• Journal of Astronomy and Space Sciences
• /
• v.38 no.1
• /
• pp.55-63
• /
• 2021

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.

• Journal of Astronomy and Space Sciences
• /
• v.40 no.4
• /
• pp.259-266
• /
• 2023

The Standard Model (SM) does not provide an information for 26% of dark matter of the universe. In the dark sector, dark matter is supposed to be linked with the hypothetical particles called dark photons that have similar role to photons in electromagnetic interaction in the SM. Besides astronomical observation, there are studies to find dark matter candidates using accelerators. In this paper, we searched for dark photons using future electron-positron colliders, including Circular Electron Positron Collider (CEPC)/CEPC, Future Circular Collider (FCC-ee)/Innovative Detector for Electron-positron Accelerator (IDEA), and International Linear Collider (ILC)/International Large Detector (ILD). Using the parameterized response of the detector simulation of Delphes, we studied the sensitivity of a double dark photon mode at each accelerator/detector. The signal mode is double dark photon decay channel, e⁺e^- → A'A', where A' (dark photon with spin 1) decaying into a muon pair. We used MadGraph5 to generate Monte Carlo (MC) events by means of a Simplified Model. We found the dark photon mass at which the cross-sections were the highest for each accelerator to obtain the maximum number of events. In this paper we show the expected number of dark photon signal events and the detector efficiency of each accelerator. The results of this study can facilitate in the dark photon search by future electron-positron accelerators.

• Journal of Astronomy and Space Sciences
• /
• v.39 no.1
• /
• pp.1-10
• /
• 2022

The universe is thought to be filled with not only Standard Model (SM) matters but also dark matters. Dark matter is thought to play a major role in its construction. However, the identity of dark matter is as yet unknown, with various search methods from astrophysical observartion to particle collider experiments. Because of the cross-section that is a thousand times smaller than SM particles, dark matter research requires a large amount of data processing. Therefore, optimization and parallelization in High Performance Computing is required. Dark matter in hypothetical hidden sector is though to be connected to dark photons which carries forces similar to photons in electromagnetism. In the recent analysis, it was studied using the decays of a dark photon at collider experiments. Based on this, we studies double dark photon decays at lepton colliders. The signal channels are e⁺e^- → A'A' and e⁺e^- → A'A'γ where dark photon A' decays dimuon. These signal channels are based on the theory that dark photons only decay into heavily charged leptons, which can explain the muon magnetic momentum anomaly. We scanned the cross-section according to the dark photon mass in experiments. MadGraph5 was used to generate events based on a simplified model. Additionally, to get the maximum expected number of events for the double dark photon channel, the detector efficiency for several center of mass (CM) energy were studied using Delphes and MadAnalysis5 for performance comparison. The results of this study will contribute to the search for double dark photon channels at lepton colliders.

• Publications of The Korean Astronomical Society
• /
• v.7 no.1
• /
• pp.31-37
• /
• 1992

Dark matter in various size of scales is reviewed briefly. The evidence of dark matter in dwarf spheroidal galaxies is still uncertain. However there is no doubt about the existence of dark matter in larger scales. Many proposed candidates for dark matter are still speculative. Several possibilities of direct detection of dark matter are proposed.

• The Bulletin of The Korean Astronomical Society
• /
• v.44 no.2
• /
• pp.53.1-53.1
• /
• 2019

The cosmic dark sector, composed of dark energy and dark matter, might be coupled, and hence mediate a fifth-force which gives rise to distinctive cosmological signatures. I will consider an interacting dark sector, in which dark energy and dark matter are coupled via specific well-motivated coupling functions. After an overview of these coupled dark energy models, I will discuss the current model parameter constraints derived from the latest cosmological observations which probe the expansion history, and the growth of cosmic structures of our Universe. Moreover, I will demonstrate how different measurements of the Hubble constant, including the GW170817 measurement, influence the inferred constraints on the dark coupling. I will further discuss how one could put tighter constraints on such a dark sector coupling with the upcoming large-scale radio surveys.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.31 no.5 s.164
• /
• pp.801-812
• /
• 2007

In this research, 128 stimuli of same-color coloration of lipstick and clothing were evaluated to the degree of harmony in the coordination of makeup and clothing color depending on the combination of eyeshadow color, lipstick color, lipstick tone, clothing style, and clothing tone. As to the brown eyeshadow, vivid lipstick and vivid, dull clothing, dull lipstick and light, dull, dark clothing, dark lipstick and dull, dark clothing among the combinations of red lipstick and clothing, vivid lipstick and vivid, light, dark clothing, dull lipstick and light, dull, dark clothing, dark lipstick and dark, clothing among the combinations of orange lipstick and clothing were evaluated as harmonious coloration regardless of the clothing style. As to the violet eyeshadow, vivid lipstick and vivid clothing, dull lipstick and light, dark clothing, dark lipstick and dull, dark clothing among the combinations of red lipstick and clothing, vivid lipstick and vivid, dull clothing, dull lipstick and vivid, light, dull clothing, dark lipstick and vivid, dull, dark clothing among the purple lipstick and clothing were evaluated as harmonious coloration regardless of the clothing style. Thus, the degree of harmony cannot only be different according to the clothing style even in the same coloration, but also the same clothing style can be perceived to be different degree of harmony depending on how the color and tone of clothing and lipstick are coordinate.

• Journal of Information Technology Services
• /
• v.21 no.6
• /
• pp.73-89
• /
• 2022

After COVID-19, the percentage of digital consumption has soared. Meanwhile, as the online platform market grows in size and digital commerce is activated, controversy over the "dark pattern" that induces consumers to do unintended things online continues. Dark patterns are deceptive design patterns that cause consumer rights and financial damage and can result in damaging fair market competition. As a result, the need to regulate dark patterns is raised not only by overseas regulators but also in Korea, and there are growing calls for strengthening consumer protection against dark patterns, with amendments to related laws being proposed by the National Assembly. On the other hand, there is no agreed definition of dark pattern from a normative point of view, and there is a concern that even legitimate advertising marketing activities of companies may be regulated, so a review of dark pattern regulatory measures is required. In this study, dark patterns were reviewed from a normative point of view and appropriate regulatory measures were analyzed. In particular, the problem of the dark pattern can be applied in a way that the market regulates and controls itself in consideration of the characteristics of the online platform. This study reviewed the possibility of self-regulation for dart patterns and proposed the role of each subject.

• Journal of the Korean Physical Society
• /
• v.73 no.10
• /
• pp.1596-1602
• /
• 2018

We suggest that the dark matter in the universe has quantum entanglement if the dark matter is a Bose-Einstein condensation of ultra-light scalar particles. In this theory, any two regions of a galaxy are quantum entangled due to the quantum nature of the condensate. We calculate the entanglement entropy of a typical galactic halo, which turns out to be at least O(ln(M/m)), where M is the mass of the halo and m is the mass of a dark matter particle. The entanglement can be inferred from the rotation curves of the galaxy or the interference patterns of the dark matter density.

• Journal of Astronomy and Space Sciences
• /
• v.34 no.2
• /
• pp.153-159
• /
• 2017

The Standard Model of particle physics was established after discovery of the Higgs boson. However, little is known about dark matter, which has mass and constitutes approximately five times the number of standard model particles in space. The cross-section of dark matter is much smaller than that of the existing Standard Model, and the range of the predicted mass is wide, from a few eV to several PeV. Therefore, massive amounts of astronomical, accelerator, and simulation data are required to study dark matter, and efficient processing of these data is vital. Computational science, which can combine experiments, theory, and simulation, is thus necessary for dark matter research. A computational science and deep learning-based dark matter research platform is suggested for enhanced coverage and sharing of data. Such an approach can efficiently add to our existing knowledge on the mystery of dark matter.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.25 no.2
• /
• pp.149-156
• /
• 2017

Various kinds of accessories(e.g., clock, radio, automatic door locks, alarm devices, etc.) or unit components (e.g., black box, navigation system, alarm, private audio, etc.) require dark current even when the vehicle power is turned off. However, accessories or unit components can be the causes of excessive dark current generation. It results in battery discharge and the vehicle's failure to start. Therefore, immediate detection of abnormal dark current and response are very important for a successful repair job. In this paper, we can increase the maintenance efficiency by presenting a standardized diagnostic process for the measurement of the dark current and the existing problem. As a result of the absence of a system to block the dark current in a vehicle, diagnosis and repair were performed immediately by using a standardized dark current diagnostic process.