• Title/Summary/Keyword: MOG

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A Numerical Study on Clear-Air Turbulence Events Occurred over South Korea (한국에서 발생한 청천난류 사례들에 대한 수치연구)

  • Min, Jae-Sik;Kim, Jung-Hoon;Chun, Hye-Yeong
    • Atmosphere
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    • v.22 no.3
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    • pp.321-330
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    • 2012
  • Generation mechanisms of the three moderate-or-greater (MOG)-level clear-air turbulence (CAT) encounters over South Korea are investigated using the Weather Research and Forecasting (WRF) model. The cases are selected among the MOG-level CAT events occurred in Korea during 2002-2008 that are categorized into three different generation mechanisms (upper-level front and jet stream, anticyclonic flow, and mountain waves) in the previous study by Min et al. For the case at 0127 UTC 18 Jun 2003, strong vertical wind shear (0.025 $s^{-1}$) generates shearing instabilities below the enhanced upper-level jet core of the maximum wind speed exceeding 50 m $s^{-1}$, and it induces turbulence near the observed CAT event over mid Korea. For the case at 2330 UTC 22 Nov 2006, areas of the inertia instability represented by the negative absolute vorticity are formed in the anticyclonically sheared side of the jet stream, and turbulence is activated near the observed CAT event over southwest of Korea. For the case at 0450 UTC 16 Feb 2003, vertically propagating mountain waves locally trigger shearing instability (Ri < 0.25) near the area where the background Richardson number is sufficiently small (0.25 < Ri < 1), and it induces turbulence near the observed CAT over the Eastern mountainous region of South Korea.

An Investigation of Synoptic Condition for Clear-Air Turbulence (CAT) Events Occurred over South Korea (한국에서 발생한 청천난류 사례에서 나타나는 종관규모 대기상태에 대한 연구)

  • Min, Jae-Sik;Chun, Hye-Yeong;Kim, Jung-Hoon
    • Atmosphere
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    • v.21 no.1
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    • pp.69-83
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    • 2011
  • The synoptic condition of clear-air turbulence (CAT) events occurred over South Korea is investigated, using the Regional Data Assimilation and Prediction System (RDAPS) data obtained from the Korea Meteorological Agency (KMA) and pilot reports (PIREPs) collected by Korea Aviation Meteorological Agency (KAMA) from 1 Dec. 2003 to 30 Nov. 2008. Throughout the years, strong subtropical jet stream exists over the South Korea, and the CAT events frequently occur in the upper-level frontal zone and subtropical jet stream regions where strong vertical wind shears locate. The probability of the moderate or greater (MOG)-level turbulence occurrence is higher in wintertime than in summertime, and high probability region is shifted northward across the jet stream in wintertime. We categorize the CAT events into three types according to their generation mechanisms: i) upper-level front and jet stream, ii) anticyclonically sheared and curved flows, and iii) breaking of mountain waves. Among 240 MOG-level CAT events reported during 2003-2008, 103 cases are related to jet stream while 73 cases and 25 cases are related to the anticyclonic shear flow and breaking of mountain wave, respectively.

Material Analysis of Bosu of the Royal Seals of the Joseon Dynasty and the Korean Empire (조선 왕실과 대한제국 황실 어보 보수(寶綬)의 재료학적 분석)

  • Lee, Hyeyoun;Kim, Jooyoung;Cho, Mungyeong;Kim, Minji;Park, Daewoo;Lee, Jungmin
    • Journal of Conservation Science
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    • v.37 no.2
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    • pp.154-166
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    • 2021
  • The royal seal, in either gold or jade, is used to symbolize Joseon's royal family, and it is made up of a Bonu (a handle), Bosin (a body), Bomun (a letter inscribed on the seal), and Bosu (a string attached to the seal). The Bosu was designed to enhance the seal's dignity and facilitate convenient handling. Bosu consists of Kkeun-mog and Bangwool-sul (decorated with gilt paper), which are made of Bangwool, Bangwool-mog, and Sul. In this study, the form survey, color, material, and composition of 318 Bosu pieces from the Joseon Dynasty and Korean Empire produced from 1441 to 1928 were analyzed. As time passed, the strings on the seals became longer and thinner. Bangwool-mog disappeared from the mid-1800s, and a ring appeared at the end of the Sul. Most of the colors used were scarlet, but orange and purple were also identified. Although most of the Bosu are silk, five Bosu from the 1900s and one Bosu from the 1740s (likely replaced in the 1900s) are estimated to be rayon. The gilt paper's main chemical components used to decorate the Bangwool-sul vary according to age. Until the mid-1800s, gold (Au) was used for the Sul and Bangwool, but since the mid-1800s, gold (Au) and brass (Cu-Zn) were used for Sul and Bangwool, respectively, and then brass (Cu-Zn) was used for Sul and Bangwool. While the Bosu was a seal accessory, it can be used to identify changes in the manufacturing techniques and materials of the period.

The Representation of the Neolithic Rock Art of Bangu-dae, South Korea

  • Lee, Sang-Mog
    • The Korean Journal of Quaternary Research
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    • v.18 no.2 s.23
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    • pp.87-92
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    • 2004
  • The rock engraving of the Korea are dated by a very few direct archaeological contexts by linking their images to objects of known prehistoric date-although many of the figures are 'abstract'. This paper focuses on the rock art of Bangu-dae, located in the south-east of Korea. I try to the date of engravings from their contexts and the ways in which they can be studied.

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A Study on the Distributed Processes for Concurrent Programming (DP를 이용한 병렬 프로그래밍에 관한 연구)

  • Oh, Byeong-Kyun;Park, Chan-Jung;Shin, In-Chul;Rhee, Sang-Burm
    • Proceedings of the KIEE Conference
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    • 1987.07b
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    • pp.1129-1132
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    • 1987
  • This paper introduces distributed processes- a new language concept for concurrent programming. It is proposed for real-time applications controlled by computer network with distributed storage. These processes communicate and syschronize by means of procedure calls and guarded regions. The paper gives several examples of distributed processes.

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Closed-form solution of ECA target-tracking filter using position and velocity measurement

  • Sagong, Sung-Dae;Yoon, Yong-Ki;Hong, Sun-Mog
    • 제어로봇시스템학회:학술대회논문집
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    • 1994.10a
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    • pp.129-133
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    • 1994
  • Presented are closed-form expressions of the steady-state solution for the three-state exponentially correlated acceleration(ECA) target-tracking filter. The steady-state solution is derived based on Vaughan's approach for the case that the measurements of target position and velocity are available at discrete points in time. The solution for the ECA filter using only position measurements is obtained as a special case of the presented results.

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