• The Bulletin of The Korean Astronomical Society
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• v.46 no.1
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• pp.32.2-32.2
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• 2021

Radio relics, Mpc-size elongated diffuse radio emissions found at galaxy cluster outskirts, are known as the result of shock acceleration during the cluster merger. Theories have claimed that low Mach number shocks are too inefficient to create the observed properties of radio relics. Alternative scenarios such as fossil cosmic ray electrons (CRes) from AGNs are required to explain the observations. However, how exactly the fossil CRes from AGNs can supply the Mpc-size radio relic is still an open question. In this study, we present our recent uGMRT radio observation results of the merging galaxy cluster Abell 514. We found three remarkable AGN jet tails that may have undergone multiple reorientations and extend nearly 800 kpc. Using multi-frequency data, we have performed spectral analysis along the AGN tails and track how the tails lose or gain energy as they propagate in the intracluster medium. We will discuss whether these AGN jets can provide sufficient seed CRes to radio relics.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.2
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• pp.64.2-64.2
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• 2021

Radio relics track cosmological shocks propagating through the intracluster medium. They are among the largest and most polarised sources in the radio sky reaching polarisation fractions up to ~60%. High-resolution observations in total intensity and in polarisation show complex structures on kiloparsec scales. Nevertheless, the relation between the observed features and the underlying morphology of the magnetic field is not clear. In this work we three dimensional MHD-Lagrangian simulations to study the polarised emission produced by a shock wave that propagates through a turbulent medium that resembles the intracluster medium. We find that the synchrotron emission produced in a shocked turbulent medium can reproduce some of the observed features in radio relics. Our work confirms that radio relics can also be formed in an environment with a tangled magnetic field. We also study the effect of intrinsic Faraday Rotation and the depolarisation of the source. Finally, we show how our results depend on the angular resolution of observations.

• 한국문화재보존과학회:학술대회논문집
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• 2004.10a
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• pp.43-54
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• 2004

In the course of examining the metallic structure of Iron chisel and Iron arrowhead, a relics of the 16th or 17th of Chosun Dynasty unearthed at near Gangsun-tower, Chengpyeong temple, we collected un-eroded samples from the relics and looked into the metallic structure through mounting, grinding and polishing, and etching, while analyzing non-metallic inclusion via SEM and EDS. The research metallic structure and SEM-SDS analysis, found that Iron chisel and Iron arrowhead had been produced from sponge iron close to pure Iron made by solid low heat reducing and then increased in rate of carbon by carburizing, It also found that Iron chisel had been hardened through the repetitive process of quench hardening and heat treatment, after being increased in amount of carbon to a certain level. Up to now, there have been a number of studies in the domestic academia which were made primarily of the structure of metallic relics of three countries the period or tile era before that. Although this research was limited in type and number of the relics, it turned out to be Interesting in that it revealed the 16thor 17th century way of processing iron, even in fragments. It is thought to be fruitful that we found iron had been made even in the Chosun Dynasty from sponge iron. It is recommended that researches be made on the relics later to be excavated and originally made in $Kory\breve{o}$ or Chosun Dynasty, because they are important in history of metal technology.

• Journal of Conservation Science
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• v.38 no.2
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• pp.144-153
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• 2022

This study conducted scientific analysis and preservation treatment for the local 7 relics (depurator bottle, eagle patten button, rank insignia, mess tin, M1 Grand-gun cleaning tool kit, Carbine bullet, cartridge) of the fallen of Korean War excavated through the MND Agency for KIA Recovery & Identification that are possessed in the exhibition hall of the Ground Operations Command. FT-IR analysis results show that remainder of depurator bottle is assumed to play a role of water and food purifier during the war for its spectrum similar to Trisodium phosphate, and inscription carved on the cartridge that is hard to observe with naked eyes was also confirmed through 3D digital shooting method. This study also established directivity of preservation treatment of relics for stable treatment by carrying out a survey of conditions based on the microscope and visual observation. The result is expected to be used as basic data for establishment of future directivity of preservation treatment for a variety of war relics.

• 보존과학연구
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• s.8
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• pp.13-34
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• 1987

A large number of metallic relics were excavated by a team of Kyungsang University museum (Nov. 25, 1985 - Jan. 29, 1986) from the groups of tombs located at No. 9 Mountain,Okchun Village, Sungsan-Ri, Ssangchak-Myon, Hyopchun-Kun, Kyungsangnam-Do which are believed to date back to Kaya period. The Research Institute of Cultural Properties was in charge performing scientific conservation and restoration for the iron cuirass and horse halmet (for one year and seven months, Feb. '86 - Sep. '87)The scientific processing for them are as follows :1. Taken Photo and record the actual conditions prior to conservation.2. Taken radiography3. Elimate Goethite ($\alpha$-FeOOH) layer on the surface using Air-brasive, remaining Magnetite ($Fe_3O_4$) layer.4. Treat to dechlorinize with 3% Sodium-Sesquicarbonate5. Protected the relics with Ruscoat acryl resin using vacuum infiltration method.6. Joint the sherd using Araldite and Microballoon mixture.7. Restored missing parts by Araldite SV 427 and HV 4278. Made record and taken photo after restoration Several hundred of sherds of relics, small or large, were restored by assortment which this method for the purpose of contributing to the further study of ancient Kaya history.* Conservator, National Research Institute of Cultural Properties.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.2
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• pp.30.1-30.1
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• 2015

Radio relics are diffuse radio sources found in the outskirts of galaxy clusters and they are thought to trace synchrotron-emitting relativistic electrons accelerated at shocks. We explore a diffusive shock acceleration (DSA) model for radio relics in which a spherical shock with the parameters relevant for the Sausage radio relic in cluster CIZA J2242.8+5301 impinges on a magnetized cloud containing fossil relativistic electrons. This model is expected to explain some observed characteristics of giant radio relics such as the relative rareness, uniform surface brightness along the length of thin arc-like radio structure, and spectral curvature in the integrated radio spectrum. We find that the observed surface brightness profile of the Sausage relic can be explained reasonably well by shocks with speed $u_s{\sim}3{\times}10^3km/s$ and sonic Mach number $M_s{\sim}3$. These shocks also produce curved radio spectra that steepen gradually over $(0.1-10){\nu}_{br}$ with a break frequency ${\nu}_{br}{\sim}1GHz$, if the duration of electron acceleration is ~60-80 Myr. However, the abrupt increase in the spectral index above ~1.5 GHz observed in the Sausage relic seems to indicate that additional physical processes, other than radiative losses, operate for electrons with the Lorentz factor, ${\gamma}_e$ > $10^4$.

• Journal of the Korean Society of Costume
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• v.66 no.8
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• pp.61-77
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• 2016

This study is to understand the meaning, the location, and the construction of Hyeonhun (玄纁) through the records and relics of the Chosun Dynasty. Hyeonhun means farewell gifts for the dead. Hyeonhun was very personal and was considered to be essential ritual supplies. it was newly made for not only first funeral(初葬), but also the second funeral(改葬), was individually made as well as in the couple funeral(夫婦合葬). the Hyeonhun ritual was performed while dressed in a simabok(緦麻服). The ritual started with washing of the hands(盥手) and deep bowing(再拜) twice. The Hyeonhun was placed on the lid of the inner coffin among the 3 coffins in Chosun tomb's way. The Hyeon was placed on the right side and the Hun on the left side of the lid.(玄右纁左). Hyeonhun are comprised of one, two, five of ten pieces. Most of the excavated Hyeonhun were two pieces : Hyeonhunsokbaek(玄纁束帛) consist of ten pieces, of which six were Hyeons and four were Huns. The records indicated that the materials used to make Hyeonhun was silk, but the excavated relics satin and twill, single gauze in the excavated relics advanced than the records.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.1378-1385
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• 2008

The probability of landslide hazards was predicted to natural terrain around the stone relics of Jinjeon-saji area, which is located in Yangyang, Kangwon Province. As the analysis results of field investigation, laboratory test and geology and geomorphology data, the effect factors of landslides occurrence were evaluated, and then the landslides prediction map was made up by use of prediction model considering the effect factors. The susceptibility of stone relics induced by landslides was investigated as the grading classification of occurrence probability using the landslides prediction map. In the landslides prediction map, the high probability area of landslides over 70% of occurrence probability was 3,489m3, which was 10.1% of total prediction area. If landslides are occurred at the high elevation area, the three stories stone pagoda of Jinjeon-saji (National treasure No.122) and the stone lantern of Jinjeon-saji (Treasure No.439) will be collapsed by debris flow.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.69.1-69.1
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• 2017

According to structure formation simulations, weak shocks with typical Mach number, M<3, are expected to form in merging galaxy clusters. The presence of such shocks has been indicated by X-ray and radio observations of many merging clusters. In particular, diffuse radio sources known as radio relics could be explained by synchrotron-emitting electrons accelerated via diffusive shock acceleration (Fermi I) at quasi-perpendicular shocks. Here we also consider possible roles of stochastic acceleration (Fermi II) by compressive MHD turbulence downstream of the shock. Then we explore a puzzling discrepancy that for some radio relics, the shock Mach number inferred from the radio spectral index is substantially larger than that estimated from X-ray observations. This problem could be understood, if shock surfaces associated with radio relics consist of multiple shocks with different strengths. In that case, X-ray observations tend to pick up the part of shocks with lower Mach numbers and higher kinetic energy flux, while radio emissions come preferentially from the part of shocks with higher Mach numbers and higher cosmic ray (CR) production. We also show that the Fermi I reacceleration model with preexisting fossil electrons supplemented by Fermi II acceleration due to postshock turbulence could reproduce observed profiles of radio flux densities and integrated radio spectra of two giant radio relics. This study demonstrates the CR electrons can be accelerated at collisionless shocks in galaxy clusters just like supernova remnant shock in the interstellar medium and interplanetary shocks in the solar wind.

• Journal of the Korean Society of Costume
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• v.53 no.4
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• pp.163-176
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• 2003

Waist lined Coat with Pleats excavated from Byun-su(1447-1524) Tomb in Yangpyeong were very similar in size to the costume of Haeina Temple which is the oldest YosunChollik up to now YosunChollik was popularly worn in the Yuan Dynasty of China(원) and it is presumed to be flown into Korea in that period. In China, the coat with a straight collar was called ByeonseonOh , and one with a round collar was called ByeonseonOhja in the Yuan Dynasty. The excavated relics of Haeinsa Temple are almost same as ByeonseonOh. In the Myoung Dynasty(명), the coat with a straight collar was called YoseonOhja, and one with a round collar was called Round collar YoseonOhja . The Waist lined Coat with Pleats excavated in the Byunsu Tomb is same as YoseonOhja Attendants who is low in position and doctors used to wear the coat, which was spread to diverse classes by degrees. Later, even emperors and high ranking officials used to wear it as military uniforms. It was made of silk and summer cloth. As mentioned above, 1 examined its history carefully through Chinese documents and photographic materials on relics. In addition, with the authentic records of Korea and the excavated relics of the Byun-su Tomb, 1 analyzed its components. However, the analysis was very restricted because the relics to be compared with were few.