universe is well known to be consists of dark energy, dark matter and the standard model (SM) particles. The dark matter dominates the density of matter in the universe. The dark matter is thought to be linked with dark photon which are hypothetical hidden sector particles similar to photons in electromagnetism but potentially proposed as force carriers. Due to the extremely small cross-section of dark matter, a large amount of data is needed to be processed. Therefore, we need to optimize the central processing unit (CPU) time. In this work, using MadGraph5 as a simulation tool kit, we examined the CPU time, and cross-section of dark matter at the electron-positron collider considering three parameters including the center of mass energy, dark photon mass, and coupling constant. The signal process pertained to a dark photon, which couples only to heavy leptons. We only dealt with the case of dark photon decaying into two muons. We used the simplified model which covers dark matter particles and dark photon particles as well as the SM particles. To compare the CPU time of simulation, one or more cores of the KISTI-5 supercomputer of Nurion Knights Landing and Skylake and a local Linux machine were used. Our results can help optimize high-energy physics software through high-performance computing and enable the users to incorporate parallel processing.
A Study of Dark Photon at the Electron-Positron Collider Experiments Using KISTI-5 Supercomputer
Park, Kihong,Cho, Kihyeon The Korean Space Science Society 2021 Journal of astronomy and space sciences Vol.38 No.1
The universe is well known to be consists of dark energy, dark matter and the standard model (SM) particles. The dark matter dominates the density of matter in the universe. The dark matter is thought to be linked with dark photon which are hypothetical hidden sector particles similar to photons in electromagnetism but potentially proposed as force carriers. Due to the extremely small cross-section of dark matter, a large amount of data is needed to be processed. Therefore, we need to optimize the central processing unit (CPU) time. In this work, using MadGraph5 as a simulation tool kit, we examined the CPU time, and cross-section of dark matter at the electron-positron collider considering three parameters including the center of mass energy, dark photon mass, and coupling constant. The signal process pertained to a dark photon, which couples only to heavy leptons. We only dealt with the case of dark photon decaying into two muons. We used the simplified model which covers dark matter particles and dark photon particles as well as the SM particles. To compare the CPU time of simulation, one or more cores of the KISTI-5 supercomputer of Nurion Knights Landing and Skylake and a local Linux machine were used. Our results can help optimize high-energy physics software through high-performance computing and enable the users to incorporate parallel processing.